The Indications and Treatment Planning of the Distraction Devices 2

Indication

IndicationWide variation in these days Hypoplastic Mandible Missing bone as a consequency of pathology Craniofacial microsomia Micrognathia Midface deficiency

Indication Calvarial expansion in craniosynostosis Severe resorbed alveolar bone Dental implant placement Alveolar cleft Periodontal ligament distraction Pediatric sleep apnea

Hypoplastic mandible, Hemifacial Microsomia, Micrognathia. Congenital anormaly Pierr Robin syndrome, Bliateral microsomia, Treacher Collin syndrome, Nagars syndrome, etc.

Severe malocclusion especially Class II occlusal relation.

Hypoplastic mandible, Hemifacial Microsomia, Micrognathia. Classification of Mandibular Hypoplasia (Pruzanski)

Grade 1 : hypoplasia affects only the gonial angleGrade 2A : the angle and ascending ramus are affected Grade 2B : hypoplasia is more severe and affects the angle and ascending ramus Grade 3 : complete absence of the ramus and condyle

Mn lengthening and widening

Missing bones as a sequence of pathology Bone Transport

The gradual movement of a free segment of bone (transport segment or transport disk) across the osseous defect

Missing bones as a sequence of pathologyVariations

Neocondyle construction Cleft palate reconstruction Velopharyngeal insuficiency.

Midface deficiency midface deficiency, craniofacial dysplasias, facial clefts.

Rigid external distraction (RED) system Three-Dimensional Midface distraction device Internal distraction device

Calvarial expansion in craniosynostosis Conventional bone graft method reveals the insufficiency of quantity of bone and dead space occuring leading to postoperative infection, bone resorption, and relapse.

patients with complex or reccurent abnormalitie resulting in limited craniofacial growth

Severe resorbed alveolar bone and dental implant placement Atrophic alveolar process Vertical and horizontal distracton is used.

Alveolar cleft Patients with insufficien secondary bone alveolar graft

Vertical osteotomy is applied on pre-grafted bone and miniplate must be fastened under the nasal mucosa.

Periodontal ligament distraction. The movement of canine after extraction of premolar tooth.

Rapid canine movements is for the adult patients required short treatment times and maximum anchorage construction

Pediatric sleep apnea. For the infants and late childhoods with OSAS caused by mandibular hypoplasia, distraction devices can eliminate the necessity for tracheostomy and correct feeding and esthetic problems.

Treatment planning of distraction device.

Patient selection Patient age. Sex. Metabolic disturbance of bone. Problem of breathing and food intaking, Susceptibility to infection. Psychosocial stability. Skin texture (kelloid),

Considering Factor Surgical correction, Potential for the future skeletal growth and developement Need for overcorrection Possible future operation.

Specific distraction related decisions Osteotomy design and location Selection of a distraction device Determination of the distraction vectorDuration of the latency periodRate and rhythm of distractionDuration of the consolidation period.

Distraction Device Selection External or internal Deistraction Devices ?

How long distance should practicer expect?

How can distracted bone move?

External Deistraction Devices Advantage : Excellent control of bone segment movement available in longer lengths Easier to place, maintain, replace and remove.

Disadvantage Scarring Poor acceptance by patients

Internal Distraction Devices Advantage Not produce facial scarring Negative psychologic effect of external devices.

Disadvantage Difficult to place High risk of injury to anatomic structure. Second surgical procedure is necessary to remove the devices

Lengthening Capabilities The actual bone distraction, which is usually less than anticipated and difficult to predict prior to distraction. Soft tissue interference. Vector of ostetomy line and device.

Direction of Distraction Unidirectional or multidirectional?

Decision of the vector.Distraction Device Orientation Influence of Masticatory MusclesOcclusal Interferences Distraction Device Acivation Orthodontic/Orthopedic forces

Distraction Device OrientationVertical distraction : parallel to occlusal planeHorizontal distraction : true AP advanceOblique distraction : Vertical and horizontal movement simultaneously.

Influence of Masticatory Muscles Induced recurrent episodic forces Soft tissue traction due to physiologic muscle activity exerted contribute to distal segment directional instability. Such movement can be altered by making adjustment in sequence and amount of activation of the multidirectionla device

Occlusal Interferences Posterior occlusal interferences Stepping posterior teeth off of the occlusal plane Utilization or biteplane or biteblock appliances, orthodontic adjustment, occlusal equibrium.. Anterior occlusal interference Advancing, proclining, intruding the maxillary anterior teeth. Using biteplane of biteblock

Distraction Device Acivation In saggital plane ~Rotation of the entire mandible around the axis located at the condyle open or close the bite anteriorlly ~ Reduces the anteroposterior length of the mandible and must be accompanied by additional linear distraction In transverse plane ~ Affected by the resistance of TMJ posteriorly, symphysis anteriorly ~ Proximal (condylar) segment is smaller, so less resistant to reactive forces, more dramatically affected.

Orthodontic/Orthopedic forces

During the active distraction phase and consolidation phase ~ Intermaxillary elastics, headgear, functional appliances

Future growth and Overcorrection skeletal age and age and future growth potential must be considered. ~ If future growth is expected to be deficient, overcorrection may be performed ~ Must consider psychosocial impact, race, sex, facial skeleton maturity ~ The existing growth pattern may be maintained and the discrepancy may resurface again with time.

Presurgical Orthodontic Preparation Evaluation of the dentition and its relation to the projected skeletal changes.Elemination of dental malrelationships

Tooth position and maxillary width should enhance distraction, not inhibit it. Fabrication and utilization of distraction stabilization appliance

Orthodontic Management during distraction and consolidation

To direct the distal mandibular segment toward its planned postdistraction position, thereby improving the final treatment result ~ Interarch elastic traction is useful for the control of anterior distal segment movement in excess of what is desired especially excessively oblique device placement.

Postconsolidation orthodontic therapy To support new bone at the distraction gap.

Bilateral Distraction ~ In anticipation of a future mandibular growth deficiency. ~ Guidance of eruption and alignment of the dentition ~ Growing children planned future orthognathic surgery or distraction

Postconsolidation orthodontic therapyUnilateral distraction: Occlusal plane management Correction of dental midline Correction of the maxillomandibular transverse disharmony If closing of the posterio openbite is failed, correction of the occlusal canting cannot be possible. In this case, surgical correction of the compensated occlusal plane (bimaxillary osteotomy) can be considered.