Smile design

What is smile design?

Smile design is the process carried out before aesthetic dental treatments, in which the intended result is planned together with the face, lips, gums and teeth. It is not a treatment or a material on its own; it is a roadmap. Depending on the outcome, veneers, crowns, bonding, whitening, orthodontics, or a combination of these may be recommended.

Planning covers factors such as tooth length, width-to-length ratio, the relationship between the incisal edge line and the lip, how well the midline aligns with the face, gum levels and colour. These factors are not assessed individually, but together with the person's facial structure and lip movements during speech.

A systematic review on digital smile design noted that this approach is associated with positive results for patient satisfaction, treatment acceptance and communication, but that the evidence remains limited because the studies are few in number and use different methods (Source 1).

What factors are considered in the design?

Planning generally proceeds from the face toward the teeth. First, reference points such as the facial midline and the lines of the eyes and lips are established; then the amount of tooth shown at rest and when smiling, the relationship between the incisal edges and the curve of the lower lip, and the spaces that appear at the corners of the mouth during smiling are evaluated. In the final stage, the width-to-length ratios, surface texture and colour of individual teeth are considered. These criteria are not fixed rules but starting points interpreted for each person; the goal is not a standard smile but a result that suits the person's face.

Who is it suitable for, and who is it not suitable for?

Smile design is suitable for people considering a change in shape, length or colour in several front teeth, those who want to replace old anterior restorations, or those whose smile proportions have been affected by tooth wear. For a small correction on a single tooth, a comprehensive design process is not always necessary.

If untreated tooth decay or gum disease is present, these are addressed first. Situations where the expectation cannot be clinically achieved should also be discussed openly: for example, if an excessive gum display is caused by the lip or jaw structure, a design involving only the teeth will not resolve it (Source 5). For more details, see the gum aesthetics article.

Treatment steps

1. Consultation and expectations: What the patient wants to change, what they like, and what is not important to them is discussed.
2. Clinical examination: Teeth, gums, bite, jaw joint and signs of teeth clenching are evaluated; X-rays are taken if needed.
3. Photographs and impressions: Facial and smile photographs, and video if needed, are taken; an impression or digital scan is obtained.
4. Analysis and design: Tooth proportions, the incisal edge line, the midline and gum levels are examined; the target tooth form is designed on a model or digitally.
5. Mock-up in the mouth: The design is transferred onto the teeth using a temporary material. The patient sees the result in the mirror and in photographs, speech and lip harmony are assessed, and changes are made if needed.
6. Treatment order: Based on the approved design, the order in which treatments will be carried out is determined.
7. Application and follow-up: Restorations are made according to the design tried in the mock-up; the bite is adjusted and an occlusal splint (night guard) is planned if needed.

How long does it take?

The planning stage usually takes 1–2 sessions; the application time varies depending on the treatments chosen. A plan involving only whitening and bonding can be completed within a few weeks, while a plan involving orthodontics or gum treatment can take months.

The treatment order directly affects the duration. For example, if whitening is planned, it is usually done before restorations, and time is allowed for the colour to settle, because the colour of porcelain and composite resin cannot be changed afterward by whitening.

Risks and limitations

The design shown on screen may not be exactly the same as the result in the mouth; for this reason, a mock-up in the mouth provides a more reliable preview than a digital image. Any change made during the design stage must be compatible with biological limits such as tooth structure and gum tissue.

An important risk is the unnecessary preparation of healthy teeth for the sake of design uniformity. Laboratory measurements have shown that even veneer preparations can remove approximately 3–30 percent of the tooth crown (Source 3). Lengthening teeth in the incisal direction has also been associated with an approximately 2.3-fold increase in veneer failure risk in one study (Source 6).

Force factors are also a limitation: a study spanning twenty years reported an approximately 7.7-fold increase in veneer failure risk in the presence of teeth clenching (Source 4). Smile design is therefore not only an aesthetic but also a functional planning process.

Finally, the design is a compromise between the patient's expectations and clinical reality. A smile admired in a photograph may not suit a person's gum structure, lip movements or bite; recognising such mismatches during the mock-up is far easier than recognising them after permanent treatment.

Alternatives

For colour concerns, see teeth whitening; for small corrections, see dental bonding and composite veneers.

Care and longevity

Smile design itself does not have a lifespan; the longevity is determined by the restorations made as a result of the design. Porcelain laminate veneers, crowns and composite resin have different care requirements and different longevity expectations.

The photographs and models taken during the design process can be kept as a reference for when a restoration is renewed or repaired in the future. Regular check-ups, an occlusal splint (night guard) if there is teeth clenching, and daily cleaning are common care principles for all restorations.

From a prosthodontist's perspective

From a prosthodontist's perspective, a good smile plan is not the one that makes the most changes, but the one that achieves the goal with the least intervention. This is why the mock-up stage matters: the target form is tried in the mouth first, and only then is the necessary portion of the tooth prepared. A controlled clinical study reported that veneer preparations were carried out based on such a mock-up (Source 2).

The main criteria considered during planning are: the amount of tooth and gum shown while smiling, the relationship between the incisal edge and the lip, the bite and how the teeth guide each other, teeth clenching, the condition of existing restorations, and which teeth actually need treatment. The treatment order is generally as follows: first decay and gum treatment, then orthodontics and whitening if needed, and permanent restorations last.

For a general overview, see the aesthetic dentistry guide page. The final decision on the right plan for you is made after an examination and, if needed, radiographic assessment.