Clinical microscopic analysis of protaper retreatment system efficacy considering root canal thirds using three endodontic sealers

To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty-five palatal root canals of first molars were filled with gutta-percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10x), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal-Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third. Microsc. Res. Tech. 75:12331236, 2012. (C) 2012 Wiley Periodicals, Inc.

The use of ultrasound for cleaning the surface of stainless steel and nickel-titanium endodontic instruments

Aim the aim of this study was to evaluate the efficacy of ultrasound in cleaning the surface of stainless steel and Ni-Ti endodontic instruments.Methodology Twenty nickel-titanium instruments (10 Quantec files and 10 Nitiflex) and 20 stainless steel K-files (10 Maillefer-Dentsply and 10 Moyco Union Broach) were removed from their original packages and evaluated using a scanning electron microscope. Scores were given for the presence of residues on the surface or the instruments. The instruments were then cleaned in an ultrasonic bath containing only distilled water or detergent solution for 15 min, and re-evaluated, using scanning electron microscopy.Results Before cleaning, a greater amount of metallic debris was observed on the nickel-titanium Quantec instruments (P < 0.05), when compared to those made of stainless steel. Statistical analysis showed that the use of ultrasound was effective for cleaning the instruments, regardless of the irrigating solution or the instruments type (P < 0.05).Conclusions the use of ultrasound proved to be an efficient method for the removal of metallic particles from the surface of stainless steel and Ni-Ti endodontic instruments.

Effectiveness of ProTaper retreatment system associated with organic solvents in the removal of root canal filling material

Aim: To evaluate the effectiveness of ProTaper universal retreatment system in the removal of root canal filling material with thermomechanical compaction, in comparison to manualmechanical technique, associated with orange oil or eucalyptol. Materials and methods: Forty extracted lower incisors were filled with thermomechanical compaction technique. After 3 years, the root canal filling was removed by: G1 - manualmechanical technique with orange oil; G2 - manual-mechanical technique with eucalyptol; G3 - ProTaper universal retreatment system with orange oil and G4 - ProTaper universal retreatment system with eucalyptol. In sequence, all root canals were instrumented to F5 instrument. The teeth were longitudinally grooved, images of buccal half were obtained in stereomicroscope and covered area by root canal filling material was measured using image tool software, in cervical, middle and apical radicular thirds. The results were subjected ANOVA and Tukey test (p = 0.05). Results: In all thirds, the manual-mechanical technique showed lower presence of root canal filling material on root canal dentin in comparison to ProTaper retreatment universal system, regardless of organic solvent used (p < 0.05). There is no difference between organic solvents in removal root canal filling material (p > 0.05). Conclusion: The ProTaper universal retreatment system showed lower effectiveness in removal root canal filling material than manual-mechanical technique, regardless of organic solvents (orange oil or eucalyptol oil) used. Clinical significance: Recently rotary instruments have been proposed to removal of root canal filling material. However, there are no studies evaluating its effectiveness in removal root canal filling material in association with orange oil or eucalyptol oil.

Wear resistance of nickel-titanium endodontic files after surface treatment

Objectives The purpose of this work was to submit the Nitinol files to plasma immersion ion implantation (PIII) and evaluate the effects of the surface treatment. Materials and Methods Wear resistance was determined in vitro by using an equipment for the application of horizontal movements on previously prepared notched plates made of resin. Vickers microhardness was measured in plates and files, before and after surface treatment and the surface chemical composition of the instruments was determined by X-rays photoelectron spectroscopy. Results The hardness values found for the treated Nitinol files were significantly lower than the hardness values measured before the implantation process. The comparison of commercially available instruments shows that the wear resistance of the stainless steel file is higher than the resistance of the Nitinol. Conclusions The results found led to the conclusion that the surface treatment significantly increased the Nitinol files wear resistance.

The Ability of Different Nickel-Titanium Rotary Instruments To Induce Dentinal Damage During Canal Preparation

The purpose of this study was to compare the incidence of dentinal defects (fractures and craze lines) after canal preparation with different nickel-titanium rotary files. Two hundred sixty mandibular premolars were selected. Forty teeth were left unprepared (n = 40). The other teeth were prepared either with manual Flexofiles (n = 20) or with different rotary files systems: ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland), ProFile (Dentsply-Maillefer), SystemGT (Dentsply-Maillefer), or S-ApeX (FKG Dentaire, La Chaux-de-Fonds, Switzerland) (n = 50 each). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. There was a significant difference in the appearance of defects between the groups (p < 0.05). No defects were found in the unprepared roots and those prepared with hand files and S-ApeX. ProTaper, ProFile, and GT preparations resulted in dentinal defects in 16%, 8%, and 4% of teeth, respectively. Some endodontic preparation methods might damage the root and induce dentinal defects. (J Endod 2009;35:236-238)

Micro-CT assessment of two different endodontic preparation systems

The aim of this study was to compare two endodontic preparation systems using micro-CT analysis. Twenty-four one-rooted mandibular premolars were selected and randomly assigned to two groups. The samples (n = 12) of Group 1 were prepared using the ProTaper Universal rotary system, while Group 2 (n = 12) was prepared using the EndoEZE AET system complemented by manual apical preparation with K-type hand files up to #30. A 2.5% sodium hypochlorite solution was used in both groups for irrigating. Both groups were scanned by highresolution microcomputed tomography before and after preparation (SkyScan 1172, SkyScan, Kontich, Belgium). The root canal volume and surface area was measured before and after preparation, and the differences were calculated and analyzed for statistically significant differences using ANOVA complemented by the Tukey test (p < 0.05). The results showed no statistically significant differences between the mean volumes of dentin removal by the two systems. However, the EndoEZE AET system presented a significantly greater mean surface area compared to the ProTaper system (p < 0.05). The EndoEZE AET system enabled preparation of a greater root canal surface area when compared to the ProTaper Universal system. There seemed to be no difference in dentin volume loss between the two systems used.

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: Eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts-FRC and cast post and core-CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom # 2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45 degrees, 37 degrees C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45 degrees device with 1 mm/min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario.

Setting time and thermal expansion of two endodontic cements

The purpose of this study was to evaluate the setting time and the thermal expansion coefficient of 2 endodontic cements, MTA-Angelus and a novel cement called CER. The setting time was determined in accordance to ANSI/ADA specifications no. 57. Three samples of 10 mm diameter and 2 mm thickness were prepared for each cement. The thermal expansion measurements were performed by strain gauge technique. Four samples of each cement were prepared using silicone rings of 5 mm diameter and 2 mm thickness. The data were analyzed statistically using the Student t test. The setting time obtained for the MTA-Angelus and CER cements was 15 (SD 1) min and 7 (SD 1) min, respectively. The linear coefficient of thermal expansion was 8.86 (SD 0.28) mu strain/degrees C for MTA-Angelus and 11.76 (SD 1.20) mu strain/degrees C for CER. The statistical analysis showed significant difference (P < .05) in the setting time and linear coefficient of thermal expansion between the 2 cements. The CER cement has a coefficient of expansion similar to dentin, which could contribute to a decrease of microleakage degree.

Alcohol screening instruments in elderly male: a population-based survey in metropolitan São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genotoxicity of antimicrobial endodontic compounds by single cell gel (comet) assay in Chinese hamster ovary (CHO) cells

Objective. In the current study, the potential DNA damage associated with exposure to a number of antimicrobial endodontic compounds was assessed by the single cell gel (comet) assay in vitro.Study design. Chinese hamster ovary (CHO) cells were exposed to formocresol, paramonochlorophenol, calcium hydroxide, or chlorhexidine at final concentration ranging from 0.01% to 1%.Results. Formocresol, paramonochlorophenol, and calcium hydroxide, as well as chlorhexidine in all concentrations tested did not contribute to the DNA damage.Conclusion. These findings are clinically relevant since they represent an important contribution to the correct evaluation of the potential health risk associated with exposure to dental agents.

Use of 4 Immediately Loaded Zygomatic Fixtures for Retreatment of Atrophic Edentulous Maxilla After Complications of Maxillary Reconstruction

This article reports the 20-month clinical outcome of the use of 4 zygomatic implants with immediate occlusal loading and reverse planning for the retreatment of atrophic edentulous maxilla after failed rehabilitation with autogenous bone graft reconstruction and maxillary implants. The intraoral clinical examination revealed mispositioned and loosened implants underneath a maxillary complete denture. The panoramic radiograph showed 6 maxillary implants. One implant was displaced into the right maxillary sinus, and the implant anchored in the region of tooth 21 was fractured. The other implants presented peri-implant bone loss. The implants anchored in the regions of teeth 21 to 23 and 11 to 13 were first removed. After 2 months, the reverse planning started with placement of 4 zygomatic fixtures, removal of the implants migrated into the sinus cavity and anchored in the region of tooth 17, and installation of a fixed denture. After 20 months of follow-up, no painful symptoms, peri-implant inflammation or infection, implant instability, or bone resorption was observed. The outcomes of this case confirm that the zygoma can offer a predictable anchorage and support function for a fixed denture in severely resorbed maxillae.

Evaluation of subcutaneous and alveolar implantation surgical sites in the study of the biological properties of root-end filling endodontic materials

Objective: The aim of this study was to compare two methodologies used in the evaluation of tissue response to root-end filling materials in rats. Material and Methods: Forty rats were divided into 4 groups: in Groups I and II (control groups), empty polyethylene tubes were implanted in the extraction site and in the subcutaneous tissue, respectively; in Groups III and IV, polyethylene tubes filled with ProRoot MTA were implanted in the extraction site and in the subcutaneous tissue, respectively. The animals were killed 7 and 30 days after tube implantation, and the hemi-maxillas and the capsular subcutaneous tissue, both with the tubes, were removed. Specimens were processed and evaluated histomorphologicaly under light microscopy. The scores obtained were analyzed statistically by the Kruskal-Wallis test (p<0.05). Results: There were no statistically significant differences between the implantation methods (p=0.78033, p=0.72039). It was observed that the 30-day groups presented a more mature healing process due to smaller number of inflammatory cells. Conclusions: The present study showed no differences in tissue responses as far as the implantation site and the studied period were concerned. Alveolar socket implantation methodology represents an interesting method in the study of the biological properties of root-end filling endodontic materials due to the opportunity to evaluate bone tissue response.