Comparison of soft tissue profile changes in serial extraction and late premolar extraction.

To assess soft tissue profile changes through time, a comparison was made of patients treated by serial extraction without subsequent orthodontic treatment (n=28), patients treated with serial extraction and orthodontic treatment (n=30), and patients treated orthodontically with late extraction (n=30). Cephalometric radiographs were traced and digitized; linear and angular measurements were made with a custom computer program that allowed digitization of specific soft tissue points. Maxillary, mandibular, and overall cephalometric superimpositions and linear measurements of change from the superimpositions were done by hand. Statistical analyses were made to determine if significant differences existed within each group at each time period and between groups at each time period, as well as between males and females at each time period. Data were also analyzed to determine if significant correlations existed between any hard tissue variable and any soft tissue variable, or between any soft tissue variable and any other soft tissue variable. It was found that in those patients treated with late premolar extraction, the most labial point of the mandibular incisor was more posterior from pretreatment to posttreatment than in the serial extraction group. While a great number of associations existed between variables, no significant differences were found between the soft tissue profiles of these three groups of patients. The gender differences that were found to exist were most likely due to normal maturational changes, not the treatment itself.