Effect of movement kinematics on the cyclic fatigue resistance of nickel-titanium instruments.

AIM: To compare the cyclic fatigue resistance of new generation OneShape and WaveOne instruments when used with different kinematics. METHODOLOGY: An artificial canal, made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature and a curvature radius of 3 mm, was used for cyclic fatigue test of new generation OneShape and WaveOne instruments. Groups were as follows (n = 20): 150°-30°, 210°-30°, 360°-30° and continuous rotation. The time to fracture was recorded in seconds, and the data were analysed statistically using a two-way anova and LSD tests (P = 0.05). RESULTS: Cyclic fatigue resistance was significantly affected by the movement kinematics (P < 0.001). The cyclic fatigue resistance of the new generation OneShape instruments increased significantly when operated in various reciprocation motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) compared with the continuous rotation mode. New generation OneShape instruments had significantly more resistance to fracture under cyclic loading than WaveOne instruments (P < 0.001). CONCLUSIONS: When using new generation OneShape and WaveOne instruments, all the reciprocating motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) resulted in extended fatigue life when compared with continuous rotation.

Variations in cyclic fatigue resistance among ProTaper Gold, ProTaper Next and ProTaper Universal instruments at different levels.

AIM: To compare the cyclic fatigue resistance of ProTaper Gold (PTG, Dentsply Tulsa Dental Specialities, Tulsa, OK, USA), ProTaper Next (PTN, Dentsply Tulsa Dental Specialities) and ProTaper Universal (PTU, Dentsply Tulsa Dental Specialities) instruments at different levels. METHODOLOGY: A total of 72 files were used to evaluate the cyclic fatigue of PTU (F2), PTN (X2) and PTG (F2) at 5 mm (n = 12) and 8 mm (n = 12) from the tip in 3-mm-radius steel canals with a 60° angle of curvature. The time to fracture was recorded. The Kolmogorov-Smirnov test was used to assess the normality of the samples distribution, and the statistical analysis was performed using the independent sample t-test (P < 0.01). RESULTS: Significant differences were found amongst the instruments 5 mm from the tip (P < 0.01). The PTG files had the highest CF resistance, and the PTN files displayed greater CF resistance than the PTU files. No significant differences were found between the PTG and PTN files 8 mm from the tip (P > 0.01). The PTG and PTN files demonstrated greater CF resistance than the PTU files (P < 0.01). CONCLUSIONS: The PTG instruments were the most resistant 5 and 8 mm from the tip; however, at 8 mm, there was no difference between the PTG and PTN instruments. The PTU files had the lowest CF resistance at all levels.

Evaluation of orange-brown precipitate formed in root canals after irrigation with chlorhexidine and QMix and spectroscopic analysis of precipitates produced by a mixture of chlorhexidine/NaOCl and QMix/NaOCl.

AIMS: (i) To compare chlorhexidine and QMix(TM) in terms of orange-brown precipitate generation in root canals and (ii) to analyse the precipitate produced by mixing chlorhexidine and QMix(™) with NaOCl to determine whether para-chloroaniline was produced. METHODOLOGY: The root canals of 57 single-rooted anterior teeth were prepared using ProTaper Universal rotary instruments up to size F4. Two millilitres of 2.5% NaOCl was used between each instrument change. The specimens were then divided randomly into three groups (n = 19) and irrigated as follows: group 1, 5 mL of distilled water (control group) for 60 s; group 2, 5 mL of 2% chlorhexidine for 60 s; and group 3, 5 mL of QMix for 60 s. The roots were split longitudinally, and one of the halves was photographed using a stereomicroscope. The amount of orange-brown precipitate was evaluated using a four-grade scoring system. The data were analysed statistically using the Kruskal-Wallis and Mann-Whitney U-tests (P = 0.05). To evaluate whether the precipitates included para-chloroaniline, 5 mL of 2% chlorhexidine and 5 mL QMix were separately mixed with 5 mL of 2.5% NaOCl in two flasks. After centrifugation, precipitates were obtained and analysed using (1) H NMR spectra. The data were subjected to statistical analysis using the Kruskal-Wallis and Mann-Whitney tests at a 95% confidence level (P = 0.05). RESULTS: Chlorhexidine had significantly higher scores than QMix(™) in terms of orange-brown precipitate formed in the root canals (P < 0.001). According to the 1H NMR spectra, para-chloroaniline was present in the mixture of chlorhexidine and NaOCl. However, the mixture of QMix(™) and NaOCl did not result in para-chloroaniline formation. CONCLUSION: QMix(™) does not form para-chloroaniline when associated with NaOCl.

Tenosynovial giant cell tumour of the posterior cruciate ligament and its arthroscopic treatment.

Tenosynovial giant cell tumours originate from synovial tissues of the joints, tendon sheaths, mucosal bursas or fibrous tissues adjacent to tendons. Tenosynovial giant cell tumours are rarely intra-articular. We report a giant cell tumour of the tendon sheath arising from the posterior cruciate ligament diagnosed by magnetic resonance imaging and resected arthroscopically in a 54-year-old woman.

Effects of fusion angle on functional results following non-operative treatment for fracture of the neck of the fifth metacarpal.

AIM: To investigate in fractures of the fifth metacarpal neck whether there is any difference in functional results of non-operative treatments with dorsal angulation either below or above 30 degrees. METHODS: After closed reduction, fractures were treated with plaster splints for 5 weeks. Cases were divided into two groups, with dorsal angulation either below (group 1) or above (group 2) 30 degrees, according to oblique radiography, and were evaluated at 6 months. Grip strength, range of passive joint movement and distance from fingertip to distal crease were measured and compared. A scoring system assessed function, and occupational adequacy, patient satisfaction and presence of pain were recorded. RESULTS: Functional outcome was good or very good in both groups and occupational adequacy was not reduced in any case. Full patient satisfaction was achieved except for one person in group 1 and two people in group 2, regarding cosmetic results. There was no statistically significant difference between the two hands in either group except for one man from group 2, who had mild pain during coercive use of the injured hand. CONCLUSIONS: With non-operative treatment of fractures of the neck of the fifth metacarpal, similar results were achieved with dorsal angulation either above or below 30 degrees. A dorsal angulation less than 45 degrees may be treated conservatively.