Factors affecting late fixture loss and marginal bone loss around teeth and dental implants.

BACKGROUND: The predictability and high success rate of implant treatment have averted attention from factors affecting fixture loss and bone loss around implants. PURPOSE: The goal of this study was to retrospectively evaluate late fixture loss and marginal bone loss around implants that have been in function for 5 years and to relate these findings to bone loss in the natural dentition. MATERIALS AND METHODS: One hundred and forty-three consecutively treated patients who had received an implant-anchored fixed prosthesis and completed a 5-year follow-up were selected. Intraoral and panoramic radiographs were used to assess bone loss. RESULTS: The bone loss was greater around remaining implants in patients who had lost implants after loading. No correlation was found between bone loss around implants and that around teeth. Only 2% of the fixtures were lost during 5 years of functional load. Most fixtures losses occurred in the edentulous maxilla. Seven of the nine patients who lost fixtures were smokers. CONCLUSION: These findings show that patients who lost implants also lost more bone around the remaining implants. There was no correlation between bone loss around implants and that around teeth, indicating that different interacting mechanisms are involved.

Loose gold screws frequently occur in full-arch fixed prostheses supported by osseointegrated implants after 5 years.

The possible occurrence of loose gold and abutment screws retaining full-arch osseointegrated prostheses has been investigated. The prostheses had been in use for at least 5 years. The findings were related to clinical parameters such as accuracy of the superstructure, operator dependence, and clinical and radiological diagnosis of implant status after 5 years. The principles of the California Dental Association's (CDA) quality evaluation criteria were modified and applied in the study. Gold screw loosening was found to be related to framework misfit and was considered to be operator dependent to some extent. It is recommended that full-arch fixed prostheses be retightened after 5 years.

Incidence of adverse effects of dental materials.

Acute and long-standing adverse effects from dental materials used in the treatment of 13,325 patients in 15,820 appointments were recorded by 137 dentists. Twenty-four suspected side effects were reported by the patients and 22 by the clinicians; 7 were classified as "probable" or "possible" acute reactions and 15 as long-standing effects, 13 being "verified" and 2 "probable". In another survey, 31 dentists representing a total of 387 years of practice recollected 113 patients with side effects from dental materials.

Clinical evaluation of angulated abutments for the Brånemark system: a pilot study.

Where fixture placement and inclination had not been optimal from a restorative perspective, angulated abutments were used to overcome compromised esthetic and functional results in situations of complicated anatomy. The angulated abutment is a treatment adjunct that provides flexibility for ensuring successful treatment when a variety of reconstruction problems are confronted.

Ranking of histologic tissue responses in the biologic evaluation of dental materials.

Implantation tests are frequently used to evaluate biological properties of dental materials. The tissue reactions have been rated as no, slight, moderate and severe responses, mainly based on a quantitative assessment of the cellular response. The distinction between categories is subject to discussion, and interexaminer calibration is necessary to obtain reproducible results. This paper presents a statistical method of evaluating tissue reaction by ranking photographic prints representing histologic sections. Polyethylene tubes, carrying the materials, were implanted subcutaneously in guinea pigs. The tissue reactions at the tube ends, where the material was exposed to the tissue, were evaluated. Photographs of 20 histologic sections were selected. Five investigators from a scientific staff and five from a group of assisting personnel with minimal instruction ranked the reactions on the prints in increasing order of severity. Assisting personnel received 1 h of instruction before the ranking. Generally, the rank ordering of the different examiners showed good agreement. Qualitative histopathologic examination of the sections indicated a marked variation in the cellular response, which limits the value of the quantitative assessment.

Evaluation of tissue response to dental alloys by subcutaneous implantation.

The tissue response of two low-gold alloys (Midas and Rajah), two silver-palladium alloys (Albacast and Alba V), and one type III gold alloy (JSC) was studied after subcutaneous implantation of cylindrical implants in 24 guinea pigs. Casting of each alloy were inserted into polyethylene tubes and implanted by means of a standardized technique. Each animal received five implants representing the five alloys. The implants were left in place for 30 and 90 days. Microscopic evaluation of the implant sites showed that after 30 days the tissue reactions were slight to moderate, with only small differences between the alloys. After 90 days the reactions were slight to extreme. One of the silver-palladium alloys (Alba V) demonstrated several severe and extreme reactions after 90 days. The other silver-palladium alloy (Albacast) demonstrated the least tissue response of the five alloys in the 90-day group.

Tissue reactions to implanted orthodontic wires in rabbits.

Tissue response to a Fe-Cr-Ni and a Co-Cr-Ni orthodontic wire, in the as-received state and with silver soldered joints, was investigated. Specimens with polytetrafluoroethylene (PTFE) as a reference material were implanted in the subcutaneous tissue of rabbits. Six rabbits were sensitized to nickel, four animals were sham-sensitized, and two were left untreated. The results showed that the as-received wires gave no tissue response relative to the PTFE control. In soldered specimens that were moderate to extreme reactions adjacent to the soldered joint and around the wire portion as well. The soldered Co-Cr-Ni wire elicited the most severe reactions, most pronounced in the nickel-sensitized animals. The agar overlay cell culture test of some retrieved implants showed pronounced cytotoxicity of the soldered specimens. Leachable toxic components of the silver solder seemed to be of major importance in the observed cell culture and tissue response to the soldered specimens.

Instrumentation for preparation and placement of subcutaneous implants.

An instrument has been designed for the preparation and placement of subcutaneous implants in small laboratory animals. The usefulness and applications of the instrument have been assessed, based on experiences from 260 implants inserted subcutaneously on guinea pigs with the aid of the described instrument.

Tissue response to allergenic leachables from dental materials.

In addition to toxic reactions to dental materials, some individuals may develop or exhibit hypersensitivity reactions to leachable components. An experimental model combining the guinea pig maximization test for induction of hypersensitivity and the subcutaneous implantation of dental cements is described. Guinea pigs immunized with AH 26, an epoxy-bisphenol resin, showed an increased tissue response to AH26 implants. Guinea pigs immunized with zinc oxide-eugenol did not show a similarly increased response, possibly because of an anti-inflammatory effect of eugenol. The experimental model may prove useful in predicting the effect of leachable allergens from dental materials in sensitized individuals.