A 22-year follow-up of the nonsurgical expansion of maxillary and mandibular arches in a young adult: Are the outcomes stable, relapsed, or unstable with aging?

•Aging can cause treatment results to change over time.•An adult patient with constricted maxillary and mandibular arches was treated.•Results of mandibular and semirapid maxillary expansion were followed for 22 years.

Adult maxillary and mandible arch expansion without a surgical approach can be uncertain when long-term stability is considered. This case report describes the treatment of a 19-year-old woman with an Angle Class I malocclusion with constricted maxillary and mandibular arches. The patient's main complaint was mandibular anterior crowding. The treatment plan included expansion of the mandibular arch concurrent with semirapid maxillary expansion. An edgewise appliance was used to adjust the final occlusion. Smile esthetics and dental alignment were improved without straightening the profile. This outcome was followed up with serial dental casts for 22 years after treatment. At the end of that period, the occlusion and tooth alignment were clinically satisfactory, further supported by mandibular fixed retention. However, the transverse widths were continuously and gradually reduced over time, superposing orthodontic transverse relapse and natural arch constriction caused by aging.