Quantitative description of temporomandibular joint sounds: defining clicking, popping, egg shell crackling and footsteps on gravel.

This study presents a quantitative description of temporomandibular joint (TMJ) sounds provided by a rule-based classification system based on sound classification by three dentists, who listened to and classified the sound recordings as no sound, click, coarse crepitus and fine crepitus. The sounds were recorded with microphones in the ear canal from 126 subjects during vertical opening, digitized at 15 000 Hz, and replayed using a computer sound card and speakers. The dentists' classification of a test set resulted in intra- and inter-tester j values ranging from 0.71 to 0.81 and 0.61-0.73, respectively. Pooled j values for the dentists and the dentists plus the rules were 0.67 and 0.58, respectively, which were not significantly different in terms of the sound features on which the rules were based (P = 0.13). Linear discriminant analysis showed the four TMJ sound types were significantly different (P < 0.001). The performance of the rules was equivalent to the dentists and marginally better than the linear discriminant functions (P = 0.08), establishing the validity of the quantitative descriptions they provide. The recording and rebroadcast methodology produced sounds very similar to those observed in the clinic and could be used to train clinicians in classifying TMJ sounds.

Toxicity testing of sealants: a tissue implant study.

The toxicity of pit and fisure sealants implanted into the subcutaneous tissues of guinea pigs was tested using the protocol for toxicity testing derived from the ADA/ANSI Document No. 41, 1982. The materials tested were Delton autopolymerized and photopolymerized, and Concise White autopolymerized and photopolymerized. After two weeks, reactive fibrosis and mild to moderately severe foreign body reactions were noted. After 12 weeks, only thin fibrous walls infiltrated occasionally by small numbers of chronic inflammatory cells were observed. The results of this investigation appear to indicate that following subcutaneous implantation of a pit and fissure sealant, a foreign body reaction will most likely take place during the first two weeks, but will be resolved by 12 weeks. Furthermore, than an initial reactive fibrosis will give way to a thin fibrosis wall by 12 weeks, and the initial inflammatory response will subside. It can also be stated that in this study, Delton and Concise White sealant materials produced similar tissue reactions, and that there were few differences between materials which were autopolymerized or photopolymerized.

Noradrenalin-inducible cyclic-AMP accumulation in rat cerebral cortex: changes during complete global ischemia.

Neurologic dysfunction after cerebral ischemic insults may be due not only to neuronal death, but also to a possibly reversible failure in synaptic transmission. Because noradrenaline (NA)-inducible cyclic-AMP (cAMP) accumulation in brain may reflect the integrity of synaptic transmission mechanisms and brain viability, we studied its changes in cerebral cortex after various durations of decapitation ischemia. Unanesthetized rats were decapitated and the brains were kept at 37 degrees C for times ranging from 0 to 60 min. Cerebral cortical slices were incubated in vitro and NA (11.2 microM)-induced cAMP accumulation was evaluated over 10 min. At 0 min of ischemia, NA-induced cAMP accumulation was 56 pmol/mg protein/10 min. Between 0 and 20 min of ischemia, a linear eightfold increase, to 435 +/- 49 pmol/mg protein/10 min, occurred in NA-induced cAMP accumulation, with no further increase after longer durations of ischemia. The mechanisms modulating the increase in cortical NA-inducible cAMP accumulation with a maximum response after 20 min of ischemia remain to be defined.

Cardiorespiratory effects of meperidine, diazepam, and methohexital conscious sedation.

The effects of conscious sedation on the respiratory and cardiovascular systems of seven healthy volunteers were studied. With mean dosages of meperidine, 0.41 mg/kg, diazepam, 0.13 mg/kg, and methohexital titrated incrementally to effect, there were statistically significant changes in PaO2, PaCO2, and arterial blood pH, and no statistically significant change in cardiac output as determined by arterial blood gas analysis and impedance cardiac output monitoring. No clinically significant changes were observed in cardiorespiratory function, and all patients were conscious according to the definition proposed by the American Dental Society of Anesthesiology. The variation in PaO2 showed only marginal statistical significance. There was no clinical indication for supplemental oxygen.