Journal of Islamic Dental Association of IRAN
Volume:27 Issue: 3, 2015

Shear bond strength is an important mechanical property in clinical durability of tooth colored restorations. The use of light emitting diode (LED) light curing units has recently increased compared to quartz tungsten halogen (QTH) devices, due to optimal properties such as optimal durability, no need for filter and no heat generation. The aim of this study was to assess the shear bond strength of composite to dentin following light curing with QTH and LED light curing units for different times.
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 one-way ANOVA, two-way ANOVA and Tukey’s HSD test.
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).
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.

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.
In this cross-sectional study, the standard 'forward-backward' method was used to translate the English version of the checklist. Face and content validity were assessed and the reliability was scored by measuring intra-class correlation coefficient (ICC) and Cronbach's alpha. A number of 3rd, 4th and 5th year dental students completed the checklist. The mean score in each domain was calculated and compared using ANOVA and SPSS version 16.0.
Of 245 subjects, 83% responded (n=204). The content validity index 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 positive self-reported 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 students.
The Persian version of DCCC is a valid and reliable tool for use in the clinical setting.

Finding appropriate materials to which low adhesion and colonization of Streptococcus mutans (S. mutans) and other pathogenic bacteria occurs 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.
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 taken and 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 ANOVA.
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 The adhesion of S. mutans to the enamel was higher than that to polished IPS e.max press and polished feldspathic porcelain.

Effective bond to dental substrate and good marginal adaptation at the tooth/restoration interface are important in clinical success of restorations. Microleakage is the most important factor responsible for marginal staining, development of secondary caries, pulpal damage and eventual failure of composite restorations. The aim of this study was to evaluate the effect of sodium hypochlorite on microleakage of two step total etch bonding agents with different solvents. Also, the effect of replacement of phosphoric acid with sodium hypochlorite on microleakage was evaluated.
This in vitro experimental study was conducted on 80 sound bovine incisors. Eighty class V cavities were prepared on buccal surfaces of the teeth. The occlusal and cervical margins were prepared in the enamel. Then, the samples were randomly divided into eight groups (n=10). After bonding, the cavities were restored with Z250 composite. After finishing and polishing, the specimens were thermocycled for 1000 cycles between 5-55C and immersed in 2% aqueous solution of basic fuchsin for 24 hours. Then, they were sectioned longitudinally and analyzed for microleakage under a stereomicroscope. Microleakage was evaluated and compared among the groups using the Kruskal-Wallis test and two-way ANOVA.
Rate of microleakage was the highest in acid sodium hypochlorite and the lowest in sodium hypochlorite acid groups. Significant differences existed between the two bonding agents except for sodium hypochlorite acid. The highest and lowest microleakage in acid sodium hypochlorite were noted in One Step and Single Bond, respectively. In use of sodium hypochlorite alone, microleakage was not significantly different between the two groups. Single Bond had the highest microleakage in the control group. The interaction effect of preparation method and type of bonding agent was significant as well (P=0.001).
Application of sodium hypochlorite before dentin etching increased microleakage in use of One Step bonding agent compared to etching alone. However, its use after etching in use of Single Bond improved the seal.

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 the simulated root canals using #60 and #80 flow rates by Beefill system.
This in vitro experimental study was done on 48 artificial 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 sealer using BeeFill #60 and #80 flow rates at 180°C with 0.6-mm applicator tips. 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 student t-test.
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).
Both #60 and #80 BeeFill flow rates provided almost similar penetration depth of gutta percha in the artificial root canals.

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 they are mostly reported in primary mandibular molars. Treatment options include root canal therapy, extraction and surgery.
A 10.5-year-old patient presented to the Pediatric Dentistry Department of TUMS with a RC associated with a primary mandibular second molar. We performed non-surgical conservative treatment. After two years of follow up, the lesion healed and the second premolar erupted.

Stability of mini screws depends on mechanical factors in the primary phase and biological factors after osseointegration. The mini screws can transfer thermal shocks in the oral cavity to the bone marrow. It has been shown that level of osseointegration and inflammation are related to the failure of mini screws. The aim of this study was to compare the tissue response to mini screws with and without composite coating in the head.
In this in vitro, experimental 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 mini screws had composite coatings on their head. The left side mini screws did not have such coatings. In the next three months, cold (1C) and warm water (40C) 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.
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 for mini screws with composite coatings than mini screws without them (P>0.0001). In both groups, the newly formed bone was woven and no inflammatory reaction was noted.
The rate of osseointegration of mini screws with composite coatings in the head was higher than that of miniscrews without them.

Odontogenic keratocyst (OKC) is a developmental odontogenic cyst with an aggressive nature and high recurrence. Radicular cyst (RC) is the most common dental cyst, which may expand and cause bone loss. Bcl-2-associated X (BAX) protein acts as an apoptotic activator (pro-apoptotic), 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 OKC 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 OKC.
In this study, paraffinized blocks of 17 RCs and 17 OKCs fixed in 10% formalin were used (all OKC samples were non-inflammatory and non-syndromic). After identifying and confirming the diagnoses by reviewing the slides, the samples 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. The cells were scored on the basis of expression as follows: (-): negative, (): less than 10%, (): between 10-25%, (): between 26-50% and (ﯯ): more than 50%. Analysis of the data was performed using SPSS 21 and Student's t-test and chi-square test.
Percentages of staining for BAX marker were 16.4±9.4 and 66.4±12.3 in the epithelial lining of OKC and RC, respectively and there was a significant difference between them (P According to the findings, lower expression of BAX protein in OKC justified its more aggressive behavior and tendency to recurrence compared to RC.