Table 1.
Characteristics of included studies
| Authors (year), type | Participants | Intervention | Comparator | Outcomes | Additional information |
|---|---|---|---|---|---|
| Abbate et al (2015), RCT | 50 teenagers (10–18) treatment with fixed brackets (n = 25) Treatment with Invisalign aligners (n = 25) |
Invisalign | Fixed labial brackets | Full mouth plaque score Full mouth bleeding score Plaque index Bleeding on probing Probing depth Oral hygiene compliance |
3 dropouts on aligner group Timeline: 3, 6, 12 months |
| Albhaisi et al (2020), RCT | 49 participants, 39 female, 10 male, 21.25±3, range 17–24 | Clear aligners | Fixed labial appliances | Fluorescence loss (ΔF) Number of newly developed lesions Deepest point in the lesion (ΔFMax) Lesion area (pixels) and plaque surface area (DR30) were measured as secondary outcomes. Fluorescence was assessed using QLF. |
Timeline: 3 months (use of attachments) |
| Azaripour et al (2015), retrospective cohort | 100 participants: 50 with Invisalign (11 males and 39 females, mean age 31.9 ± 13.6 years; range: 12–61 years) and 50 with fixed appliances (34 females and 16 males, mean age 16.3 ± 6.9 years old; range 11–61 years) | Invisalign | Fixed labial appliances | API SPI GI |
Timeline: 12 months (at least 6 months in treatment) |
| Bushang et al (2018), retrospective cohort | 450 participants, aligners (30.4 ± 14 years), fixed (29.2 ± 11.5 years), aligners (64% females, 36% males), fixed (63% females, 37% males) | Clear aligners | Fixed labial appliances | OH WSLs |
85% of the aligner cases and 48% of the fixed cases were taken from private practice Timeline: throughout treatment duration |
| Chhibber et al (2017), RCT | 71 participants 41 boys 30 girls. Mean ages of participants 16.56 + 3.99 in CLA group (27 participants), 15.39 + 3.54 in SLB group (22 participants), and 14.56 ± 3.92 in ELB group (22 participants) | Invisalign | Self-ligating brackets Elastomeric ligating brackets |
PI GI PBI |
Three in the CLA group, 5 in the SLB group, and 2 in the ELB group were completely lost to follow-up, and 2 in the SLB group and 1 in the ELB group were partially followed-up. Timeline: 9 and 18 months |
| Dallel et al (2020), PCT | 112 participants, 10–20 years of age, 49.1% females, 50.9% males | Invisalign | Fixed labial appliances Andresen type II activator |
Volume and salivary flow Biochemical parameter measurement Trolox equivalent antioxidant capacity WSLs |
Timeline: 1 and 9 months |
| Gujar et al (2019), RCT | 40 participants (age 12–32 years; mean 28±4 years), 23 females, 17 males | Clear aligners (probably Invisalign, but not clearly specified) | Fixed labial appliances | Cytokine levels PI GI POB |
Timeline: 21 days |
| Gujar et al (2020), PCT | 60 participants, 11–29 years of age | Invisalign | Fixed labial appliances Fixed lingual appliances |
Microbial level changes using checkerboard DNA-DNA hybridisation | Samples were collected only from the maxillary arch Timeline: 30 days |
| Han et al (2015), retrospective cohort | 35 participants with periodontitis, 21 females, 14 males, mean age 52.97 ± 9.42 years, range 35–74 | Clear aligners | Fixed labial appliances | PI reduction GI reduction PD reduction Bone level improvement |
The male:female ratio was statistically significantly different between the 2 groups 1 patient smoked CAT was used for severely mobile or labial inclined teeth Timeline: throughout treatment duration |
| Karkhanetci et al (2013), PCT | 42 participants, FA group: 16 females, 6 males, 34 ± 7.18 years of age, range 18–44. Invisalign group: 12 females, 8 males, 28 ± 6.86 years of age, range 18–44 | Invisalign | Fixed labial appliances | PI GI BoP PPD BANA (secondary outcome) |
Modest sample size 17% attrition rate Timeline: 1.5, 6, 12 months |
| Levrini et al (2013), RCT | 30 adults (10 Invisalign, 10 fixed appliances, 10 no intervention)(9 males, 21 females, aged 25.1 ± 4.6) | Invisalign | Fixed appliances, no intervention | PI PD BOP Compliance with OH Subgingival microbial samples |
Timeline: 1 and 3 months |
| Levrini et al (2015), RCT | 77 participants (5 male Invisalign, 18 male fixed appliances, 2 control, 27 male Invisalign, 17 male fixed appliances, 8 control) age range 16–60 years | Invisalign | Fixed appliances, no intervention | PI PD BOP Biofilm mass Periodontal pathogens (PCR) |
Timeline: 1 and 3 months |
| Madariaga et al (2020), PCT | 40 participants with permanent dentition (26 females, 14 males) mean age 27.6 ± 12.6 years, 20 treated with aligners 20 with fixed appliances | Clear aligners | Fixed appliances | PD PI BOP REC (gingival recession) |
Timeline: 3 months |
| Miethke and Vogt (2005), PCT | 60 participants (43 female, 17 male, 30 Invisalign, 30 fixed appliances) Mean age 30.1 years, range 18–51 |
Invisalign | Fixed appliances | Modified GI Modified PI Modified PBI SPI |
It is possible, though not stated, that at least 1 patient was treated with both brackets and aligners concurrently Timeline: after 1, 2, and 3 months (patients in treatment for at least 6 months) |
| Miethke and Brauner (2007), PCT | 60 participants 30 with Invisalign, 30 with fixed lingual appliances. Age information in the fixed appliances group 16–48 years, mean age: 39.6 years | Invisalign | Fixed lingual appliances | Modified GI Modified PI Modified PBI SPI |
Invisalign group was used in a previous study (Miethke et al, 2005). Some participants were recruited from private practices Timeline: after 1, 2, 3 months (patients in treatment for at least 6 months) |
| Mulla Issa et al (2020), cross sectional | 80 participants, 50% males, 50% females, mean age: 27±5.8 years; range: 23–29 years | Clear aligners (Angle Align, China / Invisalign) | Fixed labial appliances with conventional brackets (a), ceramic brackets (b), self-ligating brackets (c) | PI GI GBI SBI PBI BPE BOP |
Timeline: at least 6 months in treatment, recorded once |
| Mummolo et al (2020a), PCT | 90 participants (30 had Invisalign, mean age 21.5±1.5 years, 30 had fixed appliances, mean age 23.3±1.6 years, 30 had removable positioners, mean age 18.2 ±1.5 years) | Invisalign | Fixed appliances, removable positioners (RP) (Occlus-o-Guide) | Salivary concentrations of S. mutans and lactobacilli (CRT bacteria) PI |
Timeline: 3 and 6 months |
| Mummolo et al (2020b), PCT | 80 participants (40 [16 females, 24 males] Invisalign with mean age 20.4±1.7 years; 40 [18 females, 22 males] fixed appliances with mean age 21.3±1.7,) | Invisalign | Fixed labial appliances | PI Salivary flow (CRT prevention system) Buffering power of saliva (CRT buffer) Salivary levels of S. mutans and lactobacilli (CRT bacteria) |
Timeline: 3 and 6 months |
| Sifakakis et al (2018), PCT | 30 participants, 17 females, 13 males, mean age 13.8 years, range 12–18 years | Clear aligners | Fixed labial appliances | Simplified PI Simplified GI DMFT qPCR (for cariogenic bacteria) |
Self-ligating fixed appliances Timeline: 2 weeks, 1 month |
| Srinath et al (2016), PCT | 46 participants. Fixed appliances group: 18 women and 8 men with a mean age of 34 ± 7.18 years, range of 22–44 years. Aligners group: 8 men and 12 women, mean age: 35 ± 6.86 years, range: 18–38 years |
Clear aligners | Fixed appliances | GI, PD, BOP | Timeline: 6 weeks, 6 months, 12 months |
| Wang et al (2019), PCT | 26 participants, 20–25 years | Invisalign | Fixed labial appliances | 16S rRNA gene identified through pyrosequencing | Only 5 subjects were selected randomly from each group for high-throughput pyrosequencing analysis Timeline: one single saliva sample collection (at least 6 months in treatment) |
API: approximal bleeding index; BPE: basic periodontal examination index; BOP: bleeding on probing; CAT: clear aligner technique; CLA: clear aligners; DMFT: decayed, missing, filled teeth; ELB: elastomeric ligated brackets; FA: fixed appliances; GBI: gingival bleeding index; GI: gingival index; OH: oral hygiene; PBI: papillary bleeding index; PCT: prospective clinical trial; PI: plaque index; PPD: pocket probing depth; REC: gingival recession; RCT: randomised controlled trial; SBI: sulcus bleeding index; SLB: self-ligating brackets.