Carlos Eduardo da Silveira Bueno

In Vitro Evaluation of the Effectiveness of ProTaper Universal Rotary Retreatment System for Gutta-Percha Removal with or without a Solvent

INTRODUCTION Effective removal of gutta-percha in endodontic retreatment is a significant factor to ensure a favorable outcome from failed procedures. The purpose of this study was to evaluate the efficacy of a nickel-titanium rotary instrument system with or without a solvent versus stainless steel hand files for gutta-percha removal. METHODS Forty extracted human maxillary anterior teeth were prepared and filled. They were divided into 4 groups: Gates-Glidden and K-files, Gates-Glidden and K-files with chloroform, ProTaper Universal rotary retreatment system, and ProTaper Universal rotary retreatment system with chloroform. The operating time was recorded. The teeth were longitudinally sectioned and photographed. The images were analyzed and the filling remnants were quantified by using the IMAGE TOOL software. RESULTS With Kruskall-Wallis test, statistical analysis showed that there was no significant difference between the techniques in regard to the amount of the endodontic filling remnants (P < .05); however, the ProTaper Universal rotary retreatment system was faster than the hand files (P < .05). CONCLUSIONS All of the techniques proved helpful for the removal of endodontic filling material, and they were similar in material remaining after retreatment, but the ProTaper Universal rotary retreatment system without chloroform was faster.

Efficacy of 2 reciprocating systems compared with a rotary retreatment system for gutta-percha removal.

INTRODUCTION The maximum removal of root canal filling material is essential for successful endodontic retreatment. The purpose of this study was to assess the efficacy of 2 reciprocating systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) compared with a nickel-titanium (NiTi) rotary system (ProTaper Universal Retreatment [Dentsply Maillefer]) in the removal of root canal filling material. METHODS Sixty root canals of extracted human maxillary incisors were prepared using the NiTi ProTaper rotary system with the complementary use of a #40 K-type file and then obturated. The specimens were divided into 3 groups (n = 20) according to the system used for filling removal: group 1: instrument R25 of the Reciproc system, group 2: primary instrument of the WaveOne system, and group 3: NiTi rotary instruments of the ProTaper Universal Retreatment system. The teeth were cleaved longitudinally and photographed under a dental operating microscope with 5 × magnification. Images were transferred to a computer, and residual filling material was quantified using Image Tool software (University of Texas Health Science Center, San Antonio, TX). Results were compared using 1-way analysis of variance (P < .05). RESULTS All teeth examined had filling remnants within the canal. No statistically significant difference (P > .05) in residual filling material was observed among the groups, with 4.30% in group 1, 2.98% in group 2, and 3.14% in group 3. CONCLUSIONS The Reciproc and WaveOne reciprocating systems were as effective as the ProTaper Universal retreatment system for gutta-percha and sealer removal.

Comparison among Manual Instruments and PathFile and Mtwo Rotary Instruments to Create a Glide Path in the Root Canal Preparation of Curved Canals

INTRODUCTION Nickel-titanium rotary instruments reduce procedural errors and the time required to finish root canal preparation. The goal of this study was to evaluate the occurrences of apical transportation and canal aberrations produced with different instruments used to create a glide path in the preparation of curved root canals, namely manual K-files (Dentsply Maillefer, Ballaigues, Switzerland) and PathFile (Dentsply Maillefer) and Mtwo (Sweden and Martina, Padua, Italy) nickel-titanium rotary files. METHODS The mesial canals of 45 mandibular first and second molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 3 groups with 15 canals each, and canal preparation was performed by an endodontist using #10-15-20 K-type stainless steel manual files (group M), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 Mtwo rotary instruments (group MT). The double digital radiograph technique was used, pre- and postinstrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. The initial and final images of the central axis of the canals were compared by superimposition through computerized analysis and with the aid of magnification. The specimens were analyzed by 3 evaluators, whose calibration was checked using the Kendall agreement test. RESULTS No apical transportation or aberration in root canal morphology occurred in any of the teeth; therefore, no statistical analysis was conducted. CONCLUSIONS Neither the manual instruments nor the PathFile or Mtwo rotary instruments used to create a glide path had any influence on the occurrence of apical transportation or produced any canal aberration.

Effectiveness of rotary and hand files in gutta-percha and sealer removal using chloroform or chlorhexidine gel.

The purpose of this study was to assess in vitro the efficacy of nickel-titanium K3 rotary files and hand files for removal of gutta-percha and sealer from obturated root canals using either chloroform or chlorhexidine as solvents. Sixty extracted single-rooted bovine teeth with straight, large canals were prepared, obtured and randomly assigned to 3 groups (n=20). The teeth were stored at 37 degrees C for 1 month and then the gutta-percha and sealer were removed using different techniques, as follows. Group I: size 3 Gates-Glidden drills plus size 30 hand K-files and Hedström files and chloroform; Group II: K3 NiTi rotary files and chloroform; and Group III: K3 NiTi rotary files and 2% chlorhexidine gel. Radiographs were taken and scanned and the images were digitized. The total area of the canal and the area with remaining obturation material were measured in millimeters using a computed image analysis system (ImageLab). Data were analyzed statistically by one-way ANOVA and Tukey test at 5% significance level. The groups differed statistically (p<0.05) with respect to the average percentage of remaining gutta-percha and sealer, presenting the following sequence of effectiveness (from most to least effective): Group I (15.48%), Group II (28.42%) and Group III (35.96%). The findings of this study showed that, despite the technique used for removal of filling material, none of the retreated canals were completely free of gutta-percha and sealer remnants. The use of stainless steel hand files resulted in a lesser amount of filling debris than the use of nickel-titanium rotary instruments.

Efficacy of reciprocating instruments for removing filling material in curved canals obturated with a single-cone technique: a micro-computed tomographic analysis.

INTRODUCTION The aim of this study was to evaluate the efficacy of nickel-titanium reciprocating instrument techniques and passive ultrasonic irrigation (PUI) for retreatment in curved canals and obturated with correspondent single cones. METHODS Twenty molars were selected with mesial-buccal canals with curvatures between 20° and 40°, and they were instrumented with a Reciproc R25 instrument (VDW, Munich, Germany) in a reciprocating motion and obturated with single cones and AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). The teeth were divided into 2 groups (n = 10) according to the instrument used for the removal of filling material: group 1: Reciproc R25 instrument and group 2: WaveOne Primary instrument (Dentsply Maillefer). The analysis of the remnant filling material was made through micro-computed tomographic imaging after the use of reciprocating instruments and again after the use of PUI with xylene. The effective time of retreatment was registered. RESULTS The filling material of the root canal was efficiently removed (P < .05) for both groups. The percentage of removal of filling materials was 93% for the Reciproc group and 92% for the WaveOne group. There were no statistical significant differences (P > .05) between the groups in relation to the removal of filling material ability and the time needed for the procedure. The effective time for the removal of filling material was 78.7 seconds and 89.5 seconds for the Reciproc and WaveOne groups, respectively. CONCLUSIONS It was concluded that both instruments efficiently but not completely removed the filling material from inside the root canals. The use of xylene with PUI increased the removal of filling material a little, but it was not statically significant.

Success Rates for Removing or Bypassing Fractured Instruments: A Prospective Clinical Study

INTRODUCTION The objective of this study was to evaluate the success rates of standardized techniques for removing or bypassing fractured instruments from root canals and determine whether visualization of the fractured instrument with the aid of an operating microscope has any impact on the success rates. METHODS In this prospective study, attempts were made to visualize 112 fractured instruments under a dental operating microscope after creating a straight-line access to the fragment. By using ultrasonic tips alone or associated with bypassing, the Ruddle technique was attempted to remove the 68 visible instruments. Bypassing was performed for the 44 nonvisible fragments. The χ(2) test was performed to assess whether any significant difference occurred between the success rates observed for the visible and nonvisible fractured instrument groups. RESULTS The overall success rate (removal and bypassing) was 70.5% (n = 79). In the visible fragment group, the success rate was 85.3% (n = 58), and in the nonvisible fragment group it was 47.7% (n = 21). Success rates were significantly higher when the fragment was visible (P = .0009). CONCLUSIONS The standardized techniques used in this study for removing or bypassing fractured instruments were effective, and approximately 2 times greater success rate was obtained when the fragment was visible inside the root canal compared with when it was nonvisible.

Comparison of the Incidence of Postoperative Pain after Using 2 Reciprocating Systems and a Continuous Rotary System: A Prospective Randomized Clinical Trial.

INTRODUCTION The objective of the present study was to clinically compare the incidence of postoperative pain and the intake of analgesic medication (frequency and quantity) after endodontic treatment of posterior teeth using 2 reciprocating systems and a continuous rotary system. METHODS In a prospective randomized clinical study, 210 patients with vital teeth indicated for conventional endodontic treatment were treated by 5 specialists according to a pre-established protocol. The teeth were randomly assigned to 1 of 3 groups (n = 70) according to the instrumentation system used: ProTaper Next (Dentsply Tulsa Dental Specialties, Johnson City, TN), WaveOne (Dentsply Tulsa Dental Specialties), or Reciproc (VDW, Munich, Germany). Treatments were performed in a single visit. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 hours if they experienced pain. Participants were asked to rate the intensity of the postoperative pain on a visual analog scale according to 4 classes (no pain, mild pain, moderate pain, and severe pain) after 24 hours, 48 hours, 72 hours, and 7 days. Patients were also asked to record the number of prescribed analgesic medication tablets taken at these time points. RESULTS No statistically significant difference was found among the 3 groups in relation to postoperative pain or analgesic medication intake at the 4 time points assessed (P > .05, Kruskal-Wallis test). CONCLUSIONS The reciprocating systems and the continuous rotary system were found to be equivalent in regard to the incidence of postoperative pain and intake of analgesic medication at the time points assessed.

Retreatment efficacy of gutta-percha removal using a clinical microscope and ultrasonic instruments: Part I—an ex vivo study

OBJECTIVE This study compared the efficacy of gutta-percha/sealer removal from endodontically treated extracted human teeth with and without the aid of a clinical operating microscope/ultrasonic instruments. STUDY DESIGN Forty human extracted maxillary central incisors were prepared using a modified crown-down technique and filled with lateral compactation. Teeth were divided into 2 groups: group I, re-treated using a conventional technique with burs and solvent; and group II, re-treated using a conventional technique with burs and solvent plus clinical operating microscope/ultrasonic tips. Teeth were split longitudinally and photographed, and coded photos transfered to a computer workstation. Total canal space and remaining gutta-percha/sealer were quantified, and ratio of remaining filling material and root canal periphery was computed. Mean percentage of remaining gutta-percha/sealer in each group was compared using analysis of variance. RESULTS The average percentage of remaining gutta-percha/sealer was 25.21% in group I and 9.31% in group II, showing a statistically significant difference (P = .05). CONCLUSION The use of the dental operating microscope and ultrasonic tips removed the filling material from root canal walls better, but all examined teeth, in both groups, had remaining filling material on canal walls.

Study of the bismuth oxide concentration required to provide Portland cement with adequate radiopacity for endodontic use.

OBJECTIVE The purpose of this study was to determine the ideal concentration of bismuth oxide in white Portland cement to provide it with sufficient radiopacity for use as an endodontic material (ADA specification #57). STUDY DESIGN 2-mm thick standardized test specimens of white MTA and of white Portland cement, as controls, and of white Portland cement with the experimental addition of 5%, 10%, 15%, 20%, 25% or 30% of bismuth oxide were radiographed and compared with various thicknesses of pure aluminum, using optic density to determine the observed grayscale levels of radiopacity in a scale ranging from 0 to 255. The data was submitted to ANOVA (p<0.05) and the Ryan-Einot-Gabriel-Welch and Quiot test (REGWQ) for multiple comparison of the means. RESULTS White Portland cement with 0%, 5%, 10%, 15%, 20%, 25% and 30% of bismuth oxide presented mean readings of 63.3, 95.7, 110.7, 142.7, 151.3, 161.0 and 180.0 respectively. MTA presented a mean reading of 157.3. The readings of MTA and white Portland cement with 15% bismuth oxide did not differ significantly from the reading observed for a thickness of 4 mm of aluminum (145.3), which is considered ideal for a test specimen by ADA specification #57 (2 mm above the thickness of the test specimen). CONCLUSION White MTA and white Portland cement with 15% bismuth oxide presented the radiopacity required for an endodontic cement.

Evaluation of the Efficacy of TRUShape and Reciproc File Systems in the Removal of Root Filling Material: An Ex Vivo Micro-Computed Tomographic Study.

INTRODUCTION The purpose of this study was to evaluate the efficacy of TRUShape (Dentsply Tulsa Dental Specialties, Tulsa, OK) compared with the Reciproc file (VDW, Munich, Germany) in the removal of filling material from oval canals filled with 2 different sealers and differences in the working time. METHODS Sixty-four mandibular canines with oval canals were prepared and divided into 4 groups (n = 16). Half of the specimens were filled with gutta-percha and pulp canal sealer (PCS), and the remainders were filled with gutta-percha and bioceramic sealer (BCS). The specimens were retreated using either the Reciproc or TRUShape files. A micro-computed tomographic scanner was used to assess filling material removal, and the time taken for removal was also recorded. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS The mean volume of the remaining filling material was similar when comparing both files (P ≥ .05). However, in the groups filled with BCS, the percentage of remaining filling material was higher than in the groups filled with PCS (P < .05). The reciprocating file allowed for faster filling removal than the TRUShape files (P < .05). Retreatment was faster in the groups that were filled with PCS compared with those filled with BCS (P < .05). CONCLUSIONS There was no difference regarding the percentage of remaining filling material when comparing both files system; however, Reciproc was faster than TRUShape. BCS groups exhibited significantly more remaining filling material in the canals and required more time for retreatment. Remaining filling material was observed in all samples regardless of the technique or sealer used.