Journal of Dental Medicine

Background and Aim: By definition, pontic is an artificial replacement of missing tooth (teeth) which is essentially used to establish function and esthetics. In order to this fact that, pontic(s) is not completely the same as tooth (teeth) to be replaced, it may not be concern as a simple type of restoration to achieve the best result, it must be design from the esthetically and hygienically point of view as well as comfort, demand and tissue health of patient. The main purpose of this study is to investigate the pontic designs and their relationship to edentulous partial aras.

Materials and Methods: 73 pontics in 57 patients have been included in this cross-sectional study. These patients were under treatment in the department of prosthodontics. A primary cast was achieved from each patient and then the cross-sectional contour of edentulous ridge was depicted. For each patient the type of pontic design was derived from textbook standards and then compared with the design of actual verified Prosthesis at delivery. The shape of tissue surface of each denture was determined by a low viscous impression material. The result of each comparison was recorded in a chart data set.

Results: The most common pontic design was Modified ridge lap with frequency of 93.2%. The type of ridge was %45.2 normal, %19.2 class I, %8.2 class II and %27.4 class III, respectively. %72.6 of pontics tested have inappropriate design in tissue surface.

Conclusion: It seems that in a high percentage of cases the tissue surface contour of prescribed pontics in department of prosthodontics was incorrect and more attention must be paid to the education of students and technicians.

Background and Aim: Evaluation of shear bond strength and microleakage of bonding agents is important as these properties play main roles in adhesion of composite to dental tissues. Microleakage results in bacterial penetration into dentin tubules and enamel surfaces and causes sensitivity and recurrent caries followed by destruction of composite filling. Insufficient shear bond strength results in early failure of filling in low masticatory forces. The main goal of this study was to compare the microleakage and shear bond strength of an experimental adhesive and Scotchbond multi-purpose (MP) adhesive system.
Materials and Methods: In this experimental study, sixty extracted caries free human molar teeth were randomly assigned into 4 groups of 15 each for shear bond strength. Variables were bonding agents, enamel and dentin. Twenty teeth assigned into 2 groups of 10 each were used for valuation of the microleakage. Microleakage and shear bond strength were performed according to ISO TR 11405. All data were analyzed with parametric and non-parametric tests according to their normality distribution. Also, Weibull distribution performed on data.
Results: Data obtained from both microleakage and shear bond strength tests showed no significant difference between the experimental bonding and Scotchbond MP bonding (P>0.05). Furthermore, there was no significant difference between the microleakage of occlusal and gingival parts of both bondings (P>0.05).
Conclusion: Experimental adhesive bonding showed acceptable results regarding microleakage and shear bond strength. It may be concluded that the experimental dentin bonding had a comparable performance quality with that of commercial system.

Background and Aims: Because of high prevalence of TMJ dysfunctions , increased promotion of diagnostic and treatment methods is necessary. In many cases, in addition to disc position, morphology of other joint components such as articular eminence can be changed and therefore the probable correlation between disc position and morphology of hard tissue components can be used for prediction of internal derangements. The aim of this study was to evaluate the correlation between the position of disc and morphology of articular eminence of TMD`s patients using magnetic resonance imaging (MRI).

 Materials and Methods: In this cross sectional study by evaluation of digital MRI files, ultimately 78 joint images were identified which had sufficient quality and resolution for review. Then the MRI images, were observed and evaluated by 3 oral and maxillofacial radiologists to determine the disc position (normal, anterior displacement with and without reduction, and posterior displacement) and morphology of articular eminence (Box, Sigmoid, Flattened). Ultimately the results that were reported at least by 2 observers were included as the final results and were recorded in the check list. Data were analyzed using Chi-Square test and Fisher test.

 Results: In this study, no case of posterior disc displacement was found and therefore was excluded from the study. Articular eminence morphology (Flattened versus Sigmoid) showed statistically significant correlation with anterior disc displacement with and without reduction (P-values for anterior displacement with and without reduction were 0.03 and 0.002, respectively). No significant difference was found between the sigmoid and box types in relationship with disc displacement (P-values for anterior displacement with and without reduction were 0.72 and 0.70. In this study, no significant difference between the anterior disc displacement with reduction and anterior disc displacement without reduction in relationship with the morphological changes of articular eminence in any of the cases were found.

 Conclusion: The results showed that flattening of articular eminence had significant relationship with anterior disc displacement.