A comparative clinical study of the efficacy of subepithelial connective tissue graft and acellular dermal matrix graft in root coverage: 6-month follow-up observation.

AIMS: The purpose of this study was to compare the clinical efficacy of subepithelial connective tissue graft and acellular dermal matrix graft associated with coronally repositioned flap in the treatment of Miller's class I and II gingival recession, 6 months postoperatively. SETTINGS AND
DESIGN: Ten patients with bilateral Miller's class I or class II gingival recession were randomly divided into two groups using a split-mouth study design.
MATERIALS AND METHODS: Group I (10 sites) was treated with subepithelial connective tissue graft along with coronally repositioned flap and Group II (10 sites) treated with acellular dermal matrix graft along with coronally repositioned flap. Clinical parameters like recession height and width, probing pocket depth, clinical attachment level, and width of keratinized gingiva were evaluated at baseline, 90(th) day, and 180(th) day for both groups. The percentage of root coverage was calculated based on the comparison of the recession height from 0 to 180(th) day in both Groups I and II. STATISTICAL ANALYSIS USED: Intragroup parameters at different time points were measured using the Wilcoxon signed rank test and Mann-Whitney U test was employed to analyze the differences between test and control groups.
RESULTS: There was no statistically significant difference in recession height and width, gain in CAL, and increase in the width of keratinized gingiva between the two groups on the 180(th) day. Both procedures showed clinically and statistically significant root coverage (Group I 96%, Group II 89.1%) on the 180(th) day.
CONCLUSIONS: The results indicate that coverage of denuded root with both subepithelial connective tissue autograft and acellular dermal matrix allograft are very predictable procedures, which were stable for 6 months postoperatively.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Gingival recession results in exposure of the root surface, loss of marginal tissue, and loss of attachment.[1] The ultimate goal of periodontal plastic surgery is the coverage of the exposed root surfaces when this condition is related to esthetic problems, dentinal hypersensitivity, root caries, or when it hampers with proper plaque removal.[2]

A variety of surgical techniques have been developed to attain root coverage, with the predictability of these procedures having improved with modifications. Among these procedures, the subepithelial connective tissue graft (SCTG) is considered as the gold standard because of its high predictability for root coverage, dual blood supply, and the resultant increase in the width of keratinized gingiva.[3] Although the SCTG achieves high rate of success and predictability, this procedure requires a second surgical site in order to harvest the tissue,[4] causing discomfort and the risk of bleeding.[5] Also, the longer surgical time, technique-sensitive results, presence of shallow palate with decreased connective tissue,[6] and limited amount of tissue that can be procured from the palate for treatment of multiple sites limit its application.[7] It has been shown that individuals with thin gingival tissues are more susceptible to the development of gingival recessions and often have thin palatal mucosa which can make it difficult or even impossible to harvest a connective tissue graft of adequate thickness.[5]

These limitations led to the search for an alternative method for root coverage. Klingsberg[8] used preserved sclera for coverage of denuded roots. Schoo and Coppes[9] tried duramater to obtain gain in the width of attached gingiva and coverage of the denuded root.

Freeze-dried skin graft has also been used for treatment of mucogingival defects and is also considered a substitute for gingival autografts.[10] The first case on the histologic study of freeze dried skin (FDS) allograft in the oral cavity was reported later in the 1980s.[11] Acellular dermal matrix is an aseptically prepared biocompatible graft material obtained from human donors by processing the dermis, removing the cells, and leaving behind a structurally intact connective tissue matrix composed of type I collagen. It is immunologically inert and lacks the major histocompatibility complex class I and II antigens required for antigenicity, rejection, inflammation, and the cellular elements required for viral transmission.[12] It has been used in periodontal plastic surgery since 1994 and has been demonstrated as effective as free gingival grafts in mucogingival surgeries.[13]

With the heightened interest in soft tissue regeneration, the clinician is in constant search for techniques that require minimal time and surgical dexterity while producing excellent results. The purpose of this study was to evaluate the effectiveness of an acellular dermal matrix allograft for root coverage and to compare it to an SCTG, when used in conjunction with coronally repositioned flap (CRF).

MATERIALS AND METHODS

The candidates for this study were selected from the patient pool of the Department of Periodontics. The power analysis was used to determine the minimum sample size required to differentiate the effect of treatment; a sample size of 20 was set for this study, based on an approximate value of 80% power that is required to reject the null hypothesis. A split-mouth study design was used where a total number of 20 sites among 10 patients aged 18-50 years (mean age 34 years), each contributing to one pair of Miller's class I and II buccal gingival recession in either maxilla or mandible, were selected. It was a double-blind study where one examiner measured the clinical parameters while the other performed the surgical procedure. The patients agreed to the study protocol and gave informed consent prior to treatment.

The inclusion criteria for the study were patients with Miller's class I and II recession, well-aligned teeth, presence and maintenance of good oral hygiene, and nonsmokers.

Patients with systemic diseases or those who have undergone periodontal surgery in the past 12 months, those with traumatic occlusion, and teeth with root caries were excluded from the study.

The patients were prepared for surgery with an initial phase of therapy which included oral prophylaxis, root planing, oral hygiene instructions, and occlusal adjustment.

In each patient, one of the two teeth with areas of gingival recession was randomly assigned to Group I (SCTG) and the contralateral site to Group II (acellular dermal matrix graft) using a coin toss method.

The following clinical measurements were taken by one examiner at the time of surgery and on the 90th and 180th days at the mid-buccal point of the involved tooth: (1) recession height (RH); (2) recession width (RW); (3) probing pocket depth (PD); (4) clinical attachment level (CAL); and (5) width of keratinized gingiva (WKG). The percentage of root coverage was calculated based on the comparison of the RH from 0 to 180th day in both Groups I and II.

Surgical procedure

All the surgical procedures were done by one operator. The same surgical procedure was used for both groups, except that Group I [Figure 1a] received the SCTG while Group II [Figure 2a] received the acellular dermal matrix graft.

Figure 1

Group I – (a) Preoperative view day 0; (b) Reflection of flap; (c) Procurement of connective tissue graft from the palate; (d) Harvested palatal connective tissue graft; (e) Placement of connective tissue graft; (f) Flap coronally positioned and sutured; (g) 6 Months post-op

Figure 2

Group II – (a) Preoperative view day 0; (b) Reflection of flap; (c) Basement membrane and connective tissue side of Alloderm®; (d) Placement of Alloderm®; (e) Flap coronally positioned and sutured; (f) 6 Months post-op

The surgical area was prepared with adequate anesthesia using 2% lignocaine HCl containing 1:100,000 epinephrine. A trapezoidal flap was designed using a primary horizontal incision made in the mesial and distal directions from the cementoenamel junction (CEJ) up to 1 mm of the proximal line angle of the adjacent teeth, leaving the interdental papilla intact. A sulcular incision was made connecting the primary incisions, preserving all the existing radicular gingiva and two diverging vertical incisions were made at each end of the primary incision, extending apically into the alveolar mucosa.

A full-thickness flap was raised up to the mucogingival junction with a No. 15 scalpel blade and a split-thickness flap was dissected mesially, distally, and apically by sharp dissection with a No. 11 scalpel blade. The flap was extended well beyond the mucogingival junction, so that it exhibited no tension when pulled coronally beyond the CEJ. The root was thoroughly planed and any convexities of the root were reduced using a rotary bur and saline irrigation. The intact papillae mesial and distal to the recession were de-epithelialized [Figure 1b and 2b].

In Group I, measurement of the approximate length and width of the autograft required was obtained with the use of a tin foil template. The connective tissue graft was harvested from the palate, following a “trap door” flap design. The harvested graft was trimmed to snugly fit the recipient bed preparation. The graft was then placed on the recipient bed and firm pressure was applied on the graft with a sterile moist gauze pack for 3-5 min to aid the graft to adapt and adhere to the recipient bed. The connective tissue graft was secured in position with 5-0 absorbable sutures [Figure 1c–e].

In Group II, the acellular dermal matrix graft (Alloderm) was aseptically rehydrated in the operating room for at least 10 min, as recommended by the manufacturers. The fully rehydrated graft was applied to the wound bed. Acellular dermal matrix graft (Alloderm) has a basement membrane side and connective tissue side [Figure 2c]. The acellular dermal matrix was oriented, so that the connective tissue side was placed adjacent to the defect. Firm pressure was applied on the graft with a sterile moist gauze pack for 3-5 min to help the graft adapt and adhere to the recipient wound bed. It was secured to the wound bed with 5-0 vicryl sutures [Figure 2d].

In both the groups, the previously reflected full-thickness flap was coronally positioned to cover the entire graft with very little tension on the flap and was secured with 4-0 black silk sutures using interrupted sling suture technique [Figures 1f and 2e].

The surgical area was protected and covered with non-eugenol dressing (Coe-pack; GC America Inc., Illinois, USA). All the patients were prescribed systemic antibiotic (Amoxycillin 500 mg, 3 times a day for 5 days) and analgesic (Ibuprofen 400 mg, 3 times a day for 3 days) with instructions to rinse the mouth twice daily with a solution of 0.2% chlorhexidine digluconate for 7 days after the surgery. Patients were also instructed not to brush over the periodontal pack and were recalled after 2 weeks for the suture and periodontal dressing removal.

At the time of suture removal, advanced healing was observed at both the recipient and donor sites in Group I; 3 out of 10 sites in Group II presented with exposure of the acellular dermal matrix graft along the margins. There was decreased root hypersensitivity and they resumed mechanical tooth cleaning of the treated areas using a soft toothbrush. The surgical sites were evaluated on follow-up visits postoperatively at 90th and 180th days. All the clinical parameters were again recorded and postoperative clinical photographs were taken [Figures 1g and 2f].

Statistical analyses

Quantitative data were recorded as mean and standard deviation. Differences in RH, RW, PD, CAL, and WKG values between 0 day (baseline), 90th day and 180th day post-surgery within each group were assessed by Wilcoxon signed rank test. Mann–Whitney U test was employed to analyze the differences between test and control groups in mean RH, RW, PD, CAL, and WKG. For all the statistical analyses, P = 0.05 was selected. Further testing was carried out using the multiple analysis of variance.

Calculation of % of root coverage

RESULTS

Both groups had similar-sized defects. There was no statistically significant difference in the mean preoperative gingival RH (Group I: 3.3 ± 0.7 mm, Group II: 3.2 ± 0.4 mm; P = 0.56), RW (Group I: 3.1 ± 0.3 mm, Group II: 3.1 ± 0.3 mm; P = 1.00), PD (Group I: 1.0 ± 0.0 mm, Group II: 1.0 ± 0.0 mm; P = 1.00), CAL (Group I: 4.3 ± 0.7 mm, Group II: 4.2 ± 0.4 mm; P = 0.56), and width of keratinized tissue (Group I: 3.3 ± 0.5 mm, Group II: 3.2 ± 0.4 mm, P = 0.66).

Tables 1 and 2 show the clinical data at baseline examination and after 90th and 180th days for Group I (SCTG) and Group II (acellular dermal matrix graft), respectively.

Table 1

Clinical results with subepithelial connective tissue graft (Group I)

Table 2

Clinical results with acellular dermal matrix graft (Group II)

When Group I and Group II were compared, Group I showed a significant change (P = 0.003) in RH to 0.0 ± 0.0 mm and RW to 0.0 ± 0.0 mm (P = 0.002) at 90th day when compared to Group II which showed a reduction to 0.3 ± 0.5 mm (P = 0.004) and 0.1 ± 0.3 mm (P = 0.003), respectively. However, when both groups were compared at 180th day, there was no statistically significant change in RH (P = 0.16) and RW (P = 0.32) between the two groups [Table 3].

Table 3

Comparison of surgical procedures

The percentage of mean root coverage obtained for Group I (SCTG + CRF) was 98%, whereas Group II (acellular dermal matrix graft + CRF) presented with 89.1% root coverage [Tables 4 and 5].

Table 4

Mean, standard deviation for recession height in sites treated with subepithelial connective tissue graft and coronally repositioned flap at different time intervals and percentage of root coverage at 180th day (Group I)

Table 5

Mean, standard deviation for recession height in sites treated with acellular dermal matrix graft and coronally repositioned flap at different time intervals and percentage of root coverage at 180th day (Group II)

When the groups were compared, Group I (0.9 ± 0.3 mm) showed a statistically significant gain in CAL at 90th day when compared to Group II (1.3 ± 0.5 mm), and there also was a statistically significant difference in the gain in CAL between the two groups at the end of 180th day (P = 0.02) [Table 3].

When Group I and Group II were compared, Group I (6.6 ± 0.7 mm) showed a statistically significant (P = 0.046) increase in WKG at 90th day when compared to Group II (6.1 ± 0.7 mm). However, when both groups were compared at 180th day for the gain in the WKG, there was no statistically significant difference (P = 0.16).

All the above results were confirmed using multiple analysis of variance to eliminate any form of errors during testing within and between the two groups [Table 6].

Table 6

Multiple analysis of variance for the parameters within and between Group I and Group II

DISCUSSION

In this study, we have attempted to compare the clinical efficacy of SCTG and acellular dermal matrix graft in the treatment of Miller's class I and II recession.

The percentage of mean root coverage obtained for Group I (SCTG + CRF) was 98%. These results are in accordance with those reported in other studies.[31415] In one of the patients who obtained only 80% of root coverage, the reason was found to be faulty tooth brushing habits. Controlled studies using connective tissue graft have reported mean root coverage between 65% and 98%.[1617]

The percentage of mean root coverage obtained for Group II (acellular dermal matrix graft + CRF) was 89.1%. The result of the present study is similar to the root coverage reported by Harris,[18] who obtained 89% root coverage with Alloderm, and Tal et al.,[19] who reported 89.1% root coverage when Alloderm was used with a coronally positioned flap. Another study showed mean root coverage of 97%, and out of 11 teeth treated with acellular dermal matrix, 9 teeth gained 100% coverage.[20]

In the present study, acellular dermal graft was well tolerated by the host periodontal tissue. Seven out of 10 sites showed complete root coverage (100%). In one of the patients, the needle nicked the overlying flap while suturing the graft, thereby resulting in a tear in the flap and exposure of the dermal matrix graft at the coronal aspect which resulted only in 50% root coverage. In the remaining two patients who did not attain complete root coverage, the acellular dermal matrix graft was exposed through the vertical incision, resulting in graft necrosis at the wound edges and limited root coverage.

When Group I and Group II were compared, Group I showed a significant change in RH (P = 0.003) and RW (P = 0.002) at 90th day when compared to Group II. However, when both groups were compared at 180th day, there was no statistically significant change in RH (P = 0.16) and RW (P = 0.32) between the two groups. Noveas et al.[21] also reported similar amount of recession reduction between the two groups in their 6-month study comparing SCTG and acellular dermal matrix graft.

Absence of significant change in probing depth is a very common finding reported in the studies on root coverage treatment. According to Waterman et al.,[22] this finding is probably due to the excellent level of gingival health pre- and post-surgery.

Clinically it was difficult to penetrate the sulcus with a probe. There was no bleeding on probing. These clinical findings are compatible with a healthy attachment. To discover the type of attachment that is formed, it would require the removal of a successfully treated tooth. This type of information generated from human histology is beyond the scope of this study.

Significant gain in CAL was observed in both the groups (P = 0.003). On comparison of the difference between the two groups, at 90th day, the difference in the gain in CAL between the two groups was statistically significant (P = 0.02) when compared to that at 180th day (P = 0.02). This finding is in accordance to the results obtained in various studies that have reported no statistically significant change in CAL in the group treated with SCTG when compared to the acellular dermal matrix graft group.[221]

Historically, the presence of an “adequate” zone of keratinized gingiva has been considered critical for the maintenance of gingival health. In 2005, Pini Prato[23] had stated that an increase in the WKG is a desired effect in decreasing the possibility of recurrence of gingival recessions.

Significant increase in WKG was observed in both the groups (P = 0.003). When Group I and Group II were compared, Group I showed a statistically significant (P = 0.003) increase in WKG at 90th day when compared to Group II (P = 0.004). However, when both groups were compared at 180th day for the increase in the WKG, there was no statistically significant difference (P = 0.16). Several studies have reported that a connective tissue graft contributes to the keratinization of the overlying epithelium.[2425] However, it is unknown exactly how an increase in the width of keratinized tissue occurs in recessions treated with acellular dermal matrix graft. Studies in which biopsy was obtained at the time of gingivoplasty showed that acellular dermal matrix was completely incorporated into the tissue, rather than being exfoliated or absorbed.[14]

This study must be interpreted with due consideration to the limitations such as the relatively small sample size (N = 10) and short evaluation period (6 months). A study sample using a larger sample size and a longer follow-up period is recommended to confirm the present findings.

CONCLUSIONS

We found that the most obvious advantage of acellular dermal matrix is that a second surgical area is avoided and the amount of material available is not limited, compared to the limited amount of connective tissue harvested from the palate, thus allowing the treatment of multiple defects. In the current era that focuses on minimally invasive techniques, the use of allograft contributed to a significant reduction in the patient morbidity and surgical risks. Despite the numerical differences, the result provided by acellular dermal matrix graft was somewhat similar to that provided by SCTG, which implies that in spite of its expense, it is a suitable material for root coverage.