Motor control of velopharyngeal structures during vowel production

This investigation was designed to measure the ability of normal adult speakers to exert voluntary control over velopharyngeal positioning. Speakers were asked to phonate the vowels [a] and [i] at 50 percent and 75 percent of complete velopharyngeal closure, using visual feedback of velopharyngeal opening and closing gestures from a phototransducer. The musculature of the velopharyngeal mechanism was hypothesized to act as a coordinated system that may demonstrate both motor flexibility and plasticity (Folkins, 1985) when forced to function in a novel way. Evidence of both motor system responses to a novel speaking condition was observed. Speakers were able either to phonate at intermediate closure levels without having to learn new motor rules, or to learn new rules for velopharyngeal muscle activation that resulted in the ability over time to position the velopharyngeal mechanism appropriately. As such, support is derived for the notion (Folkins, 1985) that speakers develop motor rules or coordinative structures involving the velopharyngeal mechanism that govern velopharyngeal movement. The characteristics of this coordinative structure framework has not yet been described, however, and are the subject of ongoing research efforts.     

Microcomputer use in an oral biopsy service

The need for rapid and accurate retrieval of the data generated by an oral biopsy service and the adjacent medical center was met with the purchase and programming of a microcomputer and hard disk drive. The planning phase involved an assessment of the needs of the department, creation of an ideal form to be displayed on the video screen that can be easily used to enter the information, selection of coding systems, and selection of compatible hardware and software. Customized in-house programming using a commercially available database management system has created an entry form and menu-driven information retrieval system tailored to the needs of the department.     

Imaging artificial caries on the occlusal surfaces with polarization-sensitive optical coherence tomography

Polarization-sensitive optical coherence tomography (PS-OCT) is a nondestructive imaging system that can utilize near-infrared (IR) light to produce depth-resolved images of dental enamel and has the potential to monitor early enamel occlusal caries. The objective of this study was to investigate the relationship between the magnitude of backscattered light and depolarization recorded by PS-OCT with changes in the enamel mineral volume in an artificial caries model. Artificial lesions were created on a selected region on the occlusal surfaces of sound posterior teeth (n=10) using a well-characterized 14-day pH cycling model. An all-fiber-based PS-OCT system operating at 1,310 nm was used to collect serial images at day 0 and day 14 prior to tooth sectioning. The quantitative mineral content profile and relative mineral loss, DeltaZ (%volxmicrom), of the carious enamel samples were obtained from transverse sections using high-resolution digital microradiography (DM). Line profiles of PS-OCT and DM images were used to evaluate the artificial caries severity and depth. The integrated reflectivity of the perpendicular-axis PS-OCT image, quantifying lesion severity, was correlated to the DeltaZ of the caries lesions. There was also a strong correlation between the lesion depth calculated from both imaging modalities. PS-OCT can image and quantify artificial occlusal caries by measuring the increase in backscattering and depolarization of near-IR light. This optical method has promising applications for in vivo detection and monitoring of early enamel occlusal caries.