Influence of bioceramic cones on the quality of root canal filling relative to bond strength and adaptation of the adhesive interface.

AIM: To evaluate the bond strength (BS) and analysis of the adhesive interface in root canals filled with bioceramic gutta percha sealers and cones. MATERIAL AND METHODS: Ninety-six maxillary canines were divided into eight groups according to the endodontic sealer (AH Plus, AH Plus Bioceramic, Bio-C Sealer or Bio-C Sealer Ion+ and gutta percha cones (conventional or bioceramic) tested. They were analyzed using the BS test, failure pattern, analysis of the adhesive interface by scanning electron microscopy and confocal laser scanning microscopy. The BS data were compared between groups using the analysis of variance test with the Turkey post-test. The chi-square test was used to assess the type of failure and the non-parametric Mann-Whitney and Kruse-Wallis tests (P < 0.05). RESULTS: Analysis of variance showed higher BS values for the groups of bioceramic gutta percha cones in Bio-C Sealer Ion+ (8.38 ± 4.27), AH Plus Bioceramic (6.19 ± 3.28), Bio-C Sealer (5.70 ± 3.18), AH Plus (4.61 ± 2.11) and for conventional gutta percha cones in AH Plus sealers (4.26 ± 2.35), Bio-C Sealer Ion + (3.63 ± 2.29), Bio-C Sealer (2.94 ± 2.32) and AH Plus Bioceramic (1.19 ± 0.89) (P < 0.05). Relative to the type of failure and adaptation of the types of filling material, a higher percentage of mixed failures was observed (gaps between 1 µm-10 µm) for the group with bioceramic gutta percha cones (P < 0.001). CONCLUSION: The bond between sealers and bioceramic gutta percha cones showed higher bond strength values and greater penetration into the dentin tubules. CLINICAL RELEVANCE: The filling the root canal system with bioceramic sealers should be associated with bioceramic gutta percha cones.

Impact of several NiTi-thermally treated instrumentation systems on biomechanical preparation of curved root canals in extracted mandibular molars.

AIM: To evaluate the shaping ability of several heat-treated nickel-titanium systems used to prepare root canals with moderate and severe curvature, in extracted mandibular molars, by micro-computed tomography, considering their variation in kinematics and design. METHODOLOGY: Curved-mesial roots of mandibular molars were randomly selected and assigned into 4 balanced experimental groups (n = 10), established by determining homogeneous 3D parameters of volume and surface area: R-Motion (RM) size 30, 0.04 taper (RM; FKG Dentaire), Reciproc Blue (RCB) size 25, 0.08 taper (RCB; VDW GmbH), HyFlex CM (HFX) size 30, 0.04 taper (HFX; Coltène Whaledent) and XP-endo Shaper size (XPS) 30, 0.01 taper (XPS; FKG Dentaire). The volume of irrigation was established at 10 ml of 2.5% NaOCl. Throughout the entire root canal preparation procedures, the samples were fixed in a vice submerged in a container with water monitored at 37°C. Dimensional cross-sectional measures of area, perimeter, roundness, major/minor diameters and 3-dimensional (volume, surface area, structure model index - SMI) parameters as well as the smallest dentine thickness along the cervical and middle root thirds were evaluated by micro-CT. Data were analysed using analysis of variance and post hoc Tukey tests (α = 5%). RESULTS: Reciproc Blue and XPS had significantly greater mean increases in cross-sectional area measurements, only in the middle third, when compared with RM and HFX (p < .05). RM, RCB and XPS had a similar increase in measurements of length and width of perimeter (p > .05), and HFX had significantly lower mean increases in perimeter values only when compared with XPS (p < .05). RCB and XPS had significantly greater mean increases in volume when compared with RM and HFX (p < .05). RM had a significantly lower difference in SMI after preparation, compared with RCB, HFX and XPS (p < .05). The smallest dentine thickness was observed after the use of RCB (p < .05), in the danger and safety zones. CONCLUSIONS: XP-endo Shaper and RM had a shaping ability similar to that of instruments with larger tapers, achieved with less dentine removal in danger and safe zones in curved-mesial canals of extracted molar teeth treated on a laboratory benchtop.

A Fluorescence-based Method to Reaccess Root Canals in Endodontically Treated Teeth: A Micro-Computed Tomography Tridimensional Assessment.

INTRODUCTION: The aim of this study was to evaluate the volume of dentin removal and the volume of remnants of restorative material after the removal of an esthetic restorative coronal set and cervical barrier in endodontically treated mandibular molars with the aid of different magnification methods using 3-dimensional (3D) micro-computed tomographic (micro-CT) morphometric analysis. METHODS: A sample of 30 mandibular first molars (N = 30) was used. All teeth were endodontically treated, and the specimens were initially scanned using micro-CT imaging and reconstructed. The molars were filled by a single-cone technique, and immediately the material at the initial 2-mm cervical level was removed. Cervical barriers were confected using ionomer glass cement with fluorescein 0.1%, filling the 2 mm at the cervical level of the canals and an additional 2 mm as the base. The coronal restoration set was performed using esthetic resin composites. A simulated tooth aging process was performed with 20,000 thermocycling cycles. The sample was distributed into the following 3 groups (n = 10) for the removal of the restoration set and cervical barrier with diamond burs based on the magnification aid: no magnification aid (naked eye), operative microscope aid, and REVEAL device (Design for Vision Inc, Bohemia, NY) aid. After removal, the final 3D micro-CT scanning and reconstruction were conducted with the same parameters as the initial scanning, and superposition of the final and initial scanning was performed. Morphometric analysis was conducted using CTAn software (Bruker microCT, Kontich, Belgium) to assess the volume of remnant restorative material (mm³), the volume of dentin removal (mm³), and the direction and site of dentin removal. Data were analyzed using 1-Way analysis of variance (P < .05). RESULTS: The REVEAL group showed better results regarding the volume of remnant material (3.17 ± 1.65) and the percentage of dentin removal (2.56 ± 1.34). The microscope group showed no statistical difference compared with the REVEAL group regarding dentin removal (3.30 ± 1.48) and was statistically similar to the naked eye group in the volume of remnant material (9.63 ± 4.33). The naked eye group showed the worst results for the volume of remnant material (7.60 ± 2.68) and the percentage of dentin removal (6.60 ± 3.70). CONCLUSIONS: The use of fluorescence associated with magnification was the method that presented the best results, with lower percentages of dentin removal and smaller volumes of remaining restorative material. This is an innovative technology in endodontics that shows potential to overcome the challenge of reaccessing root canals in the context of endodontic retreatment.

Influence of initial root canal treatment on intratubular penetrability and bond strength of nonsurgical retreatment: an in vitro study.

AIM: To assess the effect of combinations of two different endodontic sealers used in initial and endodontic retreatment on the bond strength of the secondary obturation and the penetrability of the sealers. METHODS: Forty-eight mandibular premolars were used, receiving standardized endodontic access and biomechanical preparation. Twenty-four teeth received AH Plus sealer (AHP) in primary obturation, and the others received Bio-C® Sealer (BCS) sealer. Retreatment protocol was performed with an R50 instrument. The samples were further subdivided into four groups (n=12) based on the combination of primary/secondary obturation sealers: AHP/AHP; AHP/BCS; BCS/AHP; BCS/BCS. Four samples from each subgroup received the addition of fluorophores to the sealer for penetrability analysis using laser scanning confocal fluorescence microscopy (LSCFM). The root portion on the 8 push-out samples was sectioned into 6 slices of 1.0 mm. Bond strength (BS) was assessed using a universal testing machine until displacement of the filling mass. Failure pattern was evaluated under a stereomicroscope (20x magnification). BS data were analyzed using two-way ANOVA followed by Tukey's test (p<0.05), and the association between the failure pattern and BS value was assessed using the chi-square test (p<0.05). Penetrability was qualitatively evaluated. RESULTS: The highest BS values were observed in the AHP/AHP (4.54±1.5 MPa) and BCS/AHP (5.00±1.0 MPa) groups (p<0.05), with a higher percentage of adhesive failures to the filling material for all groups. LSCFM images indicated greater penetrability of AHP compared to BCS, both in initial treatment and retreatment. CONCLUSION: AHP sealer exhibited higher BS and greater penetrability compared to BCS sealer.

Physicochemical properties of calcium silicate cement based endodontic sealers.

AIM: To mensure the physicochemical properties of three ceramic cement endodontic sealers AH Plus Bioceramic, Bio-C Sealer and Bio-C Sealer Ion+ with an epoxy resin sealer, AH Plus. MATERIAL AND METHODS: These properties were measured: hardening time (HT), dimensional change (DC), solubility (SL), flow (FL) and radiopacity (RD). The distilled water obtained from the SL test was analyzed with atomic absorption spectrometry. A sample calculation was made considering n = 5 repetitions for each experimental sealer evaluated. Statistical analysis was performed using one-way ANOVA and post hoc Tukey tests (p < 0.05). RESULTS: For the HT, AH Plus (484 ± 2.76 min) and AH Plus Bioceramic (424 ± 1.23 min) set more slowly than of Bio-C Sealer (370 ± 4.50 min) and Bio-C Sealer Ion+ (380 ± 1.42 min) (p < 0.05). AH Plus Bioceramic (12.56 ± 2.71 %) was more soluble than Bio-C Sealer (6.69 ± 1.67 %), Bio-C Sealer Ion+ (5.67 ± 2.16 %) and AH Plus (0.15 ± 0.01 %) (p < 0.05). AH Plus (0.03 ± 0.01 %) had slight expansion while the cement-based sealers had shrinkage: AH Plus Bioceramic (-1.60 ± 0.63 %) and Bio-C Sealer (-1.38 ± 0.69 %), Bio-C Sealer Ion+ (-5.19 ± 1.23 %) (p < 0.05). Bio-C Sealer Ion+ (59.80 ± 0.86 mm) and Bio-C Sealer (58.60 ± 0.98 mm) had the highest flow compared with AH Plus (56.90 ± 0.56 mm) and AH Plus Bioceramic (49.50 ± 0.63 mm) (p < 0.05). AH Plus (9.17 ± 0.06 mmAl) and AH Plus Bioceramic (8.27 ± 0.84 mmAl) showed radiopacity values when compared with those of Bio-C Sealer (4.90 ± 0.08 mmAl) and Bio-C Sealer Ion+ (4.14 ± 0.05 mmAl) (p > 0.05). CONCLUSION: Ion release is inhered to these cement-based sealers and this result in calcium ion release.

Evaluation of rotary instruments with whipping motion in the biomechanical preparation of large root canals of young permanent teeth.

Shaping ability evaluation of taper ./01 instruments in large root canals, by microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Maxillary central incisors with large diameter root canals were divided into two groups (n = 10): XP-Endo Shaper (FKG-Dentaire, Switzerland) and manual instrumentation (FKG-Dentaire). Two- and three-dimensional parameters from cervical to apical root thirds were evaluated by micro-CT. Apical stop was evaluated by SEM images. Data were analysed by ANOVA and Tukey tests (α = 5%). XP-Endo Shaper allowed a regular biomechanical preparation with less dentinal wear compared with manual instrumentation, which showed excessive wear of the thin root canal walls (p < 0.05). Roundness and SMI showed similarity between both protocols (p > 0.05). XP-Endo Shaper SEM showed a regular and well-defined shape of the apical foramen suggesting the formation of the apical stop. Reduced diameter and taper instruments promoted a conservative wear and a well-defined apical stop formation in large root canals.

Canal Drying Protocols to Use with Calcium Silicate-based Sealer: Effect on Bond Strength and Adhesive Interface.

INTRODUCTION: The aim of this study was to evaluate the influence on bond strength and interface quality of different canal drying protocols in roots filled with Bio-C Sealer (BCS; Angelus, Londrina, Paraná, Brazil). METHODS: Ninety-six roots of upper canines were prepared with an R50 file (Reciproc; VDW GmbH, Munich, Germany) and irrigated with 2.5% sodium hypochlorite and 17% EDTA under ultrasonic agitation. Roots were divided according to the drying protocol as follows: dry, the White Mac tip (Ultradent, Indaiatuba, SP, Brazil) for 5 seconds followed by aspiration with a capillary tip for 5 seconds and paper points; slightly moist, the White Mac tip followed by capillary aspiration without paper points; wet, the White Mac tip followed by a single paper point. The roots were filled with BCS or AH Plus (AHP; Dentsply Maillefer, Ballaigues, Switzerland) (n = 16) and sectioned for the push-out test after 3 months. Failure modes were assessed, and the interface morphology was analyzed under scanning electron microscopy. After 6 months, the other half of the roots were evaluated. Data were analyzed by analysis of variance/Tukey test at 5%. The chi-square test was used in the failure analysis and the Kruskal-Wallis/Dwass-Steel-Critchlow-Fligner for interface analysis. RESULTS: The AHP-filled roots had the highest bond strength when the canal was dried (P < .05). No difference was found for periods (P > .05). For BCS, the highest bond strength was found in the slightly moist canals (P < .05). A predominance of adhesive failures was observed. The dried canals filled with AHP had the highest percentage of good adaptation, whereas BCS had no difference. CONCLUSIONS: The best drying protocol for AHP is using the White Mac tip followed by capillary tip aspiration and paper points until complete dryness, and for BCS, it is using the White Mac tip followed by capillary aspiration without paper points.

Evaluation of 2- and 3-dimensional anatomic parameters of C-shaped root canals with cone beam computed tomography, microcomputed tomography, and nanocomputed tomography.

OBJECTIVE: The objective of this study was to evaluate 2-dimensional (2D) and 3D morphometric parameters of C-shaped root canals on cone beam computed tomography (CBCT) and microcomputed tomography (microCT) images using nanocomputed tomography (nanoCT) as the reference standard. STUDY DESIGN: Sixty mandibular molars with C-shaped canals were individually scanned using nanoCT and microCT. Cone beam computed tomography acquisitions were then performed with 4 CBCT systems, using high and standard resolutions. The 2D parameters of roundness and major and minor diameters were obtained in the cross sections of the root canals at 1, 2, and 3 mm from the root apex. The 3D parameters of surface area, volume, and structure model index were measured considering the entire extension of the root canals. Absolute error (AE) in measurement was calculated against the nanoCT values. Data were statistically analyzed with the Shapiro-Wilk test and analysis of variance (α = 0.05). RESULTS: No significant differences in AE were discovered for the 2D parameters among microCT and the CBCT scans. The AE values for the 3D parameters of volume and surface area were significantly smaller in microCT compared to all CBCT units (P < .05). Significantly lower AE values for surface area were observed in high resolution compared to standard resolution for all CBCT units (P < .05). Structure model index did not differ significantly among microCT and all CBCT protocols. CONCLUSIONS: Cone beam computed tomography images showed accuracy for evaluating 2D parameters and over- and underestimation for 3D parameters.

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

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.

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

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.

Natural history of the Neotropical arboreal ant, Odontomachus hastatus: nest sites, foraging schedule, and diet.

The ecology of most arboreal ants remains poorly documented because of the difficulty in accessing ant nests and foragers in the forest canopy. This study documents the nesting and foraging ecology of a large (∼13 mm total length) arboreal trap-jaw ant, Odontomachus hastatus (Fabricius) (Hymenoptera: Formicidae) in a sandy plain forest on Cardoso Island, off the coast of Southeast Brazil. The results showed that O. hastatus nested in root clusters of epiphytic bromeliads, most commonly Vriesea procera (70% of nest plants). Mature O. hastatus colonies include one to several queens and about 500 workers. Foraging by O. hastatus is primarily nocturnal year-round, with increased foraging activity during the wet/warm season. The foragers hunt singly in the trees, preying on a variety of canopy-dwelling arthropods, with flies, moths, ants, and spiders accounting for > 60% of the prey captured. Although predators often have impacts on prey populations, the ecological importance of O. hastatus remains to be studied.

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

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.

Quantitative Assessment of 2-dimensional Parameters in Tomographic Images by Using Different Segmentation Methods.

INTRODUCTION: The purpose of this study was to assess the accuracy of 2-dimensional morphometric parameters of root canals on different cone-beam computed tomographic (CBCT) images using 2 segmentation methods (operator dependent and Otsu's automatic), considering micro-computed tomographic (micro-CT) images as the reference standard. METHODS: Ten mandibular molars were scanned by micro-CT imaging and 3 different CBCT devices: Accuitomo (J Morita Corporation, Kyoto, Japan), NewTom 5G (CEFLA, Imola, Italy), and NewTom VGi evo (CEFLA). The images were standardized and recorded using MeVisLab software (MeVis Medical Solutions AG, Bremen, Germany). Two calibrated examiners assessed the images of axial reconstructions quantitatively by 2-dimensional parameters (area, perimeter, roundness, and largest and smallest diameter). Fleiss kappa was performed to check interrater and intrarater reliability. The absolute error was calculated as the means and standard deviation. One-way analysis of variance was performed for comparison between the methods used by the operator and Otsu's automatic thresholding. To determine the accuracy of CBCT devices, the absolute error rate of each parameter was calculated using micro-CT measurements as the reference value with thresholding determined by the operator. RESULTS: The thresholding method performed by the operator had lower absolute error values for area, perimeter, and major and minor diameters, differing (P < .05) from Otsu's automatic method, with no differences between the CBCT machines. CONCLUSIONS: An overestimation of area, roundness, and major and minor diameters and an underestimation of the perimeter were shown for the 3 CBCT machines evaluated. Thresholding determined by the operator is more accurate than that determined by Otsu's automatic method for the assessment of 2-dimensional morphometric parameters, which could direct influence in the diagnosis and endodontic treatment plan.

Management of a perforating internal root resorption using mineral trioxide aggregate: a case report with 5-year follow-up.

Internal root resorption is characterised by progressive loss of tooth substance initiating at the root canal wall as a result of clastic activity. This report describes a case of a perforating internal root resorption on a maxillary central incisor in a 25-year-old patient. The perforating internal root resorption was firstly diagnosed with periapical radiographs and assessed with full detail with the aid of CBCT, allowing determination of the extension and areas involved in the resorption lesion, as well as the treatment planning. According to these findings, a MTA barrier was performed on the root, -coronally to the resorption lesion, leaving the root apically to the resorption lesion untouched. Clinical findings and periapical radiographs indicated complete resolution of the radiolucency associated with the resorptive defect, with reestablishment of lamina dura along the root and occlusion of the lumen of the root canal in the apical segment, after a 5-year follow-up.

Happiness among dentists: a multi-scale, multi-national study from 21 countries.

OBJECTIVES: The extent to which dentists are happy with their profession and their life has not been well studied. The present study aimed to explore the level of happiness, satisfaction with life and psychological well-being among a sample of dental professionals from 21 countries. MATERIALS AND METHODS: The sample comprised 2,200 dentists from 21 countries. Three scales - Subjective Happiness Scale (SHS), Satisfaction With Life Scale (SWLS), and Affect Balance Scale (ABS) - were used to measure the subjective responses. Data related to demographic and social characteristics were recorded. Mann-Whitney and Kruskal-Wallis tests were used as appropriate. Scales were correlated, and multiple linear regression analyses were employed to identify the independent determinants of SHS, SWLS and ABS. Data were analysed using the SPSS software program; a value of P <0.05 was considered significant. RESULTS: The overall mean scores of SHS, SWLS and ABS were 18.53 ± 5.06, 23.06 ± 6.25 and 1.26 ± 2.40, respectively, with significant differences found across countries: dentists working in Croatia, Peru and Serbia recorded the highest scores, unlike dentists practicing in Yemen, Syria, and Iraq, who recorded the lowest scores. There were significant, moderately positive correlations between the various scales: SHS and SWLS: r = 0.535, P < 0.001; SHS and ABS: r = 0.58, P < 0.001; and SWLS and ABS: r = 0.533, P < 0.001. Country of practice, age, qualification and monthly income were the significant independent predictors of SHS, SWLS and ABS. CONCLUSION: Country of residence and social characteristics were associated with dentists' responses regarding their feelings and subjective well-being.

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.

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.

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

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.

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.

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.