Document Type : Original Article
Authors
1 Assistant Professor of Prosthodontics Department, School of Dentistry, Shiraz University of Medical Sciences
2 Postgraduate Student of Prosthodontics Department, School of Dentistry, Shiraz University of Medical Sciences
Abstract
Background: The most important factor in fabrication of a perfect crown is having a perfect margin, which matches completely with finish line preparation and has a good situation in relation to the alveolar bone crest. To control the quality of the fixed prostheses made in a dental clinic in Shiraz, there was an attempt to assess the quality of their margins.Materials and Method: Radiography was used to check this quality. Parallel periapical radiography was made from the 102 crowns and bridges after cementation and before discharging the patients. To measure the magnification, a metal ball with 4mm diameter was attached on the crowns at the line of their proximal margins before taking images. To obtain more exact and detailed information, a projector was used to increase the magnification of the images. The distance between the crown's margin and finish line in horizontal and vertical aspects and also the distance to the alveolar bone crest were measured.Results: The statistical analysis of the data revealed that in 76.5 percent of the cases the crowns had more gap in the vertical aspect than the acceptable range (50 micro meters). In 60.8 percent of the cases there was a gap in the horizontal aspect. In 11 percent of the cases, a ledge was seen in the horizontal aspect and by combining the gaps in both horizontal and vertical aspects, it was seen that, as a whole, 92.2 percent of the crowns had more gaps than the acceptable range. Also it was seen that in 77 percent of the cases in the mesial and 64.5 percent in the distal part, the crown's margin had invaded to the biologic width.Conclusion: It is concluded that it would be worthwhile to make radiographic image to check the framework, thereby important errors, which are difficult or impossible to discover by clinical examination will be shown.Key words: Radiographic evaluation, Vertical gap, Horizontal gap, Biologic width
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