nitinol and Tooth-Fractures

To investigate the complications associated with the use of nickel titanium rotary instruments (NiTi-RIs) for root canal treatments (RCTs), in Saudi Arabia dental practice, and to explore the influencing factors.. After obtaining an ethical approval, two pilot studies were conducted to formulate the final questionnaire. The sample size was measured taking into consideration 60% expected response rates and confidence level of 99.9%. The questionnaire was emailed to 600 general dentists (GDs) randomly selected from the dental register and all of the endodontists (175). The email's introduction clarified objectives of the study and guaranteed that all of the collected information would remain confidential. A reminder was sent after 10 weeks. The data were collected and analyzed using the chi-squared test at a 0.05 significance level.. With a 51% overall response rate, 71.9% off the respondents used NiTi-RIs. The majority (83.1%) experienced complications while using NiTi-RIs; with the instruments' fracture being significantly the most common complication (52.7%) (p < 0.001). The majority (87.7%) experienced NiTi-RIs' fracture at least once; with more endodontists (94.3%) than GDs (83.3%) (p < 0.001). The greater the number of weekly performed RCTs and participants' experiences, the more NiTi-RIs fractures and the greater the number of fracture incidents (p < 0.001). While 60% of those who performed 1-3 RCTs per week experienced NiTi-RIs fractures, 100% of those who performed more than 12 RCTs per week did so. The highest percentage of those who experienced more than 10 fractured NiTi-RIs (60%) was within the group who performed more than 12 RCTs per week. Although fracture incidents decreased with a smaller number of reuses, there was no significant correlation between the number of fractured instruments and NiTi-RIs discard strategy (p ≥ 0.05).. Fracture incidence was the most common complication while using NiTi-RIs, regardless of the clinicians' experiences and skills. While the single use may reduce NiTi-RIs fractures, to some extent, the greater number of RCTs performed per week was the most influential factor.

Topics: Alloys; Dental Instruments; Dental Pulp Cavity; Equipment Design; Humans; Nickel; Root Canal Preparation; Saudi Arabia; Titanium; Tooth Fractures

The objective of this study was to examine the influence of instrument taper on the fracture resistance of endodontically treated roots under in vitro experimental conditions.. In total, 58 maxillary canines complying with the inclusion criteria were sectioned at approximately 13 mm from the apex. The roots were standardized with respect to the buccolingual-mesiodistal diameter and weight before being randomly distributed into 3 experimental groups (n = 14) and 1 control group (n = 16). The roots in group 1 were instrumented with hand files up to file 40/.02 and groups 2 and 3 with Mtwo (VDW, Munich, Germany) rotary files up to files 40/.04 and 40/.06, respectively. After mechanical preparation, the roots were obturated with gutta-percha and sealer. Roots in group 4 acted as uninstrumented controls. A vertical load was applied to each specimen using a universal testing machine until the roots fractured. Data were statistically analyzed by introducing an innovative approach integrating 1-way analysis of variance, confirmatory factor analysis, and regression analysis.. The mean fracture load was 357.47 ± 110.54 N for the control group, 338.86 ± 105.23 N for group 1, 297.74 ± 77.31 N for group 2, and 280.10 ± 68.51 N for group 3. However, only the difference between group 3 and the control group was statistically significant (P < .05).. After instrumentation using hand files up to file 40/.02 and rotary files up to files 40/.04 and 40/.06, only the last appeared to change the fracture resistance of endodontically treated roots.

Topics: Alloys; Dental Stress Analysis; Endodontics; Humans; Materials Testing; Root Canal Filling Materials; Root Canal Obturation; Root Canal Preparation; Tooth Fractures

The aim of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Tulsa, OK), ProTaper Gold (PTG; Dentsply Tulsa Dental Specialties), Self-Adjusting File (SAF; ReDent Nova, Ra'anana, Israel), and XP-endo Shaper (XP; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments using micro-computed tomographic (CT) analysis.. Forty extracted human mandibular premolars having single-canal and straight root were randomly assigned to 4 experimental groups (n = 10) according to the different nickel-titanium systems used for root canal preparation: PTU, PTG, SAF, and XP. In the SAF and XP groups, the canals were first prepared with a K-file until #25 at the working length, and then the SAF or XP files were used. The specimens were scanned using high-resolution micro-computed tomographic imaging before and after root canal preparation. Afterward, preoperative and postoperative cross-sectional images of the teeth were screened to identify the presence of dentinal defects. For each group, the number of microcracks was determined as a percentage rate. The McNemar test was used to determine significant differences before and after instrumentation. The level of significance was set at P ≤ .05.. The PTU system significantly increased the percentage rate of microcracks compared with preoperative specimens (P < .05). No new dentinal microcracks were observed in the PTG, SAF, or XP groups.. Root canal preparations with the PTG, SAF, and XP systems did not induce the formation of new dentinal microcracks on straight root canals of mandibular premolars.

Topics: Alloys; Dentin; Humans; Radiography, Dental; Root Canal Preparation; Tooth Fractures; X-Ray Microtomography

Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments.. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images.. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files.. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

Topics: Alloys; Boron; Dental Alloys; Dental Instruments; Equipment Failure; Glass; Humans; Materials Testing; Root Canal Preparation; Surface Properties; Titanium; Tooth Fractures; Trace Elements; Zirconium