Biomedical subjects
Publications and source records attributed to T Kerschbaum.
1310 three-unit resin-bonded bridges were examined for their failure rates. After five years 86% (+/- 4%) were still in situ. 64% (+/- 5%) didn't need rebonding. Significant prognostic factors were: preparation of abutments, surface treatment (net retention, silicoating), type of luting agent (Bis GMA) and mobility of the abutments.
Statistical methods of survival-analysis were applied to investigate the effects of anatomical, constructional and individual factors, which determine the "life-time" of 4371 single crowns, 1669 bridges and 175 fixed splints of a total of 1841 patients of a private insurance company. After 15 years of service 64% of the bridges, 56% of the single crowns and 45% of the splints were still under risk. The number of abutments and units, location, date of insertion, jaw and extension/normal bridge were significant risk factors.
Failure-time analysis of Dicor single crown restorations: Statistical methods of survival-analysis according to Kaplan-Meier were applied to investigate the effects of the fracture of 159 Dicor-restorations in 82 patients in a private dental office. After 33 months of service 77% (+/- 15%; 95% Conf. Int. for the mean) of the crowns were still under risk. Fractures were very high in molar crowns.
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In a study of 703 resin-bonded fixed partial dentures, the success rates of two groups were analyzed where rebonding or renewals were necessary. Results revealed that rebonding often leads to repeated failures whereas renewals showed a failure rate similar to the whole of the investigated material.
An evaluation of about 300 abutment teeth of resin-bonded bridges (Rochette, electrochemically etched) and resin-bonded extracoronal attachments was performed to determine the surface area and the length of the circumference of the retainers. By using a combined indirect (preparation of the specimen) and direct (automatic image analysis) method for the determination of both parameters a mean value of 50 mm2 for the surface area and 30 mm for the circumference, respectively, was evaluated. In addition, two indices (loading-index (BI): sigma surface area/width of pontic tooth; moisture penetration-index (FPI): sigma surface area/sigma circumferences) as predictors for the longevity of resin-bonded reconstructions were calculated. The loading-index was a good predictor for successful reconstructions: the clinical success was the better, the bigger the retention area, and the smaller the circumference of the retainer and the smaller the pontic tooth.
Statistical methods of survival-analysis were applied to investigate the "life-time" of three types of class II amalgam restorations: 1355 F3-, 355 F4-amalgam filling, 108 TMS-pin-retained extensive amalgam restorations and 222 single crowns of a total of 630 patients of a private dental office. After 8 years of service about 50% of the extensive amalgam fillings, but 12% of the single crowns were still under risk.
788 patients with 3-unit resin-bonded bridges were followed up over a time period of up to 5 years after placement. In this multicenter study, the following clinical variables were analyzed: caries, periodontal disease, loss of pulp vitality and the behavior of the dental materials involved were assessed. Adverse findings were rare. More data are needed over a longer period of time to support the present results.
The development of modern information technology has brought about dramatic changes in the field of auxiliary instruments for scientific research, and by the same token, for research in dentistry. In the context of data acquisition literature data bases play an important part; in the evaluation of data emphasis is being placed on data bases, improved online measuring techniques and statistical systems. Text and graphics programs may facilitate and improve the mediation of scientific results. The value of expert systems for establishing diagnoses seems highly questionable.
Statistical methods of survival-analysis were applied to investigate the effects of anatomical factors and clinical procedures which determine the "life-time" of 3-unit adhesive bridges. Their influences were analyzed until the first loss of retention after insertion. Besides the therapist effect, increased mobility and macromechanical preparation of the abutments could be identified as significant variables. Bridges bonded to one non-mobile and one hypermobile abutment tooth were found to be especially threatened. Extensive macromechanical preparation of the hard tissues reduces the hazard of debonding remarkably; this effect may be replaced by improved retentive mechanism of retainers.
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This second report establishes that the success of treatment with resin-bonded bridges was dependent upon many factors. Factors controlled by the clinician, such as case selection and treatment planning greatly influence the clinical success. It was possible to show that framework preparation and the amount of available enamel were significant factors, whereas isolation technique, type of retention mechanism and type of adhesive used were of less importance. Longitudinal studies are needed to confirm these observations. Seventeen clinicians placed 496 resin-bonded bridges and splints with different retention mechanisms and bonding agents. These reconstructions were examined in regard to the failure rate and in regard to reattachment problems. Ninety-seven per cent of the bridges and 90% of the splints were still in place after 1 year. For bridges and splints a 90% success rate was ascertained after 2 years.
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In a joint evaluation of 496 resin-bonded bridges and splints anchored by various retention principles and composites, the initial experiences of seventeen clinicians were compiled. The main indications for treatment were congenital anodontia and loss of teeth due to caries and trauma. After 3 months, 95% of the bridges were still in place without need of reattachment procedure. After 6 months the figure was 91%, after 1 year 81.5% and after 1 1/2 years 73%. Seventy-five per cent of the loosened bridges were attached successfully a second time. The success rate for splints was significantly lower.
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