The International Journal of Oral & Maxillofacial Implants, 03/1994

The most commonly used techniques for uncovering implants in stage 2 surgery are listed and the advantages and disadvantages are described. A reconstructive technique as used by the authors is described and clinically evaluated. Use of the reconstructive technique creates a significantly broader fixed mucosa. In patients with less than 4 mm of preoperative fixed mucosal width, the destructive techniques often leave no postoperative fixed mucosa whatsoever. Keywords: dental implants, stage 2 dental surgery

Besides bone, two other tissues directly contact an osseous implant and/or attachments to it: epithelium and soft connective tissues including the gingival connective tissue. These tissues have received less attention than bone, but are required because of the transmucosal nature of endosseous dental implant restorations. The attachment and growth of human gingival and periodontal ligament fibroblasts and an epithelial cell line to titanium with various surface textures have been examined. Of the three cell types examined, gingival fibroblasts attached best, followed by periodontal ligament fibroblasts and the epithelial cells. Both fibroblast cell types had more cells attached to control (tissue culture plastic) and smooth titanium than either of two rough surfaces. However, once attached, the fibroblast cells grew well on smooth and rough titanium. Epithelial cells did not attach well to any of the surfaces but after a lag period proliferated on control and smooth titanium, although not on either rough titanium surface. This study demonstrates that, as has been found in vivo, human fibroblast and epithelial cell attachment and proliferation are significantly affected by surface characteristics of titanium. These studies suggest that surface texture could be used to guide specific cell attachment to the dental implant. They also provide an in vitro model in which agents such as inflammatory mediators and growth factors could be examined on specific cell function on titanium with distinct surface characteristics. Keywords: cell attachment, epithelial cells, fibroblasts, implant surfaces, titanium implants

Using both in vivo and in vitro experiments, we have demonstrated that reconstituted collagen will undergo mineralization in a healing bony compartment and that this mineralization is the result of spontaneous precipitation of calcium salts related to the presence of alkaline phosphatase produced by the bone cells. Once calcified, the collagen will undergo cellular resorption by tartrate-resistant multinucleate giant cells similar to osteoclasts. This sequence of events is quite different from that in the suprabony soft tissue compartment, where no calcification of the collagen is apparent, the collagen matrix becomes infiltrated with fibroblast-like cells, and little resorption of the matrix occurs during implantation. It is concluded that reconstituted collagen may be employed as both a tissue barrier, enhancing guided tissue regeneration, and a bone-substitute material that is replaced by natural bone tissue. Thus, materials exhibiting these site-specific reactions are particularly suitable for use in immediate implant placement following tooth extraction. Keywords: bone healing, collagen, guided tissue regeneration, immediate implants

Regenerated bone around implants promoted by an e-PTFE barrier membrane technique was tested to evaluate its capacity to withstand loading. Twenty-four implants were placed into fresh extraction sockets with buccal dehiscences in four dogs. Twelve sites were augmented with barrier membranes. Histologic evaluation of 3-month-postoperative biopsies taken from two dogs showed significantly more bone formation for the augmented sites than for the nonaugmented implants (P .02). The augmented sites in the remaining two dogs demonstrated complete bone fill of the original defects. After 6 months of prosthetic loading, histologic evaluation of four augmented sites showed a decrease in bone fill from that at 3 months postoperative. Premature loading of immature bone was believed to be the primary reason for the bone loss. The remaining two implants in the augmented and non-augmented groups served as unloaded controls. After 6 months of further healing, the augmented but unloaded group demonstrated complete bone fill, with more mature bone quality than the 3-month histologic specimens. For the nonaugmented sites, no new bone formation occurred between the 3- and 9-month healing periods. The results from this study indicate that bone augmentation with barrier membranes should be allowed extended healing periods prior to loading. The precise time for loading of newly regenerated bone with e-PTFE membranes has not been determined. Keywords: bone regeneration, dogs, e-PTFE, loading, membranes, titanium implants

The objective of this study was to identify and compare the subgingival bacterial population around Brånemark implants and natural teeth using an enzymatic test (kit SK-013, Periocheck) to determine the trypsin-like activity of the subgingival bacterial population. Significant difference was seen between SK-013 activity and increased probing depth for both teeth and implants. The morphologic bacterial composition in subgingival plaque samples was examined by phase contrast microscopy. Spirochetes were conspicuously absent around implants in totally edentulous patients, but were present in those from partially edentulous patients. The present study indicates that the use of SK-013 to determine the trypsin-like enzymatic activity of dental plaque around implants is a simple and useful method and is similar to counting motile rods and spirochetes. Keywords: Brånemark implants, enzymatic activity, peri-implant condition, subgingival microbial flora

A new insertion technique, pilot-hole preparation, has been developed for proper implant positioning. The purpose of the technique is to prepare pilot holes in positions determined by diagnostic waxup and to form implant channels by means of pilot holes with an instrument called the trephine guide pin. The insertion technique has been shown to be effective for proper implant placement through simulated tests. The advantages of the technique are discussed. Keywords: Apaceram, implant position, pilot-hole preparation, trephine guide pin

Nonrotational capability is recommended for multiple-implant supported prostheses, as well as single-tooth restorations. Interlocking interfaces facilitate the fabrication of custom re-angulated abuments when required, provides built-in troubleshooting redundancy in the event of implant loss, and helps reduce torque on retaining screws. The path of insertion can be established in the laboratory with a verification jig and any interferences adjusted or reangulated, or a standard gold cylinder substituted with compatible armamentarium. Brånemark nonrotational abutments can be used in place of standard abutments for all multiple-implant-supported prostheses, regardless of position or orientation. When required, a standard gold cylinder can be used with the Brånemark nonrotational abutment. Specialized abutments, such as the Estheticone, can also utilize nonrotational conical cylinders to reduce torque on the gold retaining screws. Keywords: abutment reangulation, male-female interlocking interface, nonrotational configuration, nonrotational redundant capability, preloaded interface, systems interchangeability

Partial edentulism in a 16-year-old female with Hermansky-Pudlak syndrome was treated using the Brånemark osseointegration technique. Two 15 x 3.75 mm implants were placed in the mandibular anterior area. The two implants were tested for mobility using a Periotest instrument at the time of the implant placement, at abutment connection, and at 3 months following delivery of the final prosthesis. The results from this study showed that the Brånemark osseointegration procedure can be used to treat patients with platelet disorders affecting the clotting mechanism. Keywords: Hermansky-Pudlak Syndrome, implants, osseointegration, Periotest, platelet disorders

The course of the mental nerve within the mandible was examined in 37 human specimens. Two different types of pathways were found. In 22 cases, a siphon (ie, an arch that travels laterally and cranially) was observed. This type of path was classified as Type I. The distance measured between the mental foramen and the most anterior point of the canal was up to 5 mm. There was no correlation between this distance and the degree of atrophy. In 15 specimens, the mental canal ascended directly from the mandibular canal to the mental foramen without curving forward. This type of course was classified as Type II. The average angle of inclination between the plane through which the mental canal courses and the horizontal plane was 50 degrees. Based on the present data, it is recommended that a safe distance of at least 6 mm anterior to the mental foramen be maintained when performing surgery in the mandibular premolar region. Keywords: implants, mental canal, mental foramen, mental nerve

A study was conducted to investigate the hypothesis that mechanical loading of implants and the consequent stress and strain fields influence bone modeling and remodeling at the bone-implant interface. Two implants ad modum Brånemark were placed in each of 20 canine tibiae, allowed to heal for I year, and then subjected to a controlled loading protocol. Implants in the left limb were loaded in axial tension with a triangular waveform (300 N maximum, 10 N minimum, 330 N/s) for 500 cycles per day for 5 consecutive days; implants in the right limb served as unloaded controls. Twelve weeks after loading, polished undecalcified thick sections were examined with light and scanning electron microscopy to provide bone modeling and remodeling data, including the surface area of periosteal and endocortical modeling, the percentage of mineralized tissue in the bone threads, and the frequency of occurrence of preloading and postloading fluorochrome bone labels. Also, a three-dimensional finite element model was developed to investigate the strain state in the bone near loaded implants. The morphometric data were statistically analyzed in terms of individual load-control pairs and showed the following trends for loaded implants: (1) a net bone loss near the coronal portion of the implant, (2) a smaller percentage of mineralized tissue in the cortex, and (3) a decreased frequency of occurrence of postloading fluorochrome bone label in the cortex adjacent to the implant. The finite element model indicated regions of high strain on the periosteal surface adjacent to the loaded implants. The results support the premise that the bone loss observed around the neck of the loaded implants at 12 weeks postloading was a consequence of bone modeling and remodeling secondary to bone microdamage caused by the loading protocol. This scenario, as well as certain other features of the bone response at the interfaces, can be interpreted in light of existing bone modeling and remodeling theories that relate bone activities and mechanical loading. Keywords: bone modeling, bone remodeling, interface, microdamage, overload

Each available cylindrical endosseous dental implant requires unique prosthodontic components to restore osseointegrated implants. The prosthodontist may not always have the opportunity to dictate the implant system for every patient, since this decision too frequently is made by the surgeon without prior consultation with the restoring dentist. Therefore, a large inventory of prosthetic components for each manufacturer's system is required. To address this problem, third-party manufacturers developed the concept of the universal abutment. The purported advantages of prosthetic-component standardization, regardless of the type of implant, are appealing. A case report involving a patient requiring prosthetic rehabilitation of posterior edentulous quadrants using IMZ implants is presented. The Universal Modification Abutment replaced the intramobile element and transmucosal extension. The advantages include a one-piece titanium-alloy tissue extension, more variety of transmucosal lengths, and compatibility of the prosthetic components regardless of implant. Keywords: compatibility, implants, prosthodontics, universal abutment