Class III Underbite Treat now or do Surgery?

Measurements

Cephalometric values before and after treatment
Measure	Norm	Pre	Post
SNA	82	80	80
SNB	80	80	79
ANB	2	0	1
Wits	0	-2	0
SN-MP	32	33	38
U1-SN	102	109	107
L1-MP	90	89	75
Overjet (mm)	2–3	-2	2
Overbite (mm)	2–3	2	2

Treatment

Objectives. Wait until peak mandibular growth has occurred, then distalize the lower right molars to camouflage the mandibular asymmetry.

Plan. Due to the patient’s remaining mandibular growth and underlying Class III/asymmetric growth pattern, defer comprehensive orthodontic treatment until approximately one year after peak mandibular growth has passed and mandibular growth has significantly slowed. Since growth has stabilized sufficiently, we will initiate treatment with the goal of camouflaging the skeletal discrepancy and mandibular asymmetry. Treatment will include: Sequential distalization of the lower molars, beginning on the right side and distalizing the mandibular teeth one at a time to help correct the asymmetric Class III relationship. Bilateral Class III elastics during treatment to assist with anteroposterior correction and support the distalization mechanics. Continue sequential distalization and alignment until the best achievable dental midline, overjet, overbite, and Class I occlusal relationship are obtained within the limits of orthodontic camouflage. Closely monitor facial growth, mandibular position, and occlusion throughout treatment. Retention / Residual Growth Following completion of active treatment, use nighttime Class III elastics in conjunction with retainers during the period of potential residual mandibular growth. The elastics will be used to help maintain the corrected dental relationship and reduce the effect of any remaining Class III growth tendency on the occlusion. Long-term stability will depend in part on the amount and direction of any residual mandibular growth.

Appliances and materials

Invisalign
Class III elastics — Cut outs on the L3s and Mesial of the U6s

Progress records

Outcome

We successfully camouflaged the mandibular asymmetry and Class III underbite by sequentially distalizing the lower teeth on the right side. The patient finished with a Class I dental relationship, positive overjet, and appropriate overbite, with good coordination of the upper and lower arches. Mild facial asymmetry remains due to the underlying skeletal asymmetry, but the patient is comfortable with his facial appearance and pleased with the result. Overall, the dental goals were achieved successfully despite the residual skeletal discrepancy. Treatment Summary Treatment duration: 12 months Initial aligners: 47 Refinement: 19 aligners Number of visits: 6 Aligner change interval: Every 7 days

Retention

Fixed retainers: Upper lateral-to-lateral (U2–2) and lower canine-to-canine (L3–3). Essix retainers: Fabricated with Class III elastic slits. Continue nighttime retainer wear with Class III elastics as indicated through approximately age 18 while residual mandibular growth is monitored. Reassess growth and occlusion approximately every 6–10 months and adjust retention or elastic wear if needed.