A Class III malocclusion is what we would normally call an "underbite". This is a misnomer and is more appropriately called an "undershot" occlusion where the mandibular incisors occlude mesial to the maxillary incisors. We have bred for this condition in a number of dogs including Boxers, Pugs, Boston Terriers, etc. by shortening the maxilla (brachycephaly), but all breeds can be affected. This form of malocclusion can be punishing on the other structures in the oral cavity including teeth, bone and soft tissue structures. Always check the occlusion in these dogs to look for signs of trauma. It really IS painful, despite what the young Boxer with the waggling tail is telling you!

"Sophie" is a 9 year old, FS, Rottweiler mix that presented to me last month for routine periodontal therapy. General physical examination and pre-operative laboratory work were unremarkable. Oral examination revealed a Class III malocclusion with severe attrition (tooth on tooth contact) to the mandibular canines (304, 404) from the maxillary third incisors (103, 203) (Fig 1). In addition, there was soft tissue trauma to the floor of the mouth from the first and second maxillary incisors (101, 102, 201, and 202).

Fig 1: Notice the damage to the mandibular canines and soft tissue at the floor of the mouth.

  

"Sophie" was admitted for an anesthetized oral examination, whole mouth digital dental radiographs, periodontal therapy and treatment of the traumatic occlusion. Periodontal probing and radiographs revealed horizontal bone loss and stage IV periodontitis of the mandibular third incisors (Fig 2). The periodontitis can be secondary to the traumatic occlusion and crowding between the mandibular incisors. Periodontal therapy including closed root planing was performed on all dentition. The traumatic occlusion was treated with crown reduction of all the maxillary incisors (101, 102, 103, 201, 202, 203) followed by dentinal bonding (Fig 3, 4).

Fig 2: Notice the 10mm periodontal pocket between the
left mandibular third incisor (303) and the left mandibular canine (304)

Fig 3: Before crown reduction   

 

Fig 4: After crown reduction and dentinal bonding of the maxillary incisors

 

After the procedure, the endotracheal tube was removed and the occlusion was checked to ensure that an adequate amount of crown was reduced to prevent any further tooth on tooth or tooth on soft tissue contact. Follow up periodontal therapy and probing will be required to see if the present treatment has resolved or improved the periodontitis or if further therapy including extractions may be necessary. At the two week recheck, the owner felt that Sophie was greatly improved!

KEEP CHECKING FOR TRAUMATIC OCCLUSIONS!