Successful management of gingival recession with interdental attachment loss using gingival unit grafts.

Background: Gingival recession leads to root surface exposure devoid of periodontal attachment. Recession defects with interdental attachment loss (RT2, RT3), further increase the avascular area which is critical for survival of soft-tissue grafts. Nonsubmerged grafts such as free gingival grafts and gingival unit grafts (GUGs) rely primarily on plasmatic circulation from the recipient area during the initial stages of healing for its survival.
Methods: Nineteen isolated RT2 recession defects, in the mandibular anterior region, were treated using GUG. The clinical parameters of recession depth (RD), recession width (RW), interdental clinical attachment levels (iCAL) were measured at baseline. Percentage of mean root coverage (MRC) was calculated at 3 months and 6 months.
Results: The percentage of mean root coverage (MRC) achieved at the end of 6 months was 81.79% ± 6.16%. Further, Simple linear regression analysis to predict MRC at 6 months using baseline RW revealed, for every 1 mm decrease in RW, the percentage of root coverage significantly increased by 5.25% (P = 0.04).
Conclusion: GUG can be used as an alternative treatment modality to achieve successful root coverage in RT2 recession defects. Baseline RW can be used to predict the outcome of root coverage at the end of 6 months. Copyright:

INTRODUCTION

Gingival recession causing apical shift in the position of marginal gingiva, leads to exposure of one or more surfaces of the tooth. The dimensions of avascular root surface devoid of its periodontal attachment is one of the most important baseline defect characteristics affecting the outcome of any root coverage procedure.[1] This gains significance when attempting to cover denuded root surfaces using nonsubmerged soft-tissue grafts such as free gingival grafts (FGGs) or gingival unit grafts (GUGs), as the success and survival of these grafts primarily rely on diffusion of blood from the recipient connective tissue bed.[2]

Miller's classification of marginal tissue recession, stated that complete root coverage (CRC) cannot be achieved in sites with inter-dental bone loss (Miller's class 3 and class 4 recession defects).[3] Among the numerous classifications proposed to overcome the limitations of Miller's classification, the recession type (RT) classification system proposed by Cairo et al. addresses the interdental clinical attachment level (iCAL) more prominently.[4] This classification takes into consideration, the amount of midbuccal attachment loss respective to the amount of interproximal attachment loss. The sites with interdental attachment loss are classified under RT2 or RT3, segregating them as defects associated with periodontal disease.

GUG, first proposed by Allen in 2004,[5] is a modification of FGG, wherein the harvested graft includes the palatal marginal gingiva and interdental papilla. The graft is considered more “site specific” in terms of its anatomy and function and may have increased potential for survival in recipient areas where the blood supply is less than optimal.[5]

The efficacy of GUG has been compared with FGG in few randomized controlled trials in both split-mouth and parallel-design models.[678] In all the comparative studies, GUG has been proved to exhibit better clinical results in terms of recession coverage and keratinized tissue gain, as well as shows better esthetics than FGG. However, none of the studies has tested its efficacy in RT2 recession defects. Hence, the aim of the study was to assess the clinical efficacy of GUG in the treatment of RT2 recession defects over a period of 6 months. Furthermore, an attempt was made to correlate the baseline clinical parameters related to avascular area of the defect-recession depth (RD), recession width (RW), and iCAL levels with the amount of mean percentage of root coverage (MRC) achieved at the end of 6 months.

METHODS

Sample size calculation

The sample size has been estimated using the G Power software v. 3.1.9.4 (Franz Faul, Universität Kiel, Germany); considering the effect size to be measured at 70%, power of the study at 80%, and the alpha error at 5%, the sample size needed is 19.

Nineteen systemically healthy patients, aged 22–36 years (mean: 27.8 ± 4 years, male = 12, female = 7) attending the outpatient department, department of periodontics, were selected for the study based on the following criteria.

Inclusion criteria

(1) Isolated RT2 buccal recession defects with depth ≥3 mm and clinically identifiable cementoenamel junction (CEJ) in mandibular anterior region (RT2-iCAL less than or equal to buccal attachment loss).[4] (2) No active periodontal disease with full-mouth plaque and full-mouth bleeding scores ≤15% after phase I therapy (measured at four sites per tooth).[910] (3) Nonsmoker, nontobacco user subjects maintaining good oral hygiene throughout the duration of study period.

Exclusion criteria

(1) Prominent or maloccluded teeth, which might require orthodontic correction prior to root coverage procedure. (2) Presence of noncervical carious lesions or root caries. (3) Pregnant patients and patients with systemic condition or using drugs which may be contraindication for periodontal surgery.

Surgical procedure was explained to the patients along with the importance of maintaining oral hygiene throughout the study period. Written informed consent was obtained from the patients. The patients underwent a session of scaling and root planing and were instructed on oral hygiene maintenance. Over a period of 4 weeks, the patients were regularly recalled once a week and their oral hygiene was monitored using plaque and gingival index.[910] At the end of 4 weeks, the decision was made to perform surgery by GUGs. All surgical procedures were performed by an expert operator. Two independent examiners assessed all the clinical outcomes of treatment. Clinical measurements were taken at the baseline, 3 months, and 6 months after surgery. All the parameters were measured by UNC 15 probe and were rounded off to the nearest 0.5 mm. The parameters measured were RD, RW, iCAL, clinical attachment level at recession site relative clinical attachment level (rCAL), keratinized tissue width (KTW), probing depth (PD), and palatal clinical attachment level (pCAL). iCAL at both mesial and distal sites of the involved tooth was measured and the deepest measurement was recorded. pCAL levels were recorded at the baseline and at the end of 2 months. The percentage of root coverage achieved was estimated using the following equation:

CRC – the soft-tissue margin is at the CEJ, associated with a clinical attachment to the root and a shallow sulcus (≤2 mm) without bleeding on probing.[11]

Surgical procedure

Recipient site preparation

After adequate anesthesia, the root surface was root planed for a smooth finish and irrigated using normal saline to flush away loose debris. The recipient site was outlined using no. 15 bard parker (BP) blade. Two divergent incisions were placed outlining the recession defect involving mesial and distal papillae of the involved tooth. The apical extent of the incision was carried beyond the mucogingival junction to a distance of 3–5 mm apical to the level of recession. The outlined area including the papillae was de-epithelialized to create a vascular bed for receiving the graft [Figure 1b].

Figure 1

(a) Case 1: Prescaling. (b) Recipient site preparation. (c) Incision outlining the palatal graft. (d) Harvested graft. (e) Graft in place with sutures. (f) Postsuture removal. (g) 3 months postoperative. (h) 6 months postoperative. (i) Palatal healing at 2 weeks. (j) Palatal healing at 2 months

Donor site preparation

Palatal donor site was anesthetized. The outline of the recipient area was transferred onto a tin foil which was used to outline the palatal graft at first or second premolar region. A no. 15 BP blade was used to trace the outline of the graft to a depth of 1–1.5 mm [Figure 1c]. Graft papillae were first reflected by split dissection joined by a sulcular incision. The remaining portion of the graft was detached using no. 15 blade. The undersurface of the graft was trimmed to remove any loose tissue tags [Figure 1d]. After harvesting, hemorrhage control was done by pressure pack for 5 min and a custom-made acrylic stent was placed to cover the palatal wound. The graft was sutured to recipient bed using 4-0 black silk suture (Mersilk, Ethicon) [Figure 1e]. The area was gently pressed with moist gauze for approximately 2 min and covered using periodontal pack (Coe-Pak GC). The patient was prescribed systemic antibiotics and analgesics (500 mg amoxicillin every 8 h for 7 days and 600 mg ibuprofen every 12 h for 3–4 days). Chlorhexidine rinse 0.2% (10 ml, twice daily) was prescribed for oral hygiene maintenance. Suture removal was done after 2 weeks [Figure 1f]. Normal oral hygiene measures were resumed after 4 weeks. The patient was recalled every week for the 1st month and once every month thereafter for 6 months postoperatively. The recipient site clinical parameters were checked at 3 months [Figure 1g] and 6 months [Figure 1h]. Palatal CAL was recorded at the end of 2 months of healing postoperatively [Figure 1j].

Statistical analysis

The Statistical Package for the Social Sciences (SPSS) for Windows version 22.0 Released 2013. Armonk, NY, USA: IBM Corp. was used to perform statistical analyses. Descriptive statistics of all the explanatory and outcome parameters was done using frequency and proportions for categorical variables whereas in mean and standard deviation for continuous variables.

Inferential statistics

Friedman's test followed by Wilcoxon signed-rank post hoc test was used to compare the mean values of different parameters between different time intervals. Wilcoxon signed-rank test was used to compare mean pCAL at baseline and 2-month period and percentage MRC between 3- and 6-month periods. Spearman's correlation test was done to assess the relationship between RD, RW, iCAL, and percentage of MRC at 3 and 6 months. Simple linear regression analysis was used to predict the percentage of MRC at 6 months using RW at baseline period. The level of significance was set at P < 0.05.

RESULTS

Nineteen patients (mean age: 27.8 ± 4.0 years) were enrolled and completed the study. Out of 19 mandibular teeth, there were 9 central incisors, 6 lateral incisors, and 4 canines. Healing was uneventful in all patients. The clinical procedures and results of 2 representative cases are shown in Figures 1a-1j and 2a-2c. Table 1 shows the comparison of clinical parameters (in mm) at baseline, 3 months, and 6 months using Friedman's test followed by Wilcoxon signed-rank post hoc test. The mean RD was 4.87 ± 1.69 mm and mean RW 2.95 ± 0.47 mm, with labial CAL at 6.40 ± 1.90 at the baseline. RD, RW, rCAL, KTW, and PD showed a statistically significant difference with respect to baseline, at 3 months, and 6 months (P < 0.001). Furthermore, except PD, there was a statistically significant difference in the above clinical parameters between 3 and 6 months. pCAL, however, did not show any significant difference at baseline and 2 months. Table 2 shows the comparison of percentage of MRC between 3- and 6-month periods using Wilcoxon signed-rank test. The percentage of MRC was 81.79% ± 6.16% at the end of 6 months, which showed a statistically significant difference when compared with MRC at 3 months (P = 0.005). Table 3 shows Spearman's correlation test to assess the relationship between baseline RD, RW, iCAL, and percentage of MRC at 3 and 6 months. There was a negative correlation between all the three parameters and MRC at both 3 and 6 months. However, only RW had a statistically significant negative correlation with MRC at 6 months (P = 0.03). Further, simple linear regression analysis [Table 4] to predict the percentage of MRC at 6 months using RW at baseline was statistically significant. Graph 1 represents a scatter plot depicting recession width at baseline and percentage mean root coverage at 6 months.

Figure 2

(a) Case 2: Preoperative. (b) Healing at 3 months. (c) Healing at 6 months

Table 1

Comparison of clinical parameters (mm) at baseline, 3 months, and 6 months

Clinical parameter (n=19)	Time interval	Mean±SD (mm)	Pa	Pb
				Baseline and 3 months	Baseline and 6 months	6 months and 3 months
RD	Baseline 3 months 6 months	4.87±1.69 1.13±0.40 0.87±0.37	<0.001*	<0.001*	<0.001*	0.002*
RW	baseline 3 months 6 months	2.95±0.47 1.16±0.50 1.05±0.50	<0.001*	<0.001*	<0.001*	0.04*
PD	baseline 3 months 6 months	1.53±0.56 1.08±0.25 1.00±0.24	<0.001*	0.004*	0.001*	0.18
rCAL	baseline 3 months 6 months	6.40±1.90 2.21±0.48 1.87±0.44	<0.001*	<0.001*	<0.001*	0.003*
KTW	baseline 3 months 6 months	1.18±1.07 4.76±1.43 5.08±1.54	<0.001*	<0.001*	<0.001*	0.001*
iCAL	Baseline	2.21±0.69			0.18
pCAL	Baseline	0.53±0.61
	2 months	0.61±0.54

*Statistically significant difference (P<0.05). SD – Standard deviation; Pa – Friedman’s test; RD – Recession depth; RW – Recession width; PD – Probing depth; rCAL – Clinical attachment level at recipient site; Pb – Wilcoxon signed-rank post hoc test; KTW – Keratinized tissue width; iCAL – Clinical attachment level at interdental site; pCAL – Clinical attachment level at palatal site; n – number of subjects

Table 2

Comparison of percentage of mean root coverage at 3- and 6-month periods using Wilcoxon signed-rank test

Variable	Time	Mean±SD (%)	Mean difference (%)	P
Percentage of MRC	3 months	76.03±7.43	5.76	0.005*
	6 months	81.79±6.16

*Statistically significant difference (P<0.05). SD – Standard deviation; MRC – Mean root coverage

Table 3

Spearman’s correlation test to assess the relationship between RD, RW, iCAL, and percentage of root coverage at 3 and 6 months

Time	Variable	Values	RD	RW	iCAL
3 months	Percentage of MRC	Rho	−0.21	−0.21	−0.07
		P	0.39	0.40	0.78
6 months	Percentage of MRC	rho	−0.11	−0.51	−0.15
		P	0.66	0.03*	0.53

*Statistically significant (P<0.05) Correlation coefficient range 0.0-no correlation: 0.01-0.20-very weak correlation 0.21-0.40-weak correlation: 0.41-0.60-moderate correlation 0.61-0.80-strong correlation: 0.81-1.00-very strong correlation Rho – Correlation coefficients; minus (−) sign denotes negative correlation; MRC – Mean root coverage; RD – Recession depth; RW – Recession width; iCAL – Clinical attachment level at interdental site

Table 4

Simple linear regression analysis to predict percentage of root coverage at 6 months using recession width at baseline

IV	β	SE	t	P	R2
Constant	97.25	8.73	11.145	<0.001*	0.16
RW	−5.25	2.93	−1.793	0.04*

*Statistically significant (P<0.05). Interpretation: For every 1 mm decrease in recession width, the percentage of root coverage will significantly increase by 5.25% (P=0.04). The variability in percentage of root coverage will be explained by recession width level by 16%. IV – Independent variable; β – Beta-coefficient; SE – Standard error; t – Test statistic value; RW – Recession width

Graph 1

Scatter plot depicting recession width at baseline and percentage mean root coverage at 6 months. Percentage of mean root coverage (MRC)

DISCUSSION

The loss of interproximal attachment compromises the blood supply received by a nonsubmerged graft, as the graft heavily depends on plasmatic circulation or diffusion of nutrients from recipient area during the initial stages of healing. The vessels of gingiva are oriented in apico-coronal direction. These gingival vessels decrease in size and increase in number as they move coronally and form repetitive capillary loops at the marginal gingiva.[6] Supracrestal gingiva is the only tissue naturally created and specifically designed to survive and function interproximally and over avascular root surfaces.[5] Hence, in the present study, the authors have made an attempt to measure the clinical efficacy of GUG technique in achieving root coverage in RT2 recession defects in mandibular anterior region.

Mandibular anterior region presents some unique challenges. Presence of compromising factors such as narrow papillae influencing the vascularity, thin and narrow zone of keratinized tissue, presence of frenal pull, lip muscles, and minor vestibular depth may create an unfavorable environment for using submerged grafts.[12] FGG, when used as a one- or two-step procedure, is the most predictable treatment modality for increasing the thickness and width of keratinized tissue, as well as obtaining some amount of root coverage.[13] GUG, a modification of FGG, in the randomized controlled trials conducted has shown to increase KTW, and better MRC when compared to FGG.[678]

In the present study, the baseline RD measuring 4.87 ± 1.69mm reduced to 0.87 ± 0.37mm resulting in a MRC 81.79 ± 6.16% at the end 6 months. There was also a statistically significant increase in KTW (4.76 ± 1.43 mm and 5.09 ± 1.54 mm) at the end of 3 and 6 months, respectively, when compared to baseline levels (1.18 ± 1.06 mm) (P = 0.001). The documentation of GUG in the treatment of class III recessions can be seen only in two case reports.[1415] The authors reported 83% and 100% coverage of recession defects. Since there are no clinical trials using GUG to compare with, parallels can be drawn from the studies where FGG was used to treat recession sites with interdental attachment loss. A retrospective study by Esteibar et al. 2011 was done to assess presurgical, surgical, and postsurgical factors involved in achieving CRC using different root coverage techniques.[16] Out of the 121 class III recession sites treated with different surgical techniques, 11% of the sites were treated with FGG using Holbrook and Ochsenbein technique. The mean baseline RD of 3.18 mm reduced to 0.64 mm at the end of 12 months. A study by Remya et al., followed 12 early class III recession sites post FGG surgery for a period of 12 months.[17] The authors reported a mean baseline reduction of RD from 4.0 ± 1.4 mm to 2.3 ± 1.15 mm with a MRC percentage of 41.25 ± 21.07% at the end of 12 months.

The supracrestal gingiva when used as a free graft for root coverage purpose, may have a high capacity for perfusion and survival, gets rapidly revascularized and integrated into the recipient site.[5] Furthermore, the shape of the graft adapts well to the root curvature and the interdental spaces, thus reducing the dead space and further improving the vascularity. This can be a plausible explanation for the higher percentage of MRC in our study.

The palatal healing was uneventful and no undesirable recession at the palatal premolar region was seen due to harvesting of marginal gingiva and interdental papilla.

The mean presurgical iCAL was 2.21 ± 0.69 mm. An inverse, yet nonsignificant correlation was found between baseline RD, iCAL, and percentage of MRC at 3 and 6 months. As proposed by Miller, interdental attachment loss can be a limiting factor for CRC, especially when using nonsubmerged grafts. This paradigm holds true in the present study, as no CRC was achieved in any of the tested sites. However, none of the sites showed a residual recession more than 1.5 mm and 80%–100% of mean defect coverage can also be considered a successful treatment procedure.[18]

The correlation coefficient for baseline RW and percentage of MRC at 6 months was negative and statistically significant (P = 0.03). The percentage of MRC at 6 months can be predicted using RW at baseline that, with every 1 mm decrease in RW, MRC at 6 months will significantly increase by 5.25% (P = 0.04). Survival of the graft over the denuded root surface takes place by receiving circulation from capillaries in the vascular portion of the recipient site. This process is called bridging and is responsible for the uptake of nonsubmerged grafts, best results being obtained in cases of narrow recessions defects (<3 mm of RW).[19] The interproximal tissues provide stability and blood supply to the buccal flap / graft during the healing process and determines the coronal limit of the achievable root coverage at the buccal site after surgery.4 The mean RW of 2.95±0.47mm in the present study and an additional avascular surface due to interproximal attachment loss (2.21 ± 0.69 mm), acted as a limiting factor in achieving complete coverage in any of our tested sites.

CONCLUSION

GUG can be used to successfully cover denuded root surfaces and increase the width of keratinized tissue in teeth with interdental attachment loss. RW is the most significant factor in predicting the amount of root coverage achieved in RT2 recession defects. Studies, using a control group and followed up for a longer duration, will be useful to further test the efficacy of the relatively new GUG technique.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.