Failure rates and survival analysis of maxillary expansion appliances: a 24-year retrospective analysis

The purpose of this study was to describe the failure rates of maxillary expansion appliances (MEAs) and assess risk variables associated with failures and treatment time.

Retrospective chart reviews were performed on 436 primary or mixed dentition patients presenting with crossbite to a private practice between 1981-2005. Survival analysis was used to analyze and compare the types of MEAs with respect to the treatment time. The effect of demographic and clinical characteristics on appliance failure and treatment time was assessed using linear and logistic regression models.

The average age at insertion of a MEA was 8 years, 4 months (+/-1.72 SD). Nineteen percent (n=84) of the MEAs failed, with a median treatment time for all appliances of 216 days (interquartile range=126 days). Cement loss (69%) was the most common type of failure. The likelihood of an appliance failing increased in children with a malocclusion other than Class I (adjusted odds ratio=1.91; 95% CI=1.16-3.14) and was nearly 4 times greater when a quad helix was used compare to the Haas appliance (adjusted odds ratio=3.60; 95% CI=1.92-6.75). The treatment time was significantly affected by the type of crossbite present and the occurrence of an appliance failure (P=.001).

The use of a quad helix appliance and the presence of malocclusion other than Class I was significantly predictive of appliance failure. Treatment time was increased when MEAs failed and bilateral crossbite was present.