The International Journal of Oral & Maxillofacial Implants, 04/2004

The transition from a lifelong period of professional academic preparation, academic pursuits, and/or clinical practice to a more tranquil, moderated life with fewer commitments is welcomed by most of us at the appropriate time. From time to time, individuals who have significantly affected our professional and personal lives reach the pinnacle of their careers and are deserving of special recognition as they realize retirement. Such a colorful figure and articulate player on the prosthodontic stage of the past 4 decades has been Dr George Albert Zarb.

Purpose: The aim of this randomized, controlled, blinded clinical study was to compare ridge dimensions and histologic characteristics of ridges preserved with 2 different graft materials. Materials and Methods: Twenty-four subjects, each requiring a nonmolar extraction and delayed implant placement, were randomly selected to receive ridge preservation treatment with either an allograft in an experimental putty carrier plus a calcium sulfate barrier (PUT) or a bovine-derived xenograft (BDX) plus a collagen membrane. Horizontal and vertical ridge dimensions were determined using a digital caliper and a template. At 4 months postextraction, a trephine core was obtained for histologic analysis. Results: The average ridge width decreased by 0.50 mm for both groups (P .05). The midbuccal vertical change for the PUT group was a loss of 0.3 ± 0.7 mm versus a gain of 0.7 ± 1.2 mm for the BDX group, a difference of 1.0 mm (P > .05). Histologic analysis revealed vital bone in the PUT group of about 61% ± 9% versus 26% ± 20% for the BDX group (P .05). Discussion: Greater vital bone fill in the PUT group may be attributable to earlier and greater vascular invasion of the carrier material. The putty material was characterized by ease of handling, simple placement, and enhanced graft particle containment. Conclusions: Allograft mixed with an experimental putty carrier produced significantly more vital bone fill than did the use of a xenograft with no carrier material. Ridge width and height dimensions were similarly preserved with both graft materials.

Purpose: The present study was designed to investigate the long-term bone response around machined screw-type uncoated and calcium phosphate (CaP) -coated commercially pure titanium implants. Materials and Methods: Using a magnetron sputtering technique, implants with a CaP coating similar in composition and CaP ratio to hydroxyapatite were produced. Heat treatment was subsequently used to increase the crystallinity of the coatings. Four types of coatings (0.1 and 2.0 µm amorphous and 0.1 and 2.0 µm crystalline) were manufactured; uncoated implants served as a control. Three hundred twenty implants (64 of each type) were randomly placed in the tibial cortical and trabecular femoral bones of 40 rabbits. The rabbits were sacrificed 9 months after implant placement. Results: Histomorphometric evaluation carried out on ground sections revealed that the crystalline CaP coatings achieved the highest bone-implant contact in both tibiae and femora compared with amorphous CaP-coated and uncoated titanium. Discussion: The present study suggests that submicron crystalline hydroxyapatite coating adds bioactive properties to titanium oral implants. Conclusion: An ultra-thin, 0.1- µm crystalline CaP coating can elicit and maintain an improved long-term bone response compared to amorphous coated or uncoated Ti implants, without any adverse tissue reactions. (More than 50 references.)

Purpose: Protocols for quantifying the surface roughness of implants are varied and dependent upon the roughness parameter produced by the particular measurement device. The objective of this study was to examine the accuracy and precision of typical roughness characterization instruments used in the dental implant industry. Materials and Methods: The average roughness (Ra) was measured using 2 common surface characterization instruments: an interferometer and a stylus profilometer. Titanium disks were prepared to represent 4 typical dental implant surfaces: machined, acid-etched, hydroxyapatite- coated, and titanium plasma-sprayed. Repeated measurements from multiple sites on each surface were undertaken to establish statistical inferences. Qualitative images of the surfaces were also acquired using a laser scanning confocal microscope. After surface measurements were conducted, the disks were diametrically cut and cross-sectional profiles were examined using a scanning electron microscope (SEM) as a comparative measure of surface topography. An analysis of variance was applied to isolate the effects of the measurement site, measurement sequence, surface treatment, and instrument type on Ra values. Results: The results indicated that surface treatment (P = .0001) and instrument (P = .0001) strongly influenced Ra data. By design, measurement site (diametrical: P = .9859; area: P = .9824) and measurement sequence (P = .9990) did not influence roughness. In the assessment of individual instrument accuracy, the interferometer was the most accurate in predicting SEM-based roughness (P = .6688) compared with the stylus (P = .0839). As a measure of aggregate precision over all measurements, the most repeatable instrument was the stylus (coefficient of variation [CV] = 0.108), followed by the interferometer (CV = 0.125) and SEM (CV = 0.273). Discussion: These results indicate dependencies in accuracy and precision related to the surface characterization technique. Conclusion: Instrument variability may obscure functional correlations between implant surface topography and osseointegration.

Purpose: The aim of this study was to compare the accuracy of casts produced by 2 impression techniques and elastomeric impression materials commonly used for the fabrication of implant-supported fixed prostheses. Materials and Methods: A master model with 4 synOcta ITI implants placed unilaterally in place of the mandibular right central incisor, canine, first premolar, and first molar was constructed. Implant-level impressions were made by direct and indirect techniques. In the direct technique, synOcta impression caps with integral guide screws were used to transfer the implants using a custom-made acrylic resin tray and a polyether impression material (the PE direct technique). In the indirect technique, synOcta plastic positioning cylinders with impression caps were used to transfer the implants with either a custom-made acrylic resin tray and polyether impression material (the PE indirect technique) or with a stock tray with a vinylpolysiloxane impression material (the VPS indirect technique). After impression making, all casts (n = 21) were poured in type IV dental stone. Linear changes in -x or -y direction and numeric and descriptive angular changes between the implants were quantified using a coordinate measuring machine. Results: Seven of 12 distance measurements (6 for -x direction, 6 for -y direction) showed differences between groups (P .05). Of these, 5 were associated with the PE direct versus PE indirect and PE indirect versus VPS indirect, and 3 were associated with PE direct versus VPS indirect. Two implants also showed angular changes but only for the PE indirect technique versus the VPS indirect technique (P .05). Conclusion: The snap-on VPS indirect impression technique using a stock tray, which has the advantages of being clinically convenient and eliminating repositioning after removal of the impression, resulted in dimensional accuracy similar to that achieved with the PE direct technique.

Purpose: This article describes (a) an immediate loading technique in the treatment of edentulous arches with screw-retained provisional restorations and (b) the effort to determine whether the described technique is compatible with the predictable achievement of osseointegration. Materials and Methods: Eight patients with either 1 or 2 edentulous arches were treated. A diagnostic tooth arrangement was carried out for each patient and was then duplicated twice to fabricate a provisional template and a surgical guide. Six to 10 solid-screw ITI implants were placed around the dental arch to reach the first molar regions. On the same day, all patients received splinted metal-free screw-retained provisional restorations according to the pickup technique. The provisional prostheses were retrieved every 2 weeks during the healing phase. Results: Seventy-eight implants were placed in 11 edentulous arches. Two implants were not immediately loaded because of inadequate primary stability. In an 8- to 20-month follow-up period (mean 14 months), two 8-mm implants were lost after 5 weeks of functional loading, resulting in an overall survival rate of 97.4%. All implants were assessed by resonance frequency analysis. After 4 months of functional loading, the mean implant stability quotient was 60 ± 4.1 units (range 51 to 72 ISQ units) for maxillary implants and 65 ± 6.5 units (range 47 to 74 ISQ units) for mandibular implants. Discussion and Conclusion: The immediate loading of implants placed in edentulous arches with screw-retained 1-piece (cross-arch) provisional restorations does not appear to jeopardize the achievement of osseointegration. Neither the metal-free design of the provisional prostheses nor the removal of the provisional prostheses during the healing phase adversely affected osseointegration. The pickup technique for immediate provisionalization represents a reproducible treatment option.

Purpose: The purpose of this study was to assess the survival rates and interproximal bone levels for Osseotite implants that were restored with fixed provisional crowns without occlusion immediately after implant placement. Materials and Methods: Ninety-three implants were placed in 38 partially edentulous patients. All implants were immediately restored with prefabricated abutments and cement-retained provisional crowns without centric or eccentric occlusal contacts. The implants were restored with definitive restorations approximately 8 to 12 weeks after implant placement. All patients included in the study were followed for at least 18 months after implant placement (average 20.3 months). Results: Seventy-seven of the 93 implants satisfied the inclusion criteria. Seventy-five implants became osseointegrated. The overall survival rate was 97.4%. Radiographic bone loss 18 months after implant placement (the mean of both interproximal surfaces) was 0.76 mm. The exact binomial confidence interval was 0.32% to 9.07%. For the exact binomial test with the null hypothesis proportion = .05, P was .3334 and was not statistically significant. Discussion: Immediate nonocclusal loading of single-unit dental implants differs from immediate loading of multiple, splinted implants. Unsplinted, restored implants without occlusal loading may still be subject to lateral and occlusal loads secondary to the proximate location of the food bolus. Immediate restoration of dental implants significantly reduces treatment time and may be beneficial in reducing the morbidity associated with loss of teeth, contraction of the alveolus, and loss of interdental papillae associated with the traditional method of treatment following tooth loss. Conclusions: The results of this study suggest that immediate restoration of Osseotite implants can be accomplished with results that are similar to the results obtained with the traditional 1- or 2-stage surgical, unloaded healing protocols.

Purpose: This study aimed to (1) compare 2 scales in the assessment of first-stage implant surgery, (2) assess the interrater reliability of these scales, and (3) compare self-assessment with observer assessment. Materials and Methods: Twenty-three patients underwent first-stage implant surgery. One assessor, an experienced dental surgeon, assisted and supervised the operator, while the second, a postgraduate trained in assessment, observed the procedure closely. The assessment scales consisted of a checklist and a global rating scale. Results: A significant correlation was found between the checklist and the global rating scale scores (r = 0.47, P = .002). The British Standards Reproducibility Coefficients were 2.5 (checklist) and 7.4 (global rating scale) for interrater reproducibility and 7.0 (checklist) and 12.6 (global rating scale) for self-assessment versus assessor reproducibility. Finally, analysis of the intraclass correlation coefficients between the assessors (0.74 and 0.64 for the checklist and the global rating scale, respectively) and between the surgeons' and trainers' scores (0.09 for the checklist and 0.18 for the global rating scale) showed a much weaker agreement for the latter. Discussion: There was good correlation between scores using the 2 different methods of assessment. The interrater reliability was substantial for both scales. However, training of assessors to ensure higher levels of interrater reliability may be necessary. These results also demonstrated the inability of some surgeons to assess their performance accurately. Conclusion: Both the checklist and the global rating scales provided useful assessment data, and both were considered of value by the assessors and surgeons in providing feedback. The development of assessment and self-assessment skills in implant surgery is necessary if we are to establish a culture of commitment to lifelong learning.

Purpose: The purposes of the present study were to evaluate implants placed immediately after tooth extraction without incision or primary flap closure and to observe the peri-implant soft tissue healing. Materials and Methods: Fifteen patients (9 men and 6 women) aged 31 to 54 years were included in this study. Each patient had a tooth that required extraction, and each had at least 4 mm of bone beyond the root apex. Teeth with multiple roots were excluded from this study. After tooth extraction, the implants were immediately placed without incision or flap elevation. Implant sites showing bone fenestrations, bone dehiscences, or peri-implant bone defects exceeding 2 mm were excluded from this study. In these cases, a standard guided bone regeneration procedure with a surgical flap elevation was used. The second-stage surgical procedure was performed 6 months after the first procedure. The following clinical parameters were evaluated at the time of implant placement and at secondstage surgery: levels of mesial and distal papillae, width of keratinized mucosa, position of mucogingival junction relating to the surrounding tissues, and peri-implant radiolucency and marginal bone loss, which were evaluated radiographically. Results: The postsurgical healing period was uneventful for all patients. Soft tissue closure over the implant sites was achieved in 1 to 3 weeks after surgery at all sites. At second-stage surgery, no peri-implant bone defects were observed or detected by probing around all the experimental implants. The soft tissue anatomy was considered clinically acceptable in all patients. Discussion and Conclusion: Successful osseointegration and complete bone healing were observed for all patients. The soft tissue healing and morphology were satisfactory; additional mucogingival surgery was not required before definitive prosthetic rehabilitation.

Purpose: The aim of this study was to evaluate the effectiveness of a split-crest bone augmentation technique performed for immediate implant placement in thin edentulous posterior mandibular ridges. Materials and Methods: In the present study, 125 implants were placed in posterior mandibular ridges of 30 patients. The mandibular buccal walls were split, expanded, and grafted with a combination of platelet-rich plasma and Cerasorb. The split segments were held in place by cortical bone screws. Before loading, periodontal status was checked, implant stability was evaluated with the Periotest, and panoramic radiographs and computerized tomography scans were obtained. Second-stage surgery (cover screw removal and healing abutment placement) was performed after 3 to 4 months. Results: All implants osseointegrated successfully and underwent loading after 4 months. Optimal healing occurred 3 to 4 months earlier than the usual 6 to 9 months required, and no lip paresthesia was noted. Discussion: Although onlay-inlay grafts, sandwich osteotomies, guided bone regeneration, piezoelectricity, and alveolar distraction have been indicated for augmentation in the posterior mandibular region, each of these techniques involves risks and complications. The crest-splitting bone expansion technique enables single-stage immediate implant placement and lateral ridge augmentation in thin crests and may prevent neurosensorial deficiencies. Conclusions: The split-crest surgical technique is a valid reconstructive procedure for sharp posterior mandibular ridges. If performed using platelet-rich plasma and Cerasorb, it can shorten the osseointegration period.

Purpose: The present study compared the regenerative outcome of sinus graft procedures in a group of patients who underwent the repair of an intraoperatively diagnosed sinus membrane perforation to that of a group of patients without sinus membrane perforations. Materials and Methods: A sinus floor augmentation procedure was performed in 73 sinuses in 63 patients. In 28% of these sinuses a significant (> 5 mm) membrane perforation was observed intraoperatively. In these cases, the perforation was sealed with a freeze-dried human lamellar bone sheet, and the grafting procedure was carried out as planned. The following parameters were measured on panoramic radiographs immediately postoperatively and at the 6- and 24-month follow-up examinations: (1) the distance between the occlusal edge of the implant and the preoperative sinus floor, (2) the distance between the occlusal edge of the implant and the postoperative sinus floor, and (3) the distance between the occlusal edge of the implant and the alveolar crest. Results: The patients whose sinus membranes were perforated experienced no complications. No statistically significant differences were found between the 2 groups in the parameters measured. Discussion: Lambone was used in all cases in the present study. In no case did the sinus augmentation procedure have to be abandoned. Conclusion: It can be concluded that membrane elevation must be carefully executed to avoid membrane perforation, but that if it occurs, it is still possible to continue the procedure safely after repair.

Purpose: The aim of this prospective clinical study was to compare the clinical and radiographic results of 3 modes of implant treatment in combination with an overdenture in patients with extremely resorbed mandibles. The 3 treatment strategies used were a transmandibular implant, augmentation of the mandible with an autologous bone graft followed by placement of 4 endosseous implants, and the placement of 4 endosseous implants only. Materials and Methods: Sixty edentulous patients met the inclusion criteria and were assigned according to a balanced allocation method to 1 of the 3 groups. Postoperative complications, implant survival, periodontal indices, change in mandibular bone height, and prosthetic complications were assessed during a 2-year evaluation period. Results: During the evaluation period significantly more implants were lost in the transmandibular implant and the augmentation groups compared to the group with endosseous implants only. Except for the Bleeding Index and the Periotest values, the periodontal parameters did not differ significantly among the groups. In all 3 groups, there was no significant bone loss at most locations. Minimal prosthetic retreatment was necessary. Discussion: Although implant loss is a frequently used outcome measure for success, the necessity of retreatment seems to be of more relevance for both the patient and the clinician. Conclusions: The results of this study suggested that patients with extremely resorbed mandibles can be treated with implants alone in this patient population. (More than 50 references.)

Purpose: In this study, standard Brånemark System implants and Brånemark TiUnite implants were evaluated regarding primary stability and placement torque. The correlation between placement torque and primary stability as well as the influence of implant design on placement torque and primary stability were examined. Materials and Methods: Twelve patients who presented bilateral loss of either maxillary lateral incisors or premolars were treated with 24 immediately loaded dental implants. Each patient received 1 standard 3.75 × 13-mm Brånemark System implant and one 3.75 × 13-mm TiUnite Mk III implant. One at a time, each implant was connected by a transducer to an Osstell machine that automatically translated a resonance frequency value for the implant into an implant stability quotient value. Osseocare equipment was used to measure the placement torque for both types of implants. Results: Statistical analysis showed higher mean values for standard implants in relation to placement torque and resonance frequency values. Discussion: There was no overall correlation between placement torque and resonance frequency values; this finding supported previous studies. Conclusion: Stability was shown to be higher for the standard implants. Mean values of torque resistance were higher for the standard implants than for the TiUnite implants. Implant design appeared to influence primary stability and placement torque.

Autologous bone grafts for alveolar ridge augmentation are the gold standard for restoring atrophic residual ridges in preprosthetic surgery. Many indications, donor sites, and techniques have been reported. The purpose of this article is to review the anatomy, surgical technique, and potential complications associated with proximal tibia bone harvest. A consecutive series of 44 patients who underwent proximal tibia bone graft harvest between 2000 and 2003 was studied by retrospective chart review. Five major and 7 minor complications were observed; overall morbidity was low. A significant amount of corticocancellous bone may be harvested from the proximal tibia with minimal morbidity.

Purpose: To study the factors that influence radiographic magnification of implant diameter and length. Materials and Methods: The dental records and panoramic radiographs of 80 patients with 210 dental implants treated with implant-supported prostheses at Bundang Jesaeng Hospital in South Korea from January 2000 through February 2003 were reviewed. The panoramic radiographs were developed under standardized conditions. The patient's gender and the anatomic locations of implants were identified from the dental records. To prevent bias, a blinded investigator measured implant diameter and length on a panoramic radiograph. To evaluate intra-examiner variability, the intraclass correlation coefficient (RI) was calculated. The Mann-Whitney rank-sum test and the Kruskal- Wallis test were used to determine the statistical significance of the difference between actual length and radiographic length. Results: The intraclass correlation coefficients (RI) were 0.83 for diameter and 0.87 for length. There was no statistically significant difference in length in regard to gender (P = .08). Magnification of diameter did differ on the basis of gender (P = .03; 25% magnification in radiographs of women; 20% in men). No difference in diameter was found in regard to anatomic location (P = .51), however, while evidence of difference in length in regard to anatomic location was found (P = .01). Discussion: Radiographic magnification of implant dimensions in diameter and length can have different influencing factors. Conclusions: This study found that radiographic magnification of implant diameter was influenced by gender, whereas radiographic magnification of implant length was influenced by anatomic location. Each anatomic location had a different amount of radiographic magnification for implant length.

Purpose: The aim of the present study was to assess crestal bone resorption 5 years after loading by conducting a clinical and radiographic evaluation of 112 Frialit-2 implants consecutively placed in 51 patients from January 1994 through June 1994. Materials and Methods: All implants were placed in the same private-practice clinic by the same surgeon. Clinical assessment included plaque score monitoring, bleeding on probing, probing depth, type of occlusion, and prosthetic adaptation. Intraoral radiographs were taken and compared using suitable software to accurately measure peri-implant bone resorption. Results: The survival rate of the implants was 100%. Plaque was present on 47 (42%) implants. Bleeding on probing was detectable at 17 implants (15.5%). Probing depth was > 5 mm for 5 implants (4.5%). Crestal bone resorption was 3 mm for 32 implants (28.6%); the average observed crestal bone resorption was 2.17 ± 1.6 mm. Discussion: The survival rate of the implants may be the result of the relatively short functional period as well as the strict and frequent clinical evaluations associated with oral hygiene procedures during the supportive periodontal therapy. Conclusion: The results suggest that with strict plaque control, and provided that the patient follows a regular program of supportive therapy, crestal bone resorption around a 2-stage implant system may be limited. Schlagwörter: crestal bone resorption, wide-diameter dental implants

After resection and autogenous bone grafting in infancy and childhood, hypotrophy of the concerned jaw can often be observed. A 6-year-old male patient with osteogenic sarcoma was treated with partial resection of the mandible from the left first molar to the right first premolar. The aim was to rehabilitate the patient functionally and esthetically as he grew. At the age of 16, after the placement of 4 Brånemark System implants in the consolidated autogeneous bone graft, the patient was treated with horizontal distraction osteogenesis. A new and unconventional type of individual tooth/implant-supported distraction device was used to lengthen the mandible by 16 mm. The implants placed to support the device were later used for prosthodontic rehabilitation. Progress in bone reconstruction, plastic coverage, and implant dentistry, as well as distraction osteogenesis, have enabled the compensation of functional and esthetic impairments caused by resection, especially in infants and young children.