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Variations in tooth preparations for resin-bonded all-ceramic crowns in general dental practice
1Liverpool University Dental Hospital. Finlaysutton@another.com
Objective:
To investigate variations in tooth preparations for resin-bonded all-ceramic crowns (RBCs) in general dental practice (GDP).
Design:
Laboratory-based retrospective analysis of dies for RBCs.
Setting:
General dental practices in the UK and Ireland (2000).
Methods:
A sample (n = 132) of laboratory models containing 180 tooth preparations for RBCs, featuring work from different general dental practitioners was obtained from four commercial dental laboratories. Aspects of the preparations were quantified and compared with accepted criteria defined following a review of the literature.
Results:
The teeth found to be most frequently prepared for RBCs were maxillary incisors (41%). Margin positions were variably positioned with 29% of the preparations on the buccal aspect having subgingival margins. There were many tooth preparation dies for low fusing RBCs (47%) and Chameleon Fortress RBCs (62%) demonstrating overpreparation in the mesiodistal plane. The majority of the margins (84% buccally and 79% lingually) of the dies examined exhibited appropriate shoulder or chamfer finishes. Of the Chameleon Fortress preparations analysed, 86% had been underprepared occlusally. 42% of the teeth had been prepared with no regard to tooth morphology and demonstrated just one plane of reduction. The majority (93%) of the clinicians failed to provide any information regarding the shade of the prepared tooth stump.
Conclusions:
On the evidence of this survey of this sample of general dental practitioners' work, it was found that relevant guidelines for the preparations of RBCs are not being fully adhered to.