Immediate versus delayed midface distraction in a primate model using a new intraoral internal device

Area of Science:

• Craniofacial surgery
• Orthognathic surgery
• Distraction osteogenesis

Background:

• Severe midface retrusion and maxillary scarring pose challenges in craniofacial reconstruction.
• Distraction osteogenesis theoretically offers reduced relapse rates for significant skeletal advancements.

Purpose of the Study:

• To evaluate a novel low-profile, intraoral device for midface distraction at the Le Fort I level.
• To compare the efficacy of immediate versus delayed distraction protocols on maxillary relapse.

Main Methods:

• A modified Le Fort I osteotomy and intraoral device placement were performed in four rhesus monkeys.
• Group 1: Immediate distraction (10mm intraoperative, 10mm postoperative). Group 2: Delayed distraction (20mm postoperative after 5-day lag).
• Distraction occurred at 1mm/day, devices removed 6 weeks post-distraction. Serial cephalograms, dental models, and histological analyses were used.

Main Results:

• No evidence of relapse was observed in either immediate or delayed distraction groups at 6 months post-distraction.
• Histologic, ultrastructural, and dry skull analyses revealed no significant differences in regenerate bone quality between groups.
• The intraoral device facilitated significant midface advancement without additional incisions or osteotomies.

Conclusions:

• A new internal, intraoral device is effective for midface advancement via distraction osteogenesis.
• Immediate distraction is a viable option, potentially shortening the treatment period without compromising outcomes.
• This device offers advantages over external or more invasive internal systems.