Malocclusion- Firestone Flashcards
what is epidemiology
study of the dynamics of occurrence of a condition or trait in a population or group
percentage of occlusions
normal- 35% mild malocclusion- 20% moderate malocclusion- 20% severe- 20% handicapped- 5%
irregularity data
little more than 50% surveyed had little or no crowding with about 6-8 percent exhibiting severe to extreme crowding in the younger age group
irregularity increased between childhood and youth and was largely stable between youth and adult except for mandibular crowding which increased
diastema data
26% had maxillary midline diastemas in the 8-11 age group which decreased to 6% in later age groups
angle’s classification
class 1- mesiobuccal cusp in buccal groove class 2- mesiobuccal cusp is anterior to buccal groove class 3- meseiobuccal cusp is behind buccal groove
a-p dimension data
mild class 2 decrease from childhood to adolescence
probably result of differential jaw growth during the adolescent growth spurt
the increase in mild class 3 has the same cause
lack of change in the more sever categories that is puzzling but could be result of more severe skeletal mal relationships that continue to be expressed during growth
ideal- 30%-40% 1-2mm overjet
3-4 most common- 50%
a-p dimension ethnicity data
european americans- class 2 tendency more likely hispanic and african americans- class 3 more likely
vertical dimension data
deep bite decreases and ideal overbite increases- due to continued vertical growth
vertical problems of anterior open bite versus anterior deep bite exhibit racial differences
anterior open bite affect larger number of african americans and hispanics
anterior deep bites more common in european americans
around 40-50% open bite
around 30-40% deep bite
prevalence summary
30% normal class 1 occlusion 50-55% class 1 malocclusions (mostly crowding) 15-20% had class 2 malocclusins less than 1% had class 3 malocclusions class 2 problems more prevalent in european descent class 3 more prevalent in af am, hispanic, east asian
etiology of malocclusion
malocclusion is in most instances a development condition
resulting from a complex interaction among multiple factors
occasionally a single specific cause is apparent
percent normal occlusion, malocclusion of unknown etiology, malocclusion of known etiology
35%, 60%, 5%
what are the result of hereditary factors from twin studies?
40% of the dental and facial variations that lead to malocclusion can be attributed to hereditary factors
what are the results of study of family members?
facial skeleton measurements correlation coefficient for parent-child pairs is 0.5
lower for dental measurement- 0.15 to 0.5
with increasing age heritability estimates increases for skeletal and decrease for dental variables
inheritance is particularly strong for mandibular prognathism followed by long face pattern of facial development
what are some prenatal development interferences?
agents- teratogens, biological agents, radiation
fetal molding and birth injuries
migration of neural crest cells
what are some post -natal development interferences?
childhood fractures
muscle dysfunction- atrophy, hyperfunction, muscle weakness syndromes
acromegaly
condylar hyperplasia- hemi mandibular hypertrophy
