Quality of root canal treatment performed by undergraduate students using nickel-titanium reciprocating versus hand instruments.

PURPOSE: To compare the technical quality of root canal treatment (RCT) depending on the incidence of procedural errors performed by undergraduate students using nickel-titanium reciprocating and conventional hand instrumentation techniques, and to assess the impact of case difficulty and localization of the teeth (maxillary or mandibular molars). METHODS: Dental records and periapical radiographs of molars that were treated with either hand or reciprocating WaveOne (WO) instruments were evaluated retrospectively. The technical quality of RCTs, the incidence of ledge formation, perforation, instrument fracture, overinstrumentation, underfilling, overfilling, inadequate root canal filling, and the effects of case difficulty and tooth localization were compared using the chi-square test with a significance of 5% (α = 0.05). RESULTS: While overinstrumentation was more frequent in the WO group (247 teeth), the incidence of inadequate root canal fillings was higher in the hand instrumentation group (245 teeth) (p < 0.01). No significant difference was observed in the incidence of other procedural errors (p > 0.05). The number of teeth with acceptable technical quality in preparation and obturation was 172 (69.6%) in the WO group, whereas it was 142 (58%) in the hand instrumentation group, presenting a significant difference between the instrumentation techniques (p < 0.01). Higher technical quality rates were observed with WO instrumentation in the high difficulty category and in maxillary teeth (p < 0.01). CONCLUSION: Higher technical quality in preparation and obturation can be achieved with WO reciprocating instruments and file-matched greater tapered gutta-percha cones. No significant difference was observed between the groups in the incidence of procedural errors except for overinstrumentation and insufficient root canal filling. WO instrumentation and obturation with file-matched greater tapered gutta-percha cones provided better technical quality in the high difficulty category and in maxillary teeth.

Outcome of single- versus two-visit root canal retreatment in teeth with periapical lesions: A randomized clinical trial.

AIM: The aim of the study was to evaluate the clinical and radiographic outcome of single-visit root canal retreatment and compare the results with conventional two-visit root canal retreatment as control group. METHODOLOGY: One hundred root canal-treated, single-rooted asymptomatic teeth with periapical lesion were retreated by one operator. Fifty of the teeth were randomly assigned to the single-visit group and the others were treated in two visits. In both groups, root canal filling material was removed, and re-instrumentation of the root canal was performed using step-back technique with hand files using 2.5% NaOCl and 5% EDTA as irrigants. In the single-visit group, 5 ml 2% chlorhexidine (CHX) were applied as the final irrigation and in the two-visit group, calcium hydroxide paste was placed into the root canal as an interappointment dressing. All root canal obturations were performed with lateral compaction. All patients were followed up for 24 months. The success was determined depending on both healed and healing cases. The chi-square or Fisher's exact test was used to analyse the differences between the groups for success rates and the factors affecting the outcome. RESULTS: The recall rate was 89 (89%). At 24 months, 39 teeth (88.6%) were considered as healed, three teeth (6.8%) as healing, and two teeth (4.5%) were identified as failed in the single-visit group, while in the two-visit group 39 teeth (86.7%) had healed, two teeth (4.4%) were scored as healing, and four teeth (8.9%) as failed. There was no statistically significant difference in the success rates between the two groups (p > .05). Size of the lesion and the preoperative length of root canal filling had a statistically significant impact on the outcome (p < .05). CONCLUSION: No statistically significant difference was observed in terms of healing in 24-month follow-up of retreatments completed in single visit or two visits in asymptomatic teeth with periapical lesions. The size of the periapical lesion and initial apical level of root canal filling have affected the outcome of root canal retreatment.

A prospective cohort study evaluating the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions.

AIM: To evaluate the impact of various predictors on the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions after a minimum of 2 years. METHODOLOGY: One hundred and twenty previously root canal treated symptomatic mandibular first molars with periapical lesions which were diagnosed as symptomatic apical periodontitis or acute apical abscess with localized intraoral swelling were included. Root canal retreatment was performed by an experienced endodontist using a standardized treatment protocol. The teeth were followed up clinically and radiographically and the radiographic outcome was assessed using a modified periapical index scale (PAI). The cumulative success proportion and the influence of predictors on the outcome of the root canal retreatment were analysed using Kaplan-Meier analyses and log-rank tests, and the hazard ratios for the predictors were also investigated using Univariate Cox Proportional Hazard regression analysis at a significance level of 5%. RESULTS: Of the 120 teeth, 103 teeth were re-examined with an 85% recall rate. The cumulative success rate was 88% in which 64% were healed and 24% were healing, and failure rate was recorded as 12%. None of the preoperative predictors, including age, gender, soft tissue tenderness, intraoral swelling, size of the lesion, PAI score, apical level and density of root canal filling before root canal retreatment, nor intraoperative predictors, such as active exudate drainage, density of root canal filling after root canal retreatment and restoration type had an influence on the outcome of root canal retreatment (p > .05). The only factor that significantly reduced the success rate of root canal retreatment was the apical level of the root canal filling; when it was more than 2 mm short of the radiographic apex in teeth where apical patency was not established, the success was significantly lower (p = .023). CONCLUSIONS: Root canal retreatment in symptomatic mandibular first molars with periapical lesions resulted in a success rate of 88%. None of the predictors had a significant influence on the outcome, except for the apical level of the root canal filling after root canal retreatment with short root fillings being associated with significantly more post-treatment endodontic disease.

The influence of different NiTi instrumentation techniques on postoperative pain after single-visit root canal treatment.

This study aimed to evaluate the effect of multi-file rotary (Protaper Universal) and reciprocating single-file (Reciproc Blue) root canal preparation techniques on the occurrence of postoperative pain in asymptomatic mandibular molar teeth with large periapical lesions in single-visit root canal treatment (RCT). A hundred and twenty teeth were randomly assigned to two groups: Protaper Universal (PTU) or Reciproc Blue (RB) instruments. Postoperative pain at 6, 12, 24, 48, 72 h and 7 days after obturation was measured. Mann-Whitney U-test was performed to compare the pain scores between the groups and to assess the relation of pain with patients' age and gender. Spearman's rank correlation was utilized to correlate the pain intensity and analgesic intake at different time points. There was no significant difference between the instrumentation techniques regarding postoperative pain at any time points evaluated (P > 0.05). There was a correlation between analgesic intake and intensity of pain (P < 0.05). No statistically significant difference was found among the groups assessed in the study in terms of analgesic intake (P > 0.05).

Impact of root canal curvature and instrument type on the amount of extruded debris during retreatment.

OBJECTIVES: The aim of the current study was to assess whether the amount of extruded debris differs for straight and severely curved root canals during retreatment using H-files, R-Endo, Reciproc and ProTaper Universal Retreatment (PTU-R) files. Additionally, the area of residual filling material was evaluated. MATERIALS AND METHODS: Severely curved (n = 104) and straight (n = 104) root canals of maxillary molar teeth were prepared with WaveOne Primary file and obturated with gutta-percha and AH Plus sealer. Root canal filling materials were removed with one of the preparation techniques: group 1: H-file; group 2: R-Endo; group 3: Reciproc; group 4: PTU-R (n = 26). The amount of extruded material and the area of the residual filling material was measured. The data were analyzed with 2-way analysis of variance (ANOVA) and 1-way ANOVA at the 0.05 significance level. RESULTS: Except for Reciproc group (p > 0.05), PTU-R, R-Endo, and H-file systems extruded significantly more debris in severely curved canals (p < 0.05). Each file system caused more residual filling material in severely curved canals than in straight ones (p < 0.05). CONCLUSIONS: All instruments used in this study caused apical debris extrusion. Root canal curvature had an effect on extruded debris, except for Reciproc system. Clinicians should be aware that the difficult morphology of the severely curved root canals is a factor increasing the amount of extruded debris during the retreatment procedure.

Cyclic fatigue resistance and energy dispersive X-ray spectroscopy analysis of novel heat-treated nickel-titanium instruments at body temperature.

The aim of this study was to evaluate the cyclic fatigue resistance of Dia-X, WaveOne Gold and One Curve files in a water bath at intracanal temperature (35°C). Thirty-nine instruments Dia-X, WaveOne Gold, and One Curve systems (n = 13) were tested in an artificial canal with a curvature angle of 60° and a radius of 3 mm. A water bath setup at a temperature of 35°C was used to simulate the intracanal temperature and time to fracture (TTF) as seconds was recorded. The mean data were analyzed statistically using one-way ANOVA, and post hoc Tukey test (p = .05). The fractured surface of the instruments was examined with scanning electron microscopy (SEM) and chemical composition of the instruments were investigated with energy dispersive X-ray spectroscopy (EDS). Statistically significant differences were detected in TTF values of all the systems as follows: One Curve > WaveOne Gold > Dia-X (p < .05). One Curve instruments demonstrated the highest TTF values in all the tested instruments. The EDS microanalysis revealed similar NiTi composition of on the surface of One Curve, WaveOne Gold, and Dia-X instruments. The novel manufacturing process, including C-wire heat treatment and the variable cross-section of the One Curve files, could be the main factors affecting the fatigue life of the instruments.

Cyclic Fatigue Resistance of Multiused Reciproc Blue Instruments during Retreatment Procedure.

INTRODUCTION: Root canal retreatment procedure may reduce the mechanical resistance of nickel-titanium instruments and increase the frequency of instrument fracture. The aim of the present study was to evaluate the effect of multiuse of Reciproc Blue R25 instruments on cyclic fatigue resistance during retreatment procedure in mandibular molar teeth. METHODS: Forty-eight Reciproc Blue R25 files were included in the study. In control group, 12 new Reciproc Blue R25 instruments were subjected to cyclic fatigue test by using a stainless steel artificial canal with a 90° angle and 3-mm radius of curvatures. In experimental groups, Reciproc Blue R25 files (n = 12) were used to remove the root canal filling (RCF) material of 1, 2, and 3 molar teeth, respectively. Then cyclic fatigue tests of these 36 instruments were performed. The number of cycles to fracture (NCF) and the length of the fractured fragment were calculated for each instrument. Working time for retreatment procedures was determined in seconds with a digital chronometer. The data were analyzed by using one-way analysis of variance followed by post hoc Tukey test and mixed-effect analysis (P = .05). RESULTS: No significant difference was found between NCF values of new and first time used files (P > .05), but NCF values of new and first time used files were significantly higher than those of second and third time used files (P < .05). The second and third time used files revealed no difference (P > .05). As the number of uses increased, the average time for retreatment procedure statistically extended (P < .05). CONCLUSIONS: Reciproc Blue R25 instrument can be used to remove RCF material of 2 molar teeth. However, because of its decreased NCF values, multiple use over 2 molars may not be suggested.

Cyclic Fatigue Resistance of Novel Glide Path Instruments with Different Alloy Properties and Kinematics.

INTRODUCTION: The aim of the present study was to evaluate the cyclic fatigue resistance of the WaveOne Gold Glider (Dentsply Maillefer, Ballaigues, Switzerland), R-Pilot (VDW, Munich, Germany), and ProGlider (Dentsply Maillefer) glide path instruments. METHODS: Ten instruments from each glide path system were included in the study. A stainless steel artificial canal with a 90° angle and a 3-mm radius of curvature was used for the testing process. The working lengths of the instruments were fixed at 19 mm, and the instruments were operated using an endodontic motor (X-Smart Plus, Dentsply Maillefer) at recommended setting for each. A digital camera (Sony HDR-XR260; Sony Corporation, Minato, Tokyo, Japan) was positioned on the top of the cyclic fatigue test device, and the time to fracture was recorded in seconds by means of the video camera. For each instrument, the number of cycles to failure was calculated, and the length of the fractured fragment was measured. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey test. RESULTS: Statistically significant differences in the number of cycles to failure values were observed across the tested groups; the ranking of the instruments was as follows: WaveOne Gold Glider > R Pilot > ProGlider (P < .05). There was no significant difference in the mean length of the fractured fragment of the instruments (P > .05). CONCLUSIONS: Within the limitations of the present study, it can be concluded that improved alloy properties and reciprocating motion could enhance the cyclic fatigue resistance of glide path instruments.

Effect of novel restoration techniques on the fracture resistance of teeth treated endodontically: An in vitro study.

The aim was to evaluate the effects of fiber-reinforced composite restorations and a bulk-fill resin composite on the fracture strength of mandibular premolars treated endodontically. Standard mesio-occluso-distal (MOD) cavities were prepared in 48 mandibular premolars. Following root canal treatment, teeth were assigned to four groups: Group 1, nano-hybrid resin composite; Group 2, polyethylene woven fiber plus nano-hybrid resin composite; Group 3, short fiber-reinforced resin composite plus nano-hybrid resin composite; and Group 4, bulk-fill resin composite plus nano-hybrid resin composite. Then, the teeth were subjected to the fracture toughness test. The data were analyzed statistically using one-way ANOVA, followed by Tukey's post-hoc test. The fiber-reinforced groups had better results than the nano-hybrid and bulk-fill composites (p<0.05), while the bulk-fill and nano-hybrid composite restorations gave similar results (p>0.05). Fiber-reinforcement improved the fracture strength of teeth with large MOD cavities treated endodontically. Bulk-fill composites can be used reliably as well as nano-hybrid composites.