The International Journal of Oral & Maxillofacial Implants, 01/1999

The recent announcement of the discovery of a first or second century AD Roman example of a dental implant appears to fall into a category of spurious claims regarding ancient dentistry. Several earlier claims of the discovery of impressive examples of ancient dentistry are reviewed, followed by a discussion of the recent discovery from France. This survey of all of these claims regarding finds of ancient dental implants, plus data from the modern and rapidly evolving field of implant dentistry, suggests that these "ancient implants" are the product of the imaginations of 20th-century archaeologists. Keywords: ancient dentistry, dental history, implants

A new soft tissue flap design technique, called "the palatal sliding strip flap" (PSSF), has been developed to improve the soft tissue surgical results at stage 2 implant surgery. The purpose of this flap design is to help form papillae between implants and between natural teeth in the anterior area of the maxilla. The flap is designed and managed so that the palatal attached mucosa slides in a labial direction to create papillae and at the same time augment the labial ridge. This surgical approach is valid, predictable, and has a low risk-to-benefit ratio. This new flap design is indicated for a variety of clinical situations, especially for the problematic maxillary soft tissue reconstruction around teeth and implants. Keywords: flap design, palatal strip, papilla regeneration

Altering osseous responses at implant surfaces to enhance bone is a current goal of clinical therapy. Cell culture may be used to investigate surface-dependent responses of bone-forming cells. In this report, the ability of primary fetal bovine mandibular osteoblast cultures to form a mineralizing matrix on machined, titanium plasma-sprayed, and titanium oxide grit-blasted surfaces has been compared. Immunohistochemical markers associated with bone formation were used to define the differentiated state of the formed matrix using qualitative light microscopy, and von Kossa staining was used to demonstrate the presence of mineralization within this matrix. Compared to either titanium oxide grit-blasted or machined surfaces, titanium plasma-sprayed surfaces displayed a unique pattern of mineralized matrix formation. Scanning electron microscopy further revealed that each surface accumulated unique organic and inorganic deposits during matrix formation, suggesting that surface-dependent physicochemical and biochemical conditioning of implant surfaces takes place. Surface topographic features of commercially pure titanium substrates can alter cultured osteoblast extracellular matrix formation and mineralization. Similar molecular and cellular assessment of in vivo responses to implant surface topography may contribute to improved engineering of endosseous implants. Keywords: differentiation, osseointegration, osteoblast culture, surface topography

Esthetically compromised or nonrestorable implants present major clinical problems. Of 3,850 implants placed, 10 osseointegrated implants in 6 patients were surgically repositioned using maxillary or mandibular osteotomies and rigidly fixated, under intravenous sedation. The segments were predictably changed in a vertical, anteroposterior, transverse, or axial inclination manner. Excellent healing of bone and soft tissue was observed. This simple, reliable technique allowed these 10 implants to be esthetically and functionally restored with permanent prostheses. Keywords: bone healing, compromised implants, orthognathic surgery, rigid fixation, segmentalized osteotomies

A technique for single-tooth sinus lift and simultaneous implant placement in the posterior maxilla is presented. Ten hydroxyapatite-coated cylindric implants, 13 to 15 mm in length, were placed together with a composite bone graft of demineralized freeze-dried bone allograft and autogenous bone in 10 adults. Surgical technique and anatomic considerations are discussed. Follow-up of 3 years showed successful function and no cervical bone loss in all patients. Keywords: root-form implants, single tooth, sinus augmentation

The effect of hyperbaric oxygen (HBO) on the tissue reaction around hydroxyapatite (HA) implants in irradiated bone of rats was investigated. A single dose of 15 Gy was delivered to the right leg of 20 rats. HA implants were placed in the bilateral tibial proximal metaphysis 3 months after irradiation. HBO was administered to half of the rats before and after 15-Gy irradiation. The healing process was examined histologically and histomorphometrically. The results indicated that HBO slightly improved trabecular bone formation in the irradiated bone, accelerated bone remodeling in the nonirradiated bone, and improved HA-bone contact in both the irradiated and nonirradiated bones. Keywords: hydroxyapatite implants, hyperbaric oxygen, irradiated bone, rat, tibia

The 5-year results from a multicenter study of implant-supported, laser-welded titanium frameworks are reported here as a complement to earlier reported 2-year results. Implant survival rates were satisfactory for patients with titanium frameworks and for a control group of patients with gold-alloy frameworks. At the 5-year review, more patients with titanium frameworks had lost implants than the patients with gold-alloy frameworks, but this difference was not statistically significant. More fractures of the titanium frameworks occurred, compared to the gold-alloy frameworks; again, this difference was not statistically significant. No significant differences in marginal bone levels were found between the 2 groups of patients. Slightly more fractures of artificial teeth occurred in patients with titanium frameworks than in patients with gold-alloy frameworks. Overall results for the titanium frameworks after 5 years in function are encouraging. Keywords: dental implants, multicenter study, titanium frameworks

The aim of this study was to investigate the possible use and ultimate fate of anorganic xenogenic bone for the restoration of defects in the maxillae and mandibles of adult rabbits. Furthermore, anorganic xenogenic bone was compared with implanted autogenous bone particles with regard to the response of the surrounding connective tissue and possible resorption of these implants by multinucleated cells. Results showed that after 12 weeks, the implanted autogenous bone was actively resorbed by multinucleated cells, and new bone was formed in close apposition to the particles. In contrast, implanted anorganic xenogenic bone was degraded to a much lesser extent, and new bone was seen adjacent to the anorganic bone particles without signs of resorption. Further long-term studies are needed to determine whether anorganic xenogenic bone may be regarded as a resorbable material and whether any side effects occur as a result of this material's tendency to linger on in the recipient bed. Keywords: anorganic bovine bone, Bio-Oss, implant, rabbit

The purpose of this study was to determine the maximum permissible x-ray tube angulation that can be used to verify the fit of an abutment. An implant and an abutment were assembled with an abutment screw. A variety of openings were created between the abutment and the implant. Radiographs were taken combining the different gaps with various x-ray tube angulations. The radiographs were randomly presented to 8 clinicians, who judged the interface as open or closed. The results indicate that a radiographic analysis of interface openings becomes subjective with tube angulations of more than 5 degrees. Keywords: abutment fit, dental implant, film positioner, interface, radiographs, tube angulation

The objective of this study was to evaluate the bone quantity of alveoli grafted with autogenous particulate cancellous bone and marrow for implant placement in patients with alveolar clefts. Bone height, bone width, and interdental alveolar crest level were evaluated using computed tomography and periapical radiographs. The grafted alveoli underwent resorption 3-dimensionally, and the interdental alveolar crest level also decreased. The latter seemed to be the critical factor for implant surgery, as almost half of the grafted alveoli required another bone graft within 24 months after the original bone graft to increase the interdental alveolar crest level for endosseous implant placement. These data suggest that alveoli grafted with particulate cancellous bone and marrow are suitable for implant placement, but that the loss of width and height of the bone bridge must also be considered. Keywords: bone bridge, bone graft, cleft lip or palate, grafted alveolar cleft, interdental alveolar bone height, particulate cancellous bone and marrow

Microleakage can occur at the abutment-implant (A-I) interface in osseointegrated implants and may cause malodor and inflammation of peri-implant tissues. The degree of microleakage at the A-I interface of 5 implant systems was comparatively assessed at varying closing torques. Using colored tracing probes driven by a 2-atm pressure system, the interface microleakage of Brånemark, Sulzer Calcitek, 3i, ITI, and Steri-Oss implants was determined spectrophotometrically. Microleakage through the A-I interface occurred in all systems, with variability between systems, samples, and closing torques. As closing torque increased from 10 Ncm to 20 Ncm to manufacturers' recommended closing torques, microleakage decreased significantly (P .005) for all systems. Analysis of variance showed significant interaction between closing torques and the time course of microleakage, and between systems and the time course of microleakage (P .001). The results indicate that fluids and small molecules are capable of passing through the interface of all the A-I assemblies studied. Presumably in an in situ situation, fluids containing bacterial byproducts and nutrients required for bacterial growth may pass through the interface gap, contributing in part to clinically observed malodor and peri-implantitis. Keywords: closing torque, implant, microleakage, preload, screw loosening

In recent years, indications for endosseous dental implants have been extended to include partially edentulous jaws with areas of limited bone density and bone volume. Wide-diameter implants are particularly well suited for these situations. The purpose of this paper was to report on 98 consecutively placed 5-mm-diameter implants without smooth surface collars. Eight implants failed-6 at second-stage surgery, and 2 after 1 year of loading (91.8% survival rate). Sixty percent of the remaining implants had no thread above the bone level after 1 year of loading. The authors discuss the possible causes for failure and suggest guidelines to avoid failure. Keywords: bone loss, dental implant, wide diameter

The aim of this study was to investigate the ultrastructural and immunohistochemical organization of the main collagenous components of healthy human keratinized mucosa surrounding endosseous implants. Eight patients with completely edentulous mandibles were selected. Four endosseous implants were placed in the mandible of each patient, connected with a bar to support a complete overdenture, and loaded 4 months later. Two years after placement, biopsies of surrounding soft tissue, including the sulcular and junctional epithelium with the underlying and supracrestal connective tissue, were routinely prepared for standard electron microscopy and for ultrastructural immunolabeling of Types I, III, and IV collagen. The connective tissue located under the junctional epithelium comprised Types I and III collagen, whereas the supracrestal connective tissue was composed mainly of Type I collagen. Type IV collagen was located exclusively in the basement membrane of the junctional epithelium. Keywords: collagen, immunotyping, peri-implant mucosa, ultrastructure

Osseointegrated implants are widely used in dental rehabilitation. They are particularly valuable if the structures supporting a denture had to be removed because of oral cancer. Additionally, many of these patients undergo radiotherapy, but cancer and radiotherapy are seen as relative contraindications for implant therapy. In the literature, there are few clinical studies documenting successful oral rehabilitation using implants in such patients. The authors report a clinical case in which histologic evidence of osseointegration can be demonstrated in an irradiated and reconstructed mandible. This observation should encourage the extended application of implants in rehabilitation following oral cancer surgery. Keywords: dental implants, mandibular reconstruction, oral cancer, radiotherapy

Experience with 9 patients who underwent mandibular reconstruction with autogenous free bone grafts and subsequent placement of titanium screw-type implants is reported. The interval between bone grafting and implant placement in these patients ranged from 8 to 34 months. A total of 33 implants was placed, followed up for 16 to 53 months, and achieved an 85% survival rate. Analysis of these patients reveals that the type of bone graft used is integral to successful prosthodontic reconstruction to ensure viability and minimal resorption as well as the timing of implant placement. Keywords: mandibular reconstruction, oral cancer, osseointegration, titanium implants

Atraumatic preparation of the recipient site has been considered an important factor influencing implant survival. Heat generation during bone drilling has been reported to be related to various factors. The methodology for heat assessment and bone examination together with the osseous models are still points of great speculation. The present paper classifies and discusses some of those factors in detail from both biologic and clinical perspectives. The methods of heat assessment and bone examination are reviewed, and the advantages and the limitations of each technique are presented. Future considerations based on clinical data reported are suggested. Keywords: dental implant, heat generation, osseointegration, osseous models, thermocouple, thermography