Association between Salivary Hormones, Dental Caries, and Cariogenic Microorganisms during Pregnancy

Abstract

Objective: This study aimed to identify the salivary levels of six hormones (progesterone, estradiol, testosterone, cortisol, thyroxine T3, and triiodothyronine T4) in pregnant women, and to assess the association between salivary hormones, dental caries, and cariogenic microorganisms. Methods: This cross-sectional study included 181 low-income US pregnant women who were in their third trimester. Demographic details, oral hygiene practices, and medical backgrounds were obtained via questionnaires and medical records. Calibrated dentists obtained data on plaque index and caries status through comprehensive oral examinations. Unstimulated saliva was collected 2 h before eating and brushing. Salivary hormones were measured with a multiplex assay. Oral Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) were quantified via colony-forming unit (CFU) counts. A latent model was used to generate clusters of pregnant women based on salivary hormone levels, followed by post-clustering analysis. Factors associated with salivary cariogenic microorganisms were further evaluated via multiple regression analyses. Results: Estradiol, progesterone, testosterone, cortisol, T3, and T4 in saliva were detectable at rates of 92%, 97%, 77%, 99%, 71%, and 50%, respectively. Three distinct participant clusters (high, intermediate, and low) were identified based on salivary hormone levels. Intermediate-level and high-level clusters had increased numbers of decayed teeth, decayed surfaces, ICDAS scores, and salivary S. mutans and C. albicans, compared to the low-level cluster (p < 0.05). Covariate analysis demonstrated that the high-level cluster was positively associated with salivary carriage of S. mutans (CFU/mL) (p < 0.05). Participants with higher levels of progesterone, estradiol, testosterone, and cortisol were associated with a high carriage status of S. mutans in saliva (>10⁵ CFU/mL) (p < 0.05). Conclusions: This study demonstrated the feasibility of detecting salivary hormones during pregnancy and revealed the positive association between salivary steroid hormones and cariogenic pathogens.

Keywords: Candida albicans; Streptococcus mutans; caries; hormone; pregnancy.

Figure 1

Correlation matrix of hormones. Progesterone, estradiol, and testosterone had strong correlations in between. ** p < 0.01.

Figure 2

Clusters of pregnant women based on hormone level patterns with latent profile analysis (LPA). (A) A latent model was used to generate three clusters of pregnant women based on their salivary hormone levels. Three clusters were distinguished from 181 samples, including the clusters of low hormone levels, intermediate hormone levels, and high hormone levels. There is minimal overlap among the three classes, signifying that the classification effectively differentiates based on hormone levels. (B,C) The K-means clustering method yields results remarkably similar to those obtained using LPA, with 170 out of 181 subjects being classified into the same cluster by both methods. Additionally, the K-means method produces a flawless cluster plot for three clusters; the plot—indicating the optimal number of clusters—also suggests that three is the ideal number. Consequently, we selected three as the number of clusters.

Figure 3

Forest plots of logistic regression models show factors associated with a high caries risk status indicated by salivary S. mutans ≥ 10⁵ CFU/mL. The odds of a high caries risk status of salivary S. mutans ≥ 10⁵ CFU/mL are predicted to (A) increase by 1.68 times with each additional unit of Ln (progesterone, pg/mL) (p < 0.01), (B) increase by 1.64 times with each additional unit of Ln (estradiol, pg/mL) (p < 0.01), (C) increase by 1.55 times with each additional unit of Ln (testosterone, pg/mL) (p < 0.01), and (D) increase by 1.58 times with each additional unit of Ln (cortisol, pg/mL) (p < 0.05).