Standards of teeth preparations for anterior resin bonded all-ceramic crowns in private dental practice in Jordan

OBJECTIVES: To 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 METHODS: A 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. RESULTS: Subgingival margins on the buccal aspect were noticed in 36 percent of the preparations, 54 percent 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 percent. Twenty-nine percent and 12 percent of samples had either a feathered or no clear margin design respectively. Incisal underpreparation was observed in 18 percent of dies of each type. Only 17 percent of all preparations were found to follow the recommended anatomical labial preparations while 29 percent of the RBC preparations were found to have the recommended axial convergence angle. In total, 43 percent of preparations were found to have the recommended depth of the finish line. CONCLUSIONS: It was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan.

Comparison of convergence angle of prepared teeth for full veneer metal ceramic crowns

To compare clinically practiced convergence angle values of tooth preparation with recommended values, and also the effect of tooth position and operator experience on convergence angle. Analytical study. The study was carried out at the Dental clinic, The Aga Khan University Hospital, Karachi, from January to June 2007. A minimum of 75 crown preparation dies including 25 dies in each group of teeth [anterior, premolars and molars] were collected retrospectively which were prepared by residents and specialists of operative dentistry. AutoCAD 2007 software was used for measurement of convergence angle. One sample t-test was applied to compare the mean practiced convergence angle values with its recommended values. Two way ANOVA was applied to measure difference in convergence angle values with respect to operator experience and tooth type with the level of significance being a=0.050. Mean reported convergence angle value was 22.72°, which was significantly greater [p < 0.001] than the recommended values. Statistically significant difference in convergence angle was found between anterior vs. molar teeth and between premolars vs. molar teeth [p=0.0001 and p=0.002, respectively]. There was a considerable disparity between the convergent angles values recorded in this study and the recommended guidelines. Measured convergence angle values were greater for posterior teeth as compared to the anterior teeth

Indice de qualidade do trabalho protético (IQP): um estudo metodológico / Prosthodontic Quality Index (PQI): a methodological study

Embora alguns estudos de avaliaçäo clínica da eficácia dos resultados da instalaçäo de PPRs tenham sido elaborados, nenhum deles utilizou medidas estandardizadas abrangentes que envolvessem tanto os aspectos biomecânicos das PPRs quanto as conseqüências clínicas do tratamento protético. O índice de qualidade do trabalho protético (IQP) foi desenvolvido com a finalidade de compensar os problemas acima descritos, podendo ser utilizado no âmbito de três parâmetros: biomecânica, preparo de boca e avaliaçäo clínica, para futuros estudos de avaliaçäo global dos pacientes portadores de próteses parciais removíveis. Este estudo tem a finalidade de apresentar a nova metodologia do IQP para que o leitor possa aplicá-la, por meio de sistemas de escores, na análise da qualidade de seu trabalho protético