April 18, 2021
Smile designing has evolved with the advent of cosmetic dentistry. In order to get an aesthetic smile, two zones have been in focus in particular. These are called the white and the pink zone. The white zone represents the teeth whereas the pink zone represent the soft tissues namely the gingiva and the lips. Both these zones need to be in a definitive proportion in accordance with the facial profile to ensure an aesthetic smile.
There are certain principles of smile designing that need to be satisfied. One of these refers to the gingival zenith point. This point is the highest point at the junction where the gingiva meets the teeth. The gingival zenith point is of prime concern in the upper front teeth region. These teeth, namely the central incisors, lateral incisors and canines, have a certain angulation of their respective gingival zenith points. When these teeth are divided vertically by an imaginary line that bisects the teeth, it helps us in identifying the ideal position of the gingival zenith point.
Taking a mid-point on the edge of the tooth and drawing a line till the gingival zenith gives us the axial inclination of the tooth. In cases of midline diastema (gap between the two front teeth), zenith points can be modified slightly during their correction in order to correct the angulation of the teeth. In the central incisors, the gingival zenith point lies slightly away from the midline. In the lateral incisors it coincides with the vertical midline. Finally, in the canines, the zenith point can vary but is most often positioned away from the midline.
Gingival zenith points also help in determining the relation between the zenith points of two adjacent teeth. This helps in determining the total amount of gingiva that should be visible during a smile. This factor particularly helps in smile designing for patients with a gummy smile and the ones who need a crown lengthening procedure.
The selection of a zenith point can also be done based on the patient's facial profile and personality. This is especially true when zenith point determination is done for canines. The angulation of the tooth and its shape differs in men and women. During a dental rehabilitation of the front teeth, smile designing is thus coupled with the overall outlook of a person.
Determination of gingival zenith position is mandatory when the upper front teeth are given a prosthesis in the form of a crown, bridge, implant or fixed dentures. During the fabrication of the prosthesis, the gingival zenith points are one of the key landmarks that are marked on a cast (replica of the teeth receiving the prosthesis). Any shift in the gingival zenith point can affect the natural contours of gingiva, the midline of each tooth and the relation of one tooth to its adjacent teeth. Periodontal plastic surgeries, whose goal is to change the position of the gingiva relative to the position of the corresponding tooth and bone, are done by keeping gingival zenith points as one of the landmarks. Gingival zenith points also need to be kept in mind during orthodontic (braces) treatment. Since these treatment modalities exert a pressure on the underlying bone, it is important that there is no shift in the inclination of the teeth and their subsequent zenith points during or after the treatment.
When the gingival zenith points are connected with each other, we get a gingival esthetic line. This horizontal line represents the total smile appeal. It also ensures that the zenith points on both sides of the face are symmetrical. This esthetic line also helps in determining the required proportion of the teeth, gingiva and lips relative to each other during a natural smile. Based on this esthetic line, surgical procedures like gingivectomy (gingiva cutting) or crown lengthening can be carried out.
Zenith points are an essential component of pink esthetics. Designing a smile can become much more precise when tooth angulations and subsequent treatment plans flow in conjunction with the determined zenith points. It also helps in maintaining the natural slopes and curves of the gingiva around the teeth when viewed from the front. At the end of the dental treatment, the zenith points contribute in assuring that the teeth, lips and gingiva are in harmony with each other.