Class I Malocclusion

Question 1

What skeletal pattern is normally seen in Class I malocclusions?

Answer 1

• Class I usually

- Can also be Class II or III with incisor inclination compensating for skeletal discrepancy

Question 2

What main dental factor contributes to Class I malocclusions?

Answer 2

• Majority of cases the underlying problem will be one of tooth/arch size discrepancy, leading to crowding or less frequently spacing.
• Premature loss of deciduous/permanent teeth can also contribute to crowding

Question 3

What is the aetiology of late lower incisor crowding?

Answer 3

• Intercanine width increases up to 9 yrs and then gradual diminution (most noticeable during late teens leading to more incisor crowding)
• Multifactorial aetiology:
  1. forward growth of mandible in conjunction with soft tissue pressures
  2. mesial migration of posterior teeth
  3. erupting 8s - maybe

Question 4

Management of spacing in Class I malocclusions?

Answer 4

Complete space closure may be difficult and permanent retention usually required
May necessary to concentrate spaces posteriorly and replace with bridges

Question 5

Management of missing upper incisors in Class I malocclusions?

Answer 5

• Can be lost due to trauma or extracted due to dilaceration
• Close space or open space and replace with denture/bridge/implant
• Canines can be used to disguise if colour and form is acceptable
• Lateral brought forward to replace central only if large and has good gingival circumference
• The desired buccal segment occlusion affects decision to open or close space: if buccal segment well aligned and class I, may opt to open space

Question 6

Management of displaced teeth in Class I malocclusions?

Answer 6

1. Extraction of primary tooth and space maintenance
2. Exposure and application of orthodontic traction
3. Extraction if severely displaced

Question 7

Management of bimaxillary proclination in Class I malocclusions?

Answer 7

• Retracting both labial segments with fixed appliances
• If lips have good muscle tone the chances of obtaining a stable result are better as they can adapt
• Incompetent lips will be unstable and long term retention needed