Multimethod analysis of large- and low-tapered single file reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow

AIM

To compare eight large- and low-tapered heat-treated reciprocating instruments regarding their design, metallurgy, mechanical properties, and irrigation flow through an in silico model.

METHODOLOGY

A total of 472 new 25-mm E-Flex Rex (25/.04 and 25/.06), Excalibur (25/.05), Procodile (25/.06), Reciproc Blue R25 (25/.08v), WaveOne Gold Primary (25/.07v), and Univy Sense (25/.04 and 25/.06) instruments were evaluated regarding their design (stereomicroscopy, scanning electron microscopy, and 3D surface scanning), metallurgy (energy-dispersive X-ray spectroscopy and differential scanning calorimetry), and mechanical performance (cyclic fatigue, torsional resistance, cutting ability, bending and buckling resistance). Computational fluid dynamics assessment was also conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparations. Kruskal-Wallis and one-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%).

RESULTS

Instruments presented variations in blade numbers, helical angles, and tip designs, with all featuring non-active tips, symmetrical blades, and equiatomic nickel-titanium ratios. Cross-sectional designs exhibited an S-shaped geometry, except for WaveOne Gold. Univy 25/.04 and Reciproc Blue displayed the smallest and largest core diameters at D3. Univy 25/.04 and E-Flex Rec 25/.04 demonstrated the longest time to fracture (p < .05). Reciproc Blue and Univy 25/.04 exhibited the highest and lowest torque to fracture, respectively (p < .05). Univy 25/.04 and Reciproc Blue had the highest rotation angles, whilst E-Flex Rec 25/.06 showed the lowest angle (p < .05). The better cutting ability was observed with E-Flex Rec 25/.06, Procodile, Excalibur, and Reciproc Blue (p > .05). Reciproc R25 and E-Flex Rec showed the highest buckling resistance values (p < .05), with WaveOne Gold being the least flexible instrument. The impact of instruments' size and taper on wall shear stress and apical pressure did not follow a distinct pattern, although Univy 25/.04 and E-Flex Rec 25/.06 yielded the highest and lowest values for both parameters, respectively.

CONCLUSIONS

Low-tapered reciprocating instruments exhibit increased flexibility, higher time to fracture, and greater angles of rotation, coupled with reduced maximum bending loads and buckling strength compared to large-tapered instruments. Nevertheless, low-tapered systems also exhibit lower maximum torque to fracture and inferior cutting ability, contributing to a narrower apical canal enlargement that may compromise the penetration of irrigants in that region.

Comparative Analysis of Endodontic ISO Size 06, 08, and 10 Stainless Steel K-Files Used for Glide Path Procedures

Small-sized stainless steel hand files are conventionally employed in root canal treatment procedures for canal scouting and for glide path establishment, owing to their superior flexibility and proficiency in navigating confined spaces. Given the diversity of brands available in the market, there exists potential variability in their physical characteristics, thereby influencing clinical performance. Consequently, this study aims to conduct a comparative analysis of the design, metallurgy, and mechanical characteristics among seven stainless steel hand file brands across ISO sizes 06, 08, and 10. A total of 315 new 25 mm length stainless steel hand files with apical sizes of 0.06, 0.08, and 0.10 from seven distinct brands were included in the study. A meticulous inspection of all instruments was undertaken to identify any structural deformations that might render them ineligible for the study. The design inspection involved the random selection of instruments from each group, which were examined under various microscopes, including a dental operating microscope, optical microscope, and scanning electron microscope. Furthermore, two instruments from each group underwent energy-dispersive X-ray spectroscopy analysis for elemental composition documentation. Mechanical tests were conducted to evaluate the instruments' resistance to lateral deformation (buckling) and their microhardness. Statistical analysis was executed using the nonparametric Mood's median test, with a predetermined significance level of 0.05. Regarding the instruments design, all files exhibited an active blade length ranging from 16 to 17 mm. However, variations were observed in the number of spirals, tip designs, and sizes, with the API K-File notably larger in sizes 0.06 and 0.08 compared to the other instruments. Despite uniform elements composition, differences in geometric features and mechanical properties were evident. Concerning buckling strength, the API K-File demonstrated superior performance across all tested sizes, while the Dentsply ReadySteel, SybronEndo, and Mani K-Files exhibited lower results (p < 0.05). In microhardness assessments, both the API and Oro K-Files displayed the lowest outcomes, with medians of 531 HVN and 532 HVN, respectively, whereas the SybronEndo K-File exhibited the highest microhardness (657 HVN). Despite similar metallurgical composition, the observed distinctions in geometric features and mechanical properties underscore the impact of the manufacturing process on the characteristics of glide path stainless steel endodontic files. These disparities may ultimately influence their clinical performance.

Comparison between digital superimposition and microcomputed tomography methods of fit assessment of removable partial denture frameworks

STATEMENT OF PROBLEM

The fit of removable partial denture frameworks should be assessed to optimize clinical adaptation. Potential discrepancies between framework and supporting structures are typically precisely measured with negative subtracts and high-resolution equipment. The growth of computer-aided engineering technology allows the development of new methods for the direct evaluation of discrepancies. However, how the methods compare is unclear.

PURPOSE

The purpose of this in vitro study was to compare 2 digital methods of fit assessment based on direct digital superimposition and microcomputed tomography indirect analysis.

MATERIAL AND METHODS

Twelve cobalt chromium removable partial denture frameworks were fabricated by conventional lost-wax casting or additive manufacturing techniques. The thickness of the gap between occlusal rests and respective definitive cast rest seats (n=34) was evaluated by using 2 different digital methods. Silicone elastomer impressions of the gaps were obtained, and microcomputed tomography measurements were used as controls for validation purposes. Digitization of the framework, the respective definitive cast, and the combination was followed by digital superimposition and direct measurements with the Geomagic Control X software program. Because normality and homogeneity of variance were not verified (Shapiro-Wilk and Levene tests, P<.05), the data were analyzed with Wilcoxon signed rank and Spearman correlation tests (α=.05).

RESULTS

The thicknesses measured by microcomputed tomography (median=242 μm) and digital superimposition (median=236 μm) did not reveal statistically significant differences (P=.180). A positive correlation (ρ=0.612) was detected between the 2 methods of assessing fit.

CONCLUSIONS

The frameworks presented median gap thicknesses under the limit of clinical acceptability without differences between the proposed methods. The digital superimposition method was determined to be as acceptable as the high-resolution microcomputed tomography method for assessing removable partial denture framework fit.

Accuracy of Silicone Impressions and Stone Models Using Two Laboratory Scanners: A 3D Evaluation

PURPOSE

To evaluate the in vitro accuracy of impressions obtained with two silicone and corresponding stone models using two laboratory scanners.

MATERIALS AND METHODS

A master model with synthetic resin teeth with two single-unit crown preparations was created and scanned using a 12-megapixel scanner. Five conventional impressions of the physical model were prepared with different silicone impression systems (Zhermack and Coltene) using the double-mix technique and poured with gypsum. The impressions and stone models obtained were scanned using two extraoral scanning systems (Identica T500, Medit; S600 ARTI, Zirkonzahn). All best-fit superimpositions of the teeth areas were conducted between the master model and the scans of the impressions and models obtained with the two scanners. A P < .05 level was considered significant.

RESULTS

The Identica T500 Medit scanner showed an accuracy of 102.34 (89.67, 115.01) μm for Coltene silicone and 79.51 (67.82, 91.21) μm for Zhermack silicone, while the S600 ARTI Zirkonzhan scanner presented 110.79 (98.24, 123.33) μm and 91.91 (81.29, 102.54) μm, respectively, with significant differences between scanners for Zhermack silicone (P = .008) and for the corresponding stone models (P = .002). Zhermack silicone presented overall discrepancies lower than Coltene silicone, with statistically significant differences in both scanners analyzed (P < .001; P = .017). However, the discrepancies found were within clinically acceptable values. With the Zirkonzahn scanner, discrepancies found in the Zhermack impressions were lower than in the corresponding stone models (P < .001).

CONCLUSIONS

The direct digitization of silicone impressions with laboratory scanners presented comparable results to conventional techniques with stone models.

Comparative Analysis of Endodontic 0.15 Stainless-Steel K-Files: Exploring Design, Composition, and Mechanical Performance

To establish a glide path, smaller files (up to size 0.15) with tapers of 2% are commonly used as pathfinding files. They pre-shape the root canal space before transitioning to larger taper endodontic instruments, aiming to prevent procedural errors. This study aimed to compare the design, metal wire composition, and mechanical characteristics of seven different ISO size 15 stainless-steel hand files (K-File and C-File+). Ninety-one new stainless-steel ISO 15 K-files were mechanically tested. All files were inspected for deformations before the assessment. Dental operating microscope, scanning electron microscope (SEM), and optical microscope analyses were conducted on four randomly selected instruments from each group, and two instruments per group underwent an energy-dispersive X-ray spectroscopy (EDS) analysis. Buckling mechanical tests were performed using an Instron universal testing machine, and microhardness was assessed using a Vickers hardness tester. The statistical analysis employed the nonparametric Mood's median test, with a significance level set at 0.05. The instrument design analysis unveiled variations in the active blade area length and the number of spirals, while maintaining consistent cross-sections and symmetrical blades. Distinct tip geometries and surface irregularities were observed. While the energy-dispersive X-ray spectroscopy confirmed similar compositions, the buckling strength and microhardness values exhibited variability across for all tested files. Notably, the Dentsply ReadySteel C-File+ recorded the highest buckling value (2.10 N), and the Dentsply ReadySteel K-File exhibited the lowest (1.00 N) (p < 0.05). Moreover, the Dentsply ReadySteel K-File recorded the highest microhardness value (703 HVN), while the SybronEndo Triple-Flex had the lowest (549 HVN) (p < 0.05). While similarities in cross-section design and metal wire composition were noted among the files, variations in the number of spirals and mechanical performance were also observed. Thus, all of these factors should be considered when selecting suitable files for an efficient root canal treatment.

Characterization of four heat-treated reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow patterns

AIM

To compare the design, metallurgy, and mechanical properties of four heat-treated reciprocating instruments coupled with the evaluation of the irrigation flow using an in silico model.

METHODOLOGY

New EdgeOne Fire Primary, Easy-File Flex Regular 25, WaveOne Gold Primary and Reciproc Blue R25 instruments (n = 124) were initially evaluated regarding their design through stereomicroscopy, scanning electron microscopy and 3D surface scanning. In addition, energy-dispersive X-ray spectroscopy was utilized to determine their elemental composition, and differential scanning calorimetry tests to evaluate their phase transformation temperatures. Their mechanical performance was further assessed through torsional and bending tests. Using scans obtained from a real tooth and the instruments, a computational fluid dynamics assessment was conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparation. Mood's median and One-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%).

RESULTS

Reciproc Blue exhibited a superior number of blades (n = 8), whereas EdgeOne Fire had the highest overall volume (4.38 mm3 ) and surface area (32.32 mm2 ). At the 3-mm axial level, EdgeOne Fire displayed the lowest core diameter (0.13 mm), while Reciproc Blue had the highest (0.16 mm). All blades were symmetrical, and the tips of the instruments were non-active but differed from each other. The most irregular surfaces were observed in EdgeOne Fire and Easy-File Flex. All instruments were manufactured from nickel-titanium alloys and exhibited distinct phase transformation temperatures. WaveOne Gold and Reciproc Blue demonstrated the highest maximum torque values (1.87 and 1.62 N cm, respectively), while the lowest was observed on EdgeOne Fire (1.21 N cm) (p < .05). The most flexible (p < .05) were EdgeOne Fire (angle of rotation: 602.6°; maximum bending load: 251.4 g.f) and Reciproc Blue (533.2° and 235.6 g.f). There were no significant differences observed in the irrigation flow among the four domains generated by the tested instruments.

CONCLUSIONS

Despite observing variations in the design, phase transformation temperatures, and in the torsional and bending test outcomes among the four heat-treated reciprocating instruments, no significant differences were found in the irrigation flow pattern among the different groups in the simulated root canal preparations.

The REWRITE Study - REal-WoRld effectIveness of TrifluridinE/tipiracil in Patients with Previously Treated Metastatic Colorectal Cancer

AIMS

In the pivotal RECOURSE trial, trifluridine/tipiracil improved survival outcomes in refractory metastatic colorectal cancer (mCRC), while demonstrating an acceptable toxicity profile. Routine clinical practice evidence is important to support the ongoing value of recently approved medicines. Our objective was to assess the utilisation patterns and real-world effectiveness of trifluridine/tipiracil in previously treated mCRC patients.

MATERIALS AND METHODS

This was a retrospective observational study including consecutive patients who started trifluridine/tipiracil between 1 April 2018 and 30 September 2019 in the medical oncology departments of three major public hospitals in Portugal. The primary outcome measure was overall survival. Associations between overall survival and patient and tumour characteristics were assessed using multivariate Cox regression analyses.

RESULTS

In total, 111 patients were included in the study, with a mean age of 64 years. From these, 45.9% received two prior lines of treatment, 47.8% had three or more previous lines of treatment and 83.6% had Eastern Cooperative Oncology Group (ECOG) performance status 0-1 at baseline. The median duration of trifluridine/tipiracil treatment was 3.7 cycles (95% confidence interval 3.4-4.1). Most patients (80.4%) remained on their planned dose throughout the trifluridine/tipiracil treatment period, fulfilling 100% relative dose intensity. The median overall survival in the total study cohort was 7.9 months (95% confidence interval 6.4-9.8) and the median progression-free survival was 3.4 months (95% confidence interval 3.2-3.9). The median overall survival was significantly higher in patients with a normal serum lactate dehydrogenase (LDH) level (median overall survival 11.2 months for [135, 205] IU/l LDH [95% confidence interval 8.2-NR] and 13.6 months for [205, 251] IU/l LDH [95% confidence interval 8.2-NR]) and in better fitted (ECOG = 0-1) patients (median overall survival 8.0 months; 95% confidence interval 6.7-10.0). The median time to worsening performance status was 6.2 months (95% confidence interval 5.0-8.0). Treatment discontinuation due to adverse events was low (3.1%).

CONCLUSION

Our study confirms the effectiveness of trifluridine/tipiracil in real-life mCRC patients. Overall survival and progression-free survival outcomes are consistent with the efficacy profile reported in the earlier randomised RECOURSE clinical trial. Like other real-world studies, we found no additional safety concerns in the use of trifluridine/tipiracil.

Different Methods for Assessing Tooth Colour-In Vitro Study

Colour assessment using digital methods can yield varying results, and it is important for clinicians to recognize the potential variability intra and inter-device. This study aimed to compare the L*a*b* values of VITA Classical (VC) and VITA Toothguide 3D-MASTER (VM) guides using two methods, SpectroShade (SS) and eLAB. Thirty-four measurements per tab were performed by a single operator across three batches of each guide. Intraclass correlation coefficients (ICC) between batches were calculated. Values <0.5, 0.5-0.75, 0.75-0.9, and >0.90 were classified as poor, moderate, good, and excellent reliability, respectively. Results were reported as mean and standard deviation of the L*a*b* values and respective colour differences (ΔE00) for each tab and method. Statistical analyses were performed with an independent t-test, α = 0.05. ICC values between batches were excellent for all L*a*b*, except for a* component in eLAB. There were statistically significant differences between methods in most L*a*b* values. The intra-device mean ΔE00 was 0.5 ± 0.6 for VC, 0.5 ± 0.8 for VM in SS, 1.1 ± 0.8 for VC, 1.1 ± 0.9 for VM in eLAB. The mean ΔE00 inter-device was 4.9 ± 1.7 for VC, 5.0 ± 1.7 for VM. Both methods demonstrated good internal consistency, with high ICC values and low intra-device colour differences, but exhibited high variability between methods, higher for a* the component.

Hydrogen Peroxide Diffusion through Dental Tissues-In Vitro Study

Whitening products commonly utilize hydrogen peroxide (HP) as an active principle, which can penetrate dental tissues with potential side effects due to its low molecular weight. This study aimed to evaluate the HP diffusion of two in-office whitening products, namely 6% VivaStyle Paint On Plus (VS) and Opalescence Boost 40% (OP), in different tooth types. Additionally, the influence of the area of exposure, dental tissue thickness and pulp chamber volume was assessed. Each group consisted of eighteen intact anterior (A), premolar (PM) and molar (M) human teeth, and a positive pulpal pressure model was employed. The samples were analyzed using spectrophotometry, and results were expressed as the mean and 95% confidence interval. Statistical tests and linear regression models were appropriately applied at α = 5%. The total HP (µg) retrieved was as follows: VS-A, 1.333 [1.214, 1.452]; OP-A, 1.538 [1.457, 1.620]; VS-PM, 1.208 [1.123, 1.291]; OP-PM, 3.628 [3.401, 3.855]; VS-M, 2.560 [2.297, 2.823]; and OP-M, 4.197 [3.997, 4.396], with statistically significant differences in diffusion kinetics between whitening products for PM and M. Several HP concentrations attained a minimum cytotoxicity value of 2.22 µg/mL. The regression model shows that OP exposed the pulp chamber to 1.421 µg of HP more than that of VS. Different whitening products can cause cytotoxic HP concentrations in the pulp chamber, with a higher risk observed in molars.

3D Surface Scanning-A Novel Protocol to Characterize Virtual Nickel-Titanium Endodontic Instruments

The nickel-titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.

Characterization of the file-specific heat-treated ProTaper Ultimate rotary system

AIM

To compare design, metallurgy and mechanical performance of the ProTaper (PT) Ultimate system with instruments of similar dimensions from the ProGlider, PT Gold and PT Universal systems.

METHODOLOGY

New PT Ultimate instruments (n = 248) were compared with instruments of similar dimensions from ProGlider (n = 31), PT Gold (n = 155) and PT Universal (n = 155) systems regarding their number of spirals, helical angle, blade symmetry, tip geometry, surface finishing, nickel/titanium ratio, phase transformation temperatures and mechanical performance. One-way anova and nonparametric Mood's median tests were used for statistical comparison (α = 5%).

RESULTS

All instruments had symmetrical blades without radial lands or flat sides, similar surface finishing and an almost equiatomic nickel/titanium ratio, whilst the number of spirals, helical angles and the tip geometry were different. PT Ultimate instruments showed 3 distinct heat treatments that matched with the colour of their metal wire. Slider and ProGlider instruments had similar R-phase start (Rs) and R-phase finish (Rf) temperatures. SX, F1, F2, F3 and Shaper instruments showed equivalent heat treatments (Rs ~45.6°C and Rf ~28.3°C) that were similar to their PT Gold counterparts (Rs ~47.9°C and Rf ~28.2°C), but completely distinct to the PT Universal ones (Rs ~16.2°C and Rf ~-18.2°C). Amongst the PT Ultimate instruments, the lowest maximum torques were observed in the SX (0.44 N cm), Slider (0.45 N cm) and Shaper (0.60 N cm) instruments, whilst the highest was noted in the FXL (4.90 N cm). PT Ultimate Slider and ProGlider had similar torsional (~0.40 N cm) and bending loads (~145.0 gf) (p = 1.000), whilst the other PT Ultimate instruments showed statistically significantly lower maximum torque, higher angle of rotation and lower bending load (higher flexibility) than their counterparts of the PT Universal and PT Gold systems.

CONCLUSIONS

The PT Ultimate system comprises instruments with 3 distinct heat treatments that showed similar phase transformation temperatures to their heat-treated analogues. PT Ultimate instruments presented lower torsional strength and superior flexibility than their counterparts, whilst maximum torque, angle of rotation and bending loads progressively increased with their sizes.

Bleaching efficacy and quality of life of different bleaching techniques - randomized controlled trial

OBJECTIVES

To evaluate bleaching efficacy and oral health-related quality of life (ORHQoL) of three bleaching systems with similar hydrogen peroxide (HP) concentration for up to 6 months post-treatment.

MATERIALS AND METHODS

A randomized controlled trial was designed with three parallel groups: group A - in-office 6% HP paint-on varnish; group B - at-home 6% HP with adaptable tray; group C - at-home 16% carbamide peroxide with custom tray. At three different stages (baseline, after bleaching, and 6-month follow-up), ORHQoL was evaluated by the OHIP-14 questionnaire and tooth color of the upper canines and central incisors were measured by two shade guides and a spectrophotometer (measuring CIE L*a*b* with respective color/whiteness differences - ΔE00/ΔWID). Results were presented as mean and 95% confidence intervals and statistical tests were performed appropriately, considering a significance level of α = 0.05.

RESULTS

All groups presented significant color differences (P < 0.05) between all stages, with ΔE00/ΔWID surpassing the perceptibility threshold in 98% cases, with group C's results being significantly (P < 0.05) higher when compared to other groups, although with significantly (P < 0.05) higher values of color relapse. Significative ORHQoL improvements (P < 0.05) were detected after bleaching in a global analysis with no differences between techniques.

CONCLUSIONS

All techniques presented bleaching efficacy, color stability, and improvements in ORHQoL up to 6 months post-treatment.

CLINICAL SIGNIFICANCE

Clinicians may consider both at-home and in-office bleaching techniques with 6% HP to attain long-lasting satisfactory clinical results while producing positive changes in ORHQoL.

Multimethod Assessment of the Cyclic Fatigue Strength of ProGlider, Edge Glide Path and R-Pilot Endodontic Instruments

Background: The aim of this study was to comprehensively evaluate the cyclic fatigue strength of ProGlider, Edge Glide Path, and R-Pilot instruments. Methods: Sixty-three instruments were submitted to a multimethod evaluation. Their design was analyzed by stereomicroscopy and scanning electron microscopy, including the number of blades, helical angle means, cross-sectional design, surface finishing, and symmetry. Energy-dispersive X-ray spectroscopy was used determine the nickel/titanium elements ratio, and differential scanning calorimetry determined the instruments’ phase transformation temperatures. The cyclic fatigue tests were conducted in an artificial canal with a 6 mm radius and 86 degrees of curvature. The Mood’s median test and one-way ANOVA were used to determine differences, with the significance level set at 0.05. Results: The ProGlider presented the highest number of blades (n = 21), while R-Pilot had the highest helical angles (26.4°). Differences were noted in the instruments’ cross-sections and surface finishing. The ProGlider and R-Pilot showed some similarities regarding the phase transformation temperatures but differed from the Edge Glide Path. All alloys showed an almost equiatomic nickel/titanium ratio. The R-Pilot instruments showed a significantly higher (p < 0.05) time to fracture than both the other files. Conclusion: Reciprocating R-Pilot instruments showed a higher cyclic fatigue time to fracture than the ProGlider and Edge Glide Path rotary files.

Design, Metallurgical Features, and Mechanical Behaviour of NiTi Endodontic Instruments from Five Different Heat-Treated Rotary Systems

The current study aimed to compare the F1 endodontic instruments from five different heat-treated rotary systems regarding their design, metallurgical properties, and mechanical performance. Five F1 root canal shaping instruments (ProTaper Gold [PTG], Premium Taper Gold, Go-Taper Flex, EdgeTaper Platinum, and Super Files Blue)—plus, a conventional ProTaper Universal (PTU)—which were evaluated regarding their design, nickel/titanium ratio, phase transformation temperatures, microhardness, cyclic fatigue, and torsional and bending strengths. Mood's median test was used for the statistical comparison with a significance set at 5%. The instruments were similar regarding the nickel/titanium ratio and overall design. Go-Taper Flex had the closest transformation temperatures to PTG. PTU and Go-Taper Flex had the highest microhardness (408.3 and 410.5 HVN). The time to fracture of Super Files Blue was three and seven times higher than PTG and PTU, respectively. No difference was observed in the maximum torque to fracture among PTG (1.30 N·cm) and the other systems, except for the Premium Taper Gold (1.05 N·cm) and Go-Taper Flex (1.10 N·cm). Significantly lower bending loads than PTG (269.2 gf) were observed for the EdgeTaper Platinum (158.3 gf) and Premium Taper Gold (103.5 gf) instruments. Super Files Blue outperformed PTG in the cyclic fatigue test, while EdgeTaper Platinum and Premium Taper Gold were more flexible. Premium Taper Gold and Go-Taper Flex showed lower torsional strength.

Hydrogen Peroxide Release Kinetics of Four Tooth Whitening Products-In Vitro Study

Tooth whitening efficacy can be influenced by several factors, of which concentration and application time are two of the most important. This in vitro study aimed to evaluate the initial content and release kinetics of the hydrogen peroxide (HP) content, or the carbamide peroxide (CP) content as converted to its HP equivalent, of four tooth whitening products with different concentrations (6% HP, 16% CP, 10% CP, and 5% CP). Titrations with Cerium Sulphate IV were performed to determine HP concentration. HP release kinetics were evaluated by a spectrophotometric technique. The results were expressed as the mean values and 95% confidence interval of the percentage of hydrogen peroxide content during release kinetics. One sample t-test, one-way ANOVA, Tukey post hoc testing, and Pearson correlation testing were used, as appropriate, with a significance level of α = 0.05. The concentration of titrated HP was higher than that indicated by the manufacturers in all tested products (p < 0.01). At the minimum application times indicated by the manufacturers, all products released at least 85% of HP content; the gel containing 10% CP registered the lowest release at 85.49 (81.52–89.46). There was a significant HP release in all products during the application times indicated by the manufacturers. Further studies are needed to assess in vitro release kinetics.

Comparison of five rotary systems regarding design, metallurgy, mechanical performance, and canal preparation-a multimethod research

OBJECTIVES

To compare the design, metallurgy, mechanical performance, and canal preparation of 5 rotary systems.

MATERIAL AND METHODS

A total of 735 25-mm NiTi instruments (sizes 0.17[0.18]/.02v, 0.20/.04v, 0.20/.07v, 0.25/.08v, 0.30/.09v) from ProTaper Gold, ProTaper Universal, Premium Taper Gold, Go-Taper Flex, and U-File systems were compared regarding overall geometry and surface finishing (stereomicroscopy and scanning electron microscopy), nickel and titanium ratio (energy-dispersive spectroscopy), phase transformation temperatures (differential scanning calorimetry), mechanical performance (torsional and bending tests), and unprepared canal surface (micro-CT). One-way ANOVA and Mood's median tests were used for statistical comparisons with a significance level set at 5%.

RESULTS

Stereomicroscopic analysis showed more spirals and high helical angles in the Premium Taper Gold system. All sets of instruments had symmetrical spirals, no radial lands, no major defects, and an almost equiatomic ratio between nickel and titanium elements, while differences were observed in their tips' geometry and surface finishing. At room temperature (20 °C), DSC test revealed martensitic characteristics for ProTaper Gold and Go-Taper Flex, and mixed austenite plus R-phase for the Premium Taper Gold, while ProTaper Universal and U-Files had full austenitic characteristics. Overall, larger instruments had higher torque resistance and bending load values than smaller ones, while a lack of consistency and mixed values were observed in the angle of rotation. The 0.25/.08v and 0.30/.09v instruments of ProTaper Universal and U-File had the highest maximum torques, the lowest angles of rotation, and the highest bending loads than other tested systems (P < .05). No significant difference was noted regarding the untouched root canal walls after preparation with the tested systems (P > .05).

CONCLUSIONS

Although differences observed in the overall geometry and phase transformation temperatures have influenced the results of mechanical tests, unprepared canal surface areas were equivalent among systems.

CLINICAL RELEVANCE

Root canal preparation systems with similar geometries might present different mechanical behaviors but equivalent shaping ability.

Prevalence of maxillary sinus septa: systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to determine the prevalence and characteristics of maxillary sinus septa using cone beam computed tomography and computed tomography data. Publications were searched until October 5, 2020 in three electronic databases. Additionally, article bibliographies were searched, and authors were contacted if required. This review has been registered in PROSPERO (CRD42019124933). Two independent evaluators assessed methodological quality using the Joanna Briggs Institute levels of evidence; inter-rater reliability tests were performed (Cohen's κ). The prevalence of maxillary sinus septa was expressed as a proportion; differences according to sex were reported in terms of the odds ratio (OR) and 95% confidence interval (95% CI). Heterogeneity and sources of heterogeneity were evaluated by meta-regression. Publication bias was assessed by visual analysis of the funnel plot. Statistical significance was set at P < 0.05. The 62 studies identified and included in the review involved 13,701 patients (22,460 sinuses). The meta-analysis of 35 studies (14,664 sinuses) revealed an overall mean sinus septa prevalence per sinus of 33.2% (95% CI 27.8-38.5%; I² = 98.32%). The meta-analysis of 42 studies (9631 patients) found an overall mean sinus septa prevalence per patient of 41.0% (95% CI 36.0-46.0%, I² = 96.45%). The OR for the difference in septa prevalence between sexes was 0.785 (95% CI 0.590-1.046; P = 0.098, I² = 73.24%). Septa were most frequent in the middle area of the sinus and with a transverse orientation (86.0%). Within the limitations, the results suggest a high proportion of septa in the sinus, commonly in the middle area, which can interfere with the success of sinus floor elevation required for implant rehabilitation.

Is the timing of implant placement and loading influencing esthetic outcomes in single-tooth implants?-A systematic review

OBJECTIVES

To address the following question: "Is the timing of implant placement and/or loading influencing the esthetic outcomes of implant-supported single crowns?"

MATERIAL AND METHODS

A literature screening was performed in four electronic databases until June 2020. Randomized controlled clinical trials with a minimum of 10 patients and 1 year of follow-up and reporting on dimensional changes of the peri-implant mucosa (midfacial recession, papilla level) and esthetic indexes were included. Cochrane Risk of Bias Tool was used, and comparable trials were subjected to meta-analyses.

RESULTS

Out of 8549 articles, 72 full-text articles were assessed for eligibility and 18 were included. Nine trials evaluated the timing of implant placement, and nine trials evaluated the timing of loading. The included trials comparing immediate implant placement to delayed implant placement evaluating the midfacial recession reported heterogeneous findings. No differences were found at 1 and 2-years, when comparing midfacial recession and papilla level between immediate and early implant placement. In immediate and delayed implant placement, when comparing conventional and immediate loading, the midfacial mucosal margin change was not statistically significant at the 1-year follow-up. When evaluating the timing of implant placement and/or loading the included trials found no differences in the Pink Esthetic score, White Esthetic score, and Papilla Index between groups.

CONCLUSIONS

Both immediate and early implant placement protocols presented stable treatment results in terms of esthetic outcomes at the 1-, 2-, and 10-years follow-up. Loading protocols did not seem to influence esthetic outcomes in short- and medium-term follow-ups.

Evaluation of Design, Metallurgy, Microhardness, and Mechanical Properties of Glide Path Instruments: A Multimethod Approach

INTRODUCTION

This study aims to compare the design, metallurgy, microhardness, and mechanical properties of 3 glide path nickel-titanium (NiTi) instruments.

METHODS

A total of 132 ProGlider (Dentsply Sirona, Ballaigues, Switzerland), Edge Glide Path (EdgeEndo, Johnson City, TN), and R-Pilot instruments (VDW, Munich, Germany) (44 per group) were selected. Design was assessed through stereomicroscopy (blades, helical angle, measuring lines, and deformation) and scanning electron microscopy (symmetry, cross section, tip, and surface finishing). NiTi ratios were measured by energy-dispersive X-ray spectroscopy and phase transformation temperatures by differential scanning calorimetry. Microhardness and mechanical performance (torsion, bending, and buckling resistance tests) were also evaluated. Statistical analyses were performed with the Mood median test with a significance set at 5%.

RESULTS

The Edge Glide Path had the lowest number of blades and the R-Pilot the greatest helical angle. All instruments had an almost equiatomic NiTi ratio, while showing different cross sections and tip geometries. The Edge Glide Path had a smoother surface finishing. The R-Pilot showed martensitic characteristics at room temperature, whereas mixed austenite plus R-phase was observed in the other instruments. The R-Pilot had higher results on the microhardness (436.8 hardness Vickers number), maximum torsion (0.9 Ncm), and buckling load (0.7 N) tests (P < .05), whereas the Edge Glide Path had a superior angle of rotation (683.5°) and the ProGlider was more flexible (144.1 gf) (P < .05).

CONCLUSIONS

Differences in the design of the instruments and the phase transformation temperatures accounted for their mechanical behavior. The R-Pilot showed the highest torque, buckling, and microhardness, whereas the ProGlider instrument was the most flexible.

Precision and trueness of maxillary crowded models produced by 2 vat photopolymerization 3-dimensional printing techniques

INTRODUCTION

This cross-sectional study aimed to analyze the precision and trueness of dental models produced using 2 rapid prototyping 3-dimensional printers.

METHODS

A digital crowded maxillary arch with a T-shaped base and 2 hemispheres of 2.5 mm radius was printed 10 times with a stereolithography apparatus (SLA) and digital light processing (DLP) in the highest precision and minimum layer thickness (z-resolution) mode. The copies were scanned using the D710 3Shape desktop scanner and assessed for precision and trueness via arch superimpositions and hemisphere measurements. Mann-Whitney U tests were used to compare trueness and precision among printers. Hemisphere radius was compared with the reference measurement and between 3-dimensional printers using 1 sample and independent Student t tests, respectively (α = 0.05).

RESULTS

The root mean square values of arch superimpositions showed statistically significant differences between the 2 techniques, both for precision (P = 0.011): SLA (46.8 μm ± 13.5); DLP (111.1 μm ± 71.9), and trueness (P = 0.015): SLA (61.1 μm ± 9.8); DLP (99.8 μm ± 47.2). The color map model analysis indicated greater distortion on premolar and molar surfaces, with a higher range of contraction on the SLA and both contraction and expansion on the DLP. Anterior and posterior hemisphere radius registered increased values with DLP (1.7% and 0.49%) and reduced values with SLA (0.6% and 0.7%); however, only the anterior SLA hemispheres revealed a significant decrease from the reference value (P = 0.037).

CONCLUSIONS

In this study, the SLA printer was significantly different from the DLS printer, with the highest precision and trueness.

Design, metallurgical features, mechanical performance and canal preparation of six reciprocating instruments

AIM

To compare six reciprocating instruments regarding their geometric design, metallurgical characteristics, mechanical behaviour and ability to prepare root canals.

METHODOLOGY

A total of 246 new 25-mm NiTi instruments (41 per group) from six reciprocating systems (Reciproc, Reciproc Blue, One Files, One Files Blue, Reverso Silver, and WaveOne Gold) were evaluated throughout a multimethod approach regarding their design using stereomicroscopy (number of blades and helix angle) and scanning electron microscopy (blades symmetry, cross section and surface finishing), nickel-titanium composition, phase transformation temperatures, mechanical performance (cyclic fatigue, torsional and bending resistance) and unprepared canal surface area on anatomically matched mandibular molars assessed by micro-CT. One-way ANOVA and post hoc Tukey's or Mood's median tests were selected depending on sample distribution with significance level set at 5%.

RESULTS

The instruments had similarities regarding their metal composition and unprepared canal area, whilst differences in phase transformation temperatures and geometric design (number of blades, surface finishing and tip geometry) were observed. Overall, no difference was observed regarding the maximum torque values (P > 0.05), whilst One Files (72 s) and One Files Blue (414 s) had the shortest and longest times to fracture, respectively (P < 0.05). Similar angles of rotation were observed in Reciproc (310°), One Files (285°) and Reverso Silver (318°) instruments (P > 0.05), which were significantly lower than Reciproc Blue (492°), One Files Blue (456°) and WaveOne Gold (492°; P < 0.05). Maximum bending load demonstrated that Reciproc Blue (201.3 gf) was significantly more flexible that the other instruments (P < 0.05).

CONCLUSION

Although there were similarities in metal composition and percentage of unprepared canal surface, the instruments had differences in the overall geometric design, phase transformation temperatures and in the four mechanical resistance parameters (time to fracture, maximum torque, angle of rotation and maximum bending load).

Comparison of design, metallurgy, mechanical performance and shaping ability of replica-like and counterfeit instruments of the ProTaper Next system

AIM

To compare the ProTaper Next (PTN) system with a replica-like and a counterfeit system regarding design, metallurgy, mechanical performance and shaping ability.

METHODOLOGY

Replica-like (X-File) and counterfeit (PTN-CF) instruments were compared to the PTN system regarding design (microscopy), phase transformation temperatures (differential scanning calorimetry), nickel-titanium ratio (energy-dispersive X-ray spectroscopy), cyclic fatigue, torsional resistance, bending strength, and untouched canal areas in extracted mandibular molars (micro-CT). anova, post hoc Tukey's and Kruskal-Wallis tests were used according to normality assessment (Shapiro-Wilk test) with the significance level set at 5%.

RESULTS

Overall similarities in design and nickel-titanium (Ni/Ti) ratio were observed amongst instruments with the X-File having a smoother surface finish. PTN and PTN-CF had mixed austenite plus R-phase (R-phase start approximately at 45 ºC and near 30 ºC, respectively), whilst X-File instruments were austenitic (R-phase started at approximately at 17 ºC) at room temperature (20 ºC). PTN-CF had the greatest inconsistency in the phase transformation temperatures. Time to fracture of PTN-CF X2 and X3 was significantly shorter than PTN and X-File instruments (P < 0.05), whilst no difference was noted in maximum torque to fracture amongst the tested systems (P > 0.05). X-Files and PTN-CF had a stress-induced phase change during bending load. Mean unprepared surface areas of root canals were 25.8% (PTN), 31.1% (X-File) and 32.5% (PTN-CF) with no significant difference amongst groups (P > 0.05).

CONCLUSION

Similarities amongst the systems were noted in the Ni/Ti ratio and maximum torque to fracture, whilst differences were observed in the design, phase transformation temperatures and mechanical behaviour. The ProTaper Next counterfeit instruments could be considered as the less secure system considering its low-cyclic fatigue resistance. Apart from these differences, the unprepared canal surface areas, obtained with the tested systems, were similar.

Survival Rate of 1008 Short Dental Implants with 21 Months of Average Follow-Up: A Retrospective Study

This retrospective study evaluated the survival rate of short, sandblasted acid-etched surfaced implants with 6 and 8 mm lengths with at least 120 days of follow-up. Data concerning patient, implant and surgery characteristics were retrieved from clinical records. Sandblasted and acid-etched (SLA)-surfaced tissue-level 6 mm (TL6) or 8 mm (TL8) implants or bone-level tapered 8 mm (BLT8) implants were used. Absolute and relative frequency distributions were calculated for qualitative variables and mean values and standard deviations for quantitative variables. A Cox regression model was performed to verify whether type, length and/or width influence the implant survival. The cumulative implant survival rate was assessed by time-to-event analyses (Kaplan–Meier estimator). In all, 513 patients with a mean age of 58.00 ± 12.44 years received 1008 dental implants with a mean follow-up of 21.57 ± 10.77 months. Most implants (78.17%) presented a 4.1 mm diameter, and the most frequent indication was a partially edentulous arch (44.15%). The most frequent locations were the posterior mandible (53.97%) and the posterior maxilla (31.55%). No significant differences were found in survival rates between groups of type, length and width of implant with the cumulative rate being 97.7% ± 0.5%. Within the limitations of this study, the evaluated short implants are a predictable option with high survival rates during the follow-up without statistical differences between the appraised types, lengths and widths.

Street Medical Consultation: health access of the Homeless People and intersectoral articulation

Background

The Homeless People is marked by serious social vulnerability, related to the absence of human dignity. Requirements of personal and residential documents, reception and inadequate approaches are barriers to access these people. The creation of Street Medical Consultation (CnaR), based on the logic of harm reduction in association with the other services, is a strategy that seeks to expand access to the services of the Public Healthcare System (SUS) in Brazil. The research aimed to analyze the characteristics and vulnerabilities of this population, the performance of CnaR and its articulation with services from the health care and the social assistance care network.

Methods

Study of a qualitative approach using 8 semi-structured interviews and the Thematic Content Analysis method. The study scenario was the CnaR multiprofissional team in a city in the interior of São Paulo.

Results

Three categories were found: (1) Population in Street Situation - complexity of those who live on the street: prejudices, violence and barriers in society and health institutions constitute a process of invisibility. (2) CnaR's work in the perspective of harm reduction: it is organized to meet the clinical and alcohol and other drugs demands through fixed fields, mobile fields and team meeting. (3) Beyond CnaR - network relationships: bringing dynamics to relationships, being strengthened or weakened. Ignorance of the service and their performance also generates CnaR invisibility process. The strategies developed include coping, dialogue, building partnerships and the process of visibility and fighting for the rights of the Homeless Persons.

Conclusions

CnaR finds itself as an insufficient service to meet all the demands of this vulnerable population in isolation, needing the network to expand access to health and other goods. It is necessary to combat prejudice against this population among health professionals and develop more efficient intersectoral articulation.

Key messages

The Homeless People have serious vulnerability and need humanization, guaranteeing equity in assistance in all sectors of society, especially the health care and the social assistance. The Street Medical Consultation faces performance difficulties to guarantee access to the Homeless People within the intersectoral network, often being the sole responsible for this population.

Dental prophylaxis influence in tooth color assessment-Clinical study

OBJECTIVE

To evaluate dental prophylaxis influence in tooth color assessment with the use of different methods.

MATERIALS AND METHODS

Volunteers were consecutively recruited and screened according to appropriate inclusion/exclusion criteria. Each participant's upper right central incisive and canine color was measured before and after dental prophylaxis with a one-week interval. Tooth color assessment was performed by calibrated operators and the patient using a VITA Classical shade guide and by spectrophotometric methods with a proper device (SpectroShade). Color was reported as mean with SD of Commission Internationale De l'Eclairage (CIE) L*a*b* values, ΔE_ab and ΔE₀₀ . One-way analysis of variance and Tukey post hoc were performed to assess differences between methods and paired t test for assessing differences in tooth color coordinates after dental prophylaxis. Values of P < .05 were taken as significant.

RESULTS

Fifty patients were included. Self-assessed dental prophylaxis effects equated to a significantly different mean ΔE₀₀ value of 2.3 ± 1.7 (P < .01), when compared to the calibrated operator reported 0.8 ± 1.1 and the spectrophotometer 1.0 ± 0.5. Half of volunteer's ΔE₀₀ values surpassed the acceptability threshold, when compared to 28% from investigator and 10% from spectrophotometer.

CONCLUSION

Performing a dental prophylaxis did have an influence in tooth color perception with a higher self-perceived effect in the patient assessment.

CLINICAL SIGNIFICANCE

The results of this study suggest that performing professional dental prophylaxis presented a perceived effect in tooth color regardless of the method used being that patients precepted whiter and less yellowish teeth. Since extrinsic stain is considered as one of the factors that could influence tooth color assessment, performing professional dental prophylaxis prior to composite or ceramic color selection in anterior teeth restorations could consequently increase treatment predictability.

Malignant transformation rate of oral leukoplakia-systematic review

OBJECTIVE

The aim of this study was to perform a systematic review of prevalence studies to determine the rate of malignant transformation of oral leukoplakia and assess the influence of demographic factors (age, gender, and geographic region) on the overall transformation rate.

STUDY DESIGN

A search was conducted for publications until July 2019 in 4 electronic databases and peer-reviewed journals. A manual search was performed on the bibliographies of the collected articles, and the authors were contacted for additional information. This study was previously registered with the trial number CRD42019126909 and study quality assessed through established methods. The results were expressed by means of proportions or odds ratios with a 95% confidence interval. Meta-regression was undertaken to evaluate possible sources of heterogeneity, and funnel plot visual analysis was performed to assess publication bias.

RESULTS

The 34 observational epidemiologic studies included reported data on 26,209 patients with oral leukoplakia from 18 different countries. Meta-analysis of 32 studies (23,489 patients) presented an estimated overall mean proportion of malignant transformation rate of 9.70% (7.80-11.70) (I² = 98.66%; τ² < 0.001; χ² = 23.18; degrees of freedom [df] = 31). When comparing genders, the odds ratio favored males with 0.622 (0.468-0.826) (I² = 29.77%; τ² = 0.089; χ² = 22.78; df = 16).

CONCLUSIONS

Within the limitations of the included studies in this systematic review, the results suggest that the malignant transformation rate was dependent on demographic factors and follow-up time. Future studies should include the development of guidelines to standardize the methodology for long-term follow-up assessment, thus reducing the risk of bias.

Validation of a Portuguese version of the Groningen radiotherapy-induced xerostomia questionnaire

Background

The aim of this study was to validate and determine at pretest level the reliability of the Portuguese version of the Groningen radiotherapy-induced xerostomia questionnaire.

Material and Methods

This study employed 37 head and neck cancer patients. Each patient signed an informed consent and responded to the Portuguese version of the questionnaire in the form of an interview. This was repeated again after 2 weeks. A standard single question provided a validity check. Data were analyzed using Cronbach’s α to test its reliability and total and interitem correlation, and intraclass correlation to determine its internal consistency and test-retest reliability. Construct validity supported by objective measurements as salivary secretion was also investigated. Significance was set at .05.

Results

Cronbach’s α was 0.91 and 0.89 for the first and second test administrations, respectively, which indicates that the internal consistency was excellent. The intraclass correlation coefficient value for the test-retest reliability was 0.70. The correlation between the total score of the questionnaire and standard single dry mouth question was 0.72 for the first round, indicating a good correlation.

Conclusions

Demonstrating very good psychometric properties, the Portuguese version of the Groningen radiotherapy-induced xerostomia questionnaire is a valid tool and can be considered a reliable instrument to measure xerostomia in head and neck cancer patients.

Key words:Xerostomia, quality of life, xerostomia questionnaire, transcultural validation, head and neck cancer, radiotherapy, saliva.

Prevalence of C-shaped mandibular molars in the Portuguese population evaluated by cone-beam computed tomography

Objective:

The purpose of this study was to evaluate the prevalence of first and second C-shaped mandibular molars in a Western European population of Portuguese Caucasians.

Materials and Methods:

Patients having both routine panoramic radiograph and presurgical cone-beam computed tomography (CBCT) exams were selected. The CBCT examination was performed at five different axial levels and the mandibular molars were classified as C-shape according to the Fan criteria. Differences between genders, age groups, left and right side, type of tooth, and root concavity side were determined. The molars were classified as nonfused roots (NFRI–II), FRI–III, or single root with single canal (SS) groups, using the panoramic radiograph. The prevalence of C-shaped anatomy was calculated to each group.

Results:

A total of 1783 teeth (695 first molars and 1088 second molars) from 792 patients were included in the study. The prevalence of C-shaped configurations was 0.6% and 8.5% to mandibular first and second molars, respectively. The differences between gender, teeth, and root concavity direction were considered statistically significant (P < 0.05). The FR had a significantly higher rate of C-shapes when compared to NFR (P < 0.05). Intrarater reliability was 93.6%.

Conclusions:

The FR radiographic appearance may be considered a predictor of this anatomy. Second mandibular molars and females had a higher incidence ratio. Apparently, the mandibular C-shaped anatomy is more common in the population of this study than that has been previously reported for the European population.

Total digital workflow in the fabrication of a partial removable dental prostheses: A case report

This report describes a clinical and laboratory protocol used in the fabrication of a removable partial dental prosthesis with a digital workflow in a 73-year-old patient. The metal framework was produced with a selective laser melting technique. For quality assurance and discrepancy analysis, the framework was superimposed and compared to the respective digital design file, and the printed model was also compared to the digital impression and rendered as a 3D colour map. Differences were detected in the framework on the clasp of tooth 17 (upper right second molar) and on the printed model on the interproximal surfaces of the abutments, particularly on tooth 17 and palatine area. The use of this digital workflow allowed for the achievement of an removable partial dental prosthesis with a good fit and occlusion with minimal adjustments, with the reduction of both clinical and laboratory time. Further studies are needed to gain a better understanding of these techniques.

Gender influence on the number of roots and root canal system configuration in human permanent teeth of a Portuguese subpopulation

OBJECTIVE

The aim of this study was to investigate in vivo, using cone beam computed tomography (CBCT), the differences between genders regarding the number of roots and root canal morphology.

METHOD AND MATERIALS

An existing CBCT scan database was accessed and the scans were divided in two groups according to gender. Tooth inclusion and exclusion criteria were applied. The examined teeth were classified according to the number of roots, and the root canal system was classified according to Vertucci classification. Z-test for independent groups was used to detect differences between groups.

RESULTS

In total, 12,325 teeth (4,597 from males and 7,728 from females) from 670 patients were analyzed. Females presented a lower number of roots per tooth in all groups of teeth, except for mandibular canine, the difference being statistically significant in the maxillary first premolar and both maxillary and mandibular second molars. Vertucci Type I configuration had a higher or equal prevalence in nine of the eleven groups of maxillary roots in females, with significance in both maxillary premolars. The same configuration was higher in females in five of the nine groups of mandibular roots, with significance in mandibular central incisor and first premolar. Eight of the nine root groups (maxillary and mandibular roots combined) that presented three-root canal system configurations, had a higher prevalence of that anatomy in males.

CONCLUSION

Few differences were found between genders. It was possible to detect a lower number of roots per tooth and a higher number of Vertucci Type I configurations in females. The three-root canal system configurations were more common in males.

Validation of Oral Health Impact Profile-14 and its association with Hypossialia in a Sjögren Syndrome Portuguese Population

AIMS

The objective of this study was to perform the Portuguese transcultural adaptation of the original Brazilian version of the Oral Health Impact Profile-14 (OHIP-14) while evaluating the association between hyposalivation and quality of life in a Sjögren´s Syndrome population.

METHODS

The original Brazilian version of the Oral Health Impact Profile-14 was culturally adapted following the guidelines for cross-cultural adaptation of health-related quality of life measures. The questionnaires were administered by trained and calibrated dental doctors to 86 patients with Sjögren´s Syndrome. Oral Health Impact Profile-14 properties were examined including reliability, internal consistency and test-retest reliability, using Cronbach's alpha, total and inter-item correlation, and intra-class correlation coefficients, respectively. Whole saliva secretion rates and hyposalivation-related variables were collected and statistically analyzed. Spearman´s rho correlations were obtained between salivary flows and OHIP -14 domains and total score. Alpha was set at 0.05. Informed consents and local ethical committee clearance were obtained.

RESULTS

Each question of the questionnaire performed adequately. Cronbach alpha values for the 14 questions were 0.89 for both test administrations and were lower if item removed. Scores for both questionnaire administration and ICC results presented good to excellent reliability with ICC ranging from 84% to 92%. Mean salivary flow rate was 0.05 (SD: 0.03) ml/min and mean stimulated salivary flow was 0.57 (SD: 0.44) ml/min, which are within expected values in a population with hyposalivation. The results describe a negative and significant correlation between total OHIP-14-PT score, physical pain, physical disability domain and stimulated and differential salivary flows. There was a negative and significant correlation between unstimulated salivary flow with physical pain.

CONCLUSION

Within the limitations of this study, the OHIP-14-PT seems to be a valid and reliable instrument for measuring oral health related quality of life in patients with Sjögren´s Syndrome. Both differential and stimulated salivary flows seem to correlate negatively with age and the quality of life is significantly diminished by lower stimulated salivary flow rates.

Neonatal maternal separation opposes the facilitatory effect of castration on the respiratory response to hypercapnia of the adult male rat: Evidence for the involvement of the medial amygdala

Respiratory manifestations of panic disorder (PD) include a greater respiratory instability and enhanced responsiveness to CO₂ compared to normal individuals. Although the prevalence of PD is approximately three times greater in women compared to men, the origins of this sexual dimorphism remain poorly understood. Similar to PD patients, adult female rats previously subjected to neonatal maternal separation (NMS) show an increase in their ventilatory response to CO₂ . Because this effect of NMS is not observed in males, we hypothesised that testosterone prevents NMS-induced hyper-responsiveness to CO₂ . Pups subjected to NMS were placed in an incubator for 3 h d^-1 from postnatal days 3-12. Control pups remained undisturbed. At adulthood (8-10 weeks of age), rats were then subjected either to sham surgery or castration. Fourteen days later, breathing was measured at rest (room air) and during acute exposure to hypercapnia (5 and 10% CO₂ for 10 minutes each) using plethysmography. To gain insight into the mechanisms involved, c-fos expression was used as an indicator of neuronal activation. Brains were collected following air or CO₂ exposure for quantification of c-fos positive cells by immunohistochemistry in selected regions, including the paraventricular nucleus of the hypothalamus, the dorsomedial hypothalamus and the amygdalar complex. Castration produced a 100% increase of hyperventilatory response to 10% CO₂ in control rats. Unexpectedly, castration had no effect on the hyperventilatory response of NMS rats. The intensity of the hypercapnic response was inversely correlated with c-fos expression in the medial amygdala. We conclude that testosterone prevents the hyper-responsiveness to CO₂ , whereas NMS attenuates sensitivity to hormone withdrawal. We propose that an inhibitory influence from the medial amygdala contributes to this effect.