The International Journal of Oral & Maxillofacial Implants, 05/2002

Purpose: The aim was to answer a fundamental question: Do the chemical properties of titanium implants influence osseointegration? Materials and Methods: Screw-type implants produced of turned commercially pure (grade 1) titanium (controls) and electrochemically calcium-deposited titanium implants (Ca test implants) were placed in the tibiae and femora of a total of 10 mature New Zealand white rabbits. The macro arc oxidation method was applied for Ca implants. Surface oxides were characterized with different analytic techniques, including x-ray photoelectron spectroscopy, auger electron spectroscopy, scanning electron microscopy, thin-film x-ray diffractometry, and TopScan 3D. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. Results: After a follow-up period of 6 weeks, test Ca implants showed a significant increase in mean peak removal torque (P = .0001) and in the histomorphometric measurement of bone-to-metal contact around the implants (P = .028) in comparison to controls. In addition, more mature mineralized bone was observed adjacent to test Ca implants compared to controls, as evaluated on 10-µm undecalcified, toluidine blue-stained, cut, and ground sections. Discussion: The potential role of surface Ca chemistry to a superior bone response is discussed with specific reference to interaction with Ca±binding proteins and function as binding sites of calcium phosphate mineral. Conclusion: The present results suggest that the surface chemical composition of titanium implants is of great importance for the bone response. Ca ion-deposited titanium implants showed fast and strong osseointegration in the rabbit bone model.

Purpose: This study was designed to clinically and histologically evaluate the integration of titanium implants in different grafting materials used for maxillary sinus augmentation procedures. Materials and Methods: A total of 21 patients and 36 maxillary sinuses were augmented with (1) autogenous particulated bone from the mandibular ramus, (2) bovine hydroxyapatite (BH) with membrane coverage, or (3) an 80/20 mixture of BH and autogenous bone. The grafts were allowed to heal for 6 to 9 months prior to placement of microimplants for histology and standard implants for prosthetic rehabilitation. After another 6 months of healing, when abutments were connected, the microimplants were retrieved for histologic and morphometric analyses. The outcome of the standard implants was clinically evaluated after 1 year of loading. Results: The mean bone-implant contact was 34.6 ± 9.5%, 54.3 ± 33.1%, and 31.6 ± 19.1% for autogenous bone, mixture of 20% autogenous bone/80% BH, and 100% BH, respectively. The corresponding values for the bone area parameter were 37.7 ± 31.3%, 39.9 ± 8%, and 41.7 ± 26.6%. The BH area was found to be 12.3 ± 8.5% and 11.8 ± 3.6% for 20% autogenous bone/80% BH and 100% BH, respectively. There were no statistically significant differences for any parameter between any of the groups. After 1 year of loading, 6 of the 33 implants placed in autogenous bone grafts, 2 of the 35 implants placed in the BH/autogenous bone mixture, and 2 of 43 implants placed in BH were lost. There were no statistically significant differences between any of the groups. Discussion: The histomorphometric analysis showed no differences between the 3 groups, indicating that autogenous bone graft can be substituted with bovine hydroxyapatite to 80% or 100% when used for maxillary sinus floor augmentation. The effect of adding autogenous bone remains unclear but may allow for a reduction of the healing time. Conclusion: The results from this clinical and histologic study indicate that similar short-term results can be expected when using autogenous bone, BH, or a mixture of them for maxillary sinus floor augmentation and delayed placement of dental implants.

Purpose: Many situations in clinical practice require metallic implants to be combined with bone grafts and/or bone substitutes such as bioactive glass (BG). Upon implantation, silica-based BG particles are transformed into a shell containing calcium and phosphate that loses its inner silicon-rich core. The release of silicon by BG particles and its incorporation by newly formed bone tissue in the peri-implant area had not been studied to date. Materials and Methods: Thirty Wistar rats were used throughout. Under anesthesia, a commercially pure titanium (Ti) laminar implant was placed inside the medullary compartment of the tibia (Ti group), while in the contralateral tibia (Ti/BG group) a titanium laminar implant and melt-derived BG 45S5 particles were implanted. The animals were sacrificed 14, 30, and 60 days postimplantation. The tibiae were resected, radiographed, and embedded in methyl methacrylate resin. Sections were stained with toluidine blue and analyzed by light microscopy and energy-dispersive x-ray analysis (EDX). The presence of silicon, calcium, and phosphorus was evaluated in the BG particles and in the peri-implant bone tissue for each of the experimental times. Results: The histomorphometric study revealed an increase in peri-implant bone thickness in the Ti/BG group as compared to the Ti group. EDX of newly formed bone tissue showed a transient appearance of silicon at 14 and 30 days postimplantation and a rise in the calcium:phosphorus ratio in peri-implant bone tissue in the Ti/BG group. Discussion: The present study shows an increase in reactive medullary bone formation when BG particles are implanted around a Ti implant. Conclusion: The results described in the present study reveal that the release of Si by BG particles is an important issue that warrants further study.

Purpose: The aim of this study was to compare the force and moment distributions that develop on different implant overdenture attachments when vertical compressive forces are applied to an implantretained overdenture. Materials and Methods: The following attachments were examined: Nobel Biocare bar and clip (NBC), Nobel Biocare standard ball (NSB), Nobel Biocare 2.25-mm-diameter ball (NB2), Zest Anchor Advanced Generation (ZAAG), Sterngold ERA white (SEW), Sterngold ERA orange (SEO), Compliant Keeper System with titanium shims (CK-Ti), Compliant Keeper System with black nitrile 2SR90 sleeve rings (CK-70), and Compliant Keeper System with clear silicone 2SR90 sleeve rings (CK-90). The attachments were tested using custom strain-gauged abutments and 2 Brånemark System implants placed in a test model. Each attachment type had one part embedded in a denturelike housing and the other part (the abutment) screwed into the implants. Compressive static loads of 100 N were applied (1) bilaterally, over the distal midline (DM); (2) unilaterally, over the right implant (RI); (3) unilaterally, over the left implant (LI); and (4) between implants in the mid-anterior region (MA). Both the force and bending moment on each implant were recorded for each loading location and attachment type. Results were analyzed using 2-way analysis of variance and the Duncan multiplerange test. Results: Both loading location and attachment type were statistically significant factors (P .05). In general, the force and moment on an implant were greater when the load was applied directly over the implant or at MA. Discussion: While not significant at every loading location, the largest implant forces tended to occur with ZAAG attachments; the smallest were found with the SEW, the SEO, the NSB, the CK-70, and the CK-90. Typically, higher moments existed for NBC and ZAAG, while lower moments existed for SEW, SEO, NSB, CK-90, and CK-70. Conclusion: For different loading locations, significant differences were found among the different overdenture attachment systems. Schlagwörter: dental precision attachments, forces and moments, loading, overdenture, strain gauge

Purpose: The purpose of the present investigation was to examine to what extent precision data from 3-dimensional planning software for oral implants can be transferred to the operative field by means of a drilling template, containing high-precision drilling sleeves, fitted on the jawbone. It was investigated whether this procedure would allow advance preparation of a fixed definitive prosthesis that could be placed at the completion of surgery. Materials and Methods: This procedure was experimentally carried out in 2 cadavers and later in 8 consecutive human patients. Results: The results indicated a nearly perfect match between the positions and axes of the placed implants and those planned. Discussion: This procedure permitted the placement of a definitive fixed prosthesis with limited freedom of space between the abutments and the metallic cylinders incorporated into the prosthesis. Conclusion: These encouraging results of the Leuven information technology-based oral rehabilitation by means of implants (LITORIM) are presently being further investigated at the clinical level.

Purpose: The purpose of this study was to evaluate the outcome of the 3 different diameters of Brånemark System implants, with special focus on the 5.0-mm-diameter implant. Materials and Methods: Ninety-eight patients (99 jaws) with a mean age of 62 years were included in this retrospective report. The mean follow-up period was 2 years and 8 months. A total of 379 Brånemark System implants (3.75 mm diameter, n = 146; 4.0 mm diameter, n = 76; 5.0 mm diameter, n = 157) were placed in 29 edentulous and 70 partially edentulous jaws. Results: Eight of the 146 implants in the 3.75-mm-diameter group failed (5.5%). The corresponding figures for the 4.0- and 5.0-mm-diameter implants were 3 of 76 (3.9%) and 7 of 157 (4.5%), respectively. Discussion: All failures were recorded in maxillae, ie, 18 of the 298 placed, and the majority of these were found in bone quantity group B and quality group 2. Only 3 implants of 131 failed in bone judged as quality 4. The marginal bone loss was low for the 3 implant diameter groups. Conclusion: The favorable outcome in bone of poor quality is ascribed partly to the use of an adapted preparation technique and extended healing periods for achievement of the best primary and secondary implant stability possible.

Purpose: Studies of maxillary overdentures supported by endosseous implants often show a high implant failure rate. The aim of the present investigation was to evaluate clinically and radiographically non-submerged implants supporting an overdenture in the maxilla. Materials and Methods: Forty-one patients were consecutively admitted for treatment. The standard procedure was to place 4 implants and to mount a U-shaped bar for overdenture connection. When the overdenture was delivered to the patients, peri-implant parameters were recorded and radiographs were taken. All patients were required to follow a maintenance care program. In the context of this study, all patients were clinically examined and the peri-implant parameters were compared. Crestal bone loss was analyzed using linear radiographic measurements. A life table analysis was applied to calculate the cumulative survival rate (CSR). Results: Three implants failed in the early healing phase, and 3 patients lost 6 implants during the loading period. The 5-year CSR of all implants was 94.2%. The peri-implant parameters gave evidence of healthy soft tissues and good oral hygiene. The increases in probing depths and attachment loss were significant (P .05). The mean marginal crestal bone loss was about 0.7 mm and was statistically significant at mesial and distal sites (P .001). Discussion: The correlation between clinical attachment loss and crestal bone loss was not significant. Pronounced marginal bone loss was found around some implants. Conclusion: In planned maxillary overdenture treatment, it is possible to achieve a satisfactory survival rate of the implants.

Purpose: This retrospective study investigated whether or not implants can be placed successfully without sinus grafts in atrophic posterior maxillary ridges with ¡Ü 4 mm of bone utilizing the localized management of the sinus floor technique as described by Bruschi and coworkers. Materials and Methods: Fifty-eight implants were placed in 34 consecutive patients with an average vertical height of 2.87 mm of residual bone under the sinus. The implants were placed at the time the sinus membrane was elevated. Results: The sinus was ¡°raised¡± an average of 9.12 mm without benefit of bone grafts or membranes. The success rate after 22 months of loading was 91.4%. Discussion: The localized management of the sinus floor (LMSF) technique permits osseointegration of titanium implants by an endosteal-periosteal continuum that is unhindered by the need of graft material to resorb. Conclusion: This preliminary study demonstrated that it is possible to place implants in an atrophic alveolar ridge with ¡Ü 4 mm of bone without the need for a traditional sinus graft.

Purpose: The presence of periodontopathic bacteria is a risk factor for peri-implantitis. The present study examined colonization by periodontopathic bacteria and their transmission from periodontal pockets to osseointegrated implant sulcus. Materials and Methods: Plaque samples were collected from 105 sites in the 15 patients who participated in the study. Colonization by these bacteria was examined by polymerase chain reaction (PCR) and culture. The transmission of periodontopathic bacteria from periodontal sites of natural teeth to the implant sulcus was analyzed by pulsed field gel electrophoresis (PFGE). Results: The PCR detection rates of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, and Treponema denticola were 80.0%, 53.3%, 46.7%, 60.0% and 40.0%, respectively. Colonizations by P gingivalis and A actinomycetemcomitans were statistically correlated with periodontal pockets and implant sulcus regions (P .01). The PFGE patterns of the P gingivalis strains isolated from each patient were identical, but differed from those from other patients. The PFGE patterns of P intermedia strains were identical in 2 out of 3 patients. Discussion: These analyses indicated that there appeared to be transmission of P gingivalis and P intermedia from the periodontal pocket to the peri-implant region. Conclusion: Elimination of these periodontal pathogens from the patient's oral cavity before administering dental implant treatment may inhibit colonization by these pathogens and reduce the risk of peri-implantitis.

Pathologies of the implant cavity wall currently cannot be diagnosed by direct observation because of the rapid pollution of the optical systems used. A technique to examine prepared implant sites intraoperatively to diagnose possible risk factors for the osseointegration process is presented. Examination of implant cavities is performed with support immersion endoscopy (SIE). Using a specially designed support and irrigation sheath (SIS), a 1.9-mm endoscope can be placed at a certain distance to the underlying bone surface. When immersed in a bleeding implant site, the endoscope window is cleaned by continuous laminar irrigation flow to allow observation of the cavity walls under variable magnification. Cortical and cancellous bone structures can be differentiated in situ and pathologies detected during capillary bleeding. Two case reports citing practical applications are reported. By means of SIE, possible risk factors during and after implant cavity preparation can be detected.

Purpose: Titanium endosseous implants are becoming increasingly important in dentistry because of their excellent long-term results. However, it has been reported that these implants may lead to higher concentrations of titanium, especially in the lungs and kidneys. The purpose of this study, therefore, was to determine whether CO2 laser-assisted decontamination of exposed implant surfaces is associated with an increase in titanium release. Materials and Methods: In 6 beagle dogs, a total of 60 implants were placed. After osseointegration and second-stage surgery, peri-implantitis was induced by cotton floss ligatures for 12 weeks. Surgical treatment consisted of granulation tissue removal, including decontamination of the implant surface with 3 different methods. Twenty implants were decontaminated conventionally by an air-powder abrasive for 60 seconds. Another 20 implants were decontaminated by laser treatment alone. The last 20 implants were treated conventionally by air-powder abrasive and then lased. Four months later, fresh tissue samples of various tissues were evaluated by histologic and chemical analysis. Results: Quantitative analysis indicated that titanium accumulation could be detected, especially in the spleen, liver, oral mucosa, regional lymph nodes, lung, and kidney in the beagle dog model. Discussion: The concentrations found did not exceed those previously reported in the literature. Conclusion: These results support the hypothesis that CO2 laser-assisted therapy of ailing implants will not result in excessive titanium concentrations in tissues. Accordingly, CO2 lasers appear suitable and safe for peri-implant gingival surgery.

The Novum System offers a unique opportunity to create a definitive, immediately loaded fixed prosthesis on the edentulous mandible for patients who meet specific presurgical criteria. Since this system is based on precisely placed implants and prefabricated bar structures, the surgical techniques are critical in obtaining a satisfactory result. It is especially important that the bone reduction required to create space for the implants and bar assembly be in the proper plane and deep enough to leave room for eventually setting and processing teeth. The surgical guide described here can be an important adjunct during bone reduction to assure proper spatial positioning of the preformed titanium bars. Mounted casts of the correct or corrected maxillary dentition and mandibular arch are required at the appropriate vertical dimension of occlusion. The mandibular cast is reduced in prescribed dimensions to allow the subsequent creation of a processed resin surgical guide for use during the initial stages of surgery. This guide, when used for bone reduction during surgery, eliminates the arbitrary removal of osseous structure and helps assure the plane of implant placement is appropriate for each patient. When used routinely, a significant complication of the Novum procedure can be minimized or eliminated completely. Setting of teeth and processing are subsequently simplified, especially in the posterior dimensions, with this guide technique.

An implant has been developed as an adjunct to conventional orthodontic anchorage. Planning is advisable to determine the available bone and soft tissue thickness and the optimum position for orthodontic utilization. A simple method is described for fabrication of a radiographic and surgical template to aid in optimal placement of the implant.

This article describes a procedure to harvest bone from the zygoma for alveolar bone reconstruction. A detailed description of the bone harvesting procedure and a preliminary report of 3 patients undergoing alveolar bone reconstruction and simultaneous dental implant placement in the maxillary anterior area is presented. The technique is indicated when a modest amount of bone is needed, for example, to cover exposed implant threads and expand a narrow alveolar ridge. It also could be used as an additional source of bone with other intraoral donor sites. Surgical access to the zygoma is simple and can be performed using local anesthesia. Postoperative complications after zygomatic bone harvest are minimal.

Animal studies have shown that a periodontal ligament may be produced around a titanium implant when it is in contact with fractured and retained roots. Formation of cementum and attachment connective tissue around titanium implants confirms that cementum progenitor cells are located in the periodontal ligament, since cementum and periodontal ligament are present at the implant-root interface, whereas the remainder of the implant, which is not in contact with the root, shows osseointegration. The aim was to evaluate histologically the characteristics of the tissue present between a titanium implant and a retained root, which were subsequently extracted as a result of peri-implantitis. The histologic examination revealed a continuous layer of cementum and numerous cementocytes on the implant surface. No blood vessel or collagen fibers were detected in the periodontal space. In contrast to experimental studies carried out on animals, the lack of connective tissue fibers and the presence of hypercementosis in this specimen could have been caused by the inflammatory process. Furthermore, the extrusive movement of the root might explain the presence of cementum hypertrophy. Further studies are required to establish whether the neoformation of cementum and collagen fibers on an implant in the presence of root residues occurs only in animal models or whether it may also occur in humans.