JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2015 | Volume:27 | Issue:4|Papers Count:7

Background and Aim: Stability of mini-screws in bone depends on mechanical factors in the primary phase and biological factors after osseointegration. mini-screws can transfer thermal shocks in the oral cavity to bone marrow. It has been shown that impaired osseointegration and inflammation can lead to failure of mini-screws. The aim of this study was to compare the tissue response to implanted mini screws with and without composite coating of the head. Materials and Methods: In this animal study, mini-screws with 1. 4mm diameter and 6mm length were implanted in the maxilla of 12 male rabbits. One mini-screw was implanted in each of the right and left quadrants of the maxilla. The right side miniscrews received composite coating on their head. The left side mini screws did not receive coating. In the next three months, cold (1° C) and warm (40° C) water were injected into their mouth 10 times daily. After three months, the rabbits were sacrificed, and paraffinized tissue blocks were prepared. The tissue reaction was examined under light microscopy. The paired t-test and Wilcoxon signed rank test were used for statistical analysis. Results: The mean rate of osseointegration of mini-screws with and without composite coatings was 32. 1± 5. 3 and 20. 4± 3. 43, respectively. The rate of osseointegration was significantly higher around mini-screws with composite coating than mini-screws without coating (P<0. 001). In both groups, the newly formed bone was woven and no inflammatory reaction was noted. Conclusion: The rate of osseointegration of mini-screws with composite coatingof the head was higher than that of mini-screws without it.

Background and Aim: The use of light emitting diode (LED) light curing units has recently increased due to optimal properties such as longer durability, no need for filter and less heat generation compared to quartz tungsten halogen (QTH) devices. The aim of this study was to assess the shear bond strength of composite to dentin following lightcuring with QTH and LED light curing units for different time periods. Materials and Methods: In this experimental study, 60 sound extracted human molar and premolar teeth with no decay or restorations were collected. The buccal surface of the teeth was ground to expose adequate amount of dentin. The teeth were randomly divided into six groups. After acid etching and bonding, composite was packed in plastic cylindrical molds and placed on dentin surface. Groups one, two and three were cured by a LED unit (Wood Pecker) with ramp method for 20, 30 and 40 seconds, respectively. Groups four, five and six were cured with a QTH unit (Optilux 501) with a light intensity of 500 mW/cm2 for 20, 30 and 40 seconds, respectively. After keeping the samples for two weeks in distilled water at room temperature, shear bond strength was measured by a universal testing machine at a crosshead speed of 1mm/minute. The data were analyzed by Two-way ANOVA, one-way ANOVA and Tukey’ s HSD test. Results: One-way ANOVA showed a significant difference among the groups and the mean shear bond strength was the highest following light curing by LED device for 40 seconds (18. 63 MPa). Pairwise comparisons by Tukey’ s test showed significant differences in shear bond strength of groups cured with LED unit (P= 0. 059 for the difference between 20 seconds and 40 seconds and P=0. 004 for the difference between 30 seconds and 40 seconds). Conclusion: Use of LED units (ramp method) yielded superior results in terms of shear bond strength compared to QTH. Also, 40 seconds of curing is recommended in use of LED devices.

Background and Aim: Attention to proper communication with patients in dental setting is important in the quality of care. The purpose of the present study was to translate the Dental Consultation Communication Checklist (DCCC) to Persian and validate the Persian version. Materials and Methods: In this descriptive analytical study, the standard 'forwardbackward' method was used to translate the English version of the checklist to Persian. Face and content validity were assessed and the reliability was scored by calculating the intra-class correlation coefficient (ICC) and Cronbach's alpha. A number of 4th, 5th and 6th year dental students completed the checklist. The mean score in each domain was calculated and compared using one way ANOVA test. Results: Of 245 dental students, 83% responded (n=204). The content validity index (CVI) was 0. 83 and 0. 93 for the appropriateness and clarity, respectively. Reliability analysis showed satisfactory result (ICC=0. 86, Cronbach's alpha=0. 89). The selfreported positive response to question “ I introduced myself and explained my role” was weak compared to all other questions. There was no statistically significant difference in the scores obtained by the three groups of dental students. Conclusion: The Persian version of DCCC is a valid and reliable instrument for use in the clinical setting.

Background and Aim: Finding appropriate dental materials with minimal adhesion and colonization of Streptococcus mutans (S. mutans) and other pathogenic bacteria is of great importance. The aim of this study was to compare the level of adhesion of S. mutans to polished IPS e. max and feldspathic porcelain and dental enamel. Materials and Methods: This in vitro experimental study was conducted on 15 specimens in three groups (five polished IPS e. max Press blocks, five polished feldspathic porcelain blocks and five dental enamel blocks) exposed to S. mutans bacterial suspension (1×106 mg/mL). The specimens were then rinsed twice and 0. 1 mL of the new suspension was cultured on blood agar. After 48 hours of storage at 37; C, S. mutans colonies were counted by naked eye. The results were analyzed using one way ANOVA. Results: The adhesion of S. mutans was 24. 4± 8. 44 colonies/mm2 to the enamel, 5. 6± 2. 35 colonies/mm2 to polished IPS e. max Press, and 5. 8± 1. 92 colonies/mm2 to feldspathic porcelain. The difference between enamel and the other two groups in terms of adhesion of S. mutans was statistically significant (P<0. 001); the two groups of ceramics were not significantly different in this regard (P=0. 8). Conclusion: The adhesion of S. mutans to the enamel was higher than that to polished IPS e. max Press and polished feldspathic porcelain.

Background and Aim: Penetration of injectable gutta percha into the root canals is of utmost importance in success of endodontic treatment and is related to the composition, phase and flow of gutta percha. The aim of this study was to evaluate the penetration depth of gutta percha into simulated root canals using 60 and 80 flow rates by BeeFill system. Materials and Methods: This in vitro experimental study was done on 48 artificial root canals created in the form of a semicircle in a bovine femur. The canals were prepared using FlexMaster rotary instruments according to the manufacturer’ s instructions for narrow canals and filled with gutta percha and AH26 sealer using BeeFill 60 and 80 flow rates at 180° C with 0. 6mm applicator tips to 0. 5mm to the working length. Digital images were taken from the root fillings and the root filling penetration depths were determined for each sample. The data were statistically analyzed by independent sample t-test. Results: The mean penetration depths of thermo-plasticized gutta percha were 2. 58mm and 4. 83mm for 60 and 80 BeeFill flow rates, respectively. The difference between the two rates was not statistically significant (P=0. 69). Conclusion: Both 60 and 80 BeeFill flow ratesprovided almost similar penetration depth of gutta perchain artificial root canals.

Introduction: Radicular cysts (RCs) are the most common odontogenic cystic lesions with an inflammatory origin. Radicular cysts originate from epithelial remnants of the periodontal ligament as a result of inflammation, which is generally a consequence of pulp necrosis. Dental caries is the most common etiology of RCs and theyaremost commonlyreported in primary mandibular molars. Treatment options include root canal therapy, extraction and surgery. Case Presentation: A 10. 5 year-old patient presented to the Pediatric Dentistry Department of Tehran University of Medical Sciences (TUMS) with a RC associated with a primary mandibular second molar. We performed non-surgical conservative treatment by extracting the involved tooth. After two years of follow up, the lesion healed and the second premolar erupted.

Background and Aim: Keratocystic odontogenic tumor (KCOT), formerly known as odontogenic keratocyst (OKC), is a developmental odontogenic cyst with an invasivebehavior and high recurrence rate. Radicular cyst (RC) is an inflammatory non-invasive dental cyst, with no tendency to recurrence. Bcl2-associated X (BAX) protein acts as an apoptotic activator (pro-apoptotic protein), disrupts the integrity of mitochondrial membrane, and leads to the loss of outer membrane and release of cytochrome c from the inner membrane into the cytosol. Since KCOT is more aggressive and has a greater tendency to recurrence than RC, the aim of this study was to assess the immunohistochemical expression of BAX protein in the epithelial lining of RC and KCOT. Materials and Methods: In this descriptive analytical study, paraffinized blocks of 17 RCs and 17 KCOTs fixed in 10% formalin were used (all KCOT samples were noninflammatory and non-syndromic). After confirming the diagnoses by reviewing the slides, tissuespecimens with sufficient length of epithelium were stained by immunohistochemistry (IHC) for BAX marker. Then, the stained cells were randomly counted in five high power fields. Analysis of the data was performed using SPSS 21 via Student's t-test and chi-test. Results: Percentages of staining for BAX marker were 16. 4± 9. 4% and 66. 4± 12. 3% in the epithelial lining of KCOT and RC, respectively and there was a significant difference between them (P<0. 001). Conclusion: According to the findings, lower expression of BAX protein in KCOT justifies its more aggressive behavior and tendency to recurrence compared to RC.