Electron microscopy of cells displaced into the dentinal tubules due to dry cavity preparation.

Using dogs' teeth, cells displaced into the dentinal tubules due to dry cavity preparation were observed using electron microscopy. In order to obtain adequate fixation a new local-perfusion method was employed. Most of the cells which moved into the dentinal tubules were odontoblast nuclei and partly neutrophilic leukocytes and erythrocytes. Not only odontoblast nuclei but also cytoplasmic organelles, such as mitochondria, rough endoplasmic reticulum, free ribosomes, and lysosomes were displaced into the tubules. The weavings of dentinal fibers in the tubules were observed in some areas.     

The role of xeroradiography in cephalometric radiology.

The advantages of xeroradiography in the precise identification of anatomical landmarks for orthodontic analysis are overwhelming. In addition, the soft tissues of the face are shown fully and in detail. The tongue and soft palate can also be visualized. However, there is undue anxiety among clinicians and radiologists about the risk of excessive radiation exposure to patients. This has hitherto been regarded as unavoidable for the purposes of xeroradiography.This paper sets out in detail the advantages of xeroradiography for cephalometry and also clarifies the problem of patient exposure by presenting detailed measurements of the parameters affecting exposure and of the incident skin exposure. In this way it can be shown that by choice of correct kilovoltage and adequate filtration the incident skin exposure can actually be reduced when compared with conventional techniques using film.     

Experimental transient bacteraemias in human subjects with varying degrees of plaque accumulation and gingival inflammation

Ninety-six subjects were assigned to one of four groups according to severity of gingival inflammation and bacterial plaque accumulation on the teeth. Following a standardized toothbrushing procedure, blood specimens from a vein in the antecubital fossa were cultured under aerobic and stringent anaerobic conditions. The percentage of positive cultures increased significantly with increasing severity of gingival inflammation, as did the number of species of organisms isolated. Thirty different microbial species indigenous to the oral cavity, including many strict anaerobes, were recovered. The study has implications for standards of oral health which might be considered necessary in patients with congenital or acquired endocardial defects or cardiovascular prostheses.     

The effect of the bite plane splint on the electromyographic silent period duration

An electromyographic study of the masseter and anterior part of the temporalis muscles was performed on ten patients presenting temporomandibular joint dysfunction symptoms. The EMG silent periods (SP) produced in the open-close-clench cycle and jaw-jerk reflex were compared for duration before and after treatment with an occlusal bite splint. Following use of the splint, there was a shortening of SP indicating the possible use of the duration of SP as a diagnostic measurement, and also as an indication of treatment effectiveness.