The scissor bite in a mesaticephalic dog with proper relations of its dentition and all criteria of bite evaluation will be presented prior to discussion about malocclusion. In scissor bite the maxillary incisors overlap mandibular ones and the lower incisors' incisal edge rest on the upper incisors' cingulum. The mandibular cuspid fits evenly between the third maxillary incisor and maxillary cuspid. The upper premolars interdigitate with lower premolars starting rostrally with the first mandibular premolar. Crowns of maxillary and mandibular molars occlude with each other.

Myths

1.  'Manual dental replacement by massage is a good, safe, and efficient method for management of occlusal problems.'
No it is not. Manual pressure by the owner does not provide reliable and measurable action which will safely move maloccluded teeth. There exist some acceptable methods of improving occlusion with the use of toys, where the patient itself provides the orthodontic force.

2.  'Dental buds cannot be visualized.'
After the apposition and maturation process the bud's enamel and mineralized dentine are easily visualized on properly exposed radiographs.

3.  'Everything was normal and yesterday those teeth suddenly were maloccluded.'
Sudden, non-traumatic occurrence of a malocclusion is impossible. Therefore proper bite evaluation contains several criteria.

4.  'The bite is normal when the incisors are in proper relations.'
No, incisor position is only the part of bite evaluation.

5.  'Heads in some breeds continue to grow until 3 years of age. Therefore the final bite evaluation cannot be performed at this age.'
There is no scientific proof for this.

6.  'Acceptance of missing teeth and malocclusion does not influence the genetic material of particular breed.'
Of course it does. The list of tolerated problems in pedigree dogs which will be reproduced should be revised and updated.

Truths

1.  The evaluation of occlusion contains several important criteria that include shape and symmetry of the skull, the function of the temporo-mandibular joint (TMJ), and finally position and number of the teeth.

2.  The tongue pushes teeth forward as the upper lip pushes them backward. 'Dental interlock' controls this phenomenon.

3.  Complete dentition in dogs consists of 42 teeth. Acceptance of missing dentition leads to having this problem established in the population.

4.  The cause of persistent deciduous teeth may be their malposition as well as malocclusion of permanent teeth during eruption.

5.  Until the somatic development of the animal is completed changes in occlusion may be observed. The final reliable evaluation of occlusion is performed at an appropriate age (usually 9-10 months in small, 10-12 months in medium, and 12-14 months in large breeds).

6.  Skeletal characteristics of malocclusion are considered hereditary and therefore affected individuals should not be treated orthodontically.

7.  Interceptive orthodontics in deciduous dentition, if properly performed, may diminish the risk of certain malocclusions.

8.  Orthodontic movement must be followed by retention which can last for several weeks.

9.  Malocclusion, particularly cases with traumatic consequences, require immediate intervention. Often it may be resolved in surgical and endodontic way, provided the result removes trauma.

Ethics

1.  All orthodontic therapy should be designed to relieve trauma, pain, and discomfort; not to improve the cosmetics of the patient.

2.  Numerous anesthetics are necessary, this fact must be considered prior to acceptance of the orthodontic treatment plan.

3.  More and more malocclusions are being proven to be genetically based and therefore hereditary.

4.  All orthodontic procedures performed in pedigree dogs should be recorded in detail and attached to the rest of the patient's records.

5.  To prevent propagation of hereditary malocclusions sterilization of affected animals is required.

References

1.  Emily P. Feline malocclusion. Vet Clin North Am Small Anim Pract. 1992 Nov;22(6):1453-60.

2.  Gengler WR. Masel chain appliance for orthodontic treatment. J Vet Dent. 2004 Dec;21(4):258-61

3.  Gough A, Thomas A. Breed Predispositions to disease in Dogs and Cats Blackwell Publishing Ltd 2004, 163-176

4.  Niemiec BA. Vital pulp therapy J.Vet.Dent 2001 18(3), 154-6

5.  Surgeon TW. 2005. Fundamentals of small animal orthodontics. Vet. Clin. North Am. Small Anim. Pract. Dent. 35(4):869-889.

6.  Surgeon TW. 2007. Indications planning and ethical considerations for orthodontic treatment. Pesquisa Veterinária Brasileira 27(Supl.).

7.  Wiggs B, Lobprise H. Basics of Orthodontics in Veterinary Dentistry Principles and Practice Lippincott Raven, 435-481, 1997