CATEGORY 66 AUSTRALASIAN DENTIST CLINICAL Dr Geoff Hall By Dr Geoff Hall, BDSc (Melb) Cert Orth (Uni of Penn) MRACDS (Orth) Specialist Orthodontist Smile Analysis Part II Micro Aesthetics Microaesthetics refer to the relationship of gingival elements to the teeth, the contour shape and structure of teeth. Aesthetic Dental Guidelines: width, proportions, and smile design Width relationships and the golden proportion The apparent width of maxillary anterior teeth as seen in a normal smile differs from their actual mesiodistal dimension due to the curvature of the dental arch. This anatomical feature means that only portions of the lateral incisors and canines are visible from a direct frontal view. For optimal aesthetics, the apparent width of the lateral incisor should be approximately 62% of the apparent width of the central incisor. Similarly, the visible width of the canine should be 62% of the lateral incisor, and the first premolar should appear 62% as wide as the canine. This recurring ratio of 62% is often referred to as the golden proportion, a concept that appears in various aspects of human anatomy and classical design [Fig. 1]. This tool remains a valuable guideline in smile designing while giving the appropriate tip, torque, and angulation to the maxillary anterior teeth. aesthetic imbalance is due to excessive width, insufficient height, or both [Fig. 2]. For example, a central incisor that measures 8.7 mm in width and 8.5 mm in height appears almost square, exceeding the ideal width-to-height ratio. In such cases, if the width is within the normal range, reduced crown height may be the underlying issue. Causes of short clinical crowns Several factors can contribute to short clinical crowns. In children, incomplete eruption may be the cause and often resolves naturally. However, in older patients, loss of crown height from attrition may necessitate restorative treatment. Excessive gingival coverage may call for crown lengthening procedures. Alternatively, an inherent distortion in crown form may require more extensive aesthetic intervention, such as facial veneers or full-coverage crowns. Any noted disproportions and their potential causes should be included in the patient’s problem list to ensure they are addressed prior to the completion of orthodontic treatment. Connectors and embrasures Connectors and embrasures play a crucial role in the aesthetics of the smile and must be carefully assessed. The connector, or interdental contact area, is the visible region where adjacent teeth appear to be in contact. While the actual contact point is very small, the connector includes the closely positioned areas above and below this point. Connector height is greatest between the central incisors and progressively diminishes as one move posteriorly, following an apical trend [Fig. 3]. The embrasures – the triangular spaces located incisal or gingival to the contact areas – should ideally be slightly larger than the connectors. This proportion promotes natural light reflection, enhances visual appeal, and allows for easier oral hygiene maintenance. Fig. 1: Golden proportion Fig. 4: Black triangles Fig. 2: Short clinical crown Fig. 3: Connectors Tooth width-to-height ratio It is generally accepted that the visible width of a tooth – particularly from the incisors through the premolars – should be approximately 80% of its height. In orthodontic assessment, evaluating both the width and height of teeth is essential, as identifying any disproportion between the two can help determine whether an Embrasures: black triangles Open gingival embrasures, or black triangles, can significantly detract from the appearance of the smile [Fig. 4]. These voids occur when interdental papillae are insufficient in height or volume. In adults, black triangles are often caused by the loss of gingival tissue due to periodontal disease. They may also appear after orthodontic correction of crowded or rotated maxillary incisors, where the repositioned teeth shift the contact area incisally, revealing space that was previously concealed. Careful assessment of papillary support and the impact of tooth movement is essential in preventing or addressing black triangle formation.
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