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.

Characterization of the Protective Role of Regulatory T Cells in Experimental Periapical Lesion Development and Their Chemoattraction Manipulation as a Therapeutic Tool.

INTRODUCTION: The pathogenesis of periapical lesions is determined by the balance between host proinflammatory immune response and counteracting anti-inflammatory and reparative responses, which include regulatory T cells (Tregs) as potential immunoregulatory agents. In this study, we investigated (in a cause-and-effect manner) the involvement of CCL22-CCR4 axis in Treg migration to the periapical area and the role of Tregs in the determination of outcomes in periapical lesions. METHODS: Periapical lesions were induced in C57Bl/6 (wild-type) and CCR4KO mice (pulp exposure and bacterial inoculation) and treated with anti-glucocorticoid-induced TNF receptor family regulated gene to inhibit Treg function or alternatively with CCL22-releasing, polylactic-glycolic acid particles to induce site-specific migration of Tregs. After treatment, lesions were analyzed for Treg influx and phenotype, overall periapical bone loss, and inflammatory/immunologic and wound healing marker expression (analyzed by real-time polymerase chain reaction array). RESULTS: Treg inhibition by anti-glucocorticoid-induced TNF receptor family regulated gene or CCR4 depletion results in a significant increase in periapical lesion severity, associated with upregulation of proinflammatory, T-helper 1, T-helper 17, and tissue destruction markers in parallel with decreased Treg and healing marker expression. The local release of CCL22 in the root canal system resulted in the promotion of Treg migration in a CCR4-dependent manner, leading to the arrest of periapical lesion progression, associated with downregulation of proinflammatory, T-helper 1, T-helper 17, and tissue destruction markers in parallel with increased Treg and healing marker expression. CONCLUSIONS: Because the natural and CCL22-induced Treg migration switches active lesion into inactivity phenotype, Treg chemoattractant may be a promising strategy for the clinical management of periapical lesions.

Genetic susceptibility to periapical disease: conditional contribution of MMP2 and MMP3 genes to the development of periapical lesions and healing response.

INTRODUCTION: It has been proposed that individual genetic predisposition may contribute to a persistent apical periodontitis condition. Matrix metalloproteinases (MMPs) are associated with levels of inflammation and are involved in caries, pulpal, and periapical tissue destruction. MMPs also play a major role in bone resorption. In this study, we hypothesized that polymorphisms in MMP genes and their regulators may contribute to an individual's increased susceptibility to apical tissue destruction in response to deep carious lesions. METHODS: Sixteen hundred radiographic records obtained through the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository were screened for subjects with deep carious lesions in dentin with or without periapical lesions (≥ 3 mm). DNA samples of 268 patients were sorted into 2 groups: 158 cases with deep carious lesions but no periapical lesions (controls) and 110 cases with periapical lesions and deep carious lesions (cases). Sixteen SNP markers in MMP2, MMP3, MMP9, MMP13, MMP14, and TIMP2, were selected for genotyping. Genotypes were generated by endpoint analysis in a real-time polymerase chain reaction instrument. Analyses were performed comparing cases and controls. Allele and genotypic frequencies and haplotype analysis were calculated using the PLINK program. RESULTS: An association was found for MMP3 rs639752 (P = .03) and rs679620 (P = .004) genotypes in individuals with periapical lesions. We also observed altered transmission of MMP2 marker haplotypes (P = .000004) in these individuals. CONCLUSIONS: Variations in MMP2 and MMP3 are associated with periapical lesion formation in individuals with untreated deep carious lesions. Future studies could help predict host susceptibility to developing periapical lesions.