Maximum closing force of mentolabial muscles and type of malocclusion.
OBJECTIVE
To measure the closing force of the upper and lower lips and to ascertain the relationship between the maximum closing force of the mentolabial muscles and types of malocclusion.


METHODS
Of those who showed the full eruption of a second molar and no permanent tooth loss, 99 subjects were chosen who showed a positive overbite and ANB and no skeletal asymmetry. By using the Y-meter, which can measure the lip force in the vertical direction using a load cell, the closing forces of the upper and lower lips were measured separately. A one-way analysis of variance (ANOVA) test and the Pearson's correlation test were used to evaluate the interrelationship between lip force and dentofacial morphology.


RESULTS
The lip closing force was greater in male and Class I subjects. Upper lip force was greater than that of the lower lip in all groups. The values of lip closing forces were related to the variables of upper incisor angulation. In Class II subjects, the values of lip closing forces were also related to the vertical skeletal pattern.


CONCLUSIONS
The mentolabial muscle force was highly correlated with dentofacial structure and types of malocclusion.
Jung
Min-Ho
MH
Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea. fortit@chol.com
Yang
Won-Sik
WS
Nahm
Dong-Seok
DS
D002508:Cephalometry / Q000379:methods; D005152:Facial Muscles / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007180:Incisor / Q000473:pathology; D008046:Lip / Q000502:physiology*; D008297:Male; D008310:Malocclusion / Q000145:classification* / Q000503:physiopathology; D008311:Malocclusion, Angle Class I / Q000473:pathology / Q000503:physiopathology; D008312:Malocclusion, Angle Class II / Q000473:pathology / Q000503:physiopathology; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D009119:Muscle Contraction / Q000502:physiology*; D012737:Sex Factors; D014716:Vertical Dimension; D055815:Young Adult