USE OF STEREOLITHOGRAPHIC MODELS AS

DIAGNOSTIC AND RESTORATIVE AIDS FOR

PREDICTABLE IMMEDIATE LOADING OF IMPLANTSScott D. Ganz, DMD*

Pract Proced Aesthet Dent 2003;15(10):763-771 763

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 advancedsurgical 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

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*Private practice, Fort Lee, NJ.

Scott D. Ganz, DMD, 158 Linwood Plaza, Suite 204, Fort Lee, NJ 07024Tel: 201-592-8888 • Fax: 201-592-8821 • E-mail: sdgimplant@aol.com

C O N T I N U I N G E D U C A T I O N 3 0

Presurgical prosthetic planning is essential in deliveringthe restorative component to the patient following

implant placement. This is particularly true when implantsare to be loaded at the time of surgical placement. Todetermine proper fixture placement based on tooth posi-tion and occlusal demands, state-of-the-art diagnostictools transfer the procedure to the virtual environment ofa computer, where computed tomography (CT) imagingand three-dimensional assessment of the bone can beconducted. In this environment, optimal fixture positionsshould be chosen based on the restorative requirementsof the patient and the quantity and quality of the bone.Precise virtual planning can be ideally achieved whena radiopaque representation of the desired occlusion inthe form of a CT or scannographic template is incorpo-rated intraorally during the CT scan.1-3 Stereolithographicmodels created from the CT software data set, combinedwith software-driven treatment planning, allow the fabri-cation of surgical templates that guide implants preciselyto their desired positions. Utilizing advancements in imag-ing, diagnostic software application, and surgical tem-plates facilitates the entire procedure, reducing surgicalchairtime and accelerating treatment.

This article presents concepts that enable cliniciansto simulate implant surgery on rapid prototype (RP) mod-els utilizing advanced surgical templates fabricated fromCT scan treatment planning data. These templates arethen used to guide the surgical placement of the implantsin the same position as on the RP model. The resultingtechnique can be used to enhance surgical and restora-tive accuracy for predictable placement and immediateloading of implants.

BackgroundComputed tomography has been used in fabricatingexact replicas of the maxilla or mandible throughstereolithography for almost two decades. Early utiliza-tion was to eliminate the surgical bone impression phaseof the subperiosteal implant modality.4,5 Cranin et al,

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Figure 1. Preoperative facial view of existing maxillarymetal-ceramic restoration. Gingival inflammation wasnoted around the left central, left canine, and posteriormolar areas.

Figure 2. Preoperative panoramic view of the patient’sdentition and bone morphology.

Figure 3. Four cross-sectional images with virtual implant and simulated abutment extension (depicted in yellow) were createdwith the imaging software.

however, compared direct bone impression techniquesto CAD/CAM-generated models for subperiosteal fab-rication and found variations in accuracy.6 McAllister sug-gested that stereolithography offered a higher degreeof build accuracy and repeatability for subperiostealimplant manufacture.7 Webb reviewed the use of the RPtechnique in the medical sector, concluding that the useof RP models was beneficial in terms of measurementand diagnostic accuracy.8

Most clinicians accept the necessity of transferringthe ideal tooth position to an accurate surgical guide.This is generally accomplished by using a duplicate ofthe patient’s existing denture, or through the creation ofa diagnostic waxup that is replicated using radiopaquebarium sulfate, which allows for the tooth form to be vis-ible on the CT image. Variations on this modality havebeen reported as clinicians sought to determine the miss-ing link that enabled a transfer of the treatment planninganalysis to the surgery.9 -11 Most solutions used surgicalsteel drill guide tubes or a series of telescoping metaltubes to facilitate accuracy of the osteotomy.12,13 Someincluded all-acrylic templates that supplied enough infor-mation for the clinician to understand the desired implantposition in relation to the tooth replacement, but littleabout the condition of the recipient bone. Nevertheless,it was not until there was a connection between thetreatment planning data and the stereolithographic modelthat the missing link was established.14-16 Thus, the use ofCT has evolved from a diagnostic tool for implant place-ment to an integral part of the planning, surgical, andrestorative phases of treatment.

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Figure 4. Axial three-dimensional volumetric view of max-illa with four virtual implants. This model also permittedevaluation of the anatomic site and other adjacent toothor root shapes.

Figure 5. A dehiscence in the bone at tooth #11(23) wasnoted. Loss of bone volume in the area of tooth #9(21)and diminished buccolingual width of the posterioralveolar crest was easily visualized on the 3D model.

Figure 6. The natural tooth roots as viewed withoutsurrounding bone (via computer software). Note themesial tilt of the premolar tooth.

Technical ProtocolA 55-year-old male presented with a failing maxillary13-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 andradiographic evaluation revealed decay at the marginof the mesially tilted #11 (Figure 2), which was easilypenetrated with an explorer. The remaining metal-ceramic restoration was intact, with good marginalintegrity for the abutments on teeth #3(16) through#10(22). The patient was informed that if the existingFPD was to be removed and the supporting abutmentsfound to be nonrestorable, a new fixed replacementwould not be possible due to lack of support. Thepatient’s principal desire was a fixed replacement assoon as possible, and he inquired as to the possibilityof using implants to support the maxillary left sidewithout having to remove the existing FPD on the rightside. From the initial panoramic radiograph, it appearedthat sufficient vertical bone was present for implant place-ment. Without three-dimensional imaging, however,little information could be obtained about the width, vol-ume, or quality of the bone. The patient was thus referredto a local radiologist for a CT series, specifically refor-matted for use with computer-imaging software (SIM/Plant, Materialise-CSI, Inc, Glen Burnie, MD). For thispatient, a radiopaque template was not possible or nec-essary due to the existing metal-ceramic restoration.

The CT scan was evaluated in panoramic, axial,and cross-sectional views utilizing the imaging software.Implant receptor sites were determined for each cross-sectional slice that would best align with the emergenceprofile of the four teeth to be replaced. Each cross-section was evaluated based on the desired locationof the implant in relation to the tooth position and embra-sure areas. Sufficient information was present fromthe existing metal-ceramic restoration to afford accurate

positioning of the simulated implant (Figure 3). The soft-ware allowed a manufacturer-specific implant to beselected, and its corresponding shape was incorporatedinto the chosen slice along with an extension represent-ing the simulated abutment. The four potential receptorsites were located and, once evaluated for volume ofavailable bone, the implants were placed with their cor-responding abutment extensions. These initial determi-nations were completed using only the two-dimensionalaxial, panoramic, and cross-sectional views to bringthe implant into a position where it would also supportthe desired tooth position, described by the author asthe “Triangle of Bone.”17 Each potential receptor site wasalso evaluated for bone density using the Hounsfieldscale to further assess its potential for immediate load-ing. This was important in deciding if there was ade-quate fixation to allow for traditional two-stage, one-stage,immediate, or early loading of the implants.

The three-dimensional modeling allowed the clini-cian to visualize all aspects of the anatomical site andthe implant positions (Figure 4). The four implants wereseen only through the abutment extensions (yellow), as

they appeared buried in the bone model. This repre-sentation afforded the clinician with a better under-standing of the actual bone topography than did any ofthe two-dimensional views. The implants were rotatedinto the most favorable positions and transferred fromthe two-dimensional cross-sectional view to the three-dimensional volumetric model. The 3D imaging allowedthe author to avoid anatomical landmarks and neigh-boring tooth roots (Figure 5), to establish adequate inter-implant distance, and to improve emergence profiles andembrasures of the restoration. The ability to manipulatethe opacity of the model enabled the clinician to exam-ine the implants in relation to the residual tooth roots(Figures 6 and 7).

The entire data set was e-mailed to the manufac-turer for the fabrication of a stereolithographic model ofthe patient’s maxilla and corresponding surgical template.The CT scan data were used to generate a 3D computermodel of the maxilla. Based on this 3D model and theplan derived from the imaging software, surgical tem-plates were developed to securely fit on the alveolarbone and to exactly transfer position and angulation of

Figure 7. Utilizing the computer software, the four implantscan be viewed independent of bone adjacent to tooth roots.

Figure 8. Three sequential-diameter templates were used,each with 5-mm–high, stainless steel tubes. The tubes were0.2 mm wider than the drill. Thus, a 2.3-mm pilot drillwould require a 2.5-mm–diameter tube.

Figure 9. Drilling of the stereolithographic model with theaid of the template would serve as a precursor to theactual surgical osteotomy.

Figure10. Corresponding analogs were placed withinthe model. The flats of the internal hexes were rotatedto the facial surface for prosthetic considerations.

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the planned implants. Both model and surgical templateswere built on a stereolithographic machine where a liq-uid acrylate was hardened in layers using UV light. Afterpolymerization, the RP stereolithographic model was thenused to fabricate the bone-borne templates (SurgiGuide,Materialise-CSI, Glen Burnie, MD) used to position theimplants during insertion. To accommodate the drillingsequence, several templates that corresponded to themanufacturer’s guidelines for osteotomy preparation werefabricated (Figure 8) utilizing 5-mm–high stainless steeltubes 0.2 mm wider than each drill.18

A diagnostic waxup was completed for the purposeof fabricating a processed acrylic transitional splint. Theexisting FPD would be sectioned at tooth #11, preserv-ing its remaining right side. The bone-borne templateswere then utilized in a novel technique that simulated theintraoral placement of the implants on the stereolitho-graphic model of the maxilla. Osteotomies were createddirectly on the RP resin models (Figure 9). The first, third,and fourth sites received 3.7-mm–diameter taperedimplants (Tapered Screw-Vent, Centerpulse DentalDivision, Carlsbad, CA). The second implant received

a 4.7-mm–diameter implant (Tapered Screw-Vent,Centerpulse Dental Division, Carlsbad, CA). A corre-sponding internally hexed implant replica analog wasthen placed into each simulated osteotomy and securedwith light-cured acrylic resin (Figure 10). To facilitate theattachment of the transitional restoration to the implantsand to synchronize the position of the abutment withinthe analog/implant, the flat of the internal hex wasrotated to the facial surface.

Titanium fixture mounts were prepared in advanceto conform to the tooth position and embrasure designof the transitional restoration. The Tapered Screw-Ventfixture mounts served three purposes: 1) as the implantcarrier, 2) as an impression transfer post, and 3) as aprepable temporary abutment. Initially, each of the fourfixture mounts were grossly reduced using heatless stonesand then refined with titanium cutting laboratory burs(eg, Ganz Abutment Preparation Kit, Brasseler USA,Savannah, GA) until the desired shape was achieved(Figure 11). The transitional restoration was then adaptedto the abutments with light-cured acrylic resin (Figure 12).

Figure 11. On the stereolithographic model, fixturemount transfers were prepared to the contours of thebone receptor sites.

Figure 12. Occlusal view of the laboratory-processedtransitional restoration that would be used to protect thereceptor sites and maintain the gingival architecture.

Figure 13. The patient was anesthetized with local agents,and the surgical site was exposed after sectioning of theexisting FPD.

Figure 14. The mesially inclined canine was extractedusing a periotome to minimize damage to the corticalbone. Note the variation in bone contour.

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Surgical Phase The long-span FPD was sectioned with a high-speedhandpiece under copious irrigation. The left side wasunattached to the residual roots due to marginal decayand was easily removed (Figure 13). A full-thickness,midcrestal incision and mucoperiosteal flap exposed theunderlying alveolar crestal bone, and the mesially inclinedcanine was carefully extracted (Figure 14). All granula-tion tissue was curetted from the site. The remainingposterior molar was prepared and found to be satis-factory to retain as a terminal abutment. The templateswere placed onto the bone to evaluate fit. If there wasany soft tissue impingement, the flap was extended toallow for intimate fit of the template (Figure 15).Osteotomies were prepared sequentially with the use ofthe bone-borne template (Figure 16). The implants weresubsequently placed without incident.

As in the stereolithographic model-simulated place-ment, each of the implants was rotated so that the flatof its internal hex was facing facially at the predeter-mined depth. This facilitated orientation of the previouslyprepared abutments in the correct rotational and inter-proximal position. Despite the bony defects at theresidual extraction site, the bone-borne template allowedpredictable, accurate preparation of each osteotomy,implant, and abutment (Figures 17 through 19).Additionally, the prepared abutment margins conformedto the shape of the bony topography. Prior to cementa-tion of the temporary prosthesis but after primary closure,a fixture-level impression was taken to capture the posi-tion of the implants and the soft tissue in the suturedposition. A bite registration was completed, and therestoration was cemented.

Restorative PhaseThe patient healed without incident during the first month.The fixture-level impression was used to fabricate a soft-

tissue working cast to help determine margin configurationfor the anticipated custom abutments. The articulated mod-els and the original diagnostic waxup of the desiredrestorative result were then scanned to create a “virtualocclusion” from which virtual abutments (Atlantis Com-ponents, Cambridge, MA) were designed (Figure 20).The individual CAD/CAM designs were completedaccording to the margin specifications as noted on thelaboratory prescription. The first three abutments were tobe splinted and required parallelism for passive fit of theframework (Figure 21). The three virtual abutment datasets were then sent to a CNC machine for processing(Figure 22). The fourth abutment was for the canine, whichwas fabricated using a standard custom-cast post technique.

After 8 weeks of healing, the provisional restorationwas removed. The implants were nonmobile and inte-grated, and the soft tissue had matured to conform to theemergence profile of the transitional restoration. The pre-pared transfer post abutments were easily removed. Toensure the patented friction-fit for the computer-milled abut-ments, titanium blanks were provided by the manufac-turer (Centerpulse Dental Division, Carlsbad, CA). The

Figure 15. The template (SurgiGuide, Materialise-CSI, GlenBurnie, MD) was placed securely onto the bone in anintimate fit without any movement or rocking.

Figure 16. The template allows for precise osteotomypreparation. Due to the additional 5 mm of height ofthe stainless steel tubes, compensation was required todetermine the osteotomy depths.

Figure 17. The second abutment was connected to itscorresponding implant in accordance with the CT imaging,software application, and surgical template.

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computer-milled abutments were then delivered to thepatient, and the temporary splint was relined to seal thenew margins. The duplicate abutments were then utilizedon the master working cast as the die for the fabricationof the cast coping. A separate coping was cast for thenatural molar tooth, and the custom cast post was cre-ated for the canine implant. Two weeks after the abut-ments were delivered, the cast copings were evaluatedintraorally for fit. Three weeks later, the bisque bake ofporcelain was evaluated for function and aesthetics.Upon patient approval, the final case was deliveredtwo weeks later (Figures 23 through 25).

DiscussionPresurgical prosthetic planning is the foundation forsuccessful immediate loading of implants. Positioning theimplant in terms of the functional and aesthetic demandsof the tooth is difficult due to limitations inherent with themost common two-dimensional imaging techniques.Computed tomography and sophisticated diagnostic soft-ware provide clinicians with an enhanced vision ofbone anatomy. Such software applications permit an

evaluation of the bone and simulated placement ofimplants. As advocated by the author, when a barium sul-fate radiopaque CT template is utilized (representing fullycontoured tooth morphology), additional planning forabutment type within the confines of the individual toothposition can be achieved with unparalleled accuracy.17-19

The primary criticism of this technology, however,has been in translating the simulated plan to the patientat the time of surgical intervention. The introduction ofstereolithographic RP models and resultant surgical tem-plates merges technology with reality, bringing the plandirectly to the surgical site.14,16 The use of CT-derived tem-plates fabricated to incorporate simulated virtual implantplacement gives the surgeon an efficient, accurate mech-anism for creating osteotomies within a high degree ofcorrelation to the original plan, diminishing surgical timeas well as reducing the length of osseous exposure.20

Immediate load protocols require adequate hostbone as well as evaluation of the occlusion, an appro-priate implant design that maximizes bone fixation andosseocompression, secure connection between implantand abutment to avoid micromovement, and accuratesurgical guidance. The patient’s bone anatomy wasevaluated and found to be acceptable in volume anddensity in terms of Hounsfield units, a determination thatcan be successfully assessed presurgically from CT scandata, differentiating this imaging modality from lineartomography.19 Specific implants were chosen based uponsurface design features, mechanical stability, and theinternal friction-fit connection of the abutments.21 In accor-dance with the planning software, four implants werethen virtually placed in positions to maximize an imme-diate loading protocol.

Surgical templates of various designs have beenutilized to accurately position implants according to thepatient’s restorative demands. Computed tomography-derived templates have been found to be more accurate

Figure 18. Clinical view of all four implants and titaniumabutments placed to support the transitional restoration.Note how the margins of the abutments conform tothe shape of the bony topography.

Figure 20. Facial view in centric relation position.Occlusion was evaluated, and all contacts were removedfor lateral, protrusive, and working movements.

Figure 19. Facial view of the laboratory-processedtransitional restoration and soft tissue adaptation attime of implant insertion.

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than other methods, including the use of the SurgiGuideprotocol.13,20,22 This presentation describes a novelapproach where the stereolithographic replica of thepatient’s maxilla served as the receptor site for the implantreplica analogs. This differs from other methods describedin the literature that utilize stone casts created from impres-sions of the patient’s dentition or diagnostic waxup. Theanalogs were placed into the stereolithographic modelas guided by the prefabricated template processed fromthe software treatment plan data set. This allowed for thefabrication of milled provisional titanium abutments andlaboratory-processed transitional restoration prior to thesurgical procedure. The ability to thoroughly assess theexisting bone anatomy and plan for both surgical andrestorative phases enabled the procedure to be performedwith confidence. The result was decreased surgical time,improved restorative efficiency, and a highly accuratepredictable method for immediate loading protocols.

During the eight-week healing phase, a workingcast that contained analogs replicating the intraoralimplant positions was created. Using a diagnosticwaxup, computer-milled abutments were created to meet

the tooth-specific shapes of the missing dentition. Thevirtual abutment design process allowed for precise fab-rication of each original abutment and its duplicate aswell as for parallelism that ensured the passive fit of theprosthesis. The original abutments were then used intra-orally after integration was initially achieved to help withthe continued soft tissue maturation around the transi-tional restoration. The duplicate abutments were utilizedas dies on the same working cast that was created fromthe initial fixture-level impression at the time of surgeryto fabricate the metal-ceramic copings. Therefore, thelaboratory had precise control of the coping fit, as thedie was the actual abutment. Utilizing CAD/CAM tech-nology enabled the restorative phase to be completedwith the highest degree of accuracy with a minimal num-ber of impressions and office visits.23

Conclusion Implant dentistry has expanded to include advancementsin computer-based imaging technology. This presenta-tion demonstrated an expanded use of stereolithographicmodels in the presurgical phase, which is of utmost

Figure 21. Maxillary model is depicted with three virtualabutments for the pending implant-supported restorations.

Figure 22. Image demonstrates the designs for the virtualCAD/CAM-generated abutments (Atlantis Components,Cambridge, MA).

Figure 23. Lateral view of three computer-milled abut-ments and molar die on working cast. Duplicate abutmentswere milled for each of the original abutments.

Figure 24. The definitive restorations (four implant-supported units, and the full-coverage gold crownon the natural molar) were delivered 15 weeks afterimplant placement.

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importance for immediate provisionalization protocols.The described technique enables a more complete under-standing of the ultimate prosthetic goal in anticipationof implant support. The surgical placement of the implantsguided by the precise treatment plan through the appli-cation of the template was followed by the immediateplacement of transmucosal abutments and transitionalrestorations. The methodologies as described reducedsurgical chairtime and the number of involved restorativesteps, and accelerated treatment phases, ultimatelyachieving the expectations of both clinician and patient.

As immediate loading protocols gain momentum inaccelerating treatment times closer to those of conventionalprosthodontics, CT scan treatment planning and CT-derivedtemplate design become a necessary diagnostic and sur-gical tool to understand anatomy, identify pathology,avoid complications, and to ensure predictability andlong-term success. Additional research will be requiredto confirm the protocol as described herein.

Acknowledgment The author declares that he is a consultant for Materialise-CSI and Atlantis Components and that he lectureson behalf of Centerpulse Dental Division. He receivesno financial benefit from the sale of any product refer-enced herein.

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Figure 25. Postoperative radiograph of the anteriorimplants four months following case completion. The apparent overlap is an artifact of the arch curvature and film placement.

References1. 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 surgicaltemplate. 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 OralPathol 1988;65(5):499-504.

6. Cranin AN, Klein M, Ley JP, et al. An in vitro comparison of thecomputerized 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 subperiostealimplant manufacture. J Oral Implantol 1998;24(2):89-92.

8. Webb PA. A review of rapid prototyping (RP) techniques in themedical 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 preprostheticplanning of the implant patient. Pract Periodont Aesthet Dent1993;5(6):33-39.

10. Verde MA, Morgano SM. A dual-purpose stent for the implant-supported prosthesis. J Prosthet Dent 1993;69(3):276-280.

11. Weinberg LA, Kruger B. Three-dimensional guidance system forimplant insertion: Part II. Dual axes table — Problem solving.Impl Dent 1999;8(3):255-264.

12. Mizrahi B, Thunthy KH, Finger I. Radiographic/surgical tem-plate incorporating metal telescopic tubes for accurate implantplacement. Pract Periodont Aesthet Dent 1998;10(6):757-765.

13. Besimo CE, Lambrecht JT, Guindy JS. Accuracy of implant treat-ment planning utilizing template-guided reformatted computedtomography. Dent Maxillofac Radiol 2000;29(1):46-51.

14. Klein M, Abrams M. Computer-guided surgery utilizing a com-puter-milled surgical template. Pract Proced Aesthet Dent 2001;13(2):165-169.

15. Vrielinck L, Politis C, Schepers S, et al. Image-based planningand clinical validation of zygoma and pterygoid implant place-ment in patients with severe bone atrophy using customizeddrill guides. Preliminary results from a prospective clinical follow-up study. Int J Oral Maxillofac Surg 2003;32(1):7-14.

16. Tardieu PB, Vrielinck L, Escolano, E. Computer-assisted implantplacement. A case report: Treatment of the mandible. Int J OralMaxillofac Impl 2003;18(4):599-604.

17. Ganz SD. The triangle of bone — A formula for successful implantplacement and restoration. The Implant Society Inc 1995;5(5):2-6.

18. Ganz SD. CT scan technology — An evolving tool for predictableimplant placement and restoration. Int Mag Oral Implantol 2001;1:6 -13.

19. Norton MR, Gamble C. Bone classification: An objective scaleof bone density using the computerized tomography scan.Clin Oral Impl Res 2001;12(1) :79-84.

20. Sarment DP, Sukovic P, Clinthorne N. Accuracy of implant place-ment with a stereolithographic surgical guide. Int J Oral MaxillofacImpl 2003;18(4):571-577.

21. Arlin ML. Analysis of 435 Screw-Vent dental implants placed in161 patients: Software enhancement of clinical evaluation. ImplDent 2002;11(1):58-66.

22. Naitoh M, Ariji E, Okumura S, et al. Can implants be correctlyangulated based on surgical templates used for osseointegrateddental implants? Clin Oral Impl Res 2000;11:409-414.

23. Ganz SD. Computer-milled patient-specific abutments: Incrediblesimplicity with unprecedented simplicity. Pract Proced AesthetDent 2003;15(Suppl 8):37-44.

1. Presurgical, prosthetic planning is essentialin delivering the restorative component to thepatient following implant placement. This isparticularly true when implants are to be loadedat a separate time from surgical placement.a. Both statements are true.b. Both statements are false.c. The first statement is true, the second statement

is false.d. The first statement is false, the second

statement is true.

2. Varying designs of surgical templates havebeen fabricated to help:a. Determine proper fixture placement based

upon restorative demands.b. Allow the restorative clinician to assess the

quality of bone.c. Position the temporary prosthesis properly.d. All of the above.

3. For correct transfer of ideal tooth position,clinicians often use:a. The patient’s existing denture.b. A diagnostic waxup.c. Both a and b.d. Neither a nor b.

4. How long has CT been used to fabricatereplicas of the maxilla and mandible throughstereolithography?a. ~ 8 years.b. ~ 10 years.c. ~ 15 years.d. ~ 20 years.

5. The use of CT is an integral part of whichtreatment phase?a. Planning.b. Surgical.c. Restorative.d. All of the above.

6. Which of the following characteristics of boneis practically unobtainable without the use of3D imaging?a. Quality.b. Volume.c. Width.d. All of the above.

7. In the author’s opinion, CT and sophisticateddiagnostic software permit:a. Bone evaluation.b. Implant placement simulation.c. The enhancement of bone anatomy

visualization.d. All of the above.

8. What is the primary criticism surroundingthe use of CT technology?a. The translation of simulated plans to the

patient at surgical intervention.b. Increased surgical time.c. Poor determination of bone quality.d. Difficult to master.

9. The use of stereolithographic models guidedby CT-derived templates aid implant placementthrough:a. Improved restorative efficiency.b. Provision of an accurate method for

immediate loading protocols.c. Both a and b.d. Neither a nor b.

10. In what way did 3D imaging aid the authorduring implant placement?a. It established adequate interimplant distance.b. It allowed for improved emergence profile.c. Anatomical landmarks and neighboring tooth

roots could be avoided.d. All of the above.

To submit your CE Exercise answers, please use the answer sheet found within the CE Editorial Section of this issue and

complete as follows: 1) Identify the article; 2) Place an X in the appropriate box for each question of each exercise; 3) Clip

answer 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.

CONTINUING EDUCATION

(CE) EXERCISE NO. 30CE

CONTINUING EDUCATION

30

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