Substance P-like immunoreactivity in the pulp-dentine zone of human molar teeth demonstrated by indirect immunofluorescence

Freshly-extracted human third molars were fixed in Zamboni fixative, demineralized with the mixture of EDTA and the fixative; substance P-like immunoreactivity (SPLI) was revealed by the indirect immunofluorescence teachnique of Coons. Substance P (SP) was observed in the pulp-dentine zone and the dental pulp. Some of SP-containing fibres ended at the odontoblast layer and did not reach the predentine; others terminated at the predentine surface or penetrated into the predentine. In the predentine, some of SP fibres accompanied odontoblast processes and ended near the mineralized dentine; others changed course transversely at various levels.     

Effect of bite force on the masseteric electromyographic silent period in man

The duration of the masseteric EMG silent period as induced by tapping on the chin was measured at different levels of sustained bite force. Under both open bite and normal occlusion, the duration of the silent period was inversely related to the magnitude of the bite force. For bite force of the same magnitude, the value of the silent period remained relatively constant for the same subject in different trials (SEM ? 1 per cent), whereas the absolute values of the silent periods ranged far and wide for different individuals even under similar experimental conditions.     

Undergraduate teaching in geriatric dentistry*

Abstract — It is predicted that more Australians will retain their natural dentitions into old age and their dental needs will have to be met with a wide range of dental services by dentists acting with understanding, kindness, and sympathy. The empathy to do so requires experience of appropriate delivery systems in the environment in which the elderly live. For them the ability to eat a balanced and varied diet and to manage personal oral hygiene is very important for their well being. Undergraduate education must be adapted to strengthen the social orientation demanded.     

Platelet responses and anaphylaxis-like shock induced in mice by intravenous injection of whole cells of oral streptococci

Intravenous injection of lyophilized whole cells of various oral streptococcal strains into muramyldipeptide (MDP)-primed C3H/HeN mice induces rapid anaphylactoid shock. Here we examined the mechanism underlying this shock. In non-primed mice, Streptococcus intermedius K-213K (SiK213) and Streptococcus constellatus T21 (ScT21) produced little or no sign of shock. In MDP-primed mice, SiK213 caused lethal shock, while ScT21 only had a weak effect. SiK213 induced decreases in blood platelets and 5-hydroxytryptamine (5HT) preceding the shock, while the effects of ScT21 were weak. The SiK213-induced 5HT decrease and shock were reduced by a complement-C5 inhibitor. These results suggest that (i). streptococcal bacterial cells can induce rapid platelet responses, (ii). complement-dependent degradation of platelets may be involved in streptococcus-induced shock, (iii). the streptococcus-induced platelet degradation or degranulation may occur largely in the systemic circulation, and (iv). platelets may play a role not only in infectious diseases caused by gram-negative bacteria, but also in diseases caused by gram-positive bacteria.