Pathogenesis of apical periodontitis and the causes of endodontic failures

Protaper Universal (PTU), Protaper Gold (PTG) (Maillefer, Ballaigues, CH), EdgeTaper (ET), and EdgeTaper Platinum (ETP) (Albuquerque, NM, USA) were tested for both torsional and flexural resistance. The aim of the present study was to evaluate the influence of proprietary heat treatment on the metallurgical properties of the aforementioned instruments. Four groups of 30 different instruments (size 20.07) were tested, then divided into two subgroups of 15 instruments—one for the cyclic fatigue test in a curved canal (90°—2 mm radius) at 300 rpm and 2.5 Ncm. The time to fracture (TtF) and fragment length (FL) were recorded. The other subgroup was subjected to the torsional test (300 rpm, 5.5 Ncm). The torque to fracture and TtF were recorded. All the instruments underwent a SEM analysis. The heat-treated instruments showed a significantly higher fatigue resistance than the non-heat-treated instruments (p < 0.05). No significant differences were found in the torsional resistance between the ET and PTU, and the ETP and PTG. However, when comparing all the groups, the heat-treated instruments showed less torsional resistance. The improvement from heat treatment was mainly found in the cyclic fatigue resistance.

Influence of Different Heat Treatments on Torsional and Cyclic Fatigue Resistance of Nickel–Titanium Rotary Files: A Comparative Study

Aim To compare the incidence, intensity and prediction of postoperative pain after glide path preparation with manual, continuous rotary and a novel reciprocating glide path instrument. Methodology The study included 240 patients, who were treated by four specialists according to a planned treatment protocol. Following access cavity preparation and prior to glide path preparation, the subjects were randomly assigned to one of the three groups according to the glide path instrument by choosing a sealed envelope containing the group name: R-Pilot (VDW, Munich, Germany), ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and stainless steel K-files (Dentsply Sirona; n = 80). Following glide path preparation, the teeth underwent standardized single visit root canal treatment procedures. The root canals were chemomechanically prepared using the ProTaper Next rotary system (Dentsply Sirona) under copious irrigation with 5.25% NaOCl. Final irrigation was performed with 17% EDTA and distilled water. Root fillings were placed using an epoxy resin sealer and gutta-percha with a cold lateral compaction technique. After coronal restorations were placed, the patients were discharged with a questionnaire about the incidence and intensity of pain at 6, 12, 18, 24, 48 and 72 h postoperatively. The data were analysed using chi-square, anova and Tukey tests and logistic regression analysis. Results The presence of preoperative pain (OR ranged between 3.5 and 14.3) and the glide path preparation techniques (OR between 2.2 and 4.1) were associated with significant effects on the incidence of postoperative pain when comparing manual versus engine-driven glide path preparation (P 0.05). Conclusion Preparation of glide paths with rotating or reciprocating NiTi instruments was associated with less postoperative pain levels and incidence compared to manual glide path preparation with no significant difference between rotating and reciprocating instruments. Preoperative pain was the most significant predictor for the occurrence of postoperative pain.

Postoperative pain after glide path preparation using manual, reciprocating and continuous rotary instruments: a randomized clinical trial.

To evaluate the bending and torsional properties of four nickel-titanium endodontic files, we simulated and compared WaveOne® primary size 25 with 0.07 taper, WaveOne Gold® primary size 25 with 0.07 taper, Reciproc® primary size 25 with 0.08 taper, and Reciproc Blue® primary size 25 with 0.08 taper. Three-dimensional models were created using computer-aided design software and numerically analyzed in ANSYS® Workbench. Boundary conditions for the numerical analyses were based on the ISO 3630–1 specifications. The highest stress levels were recorded for WaveOne® and Reciproc®. Numerical results of the bending test showed that WaveOne Gold® is 86% more flexible than WaveOne® with a deflection of 3 mm. Reciproc Blue® was 42.31% more flexible than Reciproc® file with a deflection of 3 mm. The WaveOne® instrument withstood the highest stress under the torsion test, followed by Reciproc®, then Reciproc Blue® files. The stress under torsion in the WaveOne® and WaveOne Gold® files is reduced in a 51%. Regarding Reciproc® and Reciproc Blue® files, the stress under torsional moments remains very similar. Our results exposed a considerable difference in terms of stress tolerance between WaveOne® and WaveOne Gold®. However, Reciproc® files demonstrated a similar stress distribution. The results obtained through finite element analysis suggest that thermal treatment of files might improve their flexibility, increasing resistance during the preparation of highly curved canals. Also, the values obtained regarding the improvement of flexibility were in accordance with the manufacturer claims.

Finite element analysis comparing WaveOne, WaveOne Gold, Reciproc and Reciproc Blue responses with bending and torsion tests

BACKGROUND Use of rotary instruments in the root canals of permanent teeth is well known; however, there are no evidence-based recommendations on the effectiveness of rotary canal instrumentation techniques over manual instrumentation techniques during root canal treatment in primary teeth. AIM To appraise the current literature on the effectiveness of rotary canal preparation techniques compared to manual techniques during root canal treatment in primary teeth. DATA SOURCES MEDLINE, Embase, Cochrane Library, Scopus, PubMed and Web of Science (1 January 1991 to 3 January 2019). STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS Population: Children with primary teeth; Intervention: Rotary canal instrumentation; Control: Manual canal instrumentation; Outcomes: Success rates (clinical and/or radiographic), quality of root filling, instrumentation and root filling time, postoperative pain, cleaning effectiveness. STUDY APPRAISAL AND SYNTHESIS METHODS Cochrane risk of bias tool 2.0 was used to ascertain the validity across five domains. Risk ratio (RR) for dichotomous variables and weighted mean difference for continuous variables were used as summary measures. The GRADE approach was used to assess the certainty of evidence using GRADE-pro software. RESULTS A total of 13 trials were selected of 2471 records after screening of the databases. The RR of clinical success in rotary versus manual canal preparation technique was 1.01 (95% CI: 0.91-1.12; P = 0.913) at 6 months. The RR of radiographic success in rotary versus manual techniques was 0.97 (95% CI: 0.74-1.27; P = 0.805) at 6 months. The quality of root filling was not significantly different between the two groups (P = 0.062). The weighted mean difference of instrumentation time and canal filling time was significantly less with rotary techniques (P < 0.001); however, postoperative pain was non-significant across both techniques at 12, 24 and 72 h but significantly less with rotary techniques at 6 h (P < 0.001) and 48 h (P = 0.023). LIMITATIONS Inclusion of only English literature. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS Rotary canal instrumentation had a similar clinical and radiographic success rate, less postoperative pain (at 6 and 48 h), and took less instrumentation time compared to manual instrumentation techniques (moderate level of evidence).

https://onlinelibrary.wiley.com/doi/epdf/10.1111/iej.13233

A systematic review and meta-analysis of randomized clinical trials comparing rotary canal instrumentation techniques with manual instrumentation techniques in primary teeth.

In Vivo and In Vitro Effectiveness of Rotary Nickel-Titanium vs Manual Stainless Steel Instruments for Root Canal Therapy: Systematic Review and Meta-analysis.

Objectives: The purpose of this study was to evaluate and compare the effect of endodontic irrigation protocols on the micro-tensile bond strength of total-etch and universal adhesives to coronal dentin. Materials and Methods: Forty teeth were collected and their occlusal surfaces were flattened until middle dentin was exposed. They were divided into four groups according to surface treatment of dentin (untreated (control), NaOCl, EDTA and combination of the two irrigants). Two different adhesives were selected for the current study (total-etch adhesive and universal adhesive). Adhesives were applied according to manufacturers’ instructions, then composite restoration was built up incrementally. Resin/dentin specimens were sectioned for micro-tensile bond strength (μTBS) testing. A specimen from each group was randomly selected and investigated under scanning electron microscope (SEM). Results: Regarding the total-etch adhesive; the control group showed the highest value of μTBS, followed by the group irrigated with NaOCl + EDTA, EDTA and NaOCl; respectively. Regarding the Universal adhesive; dentin irrigated with a combination of EDTA+NaOCL was found to give the highest value of μTBS. It was followed by that irrigated with EDTA and control group. Irrigation with NaOCl resulted in a dramatic decrease in the μTBS in comparison with the other groups (p<0.001). Conclusions: The use of a combination of NaOCl and EDTA as a regular endodontic irrigants in dental clinics was found to highly improve the quality of bond strength between dentin and both the total-etch and universal adhesives used for bonding the coronal composite restoration.

Ahmed El-Kabbaney

Papers

In Vivo and In Vitro Effectiveness of Rotary Nickel-Titanium vs Manual Stainless Steel Instruments for Root Canal Therapy: Systematic Review and Meta-analysis.

Endodontic Irrigation Protocols: Effects on the Micro-tensile Bond Strength of Different Adhesive Systems to Coronal Dentin