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Purpose:The purpose of this study was to assess the cytotoxic effect of different concentrations of Chitosan Nanoparticles (CNPs) and Propolis Nanoparticles (PNPs) on periodontal ligament stem cells using MTT assay. Materials and Methods:Immature, impacted third molars were used to isolate stem cells. Cells were seeded in 96-well culture plates. Groups were divided into six experimental groups: Group I: 17% EDTA, Group II: 1% propolis NPs, Group III: 2% propolis NPs, Group IV: 1% chitosan NPs, Group V: 2% chitosan NPs, Group VI: cultured cells not receive any material. Cytotoxic effect of these materials on stem cells was evaluated using MTT assay at 24, 72,120 hours and 14 days. Results: In all assay intervals; 2%CNPs group showed the statistically significant highest median value and control group showed the statistically significant lowest median values. After 24 and 72 hours; there was no statistically significant difference between 2% PNPs and 1% CNPs groups followed by 1% PNPs group. Both EDTA and control groups; showed the statistically significantly lowest median values with no statistically significant difference between them. After 120 hours; there was no statistically significant difference between 2% PNPs and 1% CNPs groups in median value followed by 1% PNPs then EDTA groups. After 14 days; there was no statistically significant difference between 1% PNPs, 2% PNPs and 1% CNPs groups in median value followed by EDTA group. Conclusion: The ability of 2% Chitosan NPs to promote periodontal ligament stem cell viability makes them a promising irrigating solution. The cell viability of 2% Propolis NPs was comparable to that of 1% Chitosan NPs, which was better than EDTA.

Purpose:The purpose of this study was to evaluate the effect of diode laser-980nm on microhardness of young and old canal dentin after treatment with NaOCl, NaOCl/ EDTA and distilled water solutions. Material and Methods Forty-eight single rooted premolars were divided into three groups according to the chemical solutions used (16 each) (8 for young teeth <30 years old and 8 for old teeth >50 years old). Group I: irrigated with 5ml of 2.6% NaOCl activated with diode laser, group II: irrigated with 5ml of 2.6% NaOCl without laser activation followed by 5ml of 17% EDTA activated with diode laser and group III: irrigated with 5ml of distilled water activated with diode laser. Then microhardness was evaluated at coronal, middle, and apical thirds of each root canal. Results: In all young and old groups, the coronal third had the highest mean value, followed by the middle, and the apical third had the lowest mean value, with a statistically significant difference between thirds of the groups (p0.001<). There was a statistically significant difference between young and old teeth at all levels (coronal, middle, and apical) for each group (I, II, and III), with old teeth having a greater mean microhardness value than young teeth. Conclusion: Irradiation of NaOCl/EDTA solutions with 980-nm diode caused reduction in microhardness of young dentin more than old dentin, and NaOCl only or distilled water in all thirds of groups.

Statement of the problem For permanent molars in young age, which treatment planning guarantees better performance of such weakened teeth should be followed starting from the endodontic therapy till the final coronal restoration? Purpose The aim was to evaluate the performance of endocrowns as permanent restorations for endodontically treated molars (ETMs) in young age in a 2-year period. Materials and methods Inclusion and exclusion criteria were established. Ten patients of 9–12 years old were selected at random, in accordance with Research Ethics Committee (REC) of Faculty of Dental Medicine for Girls, Al-Azhar University and in conjunction with Departments of Pedodontics, Endodontics, and Crowns and Bridges. For endodontic treatment, Protaper Next system and iRoot SP sealer were used. According to the coronal restoration type, the patients were divided into two groups. Group 1: the patient received direct composite resin restorations, and Group 2: the patient received endocrown restorations. Due to the small sample size, statistical descriptive methods were applied. Results After 2-year follow up, all endocrowns were in function while two composite restorations failed. Conclusions In young age, ETMs restored with Protaper Next system, iRoot SP sealer, and IPS e.max CAD endocrowns have excellent clinical performance. Clinical significance In young age, whenever indicated, endocrowns are highly recommended for ETMs as permanent, esthetic and conservative type of restorations.

Objective: was to investigate the effect of 0.2% chitosan, 0.2% nano chitosan, and 5% apple vinegar compared to 17% EDTA on intraradicular dentin surface roughness. Materials and Methods: Twenty single-rooted human teeth were used in this study, after decoronation, working length determination, and mechanical preparation using ProTaper Next rotary files with irrigation after each file using 5ml of 2.6% NaOCl. The specimens were randomly divided into four groups according to the final irrigating solution. Group I used 17%EDTA, group II with 0.2% chitosan, group III with 0.2% nano-chitosan, and group IV with 5% apple vinegar. Specimens were sectioned longitudinally and evaluated for surface roughness changes using Environmental Scanning Electron Microscope (ESEM) and a photomicrograph was analyzed using a 3D software system. Results: The highest mean value of surface roughness was recorded in group IV treated with 5% apple vinegar with a statistically significant difference from the other groups (P value< 0.05). The lowest mean value was observed in group III used 0.2% nano-chitosan followed by group II irrigated with 0.2% chitosan which was lower than the control group I used 17% EDTA with statistically significant difference between the three groups (P value< 0.05). Conclusion: 0.2% nano-chitosan as the final irrigating solution had minimal drawbacks on dentin micro-structures by producing a slight change of surface roughness.