Effect of Low-level Laser Therapy on Postoperative Pain after Root Canal Retreatment: A Preliminary Placebo-controlled, Triple-blind, Randomized Clinical Trial.

INTRODUCTION: Low-level laser therapy (LLLT) is a practical, nonpharmacologic technique for reducing pain. This study evaluated the effect of LLLT on postoperative pain after root canal retreatment (RCR). METHODS: This study enrolled patients (N = 36) who required root canal retreatment (RCR) on mandibular molar teeth, presented with periapical lesions with periapical index scores of 2 or 3, and had a pain visual analog scale (VAS) <50 and a percussion pain VAS <50. The participants were divided into 2 groups: (1) patients scheduled for RCR followed by LLLT (n = 18) and (2) patients scheduled for RCR followed by a mock LLLT (placebo) (n = 18). Postoperative pain was assessed using the VAS. Data were collected and statistically analyzed with the chi-square test, the independent sample t test, and the Mann-Whitney U test (P = .05). RESULTS: On the first 4 days, postoperative pain significantly reduced in the LLLT group compared with the placebo group (P < .05). However, no statistically significant differences in postoperative pain were found between the 2 groups after 5 and 7 days (P > .05). The number of patients who needed analgesics was lower in the LLLT group than in the placebo group (P < .05). No patient reported pain during LLLT application. CONCLUSIONS: LLLT may reduce postoperative pain after RCR of mandibular molars.

Effect of the Simultaneous Working Length Control during Root Canal Preparation on Postoperative Pain.

AIM: The aim of this study was to evaluate the effect of simultaneous length control during root canal preparation on postoperative pain compared with separate working length determination and root canal preparation. The design was a parallel-group, randomized, controlled trial with 2 arms. METHODS: Forty-four molar teeth were randomly divided into 2 groups (n = 22), a control group (separate length determination and root canal preparation) and a simultaneous length control during root canal preparation group. The following variables were recorded: age; gender; tooth number; preoperative pain on the visual analog scale; pain level on days 1, 3, 5, and 7; and analgesic intake after the procedure and initial/final percussion pain. The data were analyzed with the χ2 test, independent samples t test, and Mann-Whitney U test. RESULTS: The simultaneous length control during root canal preparation group resulted in lower postoperative pain levels on day 1 than did the control group (P < .05). Despite 2 patients' intake of postoperative analgesics in the control group, no patient needed to use postoperative analgesics in the simultaneous length control during root canal preparation group (P > .05). CONCLUSIONS: Simultaneous length control during root canal preparation as a non-pharmacologic strategy for reducing postoperative pain is a beneficial technique for preventing postoperative pain.

The effect of various kinematics on postoperative pain after instrumentation: a prospective, randomized clinical study.

OBJECTIVE:: To evaluate various kinematic movements on postoperative pain using a Reciproc system. MATERIAL AND METHODS:: Fifty-six molar teeth were divided into four groups according to kinematics as follows: continuous rotation, 360° CCW - 30° CW, 270° CCW - 30° CW, and 150° CCW - 30° CW. Preoperative and postoperative pain levels using visual analogue scale (VAS), percussion pain, and analgesic intake were recorded for each subject. Postoperative pain levels at 1, 3, 5, and 7 d were evaluated. Data were analyzed statistically using the Kruskal-Walis, Mann-Whitney-U, one-way analysis of variance, and chi-square tests (p=0.05). RESULTS:: Continuous rotation resulted in more pain at Day 1 when compared with the reciprocating groups (360° CCW - 30° CW and 270° CCW - 30° C) (p<0.05). CONCLUSIONS:: Continuous rotation resulted in more postoperative pain at Day 1 than in reciprocating groups, and thereafter no significant pain was found among the groups.

Fracture Resistance of Endodontically Retreated Roots After Retreatment Using Self-Adjusting File, Passive Ultrasonic Irrigation, Photon-Induced Photoacoustic Streaming, or Laser.

OBJECTIVE: Additional cleaning techniques and devices are required to remove maximum amount of residual filling material, which might limit disinfection of root canal system during retreatment. This study aimed to compare fracture resistance of roots when self-adjusting file (SAF), photon-induced photoacoustic streaming (PIPS), passive ultrasonic irrigation (PUI), erbium-doped yttrium aluminum garnet (Er:YAG), or neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers are applied following the use of retreatment files in endodontics. MATERIALS AND METHODS: A total of 117 human mandibular canine teeth of similar dimensions were selected and divided into nine groups (n = 13). Aside from control, instrumented, and only-prepared groups, 91 teeth were remaining, of which 13 were assigned to the only-filling group and final 78 to retreatment, thus R-Endo file, R-Endo+SAF, R-Endo+PUI, R-Endo+Er:YAG laser, R-Endo+Nd:YAG laser, and R-Endo+PIPS. RESULTS: The fracture strengths of the retreatment groups were lower than control, instrumented, and only-filling groups (p < 0.05). There was no difference between the R-Endo group and additional retreatment procedure groups (p > 0.05). CONCLUSIONS: Further cleaning methods using SAF, PIPS, Er:YAG laser, Nd:YAG laser, or PUI did not decrease the fracture resistance when compared with the R-Endo group.

Cyclic fatigue analysis of Reciproc R25® instruments with different kinematics.

This study aimed to compare the cyclic fatigue resistance of Reciproc® instruments when used with different kinematics (150° counterclockwise (CCW)-30° clockwise (CW), 270° CCW-30° CW, 360° CCW-30° CW and continuous rotation). Various kinematics were tested in steel canals with a 3 mm radius and a 60° angle of curvature as follows (n = 20): 150° CCW-30° CW, 270° CCW-30° CW, 360° CCW-30° CW and 360° CCW (rotary motion). Reciproc R25® instruments were used until fracture occurred. The time to fracture was recorded in seconds. The data were statistically analysed using a one-way analysis of variance and Tukey's post-hoc tests (P = .05). The cyclic fatigue resistance of Reciproc R25® instruments used with various kinematics in decreasing order was as follows: 150° CCW-30° CW > 270° CCW-30° CW = 360° CCW-30° CW > 360° CCW rotary motion. The 150° CCW-30° CW reciprocating motion had the best performance in time to fracture. All reciprocating motions (150° CCW-30° CW, 270° CCW-30° CW and 360° CCW-30° CW) resulted in a longer mean duration to failure compared with the 360° CCW rotary motion.

Fracture resistance of endodontically treated roots with oval canals restored with oval and circular posts.

INTRODUCTION: The aim of the present study was to evaluate the effects of post space preparations with circular and oval post drills and the placement of oval and circular posts on the fracture strength of roots with oval canals. METHODS: Seventy mandibular premolars with oval root canals were decoronated. Fourteen teeth were used as a control group (group 1), and the root canals of the remaining teeth were prepared up to size #30. The root canals were filled, and the samples were randomly divided into 4 experimental groups as follows: post space preparation with circular-shaped drills (group 2), post space preparation with oval-shaped drills (group 3), circular post placement (group 4), and oval post placement (group 5). A fracture strength test was performed on each specimen, and the data were statistically evaluated using 1-way analysis of variance and Tukey post hoc tests. RESULTS: The fracture strengths of the circular posts-placed group were higher than those of the oval post-placed group (P < .001). The post space preparation using oval-shaped drills significantly decreased the fracture strength of the roots compared with the control group (P < .001). CONCLUSIONS: Within the limitations of the present study, oval posts did not provide a higher fracture resistance to endodontically treated roots with oval canals compared with circular posts. Therefore, clinicians should be aware that oval posts are similar to circular posts in terms of enhancing the fracture resistance of roots with oval canals.

Effect of ProTaper Universal, Endoflare, Revo-S, HyFlex coronal flaring instruments, and Gates Glidden drills on crack formation.

INTRODUCTION: The aim of the present study was to evaluate crack formation after flaring root canals with Gates Glidden drills and ProTaper Universal (SX; Dentsply Maillefer, Ballaigues, Switzerland), Endoflare (MicroMega, Besançon, France), Revo-S (MicroMega), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) flaring instruments. METHODS: One-hundred eight mandibular molars were selected. Eighteen teeth were left unprepared to serve as negative controls; the experimental groups consisted of the mesiobuccal and mesiolingual root canals of the remaining 90 teeth, which were instrumented with the following coronal flaring instruments: Gates Glidden drills and ProTaper Universal SX, Endoflare, Revo-S SC1, and HyFlex 25.08 instruments. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the cementoenamel junction. The sections were inspected under a stereomicroscope, and any crack formations were recorded. The data were analyzed using the chi-square test (P = .05). RESULTS: The Gates Glidden drills resulted in a higher rate of crack formation than that noted in the control group (P < .05). Flaring of the root canals using the ProTaper Universal, Endoflare, Revo-S, and HyFlex instruments resulted in crack formation similar to that of the control group (P > .05). CONCLUSIONS: The use of the Gates Glidden drills resulted in the formation of the most cracks. However, the results for the ProTaper Universal, Endoflare, Revo-S, and HyFlex flaring instruments were similar to those of the control group in terms of crack formation.