A new epidemiological study of Japanese adolescents found that dental crowding, increased overjet, and increased overbite were the strongest indicators of orthodontic treatment need.
In their research, which was conducted among 726 junior and senior high school students aged 12 to 18, investigators evaluated how specific dental conditions corresponded with aesthetic assessments in a school-based setting.
The researchers examined students at Tsurumi University Junior and Senior High School in Yokohama, Japan. A total of 894 students were initially screened, and 168 (18.8%) who were undergoing or had completed orthodontic treatment were excluded. The final study population consisted of 443 males and 283 females. All assessments were conducted by 9 licensed orthodontists who underwent calibration prior to data collection.
Orthodontic treatment need was evaluated using the Index of Orthodontic Treatment Need, which includes 2 components: the Dental Health Component (DHC) assesses morphological features, and the Aesthetic Component (AC) uses a 10-point photographic scale to rate dental appearance. Of the 726 students, 153 (21.1%) were classified as requiring treatment (DHC grade 4 or 5), 200 (27.5%) were borderline (DHC grade 3), and 374 (51.5%) had no treatment need (DHC grades 1 or 2).
Item Response Theory analysis identified the DHC items with the highest discriminatory power, wrote the study authors, led by Hiromi Sato, DDS, of the Department of Orthodontics at Tsurumi University. Crowding (DHC item 4.d, discrimination = 243.28), increased overjet (4.a, discrimination = 48.65), and increased overbite (4.f, discrimination = 29.92) most effectively distinguished students who required treatment.
Linear regression analysis confirmed that these features also significantly contributed to higher AC scores. Crowding at DHC grade 2 (item 2.d) was associated with AC grade (P < .001), as were increased overjet (2.a; P = .003) and increased overbite (2.f; P = .003).
Correspondence analysis revealed a general alignment between DHC and AC grades, although aesthetic evaluations tended to underestimate the severity of malocclusion. Some students with high DHC scores received relatively low AC scores, particularly in cases that involved posterior discrepancies or deep bites that are less visible from the frontal view.
Females had a higher rate of treatment need compared with males, particularly in later school years. The authors noted this finding might reflect differences in growth patterns or heightened aesthetic awareness.
The researchers acknowledged limitations, including low interexaminer reliability (κ = 0.26) and the absence of radiographic confirmation for certain conditions. Nonetheless, the authors concluded, in school-based settings where time and resources are limited, combining objective morphological assessments with aesthetic review may offer a clearer picture of who truly needs orthodontic care to avoid underdiagnosing clinically significant malocclusion.
The authors reported no conflicts of interest.
Source: Journal of Clinical Medicine
