Effect of serotonin (5-HT) on trigeminal rhythmic activities generated in in vitro brainstem block preparations

We used rat isolated brainstem block preparations to analyze the functional roles of serotonin receptors in the generation of trigeminal rhythmic activities. We previously reported that trigeminal rhythmic activities could be induced by some pharmacological applications in an isolated brainstem preparation with a rostral boundary at the border between the inferior and superior colliculus, and a caudal border at the level of the rostral facial nucleus. However, the same stimulation did not induce trigeminal rhythmic activities in a whole brainstem block preparation with the same rostral boundary and a caudal border at the obex level. In the present study, both the 5-HT(1A) phthalimido-butyl-piperazine, and the 5-HT(2C) agonist, 1-2,5-dimethoxy-4-iodophenyl-2-aminopropane, combined with N-methyl-D,L-aspartate and bicuculline, elicited trigeminal rhythmic activities in a whole brainstem block preparation. Our results suggest that serotonin has both facilitation and inhibition effects on the generation of trigeminal rhythmic activities in an isolated brainstem block preparation in vitro.     

Bond strength between luting materials and a fiber-reinforced resin composite for indirect restorations

The purpose of the present study was to evaluate the bond strength between a fiber-reinforced composite (FRC) and six luting agents (Panavia F 2.0, Linkmax MC, Chemiace II, Multibond, Super-Bond C&B, and Fuji I). A prosthodontic resin composite material (RC-control) and a luting agent containing no functional monomer (MT) were used as controls. Shear bond strengths between alumina-blasted FRC and the luting agents were determined after 20,000 thermocycles. The FRC showed superior bond strength when compared with the RC-control. Highest bond strengths were achieved when FRC was bonded with Panavia F 2.0, Linkmax MC, Multibond, Super-Bond C&B, and MT, whereas Chemiace II trailed in the list of resin-based luting agents evaluated. Insufficient bonding was obtained with Fuji I. Results of the present study revealed that when fabricating restorations, the clinician should select an appropriate combination of resin composite material and luting agent so as to ensure the longevity of restorations.     

Distribution of movement-related cortical potential upon jaw-biting in humans

We examined the cerebral location of the readiness potential (hereinafter referred to as "RP") upon activation of the masseter muscle by voluntary and unilateral jaw-biting movement. Four normal adults served as subjects. Five scalp electrodes were placed according to the international 10-20 method at CZ, C3, C4, T3 and T4. In addition, in one of the subjects, RPs were recorded by 12 scalp electrodes in order to study changes occurring in the distribution of RPs with time. The maximum amplitude of the RP was located at T4 in the temporal area, which was involved in the biting movement as a negative slow potential occurring 1.4-0.8 s before the beginning of the discharge to the masseter muscle. The maximum amplitude of the RP on the contralateral side was located at T3. This meant that the amplitude of the RP tended to be higher on the same side as the biting movement than on the contralateral side in all subjects. From scalp topography, the maximum amplitude of the RP was shown to be confined to T4, and was especially marked immediately before the beginning of discharge to the masseter muscle. From these results it is thought that in the case of voluntary biting movement, the RP reflects activities of the pyramidal cells in the masticatory area of the cortex, and that strong descending impulses from both sides then reach the masseter muscles.     

Effect of the methyl methacrylate-tributylborane sealant in preventing occlusal caries.

A newly developed pit and fissure sealant, named Enamite, was studied technologically and clinically. Major ingredients of the sealant are a solution of 3% 2-hydroxy-3-beta-naphthoxypropyl methacrylate in methyl methacrylate and poly (methyl methacrylate) powder, using tributylborane as an initiator. In comparison with other commercially available sealants, Enamite showed much greater adhesiveness to enamel, which was confirmed by scanning electron micrographic observations. The sealant was applied to 161 first molars in 99 children, aged 6-8 years, to determine the caries preventive as well as the caries retardation effect. Among the treated teeth, 98 were intact and the remaining had incipient caries. The right side teeth of each subject was assigned to the test side and the other side served as a control. Each child was evaluated every 6 months by clinical exploration and bite-wing X-ray survey. At the final examination, the electric conductivity test was also used for the caries detection. After 2 years the sealant was effective in preventing 57.1% of the occlusal caries on treated compared with control teeth. When evaluation was made by including the caries retardation effect--teeth initially carious but remaining sealed after 2 years were counted as effective--, the sealant was effective in preventing or retarding 96.3% of the occlusal caries.     

Sternocleidomastoid myocutaneous flap for intraoral reconstruction after resection of oral squamous cell carcinoma.

PURPOSE: The sternocleidomastoid (SCM) myocutaneous flap remains an important tool in head and neck reconstruction. This article retrospectively reviews 40 consecutive SCM myocutaneous flaps used for the reconstruction after resection of oral squamous cell carcinoma with respect to reliability and complications. PATIENTS: From 1987 to 1997, 40 patients underwent SCM myocutaneous flap reconstruction of the oral cavity. The age and gender of the patients, site of primary tumor TNM stage, type of associated operation, and clinical course were analyzed. RESULTS: In 8 cases, partial epithelial loss over the skin paddle occurred with survival of the muscle and at least some of the dermis. Unilateral supraomohyoid neck dissection (SND) was performed in 11 cases, and unilateral functional neck dissection, which preserves SCM and/or internal jugular vein and/or accessory nerve, in 16 cases. Pathologically positive nodes were recognized in 14 of these 27 neck dissection cases; in 11 of these 14 cases, the neck lesion was controlled. CONCLUSION: The SCM myocutaneous flap appears to be simple to use and useful for reconstruction of the defect after resection of oral carcinoma, and the indications for this flap will be extended in accordance with the recent increases in the number of supraomohyoid and functional neck dissection cases.     

Influence of proinflammatory cytokines on Actinobacillus actinomycetemcomitans specific IgG responses

OBJECTIVE: High levels of serum anti-Actinobacillus actinomycetemcomitans immunoglobulin G (IgG) correlate with reduced extent and severity of periodontal disease and the present study was undertaken to begin testing the hypothesis that proinflammatory cytokines are important in the induction of optimal anti-A. actinomycetemcomitans IgG responses. BACKGROUND: Studies with pokeweed mitogen indicate that interleukin-1alpha (IL-1alpha) and IL-1beta are necessary for optimal IgG1 and IgG2 production and that prostaglandin E(2) (PGE(2)) and interferon-gamma (IFN-gamma) selectively promote IgG2, which is a major component of the anti-A. actinomycetemcomitans response in vivo. The pokeweed mitogen results suggest that these proinflammatory cytokines would also be necessary for optimal production of IgG specific for A. actinomycetemcomitans. METHODS: Peripheral blood mononuclear cells from A. actinomycetemcomitans-seropositive subjects with localized aggressive periodontitis were stimulated with A. actinomycetemcomitans in immune complexes capable of binding follicular dendritic cells that participate in the induction of recall responses in vivo. Cultures were manipulated with anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21, indomethacin, and PGE(2). Actinobacillus actinomycetemcomitans specific IgG production was monitored by enzyme-linked immunosorbent assay (ELISA). RESULTS: Addition of follicular dendritic cells to peripheral blood mononuclear cells cultures resulted in follicular dendritic cell-lymphocyte clusters and increased anti-A. actinomycetemcomitans IgG responses (3-40-fold increases) compared with controls lacking follicular dendritic cells. Anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21 and indomethacin suppressed anti-A. actinomycetemcomitans IgG production by half or more. PGE(2) restored IgG responses suppressed by indomethacin. CONCLUSIONS: The cytokines IL-1alpha, IL-1beta, IFN-gamma, IL-12, and PGE(2) were all necessary for optimal production of human anti-A. actinomycetemcomitans and the need for proinflammatory cytokines including the T helper 1 (Th1) cytokines is consistent with a response with a significant IgG2 component.