Experimental changes of the mandible: a serial roentgenographic study

Area of Science:

• Veterinary Anatomy
• Developmental Biology
• Orthodontics

Background:

• Understanding mandibular growth is crucial for addressing craniofacial abnormalities.
• Previous studies have utilized various methods to track bone development.

Purpose of the Study:

• To investigate the specific patterns and sites of mandibular bone growth in Hampshire pigs.
• To differentiate between interstitial and appositional growth mechanisms in the mandible.

Main Methods:

• Serial cephalometric radiography was employed on nine Hampshire pigs aged 8 to 20 weeks.
• Metallic implants were used as internal markers to superimpose serial radiographs accurately.
• Analysis focused on determining growth sites, increments, and directional changes.

Main Results:

• No evidence of interstitial bone growth was found; the distance between implants remained stable.
• Significant appositional growth occurred at the posterior, inferior, anterior, and alveolar borders, as well as lateral surfaces.
• The condyle and posterior border were the most active growth sites, while the anterior ramus border showed resorption.

Conclusions:

• Mandibular growth is primarily appositional, with distinct contributions from various borders and the condyle.
• Resorption at the anterior ramus border plays a key role in mandibular shape transformation, converting ramus to body.
• While the mandibular body is relatively stable, alveolar bone and teeth positions undergo continuous change.