Abstract: We included six trials, which recruited 252 children (aged two and a half to 18 years), but presented follow-up data on only 246 children. Digit sucking was the only NNSH assessed in the studies. Five studies compared single or multiple interventions with a no-intervention or waiting list control group and one study made a head-to-head comparison. All the studies were at high risk of bias due to major limitations in methodology and reporting. There were small numbers of participants in the studies (20 to 38 participants per study) and follow-up times ranged from one to 36 months. Short-term outcomes were observed under one year post intervention and long-term outcomes were observed at one year or more post intervention. Orthodontics appliance (with or without psychological intervention) versus no treatment Two trials that assessed this comparison evaluated our primary outcome of cessation of habit. One of the trials evaluated palatal crib and one used a mix of palatal cribs and arches. Both trials were at high risk of bias. The orthodontic appliance was more likely to stop digit sucking than no treatment, whether it was used over the short term (risk ratio (RR) 6.53, 95% confidence interval (CI) 1.67 to 25.53; two trials, 70 participants) or long term (RR 5.81, 95% CI 1.49 to 22.66; one trial, 37 participants) or used in combination with a psychological intervention (RR 6.36, 95% CI 0.97 to 41.96; one trial, 32 participants). Psychological intervention versus no treatment Two trials (78 participants) at high risk of bias evaluated positive reinforcement (alone or in combination with gaining the child's co-operation) or negative reinforcement compared with no treatment. Pooling of data showed a statistically significant difference in favour of the psychological interventions in the short term (RR 6.16, 95% CI 1.18 to 32.10; I2 = 0%). One study, with data from 57 participants, reported on the long-term effect of positive and negative reinforcement on sucking cessation and found a statistically significant difference in favour of the psychological interventions (RR 6.25, 95% CI 1.65 to 23.65). Head-to-head comparisons Only one trial demonstrated a clear difference in effectiveness between different active interventions. This trial, which had only 22 participants, found a higher likelihood of cessation of habit with palatal crib than palatal arch (RR 0.13, 95% CI 0.03 to 0.59). This review found low quality evidence that orthodontic appliances (palatal arch and palatal crib) and psychological interventions (including positive and negative reinforcement) are effective at improving sucking cessation in children. There is very low quality evidence that palatal crib is more effective than palatal arch. This review has highlighted the need for high quality trials evaluating interventions to stop non-nutritive sucking habits to be conducted and the need for a consolidated, standardised approach to reporting outcomes in these trials.

Plain-language summary: Review authors from the Cochrane Oral Health Group carried out this review of existing studies and the evidence is current up to 8 October 2014. The review includes six studies published from 1967 to 1997, which involved 252 children as participants (although data were supplied on only 246 of the children). Three of the studies were carried out in the USA, one in Canada, one in Sweden and one in Australia. Not all of the studies gave the ages of children involved; in four of the studies children were aged from two and a half to 18 years old, in one study they were aged four years and over and in another nine years and over. Use of an orthodontic brace (such as a palatal crib or arch) or a psychological intervention (such as use of positive or negative reinforcement), or both, was more likely to lead to cessation of the habit than no treatment. Most of the trials that compared two different interventions were inconclusive but one study suggested that, of two different types of braces,a palatal crib is more effective than a palatal arch design. The evidence presented is of low quality due to the small number of participants in the few available studies and problems with the way in which the studies were conducted. There was a high risk of bias across the studies. Orthodontic braces or psychological intervention seems to be effective to help children stop sucking that does not have a feeding purpose but the evidence is low quality. Further high quality clinical trials are required to guide decision making for what is a common problem that can require lengthy and expensive dental treatment to correct.