Introduction: Dental caries is an infectious disease that causes damage to the tooth structure and has an increasing prevalence in developing countries. Dental caries often occur first in the first permanent molars because they are the first permanent teeth to erupt into the oral cavity. Salivary pH and plaque index can affect the development of dental caries. The purpose of this study was to determine the correlation between salivary pH and plaque index on the oc-currence of caries in permanent first molars in adolescents aged 17–20 years. Materials and methods: This study is a cross-sectional study. The population in this study is adolescents aged 17–20 years, totaling 78 people, consisting of 16 men and 62 women. The sampling technique in this study used a non-probability purposive sampling technique. Results: A total of 40 people (51.28%) had caries in their permanent first molars, and 38 people (48.72%) did not have caries in their permanent first molars. While the results of the salivary pH examination found that only one person (1.28%) had a low salivary pH (pH 5.0–5.7), eight people (10.25%) had a moderate salivary pH (pH 6.0–6.6), and 69 people (88.46%) had a high salivary pH (pH 6.8–7.8). The Spearman test was utilized to analyze the correla- tion of the results of this study. The relationship between salivary pH and the occurrence of caries in permanent first
molars teeth was not significant (p0.05). Conclusion: The dental plaque index significantly correlates with permanent first molar caries in adolescents aged 17–20 years. However, the incidence of caries does not have a significant relationship with the pH value of saliva in the oral cavity.
Keywords: Adolescent, Dental caries, Incidence, Prevalence, Saliva