Overview

Esthetic crown lengthening is a therapy used to elongate a particular tooth or a set of teeth either for aesthetic dentistry purpose or to correct an excess of gingival display (EGD). In the periodontal classification and conditions, this subject falls into the category of mucogingival deformities and conditions around teeth, in which we have among others, gingival excess (GE). In the GE, we can find the following:

1. Pseudo‐pocket
2. Inconsistent gingival margin
3. Excessive gingival display
4. Gingival enlargement

Etiology

The etiology of GE can be due to:

1. Excessive maxillary growth (Kokich 1993)
2. Altered Passive Eruption or short tooth syndrome (STS) (Chu et al. 2004)
3. Tooth malposition (Kokich 1993)
4. Gingival enlargement due to chronic inflammation, medications such as cyclosporine, phenytoin and calcium channel blockers, hormonal (pregnancy), or hereditary gingival fibromatosis
5. Deficient maxillary lip length
6. Excessive mobility of maxillary lip (Bhola et al. 2015)

In order for a clinician to determine the appropriate etiology, the following evaluation is required:

• Facial proportions
• Lip length and smile line
• Tooth proportions
• Gingival zenith and gingival margins of adjacent teeth

These evaluations will lead to a diagnosis/etiology of GE. First, the facial proportions can be determined by taking a cephalometric radiograph. The lower anterior facial height (LAFH) should equal approximately 55% of the whole length of the profile measured from the nasion to the menton. The lip length and the smile line should be assessed to be able to determine appropriate treatment thus determining the etiology is essential. The lip length that is measured from the nasion to the middle of the vermillion border has been given numerical numbers as shown in Table 12.1 by Ahmad (2005). The interesting in this table, it quantifies not only the lip length but also the exposure of the maxillary and mandibular centrals. Garber and Salama (1996) quantified the gingival display independently of the lip length as shown in Table 12.2 with treatment modalities. The measurement of tooth proportion also is an important tool to help us determine the etiology. Magne (2003) determined the proportions of unworn and worn maxillary teeth from first premolar to first premolar as shown in Table 12.3. In order for us to define the length of the tooth we need to determine the zenith. Chu et al. (2009) defined the presence of the zenith by being at 1mm from the vertical bisected midline for the central incisor, 0.4 mm for the maxillary lateral and coinciding for the maxillary canines. Once all of this has been determined, and the tooth are defined as short due to altered passive eruption, we can follow the Coslet (1977) classification, in which he divided patients in two types I and II based on the abundance of keratinized tissue from the GM to the MGL, and subdivision A and B, in which A, the bone was over 2 mm from CEJ and B the bone was at the CEJ level.