Computer Guided Surgery Using Bicon Implants

I am Vin Morgan. The following comprehensive presentation of Dr. Hesham Marei will not only show you the many advantages of guided surgeries, but more importantly their associated limitations and risk, as well as the sources of these potential issues. I applaud Dr. Marei’s conservative, yet realistic approach to guided surgeries. Yes, guided surgeries can present risk and have limitations, but with proper training they can be an important technique for certain patients in their clinical situations. The initial video before Dr. Marei’s presentation will offer a succinct overview of Bicon’s guided surgery instrumentation using a teeth supported guide for a fully guided implant placement of a mandibular molar. It should be noted that Bicon’s guided surgery kits are specific to the diameter of the intended implant and, unlike regular reamers which subsequently widen an osteotomy, guided reamers subsequently deepen an osteotomy. This video will demonstrate the two stage placement of a short implant utilizing Bicon’s guided surgery kit. After taking a CT scan and having a surgical guide fabricated, the guide is inserted into the patient’s mouth to ensure its proper fit. The tissue punch may be used if a flap is not desired. Remove the guide and expose the crest using a conservative flap. A retraction suture is used to facilitate the proper seating of the guide and to keep the flap out of the surgical site. Insert the guide into the mouth and start with the spade drill rotating at four hundred RPM with external irrigation. Next, deepen the osteotomy with sequentially longer guided reamers rotating at up to fifty RPM without irrigation. As with the spade drill, only begin rotating the instrument once the tip of the instrument has contacted bone. The full depth is reached when the guide stop contacts the guide ring. The final reamer should correspond with the length of the intended implant. Once the intended depth has been reached, a curette is used to confirm the five walls of the osteotomy and to assure there is no remnant material that could prevent the implant from being fully seated. Using the sterile packaging, engage the implant to the implant inserter and turn the barrel until it sits flush with the top of the implant. Place the implant through the guide until it is fully seated. Disengage the implant inserter and remove it. After removing the guide, a cut black healing plug is inserted into the well of the implant. The harvested bone, collected during reaming, is placed over the shoulder of the implant. The site is sutured and a radiograph is taken. Hello, first I would like to introduce myself. My name is Hesham Marei. I have been doing guided implant surgery for the last five years. Today I’m here to present my story of guided surgery when I used Bicon implants. My presentation is divided into three parts. The first part is about the concept of computer guided implant surgery and in the second part I’m going to present four clinical cases that show the different protocols of guided surgery. Finally, I will end by discussing the limitations of computer guided surgery and the different sources of errors. The workflow begins by requesting a CBCT for the patients which will result in having DICOM files then optical scanning of the patients to obtain an STL file representing the three d image of the intraoral structures then virtual simulation of the treatment plan using implant planning software which ends by designing and exporting the surgical guide for three d printing. As we discussed, the first step after clinical examination is requesting a CBCT for the patients. There are certain requirements for patient position during taking the cone beam CT as all of you know it’s very important to have absolute stability of the patient during scanning also the vertical laser marker should divide the face into two equal halves while the horizontal laser marker should be parallel to the occlusal plane. Finally, the area of interest should be at the center of the field of view. Also, it is advisable to separate the upper and lower teeth during scanning to avoid the overlap of the incisor edges and the occlusal surfaces of the mandibular teeth while planning for maxillary implants. Also, is recommended to place cotton rolls in the buccal vestibules to avoid the overlap of the shadow of the soft tissue on the buccal cortical plate of the edentulous space. While for completely edentulous path, we follow a dual scan protocol which involves two CBCT scans, one for the patient denture or we sometimes call it the scan prosthesis and the second one for the patient while wearing the denture or scan prosthesis. The scan prosthesis is an existing removable prosthesis or a radiolucent duplicate of the diagnostic teeth setup with dual scan markers integrated or glued into the surface or you can use one point five or two millimeter scan markers which can be placed on the surface of the denture as you can see in this slide. During scanning the patient with denture, the patient should be biting on a bite index which is three to five millimeters thickness. It as it stabilizes upper and lower denture in place. Also it is your reference for stabilizing the upper and lower surgical guide during surgery so you don’t throw it away after scanning. The second step in the workflow is digitizing the patients to obtain an STL file which stands for standard triangle language or standard tessellation language. Digitizing the patients involves direct scanning of upper and lower dental arch using intraoral scanner or indirect scanning of the patient study models or patient’s impression using a desktop scanner, if you don’t have intraoral or extraoral scanners, you can perform a CBCT scan for the patient impressions and then the DICOM files can be later exported as an STL files using some of the free available software. However, the accuracy might not be as good as performing a direct intraoral scanning. The third step in the workflow is using an implant planning software to simulate the treatment plan and virtually place the implants after an accurate registration of the CBCT and STL files. There are many software in the market such as Simplant, coDiagnostiX, NobelClinician, 3Shape Implant Studio, OnDemand3D and Blue Sky Plan. The implant planning software can facilitate the designs of the different surgical guides. We have either teeth supported surgical guides which have to rest on teeth during drilling and implant insertion or you might use a bone supported surgical guide which requires opening a mucoperosteal flap and in this case the surgical guide has to be fixed on bone using anchor pins or titanium screws. The third type is a mucosa supported surgical guides which would rest on the mucosa and will allow you to perform flapless surgery in a completely edentulous arch. These surgical guides can facilitate either a fully guided or partially guided surgical approach. In a fully guided approach you need to use a fully guided implant kit, implant drilling or screwing is performed through the surgical guides, implant placement is still performed while the guide is still in place, in a partially guided protocol we have two different variations which are pilot drill and universal drill approach, in pilot drill we perform only the initial drilling using the pilot drill while the guide has the corresponding pilot drill ring and sleeve and then widening of the osteotomy is performed using the freehand kit till the implant insertion which is done also freehand. In a universal drill protocol, drilling is performed using a universal drill kit till the drill before the last one and then the last drill is performed freehand using the freehand surgical kit of the corresponding implant system. The last step in the workflow is manufacturing the surgical guides which is usual performed through additive manufacturing or three d printing. There are many different types of three d printers currently available in the market. However, the most commonly used for in office printing is based on either SLA or DLP printing technology. The second part of my presentation is clinical cases showing the different guided surgery protocols and for demonstration purposes we are using 3Shape Implant Studio as a planning software for simulation of the treatment plan. In case number one, we have a fifty years old male patient who is medically fit and well presented to replace missing teeth number three point five and three point six, the workflow involves importing the STL, then digital wax up to proceed with a prosthetically driven treatment plan, importing the patient’s CT, surface registration of the CBCT and the STL of the patient. As you can see the registration shows a homogeneous green color as per the color map which is an indication for an accurate registration of the two surfaces. Then the registrations can be checked in different planes and as you can see the yellow line of the STL is following the radiopaque surfaces of the mandibular teeth in different planes. Since this step could be a potential source of error, it needs to be checked in different planes and this video is demonstrating checking the alignment in different planes. Then we have virtual implant planning using Bicon implant 4.5×6 at site three point five. As you can see, the implant is virtually placed to be around two millimeters below the crest of the ridge. Again virtual implant simulation at site three point six using four point five by six Bicon implants and this is a panoramic view showing the relations of the two implants to each other and to the inferior alveolar canal. Since we are planning for a partially guided protocol using a pilot drill, we need to adjust the offset distance to be consistent with the pilot drill that you have. So here the offset distance is the distance between the top of the ring and the implant head. It is adjusted in this case to be twelve millimeters plus a six millimeters implant so you need a pilot drill with a stopper at a length of eighteen millimeters. The same was applied to implant at site three-six. This is the designed surgical guides exported as STL printed and fitted on the study model, the printed guide is a teeth support surgical guide and its fit is checked on the patient’s mouth, then routine procedures crestal incision through a gingival circular incision with no vertical releasing incisions, the buccal and lingual soft tissue is reflected using the flanges of the surgical guides and the pilot drill is inside the pilot drill ring before drilling and here drilling to a depth of eighteen millimeter as initial pilot drilling and parallel pins in place then we continue the procedure as usual using the free hand kit, the implant insertion is free hand. And here the implants are at their final seated positions and the healing plugs are in place. Then the harvested bone from the reaming procedures is used to graft the buccal sites at implant three-five. This is a preoperative virtual plan and the postoperative OPG. In case number two, we are demonstrating a partially guided protocols to place implants at sites two-five and in this case it is obligatory to use a pilot drill. Let us see how we are going to manage this case. It is for a fifty five years old lady presented to replace missing tooth number twenty five. We have selected four point five by six millimeter Bicon implants. As I said in the last case, the use of partly guided protocol using pilot drill was an optional. However, in this case it’s obligatory due to the limited interdental space available at this site which limits the use of four point seven ring. The selected pilot ring allows for two millimeter drill diameter, this is the final virtual placement of Bicon implants again it is two millimeter below the alveolar crest and the offset distance is adjusted to be eleven millimeters so we need a pilot drill with a stopper at seventeen millimeters. The designed surgical guide then exported into STL this is the patient’s preoperative intraoral photo and the teeth supported surgical guide is fitted in place, the pilot drill with a stopper at seventeen millimeters, limited crystal incision, drilling using the pilot drill and then widening the osteotomy using the Bicon freehand implant kit, implant placement is performed freehand. This is the preoperative virtual plan and the immediate postoperative periapical radiograph. It appears that the implant has a distal tilt however it is centered perfectly under the center of the planned crown. In the next case, case number three, we are going to demonstrate a fully guided surgical protocols in placing four point five by six implants. So this is a patient’s preoperative CBCT showing missing tooth three point seven with a horizontal bone deficiency at the buccal site, the same protocol importing the patient’s CBCT and STL with digital wax up, then surface registration of the CBCT and the STL and here zero indicates no difference between both surfaces, virtual insertion of implant 4.5×6, then selecting four point seven millimeters Bicon ring and this is the design surgical guide, then drilling protocol showing the implant order number and the use of short implant in this case allowed the guided placement of implants in the posterior region of a patient with a limited mouth opening. So, is the 4.5 guided surgery kit and this is preoperative photo showing buccal concavity and lack of keratinised tissue on the buccal side, so we decided to perform a crystal incision instead of tissue punch to preserve the keratinised tissue and to allow for buccal bone grafting, widening the osteotomy using four point five by six reamer from the guided surgery kit, final osteotomy with a very thin buccal wall, guided implant placement using implant guided inserter, then the implant in its final seated position and grafting the buccal wall using the harvested bone and attaining a primary closure with four zero Vicryl suture. This is a preoperative virtual plan and the postoperative OPG. In the next case, case number four, we are going to show the fully guided surgery through a flapless approach. So, we have a fifty five years old lady who is medically fit and well presented to replace missing posterior teeth, the plan is to perform a fixed restoration on the upper right side as a part of a comprehensive treatment plan. The patient has buccal bone deficiency at site one-two, so routine workflow begins by importing the patient CBCT, importing the patient STL, digital wax up although we have five missing teeth still the denture space is just enough to accommodate four crowns, surface registration of the STL to the patient’s CT shows accurate alignment and simulation of three implants at site sixteen, fourteen, thirteen and this is the axial view showing the relations of the three implants to each other, the design surgical guide with implant sizes, patient’s preoperative view and the surgical guide is fitted well on the teeth, tissue punch using a tissue punch instrument in the guided surgery kit, at this stage it’s better to preserve the keratinized tissue just in case if you didn’t get a good primary stability due to for instance low bone quality so you can retain back the keratinised tissue and proceed as a two stage surgery. Widening the osteotomy using the different reamers which are available in the guided surgery kit, guided implant placement using the guided implant inserter, attaching immediately the temporary abutment and here if you decided to perform a two stage surgery, you might return the excised keratinized tissue and suture it back in place in place. And this is the patient’s preoperative virtual plan and the patient’s postoperative opG showing implants nicely placed and parallel to each other at the upper right side. The last part of my presentation is about the limitations of computer guided implant surgery and the sources of errors. A recent article discussing the different consensus about the use of digital technology showed that the main deviations of computer guided implant surgery at the entry point was one point two millimeter, at the apical position it was one point five millimeter and for angular deviation it was three point five. Such source of errors could be attributed to multiple factors such as CBCT acquisition, surface scanning, virtual planning, three d printing, sterilization of the surgical guides and its supporting structures and surgeon experience. All these factors together dictate the accuracy of the final product. So during CBCT acquisitions, head tilt could be a source of error as it can lead to a vertical measurement error of three millimeter and a horizontal error of around one millimeter. This is a correct head position and this is a tilted head position. Also, double margins of the bone due to patient’s movements during scanning it would be difficult during virtual implant planning to know which margin is a correct one. Also presence of radiopaque lines radiating from metallic restoration it can obscure the dental structure which complicates the surface registration process. Furthermore, the same article is showing that the margin of error in CBCT is under or over estimations by one millimeter. Another recent systematic review shows that accuracy is limited to specific applications in terms of intraoral or extraoral scanners and the scanning of completely edentulous arch is still a clinical challenge. During implant planning, there are different sources of error. The most common source of error is alignment error. As you can see, the yellow line representing the study model is not following the radiopaque surface of the corresponding dental structures. Alignment is adjusted to have a complete and accurate overlap or accurate stitch between the two surfaces. Another error could happen during the virtual immediate implant placement. Sometimes the CBCT is not sharp enough to differentiate between the radio opacity representing the tooth enamel and the buccal cortical plate, so it can become difficult to know exactly where to position the head of the implant in relation to the future extraction sockets. Another error could happen you during virtual tooth extraction from the STL, the virtual extractions might not one hundred percent be similar to the real extraction resulting in an area of excess that obstructs the guide during placement, resulting in an area of excess that obstructs the guide during placement and this is an example of lack of fitting of surgical guide which can result in deficient implant insertion. Another potential source of error is designing the guide to engage heavy undercuts on both sides of the arch. For this guide to fit we had to divide it into two halves. In regard to printing, the market involves every day new different printers. Still the accuracy of every printer plays a factor in our final product. And this is a recent article that evaluated two types of printer and reached to a conclusion that accuracy is a device dependent. Another potential source of error during printing is to add the support on the fitting surface of the guide or the ring. Its removal later on might lead to change in the internal dimensions of the guide leading to a change in the angulation of the ring during placements. Other sources of errors could be the implant length, spatial limitations with limited mouth opening, the inability of the operator to place the drill properly inside the ring might lead to deviations during the drilling procedure. It’s also reported that the shorter drilling length below the sleeve, the more accurate is the final result which supports the use of shorter implants with guided surgery. Also, type of support during surgery is another factor which dictates the degree of accuracy. It is well documented that tooth supported guides offer more accurate results than a mucosa and cone supported guides. It’s recommended that the surgical guides should be digitally designed on a surface scan model rather than on DICOM data. Moreover, the surgeon experience is also another factor. Expert surgeons perform more accurate results especially in the partially guided surgery. Based on all the presented sources of errors, let us imagine that we have another surgeon who is working on completely edentulous patients with critical amount of bone width, placing long implants and doing this through a flapless approach using a mucosa supported surgical guides. So we can imagine how would be the accuracy of this procedure. So, the take home message of my presentation is computer guided implant surgery can offer you accurate results however it is not free of risks and complications that are sometimes difficult to manage by novice surgeons. By this, I would like to conclude my presentation and thanks very much for your attention. Although Bicon’s guided surgery kits and techniques are simple, straightforward and efficient. Guided surgery is most often unnecessary. While with Bicon’s 5.0mm short and 3.0mm narrow implants, all areas of the edentulous alveolus can effectively be treated with freehand implant placements. Although it is true, most Bicon clinicians find it simple and convenient to place implants freehandedly, in certain circumstances guided surgery techniques can be beneficial for both clinicians unfamiliar with the Bicon implant system and for experienced clinicians as well. The following three guided surgery treatment videos will demonstrate these facts. The first video shows the use of a teeth supported guide for the fully guided placement of a mandibular molar. The second video demonstrates the use of a mucosa supported guide for the fully guided placement of four mandibular implants, where there is ample bone to justify the use of a mucosa supported guide. The last video demonstrates the use of a teeth supported guide for a partially guided surgery for the initial preparation of the osteotomy to the floor of the sinus. It then shows the subsequent elevation of the sinus floor using free handed instrumentation for the placement of a molar implant with an internal sinus lift procedure. Hopefully this presentation has furthered your understanding of Bicon’s versatile guided surgery techniques for the benefit of both you and your patients. Thank you for having watched.