Objective:The aim of this in vitro study is to evaluate the effect of expiration date on some mechanical properties of resin composites after controlled storage of syringes and compules in a refrigerator at 4°C.Materials and Methods:Specimens were tested at 7 days after storage in distilled water at room temperature. The investigated properties are the static modulus of elasticity, the flexural strength, and the Vickers microhardness. Same batches of restorative materials were examined at baseline (at least 1 year before their expiration date) and 1 year after they expired.Results:Paired t-test is used to compare the results between the two groups using StatView software (version 5.0) SAS Campus Drive Cary, North Carolina, USA. Except for the flexural strength, no statistical differences were found between the mechanical properties of the expired and the unexpired group.Conclusion:The 1-year expiry date did not seem to affect the investigated mechanical properties.

Objective Diode lasers have multiple indications in everyday dental practice. They allow carrying out incisions, coagulation of soft tissue, and Low-Level Laser Therapy. The goal of this study is to compare histologically the tissue interaction zones and edges of an induced laser incision on rabbits' tongues with three different wavelengths of 810, 940, and 980 nm in continuous mode. Methods Fourteen male rabbits were divided into six groups. Each animal underwent three incisions of 10 mm length on the right ventral face of the tongue, carried out in continuous mode with three diode lasers with different wavelengths of 810, 940, and 980 nm. Rabbits were sacrificed at 0, 1, 2, 6, and 15 hours and 14 days. Five rabbits were sacrificed at 0 hours and 2 hours and one rabbit was sacrificed at 1, 6, and 15 hours and at 14 days. The appearance of neutrophils marked the onset time of the inflammatory reaction. Histological study of the incisions was chosen to evaluate the edges and to measure the depth and width of carbonization and necrotic and inflammatory zones. Healing was evaluated at 14 days. Friedman test was used to assess statistical differences between groups. Results In the experimental adopted conditions, the carbonization zone was marked by degradation of vacuoles and an elongation of nuclei and was observed on the edges of incisions. Carbonization and necrotic and inflammatory zones were measured for rabbits sacrificed at 0, 1, 2, 6, and 15 hours but the onset of inflammation zone marked by the infiltration of neutrophils did not appear before 6 hours. The neutrophils infiltration was higher at 15 hours than at 6 hours. Complete healing was shown at 14 days. According to the time for the regularity of the edges, the interpretation was qualitative without a statistical test. The statistical analysis of the three different diode lasers in this study showed nonsignificant difference between the different groups for the depth (p = 0.121) and width (p = 0.376) of the incisions, the carbonization zone (p = 0.692), and the necrotic zone (p = 0.223). For the inflammation zone at 6 and 15 hours, statistical analysis was not carried out; only one rabbit was enough to evaluate onset of neutrophils infiltration and to compare its density for 6 and 15 hours. Conclusion These results indicate that diode laser used in the continuous mode is predictable for induced incision. The use of three diode lasers with different wavelengths of 810, 940, and 980 nm did not reveal a significant statistical difference according to depth and width of the incision and for carbonization and necrotic zone. The appearance of neutrophils was marked between 4 and 6 hours and was higher at 15 hours.

The aim was to evaluate debris and smear layer at 1, 3 and 5 mm from the foramen of single-file systems WaveOne Gold â and Reciproc Blue â . Thirty single-rooted teeth were prepared using one of the following NiTi instruments WaveOne Gold â and Reciproc Blue â . Root canals were observed under a scanning electron microscope. The presence of debris and smear layer at the apical third of root canals was evaluated. Data were analysed by Friedman and Wilcoxon tests. WaveOne Gold â produced significantly less debris and smear layer compared to Reciproc Blue â . However, the mean amount of debris was significantly different within distances for WaveOne Gold â , while no difference were observed for Reciproc Blue. The mean amount of smear layer was not significantly different within distances with WaveOne Gold â and Reciproc Blue â . Both systems showed debris and smear layer in the apical third; nevertheless, WaveOne Gold â showed better results.

Objectives This in vitro study aimed to compare the amount of mixed and dried debris extruded with three endodontic NiTi (nickel–titanium) systems at three levels beyond the major apical foramen. The null hypothesis is that there would be no differences between the different rotary systems in terms of apically extruded debris. Materials and Methods  Forty-eight roots of human extracted molars with 20 to 40-degrees curvature were divided randomly into three groups (n = 16) instrumented with ProTaper Next, BT RaCe, and WaveOne Gold, respectively. Instrumentation was performed at the major foramen and over instrumented 0.5 mm, 1.0 mm and 1.5 mm beyond. Irrigation was performed with sodium hypochlorite. Apically extruded debris was collected. Results Comparison of mixed extruded debris (solution/debris)and dried debris according to group and level of instrumentation showed that WaveOne Gold at the foramen and ProTaper Next beyond the foramen (p < 0.0001) resulted in significantly less extruded debris than other files and within the four levels using repeated measures analysis of variance (p < 0.0001b). Conclusions All systems exhibit extruded debris during instrumentation but in different amounts.

Aim:The aim of the present in vitro study to compare canal straightening following shaping of curved canals with three types of new generation nickel-titanium (NiTi) rotary instruments-ProTaper Next (PTN)®, BT RaCe (BTR)®, and WaveOne Gold (WOG)®- and three different levels of protrusion beyond the major apical foramen.Materials and Methods:Forty-five extracted human maxillary and mandibular molars with at least one curved canal were distributed in three comparable groups of 15 canals each. The canals were instrumented to the major foramen and then overinstrumented with the final file 0.5 mm, 1 mm, and 1.5 mm beyond the foramen using PTN (Group PTN = 15), BTR (Group BTR = 15), and WOG (Group WOG = 15). Standardized pre- and post-instrumentation radiographs of the root canal were obtained for all groups using digital intraoral radiographs coupled with software. Differences in the degree of curvature were regarded as straightening and canal curvature was evaluated based on Schneider technique using the AmScope software for measurements and compared between groups and levels of instrumentation applying Mixed-model ANOVA. Significance was set at 0.05.Results:Canal curvature tended to gradually straighten out as the level of instrumentation increased in all three groups without statistically significant difference among the groups (P = 0.826).Conclusion:Overinstrumentation in curved canals resulted in straightening of the canal curvature.