Average arch widths and associated changes between initial, post-treatment and post-retention measurements.

Computer image monitoring was used for evaluation of dental arch changes. A new special device captured geometrically calibrated images permitting comparison of several different dental casts. In the first part of this study 792 sets of study casts were screened. Measurements of dental arch width between reference points of canines, first premolars and first molars were made: upper jaw: men: canines: 35.1 +/- 0.13 mm; first premolars: 37.5 +/- 0.13 mm; first molars: 48.1 +/- 0.19 mm; women: canines: 33.4 +/- 0.13 mm; first premolars: 35.6 +/- 0.15 mm; first molars: 46.7 +/- 0.19 mm. In the second part of the study, changes between initial, post-treatment and post-retention alignment (5-years after orthodontic therapy) of upper and lower dental arch of 36 subjects were analyzed. Upper and lower arch compression in first premolars and molars area was visible before treatment. We conclude that computer image monitoring can be used for evaluation of dental arch changes during the different steps of treatment.