Evaluation of the Anatomical Limit for Mandibular Arch Distalisation in Skeletal Class III Patients with Different Growth Patterns: A Systematic Review

Introduction: Temporary Anchorage Devices (TADs) enable distalisation of the mandibular dentition in patients with mild to moderate Class III jaw bases. The extent of distalisation is influenced by the Mandibular Posterior Anatomical Limit (MPAL), which varies with growth patterns. Aim: To evaluate and compare the MPAL across different growth patterns in skeletal Class III patients. Materials and Methods: The present systematic review followed PRISMA 2020 guidelines and was registered in PROSPERO (CRD42024616501). A comprehensive search of PubMed, Web of Science, Embase, Scopus, Cochrane Library, Google Scholar, and OpenGrey was conducted from inception up to December 2024. Following the PICOS framework: (P) adult patients with skeletal Class III malocclusion and varying vertical growth patterns; (I) no intervention, grouping by growth pattern; (C) comparisons between normodivergent, hypodivergent, and hyperdivergent patterns; (O) MPAL measured on Cone Beam Computed Tomography (CBCT); (S) observational cross-sectional studies. Extracted data was used to study measurements of MPAL in different growth patterns included reference planes, reference point and reference levels; additional parameters were third molar status, sex distribution, and racial background. Risk of bias was assessed using the Critical Appraisal Checklist of the Joanna Briggs Institute (JBI). Results: Out of 5117 studies 11 studies on class III malocclusion with varying growth patterns, used the mandibular occlusal plane as the reference. Nine studies used the Posterior Occlusal Plane (POL) as the reference line and the most lingual point of the second molar’s distal root as the reference point; five measured at the subfurcation level and six at the sub-CEJ level. Conclusion: In class III malocclusion, the MPAL distance decreases from the furcation to the apex, making apical distance critical during distalisation. The racial group of the subjects, third molar status, vertical pattern and skeletal sagittal pattern all had an impact on MPAL. Of the three development patterns, patients with hyperdivergent growth patterns have the smallest MPAL and the highest risk of cortical contact in molar distalisation, whereas those with hypodivergent growth patterns have the lowest risk.