Shaping ability of rotary or reciprocating systems for oval root canal preparation: a micro-computed tomography study.

OBJECTIVES: To evaluate the shaping ability and cleaning after oval root canal preparation using one or more instruments in reciprocating or rotary motion. MATERIALS AND METHODS: Oval-shaped mandibular incisors were selected, based on the radiographic diameter (2 ≤ diameter ratio ≤ 4), and assigned according to root canal preparation (n = 18): single-file (Reciproc R40); two reciprocating files (Unicone size 20 and 40, .06 taper) or Mtwo rotary files until a size 40, .06 taper instrument. Root canal preparations were performed using an open root canal model. Scanning was performed before and after preparation using SkyScan 1176 with a voxel size of 17.42 µm. Volume, percentage of debris, and percentage of uninstrumented surface were analyzed in the entire root canal and in each root canal third. Data were compared using ANOVA and Tukey or Kruskal-Wallis and Dunn tests (α = 5%). RESULTS: The initial volume were similar among the groups (p > .05). Unicone preparation was associated with higher debris, increase in root canal volume and uninstrumented surface in entire root canal and in the middle third (P < .05). Mtwo was associated with lower uninstrumented surface in the entire root canal and in the cervical third. The apical third were similar for the three preparations. CONCLUSIONS: Unicone system using two instruments in reciprocating motion resulted in higher increase in volume. However, less remaining debris was observed when Reciproc single-file and Mtwo rotary systems were used. CLINICAL RELEVANCE: A preparation that volumetrically increases the root canal is not necessarily associated with better cleaning. Shaping and hard-tissue debris removal depends on root canal anatomy, kinematics, number of instruments, and instrument design.

Ultrasound Effect in the Removal of Intraradicular Posts Cemented with Different Materials.

AIM: This study evaluated the effect of ultrasonic vibration on the tensile strength required to remove intraradicular post cemented with different materials. MATERIALS AND METHODS: Bovine teeth were selected, and 7 mm of the cervical root canals were prepared to size 5 Largo drill, the posts were cemented with zinc phosphate, Enforce (resin) or Rely X (glass ionomer). The specimens were divided into six groups (n = 10), according to the following procedures: GI-cementation with zinc phosphate associated with traction force; GII-cementation with zinc phosphate associated with ultrasonic activation and traction force; G111-cementation with Enforce associated with traction force; GIV-cementation with Enforce associated with ultrasonic activation and traction force; GV-cementation with Rely X associated with traction force; and GVI-cementation with Rely X associated with ultrasonic activation and traction force. The tensile test was conducted using the electromechanical testing machine, the force was determined by a specialized computer program and ultrasonic activation using the Jet Sonic Four Plus (Gnatus) device in 10P. RESULTS: Concerning to average ranking, GI showed statistically significant difference in comparison with GII and GVI (p < 0.05); there was no statistical difference in GIII and GIV when compared to other groups (p > 0.05). CONCLUSION: The ultrasound favored the intraradicular post traction regardless of the employed cement in greater or lesser extent. CLINICAL SIGNIFICANCE: The post removal is a routine practice in the dental office, therefore, new solutions and better alternatives are need to the practitioner. We did not find in the literature many articles referring to this practice. Thus, the results from this study are relevant in the case planning and to promote more treatment options.

Root Canal Preparation and Enlargement Using Thermally Treated Nickel-Titanium Rotary Systems in Curved Canals.

INTRODUCTION: The purpose of this study was to evaluate root canal preparation and apical enlargement of curved canals using rotary heat-treated and heat/surface-treated systems by micro-computed tomographic imaging. METHODS: Curved mesial root canals (n = 48) of mandibular molars (20°-40°) were prepared using ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 25/.01 and 25/.06 or HyFlex EDM (HFEDM) 10/.05, HyFlex CM 20/.04, and HFEDM 25/.08. Apical enlargement was performed using PDL 40/.05 or HFEDM 40/.04. Scanning (9 µm) was performed before and after preparation and after apical enlargement using micro-computed tomographic imaging. Volume, percentage of volume increase, debris, untouched root canal surface, and centering ability were analyzed. Statistical analysis was performed using Mann-Whitney, Wilcoxon, and unpaired t tests (α = .05). RESULTS: HFEDM promoted a higher volume increase of the root canals than PDL after preparation and after apical enlargement (P < .05). The apical enlargement promoted a significant decrease in debris and untouched surface in both groups (P < .05). The percentage of debris and untouched surface were similar between HFEDM and PDL after preparation and after apical enlargement (P > .05). Both systems promoted centered canals (P > .05). CONCLUSIONS: HFEDM instruments promoted greater volume of the root canal than PDL. However, the cleaning ability of the instruments was similar. The apical increase up to size 40 with both instruments provided less debris and untouched surfaces and allowed centralization of the curved root canals.

Solubility, Porosity, Dimensional and Volumetric Change of Endodontic Sealers.

The aim of this study was to evaluate physical properties of endodontic sealers (AH Plus, MTA Fillapex and Endofill), by conventional and micro-CT tests. Dimensional stability was evaluated after immersion of materials in distilled water for 30 days. Solubility and volumetric change were evaluated after 7 and 30 days of immersion in distilled water. Solubility was evaluated by means of mass loss and volumetric change was assessed by micro-CT. Porosity was evaluated under a microscope after 7 days of immersion in distilled water, and by using micro-CT after setting and immersion in distilled water for 7 and 30 days. Statistical analysis was performed by ANOVA and Tukey's test with 5% significance level. MTA Fillapex presented the highest solubility (p<0.05), showing values above the ISO/ADA recommendations. MTA Fillapex presented higher volumetric and dimensional changes, followed by Endofill and AH Plus (p<0.05). Dimensional stability of the MTA Fillapex and AH Plus did not follow ISO/ADA standards. The highest total porosity was observed for MTA Fillapex (p<0.05). Endofill had higher total porosity than AH Plus according to microscope evaluation (p<0,05), and both sealers were similar in micro-CT assessment (p>0,05). In conclusion, MTA Fillapex presented higher solubility, dimensional and volumetric change besides porosity compared to the other evaluated sealers. The assessed physical properties of sealers are related, and the different tests provided complementary data. Micro-CT is a valuable method for assessment of physical properties of endodontic materials.

Evaluation of physicochemical properties of root-end filling materials using conventional and Micro-CT tests.

OBJECTIVE: To evaluate solubility, dimensional stability, filling ability and volumetric change of root-end filling materials using conventional tests and new Micro-CT-based methods. MATERIAL AND METHODS: 7. RESULTS: The results suggested correlated or complementary data between the proposed tests. At 7 days, BIO showed higher solubility and at 30 days, showed higher volumetric change in comparison with MTA (p<0.05). With regard to volumetric change, the tested materials were similar (p>0.05) at 7 days. At 30 days, they presented similar solubility. BIO and MTA showed higher dimensional stability than ZOE (p<0.05). ZOE and BIO showed higher filling ability (p<0.05). CONCLUSIONS: ZOE presented a higher dimensional change, and BIO had greater solubility after 7 days. BIO presented filling ability and dimensional stability, but greater volumetric change than MTA after 30 days. Micro-CT can provide important data on the physicochemical properties of materials complementing conventional tests.

Effect of ProTaper and Reciproc preparation and gutta-percha cone on cold lateral compaction.

CONTEXT: The effectiveness of cold lateral compaction depends on the root canal preparation and used gutta-percha cone. AIMS: The aim of this study is to evaluate finger spreader penetration into root canals prepared with ProTaper (PT) or Reciproc (Rec) systems and filled with gutta-percha cones with different tapers. MATERIALS AND METHODS: Twenty-four simulated root canals in resin blocks with 30° curvature were prepared up to PT F2 or Rec R25. They were divided into four experimental groups according to the master gutta-percha cone and preparation (25.02 or F2/PT, and 25.02 or R25/Rec). Cold lateral compaction was performed using a stainless steel finger spreader size B. The set cone-finger spreader-resin block was placed in a universal test machine, and a load up to 1.5 kg was applied on the finger spreader. The final distance between the finger spreader and apical preparation after load application was obtained. For comparison among the groups, data were submitted to ANOVA and Tukey's tests, with a significance level of 5%. RESULTS: Greater finger spreader penetration was observed for 0.02/Rec and 0.02/PT, followed by F2/PT and R25/Rec. CONCLUSION: The use of cones associated with PT and Rec preparations does not allow the finger spreader penetration up to the apical third.

Solubility and bacterial sealing ability of MTA and root-end filling materials.

Objective To evaluate solubility and sealing ability of Mineral Trioxide Aggregate (MTA) and root-end filling materials. Material and Methods The materials evaluated were: MTA, Calcium Silicate Cement with zirconium oxide (CSC/ZrO2), and zinc oxide/eugenol (ZOE). Solubility test was performed according to ANSI/ADA. The difference between initial and final mass of the materials was analyzed after immersion in distilled water for 7 and 30 days. Retrograde cavities in human teeth with single straight root canal were performed by using ultrasonic tip CVD 9.5107-8. The cavities were filled with the evaluated materials to evaluate sealing ability using the bacterial leakage test with Enterococcus faecalis. Bacterial leakage was evaluated every 24 hours for six weeks observing the turbidity of Brain Heart infusion (BHI) medium in contact with root apex. Data were submitted to ANOVA followed by Tukey tests (solubility), and Kruskal-Wallis and Dunn tests (sealing ability) at a 5% significance level. Results For the 7-day period, ZOE presented highest solubility when compared with the other groups (p<0.05). For the 30-day period, no difference was observed among the materials. Lower bacterial leakage was observed for MTA and CSC/ZrO2, and both presented better results than ZOE (p<0.05). Conclusion MTA and CSC/ZrO2 presented better bacterial sealing capacity, which may be related to lower initial solubility observed for these materials in relation to ZOE.

Micro-CT analysis of filling ability and porosity of root-end filling materials / Análise em micro-CT da capacidade de preenchimento e porosidade de materiais retrobturadores

Introduction: Filling ability of retrograde cavity and porosity are important properties for root-end filling materials and may be evaluated by using microcomputed tomography (micro-CT). Objective: To evaluate filling ability and porosity of root-end filling materials using microcomputed tomography (micro-CT). Material and method: Cavities with 1 mm internal diameter and 3 mm depth were prepared in bovine dentin sections by using ultrasonic tips (CVD No. 6.1107-6), and filled by Mineral Trioxide Aggregate (MTA); Sealer 26 (S26) and zinc oxide and eugenol cement (ZOE). Before and after filling, cavities were scanned by using micro-CT (SkyScan 1176). Filling and porosity were analyzed by using CTAn software. Filling ability was calculated based on volumetric percentage of the filled cavity. The number and percentage of closed pores were measured throughout entire extension of the filled cavity (total) and in each third (cervical, middle and apical), by using bi and tridimensional analyses. The filling data were submitted to ANOVA and Tukey statistical tests, and porosity data to Kruskall-Wallis and Dunn tests, at a 5% significance level. Result: S26 and ZOE presented higher filling ability than MTA (p<0.05). S26 showed the highest total porosity (number and percentage) (p<0.05). In all thirds after 2D and 3D analyses, porosity was higher for S26 in comparison to MTA and ZOE (p<0.05). Conclusion: Although Sealer 26 presented more porosity, the material was associated with a great filling ability. Micro-CT analysis showed no correlation between filling ability and porosity.

Introdução: Capacidade de preenchimento da cavidade retrógrada e porosidade são propriedades importantes de materiais retrobturadores e podem ser avaliadas por meio de microtomografia computadorizada (micro-CT). Objetivo: Avaliar a capacidade de preenchimento e porosidade de materiais retrobturadores por meio de micro-CT. Material e método: Cavidades com 1 mm de diâmetro e 3 mm de altura foram preparadas em dentina bovina utilizando pontas ultrassônicas (CVD No. 6.1107-6) e foram preenchidas com Mineral Trióxido Agregado (MTA), Sealer 26 (S26) e cimento de óxido de zinco e eugenol (OZE). As cavidades foram escaneadas em micro-CT antes e após o preenchimento. A capacidade de preenchimento foi calculada com base na porcentagem em volume, das cavidades preenchidas. O número e porcentagem dos poros fechados foram avaliados em toda extensão da cavidade preenchida (total) e por terços (cervical, médio e apical) por meio de análises bi e tridimensionais. Os dados de preenchimento foram submetidos aos testes estatísticos ANOVA e Tukey e a porosidade aos testes de Kruskall-Wallis e Dunn, com nível de significância de 5%. Resultado: S26 e OZE apresentaram maior capacidade de preenchimento que o MTA (p<0,05). S26 mostrou maior porosidade total (em número e porcentagem) (p<0,05). Em todos os terços, após as análises 2D e 3D, a porosidade foi maior para S26 em comparação ao MTA e OZE (p<0,05). Conclusão: Embora Sealer 26 tenha apresentado maior porosidade, o material foi associado a uma adequada capacidade de preenchimento. A análise em micro-CT mostrou ausência de correlação entre capacidade de preenchimento e porosidade.

Evaluation of physicochemical properties of root-end filling materials using conventional and Micro-CT tests

Abstract Objective To evaluate solubility, dimensional stability, filling ability and volumetric change of root-end filling materials using conventional tests and new Micro-CT-based methods. Material and Methods Solubility (loss of mass) after 7 and 30 days, and dimensional stability (in mm) were evaluated in accordance with Carvalho-Junior, et al. 7 (2007). The filling ability and volumetric change (in mm3) were evaluated by Micro-CT (Bruker-MicroCT, Kontich, Belgium) using resin models with cavities 3 mm deep and 1 mm in diameter. The cavities were filled with materials to evaluate filling ability, and then scanned by Micro-CT. After 7 and 30 days immersed in distilled water, the filled cavities were scanned again to evaluate the volumetric change. MTA Angelus (MTA), Biodentine (BIO) and zinc oxide-eugenol cement (ZOE) were evaluated. Data were submitted to analysis of variance (ANOVA) and Tukey's test with 5% significance level. Results The results suggested correlated or complementary data between the proposed tests. At 7 days, BIO showed higher solubility and at 30 days, showed higher volumetric change in comparison with MTA (p<0.05). With regard to volumetric change, the tested materials were similar (p>0.05) at 7 days. At 30 days, they presented similar solubility. BIO and MTA showed higher dimensional stability than ZOE (p<0.05). ZOE and BIO showed higher filling ability (p<0.05). Conclusions ZOE presented a higher dimensional change, and BIO had greater solubility after 7 days. BIO presented filling ability and dimensional stability, but greater volumetric change than MTA after 30 days. Micro-CT can provide important data on the physicochemical properties of materials complementing conventional tests.

Solubility and bacterial sealing ability of MTA and root-end filling materials

ABSTRACT Objective To evaluate solubility and sealing ability of Mineral Trioxide Aggregate (MTA) and root-end filling materials. Material and Methods The materials evaluated were: MTA, Calcium Silicate Cement with zirconium oxide (CSC/ZrO2), and zinc oxide/eugenol (ZOE). Solubility test was performed according to ANSI/ADA. The difference between initial and final mass of the materials was analyzed after immersion in distilled water for 7 and 30 days. Retrograde cavities in human teeth with single straight root canal were performed by using ultrasonic tip CVD 9.5107-8. The cavities were filled with the evaluated materials to evaluate sealing ability using the bacterial leakage test with Enterococcus faecalis. Bacterial leakage was evaluated every 24 hours for six weeks observing the turbidity of Brain Heart infusion (BHI) medium in contact with root apex. Data were submitted to ANOVA followed by Tukey tests (solubility), and Kruskal-Wallis and Dunn tests (sealing ability) at a 5% significance level. Results For the 7-day period, ZOE presented highest solubility when compared with the other groups (p<0.05). For the 30-day period, no difference was observed among the materials. Lower bacterial leakage was observed for MTA and CSC/ZrO2, and both presented better results than ZOE (p<0.05). Conclusion MTA and CSC/ZrO2 presented better bacterial sealing capacity, which may be related to lower initial solubility observed for these materials in relation to ZOE.

Alteração volumétrica por análise microtomográfica, solubilidade e capacidade seladora bacteriana de diferentes materiais retro-obturadores / Volumetric changes by microtomografic analyses, solubility and bacterial sealing ability of different root-end filling materials

O objetivo deste estudo foi avaliar os materiais retro-obturadores MTA, Cimento Portland associado a 30% de óxido de zircônio (CP/ZrO2) e óxido de zinco e eugenol (OZE). Para análise microtomográfica da alteração volumétrica, cavidades retrógradas foram confeccionadas em dentina bovina e preenchidas com os materiais experimentais, sendo analisados pelo microtomógrafo Sky Scan 1176. A avaliação de solubilidade foi realizada de acordo com normas ISO 6876, por meio da diferença de massa inicial e após 7 dias de imersão em água destilada. A análise da capacidade seladora bacteriana foi realizada em dentes humanos extraídos. Cavidades retrógradas confeccionadas foram preenchidas de acordo com os materiais experimentais (n=12), além do controle positivo (n=8), sem preenchimento, e controle negativo (n=8), com impermeabilização em toda extensão. As amostras foram submetidas à infiltração utilizando cepas de Enteroccocus faecalis (ATCC 29212) em meio de cultura BHI, sendo observadas diariamente por 60 dias e a infiltração avaliada pela turbidez do meio. Os dados foram submetidos aos testes ANOVA e Tukey para solubilidade e alteração volumétrica, e Kruskall-Wallis e Dunn para capacidade seladora bacteriana. Na análise de solubilidade, não houve diferença estatística significante entre os grupos. A análise volumétrica demonstrou maior diminuição de volume para o OZE. Também foi observada maior infiltração bacteriana para o OZE. Conclui-se que MTA e CP/ZrO2 apresentam maior capacidade seladora bacteriana, que pode estar relacionada à menor alteração volumétrica.

The present study evaluated different properties of the root end sealers MTA, Portland cement with de 30% zirconium oxide (PC/ZrO2) and zinc oxide and eugenol (ZOE). To analyze the volumetric changes by computed microtomography, bovine teeth were used in which the prepared cavities in dentine were filled according to the materials and then analyzed by Sky Scan 1176. The solubility evaluation was in accordance with ISO 6876 standards, from the difference of the original mass and after 7 days of immersion in distilled water. For analysis of bacterial sealing capacity, extracted human teeth were used. Retrograde cavities were filled according with experimental materials (n=12), besides a positive control (n = 8), no fill, and a negative control (n = 8), with waterproofing to the fullest extent. The samples were subjected to infiltration using Enteroccocus faecalis strains (ATCC 29212) in BHI culture, and observed daily for 60 days and infiltration evaluated by turbidity of the medium. Data were submitted to ANOVA and Tukey tests for solubility and volumetric change, and Kruskall-Wallis and Dunn for bacterial infiltration. In the analysis of solubility, no statistically significant difference between groups. In the analysis of solubility, no statistically significant difference between groups. Volumetric analysis showed greater volumetric reduction for ZOE, as well as greater bacterial infiltration. It was concluded that MTA and CP/ZrO2 have larger bacterial sealing ability, which may be related to lower volumetric changes observed