Etiology of malocclusions Flashcards
Predisposing Factors to Malocclusion
4
- Disturbances in Embryologic Development
- Heredity (genetics)
- Functional matrix
- Traumas
• Functional matrix (2)
- Muscular or functional disturbances
* Habits
• Traumas (1)
• Especially mandibular fractures.
Primary Etiologic Sites
• Neuromuscular system…
Cerebral Palsy
Primary Etiologic Sites
• Bone:
OI
Primary Etiologic Sites
• Teeth:
Ectodermic Dysplasia
Primary Etiologic Sites
• Soft tissues (excluding muscles):
Sclerodermia
Disturbances in Embryologic Development
• — may interfere with cellular differentiation during pregnancy
Teratogens
• Teratogens may interfere with cellular differentiation during pregnancy (4)
- Alcool
- Drugs
- Pollution
• Exemple: Cleft and Lip Palate
Craniosynostosis syndromes Crouzon Syndrome
• Crouzon’s syndrome is the most frequently occurring member of this group. It is characterized by underdevelopment of the
midface and eyes that seem to bulge from their sockets .Crouzon’s syndrome arises because of prenatal fusion of the
superior and posterior sutures of the maxilla, along the wall of the orbit. The premature fusion frequently extends
posteriorly into the cranium, producing distortions of the cranial vault as well. If fusion in the orbital area prevents the
maxilla from translating downward and forward, the result must be severe underdevelopment of the middle third of the
face. The characteristic protrusion of the eyes is largely an illusion-the eyes appear to bulge outward because the area
beneath them is underdeveloped. There may be a component of true extrusion of the eyes, however, because when cranial
sutures become synostosed, intracranial pressure increases.
Treacher Collins (6)
•down slanting eyes with notched lower lids
•underdeveloped cheek and jawbones,
•prominent nose, broad mouth 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
Cleidocranial dysplasia (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
Cleidocranial dysplasia
• Dental abnormalities - (5)
failure to lose the baby teeth (deciduous) at the expected time; slow
eruption of secondary teeth; extra teeth; delayed or absent formation of teeth
• Ability to touch the shoulders together in front of the body
Dentinogenesis Imperfecta (DI) (3)
• DI is one of the most significant aspect of OI • Not all teeth are affected in the same manner • If one OI member of the family has DI, all the other OI member will have DI as well
Down Syndrome (4)
- Underdevelopment 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 (Vittek et al, 1994).
- Molars, impacted maxillary canines, and missing premolars
Cleido Cranial Dysplasia: Some facial features (6)
- Wide –flat forehead
- Wide set eyes
- Small sinuses
- Prolongued retention of primary teeth
- Supernumary teeth
- Severe malocclusion
Normal skeletal relationship (3)
• 1. Cranial base • Position and projection of the upper jaw • Position and projection of the lower jaw
- Malocclusion occurs in — dimensions
* Angle classification is based on — relationships
3
AP
• 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= s
everely
mandibular prognathic
Cluster 5=
severely maxillary
retrognathic
▫ (most common in this sample)
Prevalence • Depends on the population • Southeast Asian ~--- • Middle eastern ~--- • Indian ~--- • European ~---
15%
10%
1%
1-4%
Genetics of Class III Xue 2010 (3)
- Focused on mandibular prognathism
- Family and twin studies
- Linkage Analysis studies
Family and twin studies
• Suggest a — model as primary cause of Class III malocclusion
polygenic
Linkage Analysis studies (2)
• Used to determine the chromosome loci associated with the condition • Suggested loci: 1p22, 1p36, 3q26.2, 6q25, 11q22, 12q13, 12q23, 19p32.2
Deep Bite and Openbite: Multifactorial Etiologies (4)
- Transitory
- Skeletal (genetic)
- Neuromuscular
imbalance (CP) - Combination
Neuromuscular
imbalance (CP) (2)
- Oral habits
- Anterior tongue
posture
. Combination (1)
Sleep Apnea
