The Effect of Functional Crown Lengthening Versus Deep Margin Elevation on Periodontal Tissues (A Randomized Clinical Trial With Biochemical Analysis)

In dental practice, restoring cavitated proximal caries lesions is a common routine procedure in dental clinics. However, subgingival margins reaching below the cementoenamel junction are known to have a common clinical concern, especially when restoring severely destructed Class II caries. Ideally, the correct choice of treatment plan is critical to ensure successful outcomes (Padbury et al., 2003).

The use of direct adhesive restoration to restore large interproximal defects is not an ideal treatment option. Due to their size, such defects usually require indirect adhesive restorations. However, this appears to be challenging since cavity preparation, impression taking, the adhesive-bonding procedure, and proper moisture control may be impeded. These challenges are usually overcomed by functional crown lengthening (Mangani et al.,2015; Juloski et al.,2018).

Functional Crown lengthening is a surgical procedure to expose the gingival margins by apical displacement of the supporting periodontal structures, thus can facilitate an access and adequate isolation to achieve the optimum position of deep restorations and avoid violating the biological width (Magne & Spreafico, 2012; Sarfati & Tirlet, 2018).

The biological width is defined as the gingival attachment along the root surface, from the most coronal portion of the epithelium attachment to the most apical portion of the connective tissue attachment (Gargiulo et al.,1961). Therefore, a recommended distance of 3 mm or more between the restorative margins and the alveolar crest is considered necessary to avoid detrimental effects on neighbouring soft and hard periodontal tissues (Ingber et al.,1977; Lanning et al., 2003). The violation of the biological width results in severe gingival inflammation and consequently deep pocket formation or gingival recession, in addition to bone level reduction (Nugala et al., 2012).

Recurrence usually occurs particularly in patients with thick biotypes or when surgery comprises only gingivectomy. Moreover, recurrence leads to restoration limits being replaced sub-gingivally, whereas surgery aims to place them sub-gingivally (Ganji et al.,2012)..