Abstract de Pesquisas

09/07/08

Sinus Augmentation Procedure Using Beta-Tricalcium-Phosphate: Histological Analysis of Grafted Bone at Time of Implant Placement

American Academy of Periodontology 94th Annual Meeting & Exhibition | Seattle, WA | September, 2008
Ulrike Schulze-Späte¹, Thomas Dietrich^{1, 2}, Justine Dobeck³, Rayyan Kayal¹, Adrian Time¹, Ziedonis Skobe³, Serge Dibart¹
¹Department of Periodontology and Oral Biology, Goldman School of Dental Medicine, Boston University, Boston, MA,
²University of Birmingham, UK
³The Forsyth Institute, Boston, MA

BACKGROUND: Implant placement in the edentulous maxilla often represents a clinical challenge due to insufficient bone height after crestal bone resorption. Several graft materials have been evaluated for augmenting the maxillary sinus in order to compensate for the lost vertical dimension. Allografts are readily available, there is no risk of disease transmission and they do not require a second site surgery.The aim of this study was to evaluate the development and maturation of augmented bone in the maxillary sinus using beta-tricalcium phosphate.
MATERIAL AND METHODS: Patients (n=10, female: 4/male 6, age 30-64) with the need for rehabilitation of their dentition in the posterior maxilla and no present medical contraindications were included in the study. Beta-tricalcium phosphate (SynthoGraft, Bicon, Boston, MA) mixed with the patient’s blood was implanted into the sinus cavity, which was accessed using a lateral window technique. 6-8 month post sinus elevation, bone biopsies were taken and implants were placed simultaneously. All specimens were demineralized and subjected to staining procedures (H&E, Goldner's staining, TRAP). Slides were analyzed using lightmicroscopy for total surface area, the surface area that consisted of bone and the surface area that consisted of graft material (all in mm2 and expressed as % of the total surface.). Osteoclasts were identifiedand counted as number per mm2.
RESULTS: All implants were placed achieving primary stability and restored 4 months after placement. H&E and Goldner's stainings demonstrated the presence of vital woven bone in the grafted area withonly a few remaining graft particles (total bone surface: 31.3%±15.8% at 6 month and 36.4%±5.4% at 8 month, total graft surface:13.9%± 4.7%at 6 month and 9.6%±4.8%). In addition, TRAP staining revealed presence of osteoclasts surrounding those particles (osteoclast number:1.23±0.25 per mm2 at 6 month and 1.4±0.4 per mm2 at 8 month). A lack of inflammatory reaction was noticed with the use of this graft material. During 12 month follow up, no implant failure or complications were observed.
CONCLUSIONS: Beta-tricalcium-phosphate has the advantage of exhibiting no risks of disease transmission and can be available in unlimited quantities. It is clinically easy to use, having great handling properties and appears to cause no persistent inflammatory reaction insurrounding bone. Overall this material seems to provide adequate stability at time of implant placement. Therefore, augmentation of the maxillary sinus with beta-tricalciumphosphate represents a viable option for increasing vertical bone height in the posterior maxilla prior to implant placement.

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02/28/08

Crown-Implant Ratios of 6mm Length Implants

Academy of Osseointegration 2008 Annual Meeting | Boston, MA | February, 2008
Hardeep (Bobby) Birdi, DMD ◆ John Schulte, DDS, MSD ◆ Alejandro Rodriguez-Kovacs, DDS ◆ Meghan Weed, RDH ◆ Sung-Kiang Chuang, DMD, MD
University of Minnesota School of Dentistry

INTRODUCTION: Unfavorable crown-implant ratios have not yet been established. Still, excessive crown-implant ratios have been cited in the literature as being detrimental to long term implant success. The primary aim of this study was to determine the crownimplant ratios of single implant-supported fixed restorations on 6mm length implants in a clinical practice, and to evaluate the health of these implants via mesial and distal bone levels. Additionally, the relationship between crown-implant ratio and proximal bone levels was to be evaluated.
MATERIAL AND METHODS: In this retrospective cohort study the cohort was composed of 314 patients possessing at least one single 6mm length plateau design implant supported fixed restoration which had been surgically placed between Feb 1997 and Dec 2005. A chart review was performed to acquire radiographs in which both the entire crown and implant were visible. The length of the crown and implant were measured directly from the radiographs using consistent magnification to calculate the crown-implant ratio. Also, the mesial and distal bone levels were measured using 3 times magnification and mathematically corrected for distortion. The last available radiograph was used to measure bone levels. Follow-up time was calculated from the day of implant placement, to the last available radiograph. Statistical analyses using analysis of variance mixed models were used.
RESULTS: Data from 534 single implant supported fixed restorations were tabulated and included in the study. The mean (SD) follow-up time was 15.8 (19.2) months, with a range of 0.01 to 99.2 months. The mean crown length (SD) was 13.3 (2.7) mm, with a range of 2.4 to 21.7 mm. The mean (SD) crown-implant ratio was 1.97 (0.4) and ranged from 0.36 to 3.2. The average mesial and distal bone levels (SD) measured from the final radiographs were -0.2 (0.7) mm and -0.2 (0.9) mm respectively. There was no statistically significant relationship between increasing crown-implant ratios and decreasing mesial and distal crestal bone levels around the implant with p-values of 0.94 and 0.57 respectively.
CONCLUSIONS: The results of this study suggest crown-implant ratios do not affect long term success of 6mm length implants. Also, there are no associations between crown-implant ratio and crestal bone levels.

02/28/08

Preliminary Results of the Survival of 5 x 6 mm Implants

Academy of Osseointegration 2008 Annual Meeting | Boston, MA | February, 2008
Augusto Saldarriaga, DDS • Michael R. Markiewicz, BS • John Schulte, DDS, MDS • Meghan Weed, RDH • Sung-Kiang Chuang, DMD, MD
University of Minnesota School of Dentistry

INTRODUCTION: Manufacturers of dental implants have introduced short implants for use in areas of vertical alveolar bone deficiency. The literature regarding the survival of short implants is mixed. Recent modifications in the geometric shape and surface treatments of short implants may contribute to a rate of survival comparable to their longer counterparts. The objective of this study was to determine the short term survival of a 5 x 6 mm plateau designed dental implant.
METHODS: A retrospective cohort study design was used. The cohort consisted of patients who received one or more 5 x 6 mm plateau designed implant inserted between January 2005 and August 2006 at a private practice clinic. A chart review was conducted to acquire data on patient demographics, implant location, bone density, length of time in function and/or implant failure. The primary outcome variable was implant failure. Survival time was defined as the time between the date of implant placement and last appointment or the date of implant removal for any reason. Descriptive statistics are reported.
RESULTS: The sample included 542 implants placed in 324 patients (52.8% female). Mean patient age was 56.6 + 13.1 years. All 5 x 6 mm plateau designed implants were placed using a two stage technique. 301 (56%) implants were placed in bone density three and 151 (28%) implants in bone density four. 226 (41%) were placed in the posterior maxilla and 265 (49%) in the posterior mandible. The average follow-up time the implants were in function was 13.3 + 8.4 months, range 0.1 to 30.4 months. 35 failures were recorded for a survival rate of 92.1%. 20 (57%) of the failed implants were placed in type three bone density and 13 (37%) in type four density bone. 17 (49%) of the failures were in the posterior maxilla and 11 (31%) in the posterior mandible.
CONCLUSION: The short term survival of the 5 x 6 mm plateau designed implant is encouraging. Additional observation time is necessary to establish long term survival rates.

02/28/08

Crestal Bone Level and its Association With Varying Densities of Bone

Academy of Osseointegration 2008 Annual Meeting | Boston, MA | February, 2008
Sujey Rodriguez-Lozano, DDS • John Schulte, DDS, MDS • Meghan Weed, RDH • Sung-Kiang Chuang, DMD, MD
Graduate Prosthodontics, University of Minnesota School of Dentistry

INTRODUCTION: Crestal bone levels associated with dental implants are an indication of the health or status of the implant.
PURPOSE: The purpose of this study was to evaluate crestal bone levels on plateau designed implants in various densities of bone.
METHODS: A case series study design was used. The sample was composed of patients who had single tooth implant supported restorations placed between February 1997 and August 2006 with densities of bone information available in the charts. Bone levels on the mesial and distal surfaces of the implants were established by direct measurement from the top of the implant to the radiographic position of the bone on the implant surface. Radiographs were mathematically corrected for distortion. Bone density was determined objectively by examination of the bone which collected on the flute of the reamer during preparation of the osteotomy. Type I bone was characterized by bone which had minimal blood content, type II bone by blood wetted bone in the reamer, type III bone by a partially filled reamer of blood wetted bone and type IV bone as a reamer devoid of bone. Descriptive statistics were computed and data was analyzed with analysis of variance mixed models.
RESULTS: The sample consisted of 214 patients (50.0% females), Average age of the patients was 56.6 years. 264 plateau designed implants were included in this study. 50 implants were placed in type II bone density, 117 implants were placed in type III bone density and 97 were placed in type bone IV bone density. The mean age of implants was 2.3 ± .8 years. Mesial and distal bone levels in each of the 4 types of densities was reported as: For density type II: mesial -.9 ± .6 mm and distal -.9 ± .6 mm. For density type III: mesial -.8 ± .7 mm and distal -.8 ± .9 mm. For density type IV: mesial -.8 ± .6 mm and distal -.8 ± .5 mm. Statistical testing reveals no statistically significant differences in mesial bone levels (P=0.38) and distal bone levels (P=0.79) between the three groups of bone densities.
CONCLUSIONS: This study suggests that the crestal bone loss associated with the plateau designed implant is well within guidelines established in the literature. Secondly, there is no statistically significant difference in the crestal bone levels when comparing various densities of bone. The results of the study are relevant only to the plateau design implant.

02/28/08

In Vivo Evaluation of Implant Length and Surface Physico/Chemistry Characteristics in Biomechanical Anchorage in Plateau Root Form Implants. An Experimental Study in Beagle Dogs.

Academy of Osseointegration 2008 Annual Meeting | Boston, MA | February, 2008
Granato R, Marin C, Suzuki M, Gil JN, Coelho PG

Introduction: Since the implant surface is the first part of the implant that interacts with the host, significant attention has been devoted towards increasing the biocompatibility and osseoconductivity of implant surfaces. Surface modification approaches have been successful in increasing the host response to surgical implants, resulting in higher bone-to-implant contact (BIC) and higher bone mechanical properties at early implantation times. Among surface chemistry modifications, the incorporation of Ca- and P-based bioceramic onto the implant surfaces through various manufacturing processes has been investigated throughout the last two decades. These basic and clinical investigations have shown that bioceramic coated implants presented higher degrees of osseoconductivity and attained higher degrees of biomechanical fixation at earlier implantation times compared to uncoated implants. The objective of this study was to determine the influence of implant length and surface chemistry (Alumina-blasted/acid-etched (AB/AE) vs. Nanotite (Na) bioceramic deposition) on the biomechanical fixation of plateu root form implants in a beagle dog tibia model.
Methods: 4.5x11 mm (L) and 4.5x6 mm (S) plateau root form implants of AB/AE and Na surfaces were placed bilaterally along the proximal tibia of 6 beagle dogs and remained for 2 and 4 weeks in vivo (n=9 per implant length, surface, and time in vivo).(Fig. 1 and 2) Following euthanization, the implants were torqued to interface failure at ~0.445 radians/sec.(Fig. 3 and 4) ANOVA was utilized to determine the effects of implant length, surface, and time in vivo as (independent variables) on torque to interface failure (dependent variable). One-wayANOVAwas utilized for direct comparison between groups.A95% level of significance was used.
Results: trans-surgical bone preparation showed that L implants engaged two bone corticals whereas S implants engaged one cortical. ANOVA showed that all independent variables presented a significant effect in torque to interface (Ncm) failure: Implant length (P<0.0005, S=43.75±11.02 , L=72.02±10.54 ), implant surface (P<0.0000, AB/AE=34.93±10.85 , Na=80.84±10.7 ), and time in vivo (P<0.002, 2W= 45.51±10.7 , 4W=70.27±10.85 ). One-way ANOVA showed significant differences between groups (P<0.0000, seeTable 01).
Conclusions: According to the results obtained, the Nanothickness bioceramic surface coating played a significant role on biomechanical fixation of L and S implants at both times in vivo. While ANOVA showed a significant effect of implant length on biomechanical fixation, direct comparison between groups showed that this difference was larger for Nanotite coated implants, and not significantly different for uncoated implants.

02/28/08

A Comparison of Crestal Bone Levels in Immediate Versus Delayed Loaded Implants

Academy of Osseointegration 2008 Annual Meeting | Boston, MA | February, 2008
Cary D. McNeil, DDS ■ John K. Schulte, DDS, MSD ■ Meghan Weed, RDH ■ Sung-Kiang Chuang, DMD, MD
University of Minnesota School of Dentistry

INTRODUCTION: The results of implant survival studies as they relate to immediate versus delayed loading are inconclusive. Some report greater failure rates with immediate loading and others show no difference between the two procedures. Implant failure is often associated with excessive bone loss over time. As a result, bone loss over time may be a critical measurement of implant health. The objective of this study was to determine if there were differences in crestal bone levels over time with immediately loaded plateau design implants compared with delayed loaded plateau design implants.
METHODS: A retrospective cohort study was used. The cohort consisted of patients who received a single tooth plateau designed implant, immediate or delayed loading, between January 1997 and July 2005. Digital radiographs were retrieved from patient records. Mesial and distal bone levels were measured directly on the radiographs using 3x magnification and mathematically corrected for distortion. Changes in bone levels over time were calculated by comparing levels at post-integration with the last available film. Analysis of variance mixed models adjusted for clustered effects was used to test for statistical significance between the two groups.
RESULTS: A total of 483 implants were included in this study. The initial radiographic measurement of bone levels was set at 10 months after implant placement and was followed with a mean follow-up time of 19.3 months. The mean patient age was 55.3 years and 48.9% were female. There were 204 implants which were immediately loaded and 278 implants which were delayed loaded. Mean changes in mesial and distal bone levels for the immediately loaded implants were 0.19mm ± 0.7mm and 0.27mm ± 0.7mm respectively. For the delayed loaded implants, the mean mesial and distal bone levels were 0.14mm ± 0.7mm and 0.09mm ± 0.6mm respectively. No statistically significant differences were found in crestal bone levels over time in the immediately loaded implants compared with the delayed loaded implants (mesial changes in bone levels p=0.70, distal changes in bone levels p=0.12).
CONCLUSIONS: Using bone level changes over time as a criterion to measure implant health, there was no statistically significant difference between immediate and delayed loaded plateau design implants. An increase in bone levels was recorded for both groups.

10/30/07

Changes in Crestal Bone Levels Associated with a Bacterially Sealed Screwless 1.5˚ Locking-Taper Implant to Abutment Connection

2007 ACP Annual Session | Scottsdale, Arizona | October, 2007
Sujey Rodriguez-Lozano, DDS
Graduate Prosthodontics, University of Minnesota School of Dentistry

Introduction: The microgap associated with a screw-retained implant-abutment connection is often cited as the reason for crestal bone level changes around dental implant-supported restorations. The design of the implant abutment connection may influence crestal bone loss. The purpose of this study was to evaluate crestal bone levels for 50 bacterially sealed locking-taper implants to abutment connections at 3 periods of time after implant placement.
Methods: A retrospective case series study design was used. The sample (33 patients , 50 implants) was randomly selected from patients who received immediately loaded implants between February 2002 and November 2005. The study measured and compared bone levels on the mesial and distal aspect of the implant-abutment connection at three periods of time: time 1- immediately after implant placement, time 2- at least 7 months (post-integration) after placement and time 3- most recent radiograph available but at least 14 months after placement. Descriptive statistics were use to report the results.
Results: The sample consisted of 33 patients who collectively had 50 immediately loaded implants placed. The mean age of the implants was 2.3 ± .82 years. Mean changes in bone levels on mesial (m) and distal (d) surfaces at time: (1), (2) and (3) were reported as: The mean differences for bone levels on mesial and distal surfaces between time (2) and (1) was: on the mesial, 0.3 ± 0.7 mm and on the distal, 0.4 ± 0.6 mm. The mean differences for bone levels on mesial and distal surface between time (3) and (1) was : on the mesial, 1.0 ± 2.1 mm and on the distal, 1.2 ± 2.1 mm. The mean differences for bone levels on mesial and distal surface between time (3) and (2) was : on the mesial, 0.2 ± 0.7 mm and on the distal, 0.2 ± 0.7 mm.
Conclusion: An increase in mesial and distal crestal bone levels was found during the observation period. This could suggest that the bacterially sealed screwless 1.5˚ locking-taper implant to abutment connection may have an important role in maintaining crestal bone levels around implants of this design.

03/24/07

Histomorphometry of Explanted Dental Implants

IADR | New Orleans, LA | March, 2007
J. Lemons, M. Anabtawi, P. Beck, and V. Morgan
Department of Prosthodontics, School of Dentistry University of Alabama at Birmingham

Objective: The significant success (%) and longevities of root form dental implants affords opportunities to evaluate and classify device-to-bone interfaces. These opportunities are based on a small percentage that come to revision. Histomorphometric analyses of human explants permits multiple comparisons including in vitro and laboratory in vivo study outcomes.
Methods: A clinical group (headed by VM) have removed root form implants, where indicated clinically, by Magnitudes of osseous integration from three time periods (about 2, 5 and 10 years) are shown in Figure 2 (A-C) trephine osteotomy. The implant body and bone remain in bloc and specimens were immediately fixed in 10% buffered formalin and transferred with selected records for analysis. Specimens were: macrophotographed, evaluated stereomicroscopically; oriented, embedded; prepared by Exakt® sectioning; stained; and evaluated along longitudinal mid-line thin (20-50 micrometer) sections by Bioquant® imaging for bone quality, quantity, and specific anatomical characteristics.
Results: Eighty* plateau-type design received from one source over the past 3 years. Specimens evaluated by staff and students resulted in: (1) adequate bone for 41 longitudinal section histomorphometric analyses; (2) percent bone integration from 5 to 95% that was not significantly correlated (p>0.05) with in vivo factors other than anatomical location; and (3) interfacial bone structures of a mature and osteonal-type anatomy reported previously1. These results support that dental implant-to-bone interfaces can be stable over time and function with bone remodeling leading to a functional anatomy that is characteristic of the implant design. Comparative analyses with screw-type designs of the same biomaterial are scheduled.
Conclusions: (1) en bloc explants from in vivo functional periods from 3 to 126 months showed osseointegration percentages from 5 to 95%; and (2) the bone anatomy was a mature osteonal type structure, characteristic of plateau type implant designs.

Partial student support from Bicon, Boston, MA is acknowledged.
Lemons, J, J Oral Imp, 2004 and in Davies, J. Ed., Bone Engineering, 2000.

03/24/07

Histological Analysis for forty one retrieved dental implants

IADR | New Orleans, LA | March, 2007
Muna Anabtawi, Preston Beck, Al Bartolucci, Vincent Morgan, Jack Lemons
Department of Prosthodontics, School of Dentistry University of Alabama at Birmingham

Objectives: To analyze the anatomy and osseous integration status of the hard tissue interfaces for retrieved implants, and to interpret the clinical status of this specific implant patient population through correlating bone integration status and demographical data.
Methods: Eighty dental implants removed for clinical reasons were retrieved from patients over a 3 year period. Forty one explants were selected for histological analysis because they had adequate bone for longitudinal section analyses. Specimens were processed, embedded in plastic, and thin (20-30 micrometer) ground sections were made along the long axis of the implants. Specimens were stained with Sandersons’ Bone Stain. Blinded histomorphometric analysis was performed to measure the percentage of bone area between the plateaus and the bone/implant contact (BIC). Patient records (gender, date of birth, smoking status, time in vivo, type of implant surface, presence of augmentation, and position of the implants in the jaw) were collected and incorporated into the histomorphometric data; and statistical analysis was performed.
Results: There were no strong associations between any of the clinical, patient and implant variables and the bone area percentage and (BIC). In a multiple regression analysis adjusting for the available data, the anterior position was marginally significantly associated with higher percentage of bone and (BIC) (p=0.067). Performing a simple pair wise correlation, females had higher percentage of bone than males (p=0.0898).
Conclusions: The findings support that the success and failure can be caused by a combination of factors not associated with bone integration status. Revision procedures represent a small percentage of dental implants treatment and this study demonstrates that larger numbers of specimens will be required for statistical significance amongst the variables considered.

03/22/07

Investigation of maxillary sinus bone graft healing by MicroCT

IADR | New Orleans, LA | March, 2007
P.M.C. CHOPRA¹, M. JOHNSON¹, P. BECK¹, T. NAGY¹, M. MARINCOLA², and J.E. LEMONS¹,
¹Department of Dental Biomaterials, School of Dentistry University of Alabama at Birmingham
²Rome, Italy

Objectives: A MicroCT analysis of bone healing quality and quantity subsequent to placement of a reformulated tricalcium phosphate (TCP)* in maxillary sinus ridge augmentation.
Methods: Ten(10) trephined rod shaped human bone cores were obtained from an independent source at three months after the placement of tricalcium phosphate particulate in the maxillary sinus for ridge augmentation prior to implant placement. The samples were immediately stored in 10% neutral buffered formalin. Using SCANCO 40 MicroCT machine, the samples were evaluated at resolutions of 6 and 20µm respectively. The threshold for bone and graft material was determined using visual image, intensity (grey level) and histogram analyses. The density and three dimensional micro architecture of the bone and graft material were analyzed using the software which was interactive with the investigators.
Results: The samples were investigated for micro architecture and density of the bone and graft material. Along with mineral density, the trabecular bone parameters such as Trabecular thickness (Tb Th), Trabecular separation (Tb sp), Structural Model Index (SMI), Trabecular number (Tb no), and connectivity density were obtained for each sample and analyzed ANOVA (p≤0.05). The results obtained at both resolutions (6and 20µm) were comparable, however parameters obtained at 20µm will be used in the future studies including histological, histomorphometrical and scanning electron microscopy comparisons.
Conclusions: MicroCT allowed the study of bone both quantitatively and qualitatively without destroying the samples. These results demonstrated an osteoconductive effect of TCP. The mean bone and graft volume obtained was 25.5 and .43 mm3 respectively; suggesting new bone formation and graft dissolution. These results corroborate independent reports of implants having moved to functional status without failures. The data achieved can be further used to correlate with the values obtained from the traditional histological methods.

*SynthoGraft

Partial student support from Bicon, Boston, MA is acknowledged.

09/30/06

Assessment of Periodontal Health Around Integrated Abutment Crowns

AAP Annual Meeting, San Diego, CA, September 2006.
Cheng, K.K., Chuang, S.K., Weed, M., Dibart, S.

Background: The Integrated Abutment Crown™ (IAC) (Bicon, Boston MA) is a cementless, screwless implant-supported crown made from a polyceramic material, which is 80% glass and 20% PEX resin. Unlike the porcelain fused to metal crown (PFM), the IAC restoration is fused to the abutment thus eliminating the presence of a crown/abutment microgap. The purpose of the present investigation was to compare various periodontal parameters in patients with IAC, natural teeth (NT), NT restored with PFMs, and implants restored with PFMs.
Materials & Methods: A retrospective cohort study was conducted on patients evaluated from January, 2003 to April, 2005 at the Implant Dentistry Centre – Faulkner Hospital (IDC-FH), Boston, MA. Natural teeth/implants of these patients were separated into 4 groups: Group 1 (NT), Group 2 (NT/PFMs), Group 3 (implants/PFMs) and Group 4 (implants/IACs). Periodontal parameters including modified plaque index (MPI), sulcus bleeding index (SBI), gingival index (GI), and the average of 6 probing depths (PD) from each tooth or implant (MF, F, DF, ML, L, and DL) were recorded at initial and final examinations. Linear mixed-effects models were used to evaluate the associations between the four groups (the main predictor) and clinical periodontal parameters over the follow-up time. A p-value ≤0.05 was considered statistically significant.
Results: TThe sample included 50 patients (22 males, 28 females) with a mean age of 64.2 years (range = 31.65 - 95.16 years) that were observed over a mean follow-up period of 23.07 months (range of 9.99 -26.28 months). A total number of 375 teeth/implants were divided into: Group 1 (105 NT), Group 2 (63 NT/PFMs), Group 3 (68 implants/PFMs) and Group 4 (139 implants/IACs). The mean changes in clinical periodontal parameters of each group were compared to a reference group (Group 1). Gingival index: Group 3 > 2 > 1 > 4. Average probing depth: Group 1 > 2 > 4 (p<0.05) ≈ 3 (p<0.05). (Difference between group 3 and 4 was not statistically significant.) Sulcus bleeding index: Group 4 > 2 > 1 > 3. Modified plaque index: Group 4 (p<0.05) > 2 > 1 > 3.
Conclusion: Group 4 had the most significant decrease in GI compared to the other groups and performed similarly to Group 3 in terms of probing depths. There were no statistical differences with respect to mean change of SBI among the four groups. Group 4 was found to have a significantly higher MPI score compared to Group 1. Further studies evaluating the plaque composition will be necessary in the near future to explain these findings.

09/23/06

An Innovative Immediate Stabilization Technique For Dental Implants

FDI World Dental Congress | Shenzhen, China | September, 2006
Drauseo Speratti, DDS; Meghan Weed, RDH; S.K. Chuang, DMD

Introduction: Several techniques for the immediate stabilization and functioning of dental implants have been used and described over the years. This study demonstrates how effective this procedure can be done, showing the ease with which quality aesthetic results can be achieved without any additional comprehensive laboratory procedures for the provisional phase. A screwless implant/abutment connection improves the efficiency and effectiveness of the procedures. Regular restorative procedures provide the final restoration.
Materials & Methods: The sample was compose of 505 patients who had a total of 1086 implants placed. We used a retrospective cohort study design including patients who had one or more implants placed using the technique of Immediate Stabilization or Loading between November 1999 and January 2006.
Results: The overall lifetime proportional rate was 91.61%.
Conclusion: This study demonstrates how this technique can be efficient and cost effective, allowing patients to function without the need for removable appliances during healing period, significantly reducing operative time.

06/30/06

Conditional Cox Frailty Predictions Within Clusters for Dental Implant Survival

International Association of Dental Research, Brisbane, Australia June 2006.
Chuang, S.K., Cai, T.

Objectives: The purpose of this study was to conduct conditional and joint predictions for the survival of future dental implants using subject level, implant specific covariate information, and the survival information of other implant(s) for the same subject.
Material and Methods: A retrospective cohort study design was conducted. The cohort consisted of subjects having at least one Bicon implant placed. Covariates information used included smoking status, timing of placement, and implant staging were previously identified using an innovative Cox frailty regression model that adjusted for within subject correlations and heterogeneity of implant failure risks.
Results: The cohort composed of 677 patients with 2349 implants placed. To improve the prediction accuracy, we utilized information on the survival status of existing implants along with the covariates. For illustration, we considered the joint and conditional predictions for the survival of three implants from a single subject who was a non-smoker with immediate implant placement after extraction and one stage protocol. For example, conditional on the first and second implants both surviving for 12- and 60- months given the above parameters, the estimated probability for the third implant surviving for 12- and 60- months was 88.8% (95%CI: 82.4%, 93.0%) and 81.4% (95%CI: 69.5%, 87.7%) respectively. On the other hand, conditional on the first implant surviving for 12- and 60- months, the probabilities that both the second and third implant survived 12- and 60- months were 77.7% (95%CI: 66.3%, 86.0%) and 63.1% (95%CI: 45.0%, 75.2%) respectively.
Conclusion: Conditional and joint survival predictions within subjects are challenging and commonly encountered in dental research. The application of this innovative flexible joint Cox frailty approach allows unique survival predictions about implant failure based on prior information about the survival status of other implants within the same subject.

06/29/06

Survival Analysis of Immediate Stabilization Loading of Screwless Dental Implants

IADR General Session | Brisbane, Australia | June 2006
D. Speratti¹, M. Hirayama¹, M. Weed¹, and S.-K. Chuang², ¹Implant Dentistry Centre, Boston, MA, USA, ²Harvard School of Public Health, Massachusetts General Hospital, Chestnut Hill, MA, USA

Objectives: The study's objective was to evaluate the survival rate and to identify covariates (risk factors) for failure of an innovative and efficient technique for immediate stabilization and loading of dental implants with a locking taper connection.
Methods: To address the research objective, we used a retrospective cohort study design including all patients who had one or more implants placed using the technique of immediate stabilization / loading at Implant Dentistry Centre at the Faulkner Hospital, Boston, MA between June 1999 and October 2005. Covariates for failure were grouped into the following categories: demographics, implant-specific, anatomic, prosthetic, and reconstructive categories. The outcome variable was implant failure defined as explantation. Overall implant survival was evaluated by the Kaplan-Meier analysis and risk factors by the Cox proportional hazards models adjusted for clustered failure time observations.
Results: The sample was composed of 506 patients who had a total of 1099 implants placed. The overall Kaplan-Meier survival rate at 12 and 24 months were 90.0% and 88.6% respectively. The overall lifetime success rate without follow-up time adjustment was 91.6%. Covariates associated with implant failure (p < 0.15) in the univariate analysis included: implant position, diameter, well size, length, and coating of implant. Based on the adjusted multivariate Cox model including age at implant placement and gender, covariates associated with implant failure were implant position, length, and presence of coating on the implant (p < 0.05).
Conclusions: There are many advantages with the use of immediate stabilization and loading implants. The overall one-year survival of the immediate stabilization and loading implant system was 90.0%. After controlling for other variables, implant position (posterior jaw) was associated with an increased risk for implant failure while increased implant length and presence of surface coating on the implant were associated with a decreased risk for implant failure.

10/07/05

Immediate Stabilization of Implants for General Dentists

ADA Annual Meeting | Philadelphia, PA | October, 2005
Speratti, D.

Immediate stabilization and function of dental implants has become a preferred method of treatment. Clinical research and engineering improvements have allowed clinicians to offer the treatment more frequently. Leading practitioners utilize the method of “Immediate Loading or Stabilization”. This presentation intends to show a predictable and affordable technique for general practitioners so that they may be able to achieve aesthetic results without additional surgical procedures. Clinical pictures will be presented.

08/25/05

Immediate Stabilization & Function of Dental Implants

FDI Annual Meeting | Montreal, Canada | August, 2005
Speratti. D., Hirayama, M.

Abstract: Immediate Stabilization and Function (ISF) of dental implants has become a preferred method of treatment. Clinical research, engineering improvements, and patients’ needs have allowed clinicians to offer the treatment more frequently. Leading practitioners utilize the method of “Immediate Loading or Stabilization”; however, many clinicians are still skeptical about its success.
Materials and Methods: In this on-going clinical study of 405 fin-type implants (Hydroxylapatite and Titanium Plasma Spray), 142 patients were treated from November 1998 to July 2004 by means of the ISF. All implants were immediately stabilized by fabrication of a temporary prosthesis bonded to natural dentition or splinting implants to one another.
Results: During this period of time, 128 implants successfully integrated and were restored. 14 failed to integrate and were replaced.
Conclusion: With this technique, a clinician may provide immediate temporary restorations of implants in function at the same time of implant placement without additional risks impacting the success of treatment.

03/11/05

Fit of Fixture/ Abutment Interface of Internal Connection Implant Systems

AO Annual Meeting | Orlando, FL | March, 2005
Kim, C., Gwangju, Chung.

Objective: The purpose of this study was to evaluate the machining accuracy and consistency of implant/ abutment/screw combination of internal connection type.
Materials and Methods: In this study, each two randomly selected internal implant fixtures from ITI, 3i, Avana, Bicon, Friadent, Astra, and Paragon system were used. Each abutment was connected to the implant with 32 Ncm torque value using a digital torque controller or tapping. All samples were cross-sectioned with grinder-polisher unit (Omnilap 2000 SBT Inc) after embedded in liquid unsaturated polyester (Epovia, Cray Valley Inc.) Then optical microscopic and scanning electron microscopic (SEM) evaluations of the implant-abutment interfaces were conducted to assess quality of fit between mating components.
Results: 1. Generally, the geometry of the internal connection system provided for a precision fit of the implant/abutment interface. 2. The most precision fit of the implant/abutment interface was provided in the case of the Bicon System which has no screw. 3. The fit of the implant/abutment inte3rface was usually good in the case of ITI, 3i and Avana system and tha amount of fit of the implant/ abutment was similar to each other. 4. The fit of the implant/ abutment interface was usually good in the case of Friadent, Astra and Paragon system. The case of Astra system with the inclined contacting surface had the most intimate contact among them. 5. Amount of intimate contact in the abutment screw thread to the mating fixture was larger in assembly with two-piece type which is separated screw from abutment such as Friadent, Atra and Paragon system than in that with one-piece type which is not separated screw from abutment such as ITI, 3I and Avana system. 6. Amount of contact in the screw and the screw seat of abutment was larger in assembly of Friadent system than in assembly of Astra system than in assembly of Astra system or Paragon system.
Conclusion: Conclusively, although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal implant-abutment connections which provide intimate contact with the implant walls to resist micromovement, resulting in a strong stable interface. From the results of this study, further research of the stress distribution according to the design of internal connection system will be required.

03/11/05

Morphological and Chemical Assessment of Two Thin-film Ion Beam Assisted Deposited Bioceramic Coated Surfaces on Ti-6Al-4V Implants

AO Annual Meeting | Orlando, FL | March, 2005
Coelho, P.G., Lemons, J.E.

Nanotechnology has strongly affected biomaterials science and engineering, once reduced condensed matter domains may deeply alter biomaterials electronics properties and thus their in-vivo behavior. It has been shown that nano-thick Ion Beam Assisted Depoisted (IBAD) bioceramic coatings increase osteoblatic activity at early implantation times, and studies have indicated higher bone-biomaterial interfacial shear strength values for IBAD coated implants. The purpose of this study was to morphologically and chemically assess 2 types of IBAD bioceramic coatings and correlate these evaluations to their in-vivo performance. Control (C) and nano-thick IBAD (IBAD 1, IBAD 2) implants were morphologically evaluated on a SEM under various magnifications, following by survey and site-specific EDS elemental assessment. Superficial layer chemical analyzes were performed by XPS (survey and site-specific), and Ca/P ratios were calculated from spectra output. Results showed no evidence of bioceramic coating presence on all implants (IBAD 1, IBAD 2 –too thin for SEM detection), although ion beam assisted surface etch was evident for IBAD implants. EDS showed the presence of Ti and Al for all specimens, and Ca and P presence for IBAD 2 implants only. XPS spectra showed the presence of Ti, Al, C, O and Si for C implant surfaces, Ti, Al, C, O, Si, Ca, and P for IBAD 1 implant surfaces, and C, O, Si, Ca, and P for IBAD 2 implant surfaces, revealing absorbed molecules (Si and C) for all implants and higher thickness for IBAD 2 implants. Stoichiometry ratios were 1.5 and 2.2 for IBAD 1 and IBAD2 respectively. According to the results obtained, IBAD 2 coatings were thicker than IBAD 1, and both were in the nanorange thickness. Stoichiometry ratios revealed that IBAD 1 and IBAD 2 were different than crystalline HA, suggesting that IBAD coating dissolution rates are potentially higher than crystalline HA. These findings were consistent with animal experiments, where biological response increases were detected at early implantation times due to coating dissolution. Coating nanothickness also allowed direct bone contact to implant metallic substrate, as per histological analyzes, as thin coatings disappear as a function of time in-vivo. IBAD coatings physico/chemical characteristics were desirable features for implant biomechanical fixation competence.

03/10/05

Gingival Tissue Health Around Locking-Taper Implant-Abutment Connections

IADR General Session | Baltimore, MD | March, 2005
Coelho, P.G., Materials Science & Engineering, Birmingham, AL, USA, Geurs, N.C., University of Alabama, Birmingham, USA, Freire, J.N.O., Universidade Federal De Santa Catarina, Florianopolis, Brazil, Coelho, A.L., UNICENP, Curitiba, Brazil, and Speratti, D., Faulkner Hospital, Boston, MA, USA

Objective: to clinically/histologically evaluate gingival tissue around locking taper connected implants in a beagle dog model.
Materials and Methods: Six beagle dogs were acquired 12 weeks prior to surgical procedures. Five weeks prior to euthanization, left mandibular 4th premolars were extracted, followed by immediate placement of two 3.5 mm diameter by 8 mm length endosseous implants at the mesial and distal root sockets. Locking taper abutments were installed to distal implants and the flap was closed by standard suture techniques. Three weeks prior to euthanization, locking taper abutments were installed on left mandibles mesial implants and the same surgical procedure previously described was used to place an implant of same dimensions on the mesial root socket, followed by abutment installation. All surgical procedures were followed by a single dose AB protocol. No mechanical/chemical plaque control was performed, and a crunchy diet was utilized throughout the study. After euthanization, mandibles were retrieved and abutments removed from implants. 5 µm thick soft tissue sections were obtained in the bucco-lingual direction aiming implants' long axis central region (H. and E. stained).
Results: Periodic clinical evaluations revealed absence of inflammation signs. Histological sections resembled healthy mucosal tissue for all 18 specimens. The junctional epithelium was well organized and void of intra cellular spaces. Neutrophils were found and few lymphocytes were noted. No vascular proliferation apical to junctional epithelium was observed.
Conclusion: Histological sections revealed that gingival tissue around locking taper connected implants were consistent with healthy gingival tissue.

03/10/05

Biomechanical Performance of IBAD Thin-Coated Implants at Early Implantation Times

IADR General Session | Baltimore, MD | March, 2005
Coelho, A.L., UNICENP, Curitiba, Brazil, Coelho, P.G., University of Alabama at Birmingham, Birmingham, USA, Freire, J.N.O., Universidade Federal De Santa Catarina, Florianópolis, Brazil, Suzuki, M., University of Alabama at Birmingham, Birmingham, USA., IADR General Session; Baltimore, MD

Desirable features of bioceramic thin-coated implants include controlled composition and thickness plus enhanced adhesion to metallic substrates. Also, metallic substrate exposure with subsequent bone direct contact to the implant surface as a function of time in-vivo may be a potential advantage compared to commercially available bioceramic coatings. Objective: compare the mechanical fixation of Ion Beam Assisted Deposited (IBAD) coated implants versus a non-coated grit-blasted/acid-etched (Control) treated implant surface. Methods: three male adult beagle dogs received 2-4 cylindrical implants on the proximal tibiae following sterile procedures. Left and right limbs provided specimens that remained for 5 and 3 weeks in-vivo respectively. After euthanization, the limbs were retrieved by sharp dissection, the implants received a connecting screw in order to adapt to a torque testing apparatus installed in a universal testing machine. Implants were torqued at a 0.5 in/min rate and maximum loads to interfacial failure were recorded. ANOVA was performed with Max Torque as the dependent variable, and time in-vivo and surface type as independent variables at 95% level of significance. Results: no post-surgical inflammation/infection was observed. Radiographic evaluation revealed bone contact to implant for all groups. Surface treatment had a significant effect on maximum torque value, IBAD= 79.55±7.21 N·cm and Control= 62.76±6.37 N·cm. Time in-vivo did not have a significant influence on maximum torque value, 3 weeks=62.52±6.66N·cm and 5 weeks= 67.23±6.9 N·cm. Conclusion: According to the results, IBAD coated implants presented higher anchorage values compared to control implants, supporting favorable conditions for early functional loading of these implants.

10/01/04

Evaluating the Bacterial Seal of an Implant-Abutment Connection

AAP Annual Meeting | Orlando, FL | October, 2004
Dibart, S.

Background: In the submerged implant design, the quality of the implant-abutment connection is thought to play a critical role in preserving the alveolar crestal bone levels from loss due to oral bacteria. Oral microorganism that would colonize that structure are suspected to initiate inflammation and promote bone loss over time. Methods: In order to test the efficacy of an implant-abutment seal to the bacterial challenge in vitro, a 2 phase experiment was devised. Phase 1: testing the ability of the seal to shield the implant well from outside bacteria. 10 abutments were seated on 10 wide body implants and then immersed in culture tubes containing a bacterial mixture. They were incubated for 24 hours anaerobically at 37°C. The abutments were then separated from implants, carbon coated, and the inside well analyzed for bacteria presence using a scanning electron microscope. Phase 2: testing the ability of the seal to prevent bacterial seepage out from the implant well. 0.1µl of a bacterial mix was deposited at the apical end of abutment posts, which were then carefully inserted into implant wells. The implant/abutment units were immersed, individually, in culture tubes containing a sterile broth and incubated anaerobically at 37°C for 72 hours. The broths were then plated on agar plates to check for bacterial growth.
Results: Phase 1: Scanning electron microscopy did not show any evidence of bacterial presence into the implant wells. Phase 2: There was no evidence of bacterial growth on the agar plates.
Discussion: The tested implant abutment seal was hermetic to oral bacteria in vitro, with no microorganisms transiting from the "outside-in" or the "inside-out".

10/01/04

Aesthetic Dental Implant Restorations

ADA General Session | Orlando, FL | October, 2004
Speratti, D.

Aesthetic restorative procedures on dental implants are known to be complexes and difficult to achieve, challenging clinicians and concerning patients where aesthetic is paramount to their needs. The technique shown in this presentation allowed the clinician to insert a screwless and cementless crown into a dental implant with no gap between the crown and the abutment, bringing an immediate aesthetic result. Clinical pictures will be shown in this presentation.

09/01/04

Comparison of the Periodontal Performance of the Integrated Abutment Crowns, Porcelain Fused to Metal Crowns and Teeth: A 2-year retrospective Cohort Study

Oral Presentation OSSEO | September, 2004
Urdaneta, R., et al.

The Integrated Abutment Crown (IAC) is a technique for the fabrication of single-tooth implant-supported restorations where the abutment and the crown material are one integral unit without the use of any screws or cement. There is no clinically discernible interface between the veneer material and the implant abutment due to a chemical bond. The precision of the prosthetic margin has been shown to be more important for the maintenance of gingival health than its location above or below the gingival margin (Richter and Veno, 1973). It was hypothesized that the gingival tissues would respond positively to a restoration without a crown margin. Purpose: The purpose of this 2-year retrospective clinical study was to compare the periodontal health around Integrated Abutment Crowns, Implant and tooth-supported metal ceramic crowns and adjacent natural teeth. Materials and Methods: 221 implants placed in 62 patients, with a mean age of 58.2 years, 56% were placed in the maxilla and 44% placed in the mandible. Of the prosthetic restorations, 151 were Integrated crowns, 70 were implant-supported Metal ceramic crowns, and 65 were tooth-supported metal ceramic crowns. Patients were recalled and the following periodontal measurements were obtained: Gingival index, modified plaque index, sulcular bleeding index and pocket depth. Results: The 2-year survival rate for Integrated crowns was 98.56%. Two Integrated crowns were removed, one due to implant failure. No significant differences in gingival inflammation and sulcular bleeding were observed between Integrated abutment crowns and unrestored teeth notwithstanding the higher plaque accumulation observed around the Integrated crowns. Furthermore, Metal ceramic crowns on implants had the highest bleeding index and the difference between the Integrated crowns was statistically significant. Teeth, regardless of restoration type, had lower pocket depths than implants. Conclusion: The gingival response around the integrated abutment crowns was similar to the health of the marginal tissues surrounding unrestored teeth. There was significantly less bleeding upon probing around Integrated abutment crowns than around implant supported metal ceramic crowns, this may be explained by the absence of a cement interface on the integrated crowns.

08/01/04

A Photoelastic Stress Analysis of Fixed Partial Dentures with Bicon Implants on Mandibular Posterior Area

Korean Acad Prosthodont. | August, 2004
Kang, JU., Kim, NY., Kim, YL., and Cho, HW.

Statement of Problem: Several prosthetic options are available for the restoration of multiple adjacent implants. A passively fitting prosthesis has been considered a prerequisite for the success and maintenance of osseointegration. Passivity is a particular concern with multiple implants because of documented inaccuracies in the casting and soldering process. One way to avoid this problem is to restore the implants individually, however, the restorations of individual adjacent impants requires careful adjustment of interproximal contacts.
PURPOSE: The purpose of this study was to compare the stress distribution pattern and amount surrounding Bicon implants with individual crowns and splinted restorations.
Material and Methods: A photoelastic model of a human partially edentulous left mandible with 3 Bicon implants(4*1 mm) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 abutments (4.0*6.5 mm, 0 degree, 2.0 mm post, Bicon Inc., Boston, USA) After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal (8 micrometershim stock drags without tearing), medium(40 micrometer), and heavy(80 micrometer). Splinted 3-unit fixed partial dentures were fabricated and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions(7.5, 15, 30 lb) were analyzed with a circular polaricope.
Results: 1. Stresses were distributed around the entire body of fin in Bicon implants. 2. Splinted restorations were useful for distribution of stress around implants especially with higher loads. 3. By increasing the contact tightness between the individually restored three implants, the stress increased in the coronal portion of implants.
ConclusionsS: Ideal adjustment of the contact tightness was important to reduce the stresses around individually restored Bicon implants.

03/23/04

Sinus Augmentation Procedure Using Beta-Tricalcium-Phosphate: Histological Analysis of Grafted Bone at Time of Implant Placement

03/20/04

Novos Casos Clínicos

Colocação e Restauração de Dois Implantes e Cirurgia de Alongamento da Coroa dos Dentes para Agenesia dos Incisivos Laterais

Este caso demonstra a colocação cirúrgica de dois implantes incisivos laterais de funcionamento imediato e sua restauração com Abutment Coroa Integrados™ Bicon juntamente com o alongamento cirúrgico da coroa dos dentes adjacentes.

03/19/04

Oportunidades Educacionais

Novos Cursos Bicon

A Bicon acaba de renovar as ofertas de cursos para apresentar maior flexibilidade a clínicos e profissionais de laboratório. O registro online encontra-se disponível agora para todos os cursos Bicon. Registre-se hoje — vagas são limitadas!

03/17/04

Novo Vídeo

Características Bicon

Este novo vídeo detalha as características únicas do Sistema Bicon de Implantes Dentários, inclusive o locking taper, remoção de abutment, selamento bacterial, posicionamento universal do abutment de 360º, ombro inclinado, estética gengival superior e raiz em forma de platô.

03/10/04

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Adesão Bacterial em Abutment Coroa Integrados™. Estudo In Vivo (II)

M. MARINCOLA, S. DIBART, M.L. WARBINGTON, Z. SKOBE, R. URDANETA, and S.-K. CHUANG, University of Cartagena, AISI, Italian Association of Restorative Implant Dentistry, Rome, Italy, Boston University, MA, USA, Forsyth Institute, Boston, MA, Harvard University, Concord Dental Associates, Concord, MA, USA, Massachusetts General Hospital and Harvard School of Dental Medicine, Harvard School of Public Health, Chestnut Hill.

Objetivos: A finalidade deste estudo foi comparar a microbiota da região subgengival presente em Abutment Coroa Integrados (ACI) suportados por implante e dentes naturais in vivo.

Material e Métodos: Um projeto de estudo de secção transversal foi utilizado com pacientes selecionados do grupo de pacientes do Implant Dentistry Centre do Faulkner Hospital (Boston, MA). Trinta e um pacientes (13 do sexo masculino e 18 do feminino) foram selecionados, com idade média de 57,36 anos (variação de 28,09 a 90,85 anos) dos quais 4 eram tabagistas. Os requisitos da seleção eram: Pacientes com coroas ACI colocadas pelo menos há 6 meses e que não tivessem tomado antibióticos 3 meses antes da avaliação. Índice gengival (IG), índice de sangramento modificado (ISM), amostras da placa subgengival e fotografias clínicas foram tiradas em pelo menos 1 ACI e do dente contralateral natural de cada paciente. As amostras de placa subgengival foram tiradas do lado mesial do ACI ou dos dentes naturais e colocadas em um tubo Eppendorf contendo 0.150 ml de Tris-EDTA. As amostras foram, então, hibridizadas com 12 sondas cromossômicas totais para Tannerella forsythensis, Prevotella intermedia, Campylobacter rectus, Fusobacterium nucleatum, Actinomyes odontolyticus, Streptococcus sanguis, Streptococcus intermedius, Actinobacillus actinomycetemcomitans serotype b, Actinomyces naeslundii, Streptococcus oralis, Porphyromonas gingivalis e Prevotella intermedia, usando o método checkerboard de hibridização DNA-DNA. As estatísticas descritivas e os modelos mistos lineares generalizados (GLMM) justificaram a correlação intra-agrupamento no mesmo paciente e foram utilizados usando SAS-PC (versão 8.2, 2001). Resultados: Foi observado que os ACIs apresentavam menos IG e ISM em comparação com os dentes naturais mas não eram estatisticamente significantes (p>0,05). Não houve disferenças estatísticas (p>0.05) em todas as diversas contagens de colônias entre ACIs e os dentes naturais.

Conclusões: O ACI apresentou semelhanças impressionantes com o dente natural em termos de contagem e composição da placa bacteriana subgengival. O ACI apresentou também índices menores de IG e ISM.

Financiado por bolsa de pesquisa da Bicon (MM, SD), OMSF Foundation Fellowship in Clinical Investigation (SKC).

03/10/04

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Adesão Bacterial em Abutment Coroa Integrados™. Estudo In Vitro (I)

S. DIBART, M. MARINCOLA, M.L. WARBINGTON, and Z. SKOBE, Boston University, MA, USA, University of Cartagena, AISI, Italian Association of Restorative Implant Dentistry, Rome, Italy, Forsyth Institute, Boston, MA.

Objetivos: A meta da presente pesquisa foi determinar se o material DiamondCrown, usado para fazer o Abutment Coroa Integrado (ACI) da Bicon, é menos suscetível para abrigar/atrair a placa bacteriana do que a coroa de cerâmica pura (CP) ou metalocerâmica (MC). A meta secundária foi comparar a composição da placa atraída sobre superfícies testadas.

Métodos: 6 coroas ACI, 6 CP e 6 MC foram igualmente divididas em 2 grupos de teste. As coroas CP e MC foram cimentadas sobre abutments de titânio. Os grupos I (3 ACI, 3 CP, 3 MC) e II foram incubados por 10 min. em solução bacteriana contendo 10 bactérias orais diferentes em O.D.1: Tanerella forsythensis, Prevotella intermedia, Campylobacter rectus, Fusobacterium nucleatum, Actinomyces odontololyticus, Streptococcus intermedius, Actinobacillus actinomycetemcomitans sorotipo b, Actinomyces naeslundii, Streptococcus oralis, Porphyromonas gingivalis. Após lavagem rápida com PBS para eliminar a placa livre, as amostras de coroa do grupo I foram incubadas em 500µl de tampão de Tris-EDTA com 500µl de NaOH. As amostras foram, em seguida, hibridizadas com 10 sondas cromossômicas totais para os microorganismos mencionados acima. A análise microbiológica foi concluída usando o método checkerboard de hibridização DNA-DNA. As amostras do grupo II foram lavadas rapidamente com PBS e fixadas em formalina a 4% para microscópico eletrônico de varredura (MEV).

Resultados: Todas as coroas experimentais mostraram adesão bacterial. Não há diferença estatística nas composições microbianas quando as coroas são comparadas. O MEV mostrou que as coroas CP abrigavam os depósitos mais pesados de bactérias. MC e ACI apresentavam os menores depósitos de bactérias especialmente na interface abutment/coroa.

Conclusões: As coroas ACI e MC parecem apresentar menor tendência à colonização bacteriana, em uma situação in vitro do que uma coroa de cerâmica pura. As coroas ACI e MC abrigavam muito poucas bactérias na interface abutment/coroa.

Este estudo foi financiado por bolsa de pesquisa da Bicon.

03/10/04

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Avaliação Retrospectiva de Dois Anos de Restauração Singular para Implantes Únicos

R. URDANETA, Harvard University, Concord Dental Associates, Concord, MA, USA, M. MARINCOLA, University of Cartagena, AISI, Italian Association of Restorative Implant Dentistry, Rome, Italy, and S.-K. CHUANG, Massachusetts General Hospital and Harvard School of Dental Medicine, Harvard School of Public Health, Chestnut Hill.

O Abutment Coroa Integrado™ (ACI) (Bicon, Boston, MA) é uma técnica para a fabricação de restaurações suportadas por implante de dente único nas quais o abutment e o material da coroa constituem uma unidade integral sem o uso de quaisquer parafusos ou cimento.

Objetivos: O objetivo deste estudo foi analisar o desempenho clínico de 2 anos de 151 ACIs colocados em consultório dentário.

Materiais e Métodos: Um projeto de estudo retrospectivo de coorte foi utilizado com pacientes selecionados do grupo de pacientes do Implant Dentistry Centre do Faulkner Hospital (Boston, MA). Os pacientes tinham retorno e as restaurações eram avaliadas de acordo com os critérios USPHS modificados. A estética gengival e a quantidade de consultas para restauração foram documentadas. As estatísticas descritivas e os modelos mistos lineares generalizados (GLMM) justificaram a correlação intra-agrupamento no mesmo paciente e foram utilizados usando SAS-PC (versão 8.2, 2001) .

Resultados: Um total de 151 implantes foram restaurados com ACIs em 59 pacientes, com média de idade de 58,2 anos, 62% foram colocados no maxilar e 38% na mandíbula. A taxa de sobrevivência de 2 anos para ACIs foi de 98,56%. Dois ACIs foram removidos, um devido a fracasso do implante; todos os demais foram classificados como excelentes ou bons em relação à anatomia, textura da superfície e cor. Nenhum ACI foi removido devido a fraturas. Foi observada excelente adaptação, sem interface clinicamente discernível entre o material de veneer e o abutment. Foi observada excelente estética gengival. Um número significativamente menor de consultas foi necessário para restaurar um ACI do que uma coroa metalocerâmica (p<0,0001).

Conclusão: Os resultados desta avaliação protética apoiam a conclusão que o Abutment Coroa Integrado™ é uma opção excelente para a restauração dos implantes únicos com locking-taper para as áreas anterior e posterior da boca. Os ACIs representam alternativa econômica e que economiza tempo às coroas metalocerâmicas.

Com o apoio da Oral and Maxillofacial Surgery Foundation (OMSF) Fellowship in Clinical Investigation (SKC).

03/10/04

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Avaliação Biomecânica de Implante IBAD de Superfície Modificada

P.G. COELHO, University of Alabama at Birmingham, Birmingham, USA, J. LEMONS, University of Alabama at Birmingham, USA, e A.W. EBERHARDT, University of Alabama at Birmingham, USA.

Grupos de pesquisa em implantologia deram atenção a revestimentos biocerâmicos de filmes finos sobre implantes dentários devido à potencial degradação biológica/dissolução do revestimento controladas após a implantação e fixação direta do osso ao substrato metálico.

Objetivo: A finalidade deste estudo foi avaliar a fixação biológica de implante de superfície modificada com deposição assistida por feixe de íons [ion beam assisted deposition (IBAD)] de filme fino comparado com implante de liga de titânio de superfície não modificada em tempos de implantação precoce in vivo em um modelo canino de laboratório.

Métodos: Os implantes foram colocados nas tíbias dos cachorros e permaneceram por 2 e 4 semanas in vivo. Após sacrifício sem dor, os membros foram recuperados e reduzidos a blocos contendo implante no seu centro. Os blocos foram montados em resina epoxy e os implantes foram extraídos a 0.5 polegadas por minuto em máquina de teste universal. Foram registradas as curvas força versus deslocamento para os espécimes, que eram subseqüentemente descalcificados e preparados (corante H. e E.) para avaliação histomorfométrica do contato ósseo na superfície do implante permitindo cálculos do esforço de cisalhamento interfacial.

Resultados: Os resultados mostraram que o contato ósseo na superfície do implante foi significativamente maior (P<0,03) para a superfície não modificada quando comparado com implante de superfície modificada para os dois tempos in vivo, e que as forças de remoção não eram estatisticamente diferentes entre os quatro grupos. ANOVA revelou que o tempo in vivo e o tratamento da superfície não afetam o esforço de cisalhamento interfacial.

Conclusão: De acordo com os resultados histomorfométricos e biomecânicos obtidos neste estudo, concluiu-se que não havia elos fracos entre o revestimento de filme fino e o substrato metálico. Além disso, o osso em torno dos implantes de superfície modificada pode ter suas propriedades mecânicas melhoradas, carcterística desejável para implantação precoce e de longo prazo de dispositivos de sustentação de carga. Esses resultados sugerem que a degradação biológica/dissolução total do revestimento pode não ser total nesses tempos de implantação precoce.

03/10/04

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Determinação do Espaço Implante-Abutment Radial por meio do Método de Seccionamento Serial

P.G. COELHO, University of Alabama at Birmingham, Birmingham, USA, M. SUZUKI, University of Alabama at Birmingham, USA, e A.L. COELHO, UNICENP, Curitiba, Brazil.

A comunidade de pesquisa em bioengenharia e implantologia devotou atenção significativa ao espaço implante-abutment, uma vez que esse espaço pode proporcionar um ambiente favorável para adesão/proliferação bacterial bem como para a degradação do substrato metálico. Classicamente, essa distância tem sido avaliada por meio de microscópico eletrônico de varredura (MEV) ao longo do perímetro do implante e nenhuma informação é revelada como função do raio.

Objetivo:A finalidade deste estudo foi avaliar o espaço implante-abutment como função do raio por meio de avaliação de microscopia óptica e da técnica de seccionamento seqüencial.

Métodos: Seis implantes (3.75 mm de diâmetro) e abutments foram conectados por parafuso e com torque de 20 N.cm. As medidas do raio externo foram registradas por MEV. Em seguida, os implantes foram montados em resina epoxy usando fixador metálico para assegurar sua posição (perpendicular ao eixo vertical). Subseqüentemente, cada implante foi desgastado e polido paralelamente a seu longo eixo em seis diferentes intervalos de distância. Os espaços implante-abutment foram obtidos por microscopia óptica (1000X de aumento) e essas distâncias foram relacionadas à sua posição radial por meio de inferências trigonométricas. Foi usada a abordagem da equação polinomial de 6º grau de melhor assentamento para determinar os padrões de adaptação radial para cada um dos implantes.

Resultados: Os resultados mostraram que as distâncias do espaço não eram estatisticamente diferentes entre os implantes (P=0,05). A abordagem da equação polinomial de melhor assentamento revelou que a distância do espaço implante-abutment aumenta como função do raio do implante e este aumento é mais pronunciado no raio 1/4 externo, na região biselada do abutment. Também, a comunicação entre as regiões externas e internas do implante foi encontrada para todos os espécimes.

Conclusão: Com base nesses resultados, concluiu-se que esta metodologia proporcionava um cenário mais amplo da distância do espaço implante-abutment e que as avaliações MEV podem subestimar o valor do espaço.

01/06/04

Caso Clínico Atualizado

Implantes Curtos: Sucesso Clínico Comprovado desde 1997

Essas radiografias demonstram a altura mínima do osso exigida pelo implante curto da Bicon, potencialmente eliminando a necessidade de elevação dos seios maxilares e enxerto ósseo. O implante curto permite uma colocação segura em casos com altura mínima de osso acima do nervo alveolar inferior.

12/15/03

Novo Guia de Seleção de Abutment ACI

Houve algumas pequenas revisões de nosso Guia de Seleção de Abutment ACI. Certifique-se de estar atualizado.

12/11/03

Nova Publicação Adicionada

Complicações dos Implantes Dentários: Freqüência de Identificação e Fatores de Risco Associados

52. McDermott, N., Chuang, S.K., Vehemente, V., Dodson, T.B., Complications of Dental Implants: Identification Frequency and Associated Risk Factors, The International Journal of Oral & Maxillofacial Implants, Vol 18 No. 6, p. 1379-1389, Dezembro 2003

12/05/03

Nova Publicação Adicionada

Avaliação Metrológica e Topográfica Tridimensional dos Implantes Dentários por Microscopia Confocal de Varredura a Laser

51. B. Al-Nawas, H. Gotz, Three-Dimensional Topographic and Metrologic Evaluation of Dental Implants by Confocal Laser Scanning Microscopy, Clinical Implant Dentistry, Volume 5, Number 3, 2003

10/03/03

Nova Publicação Adicionada

Mecânica do Ajuste de Interferência com Paralelizadores em Implantes Dentários

50. Muftu, S, and Bozkaya, D., Mechanics of the Tapered Interference Fit in Dental Implants, Journal of Biomechanics, Volume 36 Issue 11, pgs. 1649, 1658, Novembro 2003

03/12/03

Resumo da pesquisa em AADR/CADR Annual Meeting; San Antonio, TX

Implantes de 6.0 x 5.7 mm: Estimativas de Sobrevivência e Fatores de Risco para Fracasso

M.A. GENTILE, S.-K. CHUANG, and T.B. DODSON, Harvard School of Dental Medicine, Boston, MA, USA, Massachusetts General Hospital and Harvard School of Dental Medicine, Boston, USA

Introdução: Implantes dentários curtos facilitam a restauração protética na situação de altura óssea alveolar limitada. Existem poucos dados para apoiar o uso clínico de implantes curtos. Levantamos a hipótese que os implantes de 6x5.7 são uma opção clinicamente aceitável, se indicados.

Objetivo: Os objetivos do estudo são: 1) estimar a sobrevivência de um ano de implantes Bicon de 6x5.7 mm , 2) identificar os fatores de risco associados a fracasso de implante de 6x5.7 e 3) comparar a sobrevivência de um ano de implantes de 6x5.7 com implantes não 6x5.7.

Métodos: Utilizamos um projeto de estudo de coorte retrospectivo e uma amostra formada por pacientes com implante de 6x5.7 colocado. As variáveis de previsão foram categorizadas como demográficas, condições de saúde, anatômicas, específicas do implante, protéticas, perioperatórias e reconstrutivas. A variável de resultado foi o fracasso do implante definido como explantação. As estimativas Kaplan-Meier foram usadas para avaliar a sobrevivência do implante. Foram computadas as estatíticas de sobrevivência bivariadas e multivariadas (regressão de Cox).

Resultados: A amostra era composta por 35 pacientes com 172 implantes colocados (45 6x5.7 e 127 não 6x5.7). A sobrevivência de um ano de implantes 6x5.7 e não 6x5.7 foi 92,18% e 95,24%, respectivamente (p=0,78). As análises bivariadas identificaram estagiamento e reconstrução como fatores de risco para fracasso. Após o ajuste para co-variáveis em modelo multivariado, foi encontrado que a colocação de implante de um estágio representava fator de risco estatisticamente significante (p=0,047) para fracasso de implante.

Conclusão: Acreditamos ser este o primeiro estudo que apresente resultados clínicos do implante Bicon® 6x5.7. A sobrevivência de implantes de 6x5.7 foi comparável com a dos implantes não 6x5.7. Estes dados apóiam a hipótese que implantes de 6x5.7 constituem opção clinicamente aceitável para facilitar a restauração protética na situação de altura alveolar limitada. Além disso, os resultados sugerem que é preferível a abordagem de dois estágios para a colocação desses implantes.

Apoiado pela OMS Foundation Fellowship in Clinical Investigation (S-KC), NIH-NIDCR K24 DE00448 (TBD), MGH Department of OMS Research Fund (MAG).

03/12/03

Resumo da pesquisa em AADR/CADR Annual Meeting; San Antonio, TX

Métodos de Tempos de Fracasso por Fragilidade de Efeitos Mistos para Estimar a Sobrevivência de Implantes Dentários

M.A. GENTILE, S.-K. CHUANG, and T.B. DODSON, Harvard School of Dental Medicine, Boston, MA, USA, Massachusetts General Hospital and Harvard School of Dental Medicine, Boston, USA.

Finalidade: A finalidade deste estudo foi identificar efeitos de co-variáveis associados com fracasso de implante aplicando-se métodos de sobrevivência de fragilidade semi-paramétricos agrupados por regressão de Cox. Conforme nosso conhecimento, este método não foi descrito ou aplicado amplamente na literatura de pesquisa odontológica.

Métodos: Para atingir a finalidade da pesquisa, usamos um projeto de estudo de coorte retrospectivo. A coorte era formada por pacientes com um ou mais implantes Bicon colocados. As co-variáveis foram categorizadas como variáveis demográficas, condições de saúde, específicas do implante, anatômicas, protéticas, perioperatórias e reconstrutivas. A variável de resultado foi o fracasso do implante (explantação). As co-variáveis para fracasso de implante foram identificadas usando-se os métodos de sobrevivência de fragilidade ajustados para observações de tempo de fracasso agrupadas.

Resultados: A amostra era composta por 677 pacientes com 2.349 implantes colocados. As co-variáveis associadas com fracasso de implante (p < 0,15) incluiam o cirurgião, uso de tabaco, uso de antibiótico peri-operatório, posição do implante, comprimento do implante, tamanho da cavidade, revestimento do implante, proximidade do implante aos dentes adjacentes ou outros implantes, colocação imediata de implante, diâmetro do abutment, tipo de prótese, uso de procedimentos de reconstrução e estagiamento do implante. Com base no modelo ajustado de fragilidade multivariado, as co-variáveis associadas a fracasso de implante foram uso de tabaco, comprimento e estagiamento do implante, proximidade do implante aos dentes adjacentes ou outros implantes e tamanho da cavidade.

Conclusão: Conjuntos de dados formados por observações agrupadas são comumente encontrados na pesquisa odontológica. As análises de sobrevivência desses conjuntos de dados são proposições sumamente desafiadoras. Apresentamos métodos inovadores de sobrevivência de fragilidade por regressão de Cox com aplicações clínicas a implantes como exemplo. Identificamos cinco fatores associados com fracasso de implante. Três dessas variáveis, condição de tabagista, tamanho da cavidade e estagiamento da colocação do implante estão sob controle direto do dentista.

Apoiado pela Oral and Maxillofacial Surgery Research Foundation Fellowship in Clinical Investigation (S-KC), NIH grant K24 DE000448 (TBD) and MGH Department of OMS Research Fund (S-KC, TBD).

03/12/03

Resumo da pesquisa em AADR/CADR Annual Meeting; San Antonio, TX

Determinação da Actividade Óssea ao redor de um Implante de Liga de Titânio de Superfície Modificada

P.G. COELHO, University of Alabama at Birmingham, USA, e J. LEMONS, University of Alabama at Birmingham, USA.

Objetivo: A finalidade deste estudo foi avaliar a atividade óssea trabecular e cortical por meio de identificação do osso com tetraciclina de uma superfície modificada (IBAD) comparado com implante de liga de titânio de superfície não modificada em modelo canino.

Métodos: Os implantes foram colocados cirurgicamente nas tíbias dos cachorros e o modelo proporcionou espécimes que permaneceram por 2 e 4 semanas in vivo. Antes do sacrifício sem dor, foi administrada 10mg/Kg de oxitetraciclina para identificação do osso. Os membros foram recuperados por dissecção e as secções finas não descalcificadas contendo o implante em seus centros foram preparadas para avaliação microscópica sob luz UV. A determinação da atividade óssea (quantidade de rótulos de tetraciclina) foi avaliada dividindo-se os espécimes em regiões de interesse ao longo do comprimento e afastando-se da superfície do implante (até 2 mm) por técnicas de microscopia quantitativa. A atividade fisiológica foi obtida pela avaliação da identificação com tetraciclina afastando-se (> 3 mm) da superfície do implante e compreendia os dados de normalização.

Resultados: Os resultados mostraram que o implante de superfície modificada de 4 semanas apresentava quantidade significativamente maior (P = 0,05) de identificação com tetraciclina do que os outros grupos e demonstraram que há significativamente mais identificação em regiões do osso trabecular do que nas regiões de osso cortical. A quantificação da quantidade rotulada para as diferentes regiões de interesse em distâncias diferentes da superfície do implante (até 2 mm) revelaram que a única região que apresentava atividade significativamente maior do que os níveis fisiológicos era a adjacente à superfície do implante (até 0.5 mm) e a quantidade de identificação era significativamente maior para o grupo de superfície modificada de 4 semanas. A determinação dos gradientes de atividade óssea da superfície do implante foi executada por regressão linear e apresentava inclinações negativas da superfície do implante.

Conclusões: Estes resultados indicaram que existe osteocondutividade crescente dependente do tempo para implantes com superfície tratada e que a atividade óssea após a implantação está restrita aos primeiros 0.5 mm da região adjacente à superfície do implante.

03/07/02

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Complicações de implantes dentários: Tipos, freqüência e fatores de risco associados

N. MCDERMOTT, S.-K. CHUANG, V. VEHEMENTE, S. DAHER, A. MUFTU, and T.B. DODSON, Harvard School of Dental Medicine, USA, Boston University Goldman School of Dental Medicine, USA, Tufts University School of Dental Medicine, USA, Massachusetts General Hospital, USA.

Objetivos: A finalidade deste estudo foi identificar o tipo, a freqüência e os fatores associados a complicações após a colocação de implantes dentários.

Materiais e Métodos: Para atingir a finalidade da pesquisa, usamos um projeto de estudo de coorte retrospectivo e uma amostra derivada de pacientes tendo implantes Bicon (Bicon, Boston, MA) colocados no Implant Dentistry Centre, Faulkner Hospital, Boston, MA entre 1992 e 2000. As variáveis de previsão foram agrupadas nas categorias demográfica, histórico médico, específica do implante, anatômica, protética e reconstrutiva. As variáveis de complicação foram agrupadas em inflamatória, protética ou operatória. Para cada paciente, foi selecionado um implante ao acaso para inclusão no estudo. O modelo de regressão de Cox foi usado para identificar fatores de risco associados a complicações de implante.

Resultados: A amostra era composta por 677 pacientes com média de idade de 53,5 +/- 13,9 anos. A freqüência global de complicações de implante foi 13,9% (10,2% inflamatória, 2,7% protética, 1,0% operatória). A maioria dos implantes (62%) com complicações não fracassaram durante o intervalo do estudo. As variáveis associadas com complicações (p < 0,15) foram: 1) tabagismo, 2) tipo de prótese; 3) estagiamento de implante e 4) uso de procedimentos de reconstrução. Essas quatro variáveis, sexo e idade (6 variáveis no total) foram incluídas no modelo multivariado. A análise de regressão Cox revelou que tabagismo, estagiamento de implante e uso de procedimentos de reconstrução estão estatisticamente associados com complicações de implante (p < 0,05). O tipo de prótese foi limítrofe não significante (p=0,08).

Conclusão: Fatores associados com risco crescente de complicações incluem tabagismo, estagiamento de implante e uso de procedimentos de reconstrução.

03/07/02

Resumo da pesquisa em IADR/AADR/CADR 80th General Session; Honolulu, HI

Fatores de risco para fracasso de implantes dentários: Uma estratégia para a análise de observações de tempo de fracasso agrupadas

S.-K. CHUANG, Harvard School of Dental Medicine, USA, L.-J. WEI, Harvard School of Public Health, USA, and T.B. DODSON, Massachusetts General Hospital, USA.

Objetivos: O objetivo deste estudo foi identificar fatores de risco associados a fracasso de implantes dentários aplicando métodos de sobrevivência semi-paramétricos, avançados e inovadores que ajustam observações de tempo de fracasso agrupadas.

Métodos: Para atingir o objetivo da pesquisa, usamos um projeto de estudo de coorte retrospectivo incluindo todos os pacientes que tinham um ou mais implantes colocados na Implant Dentistry do Faulkner Hospital, Boston, MA entre 1992 e 2000. Os fatores de risco para fracasso foram agrupados nas seguintes categorias: demográfica, condições de saúde, específica do implante, anatômica, protética e reconstrutiva. A variável de resultado foi o fracasso do implante definido como explantação. A sobrevivência global do implante foi ajustada para observações de tempo de fracasso agrupadas. Os fatores de risco para fracasso de implante usando modelo de dependência e aplicando a abordagem marginal do modelo de regressão de Cox.

Resultados: A amostra era composta por 677 pacientes que tinham 2.349 implantes colocados. As taxas globais de sobrevivência Kaplan-Meier em um e cinco anos foram 95,46% e 90,91%, respectivamente. Fatores de risco univariados associados com fracasso (com p < 0,15) foram condição de tabagista, posição do implante, comprimento do implante, tamanho da cavidade, revestimento do implante, proximidade do implante, colocação imediata do implante, diâmetro do abutment, tipo de prótese e estagiamento do implante. Com base em modelo multivariado que ajusta para observações correlacionadas, cinco fatores foram associados estatisticamente com fracassos de implante (p < 0,05): 1) tabagismo, 2) comprimento do implante; 3) implantes imediatos; 4) estagiamento de implante e 5) tamanho da cavidade.

Conclusões: O acompanhamento e o controle de observações correlacionadas ou agrupadas dentro do mesmo tema é uma proposição comum e desafiadora da pesquisa odontológica. Na seleção de fatores de risco para inclusão no modelo de regressão de Cox, recomendamos o ajuste para dependência entre as observações de implantes dentários no mesmo paciente.

Apoiado por bolsas NIH: K16 DE000275 (SKC), R01 CA56844 (LJW) e K24 DE000448 (TBD).