Duration of action of bupivacaine hydrochloride used for palatal sensory nerve block in infant pigs.

Bupivacaine hydrochloride is frequently used in veterinary dental procedures to reduce the amount of general anesthesia needed and to reduce post-procedural pain. The aim of this study was to develop a novel method to test local anesthetic duration in mammals. Six infant pigs were placed under deep/surgical anesthesia with 3 % isoflurane and oxygen while 0.5 ml of 0.5% bupivacaine hydrochloride was injected to block the two greater palatine and the nasopalatine nerves. They were then maintained under light anesthesia with 0.5-1.0% isoflurane. Beginning 15-minutes after the injection, 7 sites in the oral cavity were stimulated using a pointed dental waxing instrument, including 3 sites on the hard palate. The response, or lack of response, to the stimulus was recorded on video and in written record The bupivacaine hydrochloride injections lasted 1 to 3-hours before the animals responded to the sensory stimulation with a reflexive movement This study provides evidence that bupivacaine used to anesthetize the hard palate has a relatively short and variable duration of action far below what is expected based on its pharmacokinetic properties.

U.S. dental students' attitudes toward research and science: impact of research experience.

This study aimed to provide a first nationwide assessment of dental students' attitudes toward the importance of research and its integration into the dental curriculum. For this purpose, the American Association for Dental Research National Student Research Group developed an online survey that was distributed to 89 percent of U.S. dental students in May 2012. The survey consisted of twenty-one Likert-type items divided into three groups: importance of research in dentistry, barriers to research involvement, and exposure to research in the dental curriculum. There were 733 responses (3.9 percent response rate), including students in all stages of education representing fifty-eight out of sixty-one dental schools. Age and race/ethnic distributions corresponded with U.S. dental school enrollees. Results showed that 63 percent of respondents had conducted research before matriculation, and of the 34 percent that participated in research during dental school, only 27 percent were newcomers. Respondents strongly agreed that scientific research enabled their progress in dentistry. Inadequate time in the curriculum was an obstacle they perceived to research involvement during dental school. Respondents agreed that dental curricula emphasize evidence-based practices but may be inadequately teaching biostatistics and research methodologies. Students with research experience tended to have stronger positive opinions about the importance of research in dental education. Efforts to foster research in schools have been well received by students, but several issues remain for enriching dental education through greater involvement of students in research.

Sucking and swallowing rates after palatal anesthesia: an electromyographic study in infant pigs.

Infant mammalian feeding consists of rhythmic suck cycles and reflexive pharyngeal swallows. Although we know how oropharyngeal sensation influences the initiation and frequency of suck and swallow cycles, the role of palatal sensation is unknown. We implanted EMG electrodes into the mylohyoid muscle, a muscle active during suckling, and the thyrohyoid muscle, a muscle active during swallowing, in eight infant pigs. Pigs were then bottle-fed while lateral videofluoroscopy was simultaneously recorded from the electrodes. Two treatments were administered prior to feeding and compared with control feedings: 1) palatal anesthesia (0.5% bupivacaine hydrochloride), and 2) palatal saline. Using the timing of mylohyoid muscle and thyrohyoid muscle activity, we tested for differences between treatment and control feedings for swallowing frequency and suck cycle duration. Following palatal anesthesia, four pigs could not suck and exhibited excessive jaw movement. We categorized the four pigs that could suck after palatal anesthesia as group A, and those who could not as group B. Group A had no significant change in suck cycle duration and a higher swallowing frequency after palatal saline (P = 0.021). Group B had significantly longer suck cycles after palatal anesthesia (P < 0.001) and a slower swallowing frequency (P < 0.001). Swallowing frequency may be a way to predict group membership, since it was different in control feedings between groups (P < 0.001). The qualitative and bimodal group response to palatal anesthesia may reflect a developmental difference. This study demonstrates that palatal sensation is involved in the initiation and frequency of suck and swallow cycles in infant feeding.

Development, reliability, and validation of an infant mammalian penetration-aspiration scale.

A penetration-aspiration scale exists for assessing airway protection in adult videofluoroscopy and fiberoptic endoscopic swallowing studies; however, no such scale exists for animal models. The aim of this study was threefold: (1) develop a penetration-aspiration scale (PAS) for infant mammals, (2) test the scale's intra- and interrater reliabilities, and (3) validate the use of the scale for distinguishing between abnormal and normal animals. After discussion and reviewing many videos, the result was a 7-point infant mammal PAS. Reliability was tested by having five judges score 90 swallows recorded with videofluoroscopy across two time points. In these videos, the frame rate was either 30 or 60 frames per second and the animals were either normal, had a unilateral superior laryngeal nerve (SLN) lesion, or had hard palate local anesthesia. The scale was validated by having one judge score videos of both normal and SLN lesioned pigs and testing the difference using a t test. Raters had a high intrarater reliability [average κ = 0.82, intraclass correlation coefficient (ICC) = 0.92] and high interrater reliability (average κ = 0.68, ICC = 0.66). There was a significant difference in reliability for videos captured at 30 and 60 frames per second for scores of 3 and 7 (P < 0.001). The scale was also validated for distinguishing between normal and abnormal pigs (P < 0.001). Given the increasing number of animal studies using videofluoroscopy to study dysphagia, this scale provides a valid and reliable measure of airway protection during swallowing in infant pigs that will give these animal models increased translational significance.

Regional variation in geniohyoid muscle strain during suckling in the infant pig.

The geniohyoid muscle (GH) is a critical suprahyoid muscle in most mammalian oropharyngeal motor activities. We used sonomicrometry to evaluate regional strain (i.e., changes in length) in the muscle origin, belly, and insertion during suckling in infant pigs, and compared the results to existing information on strain heterogeneity in the hyoid musculature. We tested the hypothesis that during rhythmic activity, the GH shows regional variation in muscle strain. We used sonomicrometry transducer pairs to divide the muscle into three regions from anterior to posterior. The results showed differences in strain among the regions within a feeding cycle; however, no region consistently shortened or lengthened over the course of a cycle. Moreover, regional strain patterns were not correlated with timing of the suck cycles, neither (1) relative to a swallow cycle (before or after) nor (2) to the time in feeding sequence (early or late). We also found a tight relationship between muscle activity and muscle strain, however, the relative timing of muscle activity and muscle strain was different in some muscle regions and between individuals. A dissection of the C1 innervations of the geniohyoid showed that there are between one and three branches entering the muscle, possibly explaining the variation seen in regional activity and strain. In combination, our findings suggest that regional heterogeneity in muscle strain during patterned suckling behavior functions to stabilize the hyoid bone, whereas the predictable regional strain differences in reflexive behaviors may be necessary for faster and higher amplitude movements of the hyoid bone.