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Each row is one question a systematic review asked: who, what, compared with what, and which outcome, with the effect it found and how certain that is. Words match anywhere in the field.
830 questions in 43 reviews · Orthodontics
current versionsNo studies 186 · 22.4%Ungraded 410 · 49.4%Very low 122 · 14.7%Low 79 · 9.5%Moderate 30 · 3.6%High 3 · 0.4%
Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.
| Question | Effect | Evidence | Status / GRADE |
|---|---|---|---|
Fixed tooth-borne expansion (Hyrax) vs Fixed tooth-tissue-borne expansion (Haas) Molar expansion (inter-molar distance) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD -0.15 [-0.86, 0.56] | 2 studies · 46 participants | Moderate |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances White spot lesions (WSLs), tooth level · Adults undergoing orthodontic treatment · 3 months, Adults Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | RR 0.72 [0.60, 0.86] | 1 study | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Time taken for the canine to erupt into the mouth · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | no estimate extracted | 0 studies | No studies |
Fixed tooth-borne expansion (Hyrax) vs Observation (no treatment) Crossbite correction · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children and adolescents Orthodontic treatment for posterior crossbites (2021) · Cochrane | OR 48.02 [21.58, 106.87] | 3 studies · 93 participants | Moderate |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Incidence of successfully erupted PDC that were favourably positioned · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 12 months Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 1.09 [0.08, 15.42] | 1 study · 23 participants | Ungraded |
Banded Hyrax (tooth-borne) vs Bonded Hyrax (tooth/tissue-borne) Molar expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 3 months after completion of expansion Orthodontic treatment for posterior crossbites (2021) · Cochrane | Asanza 1997: banded 6 mm (min 4.3-max 7.2) vs bonded 5.9 mm (min 3.2-max 7.7); P=NS (no SD reported); no significant difference in tipping or symmetrical expansion | 1 study | Ungraded |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Number of participants referred for surgical exposure of the PDC · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 48 months (maximum; mITT) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 0.31 [0.06, 1.45] | 2 studies · 96 participants | Very low |
Nickel-titanium archwire vs Multistranded stainless steel archwire Amount of crowding (change in mandibular crowding) at 8 weeks · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 8 weeks Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 1.60 [-22.16, 25.36] | 1 study · 25 participants | Very low |
Fixed bonded acrylic splint expander vs No treatment Canine expansion (maxillary intercanine width) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 2.288 | 1 study | Ungraded |
Fixed tooth-borne expansion (quad-helix) vs Removable tooth-borne expansion (expansion plate) Molar expansion (inter-molar distance) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 1.48 [0.91, 2.04] | 3 studies · 151 participants | High |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Incidence of eruption of the PDC into the mouth · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 24 months Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 0.61 [0.29, 1.25] | 1 study · 23 participants | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Incidence of eruption of the PDC into the mouth · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 12 months Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 2.87 [0.90, 9.23] | 1 study · 45 participants | Very low |
Self-ligating brackets vs Conventional brackets Time to alignment (days) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · alignment Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 89.64 [-45.89, 225.17] | 2 studies · 148 participants | Ungraded |
Cervical pull headgear vs Minor interceptive procedures (control) Upper incisors to maxilla at 2 years · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 2 years Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 4.5 [1.36, 7.64] | 1 study · 64 participants | Ungraded |
Resin infiltration vs Fluoride varnish Optical/esthetic improvement (DIAGNOdent reading) · Patients (mainly children) with white spot lesions (WSL) · 3 to 6 months Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | MD 4.76 [0.74, 8.78] | 3 studies · 212 participants | Moderate |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Bleeding on probing (BOP) · Adults undergoing orthodontic treatment · 6 to 12 weeks, Adults Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -0.26 [-0.77, 0.26] | 2 studies · 62 participants | Very low |
Extraction of third molars (wisdom teeth) vs No active treatment (control) Amount of crowding (Little's Irregularity Index, change) at 5 years · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 5 years Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD -0.30 [-1.30, 0.70] | 1 study · 77 participants | Very low |
Lower lingual arch vs No active treatment (control) Size of the lower jaw (mandibular arch length) at 1 year · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 1 year Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 2.61 [1.83, 3.39] | 1 study · 30 participants | Ungraded |
Two-band palatal expander with slow expansion vs Two-band palatal expander with rapid expansion Crossbite correction · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… Orthodontic treatment for posterior crossbites (2021) · Cochrane | Martina 2012: slow 12/12 vs rapid 14/14; NS (all corrected in both groups) | 1 study · 26 participants | Ungraded |
Fixed tooth-borne expansion (Hyrax) vs Fixed tooth-tissue-borne expansion (Haas) Canine expansion (inter-canine distance) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… Orthodontic treatment for posterior crossbites (2021) · Cochrane | Not measured (SoF 5) | 0 studies | No studies |
Extraction of lower deciduous canines vs No active treatment (control) Lower incisors to mandible (inclination, degrees) at 1 year · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 1 year Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 0.08 [-0.55, 0.71] | 1 study · 83 participants | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Plaque index (PI) · Adolescents/teenagers undergoing orthodontic treatment · 18 months, Adolescents Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -0.40 [-0.77, -0.03] | 1 study | Ungraded |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Costs / cost-effectiveness · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | The studies did not report cost-effectiveness. | 0 studies | No studies |
Sealant vs No sealant Incidence of new white spot lesions by visual-tactile assessment · Patients receiving comprehensive fixed orthodontic treatment · 3 to 27 months, Overall Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.70 [0.53, 0.93] | 6 studies · 2314 participants | Very low |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Patient-reported outcomes (pain, discomfort and analgesic use) · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · Evening after extraction and one week later Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | Self-reported VAS pain (Naoumova 2012): pain and discomfort from extraction of the primary canine were low both during and after the procedure and mostly absent at one week; 35% of boys and 50% of girls took one dose… | 1 study · 44 participants | Ungraded |
Fixed expander with differential opening expansion (DOE) vs Fixed fan-type expander Crossbite correction · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… Orthodontic treatment for posterior crossbites (2021) · Cochrane | Massaro 2020: differential opening 24/24 vs fan-type 18/24 crossbites corrected | 1 study | Ungraded |
Semi-rapid maxillary expansion vs Rapid maxillary expansion Molar expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 0.60 [-0.55, 1.75] | 1 study · 35 participants | Ungraded |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Reported improvement in the position of the ectopic canine measured from radiographs · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | no estimate extracted | 0 studies | No studies |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Patient-reported outcome measures (PROMs), including quality of life and pain · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | no estimate extracted | 0 studies | No studies |
Schwarz appliance vs No active treatment (control) Upper incisors to maxilla (inclination, degrees) at 9 months · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 9 months Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 0.33 [-2.26, 2.92] | 1 study · 28 participants | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Simplified gingival index (s-GI) · Adolescents/teenagers undergoing orthodontic treatment · 1 month, Adolescents Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -8.46 [-10.47, -6.45] | 1 study | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Lactobacilli presence (CFU > 10^5) · Adults undergoing orthodontic treatment · 6 months, Adults Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | RR 0.19 [0.08, 0.45] | 2 studies · 140 participants | Low |
Fixed tooth-borne expansion (Hyrax) vs Observation (no treatment) Molar expansion (inter-molar distance) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 5.80 [5.15, 6.45] | 2 studies · 71 participants | Moderate |
Eruption guidance appliance vs No active treatment (control) Amount of crowding (number of children with crowding, mandible) after 1 year · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 1 year Orthodontic treatment for crowded teeth in children (2021) · Cochrane | OR 0.19 [0.05, 0.68] | 1 study · 46 participants | Very low |
Bone-borne expansion appliance vs No treatment (observation) Crossbite correction · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Adolescents Orthodontic treatment for posterior crossbites (2021) · Cochrane | Alberta 2010: bone-borne expansion corrected all posterior crossbites (21/21); no self-correction in the untreated group | 1 study | Ungraded |
Fluoride-releasing compomer-based bonding agent vs Non-fluoride compomer-based bonding agent Initiation of white spot lesions (WSL), visual-tactile assessment · Patients of any age (11-40 years) receiving comprehensive/fixed orthodontic treatment with fixed appliances · 1-24 months follow-up, Compomer-based bonding agents Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.71 [0.46, 1.11] | 2 studies · 400 participants | Ungraded |
Self-ligating brackets vs Conventional brackets Lower incisors to mandible (inclination, degrees) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · post-treatment Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 1.29 [-1.77, 4.35] | 1 study · 33 participants | Ungraded |
Resin infiltration vs Microabrasion Masking effect / color improvement · Patients with white spot lesions or developmental enamel defects Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | no estimate extracted | 2 studies | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Any other adverse effects, such as gingival disease and demineralisation · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | Only root resorption was assessed; other adverse effects (gingival disease, demineralisation) were not reported. | 0 studies | No studies |
Coaxial nickel-titanium archwire vs Nickel-titanium archwire Amount of tooth movement / reduction in crowding at 12 weeks · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 12 weeks Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 6.77 [5.55, 7.99] | 1 study · 24 participants | Very low |
Sealant/coating agent WITHOUT fluoride release applied to teeth with fixed appliances vs No sealant (untreated control teeth) Initiation of white spot lesions (WSL), visual-tactile assessment · Patients of any age (11-40 years) receiving comprehensive/fixed orthodontic treatment with fixed appliances · 3-27 months follow-up, Sealant without fluoride release Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.69 [0.49, 0.97] | 3 studies · 847 participants | Ungraded |
Fixed bonded Hyrax appliance followed by U-bow activator therapy vs No treatment Canine expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 12 months after start of treatment Orthodontic treatment for posterior crossbites (2021) · Cochrane | U-bow activator 3.6 mm vs untreated 1 mm; P<0.001 (no SD reported); significant in favour of treatment | 1 study · 66 participants | Ungraded |
Fixed tooth-borne expansion (quad-helix) vs Removable tooth-borne expansion (expansion plate) Canine expansion (inter-canine distance) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 0.59 [0.09, 1.08] | 3 studies · 151 participants | Low |
Quad-helix plus multi-bracket appliance vs Expansion arch plus multi-bracket appliance Molar expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 12 weeks after start of treatment Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD -0.55 [-1.34, 0.24] | 1 study · 55 participants | Ungraded |
Fixed tooth-borne expansion (quad-helix) vs Removable tooth-borne expansion (expansion plate) Length of treatment · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · Children (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD -3.15 [-4.04, -2.25] | 3 studies · 148 participants | Moderate |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Pocket/probing depth (PD) · Adults undergoing orthodontic treatment · 6 to 12 weeks, Adults Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -0.42 [-0.71, -0.12] | 2 studies · 62 participants | Very low |
Fixed tooth-borne expansion (quad-helix) vs Removable tooth-borne expansion (expansion plate) Stability of crossbite correction (relapse) · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 12 months after correction Orthodontic treatment for posterior crossbites (2021) · Cochrane | Relapse occurred in 9.1% of both quad-helix and expansion plate groups after one year of follow-up (Godoy 2011) | 1 study · 66 participants | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances White spot lesions (WSLs), patient level · Adolescents/teenagers undergoing orthodontic treatment · 9 months, Adolescents Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | RR 0.33 [0.10, 1.04] | 1 study | Ungraded |
Resin infiltration alone vs In-office bleaching alone Dentist satisfaction (masking effect) · Patients with dental fluorosis Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | MD 3.97 [3.33, 4.61] | 1 study | Ungraded |
Vibrational appliance with fixed appliances vs Fixed appliances only / no vibrational appliance (control) Time to alignment (days) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · alignment Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD -3.70 [-26.29, 18.89] | 2 studies | Ungraded |