Mechanical properties evaluation of two resin-based three-dimensional printing materials and dentine for endodontic training model fabrication: In vitro study.

The objective of the study was to compare 4 mechanical properties of two 3-D printing resins with dentine. Four mechanical tests were performed on dentine specimens, VeroClear resin and Splint resin with 15 samples each. Vickers hardness test, samples were subjected to a 300-g load for 10 s. Flexural strength test, 8-millimetre, beam-shaped specimens were tested using the three-point bending method. Drilling force was measured on flat-surface specimens. Intra-canal torque was measured on specimens imitating root canals. The results were analysed using the Kruskal-Wallis and Mann-Whitney tests with adjusted Bonferroni's p-value (p < 0.05). Dentine exhibited the highest mechanical properties in all the tests. VeroClear's flexural strength and drilling force were higher, while the surface hardness was lower than that of Splint resin. The intra-canal torque of dentine and VeroClear resin were not significant and higher than that of Splint resin. VeroClear's mechanical properties were closer to dentine than Splint resin.

Shaping ability of non-adaptive and adaptive core nickel-titanium single-file systems with supplementary file in ribbon-shaped canals analysed by micro-computed tomography.

This study compared shaping ability between two single-file systems and before/after using supplementary file in untouched area, volume of removed dentin, maximum cut depth (the highest cut depth by main file) and remaining thinnest dentin (the thinnest root dentin after preparation). Ribbon-shaped distal canals of mandibular molars were prepared with non-adaptive core (WaveOne Gold) or adaptive core (XP-endo Shaper) files (n = 15/group) and additionally prepared with a supplementary file (XP-endo Finisher), and the shaping ability was investigated using micro-computed tomography. XP-endo Shaper group demonstrated significantly less overall untouched area than WaveOne Gold group (38.21 ± 6.98% vs. 47.68 ± 9.16%) (p < 0.05). No significant difference was detected between XP-endo Shaper and WaveOne Gold groups in volume of removed dentin (1.85 ± 0.53 vs. 1.66 ± 0.33 mm3 ), maximum cut depth (0.10-0.28 vs. 0.10-0.29 mm) and remaining thinnest dentin (0.66-0.80 vs. 0.78-0.88 mm). Supplementary XP-endo Finisher treatment significantly decreased untouched area (11%-23% reduction) (p < 0.05) with minimally cut root dentin (0.01-0.02 mm).

Gap volume and sealer penetration of C-shaped root canals obturated with cold hydraulic technique and calcium silicate sealer.

This study compared the gap volume and sealer penetration in C-shaped root canals prepared with adaptive core rotary files and obturated with cold hydraulic compaction using calcium-silicate sealer, warm vertical hybrid compaction, or lateral compaction using epoxy-resin sealer. Thirty-six extracted mandibular molars with pulpal floor configuration Types I and III were used. The teeth were prepared using XP-Shaper and XP-Finisher and obturated with: group 1: cold hydraulic compaction/calcium silicate, group 2: warm vertical hybrid compaction/epoxy resin, or group 3: lateral compaction/epoxy resin. The gap volume was evaluated using µ-CT. The sealer penetration depth and area were evaluated using confocal laser scanning microscopy. The gap volume in groups 1, 2, and 3 was 0.82%, 0.24%, 0.80%, respectively, which were not significantly different (p > 0.05). The gap volumes in the obturated C-shaped canals were not significantly different among the CHC/CSBS, WHC/ERS, or LC/ERS groups. CHC/CSBS was the most convenient technique.

Effect of solvent on root canal filling material removal by two different rotary file systems in C-shaped root canals.

This study compared the percentage reduction of total obturation materials, gutta-percha and sealer, using two rotary file systems with/without solvent in retreating C-shaped root canals and to evaluate the effect of the solvent on instrument separation. C-shaped root canals were scanned using micro-CT to identify the root canal morphology and randomly assigned to four groups (n = 12). Retreatment was performed using ProTaper Universal Retreatment (PTUR) or XP-endo systems with/without solvent. The number of separated instruments were recorded. The samples were scanned pre- and post-retreatment. The percentage reduction of total obturation materials, gutta-percha and sealer, were calculated. The percentage reduction of gutta-percha in the PTUR without solvent group was significantly lower than the other groups (P = 0.018). The number of separated instruments in the solvent groups were significantly lower than the no solvent groups (P < 0.05). Solvent increased gutta-percha removal, when using PTUR and decreased the occurrence of separated instruments for both systems.

Simplify pulpectomy in primary molars with a single-file reciprocating system: a randomized controlled clinical trial.

OBJECTIVES: To compare the clinical use of a single-file NiTi reciprocal system (sNiTi) to that of stainless steel hand file (SSH) instrumentation in primary tooth pulpectomy. MATERIALS AND METHODS: A prospective randomized clinical trial was conducted in 34 healthy children aged 3-7 years. Thirty-seven mandibular primary molars were randomly assigned to two groups: sNiTi and SSH. Instrumentation time, obturation time, quality of obturation, and 6- and 12-month clinical and radiographic outcomes were compared between the two groups. RESULTS: The median instrumentation time using sNiTi (3.23 min) was significantly shorter than that for SSH (7.38 min). Obturation times were not different. The quality of obturation was significantly different only in the mesial root canals; overfilling was seen more in the sNiTi group, while underfilling occurred more in the SSH group. At 6 and 12 months, both groups showed comparable clinical and radiographic success regardless of the type of instrumentation. CONCLUSIONS: sNiTi shortens instrumentation time with comparable obturation time, overall quality of obturation, and clinical and radiographic outcomes with SSH. CLINICAL RELEVANCE: Pulpectomy is indicated to prevent premature loss of primary teeth with irreversible inflamed or infected pulp. However, it is complicated and time-consuming. sNiTi reciprocating system is an alternative to hand filing technique, avoiding multiple steps and simplifying pulpectomy procedures.

Shear bond strengths of calcium silicate-based sealer to dentin and calcium silicate-impregnated gutta-percha.

AIM: To compare the shear bond strengths of a calcium silicate-based root canal sealer (CSS), to dentin or calcium silicate-impregnated gutta-percha (CSGP), with the shear bond strengths of an epoxy resin-based sealer. METHODS: For sealer/dentin testing, 40 hemisectioned roots were divided into 2 groups. Coronal root dentin discs were bonded with CSS or epoxy resin-based sealer. For sealer/core material testing, CSGP and conventional gutta-percha discs were bonded with a matching sealer (N = 20 per group). The shear bond strengths were tested using a universal testing machine. The failed modes were analyzed using stereomicroscopy and scanning electron microscopy. RESULTS: The CSS sealer had significantly higher shear bond strength to dentin than did epoxy resin-based sealer (P < .01). However, shear bond strengths of the 2 sealers to core materials did not significantly differ (P = .74). The remnants of the CSS sealer adhering to dentin or calcium silicate gutta-percha disc were observed. CONCLUSIONS: The CSS sealer had better adhesion to dentin than did epoxy resin-based sealer. However, the bond of the CSS sealer to impregnated gutta-percha was not superior to the epoxy resin-based sealer bonded to conventional gutta-percha.

Root Reinforcement after Obturation with Calcium Silicate-based Sealer and Modified Gutta-percha Cone.

INTRODUCTION: A root canal obturated with a calcium silicate-based sealer (bioceramic sealer [BCS]) and a modified gutta-percha cone (bioceramic cone [BCC]) might improve the fracture resistance of the root. The objective of this study was to evaluate root reinforcement of a bioceramic cone/sealer (TotalFill; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) by investigating the fracture resistance, push-out bond strength, sealer penetration, and modulus of elasticity (MOE) in comparison with gutta-percha/AH Plus (Dentsply Maillefer, Tulsa, OK) (GP/AH). METHODS: Eighty-four roots from bilateral mandibular premolars were prepared. For fracture resistance, 40 teeth were randomly divided into 4 groups (n = 10 each): intact roots (negative control), prepared roots (positive control), and the roots obturated with either BCC/BCS or GP/AH. Root canals were obturated with the matched single-cone technique and vertically loaded with a spreaderlike tip until fracture. For push-out bond strength (n = 10 each), coronal, middle, and apical root slices of BCC/BCS and GP/AH were loaded with a cylindrical plunger, and failure modes were determined. Sealer penetration of BCC/BCS and GP/AH (n = 12 each) was evaluated for the maximum depth and the circumferential and total area of penetration at the coronal, middle, and apical levels using confocal laser scanning microscopy. The MOE was investigated according to ISO 4049:2000. RESULTS: The fracture load of BCC/BCS, GP/AH, and the intact roots was not significantly different but significantly higher than the prepared, nonobturated roots. BCC/BCS provided a higher bond strength, maximum depth, and circumferential penetration at the apical root level as well as a greater sealer penetration area at all levels compared with GP/AH. The MOE of all materials was much lower than dentin. CONCLUSIONS: BCC/BCS and GP/AH bonded and reinforced the prepared roots; their fracture resistances were similar to the intact roots.

Bacterial leakage and micro-computed tomography evaluation in round-shaped canals obturated with bioceramic cone and sealer using matched single cone technique.

OBJECTIVES: To evaluate sealing ability of root canals obturated with bioceramic-impregnated gutta percha cone (BCC) or gutta percha (GP), with bioceramic sealer (BCS) or AH Plus (AH; Dentsply-Maillefer), in roundly-prepared canals using matched single-cone technique, based on bacterial leakage test, and to analyze obturation quality using micro-computed tomography (CT) analysis. MATERIALS AND METHODS: Ninety-two distobuccal roots of maxillary molars were prepared using nickel-titanium files to apical size 40/0.06. The roots were divided into 4 groups (n = 20) that were obturated with a master cone and sealer: GP/AH, BCC/AH, GP/BCS, and BCC/BCS. Bacterial leakage model using Enterococcus faecalis was used to evaluate sealing ability for 60-day period. Obturated samples from each group (n = 4) were analyzed using micro-CT. RESULTS: All groups showed bacterial leakage at 20%-45% of samples with mean leakage times of 42-52 days. There were no significant differences in bacterial leakage among the groups. Micro-CT showed minimal gaps and voids in all groups at less than 1%. CONCLUSIONS: In roundly-prepared canals, the single cone obturation with BCC/BCS was comparable to GP/AH for bacterial leakage at 60 days.

Mahidol study 1: comparison of radiographic and survival outcomes of immature teeth treated with either regenerative endodontic or apexification methods: a retrospective study.

INTRODUCTION: There are numerous challenges in treating immature permanent teeth with a diagnosis of pulp necrosis. Three general treatment options are calcium hydroxide apexification, mineral trioxide aggregate (MTA) apexification, and revascularization. The objective of this retrospective study was to evaluate radiographic and clinical outcomes of immature teeth treated with 1 of these 3 methods. METHODS: Clinical outcome data and radiographs were collected from 61 cases (ie, 22 calcium hydroxide apexification cases, 19 MTA apexification cases, and 20 revascularization cases). Both tooth survival and clinical success rates were analyzed. In addition, the preoperative and recall radiographs were analyzed to calculate the percentage increase in root width and length. RESULTS: The percentage change of root width was significantly greater in the revascularization group (28.2%) compared with the MTA apexification (0.0%) and calcium hydroxide apexification groups (1.5%). In addition, the percentage increase of root length was significantly greater in the revascularization group (14.9%) compared with the MTA (6.1%) and calcium hydroxide apexification groups (0.4%). Moreover, the survival rate of the revascularization-treated teeth (100%) and MTA apexification-treated teeth (95%) were greater than the survival rates observed in teeth treated with calcium hydroxide (77.2%). CONCLUSIONS: In this study, revascularization was associated with significantly greater increases in root length and thickness in comparison with calcium hydroxide apexification and MTA apexification as well as excellent overall survival rates.