NO EFFECT OF LIP BUMPER THERAPY ON THE PRESSURE FROM THE LOWER LIP ONTHE LOWER INCISORS

The pressures from the lower lip on the lower incisors were measured a t the midline between the central incisors and between the left latera l incisor and canine. The measurements were made with the lip at rest and during swallowing of water in 24 boys and 40 girls aged 9-15 years . The children were divided into four groups, two treated with a lip b umper with and without an oral shield, and two with a lingual arch wit h and without springs for proclination of the lower incisors. Recordin gs of the pressures were made before the start of the treatment, and 3 and 8 months after the use of the appliance, as well as 4 months afte r the removal of the lip bumper or lingual arch. The treatment with a lip bumper did not change the pressure from the lip on the lower incis ors at rest. The pressure at the midline during swallowing was also un affected by the lip bumper therapy, but the pressure between the later al incisor and canine increased. Thus, lip bumper therapy did not lead to decreased pressure from the lip on the incisors. Proclination of t he lower incisors with a lingual arch resulted in an increase of the p ressure from the lip at rest. Thus, no adaptation of the lower lip to the proclination occurred. After relapse of the proclination the press ure from the lip decreased to a value no different from that before th e start of the treatment.