Facial muscle innervation in Cebid (New World) and Macaque (Old World) monkeys via a ramus communicating with the trigeminal nerve.

Direct motor and reflex EMG responses were recorded from facial muscles in monkeys subjected to stimulation of the communicating ramus of the auriculo-temporal nerve. Transection of the ramus distal to the stimulus site eliminated the direct motor response. Transection of the ramus proximal to the stimulus site eliminated the reflex component. The results suggest that the trigeminal nerve carries motor fibres serving facial muscles.     

Effects of cement bases on the stresses and deflections in composite restorations.

A model was used to investigate stresses and deflections in cement bases and in a composite restorative material induced in a posterior Class I restoration. Deflections in the composite were highest when it was supported by a base with a low modulus; however, the maximum tensile stress (12 MN/meter2) occurring in the composite restoration at the interface with the base was well below the maximum tensile strength of most composite materials (30 to 40 MN/ meter2). Tensile and shear stresses occurring in the cement bases were of sufficient magnitude to exceed the strength of the cement when a 1.5-mm layer of zinc phosphate cement (base consistency) was supported by a 0.5-mm layer of ZOE lining material. Lowest values of stress were observed when a 2-mm layer of a zinc polyacrylate base was used to support the composite restoration. An ideal situation would be to have a cement base with a modulus of elasticity equal to that of the composite material. Finally, the maximum stress and deflection values obtained here can be easily exceeded in a clinical situation when wider variations can be easily introduced, making the choice of a cement with the proper modulus even more critical.     

Caries experience as predictor for caries incidence

The caries increment (filled surfaces) from the ages 7 to 15 years were compared in children with three or fewer (low prevalence group) or eight or more filled surfaces (high prevalence group) at the age of 8. The children participated in a fortnightly fluoride mouthrinsing program (10 ml of 0.2% NaF). Following 8 years of dental treatment and caries prophylaxis, the caries increments were 11.4 (s.d. = 7.7, n = 23 subjects) and 17.1 (s.d. = 9.6, n = 39 subjects) surfaces, i.e. significantly different (t = 2.376). Significantly (t = 4.034) more fillings had been required in the high than in the low prevalence group (31.1 +/- 17.1 vs. 15.5 +/- 9.6). The "risk group" could be identified at the ages of 7 to 8 by high caries prevalence and high ratio fillings/caries increment. Social class and number of teeth accounted more for the initial caries prevalence than for the caries increment. Correlation analyses revealed a significant, but not strong (r = 0.50), association between caries prevalence at the age of 7 and increment of fillings.     

Two-year clinical evaluation of a pit and fissure sealant. Part II. Caries initiation and progression.

For the study, 479 paired permanent teeth and 20 paired deciduous teeth were coated under controlled clinical conditions with Nuva-Seal. A red dye was added to assist in placement and subsequent evaluation over a two-year period. Eighty-four children (ages 10 to 14) participated in the study. Caries was evaluated 3, 6, 12, and 24 months later with the same rating scale used at the baseline examination (0, caries free, to 4, severe caries), except when the sealant was found completely present and intact; then caries evaluation was limited to visual inspection through the sealant. The caries rate for control teeth was 6.9% at 3 months, 16.1% at 6 months, 26.4% at 12 months, and 37.6% at 24 months. Corresponding percent effectiveness figures for the sealant were 63.6%, 66.6%, 61.7%, and 54.6%, respectively. At 24 months, effectiveness rates for all types of teeth were at least 52% with the exception of the maxillary second molars (only 27% sealant effectiveness). Overall, caries protection as reflected by percent effectiveness was higher for mandibular teeth and premolars than for maxillary teeth and molars. There was significant effect on the incidence of dental caries when the sealant remained completely intact. Percentage effectiveness rates in this case were 90.7% at 12 months and 90.9% at 24 months. There was little gain or loss in caries protection when the sealant was partially or completely missing. Twenty-four percent of the children had a positive net gain or treatment effect at three months. This increased to 52% at 6 months, 62% at 12 months, and 70% at 24 months. With the use of half-mouth caries rates, the corresponding figures for positive treatment effects were slightly higher (30%, 64%, 70%, and 80% respectively).     

Electron microscopic observations of "keratin pools" in chronic hyperplastic oral mucosa.

"Keratin pools," previously characterized clinically and histochemically in the superficial epithelium of chronic hyperplastic oral mucosa, were studied by light and electron microscopy. These occured as small beaded and larger coalescent masses which varied in metachromasia. Ultrastructurally, the "keratin pools" consisted of electron-dense, amorphous or finely-granular material developing and coalescing, chiefly as extracellular deposits. The "pools" frequently possessed a layered arrangement alternating with cells having distinct tonofilaments, desmosomes, and definite cell membranes. Occasional bands of filamentous-like material, possibly representing tonofilament bundles, were observed in some "pools."