Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients

Kanticha Chailom, Supassara Sirabanchongkran, Kanich Tripuwabhrut, Kachaphol Kuharattanachai

Published Online: Aug 7, 2026 DOI DOI 10.12982/OSR.2026.042

Objectives: This study aimed to compare the mandibular posterior available space between patients with skeletal Class I and skeletal Class III malocclusion.

Methods: The retrospectively analyzed cone-beam computed tomography (CBCT) scans from 60 Thai orthodontic patients with normodivergent patterns. Patients were allocated to skeletal Class I or Class III; Class III severity was stratified by Wits appraisal. Mandibular posterior available space (MPAS) was measured on axial slice of CBCTs at the crown level and at root levels 3, 6 and 9 mm (RL3, RL6 and RL9) apical to the cementoenamel junction. Comparisons of the mandibular posterior available space between skeletal Class I and Class III groups were performed using the Mann-Whitney U test. The value of p<0.05 was considered statistically significant for differences.

Results: No statistically significant differences in MPAS were detected between the skeletal Class I and Class III groups. Within the Class III group, MPAS did not differ significantly between non-severe and severe subgroups. Regarding mandibular third-molar status, Class III subjects with a mandibular third molar exhibited significantly greater MPAS at RL6 and RL9 compared with those without a third molar. In the Class I group, MPAS values did not differ significantly between the third-molar and non-third-molar subgroups.

Conclusions: The MPAS did not differ significantly between skeletal Class I and Class III patients. Clinically, these findings highlight the importance of individualized, CBCT-based evaluation rather than reliance on generalized characteristics such as skeletal classification.

cone-beam computed tomography orthodontics mandibular posterior available space retromolar space

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Chailom K, Sirabanchongkran S, Tripuwabhrut K, Kuharattanachai K. Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients: Original articles. Oral Sci Rep [Internet]. 2026 Aug 07 [cited 2026 Aug 08];47(3):400-408. Available from: https://www.dent.cmu.ac.th/cmdj/frontend/web/?r=site/viewarticle&id=566

Chailom, K., Sirabanchongkran, S., Tripuwabhrut, K. & Kuharattanachai, K. (2026). Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients. Oral Sci Rep, 47(3), 400-408. Retrieved from: https://www.dent.cmu.ac.th/cmdj/frontend/web/?r=site/viewarticle&id=566

Chailom, K., Supassara Sirabanchongkran,Kanich Tripuwabhrut and Kachaphol Kuharattanachai. 2026. "Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients." Oral Sci Rep, 47(3), 400-408. https://www.dent.cmu.ac.th/cmdj/frontend/web/?r=site/viewarticle&id=566

Chailom, K. et al. 2026. 'Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients', Oral Sci Rep, 47(3), 400-408. Retrieved from https://www.dent.cmu.ac.th/cmdj/frontend/web/?r=site/viewarticle&id=566

Chailom, K., Sirabanchongkran, S., Tripuwabhrut, K. and Kuharattanachai, K. "Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients", Oral Sci Rep, vol.47, no. 3, pp. 400-408, Aug. 2026.

Chailom, K., Sirabanchongkran, S., Tripuwabhrut, K., et al. "Assessment of Mandibular Posterior Available Space in Skeletal Class I and Class III Malocclusion Patients." Oral Sci Rep, vol.47, no. 3, Aug. 2026, pp. 400-408, https://www.dent.cmu.ac.th/cmdj/frontend/web/?r=site/viewarticle&id=566