Predictors of Pre-surgical Orthodontic Outcome

Objective:  To identify variables that influence pre-surgical orthodontic treatment outcomes.

Methods:  25 surgical-orthodontic patients were selected from the OSU Dentofacial program archival database.  Pre-treatment (T1) and pre-surgical (T2) lateral cephalometric measurements of upper incisal inclination to Frankfort’s Horizontal (FH) and lower incisal inclination to the mandibular plane were made to evaluate the amount of dental decompensation achieved during pre-surgical orthodontics.  Based on their T2 incisal inclination, subjects were divided into successful (upper incisor 110±1SD and lower incisor 90±1SD) and unsuccessful (greater than 1 standard deviation) groups.  Selected variables were recorded from each patient’s chart to include:  age, gender, pre-surgical treatment duration (mos), number of appointments, extraction status, use of inter-maxillary elastics, pre-surgical arch wire dimension, and orthodontic appliance slot size.  The slot size differential was calculated by subtracting wire size from slot size.  A noncompliance score was calculated by adding the total number of chart entries on poor oral hygiene, broken appointments, and appliance breakages.  Data were analyzed using the two-tailed Mann-Whitney-Wilcoxon test, Fisher Exact test, and logistic regression.

Results:  Successful decompensation occurred in 52% of pre-surgical maxillary position, while only 36% of the patients had successful mandibular incisor decompensations. While bivariate analysis revealed that none of the factors evaluated had a significant effect on outcome, multivariate analysis did reveal significant effects.

Multivariate Logistic Regression Analysis:

Conclusions:  1) Maxillary incisal angulation was significantly affected by gender and the slot-wire differential. 2) Mandibular incisor outcome was significantly affected by the pre-treatment incisal angulation, patient compliance and the use of inter-maxillary elastics.