A micro-computed tomographic analysis of obturation quality and retreatability of an epoxy resin-based sealer.

BACKGROUND: To evaluate the voids percentage and the retreatability by different supplementary irrigation techniques of a matched-taper single cone and epoxy resin-based sealer. METHODS: A total of 72 single-rooted premolars were prepared and filled with gutta-percha and MM-Seal. The percentage of voids in the whole root canal and each anatomical part were evaluated by Micro-CT scans. After root filling removal, the teeth were randomly allocated (N.=24) to group A, syringe irrigation; group B, Tornado Brush, and group C, ultrasonically activated irrigation and re-scanned to establish the volume of remnant root filling material. The data relative to voids and retreatment techniques were established by the Kruskal-Wallis test. Differences in retreatment time were examined using one-way ANOVA and Tukey's Test (P<0.05). RESULTS: No significant difference was found in the voids percentage between the different root-thirds and between the supplementary irrigation groups in the MM-Seal remnants for the whole root canal and each section. In all groups, the coronal region exhibited more remaining material than other sections. CONCLUSIONS: MM-Seal showed low voids percentage and its removal was not significantly improved by supplementary irrigation techniques.

A comparison of accuracy between three different facial detection systems for prosthodontic esthetic preview: a single-blinded in vitro study.

BACKGROUND: The aim of this study was to compare the accuracy of 3 different devices for facial images acquisition, useful for prosthodontic esthetic preview. METHODS: Bidimensional extraoral photographs (Nikon D300), facial scans (Bellus3D) and 3D digital stereophotogrammetry photos (3dMD Face System) were acquired from 15 patients. The intraoral impressions of all subjects were digitally taken through a scanner (i500; Medit). Files obtained from each acquisition method were transferred on Exocad Software, and the measurements of the frontal teeth were performed and compared with those of the intraoral scans, assumed as reference. The data were statistically analyzed (Friedman and Dunn tests) with P<0.05. RESULTS: As for central and lateral incisors, no significant difference emerged between 2D digital photography and intraoral scans, both in height and width. Measures obtained with Bellus3D significantly differed from the reference data in width of all teeth, except for central incisors. Values referred to canines were those more subjected to significant distortions in width for all devices. CONCLUSIONS: Within the limits of this study, measures of frontal teeth acquired by 2D digital photography were similar to those of intraoral scans both in height and width, while those obtained with 3D facial scanners were more subjected to distortions in mesial-distal dimension.

Cyclic fatigue and torsional resistance evaluation of Reciproc R25 instruments after simulated clinical use.

BACKGROUND: To assess the influence of multiple uses on the cyclic flexural fatigue and torsional resistance of Reciproc R25 (REC25) instruments. METHODS: Overall, 256 canals (two for each mandibular molar) were prepared using Reciproc R25 instruments. A total of 96 25-mm-long Reciproc R25 instruments were divided in six groups (N.=8) on the basis of different number of canals shaped: new instruments (control group), one, two, three, four, or six canals shaped during simulated clinical use for other groups respectively. Sixteen files were used for each of the six groups (eight instruments for cyclic fatigue test and eight ones for torsional test). Times to fracture (TtF) for cyclic fatigue and ultimate torsional strength and angle of rotation to fracture for torsional resistance were recorded. Data were statistically evaluated by the analysis of variance (ANOVA) with P<0.05. RESULTS: As for cyclic fatigue resistance, there was no significant difference between new REC25 and REC25 used in one, two and three canals respectively (P>0.05). REC25 used in four and six canals showed significant lower times to fracture when compared with other groups (P<0.05) with REC25 used in six canals showing the significant lowest times to fracture (P<0.05). Considering torsional resistance parameters, no significant difference was observed between the new and used instruments (P>0.05). CONCLUSIONS: REC25 files showed a significant decrease in cyclic fatigue resistance only when used in four or more molar canals while their torsional behavior was not affected by multiple uses.

Root fillings with a matched-taper single cone and two calcium silicate-based sealers: an analysis of voids using micro-computed tomography.

OBJECTIVES: To compare the percentage of voids in matched-taper single-cone fillings with GuttaFlow Bioseal or BioRoot RCS root canal sealers, using micro-computed tomography. MATERIALS AND METHODS: Forty-eight single-rooted mandibular premolars were prepared using rotary files and randomly allocated into 2 groups (n = 24), wherein the canals were filled with a matched-taper single gutta-percha cone and one of the two sealers: Group 1, GuttaFlow Bioseal and Group 2, BioRoot RCS. The specimens were scanned with micro-CT before and after root canal filling. A specialized software was used to calculate the voids volume percentage (V%) in the filling for the whole root canal, root canal thirds, and the last millimeter from the apex. Data were statistically analyzed by ANOVA and Tukey tests (p < 0.05). RESULTS: Root canals filled with GuttaFlow Bioseal had significantly less V% than those filled with BioRoot RCS in all the root-thirds (p < 0.05) except at the apical 1 mm (p > 0.05). Comparing the root-thirds, GuttaFlow Bioseal showed similar V% in all regions (p > 0.05), while BioRoot RCS group had significantly greater V% in the coronal third compared with the other thirds (p < 0.05). CONCLUSIONS: Root canals filled with a matched-taper single cone and GuttaFlow Bioseal had significant less voids than those with BioRoot RCS, except at the apical 1 mm. CLINICAL RELEVANCE: Voids in root fillings have been reported to have a negative impact on root canal treatment. This study highlights the percentage of voids in root fillings composed of a single cone of gutta-percha with two types of calcium silicate-based bioceramic sealers.

Antimicrobial efficacy of cordless sonic or ultrasonic devices on Enterococcus faecalis-infected root canals.

AIM: The aim of the present study was to evaluate the immediate and residual antimicrobial activity of cordless sonic or ultrasonic devices on Enterococcus faecalis (E faecalis)-infected teeth. METHODS: A total of 140 single-rooted extracted teeth with E faecalis were grouped as follows (N = 15): conventional syringe irrigation with 3% sodium hypochlorite activated by ultrasonic device (group 1) or cordless ultrasonic device (group 2), EndoActivator (group 3) or without activation (group 4), conventional syringe irrigation with sterile bi-distilled water and ultrasonic device (group 5), EndoUltra (group 6), EndoActivator (group 7), or without activation (group 8). The remaining 20 teeth were used for positive and negative controls. Colony-forming units (CFU) and turbidity were recorded from bacteriological samples taken before and after irrigation and after 24 hours of re-incubation. Data were statistically analyzed using Student's t test, Mann-Whitney test, Kruskal-Wallis test, and Dunn's multiple comparison tests (P < .05). RESULTS: Groups 1 and 2 showed higher antimicrobial efficacy than groups 3 and 4 (P < .05). No bacteria reduction was found in groups 5-8 (P > .05). After 24 hours, regrowth of bacteria was not significantly different for all groups (P > .05). CONCLUSIONS: Ultrasound produced lower CFU and turbidity after treatment and after re-incubation of 24 hours than sonic or no activation.

Influence of proper or reciprocating optimum torque reverse kinematics on cyclic fatigue of four single files.

AIM: The aim of the present study was to evaluate the resistance to cyclic fatigue of heat-treated single files used in proper or in reciprocating optimum torque reverse motions. METHODS: Ninety-six HyFlex electrical discharge machining (EDM), Reciproc R25 (Rec), WaveOne Primary (WO), and WaveOne Gold (WOG) Primary were used. Resistance to cyclic fatigue was determined by recording time to fracture in a stainless steel artificial canal. Differential scanning calorimetric analysis was performed. Data were analyzed by two-way analysis of variance and Bonferroni post-hoc tests at 0.05. RESULTS: In both movements, HyFlex EDM showed higher time to fracture than other files (P < 0.0001). Rec showed higher time to fracture than WO (P < 0.0001), while WOG showed higher cyclic fatigue resistance than Rec and WO with both movements (P < 0.005). CONCLUSIONS: Reciprocating optimum torque reverse motion improved significantly cyclic fatigue resistance of gold and controlled memory wire single files.

Effects of 6 Single-File Systems on Dentinal Crack Formation.

INTRODUCTION: The purpose of this study was to compare the formation of microcracks after canal preparation performed with different single-file systems as One Shape (Micro-Mega, Besancon, Cedex, France), F6 SkyTaper (Komet Italia Srl, Milan, Italy), HyFlex EDM (Coltene/Whaledent AG, Altstatten, Switzerland), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (VDW, Munich, Germany), and WaveOne Gold (Dentsply Maillefer). METHODS: Eighty-four human extracted mandibular central incisors (40-60 y) were selected and divided into 6 experimental groups (n = 12 teeth) and a control group (unprepared teeth): One Shape (group 1), F6 SkyTaper (group 2), HyFlex EDM (group 3), WaveOne (group 4), Reciproc (group 5), and WaveOne Gold (group 6). Roots were then sectioned at 3, 6, and 9 mm from the apex, and the surface was observed under a stereomicroscope. Data were analyzed using logistic regression (P < .05). RESULTS: No cracks were observed in the control group. All the systems tested caused cracks, mainly in the apical section (3 mm). HyFlex EDM (33.3%) and WaveOne Gold (58.3%) showed fewer microcracks than other experimental groups (P < .01); however, no significant difference was found between them in crack formation (P > .05). There was no difference among the other experimental groups (P > .05). CONCLUSIONS: All the instruments tested created dentinal cracks. Within the limitations of this study, the flexibility of nickel-titanium instruments because of heat treatment seems to have a significant influence on dentinal crack formation. HyFlex EDM and WaveOne Gold caused less microcracks than the other instruments tested.