Base Narrow Lower Canines
Another common problem is base narrow lower canines. This can be due to a tooth or jaw problem. The tooth variety can be caused by retained deciduous lower canines. This is due to the fact that the adult canines erupt lingual (or inside) the deciduous canines. The deciduous tooth will cause the adult canines to deviate inwards. If there are retained deciduous canines or the patient is base narrow with its deciduous dentition, interceptive orthodontics should be performed as soon as possible to hopefully avoid the problem. The lingual deviation of the adult canines will usually cause palatine trauma and patient discomfort. The jaw variety is due to a genetically narrow jaw. There are two ways to treat this condition. If the malocclusion is slight (usually a tooth problem), then an incline plane or other orthodontic correction can push out the teeth. If the problem is moderate to severe, or there is interlock with the upper canines, then crown amputation and pulp capping is usually the best choice. A wry bite, where the two halves of a jaw don’t grow at the same rate can also cause this problem, and crown amputation is indicated to relieve soft tissue trauma. Our experience has been very unrewarding in treating wry bite orthodontically.
Anterior crossbite is where the upper incisors erupt behind the lower incisors. This is usually not a problem for the patient, as it is usually a “reverse scissors” and comfortable. This can be corrected by orthodontic appliance if it is due to a tooth problem. If it is a jaw problem, this will be much more difficult and the patient should be neutered prior to this lengthy process.
Posterior cross bite is where the upper fourth premolar is inside the lower first molar. This is most common in collies. Correction of this defect is very difficult and is usually not necessary as the teeth function properly in their new alignment.
Undershot (longer lower jaw) and overshot (longer upper jaw) are common problems as well. Undershot jaws can be “Normal” for certain breeds (Persian cats, Lhasa Apso, bull dogs, etc. These conditions can cause problems by allowing for soft tissue trauma by the canines not being in the proper alignment. Overshot jaws can cause the lower canines to strike the upper canine or palate. Severe undershot jaws can cause lip trauma. If the defect is mild and caught early enough, the problem may be avoided. Sometimes, the jaw discrepancy will only be temporary, and the jaws will want to correct over time. However, the dental interlock will not allow the jaw to move. For this reason, if this is discovered early enough, interceptive orthodontics can be performed by extracting the deciduous teeth. This will allow the jaws to move if they want to, but will not make them do so. If the patient already has its permanent dentition orthodontic treatment is difficult to impossible. If the teeth are causing oral trauma, then crown amputation and pulp capping is the treatment of choice.
Rostrally displaced upper canines (Lance Effect) can be caused by a retained deciduous upper canine or can be genetic in nature. This is mostly seen in Shetland sheepdogs. This can cause periodontal disease, as well as tooth attrition from striking the lower teeth. This can be corrected by extraction of the tooth, amputation and pulp capping, or by orthodontic bands. If this is genetic, the patient should be neutered prior to performing orthodontic correction.
Crowded and/or rotated teeth are commonly seen in small breed dogs, especially the bracheocephalic breeds. The major problem they cause is that they greatly increase periodontal disease in the area. These are generally not orthodonticly treated, however extracting them can improve the overall periodontal health of the animal.