Comprehensive Evaluation of Posttreatment Skeletal, Dental and Soft Tissue Changes

Abstract

One of the most important challenges the orthodontist faces is producing an orthodontic result that is stable. While many investigators have analyzed postretention stability, they have focused on specific variables. These include lower incisor crowding, intercanine distance and arch form alteration. However, to effectively analyze posttreatment stability, one must also examine the occlusion, skeletal changes and soft tissue changes that. Thus, the objectives of this study were to: 1. Comprehensively evaluate posttreatment skeletal, dental and soft tissue changes and 2. compare the stability of cases from the Indiana University School of Dentistry (IUSD) Graduate Orthodontic Clinic to those of a private practitioner. The null hypotheses of this study were:

There were no significant differences (p <0.05) in the amount of change from immediately posttreatment to two years posttreatment for the 150 cases evaluated.

There were no significant differences (p < 0.05) in posttreatment stability between the IUSD Graduate Orthodontic Clinic and those treated by a private practitioner.

There were no significant differences (p <. 05) in the quality of finish between IUSD and private practice.

One hundred dental records from the IUSD Graduate Orthodontic Clinic and fifty from the office of a private practitioner were used in this analysis. Posttreatment and two year posttreatment dental casts were scored according to the American Board of Orthodontics Grading System for Dental Casts and Panoramic Radiographs. Lateral cephalometric radiographs from three time points (pretreatment, immediately posttreatment and at least two years posttreatment) were traced and measured to assess posttreatment skeletal and soft tissue changes. Except for two of the individual ABO categories, none demonstrated statistically significant changes over the two year posttreatment period. There was a statistically significant increase in 1st order alignment score and a statistically significant decrease in occlusal contact score for this period. This indicates that there is a tendency for posttreatment rotational relapse. Also, the reduction in the occlusal contact score indicates a settling of the occlusion over the two year posttreatment period. Intercanine and intermolar measurements were made to assess arch form stability. It was found that there were statistically significant increases in upper and lower intercanine distances from pretreatment to posttreatment, but the amount of change between posttreatment and two years posttreatment was not statistically significant. Cephalometrically, several of the measurements demonstrated changes from pretreatment to posttreatment. The dental measures /1 (A-Pg) and 1/(FH) were significantly increased for this time period. Also, /1 (MP) was statistically decreased for this time period. The skeletal measures N-A-Pg, SNA and ANB were statistically lower at the completion of treatment. Lip protrusion was statistically reduced from pretreatment to either posttreatment time point. Although statistically significant differences were found in two of the parameters evaluated, the majority demonstrated no statistical significance. It is the conclusion of this investigation that posttreatment changes in most of the parameters studied are stable over a two year period.