Effects of buccal shields on mandibular dental arch parameters: a clinical and cephalometric study.

The lip bumper is a vestibular functional appliance designed to extend bilaterally between the mandibular buccal tubes and contact the inner surface of the lower lip and cheeks. It functions to eliminate the pressure on the incisors, canines, and premolars, and to transmit distally directed forces to the molars. The purpose of this study was to evaluate the short-term effects of the buccal shield modification of the lip bumper design on various mandibular dental arch parameters, as well as on the inclination of the mandibular incisors. Included in the present study were 44 consecutively treated patients, consisting of 29 females and 15 males from a private orthodontic practice. Student and paired t tests were used to evaluate the changes over time for the various measurements. The results indicated a significant (P < .0001) increase in all arch parameters measured. The greatest mean expansion was observed at the first (5.0 +/- 2.2 mm) and second (3.4 +/- 2.2 mm) premolar width measurements. Less expansion occurred in the intercanine (2.4 +/- 2.0 mm) and intermolar (2.4 +/- 2.6 mm) arch widths. Arch length increased on average 1.6 +/- 2.1 mm. These were significantly (P <.0001) greater than the normal age-related changes in the corresponding parameters.