In addition to the well-known pubertal growth spurt, the juvenile growth spurt provides another excellent opportunity to benefit from natural mandibular growth.
Figure adapted from Woodside DG. In Salzmann JA, ed. Orthodontics in Daily Practice. Philadelphia: JB Lippincott; 1974. See also Proffi t WR, et al. 2007, Contemporary orthodontics, 3th edn., Chapter 4: Later Stages of Development, Figure 4-6, St Louis, Missouri, Mosby Elsevier.
As the figures show, growth velocity varies during growth with peaks at the juvenile and pubertal growth spurts. The timing of the growth spurts vary from patient to patient. Because of this variation, the average curves are smoother whereby the juvenile and pubertal growth spurt peaks are not as prominent as in the curve of a single patient. The individual variability makes “catching” a growth spurt challenging even if skeletal indicators can be used in the prediction. By treating early, you can benefit from two growth peaks instead of just one.
According to the University of Michigan Growth Study, which measured annual growth between the age of 6 and 16, girls’ mandibles grow on average 5.8mm (Condylion – Gnathion) between the age of 6 and 8 years. This is more than in any subsequent two-year period. For boys, the growth between the age of 7 and 9 years is 6.4mm, which is very close to the pubertal peaks of 12-14 years (6.8mm) and 15-16 years (7.1mm).
Data from Riolo ML, et al. An Atlas of Craniofacial Growth. Ann Arbor, Mich: University of Michigan, Center of Human Growth and Development 1974
Increase in Gonion – Pogonion
Increase in Condylion – Gnathion
Data from Riolo ML, et al. An Atlas of Craniofacial Growth. Ann Arbor, Mich: University of Michigan, Center of Human Growth and Development 1974
See also Proffi t WR, et al. 2007, Contemporary orthodontics, 3th edn., Chapter 4: Later Stages of Development, Table 4-3, St Louis, Missouri, Mosby Elsevier