Effects of Contemporary Irrigant Activation Schemes and Subsequent Placement of an Interim Dressing on Bacterial Presence and Activity in Root Canals Associated with Asymptomatic Apical Periodontitis

Abstract

New tools for activating endodontic irrigants have evolved, yet their impact on root canal disinfection, in comparison to the passive placing of an inter-visit medication, have not yet been fully elucidated. The use of DNA- and rRNA-based methods may cast some new light on this issue, as they allow a comparison to be made between microbial presence and activity. Therefore, the aim of this single-arm intervention trial is to evaluate the antibacterial effect of endodontic procedures using both molecular methods. Root canal samples were obtained from 20 patients with asymptomatic apical periodontitis after each treatment step: access cavity, chemo-mechanical preparation, adjunctive procedures (XP-endo Finisher file and passive ultrasonic irrigation), calcium hydroxide medication, and 2nd-visit root canal preparation. DNA and cDNA from the samples were subjected to quantitative polymerase chain reaction with universal primers for the bacterial 16S rRNA gene. Chemo-mechanical preparation promoted a drastic reduction in bacterial levels and activity, whereas the adjunctive procedures did not make a significant contribution to further disinfection. At the 2nd visit, bacteria were active after the use of calcium hydroxide medication; however, they were significantly reduced after a 2nd-visit preparation. Consequently, the lowest bacterial levels were found at the end of the treatment. This clinical trial, which used an rRNA and rDNA combined approach, confirmed previous studies showing that root canal preparation represents the main strategy for root canal disinfection.

Root Canal Morphology of the Permanent Mandibular Incisors by Cone Beam Computed Tomography: A Systematic Review

“…Of these, 2219 were removed because of their being duplicates or not related to the study. Of the remaining 71 studies, 52 were removed due to lack of relevance, not using CBCT as their diagnostic methodology, or being in vitro trials, case studies or systematic reviews, leaving a total of 19 studies [8,14,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] (Figure 3. Flowchart).…”

“…When there were two canals, the most frequent classification was type III, with the exception of four studies [8,22,23,35]. There was no heterogeneity as to the frequency of the rest of configurations, with studies where the next most frequent configurations were type II [14,23,26,27,30,33,34], type V [8,[19][20][21]24,25,28,29,32], or type IV [31]. The remaining types [VI, VII and others] were generally present in very low or non-existent percentages.…”

“…Five studies reported symmetry between the incisors on the right and left side of the patient [8,19,20,23,26,33]. Lateral incisors showed a higher prevalence in the existence of a second canal compared to central incisors in fourteen studies [7,14,[20][21][22]25,[27][28][29][31][32][33][34][35]. The central incisor had a higher prevalence in only three [19,23,26].…”

“…Regarding gender influence, there was no unanimity as to a higher prevalence of second canals in men [19,20,24,31] than in women [27,29], and there were even certain studies where no significant differences were found [8,22,25,30,34,35]. Geographical distribution indicated a lower incidence of a second canal in the Chinese population [14,29,[32][33][34]. There was no direct relationship between voxel size and the increased prevalence of a second canal.…”

“…Specifically, as regards such lesions, the prevalence rate of missed canals ranges between 12.2% and 17.4% in central and lateral mandibular incisors, respectively [13]. These data should encourage clinicians to search for a more complex internal anatomy and reveal the importance of chemo-mechanical preparation of the root canal as the main strategy for its disinfection [14].…”