Aims: The aim of this study was to compare the microhardness of enamel bleached with two different bleaching solutions (chemical and laser activated), preceded or not with acid etching.Materials and methods: Thirty bovine teeth were prepared and haphazardly assigned into two groups (n=15) depending on the bleaching technique. Each group was subdivided into three subgroups (n=5) consistent with acid etching by 37% phosphoric acid. A digital Vickers microhardness tester (VHN) was used to measure enamel microhardness. Three read-outs were conducted to each sample to quantify microhardness. The samples were held in artificial saliva for five days. The microhardness was measured immediately and five days after bleaching. Paired samples t-test and independent samples t-test were employed for statistical analysis.Results: The results of the paired sample t-tests used to evaluate enamel microhardness of the conventional and laser-assisted bleached groups before and immediately after bleaching revealed a significant decrease in both methods in all groups. However, the microhardness after five days increased significantly in all groups when it was compared to that immediately after bleaching. The results of the independent samples t-test employed to assess enamel microhardness between conventional and laser bleaching of the same group type showed no significant differences between any of the groups, with the exception of C2-L2 groups at immediately after bleaching.Conclusion: Acid etching of enamel followed by chemical or laser assisted bleaching resulted in significant microhardness reduction with no effect of etching time (5 or 10 sec.). Storage of samples in artificial saliva for 5 days after bleaching increased the microhardness but wasn't able to restore them to the levels before acid etching and bleaching. As a clinical implication, and for cases requiring enamel etching before bleaching, five seconds etching time may be preferred over ten seconds.

The present study aims to assess the density of bone with Concentrated growth factors and advanced plasma-rich fibrin in the bone defects that were created surgically in the sheep's mandible by the use of radiographic assessment.Materials and methods: Seven defects were made in the bone with 4 mm depth and width on every side of the mandible of the eight sheep, The defects were filled in the following manner: from the proximal to the distal orientation; 1 st , 2 nd , 3 rd , 4 th , and the 5 th defect was full of CGF on the right side and A-FRF is in the left side, the 6 th , and 7 th left empty to filled with physiological clot.Densitometric analysis of the defects of the bone was made to measure the bone density of the 4 intervals (3 days, 7 days, 21 days, 28 days), after the surgery.Results: The result of the Densitometric analysis revealed a major distinction between the CGF group and the A-PRF group when compared to the control group at all four intervals with the density of the bone being the highest in the CGF group followed by the A-PRF group and the control group was the least one show improvement in the bone density.Conclusions: The CGF group increased the density of the bone throughout the entire study period as found by densitometric analysis data.

Aims: This study aimed to compare the surface roughness between different combinations of epoxy-coated and stainless steel archwires in ceramic and stainless steel brackets. Materials and methods: Two types of archwires with a gauge of 0.019x0.025″ used in this study (Fantasia non-coated stainless steel archwire (SSA) (n=18) and tooth tone Epoxy-coated stainless steel archwires (ECSSA) (n=18). The two types of arch wires were slid on two types of brackets of premolars of slot size 0.022x0.030″ roth prescription (n=36) divided equally into monocrystalline sapphire clear esthetic ceramic brackets (CB) and Razor stainless steel bracket (SSB). The Ra surface roughness was measured using an atomic force microscope AFM to assess the wires before and after sliding them into ceramic and steel brackets. Six samples of wires received from the manufacturer were examined; additionally, six samples from each group of wires were taken after the friction test to examine the changes to the surface of the wires caused by the effect of the frictional force. For the statistical analysis One-way ANOVA and Pairwise comparisons between groups, using the DUNCAN test at the level of significant 0.05, by using SPSS software version 24. Results: ECSSA in CB had the highest value Ra (97± 60.1), followed by epoxy wire in steel brackets Ra (96.1 ± 52.9), followed by epoxy wire as received Ra (79 ± 60.1), followed by steel wire in ceramic bracket Ra (50.6 ± 24.3), followed by steel wire in steel bracket Ra (44.7 ± 23.4), the lowest values shown in steel wire as received Ra (28.2±13.3). One-way ANOVA showed a significant difference between the tested groups (P=value: 0.05). Duncan’s test demonstrated significant differences among groups. Conclusion: Epoxy-coated SS arch wire combined with ceramic bracket shows the highest roughness properties, while SS archwire combined with SS bracket and SS as received shows the lowest roughness properties.

The purpose of the current study is to compare the impact of three different treatment approaches on the surface microhardness of the enamel of third molar teeth. Materials and Methods: An in vitro study was done on fifty extracted impacted third molars. All samples were immersed in solutions of pH cycle for 10 days (demineralizing solution for 3 hours, remineralizing solution for 20 hours, and artificial saliva for 30 minutes twice daily). Then the samples were divided randomly into 5 groups according to enamel surface treatment, group1: Colgate (containing Arginine) toothpaste, group2: GC (containing Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-tooth mousse, group 3: Sensodyne (containing NovaMin) toothpaste group 4: distilled water and group 5: pH cycle solutions. The microhardness numbers were calculated from the length of the indentation on the enamel surface, the indentation length was determined microscopically with 70X magnification. An ANOVA was constructed (value P ≤ 0.05) followed by Duncan's post -hoc test for comparisons of mean values. Results: there were significant differences among the study groups with respect to Vickers microhardness (VMH) mean values of samples. The lowest value was for the control group after the pH cycle followed by the Colgate (containing Arginine) group and the highest value was for the control group before the pH cycle followed by the Sensodyne (containing NovaMin) group. Conclusions: Sensodyne (containing NovaMin) toothpaste is more effective in restoring the hardness of artificial WSLs when compared with GC (containing CPP-ACP) and Colgate (containing Arginine) toothpaste .

Aims: exposed pulp can be managed by Mineral trioxide aggregate (MTA) that stimulates reparative dentin deposition at the site of exposure. The study aims to evaluate the healing of exposed pulp immunohistochemically by using hyaluronic acid (HA) with MTA by evaluating collagen III expression rate. Materials and method: Ninety teeth were used from 10 dogs to perform an experimental pulp exposure. The samples were divided into three groups according to the mixing medium with MTA: group I: MTA + distilled water (control group), group II: MTA + hybrid cooperative complex hyaluronic acid (HCC-HA), group III: MTA + high molecular weight hyaluronic acid (HMW-HA). After pulp capping, all cavities were restored with glass ionomer restoration. The dogs were divided randomly into five groups (2 dogs each) according to the evaluation periods (7,14,21,30,60) days. At the end of the study, the dogs were euthanized and the sampled teeth were processed for immunohistochemical investigation to evaluate collagen III expression rate by Kruskal-Wallis Test using Pairwise Multiple Comparison Tukey Test with significant level set on P ≤ 0.05. Results: Both types of hyaluronic acid (HCC-HA, HMW-HA) showed a statistically higher expression rate of collagen III than using distilled water with MTA. Conclusions: within the limitations of this study, using HA for mixing with MTA increased collagen III expression, which can be explained as an increase in the healing process. HA could be an effective water substitute for mixing with MTA for direct pulp capping.

Aims: To estimate the effects of plant oil (coconut oil and/or rosemary oil) in two concentrations on the hardness and roughness of cold-cured acrylic resin. Materials and Methods: 50 samples each measuring 30 mm in diameter and 3 mm in thickness were made from cold-cured acrylic resin. Forty samples were made with the addition of rosemary and coconut oils at concentrations of 1.5% and 2.5%, respectively, while ten samples were made without any oils (the control). Each oil concentration is represented by those ten samples. A profilometer was used to measure the surface roughness (µm) and shore D hardness for each group. One-way analysis of variance (ANOVA) and the LSD test were both used to analyze the results. A level of P≤0.05 was regarded as significant. Results: Adding rosemary at concentrations of 1.5% and 2.5% would increase the value of Shore D hardness, causing an enormous variance from the control (P≤0.05). However, the addition of coconut oil considerably decreased the shore D hardness in comparison to the control group. Apart from the 2.5% coconut oil, which resulted in an extremely significant rise in surface roughness from the control and other experimental groups, the results revealed no noticeable difference in surface roughness between the control group and experimental groups. Conclusions: The hardness of cold-cured acrylic resin was increased when adding rosemary oil in concentrations of 1.5% and 2.5%, with 1.5% rosemary achieving the best findings. However, there was no effect on surface roughness when adding rosemary and coconut oil, excluding the concentration of 2.5% coconut oil, which had an adverse impact on the surface roughness of cold-cured acrylic resin.

Aims: This in vitro investigation was used to evaluate and compare the bioactivity of several restorative materials ( Cention® Forte, Tetric PowerFill bulk fill, and evereX Posterior™ ). Materials and Methods: Disc-shaped specimens of 10 mm in diameter and 2 mm in thickness were made for Cention® Forte, Tetric PowerFill bulk fill, and EvereX Posterior™ in order to evaluate their bioactivity. The manufacturer's instructions were followed while handling the materials. Dental floss was used to suspend the samples in plastic containers that were filled up to 25 milliliters with phosphate-buffered saline (PBS) for 28 days, the pH was 7.4 at 37°C, and the solution was changed every three days. The samples underwent cleaning, drying, and analysis using a Field Emission Scanning Electron Microscope (FESEM)/ Energy Dispersive X-ray (EDX) . Results: Hydroxy apatite crystals precipitated as nano-spherical needle-like shapes on the surface of Cention® Forte. The Ca\P ratios of Tetric PowerFill bulk fill and evereX Posterior™ were (0.69) and (0.71), respectively, whereas Cention® Forte had a Ca\P ratio of 1.86, which was more than the normal Ca\P ratio of dentin which is 1.67. Conclusions: Over 28 days in phosphate-buffer saline, Cention® Forte exhibited the ability of HA precipitation on its surface with a Ca/P ratio comparable to that of natural HA.

Aims: To investigate the effects of the incorporation of hydroxyapatite nanoparticles (HA NPs) with size (20 nm) at two concentrations (0.5% and 1%) on the water sorption and water solubility of heat-cured acrylic resin. Materials and methods: The total number of specimens was thirty which was divided into ten specimens (control, 0.5 % HA NPs, and 1 % HA NPs). The statistical analysis was done by using the SPSS program including descriptive statistics, ANOVA, and Duncan's test at p ≤ 0.05. Results: The results demonstrated that there was a significant decrease in the water solubility and a nonsignificant decrease in water sorption for the PMMA-HA nanocomposite at HA nanoparticles (0.5%) and (1%), when compared to control. Conclusions: the use of hydroxyapatite nanoparticles as dental fillers at 0.5% and 1% by weight decreased the water sorption and water solubility of PMMA denture base material.