Orthodontic Treatment Need and Short-Term Oral Hygiene Assessment in Children Undergoing Different Early Orthodontic Treatments

Objectives: Oral hygiene maintenance may be influenced by both malocclusion severity and orthodontic appliance type during early orthodontic treatment. Therefore, this study aimed to evaluate the relationship between orthodontic treatment need assessed using the Index of Orthodontic Treatment Need (IOTN) and oral hygiene status measured using the Simplified Oral Hygiene Index (OHI-S) in children undergoing early orthodontic treatment and to compare short-term oral hygiene outcomes between clear aligner and removable appliance therapies. Methods: Twenty-four children aged 6–12 years with anterior dental crossbite were included in this prospective observational cohort study. Patients treated with clear aligners (n = 12) or removable appliances (n = 12) were evaluated. Orthodontic treatment need was assessed using the IOTN Dental Health Component (DHC) and Aesthetic Component (AC), and oral hygiene status was evaluated using the OHI-S at baseline and day 14. Statistical analyses were performed with p < 0.05 considered significant. Results: A statistically significant positive correlation was observed between IOTN-DHC and IOTN-AC scores (rs = 0.648; p = 0.001). Participants with higher orthodontic treatment need had poorer oral hygiene status at baseline, and this difference remained evident at day 14. Day-14 OHI-S scores were significantly higher in the removable appliance group than in the clear aligner group (p = 0.039). In addition, the reduction in OHI-S scores was significantly greater in the clear aligner group (p = 0.043). When all participants were analyzed together, oral hygiene status improved significantly from baseline to day 14 (p < 0.001). Conclusions: Higher orthodontic treatment need was associated with poorer oral hygiene status during early orthodontic treatment. Clear aligners were associated with more favorable short-term oral hygiene outcomes than removable appliances.