Evaluation of Dentine Structure Loss after Separated File Retrieval by Three Different Techniques: An Ex-vivo Study.

OBJECTIVE: To evaluate the success rate of retrieving separated instrument, the root canal volume changes using cone-beam computed tomography and the retrieval time using Ruddle's technique, Terauchi file retrieval kit (TFRK) and Endo Rescue kit. METHODS: Sixty human mandibular first molars were selected, and a 4-mm portion of #25/.04 rotary files were separated in the middle third of moderately curved mesio-buccal canals. Teeth were randomly assigned into three groups (n=20): R group, in which separated files were retrieved according to Ruddle's technique; T group, in which separated files were retrieved using TFRK and E group, in which separated files were retrieved using Endo Rescue kit. Values were analyzed using IBM SPSS. Results presented as mean+-standard deviation and 95% confidence interval for the root canal volume and time and frequency (%) for success rate. Comparisons of differences in time, canal volume and success rate between groups were assessed. RESULTS: Retrieval was successful in R and T groups (70% and 80% respectively) without any significant difference between them (p=0.715), while E group hadn't any successful samples (0.0%) with significant difference compared to R and T groups (p<0.001, p<0.001). E group showed the highest increase in canal volume followed by R group, while T group exhibited the lowest increase in canal volume. There was no significant difference in the mean retrieval time between R and T groups (p=0.815). CONCLUSION: TFRK provides a more conservative way for retrieval of separated instrument from the middle third of moderately curved canals. (EEJ-2023-01-01).

Instrumentation kinematics does not affect bacterial reduction, post-operative pain, and flare-ups: A randomized clinical trial.

AIM: This randomized clinical trial aimed to assess the effect of instrumentation kinematics (reciprocation or continuous rotation) on bacterial reduction, post-operative pain, and incidence of flare-ups after root canal treatment of single-rooted mandibular premolars with asymptomatic apical periodontitis. METHODOLOGY: Sixty-six patients were included in this prospective, parallel, randomized clinical trial. Patients were randomly allocated into two groups (N = 33) according to the kinematics of the shaping instrument: WaveOne Gold (WO) used in reciprocation or One Shape (OS) used in continuous rotation. Under complete asepsis, bacterial samples were taken before (S1) and after (S2) a standard cleaning and shaping protocol. Evaluation of bacterial reduction was done by both culture technique and quantitative real-time polymerase chain reaction (qPCR) analysis. Post-operative pain was evaluated using the visual analogue scale (VAS) after 24, 48, and 72 h following treatment, while flare-ups were recorded as a binary outcome (Yes/No). Independent and paired t-tests were used for inter- and intra-group comparisons for bacterial count data, respectively. For post-operative pain score, inter-group comparisons were analyzed using the Mann-Whitney U-test while intra-group comparisons were analyzed using Friedman test followed by pairwise comparisons utilizing the Wilcoxon signed rank test with Bonferroni correction. The significance level was set at p ≤ .05 within all tests. RESULTS: All the allocated participants received the intervention and were analysed. The comparison between culture and qPCR methods showed that qPCR analysis demonstrated significantly higher pre-instrumentation baseline bacterial count (p < .05). The percentage of bacterial reduction, detected by either method, significantly decreased after instrumentation using either rotation or reciprocation kinematics (p < .05). However, the difference between the WOG or OS files was statistically non-significant (p > .05). The intra-group comparisons showed a significant reduction in post-operative pain with time (p < .05) for both groups. However, the inter-group comparison demonstrated that the difference in post-operative pain after the use of either WOG or OS was statistically non-significant (p > .05). The incidence of flare-ups between both groups was also not-significant (p = 1). CONCLUSIONS: Shaping kinematics, either rotation or reciprocation motions, had no impact on bacterial reduction and the incidence of post-operative pain and flare-ups after root canal preparation of single-rooted premolars with asymptomatic apical periodontitis.

Investigation of the regenerative potential of necrotic mature teeth following different revascularisation protocols.

This study aimed to assess the revascularisation potential of necrotic mature teeth in a dog model following different protocols. Periapical infection was induced in 54 mature premolars. Teeth were distributed into seven groups: (1) Double-antibiotic-paste/Blood clot, (2) Ciprofloxacin/collagen, (3) Double-antibiotic-paste/Collagen, (4) Modified Tri-antibiotic-paste /collagen, (5) Ciprofloxacin/Gelfoam, (6) Double-antibiotic-paste/Gelfoam, and (7) Modified Triantibiotic- paste/Gelfoam. Positive and negative controls included infected and healthy teeth, respectively, (n = 12 roots/group). Canals were apically shaped to size 0.6 mm then disinfected for 1 month. Intra-canal bleeding was induced then scaffolds were applied for another month. Teeth and supporting bone were surgically sampled. Tissues were histologically scored and vimentin immuno-intensity was estimated. Ciprofloxacin and Double-antibiotic paste/Collagen resulted in significantly better corono-apical tissue ingrowths, vascularity, cementum formation and significantly lower inflammatory extents (P < 0.05).These groups also showed significantly higher Vimentin intensities, (P < 0.05). The applied protocols revascularised necrotic mature canals and reduced inflammation particularly in the Ciprofloxacin/collagen and Double-antibiotic-paste/collagen groups.