Alignment efficiency of heat activated and superelastic nickel-titanium archwires in orthodontic patients over three months: A Single-center, randomized clinical trial.

OBJECTIVE: The aim of this 2-arm parallel study was to evaluate the alignment efficiency of heat-activated nickel-titanium (NiTi-TE) and superelastic nickel titanium (NiTi-PSE) archwires over the first 3 months of orthodontic treatment and compare these groups. SETTING AND SAMPLE POPULATION: Randomized, double-blind, controlled, single-center trial in 52 patients with fixed orthodontic appliances from an orthodontic graduate program in the permanent dentition and moderate crowding in the lower arch. MATERIAL AND METHODS: Patients were randomly allocated to one of two interventions: NiTi-TE and NiTi-PSE archwires, 0.014-inch (3M Unitek™, CA, USA) with a follow-up period of 3 months. The primary outcome was the alignment efficiency determined by the reduction in Little's irregularity index (mm), measured in three points, T0: before the start of orthodontic treatment, T1: 1 month later, T2: 2 months later, T3: 3 months later. Data were analyzed using independent sample t tests and repeated measures ANOVA. RESULTS: 52 patients (NiTi-TE n = 26; NiTi-PSE n = 26) were randomized and analyzed (average age: 21.73; standard deviation (SD): 6.07; average lower anterior irregularity: 5.20; SD: 0.76) for intention-to-treat (ITT) analysis. No statistically significant differences between the groups were found (mean of the differences: T1: 0.20; 95% CI: -0.558; 0.958; T2: 0.49: 95% CI: -0.339; 1.319; T3: 0.33; 95% CI: -0.308; 0.968). The resolution of crowding with each of the wires was significant (P < 0.0001) at all times. Twelve participants (2 treated with NiTi-TE and 10 treated with NiTi-PSE) lost follow-up due to face-to-face dental-procedures restrictions during the COVID-19 pandemic, the missing data was imputed. CONCLUSIONS: NiTi-TE and NiTi-PSE wires of 0.014-inch were similar in their clinical efficiency for the resolution of crowding during the first 3 months of orthodontic treatment. REGISTRATION: Clinical Trials NCT03256279.

Age differences in relation to bone thickness and length of the zygomatic process of the maxilla, infrazygomatic crest, and buccal shelf area.

INTRODUCTION: The purpose of this study was to compare the thickness and length of the zygomatic process (ZP) of the maxilla, infrazygomatic crest area, and mandibular buccal shelf by sex and age. METHODS: Cone-beam computed tomography images of 128 subjects were divided into 3 groups: (1) 22 female and 19 male subjects aged 9-13 years, (2) 27 female and 20 male subjects aged 14-23 years, and (3) 20 female and 20 male subjects aged 24-50 years. A previously calibrated operator was used to take all measurements of the zygomatic process vertical bone thickness, zygomatic process horizontal bone length, zygomatic process/cementoenamel length (ZP/CEJL), infrazygomatic crest region bone thickness (IZCBT), infrazygomatic crest region bone length (IZCL), and mandibular buccal shelf bone thickness. Analysis of variance and Kruskal-Wallis tests were used for statistical analyses. Two-way analysis of variance was used for variables with significant differences by sex (P <0.002 as determined by Bonferroni correction for multiple comparisons). RESULTS: Differences by sex were only found for IZCL in the maxillary second premolar and first molar (U5-U6) and the maxillary first molar (U6). Significant differences were observed among age groups for ZP/CEJL, IZCBT in U5-U6 and U6, and IZCL in U6-distal. CONCLUSIONS: The results suggest that ZP/CEJL and IZCL are larger in adults than in younger subjects, whereas IZCBT is smaller in adults than in younger subjects.

Ventilation and air-conditioning systems in dental clinics and COVID-19: How much do we know?

BACKGROUND: This study evaluated the association between knowledge and management of ventilation and air-conditioning systems (VAC) to avoid the spread of the SARS-CoV-2 virus in health facilities by dentists and demographic variables. MATERIAL AND METHODS: A cross-sectional digital media survey was administered to dentists as part of global research. The core questionnaire was used including four additional questions on VAC (Q1: knowledge, Q2: work settings, Q3: temperature, and Q4: maintenance). A descriptive analysis was conducted for sociodemographic and VAC variables, and bivariate analysis was carried out using different tests. RESULTS: 5370 dentists answered the survey (median age of 45 years; 72.22% women). About half of the respondents said that they knew about the guidelines issued for the management of air conditioners (AC) during the pandemic, and 16.77% have made modifications to their VAC systems during this period. The most frequent AC temperature range used in the dentists' offices during the pandemic was 18°C to 20°C. As age increased, self-reported knowledge about VAC guidelines expanded. Remote and rural regions were perceived to have less knowledge of the guidelines. CONCLUSIONS: Although perceptions of knowledge about VAC systems during the COVID-19 pandemic was high, the temperature in dental offices was colder than that recommended. Greater disclosure of VAC management practices and adherence to VAC management guidelines are required. Key words:Air conditioning, dentistry, coronavirus.

Changes in the mechanical properties of two nickel-titanium archwires after 3 months of clinical usage.

BACKGROUND: Nickel-titanium archwires have unique mechanical properties that make them the archwire of choice during the first phase of orthodontic treatment. However, during its clinical use when subjected to oral conditions, these properties can undergo great changes. MATERIALS AND METHODS: A sample of 24 randomly chosen superelastic NiTi orthodontic archwires (12 TE and 12 PSE) with a 0.014-inch round section from the same manufacturer were distributed into four groups of six archwires each. The first two groups were new wires (as-received), which were used as controls (T0), and the other two were collected after 3 months of clinical usage (as-retrieved) in orthodontic patients (T1). Mechanical properties were measured by mechanical tensile testing and three-point bending tests under the same experimental and temperature conditions (36°C) in a universal testing machine. Comparisons between the groups at T0 and T1 were performed with t-tests and Mann-Whitney U tests. A paired t-test and Wilcoxon signed rank sum test were used for intragroup comparisons (T1-T0). RESULTS: At baseline, PSE wires presented significantly (P < 0.05) higher load at fracture, range, ultimate tensile strength (UTS), yield strength, springback, maximum tension and flexural ultimate strength (FUS) than those of TE wires. At T1, a significant decrease in load at fracture and UTS in PSE wires and in FUS in TE wires was found. After 3 months of clinical usage, the changes (T1-T0) in the mechanical properties of both alloys were similar. CONCLUSIONS: After 3 months of clinical usage, wires lost some of their mechanical properties and had less resistance to breakage. However, the as-received differences between both wires were maintained after clinical usage.