Purpose: This study was carried out to evaluate the effect of biostimulation on the regenerative response of immature teeth with necrotic pulp and apical periodontitis in dogs. Materials and Methods: Seventy-two root canals were employed in the present study as follows: Sixty root canals for experimental groups and twelve as positive and negative controls. After the induction of pulp necrosis and apical periodontitis, roots were divided into two groups, group I: Regenerative Endodontic Therapy (RET) with subsequent biostimulation (seven sessions at 808 nm diode laser at output power of 300 mW for 90 seconds) and group II: RET without biostimulation. The groups were followed up for 1, 2 and 3 months (subgroups A, B&C). The maturation of the roots was assessed both radiographically and histologically. All data were statistically analyzed.Results: the application of biostimulation in group I demonstrated marked increase in root length, thickness and decrease in apical diameter compared to group II however, it was statistically significant only in subgroup C (12.43% versus 7.66%, 33.09% versus 17.81% and 38.12% versus 23.35 % at third month) respectively (p<0.05). Furthermore, it showed histologically the highest score of vital tissue infiltration and least inflammatory scores which was statistically significant. Conclusion: Biostimulation enhanced the response of immature teeth with necrotic pulp and apical periodontitis to regenerative endodontic therapy improving root maturation.

Purpose: To evaluate the impact of 10% Boswellia sacra water extract (B. sacra) as a final irrigant on smear layer removal consequent to primary irrigation with 2.6% sodium hypochlorite (NaOCl). Material and Methods: Thirty-six palatal &distal roots from extracted maxillary & mandibular molars have being instrumented and categorized into 3 experimental groups depending on the final irrigant used: (12 samples each), Group I: irrigated with 10% B. sacra extract. Group II: irrigated with 17% EDTA. Group III: control group irrigated with sterile saline. Irrigation was performed with 5ml of test substances for 1 minute. Scanning electron microscopic analysis was performed to assess smear layer removal on the coronal, middle, and apical portion for each root canal. Results: no statistically significant difference between using 10% B. sacra extract & 17% EDTA for smear layer removal at the entire root canal levels (P=0.000). However, there was statistically significant difference between tested irrigant (10% B. sacra extract & 17% EDTA) compared to control group. Comparison of the capability to remove smear layer among different root canal levels for each group showed a significant difference in smear layer removal on coronal and apical part for all assessed groups. Conclusion: The current in-vitro study demonstrated that 10% B. sacra water extract have a chelating potential similar to that of EDTA 17%. Boswellia sacra as natural product is a promising chelating agent.

Purpose: to reveal the effect of different concentrations of prepared calcium hydroxide pastes (70%, 50%, and 30%) used in regenerative endodontic on microhardness and fracture resistance of radicular dentin. Material and methods: Different concentrations of calcium hydroxide (Ca(OH)2) were prepared with measured pH, then forty eight single rooted teeth were prepared and randomized into three groups according to Ca(OH)2 paste concentrations (12 samples each) and 12 samples were availed as control group. Group I: root canal contained 30% Ca(OH)2 paste. Group II: root canal contained 50% Ca(OH)2 paste. Group III: root canal contained 70% Ca(OH)2 paste. Samples were stored at 37 0C with 100% humidity for four weeks for subsequent microhardness and fracture resistance tests. Results: There was a statistically significant reduction of microhardness  and fracture resistance between test groups and control group (P≤ 0.05), group III showed a  significant reduction  in both microhardness and fracture resistance compared to group I. However, there was no significant difference in pH between different concentration of Ca(OH)2. Conclusion: Increasing concentration of Ca(OH)2 paste can negatively affect microhardness and fracture resistance of radicular dentin in revascularization procedure.

Purpose: This study evaluated the effectiveness of using EndoVac irrigation device on microbial reduction and postoperative pain in single rooted teeth with necrotic teeth and apical periodontitis after single visit treatment. Subjects and Methods: Thirty six single rooted teeth from patients of age range between 20 and 50 years old were involved in this study. According to irrigation procedures, patients were assigned randomly and equally into two groups of 18 teeth per group. Group I (conventional irrigation) and Group II (EndoVac irrigation). Irrigating solution for both groups was 2.5% sodium hypochlorite. All patients were treated in a single visit. The access cavity was prepared, and a microbiological sample (S1) was obtained. The root canal was chemomechanically prepared with ProTaper rotary instruments up to #F4. Finally, after irrigation activation, the second microbiological sample (S2) was collected. Samples were cultured on plates of nutrient agar, incubated for one day at thirty seven °C, and colony forming units (CFU) were counted and recorded. The primary outcome assessed microbial reduction in both groups. The pain was measured using a Numeric rating Scale (NRS) at 6, 12, 24, and 72 hours to determine the secondary outcome. Results: The mean percentage reduction in microbial count in Group II was statistically significantly higher than in Group I (P ≤ 0.05). Conventional group (G I) showed statistically significantly higher pain scores than EndoVac group (G II) (P ≤ 0.05). Conclusion: In necrotic teeth with apical periodontitis, EndoVac could be utilized as an adjunct to conventional root canal irrigation.