Salivary matrix metalloproteinase-8 levels and periodontal health status among adults attending the university of Nairobi dental hospital
Background: Periodontal disease is common globally and affects about 80% of Kenyans. Late patient presentation and diagnosis coupled with lack of treatment, results in significant morbidity and tooth mortality, reduced quality of life for individuals and communities. Currently periodontal diagnosis is based on clinical findings, which utilizes techniques that are invasive and have been shown to have inherent errors and drawbacks including inability to detect current disease activity and host response. Matrix metalloproteinase 8 (MMP-8) is a key biomarker in periodontal tissue destruction and may be found in saliva. Quantification of salivary MMP-8 levels may provide a non-invasive technique for detecting the presence and activity state of periodontal disease. Objective: To determine the relationship between the salivary MMP-8 levels and periodontal health status in adults attending The University of Nairobi Dental Hospital. Study design: A cross-sectional study was carried out between July 2014 and April 2015. Study participants: The study participants were adult patients aged 18 years and above visiting The University of Nairobi Dental Hospital during the period of the study. Materials and methods: Using convenience sampling, one hundred and twenty adults were recruited out of a calculated sample size of 80 with a power of 80%. Participants who fitted the inclusion criteria had about 5mL of unstimulated whole saliva samples collected over 3 minutes, between 7:30 am and 10:00 am along with their serialized biodata. Periodontal examination to assess oral hygiene (Silness and Löe, 1964) and gingival status (Löe and Silness, 1963) were carried out. Periodontal health status was assessed using periodontal probing depth (PPD), recession and clinical attachment loss (CAL) recorded on similarly serialized forms and classified according to the CDC/AAP consensus definitions for epidemiological studies. In the present study, target salivary MMP-8 from every participant’s saliva sample was quantified using a double antibody sandwich ELISA technique utilizing specific monoclonal antibodies. Six out of the 120 were excluded as extreme outliers. Data collected was coded and analysed using Microsoft Excel, SPSS version 20.0 for Windows and R software. Descriptive statistics were done using means and standard deviations. Chi square, t-test, Analysis of Variance (ANOVA), Pearson correlation statistics and multiple linear regression tests were also performed. Measures of prediction of salivary MMP-8 were computed using area under the curve (AUC), receiver operating characteristic (ROC), sensitivity and specificity for cut off value. Statistical significance was set at p<0.05. Results: Statistically significant higher levels of salivary MMP-8 were found in increasing periodontal disease severity. Out of the 120 participants recruited, 6 were dropped from the analysis as extreme outliers. The participants with no periodontitis were found to have 22.68 ng/mL, mild periodontitis 44.55 ng/mL, moderate periodontitis 46.34 ng/mL and severe periodontitis 156.62 ng/mL. A mean level of salivary MMP-8 of 40.52ng/mL (±66.38 SD ng/mL) with a range of 0.0 ng/mL to 295.9 ng/mL was found. A predictive value of 0.8 (AUC=0.8, p=>0.001) and an optimal cut off concentration of 114.55 ng/mL was observed. Conclusion: Within the limits of this study, a positive association was drawn between salivary MMP-8 levels and periodontal health status among adults visiting the UoN dental hospital. Recommendation: Salivary MMP-8 should be considered as a potential diagnostic and adjunctive evaluation tool for assessing periodontal disease. However, there is further need to study this putative biomarker in better-controlled and randomized longitudinal studies in the Kenyan setting.