What Is Distraction Osteogenesis in Orthodontics?

Distraction osteogenesis (DO) allows for greater skeletal movements than can be achieved with conventional surgical techniques. It also reduces operative time and blood loss, eliminates the need for bone grafts, and may help improve postoperative stability. 

Hard tissue engineering is critical for adjusting and correcting craniofacial deformities that can occur due to birth defects, particularly where conventional orthognathic medical surgeries and bone grafting methods aren’t possible. 

Healing of a normal fracture occurs through a course of molecular and cellular events triggered in response to an injury. When such wounds occur, the ends of the bone are usually set and aligned to form a single continuous length of the bone. This woven bone then rebuilds and remodels itself into a more mature lamellar bone to restore the strength and function of the organ. 

During distraction osteogenesis, however, the use of mechanical force on the bone segments helps alter the repair process of the osteotomized bone sections, which is characteristic of bone healing, into a regenerative process. The success of new bone formation through distraction osteogenesis is influenced by the rate and rhythm of the separating forces.

Sequential phases in distraction osteogenesis (DO) are as follows:

• Osteotomy phase: Every osteotomy bone segment should contain an adequate number of viable osteocytes to start and propagate DO. Complete osteotomy rather than corticotomy is preferred on the grounds that the periosteum gives satisfactory osteoblastic activity in the well-vascularized craniofacial areas.
• Latency phase: The latency stage is the period that immediately follows the formation of osteotomy and is prescribed for 5-10 days. This prescribed period allows the organization of the tissue and formation of callus that bridge the gap between the two osteotomized bone surfaces.
• Distraction phase: The distraction period is where the application of distraction forces occurs. The distraction progresses with the active synthesis of fibrous tissue in the central regions and active mineralization at the ends until the required amount of length is achieved. The distraction process is normally carried out at the rate of 0.5-1 mm/day.
• Consolidation and remodeling phase: In this phase, bone maturation takes place and continues over a year or more before the structure of the newly shaped bone tissue is similar to that of the preexisting one and in which soft tissue adaptation occurs. Before the completion of this stage, the soft callus hardens, and the bone begins to rebuild into a more mature lamellar bone which is strong enough to function.

Advantages

• Allows better orthodontic movement
• Suitable for any age (reports have suggested that early mandibular distraction has been carried out to prevent tracheotomy in newborns with micrognathia that has been causing airway obstruction)
• Minimized need for orthognathic surgery and reduced complication rates
• Shorter hospital stays
• No bone graft required

Disadvantages

• Lack of precision
• Poor three-dimensional control
• Multiple daily outpatient visits required in some cases
• Moderate to severe pain during recovery
• Difficult access for orthodontist 
• Difficult plaque control
• Potential damage to temporomandibular joint due to incorrect vector orientation