Background: Orthodontic treatments are known to complicate oral hygiene practices due to the structural complexities they introduce, potentially increasing the risk of dental caries. This study aims to evaluate the incidence of dental caries among adolescents undergoing fixed orthodontic treatment compared to those without such interventions. Materials and Methods: A cohort study was conducted with 200 adolescents aged 12-16 years, divided into two groups: 100 receiving fixed orthodontic treatment and 100 without any orthodontic appliances. Both groups were assessed for dental caries using the Decayed, Missing, and Filled Teeth (DMFT) index at baseline and after 12 months. Oral hygiene practices were monitored, and fluoride exposure was standardized across both groups. Results: At the onset, the mean DMFT scores were comparable between the two groups (2.1 ± 1.3 in the orthodontic group and 2.0 ± 1.4 in the control group). After 12 months, the orthodontic group showed a statistically significant increase in DMFT scores (3.5 ± 1.5) compared to the control group (2.3 ± 1.5) (p < 0.05). The increase in decayed teeth was notably higher in the orthodontic group, contributing significantly to the overall DMFT score.