Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth

Abstract The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Influence of bioceramic intracanal medication on the bond strength of bioceramic root canal sealer

Abstract To investigate the influence of the remaining volume of a new intracanal medication based on bioceramic compounds on the bond strength (BS) and formation of an adhesive interface between calcium silicate-based and epoxy resin-based root canal sealers. For this purpose, the specimens were distributed according to the intracanal medication (n = 26): Bio-C Temp (BCT) and Ultracal XS (UXS). The roots were scanned in microCT, and after 7 days, the medication was removed. Then a new scan was performed to evaluate the volume of medication remaining. Subsequently, 40 specimens were redistributed into 2 subgroups (n = 10) and filled according to the sealer used: AH Plus (AHP) and Bio-C Sealer (BCS), to assess the bond strength by using the push-out test, and the adhesive interface by confocal laser fluorescence microscopy (CLSM) and scanning electron microscopy (SEM). The t test showed a smaller remainder of BCT (1.77 ± 0.86) compared with UXS (10.47 ± 5.78), irrespective of the root third evaluated. The BS showed that teeth with BCT + BCS had higher bond strength values (3.70 ± 1.22) when compared to the other groups: BCT + AHP (2.15 ± 1.07), UXS + BCS (3.18 ± 1.09) and UXS + AHP (2.11 ± 1.02) (p<0.001). The cervical third had higher BS when compared with the middle and apical thirds (p < 0.001), and higher number of adhesive failures. The adhesive interface in SEM and CLSM images showed better adaptation for the association between BCT + BCS. Intracanal medication and silicate-based endodontic sealer appeared to interact chemically by forming a biomineralizing layer, allowing for an increase in the bond strength and forming an adhesive interface between the materials, with no or less gap formation.

Heat-treated NiTi instruments and final irrigation protocols for biomechanical preparation of flattened canals

Abstract This study evaluate shaping ability of heat-treated NiTi-alloy instruments associated with different final irrigation protocols in flattened root canals. Thirty human mandibular incisors with flattened root canals were divided into 5 groups (n = 10): (XP) Original Protocol XP-endo Shaper; (XP-WT) Original Protocol XP-endo Shaper with working time variation; (XP-K) XP-endo Shaper with kinematics variation; (XP-WTK) XP-endo Shaper with kinematics and working time variations; (Hyflex) Hyflex CM. For the variation in working time protocols the same sample of the XP-endo Shaper groups with and without kinematic variation were used. To evaluate final irrigation protocols, groups 1, 3 and 5 were submitted to 3 protocols: (NI) No irrigation (n = 2); (CI) conventional irrigation (n = 4), and (EndoVac) irrigation (n = 4). The samples were scanned by microcomputed tomography and prepared for scanning electron microscopy evaluation. Quantitative data were evaluated using the parametric ANOVA test, with statistical significance level set at 5%, and qualitative data obtained were compared to establish the agreement between examiners through the Kappa test. It was observed that in the analysis of XP-endo Shaper protocols, the additional working time did not cause difference in any of parameters evaluated (p > 0.05) in relation to time recommended by manufacturer. Compared to Hyflex, XP-K showed highest mean volume increase (p < 0.05) and lowest percentage of untouched walls (p < 0.05). In the qualitative evaluation, final irrigation protocol with EndoVac provided the best cleaning results when associated with XP-K and with Hyflex. Thus, supplementary techniques are effective tools to enhance cleaning and to promote higher touch of walls during root canal preparation.

O uso do microscópio operatório associado aos novos recursos na microcirurgia parendodôntica moderna / The use of the operating microscope associated with the new resources in modern endodontic microsurgery

Introdução: mesmo quando um tratamento endodôntico ou retratamento mais rigoroso é realizado, a periodontite apical pode persistir, levando à destruição do ligamento periodontal, cemento, osso alveolar e dentina. Nesses casos, o tratamento endodôntico cirúrgico, se realizado com o microscópio operatório (MO), ressecção mínima da raiz, retropreparo com pontas ultrassônicas e materiais para retrobturação biocompatíveis, pode alcançar mais de 90% de sucesso. Os procedimentos endodônticos cirúrgicos foram completamente transformados pela incorporação do MO, associado a novos recursos como aparelhos de ultrassom piezocirúrgico com pontas específicas para microcirurgia, microespelhos flexíveis, microexploradores, microcuretas endodônticas, microcondensadores e microinstrumentos para sutura. O MO pode otimizar todas as etapas de uma microcirurgia parendodôntica, incluindo o descolamento do retalho, a osteotomia, identificação do ápice radicular, apicectomia, remoção de tecido inflamatório, observação da superfície remanescente da raiz, retropreparo, obturação retrógrada e sutura. Objetivo: o objetivo do presente artigo é apresentar todos os passos da microcirurgia parendodôntica moderna e descrever os novos recursos disponíveis no mercado para melhorar a taxa de sucesso dessa modalidade. Conclusão: o uso de técnicas modernas de microcirurgia parendodôntica melhora significativamente as taxas de sucesso da terapia, quando comparada às técnicas tradicionais.

Evaluation of the physicochemical properties of silicone- and epoxy resin-based root canal sealers

Abstract To assess the physicochemical properties of AH Plus, GuttaFlow 2, GuttaFlow BioSeal, and MM Seal, five samples of each root canal sealer were evaluated to determine their setting time (ST), dimensional change (DC), solubility (SL), flow (FL), and radiopacity (RD) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. The distilled and deionized water obtained from the SL test were subjected to atomic absorption spectrometry to observe the presence of Ca2+, K+, and Na+ ions. Statistical analysis was performed by using one-way ANOVA and Tukey-Kramer tests (p < 0.05). The following results were obtained: ST (min) (AH Plus 463.6 ± 13.22; GuttaFlow 2 24.35 ± 2.78; GuttaFlow Bioseal 17.4 ± 0.55; MM Seal 47.60 ± 4.39), DC (%) (AH Plus 0.06 ± 0.12; GuttaFlow 2 −26.06 ± 1.24; GuttaFlow Bioseal 2.10 ± 1.47; MM Seal 8.47 ± 2.41), SL (%) (AH Plus 0.41 ± 0.21; GuttaFlow 2 5.13 ± 4.11; GuttaFlow Bioseal 3.03 ± 1.05; MM Seal 0.94 ± 0.17), FL (mm) (AH Plus 36.42 ± 0.40; GuttaFlow 2 36.44 ± 0.05; GuttaFlow Bioseal 35.4 ± 0.03; MM Seal 52.75 ± 0.60), and RD (mmAl) (AH Plus 7.52 ± 1.59; GuttaFlow 2 6.85 ± 0.14; GuttaFlow Bioseal 7.02 ± 0.18; MM Seal 3.32 ± 0.90). ST, DC, SL, FL, and RD showed statistical differences among the root canal sealers (p < 0.05). As AH Plus showed the lowest DC and SL values (p < 0.05), the findings indicate that this sample is the only sealer conforming to ANSI/ADA standards.