Vol 4, No 2 (2007)
Proceeding Abstracts
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Objective: The aim of this study was to evaluate fracture characteristics of rigid two-tooth segments splinted with fiber reinforced composite (FRC), with and without application of simulated masticatory forces.
Material and Methods: In this experimental study, 80 extracted maxillary bicuspids were joined in pairs from the buccal aspect using FRC. The specimens were divided into two groups. In group A, the fracture load of FRC was measured. The 20 specimens of group B were initially loaded in a chewing simulator machine for 4×105 cycles to simulate a two-year chewing period. Samples that withstood these loads were assessed for fracture load. The results were compared using student t-test. Stereomicroscopic evaluation of fracture areas was performed to determine the fracture pattern.
Results: None of the specimens in group B failed during application of simulated masticatory forces, meaning that the survival rate was 100%. Mean (standard deviation) of fracture loads in groups A and B were 195.80 (14.345) and 190.57 (24.027), respectively. No significant difference was found in mean fracture loads between the two groups. The overall fracture pattern was similar in both groups.Conclusions: FRC bars demonstrated sufficient durability to withstand chewing forces within the chewing simulation period. The fracture loads were higher than the mean mastication forces and remained almost unchanged after application of these forces.
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Objective: The aim of this study was to evaluate and compare the cleaning ability and instrumentation time of manual and rotary methods used for preparation of primary anterior teeth.
Materials and Methods: Forty-four primary anterior teeth were used in this experimental study. Access cavities were prepared and India ink was injected into the canals. The samples were divided into three groups according to the instrument and preparation technique. In group I the root canals were manually instrumented with K-files. Rotary Flexmaster instruments were used for canal preparation in Group II, and the samples in Group III (control) were not instrumented. After canal preparation, the teeth were cleared with methyl salicilate and the removal of India ink was measured in the cervical, middle and apical thirds. The incidence of file breakage and instrumentation time was recorded in the three study groups. Statistical analysis was performed using Mann-Whitney and t-tests.
Results: There was no significant difference in cleaning capacity between the two techniques, but a significant difference was found between the experimental and control groups. Working time was significantly shorter when using the rotary system. No file fracture was observed during the study period.
Conclusion: Regarding the shorter working time for rotary instrumentation and the similar cleaning ability of the two techniques, the application of the rotary system is suggested for preparation of decidious root canals during pulpectomy.
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Objective: This study evaluated the influence of storage time on micro-shear bond strength of two self-etching materials to enamel and dentin.
Materials and Methods: Human third molar teeth were sectioned to 1.5 mm thick beams and randomly divided into 2 groups. In group I, SE Bond and in group II, Tri-S Bond was used to bond a composite rod (AP-X) to each treated surface. Specimens were prepared according to manufacturer instructions. Each group was further divided into three subgroups according to water storage time; 1 day, 6 and 12 months. Micro-shear bond strengths were determined under a crosshead speed of 1mm/min using a universal testing machine and expressed in MPa. Data was statistically analyzed by ANOVA and Dunnett post hoc test.
Results: Micro-shear bond strength of two adhesives to enamel and dentin showed a slight but not significant decrease over time (P>0.5). After one day, the mean bond strength of enamel in groups I and II were 39.47 and 34.65 MPa and in dentin were 45.20 and 36.0 MPa respectively. There was no statistically significant difference between two materials (P=0.190, P=0.082). After six months the bond strength in group I and II was 35.93 and 35.18 MPa for enamel, and 38.27and 35.19 MPa for dentin respectively, these differences was not statistically significant (P=0.520, P=0.179). After one year, the bond strength of enamel in groups I and II, were 34.47and 29.91 MPa, and in dentin were 33.86 and 32.53 MPa respectively which was not statistically significant (P=0.609, P=0.991).Conclusion: The micro-shear bond strength of both adhesives to enamel and dentin decreased slightly over time; however these decreases were not statistically significant.
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Objective: The aim of this study was to measure and compare the transverse strength and deflection of two acrylic resins.
Method and Materials: A total of 30 samples, with dimensions of 2.5×10×65mm, were prepared with Acropars and Meliodent acrylic resins according to ADA specification No. 12. The specimens were divided into two groups of 15 samples each.
A three-point bending test was carried out using a universal testing machine. Differences between the means of the two groups were analyzed with Student's t-test.
Results: The mean (SD) transverse strength was 81.55 (1.54) Mpa in the Meliodent and 73.58 (0.6) Mpa in the Acropars samples, which showed a significant difference (P<0.001). The mean (SD) transverse deflection was 3.86 (0.09) mm and 4.96 (0.06) mm in the Meliodent and Acropars samples, respectively. A significant difference was found between the two groups (P<0.001).
Conclusion: In the present investigation, the transverse strength of the Acropars specimens was smaller than that of the Meliodent samples and ADA specifications. However, the mean transverse deflection was larger in the Acropars group as compared to the Meliodent group. -
Objectives: The purpose of this study was to determine the efficacy of oral sucralfate suspension (1gr/10ml) in the treatment of recurrent aphthous stomatitis (RAS).
Materials and Methods: Fifty-five patients with oral aphthae were included in this randomized, double-blind, placebo-controlled clinical trial conducted in the Department of Oral Medicine, School of Dentistry, Mashhad University of Medical Sciences. In the first part of the study, all subjects were instructed to rinse with a 10% suspension of sucralfate or placebo, 4 times a day for 2 weeks. Clinical examination was performed two times a week. The second part consisted of topical use of sucralfate or placebo 2 times a day for 4 weeks, followed by biweekly inspections for 6 months.
The size and number of the ulcers along with pain severity were assessed in the course of the pretreatment and treatment phases. Recurrence was evaluated during the follow up period. Pearson, c2, and Fisher's exact tests were used for statistical analysis.
Results: On the fourth day of the study, pain relief was encountered in 59% and 14% of the case and control patients, respectively. Also, 63% of the ulcers in the sucralfate group and 71% in the placebo group showed size-reduction on the first visit. During the first 7 days of treatment, the number of ulcers showed reduction in both groups, which was significantly larger in the case group.Conclusion: A 10% suspension of sucralfate accelerated pain relief in aphthous patients and its use is recommended as an adjunct for the treatment of RAS.
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Various materials and techniques have been used in the treatment of periodontal disease to achieve regeneration of lost periodontal tissues including cementum, periodontal ligament (PDL) and alveolar bone. The composition, regenerative potential, application and therapeutic characteristics of several regenerative materials have been evaluated in the present study
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The use of multiple implants in the same jaw requires a detailed knowledge of abutment angulation. The position and angulation of the abutments play an important role in treatment planning and fabrication of the custom tray. Therefore diagnostic casts that contain cover screws may cause problems during implant therapy.
The current article describes a technique for making a preliminary cast with acrylic custom abutments in order to help the clinician select an appropriate impression technique and evaluate the location and angulations of the implant bodies. This method can also aid the technician to provide adequate and proper space for the fabrication of an open custom tray. -
Amelogenesis imperfecta is a heterogeneous group of hereditary disorders. Its treatment continues throughout the patients' childhood and adolescence and consists of advanced restorative care in severe cases.
A thorough prosthodontic treatment plan including orthognatic surgery, full veneer crowns and all ceramic anterior crowns is presented in this clinical report.
