Etiology of malocclusion Shi Congchong Department of Orthodontics School of Stomatology , KMU .

definition ideal normal occlusion 1. save all teeth the tooth in the upper and lower dental arch is trim the tips of the upper and lower teeth relationship are right, upper and lower dental arch occlusal is very ideal

definition ideal normal occlusion individual normal occlusion slight malocclusion, without obstruction of the physical process, can be included in the normal category individual occlusion in the normal category, is different between each other.

definition ideal normal occlusion individual normal occlusion deformities in teeth or/and maxillary(mandible) or/and craniofacial in children’s process of growth and development caused by congenital or acquired environment factors, such as disease, oral bad habits, etc

Etiology Genetic influence race evolution individual development Environmental influence congenital causes acquired causes functional influences oral bad habits local disturbances in primary dentition and mixed dentition

Genetic influence race evolution the change of living environment

Genetic influence race evolution the change of living environment the change of structure of the food

Genetic influence race evolution the change of living environment the changing structure of the food the imbalance of degradation chewing organs muscle>bone>teeth

Genetic influence race evolution individual development

Environmental influence congenital causes micrognathia palate cleft

Environmental influence congenital causes supernumerary tooth can delay eruption of adjacent teeth, increase arch perimeter and lead to crowding. Diastema, aberrant swallowing patterns and abnormal inclination of adjacent teeth can be seen as a result of congenitally missing teeth. supernumerary tooth congenital missing tooth

Environmental influence 2.acquired causes

Environmental influence 2.acquired causes trauma and accidents facial asymmetries

Environmental influence 3.functional influences During the period of children's growth and development, the factors which can influence the growth and development of teeth, occlusion, jaw when oral system functionate. .

Environmental influence 3.functional influences dysfunction of sucking inappropriate feeding way may lead to crossbite

Environmental influence 3.functional influences (2) respiratory dysfunction -mouth breathing rhinitis or habit or other reasons mouth breathing

dental arch stenosis upper teeth crowded upper jaw protrusion mandibular retraction shortening of the upper lip lip muscle relaxation ala nasi atrophy overbite and overjet

Environmental influence 3.functional influences (3)abnormal swallowing The tongue between the upper and lower teeth upper dental arch protrusion openbite

Environmental influence 4. oral bad habits (1) suck habits anterior teeth can not erupt properly openbite thumb sucking dental arch stenosis upper jaw protrusion obstruction of nasal cavity development fingers bend

Environmental influence 4. oral bad habits (2) tongue habits licking teeth tongue thrusting dental arches protrusion openbite mandible protrusion anterior crossbite

Environmental influence 4. oral bad habits (3) lip habits biting lower lip upper anterior teeth protrusion and sapcing lower anterior teeth crowding mandible retraction overbite and overjet

Environmental influence 4. oral bad habits (3) lip habits biting upper lip upper teeth inclining lingually mandible protrusion, anterior teeth crossbite

Environmental influence 4. oral bad habits (4) biting habit local openbite

Environmental influence 4. oral bad habits (5) asymmetrical chewing waste using side with low chewing function, self-cleaning effect is poor mandible, the center line skewing to chew side • facial asymmetry

Environmental influence 5. Local disturbances in primary dentition and mixed dentition (1) early loss of primary teeth a single tooth loss earlier adjacent teeth inclining space reduced occlusion relationship disorder

Environmental influence 5. Local disturbances in primary dentition and mixed dentition (1) early loss of primary teeth many teeth loss earlier anterior teeth crossbite overbite and overjet crowding

Environmental influence 5. Local disturbances in primary dentition and mixed dentition (2) delayed loss of primary teeth

Environmental influence 5. Local disturbances in primary dentition and mixed dentition (3) insufficient attrition of primary caine early contact pain crossbite

Environmental influence 5. Local disturbances in primary dentition and mixed dentition (4) early loss of permanent teeth (5) premature eruption of permanent teeth (6) improper eruption sequence of permanent teeth

summary race evolution Genetic influence individual development congenital causes etiology acquired causes functional influences Environmental influence oral bad habits local disturbances in primary dentition and mixed dentition

summary Nomatter which malocclusion, its closely related to body’s development and growth. These etiology factors are related to each other not only on the classification, but also on the influence to our bodies.

question What is the etiology of malocclusion?