Etiology of malocclusions part 2

Question 1

Deep bite
(3)

Answer 1

*Skeletal
*Overeruption of incisors
*Undereruption of molars

Question 2

Transverse dimension
(3)

Answer 2

*Usually maxillary transverse
deficiency
*Maybe caused by overdeveloped
mandible
*Some are also caused by
unfavorable dental angulations

Question 3

Disturbances of Dental Development
(5)

Answer 3

1. Congenitally missing teeth
2. Malformed and supernumerary teeth
3. Interference with eruption
4. Ectopic eruption
5. Early loss of primary teeth

Question 4

1. Congenitally Missing Teeth
   (2)

Answer 4

*Anodontia (very rare)
*Oligodontia (several teeth missing)

Question 5

Dr Moyers’ Explanations for Congenitally
Missing Teeth
(5)

Answer 5

*Heredity
*Ectodermal Dysplasia
*Localised inflammations or infections
*Systemic conditions, e.g. ricketts
*Evolutionary changes in the dentition (specially third molars)

Question 6

Ectodermal dysplasia
(2)

Answer 6

*Oligodontia
*Poorly shaped teeth

Question 7

Most frequently missing teeth
(3)

Answer 7

*Upper lateral incisors
*Lower second premolars
*Lower central incisor

Question 8

2. Malformed Teeth
   (3)

Answer 8

*“Peg” maxillary lateral incisors
*Crown can be mishaped
*Root may be shortened

Question 9

Mesio Distal Size of the Dentition
(2)

Answer 9

*Proportionality of tooth sizes within a dentition
*Bolton ratio

Question 10

Bolton Ratio
OVERALL RATIO:
ANTERIOR RATIO:

Answer 10

Mandibular 6-6 (mm)
Maxillary 6-6 (mm)

Mandibular 3-3 (mm)
Maxillary 3-3 (mm)

Question 11

*This proportion is called the Bolton ratio.

Answer 11

*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

Question 12

Bolton ratio
Ratio = –%

Answer 12

77

Question 13

Supernumerary Teeth

Answer 13

*Mesiodens

Question 14

Impacted upper central incisors
(4)

Answer 14

*Most often caused by trauma to
the deciduous tooth. Root can
become dilacerated
*Infection of deciduous central
*Cyst
*Supernumary tooth

Question 15

Impacted cuspids
(2)

Answer 15

*Upper cuspids are the teeth most often impacted (3 to 4%)
*Treatment is difficult and costly
*Can we reduce the incidence of this problem?

Question 16

Etiology (Theories)
(3)

Answer 16

1. Narrow upper arch causes a strong
   probability of impaction. Not valid in the
   majority of cases
2. A combination of genetics and familial
   tendencies
3. Missing or small lateral incisors, but a
   normally sized arch

Question 17

Malocclusions can be of

Answer 17

skeletal or dentoalveolar origin
* The majority are a combination of both

Question 18

— plays a significant role in the etiology but functional factor are also contributing
factors

Answer 18

Genetics

Question 19

The treatmetn approach will be defined by the capacity to assess the

Answer 19

etiology of the
malocclusion as accurately as possible