The developed deciduous occlusion provides a good prediction for how the occlusions will develop in the future.
- A distal step of 1 mm or more invariably leads to a Class II molar relationship in the permanent dentition [Fröhlich 1961, Fröhlich 1962, Arya, Bishara 1988, Moyers].
- A flush terminal plane leads to Class II in about 40% of patients [Arya, Bishara 1988]. A flush terminal plane combined with a Class II canine relationship seems to indicate a higher risk of distal occlusion [Varrela].
- Lingually inclined upper deciduous incisors that are covered by the lower lip are likely to develop into Class II, div 2 in the permanent dentition [Leighton 1969].
- Patients with Class II Div 1 in the permanent dentition typically have a history of excessive upper lip protrusion and mandibular facial convexity already in the mixed dentition. [Bishara 1997]
- Class II occlusal relations (distal step, Class II deciduous canine relationship, excessive overjet) in the deciduous dentition) persist into the mixed dentition. [Baccetti 1997]
- Lack of adequate space in the deciduous dentition is a reliable indicator of treatment need [Leighton 1969, Leighton 1971, Leighton 1977]:
Interdental spacing in deciduous dentition
- Crowded: Chance of crowding in permanent dentition 100%
- 0 mm (no spacing): Chance of crowding in permanent dentition 66%
- 3 mm or less: Chance of crowding in permanent dentition 50%
- 3-5 mm: Chance of crowding in permanent dentition 20%
- 6 mm or more: Chance of crowding in permanent dentition 0%
Table adapted from McNamara JA Jr, Brudon WL. Orthodontics and dentofacial orthopedics. Chapter 3: Dentitional development, Ann Arbor (Mich): Needham Press; 2001.
Malocclusions tend to become more severe as the dentition develops
- Incidence of mandibular incisor crowding increases from 14 % at the age of 6 years to 51 % at 14 years of age [Barrow].
- Overbite and overjet typically increase by 1-2 mm when the permanent incisors erupt [Leighton 1969, Leighton 1971, Björk, Moorrees, Leighton 1975, Bergensen]. Later on they tend to decrease less than 1 mm [Björk, Bergersen].
- Incisor crowding or malalignment that is present when all permanent incisors have erupted, will probably remain or become more severe by the time all permanent teeth have erupted. [Moyers, Bell]
- If Class II div 1 is present at age 6, mandibular growth deficiency occurs between age 6 and 15. [Buschang]
- The prevelence of enlarged overjet, deep bite, class II and bilateral crossbite increases from age 6 to 10.[GlasI]
Excess overjet increase the risk of incisor trauma
- Children with an overjet larger than 3 mm are approximately twice as much at risk of injury to anterior teeth than children with an overjet smaller than 3 mm.[Nguyen]
- Overjet-related risk of incisor trauma may be reduced, if treatment is started before the permanent maxillary incisors have erupted. [Koroluk, Turpin]
- Untreated excess overjet may increase the risk of incisor trauma by up to 400%. [Norton, Schatz, Harrison]
- Early intervention can reduce the risk of trauma by up to 41% according to a Cochrane reviw. [Thriruvenkatachari]
Expert associations recommend early treatment when appropriate
The AAO recommends that every child undergoes an orthodontic check-up before the age of seven years. [VV] Early treatment may prevent more serious problems from developing and may make treatment at a later age shorter and less complicated. In some cases, early treatment can lead to results that may not be achievable after the face and jaws have finished growing. [WW]
According to the AAPD, “Guidance of eruption and development of the primary, mixed, and permanent dentitions is an integral component of comprehensive oral health care for all pediatric dental patients. … Early diagnosis and successful treatment of developing malocclusions can have both short-term and long-term benefits while achieving the goals of occlusal harmony and function and dentofacial esthetics.” [XX]
Juvenile growth spurt
There are substantial mandibular growth over a number of years before the onset of abolescence. [Bishara 2000] To utilize natural preodolescent growth, treatment can be started as early as the patient is able to cooperate [Bishara 2006]. In addition to the well-known pubertal growth spurt, the juvenile growth spurt provides another excellent opportunity to benefit from natural mandibular growth. Read more
If orthodontic treatment takes place before the apical portions of teeth are fully developed, the risk of relapse may be reduced. It has been postulated that orthodontic movement of an erupting tooth prevents relapse, because the supporting tissues are in a stage of proliferation and new fibres will be formed as the root develops. These new fibres will assist in maintaining the new tooth position. [Thilander 2000, Reitan 1960, Reitan 1967]
Compliance with wearing removable appliances is dependent on several factors. Cooperation may be better before adolescence and it has been suggested that treatment should begin after the age of 6 and be completed before the onset of puberty. [Tung, Southard]