The International Journal of Oral & Maxillofacial Implants, 06/2000

Initially, implant surface analyses were performed on 10 machined implants and on 10 sandblasted and acid-etched implants. Subsequently, sandblasted and acid-etched implant cytotoxicity (using L929 mouse fibroblasts), morphologic differences between cells (osteoblast-like cells MG63) adhering to the machined implant surfaces, and cell anchorage to sandblasted and acid-etched implant surfaces were evaluated. Results indicated that acid etching with 1% hydrofluoric acid/30% nitric acid after sandblasting eliminated residual alumina particles. The average roughness (Ra) of sandblasted and acid-etched surfaces was about 2.15 ìm. Cytotoxicity tests showed that sandblasted and acid-etched implants had non-cytotoxic cellular effects and appeared to be biocompatible. Scanning electron microscopic examination showed that the surface roughness produced by sandblasting and acid etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering to the machined implants presented a very flat configuration, while the same cells adhering to the sandblasted and acid-etched surfaces showed an irregular morphology and many pseudopodi. These morphologic irregularities could improve initial cell anchorage, providing better osseointegration for sandblasted and acid-etched implants. Keywords: acid etching, cellular morphology, dental implants, immunologic cytotoxicity tests, surface properties

In an effort to better understand the supporting anatomy for unloaded endosseous dental implants, this study focused on the histomorphometric analysis of 3 different types of implants placed into non-human primate jaws and allowed to heal for 6 months. This report describes data from 24 screw-type dental implants placed in edentulated (2 months healing time) posterior arches of 4 adult female baboons. Three different implants were placed and allowed to heal for 6 months prior to processing for evaluation: commercially pure titanium (n = 8), titanium alloy (n = 8), and titanium plasma-sprayed (n = 8). Circumferential bone-implant interface sampling from 6 regions along the entire length of each implant was obtained for evaluation of percent bone-implant contact (%BIC) and percent bone area (%BA), within 3 mm of the implant. Data were collected (reliability of 1.6% for both parameters) and analyzed by an observer blinded to implant material using IMAGE analysis software for differences between jaws, implant biomaterials, and jaw/biomaterial (analysis of variance, pairwise comparison using least squares method with Bonferroni adjustment). The results indicated that the overall mean %BIC was 55.8 and mean %BA was 48.1. Maxillary and mandibular differences for both parameters were statistically significantly different: %BIC in maxilla 50.8, in mandible 60.8; %BA in maxilla 43.6, in mandible 52.6 (both significant at the P .05 level). The biomaterial analyses revealed no significant differences between the different implants for %BIC or %BA. The trend observed--that mandibular values were greater than maxillary values for the overall jaw comparisons--was found to be consistent at the jaw/biomaterial level, although the small sample size limited statistical power. These data, along with data from a previous 3-month study, provide insight into baseline supporting anatomy for dental implants. Keywords: animal study, biomaterials, bone, dental implants, histomorphometry

The purpose of this study was to estimate the quantity of dental implant literature available on MEDLINE for evidence-based clinical decision-making and to identify its location. A search strategy based on Medical Subject Headings for dental implants was developed to examine MEDLINE using the Ovid Web Gateway search engine. Sensitive and specific methodologic search filters identified 4 categories of information: etiology, diagnosis, therapy, and prognosis. The results were then subdivided by year to identify trends and sorted to identify the sources of publications. The searches identified 4,655 articles published in English between 1989 and 1999 on human dental implants on MEDLINE. The mean number of articles (± SD) per year ranged from 15 ± 11 for specific searches to 107 ± 50 for sensitive searches. The number of articles increased by 14% to 43% each year for the sensitive search. When subdivided by clinical category, the mean numbers of articles per year for sensitive and specific searches were, respectively: diagnosis 12 ± 7.5 and 1.5 ± 1.6, etiology 58 ± 33 and 1.9 ± 2.5, therapy 23 ± 15 and 0.3 ± 0.5, and prognosis 67 ± 33 and 12 ± 8.3. Four dental journals account for approximately half of these publications. These results provide 6 key central findings: (1) there appears to be a substantial literature of clinically relevant information on implants upon which to base clinical decisions; (2) the implant literature is significantly biased toward articles addressing prognosis; (3) to stay current, one would need to read between 1 and 2 articles per week 52 weeks per year, and this number increases significantly each year; (4) approximately 50% of the articles were published in 4 journals, whereas the remainder reside in approximately 97 other journals, making it difficult to stay current; (5) these trends reaffirm the need for lifelong learning; (6) these trends also suggest the need for computer-based clinical knowledge systems. Keywords: bibliometrics, diagnosis, etiology, implants, prognosis, therapeutics

A total of 2,261 2-stage implants was placed in 467 patients in combination with angled abutments ranging from 0 to 45 degrees. These were observed over a period of up to 96 months, with a mean observation time of 28.8 months. Single and multiple teeth were replaced and restored using angled abutments. For patients who contributed multiple survival data, the data were considered dependent. Therefore, a mean survival estimation was performed. With a certainty of 95%, an estimated mean survival rate better than 98.6% after a 5-year observation period was calculated. The statistical comparison of 2 independent, randomized implant groups (with abutments angled between 0 and 15 degrees and between 20 and 45 degrees) by means of a log-rank test showed a probability of 0.84 (P value) that the survival functions are the same for both groups. Good esthetic and functional outcomes were observed. Keywords: dental abutments, osseointegrated dental implants, survival analysis

Diabetes mellitus, a prevalent disorder worldwide, is associated with systemic adverse sequelae, such as wound healing alterations, which may affect osseointegration of dental implants. This prospective multicenter study assessed the success of 2-stage endosseous root-form implants (3 different implant systems) placed in the mandibular symphysis of 89 male type 2 diabetic subjects. The implants were uncovered approximately 4 months after placement, restored with an implant-supported, Hader bar clip-retained overdenture, and maintained at scheduled follow-up data collection examinations for 60 months after loading. Sixteen (9.0%) of the 178 implants failed. Life table methods calculated implant survival at approximately 88%, from prosthesis placement through the 60-month follow-up, and at approximately 90% from implant placement through the observation period. No implants failed between surgical placement and uncovering, 5 failed at uncovering, 7 failed after uncovering before prosthesis placement, and 4 failed after prosthesis placement. Fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) values were determined before implant placement (baseline) and approximately 4 months later at surgical uncovering (follow-up). The 5-year implant outcomes (successes versus failures) were analyzed against the following predictor variables: (1) baseline and follow-up FPG values, (2) baseline and follow-up HbA1c values, (3) subject age, (4) duration of diabetes (years), (5) baseline diabetic therapy, (6) smoking history, and (7) implant length. Regression analysis found only duration of diabetes (P .025) and implant length (P .001) to be statistically significant predictors of implant failure. There was no statistically significant difference in failure rates between the 3 different implant systems used. This study supports the use of dental implants in type 2 diabetic patients. Keywords: dental implants, diabetes, multicenter study, prospective studies

This study was conducted to compare the success of implants restored with angled abutments to implants restored with standard abutments. Eighty-one implants in 24 patients were evaluated for up to 36 months. Measurements included probing depths, gingival level, gingival index, and mobility. No significant difference could be found for any of the parameters examined between implants restored with angled and standard abutments. This suggests that the angled abutment may be considered a suitable restorative option when implants are not placed in ideal axial positions. Keywords: dental implant abutments, endosseous dental implantation, implant alignment

The purpose of this study was to evaluate the immediate loading of Brånemark System implants following placement with a screw-retained provisional prosthesis in edentulous patients. Twelve mandibular and 5 maxillary arches were treated from December 1997, including 3 bimaxillary patients. The provisional prosthesis, made of heat-polymerizing resin, had an inner casting of cobalt-chromium alloy to provide rigidity. The implants whose placement torque was more than 40 Ncm were immediately loaded. Implants that were placed with placement torque of less than 40 Ncm or that were associated with bone grafting were submerged. Following abutment connection, temporary cylinders were incorporated into the provisional prosthesis intraorally with autopolymerizing resin. After the provisional prosthesis was completed extraorally, it was screw-retained. After a 4- to 6-month healing period, a definitive prosthesis was fabricated and placed. Of the 140 immediately loaded implants, 136 osseointegrated during an 8- to 24-month follow-up period (97.2%). All 17 submerged implants osseointegrated. The results suggest that immediate loading of Brånemark System implants at the time of placement in edentulous patients can be a valuable adjunct to therapy and as predictable as delayed loading, in both mandibular and maxillary arches. Keywords: Brånemark System implant, complete edentulism, endosseous dental implantation, immediate loading, temporary dental restoration

Many clinical studies have shown that replacement of molars with only 1 implant is commonly associated with various functional complications, such as implant fracture and screw loosening. Thus, multiple implants have been recommended to withstand the high occlusal forces present in the molar region. The aim of this retrospective study was to evaluate the clinical response to the use of single implants with a progressive thread design (Ankylos) in the replacement of molar teeth. Fifty-eight implants (10 in the maxilla and 48 in the mandible) were placed in 51 patients. The implants were in situ for 29.30 ± 16.52 months and in function for 20.60 ± 16.64 months. All crowns were cemented to the abutments. The crown occlusion was adjusted to obtain minimal normal contacts in the centric occlusion and eccentric positions. Implants were clinically and radiographically evaluated, and clinical indices (Plaque Index, Sulcus Bleeding Index, probing pocket depth, keratinized mucosa width, Periotest) were recorded immediately before the placement of the prosthesis and once annually. Vertical and horizontal bone loss were also examined radiographically. Two implants were lost (1 because of fracture in a patient who was a bruxer and another because of abutment fracture in the endosseous part of the implant). All clinical and radiographic parameters of most of the implants were comparable to the values found for the same type of implant in other clinical indications. The reduced incidence of failure (96.55% survival rate) found in this study with the Ankylos implant system compared to the results reported in the literature indicate that this system can be used for the replacement of molars using single-implant-supported restorations. Keywords: biomechanics, molar, single-tooth dental implants

Excessive heat generation at the implant-bone interface may cause bone damage and compromise osseointegration. Autopolymerizing acrylic resins are commonly used intraorally to join impression copings and suprastructure components for soldering. The effect of heat generation at the implant surface related to the exothermic setting reaction of autopolymerizing acrylic resins applied to an attached abutment was examined in vitro. Two brands of autopolymerizing acrylic resin, Duralay and GC Pattern Resin, were compared. Acrylic resin was applied to a titanium alloy abutment connected to a titanium alloy cylindric implant in varying controlled volumes, with both bulk application and brush paint-on techniques. The implant was embedded in an acrylic resin mandible in a 37°C water bath. Temperature changes were recorded via embedded thermocouples at the cervical and apical of the implant surface. Analysis of variance for repeated measures was used to compare treatment groups. A mean maximum increase in temperature of 4 to 5°C was seen at the implant cervical for both materials, with a maximum temperature increase of 6°C. No difference between Duralay and GC Pattern Resin was seen, except for bulk application to medium-sized copper bands at the implant cervical (P .05). No difference between the bulk and brush techniques was seen for all options, except for GC, where bulk application to medium-sized copper bands produced higher temperatures than the brush technique (P .05). Spray coolant reduced temperatures for bulk application of both Duralay and GC (P .05). Keywords: autopolymerizing resins, dental implants, heat generation, impression, irrigation

In 61 patients, 61 consecutive implants were placed immediately after extraction of one anterior or premolar maxillary tooth. One of 3 surgical approaches based on rotated full (RPF) or rotated split (RSPF) palatal flaps, with and without the use of barrier membranes to enable primary soft tissue closure, was applied. A bovine bone mineral graft was used in all cases. At the time of implant placement, the distance between the most apicobuccal alveolar crestal bone and the coronal aspect of the implant body was measured; this was measured again at second-stage surgery. All implants appeared clinically stable. The buccal crestal bone gain was statistically significant for all groups (RPF = 2 mm, RSPF = 1.6 mm, RSPF with membrane = 3.7 mm) (P .001). Analysis of covariance showed a significant covariant for preoperative measurements; however, this was not significant between groups. Keywords: alveolar process, endosseous dental implantation, oral mucosa, oral surgical procedures

Sixty-three patients with inadequate topography of the edentulous ridge were treated with mandibular ramus/body grafts to allow for the placement of endosseous implants. After 4 months of osseous healing, 187 implants were placed in the grafted sites. The mandibular ramus/body grafts remained viable regardless of the age or the extent of alveolar resorption in the patients treated. The ease of harvesting this graft in the office setting, its long-term resistance to resorption, and minimal postoperative morbidity makes this a viable intraoral donor site for horizontal alveolar augmentation. Keywords: alveolar ridge augmentation, autogenous bone grafts, endosseous dental implantation, preprosthetic oral surgical procedures

This experiment was designed to study the osteogenic potential of adding medical-grade resorbable calcium sulfate mixture to grafting materials for filling osseous defects. Twelve New Zealand rabbits were divided into an active group of 10 animals and a control group of 2 animals. The median condyle of each femur was drilled to create 8-mm-deep cavities. Active osseous defects consisted of 20 cavities and were filled with Osteograf, BOP, or Capset (calcium sulfate) alone; a mixture of Osteograf and Capset; or a mixture of BOP and Capset. Osteograf and BOP were each mixed with Capset in a 4:1 ratio. Each grafting material filled 4 osseous cavities, and 4 osseous cavities were left unfilled to act as controls. The observation period was 8 weeks. Block sections of the femoral heads were prepared for decalcified histologic assessment. It appeared that mixing grafting materials with calcium sulfate powder in a 4:1 ratio, respectively, facilitated the process of osteogenesis and increased new bone bonding to remnants of the grafting materials, in spite of the poor osteoconductive property of BOP and moderate osteoconductivity of Osteograf. However, calcium sulfate material alone is not recommended for use as a bone filler. Keywords: bone substitutes, calcium sulfate, osteogenesis

The conventional placement protocol for submerged and non-submerged implants was proposed in the 1960s and 1970s. Multicenter studies have reported satisfactory success rates for both protocols and a similar loss of crestal peri-implant bone after implant loading (0.5 to 1.5 mm). In recent years, placement of submerged implants using a single surgical procedure was introduced, with the immediate placement of a healing abutment. Some studies reported good short-term results using this approach. Recently, a supracrestal apical-coronal positioning of the implant collar has been proposed for posterior sectors using submerged implants. This positioning facilitates the second surgical phase, as well as fabrication of the prosthetic restoration, and limits the amount of crestal bone loss. Keywords: bone resorption, dental implants, endosseous dental implantation, preprosthetic oral surgical procedures

In this clinical study, a 1:1 mix of particulate cancellous bone and marrow (PCBM) and bovine deproteinized bone (Bio-Oss) was used to fill cavities after elevating the sinus mucosa for major sinus dehiscences. Ten patients with edentulous posterior maxillae were treated with 12 sinus augmentation procedures according to a 2-stage technique, and 30 Frialit-2 endosseous implants were used to complete the implant-prosthetic rehabilitation. Bone cylinders were removed at second-stage surgery immediately prior to implant placement (5 to 7 months after grafting), and histologic evaluation was performed. The results showed that Bio-Oss is a reliable osteoconductive material and its association with PCBM leads to the formation of new bone with an increased overall density Keywords: bone substitutes, bone transplantation, dental implants, maxillary sinus, preprosthetic oral surgical procedures

A method to produce platelet-rich plasma and platelet concentrate using a double centrifuge technique in combination with the fibrin adhesive Tisseel is described. This technique constitutes the basic mixture for augmenting and improving an inadequate bone site. Also described is a procedure by which autologous bone or bone substitute is added to this mixture to increase the volume of grafting material. Platelet concentrates cause growth factors to be delivered to graft sites in an intense form, while Tisseel serves as a standardized, pharmaceutically manufactured fibrin adhesive. Keywords: alveolar ridge augmentation, factor XIII, fibrin tissue adhesive, plasmapheresis, platelets

The present report demonstrates a clinical approach to achieve vertical ridge augmentation around endosseous implants. Two implants were placed, leaving the threads exposed, in the atrophic mandibular right posterior quadrant of a male patient. Both implants were covered with a titanium-reinforced expanded polytetrafluoroethylene (e-PTFE) membrane. Second-stage surgery was performed 12 months after implant placement. Upon membrane removal, growth of mineralized tissue was observed around both implants, covering areas previously not covered by bone. Implants were then progressively loaded and restored. Titanium-reinforced e-PTFE membranes can be satisfactorily used for vertical augmentation of atrophic ridges. Keywords: alveolar ridge augmentation, dental implant, guided bone regeneration

The zygomaticus dental implant, designed by Nobel Biocare for the Brånemark System, is indicated primarily for the severely resorbed maxilla. Though the zygomaticus implant has had a remarkable success rate in a very difficult patient population, there are some shortcomings to the protocol for placement. The sinus slot technique described herein provides a simplified approach to zygomaticus implant placement, as compared to the currently recommended protocol. Keywords: dental implants, endosseous dental implantation, maxillary sinus, zygoma