Submerged alumina dental root implants in humans: five-year evaluation.

This article describes the placement, success rate, and evaluation of an experimental alumina (Al2O3) ceramic dental implant at a mean placement time of 5 years. The study compared the longevity of a submerged implant of the same root design and a refined surgical technique with previously reported studies of the implant exposed to the human oral environment during initial healing. A 54% success rate was achieved for 29 implants placed in the maxillae and mandible, all restored with cast gold dental crowns. A significant difference (p = 0.05) appeared between success and failures at 7.8 months following placement. Crown/root ratio slopes were an earlier and more sensitive indicator of potential success or failure than the bone height slopes. Computer analysis revealed no apparent correlation between implant mobility and/or pocket depths and implant longevity. Delayed implant root fractures and a cast post fracture occurred in 20% of the implants that survived.

Bone loss following periodontal therapy in subjects without frequent periodontal maintenance.

The longitudinal effects of periodontal therapy in patients without a frequent periodontal maintenance program have been minimally documented. In this study we used Duckworth's modification of the Schei Ruler Technique to assess the difference in bone level around individual teeth treated for periodontal disease in subjects receiving infrequent posttherapy maintenance (less than or equal to 1 time/year). Crestal bone height differences were evaluated using the initial presenting series of long cone parallel radiographs of 23 subjects with their subsequent posttherapy analogous radiographic series taken 5.4 +/- 2.9 years later. Bone loss was defined as a reduction in the alveolar crest of greater than 50% of the radiographic crown height which corresponds to approximately 4 mm in posterior and 5 mm in anterior teeth. The loss for each tooth was expressed as a per cent of the measured height of the crown after conversion from millimeters using the mean crown-root ratio for each tooth. We found increased alveolar bone loss and tooth loss in subjects examined posttherapy when compared with conditions present when each subject initially presented for periodontal treatment. Our data suggest that molar teeth are more at risk than incisors and cuspids and that a lack of periodontal maintenance care and inadequate plaque control contribute to progressive bone loss following treatment.

A method for the geometric and densitometric standardization of intraoral radiographs.

The interpretation of dental radiographs for the diagnosis of periodontal disease conditions poses several difficulties. These include the inability to adequately reproduce the projection geometry and optical density of the exposures. In order to improve the ability to extract accurate quantitative information from a radiographic survey of periodontal status, a method was developed which provided for consistent reproduction of both geometric and densitometric exposure parameters. This technique employed vertical bitewing projections in holders customized to individual segments of the dentition. A copper stepwedge was designed to provide densitometric standardization, and wire markers were included to permit measurement of angular variation. In a series of 53 paired radiographs, measurement of alveolar crest heights was found to be reproducible within approximately 0.1 mm. This method provided a full mouth radiographic survey using seven films, each complete with internal standards suitable for computer-based image processing.

The effects of spectral distribution on x-ray image quality.

Broad and monoenergetic x-ray spectra were analyzed with a computer to determine the photon signal-to-noise ratio, exposure modulation, and integral dose in a simulated caries detection task. Assuming an ideal exposure geometry, it was possible to compute relative values which permit meaningful comparison of spectra in terms of these parameters. The broad spectra were measured with a high-resolution spectrometer system. The data were corrected for spurious effects and analyzed with an idealized attenuation model. The results suggest that spectral changes brought about by even relatively small amounts of selective filtration in region between 25 and 45 keV. measurably influence the potential for diagnostic quality.