Platelet rich fibrin in combination with bioabsorbable guided tissue regeneration (GTR) membrane and GTR membrane alone using double lateral sliding bridge flap for treatment of multiple gingival recession defects in humans: A randomized controlled clinical trail.

Background: Marginal tissue recession is a frequent clinical scenario that creates substantial compromise in esthetic appearance of the patient. The current randomized, double-blind interventional trial aims to evaluate the effectiveness of the combination of "platelet rich fibrin (PRF)" membrane with bioresorbable guided tissue regeneration (GTR) membrane as compared to GTR membrane alone utilizing "double lateral sliding bridge flap (DLSBF) technique" for the management of simultaneous GR defects in human subjects. Materials and
Methods: Twenty subjects were randomly allotted in two groups: Group 1 (test): 10 subjects treated with PRF + GTR membrane using DLSBF technique and Group 2 (control): 10 subjects treated with GTR membrane alone using DLSBF technique. Clinical measurements such as relative gingival marginal level, "relative clinical attachment level (R-CAL)," "probing pocket depth (PPD)," "gingival recession (GR)," and "width of keratinized gingiva (WKG) and gingival thickness (GT)" were evaluated at the initiation of the study and 6 months thereafter.
Results: Two groups showed statistically significant differences with respect to probing depth reduction, CAL gain, and increase in WKG and GT. No significant result was observed with mean root coverage (RC) and complete RC for test (84.80% ± 19.53% and 54.99% ± 38.53%) and control group (75.69% ± 18.86% and 35.83% ± 39.29%), respectively. Conclusions: The combination of PRF membrane used along with GTR membrane provides no additional benefits over GTR membrane alone. However, the DLSBF technique convincingly shows simultaneous elimination of multiple problems associated with GR, shallow vestibule, hypersensitivity, and aberrant frenum pull in a single stage with meticulous performance. Copyright:

INTRODUCTION

Many therapeutic challenges are faced by clinicians to treat gingival recession (GR). With increasing awareness about esthetics, numerous surgical treatment modalities have been devised to correct gingival deformities functionally and esthetically. Very often, the most coronal area of GR is the only visible part when smiling; therefore, even a presence of shallow GR postsurgery may be an esthetic concern to the individuals. Thus, the goal is to achieve “complete root coverage (CRC)” till “cementoenamel junction (CEJ)” when the individual complains about the esthetic appearance of the teeth.

Numerous surgical methods have been put forward in the past few years to attain CRC on multiple GR. The success of all proposed techniques varies considerably and is not always predictable. Although the connective tissue graft (CTG) provides excellent predictability and esthetics,[1] its use is limited when treating multiple GR at once. Various techniques and biomaterials have been used for the management of GR such as CTG,[2] “guided tissue regeneration (GTR) membrane,”[2] “enamel matrix derivative,”[3] “acellular dermal matrix allograft,”[4] and “platelet rich fibrin (PRF) membrane.”[5]

Thomas Oates et al.,[6] in their systematic review, focused on the outcome of surgical treatment for root coverage (RC) in subjects to GR in comparison with other treatment modes. The authors demonstrated that various surgical techniques effectively cover the root surfaces which are exposed and show improved patient-centered outcomes, including enhancement of soft tissue esthetics and reduced sensitivity of root. They also concluded that CTG has an advantage over GTR in terms of RC and width of keratinized tissue. They focused on the need for future studies to relate patient-oriented outcomes because most of the studies lack the standardization protocols for various outcomes in quantifying the data.

The use of barriers with the GTR technique was put forward by Tinti7 and Vincenzi. It was an effort to provide stable RC and regenerate new “periodontal ligament (PDL),” “alveolar bone,” and cementum covering the denuded root surface. It has been stated that the healing of periodontal defects using GTR membrane takes place by new tissue attachment rather than true regeneration of periodontium.[8] Hence, regeneration of periodontium with respect to GTR treatment procedure has been doubtful.[9] This suggests that there is a further requirement for technical development and increased literature in the arena of periodontal regenerative approach before such technique can be practiced widely.

PRF has been evaluated recently for RC procedures. It is an aggregate of platelet concentrates geared to simplified preparation. It simulates the microcirculatory system in general and releases GF that are essential for soft tissue healing and also serves as a resorbable membrane. Placing PRF membrane in GR defects regenerates components of gingiva on the labial aspect of upper and lower teeth and renews the functioning of keratinized gingiva.[10]

Marggraf[11] described the double lateral sliding bridge flap (DLSBF) procedure for RC in simultaneous teeth with or without adequate zone of “attached gingiva (AG).” Current procedure has been used for RC as a single-step approach for mucogingival deficiencies such as inadequate width of AG, shallow vestibule, and aberrant frenal pull. This technique is effective in eliminating GR problems, shallow vestibule, hypersensitivity, and aberrant frenum pull in a single stage with meticulous performance.[12] Flap covers the denuded surface of the root and provides plasmatic circulation from adjacent gingiva. Agarwal et al.,[10] in their study of DLSBF in conjunction with PRF in a collagen membrane carrier (GTR), yielded satisfactory results. The authors also stated that neither the amount of GR nor its quality of the supporting tissues is necessary for the better treatment outcomes of this method.

Therefore, the aim of the current double blinded, randomized clinical trial was to effectively evaluate the efficiency of “PRF membrane” when combined with bioabsorbable GTR membrane (BioMesh® polylactic acid (PLA), polyglycolic acid (PGA), and lactide/glycosides copolymer (PLGA), Sark Healthcare, Delhi, India) compared to GTR membrane alone along with DLSBF technique for the management of simultaneous GR defects in humans.

MATERIALS AND METHODS

The current randomized parallel designed, controlled interventional trial was conducted in 20 patients (10 male and 10 female) with GR chosen from the outpatient department of Periodontics from April 2019 to September 2020. This study design protocol was ethically passed by the “Institutional Ethical Committee.” All participants were informed verbally and written informed consent was obtained.

Healthy subjects without any systemic illness with at least 2 or more adjacent teeth with “Miller's Class I/II GR defects” on either arch's labial/buccal surfaces of the teeth which displayed GR depth ≥2 mm with minimum of 2 mm or more of width of keratinized gingiva (WKG) and no previous periodontal surgery in the past 6 months were included.

Subjects with poor oral hygiene following “etiotropic/phase I periodontal therapy” and exhibiting plaque score more than or equal to 1, mobile teeth, any systemic disease, suspected or known allergy to drugs or materials used in study, use of tobacco in any form, immunocompromised subjects, alcoholics, and lactating or pregnant women were excluded.

“For the calculation of sample size the formula used,

Where Zα/2 is the critical value of the normal distribution at a/2, Zβ is the critical value of normal distribution at β, σ is population standard deviation (SD), and d is the difference to be detected.”

Randomization of the sample used for this clinical study was done by a flip coin test with an equal number of subjects randomized to both groups [Chart 1]. Both the groups received DLSBF design with GTR + PRF membrane placed in test group, whereas only GTR membrane was placed in control group for obtaining RC.

Chart 1

Study flowchart

Initial periodontal therapy was performed in each patient consisting of nonsurgical periodontal therapy and individualized oral hygiene majors. In teeth with recession defects, the modified Stillman brushing technique was adjudged by the clinician with a correct prior demonstration to the patient to minimize the trauma associated with tooth brushing. Surgical management of the recession defects was not appointed until the patients’ plaque index was ≤1. All measurements were recorded by a single examiner prasad dhadse (PD). The clinical measurements were recorded 1 week prior to surgery and at the 6-month visit. “relative gingival marginal level (RGML), relative clinical attachment level (R-CAL), probing pocket depth (PPD), gingival recession (GR), WKG and gingival thickness (GT).”

A stent was prepared using acrylic the cast, which was prepared after taking an alginate impression. A reference slot was marked on the acrylic stent at mid-labial region of the involved tooth to achieve probe positioning which is reproducible. The lower margin of customized acryl stent was in a linear fashion, which served as a fixed reference mark. The UNC-15-calibrated periodontal probe (Gracey, Hu-Frriedy, Chicago, IL, USA) was placed in slot given on a customized stent, and the measurement was recorded from the lower margin of acrylic stent to the margin of gingiva corresponds to RGML. Then, the probe was held at the base of the pocket, and the distance till the lower border of the prefabricated stent was marked as R-CAL. PPD was recorded by deducting the RGML from R-CAL reading. WKG was recorded from the apical most portion of “mucogingival junction” to the margin of gingiva on mid labial aspect of experimental teeth. GR was calculated from the CEJ to the marginal gingiva. GT was calculated 3 mm apical to the margin of gingiva using an endodontic reamer with a rubber stopper and digital caliper.[1314]

RGML, PPD, R-CAL, GR, and WKG measurements were recorded at the mid-buccal portion of all teeth by UNC-15 probe to the nearest millimeter.[1314]

A single periodontist (KS) performed all surgeries. Sealed envelopes were used for allocation concealment, which served to prevent study participants from influencing treatment allocation for subjects. After infiltration of 2% local anesthesia (LA) (Lignox 2%, Indoco Remedies Ltd.) (1:80,000), the exposed root surfaces were planed using “powered-driven instruments” followed by curettes [Figures 1 and 2]. A semilunar or arch-shaped incision was given in the vestibule at an interval of two times of GR defect + 2 mm (2 × GR + 2 mm) [Figures 3 and 4].[15] This ensures a large flap with sufficient blood supply. A partial-thickness flap was mirrored and linked in the apico-coronal direction to communicate two flaps with one another. Patency of the elevation was checked with a periodontal probe [Figures 5 and 6]. To accomplish the estimated shape and dimension of the membrane, a sterilized aluminum foil was employed [Figures 7 and 8]. The bioabsorbable GTR membrane was trimmed to cover the root surface completely and extend at least 2 millimeters on all sides of the defect before being sutured in place with 4-0 resorbable sutures. The PRF membrane is placed on top of the bioabsorbable GTR membrane, which was placed on the root surfaces that were exposed [Figure 9]. The entire flap was put coronally and sutured to cover the membrane [Figures 10 and 11]. The comparison group's surgical approach was comparable to the test group, except that only a bioabsorbable GTR membrane was placed over the root's denuded surface [Figure 12].

Figure 1

Preoperative gingival recession seen with 44, 45, and 46 for test group

Figure 2

Preoperative gingival recession seen with 31, 32, 41, and 42 for control group

Figure 3

Incision line marking below the mucogingival junction in the test group

Figure 4

Incision line marking below the mucogingival junction in the control group

Figure 5

Elevation of double lateral sliding bridge flap

Figure 6

Elevation of double lateral sliding bridge flap

Figure 7

Defect measurements using a surgical template

Figure 8

Defect measurements using a surgical template

Figure 9

Guided tissue regeneration membrane sutured at the recipient site with underneath PRF membrane use covers the recession defect

Figure 10

Double lateral sliding bridge flap coronally positioned and sutured

Figure 11

Double lateral sliding bridge flap coronally positioned and sutured

Figure 12

Guided tissue regeneration membrane sutured at the recipient site covers the recession defect

Ten milliliter of blood was extracted from the antecubital vein, and samples were collected in sterile test tubes and centrifuged at 3000 rpm for 10 min. A fibrin clot developed in the center, and the remaining red blood cells were eliminated. The clot will be moved to the PRF box and crushed to obtain the PRF membrane.[16]

Postoperatively, periodontal pack (Coe-Pak, GC, America Inc., Chicago, IL, USA) was given on the treated site [Figures 13 and 14]. Analgesics (Zerodol-SP, ICPA Laboratories, Ltd.) and antibiotics (Almox-500, Alkem Laboratories Ltd.) were advised after surgery for 5 days. Subjects were asked to avoid brushing over the operated site for the first 3 weeks and to rinse with “chlorhexidine gluconate” (Hexidine, ICPA Lab, India) two times for 2 weeks. Subjects were also advised to avoid undue trauma and not to disturb the pack in the operated sites. The periodontal pack was removed after 1 week of surgery, and the healing was observed. If necessary, the second periodontal pack was placed. Suture removal was done after 14 days. Subjects were trained to clean the operated site with the cotton dipped in chlorhexidine gluconate solution (Hexidine, ICPA Lab, India) for 7 days in an “apico-coronal direction” and brushing with a soft toothbrush with previously demonstrated Charter's technique. The subjects were re-evaluated at 1, 3, and 6 months after surgery. Oral prophylaxis was done at re-evaluation visit. All clinical measurements were re-recorded 6 months postoperatively [Figures 15 and 16].

Figure 13

Periodontal pack placed

Figure 14

Periodontal pack placed

Figure 15

Postoperative 6-month follow-up for test group

Figure 16

Postoperative 6 months follow-up for control group

The “mean and standard deviation” (Mean ± SD) values for all clinical measurements were calculated. The mean data were evaluated by applying statistical methods for estimating statistical significance. Kolmogorov–Smirnov test was done for normality of data distribution. For comparison of data in each group from baseline to 6 months, Student's paired t-test was used, while student's unpaired t-test was used for comparing between the groups. The level of significance was set at P < 0.05.

RESULTS

20 systemically healthy patients with a mean age 33.85 ± 8.27 (age range: 18–50 years) presenting with 49 buccal/labial GR defects (25 defects in test group and 24 defects in the control group). There was statistically significant reduction in full mouth plaque index (FMPI) and full mouth papillary bleeding index (FMPBI) at 6 months compared to baseline value. Clinical parameters such as RGML, R-CAL, PPD, WKG and GT have been found to be statistically significant in test group compared to control group.” However, there was no significant difference in mean RC and CRC in test and control groups. The baseline and 6-month values of the clinical parameters are summarized in Tables 1-5.

Table 1

Mean full-mouth plaque index scores and mean full-mouth papillary bleeding index scores at baseline and 6-month follow-up in test and control groups (mean±standard deviation in mm)

Parameters	Groups	Baseline	6 months	Difference	P
FMPI	Test	0.67±0.96	0.40±0.15	0.27±0.81	0.003*
	Control	0.69±0.16	0.39±0.12	0.30±0.04	0.003*
FMPBI	Test	0.59±0.22	0.31±0.08	0.28±0.14	0.012*
	Control	0.57±0.15	0.33±0.10	0.24±0.05	0.011*

*Statistical significance set at P<0.05. FMPI – Full-mouth plaque index; FMPBI – Full mouth papillary bleeding index; P – Probability value

Table 5

Comparison of mean percentage of root coverage corresponding to mean reduction in gingival recession between test and control groups (mean±standard deviation in mm)

Clinical parameters	Test group	Control group	Difference	P
GR reduction	2.68±0.74	2.16±0.38	0.52±0.77	0.003*
Mean root coverage in %	84.80±19.53	75.69±18.86	9.30±28.85	0.10
Complete root coverage (%)	54.99±38.53	35.83±39.29	19.19±62.39	0.35

*Statistical significance set at P<0.05. GR – Gingival recession; P – Probability value

DISCUSSION

The aim of our study was to evaluate the effectiveness of PRF membrane in combination with bioabsorbable GTR membrane compared to GTR membrane alone with DLSBF technique for the management of multiple GR defects.

Postsurgically, no sign of infection or any other problem was noticed in any subject after using PRF membrane and GTR membrane, which indicated that both procedures were well tolerated by the subject. In the present investigation, all the treated subjects were generally satisfied with both the treatment modalities.

Each subject included in the study demonstrated good oral hygiene and gingival status throughout the study period, as shown by FMPI and FMPBI scores. At baseline, the FMPI and FMPBI scores were low and remained low (<1) throughout the 6-month study period. This was the result of frequent instructions on oral hygiene given to subjects throughout the period as well as a regular supportive periodontal care program.[17] Numerous short-term studies[1819] and long-term evidence[20] suggest that good oral hygiene was correlated with the stability of clinical attachment gain as indicated by low plaque score. Numerous studies have stated the significance of GTR membrane in the management of GR. Systematic reviews put forward by Oates et al.[6] and Roccuzzo et al.[21] found that RC with GTR membrane demonstrated significant outcomes.

A new innovative idea is the use of PRF, found in platelets as concentrated GFs. Placing the PRF membrane in GR defects regenerate functioning of gingiva on the labial aspect of maxillary and mandibular teeth, as it is known to release the GFs till 23 days[22] and additionally helps in renewing the continuum of keratinized gingiva.[10]

Marggraf[11] showed CRC in 54.4% of teeth 2 years postsurgery and 30% showed CRC after 5 years using the DLSBF. The results of our study showed a remarkable gain in clinical parameters at 6 months in both groups. Significant GR reduction was observed at 6 months in both the treated groups.

The altruistic goal of periodontal therapy has long been the recovery of damaged periodontal tissues due to GR. The use of autologous blood derivatives (PRP/PRF) in periodontal defects for periodontal regeneration in recent years aims to develop a new and more effective approach for periodontal regeneration in RC procedures with decreased patient morbidity and less postoperative patient complications. The current study was therefore performed to assess the effectiveness of PRF + GTR membrane to manage multiple GR defects in order to achieve RC. In the test group, at 6 months postsurgery, a statistically significant decrease in mean recession defects was observed compared to the baseline. The mean GR in the test group decreased from 3.28 ± 0.97 mm to 0.60 ± 0.76 mm at 6 months, which corresponds to a mean RC of 84.80% and showed CRC of 14 out of 25 recession defects treated (54.99%).

The observation of a single case report utilizing DLSBF technique using PRF and GTR corresponds to CRC and stable gingival margin at 6 months.[10] Moreover, there is a lack of clinical data in the same line of using the said surgical procedure and biomaterials for RC. Therefore, the results of the current study were compared with the studies related to individual use of PRF membrane alone and GTR membrane alone for the management of multiple GR defects. The findings of Rajaram et al.[23] and Nair et al.[24] studies fall in line with the results achieved in the test group of our study.

The mean recession defect depth in the control group was reduced from 3 mm to 0.83 mm at 6 months postsurgery, which correlates to a mean 75.69% recession defect coverage. Eight out of 24 (35.83%) treated recession defects showed CRC. The result of this study for the use of GTR membrane alone using DLSBF technique to treat multiple GR can be compared with the study by Zanwar et al.,[25] Trivedi et al.,[26] and Narang and Gupta[27] who observed similar mean RC.

In the current study, mean CAL gain after 6 months was 5.24 ± 0.87 mm in test and 3.83 ± 0.20 mm in control group, which was found to be significantly higher in test group. The type of healing obtained in test group (PRF + GTR membrane) can only be speculated on since no histological studies are available due to ethical considerations. Based on the histological evidence, Fujita et al.[28] observed that despite the placement of membrane over the defect, resorption was seen. This indicates that such resorption of large defects is a natural step in healing process, irrespective of denudation or bacterial contamination. They assumed that GTR induces PDL cell accumulation with a new formation of cemental layer over such typical resorption by Frank et al.[29] that resorption leads to deposition of cementum. Mufti et al.,[30] in their study, detected that PRF membrane has an extremely elevated density of fibrin fibers. The high-density fibers provide additional stability of the wounds and promote angiogenesis. Moreover, the concentrated PDGF, VEGF, and TGF, which are the main GFs, accelerate healing of soft tissue by matrix biosynthesis and angiogenesis throughout the wound healing period.

PPD reduction limits the risk of local reinfection, which is the ultimate aim of periodontal treatment. Deep pockets are the risk indicators for the progression of periodontal disease, whereas shallow pockets have negative effects. In the current study, both groups showed statistically significant mean PPD reduction of 1.4 mm and 1 mm at 6 months. Similar findings have been described in the literature by other authors. Nickles et al.[31] used bioresorbable membrane for the management of GR and observed 1.6 mm of PPD reduction at 6 months after surgery. Vandana and Sikri[32] evaluated the efficacy of PLA/PGA membrane for the management of human buccal GR and observed PPD reduction of 1 mm was seen at 6 months postoperatively.

The mean WKG in both experiment and control group at 6 months was significantly increased in the present study. Tatakis and Trombelli[33] and Oncu E[34] found similar results in their study. An increased amount of KTW is known to provide long-term stability of the results.[3334]

Recent studies have highlighted the importance of GT for describing or achieving RC and clinical outcome stability. In the present study, GT increased statistically in both test and control groups with relatively more increase in the test group. This increase might be because of the spacing effect of the PRF membrane or the influence of GFs on the proliferation of gingival and PDL fibroblasts. Thamaraiselvan et al.[35] and Oncu E[34] reported increased GT value in the PRF group. It should not be forgotten that the initial flap thickness and type of dissection affect microcirculation of the connective tissue. In addition, PRF interpositioning can limit collateral circulation, which is essential for revascularization and healing.

Some technical aspects are represented during DLSBF technique which were key to its success. An initial arch-shaped incision was given at 2 × GR + 2 mm apical to GR and this provided a wide flap. Furthermore, with the DLSBF procedure, the incidence of the recurrent GR is reduced significantly along with deepening of vestibule, as the mucosal flap cannot be influenced by tension from an apical direction.

In terms of RC, there were statistically nonsignificant differences between the two groups, but all other clinical parameters, such as PPD, CAL, REC, WKG, and GT, indicated statistically significant variations for the therapy of numerous GR abnormalities. The application of PRF showed additional benefit to enhance outcomes achieved by DLSBF+GTR alone. This could be due to the good results in groups, the small sample size, and defects (Miller's Class I and II) that are known to cause predictable RC. The findings are comparable to Del Fabbro et al.'s meta-analysis.[36] who stated that there was no significant benefit of platelet concentrates for the management of GR.

The definitive benefit of PRF in the test group of the current study does not rule out the interest of PRF in mucogingival surgery for exposed root surfaces. Surgical variables that may affect the final result are PRF consistency, relationship with a CEJ positioning, and platelet concentration, as said by Marx et al.[37]

The quality of the supporting tissue and the amount of GR used in this investigation had no effect on the technique's performance. The transposed alveolar mucosa may be to blame for the increased connected gingiva. Bokan[38] in their research, showed that inductive cues from the underlying tissues caused the growth of keratinized epithelium in previously nonkeratinized mucosa. The influence of PRF membrane growth factors on the proliferation of gingival and PDL fibroblasts, or a spacing effect of PRF membrane, could explain the rise in gingiva thickness. For the evaluation of periodontal therapy, a period of 6 months may be considered too short, especially in dealing with barrier techniques and biomaterials for periodontal regeneration. However, Yukna et al.[39] recorded no real change in periodontal regeneration observed and compared at 6 month and 3 year re-entry period.

CONCLUSIONS

Within the limits of the present study, a combination of PRF membrane used along with GTR membrane provides no additional benefits over GTR membrane alone. However, the DLSBF technique convincingly shows simultaneous elimination of multiple problems associated with GR, shallow vestibule, hypersensitivity, and aberrant frenum pull in a single stage with meticulous performance ensuring stability of the results achieved.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 2

Comparison of clinical parameters at baseline and 6-month follow-up in test group (mean±standard deviation in mm)

Clinical parameters	Baseline	6 months	Difference	P
RGML	8.20±0.86	3.76±0.66	4.44±0.65	<0.001*
R-CAL	10.32±0.85	5.08±0.81	5.24±0.85	<0.001*
PPD	2.52±0.50	1.12±0.33	1.40±0.5	<0.001*
WKG	3.68±0.98	6.28±0.93	2.60±0.76	<0.001*
GT	0.56±0.04	1.29±0.13	0.71±0.14	<0.001*
GR	3.28±0.97	0.60±0.76	2.68±0.74	<0.001*

*Statistical significance set at P<0.05. RGML – Relative gingival marginal level; R-CAL – Relative clinical attachment level; PPD – Probing pocket depth; WKG – Width of keratinized gingiva; GT – Gingival thickness; GR – Gingival recession; P – Probability value

Table 3

Comparison of clinical parameters at baseline and 6-month follow-up in control group (mean±standard deviation in mm)

Clinical parameters	Baseline	6 months	Difference	P
RGML	7.83±0.81	4.87±0.99	2.96±0.75	<0.001*
R-CAL	10.20±0.93	6.37±0.92	3.83±0.20	<0.001*
PPD	2.50±0.51	1.50±0.51	1.00±0.41	<0.001*
WKG	3.29±0.46	5.29±0.46	2±0.58	<0.001*
GT	0.63±0.05	1.18±0.20	0.55±0.20	<0.001*
GR	3.00±0.72	0.83±0.70	2.16±0.38	<0.001*

*Statistical significance set at P<0.05. RGML – Relative gingival marginal level; R-CAL – Relative clinical attachment level; PPD – Probing pocket depth; WKG – Width of keratinized gingiva; GT – Gingival thickness; GR – Gingival recession; P – Probability value

Table 4

Comparison of clinical parameters between test and control groups at 6-month follow-up (mean±standard deviation in mm)

Clinical parameters	Test group	Control group	Difference	P
RGML reduction	4.44±0.65	2.96±0.75	1.48±1.00	<0.001*
R-CAL gain	5.24±0.87	3.83±0.20	1.41±0.32	<0.001*
PPD reduction	1.40±0.50	1.00±0.41	0.40±0.70	0.03*
WKG increase	2.60±0.76	2.00±0.58	0.6±0.95	0.03*
GT change	0.71±0.14	0.55±0.20	0.16±0.25	0.03*
GR reduction	2.68±0.74	2.16±0.38	0.52±0.77	0.03*

*Statistical significance set at P<0.05. RGML – Relative gingival marginal level; R-CAL – Relative clinical attachment level; PPD – Probing pocket depth; WKG – Width of keratinized gingiva; GT – Gingival thickness; GR – Gingival recession; P – Probability value