The classic chart from Lombardi, illustrating the SPA factor. Every characteristic of a single tooth may carry evidence concerning the patient's age, sex, and personality. However, when designing a new smile, factors such as cultural background, the expectations of the patient and their lifestyle, as well as the dentist's artistic ideals and values, are to be taken into consideration.

Anterior esthetics were described depending on the personality, age, and gender of the person as it is reflected in the shape and form of that individual's teeth. Clinical investigations by Frush and Fisher concerning the sex, personality, and age (SPA) factor arrived at the norms for these investigations.


The masculine or feminine characteristics have an important effect on the esthetics of a pleasing smile. Femininity can be expressed in terms of delicacy and softness, whereas masculinity can be expressed in terms of vigor and angularity. 

Some authors described femininity in the female form as :

  • roundness, 
  • smoothness
  • the softness that is typical in a woman.

Masculinity, on the other hand, was described as:

  • cuboidal,
  • hard,
  • muscular, 
  • vigorous appearance, which is typical of men. 

If the incisal edges of the maxillary incisors, and especially the lateral, appear more rounded then the effect is a delicate, feminine pleasing smile. These rounded softer lines add to the delicate nature of the facial features of a female. The incisal edges and transitional line angles of feminine teeth are rounded, while the edges tend to be translucent. In addition, the white hypoplastic striations can be used to give the effect or illusion of delicacy. 

In the case of males, square incisal edges that appear to be blunt can enhance the masculine appearance. This does not mean that all the features of a male's dentition will appear according to the categories listed for masculine teeth, and, similarly, neither will the female's. 

It is common to find that people tend to exhibit various features of both sexes in the same dental arch. There are many factors related to the interpretation of these features. Cultural background, personal artistic ideals, and esthetic values are all to be taken into consideration. 

* The rotation of the lateral incisor's mesial surface, outward and beyond the distal surface of the central incisor can create a more delicate or softer position of the lateral when observed. Similarly, the lateral incisor may appear quite the opposite, or appear in a hard position, when it is located behind the distal surface of the central incisor. 

* In individuals of all ages, changes of character, position, or color of the teeth are reflected in their dentition. When we think of canine teeth, aggressive cartoon characters come to mind. The design of canines may take the passive-aggressive factor into consideration when the tone of the appearance is selected.  

An aggressive canine 

  • A tooth that is longer than the ones next to it and has a pointed incisal edge 
  • The frontal view may display a height of contour or a flat profile. 
  • A small incisal embrasure between the lateral and cupid teeth.

A passive cuspid may show no aggression at all.

  • The tooth is usually the same length as the adjacent tooth or even shorter.
  • a blunt rounded tip and a convex profile
  • large incisal embrasures between the laterals and canines.


The aging signs are seen in the facial features often reflect masculine or feminine traits, can also be seen in the contours and positions of the natural dentition. 

Young teeth are more textured, lighter, and brighter, with low color saturation. They exhibit transparent incisal edges. The enamel surface is semi-translucent, with a slightly irregular surface. Owing to the thicker enamel and translucency, the teeth look grayish white in certain areas.

Young Teeth 

  1. The anatomic crowns are not fully exposed shortly after the eruption of the permanent dentition.
  2. The cervical line is well below the gingival tissue.
  3. Triangular or square morphology that looks almost like a square or round crown.
  4. Enamel appears bluish-white or gray when exposed to light, and presents vitality. 
  5. Enamel is semitranslucent, hard and shiny with a slightly irregular surface.
  6. The labial surfaces of the unworn incisal edges may appear darker owing to the thickness and translucency in this region.
  7. The underlying color of the dentin of the natural tooth affects the overall color and may cause the dentition to appear yellow or gray-white.
  8. Have often white hypoplastic lines and lower saturation light characterization, owing to lower chroma, with a more textured, lighter, brighter and higher value.
  9. Smaller gingival embrasures and a gingival margin at the dentin-enamel junction. 
  10. Significant incisal embrasures.

Aged Teeth

  1. Aged teeth appear triangular, even if they are square or rounded by nature. As the gingival tissues recede, the root becomes narrower than the crown and comes into sight. 
  2. Shorter incisally but longer gingivally, which means that less of the tooth will be visible when smiling.
  3. Little incisal embrasures appear on the worn incisal edges. 
  4. Widened gingival embrasures owing to the recession of the gingiva. 
  5. Flat broad incisal edges and a dentin core are characteristic of the lower incisors. 

Functional, parafunctional and occlusal wear of the enamel surface will result in changes related to age. These changes can be observed in the maxillary central incisors, canines and mandibular anterior teeth. Generalized attrition results in posterior wear of the dentition as well. The broadening of the contact areas occurs from the interproximal enamel wear between the anterior and posterior teeth, and there can be up to a 1 cm decrease in the overall anteroposterior dental arch length, as the wear becomes advanced with age. This excessive wear can eventually lead to narrowing of the teeth. 

For class I classification, the incisal edges of the maxillary central incisors tend to wear more cervically, affecting the lingual, rather than the labial enamel. Eventually, the maxillary central and lateral incisors will exhibit the same incisogingival length. As the incisal wear continues, the lateral and central incisors and canines wear evenly, creating a flat incisal silhouette. This silhouette is quite characteristic of an aged occlusal plane without the incisal embrasures. Unlike the youthful smile that becomes flat and broad owing to the steep curve of the occlusal plane, the aged smile is affected by dental attrition and changes in tissue elasticity and facial muscle contractility.

Little or no incisal wear is characteristic of a class II incisor relationship. In patients with class II occlusion, and parafunctional habits such as bruxism or tooth grinding, the labial surfaces of the incisors tend to wear cervically. The patient's position is determined according to the individual's occlusal type, and the canine's wear patterns tend to be similar or not flat.

The translucent enamel is lost over years of wear and function. The enamel layer becomes thinner from simple daily functions, such as tooth brushing and eating, and as a result, the dentin begins to dominate the shade. Daily oral habits allow the pigments and ions to be absorbed into the teeth; in time, combining with the decreased enamel thickness, they dominate the shade of the dentition that becomes progressively darker. Changes in the underlying dentine, owing to aging or pathologically related color changes, also contribute to this phenomenon. 

Similarly, unlike young teeth, aged teeth exhibit higher chroma and less value. The translucent porcelain, and the depth and extent of the enamel built into the restoration, will depend on the effects that needed to be incorporated related to how young the smile should be designed. These changes affect not only the appearance of the teeth, but also theirfunction. Higher surface stains and increased crown flexibility are caused by the progressive thinning of the enamel. It is possible to re-establish a youthful smile, and the appearance and function of the crown, through the restoration of the lost tooth volume. In preservation of the remaining elements of the tooth, enamel should be the priority in any treatment approach, and the degree of success of the final outcome is related directly to such preservation.

These fine details are of the utmost importance for a thorough understanding of the teeth by skilled dentists so that their artistic skills can be used to create the necessary illusions in order to achieve a successful result. 


Not only the surrounding tissues of the dentition, but the personality, character and life-style of a patient must be evaluated as a whole, as all these factors can directly affect the color of the teeth.

For example, individuals who use red lipstick, the treatment (in terms of color) must be designed accordingly. As described by Steven Chu, colors have complementary peers. The complementary color for red is green. Therefore, if the restorations are produced without taking the patient's lipstick preference into consideration, when that patient uses red lipstick, the teeth will be appear greener than they actually are. To compensate for this effect, the restorations must be in harmony with the red color of the lips, and red pigments should be added to porcelain.

Another cultural point to be considered is that, until recently, Europeans favored teeth that are genetically normal, whereas Americans have always placed more value on whiter teeth. However, with the advent of bleaching, even Europeans are changing their values with a preference for whiter teeth. As more and more individuals use bleaching, the proportion of whiter teeth has increased, thereby changing the entire perception of dental health. The fact that white teeth appear to be cleaner and fresher is enough to persuade any individual of their desirability. 

Therefore, although imitation of nature is a priority for the dentist, sensitivity to the changes in dental treatments and the possibilities that they offer, along with the change of perception that they bring with them, must always be a consideration in treatment selection. Patient perception will always tend to favor whiter colors and higher values.

The knowledge, experience and the personal artistic skills of the dentist will result in a full understanding of the color phenomenon. Quality laboratory work is necessary to create natural restorations with natural tooth arrangement and proper proportions.

Ref. The science and art of porcelain laminate veneers, Galip Gurel