Mandibular symphysis dimensions among various craniofacial patterns: A systematic review and meta-analysis.

OBJECTIVES

To evaluate and synthesize the available evidence on mandibular symphysis dimensions across different sagittal and vertical craniofacial skeletal patterns.

METHODS

Eligibility criteria: cross sectional studies comparing mandibular symphysis dimensions among individuals with different sagittal and vertical skeletal patterns.

INFORMATION SOURCES: unrestricted literature search of six databases (PubMed, Scopus, Web of Science, LILACs, Cochrane and Google Scholar) was conducted up to April 2025 without language restriction. Risk of bias: the quality assessment of the included studies was conducted using Joanna Briggs Institute tool.

SYNTHESIS OF

RESULTS

random-effects meta-analyses were performed using mean differences (MDs) and 95% confidence intervals (CIs). Heterogeneity was assessed using I2 and Tau2 statistics. Subgroup analyses were conducted based on ethnicity, imaging modality, and risk of bias. Publication bias was evaluated.

RESULTS

Included studies: twenty-three cross-sectional studies involving 3313 participants (40.35% male) were included.

SYNTHESIS OF

RESULTS

class III subjects showed significantly greater symphysis area (MD=2.37[1.33, 3.41]), height (MD=0.75[0.27, 1.22]), and convexity (MD=3.59[0.69, 6.49]) compared to Class I. Hyperdivergent individuals had increased symphysis height (MD=1.31[0.53, 2.1]) and reduced width (MD=-1.25[-2.37,-0.12]), while hypodivergent individuals showed reduced height (MD=-0.68[-1.34,-0.03]) and increased width (MD=1.42[0.41, 2.42]). Subgroup analyses revealed ethnicity and risk of bias as significant modifiers, particularly in Class II and vertical pattern comparisons. No significant publication bias was detected.

DISCUSSION: Limitations of evidence: the inclusion of mostly retrospective studies, presence of growing individuals, inadequate control for confounders, inconsistent age and sex reporting, and limited outcome data restricted the strength and scope of the meta-analysis.

INTERPRETATION: symphysis dimensions vary by skeletal pattern, with vertical growth type showing stronger associations than sagittal class.

REGISTRATION: PROPSERO (CRD420251049382).