A Cochrane review included 3 studies with a total of 120 subjects. The trials compared effects of Frankel's function regulator-4 (FR-4) with lip-seal training versus no treatment; repelling-magnet splints versus bite-blocks; and palatal crib associated with high-pull chincup versus no treatment. The study comparing repelling-magnet splints versus bite-blocks could not be analysed because the authors interrupted the treatment earlier than planned due to side effects in four of ten patients. FR-4 associated with lip-seal training (RR = 0.02 [95% CI 0.00 to 0.38]) and removable palatal crib associated with high-pull chincup (RR = 0.23 [95% CI 0.11 to 0.48]) were able to correct anterior open bite.
Comment: The quality of evidence is downgraded by study quality (inadequate allocation concealment and imprecise results) few patients and wide confidence intervals.