Etiology of malocclusions part 2 Flashcards
Deep bite
(3)
*Skeletal
*Overeruption of incisors
*Undereruption of molars
Transverse dimension
(3)
*Usually maxillary transverse
deficiency
*Maybe caused by overdeveloped
mandible
*Some are also caused by
unfavorable dental angulations
Disturbances of Dental Development
(5)
- Congenitally missing teeth
- Malformed and supernumerary teeth
- Interference with eruption
- Ectopic eruption
- Early loss of primary teeth
- Congenitally Missing Teeth
(2)
*Anodontia (very rare)
*Oligodontia (several teeth missing)
Dr Moyers’ Explanations for Congenitally
Missing Teeth
(5)
*Heredity
*Ectodermal Dysplasia
*Localised inflammations or infections
*Systemic conditions, e.g. ricketts
*Evolutionary changes in the dentition (specially third molars)
Ectodermal dysplasia
(2)
*Oligodontia
*Poorly shaped teeth
Most frequently missing teeth
(3)
*Upper lateral incisors
*Lower second premolars
*Lower central incisor
- Malformed Teeth
(3)
*“Peg” maxillary lateral incisors
*Crown can be mishaped
*Root may be shortened
Mesio Distal Size of the Dentition
(2)
*Proportionality of tooth sizes within a dentition
*Bolton ratio
Bolton Ratio
OVERALL RATIO:
ANTERIOR RATIO:
Mandibular 6-6 (mm)
Maxillary 6-6 (mm)
Mandibular 3-3 (mm)
Maxillary 3-3 (mm)
*This proportion is called the Bolton ratio.
*In order to develop a proper overbite and
overjet, the size of the lower dentition
must be proportional to the size of the
upper dentition
Bolton ratio
Ratio = –%
77
Supernumerary Teeth
*Mesiodens
Impacted upper central incisors
(4)
*Most often caused by trauma to
the deciduous tooth. Root can
become dilacerated
*Infection of deciduous central
*Cyst
*Supernumary tooth
Impacted cuspids
(2)
*Upper cuspids are the teeth most often impacted (3 to 4%)
*Treatment is difficult and costly
*Can we reduce the incidence of this problem?
Etiology (Theories)
(3)
- Narrow upper arch causes a strong
probability of impaction. Not valid in the
majority of cases - A combination of genetics and familial
tendencies - Missing or small lateral incisors, but a
normally sized arch
Malocclusions can be of
skeletal or dentoalveolar origin
* The majority are a combination of both
— plays a significant role in the etiology but functional factor are also contributing
factors
Genetics
The treatmetn approach will be defined by the capacity to assess the
etiology of the
malocclusion as accurately as possible
