Root Coverage with a New Collagen Matrix and Coronally Advanced Flap: A Case Report

US Food and Drug Administration for regenerative therapy involving teeth and implants, including treatment of dehiscence defects around teeth. Fabricated as a matrix and composed of pure porcine collagen obtained by standardized, controlled manufacturing processes. The collagen was extracted from veterinary-certified pigs and purified to avoid antigenic reactions. The matrix was made of collagen type I and type III without further cross-linking or chemical treatment and sterilized in double blisters by gamma irradiation. CM has two layers and is approximately 2.5 mm thick. The first layer is a compact layer, facing the oral cavity, consisting of a denser collagen that protects the wound but allows tissue adherence for favorable wound healing. This layer has a smooth texture with appropriate properties to accommodate suturing to the host mucosal margins. The second layer is a thicker, porous collagen that encourages tissue integration. This porous surface is placed adjacent to the host tissue to facilitate organization of the blood clot and promote neoangiogenesis [11,12]. Because CM seems to be a promising soft tissue graft substitute, we decided to test in this case report whether its placement under a CAF in a recession defects support root coverage.


Introduction
The treatment of gingival recession is a common requirement due to aesthetic concern or root sensitivity in patients with high standards of oral hygiene [1]. Gingival recession is defined as an apical shift of the gingival margin from its position 1 mm coronal to or at the level of the cemento-enamel junction (CEJ) with exposure of the root surface to the oral environment [2].
Tooth brushing trauma is the primary etiologic factor for gingival recession; in this situation cervical abrasion defects are frequently associated with the root exposures [3]. In the last decades, different surgical procedures were proposed to obtain root coverage: Pedicles flaps (PF), connective tissue graft (CTG), guided tissue regeneration, coronally advanced flaps (CAF), CAF+CTG, and more recently CAF+CTG plus enamel matrix derivative [4][5][6][7][8][9]. The coronally advanced flap (CAF) is a very common approach for root coverage, the surgery does not involve a palatal donor site, and it was demonstrated to be a safe and predictable. Localized gingival recessions have been successfully treated with this technique [10]. Outcomes have been reported by adding a connective tissue graft to the coronally advanced flap (CAF+CTG).
Due the morbidity and time associated with soft tissue graft harvest and the limited supply, the acellular dermal matrix is an important substitute. However, because this allograft material is derived from human cadavers, it is associated with ethical concerns, possible risk of disease transmission, extensive shrinkage during the healing period and is not completely incorporated histologically.  1:100,000, the root surface was gently scaled and planed with Gracey curettes(Hu-Friedy, Chicago, IL, USA), which contributed to reduce buccal prominence, and conditioned with 24% EDTA gel for 2 min to remove the smear layer. The exposed root surface was rinsed abundantly with sterile saline solution to remove all EDTA residues.
The surgical technique used to achieve soft tissue coverage was CAF. Two oblique, divergent beveled incisions were performed at the mesial and distal line angles of the two peripherical teeth with gingival recession. These incisions, together with the intrasulcular incisions along the mesial and distal recession margins, designed the two external surgical papillae. Crossed submarginal incisions, made interproximally, created the interdental surgical papillae.
The soft tissue apical to the root exposure (including the residual keratinized tissue) was elevated full thickness by inserting a small periosteum elevator into the probeable sulcus and proceeding in the apical direction to expose 3.0 to 4.0 mm of bone apical to the bone dehiscence. This was done to include the periosteum and the maximum soft tissue thickness in the central portion of the flap covering the avascular root exposure (Figure 1b).
The vertical incisions were elevated split thickness, keeping the blade almost parallel to the bone plane, thus leaving the periosteum to protect the underlying bone in the lateral areas of the flap. Apical to the bone exposure, split-thickness flap elevation continued until it was possible to move the flap passively in the coronal direction. To permit the coronal advancement of the flap, all muscle insertions present in the thickness of the flap were eliminated. This was done keeping the blade parallel to the external mucosal surface. Coronal mobilization of the flap was considered adequate when the marginal portion of the flap was able to passively reach a level coronal to the CEJ of the recession defects. The flap should be stable in its final coronal position, even without the sutures. Once coronally advanced, the flap partially overlaid the soft tissues mesial and distal to the receiving bed. These areas and the facial soft tissue of the anatomic interdental papillae were deepithelialized to create connective tissue beds ( Figure 1c). CM test material was trimmed to extend 2.0 to 3.0 mm beyond the bone crest (both laterally and apically) ( Figure 1d) and fixed with a sling suture using a 5-0 sutures (Vicryl, Johnson & Johnson, S. J. Campos, Brazil) around the crown of the tooth (Figure 1e). The flap was coronally positioned 2.0 mm above the CEJ to fully cover the CM by suturing it to the de-epithelialized papilla regions. At all times caution was maintained to avoid over compression of the test material. Suturing of the flap started with two interrupted periosteal 5-0 sutures at the most apical extension of the vertical incisions; it proceeded coronally with other interrupted sutures, each of them directed from the flap to the adjacent buccal soft tissue, in the apical-coronal direction. This was done to facilitate the coronal displacement of the flap and to reduce the tension of the flap. The sling sutures permitted stabilization of the surgical papillae over the interdental connective tissue beds and allowed for a precise adaptation of the flap margin over the convexity of the underlying anatomic crowns. At the end of the surgery, the flap margin was coronal to the CEJ (Figure 1f). This was done to compensate for post-surgical soft tissue shrinkage.
No periodontal dressing was applied. No antibiotic was prescribed. Acetaminophen 750-mg as needed for pain was noted. The patient was instructed to rinse three times a day for 1 minute with 0.12% chlorhexidine digluconate solution during 4 weeks. Rapid surgical healing with minimal postoperative morbidity was observed at 1 week (Figure 2a). The sutures were removed 14 days after surgery. esthetic in a 3 mm buccal gingival recession associated to traumatic brushing in the maxillary left canine (Figure 1a). Her medical history was unremarkable, no contraindications for periodontal surgery and no talking medications known to interfere with periodontal tissue healing, and she denied any history of smoking and collagen allergic. Periapical radiograph was taken, in a standardized manner using the long-cone paralleling technique.
The patient agreed to participate in this study and gave their written informed consent on an Institutional Review Board consent form. The study protocol involved a initial therapy to establish optimal plaque control and gingival health conditions, surgical therapy, a maintenance phase, and a postoperative evaluation 2, 4, 6 and 12 months after the surgery. Clinical photographs were taken at baseline, at surgery and each follow-up visit.
A periodontal examination was performed and all clinical measurements were determined to the nearest millimeter using a UNC-15 periodontal probe (Hu-Friedy, Chicago, IL, USA). Vertical probing measures were made at the mid-buccal aspect of canine measured from the CEJ to the free gingival margin. All measures parameters were recorded at baseline included gingival recession depht (3 mm), probing depth (2 mm) and clinical attachment level (5 mm). The width of keratinized tissue (3 mm) was determined from gingival margin to the muco-gingival junction (MGJ) that was accomplished by coronal displacement of the alveolar mucosa against a horizontally positioned periodontal probe.
The goal of treatment was determines if a CM with CAF might be as effective in the root coverage procedure of Miller's class I recession defect. The patient was offered the option the coronally advanced flap plus connective tissue graft (CAF+CTG) is considered the gold standart procedure. Because the morbidity and time associated with soft tissue graft harvest, CM+CAF were chosen.

Surgical Procedure
Preoperative intra-oral antisepsis was accomplished using 0.12% chlorhexidinedigluconate solution rinsed for 1 min. Following administration of local anesthesia with 2% mepivacaine containing  Subject was advised to practice a care mechanical oral hygiene 4 weeks following surgery to minimize trauma to the surgical site and after this period, instructed in the Bass technique with an ultrasoft toothbrush and monitored once every 2 months until the end of the study at 12 months. During this period received professional supra-gingival plaque control. The patient reported very slight discomfort.
The clinical observation at 12-months revealed complete root coverage with an adequate zone of keratinized tissue with good healing, tissue contour without adverse sequelae (like keloids), color, and texture, nicely at the native adjacent soft tissues (Figures 2b and 2c).

Discussion
This report documents the use of CM+CAF for root coverage. This surgical procedure was designed to be shorter, less aggressive, and was thought to have fewer postoperative complications. Recently published prospective clinical trials investigating the efficacy of CM in treating both keratinized mucosal deficiencies and gingival recession defects suggesting that CM may provide, viable alternative to autogenous tissue grafts and unlimited "off-the-shelf'' supply of grafting material, reducing surgery time by approximately one-third. The savings in time and discomfort is weighed against the cost of the matrix [11,12].
Despite esthetics being considered the primary goal of rootcoverage procedures, few studies evaluated the changes of esthetic conditions as they related to the opinions of patients. In these studies, the patient was satisfied with the final esthetic result. The incidence of adverse effects, such as discomfort with or without pain, was directly related to donor sites of CTG [12]. Also, procedures that made a reduction in the operatory time, eliminated the need for a second surgical site and its associated morbidity and used smaller palatal grafts was better accepted [13].
An in vitro testing of this collagen matrix showed the in-growth of primary human fibroblasts into the CM, which resulted in an increased expression of extracellular matrix proteins such as collagen type I and fibronectin. Recently, CM and another prototype with a different source of collagen were compared in a non-submerged healing environment in combination with the apically repositioned flap. Clinical results demonstrated an increase in the width and thickness of the KT. The qualitative histological analysis revealed complete healing of both CM, resulting in mature mucosal and submucosal tissues.
In an experimental study, the combination of a CM and the CAF procedure significantly reduced the recession and increased the width of KT. Histologically, allowed an uneventful healing, the matrix being completely incorporated into the adjacent host connective tissues, in the absence of a significant inflammatory response. The healing was characterized by the formation of new cementum and new connective tissue attachment in the apical aspect of the defect and by a junctional epithelium in its most coronal third. When compared with the CAF alone, the CM graft attained more tissue regeneration, with a shorter epithelium and a larger new cementum formation [14].
An in vivo evaluation of Mucograft® minimal inflammation and no multinucleated giant cells was present. The material persisted in the tissue throughout the study. At the same research, results demonstrate great potential to reverse tissue recession and promote more healthy gingival tissue [15]. Collagen matrix can enhance oral soft tissue healing compared with spontaneous healing during the first week, based on clinical observations that the two distinct structures paved the way to improve the healing by an early stabilization of the coagulum (matrix function) [16].

Summary
This present study seems to suggest that CM+CAF can provide a valid treatment procedure in Miller's class I root coverage and CM may offer a new option to CAF alone and palatal harvest. The need for twostage surgery was eliminated with a significant reduction in surgery time, no pain related and less morbidity presented. More extensive, long term clinical studies are needed to support this result obtained.