Mandibular Distraction and Long-Term Dental Morbidity

Mandibular distraction osteogenesis (MDO) has become a popular intervention since it was described for correcting hypoplastic mandibles 25 years ago. However, it remains a relatively recent tool, and long-term complications are unclear. This study reports dental morbidities and mandibular morphological findings in patients who have undergone MDO.

Methods: This is a retrospective review of patients at our institution who have undergone MDO. Inclusion criteria involved patients with radiographs and orthodontic evaluation at early mixed and early permanent dental development. Data included demographic information, medical and surgical details, complications, and dental information, i.e. morphologic anomalies, missing teeth, aberrant anatomical locations, and buccal soft tissue redundancy. These findings are compared to normative controls.

Results: Twenty-two patients met inclusion criteria: 19 Caucasian (86.4%; 1 Hispanic, 2 African American), 13 male (59.1%), 12 patients with diagnosed syndromes (54.5%), and 9 patients with hemifacial microsomia (40.9%). On average, age at first MDO was 7.95 years; 9 patients required ≥1 distraction, 10 patients required tracheostomy. Average age at last follow up was 15.1 years.

On evaluation at early mixed dentition, only two patients had undergone MDO as an infant (<1yo) and had an image available for review. 3rd molars could not be visualized on either patient, but this is within age-appropriate dental development. Overall, of 22 mandibles at this age, all patients had some dental anomaly: there were a total of 8 missing molars (1st molar =2, 2nd molar =6; third molars not accounted for due to developmental stage), one impacted 1st molar, four ectopic 2nd molars, one ectopic 1st molar, five dysplastic molars (1st molar =4, 2nd molar =1), two missing 2nd premolars, two impacted premolars (1st premolar =1, 2nd premolar =1); one impacted canine and one impacted lateral incisor. Two patients had a V-shaped sigmoid notch.

On evaluation at early permanent dentition, there were 24 distracted hemi-mandibles (6 hemifacial microsomia patients), 3 with no pre-/molar anomalies (2 hemifacial, 1 PRS). A total of 17 molars were missing (1st molar =4, 2nd =4, 3rd =9), 2 impacted (1st molar =1, 2nd =1), 4 ectopic (1st molar =2, 2nd =2, 3rd =1), 2 dysplastic (1st molar =1, 3rd =1), and 3 with ankylosis (1st molar =2, 2nd =1). 7 premolars were missing (1st premolar =4, 2nd =3), 2 impacted (1st premolar). There was 1 missing canine, 3 impacted canines, 1 missing and 1 impacted lateral incisor, and one missing central incisor. Four patients had an aberrant V-shaped sigmoid notch.

Two patients had unfavorable buccal mucosal scarring; 3 patients had anterior open bites described in their history; none had facial nerve complications reported.

Conclusions: At age 13, the most common anomaly was a missing tooth, most likely the 3rd molar (38%), though this is also the most commonly missing tooth in the general population. Other teeth, such as other molars and premolars, were also commonly missing. Molars were also observed to be impacted, ectopic, dysplastic, or ankylotic.