Ben H. Colmery, III, D.V.M.
Diplomate, A.V.D.C.
MVS Dentistry Service
Growth and development of the oral cavity is a series of events that must occur in proper sequence or long term complications will oc
cur. Understanding basic growth patterns in the oral cavity will help the veterinarian to know when to intervene to prevent further developmental defects (interceptive orthodontics). Developmental defects occur in 3 major stages. Each stage has its own set of problems thus requiring close inspection by the veterinarian. Stage 1 is 0-16 weeks of age, Stage 2 is from 4-7 months of age, and Stage 3 is from 7 months to 1? years of age.
Stage One:
Puppies and kittens are born with an ?overshot? maxilla (brachygnathism) to allow the neonatal animals to nurse. As the animal grows, and the impending transition from the mother?s milk to solid food occurs, the mandible goes through a growth spurt nearly reaching its relative adult percentage of jaw length. If this spurt does not occur, and the deciduous dentition erupts, the mandibular canines will likely be distal (behind) to the maxillary canines. This immediately creates a malocclusion with the potential for failure of the mandible to attain its proper length. The best therapy is to remove the mandibular canine teeth (cautiously so as not to damage the permanent tooth bud). If the mandibular incisors also are excessive in length and occluded behind the dental papilla, the mandibular incisors are likewise extracted. Treatment should allow the mandible to attain normal length thus averting problems with the permanent dentition. If the animal is genetically predetermined to have a significant overbite this therapy will not affect the outcome.
Underbite (prognathism) is another defect in this stage. This occurs when the mandible grows ahead of schedule and becomes too long for the maxilla. This condition becomes evident as early as 8 weeks of age. It is characterized by occlusion of the maxillary incisors inside the mandibular incisors, and the mandibular canines occluded up to or mesial to the maxillary lateral incisors. The treatment of choice is to extract (with care) the maxillary central and middle incisors. As a rule the maxillary lateral incisors are preserved, especially if the are acting as a deterrent to growth to the mandible. The prognosis for the permanent dentition to be normal is not as favorable as for brachygnathism; however, early intervention is essential for the best chance of success.
Other congenital and developmental problems that require intervention include polyodontia (extract the extra teeth) or gross displacement of a deciduous tooth (extract the tooth if it is causing mechanical interference). Asymmetry of maxilla and or mandibular growth is managed by extraction of the teeth on the affected (under developed) side. Asymmetry problems usually carry a poor prognosis for correction, but extraction is recommended to give opportunity for self-correction.
Stage Two:
The hallmark problem in this stage is retention of deciduous teeth. The normal shedding process begins around fourteen weeks of age with the initial loss of the maxillary central incisors. Then, for the next three months, the deciduous teeth are replaced with permanent teeth plus additional permanents to complete the animals dentition. If the deciduous teeth are not lost at the time of eruption of the counterpart permanent tooth, malocclusion occurs. No two teeth can occupy the same alveolus at the same time, so by definition the permanent tooth is always in malocclusion. The treatment of choice is to extract the deciduous tooth as soon as retention becomes evident. Only in rare circumstances will an error be made by removing a deciduous tooth.
Other developmental defects that occur in this stage include linguoversion of the mandibular canine teeth, rostralversion of the maxillary canines, and brachygnathism. When the canine teeth have finished erupting, a window of opportunity exists for simple orthodontic correction of lingual displacement of the mandibular canine teeth with a maxillary bite plate. Because the oral skeletal system is developing at a rapid rate at six to seven months of age, orthodontic appliances can only be left in an animals mouth for two to three weeks at a time. Thus, any therapy must be accomplished in this short period of time.
Rostralversion of the maxillary canines typically occurs in the Sheltie breed of dogs, although it has been reported in many small breeds as well as cats. The distal dentition does not mature until at least 10 months of age, so this is the minimum age for the beginning orthodontic therapy for this problem. Buttons brackets and masial chain are the materials of choice.
Brachygnathism is treated by using temporary maxillary bite plates if the degree of brachygnathism is minimal. If the brachygnathism is severe, (mandibular canine occluding on the palatal side of the maxillary canine) crown reduction of the mandibular canines or extraction of the maxillary canines are options.
Stage Three
The final stage of developmental occlusal defects are seen from 7-18 months of age. The most common problems are anterior crossbites (incisors in reverse scissors), posterior crossbites (carnassial teeth in reverse position), crowding, tooth rotation, and the final expressions of prognathism and brachygnathism. Anterior crossbites can be treated only if the remaining dentition is within normal limits (most anterior crossbites are a result of prognathism). Maxillary expansion screw splints or other accepted orthodontic treatments are employed. Posterior crossbites are best treated by extracting the maxillary fourth premolar.
If orthodontic treatment is attempted a very cooperative animal and owner are mandatory. Crowding of teeth (large teeth-small space) is treated by extracting the offending teeth. Likewise, teeth that are rotated greater than forty five degrees (often found in brachycephalic breeds) are extracted.
Dr. Colmery may be reached at 810-354-6660
Rich Text Area Toolbar Bold (Ctrl + B) Italic (Ctrl + I) Strikethrough (Alt + Shift + D) Unordered list (Alt + Shift + U) Ordered list (Alt + Shift + O) Blockquote (Alt + Shift + Q) Align Left (Alt + Shift + L) Align Center (Alt + Shift + C) Align Right (Alt + Shift + R) Insert/edit link (Alt + Shift + A) Unlink (Alt + Shift + S) Insert More Tag (Alt + Shift + T) Toggle spellchecker (Alt + Shift + N) ▼ Toggle fullscreen mode (Alt + Shift + G) Show/Hide Kitchen Sink (Alt + Shift + Z) Add EasyRotator Rotator To This Post… Format – Paragraph Paragraph ▼ Underline Align Full (Alt + Shift + J) Select text color ▼ Paste as Plain Text Paste from Word Remove formatting Insert custom character Outdent Indent Undo (Ctrl + Z) Redo (Ctrl + Y) Help (Alt + Shift + H) Ben H. Colmery, III, D.V.M. Diplomate, A.V.D.C. MVS Dentistry Service Growth and development of the oral cavity is a series of events that must occur in proper sequence or long term complications will occur. Understanding basic growth patterns in the oral cavity will help the veterinarian to know when to intervene to prevent further developmental defects (interceptive orthodontics). Developmental defects occur in 3 major stages. Each stage has its own set of problems thus requiring close inspection by the veterinarian. Stage 1 is 0-16 weeks of age, Stage 2 is from 4-7 months of age, and Stage 3 is from 7 months to 1? years of age. Stage One: Puppies and kittens are born with an ?overshot? maxilla (brachygnathism) to allow the neonatal animals to nurse. As the animal grows, and the impending transition from the mother?s milk to solid food occurs, the mandible goes through a growth spurt nearly reaching its relative adult percentage of jaw length. If this spurt does not occur, and the deciduous dentition erupts, the mandibular canines will likely be distal (behind) to the maxillary canines. This immediately creates a malocclusion with the potential for failure of the mandible to attain its proper length. The best therapy is to remove the mandibular canine teeth (cautiously so as not to damage the permanent tooth bud). If the mandibular incisors also are excessive in length and occluded behind the dental papilla, the mandibular incisors are likewise extracted. Treatment should allow the mandible to attain normal length thus averting problems with the permanent dentition. If the animal is genetically predetermined to have a significant overbite this therapy will not affect the outcome. Underbite (prognathism) is another defect in this stage. This occurs when the mandible grows ahead of schedule and becomes too long for the maxilla. This condition becomes evident as early as 8 weeks of age. It is characterized by occlusion of the maxillary incisors inside the mandibular incisors, and the mandibular canines occluded up to or mesial to the maxillary lateral incisors. The treatment of choice is to extract (with care) the maxillary central and middle incisors. As a rule the maxillary lateral incisors are preserved, especially if the are acting as a deterrent to growth to the mandible. The prognosis for the permanent dentition to be normal is not as favorable as for brachygnathism; however, early intervention is essential for the best chance of success. Other congenital and developmental problems that require intervention include polyodontia (extract the extra teeth) or gross displacement of a deciduous tooth (extract the tooth if it is causing mechanical interference). Asymmetry of maxilla and or mandibular growth is managed by extraction of the teeth on the affected (under developed) side. Asymmetry problems usually carry a poor prognosis for correction, but extraction is recommended to give opportunity for self-correction. Stage Two: The hallmark problem in this stage is retention of deciduous teeth. The normal shedding process begins around fourteen weeks of age with the initial loss of the maxillary central incisors. Then, for the next three months, the deciduous teeth are replaced with permanent teeth plus additional permanents to complete the animals dentition. If the deciduous teeth are not lost at the time of eruption of the counterpart permanent tooth, malocclusion occurs. No two teeth can occupy the same alveolus at the same time, so by definition the permanent tooth is always in malocclusion. The treatment of choice is to extract the deciduous tooth as soon as retention becomes evident. Only in rare circumstances will an error be made by removing a deciduous tooth. Other developmental defects that occur in this stage include linguoversion of the mandibular canine teeth, rostralversion of the maxillary canines, and brachygnathism. When the canine teeth have finished erupting, a window of opportunity exists for simple orthodontic correction of lingual displacement of the mandibular canine teeth with a maxillary bite plate. Because the oral skeletal system is developing at a rapid rate at six to seven months of age, orthodontic appliances can only be left in an animals mouth for two to three weeks at a time. Thus, any therapy must be accomplished in this short period of time. Rostralversion of the maxillary canines typically occurs in the Sheltie breed of dogs, although it has been reported in many small breeds as well as cats. The distal dentition does not mature until at least 10 months of age, so this is the minimum age for the beginning orthodontic therapy for this problem. Buttons brackets and masial chain are the materials of choice. Brachygnathism is treated by using temporary maxillary bite plates if the degree of brachygnathism is minimal. If the brachygnathism is severe, (mandibular canine occluding on the palatal side of the maxillary canine) crown reduction of the mandibular canines or extraction of the maxillary canines are options. Stage Three The final stage of developmental occlusal defects are seen from 7-18 months of age. The most common problems are anterior crossbites (incisors in reverse scissors), posterior crossbites (carnassial teeth in reverse position), crowding, tooth rotation, and the final expressions of prognathism and brachygnathism. Anterior crossbites can be treated only if the remaining dentition is within normal limits (most anterior crossbites are a result of prognathism). Maxillary expansion screw splints or other accepted orthodontic treatments are employed. Posterior crossbites are best treated by extracting the maxillary fourth premolar. If orthodontic treatment is attempted a very cooperative animal and owner are mandatory. Crowding of teeth (large teeth-small space) is treated by extracting the offending teeth. Likewise, teeth that are rotated greater than forty five degrees (often found in brachycephalic breeds) are extracted. Dr. Colmery may be reached at 810-354-6660 Path : p » span
The post Clinical Interceptive Orthodontics first appeared on Veterinary Specialty Practice Alliance.