Short-Term Effect of Fixed Orthodontic Appliances on Salivary pH and Its Correlation with Periodontal Health Indicators

Abstract

Background: Fixed orthodontic appliances (FOA) may alter the oral ecosystem by changing salivary pH (SpH) and promoting dental biofilm retention.

Objectives: This study aimed to evaluate short-term SpH changes after FOA placement and examined correlations between SpH and periodontal health parameters (PHPs) across early-treatment follow-up visits (baseline, 3 months, and 6 months).

Methods: In this prospective single-arm repeated-measures clinical trial, 30 patients (13–45 years) were assessed at T0 (baseline, pre-bonding), T1 (3 months post-bonding), and T2 (6 months post-bonding). Unstimulated whole saliva was collected in the morning and SpH measured immediately using a calibrated digital pH meter (mean of three readings). PHIs included plaque index (PI), gingival index (GI), mean probing pocket depth (PPD), and bleeding on probing (BOP%). Statistical analysis was conducted on the collected data using SPSS (v30), with paired comparisons across time points and correlation testing between SpH and PHPs.

Results: Mean SpH increased from 6.971±0.431 at baseline to 7.176±0.625 at 6 months, but the overall change was not statistically significant (p=0.079). PPD increased significantly over time (2.577±0.191 to 3.125±0.216; p<0.001), as did plaque index (0.437±0.324 to 0.735±0.423; p<0.001). Gingival inflammation and bleeding on probing did not change significantly (p=0.080 and p=0.055, respectively). SpH showed a significant positive correlation with bleeding on probing at baseline (r=0.386, p=0.035), while other correlations were weak and non-significant.

Conclusions: Fixed orthodontic treatment was associated with measurable worsening in selected periodontal indices over 6 months, whereas SpH showed only a modest, non-significant upward trend. These findings support careful periodontal monitoring and reinforced oral hygiene during early orthodontic treatment.