A laboratory study of the scouting ability of two reciprocating glide path instruments in mesial root canals of extracted mandibular molars.

AIM: To evaluate in a laboratory setting the performance of two reciprocating glide path systems, WaveOne Gold Glider (WO) and R-Pilot (RP), to create a glide path in mesial root canals of mandibular molars and to assess the torsional resistance of instruments after performing the glide path. METHODOLOGY: A total of 60 mesial root canals of extracted human mandibular molars were divided into two groups (n = 30) according to the glide path system to be used. The data from the volume of each canal, acquired by microcomputed tomography (micro-CT), were validated statistically for the anatomical pairing of the groups. Preparation time, frequency in gaining apical patency, plastic deformation rate of instruments, and canal transportation and centring ability were recorded and compared statistically. The torsional fatigue of the instruments after use was also evaluated. Data were analysed using Fisher's exact test and Mann-Whitney U-test with a 5% significance level. RESULTS: No significant differences were found between groups regarding the time required to perform the glide path, the frequency distributions of the canals classified as patent and the instruments with plastic deformation after use (P > 0.05). No significant differences were found between groups regarding the degree of canal transportation and centring ability at the cervical, middle and apical thirds (P > 0.05). The RP groups had significantly greater maximum torsional strength values compared with the WO groups (P < 0.05). The used WO group had greater angular deflection to fracture when compared to the new WO group (P < 0.05). A significant difference was also found in the percentage of loss of angular deflection in a comparison of the WO group with the RP group (P < 0.05). CONCLUSIONS: The WO and RP instruments performed the same in terms of preparation time, plastic deformation, gaining apical patency, degree of canal transportation and centring ability. The RP instruments had greater torsional strength, less angular deflection and lower percentage of loss in angular deflection than the WO. The used WO group had the greatest angular deflection values.

Validity and reliability of the Child Perceptions Questionnaire 11-14 for Colombian school children.

PURPOSE: To evaluate the validity and reliability of the Child Perceptions Questionnaire 11-14 (CPQ11-14) for children attending public educational institutions in Floridablanca (Colombia). METHODS: An evaluation study of diagnostic technology was conducted. The questionnaire was completed by 500 students aged 11-14 years who were selected by simple random sampling. The test-retest reproducibility was evaluated in 36 students chosen at random from one of the schools; the questionnaire was completed a second time by these students, with an interval of two weeks between administrations. Internal consistency was estimated using the Cronbach's alpha coefficient, and test-retest reproducibility was determined with the intraclass correlation coefficient (ICC). The Rasch Rating Scale Model was used to perform the validation; the structure of the categories, the quality of the items, the invariance and the one-dimensionality were analyzed; invariance was confirmed using differential item functioning (DIF). Informed consent was obtained from the parents or guardians, and assent was obtained from the minors. RESULTS: The mean age was 12.7 ± 1.1 years, and 210 (42.0%) participants were female. The Cronbach's alpha and ICC values were 0.91 and 0.63, respectively. The 37 items fit the Rasch model, but a uniform DIF was observed for an item that was eliminated. The questionnaire was not one-dimensional, and the proportion of variance explained by the model was poor (26.3%). CONCLUSION: The CPQ11-14 showed unsatisfactory test-retest reproducibility and excellent internal consistency; no unidimensionality was observed, but the items fit the Rasch model.

Effect of larger apical size on the quality of preparation in curved canals using reciprocating instruments with different heat thermal treatments.

AIM: To evaluate the influence of larger apical canal enlargement in curved canals using reciprocating systems subjected to various heat treatments. METHODOLOGY: Ninety mandibular premolars with root curvatures ranging from 20° to 30° were selected and scanned by microcomputed tomography (micro-CT) before and after root canal preparation with reciprocating systems (n = 30): Reciproc Blue (RB size 25, .08 taper and size 40, .06 taper; VDW, Munich, Germany), WaveOne Gold (WOG size 25, .07 taper and size 35, .06 taper; Dentsply Sirona, Ballaigues, Switzerland) and ProDesign R (PDR size 25, .06 taper and size 35, .05 taper; Easy Dental Equipment, Belo Horizonte, Brazil). Canal transportation, untouched areas, and apical and total root canal volumes were measured. Statistical analysis was performed with the nonparametric Kruskal-Wallis and Dunn's tests and a significance level set at 5%. RESULTS: The between-group comparison revealed no significant difference in untouched areas, canal transportation, and apical root canal volume among the groups (P > 0.05). However, WOG size 35, .06 taper was associated with a significant increase in the percentage of total canal volume in comparison to the PDR size 35, .05 taper (P < 0.05). The within-group comparison revealed a significant decrease in untouched areas, increase in apical and total root canal volume for all groups when using a larger instrument (P < 0.05). There was no significant difference in transportation among the groups and when a larger apical preparation was created (P > 0.05). CONCLUSIONS: Larger apical enlargement of curved canals was associated with a decrease in untouched areas, an increase in root canal volume and maintenance of canal trajectory. In addition, all systems were safe and provided similar root canal shapes.

The ability of three nickel-titanium mechanized systems to negotiate and shape MB2 canals in extracted maxillary first molars: a micro-computed tomographic study.

AIM: To evaluate the influence of three engine-driven NiTi file systems manufactured from different NiTi alloys for the preparation of second mesiobuccal (MB2) canals in extracted maxillary first molars using a micro-computed tomographic (micro-CT) scanner. METHODOLOGY: Thirty maxillary molars with two canals in the mesiobuccal root were selected and randomly divided into three groups (n = 10): Reciproc [REC; size 25, .08 taper; VDW, Munich, Germany], ProDesign R [PDR; size 25, .06 taper; Easy, Belo Horizonte, Brazil] and Mtwo [MO; size 25, .06 taper; VDW, Munich, Germany]. Before and after root canal preparation of the MB2 canal, the teeth were scanned using a micro-CT to evaluate canal transportation, centring ability, dentine thickness and volume change. The working time to achieve working length was also evaluated. All parameters were compared statistically using the Kruskal-Wallis and Dunn test for multiple comparisons, with a significance level of 5%. RESULTS: There was no significant difference amongst the groups regarding canal transportation and centring ability (P > 0.05). However, the PDR size 25, .06 taper group had significantly lower canal volume and volume of dentine removal compared with a MO size 25, .06 taper and REC size 25, .08 taper (P < 0.05). A root perforation was detected in MO size 25, .06 taper and REC size 25, .08 taper groups, respectively. Regarding the working time, the PDR size 25, .06 taper required a significantly longer time to achieve working length than MO size 25, .06 taper and REC size 25, .08 taper (P < 0.05). CONCLUSIONS: All NiTi systems had similar canal transportation, centring ability and increase in apical volume after preparation of MB2 canals. However, the PDR size 25, .06 taper had less volume of dentine removal, absence of root canal perforation and required a longer time to accomplish the root canal preparation.

The effect of mixing method on tricalcium silicate-based cement.

AIM: To evaluate the effect of three methods of mixing on the physical and chemical properties of tricalcium silicate-based cements. METHODOLOGY: The materials evaluated were MTA Angelus and Portland cement with 20% zirconium oxide (PC-20-Zr). The cements were mixed using a 3 : 1 powder-to-liquid ratio. The mixing methods were manual (m), trituration (tr) and ultrasonic (us) activation. The materials were characterized by means of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy. Flowability was analysed according to ANSI/ADA 57/2012. Initial and final setting times were assessed following ASTM C266/08. Volume change was evaluated using a micro-CT volumetric method. Solubility was analysed according to ADA 57/2012. pH and calcium ion release were measured after 3, 24, 72 and 168 h. Statistical analysis was performed using two-way analysis of variance. The level of significance was set at P = 0.05. RESULTS: The SEM analysis revealed that ultrasonic activation was associated with a homogeneous distribution of particles. Flowability, volume change and initial setting time were not influenced by the mixing method (P > 0.05). Solubility was influenced by the mixing method (P < 0.05). For pH, at 168 h, significant differences were found between MTA-m and PC-20-Zr-m (P < 0.05). For calcium ion release, PC-20-Zr-tr had higher values than MTA-m at 3 h, and MTA-tr had higher values than PC-20-Zr-m at 168 h (P < 0.05). CONCLUSIONS: The ultrasonic and trituration methods led to higher calcium ion release and pH compared with manual mixing for all cements, whilst the ultrasonic method produced smaller particles for the PC-20-Zr cement. Flow, setting times and volume change were not influenced by the mixing method used; however, it did have an impact on solubility.

The safety and effectiveness of stepwise and low-dose administration of follicle stimulating hormone in WHO group II anovulatory infertile women: evidence from a large multicenter study in Spain.

PURPOSE: Our goal was to investigate the safety, effectiveness, and feasibility for the practicing physician of stepwise and low-dose administration of FSH in WHO group II anovulatory infertile women. METHODS: Infertile female patients (n = 234) suffering from WHO group II anovulation, and who failed to became pregnant with clomiphene citrate, were included in a multicenter, prospective, clinical study of treatment with a protocol of chronic low-dose and small incremental rises with urinary purified or highly purified FSH. Follicular development was monitored with ultrasonographic scans. RESULTS: The 234 patients received a total of 534 cycles of treatment, for a mean number of 2.3 treated cycles per patient. hCG was withheld in 65 (12.2%) cyles because of no response and in 28 (5.2%) cycles because of hyperresponse. Of the remaining 441 cycles, 419 (95%) were ovulatory, and in 198 (47.3%) of these cycles a single dominant follicle developed. There were 93 pregnancies (39.7% per patient), for a cycle fecundity rate of 17.4%. Cumulative conception rate after two treated cycles was 33.5%. There were 14 (15%) pairs of twins and 10 (10.8%) spontaneous miscarriages. The prevalence of complications was low with no cases of severe OHSS. Basal LH/FSH ratio was significantly higher in the pregnant group of patients than in nonpregnant women. CONCLUSIONS: Stepwise and chronic low-dose administration of FSH is a safe and effective method for treatment of WHO group II anovulatory infertility, mainly in those patients having high LH/FSH ratios.

Cell volume-sensitive Na+-ATPase activity in rat kidney cortex cell membranes.

A ouabain-insensitive, K+-independent, sodium pump, has been demonstrated in guinea-pig and rat kidney proximal tubular cells. This pump is thought to be distinct from the ouabain-sensitive Na+/K+ pump. We present evidence here indicating the modulation of the biochemical expression of the Na+ pump, i.e. the ouabain-insensitive Na+-ATPase, by the cell volume in rat kidney proximal tubular cells. Thus, basolateral plasma membranes from swollen cells show a ouabain-insensitive Na+-ATPase activity 10-times higher than that in membranes from control cells. If the swollen cells recover their volume, the activity decreases ten times to control values. The ouabain-sensitive Na+/K+-ATPase is not affected by changes in the cell volume.