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Table 5 Summary of findings according to GRADE

From: The effectiveness of the early orthodontic correction of functional unilateral posterior crossbite in the mixed dentition period: a systematic review and meta-analysis

Quad-helix compared with expansion plate for treatment of functional posterior cross bite
Patient or population: patients in mixed dentition had functional posterior crossbite
Intervention: quad-helix
Comparison: expansion plate
Outcomes Anticipated absolute effects* (95% CI) Relative effect (95% CI) № of participants (studies) Certainty of the evidence (GRADE) Comments
Risk with expansion plate Risk with quad-helix
Maxillary intermolar width—RCTs   MD 1.25 higher (0.75 higher to 1.75 higher) 241 (4 RCTs) MODERATEa 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 LOWb,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 LOWa,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 LOWb,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 LOWa,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 LOWb,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 LOWa,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 LOWb,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) MODERATEh 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 LOWb,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 LOWa,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 LOWb,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) MODERATEh 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 LOWb,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) MODERATEk 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
  1. Explanations
  2. aUnclear risk of bias for random sequence generation and allocation concealment in one included trial
  3. bThere was a risk of bias in the assessment of the study endpoint and prospective calculation of the study size
  4. cThere was a significant heterogeneity between the included studies
  5. dThe boundaries of the CI are not on the same side of their decision-making threshold
  6. eThe CI crosses the clinical decision-making threshold for an acceptable estimate of treatment
  7. fThe recommendation will be altered if the lower versus the upper boundary of the CI represent the true underlying effect
  8. gThe number of patients who provide data is very low
  9. hThere a was a heterogeneity between the included studies
  10. iThe event rates are very low
  11. jThe event rates are low and CI around relative effects is wide
  12. kThe event rates are low
  13. lThe CI around relative effects may be wide
  14. mThe CI around relative effects is wide