Evaluation et quantification de différents facteurs influençant le temps de traitement orthodontique

INTRODUCTION: One of the main concerns of orthodontic patients is the overall treatment time wearing braces. The patient’s desire is to obtain an aesthetic and functional result in minimum time. Prior to considering approaches which are supposed to reduce treatment time, it is essential to understand the factors that may lengthen it. A quick and efficient correction of the malocclusion is both beneficial to the patient and to the treating orthodontist. This reduces the potential side effects of prolonged treatment (caries, bone loss, white spot lesions, etc.), while allowing the orthodontist to better control office expenses arising from the proper functioning of the clinic. OBJECTIVE: The objective of this study was to evaluate and quantify the variables that may influence the orthodontic treatment time. MATERIALS & METHODS: The study included records of 300 retention patients who were treated at the graduated orthodontic clinic, Faculty of dentistry, University of Montreal. Eight of them were excluded due to poor monitoring of their treatment related to health problems or because of lacking data. The following variables were evaluated: patient’s age and sex, the clinical and radiological data related to the malocclusions, the elements used in the planning and execution of treatment and the degree of patient cooperation. Uni-varied analyses (chi-square, t-test and ANOVA) were used to identify variables that affect treatment time. The data distribution normality was evaluated by the Shapiro-Wilk test. A p value <0.05 was considered statistically significant. Subsequently, a multiple regression analysis was used to build a model to predict the treatment time. RESULTS & DISCUSSION: We found that cooperation was an important factor in the variation in treatment time. Each missed appointment (MA) and each debonded bracket requiring rebonding increased the active time with fixed appliances by 2.3 months and 1 month, respectively. There are numerous variables affecting the duration of the active phase, ranging from planning extractions to other selected treatment protocols. For example, the use of Assure® resin and Transbond XT ™ adhesive resulted in a more effective and shorter treatment time, while limiting the number of debonded brackets. Age had no influence as opposed to the severity of the initial malocclusion (overjet [OJ] and overbite [OB]) which, for example, increased the treatment time by about 10 days per point of discrepancy index (DI) or 0.7 months per millimeter of class II according to the Angle classification. The collected data allowed us to establish the following prediction model: estimated treatment time = 12.606 months + 0.316 (if male) + 0.084 x (OJ value) + 0.301 x (OB value) + 0.339 x (per point of DI) + 0.699 x (Severity of Cl II) + X (type of adhesive) + Y (type of resin) + Z (type of bracket) + 4.297 (if extractions) + 4.163 (if elastics needed) + 1.750 (if clinician graduated more than 15 years ago) + 2.297 x (by MA) + 0.971 x (by the number of debonded brackets). CONCLUSION: This study revealed that the duration of orthodontic treatment is influenced by the following factors in order of importance: extraction (s), cooperation, initial malocclusion, adhesive and resin products, bracket type, clinician’s years of experience and patient gender. Keywords: Orthodontics, treatment time, cooperation, debonded bracket(s), malocclusion.

Keyphrases: Malocclusion, Orthodontics, Treatment time, Debonded bracket