Repair of fractured acrylic resin

Abstract

repair of fractured dentures has received little attention in the literature. Most approaches to repairs appear to be by rote rather than based on detailed scientific study. When a fractured denture is repaired with either heat-cured or chemically (cold) cured acrylic resin, the criteria for a satisfactory repair are that: (1) the repair must be rapid, (2) the repaired structure must have adequate strength, and (3) the denture must retain dimensional accuracy during and after Ware and Docking 1 reported one approach to repairs using heat-cured acrylic resin that yielded transverse strengths of up to 75% of that of the original In this study, ail sharp angles at the fracture site were eliminated using a cotton buff and pumice and a double V joint with a separation of 3.1 to 6.3 mm was prepared. During cu ring, the process flask was subjected to positive pressure. Other workers have studied the strength of den­ ture repairs, the effect of edge preparation, and the use of different repair materials. Repairs with cold­ cure resin, using a 2 mm gap between the broken edges, yielded specimens that were only 57% as strong as the original heat-cured material. Further­ more, fracture occurred at the junction of the old and new material rather than through the center of the repair material where the load was applied. A limited study examined the stress concentration around the opposing repaired edges, and the least internai stress was found with round edge profiles. 3 A similar result was obtained by Harrison and Stans­ bury4 who investigated the strengths of repairs using butt, round, and rabbet edge profiles. They found the strongest union with the rounded profile. A study of the transverse strength of repaired acrylic resins indicated that greater strengths were obtained wh en the original denture base material was used for the repair. Preparation of the edges in the form of a double V and a gap of no more than 1.5 mm was recommended. Finally, a recent study