What do systematic reviews say?

3 questions · 8 findings · 3 reviews · Oral Health

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No studies found 0 · 0%GRADE not reported 6 · 75%Very low 0 · 0%Low 0 · 0%Moderate 2 · 25%High 0 · 0%

Clear aligners (Invisalign / thermoformed aligners) vs Conventional orthodontic appliance treatment

Plaque · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries)

In randomized trials, clear aligners probably reduce plaque accumulation versus fixed appliances, though the subgroup estimate is imprecise and its CI crosses no effect (SMD -1.79, 95% CI -3.63 to 0.04; moderate certainty).

6 findings from 1 review

White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
Range 1 to 18 months (maximum time-point per study) · University/hospital orthodontic clinics and private practice (multiple countries) · Study design: randomized controlled trials
SMD -1.79 [-3.63, 0.04]
3 studies · 111 participants
Moderate
White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
6 months · University/hospital orthodontic clinics and private practice (multiple countries) · Follow-up: 6 months
SMD -2.04 [-3.37, -0.70]
5 studies · 253 participants
GRADE not reported
White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
Range 1 to 12 months (maximum time-point per study) · University/hospital orthodontic clinics and private practice (multiple countries) · Study design: non-randomized studies of interventions
SMD -1.46 [-2.77, -0.15]
5 studies · 246 participants
Moderate

Show 3 more findings

White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
3 months · University/hospital orthodontic clinics and private practice (multiple countries) · Follow-up: 3 months
SMD -1.08 [-1.93, -0.24]
5 studies · 211 participants
GRADE not reported
White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
Maximum reported time-point per study (range 1-18 months) · University/hospital orthodontic clinics and private practice (multiple countries)
SMD -1.58 [-2.57, -0.58]
8 studies · 357 participants
GRADE not reported
White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed… 2023 All outcomes
12 months · University/hospital orthodontic clinics and private practice (multiple countries) · Follow-up: 12 months
SMD -2.14 [-3.64, -0.64]
3 studies · 113 participants
GRADE not reported

Electronic cigarette use vs Non-smokers (non-users)

Plaque index (PI) / oral hygiene · Adult e-cigarette (ENDS) users (general oral health; predominantly natural dentition)

E-cigarette users tend to have a higher plaque index (more biofilm accumulation) than non-smokers (narrative synthesis of systematic reviews; ungraded).

1 finding from 1 review

An Umbrella Review of E-Cigarettes' Impact on Oral Microbiota and Biofilm Buildup. 2025 All outcomes
Oral health / dental care (community and clinical samples)
Narrative synthesis: e-cigarette users exhibited a higher plaque index than non-smokers across included reviews (Shabil, Vamos, Youssef, Thiem, Figueredo, Yang [24,25,27,29,30,31]); the umbrella review reported no…
6 studies
GRADE not reported

Anorexia nervosa (as exposure; diagnosed by DSM-III/III-R/IV/V) vs Healthy controls

Plaque · Patients with anorexia nervosa aged >=12 years (mean age ~18.4; entirely female in reported data), general community-dwelling population

Anorexia nervosa patients tended to have higher plaque accumulation than healthy controls (significant in 2 of 3 studies), but results were not pooled or graded (ungraded).

1 finding from 1 review

The influence of anorexia nervosa on oral health and related parameters potentially relevant to orthodontic treatment:… 2025 All outcomes
Clinical dental/oral examination; case-control studies and controlled clinical trials in Europe (mainly Poland, Italy, France, Germany), Australia and the USA
In 2 of 3 studies anorexic patients had significantly higher plaque accumulation than controls (Pallier 78.8% vs 53.0%, p<0.01; Paszynska 43.8% vs 13.7%, p<0.001; Milosevic 84% vs 72%, NS); not meta-analyzed
3 studies · 394 participants
GRADE not reported