Microcomputed tomography analysis of curved root canal preparation when coronal flaring and glide path files used with heat-treated nickel titanium rotary files.

The objective was to evaluate the effect of glide path and coronal flaring on the dentin volume removal and percentage of touched walls in curved canals using two heat-treated rotary files. The mesiobuccal canal of forty-eight, randomly selected, extracted mandibular molars was divided into two groups of 24 each, according to the type of instrument used (RACE EVO and EdgeSequel rotary files). Each group was further divided into three subgroups; Group (A): Control using one file shaped to 04/30, Group (B) with a glide path (EdgeGlidePath (EGP)), and Group (C): with a glide path and coronal flaring (EGP and EdgeTaper Platinum (ETP) SX file respectively). The root canals were then instrumented using the assigned instruments. The assessment was carried out using micro-CT. The comparison of the mean values of the tested groups about dentin volume removal and percentage of untouched walls did not reach statistical significance (p<0.05). Glide path and coronal flaring had an insignificant effect on the dentin volume removal and percentage of untouched walls in curved canals.

Evaluation of cyclic fatigue and bending test for different Nickle-Titanium files.

AIM: To compare cyclic fatigue resistance and bending for three different nickel-titanium (NiTi) rotary files. MATERIALS AND METHODS: A sample of 90 NiTi instruments size (25.06) was divided into three groups with 30 files in each: Race Evo files (FKG Dentaire, Switzerland); Tia Tornado Blue files (TiaDent Inc., Texas- USA); One Curve files (Micro-Mega, France). Then each group was subdivided into two groups with 15 files in each; a bending test was performed for one group, and a dynamic cyclic fatigue test at body temperature was performed for the other group. Files fractured by cyclic fatigue were randomly picked from all tested groups for Scanning Electron Microscopy (SEM) (Jeol, Tokyo, Japan). In addition, the test included measuring the broken part of the files tested using (Electronic Micrometre Calliper with LCD Screen, Inch and Millimetre Conversion, Adoric- Taiwan). Data were statistically analyzed using a one-way ANOVA with Tukey-HSD post hoc test. RESULTS: It was found that maximum load [gf] was less (meaning more flexible) in the group of Tia Tornado Blue with a statistically significant difference in comparison with Race Evo and One Curve. The number of cycles to fracture (NCF) in the Race Evo group was significantly higher than the groups of One Curve and Tia Tornado Blue. CONCLUSIONS: Within the limitation of the study, it could be concluded that Race Evo files were more resistant to cyclic fatigue fracture and Tia Tornado Blue files were more flexible compared to the other tested files.

Comparison between the analgesic effectiveness and patients' preference for virtual reality vs. topical anesthesia gel during the administration of local anesthesia in adult dental patients: a randomized clinical study.

This study aimed to compare the analgesic effectiveness of virtual reality vs. topical anesthesia gel during the administration of local anesthesia (injections to numb the gums) in adult dental patients; as well as to determine which approach is preferred by the patients. Twenty-one adult patients received dental anesthetic injections bilaterally for their maxillary premolars area. We predicted that VR would be more effective than a topical anesthetic gel at reducing pain during injections into the gums. Using a within subject design, each patient received two injections during a single dental visit. Pain was measured after each injection. One side was of the mouth was injected under the influence of the topical anesthesia (TA) 20% benzocaine. The other side of the mouth was injected when the patient was in virtual reality (VR) watching an animated movie using an Oculus Quest® helmet to distract them during the other injection, treatment order randomized. Immediately after each injection, the patients were directed to rate their pain experience using the Wong-Baker Faces Pain-rating Scale (W-BFPS), and to choose which delivery system they preferred. Heart rates were recorded prior to and after the injections using a finger pulse oximeter. Participants reported the predicted pattern of a lower W-PFPS score (less pain intensity) during needle injection while in VR than the injection with topical anesthesia gel, however, the difference was not statistically significant. A statistically significant majority of the participants (p = 0.021) preferred VR to TA. No statistically significant difference heart rate during VR vs. TA was found. Although dental patients reported less pain during VR distraction vs. topical gel anesthetic, the difference was not significant. A statistically significant majority of patients preferred virtual reality over topical anesthesia during their future injections. However, no significant difference in heart rate was found.

A Digital Microscopic Inspection of Dentinal Defects after Using Endodontic Retreatment Files.

AIM: The study aimed at evaluating the incidence of dentinal defects after root canal retreatment with ProTaper Universal retreatment (PTUR) and XP-endo Shaper and Finisher R (XP). MATERIALS AND METHODS: Sixty extracted single-rooted human premolars were selected and divided into 4 groups of 15 teeth each. In the negative control group, the teeth were left unprepared. In the positive control group, the teeth were prepared with ProTaper Next and obturated with no further retreatment. In the PTUR and XP groups, the teeth were prepared and obturated followed by removal of the filling material at body temperature using PTUR and XP instruments, respectively. The roots were then sectioned at 3, 6, and 9 mm from the apex and observed under a digital microscope to detect defects. RESULTS: PTUR group showed significantly higher (p value <0.05) incidence of defects than the other groups. Comparison of no defects versus defects between groups in different areas of root canals demonstrated significant difference among the groups in the apical and cervical regions. CONCLUSION: Within the limitations of the present study, PTUR files created significantly more dentinal defects than XP files, with most of those defects at the cervical and apical areas of the root canals.

Effect of Glide Path and Coronal Flaring on the Centering Ability and Transportation of Root Canals: Micro-CT In Vitro Study.

AIM: To compare the effect of glide path and coronal flaring on the centering ability and transportation in curved canals prepared by different NiTi instruments using micro-CT. MATERIALS AND METHODS: The mesiobuccal canal of 48 extracted mandibular molars was selected and divided into two groups of 24 each according to the type of instrument used, either Race Evo or EdgeSequel. Each group was further divided into three subgroups: Group I: without glide path and coronal flaring (control); Group II: with glide path and without coronal flaring; Group III: with glide path and coronal flaring. Following access opening and working length determination, coronal flaring and glide path were done in the required groups. The canals were then prepared according to the assigned instruments and assessed using micro-CT at 3, 5, and 7 mm of the root canal. Data of pre- and postoperative measurements were statistically analyzed using SPSS. RESULTS: The mean value of centering ability was 0.39 (SD 0.36) while the mean value of transportation ability was 0.002 (SD 0.153). Transportation and centering ability did not vary significantly among the tested groups of rotary instruments. Comparison of centering and transportation among root canal instrumentation groups at 3, 5, and 7 mm showed no statistical significance (p >0.05). CONCLUSION: No significant difference was found among the tested groups regarding transportation and centering ability. CLINICAL SIGNIFICANCE: This study provided data on the effect of glide path and coronal flaring on the centering ability and transportation on curved canals prepared by Race Evo and EdgeSequel. Coronal flaring and glide path did not affect the centering ability and transportation.

Influence of short-term cooling on the performance of superelastic and thermally-treated rotary NiTi files tested in dynamic cyclic fatigue model.

AIM: The purpose of the present study was to investigate the effects of various short-term cooling durations on the performance of both superelastic and thermally treated nickel titanium (NiTi) files, tested in a dynamic cyclic fatigue model. METHODOLOGY: Superelastic RaCe (FKG, La Chaux-de-Fonds, Switzerland) and thermally treated RaCe EVO (FKG, La Chaux-de-Fonds, Switzerland) files of the same size and taper (25, 0.06) (n = 45 each) were tested using a dynamic cyclic fatigue model, where the number of cycles to failure (Nf) was measured at simulated body temperature. In each group, the samples were tested as received, after 5 seconds of cooling treatment, and after 15 seconds of cooling treatment (n = 15 each). Fractured file surfaces were investigated via scanning electron microscopy. Statistical analysis was performed using a one-way ANOVA with Scheffe's post hoc test at a significance level of 0.05. RESULTS: Significant differences in the Nf between the tested groups were found (p < 0.05) at each testing condition, where RaCe Evo files showed overall improved cyclic fatigue resistance. Only the RaCe groups at 5 second cooling showed significantly higher Nf than the control subgroup (p < 0.05). RaCe EVO group, showed no significant difference between the 3 subgroups (p > 0.05). Scanning Electron Microscope (SEM) images revealed typical features of cyclic fatigue behavior in both groups. CONCLUSIONS: Short-term cooling application for 5 seconds on superelastic NiTi files showed an enhanced cyclic fatigue resistance.

Resistance to Cyclic Fatigue of Nickel-Titanium Files Immersed in Sodium Hypochlorite at Body Temperature.

MATERIALS AND METHODS: Forty-five files from each brand were randomly assigned to three groups (n = 15) and subjected to the following: no immersion (control), 1-minute immersion, and 5-minute immersion in 2.5% NaOCl at 37°C. CF for all the files was tested within a well-lubricated stainless-steel artificial canal in a water bath at 37°C simulating body temperature. The procedure was video recorded, and the number of cycles to fracture (NCF) was calculated by multiplying the time taken to fracture, with the number of rotations per second. The data were analyzed for normality, and thereafter, one-way ANOVA with multiple Bonferroni was used as the post hoc test. RESULTS: The resistance to CF of OC files was significantly higher than PTG files in all groups. In groups immersed in NaOCl for one minute, OC files showed significant drop in the CF resistance; PTG files showed a drop as well but not significantly. Both files demonstrated a significant drop in resistance to CF after immersion in NaOCl for five minutes compared to the control group. CONCLUSION: OC files were significantly more resistant to CF compared to PTG in all groups. Immersion in 2.5% NaOCl for 5 minutes significantly reduced the resistance to CF for all the files.