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This is the first article in a three-part series considering skeletal discrepancies in the vertical and transverse dimensions. Discrepancies in the vertical dimension are a relatively common finding, presenting challenges for the orthodontist, in terms of treatment planning, management and relapse.
CPD/Clinical Relevance: This article aims to increase awareness of the assessment, aetiology and management of patients presenting with a reduced Frankfort/maxillary mandibular planes angle and reduced anterior lower face height commonly described as ‘low angle’.
Diagnosing discrepancies in the vertical dimension is vital to understanding how skeletal, dental and soft tissue factors contribute to the development of a malocclusion. This article provides an overview of the assessment of the vertical dimension and discusses the aetiology and management of patients presenting with a reduced Frankfort/maxillary mandibular planes angle (F/MMPA) and anterior lower face height (ALFH).
The definition of ‘low angle’ in orthodontics is a decreased FMPA more than one standard deviation below the average of 27° (such as an FMPA <22°).
A low angle is associated with decreased vertical facial proportions and may be associated with a forward growth rotation of the mandible. Other terms used to describe a low angle include hypodivergent, brachyfacial and short face.
There is currently limited evidence available regarding the prevalence of patients with a ‘short face’.
During a frontal examination, the face height can be divided into thirds, with each third being roughly equal in length (Figure 1). The upper third is measured from trichion to glabella. The middle third, usually described as the anterior upper face height (AUFH), is measured from glabella to columella. The ALFH is measured from columella to soft tissue menton. The AUFH and ALFH may be equal, increased or decreased with respect to each other.
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