ObjectiveThis study investigated the effect of different ferrule heights on endodontically treated premolars.Materials and MethodsFifty sound mandibular first premolars were endodontically treated and then restored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent) luted with self-polymerized resin cement (Multilink, Ivoclar Vivadent) while the coronal section was restored with hybrid composite core build-up material (Tetric Ceram, Ivoclar-Vivadent), which received all-ceramic crown. Different ferrule heights were investigated: 1-mm circumferential ferrule without post and core (group 1 used as control), a circumferential 1-mm ferrule (group 2), non-uniform ferrule 2-mm buccally and 1-mm lingually (group 3), non-uniform ferrule 3-mm buccally and 2-mm lingually (group 4), and finally no ferrule preparation (group 5). The fracture load and failure pattern of the tested groups were investigated by applying axial load to the ceramic crowns (n=10). Data were analyzed statistically by one-way ANOVA and Tukey’s post-hoc test was used for pair-wise comparisons (α=0.05).ResultsThere were no significant differences among the failure load of all tested groups (P<0.780). The control group had the lowest fracture resistance (891.43±202.22 N) and the highest catastrophic failure rate (P<0.05). Compared to the control group, the use of fiber post reduced the percentage of catastrophic failure while increasing the ferrule height did not influence the fracture resistance of the restored specimens.ConclusionsWithin the limitations of this study, increasing the ferrule length did not influence the fracture resistance of endodontically treated teeth restored with glass ceramic crowns. Insertion of a fiber post could reduce the percentage of catastrophic failure of these restorations under function.

The occurrence of canine tooth dimorphism in Indian subjects has been investigated and the use of two statistical methods of evaluation compared. These were the methods of N.G. Rao and co-workers published in 1988 and quadratic discriminant analysis for correct classification of sex. Parameters considered were (i) the mesiodistal width of maxillary and mandibular canines, (ii) the maxillary canine arch width (intercanine distance) and (iii) the mandibular canine arch width. The results indicated significant dimorphism of the maxillary and mandibular canine teeth. When the results of the arch widths were subjected to the two statistical methods, differing results were obtained in the accuracy of sex classification. The percentage of correct classifications of sex was higher when using quadratic discriminant analysis.

Students tended to grade their teeth preparations higher compared to the examiner grades, inter examiner variation in the grades existed and the grades of the anterior teeth were higher compared to the posterior teeth.

The aim was to investigate in vitro the fracture resistance (FR) of endodontically treated teeth (ETT) with conservative access cavity restored using various direct and indirect restorative materials and techniques. Seventy-two mandibular first molars were equally divided into six groups. Teeth in Group 1 were untreated (controls). In Groups 2, 3, 4, 5 and 6, teeth were restored with amalgam, composite resin, ceramic inlay, ceramic onlay and zirconium crown, respectively. A fracture test was performed on all teeth using a static load. Compared with other groups, teeth in Groups 3 (P < 0.05) and 6 (P < 0.05) had the highest FR values with no significant difference in-between them. Teeth in Group 4 had the lowest FR than other groups (P < 0.05). All restorative techniques tested led to a significant reduction in FR. It is necessary to consider type of fracture when evaluating fracture resistance of endodontically treated teeth. Crowned molars had the highest favourable fractures among the five treatment groups. Although the results of this in vitro study showed variations between tested techniques in ETT with a conservative access cavity, further long-term controlled clinical trials are required to confirm these in vitro findings.

SUMMARY The occurrence of canine tooth dimorphism in Indian subjects has been investigated and the use of two statistical methods of evaluation compared. These were the methods of N.G. Rao and co‐workers published in 1988 and quadratic discriminant analysis for correct classification of sex. Parameters considered were (i) the mesiodistal width of maxillary and mandibular canines, (ii) the maxillary canine arch width (intercanine distance) and (iii) the mandibular canine arch width. The results indicated significant dimorphism of the maxillary and mandibular canine teeth. When the results of the arch widths were subjected to the two statistical methods, differing results were obtained in the accuracy of sex classification. The percentage of correct classifications of sex was higher when using quadratic discriminant analysis.