EFFECTS OF ADHESIVE FIXED PROSTHESIS RETAINER DESIGN ON RESULTANT RESIN LUTING AGENT THICKNESS

Statement of problem. Resin cement thickness may influence the success or otherwise of adhesive fixed prostheses and needs to be quantified for future stress analyses. Purpose. This study evaluated the effect o f different complexities of retainer preparation design on resultant r esin lute thickness. Material and methods. Five retainer designs were evaluated for resin luting thickness (Panavia Ex) after cementation to appropriately selected natural teeth as follows: (1) flat plate retai ner; mandibular canine; (2) occlusal rests, mandibular premolar; (3) o cclusal rests, proximal grooves, mandibular premolar; (4) modified thr ee-quarter crown, mandibular premolar; and (5) occlusal strut, maxilla ry premolar. Five samples of each design were prepared in vitro. A mes iodistal and a buccolingual section were obtained from each sample wit h a diamond saw. Measurements were carried out on the fluorescent ceme nt lute with a confocal microscope. Mean resin thickness and cervical resin thickness were analyzed with analysis of variance and Tukey test s. Results. Resin thickness (mu m) for each of the retainer designs we re as follows (mean +/- SD): design 1, 58 +/- 40; design 2, 67 +/- 42; design 3, 80 +/- 28; design 4, 87 +/- 15; and design 5, 85 +/- 29. Th ere were no significant differences among the designs (mean global val ue 75.4). The three-quarter crown (design 4) had a significantly wider cervical resin thickness (P less than or equal to .01) than designs 1 , 2, and 3.