Abstract
ObjectivesTo assess early versus late treatment of Class III syndrome for skeletal and dental differences.MethodsThirty-eight Class III patients treated with a chincup were retrospectively analyzed. Baseline data were obtained by reviewing pretreatment (T0) anamnestic records, cephalograms, and casts. The cases were assigned to an early or a late treatment group based on age at T0 (up to 9 years or older than 9 years but before the pubertal growth spurt). Both groups were further compared based on posttreatment data (T1) and long-term follow-up data collected approximately 25 years after treatment (T2).ResultsEarly treatment was successful in 74% and late treatment in 67% of cases. More failures were noted among male patients. The late treatment group was characterized post therapeutically by significantly more pronounced skeletal parameters of jaw size relative to normal Class I values; in addition, a greater skeletal discrepancy between maxilla and mandible, higher values for mandibular length, Cond-Pog, ramus height, overjet, anterior posterior dysplasia indicator (APDI), lower anterior face height, and gonial angle were measured at T1. The angle between the AB line and mandibular plane was found to be larger at T0, T1, and T2, as well as more pronounced camouflage positions of the lower anterior teeth at T0. The early treatment group was found to exhibit greater amounts of negative overjet at T0 but more effective correction at T1.ConclusionsEarly treatment of Class III syndrome resulted in greater skeletal changes with less dental compensation.
Highlights
Already in early childhood, the growth of the skull reaches a very advanced stage that will only be followed by limited additional growth changes of certain structures in later years [20,21,22]
Several studies [5, 12] have described greater skeletal and dental changes toward Class I by early orthodontic treatment than by later treatment, with early treatment resulting in gonial angle values similar to that found in Class I individuals while, in cases of late treatment, the skeletal disharmony was successfully corrected by camouflage [12]
Outcomes were successful in 74% of cases in the early versus 67% in the late treatment group
Summary
The growth of the skull reaches a very advanced stage that will only be followed by limited additional growth changes of certain structures in later years [20,21,22]. According to Mitani and Fukazawa [13] and Mitani and Sakamoto [14], a chincup influences mandibular growth and morphology despite the underlying genetic control; the original pattern will subsequently return, but its extent will depend on the amount of residual growth and on the change already achieved by treatment. We designed this retrospective study of Class III patients to assess dental and skeletal differences between patient being treated early or late and the treatmentrelated changes of these parameters over time
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