Effects of Conservative Access and Apical Enlargement on Shaping and Dentin Preservation with Traditional and Modern Instruments: A Micro-computed Tomographic Study.

INTRODUCTION: This ex vivo study aimed to evaluate the shaping abilities and preservation of dentin with traditional and modern instruments after using sizes 25 and 40 in oval canals of mandibular incisors with conservative access. METHOD: Thirty mandibular incisors with single straight oval canals were selected and assigned into 2 groups (n = 15) according to the instrument system used during preparation, Slim Shaper (SS) plus Apical Shaper (AS) and Protaper Gold (PG). The samples were subjected to micro-computed tomography before and after preparation with sizes 25 and 40. The shaping parameters evaluated included canal volume and surface area, amount of unprepared root canal walls, and reduction in pericervical dentin. RESULTS: Canal volume and surface area were significantly increased after enlargement with each instrument size (P < .01). The percentage of unprepared areas showed a significant intragroup decrease after using PG F2 and F4 or SS 3 and AS (P < .05). Intergroup comparison showed no significant differences. Pericervical dentin was reduced in all groups. The intragroup comparison only revealed a significant reduction (P < .01) between PG F2 and F4. In addition, a significant decrease in pericervical dentin (P < .05) was observed between PG F4 40/.06 and AS 40/.03. No significant differences were observed between PG F2 25/.08 and SS 3 25/.04. CONCLUSION: Increasing the instrumentation size from 25 to 40 significantly reduces the percentage of unprepared areas regardless of the system used. In addition, using a modern system with a regressive taper allows the maintenance of pericervical dentin without compromising shaping efficacy in the apical third of the mandibular incisors with oval canals and conservative access.

Cleaning, Shaping, and Disinfecting Abilities of 2 Instrument Systems as Evaluated by a Correlative Micro-computed Tomographic and Histobacteriologic Approach.

INTRODUCTION: This study assessed the cleaning, shaping, and disinfection abilities of 2 instrumentation systems in molar root canals using a novel correlative analytical approach. METHODS: The root canals from extracted mandibular and maxillary molars with apical periodontitis were pair matched according to anatomic similarities as determined by micro-computed tomographic analysis and prepared with either XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) (n = 16) or Reciproc Blue (VDW, Munich, Germany) (n = 16) instruments and 2.5% sodium hypochlorite irrigation. Pre- and postpreparation micro-computed tomographic scans were used to identify and calculate the unprepared surface areas (shaping), which were histobacteriologically evaluated for the presence of residual bacteria (disinfection) and pulp tissue remnants (cleaning) in each canal third. RESULTS: Unprepared canal surface areas for XP-endo Shaper and Reciproc Blue in the full canal length were approximately 26% and 19% (P < .05), respectively (30% and 23% in the apical part of the canal, P > .05). Preparation with Reciproc Blue resulted in 37.5% canals free of bacteria in all sections examined and 56% in the apical sections only. XP-endo Shaper resulted in 44% canals free of bacteria in all sections, and 56% in the apical part of the canal only. Pulp tissue remnants were not observed in 31% (all canal sections) and 50% (apical canal sections) of specimens from both instrument systems. No significant differences were observed between instruments when comparing the amount of pulp tissue remnants and the number of cases negative for bacteria and tissue remnants (P > .05). CONCLUSIONS: Although the Reciproc Blue instrument had superior shaping ability in comparison with XP-endo Shaper, both systems performed similarly in cleaning and disinfecting root canals. Irregular canals and difficult-to-reach areas were not thoroughly cleaned and disinfected by any of the tested systems.

Impact of Contracted Endodontic Cavities on Root Canal Disinfection and Shaping.

INTRODUCTION: The impact of minimally invasive endodontic procedures on root canal disinfection has not been determined. This ex vivo study compared root canal disinfection and shaping in teeth with contracted or conventional endodontic cavities. METHODS: Mandibular incisors with oval-shaped canals were selected and anatomically matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. Conservative and conventional access cavities were prepared, and the canals were contaminated with a pure culture of Enterococcus faecalis for 30 days. Root canal preparation in both groups was performed using the XP-endo Shaper instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and 2.5% sodium hypochlorite irrigation. Intracanal bacteriologic samples were taken before and after preparation, and DNA was extracted and subjected to quantitative polymerase chain reaction. Micro-CT scans taken before and after preparation were used for shaping evaluation. Bacteriologic data were analyzed by the Poisson regression model and the chi-square test with Yates correction. Micro-CT data were analyzed by the Wilcoxon, Mann-Whitney, and Student t tests with the significance level set at 5%. RESULTS: All initial samples were positive for E. faecalis. After preparation, the number of bacteria-positive samples was significantly higher in the contracted cavity group (25/29, 86%) than in the conventional cavity group (14/28, 50%) (P < .01). Intergroup quantitative comparison showed that the reduction in bacterial counts was also significantly higher in the group of conventional cavities (P < .01). Micro-CT data revealed no significant difference in the amount of unprepared areas between groups. CONCLUSIONS: Our findings showed that although shaping using an adjustable instrument was similar between groups, disinfection was significantly compromised after root canal preparation of teeth with contracted endodontic cavities.

Outcome of endodontic treatment with chlorhexidine gluconate as main irrigant: A case series.

This study evaluated the overall endodontic therapy success using 0.12% or 2% chlorhexidine gluconate as main irrigant. Seventy-two teeth diagnosed as vital, necrotic or previously treated teeth with apical periodontitis that were consecutively treated by orthograde therapy. All cases were followed clinically and radiographically for at least 1-year period. Success was established in teeth without signs or adverse clinical symptoms and complete or incomplete radiographic healing. Failure was determined in teeth with any sign or adverse clinical symptoms and a new, unchanged or enlarged radiographic periapical lesion. The data were analysed using chi-square and Fischer's exact tests. The overall success rate for teeth undergoing vital pulp was 84.6%, 76.2% as for the necrotic teeth and 84% for the retreatment cases. No significant differences were observed between groups (P > 0.05). Cases treated with CHX as main irrigant showed a high overall endodontic therapy success rate.

Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume, Concentration, and Retention Time.

INTRODUCTION: This ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system. METHODS: Palatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction. RESULTS: Bacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05). CONCLUSIONS: The concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.

Molecular Analysis of the Antibacterial Effects of Photodynamic Therapy in Endodontic Surgery: A Case Series.

In this case series, bacterial reduction promoted by antimicrobial photodynamic therapy (PDT) used during endodontic surgery was evaluated. Cases were also followed up, and the surgical outcome was reported. The study consisted of 19 teeth with posttreatment apical periodontitis that were consecutively treated by endodontic surgery. After apicoectomy, the root end was treated with PDT using methylene blue as the photosensitizer. Bacteriologic samples were taken from both the cut root surface and the root-end cavity before and after PDT. Samples were analyzed for the total bacterial and Streptococcus group counts using quantitative real-time polymerase chain reaction. EndoSequence BC-RRM Putty (Brasseler, Savannah, GA) was used as the root-end filling. Patients were followed up, and the surgical outcome was evaluated. The reduction in bacterial counts after the PDT approach was analyzed using the nonparametric Wilcoxon signed rank test. PDT significantly reduced the total bacterial and streptococcal counts in both root-end cavities and resected root surfaces (P < .05). The success rate for 15 teeth that were available for recall after 12 to 21 months was 93% under a loose evaluation criterion and 73% under a rigid one. Used during endodontic surgery, PDT significantly enhanced disinfection of the cut surface area and root-end cavity. Cases treated with PDT showed a high healing rate.