Abstract
ObjectivesTo investigate if general dental practitioners (GDPs) in private practice in Jordan follow universal guidelines for preparation of anterior teeth for resin bonded all-ceramic crowns (RBCs). Material and MethodsA sample (n=100) of laboratory models containing 208 tooth preparations for IPS Empress and In Ceram, featuring work from different GDPs, was obtained from 8 commercial dental laboratories. Aspects of preparations were quantified and compared with accepted criteria defined following a review of the literature and recommendations of the manufactures' guidelines. ResultsSubgingival margins on the buccal aspect were noticed in 36% of the preparations, 54% demonstrated overpreparation with a tendency to overprepare the teeth on the mesiodistal plane more than buccolingual plane. Twenty percent of samples presented a shoulder finish line while a chamfer margin design was noticed in 39%. Twenty-nine percent and 12% of samples had either a feathered or no clear margin design respectively. Incisal under preparation was observed in 18% of dies of each type. Only 17% of all preparations were found to follow the recommended anatomical labial preparations while 29% of the RBC preparations were found to have the recommended axial convergence angle. In total, 43% of preparations were found to have the recommended depth of the finish line. ConclusionsIt was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan.
Highlights
As all-ceramic crowns have become one of the best aesthetic restorative materials, the need for good practice and skills to perform such restorations within patient expectations and the recommended guidelines for tooth preparations becomes mandatory[33].All-ceramic resin bonded crowns appear to have a number of advantages compared with conventional metal-ceramic crowns
Their better aesthetic properties may be due to the fact that the composite resin luting material is more translucent than conventional cements used with porcelain fused to metal crowns, which improves the transmission of light through the restored unit, and because of a good peripheral blend at the gingival margin without a black-line margin due to the metal substructure[5]
Of the total 100 casts examined in this study, 62 casts containing 141 dies (67%) were preparations for IPS Empress, while 38 casts containing 67 dies were preparation for In-Ceram (33% of the total dies examined)
Summary
All-ceramic resin bonded crowns appear to have a number of advantages compared with conventional metal-ceramic crowns. Their better aesthetic properties may be due to the fact that the composite resin luting material is more translucent than conventional cements used with porcelain fused to metal crowns, which improves the transmission of light through the restored unit, and because of a good peripheral blend at the gingival margin without a black-line margin due to the metal substructure[5]. Given the insoluble nature of the resin luting material, the periodontal response associated with dentinbonded all-ceramic crowns may be superior to that associated with conventional crowns in which the luting agent at the margins may dissolve, resulting in possible plaque accumulation as well as a risk of caries lesion formation. Laboratory studies have shown that the fracture resistance of dentinbonded all-ceramic crowns was good, even though
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