
==== Front
J Periodontal Implant Sci
J Periodontal Implant Sci
JPIS
Journal of Periodontal & Implant Science
2093-2278
2093-2286
Korean Academy of Periodontology

38290996
10.5051/jpis.2204100205
Research Article
Periodontal Science
Clinical evaluation of root coverage in Miller class III/RT2 labial gingival recession treated with interdisciplinary periodontal-orthodontic therapy: a randomized controlled clinical trial
https://orcid.org/0000-0002-5056-8791
Malhotra Sakshi 1
https://orcid.org/0000-0002-2659-333X
Tewari Shikha 1
https://orcid.org/0000-0001-8065-6584
Sharma Rekha 2
https://orcid.org/0000-0001-7839-1097
Sharma Rajinder Kumar 1
https://orcid.org/0000-0001-9469-897X
Tanwar Nishi 1
https://orcid.org/0000-0002-0740-1515
Arora Ritika 1
1 Department of Periodontics, Post Graduate Institute of Dental Sciences, Rohtak, India.
2 Department of Orthodontics and Dentofacial Orthopaedics, Post Graduate Institute of Dental Sciences, Rohtak, India.
Correspondence: Shikha Tewari. Department of Periodontics, Post Graduate Institute of Dental Sciences, Pandit Bhagwat Dayal Sharma University of Health Sciences, Rohtak 124001, India. drshikhatewari@yahoo.com, Tel: +91 9416514600, Fax: +91 1262283876
8 2024
20 11 2023
54 4 265279
13 10 2022
21 3 2023
30 4 2023
Copyright © 2024. Korean Academy of Periodontology
2024
Korean Academy of Periodontology
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/).
Purpose

The aim of current study was to evaluate percentage root coverage (RC%) in isolated Miller class III/RT2 labial gingival recession (GR) associated with malaligned mandibular anteriors, using interdisciplinary periodontal-orthodontic treatment as compared to mucogingival surgery alone.

Methods

Thirty-six systemically healthy patients having isolated Miller class III/RT2 GR with respect to malaligned mandibular anteriors, were randomly divided into test group: mucogingival surgery using subepithelial connective tissue graft followed by orthodontic treatment and control group: mucogingival surgery alone. Primary clinical parameters included (RC%), recession depth, keratinized tissue width, mid-labial clinical attachment level, interdental clinical attachment level (iCAL), periodontal phenotype (PP), gingival thickness (GT), root coverage esthetics score (RES) and hypersensitivity. Total duration of follow up was 12 months.

Results

Mean RC% was significantly more achieved in test group (66.67%±40.82%) in comparison to control group (39.93%±31.41%) at the end of study (P=0.049). Further, complete root coverage was attained in 5/8 cases of test group versus 1/2 cases of control group after 3/12 months respectively. RES and hypersensitivity, showed statistically significant improvement after complete follow up period in both the groups. An ideal RES score of 10 was achieved in 4/7 cases of test group while in 1/2 cases of control group after 3/12 months respectively. Correlation analysis revealed significant negative correlation between RC% and iCAL. Correlation of RC% with GT and PP was non-significant.

Conclusions

Interdisciplinary periodontal-orthodontic approach may be more beneficial in terms of achieving improved RC%, esthetic and resolution of hypersensitivity in the management of Miller class III/RT2 GR in malaligned mandibular anteriors.

Trial Registration

ClinicalTrials.gov Identifier: NCT04255914

Graphical Abstract

Connective tissue
Dentin hypersensitivity
Esthetics
Gingival recession
Orthodontics
Phenotype
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pmcINTRODUCTION

Gingival recession (GR) is defined as the migration of the gingiva to a point apical to the cementoenamel junction (CEJ) [1]. It has been encountered more frequently in mandibular than maxillary teeth and on labial than lingual surfaces [2]. It often causes aesthetic concerns [3], dentin hypersensitivity [4], and increased vulnerability to root caries [5].

The main etiologic factors in the pathogenesis of GR are periodontal disease and traumatic tooth brushing [26]. Besides these factors, various predisposing factors associated with GR include labial orthodontic tooth movement [7], bone dehiscence and fenestration [8], thin periodontal phenotype (PP) [9], and malposition of the teeth [10]. Prevalence of mid-buccal RT2 GR was reported to be 88.8% in adult US population, according to the 2017 world workshop classification [11].

Complete root coverage (CRC) in Miller class III/RT2 GR is challenging, and various techniques for the root coverage in Miller class III/ RT2 GR include coronally advanced flaps (CAFs) [12], laterally positioned flaps [13], free gingival grafts (FGG) [14], pouch and tunnel approach [15], vestibular incision subperiosteal tunnel access (VISTA) [16], and subepithelial connective tissue graft (SCTG) [17].

Tooth malpositioning is a predisposing factor associated with GR [10]. A correlation has been reported in a previously conducted study between the percentage root coverage (RC%) achieved and malocclusion [18]. In the study, CRC was achieved using SCTG in aligned teeth whereas partial root coverage was attained in malaligned teeth having Miller class I or II GR. A case report showed that orthodontic treatment after FGG further promoted root coverage in Miller class III GR with respect to protruded mandibular central incisor [19]. An interventional study conducted by Laursen et al. [20] demonstrated that orthodontic treatment led to the conversion of Miller class III GR cases to class I or II GR, and recession depth (REC) was reduced.

Therefore, it was hypothesized that in managing Miller class III/RT2 GR where CRC is difficult to achieve, an interdisciplinary approach by performing mucogingival surgery followed by orthodontic correction would be more beneficial in achieving better outcomes. Since there is a paucity of randomized controlled trials studying this aspect; this study was designed to evaluate the clinical outcomes in terms of root coverage percentage achieved, in isolated Miller class III/RT2 GR in malaligned mandibular anteriors treated by an interdisciplinary approach.

MATERIALS AND METHODS

Experimental design

The current study was a parallel, randomized clinical trial, and this study was conducted according to the guidelines of the Helsinki Declaration of 1975, updated in 2013. The ethical approval was obtained from the ethical committee of Post Graduate Institute of Dental Sciences (PGIDS/IEC/2019/27) and study protocol was approved by the institutional review board of Pt. BD Sharma University of health sciences, Rohtak. This trial was registered at ClinicalTrials.gov.with NCT04255914.

The study was carried out in the department of Periodontology in association with the department of Orthodontics and dentofacial orthopedics, PGIDS, Rohtak. Sixty-eight patients were screened from regular out patient department of Periodontology, Orthodontics and dentofacial orthopedics, and Oral medicine and radiology. Thirty-six systemically healthy patients having isolated GR with respect to malaligned mandibular anteriors, and willing for orthodontic treatment, were enrolled for the study. The period of this study was from February 2020 to December 2021.

The inclusion criteria were as follows:

• Patients aged 18–35 years.

• An isolated Miller’s class III/RT2 GR, in relation to malaligned mandibular anteriors (Figure 1A-C, Figure 2A and B).

• Tooth size-arch length discrepancy ≤4mm, in mandibular anteriors.

• Non-extraction orthodontic cases.

• Tooth with clinically detectable CEJ.

• Good patient compliance after phase I treatment (full mouth plaque score <10%).

The exclusion criteria were:

• Systemic ailments (such as diabetes, hyperthyroidism) which affect the periodontium or periodontal treatment outcome.

• Stage III and IV periodontitis

• Patients with history of medications which hinder periodontal wound healing such as corticosteroids, long-term nonsteroidal anti-inflammatory drugs.

• Extruded tooth/tooth with trauma from occlusion (TFO).

• Pregnant or lactating women.

• Tooth with wasting disease and root caries.

• Endodontically involved/treated tooth.

• Mobile teeth

• Current and former smokers.

Figure 1 Clinical photographs of test group case. (A) Gingival recession in relation to mandibular left central incisor (#31), at baseline (T0). (B) Incisal view showing malaligned #31, at T0 . (C) Radiograph showing interdental bone loss in relation to #31. (D) SCTG harvested from palate. (E) Intraoperative image showing recession coverage with SCTG using modified supraperiosteal tunnel access technique. (F) 15 days after suture removal. (G) Three months postoperative/initiation of orthodontic treatment (T1), showing keratinized tissue width. (H) At the middle of orthodontic treatment (T2). (I) At end of orthodontic leveling and alignment (Te). (J) Incisal view at end of orthodontic leveling and alignment (Te).

SCTG: subepithelial connective tissue graft.

Figure 2 Clinical photographs of control group case. (A) Gingival recession in relation to mandibular right central incisor (#41), at baseline (T0). (B) Radiograph showing interdental bone loss in relation to #41. (C) SCTG harvested from palate. (D) Intraoperative image showing SCTG insertion using pouch and tunnel technique. (E) 15 days after suture removal. (F) At 3 months postoperative (T1), showing thick periodontal phenotype. (G) At end of follow-up (Te). (H) Incisal view showing malaligned #41 (at Te).

SCTG: subepithelial connective tissue graft.

Prior informed and written consent was taken from each patient willing to participate in this study after explaining the procedure in patient’s native language.

Sample size

Basic formula of sample size calculation was used to calculate study participants taking effect size as 1 (0.5 mm of improvement in mean REC, with a standard deviation of 0.5 in the study population), α=0.05 and power=0.80, a sample size of thirty two participants was computed [21]. To recompense for 10% drop out of participants during the course of the study, a total of thirty six participants were recruited for this study.

Clinical parameters

The primary outcome variables included RC% [22], REC, keratinized tissue width (KTW), mid-labial clinical attachment level (mCAL), interdental clinical attachment level (iCAL), PP [23], Gingival thickness (GT) [24], root coverage esthetics score (RES) [25], patient-based evaluation of hypersensitivity by visual analogue scale (VAS).

Secondary outcome variables were bleeding on probing (BOP) [26], recession width at cervical level and at apical level (RW), plaque index (PI) [27], probing pocket depth (PPD), gingival index (GI) [28].

Intraoral periapical radiographs were taken at the beginning of the study using parallel angle technique. Level of alveolar bone crest from CEJ was calculated by using Image-J software.

Data collection method

A periodontal probe (PCP-UNC 15, Hu-Friedy, Chicago, IL, USA) was used to measure PI, GI, PPD, and BOP at three sites (mesio-labial, disto-labial and mid-labial) for the specific tooth. Clinical attachment level (CAL) was calculated from CEJ to the base of the pocket at mid-labial site as well as interdentally. Measurements were taken to the nearest millimeter. REC was taken from the mid-labial point to the gingival margin of the involved tooth. KTW was recorded from the gingival margin of the involved tooth to the mucogingival junction (MGJ) at the mid-labial point. PP was registered by periodontal probe, based on transparency through the gingival surface. GT was measured using endodontic file with silicon stopper and digital vernier calliper (Zhart digital vernier calliper, India) at mid root level. RW at cervical level from the mesial to the distal gingival margin at the level of CEJ was recorded and also at the level of receded gingival margin.

RC% was calculated according to the formula: REC (preoperative–postoperative)/REC preoperative×100.

RES was evaluated using five variables, including marginal tissue contour, soft tissue texture, level of gingival margin, gingival color, and MGJ alignment.

VAS for hypersensitivity was recorded by patients and categorised into: mild (1–3), moderate (4–6) and severe (7–10).

Recording of all clinical parameters in test group cases were done at baseline (T0), 3 months of SCTG placement/initiation of orthodontic treatment (T1), middle of orthodontic treatment (T2) and at the end of leveling and alignment (approximately, 8–9 months of initiation of orthodontic treatment, Te). Similarly, in control group parameters were recorded at baseline (T0), 3 months of SCTG placement (T1) and followed-up further for 8–9months (Te).

Intraexaminer reproducibility

The intra-examiner (ST) reproducibility for REC and CAL was evaluated on 10 teeth having GR, who were not enrolled in the study. Assessment of measurements was done at two time points with a difference of 48 hours. Intra examiner reproducibility was checked and measurements were matching with >90% accuracy (k value 0.84 and 0.81 respectively).

Randomization

Patients enrolled in the present study were randomized by generating a computerized list with block size of 4 and 6 using random allocation software system [29], by another investigator (NT). For allocation concealment, sequentially numbered sealed opaque envelopes were used. The outcome assessor (ST) was not blinded in this study. Patients were allocated into two groups with allocation ratio of 1:1 and the allotted treatment was informed to the operators (SM and RS) at T1 (prior to orthodontic treatment).

1) Mucogingival surgery and orthodontic treatment (test group): After completion of phase I therapy, root coverage procedure was done using SCTG. Three months following the graft placement, orthodontic treatment was initiated.

2) Mucogingival surgery alone (Control group): After completion of phase I therapy, root coverage was done using SCTG. Orthodontic treatment was deferred till the completion of this study in this group.

Intervention

Periodontal surgical procedure

Mucogingival surgery was performed by single operator (SM) in all the patients, who was not aware about the group allocation at the time of mucogingival surgery. Thorough scaling and root planing was performed using ultrasonic scaler (Woodpecker HW-3H scaler, Guangxi, China), hand scaler and curette (Hu-Friedy). After resolution of inflammation, mucogingival surgery was performed. Root prominence was reduced with the burs (Mani Dia Burs, New Delhi, India)/curette (Hu-Friedy). Root surface conditioning was not performed. Under local anaesthesia, recipient bed was prepared in the recession region using pouch and tunnel [30], or modified vestibular incision supraperiosteal tunnel technique (without frenectomy) [31], according to the clinical case indication. In pouch and tunnel technique, the recipient site was prepared by an internal beveled incision, using 15C blade (15 C Hu-Friedy) to eliminate the sulcular epithelium, followed by “envelope” preparation apically and laterally (3–5 mm) to the recession and extended beyond MGJ. Tunneling instruments (GDC, New Delhi, India), were used to prepare supraperiosteal tunnel/envelop. Care was taken to avoid detachment of the papillae. SCTG was procured from the palate using single incision technique proposed by Hürzeler et al. [32]. A number 15 scalpel blade (Surgeon Blades & Medical Devices Private Limited, Vadodara, India) was used to make a horizontal incision to the bone 2 mm away from the gingival margin of maxillary premolars. SCTG of approximately 2 mm in thickness and approximately three times wider than recession width (Figures 1D and 2C), was inserted into the prepared tunnel/envelop at recipient site (Figures 1E and 2D) and sutured using resorbable suture (5-0 Vicryl, Ethicon, Johnson & Johnson private limited, Mumbai, India).

Postoperative care

All the patients were advised not to use toothbrush and interdental aids for plaque control until the sutures had been removed. Cap. Amoxicillin (Almox, Alkem laboratories Ltd., Mumbai, India) 500 mg, 3 tabs per day for 5 days and Tab Brufen (Brufen, Abbott, Mumbai, India) 400 mg, 3 tablets per day for 3 days was prescribed to all patients. 0.2% chlorhexidine mouthwash (0.2% Hexidine, ICPA Health Products Ltd., Mumbai, India) twice daily was advised for 14 days. After10 to 14 days of surgery, sutures were removed. Patients were recalled for examination every 15 days (Figures 1F and 2E) for up to 1 month after surgery. Orthodontic treatment was initiated in test group patients after 3 months of SCTG (T1, Figure 1G) and clinical parameters were recorded at mid-orthodontic level (T2, Figure 1H) and at the end of leveling alignment of tooth having GR (approximately 8–9 months of initiation of orthodontic therapy, Te, Figure 1I and J). Control group patients were recalled after 3 months of SCTG (Figure 2F) and further followed up for 8–9 months (Te, Figure 2G and H).

Orthodontic procedure

Orthodontic treatment was carried out by the same orthodontist (RS) using fixed mechanotherapy. MBT 0.022 slot with wire sequencing 0.014 NiTi, 0.016 NiTi, 0.018 NiTi, 0.018 SS, 0.017SS×0.025 SS was used, for leveling and alignment (Figure 1H-J). During orthodontic treatment, forces applied were light continuous and well-balanced. Home care oral hygiene maintenance program was reinforced in each patient and supragingival scaling was done, at each follow-up visit.

Statistical analysis

Data recorded were processed by standard statistical analysis using software (SPSS, version 25, IBM, Armonk, NY, USA). Shapiro wilk test was applied to check normality. All clinical parameters except CAL, was found to be non-normally distributed. Friedman test and repeated measure analysis of variance (CAL) was applied to evaluate intragroup differences at different time points in both the groups, followed by Wilcoxon signed rank test and paired t-test respectively between any two time points. Intergroup comparison was done by Mann-whitney U test and independent t-test. Pearson correlation was applied between RC%, mean iCAL. Spearman’s correlation was applied between RC% and GT. Point-biserial correlation was applied to find correlation of RC% with PP. The level of significance (P value) was set at 5%.

RESULTS

Thirty-six patients were recruited in the present study. Total six patients (3 in each group) were lost during follow up and thirty patients (15 in each group) completed treatment protocol. At three months of SCTG, one patient in test group did not report after state wide lockdown amid COVID-19. Three patients in control group were lost to follow-up due to non-compliant to follow-up visit. Two patients in test group turned COVID-19 positive at the middle of orthodontic treatment (Figure 3). Healing was uneventful after mucogingival surgery and no complications were observed throughout the treatment.

Figure 3 Flow chart of study population.

SRP: scaling and root planning, SCTG: subepithelial connective tissue graft, COVID-19: coronavirus disease 2019.

Table 1 demonstrates demographic data and clinical parameters. On applying Mann-whitney test, all the parameters were comparable at baseline.

Table 1 Demographic table: clinical parameters of the study population in terms of mean±SD for continuous variables and frequency for categorical variables

Parameters	Test group	CI	Control group	CI	P value	
Upper bound lower bound	Upper bound lower bound	
Age	21.73±4.99	24.50	18.97	24.93±4.43	27.39	22.48	0.072	
Sex (F:M)	10:5	-	-	11:4	-	-	-	
No. of surfaces involved								
	1	9			11				
	2	6			4				
	3	-			-				
GIa)	0.11±0.16	0.20	0.02	0.13±0.21	0.25	0.02	0.900	
GIb)	0.00±0.00	0.00	0.00	0.00±0.00	0.00	0.00	1.000	
PIa)	0.15±0.17	0.25	0.06	0.15±0.17	0.25	0.06	1.000	
PIb)	0.20±0.41	0.43	−0.03	0.27±0.46	0.52	0.01	0.671	
PPDa) (mm)	1.79±0.39	2.01	1.58	1.93±0.46	2.18	1.68	0.390	
PPDb) (mm)	1.27±0.46	1.52	1.01	1.67±0.62	2.01	1.32	0.059	
iCALa) (mm)	2.27±0.62	2.61	1.92	2.50±0.46	2.76	2.24	0.254	
mCAL (mm)	3.50±1.15	4.14	2.86	4.27±1.10	4.88	3.66	0.072	
BOPa)	0.02±0.09	0.07	−0.03	0.02±0.09	0.07	−0.03	1.000	
BOPb)	0.00±0.00	0.00	0.00	0.00±0.00	0.00	0.00	1.000	
RECb) (mm)	2.33±0.90	2.83	1.84	2.80±0.94	3.32	2.28	0.160	
RWC (mm)	2.67±0.90	3.16	2.17	2.73±0.59	3.06	2.40	0.673	
RWA (mm)	1.80±0.56	2.11	1.49	1.73±0.46	1.99	1.48	0.775	
KTWb) (mm)	1.87±1.41	2.65	1.09	1.33±0.72	1.73	0.93	0.370	
GT (mm)	0.60±0.21	0.72	0.49	0.66±0.19	0.77	0.56	0.183	
HYS	0.93±1.22	1.61	0.26	1.20±1.37	1.96	0.44	0.562	
	Mild	6			7				
	Moderate	0			0				
	Severe	0			0				
PP (thin:thick)	13:2	-	-	14:1	-	-	-	
MBL (mm)	2.76±0.42	2.99	2.52	2.89±0.33	3.07	2.70	0.204	
DBL (mm)	2.86±0.48	3.12	2.59	2.93±0.61	3.27	2.60	0.902	
Data are shown as mean ± standard deviation.

CI: confidence interval, F: female, M: male, GI: gingival index, PI: plaque index, PPD: probing pocket depth, iCAL: interdental clinical attachment level, mCAL: midlabial clinical attachment level, BOP: bleeding on probing, REC: recession depth, RWC: recession width at level of cementoenamel junction, RWA: recession width apically at the level of receded gingival margin, KTW: keratinised tissue width, GT: gingival thickness, HYS: hypersensitivity (reported by patients based on visual analogue scale), PP: periodontal phenotype, MBL: mesial alveolar bone loss, DBL: distal alveolar bone loss.

a)Mean; b)Mid labial.

Table 2 depicts intragroup comparison in test group at different time points. Comparison between T0 and T1, showed statistically significant reduction in PPD, gain in mCAL, gain in mean iCAL, reduction in REC, RW, increase in KTW, achieved RC%, increase in GT and improved RES (P≤0.05). Also, there was reduction in GI, PI, BOP and hypersensitivity, though it was non-significant (P>0.05). PP converted into thick phenotype in 9 out of the 13 patients. Intragroup comparison between T1 and Te revealed statistically significant reduction in RW and gain in mean iCAL (P≤0.05). No deterioration was observed in REC, GT and KTW. The RC% achieved at 3 months (52.99%±39.59%) and at end of leveling alignment (66.67%±40.82%) have improved though it was non-significant (P>0.05).

Table 2 Intragroup comparison of all clinical parameters at T0, T1, T2, and Te in test group

Parameters	Baseline (T0)	3 months (T1)	Upper bound CI	Lower bound CI	Mid-ortho (T2)	Upper bound CI	Lower bound CI	End of L&A (Te)	Upper Bound CI	Lower Bound CI	P value (Friedman test and repeated ANOVA [CAL])	
GId)	0.11±0.16	0.07±0.14, P=0.157a)	0.14	−0.01	0.29±0.25	0.42	0.15	0.22±0.24, P=0.035b)f), P=0.132c)	0.35	0.09	0.004f)	
GIe)	0.00±0.00	0.00±0.00, P=1.000a)	0.00	0.00	0.27±0.46	0.52	0.01	0.07±0.26, P=0.317b), P=0.317c)	0.21	−0.08	0.019f)	
PId)	0.15±0.17	0.04±0.12, P=0.025a)f)	0.11	−0.02	0.35±0.20	0.46	0.24	0.31±0.15, P=0.001b)f), P=0.020c)f)	0.39	0.22	0.000f)	
PIe)	0.20±0.41	0.00±0.00, P=0.083a)	0.00	0.00	0.67±0.49	0.94	0.40	0.47±0.52, P=0.008b)f), P=0.157c)f)	0.75	0.18	0.001f)	
PPDd) (mm)	1.79±0.39	1.29±0.39, P=0.002a)f)	1.50	1.07	1.50±0.37	1.70	1.29	1.39±0.37, P=0.382b), P=0.010c)f)	1.59	1.18	0.003f)	
PPDe) (mm)	1.27±0.46	1.00±0.38, P=0.046a)f)	1.21	0.79	1.33±0.49	1.60	1.06	1.27±0.46, P=0.046b)f), P=1.000c)	1.52	1.01	0.053f)	
iCALd) (mm)	2.27±0.62	1.87±0.40, P=0.000a)f)	2.09	1.65	1.70±0.56	2.01	1.39	1.57±0.50, P=0.014b)f) P=0.000c)f)	1.84	1.29	0.000f)	
mCAL (mm)	3.50±1.15	2.20±1.01, P=0.000a)f)	2.76	1.64	2.67±1.05	3.25	2.09	2.40±1.06, P=0.189b), P=0.003c)f)	2.98	1.82	0.000f)	
BOPd)	0.02±0.09	0.00±0.00, P=0.317a)	0.00	0.00	0.09±0.15	0.17	0.00	0.11±0.16, P=0.025b)f), P=0.102c)	0.20	0.02	0.037f)	
BOPe)	0.00±0.00	0.00±0.00, P=1.000a)	0.00	0.00	0.00±0.00	0.00	0.00	0.07±0.26, P=0.317b), P=0.317c)	0.21	−0.08	0.392	
RECe) (mm)	2.33±0.90	1.20±1.08, P=0.002a)f)	1.80	0.60	1.27±1.16	1.91	0.62	0.93±1.16, P=0.102b), P=0.002c)f)	1.58	0.29	0.000f)	
RWC (mm)	2.66±0.90	1.60±1.35, P=0.007a)f)	2.35	0.85	1.53±1.30	2.25	0.81	1.13±1.36, P=0.038b)f), P=0.002c)f)	1.88	0.38	0.000f)	
RWA (mm)	1.80±0.56	1.20±1.01, P=0.024a)f)	1.76	0.64	1.07±0.96	1.60	0.53	0.67±0.90, P=0.023b)f), P=0.002c)f)	1.16	0.17	0.000f)	
KTWe) (mm)	1.87±1.41	3.00±1.73, P=0.003a)f)	3.96	2.04	3.07±1.62	3.97	2.17	3.07±1.62, P=0.564b) P=0.003c)f)	3.97	2.17	0.000f)	
GT (mm)	0.60±0.21	1.03±0.19, P=0.001a)f)	1.09	0.88	1.04±0.19	1.14	0.94	1.04±0.19, P=0.317b), P=0.001c)f)	1.14	0.94	0.000f)	
HYS	0.93±1.22	0.27±0.70, P=0.063a)	0.66	−0.12	0.13±0.52	0.42	−0.15	0.13±0.52, P=0.317b), P=0.038cf)	0.42	−0.15	0.005f)	
	Mild	6	2	1	
	Moderate	0	0	0	
	Severe	0	0	0	
RES	-	7.13±2.13, P=0.001a)f)	8.31	5.95	7.13±2.33	8.42	5.85	7.73±2.60, P=0.180b), P=0.001c)f)	9.18	6.29	0.000f)	
RC%	-	52.99±39.59, P=0.002a)f)	74.92	31.07	51.67±40.61	74.15	29.18	66.67±40.82, P=0.061b), P=0.001c)f)	89.27	44.06	0.000f)	
PP (thin:thick)	13:2	4:11	-	-	-	-	-	3:12	-	-	-	
Data are shown as mean ± standard deviation.

T0: baseline, T1: 3 months of connective tissue graft/initiation of orthodontic treatment, T2: mid-orthodontic treatment, Te: end of leveling and alignment, CI: confidence interval, GI: gingival index, PI: plaque index, PPD: probing pocket depth, iCAL: interdental clinical attachment level, mCAL: midlabial clinical attachment level, BOP: bleeding on probing, REC: recession depth, RWC: recession width at level of cementoenamel junction, RWA: recession width apically at the level of receded gingival margin, KTW: keratinised tissue width, GT: gingival thickness, HYS: hypersensitivity (reported by patients based on visual analogue scale), RES: root coverage esthetics score, RC%: percentage root coverage, PP: periodontal phenotype, ANOVA: analysis of variance, CAL: clinical attachment level.

a)Intragroup comparison between T0 and T1; b)Intragroup comparison between T1 and Te; c)Intragroup comparison between T0 and Te; d)Mean; e)Mid labial; f)P value ≤0.05 indicates significance.

Table 3 shows intragroup comparison in control group at different time points. Intragroup comparison between T0 and T1 revealed statistically significant improvement in mean PPD, mCAL, mean iCAL, mean GI and PI (P≤0.05). Statistically significant gain in KTW, achieved RC%, increase in GT, decreased REC and RW at the level of CEJ, improved hypersensitivity, and RES was also observed (P≤0.05). In 8 out of 14 patients, PP converted from thin to thick phenotype. Intragroup comparison of parameters between T0 and Te e revealed significant reduction in PPD, gain in mCAL and mean iCAL. REC reduced significantly, from mean score at T0 2.80±0.94 mm to 1.80±1.01 mm at Te. KTW and GT improved significantly. RC% was achieved (39.93%±31.41%).

Table 3 Intragroup comparison of all clinical parameters in control group and Intergroup comparison of changes (T0−T1 and T0−Te) in all clinical parameters

Parameters	Baseline (T0)	3 months (T1)	Upper bound CI	Lower bound CI	Control group (T0−T1)	Test group (T0−T1)	12 months (Te)	Upper bound CI	Lower bound CI	Control group (T0−Te)	Test group (T0−Te)	P value (Friedman test and repeated measure ANOVA [CAL])	
GIf)	0.13±0.21	0.02±0.09, P=0.025a)e)	0.07	0.03	0.11±0.16	0.04±0.12, P=0.203c)	0.00±0.00, P=0.034b)e)	0.00	0.00	0.13±0.21	−0.11±0.27, P=0.013d)e)	0.009e)	
GIg)	0.00±0.00	0.00±0.00, P=1.000a)	0.00	0.00	0.00±0.00	0.00±0.00, P=1.000c)	0.00±0.00, P=1.000b)	0.00	0.00	0.00±0.00	−0.07±0.26, P=0.317d)	-	
PIf)	0.15±0.17	0.07±0.14, P=0.046a)e)	0.14	−0.01	0.09±0.15	0.11±0.16, P=0.695c)	0.09±0.15, P=0.083b)	0.17	0.00	0.07±0.14	−0.15±0.21, P=0.003d)e)	0.039e)	
PIg)	0.27±0.46	0.00±0.00, P=0.046a)e)	0.00	0.00	0.27±0.46	0.20±0.41, P=0.671c)	0.00±0.00, P=0.046b)e)	0.00	0.00	0.27±0.46	−0.27±0.70, P=0.023d)e)	0.018e)	
PPDf) (mm)	1.93±0.46	1.42±0.43, P=0.002a)e)	1.66	1.18	0.51±0.41	0.51±0.35, P=0.849c)	1.38±0.43, P=0.002b)e)	1.62	1.14	0.55±0.43	0.41±0.49, P=0.376d)	0.000e)	
PPDg) (mm)	1.67±0.62	1.20±0.41, P=0.008a)e)	1.43	0.97	0.47±0.52	0.27±0.46, P=0.264c)	1.20±0.41, P=0.008b)e)	1.43	0.97	0.47±0.52	0.00±0.53, P=0.026d)e)	0.001e)	
iCALf) (mm)	2.50±0.46	1.80±0.56, P=0.000a)e)	2.11	1.49	0.70±0.25	0.40±0.34, P=0.010c)e)	1.63±0.52, P=0.000b)e)	1.92	1.35	0.87±0.35	0.70±0.65, P=0.389d)	0.000e)	
mCAL (mm)	4.27±1.10	3.000±1.000, P=0.00a)e)	3.55	2.45	1.27±0.88	1.30±0.96, P=0.922c)	2.87±1.19, P=0.000b)e)	3.52	2.21	1.40±0.99	1.10±1.17, P=0.453d)	0.000e)	
BOPf)	0.02±0.09	0.000±0.000, P=0.317a)	0.00	0.00	0.02±0.09	0.02±0.09, P=1.000c)	0.00±0.00, P=0.317b)	0.00	0.00	0.02±0.09	−0.09±0.20, P=0.049d)e)	0.368	
BOPg)	0.00±0.00	0.000±0.000, P=1.00a)	0.00	0.00	0.00±0.00	0.00±0.00, P=1.000c)	0.00±0.00, P=1.000b)	0.00	0.00	0.00±0.00	−0.07±0.26, P=0.317d)	-	
RECg) (mm)	2.80±0.94	1.866±0.833, P=0.001a)e)	2.33	1.40	0.93±0.59	1.13±0.74, P=0.403c)	1.80±1.01, P=0.001b)e)	2.36	1.24	1.00±0.65	1.40±0.91, P=0.162d)	0.000e)	
RWC (mm)	2.73±0.59	2.07±0.80, P=0.008a)e)	2.51	1.62	0.67±0.72	1.07±1.10, P=0.364c)	1.87±0.92, P=0.004b)e)	2.37	1.36	0.87±0.74	1.53±1.13, P=0.098d)	0.000e)	
RWA (mm)	1.73±0.46	1.60±0.74, P=0.317a)	2.01	1.19	0.13±0.52	0.60±0.83, P=0.117c)	1.47±0.83, P=0.102b)	1.93	1.00	0.27±0.59	1.13±0.74, P=0.003d)e)	0.135	
KTWg) (mm)	1.33±0.72	2.60±0.91, P=0.001a)e)	3.10	2.10	−1.27±0.59	−1.13±0.83, P=0.718c)	2.60±0.91, P=0.001b)e)	3.10	2.10	−1.27±0.59	−1.20±0.94, P=0.805d)	0.000e)	
GT (mm)	0.66±0.19	0.99±0.19, P=0.001a)e)	1.09	0.88	−0.32±0.14	−0.42±0.17, P=0.074c)	0.99±0.19, P=0.001b)e)	1.09	0.88	−0.32±0.14	−0.43±0.16, P=0.038d)e)	0.000e)	
HYS	1.20±1.14	0.13±0.52, P=0.023a)e)	0.42	−0.15	1.07±1.39	0.67±1.18, P=0.397c)	0.13±0.52, P=0.023b)e)	0.42	−0.15	1.07±1.39	0.80±1.21, P=0.578d)	0.002e)	
	Mild	7	1	1	
	Moderate	0	0	0	
	Severe	0	0	0	
RC%	-	33.33±27.28, P=0.001a)e)	48.43	18.22	−33.33±27.28	−52.99±39.59, P=0.189c)	39.93±31.41, P=0.002b)e)	56.83	22.04	−39.93±31.41	−66.67±40.82, P=0.049d)e)	0.000e)	
RES	-	6.20±1.70, P=0.003a)e)	7.14	5.26	−6.20±1.70	−7.13±2.13, P=0.227c)	6.60±1.84, P=0.001b)e)	7.62	5.58	−6.60±1.84	−7.73±2.60, P=0.171d)	0.000e)	
PP (thin:thick)	14:1	6:9	-	-	-	-	6:9	-	-	-	-	-	
Data are shown as mean ± standard deviation.

T0: baseline, T1: 3 months of connective tissue graft/initiation of orthodontic treatment, T2: mid-orthodontic treatment, Te (Control group): 12 months of connective tissue graft, Te (Test group): end of leveling and alignment, CI: confidence interval, mn- mean, ML- mid labial, GI: gingival index, PI: plaque index, PPD: probing pocket depth, iCAL: interdental clinical attachment level, mCAL: midlabial clinical attachment level, BOP: bleeding on probing, REC: recession depth, RWC: recession width at level of cementoenamel junction, RWA: recession width apically at the level of receded gingival margin, KTW: keratinised tissue width, GT: gingival thickness, HYS: hypersensitivity (reported by patients based on visual analogue scale), RC%: percentage root coverage, RES: root coverage esthetics score, PP: periodontal phenotype, ANOVA: analysis of variance, CAL: clinical attachment level.

a)Intragroup comparison between T0 and T1 in control group; b)Intragroup comparison between T0 and Te in control group; c)Intergroup comparison of changes in clinical parameters at T0 and T1 (T0−T1); d)Intergroup comparison of changes in clinical parameters at T0 and Te (T0−Te); e)P value ≤0.05 indicates significance; f)Mean; g)Mid labial.

Intergroup comparison of changes in parameters at T1 from baseline showed statistically non- significant difference between the groups (P≤0.05) except mean iCAL (P>0.05). Changes in clinical parameters at Te from baseline (T0–Te) showed statistically significant improvement in achieved RC%, GT, RW at apical level (P≤0.05) in test group. There was significant increase in PI and mean GI and PPD in test group patients (P≤0.05). REC reduction and improvement in KTW was comparable (P>0.05) in test versus control group (Table 3).

Correlation analysis demonstrated statistically significant negative correlation between RC% and mean iCAL (correlation coefficient r=−0.47, P=0.008). Correlation of RC% with GT and PP were also non-significant (r=0.07, P=0.719 and r=0.04, P=0.827, respectively).

DISCUSSION

The present randomized controlled trial was conducted to evaluate the root coverage achieved by interdisciplinary periodontal-orthodontic treatment in comparison to mucogingival surgical procedures alone. Miller class III/RT2 GR presents a challenge in achieving predictable coverage by mucogingival surgery due to associated parameters such as interdental bone loss and soft tissue loss. An interdisciplinary approach might be more favorable in achieving root coverage.

Mucogingival surgery was performed before orthodontic treatment in the present study to augment the GT and KTW. Moreover, the patients were concerned about their esthetics due to the presence of exposed root surfaces in anterior teeth. Wennström et al. [7] demonstrated gingival inflammation and the thickness of the marginal gingiva are crucial factors for the development of GR and attachment loss during orthodontic treatment. Mandibular incisors included in this study usually present with thin labial bone and are more susceptible to developing or exhibiting worsening of existing GR during orthodontic treatment. Moreover, orthodontic brackets may lead to inflamed gingival margins and persistent inflammation, which in thin PP, may lead to GR [7]. So, the soft tissue augmentation before orthodontic treatment may prove to be more valuable in these cases.

In the current study, intergroup comparison of changes in parameters at T1 from baseline showed statistically non-significant difference between the groups that suggests no variations due to surgical techniques used and similar mean root coverage (RC% 52.99%±39.59% and 33.33%±27.28% in the test and control group respectively) was achieved by connective tissue graft after 3 months of SCTG placement in both groups. Both techniques offer minimally invasive approach for the treatment of recession defects and preserve papillae integrity, adequate blood supply to the underlying graft, and esthetics [3031]. Therefore, minimally invasive approach was chosen in the present study over the CAF. A recent RCT also reported no significant difference in mean root coverage achieved at 6 and 12 months follow-up in Miller’s class III/RT2 GR treated with SCTG using tunneling technique compared to CAF [33]. CRC was obtained in 5 cases of test group and only in 1 case of control group after 3months of SCTG placement. Outcome may be less predictable in presence of thin gingival phenotype, shallow vestibule, and high frenal attachment and/or muscle pull in mandibular anterior region. Factors like loss of papillary height, tooth malposition, dimension of GR, number of root surfaces involved may also limit the level of recession coverage in such cases.

In the present study, an intergroup comparison of changes at the end of the study from the baseline (T0-Te) showed significant improvement in RC%, GT, and RW at the apical level. The findings showed an improvement in RC% of approximately 27% in the test group at the end of leveling and alignment. The difference in REC reduction seen in the test group as compared to the control group was nearly 0.5 mm which though statistically non-significant, has clinical relevance. CRC was achieved in 8 cases (53.3% of cases) in the test group versus only 2 cases (13.3%) in the control group. Similar findings were reported in an RCT with CRC in 43.75% of cases and mean RC% of 69.32%±30.74% at the end of leveling alignment, where SCTG was performed before orthodontic treatment [21].

In the test group, orthodontic treatment was initiated after 3 months of the mucogingival procedure once wound healing was accomplished [2134]. Intragroup comparison at T1 and Te in the test group revealed that RC% at the end of leveling and alignment improved further as compared to that obtained 3 months after SCTG. This improvement of 14% though statistically non-significant, is of clinical significance, implying that orthodontic treatment led to further coronal advancement of the gingival margin. Wennström et al. [35] suggested that when a facially positioned tooth is moved within the alveolar process, the GT increases on the facial aspect which leads to increased free gingival height and decreased clinical crown height. Similarly, the reduction in RW was also maintained at the end of leveling alignment in this study. An RCT conducted by Mehta et al. [21], showed similar findings in their test group. Recession coverage achieved in their study was comparable at the end of leveling and alignment with the present study, despite of inclusion of malaligned teeth having Miller class III GR with interdental clinical attachment loss in this study.

Intragroup comparison of parameters between T0 and Te in control group revealed RC% achieved was 39.93%±31.41%. In agreement with this finding, an RCT showed mean RC% of 56.49% in Miller class III/RT2 GR using m-VISTA along with SCTG after 12 months of follow-up [33]. Another case series reported mean root coverage of 58.72% after 6 months of follow up, treated with m-VISTA and SCTG, having multiple mandibular GRs including posterior teeth as well [36]. The results achieved in the present study in terms of RC% imply that root coverage with SCTG can be attempted in patients with malaligned teeth in the presence of interdental bone and soft tissue loss, who are not willing to undergo orthodontic treatment due to any reason.

Interdental CAL may indirectly indicate the changes in underlying bone level and it has been proven to be an important prognostic factor in consideration of success of root coverage procedure in Miller class III/RT2 GR [1737]. There was statistically significant gain in mean iCAL in test and control groups, three months after SCTG placement, and these results were maintained till the end of the study. Correlation analysis revealed statistically significant negative correlation between RC% and baseline mean iCAL (P=0.008) in this study. A similar correlation was found between these two factors in a study by Cairo et al. [17].

In the present study, statistically significant improvement in KTW and GT was observed after 3 months of SCTG placement, in both groups. Regarding the correlation of RC% with PP and GT, no correlation was found between these parameters in the present study and this finding was also supported by Jepsen et al. [38]. However, improved PP might have helped in maintaining the stable gingival margin level till the end of the follow-up in this study. Mehta et al. [21], reported gingival margin stability throughout orthodontic treatment, in cases where SCTG was placed prior to orthodontic treatment.

Patient- centered outcomes in terms of hypersensitivity and esthetic score at Te showed statistically significant improvement when compared to T0, in both groups. In the test group, mean VAS score for hypersensitivity was 0.93±1.22 at baseline which reduced significantly to 0.13±0.52 at the end of follow- up. Out of six patients who had chief complaints of hypersensitivity, five patients had complete relief at the end of leveling alignment. A statistically significant reduction in hypersensitivity mean score at the end of leveling alignment was also observed in another study [21]. In the control group, six out of seven patients got complete relief from hypersensitivity after SCTG placement. The mean VAS score reduced statistically significantly from 1.20±1.14 at baseline to 0.13±0.52 at the end of follow-up. An RCT conducted by Cairo et al. [17] also showed similar findings.

In this study, mean RES scores observed at the end of follow-up was 7.73±2.60 and 6.60±1.84 in the test and control group respectively. A study reported, SCTG and orthodontic leveling alignment led to RES mean scores of 8.00±1.79 [21]. Another study revealed RES mean score of 7.6±1.7 at 6 months follow-up, in cases where CAF and SCTG were performed [17]. An ideal RES score of 10 was observed in 7 cases of test group while only in 2 cases of control group at Te.

In the present study, an extruded tooth was excluded because orthodontic intrusion may give misleading results of recession coverage. Tooth having TFO was also excluded as TFO would disturb wound healing and may affect the surgical outcome. Root conditioning was not performed as literature reported no added advantage of root conditioning on the clinical outcomes of root coverage in GR using SCTG [39]. However, the study has the following limitations. Patients who received orthodontic treatment could be followed only till the end of leveling and alignment due to time constraints, and to have a uniform endpoint. Standardization of cases could not be done in terms of number of root surfaces involved. Less number of patients could complete the treatment protocol due to COVID-19. Cone-beam computed tomography was not used to assess the alveolar bone status.

Within the limitations of the present study, it can be concluded that mucogingival surgery followed by orthodontic treatment may result in more root coverage in malaligned mandibular anteriors having isolated Miller class III/RT2 GR as compared to mucogingival surgery alone. Satisfactory improvement was observed in hypersensitivity and esthetics on completion of orthodontic leveling and alignment. Further, multicentered research with greater sample size, different tooth types, and comparison among arches, using an alternative to SCTG, is required as variations in these factors may influence the results.

ACKNOWLEDGEMENTS

The authors acknowledge the “Post Graduate Institute of Dental Sciences, Rohtak” for providing all the facilities to conduct this study.

Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Author Contributions: Conceptualization: Sakshi Malhotra, Shikha Tewari, Rekha Sharma.

Formal analysis: Shikha Tewari, Rekha Sharma.

Investigation: Sakshi Malhotra, Shikha Tewari, Rekha Sharma, Nishi Tanwar.

Methodology: Shikha Tewari, Rekha Sharma, Rajinder Kumar Sharma, Nishi Tanwar, Ritika Arora.

Project administration: Shikha Tewari, Rekha Sharma.

Writing - original draft: Sakshi Malhotra, Shikha Tewari, Rekha Sharma, Ritika Arora.

Writing - review & editing: Sakshi Malhotra, Shikha Tewari, Rekha Sharma, Rajinder Kumar Sharma, Nishi Tanwar, Ritika Arora.
==== Refs
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