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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 |
|---|---|---|---|
Lower lingual arch vs No active treatment (control) Amount of crowding · 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 | SoF1: Amount of crowding - Not measured. The single study (Rebellato 1997) did not report the amount of crowding for this comparison. | 1 study | Ungraded |
Sealant/coating agent WITH 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 with fluoride release Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.69 [0.46, 1.05] | 3 studies · 1467 participants | Ungraded |
Resin infiltration vs Untreated control (natural remineralization) Optical/esthetic improvement (visual-tactile assessment) · Patients with post-orthodontic white spot lesions (WSL) · 4 weeks to 6 months Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | SMD 1.24 [0.59, 1.88] | 3 studies · 949 participants | Moderate |
Vibrational appliance with fixed appliances vs Fixed appliances only / no vibrational appliance (control) Harms (discomfort, pain intensity, analgesia use) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · first week Orthodontic treatment for crowded teeth in children (2021) · Cochrane | No clear difference in discomfort/pain intensity or analgesia consumption between vibrational appliance and control (Miles 2012, Miles 2016, Woodhouse 2015; 100 mm VAS). Narrative; no pooled estimate. | 2 studies | Ungraded |
Any orthodontic (non-surgical) treatment to correct posterior crossbite or expand the top teeth vs No treatment or another orthodontic treatment Signs and symptoms of respiratory issues · 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 | no estimate extracted | 0 studies | No studies |
Fluoride-releasing coating material vs Coating material without fluoride release Incidence of new white spot lesions by visual-tactile assessment · Patients receiving comprehensive fixed orthodontic treatment · 1 to 24 months, Overall Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.84 [0.70, 1.01] | 10 studies · 4705 participants | Very low |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction Effect of severity of PDC displacement towards the midline on the proportion of successful eruptions · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 12 to 48 months, By baseline sector (severity of displacement) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | Tables 11-15 (Hadler-Olsen 2020; Bonetti 2010; Bonetti 2011): partial relationship between severity of medial displacement and successful eruption; e.g. at 18 months 17/75 (23%) sector 2 erupted vs 1/17 (6%) sector 3,… | 3 studies | Ungraded |
Removable tooth-borne expansion (expansion plate) 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 (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | OR 25.26 [13.08, 48.77] | 3 studies · 148 participants | High |
Fixed tooth-borne expansion (Hyrax) vs Fixed tooth-tissue-borne expansion (Haas) Crossbite correction · 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 | RR 1.05 [0.94, 1.18] | 3 studies · 83 participants | Moderate |
Two-band palatal expander with slow expansion vs Two-band palatal expander with rapid expansion Molar expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 7 months after start of treatment Orthodontic treatment for posterior crossbites (2021) · Cochrane | Martina 2012: slow 6.3 mm (SD 2.1) vs rapid 5.7 mm (SD 1.6); reported as no statistically significant difference in text (PUB2 MD 0.60, 95% CI -0.85 to 2.05); Table 1 lists P<0.001 (discrepant) | 1 study · 26 participants | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) 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 | Improvement in the position of the ectopic canine was not extracted as a distinct outcome (alpha-angle was the trial's own outcome). | 0 studies | No studies |
Any orthodontic (non-surgical) treatment to correct posterior crossbite or expand the top teeth vs No treatment or another orthodontic treatment Quality of life · 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 | no estimate extracted | 0 studies | No studies |
Lower lip bumper vs No active treatment (control) Amount of crowding (change in mandibular incisor crowding) at 6 months · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 6 months Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD -4.39 [-5.07, -3.71] | 1 study · 34 participants | Very low |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Lactobacilli presence (CFU > 10^5) · 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 0.09 [0.02, 0.47] | 2 studies · 140 participants | Low |
Cervical pull headgear vs Minor interceptive procedures (control) Amount of crowding (lower incisor crowding) 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 0.33 [-0.60, 1.26] | 1 study · 64 participants | Very low |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Average fluorescence loss (dF%) · Adults undergoing orthodontic treatment · 3 months, Adults Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -1.40 [-2.15, -0.65] | 1 study | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Root resorption of adjacent permanent teeth caused by the PDC · 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 0.60 [0.28, 1.31] | 1 study · 89 participants | Ungraded |
Fixed tooth-borne expansion (quad-helix) 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 (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | OR 50.59 [26.77, 95.60] | 3 studies · 149 participants | High |
Fixed tooth-borne expansion (quad-helix) vs Observation (no treatment) 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 3.15 [2.77, 3.53] | 3 studies · 146 participants | Low |
Resin infiltration vs Untreated control (natural remineralization) Optical/esthetic improvement (visual-tactile assessment) · Patients with post-orthodontic white spot lesions (WSL) · 4 weeks to 6 months, Visual analog scale (Senestraro et al. 2013) Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | SMD 2.34 [1.68, 3.01] | 1 study · 66 participants | Ungraded |
Fixed expander with differential opening expansion (DOE) vs Fixed fan-type expander Canine 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 | Massaro 2020: DOE 7.76 (SD 1.23) mm vs fan-type 8.80 (SD 1.33) mm; P=0.008 (favours fan-type) | 1 study | Ungraded |
Extraction of the primary (baby) canine (single primary tooth extraction) vs No extraction (non-intervention control) Effect of severity of PDC displacement towards the midline on the proportion of successful eruptions · Young people aged 9 to 14 years diagnosed with one or both palatally displaced permanent maxillary canines (PDC) · 12 months, By baseline sector (severity of displacement) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | Table 4 (Naoumova 2015): probability of successful eruption depended on displacement severity; sector 2 (mild) 14/19 (74%) erupted vs sector 4 0/10 erupted; data refer to 59 teeth (mITT). | 1 study · 59 participants | Ungraded |
Vibrational appliance with fixed appliances vs Fixed appliances only / no vibrational appliance (control) Amount of crowding (change in mandibular crowding) at 10 to 30 weeks · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 10 to 30 weeks Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 0.24 [-0.81, 1.30] | 2 studies · 119 participants | Very low |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Full-mouth plaque score (FMPS) · Adolescents/teenagers undergoing orthodontic treatment · 12 months, Adolescents Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and… (2021) | MD -43.48 [-47.65, -39.31] | 1 study | Ungraded |
Bone-borne expansion vs Fixed tooth-borne expansion (Hyrax) 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 | RR 1.00 [0.94, 1.07] | 2 studies · 81 participants | Low |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Gingival index (GI) · 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 -0.57 [-0.93, -0.21] | 1 study | Ungraded |
Glass ionomer cement vs Resin adhesive Incidence of new white spot lesions by visual-tactile assessment · Patients receiving comprehensive fixed orthodontic treatment · 12 to 24 months, Overall Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.72 [0.34, 1.54] | 3 studies · 394 participants | Very low |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances S. mutans presence (CFU > 10^5) · 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 0.07 [0.01, 0.49] | 2 studies · 140 participants | Low |
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) · 24 months Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 1.64 [0.33, 8.03] | 1 study · 23 participants | Ungraded |
Lower lip bumper vs No active treatment (control) Lower incisors to mandible at 6 months · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 6 months Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 3.14 [1.73, 4.55] | 1 study · 34 participants | Ungraded |
Bonded Minne appliance (slow maxillary expansion) vs Banded Minne appliance (slow maxillary expansion) Canine expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 7 to 15 weeks after start of treatment Orthodontic treatment for posterior crossbites (2021) · Cochrane | Bonded Minne 6.4 mm (SD 1.1) vs Banded Minne 5.3 mm (SD 1.9); P=NS | 1 study | Ungraded |
Nickel-titanium archwire vs 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 -16.80 [-42.79, 9.19] | 1 study · 24 participants | Very low |
Cervical pull headgear vs Minor interceptive procedures (control) Size of the jaws (maxillary and mandibular arch length) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 2 to 8 years Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 1.98 [1.80, 2.16] | 1 study · 64 participants | Ungraded |
Lower lip bumper vs No active treatment (control) Size of the lower jaw (mandibular arch length) at 6 months · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 6 months Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD 3.34 [2.71, 3.97] | 1 study · 34 participants | Ungraded |
Bleaching before resin infiltration (bleaching + infiltration) vs Resin infiltration alone Patient/dentist satisfaction · Patients with dental fluorosis Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or… (2021) | SMD -1.53 [-4.75, 1.70] | 2 studies | Ungraded |
Double primary (canine and first molar) tooth extraction vs Single primary (canine) tooth extraction 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 | The studies did not report adverse events. | 0 studies | No studies |
Fixed tooth-borne Hyrax expander vs Bonded expander plate (acrylic) Molar expansion · Children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or… · 1 week after completion of expansion Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 0.36 [-0.72, 1.44] | 1 study | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances Gingival index (GI) · 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 -0.10 [-0.35, 0.15] | 1 study | Ungraded |
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) · 18 months (mean; mITT) Interventions for promoting the eruption of palatally displaced permanent canine teeth, without the need for… (2021) · Cochrane | RR 0.68 [0.35, 1.31] | 3 studies · 119 participants | Very low |
Fixed bonded acrylic splint expander vs No treatment Molar expansion (maxillary intermolar 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 6.265 | 1 study | Ungraded |
Glass ionomer cement (for bracket bonding) vs Resin adhesive (for bracket bonding) Initiation of white spot lesions (WSL), visual-tactile assessment · Patients of any age (11-40 years) receiving comprehensive/fixed orthodontic treatment with fixed appliances · 12-24 months follow-up Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel… (2021) | RR 0.72 [0.34, 1.54] | 3 studies · 394 participants | Very low |
Nickel-titanium archwire vs Multistranded stainless steel archwire Harms (pain) · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · first days Orthodontic treatment for crowded teeth in children (2021) · Cochrane | No difference in overall pain, but more pain with nickel-titanium at 12 hours and day 1 (morning, afternoon, bedtime) vs multistranded stainless steel (Sandhu 2013). Narrative; no pooled estimate. | 1 study | Ungraded |
Four-point expansion appliance (Hyrax) vs Two-point expansion appliance Canine 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 | Lamparski 2003: 4-point 3.034 mm vs 2-point 1.7 mm; P=0.331 (NS, no SD) | 1 study | Ungraded |
Fixed tooth-borne expansion (Hyrax) vs Observation (no treatment) 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 3) | 0 studies | No studies |
Fixed expander with differential opening expansion (DOE) vs Fixed fan-type expander 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 | Massaro 2020: DOE 5.10 (SD 1.17) mm vs fan-type 2.23 (SD 0.75) mm; P<0.001 (favours differential opening) | 1 study | Ungraded |
Copper nickel-titanium archwire vs Nickel-titanium archwire Amount of crowding (Little's Irregularity Index) 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 0.49 [0.35, 0.63] | 1 study · 66 participants | Very low |
Quad-helix plus multi-bracket appliance vs Expansion arch plus multi-bracket appliance Canine 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 -0.72 [-1.52, 0.08] | 1 study · 52 participants | Ungraded |
Four-point expansion appliance (Hyrax) vs Two-point expansion appliance 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 | Lamparski 2003: not reported by group; 'no significant differences were found' | 1 study | Ungraded |
Fixed tooth-borne expansion (quad-helix) 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 (7 to 11 years) Orthodontic treatment for posterior crossbites (2021) · Cochrane | MD 4.71 [4.31, 5.10] | 3 studies · 146 participants | Moderate |
Schwarz appliance vs No active treatment (control) Amount of crowding (lower arch crowding, change) at 9 months · Children or adolescents (aged 16 years old or under) receiving orthodontic treatment to prevent or correct crowded teeth · 9 months (after 6 months treatment) Orthodontic treatment for crowded teeth in children (2021) · Cochrane | MD -2.14 [-2.79, -1.49] | 1 study · 28 participants | Very low |