Comparative evaluation of a bioabsorbable collagen membrane and connective tissue graft in the treatment of localized gingival recession: A clinical study.

BACKGROUND: Gingival recession (GR) can result in root sensitivity, esthetic concern to the patient, and predilection to root caries. The purpose of this randomized clinical study was to evaluate (1) the effect of guided tissue regeneration (GTR) procedure using a bioabsorbable collagen membrane, in comparison to autogenous subepithelial connective tissue graft (SCTG) for root coverage in localized gingival recession defects; and (2) the change in width of keratinized gingiva following these two procedures.
MATERIALS AND METHODS: A total of 10 cases, showing at least two localized Miller's Class I or Class II gingival recession, participated in this study. In a split mouth design, the pairs of defects were randomly assigned for treatment with either SCTG (SCTG Group) or GTR-based collagen membrane (GTRC Group). Both the grafts were covered with coronally advanced flap. Recession depth (RD), recession width (RW), width of keratinized gingiva (KG), probing depth (PD), relative attachment level (RAL), plaque index (PI), and gingival index (GI) were recorded at baseline, 3 and 6 months postoperatively.
RESULTS: Six months following root coverage procedures, the mean root coverage was found to be 84.84% ± 16.81% and 84.0% ± 15.19% in SCTG Group and GTRC Group, respectively. The mean keratinized gingival width increase was 1.50 ± 0.70 mm and 2.30 ± 0.67 mm in the SCTG and GTRC group, respectively, which was not statistically significant.
CONCLUSION: It may be concluded that resorbable collagen membrane can be a reliable alternative to autogenous connective tissue graft in the treatment of gingival recession.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Periodontal disease is one of the most widespread disease in mankind, causing destruction of toothsupporting structures. Periodontal disease is multifaceted and creates myriad problems, such as mucogingival problems, osseous deformities, loss of supporting alveolar bone, and periodontal pocket formation to state a few.[1]

Gingival recession or marginal soft tissue recession is the location of the gingival margin apical to the cementoenamel junction.[2] Observed more frequently on buccal surfaces, gingival recession has long been a concern of many patients who feel that the “long-in-the-tooth” look is universally accepted as a sign of aging and tooth loss.[3] Although marginal tissue recession seldom results in tooth loss, it is associated with root hypersensitivity, frenal involvement, marginal tissue irritation, esthetic concerns, and a predilection to root caries.[4]

Any one of these problems or a combination of these, along with patient's intense esthetic desire promotes the patient to seek treatment for gingival recession. Hence, root coverage forms an important part of periodontal therapy.

In the past, various treatment modalities such as pedicle flaps, free gingival grafts, and coronally repositioned flaps have been used in the treatment of gingival recession. The disadvantages of these techniques have led to the development of subepithelial connective tissue graft (SCTG) procedures. The SCTGs have been highly predictable in gingival recession therapy with respect to a high percentage of root coverage, better healing and less postoperative discomfort at the donor site when compared with free gingival grafts.[5]

More recently, guided tissue regeneration (GTR) has emerged as another treatment modality for gingival recession. However, the need for a second surgical procedure for the removal of non-absorbable membrane and its associated complications has made use of absorbable barrier membranes more favorable. Of these absorbable membranes, collagen membranes are being used widely.[6]

Collagen is a natural protein and an integral part of mammalian tissues. There is a similarity between collagen in human skin and certain animal tissues. The rationale for selecting collagen were that collagen is the major extracellular macromolecule of the periodontal connective tissue and is physiologically metabolized by these tissues, it has been shown to be chemotactic for fibroblasts, acts as a barrier for migrating gingival epithelial cells, serves as a fibrillar scaffold for early vascular and tissue ingrowth, facilitates early wound stabilization and maturation, possess hemostatic properties through its ability to aggregate platelets, and is very weakly immunogenic, therefore biocompatible.[78]

Hence, an attempt is made through this study to compare the efficacy of bioabsorbable collagen membrane with SCTG for the treatment of localized gingival recession.

MATERIALS AND METHODS

Patient selection

Ten systemically healthy patients, showing at least two localized Miller's Class I or Class II gingival recession, from among the patients referred to the Department of Periodontics, JSS Dental College and Hospital, Mysore, participated in this study. Patients were explained the elected procedure in detail and were included for the study with their consent. Patients were informed that they could withdraw from the study at any time for any reason.

Presurgical treatment

The patients were educated and motivated with emphasis on proper oral hygiene maintenance. All the patients underwent the initial phase of treatment, which consisted of thorough scaling and root planning. In a split mouth design, the pairs of defects were randomly assigned for treatment with either SCTG Group or GTR-based collagen membrane (GTRC Group). Each group included 8 Miller's Class I and 2 Miller's Class II gingival recession cases. Both the grafts were covered with coronally advanced flap.

Measurements

All measurements were performed by one examiner. The participants were evaluated for the following clinical parameters:[9] recession depth (RD), recession width (RW), relative attachment level (RAL), width of keratinized gingiva (KG), probing depth (PD), plaque index (PI), and gingival index (GI) at baseline, 3 and 6 months postoperatively. PI was measured according to Silness and Loe[10] and GI according to Loe.[11] At 6 months post-treatment, the percentage of root coverage was calculated according to the following formula.[9]

Root coverage = Recession depth (preoperative – postoperative)/recession depth preoperatively × 100

Surgical procedure

All surgical procedures were performed by one surgeon.

COLLAGEN MEMBRANE GRAFT SITE

Preparation of the recipient site

Measurements were recorded [Figures 1–3] and the surgical area was prepared with adequate anesthesia using 2% lignocaine HCl containing 1:80,000 adrenaline. A trapezoidal flap was designed using 3 different types of incisions.

Figure 1

Pre-operative recession on maxillary left canine (GTRC Group)

Figure 3

Pre-operative recession width measurement at cementoenamel junction (GTRC Group)

Pre-operative, relative attachment level measurement with a reference stent (GTRC Group)

Primary incisions were made in mesial and distal directions from the cementoenamel junction up to 1 mm of the proximal line angle of the adjacent teeth, leaving the interdental papilla intact.

Second, a sulcular incision was made connecting the primary incisions, preserving all the existing radicular gingiva.

Two apically diverging vertical incisions are made starting at the end of each of the primary incisions and extending apically into the alveolar mucosa.

An initial blunt followed by a sharp dissection with a No. 15 scalpel blade was made to raise a combined full–partial thickness flap [Figure 4]. The flap was extended well beyond the mucobuccal fold so that it exhibited no tension when pulled coronally beyond the cementoenamel junction. The root was thoroughly planed and any convexities of the root were reduced. The intact papillae mesial and distal to the recession were de-epithelized. A measurement of the approximate length and width of the graft required was obtained with the use of a periodontal probe.

Figure 4

Combined full–partial thickness flap—recipient site (GTRC Group)

Placement of the collagen membrane

The bovine type I collagen membrane used in this study was developed by Bioproducts lab, Central Leather Research Institute, Chennai, according to the procedure of Sripriya et al.[12] The prepared collagen membrane was cross-linked for 24 h by gluteraldehyde (0.15% v/v) and sterilized using ethylene oxide. Additionally, before application on the patient it was soaked for 30 min in standard Ringer's lactate solution. The sterile collagen membrane was trimmed and contoured as needed to cover the recipient site, covering at least 2 mm of the bone all around [Figure 5]. Firm pressure was applied over the collagen membrane with sterile moist gauze for 5 min to adapt and adhere to the recipient site. The membrane was secured in position with 5-0 vicryl sutures [Figure 6].

Figure 5

Sterile collagen membrane trimmed and contoured to cover the recipient site

Figure 6

Collagen membrane secured on the recipient site (GTRC Group)

The pedicle was coronally repositioned over the collagen membrane to completely cover it, and secured in position with sling sutures into the mesial and distal papillae using the same suture [Figure 7].

Figure 7

Coronally repositioned flap completely covering collagen membrane (GTRC group)

Subepithelial connective tissue graft site

The recipient site [Figure 8] was prepared similar to the GTRC site.

Figure 8

Pre-operative recession on maxillary right first premolar (SCTG group)

Graft harvesting

After preparation of the recipient site, the donor area in the palate was anesthetized by block anesthesia of the greater palatine and nasopalatine nerve with 2% lignocaine HCl containing 1:80,000 adrenaline. Bleeding points were made corresponding to the required length of the graft. The technique described by Bruno[13] was used to harvest the CTG from the palate. The first incision was made perpendicular to the long axis of the teeth, approximately 2–3 mm apical to the gingival margin of maxillary teeth.

The second incision was made parallel to the long axis of the teeth, 1–2 mm apical to the first incision, depending on the required thickness of the graft. The donor tissue was removed from the palate as atraumatically as possible [Figure 9]. The CTG was placed on saline soaked gauze while [Figure 10] the palatal wound was closed. A horizontal crossed suspension suture was used to stabilize the donor area. Pressure was applied to the donor area with wet gauze while the graft was trimmed (as needed, in a mesiodistal dimension to fit the recipient site preparation). The epithelial collar was removed and discarded.

Figure 9

Connective tissue graft retrieval from the palate

Figure 10

Harvested connective tissue

Placement of connective tissue graft on the recipient site

The CTG was placed on the recipient site and secured in position with 5-0 vicryl sutures [Figure 11]. Then the overlying full–partial thickness flap was positioned over the CTG with very little tension on the flap using sling sutures into the mesial and distal papillae covering as much of the CTG as possible using the same suture [Figure 12].

Figure 11

Connective tissue graft sutured on the recipient site (SCTG group)

Figure 12

Coronally repositioned flap completely covering connective tissue (SCTG group)

Both the GTRC Group and SCTG Group sites were evaluated postoperatively at 2nd week, 1st, 3rd, and 6 months. On each visit, supragingival plaque was removed, but no subgingival instrumentation was performed. Clinical measurements were recorded and postoperative photographs were taken at the end of 6 months [Figures 13 and 14].

Figure 13

Six-month post-operative view showing stable root coverage on maxillary left canine (GTRC group)

Figure 14

Six-month post-operative view showing stable root coverage on maxillary right first premolar (SCTG group)

Statistical analysis

In the present study, independent sample t test was applied to find out the difference between SCTG Group and GTRC Group preoperatively, and analysis of variance (ANOVA) repeated measures was applied to see the difference in SCTG Group and GTRC Group along with pre- and post-operative situations.

RESULTS

All the 10 patients completed the study. Patients presented lesions with similar preoperative clinical parameters as shown by paired t test: RD (1.04), KG (1.08), and PD (1.09).

At the end of 6 months, as compared with preoperative parameters, both procedures produced statistically significant difference within the groups [Table 1]. However, at the end of 6 months, when compared between the 2 treatment groups the parameters showed no statistical significance.

Table 1

Effect of surgical procedures on clinical parameters

The mean root coverage at the end of 6 months was found to be 84.84% ± 16.81% and 84.0% ± 15.19% in SCTG and GTRC group, respectively. Statistically, the difference in root coverage between groups was not significant (t = 0.117).

DISCUSSION

The present study demonstrated the clinical applicability of a bioabsorbable collagen membrane in comparison to autogenous CTG for root coverage in localized facial gingival recession defects.

In this study, the autogenous subepithelial CTG was harvested from the patient's palatal mucosa. The anterior and posterior extensions of the donor site were limited to canine and palatal root of the first molar region as the palatal root of the first molar represents a natural barrier to graft harvesting because the tissue is thinnest in this area.[14] The lateral border site was formed by a horizontal line 2–3mm from the marginal gingiva of the maxillary teeth. The medial extension was restricted by the neurovascular bundle.

The collagen membrane used in this study was developed by Central Leather Research Institute, Chennai, which was type I collagen prepared from purified soluble bovine Achilles tendon. The collagen membrane was cross-linked by gluteraldehyde and sterilized by ethylene oxide gas and had a resorption time of 3–4 weeks. The resorption of the collagen membrane falls well within the time specified by a study, which has reported that during GTR procedures, bone and/ or periodontal ligament cell migration reach their peaks in 2–7 days after surgery, with a decrease in mitotic activity to almost normal levels by the end of 3–4 weeks.[15] Therefore, the length of time that the collagen membrane retains its integrity should be sufficient (3-4 weeks) to allow selective cell population.

The grafted sites were followed up for a period of 6 months. The mean root coverage obtained with a CTG was 84.84% and with collagen membrane graft was 84%. The difference in root coverage between the two groups was statistically not significant; the reason for this could be that the subepithelial CTG is principally composed of collagen fibers which is similar to that of the collagen membrane graft used in this study. Thus, high percentage and almost equal amounts of mean root coverage in both the groups imply that both surgical procedures have definite therapeutic utility.

However, the benefit of utilizing resorbable collagen material eliminates the need for any donor site, and being completely absorbed by the host tissues, there is no need for surgical reentry for its removal unlike the nonresorbable barrier membranes.[16] Other studies using collagen membrane for root coverage have reported a mean root coverage between 51% and 85%.[7] The mean root coverage of 84% with collagen membrane grafting observed in the present study falls within the reported range. Comparing CTG and GTR, other studies have reported thus, Zucchelli et al.,[17] SCTG=93.5%, GTR=85.7%; Trombelli et al.,[18] SCTG=81%, GTR=48%; and Harris et al.,[19] SCTG=97.1%, GTR=75.1%. Rosetti et al.[20] reported a root coverage of 95.6% for SCTG and 84.2% for collagen-based GTR techniques. The mean root coverage obtained with a CTG in the present study was 84.84%.

In the present study, the mean keratinized gingival width increase was 1.50 ± 0.70 mm and 2.30 ± 0.67 mm in the SCTG and GTRC group, respectively. Similar increase in the amount of keratinized tissue after the GTR procedure found in the other studies[17192122] that compared SCTG and GTR techniques.

CONCLUSION

In the present study, both autogenous CTG and resorbable collagen membrane graft are effective and predictable surgical techniques for the treatment of gingival recession improved the esthetics thus, satisfying the cosmetic demands of the patients and the efforts of the surgeon.

Resorbable collagen membrane used in this study was very well tolerated by the patients without any adverse effects.

Within the purview of this study it may be concluded that resorbable collagen membrane can be a reliable alternative to autogenous CTG in the treatment of gingival recession for, the former eliminates donor site morbidity, reduces the need for multiple surgeries and expense, saves time that would be required for harvesting a CTG, and offers unlimited graft availability of uniform thickness. To confirm the use of collagen membrane as a good alternative for treatment of gingival recession, more longitudinal studies are required in this field of periodontal plastic surgery.