Introduction:In recent years, the use of ceramic base zirconia is considered in dentistry for all ceramic restorations because of its chemical stability, biocompatibility, and good compressive as well as flexural strength. However, due to its chemical stability, there is a challenge with dental bonding. Several studies have been done to improve zirconia bonding but they are not reliable. The purpose of this research is to study the effect of plasma treatment on bonding strength of zirconia. Methods: In this in vitro study, 180 zirconia discs' (thickness was 0.85-0.9 mm) surfaces were processed with plasma of oxygen, argon, air and oxygen-argon combination with 90-10 and 80-20 ratio (n=30 for each group) after being polished by sandblast. Surface modifications were assessed by measuring the contact angle, surface roughness, and topographical evaluations. Cylindrical Panavia f2 resin-cement and Diafill were used for microshear strength bond measurements. The data analysis was performed by SPSS 20.0 software and one-way analysis of variance (ANOVA) and Tukey test as the post hoc. Results: Plasma treatment in all groups significantly reduces contact angle compare with control (P = 0.001). Topographic evaluations revealed coarseness promotion occurred in all plasma treated groups which was significant when compared to control (P < 0.05), except argon plasma treated group that significantly decreased surface roughness (P < 0.05). In all treated groups, microshear bond strength increased, except oxygen treated plasma group which decreased this strength. Air and argon-oxygen combination (both groups) significantly increased microshear bond strength (P < 0.05). Conclusion: According to this research, plasmatic processing with dielectric barrier method in atmospheric pressure can increase zirconia bonding strength.

Dental anxiety and fear of needle injection is one of the most common problems encountered by dental practitioners, especially in the pediatric patient. In consequences, it might affect the patient's quality of life. Several methods are suggested to lower the discomfort of local anesthesia injection during dental procedures. Desensitization of injection site is one of the recommended strategies. Among chemical anesthetic topical agents that are effective but might have allergic side effects, using some nonpharmacological and safe techniques might be useful. This study aimed to overview the efficacy of using cooling techniques, mostly by ice or popsicles, warming or pH buffering of drug, and using modern devices to diminish the discomfort of local anesthesia injection during dental procedures.

Aim: The present study was carried out with the objective of comparing the compressive strength and setting time of four experimental nanohybrid mineral trioxide aggregates (MTAs) and angelus MTA. Materials and methods:In this research, four experimental formulations of nanohybrid MTA (groups are with the base of Portland cement, containing nanoparticles of zirconia, aluminum oxide, titanium, nanosilica, and gypsum and bismuth trioxide) and angelus MTA were compared. Powder and water were mixed with the ratio determined by a factory for angelus MTA and were mixed at a ratio of 3:1 in experimental samples until the consistency of putty was reached. These were then placed in stainless steel cylinder generators, with a diameter of 4 mm and a height of 6 mm, for testing compressive strength, and in generators with a diameter of 10 mm and height of 2 mm to test setting time. The samples prepared were tested after 24 hours and a month using a strength-testing machine. A 135 G needle was used to test the initial setting time in the prepared samples, and a 456.5 G needle was used to test the final setting time. In the end, data were analyzed using Statistical Package for the Social Sciences (SPSS) software.Results: Experimental nanohybrid MTA P significantly showed the minimum setting time and experimental nanohybrid MTA Q showed the maximum setting time in 30 days (p < 0.05). Angelus MTA had greater compressive strength than the experimental materials in 24 hours. Clinical significance: Considering that experimental MTAs showed less setting time compared with the commercial type, experimental MTAs can be deployed in clinical usage. Conclusion

Background and Aim: One limitation of caries disclosing dyes is the risk of sound dentin removal. This study sought to assess the efficacy of a newly developed experimental caries disclosing dye in complete removal of infected dentin and its properties in comparison with Snoop caries detecting dye using histological analysis.Materials and Methods: A caries detecting dye with improved properties was experimentally prepared. Twenty permanent teeth with occlusal caries were selected and divided into two groups of staining with the experimental dye (group 1) and Snoop caries detecting dye (group 2). Stained carious dentin was removed and the process of staining and caries removal was repeated until no staining was observed. DIAGNOdent laser caries detection aid was used in all cavities to ensure absence of caries. After decalcification, 5 sections were made of each tooth, Gram-stained and subjected to histological analysis. Presence of bacteria in the two groups following staining with the experimental and Snoop dyes was evaluated and statistically analyzed using Fisher’s exact test.Results: In the Snoop group, bacteria were present in 3 out of 50 (6.0%) specimens. In the experimental group, bacteria were found in 2 out of 60 specimens (4.0%). Fisher’s exact test showed no significant difference in this respect between the two groups.Conclusion: Histological analysis revealed similar efficacy of Snoop and the experimental caries detecting dyes in terms of complete elimination of infected dentin. Considering the improved properties of the experimental caries detecting dye, it may have superior efficacy in preventing unnecessary removal of sound dentin.Bangladesh Journal of Medical Science Vol.17(2) 2018 p.218-223