Purpose: The aim of this study was to evaluate the apical sealing ability of Total Fill BC sealer and AH Plus sealer with single cone and continuous wave condensation obturation techniques using dye extraction leakage method. Materials and Methods: Eighty-four extracted human single-rooted teeth with round canals were decoronated at 12 mm length and instrumented using crown down technique with the iRace rotary file system to apical file size 40 with 0.04 taper. The roots were randomly divided into four experimental groups (n=20). Group (A1) contained roots which were obturated with Total Fill BC sealer with a single cone. Group (A2) contained roots which were obturated using Total Fill BC sealer with continuous wave condensation. Group (B1) contained roots which were obturated using epoxy resin sealer (AH Plus) with a single cone. Group (B2) contained roots which were obturated using AH Plus sealer with continuous wave condensation. Apical microleakage was assessed with dye extraction method where the absorbance of leaked 1% methylene blue dye was measured using a spectrophotometer. The absorbance values were converted into concentrations, and the data was analyzed using One way ANOVA test. Results: The mean dye concentration values were 0.012, 0.016, 0.011 and 0.015 for Group A1, Group A2, Group B1 and Group B2, respectively. One-way ANOVA indicated no significant difference in dye leakage between the investigated groups (F = 0.938). Conclusion: With the limitation of the study, it was concluded that Total Fill BC was equivalent to AH Plus in apical sealing ability when using single cone or continuous wave condensation. The single cone can provide a similar apical seal of canal filling as can be achieved by using continuous wave condensation methods, in the round canal.

Background: Light-curing is a crucial step during the application of composite resin restorations. Composite's success depends on delivering enough light energy to the resin to achieve adequate polymerization. However, dentists are not recognizing the importance of proper light-curing technique. Objectives: To measure light energy delivered to simulated restorations by preclinical dental students and dentists in internship year. To evaluate the effect of experience and training on the clinician's ability to light-cure composite restorations. Methods: A group of 50 preclinical dental students and a group of 50 internship dentists light-cured for 10 seconds, a simulated class III and class I restorations positioned in a patient simulator (MARC-Patient Simulator [BlueLight Analytics Inc., Canada]) that measured the irradiance and energy delivered by the curing light. Then participants received individualized training on optimizing their light-curing technique. They were retested after the training. Statistical analysis was done with two-way ANOVA and Tukey's test. Results: Participants delivered an average of 60% more energy after the instructions, which is a significant improvement (P < 0.05). The number of participants that failed to deliver the minimum amount of energy (6 J/cm 2 ) decreased significantly from 37.5% to 2.5%. There was a significant difference in the amount of energy delivered by the Preclinical and Internship groups (P < 0.05). Conclusion: Initially, many participants were not using the curing light properly.Light-curing technique improved with training and using a patient simulator. Experience can enhance the operator's ability to light-cure composite restorations. However, a training session can improve light-curing performance more than years of experience. K E Y W O R D Scuing lights, dental education, light-curing, resin restoration, restorative dentistry 652

Objectives: To assess restorative treatment decisions on approximal caries by dental practitioners in College of Dentistry at Ajman University regarding treatment threshold, restorative techniques and restorative materials, and to evaluate the characteristics of dentists relative to their treatment decisions. Materials and Methods: Questionnaires were completed by a population of 180 dentists working in the university’s clinics. The questionnaire assessed responses to the treatment threshold for a hypothetical approximal carious lesion, the most preferred types of cavity preparation and restorative materials. Results: Out of the 180 participants, 57.9% were females, and 42.2% were males. Eighty-three percent were 35 years old or less, 12.2% were between 36 and 50 years, and 4.4% were 50 years or older. Most participants were UAE graduates (84.4%). Majority of the participants would delay surgical intervention of the approximal carious lesion until it reaches the dentine-enamel junction (41%), and 27% would wait further until it reaches into the outer dentine, while only 21% would intervene when the lesion is limited to enamel. The majority of the participants preferred simple box preparation (72.8%), and most of them chose composite as the restorative material (85%). Conclusion: There is some variation among restorative treatment decisions of approximal caries by Ajman University’s dentists, but the majority tend to delay restorative intervention until caries reaches dentine, they prefer minimally invasive restorative techniques, and prefer composite as a restorative material.

Background: Light-curing is a crucial step during the application of composite resin restorations. The clinical success of composite depends on the Light-Curing Units (LCU) to deliver adequate light energy to polymerize the resin. However, light-curing usually does not receive the proper awareness it deserves. Objective: This study aims to evaluate the effect of contamination and debris of the LCU’s tip on its light output. Determine the effect of damage to the LCU’s tip such as chipping, dents and scratches. Additionally, it evaluates the effect of plastic barrier sleeves. Methods: Sixty LED LCUs were tested using MARC™ Resin Calibrator (BlueLight Analytic Inc., Halifax, Canada) to measure their irradiance and energy before and after cleaning their tips. They were also tested with and without a clear plastic barrier. Additionally, four damaged LCUs received new tips and were tested again. Kruskal-Wallis H and One-Way ANOVA tests were used for statistical analysis. Results: Cleaning the LCUs’ tips showed significant improvement, an average increase of 8.2%. However, some units increased by up to 47% in irradiance and energy values. Replacing the damaged tip with a new one significantly improved the output of the LCUs, increasing light energy by up to 73%. The barrier used in this study caused 7% reduction in the energy delivered by the LCUs. The statistical analysis showed that cleaning the LCUs and replacing their damaged tips resulted in a significant increase in energy (p<0.05). Conclusion: Unclean or damaged LCUs’ tips can drastically reduce the light output of the LCUs, reducing the quality of the composite restorations. Clinicians are strongly recommended to regularly monitor, clean and maintain their curing lights.

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