PubMed · 9852838
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X Calvez. 1998. The universal bite jumper.. https://pubmed.ncbi.nlm.nih.gov/9852838/
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An asymmetrically activated lingual arch appliance enables rapid, unilateral molar distalization in the mandible without active patient compliance. Using the segmented arch technique, the biomechanics involve only the tooth moved, in accordance with the 2-tooth concept, with a large, multi-rooted tooth segment acting as an anchoring unit. The anchorage system requires no maxillary involvement.
In present-day orthodontics there is an increasing call for therapeutic procedures and appliances allowing those delivering the treatment maximum independence from patient cooperation. This requires both the development of new therapeutic appliances and the optimization of existing ones (via modification). The present study aims to analyze the therapeutic outcomes obtained by using a pendulum appliance (distal screw and integrated molar uprighting activation), modified and independent of patient cooperation. The dentoalveolar and skeletal outcomes and secondary outcomes were observed in 50 children and adolescents. The dentoalveolar outcomes were as follows: 72.5% of the clinically visible increase in space were gained by distal molar movement and 27.5% by mesialization of the anterior segment. The molars showed slight distal tipping and extrusion, while the incisors showed slight labial tipping. In terms of time, the molars were moved distally by an average of 0.67 mm per month. Skeletal changes taking place during treatment using the pendulum appliance are negligible. Further advantages of the pendulum appliance are independence from patient cooperation and good acceptance by patients.
Understanding mechanisms of action for orthopedic appliances is critical for orthodontists who hope to treat and retain the achieved corrections in patients with initial Class II mandibular retrognathism. That knowledge can help orthodontists produce clinically significant bone formation and avoid compression at the condyle-glenoid fossa region. It also assists us to understand the differences between short-term and long-term treatment results. It was previously thought that increased activity in the postural masticatory muscles was the key to promoting condyle-glenoid fossa growth. By analyzing results from several studies, we postulate that growth modification is associated with decreased activity, which leads to our nonmuscular hypothesis. This premise has its foundation on 3 key specific findings: significant glenoid fossa bone formation occurs during treatment that includes mandibular displacement; glenoid fossa modification is a result of the stretch forces of the retrodiskal tissues, capsule, and altered flow of viscous synovium; observations that glenoid fossa bone formation takes place a distance from the soft tissue attachment. The latter observation is explained by transduction or referral of forces. Evidence is presented, therefore, that the 3 trigger switches for glenoid fossa growth can similarly initiate short-term condylar growth modifications because the 2 structures are contiguous. These are displacement, several direct viscoelastic connections, and transduction of forces. Histologic evidence further shows that stretched retrodiskal tissues also insert directly into the condylar head's fibrocartilaginous layer. The impact of the viscoelastic tissues may be highly significant and should be considered along with the standard skeletal, dental, neuromuscular, and age factors that influence condyle-glenoid fossa growth with orthopedic advancement. These biodynamic factors are also capable of reversing effects of treatment on mandibular growth direction, size, and morphology. Relapse occurs as a result of release of the condyle and ensuing compression against the newly proliferated retrodiskal tissues together with the reactivation of muscle activity. To describe condyle-glenoid fossa growth modification, an analogy is made to a light bulb on a dimmer switch. The condyle illuminates in treatment, dims down in the retention period, to near base levels over the long-term.