University of Khartoum

Assessment of Undergraduate Students’ Tooth Preparation for Full Veneer Cast Restoration

Assessment of Undergraduate Students’ Tooth Preparation for Full Veneer Cast Restoration

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Title: Assessment of Undergraduate Students’ Tooth Preparation for Full Veneer Cast Restoration
Author: Abdel-Rahaman, Nuha
Abstract: Background: Despite strict guidelines, error in tooth preparation was reported as one of the main causes of failure. Many studies had been performed to evaluate tooth preparation in order to be acquainted with the defects and solve them. Design: A descriptive cross sectional clinical study. Setting: Department of Conservative Dentistry in two different Dental Schools • University of Khartoum /U of K.(governmental) • University of Science and Technology /UST. (Private) Objectives Evaluate the different aspects of tooth preparation for full veneer casting restorations performed by final year dental students. Methods One hundred and seventeen stone dies were evaluated, of which 100 were prepared as abutments for bridges whereas only 17 of them were prepared to receive crowns. Two impression replicas were produced by polyvinyl siloxane (additional silicon); one was sectioned in faciolingual plane and the other in mesiodistal plane. By using a digital caliber occlusal clearance was measured in functional cusp (FC), non functional cusp (NFC) and central fossa (cf) areas. The amount of axial preparation in facial, lingual, mesial, and distal walls were also measured by a digital caliber. Impression silhouettes that were produced by using over head projector were used to measure convergence angle. Working casts were examined for smoothness and evenness of the preparations, existence or absence of additional features of retention and the finishing line was examined for its position and continuity. Results The average taper (convergence angle) of the examined preparations was 39.98°, with 44.1° faciolingual, and 35.8° mesiodistal. This is regarded significantly out of ideal range that must be achieved clinically. Occlusal clearance for PFM for both anterior and posterior teeth was acceptable, whereas preparations for full metal restorations were overcut. The amount of axial preparation for PFM was acceptable, and the result was significant; however the amount of facial wall preparation was also acceptable but the result was not statistically significant. In preparations for full metal restoration, the axial walls were over prepared with the exception of the lingual wall which was ideally prepared for metal. Sub and supra gingival finishing lines were present in equal percentage, however (38.5%) of the preparations have mixed finishing lines i.e. areas with subgingival lines and others with supra gingival lines in the same preparation. Most of the students (77.8%) were able to maintain continuity of the finishing line all around the preparation, although a significant number of them (19.7%) was unable to maintain continuity. All preparations were generally smooth with no sharp angles, and small number of preparations (1.7%) had additional retentive features. Conclusions Although students have fresh knowledge about tooth preparation for fixed prosthesis, lack of sufficient preclinical training and their minimal experience affected the quality of tooth preparation especially the convergence angle and finishing line aspects. In spite of large convergence angles, lack of additional retentive features was apparent
Description: 67 Pages
URI: http://hdl.handle.net/123456789/7846
Date: 2015-03-31


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