Crowding is another common manifestation of class1 malocclusion. Crowding usually occurs as a result of disproportion between tooth size and arch length. A relative decrease in arch length or an increase in tooth material can result in crowding.
Etiology of Crowding
A. Arch length tooth material discrepancies due to decreased arch length or an increase in tooth material.
B. Presence of supernumerary or extra teeth can result in eruption of their successors in an abnormal position and can result in a crowded arrangement of teeth.
C. Prolonged retention of deciduous teeth can result in eruption of their successors in an abnormal location. The presence of an over-retained deciduous tooth along with its permanent counterpart can cause crowding.
D. Abnormalities in size and shape of teeth can lead to crowded arch. Teeth that are abnormally large can predispose to crowding.
E. Premature loss of a deciduous tooth invariably results in drifting of adjacent teeth into the extraction space. An example of such a condition is the early loss of second deciduous molars. In these cases, the first permanent molar drifts into the extraction space. Thus the second premolars do not have adequate space to erupt and may do so in an abnormal position predisposing to crowding.
F. Late lower labial segment crowding occurs commonly in mid to late teens. This is noticed even in persons who had very nicely aligned teeth with no crowding or even mild spacing. However if a person has a very mild crowding to start with we can expect it to progressively worse during this period. A number of factors play a role in this lower late anterior crowding.
Clinical examination should be carried out to determine the extent and location of crowding. Model analysis can be of use in determining the amount of arch length- tooth material discrepancy. The possible cause for the crowding should also be determined.
Treatment of crowding Teeth
Mild incisor crowding may be seen in the mixed dentition phase due to presence of large permanent incisors and primary molars. Most minor crowding resolves spontaneously during transition from the deciduous to the mixed dentition phase.
Early loss of the primary mandibular canine is an indication of an arch length discrepancy. In these patients the mandibular incisors have to be maintained in place with a lingual arch to prevent them from tipping lingually and thereby increasing the possibility of crowding.
Another approach in children who exhibit moderate incisal crowding during mixed dentition is the use of leeway space. This is done by preventing the mesial movement of the permanent first molar and thereby utilizing this space to decrowd the anteriors. The position of the first permanent molar can be controlled with lingual arch.
A lip bumper can also be used for this purpose. It not only controls the position of molar, it can cause slight distal tipping of the molar and labial tipping of the incisors.
*Use of removable appliances-Once the provision for space is made; teeth can be moved to normal non-crowded positions by using removable appliances that incorporate coil springs, labial bow and canine retractors.
*Use of fixed appliances-Fixed appliances offer better control in treatment of crowding. Fixed appliances that make use of multilooped arch wire or resilient nickel-titanium wires are very effective in correction of crowding.