Experimental Periodontitis Worsens Dopaminergic Neuronal Degeneration.

AIM: To investigate the hypothesis supporting the link between periodontitis and dopaminergic neuron degeneration. MATERIALS AND METHODS: Adult male Wistar rats were used to induce dopaminergic neuronal injury with 6-hydroxydopamine (6-OHDA) neurotoxin and experimental periodontitis via ligature placement. Motor function assessments were conducted before and after periodontitis induction in controls and 6-OHDA-injury-induced rats. Tissue samples from the striatum, jaw and blood were collected for molecular analyses, encompassing immunohistochemistry of tyrosine hydroxylase, microglia and astrocyte, as well as micro-computed tomography, to assess alveolar bone loss and for the analysis of striatal oxidative stress and plasma inflammatory markers. RESULTS: The results indicated motor impairment in 6-OHDA-injury-induced rats exacerbated by periodontitis, worsening dopaminergic striatal degeneration. Periodontitis alone or in combination with 6-OHDA-induced lesion was able to increase striatal microglia, while astrocytes were increased by the combination only. Periodontitis increased striatal reactive oxygen species levels and plasma tumour necrosis factor-alpha levels in rats with 6-OHDA-induced lesions and decreased the anti-inflammatory interleukin-10. CONCLUSIONS: This study provides original insights into the association between periodontitis and a neurodegenerative condition. The increased inflammatory pathway associated with both 6-OHDA-induced dopaminergic neuron lesion and periodontal inflammatory processes corroborates that the periodontitis-induced systemic inflammation may aggravate neuroinflammation in Parkinson's-like disease, potentially hastening disease progression.

Metal artifact reduction tool and mA levels impact on the diagnosis of fracture extension in endodontically treated teeth using cone-beam CT.

AIM: To evaluate the influence of different levels of metal artifact reduction (MAR) tool and milliamperage (mA) on the diagnosis of fracture extension in endodontically treated teeth using cone beam CT (CBCT). MATERIALS AND METHODS: Ten maxillary premolars were endodontically treated and positioned in the empty sockets of a human maxilla covered with wax. CBCT acquisitions were performed using the Eagle Edge device (Dabi Atlante, Brazil) adjusted to 120 kVp, FOV of 4 × 6 cm, exposure time of 24 s and voxel size of 0.2 mm in 8 different conditions with different MAR (1, 2 and 3) and mA (3.2 and 6.3) levels. Crown-root fractures were simulated in the universal testing machine, and CBCT images were acquired again. Five radiologists evaluated the presence and extension of fractures with a 5-point scale. Statistical analysis was performed by analysis of variance, Tukey and Kappa test (α = 0.05). RESULTS: Although different mA levels did not significantly (p > 0.05) affect the diagnosis values for fracture presence and extension, when evaluated the different levels of MAR, AUC and sensitivity showed significantly higher values (p < 0.05) for MAR 0 using 6.3 mA and kappa agreement showed significantly higher values (p < 0.05) for MAR 0 and 2 using 6.3 mA. CONCLUSIONS: Although mA levels do not have a diagnostic effect when isolating the MAR level; in 6.3 mA, MAR 0 and 2 can positively influence the diagnosis of fracture extension in endodontically treated teeth using CBCT. CLINICAL RELEVANCE: The isolate evaluation of dental fracture presence can overlook diagnostics error of its extension.

Impact of low-fusion gutta-percha cones used in variations of the continuous wave condensation technique with filling sealers based on bioceramic compounds on the quality of root canal filling.

To evaluate the impact on the quality of filling with of low-fusion and conventional gutta-percha cones. Thirty-six maxillary canines were prepared and divided into three groups: I-conventional cone with Downpack at 200 °C at 4 mm from the WL; II-low-fusion cone with Downpack at 100 °C up to 4 mm from the WL; III-low-fusion cone with Downpack at 100 °C up to 7 mm from the WL. Temperature variations were measured in thirds on the external surface of the root. The bond strength was evaluated using the push-out test. The adhesive interface was analyzed by scanning electron microscopy. The bond strength and the temperature variation data were analyzed using analysis of variance and the failure type using the chi-square test. The low-fusion cone group with 7 mm Downpack showed higher bond strength (4.2 ± 2.7) compared with conventional cones (2.8 ± 1.6) and low-fusion cones with 4 mm Downpack (2.9 ± 1.6) (p < 0.05), with occurrence of a higher number of adhesive failures to the filling material and mixed failures. Relative to temperature variation, there was less temperature change in the apical third, in the low-fusion cone with Downpack 7 mm (1.0 ± 1.0) (p < 0.05). The use of low-fusion cones allowed the continuous wave condensation technique to be performed at a lower depth of Downpack at 100 °C at 7 mm, with less heating in the apical third, without compromising the quality of filling. Using gutta-percha cones with low fusion, which permits a lower condensation temperature and reduced Downpack depth, maintains the quality of filling, in order to minimize possible damage to the periapical tissues.

Identification and classification of pulp calcifications in posterior teeth according to dental condition using digital panoramic radiography and cone beam CT.

OBJECTIVE: To compare digital panoramic radiography (DPR) and cone beam CT (CBCT) in the detection and classification of pulp calcifications in posterior teeth in relation to tooth condition and its location. METHODS: Two hundred and fifty patients with simultaneous DPR and CBCT scans were selected from a dental image bank. For each posterior tooth, its condition was registered (healthy, restored, or decayed). The presence of calcifications was assessed and classified according to location (coronal or radicular) and type (total obliteration, partial obliteration, narrowing, and no calcification). Chi-square and McNemar tests were used to compare DPR and CBCT results, with a significance level of 5%. DPR diagnostic values were calculated using CBCT as reference. RESULTS: Decayed and restored teeth showed a significantly (P < .001) higher prevalence of pulp calcifications than healthy teeth in both imaging exams. There was a significant discrepancy between the imaging modalities in the identification of calcifications (P < .001), especially for radicular calcifications of maxillary teeth (DPR = 55.2%; CBCT = 30.9%). In the case of coronal calcifications, there was a greater discrepancy between CBCT and DPR in the mandibular teeth (10.7%) than in the maxillary teeth (7.7%). Overall, DPR presents higher sensitivity (0.855) than specificity (0.483) for pulp calcifications detection. CONCLUSION: DPR considerably overestimates pulp calcifications in posterior teeth, as compared to CBCT. A higher prevalence of pulp calcifications is related to decayed and restored teeth.

Genetic polymorphism in the tumour necrosis factor alpha gene (G-308A) is associated with persistent apical periodontitis in Brazilians.

AIM: To investigate if there was an association between genetic polymorphisms in tumour necrosis factor (TNF)-⍺ and its receptors TNFRSF1A and TNFRSF1B with persistent apical periodontitis (PAP) in Brazilian subjects. METHODOLOGY: Patients who had pulpal necrosis and apical periodontitis at the time of treatment, with at least 1-year of follow-up after non-surgical root canal treatment were recalled. Three hundred and seventy eight subjects were included, 150 subjects with signs/symptoms of PAP and 228 subjects with root canal-treated teeth exhibiting healthy perirradicular tissues (healed). Genomic DNA was extracted from saliva and used for TNF-⍺ (rs1800629), TNFRSF1A (rs1800693) and TNFRSF1B (rs1061622) genotyping by real-time PCR. Genotypes and alleles frequencies were evaluated by c2 or Fisher's exact tests and odds ratios were implemented (α = 5%). RESULTS: The genetic polymorphism in TNF-α (rs1800629) was associated as a protective factor for the development of PAP (p < .05), once subjects who presented at least one allele A (AA+AG X GG), had a higher chance to lesion repair (p < .05). The polymorphisms rs1800693 and rs1061622 in TNF receptors (TNFRSF1A and TNFRSF1B, respectively) were not associated with the development of PAP (p > .05). CONCLUSIONS: The observed results demonstrate that polymorphism in TNF-α but not in its receptors is associated with PAP.

Association between single-nucleotide polymorphisms in serotonin receptor 2A and melatonin receptor 1A genes and pain after root canal treatment.

AIM: This study aimed to investigate whether single-nucleotide polymorphisms (SNPs) in the genes encoding 5-HTR2A (5-Hydroxytryptamine (serotonin) receptor 2A) and MTNR1A (melatonin receptor 1A) may contribute to postoperative pain perception after root canal treatment. We hypothesised that SNPs in HTR2A and MTNR1A genes were associated with postoperative pain after root canal treatment. METHODOLOGY: This genetic cohort study enrolled patients with single-rooted teeth diagnosed with pulp necrosis and asymptomatic apical periodontitis before root canal treatment. Root canal treatment was performed in one session using a standardized protocol. Postoperative pain and tenderness were assessed using a visual analogue scale (recorded every day for 7 days and on the 14th and 30th days after root canal treatment). Genomic DNA was extracted from saliva and used to genotype the SNPs in HTR2A (rs4941573 and rs6313) and MTNR1A (rs6553010, rs6847693 and rs13140012) using real-time polymerase chain reaction. Genotypes were compared using univariate and multivariate Poisson regression with generalized estimating equations (p < .05). RESULTS: In total, 108 patients were enrolled in this study. The SNPs rs6553010 (MTNR1A), rs4941573 and rs6313 (HTR2A) were associated with an increased risk of developing pain after root canal treatment (p < .05). CONCLUSIONS: This study suggests that SNPs in HTR2A and MTNR1A influence pain response after root canal treatment.

Adjuvant therapy with a 980-nm diode laser in root canal retreatment: randomized clinical trial with 1-year follow-up.

The purpose of this study is to assess the laser effect in root canal disinfection and periapical healing of endodontically treated teeth from patients with asymptomatic apical periodontitis. This study was performed as a randomized clinical trial. Thirty patients were selected according to the inclusion/exclusion criteria. Fifteen patients received the root canal retreatment (RCR) combined with 980-nm diode laser irradiation (LI). The canals were irrigated with saline solution and gently dried with paper points, keeping the dentin partially moist. The irradiation was performed using a 320-µm-diameter fiber in helicoidal movements (pulsed mode, power output of 1.5 W, 100 Hz for 20 s). The other 15 patients received the RCR with placebo irradiation (PI). Microbiological samples were taken in three periods: S1, after the filling material removal (baseline); S2, after laser or placebo irradiation (LI or PI); and S3, after the RCR followed by laser or placebo. The samples were submitted to the total microbial and E. faecalis counting. The periapical radiographic healing was analyzed after 3, 6, 9, and 12 months. Microbiological data (CFU/mg) were analyzed by ANOVA and Tukey's test (P < 0.05), and the repair by Mann-Whitney test (P < 0.05). In S2, the laser provided 42.44% microbial reduction and 53.14% of E. faecalis, different from the placebo that had no reduction, and 4.85% for Enterococcus (P < 0.05). In S3, the bacterial counts decreased without differences between groups. No differences in healing were found at 3 months. However, diode laser facilitated the repair from 3- to 12-month follow-up (P < 0.05) and had 45% more healed cases than placebo. Diode laser provided an antimicrobial effect before the biomechanical preparation but was not synergistic in RCR. It improved the periapical healing during follow-up.

Assessment of the root filling volume in C-shaped root canal on cone-beam CT and micro-CT in relation to nano-CT.

AIM: To assess the observed volume of filled C-shaped root canals from different CBCT and micro-CT having nano-CT as a reference. MATERIALS AND METHODS: Twelve extracted mandibular molars with C-shaped root canals were endodontically treated using Reciproc Blue R25 (VDW GMBH, Munich, Germany) in a reciprocating system and filled with gutta-percha (Dentsply Maillefer) and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). CBCT scans were performed using 3 units-3D Accuitomo 170 (J. Morita, Kyoto, Japan), ProMax 3D Max (Planmeca, Helsinki, Finland), and NewTom VGi EVO (Cefla QR, Verona, Italy)-at two resolution modes: standard and high. Micro-CT and nano-CT scans were also obtained. The volume of all filled C-shaped root canals was obtained using CTAn software (Bruker, Kontich, Belgium), and the blooming artifact, in relation to nano-CT volume, was calculated. The data were evaluated by the Bland-Altman plots and ANOVA two-way for repeated measures (α = 0.05). RESULTS: All CBCT units and micro-CT showed significantly larger observed volume of root canal filling when compared to nano-CT. The blooming artifact of root canal filling in standard resolution was significantly larger than that in high resolution (p < 0.05) in all CBCT units. CONCLUSIONS: Endodontic filling material with AH Plus sealer causes blooming artifacts in CBCT units and micro-CT. CLINICAL RELEVANCE: Considering the anatomical complexity of C-shaped root canals and the challenges associated with endodontic treatment, CBCT is frequently recommended for follow-up evaluations. However, the presence of endodontic filling material can result in blooming artifacts that may potentially impact the accurate diagnosis of endodontic complications.

Impact XP-endo finisher on the 1-year follow-up success of posterior root canal treatments: a randomized clinical trial.

OBJECTIVE: To evaluate the clinical relevance of using the XP-endo Finisher as a supplementary tool to improve the success of root canal treatment of posterior teeth with apical periodontitis, as assessed by 1-year follow-up. METHODS: A randomized clinical trial was conducted with 92 posterior teeth with apical periodontitis. Root canal treatment was performed using a single reciprocating file, with or without the supplementary use of the XP-endo Finisher. The status of apical periodontitis was assessed using the periapical index (PAI) at baseline and 1 year follow-up. Changes on PAI indicated that the lesions were healed, healing, or not healed. Successful treatments were defined as healed or healing lesions without clinical symptoms. Chi-square analysis and logistic regression were used for data analysis (α = 0.05). RESULTS: There was no significant difference in the distribution of healing status between the XP-endo Finisher group and the control group (p = 0.690). The success rates were also similar, with 81% in the XP-endo Finisher group and 78% in the control group. However, gender had a significant impact on success rates, with higher rates observed in females. CONCLUSIONS: The use of the XP-endo Finisher file as a supplementary tool did not affect the success rate of root canal treatment in posterior teeth with apical periodontitis. The findings indicate that the XP-endo Finisher file has limited clinical relevance in improving treatment outcomes for root canal treatment in posterior teeth with apical periodontitis. CLINICAL TRIAL REGISTRATION: The study protocol was registered in the Brazilian Clinical Trials Registry under identification number RBR-76w7cj (June 19, 2018).

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.

Systemic inhibition of 5-lipoxygenase by MK-886 exacerbates apical periodontitis bone loss in a mouse model.

BACKGROUND: To investigate if 5-LO selective inhibitor (MK-886) could be used for systemic treatment of experimentally induced apical periodontitis in a mouse model. METHODS: Twenty-four C57BL/6 mice were used. After coronal opening, a solution containing Escherichia coli LPS (1.0 µg/µL) was inoculated into the root canals of the lower and upper right first molars (n = 72 teeth). After 30 days apical periodontitis was established, and the animals were treated with MK-886 (5 mg/kg), a 5-LO inhibitor, for 7 and 14 days. The tissues were removed for histopathological and histometric analyses, evaluation of osteoclast number and gene expression for receptor activator of nuclear factor kappa-B (Tnfrsf11a), receptor activator of nuclear factor kappa-B ligand (Tnfsf11), osteoprotegerin (Tnfrsf11b), tartrate-resistant acid phosphatase (Acp5), matrix metalloproteinase-9 (Mmp9), cathepsin K (Ctsk) and calcitonin receptor (Calcr). Statistical data analysis was performed using Kruskal Wallis followed by Dunn's tests (α = 0.05). RESULTS: Administration of MK-886 for 7 days exerted no effect on apical periodontitis progression compared to LPS inoculation without treatment (p = 0.3549), while treatment for 14 days exacerbated bone loss (p < 0.0001). Administration of MK-886 enhanced osteoclastogenesis signaling and osteoclast formation within 7 days (p = 0.0005), but exerted no effect at 14 days (p > 0.9999). After 7 days of treatment, MK-886 induced mRNA expression for Acp5 (p = 0.0001), Calcr (p = 0.0003), Mmp9 (p = 0.0005) and Ctsk (p = 0.0008), however no effect in those gene expression was observed after 14 days (p > 0.05). CONCLUSION: Systemic treatment with MK-886 exacerbated LPS-induced apical periodontitis in a mouse model.

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.

Is the quality of root canal filling obtained by cone-beam computed tomography associated with periapical lesions? A systematic review and meta-analysis.

AIM: To evaluate the influence of root canal filling quality on periapical lesion status using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The bibliographic search was conducted in electronic databases of PubMed, Embase, Scopus, and Web of Science without restrictions related to the year of publication and language. Inclusion criteria were prospective or retrospective cohort studies that followed periapical pathosis for, at least, 1 year. Three reviewers independently evaluated the eligibility for inclusion, extracted data, and assessed the risk of bias. The quality of the studies was based on the Newcastle-Ottawa Scale. This meta-analysis was performed to evaluate the quality of treatment by the homogeneity and apical extension of the filling. RESULTS: Of the 1179 studies initially recovered, six cohort studies were included, out of which four were considered with a low risk of bias. The results showed that the absence of gaps in the filling reduced the chance of unhealed periapical lesions by 2.39 times (RR = 2.39; 95% CI: 1.62-3.53; p < 0.00001; I2 = 55%). An apical filling extension of 0-2 mm below the apex also contributed significantly to the absence of unhealed periapical lesions (RR = 1.49; 95% CI: 1.15-1.94; p = 0.003; I2 = 2%). CONCLUSION: The homogeneity and apical extension of the filling influenced the presence of unhealed periapical lesions in endodontically treated teeth evaluated using CBCT. CLINICAL RELEVANCE: Apical extension of the filling ranging between 0 and 2 mm short of the apical foramen and the homogeneity of the filling without gaps are directly related to the success rate of root canal treatment.

An ultrasonic-based experimental model to evaluate the setting time of endodontic sealers.

AIM: To evaluate an ultrasonic-based experimental model (US), to assess the setting time of AH Plus® , Bio-C Sealer® and MTA Fillapex® , and compare the results obtained with ANSI/ADA specifications (2012). METHODS: To determine the setting time according to the ANSI/ADA specification, moulds measuring 10 mm (diameter) × 2 mm (thickness) were used, and for the US tests a transducer (1 MHz) and an oscilloscope were used. Fourier-transform infrared spectroscopy (FTIR) was used to evaluate the changes on chemical structure at the different setting times found by the US and ANSI/ADA methods. After checking the normal distribution, setting time data were analysed using unilateral analysis of variance with Tukey-HSD post-test to compare the methods. RESULTS: AH Plus® and Bio-C Sealer® had longer mean setting time values for the US method than for the ANSI/ADA (p < .05), whilst for MTA Fillapex® no significant difference was found between the methods (p < .05). FTIR spectra demonstrated that at the setting time determined by the US method, AH Plus® and Bio-C Sealer® were in a more advanced stage of polymerization than at the ANSI/ADA, whilst there was no significant difference for MTA Fillapex® . CONCLUSIONS: The use of US was effective for setting time determination and measured longer values than ANSI/ADA specification for AH Plus® and Bio-C Sealer® , identifying the entire (and not only superficial) setting of the endodontic sealers.

Retreatability of BC Sealer and AH Plus root canal sealers using new supplementary instrumentation protocol during non-surgical endodontic retreatment.

OBJECTIVE: The aim of this study was to evaluate the efficacy of supplementary techniques (ultrasonic tip/XP-endo Finisher R) in removing remaining filling materials (gutta-percha/AHPlus/BCSealer) from oval-shaped root canals during non-surgical endodontic retreatment. MATERIAL AND METHODS: Twenty-eight distal roots of human mandibular molars with single and oval-shaped canals were initially shaped with a R40 instrument and filled with gutta-percha points and AH Plus (n = 14) or BC Sealer (n = 14) followed by an initial micro-CT scanning. Initial filling material removal was performed in all 28 samples with an R50 instrument, and all samples submitted to a second micro-CT. Supplementary techniques with ultrasonic tips or XP-endo Finisher R instruments were performed in each sealer group, and all samples submitted to a third micro-CT. The volume of remaining filling material was calculated for the entire canal as well as for the coronal, middle, and apical thirds. Statistical analyses were performed using T, ANOVA 3-way, and Tukey tests. RESULTS: Lower values of remnant filling material were found for BC Sealer (16.06 ± 14.34) compared to AH Plus (28.30 ± 10.54) (P < 0.001), and considering the supplementary technique, lower values of remnant filling material were found for the ultrasonic tip (18.95 ± 11.05) compared to XP-endo Finisher R (25.41 ± 15.81) (P = 0.025). Ultrasonic instruments significantly reduced the percentage of remaining filling material for both AH Plus (P = 0.04) and BC Sealer (P = 0.02) while XP-endo Finisher R was effective for AHPlus only (P = 0.04). The remaining filling material was observed in all samples regardless the filling material or the supplementary technique employed. CONCLUSIONS: Supplementary techniques increased filling material removal; however, none of them was able to render root canals completely free from root fillings. Ultrasonic tips should be considered a good option for endodontic retreatment, especially for bioceramic cases. CLINICAL RELEVANCE: Supplementary instrumentation techniques are effective tools to reduce the amount of filling materials during root canal retreatment.

Mechanical behavior of endocrowns fabricated with different CAD-CAM ceramic systems.

STATEMENT OF PROBLEM: The mechanical behavior of ceramic endocrowns is unclear. PURPOSE: The purpose of this in vitro and 3-dimensional finite element analysis (3D-FEA) study was to evaluate the mechanical behavior of endodontically treated teeth restored with ceramic endocrowns made by using different computer-aided design and computer-aided manufacturing (CAD-CAM) systems. MATERIAL AND METHODS: Sixty mandibular human molars were endodontically treated, prepared for endocrowns, and divided into 4 groups (n=15) according to the following various ceramic systems: leucite-based glass-ceramic (LC group), lithium disilicate-based glass-ceramic (LD group), glass-ceramic based on zirconia-reinforced lithium silicate (LSZ group), and monolithic zirconia (ZR group). After adhesive bonding, the specimens were subjected to thermomechanical loading and then to fracture resistance testing in a universal testing machine. The failure mode of the specimens was qualitatively evaluated. Three-dimensional FEA was performed to evaluate the stress distribution in each group. Data were analyzed by using a 1-way ANOVA and the Tukey HSD test (α=.05). RESULTS: Statistically significant differences among the groups were observed (P<.05). The outcomes of the LC, LD, and LSZ groups were similar (1178 N, 1935 N, and 1859 N) but different from those of the ZR group (6333 N). The LC and LD groups had a higher ratio of restorable failures, while LSZ and ZR had more nonrestorable failures. Fractographic analysis indicated a regular failure pattern in the ZR group and irregular failure patterns in the other groups. Three-dimensional FEA revealed similar values and stress pattern distributions among the groups. CONCLUSIONS: The mechanical performance of monolithic zirconia was better than that of the other ceramic endocrowns considered in this research; however, monolithic zirconia presented a higher rate of catastrophic tooth structure failure.

Bond strength and quality of bond interface of multifilament fiberglass posts luted onto flat-oval root canals without additional dentin wear after biomechanical preparation.

STATEMENT OF PROBLEM: An intraradicular retainer formed by multiple independent glass fiber filaments was developed aiming to allow better adaptation in flattened root canals; however, the performance of the new posts is unclear. PURPOSE: The purpose of this in vitro study was to compare the bond strength (BS) and adhesive interface quality achieved in flattened root canals restored with conventional glass fiber posts (CFPs) and multifilament glass fiber posts (MFPs). MATERIAL AND METHODS: The distal roots of mandibular molars with long oval root canals were endodontically treated, and the obturation material was removed and assigned to 2 groups (n=11) according to the type of retainer used: CFP (WhitePostDC#0.5; FGM) or MFP (CometTail#4; Synca). The posts were cemented with self-adhesive resin cement. The specimens were sectioned (2 slices per third). The most cervical slice in each third was used to evaluate the BS, while the adhesive interface in the apical slices was analyzed by scanning electron microscopy. BS data were analyzed by using a multilevel generalized linear model, and adhesive interface SEM data were analyzed by using a multilevel ordinal logistic regression model (α=.05). RESULTS: Multilevel regression showed a statistically significant difference for the "type of retainer" factor (P=.001; CFP 2.61 ±1.30>MFP 1.59 ±1.54). No statistically significant differences were found for the "root thirds" factor (P=.346) or for the interaction of both factors (P=.114). The failure pattern was predominantly mixed or adhesive for CFP and adhesive to dentin for MFP. A better adaptation of the restorative material was observed in the cervical third for CFP and in the apical third for MFP (P<.001). CONCLUSIONS: MFP resulted in lower BS values than CFP, with a higher prevalence of adhesive failures to dentin and better adaptation of the adhesive interface in the apical third.

Effect of a chitosan final rinse on the bond strength of root canal fillings.

This study was designed to evaluate the effect of a final rinse with 0.2% chitosan solution on the adhesion in roots filled with gutta percha and an epoxy resin based sealer. Thirty extracted human maxillary canines selected to ensure specimen standardization were used in the study. After the coronal portion of each tooth was removed, the roots were instrumented and irrigated with 1% sodium hypochlorite (NaOCl). Roots were distributed into 3 groups according to the final rinsing solution (n = 10): 0.2% chitosan, 17% ethylenediaminetetraacetic acid (EDTA), or 1% NaOCl. The canals were irrigated with 5 mL of each solution for 5 minutes and then filled with gutta percha cones and the resin based sealer. Ten roots in each group were prepared, sectioned, and submitted to push-out testing. Data were analyzed with analysis of variance and Tukey test (P < 0.05). In the push-out test, final irrigation with chitosan (mean, 0.37 [SD, 0.12] MPa) or EDTA (0.38 [0.11] MPa) resulted in significantly greater bond strength of the sealer to the root canal (P < 0.05) than did irrigation with 1% NaOCl (0.13 [0.04] MPa). The cervical third had greater bond strength than the other thirds (P < 0.05). Adhesive failure was the most frequent type in all groups. A final rinse with 0.2% chitosan or 17% EDTA resulted in greater bond strength of root fillings to the root canal than did 1% NaOCl.

Idiopathic external apical root resorption: clinical report of 2 cases.

External root resorptions are characterized by progressive destruction of hard tissue due to clastic activity. This article reports 2 cases that involved the nonsurgical treatment of mandibular molars with idiopathic external root resorption. In the first case, clinical and radiographic examination showed irreversible inflammation of the pulp tissue and resorption of the distal root. Chronic inflammatory infiltrate and necrosis were identified by histopathologic examination of the pulp tissue. In the second case, inadequate endodontic treatment and a resorptive process were observed in the mesial and distal roots. In both cases, mineral trioxide aggregate (MTA) was used as the filling material. Clinical and radiographic follow-ups of 1 and 7 years, respectively, showed a favorable trend, including interruption of the resorptive process and periradicular normality. More longitudinal studies are necessary to analyze the performance of MTA in treating external root resorptions.

Bond strength of epoxy resin-based root canal sealer to human root dentin irradiated with Er,Cr:YSGG laser.

OBJECTIVE: The aim was to evaluate the influence of Er,Cr:YSGG laser irradiation associated with different final irrigation protocols on the bond strength of epoxy resin-based root canal sealer to root dentin, on the dentin/filling material interface and in the temperature variation during irradiation. METHODOLOGY: Ninety-six maxillary canines were prepared with K3 rotary system up to #45/0.02 instrument, irrigating with distilled water between files. The specimens were randomly assigned to three groups-final irrigation (distilled water, 1% NaOCl, and 17% EDTAC) and four subgroups (n = 8)-laser parameters (non-irradiated, 2 W/20 Hz, 3 W/20 Hz, and 4 W/20 Hz). During irradiation, the temperatures were measured on the outer root dentin wall in the three thirds, and root apex. Canals were filled with lateral condensation of AHPlus sealer and gutta-percha cones. Two slices from each third were submitted to a push-out test in Instron machine and the failure mode was analyzed. One slice from each third was analyzed by confocal laser microscopy to evaluate the percentage of the perimeter of the root canal cross-section with sealer tags and depth of tags. Data were analyzed by ANOVA, Kruskal-Wallis, and Tukey's tests (P < 0.05). RESULTS: Er,Cr:YSGG laser irradiation increased sealer bond strength to dentin, regardless of the final irrigation. The highest values were obtained for 3 W (4.02 ± 1.32) and 4 W (4.18 ± 0.98) powers and different from the non-irradiated group (2.64 ± 0.58) (P < 0.05). The 2 W irradiation produced similar results to 3 W and 4 W when associated with 17% EDTA. Final irrigation with 17% EDTAC provided higher bond strength (4.01 ± 1.02) compared with distilled water (3.11 ± 1.09) and 1% NaOCl (3.47 ± 1.18) (P < 0.05). The cervical third (4.01 ± 1.21) presented significantly higher bond strength than the apical third (3.04 ± 0.89). There was a greater percentage of adhesive and mixed failure. In the groups irradiated with 3 W [21.1 (14.1-27.7)] and 4 W [17.8 (11.9-23.7)], a greater depth of filling material tags was observed compared with the non-irradiated group [12.9 (9.0-20.0)]. The greatest percentage of canal perimeter with sealer tags was observed in the irradiated groups, with no difference among them (P > 0.05). The temperature rise was proportional to the increase of laser power. CONCLUSIONS: Er,Cr:YSGG laser irradiation increased the bond strength of an epoxy resin-based sealer to root dentin, with greater formation of sealer tags for all tested powers, especially when combined with 17% EDTAC final irrigation; temperature rise during irradiation remained below the critical threshold biologically accepted. Lasers Surg. Med. 48:985-994, 2016. © 2016 Wiley Periodicals, Inc.