Table 5 Summary of findings according to GRADE

Patient or population: patients in mixed dentition had functional posterior crossbite

Intervention: quad-helix

Comparison: expansion plate

Maxillary intermolar width—RCTs

MD 1.25 higher (0.75 higher to 1.75 higher)

–

241 (4 RCTs)

⨁⨁⨁◯ MODERATE^a

The treatment by quad-helix increased the maxillary intermolar width by 1.25 mm with a statistically significant difference compared with expansion plate

Maxillary intermolar width—CCTs

MD 0.23 higher (0.99 lower to 1.45 higher)

–

72 (2 CCTs)

⨁◯◯◯ VERY LOW^b,c,d

Quad-helix may increase/have little to no effect on maxillary intermolar width but the evidence is very uncertain

Maxillary intercanine width—RCTs

MD 0.42 higher (0.55 lower to 1.39 higher)

–

241 (4 RCTs)

⨁◯◯◯ VERY LOW^a,c,e

The evidence suggests that quad-helix may increase the maxillary intercanine width slightly compared with expansion plate and the difference between both groups is non-significant

Maxillary intercanine width—CCTs

MD 0.45 higher (1.87 lower to 2.77 higher)

–

72 (2 CCTs)

⨁◯◯◯ VERY LOW^b,c,e

The evidence suggests that quad-helix may increase/decrease the maxillary intercanine width slightly compared with expansion plate and the difference between both groups is non-significant

Mandibular intermolar width—RCTs

MD 0.3 lower (1.06 lower to 0.47 higher)

–

131 (3 RCTs)

⨁◯◯◯ VERY LOW^a,c,f

Quad-helix may reduce/have little to no effect on mandibular intermolar width compared with expansion plate but the evidence is very uncertain

mandibular intermolar width—CCTs

MD 0.01 lower (0.28 lower to 0.25 higher)

–

72 (2 CCTs)

⨁◯◯◯ VERY LOW^b,d,g

Quad-helix may reduce/have little to no effect on mandibular intermolar width compared with expansion plate but the evidence is very uncertain

Mandibular intercanine width—RCTs

MD 0.39 lower (0.86 lower to 0.09 higher)

–

131 (3 RCTs)

⨁◯◯◯ VERY LOW^a,d,h

Quad-helix may have little to no effect on mandibular intercanine width compared with expansion plate but the evidence is very uncertain

Mandibular intercanine width—CCTs

MD 0.19 higher (0.13 lower to 0.5 higher)

–

72 (2 CCTs)

⨁◯◯◯ VERY LOW^b,d,g

Quad-helix may have little to no effect on mandibular intercanine width but the evidence is very uncertain

Success rate—RCTs

757 per 1,000

977 per 1000 (757 to 1000)

RR 1.29 (1.00 to 1.66)

206 (3 RCTs)

⨁⨁⨁◯ MODERATE^h

The evidence suggests that quad-helix likely results in an increase in success rate compared with expansion plate and the difference between both groups is significant

Success rate—CCTs

1000 per 1000

1000 per 1000 (910 to 1000)

RR 1.00 (0.91 to 1.10)

38 (1 CCT)

⨁◯◯◯ VERY LOW^b,i

The evidence is very uncertain about the effect of quad-helix compared with expansion plate on success rate

Relapse at 1 year post-treatment

91 per 1000

91 per 1000 (20 to 418)

RR 1.00 (0.22 to 4.60)

66 (1 RCT)

⨁⨁◯◯ LOWⁱ

The evidence suggests that quad-helix results in no difference in relapse at 1 year post-treatment compared with expansion plate

Relapse at 3 years post-treatment

0 per 1000

0 per 1000 (0 to 0)

RR 2.29 (0.10 to 52.48)

35 (1 RCT)

⨁◯◯◯ VERY LOW^a,j

The evidence is very uncertain about the effect of quad-helix and expansion plate on relapse at 3 years post-treatment

Relapse at 5.6 years

53 per 1000

158 per 1000 (18 to 1,000)

RR 3.00 (0.34 to 26.33)

38 (1 CCT)

⨁◯◯◯ VERY LOW^b,j

Quad-helix may have little effect on relapse at 5.6 years compared with expansion plate but the evidence is very uncertain

Treatment duration—RCTs

MD 3.36 lower (4.97 lower to 1.75 lower)

–

206 (3 RCTs)

⨁⨁⨁◯ MODERATE^h

The evidence suggests that quad-helix probably results in a reduction in treatment duration compared with expansion plate

Treatment duration—CCTs

MD 4.8 lower (7.07 lower to 2.53 lower)

–

38 (1 CCT)

⨁◯◯◯ VERY LOW^b,g

Quad-helix may reduce the treatment duration compared with expansion plate but the evidence is very uncertain

Mandibular midline correction

644 per 1000

760 per 1000 (618 to 940)

RR 1.18 (0.96 to 1.46)

122 (2 RCTs)

⨁⨁⨁◯ MODERATE^k

The evidence suggests that quad-helix may increase the midline correction rate compared with expansion plate but the difference between both groups is statistically non-significant

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI)

CI: Confidence interval; MD: Mean difference; RR: Risk ratio

GRADE Working Group grades of evidence

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect

Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different

Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect

Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect