Chlorhexidine-Containing Electrospun Polymeric Nanofibers for Dental Applications: An In Vitro Study.

Chlorhexidine is the most commonly used anti-infective drug in dentistry. To treat infected void areas, a drug-loaded material that swells to fill the void and releases the drug slowly is needed. This study investigated the encapsulation and release of chlorhexidine from cellulose acetate nanofibers for use as an antibacterial treatment for dental bacterial infections by oral bacteria Streptococcus mutans and Enterococcus faecalis. This study used a commercial electrospinning machine to finely control the manufacture of thin, flexible, chlorhexidine-loaded cellulose acetate nanofiber mats with very-small-diameter fibers (measured using SEM). Water absorption was measured gravimetrically, drug release was analyzed by absorbance at 254 nm, and antibiotic effects were measured by halo analysis in agar. Slow electrospinning at lower voltage (14 kV), short target distance (14 cm), slow traverse and rotation, and syringe injection speeds with controlled humidity and temperature allowed for the manufacture of strong, thin films with evenly cross-meshed, uniform low-diameter nanofibers (640 nm) that were flexible and absorbed over 600% in water. Chlorhexidine was encapsulated efficiently and released in a controlled manner. All formulations killed both bacteria and may be used to fill infected voids by swelling for intimate contact with surfaces and hold the drug in the swollen matrix for effective bacterial killing in dental settings.

The rs579459 ABO gene polymorphism and risk of incident cardiovascular events in obstructive sleep apnea: a pilot study.

PURPOSE: We have previously shown that the TT genotype (rs579459 location of the ABO gene) is significantly associated with circulating levels of e-selectin in patients with suspected obstructive sleep apnea (OSA). We hypothesized that this genotype would be associated with incident cardiovascular disease (CVD). METHODS: Patients with suspected OSA who had a full diagnostic polysomnogram from 2003 to 2011 were recruited; CV events occurring within 8 years of polysomnography were identified by linkage to provincial health databases. Cox proportional hazards models were used to evaluate the incidence of first CV events as a function of the rs579459 genotype. RESULTS: In this targeted study, 408 patients were studied, and 39 incident events were identified. A larger proportion of patients with the TT genotype had an event (31/247; 12.6%) than the CT and CC genotypes (8/161; 5.0%); in univariate analysis, the TT genotype was significantly associated with CV events (HR = 2.53; 95% CI = 1.16-5.51, p = 0.02). After adjustment for age, AHI, sex, smoking, diabetes, statin use, and BMI, the TT genotype remained a significant predictor (HR = 2.35; 95% CI = 1.02-5.42, p = 0.046). No events were found in patients with an absence of both OSA and the TT genotype (N = 30). The effect of the SNP was partially (16.2%) mediated by e-selectin levels. CONCLUSION: This is the first study to examine genetic variants as a risk factor for incident CVD in the context of OSA. Although these results are preliminary and in need of replication, it suggests that genetic markers may become useful in helping to guide precision clinical care.

Symptom subtypes and risk of incident cardiovascular and cerebrovascular disease in a clinic-based obstructive sleep apnea cohort.

STUDY OBJECTIVES: Patients with obstructive sleep apnea (OSA) are at increased risk of cardiovascular and cerebrovascular disease, but predicting those at greatest risk is challenging. Using latent class analysis, patients with OSA can be placed into discrete symptom subtypes. The aim of this study was to determine whether symptom subtypes are associated with future cerebrovascular disease in patients with OSA in a clinic-based cohort. METHODS: Patients with suspected OSA referred for a polysomnogram at an academic sleep center completed a comprehensive symptom survey. Patients with OSA (apnea-hypopnea index ≥ 5 events/h) were then placed into symptom subtypes based on responses to survey questions using latent class analysis. Cardiovascular events (stroke, myocardial infarction, unstable angina, bypass grafting, percutaneous coronary intervention, cardiac resynchronization therapy, defibrillation) occurring within 8 years of polysomnogram were identified by linkage to provincial health databases. RESULTS: 1,607 patients were studied, of whom 1,292 had OSA. One hundred forty first events occurred within 8 years of polysomnogram. Patients in the excessively sleepy with disturbed sleep subtype had a significantly increased rate of events compared to the minimally symptomatic subtype (hazard ratio = 2.25, 95% confidence interval: 1.02-4.94; P = .04). Two symptoms (restless legs and dozing off or sleeping while talking to someone) were significantly associated with future risk of cerebrovascular disease (hazard ratio = 1.68, 1.12-2.49 and 4.23, 1.61-11.16, respectively). CONCLUSIONS: Patients with OSA in the clinic who are in the excessively sleepy with disturbed sleep subtype are significantly more likely to have a future cardiovascular event. This underscores the importance of understanding clinical heterogeneity and incorporating symptom subtype definitions into routine clinical care. CITATION: Allen AJH, Jen R, Mazzotti DR, et al. Symptom subtypes and risk of incident cardiovascular and cerebrovascular disease in a clinic-based obstructive sleep apnea cohort. J Clin Sleep Med. 2022;18(9):2093-2102.

Circulating markers of oxidative stress and risk of incident cardiovascular events in obstructive sleep apnea.

The identification of which patients with obstructive sleep apnea (OSA) are more likely to develop cardiovascular disease (CVD) remains a challenge. OSA causes oxidative stress (OS) which may contribute to CVD pathogenesis. Therefore, OS markers could be useful in risk-stratifying cardiovascular (CV) risk in OSA patients. The purpose of this pilot study was to assess whether three OS marker levels could be associated with incident CVD in suspected OSA patients. Morning plasma levels of 8-isoprostane, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and superoxide dismutase (SOD) were measured in patients with suspected OSA referred for a polysomnogram (PSG). A composite outcome of CV events was defined by linkage with provincial administrative health databases. Cox proportional hazards models were used to assess the relationship between the levels of OS markers and events. 352 patients were included (mean age of 51.4 years, 68% male, median apnea hypopnea index of 16/h). Thirty-one first CV events occurred over an 8-year follow-up. In univariate or fully adjusted models, none of the OS markers were significantly associated with incident CV events (hazard ratio in adjusted models of: 1.25 (95% CI 0.56-2.80, p = 0.59), 1.15 (0.52-2.57, p = 0.73), 0.77 (0.37-1.61, p = 0.48), for 8-OHdG, 8-isoprostane and SOD; however, confidence intervals were wide. In this small preliminary study, oxidative stress markers were not significantly associated with risk of CV events. However, moderate associations between these markers and risk of CV events are possible and should be the focus of future larger studies. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-022-00399-0.

Circulating levels of cell adhesion molecules and risk of cardiovascular events in obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) patients are at increased risk of cardiovascular disease (CVD). Cell adhesion molecules (CAM) are increased in OSA and CAM are also implicated in the development of CVD. RESEARCH QUESTION: Do CAM (ICAM-1, VCAM-1 and E-selectin) have prognostic value in identifying risk of cardiovascular events in OSA? STUDY DESIGN AND METHODS: Patients with suspected OSA referred for a polysomnogram provided a fasting blood sample. Plasma levels of ICAM-1, VCAM-1 and E-selectin were determined by multiplex Luminex Assay (Milliporesigma ON, Canada). Cardiovascular events were determined by deterministic linkage to provincial health databases. RESULTS: 418 patients were included in the analysis. Mostly male (68.2%), mean age of 50.7 yrs, median AHI 16.5 events/hour, and mean BMI of 31.7 kg/m2. 36 cardiovascular events occurred in 8-yrs of follow up. Higher levels of ICAM-1 were associated with developing CVD (HR = 3.65 95% CI 1.40-9.53, 2nd and 3rd tertiles vs. 1st tertile), including in patients with OSA (HR = 3.1 95% CI 1.16-8.25). E-selectin was significantly associated with cardiovascular events in patients with moderate to severe OSA (HR = 3.31 95% CI 0.94-11.72, 2nd and 3rd tertiles vs. 1st tertile) but not in patients without moderate to severe OSA (HR = 0.67 95% CI 0.19-2.38), p-value for interaction = 0.07. INTERPRETATION: In a suspected OSA cohort, patients with higher levels of ICAM-1 (>816 ng/ml) were significantly more likely to experience a cardiovascular event within 8 years after PSG. In moderate to severe OSA patients, a higher E-selectin (>36.4 ng/ml) was significantly associated with cardiovascular events.

Long-term periodontal changes associated with oral appliance treatment of obstructive sleep apnea.

STUDY OBJECTIVES: To characterize the mandibular anterior teeth crown height as a marker of periodontal changes and bone loss as a side effect of an oral appliance worn for a minimum of 4.5 years. METHODS: This retrospective study conducted in patients with healthy baseline periodontium recruited participants among consecutive sleep apnea patients treated with an oral appliance between 2004 to 2014. Eligible participants were recalled for a follow-up visit at which a periodontal examination was performed and a lateral cephalogram and dental impressions were obtained. Clinical crown height for mandibular anterior teeth and cephalometric variables were measured and compared before and after treatment. A full periodontal evaluation was performed at the follow-up visit. RESULTS: Twenty-one patients enrolled with a mean treatment length of 7.9 ± 3.3 years. For the mandibular anterior teeth, clinical crown height did not change over the evaluated period. At follow-up, all the periodontal assessed variables were within normal limits, with the mean probing depth of 1.4 ± 0.5 mm, recession 0.6 ± 1.1 mm, and clinical attachment loss 0.8 ± 1.0 mm. Compared with baseline, there was a significant proclination of mandibular incisors (mean increase of 5.1 degrees) with the continued use of an oral appliance. Gingival levels were maintained with clinically insignificant changes during the observation period. CONCLUSIONS: Inclination of the mandibular incisors increases significantly with the use of an oral appliance in patients with obstructive sleep apnea. Positional changes in these teeth were not associated with any measured evidence of increase in clinical crown height or gingival recession. CITATION: Heda P, Alalola B, Almeida FR, Kim H, Peres BU, Pliska BT. Long-term periodontal changes associated with oral appliance treatment of obstructive sleep apnea. J Clin Sleep Med. 2021;17(10):2067-2074.

Obstructive Sleep Apnea Severity, Body Mass Index, and Circulating Levels of Cellular Adhesion Molecules.

PURPOSE: To investigate the relationship between obstructive sleep apnea (OSA) severity, body mass index (BMI), and circulating levels of inflammatory adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin). METHODS: A cross-sectional clinical cohort study on all consecutive adults referred to the University of British Columbia (UBC) Sleep Laboratory for a polysomnogram (PSG) for suspected OSA provided a morning blood sample. Samples were analyzed with multiplex immune assay (MilliporeSigma, CA) to assess the levels of adhesion molecules. RESULTS: 488 patients were studied; the majority were male (68%) with a mean age of 50 yrs, mean AHI of 23 events/hour, and mean BMI of 32 kg/m2. In multivariable linear regression models, all three adhesion molecules were significantly associated with BMI (E-selectin p < 0.0001; ICAM-1 p = 0.0007; VCAM-1 p = 0.0003). However, only E-selectin was independently associated with AHI (p = 0.02); there was no significant interaction between AHI and BMI for E-selectin (p = 0.33). CONCLUSIONS: Although all three adhesion molecules were associated with BMI, only E-selectin was independently associated with OSA severity. Future studies are needed to determine the clinical significance of the relationship between E-selectin and OSA.

Obstructive Sleep Apnea and Circulating Biomarkers of Oxidative Stress: A Cross-Sectional Study.

Oxidative stress (OS) drives cardiometabolic diseases. Intermittent hypoxia consistently increases oxidative stress markers. Obstructive sleep apnea (OSA) patients experience intermittent hypoxia and an increased rate of cardiovascular disease, however, the impact of OSA on OS markers is not clear. The objective was to assess relationships between OSA severity and biomarker levels. Patients with suspected OSA referred for a polysomnogram (PSG) provided fasting blood sample. Plasma levels of 8-isoprostane, 8-hydroxydeoxyguanosine (8-OHdG), and superoxide dismutase (SOD) were measured. The relationship between OSA and OS was assessed both before and after controlling for confounders (age, sex, smoking history, history of cardiovascular disease, ethnicity, diabetes, statin usage, body mass index (BMI)). 402 patients were studied (68% male, mean age ± SD = 50.8 ± 11.8 years, apnea-hypopnea index (AHI) = 22.2 ± 21.6 events/hour, BMI = 31.62 ± 6.49 kg/m2). In a multivariable regression, the AHI significantly predicted 8-isoprostane levels (p = 0.0008) together with age and statin usage; AHI was not a predictor of 8-OHdG or SOD. Female sex (p < 0.0001) and no previous history of cardiovascular disease (p = 0.002) were associated with increased antioxidant capacity. Circulating 8-isoprostane levels may be a promising biomarker of the severity of oxidative stress in OSA patients. Prospective studies are needed to determine whether this biomarker is associated with long-term cardiometabolic complications in OSA.

Air Pollution and Systemic Inflammation in Patients With Suspected OSA Living in an Urban Residential Area.

BACKGROUND: Air pollution and OSA are independently associated with systemic inflammation, but it is unknown if these exposures interact to influence systemic inflammation. RESEARCH QUESTION: The study objective was to determine the relative importance of these factors and their combined potential to influence systemic inflammation in patients under assessment for sleep ailments. STUDY DESIGN AND METHODS: A total of 315 patients contributed data, including a questionnaire, polysomnogram, and morning serum IL-6 and IL-10 concentrations. For each patient, residential annual average air pollution exposure (nitrogen dioxide [NO2], black carbon [BC], and particulate matter with an aerodynamic diameter ≤ 2.5 µm [PM2.5]) was estimated with a land use regression model. Linear regression modeling was used adjusting for age, sex, apnea-hypopnea index, BMI, smoking, socioeconomic status, and comorbidities. RESULTS: In adjusted models, quartile 4 PM2.5 exposure (compared with quartiles 1-3) was associated with increased IL-6 and IL-10 concentrations (estimated adjusted, 7.1 pg/mL [95% CI, 2.5-11.7; P < .01] and 71.4 pg/mL [95% CI, 38.2-103.7; P < .0001], respectively). OSA, BC, and NO2 were not associated with IL-6 or IL-10 in similar analyses; however, moderate to severe OSA influenced the effect of BC on IL-6 (interaction term, P = .01), with no significant interaction terms observed for NO2 or PM2.5. Subsequent stratified analysis showed that in the 173 patients with moderate to severe OSA, quartile 4 BC exposure (compared with quartiles 1-3) was associated with an increased IL-6 concentration (estimated adjusted, 8.9 pg/mL; 95% CI, 1.7-16.1; P = .02). INTERPRETATION: Long-term residential PM2.5 exposure was associated with increased IL-6 and IL-10 concentrations in patients evaluated for suspected OSA. BC exposure was also associated with increased IL-6 but only in the subgroup of patients with moderate to severe OSA. These data suggest the potential for joint effects of moderate to severe OSA and air pollution on systemic inflammation.

Obstructive Sleep Apnea Severity and the Risk of Occupational Injury: A Prospective Observational Cohort.

OBJECTIVE: To determine whether patients with obstructive sleep apnea (OSA) are at increased risk of occupational injury (OI) METHODS: Working patients (aged 18 to 65 who reported more than 10 h of work per week) who were referred to the University of British Columbia Sleep Laboratory for suspected OSA for polysomnogram (PSG) were recruited from 2003 to 2011. Patients completed an extensive survey the night of their PSG. Validated OI was obtained by linking patient data to Workers Compensation Board Claims Data. RESULTS: 1109 workers were studied; mean age was 47.1 years, median AHI was 15.0/h, median BMI was 30 kg/m2, 70.2% were male and 29% of patients worked in physical or manual related occupations. 78 patients (7.03%) suffered 140 OI in the 5 years after PSG. In a multivariate logistic regression model, OSA severity [defined as a log(AHI + 1)] was a significant predictor of OI (p = 0.04) after controlling for age, sex, BMI, and physical or manual related occupations. Patients with moderate and severe OSA had approximately two times the odds of an OI compared to patients without OSA (OR 1.99, 95% CI 0.96-4.44 and 2.00, 95% CI 0.96-4.49 for moderate and severe OSA groups, respectively). CONCLUSIONS: In this prospective study, OSA severity was independently associated with an increased risk of OI.

Doxycycline release and antibacterial activity from PMMA/PEO electrospun fiber mats.

OBJECTIVE: To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen. METHODOLOGY: PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis. RESULTS: The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans. CONCLUSION: The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.

Experimental composites of polyacrilonitrile-electrospun nanofibers containing nanocrystal cellulose.

OBJECTIVE: To test the effects of addition of polyacrilonitrile (PAN) nanofibers and nanocrystal cellulose (NCC)-containing PAN nanofibers on flexural properties of experimental dental composites. METHODS: 11wt% PAN in dimethylformamide (DMF) solution was electrospun at 17.2kVA and 20cm from the collector drum. NCC was added to the solution at 3wt%. Fiber mats were produced in triplicates and tested as-spun. Strips (5cm×0.5cm) were cut from the mat in an orientation parallel and perpendicular to the rotational direction of the collector drum. Tensile tests were performed and ultimate tensile strength (UTS), elastic modulus (E) and elongation at maximum stress (%) were calculated from stress/strain plots. Fiber mats were then infiltrated by resin monomers (50/50 BisGMA/TEGDMA wt%), stacked in a mold (2×15×25) and light-cured. Beams (2×2×25mm) were cut from the slabs and tested in a universal testing machine. Data were analyzed by multiple t-test and one-way ANOVA (α=0.05). RESULTS: Addition of 3% NCC resulted in higher tensile properties of the fibers. Fibers presented anisotropic behavior with higher UTS and E when tested in perpendicular orientation. The incorporation of 3% NCC-PAN nanofibers resulted in significant increase in work of fracture and flexural strength of experimental dental composite beams. SIGNIFICANCE: NCC was found to be a suitable nanoparticle to reinforce experimental dental composites by incorporation via nanofiber. This fundamental study warrants future investigation in the use of electrospun nanofibres as a way to reinforce dental composites.

Nanocrystalline cellulose as a reinforcing agent for electrospun polyacrylonitrile (PAN) nanofibers.

OBJECTIVES: Nanocrystalline cellulose (NCC) is a sustainable material with excellent mechanical properties and can potentially be used as a reinforcement agent. The objective of this work was to test the effects of NCC incorporation on the mechanical properties of electrospun polyacrylonitrile (PAN) nanofibers. METHODS: Eleven percent in weight of PAN (molecular weight 150 kD) in a dimethylformamide (DMF) solution was electrospun at 14.6 kV. Nonfunctionalized NCC was added to the solution at 1%, 2%, or 3 wt% (NCC/PAN). Suspensions were mixed and sonicated for 2 h before spinning. Strips (5 × 0.5 cm) were cut from the spun mat, parallel and perpendicular to the rotational direction of the fiber collection drum. Tensile tests were performed, and ultimate tensile strength (UTS), yield strength (YS; 0.3%), elastic modulus (E), and elongation at maximum stress (EMS, %) were calculated from stress-strain plots. Data were analyzed by multiple t tests and one-way ANOVA (α = 0.05). RESULTS: Among all groups, samples with 3 wt % NCC loading had significantly superior mechanical properties. The fiber mats showed anisotropic behavior. CONCLUSIONS: Regardless of concentration, the addition of NCC resulted in increased UTS, E, and YS of the nanofibers.

Circulating biomarkers to identify cardiometabolic complications in patients with Obstructive Sleep Apnea: A systematic review.

Untreated Obstructive sleep apnea (OSA) is associated with an increased risk of cardiometabolic diseases such as diabetes and myocardial infarction. However, it is difficult to predict which patients are at particularly high risk. This systematic review aimed to identify potentially useful circulating biomarkers that could predict cardiometabolic complications in OSA. We searched Cochrane (EBM), EMBASE, Medline, PubMed, and Web of Science databases. Search concepts included: "Obstructive Sleep Apnea", "Biomarkers" and "Risk-Stratification". Manuscripts were included if they studied adults with OSA, circulating (blood) markers, and relationships with clinical outcomes. After screening, 10 were included. Studies addressed cardiovascular disease, type 2 diabetes, end-stage renal disease and metabolic syndrome. In general, levels of inflammatory markers, adhesion molecules, and vascular proteins were associated with the presence of cardiometabolic disease in OSA patients. Although studies regarding prognostic circulating biomarkers in OSA are limited, a number of potentially promising biomarkers were identified in our review. However, more research is needed using prospective cohorts to determine which biomarkers are most robustly associated with and useful in predicting future cardiovascular and metabolic sequelae in OSA patients. Identification of such biomarkers could guide more selective and targeted therapy for OSA in an emerging era of precision-based medicine.

Doxycycline release and antibacterial activity from PMMA/PEO electrospun fiber mats

Abstract Objective: To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen. Methodology: PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis. Results: The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans. Conclusion: The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.

Effect of surface treatment of brackets and mechanical cycling on adhesion to enamel.

This in vitro study sought to evaluate how surface conditioning from bracket and mechanical cycling aging affected the bond strength between metallic brackets and bovine enamel, and to determine the adhesive remnant index. Eighty bovine incisors were embedded in acrylic resin using polyvinyl chloride rings and divided into 4 groups based on surface treatment (n = 20). Group 1 (control) received no surface treatment, Group 2 specimens were sandblasted with aluminum oxide particles, Group 3 specimens were sandblasted with silicon oxide and treated with a tribochemichemical silica coupling agent, and Group 4 specimens were primed with a multidomain protein-based agent. Half of the specimens were submitted to shear bond testing, while the others were subjected to mechanical cycling. ANOVA showed that mechanical cycling did not have a significant influence on bond strength (P = 0.9244), while surface conditioning of the brackets did (P = 0.0001). Tukey's test results were similar for mechanical cycling, and indicated that only Group 3 significantly improved the resin bond to the brackets; however, this group also demonstrated the highest percentage of enamel failure.

Wizard CD Plus and ProTaper Universal: analysis of apical transportation using new software.

OBJECTIVE: This study has two aims: 1) to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2) to compare, with Adobe Photoshop, the ability of a new software (Regeemy) in superposing and subtracting images. MATERIAL AND METHODS: Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature) underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection). Canals were prepared up to F2 (ProTaper) and 24.04 (Wizard CD Plus) instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Student's t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Student's t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time. RESULTS: The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05). ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for image's superposition and subtraction (P>0.05). CONCLUSION: Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop.

Wizard CD Plus and ProTaper Universal: analysis of apical transportation using new software

OBJECTIVE: This study has two aims: 1) to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2) to compare, with Adobe Photoshop, the ability of a new software (Regeemy) in superposing and subtracting images. MATERIAL AND METHODS: Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature) underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection). Canals were prepared up to F2 (ProTaper) and 24.04 (Wizard CD Plus) instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Student's t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Student's t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time. RESULTS: The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05). ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for image's superposition and subtraction (P>0.05). CONCLUSION: Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop. .