BDS7120 Orthodontic Treatment Modalities- Functional Appliances PDF

Classification of removable appliances: Passive removable appliances Functional removable appliances Active (mechanical) removable appliances • Appliances that utilize, eliminate or guide the natural muscular forces and transmit them to the teeth and alveolar bone in a predetermined direction...

Classification of removable appliances: Passive removable appliances Functional removable appliances Active (mechanical) removable appliances • Appliances that utilize, eliminate or guide the natural muscular forces and transmit them to the teeth and alveolar bone in a predetermined direction, helped by the available growth, to correct a skeletal malocclusion. Monoblock Twin block Frankel appliance They are appliances that deliver a heavy force (300-500gm) “Orthopedic force” through using extra oral means (back of the head, chin and neck) to the basal bone to result in a skeletal effect. Face mask Headgear Chin cup Functional removable appliances • It is used in treating skeletal Class II malocclusion that is caused by a retrognathic mandible. • It consists of upper and lower acrylic splints fused together into a single block. Concept: To maintain mandible in a forward position to allow mandibular growth to occur. The mandible is kept in position by the long lingual flanges of the appliance. 1 Mandible is advanced 2 Muscle stretch 3 Condyle is out of fossa Sequence of events 4 Stimulates Mandibular growth 5 Restraining of maxilla • Acceleration of mandibular growth (stimulation of mandibular growth) • Restraint of maxillary growth (headgear effect) • Backward tipping of maxillary incisors. • Forward tipping of mandibular incisors (undesirable). • To avoid unfavorable forward tipping of mandibular incisors, acrylic is extended over the tips of these incisors (incisal capping). William Clark 1979. • The mandible is kept in position by bite blocks that interlock in occlusion to posture the mandible forwards. • The inclined planes of these blocks are set at approximately 70° with the height > 5 mm vertically. 1) Open bite tendency: leave the bite block contacting the posterior teeth 2) Deep bite: relieve the bite block to allow eruption of the lower molars to correct deep bite. 1. Easy to wear. “separate upper and lower pieces”. 2. Can allow the incorporation of expansion screws. • The degree of protrusion depends on the size of the overjet and the comfort of the patient. • In large overjet, protruding the mandible can be done in stages. Avoid shifting of the mandible during the advancement for bite registration. Options: 1. Procline the upper incisors into a Class II division 1 before starting functional appliances phase. “prefunctional phase”. 2. Use a modified Twin block appliance. “springs can be added palatal to upper incisors to procline them during the Twin block phase.” • Patient is instructed to wear the appliance for 12 hours “in monobloc appliance”, or full time “twin block appliance”. • The review appointments can be made at 6–10-week intervals. • If there is no progress this could be due to a number of factors: • Poor compliance • Lack of remaining growth Treatment is terminated when the incisors reach an edge to edge relationship “overcorrection” to allow for some relapse after the functional phase. Fixed appliance treatment can start afterwards. Monobloc Twin block Frankel appliance Frankel appliance Fränkel appliances tend to change the muscular and soft tissue environment of the jaws and therefore modify growth. Frankel appliance • This is achieved with the use of wires and acrylic shields to displace the cheeks and lips away from the teeth, as well as encouraging forwards posture of the mandible. Buccal shields Encourage passive expansion, deposition of bone laterally Removes pressure of lips Allows deposition of bone by stretching the periosteum Lip pads Buccal shields Encourage arch expansion Removes pressure from the upper lip and stretches the upper periosteum Lip pads • Due to compliance problems with removable functional appliances, fixed functional appliance were developed to allow for full time action. • Many types are available; the most popular is the Herbst appliance. Start early or late ? Early Late • 8-10 yrs “early mixed • Gold standard? “Late mixed/ early permanent dentition” 11-15 yrs dentition” • Successful, if there is • Temporarily successful, because of the availability of adequate growth remaining and has less relapse. growth BUT it suffers from Relapse because the disproportionate pattern of growth continues. Start early or late ? Early Late • 8-10 yrs “early mixed dentition” “Late mixed/ early permanent dentition” 11-15 yrs • Treatment will be in 2 or 3 phases “high cost, more burden and longer total time”. • Lower cost • Can be a “One phase treatment”. • Positive impact on self esteem. • BUT: Missing the psychological benefits of early treatment. • Class II mandibular deficiency is best treated just before the pubertal growth spurt. • Chronological age is a poor indicator for the pubertal growth spurt. • Radiographic indicators are better to determine the ideal treatment time. G H They are appliances that deliver a heavy force (300-500gm) “Orthopedic force” through using extra oral means (back of the head, chin and neck) to the basal bone to result in a skeletal effect. Face mask Headgear Chin cup Face mask • For treatment of skeletal Class III due to maxillary deficiency. • Best time for treatment CS1, CS2 “pre-pubertal stage” because of the early ossification of the maxillary sutures. Chin cup • For treatment of skeletal Class III due to mandibular excess. • Treatment is best performed starting CS3-CS4 and MUST continue until the age of 16-18 years to avoid relapse that might occur after the residual mandibular growth. Headgear • Used for treatment of patients with skeletal Class II due to maxillary excess. • It acts through the restriction of further maxillary growth by application of heavy orthopedic forces in a backward direction. Headgear 1. A face bow. 2. Means of intraoral attachment. 3. Head cap/ neck strap. 4. Means of elastic traction. Increased Headgear vertical proportions High or occipital-pull Average vertical proportions Straight or combi-pull Decreased vertical proportions Low or cervical-pull Students are advised to review teaching from lecture 3 (craniofacial growth). In addition, they are advised to read relevant sections of the following texts: • Mitchell L. An introduction to orthodontics; 4th edition, Oxford University Press • Gill D. Orthodontics at a glance. Blackwell Munksgaard