Dental Specialties: Orthodontics

Orthodontics is the dental speciality involved with he evaluation and treatment of the dentition in order to maintain a functional relationship of the dental arches and teeth to the supportive tissues of the face

The four goals of orthodontic treatment are:

1. to establish or maintain, as nearly as possible, a normal, functioning occlusion
2. to improve facial esthetics's where they are under control of the teeth
3. to eliminate any factor that might interfere with the growth and development of the upper (maxilla) and lower (mandible) jaws
4. to work with all other specialities in the rehabilitation of oral and facial deformities

The relationship of the maxillary first permanent molars to be mandibular teeth is the best indicator of occlusion. If the molars are missing, then the cuspid (K9 tooth) can be utilised.

There are four difference classifications of occlusion and malocclusion

1. occlusion : relationship between the maxilla and mandible
2. centric occlusion: standard or normal occlusion
3. functional occlusion: contact during biting
4. malocclusion: abnormal relationship, not central occlusion

• Class I - neutroclusion
• the mesiso-buccal cusp of the maxillary first molar occludes into the buccal grove of the mandibular first molar

you can see that the 3rd tooth from the back (a.k.a the 1-6) looks like it resting perfectly on top of the tooth below it, not touching the 2nd premolar or the 2nd molar.

• Class II -  distoclusion
• Mesio-buccal cusp of the maxillary first molar occlude into the space between the mandibular first molar and the second premolar - the mandible appears retrognathic (moved backwards)
• Division 1: the maxillary front teeth are all protrusive with a large over jet (how far the teeth jet out in comparison to the front bottom teeth) and usually a deep overbite (how much your front top teeth cover your bottom teeth

•  Division 2: the maxillary central teeth are retruded and usually the lateral teeth are protruded

• 
  Division 3: the front teeth have an open bite (when you bite down the front teeth do not touch). This is usually caused by thumb sucking, or thrusting your tongue to your front teeth when you swallow. 

• Class III - mesioclusion
• Mesio-buccal cusp of the maxillary first molar occludes into the space between the mandibular first and second molar - the mandible appears prognathic ( moved forward )
• there may be an anterior cross bite
  
  
  

 There are several factors involved in arch development that can lead to malocclusion

• Development causes - disturbances during dental development
• congenitally missing teeth
• malformed teeth - larger or smaller than usual
• supernumerary teeth - more teeth then there are supposed to be
• ectopic eruption - eruption away from the normal position
• Genetic Causes - inherited traits
• jaw size and tooth size are inherited - large teeth and a small jaw affect development
• Environmental Causes
• birth defects such as fetal molding (pressure from body position in utero)
• birth traumas (forceps delivery)
• injuries though developmental years - like trauma to the primary teeth
• Functional Causes
• oral habits that can place pressure on the dental arches and facial bones (tongue thrust swallow, thumb sucking)