The gingival health of 201 schoolchildren aged 11-14 years was assessed at 6 sites on all the incisor and first molar teeth by recording separately the presence or absence of redness and bleeding on probing. Crowding of the incisor teeth was recorded as labio-lingual displacement and mesio-distal overlap. A 2nd examiner recorded the presence or absence of plaque at these sites and assessed mouthbreathing, lipseal and upper lip coverage of the maxillary incisors. Mouthbreathing, increased lip separation and decreased upper lip coverage at rest were all associated with higher levels of plaque and gingival inflammation. Multivariate analysis indicated that this association was statistically significant for mouthbreathing and lip coverage but increased lip separation was not independently related to plaque and gingivitis. The relationship of mouthbreathing and decreased upper lip coverage with gingivitis was most evident in the upper anterior segment and was still evident after covariate analysis to take account of variations due to gender, overcrowding and amount of plaque. However, allowance for these factors also suggested that the influence of mouthbreathing was restricted to palatal sites, whereas lip coverage influenced gingival inflammation at both palatal and labial sites.

The relationship between irregularity of teeth and periodontal disease was investigated in 201 children aged 11-14 years. The upper and lower incisor teeth were assessed for spacing, labio-lingual displacement, and mesiodistal overlap at each of the six contact areas. Plaque and gingivitis were assessed at six sites on each of the four upper and four lower incisor teeth. There was evidence for a direct relationship between the number of contact areas with tooth displacement combined with overlap and the number of sites with gingival redness (R = 0.25, P < 0.001), bleeding (R = 0.18, P < 0.01), and profuse bleeding (R = 0.25, P < 0.001). There was no evidence for a relationship between labio-lingual displacement alone and gingivitis. One-hundred-and-twenty-eight subjects without tooth displacement combined with incisor overlap had, respectively, 34, 15, and 35 per cent fewer sites with redness (P < 0.01), bleeding (P < 0.05), or profuse bleeding (P < 0.01) than the 73 subjects with overlap. The statistical significance of these differences was unaffected by covariate adjustment to take account of the effect on gingivitis of variation in the number of sites with plaque. There was no evidence of a relationship between incisor overlap and amount of plaque in these subjects. The results indicate that overlapping of incisor teeth is directly related to gingivitis and this relationship cannot be explained simply by an effect on oral hygiene.

Resting and stimulated whole saliva was collected from 94 children aged 12-14 years and analyzed for thiocyanate, hypothiocyanite, 'free' and 'total' lysozyme, lactoferrin and secretory IgA. Clinical assessments of the amounts of plaque and gingival inflammation were made, and plaque was collected for determination of dry weight. An inverse relationship was observed between salivary thiocyanate concentrations in both resting and stimulated saliva and the amounts of plaque and gingival inflammation in these subjects (p < 0.05). Lactoferrin concentration in stimulated saliva was directly related to the amounts of plaque and gingivitis (p < 0.05). 'Total' lysozyme concentration in stimulated saliva was directly related to the amount of plaque (p < 0.05), and the 'free' lysozyme concentration in the same saliva was directly related to the amount of gingivitis (p < 0.05). The direct relationship observed between clinical measurements and both lysozyme and lactoferrin concentrations in saliva may have been due to contributions from gingival crevicular fluid. Cluster analysis identified three groups of subjects with different profiles in resting whole saliva, and in particular with different levels of secretory IgA. A statistically significant difference was observed in the quantity of plaque collected from subjects in two of these groups (p < 0.05). These results from cluster analysis using resting whole saliva from children confirmed the findings of a previous study with young adults.