Introduction

Broadly defined, a crown lengthening is a surgical procedure whereby additional tooth structure is exposed coronal to the free gingival margin. Indications may be functional to allow for the restoration of a severely broken‐down or decayed tooth or when an improvement may be indicated in the esthetic zone. In this chapter, we will focus on the functional one.

In terms of function and the basic restoration of tooth structure, the concept of biologic width must be invoked. Specifically, roughly 2 mm of pristine unrestored tooth structure should be made available therapeutically for the connective tissue attachment to the tooth and its epithelial interface between the restorative margin and the alveolar crest. If that is not planned, then, it is likely that the resulting restorative margins will impinge on the periodontal hard and soft tissues, which would affect the long term prognosis (Cohen 1964; Schroeder and Listgarten 1971; Kois 1996; Camargo et al. 2007).

As a surgical procedure, a crown lengthening may be called upon in the esthetic zone if maxillary anterior teeth appear short either as a result of congenital or acquired excessive gingival display (Nevins and Skurow 1984; Allen 1993; Vacek et al. 1994; Herrero et al. 1995; Lanning et al. 2004; Camargo et al. 2007).

In all its indications and applications, a crown lengthening is a resective procedure where the marginal periodontium is positioned apically so that additional tooth structure is exposed supragingivally (Nevins and Skurow 1984; Parma‐Benfenali et al. 1985; Wagenberg et al. 1989; Sorensen and Engelman 1990; Vacek et al. 1994).

As would be the case for any periodontal surgery, a pre‐treatment checklist should be considered based on sound guiding principles and a reliable and easily reproducible road map.

Checklist

This well planned coordinated chronological checklist should include:

1. A thorough medical history.
2. A complete dental history and examination.
3. Treatment objective agreed upon by all treating dentists and clearly understood by the patient.
4. Soft tissue analysis; at the time of the relative absence of pre surgical inflammation, depth of the mucobuccal fold, width of keratinized gingiva, biotype, and periodontal probing depths. These would be significant determinants of incisions and flap designs as we will discuss later.

   Relevant considerations as to osseous anatomy: the presence or absence of bony ledges, tori, or buttressing bone.

5. Presence of periodontal disease as evidenced by deep periodontal probing depths and osseous craters. These are specifically relevant as to the nature and extent surgery planned.
6. Important aspects of dental anatomy which include proximal surfaces and vestibular convexities or lack thereof, anatomical furcations, root trunk lengths, radicular fluting, and cross section root anatomy. These considerations are relevant as to the viability and indications of the surgery in the first place and whether the tooth should even be so treated in the first place and whether the new osseous crest result in unrestorable root surfaces or furcation exposures.
7. Sterility of the surgical field. An oral antiseptic such as Chlorhexidine should be considered for rinsing during the surgery.
8. Anesthesia. Because the type of treatment involved is directed primarily at relatively superficial areas, local infiltrations are usually sufficient to provide comfort. A fair concentration of epinephrine is recommended for adequate vasoconstriction. This helps with visualization and a more deliberate procedure.
9. Incisions. Reverse bevel or sub marginal versus intrasulcular and flap design.

   Depending on the width of keratinized tissue, this will dictate the choice of a submarginal or a reverse bevel incision where a soft tissue collar is removed, for convenience if sufficient tissue is available.

   More specifically however, with a minimal width of keratinized gingiva, an intrasulcular incision is favored. Palatal incisions however are always submarginal since, in the absence of a mucogingival junction and with a resulting ample width of keratinized tissue, the final position of the new gingival margin must be worked into the initial flap design and anticipated in that initial incision, a concept referred to as crestal anticipation.

   Releasing incisions and flap extension for access both mesiodistally and apicoronally.

   In order to have sufficient operational access and be able to a create a smooth and continuous flow in the osseous topography, one that would be compatible with a physiologic architecture, and flaps need to be designed and sufficiently extended with that purpose in mind. Within the area of osseous recontouring, the flap should logically be a full thickness elevation, partial thickness dissections to be addressed later with respect to suturing. The mesiodistal extent of soft tissue flaps should be based on passive retraction for access and instrumentation. This can be done by extending the flap sufficiently on either side beyond the operating field or by making judicious use of vertical release incisions.

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