Patterns of dental crowding in the lower arch and contributing factors. A statistical study.
OBJECTIVE
To investigate the patterns of dental crowding in the lower arch and their contributing morphological and functional factors.


METHODS
Pretreatment diagnostic materials from 168 patients exhibiting dental crowding were selected, and the patients, dental casts, lateral cephalograms, and occlusal forces were evaluated. The crowding in the lower dental arch was quantified and the patterns of crowding were identified. Crowding patterns in the anterior region were classified by cluster analysis. The relationship between the crowding patterns and morphological and functional factors was investigated by correspondence analysis.


RESULTS
The prevalence of dental crowding was highest in the anterior region and was related to the same tooth on each side (eg, right lateral incisor vs left lateral incisor). In the premolar and molar region, the prevalence of dental crowding was related to the adjacent tooth (eg, right first premolar vs second premolar). Three crowding patterns were found in the anterior region: (1) a "symmetry pattern," (2) a "rotation pattern," and (3) an "irregular pattern." The first pattern was related to the factors of discrepancy, whereas the latter two patterns were related to functional factors such as occlusal force and its center of gravity.


CONCLUSIONS
These results suggest that crowding patterns can be useful information for treatment planning and achieving dental stability.
Shigenobu
Noriko
N
Department of Orthodontic Science, Tokyo Medical and Dental University, Japan. noriorts@yahoo.co.jp
Hisano
Masataka
M
Shima
Sachiko
S
Matsubara
Nozomu
N
Soma
Kunimichi
K
D001732:Bite Force; D002508:Cephalometry; D016009:Chi-Square Distribution; D003724:Dental Arch / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000145:classification* / Q000453:epidemiology / Q000473:pathology; D008334:Mandible / Q000033:anatomy & histology; D015995:Prevalence; D012399:Rotation; D018709:Statistics, Nonparametric