MESIAL DRIFT OF TEETH
Our teeth are arranged in form of an arch commonly resembling a U or V shape. Throughout life, our teeth move forward towards the midline which is called physiological drift. This is a very common phenomenon.
Mesial drift can be defined as the tendency of teeth to move in a mesial direction within the arch with an aim to maintain interproximal contact between teeth.
While chewing, the teeth rub against each other on the sides at the contact points, resulting in interproximal wear off and that space which is created is filled by mesial/ forward movement of the teeth to re-establish contact.
Mesial drift can be because of physiological, pathological, or induced reasons (e.g.: in the case of orthodontic tooth movement to obtain desired results during treatment).
CLASSIFICATION OF MESIAL DRIFT BY ANGLE:
Mesial drifting is multifactorial and causes the collapse of the dental arch. And this collapse indicates one of the following:-
Mesial Drift of buccal teeth in relation to their alveolar process
Mesial Drift in relation to maxillary and mandibular denture bases.
Mesial Drift in relation to Cranium. Such cases are usually called bimaxillary protrusion.
Here in this article, we will be discussing mainly the mesial drift of buccal teeth in relation to their alveolar process.
WHICH TEETH MOVE IN THE MESIAL DIRECTION AND IN THE DISTAL DIRECTION IN THE ARCH?
Kronfeld’s theory states that there are neutral areas located in the following:
Between the bicuspids in the maxilla
Just mesial to the 1st molars in the mandible.
Based on that theory, the following conclusion can be drawn:
Teeth anterior to the neutral area have a tendency to drift distally
Teeth posterior to the neutral area have a tendency to drift mesially.
The following factors are considered to be contributing towards teeth drifting mesially-
Heredity
Premature loss of primary teeth and inadequate space maintenance.
Contraction of trans-septal fibers-
Transseptal fibers draw neighboring teeth together and maintain them in contact. They are also capable of adaptation. Contraction of these fibers plays a major role in the interproximal teeth contact.
The adaptability of the bone tissue-
Bone is a very adaptable tissue because of its ability to resorption and apposition. The pressure side on the periodontal ligament causes resorption and the pull on the fibers causes apposition. Therefore as the contact wears off the tooth tends to move in a mesial direction to maintain contact.
Anterior component of the occlusal force-
Most of the teeth have a mesial inclination. When the teeth are clenched, an anteriorly directed force is created from the summation of the intercuspal planes causing mesial migration of teeth. If the opposing teeth are missing, there is an absence of biting force thus the mesial migration is slowed down. The forces can also be enhanced or reversed by selectively grinding the cusps resulting in the slowing of the mesial migration.
Pressure from the soft tissues:
Pressure generated by the musculature of the check and tongue does influence the tooth position even if it does not cause the tooth movement. Though not a significant role, it does play a minor role in mesial drifting.
The rate of physiological drift of teeth depends upon health, dietary factors, and age. It usually varies from 0.05 to 0.7mm per year.
Extractions of teeth due to dental decay.
Extractions of teeth for strategic mesial drifting for treatment needs.
Eruption of 3rd molars can put a forward push pressure on teeth leading to mesial migration.
The presence of pathologies like cysts or tumors can push the teeth in a mesial direction causing pathological mesial movement of teeth.
Dental trauma, facial fractures, and avulsions.
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