Murphy C Chris, Magness W Bonham, English Jeryl D, Frazier-Bowers Sylvia A, Salas Anna Maria
Department of Orthodontics, Dental Branch, University of Texas Health Science Center at Houston, 77030, USA.
Angle Orthod. 2003 Aug;73(4):396-400. doi: 10.1043/0003-3219(2003)073<0396:ALSOIE>2.0.CO;2.
A retrospective study using models was performed to evaluate the incremental expansion that occurred during mandibular lip bumper therapy in 44 adolescent patients. The purpose was to determine whether expansion occurs evenly between appointments or whether it attenuates with treatment time. Dental cast measurements were made for arch width and arch length. Treatment duration was broken into near-equal time segments and compared. Results showed that about 50% of the total expansion achieved occurred within about the first 100 days. Forty percent of the total amount of expansion occurred during the next 200 days, with only about 10% of the total expansion occurring after the first 300 days. It is unnecessary to have the appliance in place for longer than 300 days. The percentage of expansion that occurred at each time segment was not related to whether the patient had concomitant maxillary expansion.
