Cyclic and torsional fatigue resistance of a new rotary file on a rotary and reciprocating motion.

This study evaluated the cyclic and torsional fatigue resistance of a new nickel-titanium (Flat File 25.04) instrument on the continuous and reciprocating motion. Sixty instruments of the ProDesign Logic2 25.03 and 25.05 (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil), and MK Flat File 25.04 (n = 20) (MK Life, Porto Alegre, Brazil) were used. For the cyclic fatigue test, an artificial stainless steel simulated canal with an angle of 60° and a radius of curvature of 5 mm located 5 mm from its tip was used. The torque and rotation angle at the instruments' failure on the torsional fatigue test was based on the ISO 3630-1 protocol, in which the 3 mm tip of each instrument was fixed and connected to an electric motor and a load cell. The fractured surface of each fragment was examined by scanning electron microscopy. Data were analyzed using a 1-way analysis of variance and Tukey's test with a significance level of 5%. Flat File 25.04 had lower cyclic fatigue in both kinematics than the Logic instruments (p < .05). Reciprocating motion improved the cyclic fatigue of the tested instruments (p < .05). Flat File 25.04 had similar torque to Logic2 25.05 (p > .05), and both were superior to Logic2 25.03 (p < .05). The angular deflection values were different for the three tested instruments (p < .05), in the decreasing order: Logic2 25.03, 25.05, and Flat File 25.04. Flat File presented good resistance to cyclic and torsional fatigue resistance. Reciprocating motion improved the cyclic fatigue resistance of the instruments and can be considered when using programmable motors. RESEARCH HIGHLIGHTS: Scanning electron microscopy evaluation of different endodontic rotary file and fatigue resistance tests.

Intraoral Somatosensory Alterations Impact Pulp Sensibility Testing in Patients with Symptomatic Irreversible Pulpitis.

INTRODUCTION: This case-control study aimed to compare trigeminal somatosensory sensitivity between patients with a clinical diagnosis of symptomatic irreversible pulpitis (n = 33) and healthy participants (n = 33) and to evaluate the impact of somatosensory stratification of symptomatic irreversible pulpitis on pulp sensibility testing. METHODS: A standardized battery of qualitative sensory assessment measured intra- and extraoral sensitivity to touch, cold, and pinprick stimuli. Dental pain intensity (0-100, numeric rating scale) and duration (seconds) evoked by cold stimuli (refrigerant spray) were applied to, respectively, the nonaffected and affected tooth (cases) and the upper right and left premolars (controls); z score transformation, analysis of variance (ANOVA), and chi-square tests were applied to the data (P = .050). RESULTS: Patients with irreversible pulpitis reported intraoral hypersensitivity more frequently than healthy participants (58% and 33%, respectively; P < .05). In addition, patients with irreversible pulpitis reported higher z scores of pain intensity (ANOVA main effects, F = 37.10, P < .05, partial η2 = 0.37) and duration (ANOVA main effects F = 23.3, P < .05, partial η2 = 0.27) after the pulp sensibility test compared with healthy participants. Nevertheless, subgroup analysis taking into account the presence of intraoral hypersensitivity indicated that the pain lingered most for patients with symptomatic irreversible pulpitis who also presented intraoral hypersensitivity (Tukey test, P < .05) but with no differences between patients with irreversible pulpitis without intraoral hypersensitivity and healthy participants (Tukey test, P > .05). CONCLUSIONS: QualST is able to detect intraoral alterations in patients with symptomatic irreversible pulpitis that seem useful to stratify the patients into distinct subgroups. Therefore, somatosensory assessment of the adjacent tissues may provide diagnostic fine-tuning of dental pulp diseases.

Effect of endodontic retreatment on the bond strength of resin cements to root canal dentin.

PURPOSE: To evaluate the effect of endodontic retreatment on the bond strength of different cementation techniques (self-adhesive and conventional resin cement) through the push-out mechanical testing and the penetrability of resin cements to root dentin. METHODS: 60 human teeth with single oval-shaped canals were used (n=15) : G1 - Endodontic treatment and cementation with RelyX ARC (ETA); G2 - Endodontic treatment and cementation with U200 (ETU); G3 - Endodontic retreatment and cementation with RelyX ARC (ERA); G4 - Endodontic retreatment and cementation with U200 (ERU). The groups with conventional endodontic treatment were filled with AH plus (ETA and ETU), while the groups that were submitted to endodontic retreatment were initially filled with Endofill and afterwards with AH Plus. Each radicular third (cervical, middle, and apical, of each tooth) was submitted to push-out bond strength testing, followed by evaluation with confocal laser microscopy to determine the penetration of the resin cements, and scanning electron microscopy was used to evaluate the failure mode. The parametric data were evaluated by two-way ANOVA and Tukey tests, and non-parametric data by Kruskal-Wallis and Dunn tests (α< 0.05). RESULTS: The ETA group had higher bond strength values to intra-radicular dentin than the other groups in all root thirds (P< 0.05). Endodontic retreatment had a negative impact on the penetration and push-out bond strength of RelyX ARC and U200 cement, regardless of the analyzed radicular third. CLINICAL SIGNIFICANCE: The bond strength between fiber post and root dentin can be affected by several factors, such as technical failure, cementation technique, pretreatment of the dentin, type of post and adaptation. The endodontic retreatment interferes negatively on the bond strength and penetrability of RelyX ARC and U200 cements to dentin, regardless of the analyzed radicular third. Therefore, the endodontic retreatment might have an adverse effect due to over preparation and aggression to the root canal.

Manual vs. rotary instrumentation in endodontic treatment of permanent teeth: A systematic review and meta-analysis.

PURPOSE: To systematically review all studies comparing manual instrumentation with at least one rotary instrument in the preparation of the root canal of permanent human teeth. METHODS: The electronic databases PubMed, EMBASE, LILACS, IBECS and BBO were searched. In vitro studies published until 27 of September, 2016 were included. For statistical analysis, we used the Comprehensive Meta-Analysis software (Biostat), considering P< 0.05 significant. RESULTS: A total of 1,104 articles published until September 27, 2016 were obtained, with 57 meeting the eligibility criteria. The studies were grouped according to the main methodology used (computerized tomography, periapical radiography, image amplification and scanning electron microscope). Due to the wide variability of the methodologies and evaluated parameters, a subgroup analysis was performed based on the evaluated parameter. The meta-analysis revealed that rotary instruments caused a significant reduction in instrumentation time and a smaller change of the canal curvature than manual instruments. The rotary instrumentation presented better results regarding root canal transportation, ability of centralization within the canal path and shaping of the canal. Manual instrumentation performed better with regard to the smear layer and debris production, more instrumented canal surfaces and fewer dentin defects. CLINICAL SIGNIFICANCE: An increasing number of studies have compared the efficiency of manual and rotary instrumentation in endodontic treatment of permanent teeth. This study helps elucidate which method is more efficient in the endodontic treatment of permanent teeth.

Laser therapy as an adjunct in the treatment of sodium hypochlorite extrusion through a root perforation: a case report.

Accidental sodium hypochlorite extrusion can occur during endodontic irrigation procedures. The symptoms appear immediately and include severe pain, swelling, and probable tissue necrosis adjacent to the root of the treated tooth. Treatment of sodium hypochlorite extrusion involves immediate and copious saline irrigation to neutralize the area and prescription of analgesic, anti-inflammatory, and antibiotic medications. Low-level laser therapy (LLLT) might be useful as an adjuvant treatment for damaged soft tissues to improve healing. This case report describes the treatment of accidental extrusion of 1% sodium hypochlorite through a root canal perforation in a mandibular incisor during endodontic treatment. The extrusion caused minor swelling within the mentolabial sulcus and a large area of necrosis in the gingivolabial mucosa and right edentulous premolar area. Conventional treatment was performed in association with LLLT. Clinical and radiographic examinations after 6 months showed complete healing of the necrotic area without paresthesia and the repair of apical tissues.

Influence of different sized files on the accuracy of two electronic apex locators.

The aim of this study was to evaluate the impact of different file sizes on the accuracy of two electronic apex locators (EALs). Thirty extracted human single-rooted permanent mandibular incisors were used. A #10 K-file was inserted in the root canal until its end could be observed (using a light microscope) through the apical foramen. One millimetre was subtracted to establish working length (WL). Electronic readings were performed using MiniApex Locator or Root ZX II, from #10 K-file to #130 K-file. Statistical analysis was performed by two-way anova and Tukey test (P ≤ 0.05). From #60 to #130 K-file, observed differences were noted between the values obtained with both EALs and WL (P ≤ 0.05). The MiniApex Locator showed increased means when measurements were made with #50 to #70 and with #120 (P = 0.008) and #130 (P = 0.005) K-files. File sizes influenced the accuracy of EALs - the greater the instrumentation size, the higher mean differences compared to WL.

Cyclic and Torsional Fatigue Resistance of Reciprocating Single Files Manufactured by Different Nickel-titanium Alloys.

INTRODUCTION: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of the following reciprocating single-file systems: ProDesign R 25.06 (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil), Reciproc R25 (VDW GmbH, Munich, Germany), and Unicone L25 (Medin SA, Nové Mesto in Morave, Czech Republic). METHODS: Sixty instruments of the ProDesign R, Reciproc R25, and Unicone L25 systems (n = 20) were used. Cyclic fatigue resistance was tested measuring the time to failure in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature (n = 10). Torque and angle of rotation at failure of new instruments (n = 10) in the 3 mm from the tip portion were measured during torsional testing according to ISO 3630-1. The fractured surface of each fragment was examined by scanning electron microscopy. Data were analyzed using 1-way analysis of variance and Tukey tests, and the level of significance was set at 5%. RESULTS: The cyclic fatigue resistance values of ProDesign R 25.06 were significantly higher than the other groups (P < .05). Reciproc R25 showed higher fatigue resistance than Unicone L25 (P < .05). In relation to the torsional test, the ProDesign R 25.06 and Unicone L25 systems showed higher angular rotation until fracture than Reciproc R25 (P < .05). However, Reciproc R25 and Unicone L25 showed higher torque load than ProDesign R 25.06 (P < .05). Scanning electron microscopic analysis showed similar and typical features of cyclic and torsional failure for all instruments tested. CONCLUSIONS: ProDesign R presented the highest cyclic fatigue resistance and angular rotation to failure compared with Reciproc and Unicone. However, Reciproc showed higher torsional strength to failure.

Regeneração óssea em alvéolos de ratos após enxerto de osso bovino inorgânico medular e biocerâmica sintética densa / Alveolar bone regeneration in rats after grafting of anorganic bovine bone and thick synthetic bioceramic

Introdução: é incerto se o uso de biomateriais em cirurgiasparendodônticas é capaz de facilitar ou induziro processo de regeneração óssea. Esse estudo analisou,comparativamente, os efeitos do preenchimento de alvéolosde ratos com osso bovino inorgânico medular euma biocerâmica sintética densa no processo de regeneraçãoóssea. Material: Quarenta e oito ratos albinosWistar foram distribuídos, aleatoriamente, em três grupos,que, após a extração dentária, tiveram os alvéolos preenchidosda seguinte forma: GI (n = 12) coágulo (controle);GII (n = 18) osso bovino inorgânico medular; GIII (n = 18)biocerâmica sintética densa. As amostras foram obtidasem 7, 15 e 30 dias pós-cirurgia. Foram realizadas análisesmicroscópicas quantitativas do infiltrado inflamató-rio, densidade fibroblástica, densidade angioblástica eneoformação óssea. Os dados foram submetidos ao testede Kruskal-Wallis (α < 0,05) para detectar diferenças entreos grupos no mesmo intervalo de tempo. Resultados:apesar de terem sido detectadas algumas diferenças entreos grupos experimentais e o controle para infiltrado inflamatórioe densidade angioblástica em 07 dias, e formaçãoóssea em 15 dias, no período de 30 dias o processo de reparofoi semelhante para todos os grupos. Conclusões:não houve diferença entre os dois materiais empregados,os quais não atrasaram o processo de regeneração óssea,e, se usados em cirurgias parendodônticas, podem atuarcomo materiais osteocondutores e osteopreenchedoresnos grandes defeitos ósseos.

Evaluation of the flow rate of 3 endodontic sealers: Sealer 26, AH Plus, and MTA Obtura.

OBJECTIVE: The aim of this study was to evaluate the flow rate of 3 endodontic sealers: Sealer 26, AH Plus, and MTA Obtura. STUDY DESIGN: According to the method proposed by the American Dental Association (ADA specification no. 57), the sealers were placed between 2 glass slabs under a weight of 120 g. The diameters of the formed discs were measured with a digital paquimeter. The test was repeated 5 times for each sealer. RESULTS: The results were expressed as arithmetic means, and the statistical analysis was performed through Turkey test. AH Plus showed significantly superior flow rate compared with Sealer 26 and MTA Obtura. There was no statistically significant difference between flow rates presented by Sealer 26 and MTA Obtura. CONCLUSION: Within the limitations of this in vitro study, it was concluded that all of the the endodontic sealers tested presented greater flow than the minimum recommended in the ADA 57 specification.