Changes in Salivary Matrix Metalloproteinase-8 Concentrations Are Not Associated with Oral Health during Early Adolescence.

INTRODUCTION: Salivary matrix metalloproteinase-8 (MMP-8) concentration is considered a biomarker of oral health in adults, but studies in pediatric populations, especially with longitudinal data, are scarce. METHODS: We examined the associations of caries experience (DFT index) and gingivitis/calculus (CPITN) retrieved from public dental records with repeated salivary MMP-8 concentrations. Salivary MMP-8 were measured from 403 Finnish adolescents (50.1% girls) at the mean (SD) age of 11.4 (0.4) and 13.8 (0.5) years, using an ELISA kit. Oral health was determined on average 42 (27) days after saliva collection at baseline. The DFT index was categorized into no caries experience (DFT = 0) and having caries experience (DFT >0), and CPITN into no gingivitis/calculus (CPITN = 0) or having gingivitis/calculus (CPITN >0). RESULTS: Of the participants, 19.1% presented with caries experience, and 69.5% had gingivitis/calculus. The mean MMP-8 increased during follow-up by 0.125 ng/mL (95% CI: 0.05; 0.20, p = 0.006). MMP-8 at the two time points correlated weakly in all participants (r = 0.137, p = 0.006), especially in girls (r = 0.204, p = 0.004). The change in MMP-8 was not associated with caries experience or gingivitis/calculus in all participants or in gender-specific analyses (repeated measures ANOVA p > 0.05). Puberty status and medication use were not related to MMP-8 concentration. CONCLUSIONS: Oral health indices retrieved from public health records were not associated with changes in MMP-8 concentrations in early adolescents over a 2-year follow-up. Salivary MMP-8 may not be a suitable biomarker of oral health in pediatric populations.