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Ppad nov dec2003f

  1. 1. C O N T I N U I N G E D U C A T I O N 3 0 USE OF STEREOLITHOGRAPHIC MODELS AS DIAGNOSTIC AND RESTORATIVE A IDS FORPREDICTABLE IMMEDIATE LOADING OF IMPLANTS Scott D. Ganz, DMD* GANZ 15 10 NOVEMBER/DECEMBER Implant dentistry has evolved into one of the most predictable treatment alterna- tives in all of medical science. Advances in the surgical and prosthetic components, implant designs and surface technologies, and imaging techniques have allowed for significant modifications to occur with respect to one- and two-stage surgical protocols, accelerating treatment times to the benefit of patient and clinician. This article presents a technique to improve surgical and restorative accuracy, allowing for predictable placement and immediate loading of implants through use of CT imaging, stereolithographic models, and CT-derived surgical templates. Learning Objectives: This article presents concepts for implant surgery simulation using advanced surgical templates fabricated from CT-derived data. Upon reading this article, the reader should: • Understand the role of CT scanning in proper implant placement. • Recognize the steps and considerations involved in implant surgery simulation. Key Words: implant, stereolithographic model, computed tomography, template, guide, immediate loading * Private practice, Fort Lee, NJ. Scott D. Ganz, DMD, 158 Linwood Plaza, Suite 204, Fort Lee, NJ 07024 Tel: 201-592-8888 • Fax: 201-592-8821 • E-mail: sdgimplant@aol.comPract Proced Aesthet Dent 2003;15(10):763-771 763
  2. 2. Practical Procedures & AESTHETIC DENTISTRY P resurgical prosthetic planning is essential in delivering the restorative component to the patient following implant placement. This is particularly true when implants are to be loaded at the time of surgical placement. To determine proper fixture placement based on tooth posi- tion and occlusal demands, state-of-the-art diagnostic tools transfer the procedure to the virtual environment of a computer, where computed tomography (CT) imaging and three-dimensional assessment of the bone can be conducted. In this environment, optimal fixture positions should be chosen based on the restorative requirements Figure 1. Preoperative facial view of existing maxillary of the patient and the quantity and quality of the bone. metal-ceramic restoration. Gingival inflammation was Precise virtual planning can be ideally achieved when noted around the left central, left canine, and posterior a radiopaque representation of the desired occlusion in molar areas. the form of a CT or scannographic template is incorpo- rated intraorally during the CT scan.1-3 Stereolithographic models created from the CT software data set, combined with software-driven treatment planning, allow the fabri- cation of surgical templates that guide implants precisely to their desired positions. Utilizing advancements in imag- ing, diagnostic software application, and surgical tem- plates facilitates the entire procedure, reducing surgical chairtime and accelerating treatment. This article presents concepts that enable clinicians to simulate implant surgery on rapid prototype (RP) mod- els utilizing advanced surgical templates fabricated from Figure 2. Preoperative panoramic view of the patient’s CT scan treatment planning data. These templates are dentition and bone morphology. then used to guide the surgical placement of the implants in the same position as on the RP model. The resulting technique can be used to enhance surgical and restora- tive accuracy for predictable placement and immediate however, compared direct bone impression techniques loading of implants. to CAD/CAM-generated models for subperiosteal fab- rication and found variations in accuracy.6 McAllister sug- Background gested that stereolithography offered a higher degree Computed tomography has been used in fabricating of build accuracy and repeatability for subperiosteal exact replicas of the maxilla or mandible through implant manufacture.7 Webb reviewed the use of the RP stereolithography for almost two decades. Early utiliza- technique in the medical sector, concluding that the use tion was to eliminate the surgical bone impression phase of RP models was beneficial in terms of measurement of the subperiosteal implant modality.4,5 Cranin et al, and diagnostic accuracy.8 Figure 3. Four cross-sectional images with virtual implant and simulated abutment extension (depicted in yellow) were created with the imaging software. 764 Vol. 15, No. 10
  3. 3. GanzFigure 4. Axial three-dimensional volumetric view of max- Figure 6. The natural tooth roots as viewed withoutilla with four virtual implants. This model also permitted surrounding bone (via computer software). Note theevaluation of the anatomic site and other adjacent tooth mesial tilt of the premolar tooth.or root shapes. Technical Protocol A 55-year-old male presented with a failing maxillary 13-unit metal-ceramic fixed partial denture (FPD) (Figure 1). The left side of the arch contained a long- span FPD from tooth #11(23) to #13(25). Clinical and radiographic evaluation revealed decay at the margin of the mesially tilted #11 (Figure 2), which was easily penetrated with an explorer. The remaining metal- ceramic restoration was intact, with good marginal integrity for the abutments on teeth #3(16) through #10(22). The patient was informed that if the existingFigure 5. A dehiscence in the bone at tooth #11(23) was FPD was to be removed and the supporting abutmentsnoted. Loss of bone volume in the area of tooth #9(21)and diminished buccolingual width of the posterior found to be nonrestorable, a new fixed replacementalveolar crest was easily visualized on the 3D model. would not be possible due to lack of support. The patient’s principal desire was a fixed replacement as Most clinicians accept the necessity of transferring soon as possible, and he inquired as to the possibilitythe ideal tooth position to an accurate surgical guide. of using implants to support the maxillary left sideThis is generally accomplished by using a duplicate of without having to remove the existing FPD on the rightthe patient’s existing denture, or through the creation of side. From the initial panoramic radiograph, it appeareda diagnostic waxup that is replicated using radiopaque that sufficient vertical bone was present for implant place-barium sulfate, which allows for the tooth form to be vis- ment. Without three-dimensional imaging, however,ible on the CT image. Variations on this modality have little information could be obtained about the width, vol-been reported as clinicians sought to determine the miss- ume, or quality of the bone. The patient was thus referreding link that enabled a transfer of the treatment planning to a local radiologist for a C T series, specifically refor-analysis to the surgery.9 -11 Most solutions used surgical matted for use with computer-imaging software (SIM/steel drill guide tubes or a series of telescoping metal Plant, Materialise-CSI, Inc, Glen Burnie, MD). For thistubes to facilitate accuracy of the osteotomy.12,13 Some patient, a radiopaque template was not possible or nec-included all-acrylic templates that supplied enough infor- essary due to the existing metal-ceramic restoration.mation for the clinician to understand the desired implant The CT scan was evaluated in panoramic, axial,position in relation to the tooth replacement, but little and cross-sectional views utilizing the imaging software.about the condition of the recipient bone. Nevertheless, Implant receptor sites were determined for each cross-it was not until there was a connection between the sectional slice that would best align with the emergencetreatment planning data and the stereolithographic model profile of the four teeth to be replaced. Each cross-that the missing link was established.14-16 Thus, the use of section was evaluated based on the desired locationCT has evolved from a diagnostic tool for implant place- of the implant in relation to the tooth position and embra-ment to an integral part of the planning, surgical, and sure areas. Sufficient information was present fromrestorative phases of treatment. the existing metal-ceramic restoration to afford accurate PPAD 765
  4. 4. Practical Procedures & AESTHETIC DENTISTRY Figure 7. Utilizing the computer software, the four implants Figure 8. Three sequential-diameter templates were used, can be viewed independent of bone adjacent to tooth roots. each with 5-mm–high, stainless steel tubes. The tubes were 0.2 mm wider than the drill. Thus, a 2.3-mm pilot drill would require a 2.5-mm–diameter tube. Figure 9. Drilling of the stereolithographic model with the Figure10. Corresponding analogs were placed within aid of the template would serve as a precursor to the the model. The flats of the internal hexes were rotated actual surgical osteotomy. to the facial surface for prosthetic considerations. positioning of the simulated implant (Figure 3). The soft- they appeared buried in the bone model. This repre- ware allowed a manufacturer-specific implant to be sentation afforded the clinician with a better under- selected, and its corresponding shape was incorporated standing of the actual bone topography than did any of into the chosen slice along with an extension represent- the two-dimensional views. The implants were rotated ing the simulated abutment. The four potential receptor into the most favorable positions and transferred from sites were located and, once evaluated for volume of the two-dimensional cross-sectional view to the three- available bone, the implants were placed with their cor- dimensional volumetric model. The 3D imaging allowed responding abutment extensions. These initial determi- the author to avoid anatomical landmarks and neigh- nations were completed using only the two-dimensional boring tooth roots (Figure 5), to establish adequate inter- axial, panoramic, and cross-sectional views to bring implant distance, and to improve emergence profiles and the implant into a position where it would also support embrasures of the restoration. The ability to manipulate the desired tooth position, described by the author as the opacity of the model enabled the clinician to exam- the “Triangle of Bone.” 17 Each potential receptor site was ine the implants in relation to the residual tooth roots also evaluated for bone density using the Hounsfield (Figures 6 and 7). scale to further assess its potential for immediate load- The entire data set was e-mailed to the manufac- ing. This was important in deciding if there was ade- turer for the fabrication of a stereolithographic model of quate fixation to allow for traditional two-stage, one-stage, the patient’s maxilla and corresponding surgical template. immediate, or early loading of the implants. The CT scan data were used to generate a 3D computer The three-dimensional modeling allowed the clini- model of the maxilla. Based on this 3D model and the cian to visualize all aspects of the anatomical site and plan derived from the imaging software, surgical tem- the implant positions (Figure 4). The four implants were plates were developed to securely fit on the alveolar seen only through the abutment extensions (yellow), as bone and to exactly transfer position and angulation of 766 Vol. 15, No. 10
  5. 5. GanzFigure 11. On the stereolithographic model, fixture Figure 12. Occlusal view of the laboratory-processedmount transfers were prepared to the contours of the transitional restoration that would be used to protect thebone receptor sites. receptor sites and maintain the gingival architecture.Figure 13. The patient was anesthetized with local agents, Figure 14. The mesially inclined canine was extractedand the surgical site was exposed after sectioning of the using a periotome to minimize damage to the corticalexisting FPD. bone. Note the variation in bone contour.the planned implants. Both model and surgical templates a 4.7-mm–diameter implant (Tapered Screw-Vent,were built on a stereolithographic machine where a liq- Centerpulse Dental Division, Carlsbad, CA). A corre-uid acrylate was hardened in layers using UV light. After sponding internally hexed implant replica analog waspolymerization, the RP stereolithographic model was then then placed into each simulated osteotomy and securedused to fabricate the bone-borne templates (SurgiGuide, with light-cured acrylic resin (Figure 10). To facilitate theMaterialise-CSI, Glen Burnie, MD) used to position the attachment of the transitional restoration to the implantsimplants during insertion. To accommodate the drilling and to synchronize the position of the abutment withinsequence, several templates that corresponded to the the analog/implant, the flat of the internal hex wasmanufacturer’s guidelines for osteotomy preparation were rotated to the facial surface.fabricated (Figure 8) utilizing 5-mm–high stainless steel Titanium fixture mounts were prepared in advancetubes 0.2 mm wider than each drill.18 to conform to the tooth position and embrasure design A diagnostic waxup was completed for the purpose of the transitional restoration. The Tapered Screw-Ventof fabricating a processed acrylic transitional splint. The fixture mounts served three purposes: 1) as the implantexisting FPD would be sectioned at tooth #11, preserv-ing its remaining right side. The bone-borne templates carrier, 2) as an impression transfer post, and 3) as awere then utilized in a novel technique that simulated the prepable temporary abutment. Initially, each of the fourintraoral placement of the implants on the stereolitho- fixture mounts were grossly reduced using heatless stonesgraphic model of the maxilla. Osteotomies were created and then refined with titanium cutting laboratory bursdirectly on the RP resin models (Figure 9). The first, third, (eg, Ganz Abutment Preparation Kit, Brasseler USA,and fourth sites received 3.7-mm–diameter tapered Savannah, GA) until the desired shape was achievedimplants (Tapered Screw-Vent, Centerpulse Dental (Figure 11). The transitional restoration was then adaptedDivision, Carlsbad, CA). The second implant received to the abutments with light-cured acrylic resin (Figure 12). PPAD 767
  6. 6. Practical Procedures & AESTHETIC DENTISTRY Figure 15. The template (SurgiGuide, Materialise-CSI, Glen Figure 16. The template allows for precise osteotomy Burnie, MD) was placed securely onto the bone in an preparation. Due to the additional 5 mm of height of intimate fit without any movement or rocking. the stainless steel tubes, compensation was required to determine the osteotomy depths. Surgical Phase The long-span FPD was sectioned with a high-speed handpiece under copious irrigation. The left side was unattached to the residual roots due to marginal decay and was easily removed (Figure 13). A full-thickness, midcrestal incision and mucoperiosteal flap exposed the underlying alveolar crestal bone, and the mesially inclined canine was carefully extracted (Figure 14). All granula- tion tissue was curetted from the site. The remaining posterior molar was prepared and found to be satis- factory to retain as a terminal abutment. The templates were placed onto the bone to evaluate fit. If there was Figure 17. The second abutment was connected to its corresponding implant in accordance with the CT imaging, any soft tissue impingement, the flap was extended to software application, and surgical template. allow for intimate fit of the template (Figure 15). Osteotomies were prepared sequentially with the use of the bone-borne template (Figure 16). The implants were tissue working cast to help determine margin configuration subsequently placed without incident. for the anticipated custom abutments. The articulated mod- As in the stereolithographic model-simulated place- els and the original diagnostic waxup of the desired ment, each of the implants was rotated so that the flat restorative result were then scanned to create a “virtual of its internal hex was facing facially at the predeter- occlusion” from which virtual abutments (Atlantis Com- mined depth. This facilitated orientation of the previously ponents, Cambridge, MA) were designed (Figure 20). prepared abutments in the correct rotational and inter- The individual CAD/CAM designs were completed proximal position. Despite the bony defects at the according to the margin specifications as noted on the residual extraction site, the bone-borne template allowed laboratory prescription. The first three abutments were to predictable, accurate preparation of each osteotomy, be splinted and required parallelism for passive fit of the implant, and abutment (Figures 17 through 19). framework (Figure 21). The three virtual abutment data Additionally, the prepared abutment margins conformed sets were then sent to a CNC machine for processing to the shape of the bony topography. Prior to cementa- (Figure 22). The fourth abutment was for the canine, which tion of the temporary prosthesis but after primary closure, was fabricated using a standard custom-cast post technique. a fixture-level impression was taken to capture the posi- After 8 weeks of healing, the provisional restoration tion of the implants and the soft tissue in the sutured was removed. The implants were nonmobile and inte- position. A bite registration was completed, and the grated, and the soft tissue had matured to conform to the restoration was cemented. emergence profile of the transitional restoration. The pre- pared transfer post abutments were easily removed. To Restorative Phase ensure the patented friction-fit for the computer-milled abut- The patient healed without incident during the first month. ments, titanium blanks were provided by the manufac- The fixture-level impression was used to fabricate a soft- turer (Centerpulse Dental Division, Carlsbad, CA). The 768 Vol. 15, No. 10
  7. 7. GanzFigure 18. Clinical view of all four implants and titanium Figure 20. Facial view in centric relation position.abutments placed to support the transitional restoration. Occlusion was evaluated, and all contacts were removedNote how the margins of the abutments conform to for lateral, protrusive, and working movements.the shape of the bony topography. evaluation of the bone and simulated placement of implants. As advocated by the author, when a barium sul- fate radiopaque CT template is utilized (representing fully contoured tooth morphology), additional planning for abutment type within the confines of the individual tooth position can be achieved with unparalleled accuracy.17-19 The primary criticism of this technology, however, has been in translating the simulated plan to the patient at the time of surgical intervention. The introduction of stereolithographic RP models and resultant surgical tem- plates merges technology with reality, bringing the planFigure 19. Facial view of the laboratory-processed directly to the surgical site.14,16 The use of CT-derived tem-transitional restoration and soft tissue adaptation at plates fabricated to incorporate simulated virtual implanttime of implant insertion. placement gives the surgeon an efficient, accurate mech- anism for creating osteotomies within a high degree ofcomputer-milled abutments were then delivered to the correlation to the original plan, diminishing surgical timepatient, and the temporary splint was relined to seal the as well as reducing the length of osseous exposure.20new margins. The duplicate abutments were then utilized Immediate load protocols require adequate hoston the master working cast as the die for the fabrication bone as well as evaluation of the occlusion, an appro-of the cast coping. A separate coping was cast for the priate implant design that maximizes bone fixation andnatural molar tooth, and the custom cast post was cre- osseocompression, secure connection between implantated for the canine implant. Two weeks after the abut- and abutment to avoid micromovement, and accuratements were delivered, the cast copings were evaluated surgical guidance. The patient’s bone anatomy wasintraorally for fit. Three weeks later, the bisque bake of evaluated and found to be acceptable in volume andporcelain was evaluated for function and aesthetics. density in terms of Hounsfield units, a determination thatUpon patient approval, the final case was delivered can be successfully assessed presurgically from CT scantwo weeks later (Figures 23 through 25). data, differentiating this imaging modality from linear tomography.19 Specific implants were chosen based uponDiscussion surface design features, mechanical stability, and thePresurgical prosthetic planning is the foundation for internal friction-fit connection of the abutments.21 In accor-successful immediate loading of implants. Positioning the dance with the planning software, four implants wereimplant in terms of the functional and aesthetic demands then virtually placed in positions to maximize an imme-of the tooth is difficult due to limitations inherent with the diate loading protocol.most common two-dimensional imaging techniques. Surgical templates of various designs have beenComputed tomography and sophisticated diagnostic soft- utilized to accurately position implants according to theware provide clinicians with an enhanced vision of patient’s restorative demands. Computed tomography-bone anatomy. Such software applications permit an derived templates have been found to be more accurate PPAD 769
  8. 8. Practical Procedures & AESTHETIC DENTISTRY Figure 21. Maxillary model is depicted with three virtual Figure 23. Lateral view of three computer-milled abut- abutments for the pending implant-supported restorations. ments and molar die on working cast. Duplicate abutments were milled for each of the original abutments. Figure 22. Image demonstrates the designs for the virtual Figure 24. The definitive restorations (four implant- CAD/CAM-generated abutments (Atlantis Components, supported units, and the full-coverage gold crown Cambridge, MA). on the natural molar) were delivered 15 weeks after implant placement. than other methods, including the use of the SurgiGuide the tooth-specific shapes of the missing dentition. The protocol.13,20,22 This presentation describes a novel virtual abutment design process allowed for precise fab- approach where the stereolithographic replica of the rication of each original abutment and its duplicate as patient’s maxilla served as the receptor site for the implant well as for parallelism that ensured the passive fit of the replica analogs. This differs from other methods described prosthesis. The original abutments were then used intra- in the literature that utilize stone casts created from impres- orally after integration was initially achieved to help with sions of the patient’s dentition or diagnostic waxup. The the continued soft tissue maturation around the transi- analogs were placed into the stereolithographic model tional restoration. The duplicate abutments were utilized as guided by the prefabricated template processed from as dies on the same working cast that was created from the software treatment plan data set. This allowed for the the initial fixture-level impression at the time of surgery fabrication of milled provisional titanium abutments and to fabricate the metal-ceramic copings. Therefore, the laboratory-processed transitional restoration prior to the laboratory had precise control of the coping fit, as the surgical procedure. The ability to thoroughly assess the die was the actual abutment. Utilizing CAD/CAM tech- existing bone anatomy and plan for both surgical and nology enabled the restorative phase to be completed restorative phases enabled the procedure to be performed with the highest degree of accuracy with a minimal num- with confidence. The result was decreased surgical time, ber of impressions and office visits.23 improved restorative efficiency, and a highly accurate predictable method for immediate loading protocols. Conclusion During the eight-week healing phase, a working Implant dentistry has expanded to include advancements cast that contained analogs replicating the intraoral in computer-based imaging technology. This presenta- implant positions was created. Using a diagnostic tion demonstrated an expanded use of stereolithographic waxup, computer-milled abutments were created to meet models in the presurgical phase, which is of utmost 770 Vol. 15, No. 10
  9. 9. Ganz References 1. Basten CH. The use of radiopaque templates for predictable implant placement. Quint Int 1995;26(9):609-612. 2. Basten CH, Kois JC. The use of barium sulfate for implant tem- plates. J Prosthet Dent 1996;76(4):451-454. 3. Amet EM, Ganz SD. Implant treatment planning using a patient acceptance prosthesis, radiographic record base, and surgical template. Part 1: Presurgical phase. Impl Dent 1997;6(3): 193-197. 4. Golec TS. CAD-CAM multiplanar diagnostic imaging for sub- periosteal implants. Dent Clin North Am 1986;30(1):85-95. 5. Truitt HP, James RA, Lindley PE, Boyne P. Morphologic replica- tion of the mandible using computerized tomography for the fab- rication of a subperiosteal implant. Oral Surg Oral Med Oral Pathol 1988;65(5):499-504. 6. Cranin AN, Klein M, Ley JP, et al. An in vitro comparison of the computerized tomography/CAD-CAM and direct bone impres- sion techniques for subperiosteal implant model generation. J Oral Implantol 1998;24(2):74-79. 7. McAllister ML. Application of stereolithography to subperiosteal implant manufacture. J Oral Implantol 1998;24(2):89-92. 8. Webb PA. A review of rapid prototyping (RP) techniques in the medical and biomedical sector. J Med Eng Technol 2000; 24(4):149-153. 9. Klein M, Cranin AN, Sirakian A. A computerized tomography (CT) scan appliance for optimal presurgical and preprosthetic planning of the implant patient. Pract Periodont Aesthet Dent 1993;5(6):33-39. 10. Verde MA, Morgano SM. A dual-purpose stent for the implant-Figure 25. Postoperative radiograph of the anterior supported prosthesis. J Prosthet Dent 1993;69(3):276-280.implants four months following case completion. 11. Weinberg LA, Kruger B. Three-dimensional guidance system forThe apparent overlap is an artifact of the arch implant insertion: Part II. Dual axes table — Problem solving. Impl Dent 1999;8(3):255-264.curvature and film placement. 12. Mizrahi B, Thunthy KH, Finger I. Radiographic/surgical tem- plate incorporating metal telescopic tubes for accurate implant placement. Pract Periodont Aesthet Dent 1998;10(6):757-765.importance for immediate provisionalization protocols. 13. Besimo CE, Lambrecht JT, Guindy JS. Accuracy of implant treat-The described technique enables a more complete under- ment planning utilizing template-guided reformatted computedstanding of the ultimate prosthetic goal in anticipation tomography. Dent Maxillofac Radiol 2000;29(1):46-51. 14. Klein M, Abrams M. Computer-guided surgery utilizing a com-of implant support. The surgical placement of the implants puter-milled surgical template. Pract Proced Aesthet Dent 2001;guided by the precise treatment plan through the appli- 13(2):165-169.cation of the template was followed by the immediate 15. Vrielinck L, Politis C, Schepers S, et al. Image-based planning and clinical validation of zygoma and pterygoid implant place-placement of transmucosal abutments and transitional ment in patients with severe bone atrophy using customizedrestorations. The methodologies as described reduced drill guides. Preliminary results from a prospective clinical follow- up study. Int J Oral Maxillofac Surg 2003;32(1):7-14.surgical chairtime and the number of involved restorative 16. Tardieu PB, Vrielinck L, Escolano, E. Computer-assisted implantsteps, and accelerated treatment phases, ultimately placement. A case report: Treatment of the mandible. Int J Oral Maxillofac Impl 2003;18(4):599-604.achieving the expectations of both clinician and patient. 17. Ganz SD. The triangle of bone — A formula for successful implant As immediate loading protocols gain momentum in placement and restoration. The Implant Society Inc 1995;5(5):accelerating treatment times closer to those of conventional 2-6.prosthodontics, CT scan treatment planning and CT-derived 18. Ganz SD. CT scan technology — An evolving tool for predictable implant placement and restoration. Int Mag Oral Implantol 2001;template design become a necessary diagnostic and sur- 1: 6 -13.gical tool to understand anatomy, identify pathology, 19. Norton MR, Gamble C. Bone classification: An objective scale of bone density using the computerized tomography scan.avoid complications, and to ensure predictability and Clin Oral Impl Res 2001;12(1) : 79-84.long-term success. Additional research will be required 20. Sarment DP, Sukovic P, Clinthorne N. Accuracy of implant place-to confirm the protocol as described herein. ment with a stereolithographic surgical guide. Int J Oral Maxillofac Impl 2003;18(4):571-577 . 21. Arlin ML. Analysis of 435 Screw-Vent dental implants placed inAcknowledgment 161 patients: Software enhancement of clinical evaluation. Impl Dent 2002;11(1):58-66.The author declares that he is a consultant for Materialise- 22. Naitoh M, Ariji E, Okumura S, et al. Can implants be correctlyCSI and Atlantis Components and that he lectures angulated based on surgical templates used for osseointegratedon behalf of Centerpulse Dental Division. He receives dental implants? Clin Oral Impl Res 2000;11:409-414. 23. Ganz SD. Computer-milled patient-specific abutments: Incredibleno financial benefit from the sale of any product refer- simplicity with unprecedented simplicity. Pract Proced Aesthetenced herein. Dent 2003;15(Suppl 8):37- 44. PPAD 771
  10. 10. CONTINUING EDUCATION CE 30 CONTINUING EDUCATION(CE) EXERCISE NO. 30To submit your CE Exercise answers, please use the answer sheet found within the CE Editorial Section of this issue andcomplete as follows: 1) Identify the article; 2) Place an X in the appropriate box for each question of each exercise; 3) Clipanswer sheet from the page and mail it to the CE Department at Montage Media Corporation. For further instructions,please refer to the CE Editorial Section.The 10 multiple-choice questions for this Continuing Education (CE) exercise are based on the article, “Use of stereolitho-graphic models as diagnostic and restorative aids for predictable immediate loading of implants,” by Scott D. Ganz,DMD. This article is on pages 763-771. 1. Presurgical, prosthetic planning is essential 6. Which of the following characteristics of bone in delivering the restorative component to the is practically unobtainable without the use of patient following implant placement. This is 3D imaging? particularly true when implants are to be loaded a. Quality. at a separate time from surgical placement. b. Volume. a. Both statements are true. c. Width. b. Both statements are false. d. All of the above. c. The first statement is true, the second statement is false. 7. In the author’s opinion, CT and sophisticated d. The first statement is false, the second diagnostic software permit: statement is true. a. Bone evaluation. b. Implant placement simulation. 2. Varying designs of surgical templates have c. The enhancement of bone anatomy been fabricated to help: visualization. a. Determine proper fixture placement based d. All of the above. upon restorative demands. b. Allow the restorative clinician to assess the 8. What is the primary criticism surrounding quality of bone. the use of CT technology? c. Position the temporary prosthesis properly. a. The translation of simulated plans to the d. All of the above. patient at surgical intervention. 3. For correct transfer of ideal tooth position, b. Increased surgical time. clinicians often use: c. Poor determination of bone quality. a. The patient’s existing denture. d. Difficult to master. b. A diagnostic waxup. c. Both a and b. 9. The use of stereolithographic models guided d. Neither a nor b. by CT-derived templates aid implant placement through: 4. How long has CT been used to fabricate a. Improved restorative efficiency. replicas of the maxilla and mandible through b. Provision of an accurate method for stereolithography? immediate loading protocols. a. ~ 8 years. c. Both a and b. b. ~ 10 years. d. Neither a nor b. c. ~ 15 years. d. ~ 20 years. 10. In what way did 3D imaging aid the author 5. The use of CT is an integral part of which during implant placement? treatment phase? a. It established adequate interimplant distance. a. Planning. b. It allowed for improved emergence profile. b. Surgical. c. Anatomical landmarks and neighboring tooth c. Restorative. roots could be avoided. d. All of the above. d. All of the above.772 Vol. 15, No. 9