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Table 1 Extraction of data

From: Pain level between clear aligners and fixed appliances: a systematic review

Authors, (year) Type of study (country) Sample size, male/female ratio, and age (mean ± sd) per group (age) Intervention Assessment of pain Time of evaluation Sequence Pain outcomes Overall outcomes Other outcomes Analgesic consumption Author’s conclusion
Archwire Align
Almasoud (2018) [10] Prospective CCT (Saudi Arabia) CG: n = 32, 12M/20F (23.56 years ± 5.44)
IG: n = 32p, 10M/22F (28.47 years ± 8.17)
CG: Passive self-ligating (Damon)
IG: Invisalign
VAS 10 cm 4 h; 24 h; 3rd, and 7th day .014″ NiTi Firsts aligners Patients treated with IG had significantly lower pain level than did those in CG at all timepoints. The highest pain level was 24 h Higher numbers of participants reported having pain at 4 h and lower number in day 7 More patients in CG took analgesics when compared with the IG Yes (acetaminophen/paracetamol) Patients treated with Invisalign observed lower pain than did with braces. ↑of pain was experienced at 24 h and ↓ at day 7 in both groups
Flores-mir et al. (2018) [13] Cross-sectional (Alberta, Canada) CG: n = 4, NA (NA)
IG: n = 81, NA (NA)
CG: conventional fixed appliance)
IG: Invisalign
DIDL (Dental Impacts on Daily Living)
PSQ (Patient Satisfaction Questionnaire)
End of treatment NA NA Similar satisfaction Eating and chewing: IG reported a better satisfaction Patient satisfaction remained relatively similar 6 months later for the bracket-type treatment No Both groups treated patients had statistically similar satisfaction outcomes, except for eating and chewing
Fujiyama et al. (2014) [20] Prospective CCT (Ohio) CG: n = 55, 25M/35F (26.45 years ± 5.45)
IG1: n = 38, 10M/28F (26.64 years ± 5.69)
IG2: n = 52, 19M/33F (25.24 years ± 6.51)
CG: Edgewise (straight wire with .018 slot)
IG1: Invisalign (IG)
IG2: Edgewise + Invisalign (EIG)
VAS 10 cm 1°: 60 s, 6 h, 12 h, 1–7 days
2°: 3 weeks after
3°: 5 weeks after
Slot .018″ Use 20 h/day EG was significantly higher than others IG was significantly ↑ than others (intensity of pain, no. of days, discomfort) NA No Invisalign causes less pain compared to the traditional edgewise treatment; problems such as tray deformation must be carefully checked in the use of Invisalign.
Mais-Damois et al. (2015) Prospective CCT (Canada) CG1: n = 19, NA (NA)
CG2: n = 20, NA (NA) 18M/21F (14.5 years)
IG: n = 31, 11M/20F (16 years)
CG1: Damon S
CG2: Speed
IG: Invisalign
VAS 0 h, 5 h, 24 h, 3rd, 7th, 14th day - .016″ NiTi
- .016″ CuNiTi
- .016″ × .022″ CuNiTi
- .019″ × .025″ CuNiTi
Aligners 1, 4, 7, and 10 Invisalign group reported lower pain than fixed appliances Patients with Invisalign reported significantly less tissue irritation than patients with fixed brackets Quality of life was slightly affected in the first phase higher in CG than in IG) Yes
Exclusively during the first week of treatment
Perception of pain with Invisalign was lower than with fixed appliance. This method of treatment is an attractive therapy for patients wishing for an esthetic treatment.
Changed each 2 weeks
Miller et al. (2007) [11] Prospective CCT (USA) CG: n = 27, 6M/21F (28.6 years ± 8.7)
IG: n = 33, 11M/22F (38 years ± 12.4)
CG: preadjusted fixed appliance (NA)
IG: Invisalign
- Daily diary: functional, psychosocial and pain-related (Likert Scale)
- Pain (VAS)
NA NA NA Fixed appliances group reported more pain beginning at day 1 through day 7 Invisalign and fixed appliances reported decreases in OHRQL after treatment beginning The fixed appliances subjects took more pain medication during days 2 and 3 Yes The Invisalign subjects’ overall OHRQL was better than that of the fixed appliances subjects.
Shalish et al. (2011) [12] Prospective CCT (Israel) CG1: n = 28, 14M/14F (NA)
CG2: n = 19, 4M/15F (NA)
IG: n = 21, 5M/16 F (NA)
CG1: Buccal group (straight wire GAC and Ormco)
CG2: Lingual group (Incognito)
IG: Invisalign group
HRQoL
VAS (pain)
7 consecutive days and at day 14 .014″ NiTi NA Pain levels decreased from the 1 to 7 day. ↑ Invisalign and Lingual group Day 1: ↑ % pain in Invisalign group;
Day 2: Lingual group;
Small % of buccal group reported severe pain
Oral dysfunction, disturbances in eating, general activity, recovery time: ↑ Lingual group Yes
Highest in the Lingual group (similar to the buccal group)
Lingual appliance was associated with more severe pain and analgesic consumption, the ↑ oral and general dysfunction, and the most difficult and longest recovery
White et al. (2017) [2] RCT (USA) CG: n = 18, 6M/12F (NA)
IG: n = 23, 11M/12F (NA)
CG: Fixed clear appliance upper arch (Radiance) and metal brackets lower arch (Alexander)
IG: Invisalign
VAS (10 cm) Initial adjustment: daily diary for 7 consecutive days
Subsequent adjustments (2):
Daily diary for 4 days
- .016″ CuNiTi
- .017″ × . 025″ CuNiTi
- .016″ × .022″ SS
- .017″ × .025″ SS
Change each 2 week and use 22 h/day 1°: higher in CG;
2° 3°: higher in CG
Discomfort was significantly higher in CG during the 1st
week and subsequent adjustments
First 3 days after bonding: more discomfort when chewing with fixed appliances.
Analgesic consumption: higher in CG in the first week; 1° and 2° adjustment no ≠
No ≠ in sleep disturbances
Yes Traditional fixed appliances produced significantly more discomfort than did aligners.
Patients treated with aligners and fixed appliances reported significantly less discomfort at subsequent adjustments than after the initial bonding or appliance delivery.
  1. CCT non-randomized controlled clinical trial, RCT randomized clinical trial, VAS visual analog scale, OHRQL oral health-related quality of life, NA not available