Local causes of malocclusion Flashcards
List the dental causes of malocclusion
Tooth/tissue ratio No of teeth Abnormal form or position of teeth Path of closure Pathology
What can tooth/tissue ratio influence?
Crowding and spacing
Where is crowding more common in British adults?
Females and males = upper arch more common
Aetiology of crowding?
Genetic
- Independent genetic control of teeth and jaws
- Evolution
- Intermixing of racial/ethnic groups
Environmental - diet
Why has the severity of dental crowding increased?
Reduction of jaw size and decrease in tooth wear patterns
Name the types of spacing
Generalised spacing
Localised spacing - midline diastema
Number of teeth - what effects malocclusion?
Missing teeth - anodontia/hypodontia
Extra teeth - supernumerary/supplemental
Interference with normal timing
Name a condition associated with severe hypodontia
Ectodermal dysplasia
Prevalence of missing teeth?
3-7% of population are missing teeth - 13.6% lower 3rd molars (most common)
Least common = lower incisors
1.4x higher in females
2, 5, 8 common
What also occurs with hypodontia?
Teeth are often smaller = spacing
Prevalence of supernumerary teeth?
Occurs in 2% pts
Types of extra teeth?
Conical (mesiodens)
Tuberculate
Supplemental
Conical supernumerary teeth (mesiodens) features?
Usually between 1/1
Often erupts
Displaces other teeth
Tuberculate supernumerary teeth features?
Barrel shaped
Does not usually erupt
Prevents eruption of other teeth
Supplemental teeth features?
Resembles normal tooth
Occurs at end of series
Causes crowding
Interference with normal timing due to?
Premature loss of teeth - primary and permanent
Retention of primary teeth
Delayed eruption of permanent teeth
Premature loss of primary incisor effect?
Little effect with loss of incisor
Premature loss of primary canine causes what?
Shift of centre line to extraction side
Premature loss of 1st primary molar causes what?
Shift of centre line
Premature loss of 2nd primary molar causes what?
1st permanent molar moves mesially
Mesial movement 1st permanent molars
Space loss greater and faster in upper arch
More common in upper arch
Deflection of permanent teeth - how are upper laterals deflected?
How to manage?
Upper laterals deflected palatally
Extract primary teeth as early as possible
Infra-occluded teeth (submerging) happens when?
Missing permanent tooth
Ankylosed primary tooth
Examples of abnormal form of teeth
Macrodontia = big teeth Microdontia = small teeth - common for lateral incisors - can be peg shapped
Examples of abnormal position of teeth
Transposition = 2 teeth swap places - 3 and 2 can swap, 4 and 3 can swap
Impaction
Types of path of closure?
Lateral displacement Forward displacement - instanding tooth, class III incisors
What is lateral displacement?
Narrow upper arch = teeth do not meet correctly - posterior teeth cusp to cusp
Cannot get into maximum intercuspation without shifting jaw
What is forward displacement?
Instanding tooth - e.g. lateral incisor is in crossbite
In RCP = pt is biting on tooth in crossbite = posterior teeth not contacting
Posterior teeth only contacting when shift mandible forward
Class III
Examples of pathology relating to maloccusion?
Cysts e.g. dentigerous
Tumours
Trauma - dilaceration
