Salivary Biomarkers for Oral Frailty in Patients With Burning Mouth Symptoms

Despite its relevance to physical frailty, the pathophysiological mechanisms underlying oral frailty remain poorly understood. This study aimed to investigate salivary biomarkers associated with oral frailty.

Ninety-eight postmenopausal women (mean age, 65.2 ± 7.2 years) with burning mouth symptoms were included in this study. This study was conducted as an ancillary analysis of our previous cohort. Oral frailty was assessed using a validated 4-point scale for difficulties in chewing, speaking, and swallowing. The levels of inflammatory and oxidative stress biomarkers, stress hormones, and female gonadal hormones were measured using unstimulated (UWS) and stimulated whole saliva (SWS) samples. Blood biomarkers were assessed using complete blood counts. Oral frailty indicator scores, salivary and blood biomarker levels were analysed based on the presence or absence of additional oral dysfunctions, including dry mouth and taste disturbances. Furthermore, correlations between oral frailty indicators and salivary or blood biomarkers were examined.

The oral frailty scores, as well as salivary and blood biomarker levels did not differ significantly among the patients based on the presence or absence of additional oral dysfunctions. In UWS, 'speaking difficulties' correlated significantly with C-reactive protein (CRP) levels (r_s = 0.360, P = .006), while 'swallowing difficulties' was correlated significantly with the cortisol/dehydroepiandrosterone ratio (r_s = 0.325, P = .016). In SWS, 'chewing difficulties' correlated significantly with interleukin-1β levels (r_s = 0.252, P = .017), whereas 'speaking difficulties' correlated significantly with CRP (r_s = 0.267, P = .010), 8-hydroxy-2'-deoxyguanosine (r_s = 0.220, P = .040), and 17β-estradiol levels (r_s = 0.265, P = .011). Regarding blood biomarkers, 'swallowing difficulties' was significantly negatively correlated with the total leukocyte (r_s = -0.269, P = .007) and lymphocyte counts (r_s = -0.249, P = .013).

Oral frailty was significantly associated with inflammatory, oxidative stress, and endocrine salivary biomarkers, suggesting multifactorial pathophysiological mechanisms.