Development of dental arches

Each of us is born with a genetic background inherited from our parents but also with particular traits that differentiate us from other individuals.

This is how variations in jawbone development arise.

Normally, the jawbone and mandible are in harmony: the jaw circumscribes the mandible.

If incongruities occur in terms of size or bone structure, the normal development of the teeth will be hindered, with repercussions on the performance of all functions.

The role of heredity

  • The shape, particular characters and volume of teeth and jaws are hereditarily determined. In many cases, the mother’s traits may be inherited for one arch and the father’s traits for the other, which often leads to large differences in size that are incompatible with achieving a proper occlusion.

  • Timing of tooth eruption: around 6 months of age, the temporary teeth begin to erupt in the following order: incisors, first molars, canines and second molars.

Mixed dentition is present between the ages of 6 and 12 and is characterized by the presence of both temporary and permanent teeth, which will gradually replace the former.

We may encounter situations where the eruption process is delayed, genetically or the order is altered.

We also have the situation of accelerated eruption of temporary teeth, which also leads to their premature loss.

  • Numerical disorders: the most common situations are those in which we have fewer dental units than normal. Either there are no tooth buds from the embryonic stage of development, or they are embedded in the bone and normal eruption is not possible. We usually find a lack of buds for the lateral incisors, the second premolar and the last molar, or the wisdom tooth. Supernumerary teeth are called mesiodens if they are between the two central incisors.

  • Dental diastema: may occur during the replacement of temporary teeth by permanent teeth, in which case the diastema is transient, false, and disappears after complete replacement. Heredity is only responsible for true diastema, which persists even after all dental units in the oral cavity are permanent. It may be due to a greater thickening of the bony septum in the interincisal region or to an interdental papilla with an abnormal insertion.

Effects of hereditary malformations on jaw development

  • Down syndrome: the upper jaw is underdeveloped, so that it is frequently circumscribed by the mandible, with serious implications for occlusion ratios. The size of the tongue is larger and the dental arches are pushed anteriorly. Tooth size is generally smaller than normal.

  • Turner syndrome: is characterized by an overall underdevelopment of the body. At the oral level, the mandible is underdeveloped and set back posteriorly, so that the mouth always remains ajar, with consequences for self-care.

  • Trisomy 13: is characterized by a short stature of the patient, with abnormalities of the nasal bones often accompanied by cleft palate.

The treatment is an attempt to improve and correct the aesthetics and functionality of the masticatory apparatus. Application of the therapy and close follow-up of the results gives an improved quality of life.

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