Performance of titanium alloy sintered porous-surfaced (SPS) implants supporting mandibular overdentures during a 20-year prospective study.

OBJECTIVE: This study was undertaken to assess short, sintered porous-surfaced (SPS), press-fit implants with mandibular overdentures to restore edentulous patients with severe mandibular resorption. MATERIALS AND METHODS: Implant lengths of 7, 8, 9, and 10 mm were used, all with 2-mm polished collars, making the designed intrabony lengths 5, 6, 7, and 8 mm. Each patient received three non-splinted implants placed using a two-stage protocol. RESULTS: Only 22 (with 53 implants) of the original 52 patients were available after 20 years. All but one of these patients was functioning with their implant-retained overdentures. Life table analysis accounted for all patients and implants, and showed a 20-year survival of 73.4%. Analysis of carefully standardized radiographs revealed mean cumulative bone loss after 20 years of 0.67 mm relative to the polished collar-SPS junction. CONCLUSIONS: Short SPS implants with mandibular overdentures can provide an acceptable treatment over a 20-year period for fully edentulous patients with severe alveolar resorption.

Development of a gel permeation chromatographic assay to achieve mass balance in cellulose acetate phthalate stability studies.

Cellulose acetate phthalate (CAP, cellulose acetate 1,2-benzenedicarboxylate) is a common polymeric oral tablet coating. CAP is also a vaginal microbicide candidate that potently inhibits HIV-1 proliferation. This paper describes the development of a precise, stability-indicating gel permeation chromatography (GPC) assay for CAP. During accelerated stability studies monitored by separate reversed-phase high performance liquid chromatography (RP-HPLC) and GPC analyses, an apparent loss of mass balance was observed. This deficit was corrected by recalculating the response factor (RF) for each degraded sample, proportional to the fraction of phthalate remaining bound to the polymeric CAP. The correction factor enabled CAP and the degradation product phthalic acid (PA) to be quantitated by a single GPC analysis. The chromatographic approach taken here could potentially apply to any polymer containing degradable chromophores.

Using transitional implants as fixation screws to stabilize a surgical template for accurate implant placement: a clinical report.

This article describes a method of using transitional implants as surgical fixation screws to orient a surgical template predictably during the placement of implants in the anterior mandible for an implant-supported bar-retained overdenture. Ridge reduction, transitional implant placement, implant placement, and removal of the transitional implants were completed in a single surgical appointment. Details of the template fabrication, incorporating transitional implants and surgical techniques, are described.

Crown lengthening: basic principles, indications, techniques and clinical case reports.

Sometimes, in order to properly restore teeth, surgical intervention in the form of a crown-lengthening procedure is required. Crown lengthening is a periodontal resective procedure, aimed at removing supporting periodontal structures to gain sound tooth structure above the alveolar crest level. Periodontal health is of paramount importance for all teeth, both sound and restored. For the restorative dentist to utilize crown lengthening, it is important to understand the concept of biologic width, indications, techniques and other principles. This article reviews these basic concepts of clinical crown lengthening and presents four clinical cases utilizing crown lengthening as an integral part of treatments, to restore teeth and their surrounding tissues to health.

Pesticide soil sorption parameters: theory, measurement, uses, limitations and reliability.

The soil sorption coefficient Kd and the soil organic carbon sorption coefficient KOC of pesticides are basic parameters used by environmental scientists and regulatory agencies worldwide in describing the environmental fate and behavior of pesticides. They are a measure of the strength of sorption of pesticides to soils and other geosorbent surfaces at the water/solid interface, and are thus directly related to both environmental mobility and persistence. KOC is regarded as a 'universal' parameter related to the hydrophobicity of the pesticide molecule, which applies to a given pesticide in all soils. This assumption is known to be inexact, but it is used in this way in modeling and estimating risk for pesticide leaching and runoff. In this report we examine the theory, uses, measurement or estimation, limitations and reliability of these parameters and provide some 'rules of thumb' for the use of these parameters in describing the behavior and fate of pesticides in the environment, especially in analysis by modeling.