Biomedical subjects
Publications and source records attributed to D L Koth.
This article describes a study of the efficacy of the non-steroidal anti-inflammatory drug flurbiprofen in maintaining alveolar bone around mandibular root-form dental implants. The preliminary results indicate that, in appropriate doses, flurbiprofen may spare bone around such implants.
This study conducted a longitudinal prospective clinical study of the single-crystal sapphire (Al2O3) cylindrical screw-shaped endosteal dental implant, and attempted to establish clinical parameters to evaluate implant success or failure. Twenty-eight mandibular implants (17 patients) were placed. After six weeks' healing, 23 implants in 15 patients served as distal abutments for fixed prostheses (baseline). Implants were evaluated for bleeding index, crevicular fluid volume index, plaque accumulation index, radiographic index, mobility index, and patient comfort. Any implant failing in three of these criteria or implants removed were judged as failures. After 10 years, of the 21 baseline implants recalled (two implants were lost to recall), 17 were fully functional, for an 81% success rate. The use of qualitative and quantitative clinical evaluation parameters as utilized in this study appears to be important and useful in assessments of the clinical serviceability of dental implants. These parameters can be used in human clinical trials as well as in experimental animal studies.
Scanning electron microscopy (SEM) and its associated technologies have proven invaluable in elucidating the interfacial oral tissue responses to dental implants. Since the dental implant must extend from the mandibular or maxillary jaw, through the oral mucosa, and into the oral cavity, these tissue responses include epithelium, connective tissue and bone. The continual occlusal forces acting upon these tissues reinforce the dynamic character of these tissue responses. Immediately upon implantation, a healing phase begins as a response to the implanted biomaterial. Following this immediate response a longer healing phase occurs, beginning approximately 1 week after implantation, resulting in the modeling of bone to the implant as well as the formation of epithelial attachment to the implant. This later, delayed healing continues throughout the lifetime of the implant since these tissues must die and be replaced by similar tissues. Current dental research employing scanning electron microscopy is now documenting these tissue responses. This paper reviews, in detail, SEM observations of these tissue responses.
The interface between the tissues of the oral cavity and ceramic and titanium cylindrical endosteal dental implants was investigated with correlated light microscopy, transmission electron microscopy and scanning electron microscopy. This study suggested that mandibular bone can directly interface and form an intimate association with one-stage endosteal dental implants. This potential attachment matrix is composed of a composite of calcified bone, and an osteoid unmineralized matrix in association with an apparent osteogenic connective tissue. Further, results from this study suggested that at a level inferior to the junctional epithelium, and superior to the level of crestal bone, fibrous connective tissue can attach to the dental implant. This non-loadbearing attachment of gingival connective tissue could, by contact inhibition, prevent apical epithelial migration. In association with previously documented epithelial attachment, such apical support and connective tissue attachment appears to suggest that endosteal dental implants can be adequately maintained in the oral cavity.
Identically prepared, screw-type ceramic and titanium endosteal dental implants were inserted in the jaws of adult mongrel dogs for periods of up to 6 months. Sixteen of the 32 total implants supported fixed bridgework. The interface of bone and soft connective tissues with the dental implants was examined by routine and innovative scanning electron microscopic (SEM) techniques using both secondary and backscattered electron imaging. Results demonstrated excellent bone adaptation to both titanium and ceramic implants. Direct adaptation of bone to the upper third of both type implants was observed with only minimal amounts of any intervening fibrous connective tissue. A composite of trabecular bone and fibrous connective tissue was observed in the lower two-thirds of the implants examined. Areas of bone alteration suggestive of osteoid were observed at the thread apicis of some loaded implants. From this investigation we concluded that similar longitudinal tissue responses were generated to one-piece, cylindrical screw-type titanium and alpha alumina oxide ceramic dental implants. Possible bone remodeling was observed at the thread apicis of the loaded implants, an area where occlusal forces may be distributed. We further suggest that one-stage endosteal implants are capable of maintaining a proportional bone-to-implant interface at the apical support region, similar to that suggested to two-stage implant systems.
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Dental and oral implantology have rapidly moved into the mainstream of dentistry in the last ten years with a phenomenal growth based on rapidly expanding technology, increasing public interest, and the reporting of sound scientific data. This paper reviews current knowledge about implant tissue reactions and identifies areas where additional scientific inquiry is needed. Bone- and soft-tissue healing around dental implants varies greatly depending upon the form of the implant, biomaterial used, and surgical approach. Controversy exists as to whether a direct bony-biomaterial interface is preferable over a bone-connective tissue-biomaterial interface. Scientific data are required to document whether intervening molecular layers of glycoproteins exist between implant and bone, and what role is played by these structures relative to the implant-bone interface. The adaptation of regenerated gingival epithelium to an implant is critical for the development of a perimucosal seal. Many scientific questions remain unanswered about this seal and its role in maintenance of implant longevity. Controlled clinical trials must be carried out to determine clinical serviceability standards for patients. Resolving these areas of concern and understanding the biological reactions involved will require in-depth scientific inquiry by clinician and scientist alike to make dental implantology a highly acceptable and predictable treatment modality. Even with these controversies and lack of comprehensive comparison studies, dental implantology is an exciting treatment concept that makes considerable demands upon the surgical, prosthetic, periodontal, and restorative skills of today's practitioners, and on their scientific understanding as well.
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Saliva was collected from 10 subjects using a universal-design parotid collector and individually-adapted submandibular collectors. The enzymic activity of kallikrein was measured using D-leucylvalylarginine-p-nitroanilide as the substrate. Mean kallikrein activity was much higher in parotid saliva than in submandibular saliva; the difference was statistically significant. Protein concentrations were not significantly different, whereas alpha-amylase was, as expected, much higher in parotid saliva.
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A technique for fabrication of custom shade tabs in tooth form has been presented. The finished product will be a series of custom shade tabs. Any temporary (provisional) resin material can be used.
The interface of the crevicular gingiva with the surface of a dental implant is a critical zone representing the potential biological seal which protects the underlying bone and soft tissue-supporting mechanisms from destructive extraneous substances. Ultrastructural examination of regenerated junctional epithelial cells interfacing surgically placed endosteal dental implants, comprised of alpha-alumina oxide ceramic in single crystalline form, exhibited an external basal lamina and linear body located between the external surface epithelial cell and the implant. In addition, hemidesmosomes were located at intervals along the outer junctional epithelial plasma membrane. The component substructures of the basal lamina and the hemidesmosomes were similar to those seen interfacing natural teeth. The linear body was an electron-dense structure between the lamina densa and the inert biomaterial. This study provides ultrastructural evidence for the presence of an attachment complex between gingiva and aluminum oxide implants which is analogous to that seen around natural teeth. These data support concept that a viable biological seal can develop around endosteal dental implants and provide support for satisfactory clinical service.
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