An investigation was conducted to test the hypothesis that age and wear of toothbrushes do not affect plaque removal. 40 preclinical dental students between the ages of 19 and 26 years were assigned randomly to 2 groups. 1 group of 19 subjects used a toothbrush for 10 weeks while the 21 subjects in the other group were given new toothbrushes every 2 weeks for 10 weeks. A baseline of zero plaque and calculus was obtained on the first visit. On subsequent visits, 2 weeks apart, the gingival status of each group was evaluated using the gingival index, and plaque levels were scored using the patient hygiene performance index. The brushing surface area of the toothbrushes was measured with a caliper as well as being graded subjectively according to their condition (good, fair or poor). Results were statistically analysed at the end of the 10-week period. It was found that after 10 weeks, the subjects using the same toothbrush for the whole period had significantly more plaque than those who replaced their brushes every 2 weeks. As brushes deteriorated, they became less effective. No differences in gingival state were detected. There was appreciable variation in toothbrush wear among subjects, some reducing their brush to a poor state in 2 weeks whereas with others the brush was rated as "good" after 10 weeks.

Objective To measure the effect of giving out free smoke alarms on rates of fires and rates of fire related injury in a deprived multiethnic urban population. Design Cluster randomised controlled trial. Setting Forty electoral wards in two boroughs of inner London, United Kingdom. Participants Primarily households including elderly people or children and households that are in housing rented from the borough council. Intervention 20 050 smoke alarms, fittings, and educational brochures distributed free and installed on request. Main outcome measures Rates of fires and related injuries during two years after the distribution; alarm ownership, installation, and function. Results Giving out free smoke alarms did not reduce injuries related to fire (rate ratio 1.3; 95% confidence interval 0.9 to 1.9), admissions to hospital and deaths (1.3; 0.7 to 2.3), or fires attended by the fire brigade (1.1; 0.96 to 1.3). Similar proportions of intervention and control households had installed alarms (36/119 (30%) v 35/109 (32%); odds ratio 0.9; 95% confidence interval 0.5 to 1.7) and working alarms (19/118 (16%) v 18/108 (17%); 0.9; 0.4 to 1.8). Conclusions Giving out free smoke alarms in a deprived, multiethnic, urban community did not reduce injuries related to fire, mostly because few alarms had been installed or were maintained.

The periodontal status of the six teeth of the Ramfjord P. D. J. in 89 women aged 17–23 years who were taking an oral contraceptive was compared with a group of 72 in the same age bracket practising other forms of contraception. Mean plaque scores for the two groups showed no significant difference, but were slightly lower in the hormonal group. G.I. scores for the hormonal group were slightly higher than for the other group, but the difference was not significant. Those who had been on oral contraceptives for more than 1.5 years (mean 3.0 years) had a lower plaque score than those who had taken them for less than 1.5 years (mean 0.7 years) but their G. I. was greater, and their mean amount of periodontal destruction significantly greater than in the shorter time group and in those of comparable age using other forms of contraception.

The effectiveness of plaque removal using two brushes with the Bass technique and two with the Roll method was compared in a group of 38 junior dental students using a crossover experimental design. The Bass technique was superior to the Roll method in cleaning the tooth tissue adjacent to the gingival tissue on the lingual and facial aspects, but no significant differences were found in the overall effectiveness. Cleaning of all tooth surfaces was at an unacceptable level and it is concluded that efficient tooth cleaning is not achieved by detailed instruction at a single visit including a demonstration of competence by the subject and the issue of written instructions. Repetition of the instruction within 3 weeks did not achieve a higher standard of plaque removal.