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Here are a few important points about patients’ growth and development as it relates to orthodontics:
- Certain types of orthodontic problems can only be treated successfully if favorable growth exists (more particularly significant imbalances between the jaws) if jaw surgery is to be avoided.
Fig. 1 – Jaw growth potential helps the orthodontist to correct malocclusions.
- Deficient or excessive growth can influence the treatment plan and the quality of the results obtained.
- Changes caused by late growth can disrupt the best treatment plan.
- Normal growth observed in someone can very well not continue like this. If growth of a jaw becomes disproportional compared to that of the other the jaw, the relationship between the jaws may be affected and the treatment objectives may not be achieved.
- Growth (excessive or deficient) can force the orthodontist to modify a treatment plan and propose compromises or alternatives.
- Excessive growth that occurs after orthodontic corrections are made can affect the stability of the results by changing the relationship between the teeth and jaws.
- Although growth is essential for the success of many treatments, growth alone will not correct significant occlusion problems.
- Jaw growth occurs mostly at the back to allow the permanent molars to erupt and this does not help the problems affecting the anterior teeth.
- When a dental malocclusion also contains a skeletal component or a jaw imbalance, it is important to use the growth potential to attempt to restore balance in the jaw relationship.
- Without growth, jaw surgery may be necessary, so it is important to intervene early in patients presenting a significant discrepancy between the jaws.
Bad habits, such as chronic thumb sucking, an excessive pressure of the tongue against the teeth or a non-standard skeletal development, may also make an orthodontic treatment harder and/or compromise stability during or after the retention period.
Dental development and eruption of teeth in a young girl from 5 to 12 years of age
Growth still occurs, will it correct the occlusion problem?
Importance of growth for orthodontic corrections:
- Even though it is preferable to intervene during an active growth period to correct skeletal imbalances between the jaws, growth alone will not be able to correct a malocclusion.
- Growth is essential to correct certain types of problems, but an orthodontic intervention is also necessary to correct most of dental malocclusions.
- Using orthodontic appliances during a treatment makes it possible to use the growth potential optimally to try to obtain a better relationship between the jaws.
- In certain cases where the growth pattern is really unfavorable or abnormal (for instance, when the lower jaw bites in front of the upper jaw – Class III malocclusion), any additional growth can in fact worsen the problem.
- Certain appliances, such as “functional” appliances, may be used, in addition to “braces”, to help reduce the gap between the jaws during growth. To learn more about “functional” appliances.
- Without growth, significant discrepancies between the jaws may require orthognathic surgery.
- It is thus important that discrepancy problems between the jaws be evaluated early by an orthodontist. A first orthodontic evaluation should be done by age 7.
Will growth help?
- When there is not enough space and the child’s growth still occurs, one could be tempted to believe that growth could fix the lack of space by allowing the jaws to become “longer” and thus give more space to teeth. This concept is partially true… and false!
- During infancy, jaws grow in 3 dimensions and allow the temporary teeth to progressively erupt and position themselves in the dental arches. The temporary dentition is completed toward the age of ± 30 months and will not start to be replaced by the permanent or definitive dentition until several years later toward ± 6-7 years of age. During this time, spaces normally appear between the anterior teeth, a sign that the jaw size increases. Posterior growth allows more teeth (temporary molars) to progressively erupt in the dental arch.
- However, once the permanent first molars erupt and are in place, the length of the dental arches at the front of these molars will not increase anymore and can even decrease as the posterior temporary teeth shed and are replaced by narrower teeth. It is precisely in this critical area that most space is lacking!
- However, growth can help the back of the dental arches by creating space to accommodate the second molars located behind the first molars (see Figure 1 above). This growth is essential for the molars to erupt. If it were really sufficient, it could even allow the eruption of the third molars (wisdom teeth) but this is uncommon.
The radiographs below illustrate this phenomenon:
(A) This 8-year-old girl’s posterior permanent teeth do not have enough space to erupt. The residual jaw growth will occur behind the first molars (red dotted line) in the direction pointed by the arrows.
(B) This 9-year-old boy has already lost a lot of space in the areas indicated by the yellow asterisks (*). The upper first molars (blue *) have even migrated forward, shortening the length of the dental arch. Jaw growth will not help this lack of space since it occurs behind the permanent molars.
These examples show how important it is to preserve the available space during the eruption of teeth and the fact that growth helps… but not necessarily where dental crowding problems and the lack of space are located. Adequate supervision during dental development will make it possible to minimize space and eruption problems.
Growth does not occur equally in all dimensions!
- The evaluation of a dentition and an occlusion has to be made in 3 dimensions; length, width and height. One could believe that jaws grow equally and synchronously in all these dimensions but… it is not the case.
- Width is the first growth dimension to stop and it occurs relatively early (before 4-5 years of age depending on the cases). It is the reason why, when there are imbalances in that dimension, it is recommended to intervene early to restore balance in the width of jaws. This is the goal of rapid maxillary expansion that can be performed as early as 4, 5, 6 years of age for certain of the most severe cases.
- Jaws continue to grow in length and height until the patient becomes a teenager and this offers a greater potential for orthodontic corrections.
- At 9 years of age, mandibular antero-posterior (in length) growth is 85% completed in boys and 90% in girls. It will be 98% completed as early as 15 years of age in girls, whereas this percentage will only be reached at 19 years of age in boys. 1 This means that, if we hope to correct a mandibular imbalance in length, like retrognathia (short mandible or a mandible that is too far back), the treatment needs to be started while there is still enough growth potential left, which is earlier for girls.
At what age do teeth erupt and in which sequence?
To know the average age of the eruption of teeth and their sequence, consult this section.
1- Wolford et Al. , O. Surg., 1973 – 45:3
