CE 3-Siddiqui10_01


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CE 3-Siddiqui10_01

  1. 1. Immediate Loading of DentalImplants in the EdentulousMandible: A Preliminary CaseReport From an InternationalProspective Multicenter Study CE 3Abstract: The ability to predictably achieve long-term osseointegration in Azfar A. Siddiqui, DMD, BDS,patients with compromised anatomical resources has been demonstrated MScnumerous times in modern oral implantology. Recently, clinical attention has Assistant Professorfocused on new methods of reducing treatment time. One-stage surgical pro- Prosthodonticscedures and immediate loading of implants at the time of placement are two John Y.H. Ismail, DMD, PhDtechniques that have demonstrated promising clinical results. A prospective Chairmanclinical study of immediately splinting and loading a new, one-stage implant Prosthodonticsis currently in progress in the United States and France. An overview of the Steve Kukunas, DMD, MSimplant design and presentation of one case study from the University of Assistant Professor ProsthodonticsPittsburgh demonstrates how this promising technique is performed. School of Dental Medicine University of PittsburghA dvances in implant designs, biomaterials, and surgical techniques have Pittsburgh, Pennsylvania extended the benefits of root-form dental implants to many patients who were previously excluded as suitable candidates. Narrow, resorbedridges, immediate extraction sites, and ridges with labial undercuts or conver- Learning Objectives:gent tooth roots can often be successfully treated with new, tapered implantdesigns.1 For patients with poor bone quality, advances in hydroxyapatite (HA) After reading this article, the reader should be able to:coatings2-3 and microtextured titanium surfaces4-5 may offer improved prognosesof long-term implant success. One-stage surgical procedures have successfully • explain the steps for placing and immediatelyeliminated second-stage surgery with excellent clinical results,6-10 which there- loading four one-stageby avoids the physical trauma and chair time of the uncovering procedure. A implants in the edentulouschallenge that still confronts dentists and patients alike, however, is the tradi- mandible with a bartional lag time between implant placement and prosthetic loading. overdenture restoration. Originally, the Brånemarka surgical protocol11 stipulated that dental implants • discuss the rationale forwere to be submerged beneath the soft tissue at the time of placement, and developing differentallowed to heal for a minimum of 3 months in the mandible and 6 months in the surgical protocols based on bone density.maxilla to achieve osseointegration.11 Patients were also required to refrain fromwearing a denture in the lowerjaw for 2 weeks after implant placement to facili- • identify some of the research that supports thetate soft tissue healing.11 The denture was then relieved over the surgical area and immediate loading concept.relined with a soft material, which had to be replaced every 3 to 4 weeks.11 A per-manent reline with acrylic resin was only permitted at 5 weeks postoperative.11After the submerged healing period, a second surgery to uncover the implants wasrequired, followed by 2 additional weeks of soft tissue healing before restorativeprocedures could begin.11 It is not known how many patients may have been dis-couraged from selecting dental implant therapy as a result of the lag time betweenimplant placement and delivery of the final prosthesis. Recent studies have doc-umented the successful immediate loading of one-piece12-14 and two-piece15-17implant designs. While some researchers caution that immediate loading of den-tal implants should be limited to the interforamina region of the symphysis inedentulous mandibles,18 others report high clinical success rates of immediatelyloaded implants in partially edentulous cases, including the maxillary jaw.19 In 1999, a prospective 5-year clinical study of immediately splinting andloading four one-stage dental implants in the edentulous mandible was begun ataNobel Biocare, Inc., Yorba Linda, CA 92887; (800) 993-8100Vol. 22, No. 10 Compendium / October 2001 1
  2. 2. Figure 1—AdVent™ dental implants implant is manufactured with a microtexturedCE 3 feature an optional combination HA-coated and blasted surface. ,b surface (MTX™ ) or a hybrid surface (Dual ,b Transition Selective Surface™ ) that includes ™ both microtexturing and HA coating. Micro- texturing is a proprietary technology that blasts the implant with soluble HA particles, fol- lowed by a procedure to remove residual blast- ing particles that may become embedded in the implant’s surface. For the hybrid surface option, HA coating is applied over a portion of the microtextured surface as a secondary surface treatment. The coating is restricted to the mid- section of the intraosseous implant body, begin- ning 2 mm below the base of the machined neck, and extends to 3 mm above the apical end of the implant. The implant system features two different surgical protocols that are selected according to bone density. Low-density bone characterized by loosely woven tissue and a thin cortical shell the University of Pittsburgh, Boston may not provide adequate threat engagement University, and the University of Lyon, France. to immediately stabilize the implant. The soft This preliminary case report from the ongoing bone surgical protocol is used to prepare a study presents an overview of the new implant straight osteotomy that is slightly smaller than design used in the study, the technique used for the actual diameter of the tapered implant. As immediate loading, and the results achieved in the implant gradually seats into the receptor one case that has been monitored for 18 site, the widening diameter of the implant body months of clinical follow-up. is designed to increase mechanical stability at the crest of the ridge. Implant Design and Surface Features In dense bone where adequate thread ,b The AdVent™ implant selected for this engagement can be achieved, a tight mechani- study features a tapered, intraosseous body with cal interface at the crest of the ridge is not nec- self-tapping, triple-lead threads, and a slightly essary to maximize initial stabilization. fluted, 3-mm-long transmucosal neck designed Therefore, the dense bone surgical protocol to extend through the soft tissue from the time uses a double-cutting step drill to create a of placement (Figure 1). Manufactured in four straight osteotomy with a smaller diameter api- intraosseous body lengths (8 mm, 10 mm, cal end. As the implant seats into the osteoto- 13 mm, 16 mm) and two diameters (3.7 mm, my, the tapered apical end of the implant is 4.7 mm), the implants feature a common inter- designed to engage the narrow bottom of the nal hexagonal prosthetic platform 4.5 mm in receptor site and seat by self-tapping insertion. diameter. A low-profile surgical cover screw In this study, implant selection was limited and a 2-mm-high neck extension for thick to the 3.7-mm diameter to maintain at least mucosa are also packaged with each implant. 10 mm of labial plate thickness, 1 mm of lin- The neck extension component was not used gual plate thickness, and 3 mm of mesiodistal in this case. During laboratory procedures, the bone between each implant after preparation of surgical cover screw was threaded into the the osteotomies. Implants were also limited to implant to prevent the ingress of debris and lengths of ≥ 10 mm, with the proviso that at other contaminants. least 2 mm of inferior cortical plate was A relatively smooth, machined titanium retained. These limitations were designed to surface on the neck portion of the implant is help ensure adequate thread engagement for designed to facilitate maintenance of oral immediate stabilization and bony support of the hygiene. The intraosseous body portion of the restoration. Each case in the study consists of b Sulzer Dental Inc., Carlsbad, CA 92008; (760) 929-4300 four implants placed in the anterior mandible 2 Compendium / October 2001 Vol. 22, No. 10
  3. 3. CE 3Figure 2—Clinical view of the patient’s edentulous jaws. Figure 3—Stone cast demonstrates the severe bone resorption pattern in the mandible.Figure 4—New dentures were made and used for 2 weeks Figure 5—The cut-back surgical template provided access to thebefore implant surgery. surgical field.with cross-arch splinting for additional implant template for placing the dental implants instability. Each case also consisted of two optimal locations relative to the prosthesisimplants with HA-coated surfaces and two (Figure 5). A regimen of antibiotic coverageimplants with microtextured surfaces, which was prescribed, which the patient was instruct-will allow comparisons of clinical performance, ed to commence 24 hours before surgery. Onmarginal bone changes, and soft tissue response the day of surgery, the patient was prepared forbetween the two surfaces. an aseptic procedure and anesthetized by local infiltration. A midcrestal incision and twoCase Report release incisions were made and the soft tissuePatient Selection was elevated to expose the underlying alveolar The patient in this report was a 70-year-old process. After flattening the ridge to provide atman who presented with full edentulism in least 1 mm of bone on the facial and lingualboth jaws (Figure 2). Progressive bone loss in surfaces after preparation of the implanthis edentulous lower jaw (Figure 3) compro- osteotomies, the surgical template was placedmised the fit and function of his complete den- into the patient’s mouth, and the osteotomiesture prosthesis. The presurgical work-up con- were prepared by sequential cutting with inter-sisted of an oral examination, health history, nally irrigated drills in a slow-speed, high-study cast evaluations, and various clinical and torque handpiece. In the present case, thelaboratory assessments. Tooth wear on the dense bone surgical protocol was successfullypatient’s existing denture required fabrication used to place the implants (Figure 6).of a new prosthesis, which was placed into fullfunction without complications 2 weeks before Fabricating the Working Castimplant surgery (Figure 4). Indirect transfers were threaded into the implants (Figure 7), after which the soft tissueImplant Placement was sutured around the necks of the implants Since the patient’s new denture would be with 4-0 vicryl suturese. After trimming theused as the final restoration, an acrylic dupli- loose ends, each suture was coated with petro-cate was made of it to function as a surgical e Ethicon, Inc. Somerville, NJ 08876; (800) 255-2500Vol. 22, No. 10 Compendium / October 2001 3
  4. 4. CE 3 Figure 6—The surgical placement of four transmucosal Figure 7—Indirect transfers were threaded into the implants. implants. Figure 8—A full-arch, and wax to provide additional space for sol- elastomeric impression dering after investment and burnout. was made over the implants and transfers. When the bar pattern was completed, the fixation screws were unthreaded with the wrench tool. The bar pattern was carefully removed from the working cast and invested in a silica-bonded soldering investment material, which was allowed to flow through the gold cylinders and over the metal bars. After setting, the investment was trimmed and shaped around the joints to allow for the free flow of heat and soldering mate- rial. Standard laboratory procedures were used for leum jelly to facilitate the impression proce- burnout of the residual autopolymerizing acrylic dure. A full-arch impression was made with an and wax. The round bar segments were then sol- elastomeric material (Figure 8). Once the dered to the gold cylinders. After bench-cooling, impression material set, the tray was removed the soldered bar was divested, the soldered joints from the patient’s mouth. The transfers were were finished, and the bar was polished. unthreaded from the implants, and replaced by the surgical cover screws to maintain hygiene Verifying a Passive Fit during bar fabrication (Figure 9). Each transfer The surgical cover screws were removed was attached to a replica of the implant and and the bar was seated on the implants. The reinserted into its corresponding impression one-screw or “Sheffield fitting test”20 was used hole (Figure 10). The impression was poured in to determine if the bar achieved a passive fit dental stone, then separated after setting on the implants. A distal gold cylinder incor- (Figure 11). Each of the indirect transfer com- porated within the bar was attached to its cor- ponents was unthreaded from the working cast. responding implant with a fixation screw. The bar was then visually inspected to verify that Fabricating the Overdenture Bar no discernable gaps were present between the A 3-mm-high gold coping and fixation remaining gold cylinders and the implants. screw assembly was attached to each implant This procedure was repeated in succession replica in the working cast (Figure 12) and with each remaining gold cylinder and the pas- tightened to 20 Ncm with a 1.25-mm diame- sive fit of the bar was verified (Figure 14). If a ter hexagonal wrench tool and torque gap had been present between the bar and any wrench. Round gold bars were cut to the of the implants, the bar would have to be cor- appropriate lengths and shaped to fit rected by sectioning and resoldering. between the gold cylinders. Each bar seg- ment was luted to the gold cylinders with Processing the Denture Clips autopolymerizing acrylic (Figure 13). The The bar fixation screws were tightened to 20 joints of the bar pattern were reinforced by Ncm of torque. Adequate clearance was created overbulking with autopolymerizing acrylic in the denture base to accommodate the bar and 4 Compendium / October 2001 Vol. 22, No. 10
  5. 5. CE 3Figure 9—Surgical cover screws were threaded into the Figure 10—The indirect transfer were attached to implant repli-implants until delivery of the prosthesis. cas and reinserted into the impression.Figure 11—The working cast contained replicas of the patient’s Figure 12—Gold cylinders were attached to the implant replicasAdVent™ implants. in the working cast.implants without contact when the denture was and the patient was dismissed. The patient wasseated over them and placed into occlusion with recalled for an evaluation of healing 7 daysthe opposing denture. After removing the den- later. Oral hygiene and home-care instructionsture from the mouth, block-out wax was used to were reinforced, and the patient was dismissed.eliminate the voids beneath the bar. A gold den- After 3 months, the patient was recalled forture clip was fastened to the bar, the denture was manual testing to verify the presence of clinicalreseated over the assembly, and the occlusion was osseointegration. Oral hygiene instructionsrechecked to verify that the clip did not interfere were repeated, and the patient was dismissedwith the full, contact-free seating of the denture. until the first prophylaxsis appointment.The denture was removed from the mouth and asmall amount of autopolymerizing acrylic was Discussionplaced into the dry, relieved area of the denture All of the implants in this report successfullybase. After reseating the denture over the bar and osseointegrated under immediate loading condi-clip, the patient was instructed to bite lightly tions, and healing was uneventful. The entirein centric occlusion. When the autopolymeriz- restorative procedure took approximately 2 1/2ing acrylic set, the denture was removed from hours after completion of the surgery, includingthe patient’s mouth and final adjustments were time for fabrication of the gold bar superstructuremade to the prosthesis. Voids around the in the laboratory, and the patient left with a fullyprocessed clip were occluded with additional functioning, implant-supported overdentureautopolymerizing acrylic (Figure 15). The restoration. No complications or discernableblock-out material was removed from the bar changes in marginal bone height were radi-and the denture was reseated. ographically evident at the 18-month follow-up appointment (Figure 16), and the patientCompletion of the Case and Follow-up expressed great satisfaction with the results. The fit and function of the prosthesis were Modern implant dentistry stems from theclinically evaluated. Oral hygiene and postop- 19th century, when implants ranged from one-erative home care instructions were provided, piece, transmucosal designs that were loadedVol. 22, No. 10 Compendium / October 2001 5
  6. 6. CE 3 Figure 13—The bar pattern was formed by connecting the gold Figure 14—The finished gold bar provided a passive fit on the cylinders with gold bar segments. implants in the patient’s mouth. from the time of placement, to two-piece root- may be as effective as splinting in the preven- and-crown analogs that were loaded after a brief tion of implant micromovement. healing period of no more than 6 weeks.21 The Some researchers have stated that the long-term results of these early designs were increasing diameter of tapered implants results highly variable and unpredictable because of a in compression of the interfacial bone, which lack of appropriate biomaterials.22 An immedi- produces a higher insertion torque and greater ately loaded porcelain-and-lead implant intro- mechanical retention than nontapered duced in 1886, for example, remained in func- implant designs.27 While actual bone compres- tion for 27 years, despite the inherent toxicity sion with tapered implants has not yet been of the metal.21 The popularity of one-stage adequately demonstrated in clinical studies, it implants continued into the 20th century, with is reasonable to assume that the higher torque various designs introduced by Formiggini, reported27 with tapered implants is indicative Chercheve, Linkow, and others.23 of very close interfacial contact between the Immediate loading of one-stage dental increasing diameter of the implant body and implants continues to generate clinical inter- the walls of the receptor site. It has also been est. One concern in using the protocol, howev- theorized1 that tapered implants dissipate er, is that implant micromovement during early forces into the surrounding bone more uni- postinsertion healing will hamper bone regen- formly than parallel-walled implants and are eration, prevent osseointegration, or will result associated with more uniform compaction of in the interposition of fibrous tissue between bone in adjacent osteotomy walls. These the implant and the walls of the receptor site. claims, together with the effects of marginal Thread engagement, friction fit, or a combina- bone changes under long-term functional load- tion of both are methods used by root-form ing, are yet to be documented by long-term, dental implants to achieve initial stabilization. prospective clinical studies. Engaging dense, compact quality 1 or 2 bone Implant threads are designed to maxi- with implant threads is another technique for mize initial contact, achieve initial stability, achieving immediate implant stabilization. enlarge the implant’s surface area, and dissi- It has been postulated that a gentle surgical pate interfacial stress.28 The threads of screw- technique and splinting of implants may suffi- type implants can range from the pretapping ciently shield the bone-implant interface from variety, which requires the use of a bone tap functional overload and prevent micromove- before implant placement, to self-tapping ment from exceeding the allowable limits for designs, which cut directly into the bone as successful osseointegration.12 This theory is the implant is threaded into place. Prolonged supported by the extremely high success rates tightening of the bone by pretapping fol- achieved with splinted implants loaded early in lowed by screwing an implant into place has primates24 and loaded immediately in been postulated to create stress concentra- humans.25 However, even higher success rates tions at the crest of the ridge, which can have been reported for nonsplinted crowns reportedly contribute to a loss of marginal placed in the anterior maxilla,26 which suggests bone.29 Satomi and colleagues29 recommend that other methods of implant stabilization self-tapping insertion of the implant instead 6 Compendium / October 2001 Vol. 22, No. 10
  7. 7. CE 3Figure 15—A retentive clip processed into the denture base Figure 16—Panoramic radiograph taken at 18 months.attached to the bar when the prosthesis was placed into thepatient’s mouth.of pretapping the surgical site to avoid exces- between machined titanium and surfacessive stress concentrations in the hard tissue. roughened by blasting with small-grit (25 µm), In a study of maxillofacial fixation screws, medium-grit (75 µm), and large-grit (250 µm)Bähr and Lessing30 report that pretapped screws particles of A12O3, they reported that the medi-require more bone remodeling to osseointegrate um-grit particles achieved the highest degree ofthan self-tapping screws, and conclude that the bone-to-metal contact.38 This may suggest thathigher friction between the bone and self-tap- uncoated implant surfaces grit-blasted withping screws results in a greater degree of anchor- medium-sized particles in the diameter range ofage. This finding is reaffirmed by Cook and 75 mm may provide an optimum range of sur-coworkers,31 who report that the more intimate face roughness for bone apposition. Morethe initial fit between the implant and the walls research is needed in this area before any defin-of the receptor site, the greater the percentage itive conclusions can be drawn.of bone apposition to the implant surface afterhealing. Self-tapping insertion of screw-type Conclusionimplants has also been reported to reduce surgi- The observations in this report raise hopecal time by as much as 3 minutes per implant,32 that AdVent™ implants immediately splintedwhich may shorten clinical chair time. Sykaras and loaded with bar-supported overdentureand colleagues28 report that double-threaded or restorations in the edentulous mandible maytriple-threaded implants are faster to thread offer a promising alternative to traditionalinto the osteotomy site, generate less heat on overdenture treatment. Data from the currentplacement, provide increased initial stability, study and other long-term, prospective studiesand require more torque for placement (and with a larger patient population, are neededthus tighter contact with bone). The ability of before definitive conclusions can be made.a dental implant to distribute the stresses ofocclusion is determined, in part, by the amount Acknowledgmentsof bone-to-metal interface achieved by the The authors thank Robert Riley, CDT, Bobimplant.33 Recent studies on implant surfaces Vanard, CDT, and Michael D. Henry, MA, forhave shown that roughening the surface by grit their sterling assistance in researching, writing,blasting,7,8 increases the amount of bone-to- and editing this article.implant apposition, and that coating with tita-nium plasma spray (TPS)34 or HA35 increases Disclosureremoval torque values. Conversely, the health This study was supported by a grant fromof soft tissue is more readily maintained if the Sulzer Dental, Inc.portion of the implant emerging from the bonehas a relatively smooth surface.36 References Wennerberg and colleagues37 observed that 1. Callan DP, Hahn J, Hebel K, et al: Retrospective multi- center study of an anodized, tapered, diminishing threadsurface topography varied among 13 commer- implant: success rate at exposure. Implant Dent 9(4):329-cially available implant systems. In an animal 335, 2000.study comparing bone-to-metal contact 2. Burgess AV, Story BJ, La D, et al: Highly crystalline MP-1 hydroxyapatite coating. Part I: In vitro characterizationVol. 22, No. 10 Compendium / October 2001 7
  8. 8. and comparison to other plasma-sprayed hydroxyapatite 21. Ring ME: A thousand years of dental implants: a definitiveCE 3 3. coatings. Clin Oral Implants Res 10(4):245-256, 1999. Burgess AV, Story BJ, Wager WR, et al: Highly crystalline history—Part 1. Compend Contin Educ Dent 16(10):1060- 1069, 1995. MP-1 hydroxyapatite coating. Part II: In vivo performance 22. Luckey HA and Kubli Jr F (eds.): Titanium Alloys in Surgical on endosseous root implants in dogs. Clin Oral Implants Res Implants. Philadelphia, American Society for Testing and 10(4):257-266, 1999. Materials, pp 1-3, 1983. 4. Wennerberg A, Ektessabi A, Albrektsson T, et al: A 1-year 23. Ring ME: A thousand years of dental implants: a definitive follow-up of implants of differing surface roughness placed history—Part 2. Compend Contin Educ Dent 16(11):1132- in rabbit bone. Int J Oral Maxillofac Implants 12(4):486- 1136, 1995. 494, 1997. 24. Piatelli A, Corigliano M, Scarano A, et al: Bone reactions 5. 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Collaert B, De Bruyn H: Comparison of Brånemark fixture zone with immediate provisionalization: fourteen consecu- integration and short-term survival using one-stage or two- tive case reports. Pract Periodontics Aesthet Dent stage surgery in completely and partially edentulous 10(9):1107-1114, 1998. mandibles. Clin Oral Implants Res 9(2):131-135, 1998. 27. O’Sullivan D, Sennerby L, Meredith N: Measurements 8. Ericsson I, Randow K, Nilner K, et al: Some clinical and comparing the initial stability of five designs of dental radiographical features of submerged and non-submerged implants: a human cadaver study. Clin Implant Dent Relat titanium implants. A 5-year follow-up study. Clin Oral Res 2(2):85-92, 2000. Implants Res 8(5):422-426,1997. 28. Sykaras N, Iacopino AM, Marker VA, et al: Implant mate- 9. Kohal RJ, De LaRosa M, Patrick D, et al: Clinical and his- rials, designs, and surface topographies: their effect on tologic evaluation of submerged and nonsubmerged osseointegration. A literature review. Int J Oral Maxillofac hydroxyapatite-coated implants: a preliminary study in Implants 15(5):675-690, 2000. dogs. Int J Oral Maxillofac Implants 14(6):824-834, 1999. 29. Satomi K, Akagawa Y, Nikai H, et al: Bone-implant inter- 10. Becker W, Becker BE, Israelson H, et al: One-step surgical face structures after nontapping and tapping insertion of placement of Brånemark implants: a prospective multicen- screw-type titanium alloy endosseous implants. J Prosthet ter clinical study. Int J Oral Maxillofac Implants 12(4):454- Dent 59(3):339-342, 1988. 462, 1997. 30. Bähr W, Lessing R: The response of midfacial bone in 11. Adell R, Lekholm U, Brånemark PI: Surgical procedures sheep to loaded osteosynthesis screws in pretapped and In: Brånemark PI, Zarb GA, Albrektsson T (eds.): Tissue- nontapped implant sites. J Oral Maxillofac Surg Integrated Prostheses. Osseointegration in Clinical Dentistry. 50(12):1289-1294,1992. Chicago, Quintessence Pub Co, Inc, pp 211-232, 1995. 31. 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Rimondini L, Fare S, Brambilla E, et al: The effect of sur- results for Brånemark implants immediately loaded with face roughness on early in vivo plaque colonization on tita- fixed prostheses at implant placement. Int J Oral Maxillofac nium. J Periodontol 68(6):556-562, 1997. Implants 12(4):495-503, 1997. 37. Wennerberg A, Albrektsson T, Andersson B: Design and 17. Balshi TJ, Wolfinger GJ: Immediate loading of Brånemark surface characteristics of 13 commercially available oral implants in edentulous mandibles: a preliminary report. implant systems. Int J Oral Maxillofac Implants 8(6):622- Implant Dent 6(2):83-88, 1997. 633, 1993. 18. Ericsson I, Randow K, Nilner K, et al: Early functional 38. Wennerberg A, Hallgren C, Johansson C, et al: A histo- loading of Brånemark dental implants: 5-year clinical fol- morphometric evaluation of screw-shaped implants each low-up study. Clin Implant Den Relat Res 2(2):70-77, 2000. prepared with two surface roughnesses. Clin Oral Implants 19. 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  9. 9. Quiz31. In which three areas have advancements extended the 4. The joints of the bar pattern were further reinforced by 8. What are methods used by root-form dental implants to benefits of root-form dental overbulking with additional achieve initial stabilization? implants to many patients who autopolymerizing acrylic and a. Thread engagement were previously excluded? wax to: b. Friction fit a. Stronger titanium, antibiotics, a. compensate for inadequate c. Combination of both thread chemotherapeutics bar length. engagement and friction fit b. Implant designs, biomaterials, b. provide more room for d. all of the above surgical techniques soldering. c. Improved tolerances, c. facilitate clip attachment. 9. It has also been theorized that chemotherapeutics, d. add strength to the bar. which implants dissipate forces antibiotics into the surrounding bone more d. Stronger antibiotics, designs, 5. If a gap had been present uniformly? biomaterials between the bar and any of the a. Parallel-walled other implants, the bar would b. Smooth-walled2. Some researchers caution that have to be corrected by: c. Tapered immediate loading of dental a. carefully screwing the bar d. Coated implants should be limited to the: into place. a. intercanine region of the b. using fewer screws to retain 10. Uncoated implant surfaces grit- maxilla. the bar. blasted with medium-size b. intermolar region of the c. repolishing the bar. particles in the diameter range of posterior mandible. d. sectioning and resoldering 75 µm may provide an optimum c. interforamina region of the the bar. range of surface roughness for: mandible. a. thread sharpness. d. intermolar region of the 6. The bar fixation screws tightened b. soft tissue apposition. maxilla. to what torque? c. oral hygiene. a. 20 Ncm d. bone apposition.3. In the soft bone surgical b. 25 Ncm protocol, the widening diameter c. 30 Ncm of the implant body is designed d. 35 Ncm to increase mechanical stability at the: 7. The patient was recalled for a. crest of the ridge. manual testing to verify the b. apical region. presence of clinical c. medullar region. osseointegration after: d. lingual region. a. 1 year. b. 6 months. c. 3 months. d. 1 month. This article provides 1 hour of CE credit from Dental Learning Systems, in association with the University of Southern California School of Dentistry and the University of Pennsylvania School of Dental Medicine, representatives of which have reviewed the articles in this issue for acceptance. Record your answers on the enclosed answer sheet or submit them on a separate sheet of paper. You may also phone your answers in to (888) 596-4605, or fax them to (703) 404-1801. Be sure to include your name, address, phone number, and social security number.Vol. 22, No. 10 Compendium / October 2001 9