Immature permanent teeth with necrotic pulp and peri-apical tissues constitute a challenging endodontic problem due to difficult root canal debridement and obturation as well as high risk of tooth fracture. The conventional treatment of such cases is apexification by calcium hydroxide, which results in acceptable endodontic outcomes. Apexification has several disadvantages such as multiple visits and alteration of the mechanical properties of dentin. 1

Purpose: This study aimed to evaluate the efficacy of Chitosan as root canal irrigant with Endovac irrigation system in removing smear layer of curved root canal walls using Scanning Electron Microscope (SEM). Materials and Methods: Fifty extracted human first mandibular molars were selected with curved mesiobuccal root (20º-35º). Samples were instrumented with Universal ProTaper rotary files till size F4 then divided into 2 main experimental groups according to the final rinse used; Group I: irrigated with 17 % EDTA Group II: irrigated with 0.2% chitosan acetate and control group, irrigated with sterile saline (10 samples). Each group was further subdivided into 2 subgroups according to the irrigating technique used; Subgroup A: using conventional needle irrigation and Subgroup B: using Endovac irrigation system. Samples were grooved longitudinally and smear layer was evaluated using SEM at the coronal, middle and apical root canal levels. The significance level was set at P≤ 0.05. Results: There was a statistically significant difference among the tested groups and the control group in the mean scores of smear layer at all root canal levels and no significant difference between irrigants used. Concerning the irrigating devices, there was no statistical significant difference between conventional irrigation and Endovac system at the coronal and apical root canal levels while at the middle level, 0.2% chitosan showed statistical significant difference with Endovac system subgroup than conventional irrigation (P ≤ 0.05). Conclusion Endovac irrigation system was effective in smear layer removal from curved root canals using either 0.2% Chitosan acetate or 17 % EDTA as final rinse.

Purpose Assessment of the surface roughness of root canal and its correlation with Resin Sealer Bond Strength following final irrigation by apple vinegar. Material and methods 50 extracted lower premolars were selected and prepared using Universal ProTaper rotary files and 14 ml 2.6% NaOCL then the samples were equally distributed into 2 main groups (20 samples each) depending on the type of the final rinse. Group I: Apple vinegar (AV), Group II: 17 % Ethylenediamine tetra acetic acid (EDTA), Control group (10 samples): sterile saline. Each main group was further equally distributed into 2subgroups (10 samples each). Subgroup A: For surface roughness evaluation. Subgroup B: For push out bond strength evaluation. Surface roughness was evaluated using digital microscope. The push out bond strength test was carried on using universal testing machine. The sealer penetration inside the dentinal tubules was seen under scanning electron microscope (SEM) in selected samples. Results Regarding the results of subgroup A, at all levels, the highest value of the average roughness deviation (Ra) was recorded in samples treated with 17% EDTA, while the lowest value was recorded with the saline group and there was no statistical significant difference among the tested groups. Regarding the results of subgroup B, at all levels, the highest median push out bond strength was recorded in samples treated with 17% EDTA, while the lowest value was recorded with the saline group and there was no statistical significant difference among the tested groups except at the apical levels where the difference statistically significant among the tested groups. SEM observation of sealer/ dentin interface revealed few traces of sealer penetration with samples treated with 17% EDTA and AV. Conclusion EDTA 17% as a final rinse produced higher value of surface roughness compared to AV. The push out bond strength results of AV was comparable to that of 17%EDTA when applicated as a final rinse. There is a linear relation between Ra and the push out bond strength of resin sealer in Groups I, II.

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Purpose: This study aimed to evaluate the treatment outcome after using diode laser disinfection of root canals in necrotic teeth with periapical radiolucency. Subjects and Methods: Thirty patients of age range between 20 and 50 years old were involved in this study. They were divided randomly into two groups (15 teeth each). Group I:Access cavity preparation was performed and microbiological sample (SI1) was taken.The root canal was prepared using ProTaper rotary instruments up to #F4 and irrigated with 2ml of 2.6% sodium hypochlorite, this was repeated after each instrument use with total volume 14ml. Smear layer removal with 17% EDTA (5ml) was performed, saline solution (5ml) was used as a final irrigant then, the canal was irradiated with 810 nm diode laser in a continuous wave mode with a power of 1.5 w then, microbiological sample (SI2) was taken. Group II: The same steps were followed as in group I up to the use of saline solution (5ml) as a final irrigant, then microbiological sample (SII2) was taken. The treatment outcome was evaluated clinically (pain recording using Visual Analogue Scale (VAS) at 6,12,24,48 and 72hours) and microbiologically (reduction in number of CFU of microorganisms). Results: There was no statistically significant difference between pain scores in the two groups. Group I showed statistically significant higher mean percentage reduction in bacterial and fungal counts than group II. Conclusion: 810 nm diode laser can be used as an adjunct to conventional root canal treatment in necrotic teeth with periapical radiolucency.