Assessment of tooth preparation designs for posterior resin-bonded porcelain restorations.
Tooth preparation designs advocated for posterior resin-bonded porcelain restorations were evaluated for clinical application. This study examined the design of tooth preparations from stone dies for individual posterior resin-bonded porcelain onlays and complete porcelain crowns placed in a specialist practice, and compared features that provided retentive and porcelain fracture-resistance with those in the dental literature. Stone dies of tooth preparations for 57 onlay and 46 crown preparations were provided. Measurements were recorded for the tooth preparations with the aid of interocclusal silicone impressions. Proximal boxes, grooves and occlusal steps resulting from removal of amalgam restorations were common. These retentive features were more evident with onlays, and appeared larger on the distal than the mesial surfaces. Internal tooth preparation tapers or convergence angles were frequently greater than 20 degrees, leading to relatively-wide occlusal isthmus widths, especially for onlays. There were wide variations in occlusal surface reductions for the central fossae and supporting cusps. Tapers for tooth preparations were frequently more extensive, and occlusal surface reductions were often less than recommended. The implications of these differences for long-term clinical success should be resolved.
Etemadi
S
S
Department of Dentistry, The University of Adelaide, South Australia.
Smales
R J
RJ
Drummond
P W
PW
Goodhart
J R
JR
D000328:Adult; D001641:Bicuspid; D003442:Crowns; D003723:Dental Amalgam; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000379:methods*; D003760:Dental Impression Materials; D003761:Dental Impression Technique / Q000295:instrumentation; D003776:Dental Porcelain; D017268:Dental Prosthesis Retention; D006801:Humans; D007284:Inlays; D003765:Models, Dental; D008963:Molar; D015203:Reproducibility of Results; D012828:Silicones; D013314:Stress, Mechanical; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*; D016896:Treatment Outcome
D003760:Dental Impression Materials; D012828:Silicones; D003776:Dental Porcelain; D003723:Dental Amalgam