ABSTRACT
Statement of Problem: A strong bond of fiber post to resin core, as well as to dentin would critically ensure the durability of restorations in endodontically treated teeth
Purpose: The purpose of this study was to evaluate the effect of etch-and-rinse dentin bonding systems on the bond strength between resin core and fiber post after application of 24% hydrogen peroxide
Materials and Method: Twenty-four fiber posts [RTD; St. Egèven, France] were treated with 24% hydrogen peroxide for 10 minutes. They were randomly divided into 4 groups [n=6] based on the bonding agent used: Group P: Prime and Bond, Group O: One Step, Group S: Single Bond and Group E: Excite. Each group was prepared according to the manufacturer's instructions. For all posts, a flowable composite core [?liteFlo, Bisco, USA] were built-up over the bonded area. Each specimen was sectioned to produce 2 sticks, 1mm in thickness and underwent microtensile bond strength [µTBS]. Data were analyzed using one-way ANOVA at the 0.05 level. The fractured surfaces of all sticks were evaluated by stereomicroscope [× 20]. SEM assessment of two sticks from each group was performed to evaluate the surface morphology
Results: The means and SDs of micro TBS were: Group P: 10.95 +/- 1.74; Group S: 10.25 +/- 2.39; Group E: 9.52 +/- 2.07; and Group O: 9.12 +/- 1.34. There was no statistic means and SDs ally significant difference in bond strength means between the groups used [p> 0.05]
Conclusion: The results of this study indicated the bonding agents used had no significant influence on the bond strength of fiber post to composite core
ABSTRACT
Fractured ceramic crowns can sometimes be repaired with composite resin. The aim of the current study was to determine the shear bond strength of composite to Feld spathic porcelain after CO[2] and Er:YAG laser porcelain surface preparation. In this in-vitro study, 36 Feldspathic porcelain blocksmeasuring 1*10*10 mm were divided into 3 groups of 12. Porcelain surfaces in the first and second groups were treated with 1.8W CO[2] laser and 5W Er:YAG laser irradiation, respectively. Third group specimens were subjected to 9.5% hydrofluoric acid surface conditioning. All groups received application of silane and adhesive after wards. A composite cylinder with 3.5 mm diameter and 5 mm height was bonded to specimens. In order to evaluate the shear bond strength, a Universal Testing Machine with crosshead speed of 1 mm/min was used. Statistical analysis was performed using one-way ANOVA and Tukey's HSD test and P<0.05 was considered statistically significant. The mean shear bond strength values [MPa] were 13.03 +/- 2.57%, 12.02 +/- 3.4 and 19.23 +/- 4.62, for the first, second and third groups respectively. One-way ANOVA revealed a statistically significant difference in this respect between the three groups [P< 0.001]. Tukey's HSD test demonstrated significant differences between the first and third groups [P= 0.000] as well as the second and third groups [P=0.000]. However, no significant difference was detected between the first and second groups [P =0.778]. Considering the study results, CO[2] or Er:YAG laser irradiation is not suggested as an appropriate alternative to hydrofluoric acid for surface preparation of Feld spathic porcelain
ABSTRACT
Fluoride is the most important mineral in the prevention of tooth caries. This study evaluated the relationship between salivary pH levels, fluoride baseline concentration in saliva and dmft index in 5-year-old children attending kindergartens in Hamadan, during 2004. A total of 200 children [100 male and 100 female], 5 years of age were selected for this cross sectional study. The dmft indices were determined through examination of all subjects using a dental mirror and explorer under natural light. 100 children [50 male and 50 female] were divided into 2 groups: dmft>l and dmft<1 which constituted the case and control groups, respectively. Approximately 1-3 ml unstimulated saliva was collected from each subject and fluoride concentration was measured in ppm using a fluoride ion selective electrode. The pH of all samples were assessed by a pH meter. The data were analyzed using T-test. Fluoride concentration and salivary pH levels were 0.0113 +/- 0.007 ppm and 6.74 +/- 0.28 in the case group and 0.0321 +/- 0.011 ppm and 6.53 +/- 0.44 in the control group, respectively. A statistically significant relationship was observed between the baseline fluoride and pH levels of saliva and dmft indices. According to these results an appropriate concentration of fluoride in the saliva and an increased pH can reduce the dmft index in children
Subject(s)
Humans , Male , Female , Saliva/chemistry , Saliva , Cross-Sectional Studies , Dental Caries , Child , DMF Index , Hydrogen-Ion ConcentrationABSTRACT
The width ratio of teeth is very important for esthetic of maxillary anterior teeth. Some dentists utilize golden proportion [1.618] as a main guidance to establish a harmonious proportion. Although the proportion has been used frequently in dentistry, it has rarely been studied, especially among Iranian population. The aim of this study was to evaluate golden proportion in a group of Iranian dental students, in Hamedan. This cross-sectional study was conducted with 165 dental students [79 female and 86 male] in Hamedan Dental School-Iran. The inclusion criteria for case selection was lack of rotation, tilt, spacing, caries, restoration or missing in anterior maxillary teeth. Photographs of the subject's teeth were taken from frontal view. The apparent width of the teeth were measured by a digital caliper and width ratio's of central to lateral, lateral to canine and canine to first premolar were calculated. Then data were analysed by student t-test, t-paired t-test and one sample t-test. In this study the mean ratio of central to lateral, lateral to canine and canine to first premolar width on the right side were 1.489 +/- 0.153, 1.200 +/- 0.153, 1.432 +/- 0.271 respectively and 1.525 +/- 0.151, 1.235 +/- 0.170, 1.477 +/- 0.368 for the left side. In comparing the results and golden proportion [1.618], it was concluded that golden proportion was absent in a high percent of the subjects. Comparing the mentioned ratios showed that central to lateral width was the closest ratio to golden proportion and lateral to canine width had the lowest similarity to golden proportion. In addition, it was showed that there was not a significant difference between male and female in apparent width ratios, in maxillary antetior teeth. This study indicated that golden proportion can not be assumed as a constant ratio between the apparent widths of maxillary anterior teeth in all conditions
ABSTRACT
Taurodontism is a rare dental anomaly in which the involved tooth has enlarged and elongated body and pulp chamber with apical displacement of the pulpal floor. Endodontic treatment of these teeth is challenging because it requires identifying the number of root canals. A case of bilateral involvement of maxillary first molar teeth is presented. Endodontic treatment of the right maxillary first molar with taurodontism was indicated due to irreversible pulpitis. In this article, we described the procedure of root canal therapy for this case