The relationship between maxillary and mandibular third molar germ stages and skeletal orthodontic malocclusions.

Abstract

Aim: To evaluate the relationship between third molar germ formation and three-dimensional (sagittal, vertical, and transverse) skeletal malocclusions to guide early orthodontic diagnosis and proactive treatment planning.

Materials and methods: A retrospective study was conducted using the initial orthodontic records of 483 patients (58.6% female, 41.4% male; mean age 12.42 ± 2.26 years) treated between 2014 and 2025. Initial panoramic, posteroanterior (PA), and lateral cephalometric radiographs were evaluated to determine Sella-Nasion-Point A Angle (SNA), Sella-Nasion-Point B Angle (SNB), Point A-Nasion-Point B Angle (ANB), and Sella-Nasion to Gonion-Gnathion Plane Angle (SN-GoGN) angles, along with maxillary-mandibular skeletal widths. Sagittal classification used ANB angle thresholds (Class III: ANB <0°; Class I: 0°-4°; Class II: ANB >4°); vertical classification used SN-GoGn (<27° = hypodivergent; 27°-38° = normodivergent; >38° = hyperdivergent); transverse classification used PA cephalometric skeletal widths relative to age- and sex-adjusted reference norms. Third molar germs were scored utilizing the Demirjian method. Inclusion criteria strictly required the absence of systemic diseases and prior third molar region surgeries.

Results: In the early mixed dentition group, the germ formation stage of the mandibular right third molar (tooth 48) showed a nominally significant difference across sagittal skeletal malocclusion classes (P = .018; uncorrected). Skeletal Class III cases exhibited more advanced germ formation for tooth 48 compared to Skeletal Class II cases. However, following Bonferroni correction for multiple comparisons (corrected threshold P < .0028), this finding did not reach statistical significance and should be considered an exploratory observation. No significant differences were found regarding transverse or vertical skeletal malocclusions across any dentition groups (P > .05).

Conclusions: (i) No significant correlation exists between maxillary/mandibular transverse skeletal widths and third molar germ formation stages. (ii) Skeletal Class III patients in the early mixed dentition period demonstrate accelerated development of tooth 48, likely reflecting advanced sagittal mandibular growth.