A smile can often determine how well a person can function in society.
Aesthetics with function is the trend that we had long been waiting for. The focus of dentistry in the present times is not only prevention and treatment of disease but on meeting the demands of better esthetics.
Patients Desires and Expectations
Patient’s chief complaint and concerns and their expectations of the final result are the first and primary step in designing a treatment plan. Proper documentation is a must to reach an appropriate diagnosis and that inludes: full face photos, lip at rest or repose photos, anterior and lateral photos and/or video of the patient smiling naturally, dynamically as well as an exaggerated smile, retracted anterior and lateral views, retracted views, retracted views of the anterior dentition. The clinician should also obtain impressions (whether digital or analog) as well as a facebow and a bite registration in CR (centric relation), so that the case can be properly mounted and articulated on a semi adjustable articulator. All of this critical information for the clinician to properly evaluate, review, treatment plan and thus, treat the patient appropriately and effectively.
A basic overall assessment of the smile must start from an outside-in approach. Assessment of:
- patient’s facial thirds, in horizontal plane,
- Alignment of the facial midline and the dental midline
- asymmetries from the right and left hemifacial portions
- interpupillary line and occlusal planes as well as the relation to the horizon and
- developmental growth pattern
A good example is a patient who may have a concern over an excessively gummy smile, when in fact, it may be due to the fact the patient has an excessively long middle third of the face and longer facial height, indicating vertical maxillary excess (VME). Vertical maxillary excess is a skeletal issue, and hence, would require a different treatment modality to successfully treat the patient’s concern.
Lip Length, Lip Position, Mobility and Symmetry
The lips create the boundaries of the smile. Overall lip mobility is simply the movement of the lips at rest to the farthest position that occurs when the patient smiles spontaneously and is directly related to the upper lip length. Assessment of the upper lip length and amount of tooth that is displayed at rest must be first assessed and then reassessment at the farthest position. The average upper lip length in males is 23 mm and 20mm in females, who have an average of 1.5 mm of higher lip line, and thus showing more tooth display at rest. The average lip mobility in general is 7-8 mm, with females having slightly more lip elevation than males. Asynchronous or asymmetric Lip movement can lead to more tooth and/ or gum displayed on one side versus the other, creating a disharmony in the overall smile of the patient.
The amount of tooth that is displayed at rest is greater in females than males by an average of 1.5mm. Average display in female is 3.5 mm of maxillary central incisors at rest versus 1.9mm in males and as patients age, they display less of the maxillary incisors and more mandibular incisors. This is a result of changes in soft tissues to the skeletal base.
Incisal Edge Position in Relation to Surrounding Tissues and Horizontal Planes
One landmark to evaluate is the interpupillary line and how the incisal edge line is parallel in relation to it. The incisal edge position should be assessed in relation to the occlusal plane and posterior teeth and the incisal edge in relation to the lower lip/wet dry line or smile line. Another consideration is the “buccal corridor”. The buccal corridor is the space that is present between the lateral aspects of the posterior teeth and the corner of the mouth. When there is “dark” space in the buccal corridor, this is considered a “negative space”. It has been suggested that having minimum “negative space” in buccal corridors is preferred esthetically.
It is important to evaluate the relationship of the dental midline to the facial midline in addition to the overall angulation of the midline. Studies show that most people will be unable to detect up to a 4 mm dental midline deviation from the facial midline. However, when there are slight changes in crown and midline angulation, it becomes quickly evident to most people. Hence, overall angulation of the midline is more critical than the overall position of the midline to create an esthetically pleasing smile.
Current Tooth Position Within Dentoalveolar Housing
Ideally, tooth position should be assessed in three dimensionally so that the following can be evaluated properly:
- Facial-Lingual Position
- Mesial-Distal Position
- Apical-Coronal Position
Tooth Proportions and Proper Length to Width Rations
The length of the maxillary central incisor is 10.5-11 mm and average width to be 8.0-9.0 mm, creating a length to width ratio of approximately 76%. This can be related to the “golden proportions”, a term that related back to ancient Greeks who used the term to related the proportions between large and small in the beauty of nature.
Anterior Guidance and Coupling
An equally important, and sometimes overlooked principle when it comes to smile design, is the importance of function following form and how the anterior teeth couple together and help guide the posterior teeth apart. Ideally, canine guidance with immediate posterior disocclusion is desired as this has been shown to decrease overall elevator muscle activity.
Other Factors to Consider – Microesthetics
When it comes to designing the ideal smile for patients, especially with the use of indirect restorations, the clinician needs to assess and discuss the final color or shade desired by the patient. If possible, a shade that is naturally pleasing but esthetically enhancing to the patient’s final desired result is best. The desired facial surface texture, overall incisal translucency, additional tooth characteristics including incisal effects, embrasures, tooth shape, and variations in value, hue and chroma from the centrals to the cuspids are some of the factors to be kept in mind while designing a smile.
Dentistry has evolved from a curative to a creative science in a very short span of time. The principles of smile design require an integration of esthetic concepts that harmonize facial esthetics with the dental composition. It is very important that when planning treatment for cases of compromised esthetics, to not isolate smile design from a comprehensive and holistic approach to patient care.