TITLE: Coronally positioned flap with or without acellular dermal matrix graft in the treatment of class II gingival recession defects: A randomized controlled clinical study

  ABSTRACT:
The aim of the randomized controlled single blind study is to evaluate the treatment of Miller's class II gingival recessions by coronally positioned flap (CPF) with or without acellular dermal matrix allograft (ADMA). Ten patients with 20 sites with maxillary bilateral Miller's class II facial recession defects were selected randomly into two groups of test (ADMA+CPF) and control (CPF alone) group with each group having 10 recession defects to be treated. The clinical parameters included plaque index (PI), gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), recession height (RH), recession width (RW), height of the keratinized tissue (HKT), and thickness of the keratinized tissue (TKT). These measurements were recorded at baseline and after 6 months post-surgery. Statistical analysis was made by the paired "t" test for intragroup and intergroup comparison was done by the unpaired "t" test. The percentage of root coverage for both the experimental and control groups were 82.2% and 50%, respectively. The changes from baseline to 6 months were significant in both the groups for PD, CAL, and RH; however, for parameters such as RW, HKT, and TKT significance was seen only in the experimental group. On comparison between two groups, only TKT showed statistically significance. It can be concluded that the amount of root coverage obtained with ADMA + CPF was superior compared to CPF alone.

BODY.INTRODUCTION:
Root coverage procedures are usually indicated to achieve better esthetics.[12] Although several techniques have been proposed to achieve consistent and predictable root coverage, by some estimates, the average percentage of covered root surfaces resulting from different procedures performed under varying clinical conditions varies from 56% to 97.8%.[3–6] Thus, treatment of buccal recession remains a major challenge to clinicians.[6]  Many different surgical procedures have been used to achieve root coverage which include pedicle grafts (lateral sliding or double papillae) with or without connective tissue grafts, epithelialized autogenous grafts (free gingival), connective tissue grafts, coronally positioned flaps (CPF) alone, CPF preceded by a free gingival graft, and CPF with a simultaneous connective tissue graft. Each of these techniques results in varying degrees of success and offers a variety of treatments for such defects.[3]  The use of subepithelial connective tissue graft (SCTG) covered by a CPF has shown good predictability.[2] However, it involves a certain degree of discomfort for the patient because of two surgical sites (palatal donor and recepient sites). A study evaluated the treatment of localized gingival recession by CPF (test) with or without an SCTG (control). The mean root coverage was 98.9% in the test group and 97.1% in the control group. It was concluded that the two surgical procedures could provide efficient root coverage.[7]  Recently, an acellular dermal matrix allograft (ADMA) has been used as a substitute for the keratinized tissue (KT) around teeth for the treatment of alveolar ridge deformities and for the root coverage procedures. In vitro and clinical studies suggested that ADMA is an acellular, non-immunogenic scaffold that heals by repopulation and revascularization, rather than through a granulation process.[2] Previous studies compared the results obtained with ADMA and the SCTG for the treatment of gingival recessions. None of them showed any significant differences in recession reduction between the procedures. However, a study has shown that the SCTG produced a greater mean probing reduction and mean keratinized tissue increase than the ADMA.[28]  Hence, the aim of the present study was to clinically evaluate the treatment of gingival recessions (Miller class II) by coronally positioned flap (CPF) with or without acellular dermal matrix allograft (ADMA).

BODY.MATERIALS AND METHODS:
The patients for the clinical trial were selected from Department of Periodontics, College of Dental Sciences, Davangere, Karnataka. Both the sexes were included in the study satisfying the following criteria. Informed consent was taken from all the patients after explaining the procedure and the ethical clearance was obtained from the ethical committee of College of Dental Sciences, Davangere, Karnataka, India. Ten patients with 20 recession defects (buccal/labial), five males and six females, ranging from 20 to 55 years of age (mean age 37 years) with a comparable bilateral class II gingival recession in maxillary anteriors and premolars in each patient were included in this study. The control group consisted of sites treated with CPF alone and the test group consisted of sites treated with ADMA and CPF.  The patients were consecutively selected from the out-patient department (OPD) of Periodontics, College of Dental Sciences, who visited the department with the complaint of gingival recession at the sites selected for the study. These patients desired for improved esthetics and demanded root coverage procedures.  All the patients were in good general health with no contraindication for periodontal surgery. All the patients had recession of 2 mm or greater. There was soft tissue coronal to the cementoenamel junction (CEJ) in the interproximal regions. All the teeth were vital because none had been treated endodontically and all were asymptomatic and the sites to be treated had no caries or restoration, smokers were excluded from the study.  Initial therapy included oral hygiene instructions and scaling and root planning. Every effort was made to modify habits that may have contributed to the recession defects. No occlusal therapy was performed in any case as occlusal analysis was within normal limits in all cases included in the study.  Initial photographs were taken and clinical findings were recorded. The measurements included recession height (RH)---measured from cementoenamel junction (CEJ) to free gingival margin; recession width (RW)---measured mesiodistally at the CEJ level; probing depth (PD)---measured from gingival margin to the base of the defect; clinical attachment level (CAL)---calculated as RH + probing depth; height of the keratinized tissue (HKT)---measured from the distance between the most apical point of the gingival margin (GM) and the mucogingival junction (MGJ);[2] thickness of keratinized tissue (TKT)[9] is measured at midpoint location between gingival margin and mucogingival junction, using periodontal probe After anesthetizing, the straight probe was pierced perpendicularly to the mucosal surface, through the soft tissue until a hard surface was felt. Later the straight probe was replaced by graduated periodontal probe (Williams probe) until hard surface was felt and recordings were made and rounded off to the nearest millimeters.  The surgical procedure used was the same for the both groups, except that the control group was treated with CPF and the test group was treated with CPF and ADMA. After obtaining anesthesia, the exposed root surface was planed to eliminate soft tooth structure, undercuts, ridges, plaque, and calculus. The root biomodification was done with a tetracycline solution (125 mg tetracycline/ml of saline).[8] The solution was burnished onto the root surface with cotton pledgets for 3 min. The area was then rinsed with water by a 3-way syringe and dried. The resulting surface appeared frosted. Horizontal incisions were made, starting at the CEJ of the adjoining teeth. Next sulcular incisions were made to connect the horizontal incisions. The incisions were extended mesially and distally as far as necessary to permit coronally positioning a pedicle graft over the defects. Two oblique vertical incisions were extended beyond the MGJ and a trapezoidal mucoperiosteal flap was raised up to MGJ. After this point, a spit thickness flap was extended apically, to release the tension and favor the coronal positioning of the flap. The epithelium on the mesial and distal papillae was scraped to create a bleeding surface for a recipient bed [Figures 1–4].  Figure 1Preoperative view of maxillary left first premolars  Figure 2Incisions are made  Figure 3Reflection of partial thickness flap  Figure 4Root biomodification is done and recipient bed is prepared  In the test group, an acellular dermal matrix allograft was adapted after being aseptically rehydrated in sterile saline, according to manufacturer's instruction. A template is prepared and the graft was trimmed to a shape and size of template designed to cover the root surface and the adjacent surrounding bone. The basement membrane side was placed adjacent to bone and tooth and connective tissue side was placed facing the flap. The coronal lateral borders of ADM were sutured with sling sutures using resorbable sutures (Ethicon 4-0) [Figures 5 and 6]. The flap was coronally positioned and sutured to completely cover the allograft and protected with a non-eugenol dressing. In the control group, the surgical procedures were similar except for the placement of graft.  Figure 5Alloderm is sutured over the defect  Figure 6Flap is sutured completely covering alloderm  Routine post-operative instructions were given to both groups. All patients were seen 2, 4, 8, 12 and 24 weeks post-operative. At 2 weeks post-operative, the dressings were removed. At all post-operative appointments, the areas were polished and deplaqued. Oral hygiene was stressed at all appointments. Patients were instructed to clean the area with a soft brush. Flossing was not restarted in area until 8-12 weeks post-operative. At that point, patients were returned to normal brushing. At 24 weeks post-operative, the final clinical measurements were recorded [Figure 7]. These were the same measurements that were recorded pre-operatively.  Figure 7Postoperative view after 24 weeks  Statistical analysis was performed. Changes in the vertical and horizontal dimensions in both experimental and control groups were analyzed by intragroup comparisons by the paired "t" test and intergroup comparisons by the unpaired "t" test. The results were also ascertained by nonparametric methods like Wilcoxon's test and Mann-Whitney test whenever measurements were found to be non-normal. A P-value of 0.05 or less was considered for statistical significance. The results were presented as mean ± standard deviation (SD) for all the parameters.

BODY.RESULTS:
Both groups were made of comparable sized defects. Pre- and post-operative changes and comparison between test and control groups are summarized in [Table 1].   Table 1 Pre- and post-operative changes and comparison between test and control groups   There was statistical significant reduction in PD, RH, RW and an increase in CAL gain, HKT, and TKT for the test group. For the control group statistically significant reduction was seen only in relation to PD, RH and an increase in CAL gain where as RW, HKT, TKT were statistically not significant. However, on comparison between the test and control group, only TKT parameter showed statistically significant result, indicating that acellular dermal matrix has significantly contributed to the thickness in the test group.  The test group has mean root coverage of 82.2% and the control group has 53% and the difference was found to be statistically significant. The predictability of root coverage in both test and control groups was 80% and 50%, respectively [Table 2].  Table 2 Comparison of percentage root coverage (%) and predictability in both experimental and control groups 

BODY.DISCUSSION:
It has been accepted that complete root coverage can be achieved in class II gingival recessions.[2] The present study included Miller's class II gingival recessions. This type of defect could be treated with many variations of three basic approaches; (1) pedicle soft tissue grafts; (2) free soft tissue grafts; and (3) combinations of the two. Among the pedicle grafts, the CPF is one of the valid surgical options to cover exposed root surfaces. It has many advantages over other surgical procedures used to treat the gingival recessions: it does not require a separate surgical site to obtain a graft, the tissue of the pedicle provides a perfect color/contour match with the surrounding tissue, the procedure is simple to perform, and does not require extended surgical or recovery time.[10] The association of autogenous connective tissue graft with the CPF is also considered predictable; however, the second surgical site necessary to harvest the autogenous palatal donor tissue is a serious disadvantage due to increased risk of pain and post-operative hemorrhage. Therefore, an ADMA has been used as an alternative source of donor tissue. The material provides an unlimited supply of graft material that could be particularly helpful when treating multiple recession sites.[11] The present study compared treatment of class II gingival recessions by coronally positioned flap (CPF) with or without acellular dermal matrix allograft (ADMA). The experimental design included two treatment groups that differed only by the presence of allograft allowing the evaluation of the influence of the graft in the clinical results. The graft was oriented with the basement membrane toward the root surface based in previous reports showing that the orientation of the material did not affect the treatment outcome.[1112]  In both the groups statistically significant results was obtained with PD, CAL, and RH parameters; however, between the groups statistical significance was not seen. These results are in correlation with the studies done by various authors.[213–15] These clinical changes probably represent a combination of new connective tissue attachment in the apical half of the defect and the presence of a long junctional epithelium attachment in the coronal half. However, these changes are probably not large enough to be detected or considered important in most clinical situations. It seems more important that in all cases the final results were esthetically pleasing, functionally adequate, and had a healthy sulcus.  The RW and HKT were statistically significant only in test and results between the groups for these parameters were not statistically significant. This correlated with the studies done by many authors.[216] The possible effect of ADM in increasing the amount of keratinized gingiva is not clear. However, it is not known why an increase in the amount of keratinized tissue would occur in defects treated with the acellular dermal matrix. The cellular dynamics need to be studied.  The gain in the thickness of KT is worth noting. The TKT is measured using transgingival probing, as this method was found to be more reliable, cost effective, and compatible at chair side.[9] The increase in the TKT was statistically significant only in the test group and comparison between groups was also statistically significant. These results are in correlation with the studies done by several authors.[211131516] The increase in the thickness might be due to integration of the ADMA graft membrane with the overlying flap. The role of collagen membranes cannot be underestimated or overlooked because collagen membranes can increase tissue thickness via membrane integration.[13] A histologic study of ADMA-treated areas showed the presence of elastin fibers which implies that the ADMA was incorporated into the tissue, rather than being exfoliated or absorbed. Elastin fibers are found in skin and in an ADMA, but not in gingival and oral mucosa. Therefore, the elastin fibers serve as a good marker for the ADMA.[8]  A statistically significant root coverage (82.2%) and predictability (80%) associated with the ADM group might be due to the presence of collagen, which forms a major portion of the ADM graft extracellular matrix. It was found that collagen stimulates platelet attachment, enhances fibrin linkage, and is chemotactic for fibroblasts. It also inhibits the apical migration of epithelium, allowing undifferentiated mesenchymal cells to repopulate the space and promote regeneration resulting in a stable attachment of the covering flap to the previously denuded root surface, thus preventing "subsidence of epithelium." During healing period, the ADM graft might have acted as a shock absorber, deflecting the undue forces that otherwise would be transmitted to the fragile maturing fibrin clot on the root surface. ADM graft facilitates better tissue maturation, resulting in long-term root coverage.[14]

BODY.CONCLUSION:
ADM allograft was found to be a biocompatible, non-allergenic, and did not produce any inflammatory response. From the clinician's point of view, the ADM graft eliminates donor site morbidity, offers unlimited tissue availability, and reduces multiple surgeries. Clinically, the handling, trimming, adapting, and suturing of the graft is simple and convenient, and it is significantly superior in effectiveness and efficiency in the treatment of gingival recession compared to CPF alone. It may also provide as a useful substitute for connective tissue graft procedures for root coverage.

Question: Compared to coronally positioned flap (CPF) without acellular dermal matrix allograft (ADMA). what was the result of coronally positioned flap (CPF) with acellular dermal matrix allograft (ADMA). on thickness of the keratinized tissue (TKT)?
Evidence: However, on comparison between the test and control group, only TKT parameter showed statistically significant result, indicating that acellular dermal matrix has significantly contributed to the thickness in the test group.
Answer: significantly increased