Vertical effects of cervical headgear in growing patients with Class II malocclusion: a systematic review and meta-analysis

Abstract

Background: Cervical headgear (cHG) has been shown to be effective in Class II correction both with dental and orthopaedic effects but has traditionally been associated with vertical adverse effects in terms of posterior mandibular rotation.

Objective: To assess the treatment effects of cHG treatment in the vertical dimension.

Search methods: Unrestricted literature search of five databases up to May 2023.

Selection criteria: Randomized/non-randomized clinical studies comparing cHG to untreated controls, high-pull headgear (hp-HG), cHG adjuncts, or other Class II treatment alternatives (functional appliances or distalisers).

Data collection and analysis: After duplicate study selection, data extraction, and risk-of-bias assessment according to Cochrane, random-effects meta-analyses of mean differences (MD)/standardized mean diffences (SMD) and their 95% confidence intervals (CIs) were performed, followed by meta-regressions, sensitivity analyses, and assessment of certainty on existed evidence.

Results: Two randomized/16 non-randomized studies (12 retrospective/4 prospective) involving 1094 patients (mean age 10.9 years and 46% male) were included. Compared to natural growth, cHG treatment was not associated on average with increases in mandibular (eight studies; SMD 0.22; 95% CI -0.06, 0.49; P = 0.11) or maxillary plane angle (seven studies; SMD 0.81; 95% CI -0.34, 1.95; P=0.14). Observed changes translate to MDs of 0.48° (95% CI -0.13, 1.07°) and 1.22° (95% CI -0.51, 2.94°) in the SN-ML and SN-NL angles, respectively. No significant differences were seen in y-axis, facial axis angle, or posterior face height (P > 0.05). Similarly, no significant differences were found between cHG treatment and (i) addition of a lower utility arch, (ii) hp-HG treatment, and (iii) removable functional appliance treatment (P > 0.05 for all). Meta-regressions of patient age, sex, or duration and sensitivity analyses showed relative robustness, while our confidence in these estimates was low to very low due to the risk of bias, inconsistency, and imprecision.

Conclusions: cHG on average is not consistently associated with posterior rotation of the jaws or a consistent increase in vertical facial dimensions among Class II patients.

Registration: PROSPERO registration (CRD42022374603).

Keywords: Class II malocclusion; cervical pull headgear; clinical trials; meta-analysis; orthodontics; systematic review.