Effect of sodium hypochlorite temperature and concentration on the fracture resistance of root dentin.

BACKGROUND: Sodium hypochlorite (NaOCl) is the most efficient root canal irrigant to date. The aim of this study was to compare the effect of NaOCl used at different temperatures and concentrations on the compressive strength of root dentin. MATERIALS AND METHODS: Seventy-two extracted human single-canaled straight roots of comparable size and length were selected and randomly divided into six groups (n = 12): Group (A) served as a control with unprepared canals. The other groups were instrumented with rotary ProTaper Universal files up to size F3. Group (B) was irrigated with 1% NaOCl at room temperature, Group (C) with 1% NaOCl heated to 70 °C, Group (D) with 5.25% NaOCl at room temperature, and Group (E) with 5.25% NaOCl heated to 70 °C. Saline was used in Group (F). The roots were sectioned into 2-mm-thick disks that underwent compression testing using a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests. The significance level was set at p ≤ 0.05. RESULTS: A total of 255 disks were tested. The control group showed the highest compressive strength (p = 0.0112). However, this did not differ significantly from that of heated (p = 0.259) or unheated (p = 0.548) 1% NaOCl. There were no statistically significant differences between the groups of instrumented teeth. CONCLUSION: Within the conditions of this study, irrigation with NaOCl at different concentrations and temperatures during root canal preparation did not affect the compressive strength of root dentin. CLINICAL RELEVANCE: This study demonstrates that the use of NaOCl as a root canal irrigant is not associated with a clinically relevant decrease in root compressive strength, especially when compared to saline.

Undergraduate Endodontic Training and Its Relation to Contemporary Practice: Multicenter Cross-Sectional Study in Saudi Arabia.

Materials and Methods: An online questionnaire was developed and emailed to all dental schools in Saudi Arabia. This questionnaire was answered by the endodontic undergraduate program director. The data collected were analysed using descriptive statistics. Results: The response rate was 96.15%, which means twenty-five out of twenty-six dental schools participated in the study. The majority of the academic supervisors was endodontists (92%). The use of magnification and ultrasonic tips was not required by 84% and 76% of the dental schools, respectively. The main endodontic treatment techniques were the step-back technique and gates glidden for cleaning and shaping (76%) and cold lateral compaction for obturation (92%). Conclusions: The dental students were supervised by endodontic specialists and trained to use traditional endodontic methods. Encouraging dental educators to train students to use modern technology and equipment would probably improve their graduate clinical skills and performance.

The objectives and instructional design of undergraduate endodontic program: multicenter cross-sectional study in Saudi Arabia.

BACKGROUND: Identify the objectives and the instructional design of undergraduate endodontics in dental schools in Saudi Arabia. METHODS: The online questionnaire was developed from an original survey conducted in the United Kingdom. The questionnaire was modified for purpose of the study and the region of interest. Then it was directed and emailed to the undergraduate endodontic program directors in twenty-six dental schools in Saudi Arabia. The results were analyzed using descriptive statistics and the Chi-square and Fisher's exact tests. RESULTS: The response rate was 96.15%. The number of credit hours for preclinical endodontic courses was up to four credit hours (84%). Students were clinically trained to do vital pulp therapies (92%), root canal treatment (100%), and root canal retreatment (68%). The majority of dental schools define the minimum clinical requirements (92%). Practical and clinical competency exams were used to evaluate students' performance (92% and 84% respectively). The students were trained to treat cases of minimal (52%) to moderate complexity (48%). Endodontic treatment consent and difficulty assessment form were used by 32% and 60% of dental schools respectively. There was no significant difference in the instructional design between public and private dental schools (P > 0.05). CONCLUSION: The endodontic undergraduate objectives were to graduate competent clinicians who acquired basic science of endodontics and who know their limitations as it is necessary for a safe general dental practice. The use of endodontic treatment consent and case difficulty assessment should be wisely considered in clinical training.

Effect of dental trauma management resources on dental practitioners' confidence and knowledge: A pilot cross-sectional study.

BACKGROUND/AIM: The knowledge of standardized care guidelines is critical to the confidence of practitioners in managing dental trauma. Therefore, the aim of this study was to assess the awareness, use and impact of the International Association of Dental Traumatology guidelines, and the online Dental Trauma Guide on general dental practitioners' self-reported confidence and knowledge in managing traumatic dental injuries in the primary and permanent dentitions. MATERIALS AND METHODS: A cross-sectional, pre-piloted, 27-item self-administered questionnaire survey was distributed electronically to general dental practitioners' working within five member states of the Gulf Cooperation Council countries (Kingdom of Bahrain, Kingdom of Saudi Arabia, Kuwait, Oman, and Qatar) between September and December 2020. Data were collected and analysed using descriptive statistics and Wilcoxon Signed Rank test analysis for relevant comparisons. RESULTS: A total of 294 respondents completed the survey, with the majority being from the Kingdom of Saudi Arabia (47.4%) and Qatar (27.3%). A lack of evidence-based knowledge in managing traumatic dental injuries was evident among more than half of the respondents. Respondents who were cognizant of the recent International Association of Dental Traumatology guidelines (2020) and those who use the Dental Trauma Guide routinely demonstrated a higher self-reported confidence level in managing both simple and complex primary dentition trauma, as well as simple traumatic dental injuries in the permanent dentition (p < .05). CONCLUSION: This survey highlights critical deficiencies in the knowledge of a large number of the respondents in the management of dental trauma which is likely to cause irreversible long-term patient effects.

Efficiency of Using Different Greater Taper Gutta-Percha Cones in Continuous Warm Vertical Condensation: An Ex Vivo Study.

AIM: The aim of this ex vivo randomized study is to evaluate the efficiency of gutta-percha cones that match a nickel-titanium instrumentation system and nonmatching greater taper cones, when used with continuous warm vertical condensation technique. MATERIAL AND METHODS: Thirty-six straight canals were prepared using ProTaper Next files, and the apical third was obturated using either ProTaperNext cones (group A), ISO uniform greater taper cones (group B), or nonstandardized cones (group C). Cone adaptation time was quantified by the number of required modifications. Micro-computed tomography was used to measure voids and sealer percentage. RESULTS: There was no significant difference between the groups regarding void volume (p = 0.666), percentage (p = 0.379), and the number of modifications (p = 0.757). Sealer percentage, however, was significantly lower in group B when compared to group A (p = 0.0194). CONCLUSION: In straight canals, matching gutta-percha cones were not associated with significantly better obturation or saving time to fit the cone. CLINICAL SIGNIFICANCE: Using gutta-percha cones that do not match a nickel-titanium instrumentation system to obturate the straight canals with continuous warm vertical condensation technique is as efficient as using matching cones in terms of obturation quality and ease of cone fit.

The association between root canal filling and treatment outcome.

The aim of the study was to evaluate the technical quality of endodontic treatment per- formed by postgraduate students in Karolinska Institutet, Stockholm, Sweden during the years (2008-2011) and to evaluate the treatment outcome. In addition, possible influencing factors to treatment outcome were analyzed. All maxillary first molars that received endo- dontic treatment between 2008 and 2011 were included in the study. Pre, post and follow up radiographs were collected.The apical status (PAI-score),the quality of the root canal treat- ment (RCT) and the treatment outcome were assessed. Analysis of the treatment outcome in relation to the quality of root canal treatment and other possible influencing variables was performed by Chi2 or Fisher's Exact test, and the statistical significance was set at P<0.05. A total of 73 teeth were included in the study. Out of these, sixty-three teeth (86,3 %) had periapical lesions at the time for RCT. An initial root canal treatment was performed in 46 teeth (63 %) and 27 teeth (37 %) were retreated.There was no significant as- sociation between the outcome and the type of treatment.The majority of the RCT's (58 %) had good seal and correct length. In total, the treatment outcome was successful in 59 (81 %) of the cases. The success rate was 88% in cases with high quality root fillings, compared to 71% in cases with less good quality.There was a non- significant trend (P =0.066) of an association between RCT quality and treatment outcome. In conclusion the association between the quality of the root filling and the treatment outcome was not verified with statistical significance, but the results indicate a trend that satisfactory root fillings are associated with a favorable outcome.This study was limited by its retrospective nature and a relatively small sample size.

Effect of Active Oxygen Fluid (Blue®m) as a Root Canal Irrigant Against Enterococcus Faecalis.

PURPOSE: To evaluate the antimicrobial effect of a new active oxygen fluid (Blue®m) as a root canal irrigant against Enterococcus faecalis compared to sodium hypochlorite (NaOCl). MATERIAL AND METHODS: Forty-five extracted single-canaled human teeth were selected, received root canal preparation, autoclaved, and contaminated with Enterococcus faecalis. The specimens were randomly allocated into three groups: Group (A) served as the negative control, receiving irrigation with saline (n = 15); Group (B) was irrigated with 5.25% NaOCl (n = 15); and Group (C) was irrigated with 10 mL of Blue®m (n = 15). Microbial sampling from the root canals was performed before and after irrigation. The difference between the pre-irrigation and post-irrigation colony-forming units (CFU/mL) was calculated. The data was analysed using a one-way ANOVA followed by post-hoc Tukey tests. The significance level was set at 5%. RESULTS: Blue®m statistically significantly reduced the bacterial load compared to saline (p = 0.009), but NaOCl was most effective, outperforming both (p 0.0001). CONCLUSION: Irrigation with Blue®m demonstrated antibacterial efficacy against Enterococcus faecalis, but it was not as effective as NaOCl.

Comparative Accuracy and Reliability of Three Electronic Apex Locators in Determining the Apical Constriction of Molar Canals: A Micro-CT Evaluation.

Background: Determining the correct apical limit for root canal treatment is essential for its success. This study evaluates the accuracy of three electronic apex locators (EALs) in locating the apical constriction (AC) in molar canals. Methods: Forty extracted human mandibular molars were scanned using micro-CT, and endodontic access cavities were created. Teeth were mounted in alginate, and three EALs-Root ZX-mini, Root ZX-II, and Sirona integrated apex locator-were used to measure the canal working length in dry canals and with EDTA gel. Micro-CT scans were performed with files in place, and the distance from the AC was calculated. Measurements within 0.1-0.5 mm were categorized as 'close'. Those extending beyond towards the major foramen were categorized as 'beyond', otherwise they were classified as 'far'. Data analysis was conducted with a level of significance set at 5%. Results: Most readings for all EALs were in the 'close' category, with significant differences between devices (p < 0.0001). Root ZX-mini and Root ZX-II had 74.4% and 72.5% 'close' readings, respectively, versus 51% for Sirona integrated. Accuracy did not differ significantly between dry and EDTA-treated canals (p = 0.306). All EALs demonstrated excellent operator reliability (ICC 0.996-1.00). Conclusions: All EALs accurately determined AC, unaffected by lubricants. However, Root ZX-mini and Root ZX-II outperformed Sirona integrated. All EALs showed consistent reliability.

Effect of bioceramic intracanal medication on the dentinal bond strength of bioceramic cements: an ex-vivo study.

Background: The present study evaluated the effect of a bioceramic intracanal medicament (Bio-C Temp) on the push-out bond strength of bioceramic cements. Methods: Forty-eight human single-canaled premolars were prepared and randomly divided into three groups: Group (A) received no intracanal medicament; Group (B) calcium hydroxide (CH); and Group (C) Bio-C Temp. After medicament removal, the roots were sectioned transversely. The slices in each group were separated into two subgroups (n = 16): in Subgroup (1), mineral trioxide aggregate (MTA) was placed, and in Subgroup (2) Bio-C Repair. Push-out bond strength was determined using a universal testing machine, applying a constant compressive force on the cement until bond failure. The failure mode was also evaluated. Data were analyzed using the Chi-square test and two-way ANOVA followed by Tukey's post hoc tests. The level of significance was set at 5%. Results: The pushout bond strength of Bio-C Repair was significantly higher than that of MTA irrespective of intracanal medication (p = 0.005). The placement of Bio-C Temp was associated with significantly lower bond strength (p = 0.002, p = 0.001). Conclusion: Bio-C Repair showed better bond strength compared to MTA, irrespective of intracanal medication. Bio-C Temp intracanal medicament, however, decreased the bond strength of both these cements.

Efficacy of various techniques in calcium silicate-based intracanal medicament removal: a micro-CT analysis.

The purpose of this study was to evaluate the efficacy of different techniques in removing calcium silicate intracanal medicament (Bio-C Temp). Forty human single-canaled premolars were randomly distributed into five groups (n = 8). All root canals were instrumented, then filled with Bio-C Temp. Following 1-week incubation, the intra-canal medicament was removed using one of five techniques according to tooth group: conventional syringe irrigation, Endo Activator, passive ultrasonic irrigation (PUI), ProTaper Universal F3 and XP-endo Finisher (XPF). Micro-CT scanning was performed before and after removal of Bio-C Temp. All techniques significantly reduced the volume of Bio-C Temp (p < 0.001) without reaching complete elimination. The percentage of Bio-C Temp removed was significantly higher in the XPF group (98.2%) compared to conventional syringe irrigation (70.6%), the Endo Activator (75.7%), and the ProTaper Universal (76.6%). There was no significant difference between the XPF and PUI (95.1%) groups. None of the removal techniques were able to completely remove Bio-C Temp from the root canal. However, XPF was the most effective method, but was not statistically significant when compared to PUI. Clinical Relevance: This study demonstrated that both XPF and PUI outperform conventional irrigation in removing Bio-C Temp intracanal medicament.

Cyclic fatigue resistance of EdgeTaper Platinum, Protaper Gold, and TruNatomy Prime rotary files before and after autoclave sterilization.

Background: This in vitro investigation aimed to determine the influence of multiple autoclave cycles on the cyclic fatigue resistance of three heat-treated nickel-titanium (NiTi) files: EdgeTaper Platinum (ETP), ProTaper Gold (PTG), and TruNatomy Prime (TN). Materials: Sixty NiTi files, twenty of each NiTi file type: ETP 25/.06, PTG 25/.08, and TN 26/.04 were randomly divided into four equal subgroups (n = 5). The files for the control group were left un-autoclaved. Different autoclave sterilization cycles (one, five, and ten) were used for the other three groups. The files were then placed in a metal canal block and rotated according to the manufacturer's instructions until fracture. The length of the broken segment and the time taken for fracture were measured. The fractured surfaces were subsequently subjected to SEM imaging. The Kruskal-Wallis test was used to analyze the data, followed by Dunn-Bonferroni pairwise comparisons. Statistical significance was set at p < 0.05. Results: ETP showed significantly greater resistance to cyclic fatigue than TN in all autoclave groups and PTG after five autoclave cycles (p = 0.014). Fatigue resistance was not affected by the number of autoclaving cycles, except for ETP. After the first and tenth autoclaving cycles, they required significantly more rotations to failure than the non-sterilized files (p = 0.039 and p = 0.021, respectively). The fractured segments of the ETP files in these two groups were also longer than those in the control group (p = 0.010). Conclusion: The cyclic fatigue resistance of ETP was greater than that of TN in all tested conditions. Repeated autoclave cycles of sterilization improved the cyclic fatigue resistance of the ETP files only and did not affect the cyclic fatigue resistance of TN and PTG. However, the ETP files separated at a longer distance from the tip with increased autoclaving cycles.

Assessment of the effect of spacer material on gap and void formation in an endodontic temporary restoration using micro-computed tomography.

This study aimed to evaluate the effect of two spacer materials (cotton pellet and polytetrafluoroethylene [PTFE]) on gap and void formation in the Cavit restoration used for endodontic temporization. Thirty-four extracted human single-rooted premolars were matched and allocated into two groups (n = 17/group) according to the access cavity spacer (cotton pellet or PTFE). Standardized endodontic access cavities were prepared in all the teeth. Subsequently, the teeth were scanned by micro-computed tomography (micro-CT) to determine the volume of the access cavities. The teeth were then temporized by placing either cotton pellet or PTFE as spacer materials on the canal orifices, followed by the Cavit restoration. Following the temporization procedure, the teeth were subjected to a second micro-CT scan to determine the percentage volume of gaps and voids along the margins and within the Cavit restoration, respectively. Statistical analysis was performed using the Shapiro-Wilk and Wilcoxon signed-rank tests with a 5% significance level. The PTFE spacer was associated with significantly less gap formation between the Cavit restoration and the access cavity walls (P < 0.05) compared with the cotton pellet. No difference existed in void formation between the groups (P > 0.05). These findings indicate that the spacer material placed under the Cavit restoration can influence the quality of overlying restoration. PTFE was associated with less gap formation and, therefore, performed better than the cotton pellet as a spacer material beneath the Cavit restoration during endodontic treatment.

Application of advanced platelet-rich fibrin for through-and-through bony defect during endodontic surgery: Three case reports and review of the literature.

BACKGROUND: The use of advanced platelet-rich fibrin (A-PRF) membranes for guided bone and tissue regeneration in through-and-through defects after endodontic surgery was explored in three cases. CASE SUMMARY: Herein, three patients presented to the endodontic clinic suffering from apical periodontitis, associated with large bone resorption and related to previously endodontically treated teeth. Periapical surgery was indicated in these cases and the osteotomy site was covered by A-PRF membrane. Cone-beam computed tomography (CBCT) was used to assess the cases before and after the surgery. CONCLUSION: Four months post-surgery, the recall CBCT scan showed complete obliteration of the osteotomy with newly formed bone. A-PRF membrane showed promising results and was an advantageous addition to surgical endodontic treatment.

Efficiency of diode laser and ultrasonic-activated irrigation in retreatment of gutta percha and bioceramic sealer: An in vitro study.

This study was to determine the effectiveness of diode laser (LI) and ultrasonic (UI)-activated irrigation with or without a surfactant as adjunct techniques during the retreatment of gutta-percha and tricalcium silicate-based sealer (BC) sealer. Forty-two single-rooted premolars were instrumented and filled with gutta-percha and BC sealer, then retreated using NiTi retreatment rotary files. Teeth were randomly divided into three equal groups: Control (manual irrigation), UI and LI groups. Each group was subdivided into 2.5% NaOCl irrigant and ChlorCid™ï¸ Surf subgroups. The amount of material removed following UI and LI was significantly greater than that of manual irrigation (p < 0.0001). However, there was no significant difference between the surfactant subgroups, irrespective of irrigation technique (p = 1.00, p = 0.535, p = 0.805). The use of UI and LI adjuncts to NiTi rotary retreatment techniques showed significant improvement in gutta-percha with BC sealer removal. However, surfactants had no effect on the efficacy.

Prevalence of bone loss surrounding dental implants as detected in cone beam computed tomography: a cross-sectional study.

Objectives: The objective of this study was to assess the prevalence of crestal, and apical bone loss (CBL & ABL) associated with dental implants in CBCT scans. The second objective was to assess the radiographic stage of implant disease and the visible predisposing factors. Materials and Methods: The CBCT scans that were taken from January 2015 to January 2022 in King Saud Medical City were screened to examine the marginal and periapical condition of dental implants. Information related to demographic variables, stage of bone loss, and radiographically evident predisposing factors were collected. The results were analyzed using descriptive statistics, chi-square test, and logistic regression analysis. Results: In total, 772 implant scans were analyzed. The prevalence of crestal bone loss and apical bone loss around the implants were 6.9% and 0.4% respectively. The amount of bone loss was moderate in 52.8% of cases of CBL and 100% mild in cases of ABL. The risk factors for CBL were patient age (p < 0.001), implant location (p < 0.001), bone loss in proximal teeth (p < 0.001), and adjacent edentulous sites (p < 0.001). The risk factors for ABL were adjacent periapical infection (p < 0.001) and endodontic therapy (p = 0.024). Conclusion: The prevalence of CBL and ABL was low. The CBCT can be used as a diagnostic tool for studying the prevalence of bone loss associated with peri-implant disease and relevant risk factors. The implantation of CBCT to evaluate the success and the prognosis of dental implants or the treatment of peri-implant diseases can be further considered in future research.

Conservative preparation of curved root canals using novel nickel-titanium instruments: influence of operator experience.

Background: Nickel-titanium (NiTi) instrumentation systems allow predictable dental root canal treatment. Novel systems promoting conservative preparation are constantly introduced into the market. Therefore, this study aimed to explore how operator experience would influence the performance using a new system - Race Evo- in preparation of curved root canals. Methods: Three groups of participants, with no previous experience with Race Evo, were compared: Third-year dental students, general dental practitioners (GPs), and endodontists. Each participant was asked to prepare 3 simulated resin blocks. Preparation time, the occurrence of procedural errors, and canal deviation were measured. Results: Endodontists prepared the canals with significantly fewer procedural errors (p = 0.027), and in less time than students (p < 0.001) and GPs (p = 0.019). However, there was no significant difference in performance between undergraduate students and GPs. In fact, endodontists and students alike prepared the canal with less deviation compared to GPs (p = 0.006 and p = 0.002). Conclusion: Proficiency in instrumenting curved canals with a new conservative NiTi system was not influenced by experience related to that of the general dental practitioner, but required more specialized experience in root canal treatment. Regardless of experience level, a learning period was still necessary.

Quantitative Analysis of Cone-Beam Computed Tomography Artifacts Induced by Nonmetallic Root Canal Filling Materials Using Different Fields of View: In Vitro Study.

Cone-beam computed tomography (CBCT) imaging artifacts can hinder accurate diagnosis of several conditions. The aim of this study was to quantify CBCT artifacts created by nonmetallic root canal filling materials using two fields of view (FOV). Root canals of twenty extracted maxillary central incisors (n = 20) were instrumented and randomly divided into four equal groups: canals in Group 1 were filled with gutta-percha, canals in Group 2 with mineral trioxide aggregate (MTA) and gutta-percha, canals in Group 3 with gutta-percha and glass-fiber posts, and canals in Group 4 with MTA and glass-fiber posts. Each tooth was mounted on a silicon block and scanned three times using a CBCT machine, first with a prefilling scan (control) and then with postfilling scans, using two different FOV (40∗50 mm and 80∗50 mm). Imaging software was used to measure grayscale pixel values of canal cross sections. Data were analyzed using t-test and paired t-test statistical tests, with statistical significance set at p ≤ 0.05. Dentin at the apical and middle third of the teeth showed a significant decrease in minimum grayscale values in association with gutta-percha (p = 0.027, p = 0.034). However, a wide 80∗50 FOV showed a significant increase in maximum grayscale values of coronal (p = 0.048) and apical dentin (p = 0.049). Glass-fiber posts in middle third cross sections also corresponded to an increase in maximum grayscale values (p = 0.018). Gutta-percha produced dark band artifacts in the root's middle and apical thirds, whereas white streak artifacts were produced by gutta-percha in the coronal third and glass-fiber posts in the coronal and middle thirds when imaged with a wider FOV. A smaller FOV is therefore recommended for CBCT imaging, as it produces fewer artifacts.

New heat-treated vs electropolished nickel-titanium instruments used in root canal treatment: Influence of autoclave sterilization on surface roughness.

Nickel-titanium (NiTi) instruments used to treat root canal infections are affected by autoclave sterilization in various ways. The aim of this study was to compare the effect of autoclave sterilization on two NiTi rotary instruments that undergo different manufacturing treatments: The electro-polished Race and the heat-treated Race Evo, using scanning electron microscope analysis. In this in-vitro study, Race and Race-Evo instruments were subjected to a number of autoclaving cycles (0, 1, 3, 5, and 10). Scanning electron microscopy images were obtained at 3 mm from the tip of the file at 450x and 1000x magnifications. Surface roughness parameters were measured using ImageJ software. The results showed that autoclave sterilization caused a significant decrease in conventional NiTi Race surface roughness. While in Race Evo, surface roughness increased following the first autoclaving cycle. After 10 autoclaving cycles, surface roughness significantly decreased for both Race and Race Evo files.

Radiographic assessment of endodontic mishaps in an undergraduate student clinic: a 2-year retrospective study.

Objectives: The aim of this study was to compare the occurrence of instrumentation and obturation related endodontic procedural mishaps following the use of either, stainless steel hand or engine-driven rotary instrumentation techniques. Methods: From a computerized hospital database, a total of 730 dental patient records who had received endodontic treatment by undergraduate dental students between August 2018 to September 2020 were retrieved. The inclusion criteria were primary (non-surgical) endodontic treatment on permanent teeth with complete radiographic records. Following record screening, a final sample of n = 475 dental records were included. Radiographic records were evaluated for both instrumentation and obturation related mishaps. The data was analysed using multiple logistic regression analysis (α = 0.05). Results: Engine-driven rotary instrumentation resulted in a significant decrease in the overall occurrence of instrumentation related endodontic mishaps by 40% compared to hand instrumentation (Odds Ratio = 0.59 [0.36-0.97], p = 0.04). In particular, rotary instrumentation decreased ledge formation, perforation and obturation related mishaps, with minimal effect on the limitation of zipping. Conclusion: The use of rotary instrumentation techniques may reduce the incidence of instrumentation and obturation endodontic mishaps in the undergraduate dental clinic.

Evaluation of Dentinal Microcracks following Diode Laser- and Ultrasonic-Activated Removal of Bioceramic Material during Root Canal Retreatment.

This study is aimed at evaluating the use of microcomputed tomography (micro-CT) analysis and the dentinal microcrack formation following retreatment of bioceramic sealer employing adjunct laser-activated irrigation and ultrasonic-activated irrigation. Thirty sound human single-canal teeth (n = 30) obturated using the single-cone technique with bioceramic sealer were retreated using nickel-titanium (NiTi) rotary files. The sample was randomly divided into three equal groups: group 1, the control group, was not subjected to further treatment; group 2 underwent ultrasonic activation of irrigants; group 3 underwent active irrigation with a diode laser (980 nm wavelength). Using micro-CT, the teeth were scanned before and after retreatment protocols. Two calibrated experienced observers viewed the cross-sectional images and calculated the number of dentinal defects. The presence of any crack or craze line on the external root surface or internal canal wall was counted. Data were analyzed using Friedman's two-way analysis of variance and Fisher's exact test. Statistical significance was set at p < 0.05. A significant increase occurred in the number of cracks post retreatment protocols, specifically in the coronal and middle canal thirds, compared to pre- and postinstrumentation (p = 0.0001). However, ultrasonic- or laser-activated irrigation did not result in a significant increase in the number of cracks (p = 0.345). NiTi rotary root canal retreatment was associated with a significant increase in dentinal microcracks. However, employing ultrasonic- or laser-activated irrigation as adjunct retreatment techniques did not reveal a significant increase in dentinal microcracks within the roots.