R. Mosharraf , D. Abtahi , M. Porrabani ,
Volume 16, Issue 4 (9 2004)
Abstract
Statement of Problem:The determination of the dental midline is necessary in most dental procedures.One of the methods to fulfill this goal is to determine the facial midline based on the midpoints of the forehead, nose, upper lip and chin. However, for various reasons, this method has not always been proved successful. In such cases, different techniques, based on the investigations in the edentulous
patients, have been suggested.
Purpose: The aim of this study was to investigate the conformity of some landmarks such as labial frenum, incisive papilla and mid palatal suture with dental and facial midlines among people with natural dentition in order to obtain accurate anatomic landmarks for denture replacement.
Materials and Methods: In this descriptive study, 96 dental students, having all their permanent teeth and without any orthognathic problem, were chosen. For each subject, Alginate impressions and dental casts were prepared. Then, centric occlusion was recorded with a biting wax and the facial mid line was determined on the anterior part of it. The distances from the facial midline to the upper teeth midline,
incisive papilla, labial frenum and mid palatal suture were determined with a special tool and were measured by a VERNIEH two times. In order to analyze the results, Chi- Square and t-student tests were used.
Results: The average of facial midline distance to the upper teeth midline, the labial frenum, the incisive papilla and the mid palatal suture were 0.83±0.60, 0.67±G.54, 0.83±00.63 and 0.81±0.62 mm,respectively. There was no significant difference between males and females. Labial frenum showed the minimum distance to the facial midline, while the incisive papilla had the maximum. There was no significant difference between these anatomic landmarks, in conformity or unconformity with the facial midline
Conclusion: Considering the low percentage of the subjects with complete conformity and the lack of significant differences between these three landmarks, it is suggested that there is no superiority among these landmarks for the determination of facial midline. The similar distances from the facial midline to the incisive papilla and upper teeth midline indicate that using incisive papilla to determine the upper
teeth midline in edentulous patients lead to normal face.
Ramin Mosharraf, Aref Sadeghian,
Volume 31, Issue 3 (11-2018)
Abstract
Background and Aims: In endodontically treated teeth, the fiber posts are used to retain a core restoration. The purpose of this study was to evaluate the effect of different resin cements on the bond strength of fiber reinforced composite posts to root canal dentin, and comparing the bond strength in different sections of root.
Materials and Methods: In this in-vitro experimental study, 48 extracted single-canal central incisors were endodontically treated. For the push out test, the posts were divided into 3 groups according to one of the following three different cement materials (n=16) (Bifix SE, Bifix QM, Rebilda). Three slices with a thickness of 2-mm were prepared of each root. The push-out tests were performed at a cross-head speed of 1 mm/minute using a universal testing machine. Data were analyzed by two-way and one-way ANOVA test followed by Tukey post hoc test (α=0.05).
Results: There was no significant differences between the mean push out bond strength of three experimental groups (P=0.650), but there were significant differences between the mean push out bond strength of root dentin regions (P<0.001).
Conclusion: Under the conditions of this study, there was no significant difference between the mean push out bond strength of 3 different resin cement systems. The coronal region of root dentin showed significantly higher mean bond strength values than that of the middle and apical thirds.
