• An Assessment of Lip Protrusiveness and Thickness in the Modern African American Patient: A Generational Comparison of Orthodontists

      Battle, Yvette; Pae, Eung-Kwon (2015)
      The goal of this research is to investigate the relationships and dimensions of the most favorable African American lip profile for the 21st century using the professional opinion of 10 experienced versus 10 new generation orthodontists. A comparative ranking of 16 African American profiles, with a focus on lip protrusiveness and thickness will be made among the groups. Results will be converted to measured data using the mixed effects linear regression model. Profiles will be compared to the normative values and esthetics set by prior orthodontic analyses. Because of the changing demographics in the United States and worldwide, orthodontists should be more conscious when using the standardized profile prescriptions and analyses made from and for Caucasians, on the African American patient. A straight profile is not perceived as normal for the African American patient and if so, an adequate level of lip protrusiveness and thickness should be maintained and is essential in the proper esthetics for this group.
    • A clinically relevant viscoelastic FEA model of the mandible simulating the effect of a Herbst appliance

      Heidari Zadi, Zahra; Pae, Eung-Kwon (2018)
      As a powerful numerical solution to partial differential equations with sophisticated boundary conditions, Finite element analysis (FEA) has been vastly used to solve engineering problems. This tool also found to be useful in predicting load-strain patterns and biological failures in mechanics of dental applications as well. In orthodontics field, several studies addressed the benefits in use of FEM models to predict stresses and strains in jaws. These studies mostly considered only the linear elastic phase which corresponds to the immediate response of the bone to the loading during functions. On the other hand, it is the prediction of long-term stress and strain distributions that are useful for clinical purposes. Therefore, it is suggested in this study that the viscoelastic properties of the bone need to be incorporated in the analysis to render long-term stress and displacement patterns. In this research, for the first time to our knowledge, effects of viscoelasticity of the mandibular bone are incorporated into finite element analyses of force distribution and displacement of anatomical structures in response to a Herbst appliance. Our models clearly demonstrate how displacements of the mandible occur in accordance with distributions of force vectors.
    • Genioglossus EMG Activity in Pediatric Obstructive Sleep Apnea Patients

      Chae, Thomas; Pae, Eung-Kwon (2015)
      Obstructive sleep apnea (OSA) is a common condition in childhood and can result in severe complications if left untreated. Genioglossus electromyography (EMG) signals were obtained from ten children during quiet breathing, deep breathing, and maximum protrusion. We expected similar EMG readings during quiet breathing; but when there is increased respiratory drive during deep breathing, EMG recordings should be higher. Moreover, OSA patients fatigue more easily so we expected lower EMG readings during maximum protrusion. The OSA group had quiet breathing EMG signal of 0.192 mV.s (S.D. ±0.92) versus control 0.213 mV.s (S.D. ±0.112). During deep breathing, OSA children had higher EMG signals of 0.532 mV.s (S.D. ±0.317) compared to control 0.218 mV.s (S.D. ±0.096). OSA children had lower genioglossus activity at 0.171 mV.s (S.D. ±0.044) compared to control 0.247 mV.s (S.D. ±0.059). In conclusion, EMG provides an additional tool to differentiate patients with various types of sleep disordered breathing.
    • The Role of Nociceptors in Orthodontic Tooth Movement, Pain, and Alveolar Bone Remodeling

      Elnabawi, Omar; Pae, Eung-Kwon (2018)
      Objective: To determine the effects of selectively ablating transient receptor potential vanilloid 1 (TRPV1)-expressing nociceptors on orthodontic tooth movement, pain, and alveolar bone remodeling. Methods: Resiniferatoxin (RTX) or vehicle was stereotaxically injected into left trigeminal ganglia in adult C57BL/6 mice. After 1 week, orthodontic spring was placed between left maxillary first molar and upper incisors. Pain level was evaluated by measuring mouse grimace scale (MGS) and bite force before and after 1, 3, and 7 days following the procedures. After 12 days, micro-CT was used to quantify tooth movement and analyzing alveolar bone changes. Results: Experimental tooth movement increased MGS scores and decreased bite force. RTX ablation of TRPV1+ nociceptors attenuated MGS scores and relieved the reduction in bite force. The extent of tooth movement was decreased in RTX-treated group, but interradicular alveolar bone volume was not affected. Conclusion: Selective ablation of TRPV1+ nociceptors significantly decreases tooth movement and pain.