| Abstract|| |
Aims and Objectives: The aim of this study is to determine the effectiveness of subepithelial connective tissue grafts (SCTG) in the coverage of denuded roots.
Materials and Methods: A total of 16 sites with ≥2 mm of recession height were included in the study for treatment with SCTG. The clinical parameters, such as recession height, recession width, width of keratinized gingiva, probing pocket depth, and clinical attachment level were measured at the baseline, third month, and at the end of the study [sixth month]. The defects were treated with a coronally positioned pedicle graft combined with connective tissue graft.
Results: Out of 16 sites treated with SCTG, 11 sites showed complete (100%) root coverage; the mean root coverage obtained was 87.5%. There was a statistically significant reduction in recession height, recession width, and probing pocket depth. There was also a statistically significant increase in the width of keratinized gingiva and also a gain in clinical attachment level. The postoperative results were both clinically and statistically significant ( P < 0.05).
Conclusion: From this study, it may be concluded that SCTG is a safe and effective method for the coverage of denuded roots.
Keywords: Connective tissue graft, full-thickness flap, recession, root coverage
|How to cite this article:|
Ahathya R S, Deepalakshmi D, Ramakrishnan T, Ambalavanan N, Emmadi P. Subepithelial connective tissue grafts for the coverage of denuded root surfaces: A clinical report. Indian J Dent Res 2008;19:134-40
The desire for improved esthetics and the consequent demand for cosmetic dentistry has increased tremendously in recent times. Cosmetic procedures have become an integral part of periodontal treatment. One of the commonly used esthetic periodontal procedures is coverage of denuded roots.
|How to cite this URL:|
Ahathya R S, Deepalakshmi D, Ramakrishnan T, Ambalavanan N, Emmadi P. Subepithelial connective tissue grafts for the coverage of denuded root surfaces: A clinical report. Indian J Dent Res [serial online] 2008 [cited 2021 Sep 24];19:134-40. Available from: https://www.ijdr.in/text.asp?2008/19/2/134/40468
Gingival recession is the term for the exposure of root surface due to apical migration of gingival margins. Many patients seek treatment because of concerns about esthetic appearance, root sensitivity, or fear of early loss of the affected teeth. However, other complications can also arise, such as root caries and tooth discoloration.
The most common cause for gingival recession is abrasive and traumatic tooth brushing habits. , Other causes include, buccally positioned teeth,  periodontal inflammation and resultant loss of attachment, frenal and muscle attachments that encroach on marginal gingiva, and orthodontic tooth movement through a thin buccal osseous plate. ,
The etiopathogenesis of gingival recession is based on the inflammation and subsequent destruction of the connective tissue of free gingiva. The oral epithelium migrates to the borders of the destroyed connective tissue. The thickening of the gingival and sulcular epithelial basal laminae reduces the quantity of connective tissue between them. Thus, blood supply is reduced, negatively influencing the repair of the initial lesion. As the lesion progresses, the connective tissue disappears, and the oral epithelium fuses with the junctional/sulcular epithelium. In recession caused by plaque and tartar, the initial ulcer appears in the junctional epithelium of the sulcus and the destruction of the connective tissue occurs from inside out. In lesions caused by toothbrush trauma, destruction occurs from outside in. 
Obtaining predictable and esthetic root coverage has become an important goal for a periodontal plastic surgeon. The search for the perfect root coverage technique has taken many different approaches. Of these, subepithelial connective tissue graft (SCTG) has become a popular modality of root coverage because of its high success rate. 
The clinical advantages of SCTG are apparent not only at the recipient site, where there is good tissue blending and predictability of results, but also in the palatal donor area, as it uses a more conservative approach to harvest the graft, decreasing the degree of discomfort. 
The present study is a fresh effort to evaluate the clinical effectiveness of SCTG in the coverage of denuded roots.
| Materials and Methods|| |
The patients for this study were selected from the patient pool of the Department of Periodontics, Meenakshi Ammal Dental College and Hospitals, Chennai. Twelve patients within the age-group of 20-50 years participated in the study.
- Anterior teeth and premolars with recession height ≥2 mm, which were classifiable as Miller's class I or II recession
- Normal alignment of teeth in the arch
- Radiographic evidence of sufficient interdental bone adjacent to the involved tooth
- Patient capable of maintaining good oral hygiene
- Patient not undergone periodontal surgery within the past 12 months
- Root surface restoration
- Root caries that would require restoration
- Drug allergy
- Systemic disease
- Abnormal frenal attachment
- Trauma from occlusion
The treatment protocol was explained to the patients and informed consent was obtained. All the patients were educated and motivated regarding maintenance of good oral hygiene. All patients underwent the initial phase of treatment, i.e., thorough scaling and root planing.
At the baseline, a preoperative photograph was taken [Figure - 1]. All the clinical parameters like recession height (H), recession width (W), width of keratinized gingiva (WKG), probing pocket depth (PD), and clinical attachment level (CAL) were recorded using William's graduated periodontal probe.
The surgical technique used was bilaminar connective tissue graft (CTG) placed beneath a full-thickness flap.  The surgical area was anesthetized with 2% lignocaine hydrochloride containing 1:2,00,000 epinephrine. A full-thickness flap was raised with a horizontal incision 2 mm apical to the tip of the papilla and two vertical incisions 1-2 mm apical to the gingival margin of the adjoining teeth. The flap was extended till the mucobuccal fold, ensuring that there were no perforations that could affect the blood supply [Figure - 2]. A releasing incision of the periosteum at the base of the flap was made for easy coronal migration. The convexity of the root was reduced using an airotor with a tapered fissure bur and a thorough root planing was done.
The CTG was harvested from the palate, following a "trap-door" flap design  [Figure - 3]. A No. 15 blade was used to make a partial-thickness horizontal incision, with a bevel about 3 mm apical to the gingival margin of the first premolar, extending towards the first molar. Two vertical incisions were made mesiodistally. Tissue forceps was used to lift the prepared palatal flap edge. It was reflected toward the center of the palate and the underlying connective tissue was exposed. An incision perpendicular to the bone was made around the edge of the connective tissue, facilitating its reflection from the bone. A small periosteal elevator and Kirkland knife were used to reflect the connective tissue and harvest it. After harvesting the graft, the wound was closed using 4-0 black silk sutures.
The harvested CTG was placed on the denuded root and stabilized with 5-0 polyglactin 910 resorbable sutures [Figure - 4]. The overlying flap was pulled coronally to cover the graft as much as possible and was sutured [Figure - 5]. The donor and recipient sites were covered with Coe-pack.
All patients were placed on analgesics and 0.2% chlorhexidine digluconate mouthrinse twice daily for 2 weeks. Patients were advised to take soft food and not to brush at the grafted site for at least 1 month from the day of surgery. They were told to use a cotton-tip applicator with 1% chlorhexidine gel to gently clean the area for 2 weeks after suture removal. Gentle brushing and flossing was to be resumed after a month.
Patients were recalled after 10 days for removal of periodontal dressing and sutures [Figure - 6]. The surgical site was examined to confirm that uneventful healing had taken place. The clinical parameters, i.e., recession height, recession width, width of keratinized gingiva, were recorded. A postoperative photograph was taken.
On follow-up visits at the end of the third month (ninetieth day) [Figure - 7] and at the end of the sixth month (one hundred and eightieth day) [Figure - 8] all the clinical parameters were again recorded. Postoperative clinical photographs were also taken.
| Results|| |
In this study, a total of 16 sites (in 12 patients) with gingival recession ranging from 2 to 6 mm were treated with SCTG. In order to minimize variation in surgical technique, all the procedures were completed by one surgeon, who also followed up the patients for a period of 6 months.
Mean and standard deviation of all the parameters were estimated for the recession sites. Mean changes were compared against the null hypothesis. Student's paired t-test was employed to test the significance of the differences between the means at baseline and at the sixth month. In the present study, P < 0.05 was considered as indicating statistical significance.
The preoperative (at baseline) and postoperative (at third and sixth month) readings of the five parameters were recorded and the percentage of root coverage for all 16 sites were calculated and tabulated [Table - 1].
Eleven out of the sixteen sites showed 100% recession height coverage. The mean recession height coverage obtained at the end of the sixth month was 87.5%. The mean preoperative recession height was 3.37 mm. The mean postoperative recession height at the third month was 0.43 mm, which remained the same at the end of the study (sixth month). The mean change in recession height was 2.84 mm, which was statistically significant at P < 0.05.
The mean preoperative recession width was 3.25 mm. The mean postoperative recession width at third month and sixth month was 0.62 mm. The mean change in recession width was 2.63 mm, which was statistically significant at P < 0.05. The mean preoperative width of keratinized gingiva was 3.06 mm. The mean width of keratinized gingiva at third month was 5.18 mm and it was 5.12 mm at the end of the study (sixth month). The mean change in width of keratinized gingiva was 2.06 mm, which was statistically significant at P < 0.05.
The mean preoperative pocket depth was 1.31 mm. The mean probing pocket depth at third and sixth month was 1 mm. The mean change in pocket depth was 0.31 mm, which was statistically significant at P < 0.05. The mean preoperative clinical attachment level was 4.68 mm. The mean clinical attachment level at the end of the third month was 1.56 mm and it was 1.43 mm at the end of the study [sixth month]. The mean gain in clinical attachment level was 3.25 mm, which was statistically significant at P < 0.05.
Preoperatively, the mean width of attached gingiva was 1.75 mm (width of keratinized gingiva of 3.06 mm - probing depth of 1.31 mm). The mean gain in the width of attached gingiva at the end of the study was 4.12 mm (5.12-1.00 mm).
| Discussion|| |
Obtaining predictable root coverage has become an important part of periodontal therapy. Many different surgical procedures have been used to achieve root coverage, for example pedicle grafts, free gingival grafts, CTG, and guided tissue regeneration. Some techniques, when attempted by the clinician, produce unsatisfactory results. There are many reasons for these failures; they include poor case selection, improper technique selection, poor surgical technique, unrealistic goals, and lack of experience in performing reconstructive periodontal plastic surgical procedures.
Of the various techniques used, subepithelial connective tissue graft (SCTG) is considered the gold standard treatment for coverage of denuded roots. In this study, during the preparation of the recipient bed, a full-thickness flap was reflected for the following reasons:
- Attempts made to prevent bone loss by reflecting a partial thickness flap may sometimes result in flap perforation which in turn can lead to flap necrosis and further bone loss. 
- With full-thickness flap/subepithelial connective tissue grafting, rapid capillary proliferation from the periosteal surface of the overlying full-thickness flap approximating the outer surface of the connective tissue grafting material is anticipated. 
- Also, highly vascularized tissue adjacent to a root surface (as in the case of a partial-thickness flap) has been suggested as a necessary condition for root resorption. Hence periodontists performing partial-thickness connective tissue grafting should be alert to the possible occurrence of external root resorption over extended periods of time. 
Full-thickness flap/subepithelial connective tissue grafting has been studied in detail by many workers. ,,
Root preparation before root coverage can be mechanical, chemical, and/or a combination of both. The mechanical preparation usually involves scaling and root planing, which will remove cementum and softened dentin and smoothen the root surface. Chemical biomodification of the root has generally centered on citric acid/tetracycline hydrochloride therapy, supposedly to demineralize a hypermineralized root.
Many investigators have utilized citric acid or tetracycline solutions in root surface biomodification in the belief that removing the smear layer and exposing collagen fibrils would aid in better reattachment of grafted tissue. However, Cafesse et al .  failed to show the benefit of citric acid conditioning in root coverage with SCTG. Also, Bouchard et al .  in his study found only minimal increase in the percentage of root coverage in patients treated with citric acid.
The potential role of root surface demineralization with acidic agents in inducing resorption also deserves attention. Ben Yehouda  reported a case of root resorption following a periodontal regenerative procedure for an intrabony defect where tetracycline hydrochloride was applied to the root.
At present, there is insufficient human biopsy material or histologic evidence available to determine the quality of wound healing following root conditioning with tetracycline or citric acid. Thus, owing to the risks and limited benefits of root demineralization with chemical agents, in the present study, root preparation was limited to mechanical scaling and root planing.
Graft was procured by the trap-door technique as described by Edel.  Its advantages include the ability to obtain a graft size similar to the incision design, greater visibility, and easier execution. But its disadvantage is that it involves more incision lines and requires more sutures. 
Orientation of the superficial surface of the CTG was not specific to either the gingival flap or the root surface. This is in accordance with the study done by Mohammed et al .,  which indicated that the surface orientation of the CTG had no significant effect on the clinical outcome of root coverage. After placing the procured graft over the recipient bed, it was covered by coronally positioning the flap. A recent study concluded that the more coronal the level of the gingival margin after suturing, the greater the probability of complete root coverage.  Accordingly, in this study, the flap covered the graft as much as possible and was coronally positioned and sutured.
In this study, a total of 16 sites with gingival recession ranging from 2 to 6 mm were treated with SCTG combined with a coronally positioned pedicle flap. The patients were followed for up to 6 months (180 days).
With SCTG, the mean root coverage obtained at the end of the study (sixth month) was 87.5%. This coverage of denuded roots is statistically significant. Thus the percentage of root coverage obtained in the current study is found to be well within the limits of the studies done by Borghetti et al .,  who obtained root coverage of 70.5%, and Harris et al .,  who obtained root coverage of 97.6%.
The root coverage obtained with this bilaminar technique was found to be less than that obtained by Tozum et al .  (96.4%) and Zabalegui et al .  (91.6%), who used the pouch and tunnel technique with SCTG for root coverage. The increased percentage of root coverage in these studies may be due to the minimal incision and reflection of the flap, allowing unhindered blood supply. This technique is especially effective for the anterior maxillary area, where vestibular depth is adequate and there is good gingival thickness.  In contrast, we have included maxillary and mandibular premolars in our study. However, the percentage of root coverage obtained by Tozum et al .,  using the Langer and Langer technique, was 75.5%, which is less than that obtained in our study (87.5%).
Eleven out of the 16 sites showed complete root coverage (100%), with five other sites showing ≥ 50% of coverage. Complete root coverage was obtained in 68.7% of the sites and it correlated well with the study by Paolantonio et al .,  who observed complete root coverage in only 46.6% of the sites treated with SCTG.
Of the five sites which did not achieve complete root coverage, one showed 83.33%, one 66.66%, and three other sites obtained 50% of root coverage. In one of the patients who obtained only 50% of root coverage, the reason was found to be overzealous brushing. In the rest of the patients, who did not attain complete coverage, the maintenance of the site was fair to poor, which probably led to reduced coverage.
The mean recession height reduction of 2.84 mm obtained in this study is comparable with the results obtained by Borghetti et al .,  Lee et al .,  and Carvalho da Silva et al .  The mean recession width reduction of 2.63 mm from baseline is statistically significant ( P < 0.05) and is consistent with the finding in the study done by Trombelli et al . 
Modification of the apico-coronal dimensions of the mucogingival complex appears to be common following periodontal plastic surgery. Several surgical procedures have been proposed and practiced to increase the width and thickness of keratinized gingival tissue in order to assist proper plaque control and prevent further recession of the gingival margin.
In our study, there is an increase in the width of keratinized gingiva from baseline to the third month, i.e., from 3.06 to 5.18 mm. This increase in width decreased to 5.12 mm at the end of the study (sixth month). The mean gain in width of keratinized gingiva from baseline to the end of the sixth month was 2.06 mm, which is statistically significant ( P < 0.05) and correlates well with the studies done by Borghetti et al .,  Lee et al .,  and Harris et al .  It is commonly believed that a CTG would contribute to keratinization of the overlying epithelium.
The mean pocket depth reduction of 0.31 mm from baseline is statistically significant ( P < 0.05). The results obtained in this study are consistent with the studies done by Paolantonio et al .,  Carvalho da Silva et al .,  and Trombelli et al . 
Clinically, it was difficult to penetrate the sulcus with a probe. There was also no bleeding on probing. These clinical findings are compatible with a healthy attachment.
The mean gain in clinical attachment level was 3.25 mm from baseline, which is statistically significant ( P < 0.05). Thus, the gain in clinical attachment level in this study correlates well with the results obtained in the studies done by Lee et al .  and Rosetti et al . 
In this study, modifications of the surgical technique were made in two patients (not included in the statistical analysis). In one of the patients, a laterally displaced flap with a CTG was used to cover the recession defect, and in another patient, the CTG was covered with a double papilla pedicle graft. At the end of 6 months, there was good root coverage in both the patients.
SCTG yielded excellent color and tissue blending. Only one patient had enlarged marginal gingiva and required gingivoplasty.
Harris, in his study, found areas of regeneration, with new bone, cementum, and connective tissue attachment, in a case successfully treated with SCTG.  This report confirms that regeneration is possible with SCTG. To find out the type of attachment that is formed would require the removal of a successfully treated tooth. However, this type of histological examination was beyond the scope of this study.
Even though, Breault et al .  reported a "surgical cyst" developing secondary to an SCTG and Vastardis et al .  reported "abscess" formation as a complication of SCTG, no such complication was encountered in any of the patients who participated in this study.
Recent evidence also suggests that among all the plastic surgical procedures for root coverage, SCTG remains the most effective. 
Within its limitations, the results of this study demonstrate that SCTG is an effective technique to obtain root coverage.
| Summary and Conclusion|| |
The present study indicates that the SCTG (CTG with a coronal advancement pedicle) is an effective method to cover exposed roots. If optimal maintenance care is provided, the clinical outcome gained by this technique can be long lasting.
From the present study, the following conclusions can be made:
- SCTG is a safe and effective method for treatment of gingival recession.
- A statistically significant coverage (87.5%) was obtained.
- The root coverage obtained improved the esthetics and met the expectations and demands of the patients, as also that of the treating surgeon.
- No complications were encountered in any patient who participated in this study.
The results should be interpreted with due consideration given to the relatively small sample size (n = 16) and the short evaluation period (6 months).
The results of this study thus demonstrate that SCTG is an effective technique to obtain root coverage. Hence, SCTG should be considered whenever root coverage is desired.
| References|| |
|1.||Hirschfeld I. Toothbrush trauma recession: A clinical study. J Dent Res 1986;11:61-3. |
|2.||Agudio G, Pini Prato G, Cortellini P, Parma Benfenati. Gingival lesions caused by improper oral hygiene measures. Int J Periodontics Restorative Dent 1987;7:52-65. |
|3.||Hirschfeld I. A Study of skulls in the American Museum of natural history in relation to periodontal disease. J Dent Res 1923;5:241-6. |
|4.||Boyd RL. Mucogingival consideration and their relationship to orthodontics. J Periodontol 1978;49:67-76. |
|5.||Trossello VK, Gianelly AA. Orthodontic treatment and periodontal status. J Periodontol 1979;50:665-71. |
|6.||Santarelli G. Connective tissue grafting employing the tunnel technique: A case report of complete root coverage in the anterior maxilla. Int J Periodontics Restorative Dent 2001;21:77-83. |
|7.||Roccuzzo M, Bunino M, Needleman I, Sanz M. Periodontal plastic surgery for the treatment of localized gingival recession: A systematic review. J Clin Periodontol 2002;29:178-94. |
|8.||Paolantonio M, Di Murro C, Cattabriga A. Subpedicle connective tissue graft versus free gingival graft in the coverage of exposed root surfaces: A 5 year clinical study. J Clin Periodontol 1997;24:51-6. |
|9.||Nelson S. The Subpedicle connective tissue graft, A bilaminar reconstructive procedure for the coverage of denuded root surfaces. J Periodontol 1987;58:95-102. |
|10.||Edel A. Clinical evaluation of free connective tissue grafts used to increase the width of keratinized gingival. J Clin Periodontol 1974;2:185-96. |
|11.||Staffileno H. Significant differences and advantages between the full thickness and split thickness flaps. J Periodontol 1974;45:421-5. |
|12.||Wilcko MT, Wilcko WM, Murphy KG, Carroll WJ, Ferguson DJ, Miley DD, et al . Full-thickness flap/Subepithelial Connective tissue Grafting with intramarrow penetrations: Three case reports of lingual root coverage. Int J Periodontics Restorative Dent 2005;25:561-9. |
|13.||Hokett SD, Peacock ME, Burns WT, Swiec GD, Cuenin MF. External Root Resorption following partial thickness connective tissue placement: A case report. J Periodontol 2002;73:334-9. |
|14.||Muller HP, Eger T, Schorb A. Alterations of gingival dimensions in a complicated case of gingival recession. Int J Periodontics Restorative Dent 1998;18:345-53. |
|15.||Caffesse RG, La Rosa M, Garza M, Travers AM, Mondragon J, Weltman R. Citric acid demineralization and subepithelial connective tissue graft. J Periodontol 2000;71:568-72. |
|16.||Bouchard P, Etienne D, Ouhayoun JP, Nilveus R. Subepithelial connective tissue grafts in the treatment of gingival recessions: A comparative study of 2 procedures. J Periodontol 1994;65:929-36. |
|17.||Ben Yehouda A. Progressive cervical root resorption related to tetracycline root conditioning. J Periodontol 1997;68:432-5. |
|18.||Liu CL, Weisgold AS. Connective tissue graft: A classification for incision design from the palatal site and clinical case reports. Int J Periodontics Restorative Dent 2002;22:373-9. |
|19.||Mohammed S, Nabil FB, Anthony JF. Benton cole: Effect of connective tissue graft orientation on root coverage and gingival augmentation. Int J Periodont Restorative Dent 2004;24:65-9. |
|20.||Pini Prato GP, Baldi C, Nieri M, Franseschi D, Cortellini P, Clauser C, et al . Coronally advanced flap: The post surgical position of the gingival margin is an important factor for achieving complete root coverage. J Periodontol 2005;76:713-22. |
|21.||Borghetti A, Louise F. Controlled clinical evaluation of the subpedicle connective tissue graft for the coverage of gingival recession, J Periodontol 1994;65:1107-12. |
|22.||Harris RJ. Connective tissue grafts combined with either double pedicle grafts or coronally positioned pedicle grafts: Results of 266 consecutively treated defects in 200 patients. Int J Periodont Restorative Dent 2002;22:463-71. |
|23.||Tozum TF, Keceli HG, Guncu GN, Hatipoglu H, Sengun D. Treatment of gingival recession: Comparison of two techniques of subepithelial connective tissue graft. J Periodontol 2005;76:1842-8. |
|24.||Zabalegui I, Sicilia A, Cambra J, Gil J, Sanz M. Treatment of multiple recessions with the tunnel subepithelial connective tissue graft: A clinical report. Int J Periodontics Restorative Dent 1999;19:199-206. |
|25.||Newman MG, Takei HH, Klokkevold PR, Carranza FA. Carranza's clinical periodontolgy. 10 th ed. Elseviers Publishers: 2006. p. 1022. |
|26.||Paolantonio M, Dolci M, Esposito P, Archivio D, Lisanti L, Diluccio A, et al . Subpedicle Acellular dermal matrix graft and autogenous connective tissue graft in the treatment of gingival recessions: A comparitive one year clinical study. J Periodontol 2002;73:1299-307. |
|27.||Borghetti A, Glise JM, Virgiene MC, Jacques D. A comparative clinical study of bioabsorbable membrane and SCTG in the treatment of human gingival recession. J Periodontol 1999;70:123-30. |
|28.||Lee YM, Kim JY, Lee YK, Han SB, Choi SM, Chung CP. A one year longitudinal evaluation of subpedicle free connective tissue graft for gingival recession coverage. J Periodontol 2002;73:1412-8. |
|29.||Carvalho da silva R, Joly JC, Martorelli de lima AF, Tatakis DN. Root coverage using the coronally positioned flap with or without a subepithelial connective tissue graft. J Periodontol 2004;75:413-9. |
|30.||Trombelli L, Scabbia A, Tatakis D, Calura G. Subpedicle connective tissue graft vs GTR with bioabsorbable membrane in the treatment of human gingival recession defects. J Periodontol 1998;69:1271-7. |
|31.||Harris RJ. A comparative study of root coverage obtained with an acellular dermal matrix vs a connective tissue graft: Results of 107 recession defects in 50 consecutively treated patients. Int J Periodontics Restorative Dent 2000;20:51-9. |
|32.||Rosetti EP, Marcantonio RC, Rossa C, Chaves Eros S, Gilberto G, Marcantonio E. Treatment of gingival recession-comparative study between SCTG and GTR. J Periodontol 2000;71:1441-7. |
|33.||Harris RJ. Successful root coverage: A human histologic evaluation of a case. Int J Periodontics Restorative Dent 1999;19:439-47. |
|34.||Breault LG, Billman MA, Lewis DM. Report of a gingival „surgical cyst" developing secondarily to a subepithelial connective tissue graft. J Periodontol 1997;68:392-5. |
|35.||Vastardis S, Yukna R. Gingival/soft tissue abscess following subepithelial connective tissue graft for root coverage: Report of three cases. J Periodontol 2003;74:1676-81. |
R S Ahathya
Department of Periodontology and Implantology, Meenakshiammal Dental College and Hospital, Alapakkam Main Road, Maduravoyal, Chennai - 600 095, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]
[Table - 1]