Comparative Analysis of Halitosis in Adolescents and Young Adults with Removable Retainers, Fixed Retainers, or No Orthodontic Treatment: A Cross-Sectional Study with Salivary pH Subgroup Analyses

<b>Background and Objectives</b>: Halitosis is a persistent oral health issue that can undermine self-esteem and social interactions, particularly in younger populations who may be more vulnerable to peer judgment. Orthodontic retainers-both removable and fixed-can alter oral microbiota and salivary parameters, potentially influencing malodor development. This study aimed to compare halitosis severity and oral-health-related quality of life (OHRQoL) in adolescents and young adults (aged 12-25) wearing removable retainers, fixed retainers, or no orthodontic appliances, with an additional focus on salivary pH as a possible modifying factor. <b>Methods</b>: A total of 88 participants were allocated into three groups: removable retainer (n = 28), fixed retainer (n = 30), and no orthodontic treatment (n = 30). Halitosis severity was measured via organoleptic evaluation (0-5 scale) and the Halitosis Associated Life-Quality Test (HALT, 0-100). Salivary pH was determined using a digital pH meter. OHRQoL was assessed through the Oral Health Impact Profile-14 (OHIP-14, 0-56). One-way ANOVA with Tukey's post hoc test and chi-square analyses were employed to compare outcomes among groups. Spearman's correlation explored relationships among HALT, organoleptic scores, OHIP-14, and salivary pH. <b>Results</b>: Fixed retainer wearers exhibited higher mean organoleptic scores (2.2 ± 0.6) compared to removable retainer users (1.7 ± 0.5, <i>p</i> = 0.003). HALT results similarly showed that the fixed retainer group (35.6 ± 6.4) reported more halitosis-related burdens than the removable group (31.4 ± 5.9, <i>p</i> = 0.015). Low salivary pH (<6.8) was linked to greater malodor indices in all cohorts (<i>p</i> < 0.05). Correlations revealed moderate positive associations between HALT and OHIP-14 (r = +0.52, <i>p</i> < 0.001). <b>Conclusions</b>: Adolescents and young adults wearing fixed orthodontic retainers reported more severe halitosis and a correspondingly lower oral-health-related quality of life than those with removable retainers or no orthodontic appliances. Salivary pH emerged as an influential factor, indicating that maintaining a neutral oral environment could mitigate malodor. Targeted interventions emphasizing hygiene and saliva management may improve overall well-being in this vulnerable age group.