Etiology of Malocclusions

Question 1

what are some predisposing factors to malocclusion

Answer 1

• disturbances in embryologic development
• heredity
• functional matrix- muscular or functional disturbances and habits
• traumas- especially mandibular fractures

Question 2

what are the primary etiologic sites and what are the diseases of each

Answer 2

• neuromuscular system- cerebral palsy
• bone: OI
• teeth: ectodermic dysplasia
• soft tissues: sclerodermia

Question 3

what tetrogens interfere with cellular differentiation during pregnancy

Answer 3

• alcohol
• drugs
• pollution

Question 4

what is crouzon’s syndrome characterized by

Answer 4

underdevelopment of the midface and eyes that bulge from their sockets

Question 5

how does crouzons syndrome arise

Answer 5

prenatal fusion of the superior and posterior sutures of the maxilla along the wall of the orbit

Question 6

what are the symptoms for treacher collins

Answer 6

• down slanting eyes with notched lower lids
• underdevloped cheek and jawbones
• prominent nose, broad nose and characteristically small chin with steep lower jaw angle
• ears are malformed or prominent and hair may extend towards the face
• hearing loss is also possible
• may have cleft lip and/or palate, heart defects and strabismus

Question 7

what are the symptoms of cleidocranial dysplasia

Answer 7

• delayed closure (ossification) of the space between the bones of the skull (fontanels)
• premature closing of the coronal suture
• protruding jaw (mandible) and protruding brow bone (frontal bossing)
• wide nasal bridge due to increased space between the eyes (hypertelorism)
• high arched palate or possible cleft palate
• short stature
• scoliosis of the spine
• ability to touch the shoulders together in front of the body

Question 8

what are the dental abnormalities of cleidocranial dysplasia

Answer 8

• failure to lose baby teeth at expected time
• slow eruption of secondary teeth
• extra teeth
• absent formation of teeth

Question 9

what type of malocclusion does OI cause

Answer 9

class III malocclusion, posterior open bite
- midline deviation, asymmetry, repercussion on the condyles
- posterior open bite: lack of chewing capability

Question 10

what happens in DI

Answer 10

not all teeth are affected in the same manner
- if one OI member of the family has DI, all other OI member will have DI as well

Question 11

what are the symptoms of down syndrome

Answer 11

• underdeveloped or hypoplasia of the midfacial region
• the bridge of the nose, bones of the midface and maxilla are relatively smaller in size
• prognathic class III occlusal relationship which contributes to an open bite
• molars, impacted maxillary canines, and missing premolars

Question 12

what are facial features of cleidocranial dysplasia

Answer 12

• wide flat forehead
• wide set eyes
• small sinuses
• prolonged retention of primary teeth
• supernumary teeth
• severe malocclusion

Question 13

what are the 5 clusters of phenotypic diversity

Answer 13

• cluster 1: mild maxillary retrognathism and mandibular prognathism, flat mandibular plane
• cluster 2: mild maxillary retrognathism and mandibular prognathism, normal mandibular plane
• cluster 3= large mandible expressed vertically
• cluster 4 = severely mandibular prognathic
• cluster 5: severely maxillary retrognathic

Question 14

what are the etiologies of deep bite and openbite

Answer 14

• transitory
• skeletal
• neuromuscular imbalance: oral habits, anterior tongue posture
• combination sleep apnea