The impact of an enhanced infection control protocol on molar root canal treatment outcome - a randomized clinical trial.

AIM: To evaluate the effect of an enhanced infection control protocol on root canal treatment outcomes and on microbial load within root canals after chemomechanical preparation. METHODOLOGY: A total of 144 molar teeth from 139 healthy patients receiving primary root canal treatment were block randomized to a standard protocol (StP) or an enhanced infection control protocol (EnP). Both treatment arms adhered to current best practice recommendations, while the EnP comprised additional steps that included replacing rubber dams, gloves, files, all instruments and surface barriers at the time of canal filling to reduce the chances of iatrogenic contamination. Patients and radiographic examiners were blinded to the protocol used. Intracanal microbial samples were taken at baseline (S1) and after completion of chemomechanical preparation (S2). Microbial 16S rDNA copy numbers were enumerated by quantitative polymerase chain reaction (qPCR). Cone beam computed tomography (CBCT) scans were taken before treatment and at one-year follow-up. The outcome was assessed clinically and radiographically using CBCT by logistic regression modelling. RESULTS: At one-year follow-up, 115 teeth were analysed (54 in StP and 61 in EnP). The percentage of favourable outcomes assessed by CBCT was 85.2% in the EnP and 66.7% in the StP. The odds of 12-month success was three times higher in the EnP group compared with the StP group (OR=2.89; p=0.022, CI: 1.17 - 7.15). The median bacterial reads were reduced from 8.1×103 in S1 samples to 3.5×103 in the StP group and from 8.6×103 to 1.3×103 in the EnP group. The enhanced protocol significantly reduced bacterial counts in pre-canal filling samples when compared to the standard protocol (p=0.009). CONCLUSIONS: The implementation of a facile, enhanced infection control protocol in primary root canal treatment resulted in less detectable bacterial DNA before canal filling and significantly more successful outcomes at one year.

Impact of an Enhanced Infection Control Protocol on the Microbial Community Profile in Molar Root Canal Treatment: An in Vivo NGS Molecular Study.

INTRODUCTION: Recent findings demonstrated that 1-year cone-beam computed tomography-based outcomes of molar root canal treatment were improved through an enhanced infection protocol (EnP), when compared with a current best-practice standard infection control protocol (StP). The EnP comprised measures to reduce iatrogenic contamination from direct and indirect contact surfaces, including the replacement of the rubber dams, gloves, files, all instruments, and surface barriers before root canal obturation. The aim of this study was to investigate the effect of such an EnP on resident microbiome present after chemomechanical instrumentation and the protocol ability in reducing iatrogenic contamination in molar teeth during root canal treatment. METHODS: Molar teeth were block-randomized to receive treatment under EnP or StP. To compare the differential effect of the protocol on the identity of bacteria present, 150 matched DNA extracts from 75 molar teeth samples (StP, n = 39; EnP, n = 36) were evaluated. Samples were taken before (S1) and after (S2) chemomechanical preparation and were subjected to next-generation sequencing of the V3-V4 region of the 16S rRNA gene before bioinformatical identification using the HOMD oral microbiome database and downstream taxonomic processing, providing measures of richness and diversity of bacteria and significant bacterial taxa during chemomechanical instrumentation and the effect of the 2 treatment groups. RESULTS: Eighty-eight microbial taxa were significantly more abundant in StP S2 samples, including endodontically relevant contaminants taxa as Actinomyces, Cutibacterium, and Haemophilus. The S2 samples demonstrated fewer residual bacterial species in the EnP group, with 26.8 observed species compared with 38.3 in the StP. Reduced diversity and richness measures were noted in the EnP pre-obturation samples compared with the StP in OTU, Chao1, and ACE indices (P ≤ .05). Differential microbial identities between S1 and S2 samples and protocols demonstrated that the previously observed increased effectiveness of the EnP protocol was likely to prevent recontamination or de novo contamination of the root canal space during treatment. CONCLUSIONS: The implemented EnP resulted in a specific reduction of microbial taxa often associated with recontamination or iatrogenic contamination, suggesting the basis for improved infection control measures during root canal treatment.