Comparaison de la perception de la douleur entre le traitement orthodontique avec Invisalign® et le traitement avec fils et boîtiers fixes

Introduction : The discomfort caused by the orthodontic appliances can significantly affect patients cooperation during their treatment. Pain and function deterioration (chewing, speech) are recognized as major determinants of patients cooperation treated with removable appliances. Invisalign® is positioned as an aesthetic alternative to the many discomforts observed during treatment with fixed brackets. To date, few studies have compared the pain (quantitatively and qualitatively) between this technique and fixed appliances over a long period.  Objective : The objective of this study is to assess the pain experienced in the first six months with Invisalign® treatment and compare it to the pain felt during conventional orthodontic treatment with fixed self-ligating brackets.  Methods : The study was comprised of 70 patients (29 males,  41 females), with an age mean of 15.7 (range 11 to 30). The three subgroups are Invisalign® (n = 31), Damon (n = 19) and Speed (n = 20). The two bracket groups, Damon (passive) and Speed (active), were treated in the Orthodontic Clinic at the University of Montreal in 2011, and were compared (active vs. passive self-ligating brackets) for the perception of pain during orthodontic treatment. The study was conducted in four phases corresponding to the insertion of the first 4 wires for groups with brackets (Phase 1: 0.016 " Supercable, Phase 2: 0.016" CuNiTi, Phase 3: 0.016" x 0.022" CuNiTi, and Phase 4: 0.019" x 0.025" CuNiTi) and the insertion of aligners 1, 4, 7 and 10 for the Invisalign group. Using a questionnaire, the study evaluates the pain magnitude for each phase (using a visual analogue scale VAS), the duration, and location of the pain in 6 different time points (T1: immediately after insertion, T2: 5h later, T3: 24h later, T4: 3 days later, T5: 1 week later, T6: 2 weeks later). Results: At T1Ph3 the percentage of patients reporting pain was higher with Damon than with Invisalign® (p = 0.032) (Damon = 55.6%, Invisalign® = 23.3%), but there was no difference with Speed (p = 0.114). Patients with Invisalign® reported significantly less irritation of the soft tissues (mucous membranes, gums) than patients with brackets. For the VAS results, the differences were statistically significant at 2 stages: T3Ph1 (median Invisalign® = 33.31, Median Speed = 49.47, p = 0.025) and T3Ph4 (median Invisalign® = 13.15, median Damon = 27.28, p = 0.014). For most patients, the pain does not require medication and there was no significant difference between the groups in this respect. Quality of life was slightly affected during the first phase and less for the Invisalign® group than for the bracket groups. For Invisalign® patients, pain reached its highest level between 5 and 24 hours after insertion of the first aligner, and decreased in intensity and duration at each phase. Conclusion: The pain perception during orthodontic treatment with Invisalign® is lower than the pain experienced during treatment with fixed brackets. This method of treatment is therefore an attractive therapy for patients wishing for an aesthetic and reasonably comfortable treatment.

Keyphrases: Invisalign®, Pain, Brackets, Orthodontics