Introduction to orthodontics Flashcards
Describe the four purposes of orthodontics:
1. Preventive
- Interceptive
- Corrective
- Surgical
- Preventive:
Avoid/stop something before it happens - Interceptive:
Interrupts abnormal process which is already happening - Corrective:
Correcting the malocclusion through orthodontic treatment - Surgical:
Correcting the jaw position
List the 3 goals of orthodontics: Jackson’s triad
- Functional efficiency of chewing, speech and breathing
- Aesthetic harmony including well-aligned teeth, good smile display and good soft tissue profile
- Structural balance between hard and soft tissue
List 4 reasons why people get orthodontic treatment
- Psychosocial reasons
- Aesthetics
- Interference with growth and development (Crossbites causing asymmetry)
- Abnormal Muscle function (Habits, hyperactive muscle function)
Explain the basic relationship between orthodontic treatment and periodontal disease
- Crowding leads to plaque accumulation
- The impact of orthodontic treatment on periodontal disease is not as great as the impact of motivation and oral hygiene
- Ortho Tx can still be done on teeth with reduced support without further compromising periodontal health, provided causative factors such as plaque are under control
Explain the relationship between psychosocial effects and orthodontics (4)
- Unattractive appearance = unfavorable social response
- Facial aesthetics determines self perception
- Early treatment improves self image especially in children targeted by peer group bullying
- Early orthodontic treatment for Class II malocclusion reduces the chance of incisal trauma in children with increased overjet
- Psychosocial gain from orthodontic treatment higher than the dental health gain
List the effects of the 6 molar relationship if it is in a:
- Mesial step
- Distal step
- Flush terminal plane
Mesial step
- Class I
Distal step
- Class II
Flush terminal plane
- Class III
Explain the concept of spacing in the primary dentition and the formation of diastema
List which teeth are most likely to form diastemas
- It is normal for general spacing to occur in the primary dentition
- As a child grows in height and weight, so do the jaws
- This growth of the mandible and maxilla results in horizontal and vertical growth of the dental arches
- The teeth, however, remain the same size. Thus as the arches grow, spaces called diastemas form between the teeth
Teeth are most likely to form diastemas:
- Mesial of the upper 3’s
- Distal of the lower 3’s
Explain the concept of “leeway space” by:
- Defining
- Stating which teeth are part of this concept
- Stating where leeway space is largest
Definition
• The difference between the space that deciduous teeth take up and that of their permanent replacements is called leeway space.
The teeth:
• Leeway space is extra space that deciduous canines and molars occupy (in their size/ width) to help save room for their permanent successors (which are smaller/ width)
Where the biggest leeway space exists:
• Leeway space in the mandible is larger than that of the maxillary
List three appliances that are used to maintain leeway space
- Trans-palatal arch
- Lingual arch
- Lip bumper
List and explain the four main eruption problems that occur
- Impacted teeth: tooth that fails to erupt due to their positioning in the jaw. Canines should be palpable buccally by age 10. If not, it is possibly impacted
- Ectopic eruption: tooth erupting in the wrong spot
- Congenitally missing teeth: teeth that are congenitally missing
- Supernumerary teeth: extra teeth (mesiodens, distodens)
Explain the concept of the ‘ugly duckling’ stage
- It is caused by malocclusion seen in the maxillary incisor region around 8- 9 years age
- It is usually self correcting and sorts itself out once the canines erupt and the pressure is transferred from the root to the crown area, setting the incisors in place
Explain what normal occlusion should look like in relation to the line of occlusion in the maxilla and mandible
Maxilla:
- The line of occlusion should pass through the central fossa and along the cinugulae of maxillary teeth
Mandible:
- The line of occlusion should pass through the buccal cusps and incisal edges of mandibular teeth
Define centric occlusion and centric relation
Centric occlusion:
• Position of the lower jaw when you bite and all your teeth come together
• It is a dentally determined position independent of condylar position
(Other synonymous terms: CO, ICP, Habitual occlusion)
Centric relation:
• The relation of the mandible to the maxilla when the mandible is in the most retruded, unstrained position and the condyles are seated in the most superior and anterior position in the articular fossa (jaw at rest)
Define CR-CO Discrepancy (functional shift)
- Known the displacement of the mandible in an anterior, posterior and/or lateral direction, as a result of premature contact occurring when the mandible is in centric relation.
- A functional shift of up to 1-2 mm is acceptable.
Explain the impact of what could happen if a functional shift is not identified and treated early
A major functional shift in the lateral direction may lead to potential asymmetrical growth if left untreated
