Eighty‐seven sunjects from 3 age groups (5, 11 and 18–22 yr) were asked to brush their teeth and were unaware that they were recorded on video tape. from repeated viewing of the films the following data were obtained: the areas of the mouth which were brushed, the brushing stroke used in each area, the total brushing time and the proportion of time spent on each area. In each of the three age groups, the proportion of the areas that were brushed was 25, 50 and 67 per cent, respectively. MOre time was spent brushing the lower than the upper teeth, and the contra‐lateral side (the left side in right‐handed persons) was brushed more than the ipse‐lateral sinde in children but equally in adults. Less than 10 per cent of the time was spent brushing lingual areas. The most populor brushing strokes were the horizontal in children and the vertical in adults; the roll and circular strokes were seldom used. Eighty‐four per cent of subjects used more than one type of brushing stroke.

The purpose of this investigation was to examine the relation between some dental health behaviours and 2 measures of self-concept in adolescents. Data from a survey of 41142, 12-16-year-old children from 244 secondary schools throughout England were analysed to obtain information about their frequencies of toothbrushing, use of dental floss and dental attendance, and whether they recalled advice about toothbrushing, in relation to self-esteem and health locus of control (HLOC). Subjects completed a questionnaire, anonymously, in school class. The results showed a significant positive correlation (Spearman) between the frequencies of flossing and toothbrushing, in both sexes, and between social group and toothbrushing frequency, where brushing frequency increased as socio-economic status improved. Some association between use of floss and social group emerged, but this was smaller and less consistent than that observed with toothbrushing brushing frequency. Self-esteem was positively correlated with toothbrushing frequency at ages 12-15 years, while HLOC showed correlations at some ages but not others. Use of dental floss showed no relation to self-concept. Subjects with more favourable self-concept were more likely to make more frequent dental visits than those with a poorer self-view. There was a strong and consistent correlation between recalled advice about toothbrushing and lower self- esteem and external locus of control. The results are in agreement with our earlier reports and suggest that self-concept may play a significant role in mediating changes in dental health behaviour.

Proqram in Geosciences, University of Texas at Dallas, RichardsonThe two groups of Roberts Victor eclogites may be further distinguished by their •80/•60 ratios; one above (I) and one below (II) the mantle value (5.7). In the group II suite systematic variation of the major elements with oxygen isotopes matches that calculated for oceanic volcanic rocks altered by circulating seawater in ridge crest hydrothermal systems. A negative linear correlation between t80/•60 and 87Sr/86Srtwm and an associated positive correlation with K20 (and Rb) of the anhydrous eclogite assemblage with 87Sr/S6Srtwm are also products of hydrothermal alteration. The chemical and isotopic similarity of the eclogites to hydrothermally altered oceanic crust supports the conclusion that they are subducted fragments that have been metamorphosed from metabasalts to eclogites. During metamorphism the elements are fractionated into two components. One, enriched in the radiogenic isotopes of U, Th, K, and Rb, and light rare earth elements, is concentrated in a hydrous, interstitial, mobile component, and the other, enriched in Nd relative to Sm, is concentrated in the anhydrous, immobile, garnet and clinopyroxene host. The mobile component is comparable in chemistry to rocks of the MARID suite and may well play an important role in mantle metasomatism. Nd/Sm and Pb/Pb ages indicate an Archean age (approximately 2.47 b.y.) for the metamorphism. Depth estimates indicate a skewed distribution with most eclogites coming from the depth range 165-190 km. The concentration of eclogites correlates with the inflection in the Lesotho geotherm and appears to mark a disrupted layer of subducted Archean oceanic crust separating a shallower region of undeformed, refractory, Mg-rich peridotites from deformed, Fe-rich, more "fertile" pyrolite. This boundary may be interpreted as the "petrologic" base to the continental lithosphere. lower depths close to the base of the continental crust [Griffin et al., 1979]. The Roberts Victor eclogites have been previously interpreted as two groups of rocks that are cogenetically related as a suite of cumulates and liquids formed during the fractional crystallization of a high-pressure mafic magma [MacGreqor and Carter, 1970; Hatton, 1978; Hatton and Gurney, 1977; Kyser et al., 1981]. Although the model adequately accounts for the major element and textural variations, it has not been successful in explaining subsequent data sets on oxygen isotopes [Garlick et al., 1971-1, trace elements [Chen, 1969, 1972-1, rare earth elements [Early, 1971-1, and whole rock strontium isotopes. The stimulus to reevaluate the magmatic hypothesis came from the comprehensive studies on the Samail ophiolite, Oman [Coleman and Hopson, 1981], and oxygen isotope studies of oceanic rocks [Stakes and O'Neil, 1984; Stakes et al., 1984; Taylor, 1983]. In particular, application of the models used to explain the oxygen and strontium isotopic distribution in rocks from the oceanic crust [McCulloch et al., 1981; Gre-•7ory and Taylor, 1981; Bowers and Taylo...

One hundred and fifteen uninstructed subjects from two age groups (11-13 y and 18-22 y) were asked to brush their teeth and were unaware that their toothbrushing was recorded on video tape. From the video tape the sequence in which different areas of the mouth were brushed was obtained. The brushing sequence in the two age groups was similar, though the adults brushed a greater variety of sites. Fifty per cent of subjects began brushing in the anterior labial areas, 25 per cent in the left buccal, but only 3 per cent in the right buccal areas. There was a strong tendency to move the brush from left to right; occlusal surfaces were commonly brushed consecutively. Lingual areas were rarely brushed, but when brushed most commonly followed occlusal surfaces. Areas which were brushed were usually brushed more than once: the anterior labial areas were brushed 4.5 times and were the most frequently returned-to site.

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The aim of this 3-group, 3-treatment, single-blind, parallel group study was to evaluate and compare the efficacies of the Philips/Jordan HP 735 powered toothbrush, the Braun/Oral B D7 powered toothbrush and the Oral B Advantage B35 manual toothbrush in a cohort of 75 young adults (18-25 years). Following an appointment for screening, full mouth mean (+/-sd) modified Turesky plaque index (PI) and Löe & Silness gingival index (GI) were recorded at baseline. After 24 h abstinence from all oral hygiene measures, PI was recorded and each subject was given one of the test brushes with detailed instructions for use. The subject then brushed under supervision for 90 s, during which time mean (+/-sd) toothbrushing forces (TBF) were recorded. PI were recorded immediately after supervised brushing and the subjects were then discharged for 6 weeks to use the allocated toothbrush at home. After 6 weeks, PI, GI and TBF were again recorded. Comparisons between the brushing groups for all parameters, at baseline, 24 h and 6 weeks were tested using ANCOVA. There were no significant differences for PI and GI between groups at baseline, or for PI following supervised brushing at 24 h. After 6 weeks subjects using the powered brushes had lower mean PI (+/-sd) scores than those using manual brushes but the differences were significant only at interproximal sites; HP 735 1.44 (0.52), D7 1.44 (0.53), B35 1.75 (0.51) (p=0.05). At 6 weeks, mean (+/-sd) GI were; HP 735 1.49 (0.21), D7 1.61 (0.21), B35 1.64 (0.22) (p=0.033). Mean GI scores for the HP 735 group were similar at baseline and at 6 weeks although for the other brushes, the GI scores actually increased over this period. Mean (+/-sd) TBF (grammes/force) at baseline and 6 weeks respectively for the brushes were; HP 735 233 (205), D7 159 (58), B35 279 (122) (p=0.026): HP 735 194 (86), D7 141 (57), B35 297 (113) (p=0.0001). The within-group variability for the HP 735 TBF reduced considerably over 6 weeks, a likely consequence of the click-force threshold feature of this brush.

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