Abstract Introduction This study evaluated the disinfecting ability of chemomechanical preparation with rotary nickel-titanium instruments, followed by 2 distinct adjunctive procedures in the root ...canals of extracted mandibular molars by means of a correlative analytical approach. Methods Twenty-two extracted mandibular molars were selected and anatomically matched between groups on the basis of micro–computed tomographic analysis. In the first phase of the experiment, root canals were contaminated with Enterococcus faecalis and subjected to chemomechanical preparation with BT RaCe instruments and 2.5% NaOCl irrigation. Then either XP-Endo Finisher instrument or passive ultrasonic irrigation was used to supplement disinfection. Micro–computed tomography was used to show whether the percentage of unprepared areas correlated to bacterial counts. In the second phase, the same teeth were contaminated once again, and the adjunctive procedures were used. Samples from the isthmus area of mesial roots and the apical 5-mm fragment of distal roots were obtained by cryopulverization. Samples taken before and after treatment steps in both phases were evaluated by quantitative polymerase chain reaction and statistically analyzed. Results In phase 1, preparation in both groups resulted in substantial decrease of bacterial counts ( P < .001). The adjunctive approaches led to a further small bacterial reduction, which was significant for XP-Endo Finisher ( P < .05). No significant differences were observed between groups for persisting bacterial counts. Correlative analysis revealed no statistically significant relationship between bacterial reduction and the percentage of unprepared areas ( P > .05). In phase 2, both methods had significant antibacterial effects in the main canal, but none of them could predictably disinfect the isthmus/recess areas. Conclusions Both XP-Endo Finisher and passive ultrasonic irrigation exhibited antibacterial effectiveness, but only the former caused a significant reduction in the bacterial counts after chemomechanical preparation. None of them were effective in predictably disinfecting the isthmus/recess areas.
Abstract Introduction This study compared the efficacy of a reciprocating single-instrument system and a rotary multi-instrument system followed by a supplementary approach with a finishing ...instrument in removing the filling material from curved canals during retreatment. Methods Forty mesial canals from extracted mandibular molars were instrumented and filled. Then, each mesial canal was retreated by using either Reciproc (VDW, Munich, Germany) or Mtwo (VDW) instruments, alternating the technique used per canal from root to root. The working time was recorded, and the percentage of removed filling volume was assessed by means of micro–computed tomography imaging before and after retreatment. Canals still showing filling material remnants were subjected to an adjunctive approach with the XP-Endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland), and another microCT scan was taken. Data were statistically analyzed with a significance level of 5%. Results The percentage of filling material removed with Mtwo instruments (96%) was significantly higher than Reciproc (89%) ( P < .05), both used up to a final instrument size of 40. Mtwo required less time to remove the filling material than Reciproc ( P < .05). Intragroup analysis in the Reciproc group showed that the R40 instrument removed significantly more filling material than R25 ( P < .05). The supplementary approach with the XP-Endo Finisher was effective in significantly enhancing the removal of filling material ( P < .05). Conclusions The rotary multiple-instrument system was more effective and faster than the reciprocating single-instrument approach in removing previous root canal fillings. As for the Reciproc group, it was observed that the larger instrument promoted significantly better results. The adjunctive finishing instrument XP-Endo Finisher significantly improved filling material removal.
Abstract Introduction This ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative ...bacteriologic and micro–computed tomographic (μμCT) analysis. Methods The mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File ReDent-Nova, Ra’anana, Israel, Reciproc VDW, Munich, Germany, and Twisted File SybronEndo, Orange, CA). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals. Results All instrumentation protocols promoted a highly significant intracanal bacterial reduction ( P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups ( P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area ( P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters ( P > .05). Conclusions The 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.
Abstract Introduction Most studies of the microbiota in root canal–treated teeth focused only on the main canal, not distinguishing regions nor incorporating the intricate anatomy in the analysis. ...Moreover, most of them provided only prevalence data. This study was designed to evaluate the total bacterial counts and the presence, levels, and relative abundance of candidate endodontic pathogens exclusively in the apical root canal system associated with post-treatment apical periodontitis. Methods Apical root specimens obtained during periradicular surgery of 27 adequately treated teeth with persistent apical periodontitis were cryogenically ground. DNA was extracted from the powder, and real-time polymerase chain reaction was used to quantify the total bacteria and 7 bacterial taxa. Results Samples from 21 teeth were positive for bacteria. Streptococcus species were the most prevalent (76%) followed by members of the Actinobacteria phylum (52%) and Pseudoramibacter alactolyticus (19%). The mean total bacterial load in the apical root segments was 5.7 × 104 cell equivalents per root apex (or 2.1 × 104 /100 mg root powder). Streptococci comprised from 0.02%–99.9% of the total bacterial counts, Actinobacteria from 0.02%–84.7%, and P. alactolyticus from 67.9%–99%. Although Enterococcus faecalis was found in only 3 (14%) cases, it was dominant in 2. Conclusions Streptococcus species, members of the Actinobacteria phylum, and P. alactolyticus were the most prevalent taxa in the apical canal system and dominated the bacterial populations in many cases of post-treatment apical periodontitis.
Abstract Introduction This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis. Methods Root ...apexes and matched inflammatory lesions from root canal–treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap. Results The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage. Conclusions Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.
Abstract Introduction This study evaluated the influence of flexibility and reciprocating movement on the fatigue life of endodontic instruments subjected to static and dynamic tests. Methods The ...rotary nickel-titanium instruments used in this study were Reciproc and Mtwo. The instruments were initially subjected to a cantilever-bending test and then to static and dynamic fatigue tests. Reciproc instruments were operated in reciprocating movement, whereas Mtwo instruments were worked in continuous rotation. Results The means of bending resistance (maximum load in grams) of the instruments were 274.9 for Reciproc and 429 for Mtwo. The mean times (in seconds) to fracture of the instruments subjected to static and dynamic tests were 214.5 (static) and 286.3 (dynamic) for Reciproc and 38.9 (static) and 99 (dynamic) for Mtwo. The Student's t test revealed significant differences in all tests ( P < .05). Conclusions The results of the present study showed longer fatigue life for instruments with higher flexibility, driven by reciprocating movement, and in the dynamic testing model. These findings reinforce the assumption that use of reciprocating movement is a means to prolong the fatigue life of rotary nickel-titanium endodontic instruments during instrumentation of curved canals.
Abstract Introduction This study compared the ability of different approaches to supplement the antibacterial effects of chemomechanical preparation in oval-shaped root canals. Methods Long oval ...canals from extracted teeth infected with Enterococcus faecalis (ATCC 29212) were chemomechanically prepared up to a 40/04 rotary BioRaCe instrument using 2.5% NaOCl irrigation and then subjected to two supplementary protocols. In the passive ultrasonic irrigation (PUI)/chlorhexidine (CHX) group, canals were subjected to PUI for the activation of NaOCl followed by a final rinse with 0.2% CHX digluconate solution. In the Hedström group, canals received additional Hedström filing directed towards the buccal and lingual canal recesses. Bacteriological samples were taken before and after preparation, after PUI or Hedström instrumentation, and after CHX final rinsing. Results Chemomechanical preparation and the supplementary steps promoted a highly significant bacterial reduction ( P < .001). Quantitative (reduction in levels) and qualitative (frequency of negative cultures) analyses showed that PUI alone or Hedström filing did not significantly increase bacterial reduction ( P > .05). Further rinsing with CHX also failed to significantly increase bacterial elimination when compared with post-PUI samples. However, the cumulative antibacterial effects of PUI and CHX final rinse were effective in significantly reducing bacterial counts to levels below those achieved after preparation ( P = .03). This combined PUI/CHX approach also resulted in a significant increase in the incidence of negative cultures ( P = .04). Conclusions Findings suggest that there may be a benefit of using the PUI for the activation of NaOCl followed by a final rinse with CHX as supplementary steps in the treatment of infected oval-shaped root canals.
Abstract Introduction Oval-shaped root canals might represent a great challenge for proper disinfection. This study compared the capability of a newly developed instrument, the self-adjusting file ...(SAF), and rotary nickel-titanium (NiTi) instrumentation to eliminate Enterococcus faecalis populations from long oval root canals of extracted human teeth. As a secondary purpose, the ability of a modification in sampling technique to recover bacteria lodged in recesses of oval canals was evaluated. Methods Long oval canals from mandibular incisors and maxillary second premolars were infected with E. faecalis (ATCC 29212) for 30 days and then randomly distributed into 2 experimental groups. In group 1, canals were prepared up to a 40/04 rotary BioRaCe instrument by using irrigation with NaviTip needles; in group 2, canals were prepared by using the SAF system with continuous irrigation. NaOCl and ethylenediaminetetraacetic acid were used as irrigants. Bacteriologic samples were taken before (S1) and after preparation (S2a and S2b). Results Reduction in the bacterial populations was highly significant in both groups ( P < .001). Preparation of long oval canals with the SAF was significantly more effective than rotary NiTi instrumentation in reducing intracanal E. faecalis counts ( P = .01). Frequency of positive cultures in S2 samples was 11 of 20 (55%) for rotary instrumentation and 4 of 20 (20%) for SAF instrumentation ( P = .048). S2b samples (modified method) yielded more positive samples than S2a (12/40 vs 5/40), but this difference reached no statistical significance ( P > .05). Conclusions The SAF system was significantly more effective than rotary NiTi instrumentation used with syringe/needle irrigation in disinfecting long oval root canals in vitro . A modified sampling technique might be necessary for oval canals.
Abstract Introduction Bacterial biofilm communities established in the apical part of infected root canals are conceivably of utmost importance in the pathogenesis of apical periodontitis. This study ...investigated the diversity of the apical endodontic microbiota by using cryopulverized root segments and massive parallel pyrosequencing analysis. Methods Ten extracted teeth with attached apical periodontitis lesions were sectioned to obtain 2 root fragments (apical and middle/coronal segments). Apical root fragments were cryogenically ground, and DNA was extracted from samples and subjected to multiplex tag-encoded FLX-titanium amplicon pyrosequencing. Results Pyrosequencing analysis yielded partial 16S rRNA gene sequences that were taxonomically classified into 187 bacterial species-level phylotypes (at 3% divergence), 84 genera, and 10 phyla. The most represented, abundant, and prevalent phyla were Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria. The majority of species-level phylotypes occurred at low levels. The mean number of species-level phylotypes per sample was 37 (range, 13–80). A great interindividual variation in the composition of the apical microbiota was disclosed. Conclusions This study extensively describes the diversity of the bacterial communities present selectively in the apical part of root canals of teeth with apical periodontitis and revealed a previously unanticipated high bacterial diversity.
Abstract Introduction This cross-sectional study determined the prevalence of apical periodontitis in 1086 root canal–treated teeth from an urban Colombian population and evaluated the association of ...several factors with the periradicular status. Methods Periapical radiographs were used for analyses, and teeth were classified as healthy or diseased according to the periradicular status. Other factors were also evaluated for their association with the periradicular conditions, including gender, quality of both endodontic treatment and coronal restoration, apical level of filling, and presence of post restoration. Results Fifty-one percent of the treated teeth were classified as healthy. Only 33% of the teeth had endodontic treatment rated as adequate. The quality of both endodontic treatment and coronal restoration significantly influenced the periradicular conditions ( P < .001). Combined data revealed that teeth with both adequate endodontic treatment and adequate restorations showed significantly better periradicular status than the other combinations ( P < .01), except for teeth with adequate treatment and inadequate restoration ( P = .08). Canals filled up to 0–2 mm short of the apex had a significantly higher number of teeth rated as healthy than overfilled or underfilled cases ( P = .02). Regression analysis showed that the quality of endodontic treatment was the most significant factor influencing the periradicular status ( P < .001). Gender and presence of post restoration had no association with the periradicular conditions. Conclusions Data from this Colombian population showed a relatively high prevalence of apical periodontitis in root canal–treated teeth. This was largely due to an equally high prevalence of treatments performed under substandard technical quality. The quality of the endodontic treatment was the most determinant factor for healthy periradicular status.
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