CATEGORY 54 AUSTRALASIAN DENTIST A smile is not just the expression shaped by the hard and soft tissues of the face, but emotions! It doesn’t include mere teeth but the surrounding structures as entities. e upper and lower lips create the smile frames, which unveils the beauty of teeth and gingiva. Several soft-tissue factors in uence how a smile looks. ese include: u Lip thickness – fuller or thinner lips can change the teeth and gingiva visibility. u Intercommissure width – the horizontal distance between the corners of the mouth. u Interlabial gap – the vertical space between the upper and lower lips when smiling. u Smile index – the ratio of width to height of the smile, giving it either a wide or narrow appearance. u Gingival architecture – the shape and contour of the gums around the teeth. e corners of the mouth, called the commissures, mark the sides of the smile. Interestingly, we can visually detect both an inner commissure (where the inside lining of the mouth meets) and an outer commissure (the visible corner of the lips). e inner commissure is where two important muscles meet: the buccinator (cheek muscle) and the orbicularis oris (the muscle around the mouth), coming together at a point called the modiolus. is area plays a key role in controlling facial expressions, especially the smile. Classification of smile: 1. Posed/ social smile: A posed smile is voluntary and produces a socially acceptable expression often used in clinical photographs. 2. Natural/duschenne smile: Duchenne smile is spontaneous and emotionally driven, resulting in elevation of the mouth corners and the characteristic eye crinkling. Because the Duchenne smile re ects true emotional expression, it o ers valuable insight into how a patient’s smile functions in real-life situations which is way beyond static imaging [Fig 1] Miniaesthetics: Incisor and Gingival Display in Smile Aesthetics e amount of maxillary incisors (Morley ratio) and gingival display during smiling plays a critical role in perceived smile aesthetics. e esthetic and youthful appearance of tooth exposure is said to be full incisor exposure with 2 mm of gingiva. However, the ideal upper lip position in adolescents is just apical to the gingival margin or even 2mm tooth coverage, allowing nearly full but not complete incisor visibility [Fig 2]. e acceptable range of incisor exposure extends from approximately 1 mm to 4 mm of visible crown below the upper lip. Exceeding this range, especially with more than 4 mm of gingival display, is generally perceived as unesthetic and may be associated with what is colloquially referred to as a “gummy smile” [Fig 3]. e vertical relationship between the upper lip and the maxillary incisors is dynamic and age-dependent. As age advances, upper lip length tends to increase, leading to a gradual reduction in incisor display at rest and during smiling. us it is important to carefully evaluate incisor-lip relationships during initial diagnostic assessments and incorporate age-related changes into comprehensive orthodontic treatment planning [Fig 4]. CLINICAL Dr Geoff Hall Smile Analysis Part II Mini Aesthetics: unveiling the smile By Dr Geoff Hall, BDsc (Melb) Cert Orth (Uni of Penn) MRACDS (Orth), Diplomate – American Board of Orthodontics (ABO) Posed smile Duchenne smile Fig 1: Types of smile Fig 2: Normal smile: full incisor exposure +/- 2 mm gingiva Fig 3: Gummy smile with more than 4 mm gingival exposure Fig 4: Pt with poor Morley ratio due to over intrusion of anteriors2. SOURCE: Ackerman MB, Ackerman JL. Smile analysis and design in the digital era. J Clin Orthod. 2002 Apr;36(4):221-36. PMID: 12025359 Transverse Dimensions & the Buccal Corridor in Smile Aesthetics e transverse dimension of a smile is in uenced by both the width of the dental arches and the patient’s facial proportions. A key element in this is the buccal corridor, which refers to the dark space visible between the maxillary posterior teeth (usually the premolars) and the inner cheek during smiling. A smile with excessive buccal corridor (also called negative space) may appear narrow or collapsed and is often viewed as unesthetic [Fig 5], especially in patients with wider faces. Conversely, minimal buccal corridors are generally considered more attractive, particularly in females, as they contribute to a broader, fuller smile. Fig 5: Buccal corridor space
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