Description
Crowding
Crowding can be defined by severity, location and type.
Severity
Mild crowding is defined as less than 4mm of space deficiency to their arch size, moderate crowding is 4 to 8mm of space deficiency to their arch size and severe crowding is more than 8mm of space deficiency to their arch size (Cobourne and DiBiase 2010). Tooth sizes and arch sizes vary among individuals, the former is primarily genetically determined and the later is influenced by genetics and the soft tissues predominantly. Space deficiencies can be calculated several ways including as a visual estimate, a treatment objective-based analysis, like the Royal London Space Analysis (Kirschen 2000), or mixed dentition analyses like Moyers analysis 1971 and Tanaka and Johnson 1974.
Location
Dental crowding most commonly expresses in the incisor regions however posterior crowding (e.g. maligned or impacted molars) is also present.
Type
There are three types of crowding. Primary crowding is the tooth and jaw size discrepancy (e.g. large teeth relative to the jaw size) which is often a genetic cause. Secondary crowding is common and involves the loss of space due to environmental factors such as early loss of deciduous teeth, supernumeraries/obstructions etc. Tertiary crowding is predominantly late incisor crowding and arises from a range of causes which is described at the diagnosis section.
