Rickett's and Holdaway analysis following extraction of four premolars and orthodontic treatment in bimaxillary protrusion female Malays

Aim: To quantify the amount of soft-tissue changes in Malaysian female patients treated with the extraction of first four premolars. Materials and Methods: This is a retrospective study involving 24 Malaysian female patients age between 18 and 24 years treated with extraction of the upper and lower first premolars and bonded by 0.22 x 0.28 ' ' standard edgewise technique. The average of treatment time was 22 months. Pre and posttreatment lateral cephalograms of patients were traced on a cephalometric tracing software CASSOS (Soft Enable Technology Limited, Hong Kong). Linear and angular measurements were made. Data were analyzed using paired t-test to determine the difference between two means. Results: All linear and angular measurements of hard- and soft-tissue changes showed significant differences except L1 to A-pogonion (A-pog) angle (P = 0.05), and the mean change has decreased to almost 1.0mm posttreatment. The Pearson's correlation test showed that the lower lip contacts both the upper and lower incisors; hence, the lower lip position would be impacted not only by the lower incisor retraction but also by the upper incisor retraction. Conclusion: In Malaysian females, significant changes were found in soft-tissue profile post-orthodontic treatment with corresponding simultaneous change in the underlying hard tissue.