Wu J, Lei G, Yan M, Yu Y, Yu J, Zhang G
Instrument separation analysis of multi-used ProTaper universal rotary system during root canal therapy
Journal of Endodontics 37(6):758−63
Instrument separation was associated with the number of treated canals
Introduction: The purpose of this study was to identify the influential factors responsible for clinical instrument separation of reused ProTaper Universal rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). Methods: Six thousand one hundred fifty-four root canals in 2,654 teeth were prepared using ProTaper Universal files in endodontic clinics. Separation incidence was determined based on the number of treated teeth or canals. Data were collected including the size of fractured instrument, the length and location of a broken segment within the root canal, and the curvature of canal. The chi-square test and independent samples t test were used to determine the statistical significance. Results: The overall instrument separation incidences were 2.6% according to the number of teeth and 1.1% according to the canal number, respectively. Separation incidences according to the number of teeth or canals were significantly higher (P < .05) in molars than those in premolars or anterior teeth. Because of its largest diameter, F3 file presented the highest separation incidence according to the number of teeth (1.0%) or canals (0.4%); 47.5% instrument separation of mandibular molars and 61.5% instrument separation of maxillary molars happened in the mesiobuccal canals. Moreover, 91.4% fragments were located in the apical third of root canals, and 54.2% instrument separation occurred in severely curved canals. There was a significant difference (P < .05) in the mean fracture length between shaping (2.42 ± 0.73 mm) and finishing files (3.32 ± 0.73 mm). Conclusions: Separation incidence according to the canal number is more reliable than that according to the number of teeth because of the variable canal number in different teeth. The tooth type, rotary file size, canal location, and anatomy were correlated with the instrument separation of reused ProTaper Universal files.
Stewart JT, Lafkowitz S, Appelbaum K, Hartwell G
Distortion and breakage of Liberator, EndoSequence and ProFile systems in severely curved roots of molars
Journal of Endodontics 36(4):729−31
Provides incidence rate for file breakage. However, not clear whether this is after multiple or single-use
Introduction: The aim of this study was to investigate the incidence of endodontic file distortion and breakage when the Liberator (Miltex Inc, York, PA), EndoSequence (Brasseler USA, Savannah, GA), and ProFile (Tulsa Dental Products, Tulsa, OK) systems were used to instrument severely curved root canals of extracted human molars. Methods: Eighty-four roots of extracted human molars with curvatures measuring 40° to 80° were used. The roots were randomly assigned into four groups based on the rotary instrumentation system: group 1, ProFile (.04 taper); group 2, EndoSequence (.04 taper); group 3, Liberator (.04 taper); and group 4, Liberator (.02 taper). Results: File distortion was 19.4%, 10%, 44.4%, and 59.1% for the ProFile, EndoSequence, and Liberator .04 and Liberator .02 groups, respectively. There were statistically significant differences between the ProFile and Liberator .04 groups (p < 0.05), the ProFile and Liberator .02 groups (p < 0.01), the EndoSequence and Liberator .04 groups (p < 0.01), and the EndoSequence and Liberator .02 groups (p < 0.01). Broken files occurred in 2.8% of the ProFile group and 7.4% of the Liberator .04 group. There were no broken files in the EndoSequence or Liberator .02 groups. No statistically significant differences were found among the four groups (p = 0.28) with regard to file breakage. Conclusion: It can be concluded that more file distortions occurred in both Liberator groups than with either the ProFile or the EndoSequence groups to a statistically significant degree.