Vertical facial pattern and orthodontic stability Part I: Pretreatment vertical pattern and stability

The occlusions of sixty patients treated by one experienced orthodontist were assessed using the PAR Index. For each patient, pretreatment, post-treatment and long-term follow-up study casts were examined. Follow-up casts were taken at least 6.5 years following the removal of all retention appliances. Following pretreatment cephalometric analysis, the patient sample was divided into three vertical facial subgroups according to the Jarabak Facial Height Quotient. Mean weighted PAR scores were then calculated at each stage for the total sample and for the three subgroups. Mean absolute and percentage occlusal changes were also calculated for the post-treatment period. The relationship between post-treatment occlusal change and pretreatment vertical facial pattern was then studied.

The mean weighted pretreatment, post-treatment and follow-up PAR scores were 27.3, 3.3 and 8.0, respectively. The mean absolute and percentage post-treatment increases in weighted PAR score were 4.7 and 25.4, respectively. No statistically-significant relationship could be found between the pretreatment vertical facial pattern and changes occurring in the weighted PAR score during the follow-up period. It was concluded, therefore, that pre-treatment vertical facial pattern, at least on its own, is not likely to be predictive of the amount of post-treatment occlusal change.