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Comparative Study
. 2014 Nov 22;15(1):64.
doi: 10.1186/s40510-014-0064-7.

Analysis of pain level in cases treated with Invisalign aligner: comparison with fixed edgewise appliance therapy

Koji Fujiyama, Tadashi Honjo, Makoto Suzuki, Shinya Matsuoka, Toru Deguchi  1
Affiliations
Comparative Study

Analysis of pain level in cases treated with Invisalign aligner: comparison with fixed edgewise appliance therapy

Koji Fujiyama et al. Prog Orthod. .

Abstract

Background: The aim of this study was to evaluate and compare the difference in the level of pain using the visual analog scale (VAS) between cases treated with the edgewise appliance and Invisalign. In addition, the cause of pain and discomfort in the Invisalign cases was identified.

Methods: The sample consisted of 145 cases for the edgewise group (EG; n=55), Invisalign group (IG; n=38), and edgewise and Invisalign group (EIG; n=52). VAS scores were collected during the first three stages (first stage: 0 to 7 days, second stage: 14 to 21 days, and third stage: 28 to 35 days) and at the end of the treatment (overall VAS score). Evaluation of the cause of pain was categorized into three different types of problem (category 1: non-smoothed marginal ridge or missing materials, category 2: deformation of attachments, and Category 3: deformation of the tray). Statistical comparison of VAS scores between groups was performed by two-way analysis of variance.

Results: A significantly higher VAS score was observed at 3 and 4 days after, at 1, 2, and 3 days after, and at 2 and 3 days after in stages 1, 2, and 3, respectively, in EG compared to EIG and IG. A significant difference was observed in overall VAS scores between EG and IG in intensity of pain, number of days that pain lasted, and discomfort level. Only intensity of pain resulted in a significant difference between EG and EIG. Most of the causes of problem in the Invisalign cases were deformation of the tray.

Conclusions: Invisalign may offer less pain compared to the edgewise appliance during the initial stages of treatment. In the use of Invisalign, deformation of tray must be carefully checked to avoid pain and discomfort for the patients.

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Figures

Figure 1
Figure 1
Three categories of reasons for pain or discomfort. Category 1 indicates trays with some materials missing (arrow in (A)) or non-smooth edges (arrow in (B)). Category 2 indicates deformation of the attachments at the occlusal margin (arrows in (C)) and at the gingival margin (arrow in (D)). Category 3 indicates deformation of the tray in vertical dimension (E) and in transverse dimension (F).
Figure 2
Figure 2
Graph showing changes of VAS score during the first stage (h: hours). *Significant difference compared with EIG and IG; p < 0.05.
Figure 3
Figure 3
Graph showing changes of VAS score during the second stage (h: hours). *Significant difference compared with EIG and IG; p < 0.05.
Figure 4
Figure 4
Graph showing changes of VAS score during the third stage (h: hours). *Significant difference compared with EIG and IG; p < 0.05.
Figure 5
Figure 5
Overall VAS score for intensity of pain. *Significant difference compared to EIG and IG; p < 0.05. **Significant difference compared to IG; p < 0.05.
Figure 6
Figure 6
Overall number of days that pain lasted. *Significant difference compared to IG; p < 0.05.
Figure 7
Figure 7
Overall discomfort level. *Significant difference compared to IG; p < 0.05.
Figure 8
Figure 8
Overall VAS scores in IEG. Overall VAS scores for intensity of pain (A), number of days that pain lasted (B), and discomfort level (C) in IEG. *Significant difference between two groups; p < 0.05.
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