Lower lip analysis

The inclination of the lower lip white roll to labiomental fold affects perception of chin size after augmentation or reduction (Fig. 36.1). If the inclination of the lower lip is vertical and the demarcation between the lip and chin is poor, the patient will appear to have an excessively large chin after augmentation. This is particularly true if a full height implant is incorrectly used. The lower lip analysis is intermingled with the labiomental fold analysis because the lip inclination helps define the labiomental fold. If a patient has a deep overbite and the lip is everted, then the lower lip will have an oblique inclination. The obliquity of the lower lip will contribute to a deeper labiomental fold with a more acute angle. The surgeon should note this because an alloplastic implant that is too tall will deepen the fold and make the labiomental fold angle even more acute. If it is helpful, the lower lip inclination can be classified as follows: Type I is nearly vertical, type II is slightly posterior, type III is significantly posterior, and type IV is most oblique.

Fig. 36.1 The inclination of the lower lip white roll to labiomental fold affects perception of chin size after augmentation or reduction. The classification of lip-to-labiomental fold inclination: type I is nearly vertical, type II is slightly posterior, type III is significantly posterior, and type IV is most oblique.

Labiomental fold analysis

If two chins project exactly the same amount, the chin with the higher and/or shallower labiomental fold will always appear larger from the front (Fig. 36.2). Since the chin is primarily seen as the pad, the labiomental fold defines the apparent vertical height of the chin. Thus, augmenting a patient with a high, shallow labiomental fold tends to increase the appearance of the vertical height of the chin as well as its overall size. To overcome this problem, the surgeon should reduce the vertical height of the implant (see below) to limit augmentation to the lower pogonion. If the chin is long with a high fold, the patient may need both a vertical chin reduction and a sagittal augmentation. In contrast, a patient with a low, distinct labiomental fold will tolerate chin augmentation much better because the implant accentuates only the chin pad.

Fig. 36.2 Line drawings demonstrating that the position of the labiomental fold determines the chin pad percentage of the lower facial height. A, The relationship of the lip height to chin pad height is determined by the labiomental fold. B, High indistinct labiomental fold gives the illusion of a large chin. C, Low distinct labiomental fold gives the illusion of a smaller chin.

Static and dynamic chin pad analysis

The normal chin pad thickness is 8–11 mm. The chin pad thickness can be easily estimated by paramedian palpation. Soft tissue chin projection should be greatest at the lower part of the pogonion. The soft tissue chin pad position and static chin pad ptosis are noted. Chin pad clefting or fasciculations are documented. Since the chin pad is dynamic, soft tissues are also assessed during smiling.

The observer will note that when a chin pad is thick, a smile usually improves the patient’s appearance because the thick pad becomes effaced (Fig. 36.3). In contrast, as a thin chin pad is effaced upon smiling, the chin appears even more prominent (Fig. 36.4). During a normal smile, elevation of the corners of the mouth brings the chin pad superiorly. Some patients have a horizontal non-lifting smile such that the lower lip depressors are unopposed. Unopposed activation of the lower lip depressors produces dynamic chin pad ptosis with smiling as the chin pad drops (Fig. 36.5).

Fig. 36.3 Effect of smiling on a thick chin pad. A, Lateral photograph of patient in repose. B, During a smile, the thick chin pad becomes effaced, usually improving the appearance of the chin.

Fig. 36.4 Effect of smiling on a thin chin pad. A, Lateral photograph of patient in repose. B, Smiling will cause effacement of a thin soft tissue chin pad unmasking the underlying bony chin prominence.

Fig. 36.5 During a normal smile, the zygomaticus and levator muscles elevate the corners of the mouth brings the chin pad superiorly. Some patients have a horizontal non-lifting risorius-dominated smile. In a horizontal smile, the lower lip depressors are unopposed. Unopposed activation of the lower lip depressors produces dynamic chin pad ptosis with smiling. A, Lateral photograph of patient in repose. B, Unopposed activation of the lower lip depressors produces dynamic chin pad ptosis with smiling.

Bony chin analysis

The optimal site for bony chin projection is the lower portion of the pogonion, not at the inferior portion of the labiomental fold. Since the surgical spine of the mental symphysis is beneath the labiomental fold, it may contribute to an acute labiomental fold or chin projection that is too superior and, therefore, need reduction. The location and prominence of the surgical spine is determined be palpation. In other cases, mentalis muscle coalescence beneath the fold (usually with a soft tissue cleft) can contribute to excessive lower labiomental fold prominence. This can be differentiated from bony chin excess by asking the patient to pout.

Submental analysis

Subcutaneous adipose and skin laxity are assessed. The surgeon should determine if preplatysmal or subplatysmal adipose is contributing to submental fullness. Skin and pre/subplatysmal adipose may need to be excised in order to improve the chin/neck contour.

During the physical evaluation, the surgeon must keep in mind that chin augmentation in women should be conservative. Female patients are more apt to complain that a chin implant is too large and request removal. It is important to note, that removing an excessively large implant is no simple matter. Removing an implant can result in surface irregularities and fasciculations or the redundant tissue can cause static chin pad ptosis (Fig. 36.6). When evaluating a patient with an excessively large implant, rather than simply removing the implant, we recommend that the existing implant be exchanged with a smaller implant (see below) or an osseous genioplasty should be performed. The new implant or osseous advancement will support the chin pad soft tissues and reduce fasciculations and/or ptosis.

Fig. 36.6 Unsupported redundant chin soft tissue produces surface irregularities, fasciculations and/or static ptosis after removal of an implant without replacement. We recommend that an existing excessively large implant be exchanged with a smaller implant or an osseous genioplasty. The new implant or osseous advancement will support the chin pad soft tissues and reduce surface irregularities, fasciculations and/or ptosis. A, Static chin ptosis (left > right) following chin implant removal without replacement. B, Surface irregularities when pouting.