![]() This patient came to see me because he felt his teeth did not show in his smile. It may not be possible functionally to add much length to the teeth, but if they are restored with stronger reflective surfaces, they can appear more dominant in the face. Similarly, if the anterior teeth have worn down, they will have less reflective surface available. Completing orthodontics to upright the facial surface will allow for better light reflection. This is because of the position of the teeth and not the actual color. If the teeth are retroclined, for example, there is less reflective surface available, and so a patient may whiten his or her teeth in an attempt to make them brighter but still feel they are dull. This understanding of visual dominance helps me consider the light reflective properties of the teeth and how I might influence them so the teeth appear more dominant in the smile. I can then discuss, given the limitations of the small maxilla, what can be done dentally to compensate for this compromised starting point. Through a process of systematic analysis, I recognize this and can explain their orthognathic options. Sometimes, I have patients who are maxillary deficient and want their teeth to look more obvious in their smile. In smile design, we learn about the importance of dominant centrals: One of the factors we can change is the light reflective surface of a tooth or teeth. We can then narrow our focus to the smile and any areas of tension to determine what we should change to improve the balance and harmony. ![]() There will be areas of harmony that are pleasing to the eye, and areas of visual tension that are not pleasing. It also helps to take a step back and look at the entire face as if it were an artistic composition. For example, procedures such as crown lengthening and orthodontics can be calibrated according to the planned end result. If the smile is designed before treatment, this also serves as quality control for all stages of treatment. With this approach, the risks and benefits of treatment can be viewed in the context of the desired and achievable end result to ensure valid consent is obtained. We may decide to deviate from what’s considered the ideal smile, but this can be identified at an early stage and discussed with patients to set realistic expectations before they decide on treatment. We can design the ideal smile according to the face and then compare it with the existing starting point, taking into consideration the underlying skeletal structure, the lip position and dynamics, and the position and health of the current dentition. Systematic Smile DesignĪs such, the traditional rules of smile design need to be considered more as guidelines to help us understand why a smile does not appear to be in harmony. So, mathematical rules for design need to be placed in the context of the face. A very asymmetric face does not necessarily look in harmony with a perfectly symmetrical smile. The premise of facially driven smile design is that the smile should be in harmony with the landmarks of the face. This is why many patients end up with teeth of different sizes and colors, where compromises have been made to “conform” to the existing condition. Anti-reflection coatings are used to diminish the losses.Planning a mouth full of dentistry without first designing the ideal smile is like trying to build a house with no architectural plans. The reflection loss at a single surface may seem small, but with multiple lenses, it becomes an unacceptable loss. Since this contribution is proportional to the square and higher powers of the reflection coefficient, it can often be neglected. This calculation of the transmission is not exactly correct since it neglects the contribution from multiple internal reflections in the medium. Reflected internally from second surface: % The reflection coefficients can be used to calculate the amount of light transmitted through a medium if the only losses are reflection losses. Normally incident upon a medium of index n 2 = The reflectivity of light from a surface depends upon the angle of incidence and upon the plane of polarization of the light. This normal incidence reflectivity is dependent upon the indices of refraction of the two media. ![]() For purposes such as the calculation of reflection losses from optical instruments, it is usually sufficient to have the reflectivity at normal incidence. The general expression for reflectivity is derivable from Fresnel's Equations. The reflectivity of light from a surface depends upon the angle of incidence and upon the plane of polarization of the light. Reflection Coefficient for Light Normal Reflection Coefficient
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