Effect of Real-Time Environment on Mechanical Properties of Preformed Stainless Steel Archwires: An In Vivo Study.

Introduction: Clinicians should be aware of any effect the oral environment may have on archwires. Laboratory models fail to closely imitate intraoral conditions. The aim was to evaluate the change in mechanical properties of preformed stainless steel archwires after 15 weeks of exposure to the oral environment. Methods: Three commercially manufactured 0.019 × 0.025″ stainless steel archwires were evaluated. Young's modulus, yield strength, spring factor, and hardness were studied. The unexposed distal end cuts (control samples) and archwires were tested after 15 weeks of intraoral exposure (test samples). Tension tests, Vickers microhardness tests, and nanoindentation tests were carried out. Results: Normality was tested using the Shapiro-Wilk test. Statistical analyses included the paired t-test for intragroup comparisons and Kruskal-Wallis ANOVA with the post hoc Dunn test for comparison of mean percentage reduction in values. At T15, Young's modulus showed a statistically significant decrease. Changes in yield strength and spring factor were not significant for groups other than American Orthodontics wires. The reduction in hardness was significant in 3M Unitek. Vickers, tension, and nanoindentation tests demonstrated an expansive range between hardness and Young's modulus so determined. Conclusion: 3M Unitek archwires showed the highest difference in Young's modulus. Yield strength values increased in Ortho Organizers archwires. Spring factor decreased only in 3M Unitek archwires. Hardness values obtained from various tests did not produce identical results.

Fluorescence and Photoacoustic Spectroscopy-Based Assessment of Mitochondrial Dysfunction in Oral Cancer Together with Machine Learning: A Pilot Study.

The current study reports an integrated approach of machine learning and tryptophan fluorescence and photoacoustic spectral properties to assess the mitochondrial status under oral pathological conditions. The mitochondria in the study were isolated from oral cancer tissues and adjacent normal counterparts, and the corresponding fluorescence and photoacoustic spectra of tryptophan were recorded at 281 nm pulsed laser excitations. A set of features were selected from the pre-processed spectra and were used to classify the data using support vector machine (SVM) learning in the MATLAB platform. SVM analysis demonstrated clear differentiation between mitochondria isolated from normal and cancer tissues for fluorescence (sensitivity, 86.6%; specificity, 90%) and photoacoustic (sensitivity, 86.6%; specificity, 96.6%) measurements. Further investigation into the influence of change in protein conformation on the nature of tryptophan spectral properties was evaluated by 8-anilino-1-naphthalene sulfonic acid (ANS) fluorescence assay. The impact of protein structural changes on the mitochondrial functions was also estimated by mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and cytochrome c oxidase (COX) assays, suggesting an altered mitochondrial function. The findings indicate that tryptophan fluorescence and photoacoustic spectral properties together with machine learning algorithms may delineate the mitochondrial functional status in vitro, indicating its translational potential.

Lip profile changes in patients with Class II Division 1 malocclusion of varied growth patterns treated with maxillary premolar extractions: A pilot study.

INTRODUCTION: This retrospective pilot study assessed the pre- and posttreatment lip profile changes among adult patients with Class II Division 1 malocclusion of varied growth patterns and compared these changes with patients with a skeletal Class I relationship, to identify the dental, skeletal, and soft tissue cephalometric variables that altered the posttreatment lip profile. METHODS: A total of 33 digital cephalograms were divided into 4 study groups based on the mandibular plane (Mp-SN) angle: group 1 (control, skeletal Class I; mean angle = 21.5°) (n = 8), group 2 (Class II Division 1 malocclusion; low angle = <26°) (n = 8), group 3 (Class II Division 1 malocclusion; intermediate angle = 26°-38°) (n = 9), and group 4 (Class II Division 1 malocclusion; high angle = >38°) (n = 8). RESULTS: We observed a significant decrease in SNA, ANB, maxillary incisor to NA (degrees and millimeters), and soft tissue parameters, especially lip strain and lower lip to E line and upper lip to E line. Posttreatment intergroup comparison showed a significant increase of Mp-SN, and this increase was greater in group 3, followed by group 4 as compared with group 1. In addition, statistically significant differences in SNA, ANB, mandibular incisor to NB (degrees) and IMPA, and H angle in groups 2-4 were observed. CONCLUSIONS: Patients with Class II Division 1 malocclusion showed a significant decrease in SNA, ANB, maxillary incisor to NA, and all soft tissue parameters in posttreatment compared with group 1. Thus, the soft tissue changes resulted in a similar profile to patients in group 1, who are considered to have an aesthetically pleasing posttreatment profile.