Clinical and Radiographic Comparative Evaluation of Osseous Resection by Piezoelectric Device Versus Conventional Rotary Instruments in Crown Lengthening Procedure: A Randomized Controlled Clinical Trial

Surgical Crown lengthening (SCL) procedure facilitates restorative and prosthetic rehabilitation to provide adequate clinical crown structure to teeth which are otherwise compromised due to subgingival pathologies. One of the main advantages of the surgery is gain in supragingival crown length which is desirable for restoring severely lost tooth structure. This procedure provides increase in retention and resistance forms of the tooth necessary for restorative treatment. Indications of this procedure are subgingival caries, crown & root fracture, short clinical abutments, cervical root resorption and altered passive eruption.

Gargiulo et al. has given the concept of biologic width the distance between the base of the gingival sulcus and height of alveolar crest) based on classic histologic study in humans. He measured the average dimensions of epithelial junction and connective tissue attachment, the summed value of these dimensions gave biological width (2.04mm=0.97mm+1.07mm). Later on, Vacek et al.2 examined naturally occurring dimensions in human cadaver histomorphometrically and measured mean dimensions for epithelial attachment (1.14 +/- 0.49 mm) and for connective tissue attachment(0.77 +/- 0.32 mm). The average dimensions reported was approximately 2mm. The importance of biologic width lies in the fact that the violation of this width leads to gingival inflammation, attachment loss, and alveolar bone resorption. The integrity of biologic width should be maintained while performing crown lengthening for healthy hard and soft tissues, required for prosthetic and restorative rehabilitations.

Nevins M et al. and Ingber JS et al. proposed "3mm rule" for crown lengthening. According to this, 3mm of alveolar bone should be removed during crown lengthening, but this can not be applicable to all cases. Deas DE et al. in a study demonstrated significant tissue rebound following crown lengthening which was found to be related to placement of flap with respect to alveolar crest. More the distance between POST SUTURING Flap position and alveolar crest, less was the tissue rebound observed.

Osseous surgery in crown lengthening can be performed using rotary & manual instruments like carbide diamond burs, surgical chisels and files which leads to generation of heat, post-operative discomfort, swelling and trismus. Vercellotti et al. proposed that Piezosurgery is a new osteotomy procedure that requires microvibrations at ultrasonic frequency facilitated to cut hard tissue, while soft tissue remained unaffected. The sites treated with piezoelectric device had gain in bone level compared to sites treated by carbide bur or diamond bur. Ma LI et al and Esteves JC et al in a study performed on animals, demonstrated that the use of piezoelectric device in bone cutting showed advanced bone healing compared to traditional bone cutting. Sortino et al. proposed that piezosurgery osteotomy showed less post-operative complications (facial swelling, trismus, discomfort) although it required longer time for surgery. Verardi S.et al. evaluated and proposed that piezosurgery showed more favorable response in periodontal compromised patients in terms of less chewing discomfort, less cold sensitivity and low pain perception at various time points compared to conventional surgical treatment.

Till date, no studies have compared the periodontal healing, patient based perception of pain, and discomfort after osseous resection in crown lengthening using piezosurgery with conventional rotary instruments. The aim of this study is to comparatively evaluate, clinically and radiographically,the changes in periodontal healing, surgical time required and postoperative morbidity observed in patients undergoing osseous resection in crown lengthening procedure with conventional rotary instruments versus piezoelectric device.