Faculty Bibliography

Injury to peripheral dental tissues evokes dynamic alternations in central sensory pathways. We have previously reported that transient stimulation of the dental pulp with noxious heat evokes the induction of the immediate early gene product Fos in the transitional region between subnucleus interpolaris and caudalis (Vi/Vc) and subnucleus caudalis (Vc). A question arises as to whether similar changes occur in response to inflammation to the tooth pulp. In this study, the effects of pulpal inflammation produced by bacterial lipopolysaccharide (LPS) on face-grooming behavior and trigeminal Fos expression were examined. Face-grooming behaviors were recorded daily for 3 days pre- and 24, 48 and 72 h post- LPS or saline application. All animals were perfused 72 h post- LPS or saline application. Brainstems were processed for Fos-like immunoreactivity (Fos-LI). Teeth were processed for H&E staining. Histological examination of LPS-treated teeth revealed features of an acute pulpitis. Moreover, LPS-treated animals showed greater face-grooming activity (i.e. tongue protrusions) directed to the injured tooth than the sham-operated group. The number of Fos-positive neurons was greater in the trigeminal subnucleus caudalis (Vc) and the transitional regions (Vi/Vc) in LPS-treated animals compared with sham-operated animals, and greater in the deeper laminae than the superficial laminae of each trigeminal region. LPS treatment did not evoke Fos expression in the rostral trigeminal regions above Vi/Vc. These results demonstrate that LPS-induced pulpal inflammation results in significant alterations in the Vi/Vc and Vc, and such changes may underlie the observed nociceptive behavioral responses and may play an important role in producing a symptomatic pulpitis in humans.

Previously reported differences in sensitivity to experimental pain stimuli between the sexes, as well as between temporomandibular disorder (TMD) patients and healthy control subjects, may be attributable in part to group differences in two pain modulatory mechanisms: the baroreceptor reflex arc and the endogenous opioid system. Twenty-two pain-free (PF) men, 20 PF women and 20 women with TMD underwent two testing sessions in which heat pain and ischemic arm pain threshold and tolerance were measured during both sessions, but followed relaxation during one session and laboratory stress tasks during the other. Blood pressure (BP) and plasma -endorphin (E) concentration were measured during a baseline rest and during the stress or relaxation periods. PF men's threshold and tolerance for heat pain, but not for ischemic pain, exceeded that of PF women's during both sessions. PF women and TMD women did not differ in sensitivity to either pain modality; however, significantly lower ischemic pain threshold (IPTh) was linked to oral contraceptive use in PF women but not TMD patients. In the men alone, higher baseline systolic BP (SBP) was correlated with higher heat pain threshold on both days and heat pain tolerance on the stress day. Conversely, in TMD women, higher baseline SBP was correlated with lower ischemic pain tolerance (IPTol) on both days; BP and pain sensitivity were not related in PF women. In men, but not in PF or TMD women, stress systolic and diastolic BP were positively correlated with heat pain threshold and tolerance and higher diastolic reactivity to stress were correlated with higher heat pain and IPTh and tolerance. On the stress day, higher baseline E level was strongly associated with higher IPTol in PF women but marginally associated with lower IPTol in TMD women. Thus, it appears that a BP-related analgesic mechanism (probably baroreceptor-mediated) predominates in PF men, while an endogenous opioid mechanism predominates in PF women. Stress enhances the expression of these central mechanisms. Female TMDs appear unable to effectively engage normal pain-inhibitory systems; opioid receptor desensitization and/or downregulation are probably implicated, because TMDs' production of E appears normal.

PURPOSE: Dental injuries can be permanent and disfiguring. They are also universally expensive to treat. Many dentists, sports physicians, and athletic trainers recommend mouthguards for athletes participating in certain competitive sports, including men's college basketball, because of a common perception that mouthguards afford protection from dental injuries, and even some concussions. However, there are few reliable reports of the incidence of dental injuries and concussions in men's college basketball, and good evidence that mouthguards reduce the risk of these injuries in this population of athletes is notably lacking. This study prospectively recorded dental injuries and concussions among 50 men's Division I college basketball teams during one competitive season, then compared injury rates between mouthguard users and nonusers. METHODS: During the 1999 to 2000 basketball season, athletic trainers from 50 men's Division I college basketball programs used an Internet Web site to submit weekly reports of the number of athlete exposures, mouthguard users, concussions, oral soft tissue injuries, dental injuries, and dentist referrals. RESULTS: Response rate was 86%. There were 70,936 athlete exposures. Athletes using custom-fitted mouthguards accounted for 8663 exposures. Injury rates were expressed as number of injuries per 1000 athlete exposures. There were no significant differences between mouthguard users and nonusers in rates of concussions (0.35 vs 0.55) or oral soft tissue injuries (0.69 vs 1.06). Mouthguard users had significantly lower rates of dental injuries (0.12 vs 0.67; P < 0.05) and dentist referrals (0.00 vs 0.72; P < 0.05) than nonusers. CONCLUSION: Custom-fitted mouthguards do not significantly affect rates of concussions or oral soft tissue injuries, but can significantly reduce the morbidity and expense resulting from dental injuries in men's Division I college basketball.

Laser Doppler Flowmetry (LDF) has been shown to be valuable in monitoring revascularization of immature incisors following severe dental trauma. Several investigators have demonstrated the ability of LDF to record blood flow signals from vital tooth pulps. In this case report, LDF was used for a 7-year-old child patient following a severe luxation of tooth #9. During follow-up examinations the traumatized tooth was unresponsive to traditional vitality testing during the first 6 months; however, LDF indicated that revascularization had occurred much sooner. Until recently, CO2 ice has been the most effective method for sensitivity testing in trauma cases such as presented here. In this case, LDF gave us the assurance that we could defer invasive care during a critical time period when root canal therapy might have been initiated for this child patient.