Publications by authors named "Marco Antonio Hungaro Duarte"

211 Publications

Evaluation of foramen locating accuracy of an endodontic motor integrated with electronic foramen employing optimal glide path kinematics.

Clin Oral Investig 2021 Aug 18. Epub 2021 Aug 18.

Post-Graduate Program in Dentistry, Federal University of Ceará, Fortaleza, Ceará, Brazil.

Objective: This study aimed to evaluate the accuracy of the auto apical function in the maintenance of the apical limit of instrumentation during glide path procedures when associated to OGP kinematics of Tri Auto ZX2, compared to the continuous rotation of the same motor, as well as Root ZX II and VDW Gold.

Materials And Methods: Forty-eight extracted human mandibular single-rooted premolars were selected. After endodontic access, cervical pre-flaring was performed using size 30, 0.10 taper rotary instruments, and the apical foramen size was standardized to 200 μm. Teeth were randomly divided into four groups (n = 12) according to the device and kinematics. For all the groups, the Auto Apical Stop function (AAS) was set to the 0.0 mark. Glide path instruments size 25, .01 taper were activated inside the canals until the apical limit was reached. Then, the files were fixed with cyanoacrylate to the teeth and decoupled from the equipment. Data were statistically analyzed in GraphPad Prism 6.0 software with the significance set at 5% (Kruskal-Wallis tests).

Results: There was no difference in the mean deviation between the groups. No significant difference was found among the groups when the distributions and percentages of differences between the file tip and the apical foramen were compared (P > 0.05).

Conclusion: The use of auto apical function at the 0.0 mark of all tested devices provided an adequate control of the apical limit during glide path preparation. Foramen locating accuracy of Tri Auto ZX2 in OGP kinematics was similar to those of Tri Auto ZX2, Root ZX II, and VDW Gold in continuous kinematics.

Clinical Relevance: Clinical strategies in canal negotiation and glide path as OGP motion associated to electronic foramen locators could reduce iatrogenic risk of deviation and file fractures and create an easier initial preparation to facilitate endodontic procedures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00784-021-04103-3DOI Listing
August 2021

Effect of Irrigating Agitation after Root End Preparation on the Wall Cleaning and Bond Strength of Calcium Silicate Material in Retrograde Obturation.

Eur J Dent 2021 Jul 24. Epub 2021 Jul 24.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.

Objective:  The study aimed to evaluate the cleaning efficacy of irrigant activation with a new ultrasonic tip in root-end preparations and to determine its influence on the bond strength of calcium silicate-based material.

Materials And Methods:  Maxillary canines were prepared and filled, and their root ends resected. Root-end cavities were ultrasonically prepared and randomly distributed into four groups according to the final irrigation protocols: G1 (ultrasonic irrigation [UI] + saline solution [SS]), G2 (syringe irrigation [SI] + SS), G3 (UI + ethylenediaminetetraacetic acid [EDTA]), and G4 (SI + EDTA). Cleaning efficacy analysis employed 72 specimens ( = 18) split longitudinally for imaging of the same areas by scanning electron microscopy (SEM). The percentage of dentinal tubules opened before and after irrigation was used as evaluation parameter. Push-out testing employed 40 specimens ( = 10) sectioned apical region perpendicularly, which slice was placed on a testing machine for the bond strength measurement and failure mode was assessed by SEM. The data were statistically analyzed (α ≤ 0.05).

Results:  G3 (UI + EDTA) removed the smear layer more effectively, showed the best tubule opening ( < 0.05), and presented the highest mean bond strength values ( < 0.05). Failure modes were predominantly adhesive, except for the G3 (UI + EDTA) group, in which they were mainly mixed (80%).

Conclusion:  The results of this study suggest that EDTA 17% agitation promoted better cleaning and smear layer removal, improving the push-out bond strength of calcium silicate material in retrograde obturation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0041-1729454DOI Listing
July 2021

Analysis of Instrumentation Protocols Regarding the Quality of Mesial Canal Preparation in Mandibular Molars: A Micro-computed Tomographic Study.

J Endod 2021 Sep 15;47(9):1481-1486. Epub 2021 Jun 15.

Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

Introduction: This study aimed to use micro-computed tomographic imaging to analyze the quality of the endodontic preparation of mesial canals in mandibular molars provided by 3 instrumentation protocols.

Methods: Forty-five extracted mandibular molars with 2 independent mesial canals were selected, and the initial micro-computed tomographic imaging was performed. The initial volume values of the canals were submitted to statistical analysis for paired division. The groups were determined according to the final enlargement of the canal and the working length adopted (ie, G25.06/+1 mm, G35.05/foramen, and G50.01/-1 mm). At the end of each instrumentation sequence, the root canals were scanned and analyzed with regard to the increase in the total and apical volume, centralization, and preparation transportation and the percentage of the total and apical uninstrumented walls.

Results: For the intragroup comparison, the Wilcoxon test was used, and for the intergroup analysis, the Kruskal-Wallis and Dunn tests were used (P < .05). In the analysis of the canal total volume, a statistical difference was found between G25.06/+1 mm and the remaining groups (P < .05). In the apical third, a statistical difference was observed between G25.06/+1 mm and G50.01/-1 mm (P < .05). No statistical difference was found between the groups in terms of centralization and transportation of the preparation or in terms of the percentage of the total or apical uninstrumented walls.

Conclusions: The preparation of the mesial canals of mandibular molars up to larger tip files but with a lower taper at 1 mm before the foramen resulted in a larger volume of apical preparation, kept the preparation centralized, and provided safe apical dentin wear without excessive cervical wear.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.joen.2021.06.008DOI Listing
September 2021

Cleaning efficacy and uncontrolled removal of dentin of two methods of irrigant activation in curved canals connected by an isthmus.

Aust Endod J 2021 Jun 7. Epub 2021 Jun 7.

Department of Restorative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.

The aim of this study was to compare the efficacy of UAI with ESI, sonic activation with Eddy and syringe irrigation in removing debris, and dentin removal during canal irrigation. Twenty-four mandibular molars containing isthmus type V and with a mean curvature of 32.5º were instrumented and divided into three groups for final irrigation: UAI with ESI, sonic activation with Eddy and syringe irrigation. The samples were scanned in a SkyScan 1172 micro-CT device for pre-, post-instrumentation and post-irrigation images and analysis of dentin removal. Statistical analysis was performed using Wilcoxon, Kruskal-Wallis and Dunn tests. UAI and sonic activation significantly improved debris removal (P < 0.05). No significant difference was observed regarding dentin removal between the groups (P > 0.05), although higher values were found for UAI. Sonic activation with Eddy showed to be an effective and safe device since it was able to remove debris without causing damage to the canal walls.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/aej.12534DOI Listing
June 2021

Evaluation of type of kinematics on glide path procedures and torsional fatigue resistance after preparation of moderately curved canals.

Braz Oral Res 2021 31;35:e064. Epub 2021 May 31.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

Sixty moderately curved canals of mandibular molars classified as Vertucci's type IV canal configuration were selected by micro-CT 1174. The teeth were divided into two groups according to the kinematics used, whether reciprocating or rotary motion (n=30, totaling 60 mesial root canals). The instruments used to perform the glide path procedures had identical features (0.15 mm of tip size, 0.04 mm/mm taper, thermal treatment, and square cross-section), but differed in the direction of the cutting blade. The duration of the procedure and the absolute and percentage frequency of the instruments to reach the full working length were recorded. The torsional test (3630-1; 1992) was performed on both used and unused instruments, to evaluate a possible reduction in the torsional resistance when using the glide path procedure. Statistical analysis was performed using the unpaired t-test and the chi-square test, and the level of significance was set at 5%. The type of kinematics used affected the duration of glide path procedures, and the reciprocating motion seemed to induce less torsional stress during glide path procedures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/1807-3107bor-2021.vol35.0064DOI Listing
June 2021

Optimum glide path motion is safer than continuous rotation of files in glide path preparation.

Aust Endod J 2021 Apr 29. Epub 2021 Apr 29.

Post Graduation Program in Dentistry, Department of Restorative Dentistry, Faculty of Dentistry, University of São Paulo, Bauru, Brazil.

This study evaluated the resistance to flexural fatigue and torsional strength of files for glide path preparation in continuous rotation or Optimum Glide Path motion (OGP). ScoutRace 15.02 and ProGlider 16.02 files were used in a dynamic testing device during preparation of simulating curved root canals (40-degree curvature and 5 mm radius). For the torsional test, a machine was used to test torsion measured maximum torsional strength (N.cm). Two-way anova and Tukey's multiple comparisons test were used for statistical analysis. Files in OGP motion had a statistically better resistance to flexural fatigue (P < 0.05). ProGlider files took longer time to failure than ScoutRace files only when OGP was used (P < 0.05). The torsional test revealed that OGP produced significantly less torsional stress than rotary motions for both types of glide path files (P < 0.05) In conclusion, OGP motion increased substantially the mechanical safety of endodontic glide path files.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/aej.12519DOI Listing
April 2021

Comparison of limited- and large-volume cone-beam computed tomography using a small voxel size for detecting isthmuses in mandibular molars.

Imaging Sci Dent 2021 Mar 28;51(1):27-34. Epub 2021 Jan 28.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of Sao Paulo, Bauru, Brazil, Brazil.

Purpose: This study was performed to compare the ability of limited- and large-volume cone-beam computed tomography (CBCT) to display isthmuses in the apical root canals of mandibular molars.

Materials And Methods: Forty human mandibular first molars with isthmuses in the apical 3 mm of mesial roots were scanned by micro-computed tomography (micro-CT), and their thickness, area, and length were recorded. The samples were examined using 2 CBCT systems, using the smallest voxels and field of view available for each device. The Mann-Whitney, Friedman, and Dunn multiple comparison tests were performed (α=0.05).

Results: The 3D Accuitomo 170 and i-Cat devices detected 77.5% and 75.0% of isthmuses, respectively (>0.05). For length measurements, there were significant differences between micro-CT and both 3D Accuitomo 170 and i-Cat (<0.05).

Conclusion: Both CBCT systems performed similarly and did not detect isthmuses in the apical third in some cases. CBCT still does not equal the performance of micro-CT in isthmus detection, but it is nonetheless a valuable tool in endodontic practice.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5624/isd.20200144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007390PMC
March 2021

In Vivo Biological Behavior of Polymer Scaffolds of Natural Origin in the Bone Repair Process.

Molecules 2021 Mar 13;26(6). Epub 2021 Mar 13.

Department of Morphology and Pathology, Medical College of Jundiai, Jundiaí, São Paulo 13202-550, SP, Brazil.

Autologous bone grafts, used mainly in extensive bone loss, are considered the gold standard treatment in regenerative medicine, but still have limitations mainly in relation to the amount of bone available, donor area, morbidity and creation of additional surgical area. This fact encourages tissue engineering in relation to the need to develop new biomaterials, from sources other than the individual himself. Therefore, the present study aimed to investigate the effects of an elastin and collagen matrix on the bone repair process in critical size defects in rat calvaria. The animals (Wistar rats, 30) were submitted to a surgical procedure to create the bone defect and were divided into three groups: Control Group (CG, 10), defects filled with blood clot; E24/37 Group (E24/37, 10), defects filled with bovine elastin matrix hydrolyzed for 24 h at 37 °C and C24/25 Group (C24/25, 10), defects filled with porcine collagen matrix hydrolyzed for 24 h at 25 °C. Macroscopic and radiographic analyses demonstrated the absence of inflammatory signs and infection. Microtomographical 2D and 3D images showed centripetal bone growth and restricted margins of the bone defect. Histologically, the images confirmed the pattern of bone deposition at the margins of the remaining bone and without complete closure by bone tissue. In the morphometric analysis, the groups E24/37 and C24/25 (13.68 ± 1.44; 53.20 ± 4.47, respectively) showed statistically significant differences in relation to the CG (5.86 ± 2.87). It was concluded that the matrices used as scaffolds are biocompatible and increase the formation of new bone in a critical size defect, with greater formation in the polymer derived from the intestinal serous layer of porcine origin (C24/25).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/molecules26061598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002007PMC
March 2021

A matched irrigation and obturation strategy for root canal therapy.

Sci Rep 2021 Feb 25;11(1):4666. Epub 2021 Feb 25.

School of Dentistry, Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.

In root canal therapy, irrigating solutions are employed to eliminate the bacterial load and also prepare dentin for sealer interaction. The aim of this research was to assess how irrigating solutions employed on their own or in sequence affected the tooth structure. The best way to prepare the tooth for obturation using hydraulic calcium silicate cement (HCSC) sealers and gutta-percha, thus guiding clinicians on a matched irrigation-obturation strategy for optimized root canal treatment was investigated. The effect of irrigating solutions on dentine was investigated by assessing changes in dentin microhardness, ultrastructure and mineral content, organic/inorganic matter, surface roughness and Young's modulus. The interaction of four root canal sealers with the dentin was analysed by assessing the changes in microhardness of the dentin after sealer placement and also the sealer to dentin interface by scanning electron and confocal laser microscopy. The irrigating solutions damaged the dentin irreversibly both when used on their own and in combination. The best sequence involved sodium hypochlorite followed by chelator and a final rinse with sodium hypochlorite and obturation using HCSC sealers that enabled the restoration of dentin properties. The HCSC sealers did not rely on chelator irrigating solutions for a good material adaptation to dentin.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-021-83849-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7907354PMC
February 2021

Safety and Effectiveness of Additional Apical Preparation using a Rotary Heat-treated Nickel-Titanium file with Larger Diameter and Minimum Taper in Retreatment of Curved Root Canals.

Eur J Dent 2021 May 23;15(2):247-252. Epub 2021 Feb 23.

Department of Restorative Dentistry, School of Dentistry, São Paulo State University, São Paulo, Brazil.

Objective:  The aim of this study was to investigate the effect of additional apical preparation using the ProDesign Logic (PDL) 50/.01 rotary heat-treated nickel-titanium (NiTi) file with a larger diameter and minimal taper for retreatment of curved root canals.

Materials And Methods:  Mesial curved root canals of 12 mandibular molars were prepared using PDL 25/.06 and filled using the continuous wave of condensation technique and AH Plus sealer. After retreatment using ProDesign S (PDS) 25/.08, PDL 25/.06 and PDL 35/05, a complementary procedure was performed with PDL 50/.01. Microcomputed tomography (micro-CT) scanning was performed before and after retreatment procedures. The cyclic fatigue resistance of unused PDS 25/.08, PDL 25/.06, PDL 35/.05 and PDL 50/.01 instruments ( = 12) was evaluated in a stainless-steel device.

Statistical Analysis:  Data on the volumes of the root canals and the remaining filling materials were submitted to the paired t-test. Cyclic fatigue resistance data was submitted to one-way ANOVA and Tukey's tests (α = 0.05).

Results:  Use of PDL 50/.01 decreased the remaining filling materials in the apical third ( 0.05). The root canal volume was similar in the cervical and middle thirds before and after preparation using PDL 50/.01 ( 0.05). PDL 50/.01 presented the highest cyclic fatigue resistance ( 0.05).

Conclusions:  Use of the PDL 50/.01 instrument as an additional apical preparation for retreatment of curved root canals improved filling material removal in the apical third, while maintaining the dentin in the cervical and middle thirds. In addition, PDL 50/.01 presented high-flexural resistance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0041-1723065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8184271PMC
May 2021

Photobiomodulation Therapy on the Guided Bone Regeneration Process in Defects Filled by Biphasic Calcium Phosphate Associated with Fibrin Biopolymer.

Molecules 2021 Feb 5;26(4). Epub 2021 Feb 5.

Department of Biological Sciences (Anatomy), Bauru School of Dentistry, University of São Paulo (USP), Bauru 17012-901, São Paulo, Brazil.

The aim is to evaluate the effects of photobiomodulation therapy (PBMT) on the guided bone regeneration process (GBR) in defects in the calvaria of rats filled with biphasic calcium phosphate associated with fibrin biopolymer. Thirty male Wistar rats were randomly separated: BMG ( 10), defects filled with biomaterial and covered by membrane; BFMG ( 10), biomaterial and fibrin biopolymer covered by membrane; and BFMLG ( 10), biomaterial and fibrin biopolymer covered by membrane and biostimulated with PBMT. The animals were euthanized at 14 and 42 days postoperatively. Microtomographically, in 42 days, there was more evident bone growth in the BFMLG, limited to the margins of the defect with permanence of the particles. Histomorphologically, an inflammatory infiltrate was observed, which regressed with the formation of mineralized bone tissue. In the quantification of bone tissue, all groups had a progressive increase in new bone tissue with a significant difference in which the BFMLG showed greater bone formation in both periods (10.12 ± 0.67 and 13.85 ± 0.54), followed by BFMG (7.35 ± 0.66 and 9.41 ± 0.84) and BMG (4.51 ± 0.44 and 7.11 ± 0.44). Picrosirius-red staining showed greater birefringence of collagen fibers in yellow-green color in the BFMLG, showing more advanced bone maturation. PBMT showed positive effects capable of improving and accelerating the guided bone regeneration process when associated with biphasic calcium phosphate and fibrin biopolymer.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/molecules26040847DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7914843PMC
February 2021

Influence of CBCT-based volumetric distortion and beam hardening artefacts on the assessment of root canal filling quality in isthmus-containing molars.

Dentomaxillofac Radiol 2021 Jul 5;50(5):20200503. Epub 2021 Jan 5.

Department of Restorative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.

Objectives: To evaluate the influence of artefacts in cone beam CT (CBCT) images of filled root canals in isthmus-containing molars.

Methods: 10 teeth presenting canals with an isthmus were instrumented and filled with a thermoplasticised obturation technique. The teeth were scanned using a micro-CT device and two CBCT devices: 3D Accuitomo 170 (ACC) and NewTom VGi evo (NT), with different acquisition protocols: larger and smaller voxel size. Three examiners assessed the CBCT images for: (1) detection of filling voids; (2) assessment of under- or overestimation of the filling material and (3) resemblance of CBCT images to the reference standard. Analyses of Task 1 yielded accuracy, sensitivity and specificity for detection of filling voids. For tasks 2 and 3, statistical analysis was performed using Wilcoxon test. The level of significance was set at < .05.

Results: For Task 1, ACC showed higher sensitivity, whereas NT presented higher specificity. No significant difference was found between the protocols in ACC, however, for NT, differences between protocols were significant for all diagnostic values. In Task 2, visualisation of the filling was overestimated for NT, while for ACC, underestimation was observed. For Task 3, images with smaller voxel size were more similar to the reference image, for both CBCT devices.

Conclusions: Different artefacts compromise the detection of filling voids on CBCT images of canals in mandibular molars with isthmus. ACC and NT present rather similar diagnostic accuracy, even though artefact expression remains device-specific.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1259/dmfr.20200503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8231682PMC
July 2021

Safety of large preparation with different instruments in the buccal canals of maxillary molars.

Aust Endod J 2021 Apr 26;47(1):81-89. Epub 2020 Dec 26.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.

This study aimed to evaluate the influence of large apical preparations with Reciproc (REC), Hyflex CM (HCM) and Twisted File Adaptive (TFA) systems using micro-computed tomography (MCT). Ninety mesiobuccal (MB) and distobuccal (DB) root canals of maxillary molars (n = 45) were scanned using MCT before and after the shaping procedures. The root canals (n = 15) were prepared until REC 40.06, HCM 40.04 and TFA 35.04. The root canal transportation (RCT), centring ability (CA), change in volume of the root canal and at different levels (VC), remaining dentine thickness (RDT), removal of dentine wall (RDW) and working time (WT) were evaluated. Data were analysed using the Kruskal-Wallis and Dunn tests, and the one-way ANOVA and Tukey tests with a level of significance set at 5%. No significant difference among the instruments was found regarding the RCT, CA, RDT, RDW and WT (P > 0.05), in larger apical preparations in curved MB and straight DB canals of maxillary molars.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/aej.12481DOI Listing
April 2021

Mechanical Properties of ProTaper Gold, EdgeTaper Platinum, Flex Gold and Pro-T Rotary Systems.

Eur Endod J 2020 12;5(3):205-211

Department of Restorative Dentistry, Dental Materials and Endodontics, Bauru Faculty of Dentistry, University of So Paulo, Bauru, SP, Brazil.

Objective: The aim of this study was to evaluate the cyclic fatigue, torsional behavior and bending resistance of EdgeTaper Platinum [ETP (tip 25, taper 0.06)], Flex Gold [FG (tip 25, taper 0.08)], Pro-T [PT (tip 25, taper 0.08)] and ProTaper Gold [PTG (tip 25, taper 0.08)] systems.

Methods: Rotary instruments of ETP, PT, FG, and PTG were used (n=30). Cyclic fatigue tests were performed using an artificial stainless-steel canal with a 60o angle and a 5-mm radius of curvature at body temperature (35°±1°C). The time and number of cycles to fracture (NCF) was recorded. The torsional test evaluated the torque and angle of rotation to failure at 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). The bending test evaluated the torque required to bend the instruments at an angular deflection of 60°. Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%.

Results: The ETP had highest time until fracture and NCF than all the groups (P<0.05). The PTG had the highest torsional strength, followed by FG (P<0.05). The ETP had the highest angular rotation, followed by PT and PTG (P<0.05). The FG showed the highest bending resistance, followed by the PTG (P<0.05).

Conclusion: In conclusion, the ETP and PT exhibited higher cyclic fatigue resistance, higher angular deflection values and lower bending force than FG and PTG. The PTG instruments showed the highest torsional strength and the lowest cyclic fatigue resistance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.14744/eej.2020.48658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881372PMC
December 2020

Evaluation of the mechanical properties of different nickel-titanium retreatment instruments.

Aust Endod J 2021 Aug 9;47(2):265-272. Epub 2020 Dec 9.

Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.

This study investigated the cyclic fatigue, bending, torsional resistance and angular deflection of Pro-R 25.08, Logic RT 25.08, MK Retreatment 25.08 (MK RT) and ProTaper Retreatment D2 instruments. Cyclic fatigue test was performed until fracture in a custom stainless-steel device with water bath equipment to simulate body temperature. Fracture time was recorded. A number of cycles were calculated. Resistance to bending at 45°, torsional resistance and angular deflection were evaluated. The fracture surfaces were examined by scanning electron microscopy. Statistical analysis was performed with one-way ANOVA and Tukey and Kruskal-Wallis and Dunn tests. Pro-R and Logic RT presented the highest cyclic fatigue (P < 0.05). D2 had higher strength to bend than Pro-R and Logic RT (P < 0.05). Logic RT showed the highest torque and angular deflection (P < 0.05), without differences when compared to D2 (P > 0.05). Instrument performances were dependent on their geometrical features and heat treatments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/aej.12474DOI Listing
August 2021

Analysis of the physicochemical properties, cytotoxicity and volumetric changes of AH Plus, MTA Fillapex and TotalFill BC Sealer.

J Clin Exp Dent 2020 Nov 1;12(11):e1058-e1065. Epub 2020 Nov 1.

Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.

Background: To evaluate the physicochemical properties and cytotoxicity of AH Plus, MTA Fillapex and TotalFill BC Sealer. Volumetric changes were also evaluating using micro-computed tomography (micro-CT).

Material And Methods: Radiopacity and flow were evaluated in accordance with the ISO 6876, while setting time was evaluated in accordance with the ASTM- C266-08 specifications. The release of Ca2+ ions and pH were measured with spectrophotometer and pH meter, respectively, after different time intervals (1h, 3h, 24h, 72h, 168h, and 360h). Cytotoxicity was evaluated by MTT reduction assay to check 3T3 cells viability at 24, 48 and 72 hours. Volumetric change was evaluated by micro-CT, by using 30 acrylic teeth, filled with gutta-percha cones and the tested root canal sealer. The samples were evaluated after 168h, 360h and 720h of immersion in distilled water. Data were statistically analyzed by one-way ANOVA and Tukey test or by Kruskal-Wallis and Dunn tests (<0.05).

Results: MTA Fillapex and TotalFill BC Sealer showed lower radiopacity than AH Plus (<0.05). The MTA Fillapex showed the highest flow, while AH Plus showed the lowest flow (<0.05). The initial and final setting time of AH Plus were lower than MTA Fillapex and TotalFill BC Sealer (<0.05). In general, TotalFill BC Sealer presented higher Ca2+ ion release and pH than the other tested sealers. TotalFill BC Sealer also showed overall lower cytotoxicity when compared to the other sealers. Volumetric change of AH Plus and TotalFill BC Sealer was lower than MTA Fillapex (<0.05).

Conclusions: AH Plus, MTA Fillapex and TotalFill BC Sealer showed slight differences in the physicochemical properties and cytotoxicity, but all suitable for an endodontic sealer. However, AH Plus and TotalFill BC Sealer showed low volumetric changes when compared to MTA Fillapex. Calcium silicate, cytotoxicity, physicochemical properties, micro computed tomography.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4317/jced.57527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7680565PMC
November 2020

Can kinematics, file diameter, and PUI influence the intracanal decontamination and apical bacterial extrusion?

Braz Oral Res 2020 13;35:e003. Epub 2020 Nov 13.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

The present study investigated the intracanal decontamination and apical extrusion of bacteria and debris from root canals instrumented with rotary and reciprocating systems (ProDesign Logic or ProDesign R), with different file diameters and using conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI). Eighty extracted mandibular premolars were contaminated with Enterococcus faecalis and randomly assigned to eight experimental groups according to the root canal instrumentation and irrigation technique employed (n = 10): G1: Prodesign Logic 25.06; G2: Prodesign R 25.06; G3 and G4 were instrumented with the same single-file systems, respectively, using 35.05 diameters and CSI. G5, G6, G7, and G8 were instrumented like the previous groups, but with PUI. Apically extruded debris during instrumentation was collected into pre-weighed microtubes. The weight of the empty microtube was subtracted from the final weight to establish the amount of extruded debris. Bacteria from root canals and extruded debris were collected for a microbiological evaluation of colony forming units (CFU/mL). For statistical analyses, the Mann-Whitney and Kruskal-Wallis followed by the Dunn's tests were used (α = 0.05). All instruments caused extrusion of debris. For irrigation techniques, PUI promoted greater debris and bacterial extrusion (p < 0.05). The CFU/mL count indicated that the instrumentation of the experimental groups were equally effective in the decontamination of the root canal (p > 0.05). The systems tested (regarding file diameter and kinematics) were associated with similar amounts of apically extruded debris and root canal decontamination. PUI was associated with greater debris and bacterial extrusion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/1807-3107bor-2021.vol35.0003DOI Listing
January 2021

Biocompatibility, Biomineralization, and Maturation of Collagen by RTR®, Bioglass and DM Bone® Materials.

Braz Dent J 2020 Sep-Oct;31(5):477-484

Department of Endodontics, School of Dentistry, UNESP - Universidade Estadual Paulista, Araçatuba, SP, Brazil.

This study evaluated the biocompatibility, biomineralization, and collagen fiber maturation induced by Resorbable Tissue Replacement (RTR®; β-tricalcium phosphate [TCP]), Bioglass (BIOG; bioactive glass), and DM Bone® (DMB; hydroxyapatite and β-TCP) in vivo. Sixty-four polyethylene tubes with or without (control group; CG) materials (n=8/group/period) were randomly implanted in the subcutaneous tissue of 16 male Wistar rats (four per rat), weighting 250 to 280 g. The rats were killed after 7 and 30 days (n=8), and the specimens were removed for analysis of inflammation using hematoxylin-eosin; biomineralization assay using von Kossa (VK) staining and polarized light (PL); and collagen fiber maturation using picrosirius red (PSR). Nonparametric data were statistically analyzed by Kruskal-Wallis and Dunn tests, and parametric data by one-way ANOVA test (p<0.05). At 7 days, all groups induced moderate inflammation (p>0.05). At 30 days, there was mild inflammation in the BIOG and CG, and moderate inflammation in the RTR and DMB groups, with a significant difference between the CG and RTR (p<0.05). The fibrous capsule was thick at 7 days and predominantly thin at 30 days in all groups. All materials exhibited structures that stained positively for VK and PL. Immature collagen fibers were predominant at 7 and 30 days in all groups (p>0.05), although DMB exhibited more mature fibers than BIOG at 30 days (p<0.05). RTR, BIOG, and DMB were biocompatible, inducing inflammation that reduced over time and biomineralization in the subcutaneous tissue of rats. DMB exhibited more mature collagen fibers than BIOG over a longer period.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/0103-6440202003660DOI Listing
November 2020

The impact of the use of magnifying dental loupes on the performance of undergraduate dental students undertaking simulated dental procedures.

J Dent Educ 2021 Mar 27;85(3):418-426. Epub 2020 Sep 27.

Department of Operative Dentistry, Endodontics and Dental Materials, University of São Paulo, Bauru School of Dentistry, Bauru, São Paulo, Brazil.

Objectives: This study aimed to evaluate the impact of the use of magnification (2.5x dental loupes) for third-year dental students in simulated endodontics and fixed prosthodontics assessments compared to those using no magnification.

Methods: Upon institutional review board exemption, third-year dental students were assessed during endodontics and fixed prosthodontics exams in the simulation laboratory. The endodontic group (n = 93) consisted of students who made an endodontic access preparation on a plastic lower left first molar (Nissan). The prosthodontic group (n = 86) consisted of students who made porcelain fused to metal preparation (PFM) on a plastic lower right first molar mounted on an acrylic lower jaw model (Columbia Dentoform). The impact of the use of dental loupes was evaluated. Assessment of the tasks was undertaken by experts-calibrated, blinded examiners-using a standardized marking rubric for each task. The statistical analysis included Chi-square test, one-way ANOVA, and Logistic regression. The level of significance adopted was 5%.

Results: Students' preparations using magnification were better compared with those without magnification. Students using magnification had a significantly higher pass rate than those not using magnification in both endodontic and prosthodontic groups (P < 0.05).

Conclusions: In conclusion, third-year dental students who used loupes in the endodontics and prosthodontics simulation laboratory had significantly higher scores at the assessments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jdd.12437DOI Listing
March 2021

Knowledge about Coronavirus disease 19 (COVID-19) and its professional repercussions among Brazilian endodontists.

Braz Oral Res 2020 Sep 4;34:e117. Epub 2020 Sep 4.

Centro Universitário Christus, School of Dentistry, Post-graduation Program of Dental Sciences, Fortaleza, CE, Brazil.

The aim of this study was to assess Brazilian endodontists' level of knowledge about the coronavirus disease (COVID-19) and examine its professional repercussions. The link to the online survey that was created for this study was shared with Brazilian endodontists through social networking applications. The questionnaire contained questions that pertained to COVID-19 and its impact on dental practice. The collected data were analyzed using t-test, chi-square analysis, and analysis of variance, and the level of significance was set at 0.05. A total of 2,135 participants responded to the questionnaire, and all five Brazilian regions were represented in the sample. A total of 98.50% of endodontists reported that dental procedures can transmit COVID-19. Complete social distancing was practiced by 96.68% of the participants, and approximately 25% knew someone who had COVID-19. Moreover, in their daily practice, 72.13% of them implemented biosecurity measures that are ineffective in preventing COVID-19. Furthermore, 91.7% of them reportedly suspended elective dental procedures. Only 55.69% of them reported that they performed only emergency procedures in their workplaces. Those who believed that COVID-19 cannot be transmitted during dental procedures were less knowledgeable about the symptoms of COVID-19 (p = 0.0095). Endodontists who believed that personal protective equipment cannot prevent contamination were more knowledgeable about the symptoms of COVID-19 than their counterparts (p = 0.0003). The participating Brazilian endodontists demonstrated adequate knowledge about the risk of contamination during dental procedures and the main symptoms of COVID-19. Only some professionals reported providing emergency dental care during the pandemic.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/1807-3107bor-2020.vol34.0117DOI Listing
September 2020

Influence of Different Coronal Preflaring Protocols on Electronic Foramen Locators Precision.

Braz Dent J 2020 Sep 4;31(4):404-408. Epub 2020 Sep 4.

Post-graduate Program in Dentistry, UFC - Universidade Federal do Ceará, Fortaleza, CE, Brazil.

The aim of this study was to evaluate the influence of different coronal preflaring protocols (absent, conservative and conventional) on the accuracy of Root ZX II, Raypex 6, and RomiApex A-15 electronic foramen locators (EFLs). Twenty mandibular molars with Vertucci's type IV mesial roots were subjected to endodontic exploration and foraminal patency confirmation. Under 16x magnification, its real lengths (RL) were measured and registered (RL1). The canals were then irrigated with 2.5% sodium hypochlorite and electronically measured (EM1) employing the alginate model; all measurements were performed in triplicate by a blind operator using adjusted endodontic hand-files introduced until the apex foramen. Coronal preflaring procedures were sequentially performed with #25/.06 (conservative) and #25/.12 (conventional) instruments; new RLs extents were performed after each coronal preparation protocol (RL2/RL3), as same as electronic measurements (EM2/EM3). The devices error (mm) was evaluated considering the difference between RLs and EMs at each preparation stage; their precision was stablished adopting ±0.5 mm as tolerance margin. The EFLs error significantly reduced after conventional coronal preflaring protocol (p<0.05), which not occur after the conservative one. The best precisions values were noted after conventional preparation as 90% (Root ZX II), 97.5% (Raypex 6), and 92.5% (RomiApex A-15). No significant differences were found in EFLs comparisons, regardless of the coronal protocol tested (p>0.05). Under the conditions tested it can be concluded that the EFLs evaluated were precise. Moreover, the preflaring protocols influences its accuracy's, where the less conservative one produced the best results.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/0103-6440202003282DOI Listing
September 2020

Comparison of Canal Transportation and Centering Ability of ProGlider and WaveOne Gold Glider in Curved Canals.

Eur J Dent 2020 Oct 31;14(4):639-643. Epub 2020 Aug 31.

School of Health Sciences, Universidade Positivo, Curitiba, Paraná, Brazil.

Objectives:  The aim of this study was to compare the volume variation and maintenance of the root canal position when using the ProGlider 16.02 (PG) and the WaveOne Gold Glider 15.02 (WOGG) file systems for glide path preparation.

Materials And Methods:  Twenty-four moderately curved mesiobuccal canals of maxil-lary first molars were selected and randomly divided into two groups: PG and WOGG. The selected teeth were scanned using microtomography before and after root canal preparation to assess centralization and linear transport at 1, 3, 5, and 7 mm from the apical foramen.

Statistical Analysis:  The data were analyzed with the Mann-Whitney U test. The level of significance was 5%.

Results:  There were no significant differences in volume variation or root canal transport ( > 0.05). There was a significant difference in the centralization of the root canal at 3 mm from the foramen ( < 0.05).

Conclusions:  WOGG and PG instruments presented similar results regarding the root canal volume increase and transport. WOGG caused higher decentralization at 3 mm from the apical foramen.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0040-1715780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536097PMC
October 2020

New Surgical Model for Bone-Muscle Injury Reveals Age and Gender-Related Healing Patterns in the 5 Lipoxygenase (5LO) Knockout Mouse.

Front Endocrinol (Lausanne) 2020 11;11:484. Epub 2020 Aug 11.

Department of Basic Sciences, School of Dentistry, São Paulo State University (UNESP), Araçatuba, Brazil.

Signaling lipid mediators released from 5 lipoxygenase (5LO) pathways influence both bone and muscle cells, interfering in their proliferation and differentiation capacities. A major limitation to studying inflammatory signaling pathways in bone and muscle healing is the inadequacy of available animal models. We developed a surgical injury model in the (VL) muscle and femur in 129/SvEv littermates mice to study simultaneous musculoskeletal (MSK) healing in male and female, young (3 months) and aged (18 months) WT mice compared to mice lacking 5LO (5LOKO). MSK defects were surgically created using a 1-mm punch device in the VA muscle followed by a 0.5-mm round defect in the femur. After days 7 and 14 post-surgery, the specimens were removed for microtomography (microCT), histopathology, and immunohistochemistry analyses. In addition, non-injured control skeletal muscles along with femur and L5 vertebrae were analyzed. Bones were microCT phenotyped, revealing that aged female WT mice presented reduced BV/TV and trabecular parameters compared to aged males and aged female 5LOKO mice. Skeletal muscles underwent a customized targeted lipidomics investigation for profiling and quantification of lipid signaling mediators (LMs), evidencing age, and gender related-differences in aged female 5LOKO mice compared to matched WT. Histological analysis revealed a suitable bone-healing process with osteoid deposition at day 7 post-surgery, followed by woven bone at day 14 post-surgery, observed in all young mice. Aged WT females displayed increased inflammatory response at day 7 post-surgery, delayed bone matrix maturation, and increased TRAP immunolabeling at day 14 post-surgery compared to 5LOKO females. Skeletal muscles of aged animals showed higher levels of inflammation in comparison to young controls at day 14 post-surgery; however, inflammatory process was attenuated in aged 5LOKO mice compared to aged WT. In conclusion, this new model shows that MSK healing is influenced by age, gender, and the 5LO pathway, which might serve as a potential target to investigate therapeutic interventions and age-related MSK diseases. Our new model is suitable for bone-muscle crosstalk studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fendo.2020.00484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431610PMC
June 2021

Cyclic Fatigue Resistance of Nickel-Titanium Reciprocating Instruments after Simulated Clinical Use.

J Endod 2020 Aug 18. Epub 2020 Aug 18.

Department of Dentistry, Endodontics, and Dental Materials, School of Dentistry of Bauru, University of São Paulo, São Paulo, São Paulo, Brazil.

Introduction: The aim of this study was to evaluate the cyclic fatigue resistance of different heat-treated nickel-titanium reciprocating instruments in 2 different situations: new and used instruments after preparing 3 curved canals.

Methods: A total sample of 60 nickel-titanium instruments of 3 systems (n = 20 per system) were used in this study: ProDesign R (tip 25, 0.06 taper; Easy Dental Equipment, Belo Horizonte, Brazil), Reciproc Blue (tip 25, 0.08v taper; VDW, Munich, Germany), and WaveOne Gold (tip 25, 0.07v taper; Dentsply Sirona, Ballaigues, Switzerland). Thirty new instruments (n = 10 per system) were used to prepare 90 curved single-rooted mandibular premolars (n = 30). Each instrument was used to prepare 3 root canals, and after each canal preparation the instrument was ultrasonic cleaned and submitted to autoclave sterilization procedures. The other 30 instruments (n = 10 per system) were kept without use. Then, the new and used instruments were subjected to the cyclic fatigue test in an artificial canal with a 30° angle and a 5-mm radius of curvature. The time and number of cycles to fatigue were recorded. Data were analyzed using the unpaired t test for intragroup comparison. For intergroup comparison, analysis of variance and the Tukey test for multiple comparisons were used.

Results: The intergroup comparison of new instruments showed that ProDesign R had the highest cyclic fatigue resistance followed by Reciproc Blue and WaveOne Gold (P < .05). Regarding the used instruments, WaveOne Gold had the lowest cyclic fatigue resistance (P < .05). The intragroup comparison between new and used instruments showed that WaveOne Gold and ProDesign R presented a significant reduction in the cyclic fatigue resistance after simulated clinical use (P < .05); no difference was found with the Reciproc Blue instruments (P > .05).

Conclusions: ProDesign R had the highest cyclic fatigue resistance, whereas WaveOne Gold had the lowest for new and used instruments. Simulated clinical use affected the cyclic fatigue resistance of ProDesign R and WaveOne Gold but not of Reciproc Blue instruments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.joen.2020.08.010DOI Listing
August 2020

Dental discoloration caused by Grey-MTAFlow cement: analysis of its physicochemical, biological and antimicrobial properties.

J Appl Oral Sci 2020 5;28:e20200269. Epub 2020 Aug 5.

Faculdade de Odontologia de Piracicaba, Universidade de Campinas, Piracicaba, São Paulo, Brasil.

Tricalcium silicate-based cement are materials used in reparative and regenerative procedures in endodontics. A recently proposed formulation aimed to enhance handling during clinical use with a versatile material applicable by syringe. Although, the use of bismuth oxide as radiopacifier and grey raw powder are drawbacks considering aesthetics. Objectives Evaluate physicochemical, biological, and antimicrobial properties of Grey-MTAFlow (Ultradent) and assess whether the addition of zinc oxide (ZnO) prevents dentinal discoloration caused by bismuth oxide. Methodology Grey-MTAFlow was manipulated in 'thin' consistency for all tests. Luminosity, color change, ion migration to dentine, radiopacity, setting time, ISO 6876:2012 linear flow, volumetric lateral flow and central filling of simulated grooves scanned using micro-computed tomography (μCT), pH, calcium release, volumetric change using μCT, chemical characterisation, cytotoxicity, and antimicrobial activity were assessed. Addition of 5% ZnO to Grey-MTAFlow and a bismuth-containing experimental composition were comparatively tested. Statistical analyses used Shapiro-Wilk, T-test, ANOVA, and Kolmogorov-Smirnov (p<0.05). Results The addition of ZnO to Grey-MTAFlow prevented dentine darkening after 90 days due to bismuth migration reduction, although no statistical difference was found (p=0.863). ZnO addition significantly enhanced Grey-MTAFlow radiopacity without differences in initial setting time. Grey-MTAFlow presented an ISO linear flow of 10.9 mm and a balanced volumetric lateral flow with central filling in μCT evaluation. All compositions presented an alkaline pH after immersion. Grey-MTAFlow had a significantly higher calcium ion release after 28 days in comparison to 24 hours (p=0.011) and volumetric expansion of 0.4±1.8% after immersion. ZnO addition altered the hydrated cement matrix once calcium hydroxide (portlandite) could not be detected in characterisation. Neither of the materials produced inhibition halos nor reduced bacterial turbidity, but all presented cytocompatibility above 100%. Conclusion Grey-MTAFlow expanded after immersion and exhibited higher luminosity values after the evaluation period when ZnO was added, but chemical modifications after this addition occurred.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/1678-7757-2020-0269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406195PMC
October 2020

Comparison of marginal adaptation and internal fit of monolithic lithium disilicate crowns produced by 4 different CAD/CAM systems.

Clin Oral Investig 2021 Apr 11;25(4):2029-2036. Epub 2020 Aug 11.

Department of Prosthodontics and Periodontics, Bauru School of Dentistry, University of São Paulo, Alameda Doutor Octávio Pinheiro Brisolla, 9-75, Bauru, SP, 17012-901, Brazil.

Objectives: To evaluate the marginal adaptation and internal space of crowns produced by 4 CAD/CAM systems using microcomputed tomography (μCT) and replica technique (RT).

Materials And Methods: Monolithic lithium disilicate crowns were milled (Ceramill, Cerec, EDG, and Zirkonzahn) (n = 10). The cement film obtained with low viscosity silicone was scanned by the μCT system and captured by a stereomicroscope, according to RT. Two-way ANOVA followed by Tukey's test were used for statistical analysis (α = 0.05). A uniformity index (UI) was idealized to describe the distribution of crowns' internal space and submitted to the Kruskal-Wallis and Tukey's test (α = 0.05). The correlation between μCT and RT was performed by Pearson's Correlation Coeficient (α = 0.05).

Results: Marginal adaptation and internal space were statistically significant different between the experimental groups for the μCT and RT (p < 0.05). The medians of the 4 systems tested were within clinically acceptable range and the mean (± SD) highest marginal discrepancy was recorded in the Ceramill group at 133.0 ± 71.5 μm (μCT) and 90.6 ± 38.5 μm (RT). For internal fit, the UI disclosed a better distribution of the internal space for the Zirkonzahn group (p < 0.001). There was a strong correlation between the methods (p = 0.01 and r = 0.69).

Clinical Relevance: Because of the variability of the CAD/CAM systems available, evaluating their accuracy is of clinical interest. The 4 systems are capable to produce restorations adaptated within clinically appropriate levels. The μCT and RT are efficient adaptation methodologies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00784-020-03511-1DOI Listing
April 2021

Comparison of the Self-Adjusting File and Hedström File Used as Supplementary Instruments for the Remaining Filling Material Removal During Retreatment of C-Shaped Canals: A Micro-CT Study.

Eur Endod J 2020 11;5(2):112-117. Epub 2020 Jun 11.

Department of Endodontics, Faculdade de Odontologia de Bauru, São Paulo University, Bauru, São Paulo, Brazil.

Objective: The aim of this study was to evaluate the use of Self-adjusting file (SAF) system and Hedström (H) file for removing remaining filling material (RFM) from C-shaped canals.

Methods: 20 C-shaped mandibular second molars with C1 configurations were instrumented, filled with tagger´s hybrid technique. Samples were divided into 2 groups (n=10). Reciproc R25 and a Mtwo 35/04 file were used for retreatment in both groups. Then, a 2.0 SAF file (group I) and a #35 H file (group II) were used as supplementary steps for RFM removal. Micro-CT scanning was performed after every procedure. Total volumes were calculated and converted into percentages. Also, the minimum wall thickness at 3, 5, 7 mm from apex was calculated. The Prism 7.0 software was used as the analytical tool with a significance of 5%.

Results: Initial obturation removal was approximately 64% in group I and 67% in Group II. The apical third had the highest values of RFM. The use of a H file significantly reduced the RFM compared to SAF in the total canal length respectively (30% vs 18%) and at 1-3 mm and 3-6 mm when compared to the use of SAF. A statistically significant decrease of RFM and minimum wall thickness were observed in both groups (P<0.05).

Conclusion: None of the retreatment techniques completely removed RFM. The apical region was the more unaffected area. Also, the SAF file was less effective than the H file in removing the RFM. Although C-shaped canals possesses thinner dentinal wall thickness, no excessive dentine removal was observed after each instrument use.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.14744/eej.2019-07-067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7398992PMC
June 2020

Influence of the Preparation Order in Four-Canal Maxillary Molars with WaveOne Gold System.

J Endod 2020 Sep 10;46(9):1291-1296. Epub 2020 Jun 10.

School of Health Sciences, Universidade Positivo, Curitiba, Paraná, Brazil; Department of Dentistry, Universidade da Região de Joinville, Joinville, Santa Catarina, Brazil.

Introduction: The aim of this study was to evaluate the effect of the order of preparation of four-canal maxillary molars on volume variation, instrument deformation, cyclic fatigue, and preparation time by using the WaveOne Gold Primary (WOG 25.07).

Methods: We selected 48 permanent, human, four-canal maxillary molars. The teeth were divided into 4 groups according to the order of initiation of the canal preparation sequence: (1) mesiobuccal (MB), distobuccal (DB), palatal (P), second mesiobuccal (MB2); (2) DB-P-MB2-MB; (3) P-MB2-MB-DB and (4) MB2-MB-DB-P. Pre- and post-preparation microtomography scanning was performed to obtain initial and final canal volume measurements. The instruments were also evaluated by using scanning electron microscopy to determine the wear and deformation present after use. The active instrumentation time was also recorded. The data were statistically compared by using a significance level of 5%.

Results: No statistically significant difference was found between groups for volume variation and time of preparation of the canals with the WOG system (P > .05); however, a statistically significant difference was observed in the deformation of the instruments. In the comparison between the groups for MB-DB-P-MB2 and P-MB2-MB-DB, the latter presented greater deformation of the instruments.

Conclusions: Root canal preparation sequence affected deformation of the instruments but did not influence the volume variation or the canal preparation time with the WOG system. To minimize instrument deformation, the preparation order should be MB-DB-P-MB2.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.joen.2020.05.018DOI Listing
September 2020

Elastin-derived scaffolding associated or not with bone morphogenetic protein (BMP) or hydroxyapatite (HA) in the repair process of metaphyseal bone defects.

PLoS One 2020 20;15(4):e0231112. Epub 2020 Apr 20.

Department of Morphology and Pathology, Medical College of Jundiai, Jundiaí, São Paulo, Brazil.

Tissue engineering represents a promising alternative for reconstructive surgical procedures especially for the repair of bone defects that do not regenerate spontaneously. The present study aimed to evaluate the effects of the elastin matrix (E24/50 and E96/37) incorporated with hydroxyapatite (HA) or morphogenetic protein (BMP) on the bone repair process in the distal metaphysis of rat femur. The groups were: control group (CG), hydrolyzed elastin matrix at 50°C/24h (E24/50), E24/50 + HA (E24/50/HA), E24/50 + BMP (E24/50/BMP), hydrolyzed elastin matrix at 37°C/96h (E96/37), E96/37 + HA (E96/37/HA), E96/37 + BMP (E96/37/BMP). Macroscopic and radiographic analyses showed longitudinal integrity of the femur in all groups without fractures or bone deformities. Microtomographically, all groups demonstrated partial closure by mineralized tissue except for the E96/37/HA group with hyperdense thin bridge formation interconnecting the edges of the ruptured cortical. Histologically, there was no complete cortical recovery in any group, but partial closure with trabecular bone. In defects filled with biomaterials, no chronic inflammatory response or foreign body type was observed. The mean volume of new bone formed was statistically significant higher in the E96/37/HA and E24/50 groups (71.28 ± 4.26 and 66.40 ± 3.69, respectively) than all the others. In the confocal analysis, it was observed that all groups presented new bone markings formed during the experimental period, being less evident in the CG group. Von Kossa staining revealed intense calcium deposits distributed in all groups. Qualitative analysis of collagen fibers under polarized light showed a predominance of red-orange birefringence in the newly regenerated bone with no difference between groups. It was concluded that the E24/50 and E96/37/HA groups promoted, with greater speed, the bone repair process in the distal metaphysis of rat femur.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231112PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7170266PMC
July 2020

Influence of cervical preflaring and root canal preparation on the fracture resistance of endodontically treated teeth.

BMC Oral Health 2020 04 16;20(1):111. Epub 2020 Apr 16.

Departamento de Odontologia Conservadora, Universidade Federal do Rio Grande do Sul, 2492 Ramiro Barcelos Street, Porto Alegre, RS, 90035-003, Brazil.

Background: Evaluate the fracture resistance of endodontically treated teeth after cervical preflaring and root canal preparation and to assess the volume of the root canal and the amount of remaining root dentin before and after cervical preflaring.

Methods: Forty-four mandibular incisors were selected using micro-CT scanning and distributed into 4 groups (n = 11) according to the instrument used for cervical preflaring: control group - no cervical preflaring; Gates Glidden - burs size #2 and #3; WXN - 25.07 Navigator instrument; and Easy - 25.08 ProDesign S instrument. Coronal opening was performed, and the canals were prepared with Wave One Gold Primary and filled with an epoxy-resin based sealer and gutta-percha cones. Micro-CT scans were performed before and after root canal instrumentation. All images were reconstructed and assessed for the thickness of mesial and distal root dentin at 3 mm and 5 mm from the cement -enamel junction and for the volume of cervical portion of the canal after preparation. Fracture resistance test was performed applying compressive loads at a crosshead speed of 0.5 mm/min, applied on the palatal aspect of specimens at 135° along the long axis of the tooth. The data were analyzed using ANOVA and Tukey's test (P = .05).

Results: Cervical preflaring and canal preparation reduced the dentin thickness (P < .05) and increased the canal volume (P < .05) in all groups at 3 mm an 5 mm. Cervical preflaring with Gates Gliden burs reduced the fracture resistance of endodontically treated teeth (P < .05).

Conclusions: All instruments reduced the dentin thickness and increased the canal volume in the cervical at 3 mm and 5 mm. Gates Glidden reduced fracture resistance of mandibular incisors submitted to cervical preflaring, whereas NiTi instruments did not.

Clinical Relevance: Cervical preflaring assumes particular importance previously to the root canal preparation because it minimizes the occurrence of operative accidents, and permits more accurate determination of working length and the apical diameter.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12903-020-1050-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7161170PMC
April 2020
-->