A comparative evaluation of subepithelial connective tissue graft (SCTG) versus platelet concentrate graft (PCG) in the treatment of gingival recession using coronally advanced flap technique: A 12-month study.

OBJECTIVE: The objective of this study was to clinically evaluate and compare the efficacy of platelet concentrate graft (PCG) with that of subepithelial connective tissue graft (SCTG) using a coronally advanced flap technique in the treatment of gingival recession.
MATERIALS AND METHODS: Twelve patients with a total of 24 gingival recession defects were selected and randomly assigned either to experimental site-A (SCTG) or experimental site-B (PCG). The clinical parameters were recorded at baseline up to 12 months post-operatively and compared.
RESULTS: The mean vertical recession depth (VRD) statistically significantly decreased from 2.50 ± 0.48 mm to 0.54 ± 0.50 mm with PCG and from 2.75 ± 0.58 mm to 0.54 ± 0.45 mm with SCTG at 12 months. No statistically significant differences between the treatments were found for VRD and clinical attachment level (CAL), while keratinized tissue width (KTW) gain was statistically significant.
CONCLUSION: Both the SCTG and the PCG group resulted in a significant amount of root coverage. The PCG technique was less invasive and required minimal time and clinical maneuver. It resulted in superior aesthetic outcome and lower post-surgical discomfort at the 12 months follow-up.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Gingival and periodontal diseases have afflicted humans since the dawn of history.[1] Gingival recession is one of the most common aesthetic and functional concerns associated with periodontal tissues. It is defined as “the displacement of soft tissue margin apical to cemento–enamel junction with exposure of root surface.”[2] Gingival recession is well documented in populations having a good standard of oral hygiene and also in those with a high plaque index (PI).[3] A host of factors lead to gingival recession, e.g., alveolar bone dehiscence, gingival quality and quantity, high muscle attachment and frenal pull, iatrogenic factors, localized inflammatory processes, hard tooth brushes, traumatizing tooth brushing and tooth malposition.[4]

The possible consequences of gingival recession are: Compromised aesthetics, dentinal hypersensitivity, cervical abrasions, plaque retention and gingival bleeding, risk of root caries and, also, fear of losing teeth.[56]

Various techniques have been introduced to the field of Cosmetic Periodontology since Grupe and Warren first described the “lateral positioned flap.”[7] Subsequently, a number of surgical techniques have been proposed such as pedicle grafts, regenerative techniques and bilaminar procedures.[8] Of these, the bilaminar technique using subepithelial connective tissue graft (SCTG) seems to be the most promising for root coverage, with a 65-98 mean percentage of root coverage.[9]

In spite of its promising results, SCTG has its own limitations, such as lack of graft availability, need for a second surgical site, proximity to palatine neurovascular complex and unaesthetic tissue contour at the recipient site.[1011] To overcome some of these drawbacks and to accomplish optimum root coverage, an alternate technique using platelet concentrate graft (PCG) has been developed.

PCG is an enhanced concentration of platelets processed from platelet-rich plasma and incorporated into two layers of properly trimmed collagen sponge. Because the platelet concentrate has a higher number of platelets per millimeter, it is expected that it contains a higher concentration of growth factors to accelerate/enhance regeneration.[12] Moreover, as donor site graft procurement is avoided, there is less post-surgical discomfort involved as well as a relatively unlimited source of graft material availability with this procedure.[13] Hence, PCG can be a viable alternative to SCTG for the treatment of gingival recession.

MATERIALS AND METHODS

Twelve patients, fulfilling the selection criteria, were selected for the study from the Outpatient Department of Periodontics and Oral Implantology of our institution. Twenty-four sites in 12 patients (each patient having near-identical Miller's Class-I or II gingival recession defects[14] on contralateral teeth of same arch) were randomly assigned into experimental site-A (SCTG) and experimental site-B (PCG) as per the split mouth design.

Inclusion criteria

Patients between 18 and 60 years of age

Patients with Miller's Class-I or II gingival recession defects measuring ≥2 mm on anterior teeth or premolars, on the contralateral sides of the same arch or one in each quadrant

In good systemic health (with no history of drug intake known to affect the periodontium)

No history of surgical treatment in the delineated area for at least 2 years prior to the study

Teeth involved in the study are vital and free of faulty restorations.

Exclusion criteria

Patients unable to perform routine oral hygiene procedures

Patients who are known smokers

Any uncontrolled local or systemic diseases that might contraindicate periodontal surgery

Teeth showing trauma from occlusion.

The surgical procedure and possible alternatives were discussed and informed consent was obtained from the patients. The study protocol was approved by the Ethical Committee of the Institution. Before surgery, all the patients received professional oral prophylaxis, oral hygiene instructions and occlusal adjustments as per the individual requirements.

Clinical measurements

A customized acrylic stent was made with guiding grooves on each experimental tooth angled toward the deepest part, i.e. midfacial part of the recession. Baseline measurements were taken immediately before the procedure. Any measurement falling in the 1-mm interval was considered as 0.5 mm. The following clinical parameters were assessed: PI (Silness and Loe 1964), Gingival index (GI) (Loe and Silness 1963), Pocket depth (PD), Vertical recession depth (VRD) and Clinical attachment level (CAL).

A visual analogue scale (0-5) form, with “0” indicating negligible discomfort and “5” indicating unbearable pain, was completed by the patients.[15]

All the pre-operative measurements were performed using a UNC 15 probe by the same examiner who also performed all the surgeries. A second examiner who was masked to the surgical procedure evaluated the clinical sites post-operatively. This evaluation included color match, tissue texture and contour of the surgical area in comparison with the adjacent tissue.[15] The scoring was from 1 (most favorable) to 4 (least favorable).

Surgical procedure

After the baseline measurements were recorded, the surgical procedure was initiated. Contralateral sites were assigned at random to one of the surgical techniques (SCTG or PCG) by the flip of a coin.[15] After the extraoral skin preparation was done with 5% povidone–iodine solution, the patient was asked to rinse his/her mouth with 10 mL of 0.2% chlorhexidine digluconate solution for 1 min.

Recipient site preparation

Following local infiltration with 2% lidocaine, an intrasulcular incision was given on the buccal aspect of the involved tooth. A horizontal right angle incision was then made into the adjacent interdental papilla at or slightly coronal to the level of the cemento–enamel junction (CEJ) of the tooth presenting the defect. Two divergent vertical incisions were given starting at least 0.5 mm from the gingival margin of the adjacent teeth and extending into the alveolar mucosa. The intrasulcular, horizontal right angle incision and the vertical incisions were connected and a trapezoidal full-thickness flap was raised 3-4 mm apical to the bone dehiscence; from there, a partial-thickness dissection was then performed apically to allow for coronal positioning of the flap [Figure 1a–d].[16]

Figure 1

(a) Recession depth; (b) Recession width; (c) Crevicular horizontal and vertical incisions given; (d) Full-thickness flap elevation done

The preparation of the recipient site included the de-epithelization of the papillae adjacent to the defect. The exposed, affected root surface was scaled and planed and subsequently root biomodification was done with a fresh tetracycline solution (125 mg tetracycline hydochloride/1 mL of saline) for 1 min.[17]

Donor site preparation

SCTG

The Edel trap door (1974) approach was adopted for harvesting a connective tissue graft of 1.5-2.0 mm from the palate using a no. 15 scalpel blade. The graft was placed over the recipient site such that its coronal margin was located at the CEJ and its apical margin at least 3.0 mm apically beyond the base of the defect. Coronal advancement of the partial-thickness flap was done so as to completely cover the graft without tension. The coronally positioned flap was secured in position by independent sling sutures using 5-0 vicryl sutures. Independent interrupted sutures were placed along the vertical incision line for close approximation [Figure 2a and b].[18]

Figure 2

(a) Liu's Class III type A incision design (Trap door); (b) Split-thickness flap elevation done

PCG

A laboratory centrifuge having a maximum speed of 3500 rpm was used. The blood collection tubes were blue top 10 mL vaccutainers containing 1.5 mL, 3.2% sodium citrate solution.

8.5 mL of venous blood was drawn and transferred to two 10 mL blue top vaccutainers. These vaccutainers were then placed into the centrifuge and subjected to a 1st spin for 10 min at 1300 rpm, which led to the separation of whole blood into the lower RBC region and an upper straw-colored plasma region. The straw-colored plasma was drawn into a syringe, moving the needle from above downwards up to the RBC layer or into the first 1-2 mm of that layer. The contents of the 10 mL syringe were then expressed into red top vaccutainers and were subjected to a second spin for 10 min at 2000 rpm (Gonshor technique for PRP preparation). The contents of each tube consisted of an upper portion of clear yellow supernatant serum, containing fibrinogen and a very low concentration of platelets, the bottom layer, often red tinged, consisting of highly concentrated platelet-rich plasma (cPRP). Two layers of collagen sponge were used as carrier of the platelet concentrate gel. The cPRP-soaked collagen sponge was trimmed to the size of the measured defect. Once the collagen sponge was soaked with cPRP, 10% CaCl2 was added to cPRP in the ratio of 1:20 along with whole blood. This completed the preparation of PCG.[1215]

The PCG of desired dimension was transferred to the recipient site using a similar technique as described for SCTG [Figure 3a–c]. The surgical site was then covered with an aluminum foil over which a non-eugenol (Coe pack) periodontal pack was given.

Figure 3

(a) Platelet-rich plasma; (b) Platelet concentrate graft (PRP + COLLACOTE); (c) Platelet concentrate graft sutured to recipient site

Post-surgical care

Patients were instructed to avoid brushing their teeth in the treated area for 2 weeks but to rinse their mouth with 10 mL of 0.2% chlorhexidine digluconate solution twice daily for 10 min. The periodontal pack (Coe-pack) was removed on 1-week recall and the surgical site was irrigated gently with saline. The sutures were removed 2 weeks after surgery. Patients were advised to avoid hard and spicy food for 3 days following surgery. Systemic antibiotics (Amoxicillin 500 mg t.i.d. for 5 days) and analgesics (Ibuprufen 400 mg b.i.d. for 3 days) were prescribed. Patients were seen at 1 week and 1, 3, 6 and 12 months for post-operative follow-up [Figure 4]. After 4 weeks, the patients were instructed in mechanical plaque control of the treated tooth region using a soft bristled tooth brush and a roll technique.

Figure 4

Twelve months post-operative

Sample size

A priori power analysis was performed to determine that 12 patients and 24 sites was an adequate sample size to conduct the study. Significance level for rejection of the null hypothesis was set at α = 0.05.

Statistical analysis

All the clinical parameters recorded were subjected to the following statistical analysis: (1) Paired t-test for intragroup and (2) unpaired t test for intergroup comparisons were performed. Significance level for rejection of the null hypothesis was set at α = 0.05.

RESULTS

A statistically significant mean increase of PI at 6 and 12 months from baseline was recorded in both groups, with the SCTG group presenting statistically higher values than the PCG group. A statistically significant mean increase of GI was recorded in both groups at the 12 months follow-up. The difference between the groups was not significant.

There was a statistically highly significant reduction in the mean recession depth and gain in CAL for both groups at 6 and 12 months post-operatively. For the SCTG group, the mean recession depth reduced 2.33 ± 0.11 mm (84.73%) at 6 months and 2.21 ± 0.13 mm (80.36%) at 12 months from baseline; for the PCG group, the mean recession depth reduced 2.12 ± 0.05 mm (84.80%) at 6 months and 1.96 ± 0.02 mm (78.40%) at 12 months from baseline [Table 1]. A statistically highly significant mean reduction in CAL of 2.42 ± 0.21 mm for the SCTG group and 1.92 ± 0.16 mm for the PCG group at 12 months from baseline measurements was recorded. No statistically significant difference was observed between the groups. The mean percentage root coverage of 85 ± 15.23% at 6 months from baseline declined to 83 ± 14.5% at 12 months in the SCTG group and from 86 ± 17.29% at 6 months from baseline to 77 ± 18.42% at 12 months in the PCG group, showing a statistical significance (P < 0.05) between the 6- and 12-month follow-ups within the groups. No statistically significant difference was found between the groups [Table 2].

Table 1

Comparison of the midfacial (in mm) recession depths in Group A and Group B at different time intervals

Table 2

Comparison of percentage of root coverage at 6 months and 12 months in Exp A and B, and intergroup

A statistically highly significant gain of mean width of keratinized gingiva at 12 months was noticed in the SCTG group (2.63 ± 0.30 mm), whereas in the PCG group, a mean gain of 0.71 ± 0.04 mm was recorded (P < 0.005).

A statistically significant mean reduction in probing depth at 12 months was recorded in the SCTG group, while in the PCG group the mean probing depth remained unaltered.

On comparison of the post-surgical discomfort levels (PSDLs) between the two sites, the SCTG group presented with higher values at 1 week of follow-up and, by 1 month, there was complete reduction in the PSDLs in both the groups [Table 3].

Table 3

Comparison of PSDL in Group A and Group B at baseline, 1 week and 1 month by the unpaired t-test

On comparison of the aesthetic evaluation scores, the PCG group yielded a clinically better gingival texture and contour. No statistically significant difference could be detected in color match between the two groups.

DISCUSSION

The ultimate goal of periodontal therapy is the complete regeneration of periodontal-supporting tissue.[19] Over the years, a variety of periodontal plastic surgical approaches have been presented for the treatment of gingival recession defects. Chambrone, Sukakava, Aruajo, Pustiglioni, Chambrone under the Cochrane Collaboration in 2009, ascertained the superiority of SCTGs over the other periodontal plastic surgical approaches for root coverage.[20] In spite of its promising results, SCTG has some limitations. To overcome some of the drawbacks, PCG has been considered.

The results of this study demonstrated that both techniques, the autogenous SCTG or the PCG, covered by a coronally positioned flap, were effective in the treatment of shallow gingival recession defects (≥2 mm) with significant root coverage (87% and 80% for SCTG and PCG, respectively) and clinical attachment gain (2.42 ± 0.21 mm for the SCTG group and 1.92 ± 0.16 mm for the PCG group) at 12 months post-operatively. The difference between the two procedures in terms of recession reduction and attachment gain are not statistically significant. The SCTG procedure resulted in a statistically significant gain in width of keratinized gingiva when compared with the PCG group, while the PCG procedure resulted in less post-surgical discomfort and superior aesthetic outcomes.

The mean percentage root coverage with SCTG in the present study was 87%, which is in agreement with the results of the studies of Wang,[21] Jahanke et al.[22] and Cheung et al.[12] The significant amount of root coverage achieved is attributed to tensionless flap closure and adopting the suturing technique proposed by Zuchelli et al.[23] Optimal gingival thickness at the recession site, optimal donor tissue thickness and stringent post-surgical care were ensured.

In the present study, preparation of PRP was according to the “GONSHOR” proposed guidelines. It is documented that platelets begin to release their growth factors immediately, with almost 70% of the stored growth factors released within 10 min and 100% within the first hour of their activation. Hence, PCG is applied to the exposed root surface within this time.[2425] This could have accelerated the formation of an insoluble fibrin network, providing a scaffold for cell migration, proliferation and upregulation of collagen synthesis in extracellular matrix as per the healing model proposed by Wilderman and Wentz,[26] thereby presenting a consistent probing depth throughout the study.

In the present study, a statistically significant increase in width of keratinized gingiva in the SCTG group (1.50 ± 0.56 mm to 4.13 ± 0.86 mm) was seen, as with the other studies in which an effort to fully cover the graft were made. A shortcoming with PCG was the quick dissolution of the carrier and shrinkage of the graft, which in turn failed to support and stabilize the overlying flap. This problem was compensated by stabilizing the flap margin 1-2 mm coronal to the CEJ.

Although the present study obtained significant root coverage in both the groups, in agreement with the results of the studies of Cheung et al.,[12] the mean recession depth of these defects fall into the shallow recession category, which can contribute to the absence of a significant difference between the experimental groups. To the best of our knowledge, there has been no other study published where deeper recession defects have been treated with PCG. This could be one of the drawbacks of our study; hence, further studies need to be carried out.

The PSDL values were recorded by asking the patients to rate their PSDL on a visual analogue scale according to their subjective feelings. The difference in PSDL was judged to be statistically significant for the SCTG group (P = 0.002, P < 0.05) at 1 week follow-up, which can be attributed to the second surgical site in the SCTG group. An aesthetic evaluation was performed in the treated sites at 12 months of follow-up, where the PCG group presented superior aesthetics, especially in terms of contour and texture, when compared with the SCTG group, which might be attributed to accelerated early wound healing. In addition, thickness of tissue after surgery was more compatible with the adjacent tissue.

CONCLUSION

Within the limits of the study, both the PCG and the SCTG techniques resulted in a significant amount of root coverage. The PCG technique required less time and was less invasive, resulting in better aesthetic outcomes with lower PSDL values. Although the clinical findings following PCG use need to be corroborated with histological observations and more long-term studies need to be conducted, this technique shows promise in the treatment of recession defects.