Correcting Crowding and Cross-bites 
by J. Chris Martin, D.M.D.

For children, the number one dental concern remains cavities, dental decay. For their parents and their dentist, preventing cavities in children’s teeth is the highest goal. Physically and emotionally, preventing cavities is easier for everyone. When preventing cavities fails us, repair of cavities becomes the goal. Wishfully, the preventing and repairing of dental decay would be the only large chores in dentistry for children. But another concern begins when the permanent incisors replace the primary incisors, which is called crowding. Because the permanent incisors are routinely larger than the primary incisors, the new teeth must have spacing between primary teeth to erupt into, if they are to reside in proper, straight, arch alignment. Since our tooth sizes and jaw sizes are mostly genetically determined, prevention of crowding is not very feasible. Although we cannot change our genetics, dentists can treat crowding in a variety of ways for children who exhibit crowding as the permanent incisors erupt (see photos 1 & 2).

The lower permanent incisors erupt about six months before the upper incisors, and they are normally constrained within the confines of the upper teeth. Thus, the lower incisors often demonstrate crowding first, by erupting out of line away from the upper incisors toward the tongue. When the lower primary incisor remains in place while the permanent incisor erupts out of place toward the tongue then the visual effect is a double row of teeth. Relief from this crowding can be obtained by removing the primary incisor in front of the permanent incisor. If x-rays and measurements of the teeth and spaces in the mouth indicate an additional lack of space, then removal of the adjacent primary incisors may be necessary for the permanent incisor to move forward into its proper place. Conversely, in circumstances of less crowding than extraction of primary teeth would warrant, a dentist can reduce the size of adjacent primary teeth to allow the crowded permanent incisor more space to move into alignment. Because the tongue exerts a steady forward force on the lower incisors, the creation of enough space for a lower incisor crowded toward the tongue usually shows obvious improvement in a few months time. If more certain and swifter alignment of incisors is desired then the use of dental devices which can move teeth directly can be employed. While extracting or reducing the size of baby teeth to relieve crowding for permanent teeth can improve the appearance of teeth during the years when permanent and primary teeth sit side by side, eventually the fact of crowding must be resolved with permanent tooth removal and/or orthodontic treatment (photos 1-5).

Less frequently crowding of permanent teeth, particularly for the upper incisors, results from narrowness of the underlying jawbone. In the lower jaw the bone shape cannot be changed, short of surgery. However, in the upper jaw, narrowness can be improved by the expanding the right and left halves of the jaws with deliberate, outward, lateral pressure exerted by a dental device. These devices are cemented in like braces and then left in for three to six months while they widen the space available for the new permanent incisors (photo 6).

Besides crowding due to tooth size or jaw shape if new incisors erupt out of place a crowded, unsightly appearance results. Especially when a new upper incisor erupts so far toward the palate that it remains behind the lower incisors during chewing. This cross-bite creates crowding for adjacent teeth while interfering with proper function and appearance. Correcting this type of cross-bite requires some sort of dental help but the correction can be speedy, a week or two with steady pressure. Perhaps some early braces might be used to correct this type of crowding even though they might be used for only a few months. In fact there are situations when only braces work where new incisors are rotated significantly (photos 7 & 8).

Certainly the majority of orthodontic treatment is best done in teenage years with all permanent teeth but crowding when permanent incisors erupt at ages six to eight is the most frequent sign of future orthodontic need and should not be ignored or tolerated entirely. Extraction of primary teeth, reducing the size of primary teeth, simple dental devices for cross-bite corrections and even some braces for a few months will ease a child’s transition to great oral health with cavity free, straight teeth. (photos 9-13).