Pressure from the lips on the teeth and malocclusion

Area of Science:

• Orthodontics and Dental Morphology
• Pediatric Dentistry
• Biomechanical Analysis of Oral Structures

Background:

• Understanding the interplay between lip function and dental occlusion is crucial for diagnosing and treating malocclusion.
• Previous research has explored lip muscle activity and its effects, but direct correlations with lip pressure in pediatric populations with malocclusion require further investigation.

Purpose of the Study:

• To investigate the relationship between lip strength and lip pressure in children with diverse malocclusion types.
• To analyze how different malocclusion classifications (Angle Class I, II/1, II/2) affect lip pressure on incisors.
• To explore potential correlations between lip muscle activity, bite morphology, and facial patterns.

Main Methods:

• Lip strength was quantified using a dynamometer in 84 children (aged 7–16 years).
• Lip pressure on central incisors was measured at rest, during chewing, and swallowing using an extraoral pressure transducer system.
• Electromyography recorded lip muscle activity, while dental casts and cephalograms assessed bite and facial morphology.

Main Results:

• No significant correlation was found between measured lip strength and lip pressure.
• Children with Angle Class II, Division 1 malocclusion exhibited lower lip strength compared to those with Angle Class I malocclusion.
• Lip pressure on upper incisors was highest in Angle Class II, Division 1 and lowest in Angle Class II, Division 2 malocclusion.

Conclusions:

• Lip strength is not a direct determinant of lip pressure exerted on the teeth.
• Incisor position appears to be a primary factor influencing the magnitude of lip pressure in pediatric malocclusion.
• These findings have implications for orthodontic treatment planning, particularly concerning the management of lip-tooth relationships.