Dimitrios Tortopidis

Association between self-reported bruxism activity and occurrence of dental attrition, abfraction, and occlusal pits on natural teeth

STATEMENT OF PROBLEM It is unclear whether subjects who report tooth clenching and/or grinding have more noticeable clinical signs of dental attrition, abfractions, and occlusal pits on their natural teeth than subjects who do not report bruxism activity. PURPOSE The purpose of this study was to determine whether there was an association between self-reported (or not reported) bruxism activity and occurrence of dental attrition (anterior, posterior), abfractions, and occlusal pits on natural teeth. MATERIAL AND METHODS One hundred and two volunteer adult Greek subjects (mean age 44.6 +/-5.7 years) were classified into 2 groups (50 self-reported bruxers and 52 nonbruxers) according to 2 inquires regarding grinding and/or clenching of their teeth. Dental attrition (anterior, posterior) was assessed by 2 calibrated experienced examiners on diagnostic casts on a tooth-by-tooth basis, using a previously well established ordinal scale. Abfraction lesions (V-shaped, in the cervical region) and occlusal pits were recorded if these clinical signs were found on at least 2 natural teeth. Statistical comparisons between the 2 groups relative to the distribution of the occurrence of the 4 clinical signs were performed by means of the exact version of the chi-square test. The Fishers exact test was used for the comparison of percentages. The intra- and interexaminer reliability was assessed by means of the Cohens kappa coefficient (alpha=.05). RESULTS The results demonstrated that there was a significant association between self-reported bruxism and occurrence of the 4 clinical signs. Although the 2 groups were significantly different according to the distribution of the 4 clinical signs, the greatest differences occurred for the anterior and posterior attrition signs. CONCLUSIONS In this study, the occurrence of 4 clinical signs (posterior or anterior dental attrition, abfractions, and occlusal pits) was associated with self-reported bruxers. It is suggested that, primarily, signs of dental attrition may differentiate self-reported bruxers from nonbruxer subjects.

The effect of ferrule on the fracture mode of endodontically treated canines restored with fibre posts and metal-ceramic or all-ceramic crowns

OBJECTIVES The aim of this study was to evaluate the fracture mode of endodontically treated canines (ETC) restored with glass-fibre posts (GFP) and either metal-ceramic (MC) or all-ceramic (AC) crowns, in the presence or absence of 2 mm ferrule height. METHODS Fifty recently extracted human maxillary canines were endodontically treated and randomly divided into 5 groups of 10 specimens each. Four groups (with or without ferrule) were restored with GFP, composite cores and either MC or AC crowns. The fifth group with intact ETC served as control. Teeth were loaded to fracture at a 135° angle to their long axis, at a cross-head speed 0.5 mm/min. The fracture modes were divided through optical microscopy to repairable and irreparable. Statistical analysis was performed by means of the Fishers Exact test. RESULTS All groups presented brittle fracture following bending deformation. Irreparable root fractures were the primary fracture mode independently of ferrule. The percentages (%) of repairable fractures were not statistically significant different amongst the MC and AC restored teeth independently of ferrule. However the 2 mm ferrule was associated to a higher percentage of repairable fractures, especially in teeth restored with AC crowns. CONCLUSIONS The percentage (%) of repairable fractures was higher in all-ceramic compared to metal-ceramic ETC and in restorations with ferrule, although the differences were not statistically significant. CLINICAL SIGNIFICANCE This in vitro study supports evidence that neither the type of crown restoration nor the presence of ferrule affects statistically significantly the mode of fracture of ETC restored with GFP.

Effect of a crown ferrule on the fracture strength of endodontically treated canines restored with fiber posts and metal-ceramic or all-ceramic crowns.

The aim of this study was to comparatively evaluate the fracture strength of endodontically treated canines restored with glass-fiber posts (GFPs) and either metal-ceramic (MC) or all-ceramic (AC) crowns in the presence or absence of 2 mm of ferrule height. Fifty human maxillary canines were endodontically treated and randomly divided into five groups of 10 specimens each. The first group remained intact (control), while the remainder were restored with GFPs and composite cores with either MC or AC crowns. Each of the AC and MC groups was equally divided between teeth with or without ferrule. Teeth were embedded in acrylic resin and loaded at a 135-degree angle to their long axis until fracture. Fracture strength was not significantly different between ferrule and no ferrule groups (P = .571), but was significantly larger for the MC groups compared with the control and AC groups (P = .009 and P = .024, respectively). A significant effect of the type of restoration was found as teeth restored with MC crowns presented significantly higher fracture strength, independently of ferrule.

Accuracy of 3 different impression techniques for internal connection angulated implants.

STATEMENT OF PROBLEM Making implant impressions with different angulations requires a more precise and time-consuming impression technique. PURPOSE The purpose of this in vitro study was to compare the accuracy of nonsplinted, splinted, and snap-fit impression techniques of internal connection implants with different angulations. MATERIAL AND METHODS An experimental device was used to allow a clinical simulation of impression making by means of open and closed tray techniques. Three different impression techniques (nonsplinted, acrylic-resin splinted, and indirect snap-fit) for 6 internal-connected implants at different angulations (0, 15, 25 degrees) were examined using polyether. Impression accuracy was evaluated by measuring the differences in 3-dimensional (3D) position deviations between the implant body/impression coping before the impression procedure and the coping/laboratory analog positioned within the impression, using a coordinate measuring machine. Data were analyzed by 2-way ANOVA. Means were compared with the least significant difference criterion at P<.05. RESULTS Results showed that at 25 degrees of implant angulation, the highest accuracy was obtained with the splinted technique (mean ±SE: 0.39 ±0.05 mm) and the lowest with the snap-fit technique (0.85 ±0.09 mm); at 15 degrees of angulation, there were no significant differences among splinted (0.22 ±0.04 mm) and nonsplinted technique (0.15 ±0.02 mm) and the lowest accuracy obtained with the snap-fit technique (0.95 ±0.15 mm); and no significant differences were found between nonsplinted and splinted technique at 0 degrees of implant placement. CONCLUSIONS Splinted impression technique exhibited a higher accuracy than the other techniques studied when increased implant angulations at 25 degrees were involved.

Comparison of Elastomeric Impression Materials’ Thixotropic Behavior

The improved flow characteristics of new elastomeric impression materials are significant factors in the selection ofsuitableproductsfor clinical applications. The aim of this study was to assess the thixotropic behavior and compare the flow characteristics of seven different elastomeric impression materials using a shark fin test. One polyvinylsiloxane showed the highest shark fin height values, while the newly formed vinylsiloxanether material exhibited no significant differences when compared with two polyvinylsiloxanes. One of the five polyvinylosiloxanes presented significantly lower shark fin values than all other materials. It was concluded that flow characteristics for most of the tested materials are acceptable.