A. Leibrock

Adhesive-fixed partial dentures in anterior and posterior areas

Abstract Within the framework of an on-going prospective clinical study begun in 1985, 120 adhesive-fixed partial dentures (AFPD) continued to be examined. The manufacture and the fitting of the AFPDs were carried out following a standard procedure. The preparation technique and the metal framework conditioning (silica-coating, sandblasting and electrochemical etching) has varied throughout the duration of the study. Using Kaplan-Meier analysis, the survival rate was determined and an analysis of risk with regard to location factors (anterior, posterior; maxilla, mandible), conditioning and preparation techniques (retentive/non-retentive) was determined using the Cox regression model. The location of the AFPD had no influence on the survival rate. The survival time was determined mainly by the preparation technique. Strict preparation of seating grooves and pin holes made a 95% survival rate possible after 10 years (Kaplan-Meier estimation). Without retention, the risk of failure increased by a factor of 3.7.

Intraoral repair of fiber-reinforced composite fixed partial dentures

STATEMENT OF THE PROBLEM Fractured composite facings may result in replacement of a fixed partial denture unless a reliable intraoral repair method can be provided. PURPOSE This in vitro study tested the quality of an intraoral repair method for fractured facings of fixed partial dentures made of a fiber-reinforced composite system. MATERIAL AND METHODS Shear bond strengths of a light-curing composite to a fiber-reinforced composite material were determined after different mechanical surface treatments. Aluminum oxide air abrading provided the most reliable bond strength values and therefore was used as a pretreatment for the facing repair of three-unit posterior fixed partial dentures. Facing repair was performed with the tested light-curing hybrid composite. Facing fracture strengths of repaired and original fixed partial dentures were determined after thermocycling and mechanical loading. RESULTS Median facing fracture strength of the original fixed partial dentures was 1450 N after a simulated clinical service of 5 years. Facing fracture strengths of the repaired fixed partial dentures were significantly lower compared with the control group after an additional simulated 2-year interval. However, the median fracture force was still 1000 N. CONCLUSIONS The facing repair of a fiber-reinforced fixed partial denture with a hybrid composite in combination with aluminum oxide air-abrading pretreatment and silanization provided sufficient fracture strength. Therefore the replacement of the complete restoration may be avoided.

Veneering composites – a thermoanalytical examination

Differential thermal analysis and thermal gravimetric analysis were used to characterize veneering composites. Samples weighing 4–20 mg, made from the composite materials Visio-Gem (Espe, Germany), Sinfony (Espe, Germany), Artglass (Kulzer, Germany), Dentacolor (Kulzer, Germany) and Targis (Ivoclar, Liechtenstein), were examined. The samples were subjected to various thermal curing times of between 4 s and 25 min, using the relevant devices of the manufacturers. As a control group, samples of all materials were examined unreacted. In order to avoid post-curing during storage, all samples were subjected, immediately after manufacture, to the appropriate dynamic temperature programme of the thermoanalytical unit at a heating rate of 10 °C min-1. The materials showed specific material characteristics which can, for instance, be used to analyse the curing behaviour of the materials. The position of the glass transition, polymerization and post-polymerization peaks at temperatures between 30 and 100 °C, as well as 150 and 300 °C, and the filler and matrix content, allow the classification of the veneering composites.