Orthodontic treatment for posterior crossbites.

BACKGROUND: A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. The prevalence of posterior crossbite is around 4% and 17% of children and adolescents in Europe and America, respectively. Several treatments have been recommended to correct this problem, which is related to such dental issues as tooth attrition, abnormal development of the jaws, joint problems, and imbalanced facial appearance. Treatments involve expanding the upper jaw with an orthodontic appliance, which can be fixed (e.g. quad-helix) or removable (e.g. expansion plate). This is the third update of a Cochrane review first published in 2001. OBJECTIVES: To assess the effects of different orthodontic treatments for posterior crossbites. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 8 April 2021 and used additional search methods to identify published, unpublished and ongoing studies. SELECTION CRITERIA: Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults. DATA COLLECTION AND ANALYSIS: Two review authors, independently and in duplicate, screened the results of the electronic searches, extracted data, and assessed the risk of bias of the included studies. A third review author participated to resolve disagreements. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous data (event), unless there were zero values in trial arms, in which case we used odds ratios (ORs). We used mean differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models. We used the GRADE approach to assess the certainty of the evidence for the main outcomes. MAIN RESULTS: We included 31 studies that randomised approximately 1410 participants. Eight studies were at low risk of bias, 15 were at high risk of bias, and eight were unclear. Intervention versus observation For children (age 7 to 11 years), quad-helix was beneficial for posterior crossbite correction compared to observation (OR 50.59, 95% CI 26.77 to 95.60; 3 studies, 149 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 4.71 mm, 95% CI 4.31 to 5.10; 3 studies, 146 participants; moderate-certainty evidence). For children, expansion plates were also beneficial for posterior crossbite correction compared to observation (OR 25.26, 95% CI 13.08 to 48.77; 3 studies, 148 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 3.30 mm, 95% CI 2.88 to 3.73; 3 studies, 145 participants, 3 studies; moderate-certainty evidence). In addition, expansion plates resulted in higher inter-canine distances (MD 2.59 mm, 95% CI 2.18 to 3.01; 3 studies, 145 participants; moderate-certainty evidence). The use of Hyrax is probably effective for correcting posterior crossbite compared to observation (OR 48.02, 95% CI 21.58 to 106.87; 93 participants, 3 studies; moderate-certainty evidence). Two of the studies focused on adolescents (age 12 to 16 years) and found that Hyrax increased the inter-molar distance compared with observation (MD 5.80, 95% CI 5.15 to 6.45; 2 studies, 72 participants; moderate-certainty evidence). Intervention A versus intervention B When comparing quad-helix with expansion plates in children, quad-helix was more effective for posterior crossbite correction (RR 1.29, 95% CI 1.13 to 1.46; 3 studies, 151 participants; moderate-certainty evidence), final inter-molar distance (MD 1.48 mm, 95% CI 0.91 mm to 2.04 mm; 3 studies, 151 participants; high-certainty evidence), inter-canine distance (0.59 mm higher (95% CI 0.09 mm  to 1.08 mm; 3 studies, 151 participants; low-certainty evidence) and length of treatment (MD -3.15 months, 95% CI -4.04 to -2.25; 3 studies, 148 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and Haas for posterior crossbite correction (RR 1.05, 95% CI 0.94 to 1.18; 3 studies, 83 participants; moderate-certainty evidence) or inter-molar distance (MD -0.15 mm, 95% CI -0.86 mm to 0.56 mm; 2 studies of adolescents, 46 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and tooth-bone-borne expansion for crossbite correction (RR 1.02, 95% CI 0.92 to 1.12; I² = 0%; 3 studies, 120 participants; low-certainty evidence) or inter-molar distance (MD -0.66 mm, 95% CI -1.36 mm to 0.04 mm; I² = 0%; 2 studies, 65 participants; low-certainty evidence).  There was no evidence of a difference between Hyrax with bone-borne expansion for posterior crossbite correction (RR 1.00, 95% CI 0.94 to 1.07; I² = 0%; 2 studies of adolescents, 81 participants; low-certainty evidence) or inter-molar distance (MD -0.14 mm, 95% CI -0.85 mm to 0.57 mm; I² = 0%; 2 studies, 81 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: For children in the early mixed dentition stage (age 7 to 11 years old), quad-helix and expansion plates are more beneficial than no treatment for correcting posterior crossbites. Expansion plates also increase the inter-canine distance. Quad-helix is more effective than expansion plates for correcting posterior crossbite and increasing inter-molar distance. Treatment duration is shorter with quad-helix than expansion plates. For adolescents in permanent dentition (age 12 to 16 years old), Hyrax and Haas are similar for posterior crossbite correction and increasing the inter-molar distance. The remaining evidence was insufficient to draw any robust conclusions for the efficacy of posterior crossbite correction.

Orthodontic treatment for prominent upper front teeth (Class II malocclusion) in children and adolescents.

BACKGROUND: Prominent upper front teeth are a common problem affecting about a quarter of 12-year-old children in the UK. The condition develops when permanent teeth erupt. These teeth are more likely to be injured and their appearance can cause significant distress. Children are often referred to an orthodontist for treatment with dental braces to reduce the prominence of their teeth. If a child is referred at a young age, the orthodontist is faced with the dilemma of whether to treat the patient early or to wait and provide treatment in adolescence. OBJECTIVES: To assess the effects of orthodontic treatment for prominent upper front teeth initiated when children are seven to 11 years old ('early treatment' in two phases) compared to in adolescence at around 12 to 16 years old ('late treatment' in one phase); to assess the effects of late treatment compared to no treatment; and to assess the effects of different types of orthodontic braces. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 27 September 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 8), MEDLINE Ovid (1946 to 27 September 2017), and Embase Ovid (1980 to 27 September 2017). The US National Institutes of Health Ongoing Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: Randomised controlled trials of orthodontic treatments to correct prominent upper front teeth (Class II malocclusion) in children and adolescents. We included trials that compared early treatment in children (two-phase) with any type of orthodontic braces (removable, fixed, functional) or head-braces versus late treatment in adolescents (one-phase) with any type of orthodontic braces or head-braces, and trials that compared any type of orthodontic braces or head-braces versus no treatment or another type of orthodontic brace or appliance (where treatment started at a similar age in the intervention groups).We excluded trials involving participants with a cleft lip or palate, or other craniofacial deformity/syndrome, and trials that recruited patients who had previously received surgical treatment for their Class II malocclusion. DATA COLLECTION AND ANALYSIS: Review authors screened the search results, extracted data and assessed risk of bias independently. We used odds ratios (ORs) and 95% confidence intervals (CIs) for dichotomous outcomes, and mean differences (MDs) and 95% CIs for continuous outcomes. We used the fixed-effect model for meta-analyses including two or three studies and the random-effects model for more than three studies. MAIN RESULTS: We included 27 RCTs based on data from 1251 participants.Three trials compared early treatment with a functional appliance versus late treatment for overjet, ANB and incisal trauma. After phase one of early treatment (i.e. before the other group had received any intervention), there was a reduction in overjet and ANB reduction favouring treatment with a functional appliance; however, when both groups had completed treatment, there was no difference between groups in final overjet (MD 0.21, 95% CI -0.10 to 0.51, P = 0.18; 343 participants) (low-quality evidence) or ANB (MD -0.02, 95% CI -0.47 to 0.43; 347 participants) (moderate-quality evidence). Early treatment with functional appliances reduced the incidence of incisal trauma compared to late treatment (OR 0.56, 95% CI 0.33 to 0.95; 332 participants) (moderate-quality evidence). The difference in the incidence of incisal trauma was clinically important with 30% (51/171) of participants reporting new trauma in the late treatment group compared to only 19% (31/161) of participants who had received early treatment.Two trials compared early treatment using headgear versus late treatment. After phase one of early treatment, headgear had reduced overjet and ANB; however, when both groups had completed treatment, there was no evidence of a difference between groups in overjet (MD -0.22, 95% CI -0.56 to 0.12; 238 participants) (low-quality evidence) or ANB (MD -0.27, 95% CI -0.80 to 0.26; 231 participants) (low-quality evidence). Early (two-phase) treatment with headgear reduced the incidence of incisal trauma (OR 0.45, 95% CI 0.25 to 0.80; 237 participants) (low-quality evidence), with almost half the incidence of new incisal trauma (24/117) compared to the late treatment group (44/120).Seven trials compared late treatment with functional appliances versus no treatment. There was a reduction in final overjet with both fixed functional appliances (MD -5.46 mm, 95% CI -6.63 to -4.28; 2 trials, 61 participants) and removable functional appliances (MD -4.62, 95% CI -5.33 to -3.92; 3 trials, 122 participants) (low-quality evidence). There was no evidence of a difference in final ANB between fixed functional appliances and no treatment (MD -0.53°, 95% CI -1.27 to -0.22; 3 trials, 89 participants) (low-quality evidence), but removable functional appliances seemed to reduce ANB compared to no treatment (MD -2.37°, 95% CI -3.01 to -1.74; 2 trials, 99 participants) (low-quality evidence).Six trials compared orthodontic treatment for adolescents with Twin Block versus other appliances and found no difference in overjet (0.08 mm, 95% CI -0.60 to 0.76; 4 trials, 259 participants) (low-quality evidence). The reduction in ANB favoured treatment with a Twin Block (-0.56°, 95% CI -0.96 to -0.16; 6 trials, 320 participants) (low-quality evidence).Three trials compared orthodontic treatment for adolescents with removable functional appliances versus fixed functional appliances and found a reduction in overjet in favour of fixed appliances (0.74, 95% CI 0.15 to 1.33; two trials, 154 participants) (low-quality evidence), and a reduction in ANB in favour of removable appliances (-1.04°, 95% CI -1.60 to -0.49; 3 trials, 185 participants) (low-quality evidence). AUTHORS' CONCLUSIONS: Evidence of low to moderate quality suggests that providing early orthodontic treatment for children with prominent upper front teeth is more effective for reducing the incidence of incisal trauma than providing one course of orthodontic treatment in adolescence. There appear to be no other advantages of providing early treatment when compared to late treatment. Low-quality evidence suggests that, compared to no treatment, late treatment in adolescence with functional appliances, is effective for reducing the prominence of upper front teeth.