|Year : 2020 | Volume
| Issue : 2 | Page : 112-118
Clinical evaluation of autologous platelet-rich fibrin and perioglas® in treating periodontal intrabony defects
Shravanthi Raghav Yajamanya, Anirban Chatterjee
Department of Periodontology and Oral Implantology, The Oxford Dental College, Bengaluru, Karnataka, India
|Date of Submission||18-Aug-2020|
|Date of Decision||15-Sep-2020|
|Date of Acceptance||25-Sep-2020|
|Date of Web Publication||11-Feb-2021|
Dr. Shravanthi Raghav Yajamanya
Department of Periodontology and Oral Implantology, The Oxford Dental College, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Context: This study was conducted to compare autologous platelet-rich fibrin (PRF) with PerioGlas® in treating periodontal intrabony defects (IBDs) of variable number of walls, based on clinical and radiographic outcomes. Aim: The aim of the study was to assess which regenerative material, i.e., autologous PRF or PerioGlas®, has a broader range of applicability in treating periodontal IBDs. Settings and Design: This study is a randomized controlled trial conducted at the Department of Periodontology and Oral Implantology of the Oxford Dental College and Hospital, Bangalore, India. Methods: Sixty IBDs were provided nonsurgical periodontal treatment, i.e., scaling and root planing, followed by oral hygiene instructions. When performing periodontal surgery, the IBDs were assigned to the Control group (i.e., access flap alone), test Group I (i.e., access flap + (PerioGlas®), and test Group II (i.e., access flap + autologous PRF). The vertical bone defects in three groups consisted of 3-, 2-, and 1-wall intrabony periodontal defects. Radiographic assessments were performed at baseline and 6 and 9 months. Statistical Analysis Used: Statistical analysis was based on the mean values, standard deviation, and P values. Results: Mean defect depth fill compared to baseline and 9 months postoperatively for: (1) 3-wall IBDs: Control group was 6.50 ± 1.56 mm, test Group I was 9.27 ± 1.62 mm, and test Group II was 10.45 ± 2.33 mm, (2) 2-wall IBDs: Control group was 6.08 ± 0.62 mm, test Group I was 8.21 ± 1.58 mm, and test Group II was 8.96 ± 1.85 mm, and (3) 1-wall IBDs: Control group was 5.78 ± 1.07 mm and test Group II was 8.00 ± 0.69 mm. Conclusion: Autologous PRF has a wider applicability in case of various types of IBDs as compared to PerioGlas® owing to its mechanism of action and composition which is the presence of various growth factors and cytokines.
Keywords: Autologous platelet-rich fibrin, bioactive glass (PerioGlas®), periodontal intrabony defects, scaling and root planing
|How to cite this article:|
Yajamanya SR, Chatterjee A. Clinical evaluation of autologous platelet-rich fibrin and perioglas® in treating periodontal intrabony defects. Niger J Exp Clin Biosci 2020;8:112-8
|How to cite this URL:|
Yajamanya SR, Chatterjee A. Clinical evaluation of autologous platelet-rich fibrin and perioglas® in treating periodontal intrabony defects. Niger J Exp Clin Biosci [serial online] 2020 [cited 2021 May 12];8:112-8. Available from: https://www.njecbonline.org/text.asp?2020/8/2/112/309169
| Introduction|| |
Frequent anatomical sequelae to periodontitis are periodontal osseous lesions associated with deep pockets.
The various determining factors on results of periodontal osseous defect treatment are plaque control, smoking, diabetes, genetics, age, operative skill, surgical approach, devices used, root surface preparation, and site characteristics (such as pulpal status, occlusion, defect morphology, and tooth anatomy). Among local factors that may influence the result of regenerative therapy, occlusion and morphology of the bone defect have been the most studied.
Periodontal osseous lesions are presented either in the form of a horizontal or vertical pattern of bone loss. The type of vertical bone loss (such as 3-, 2-, and 1-wall defects, craters, funnel-shaped defects, those associated with furcations, and combined defects) influences the positive clinical outcomes.
In clinical practice, the use of various materials such as autologous platelet-rich fibrin (PRF) and bioactive glass with access flap surgery has been considered to achieve the goal of periodontal regeneration.
Bioactive glasses were developed by Dr. Hench and have the ability to bind to the tissues (1969) and have the ability to bind to the tissues. Bioglass TM (45S5) acquired the Food and Drug Administration (FDA) approval and is now being used for bone grafting intraorally. The composition of 45S5 bioactive glass is SiO2 (46.1 mol%), CaO (26.9 mol%), Na2O (24.4 mol%), and P2O5 (2.6 mol%).
45S5 tissue binding is seen in < 2 h by hydroxycarbonated apatite formation. FDA in 1993 cleared PerioGlas® for restoring periodontal disease-related bone loss in infrabony defects.
Autologous PRF could improve periodontal osseous defects healing because of properties like upregulation of phosphorylated extracellular signal-regulated protein kinase expression and suppression of osteoclastogenesis by promoting the secretion of osteoprotegerin in osteoblasts cultures, stimulation of osteogenic differentiation of human dental pulp cells by upregulating osteoprotegerin and alkaline phosphatase expression, and release of platelet-derived growth factor (PDGF) and transforming growth factor.
This study was conducted to compare the efficacy of PerioGlas® with autologous PRF in treating the intrabony defects (IBDs) of various types.
| Methods|| |
This was an intervention study.
This was an in vivo study.
Study design and sampling technique
Patients reporting to the Department of Periodontology and Oral Implantology of the Oxford Dental College and Hospital, Bangalore, India, were assessed for the periodontal probing depths and periodontal defect morphology using UNC 15 periodontal probe and RadioVisioGraphy. Periodontal treatment was started by providing 60 IBDs [Table 1] with phase I periodontal therapy which included scaling and root planing (SRP) followed by oral hygiene instructions. For periodontal surgery, the IBDs were assigned to the Control group (access flap alone), test Group I (access flap + (PerioGlas®), and test Group II (access flap + Autologous PRF). Acrylic stent was used for recording the clinical parameters at baseline and 3, 6, and 9 months.
Ethical clearance was obtained. Furthermore, informed consent obtained from all the patients included in the study.
Inclusion criteria included (1) minimum twenty permanent teeth, (2) age group of 20–55 years, (3) chronic periodontitis patients, (4) radiographic evidence of periodontal IBDs, and (5) periodontal pocket depth >5 mm.
Exclusion criteria included (1) Grade III tooth mobility and systemically compromised patients, (2) those on corticosteroids/bisphosphonate therapy, (3) smokers, (4) alcoholics, (5) pregnant and lactating mothers, and (6) patients who underwent periodontal treatment within a period of 1 year.
After nonsurgical periodontal therapy, periodontal evaluation was performed after 4 weeks. Persistence of ≤5 mm pocket depth [Figure 1] with radiographic evidence of bone loss was assigned to either Control group (access flap surgery alone), test Group I (access flap surgery + (PerioGlas®), and test Group II (access flap surgery + Autologous PRF) when performing periodontal access flap surgery based on direct visualization and exploring the number of walls, depth, and width of the IBD using UNC 15 probe after the periodontal full-thickness flap reflection.
|Figure 1: Probing pocket depth measurement just before starting the access flap surgery|
Click here to view
Step 1– 2% lignocaine HCL with adrenaline 1:80,000 local anesthesia was administered. Step 2 – Crevicular incisions were placed and full-thickness mucoperiosteal flaps both on buccal and palatal/lingual sides were reflected. Step 3 – Gracey curettes and ultrasonic scaler were used to remove granulation tissue, calculus, and any residual debris.
In case of 1 wall IBDs allotted to Control group and Test group II, step 3 included- limiting granulation tissue removal such that, the granulation tissue which was left behind in the IBD did not compromise thorough visualization of plaque and calculus during the process of complete elimination of plaque, calculus and residual debris.
In case of Control group
After Step 3, the surgical site was thoroughly inspected for residual calculus and debris if any and then the periodontal flaps were secured with 3-0 silk sutures to the same level as they were presurgically.
In case of test Group I
After Step 3, IBD site was thoroughly inspected and then was presutured (it is placing sutures loose and leaving them untied prior to the placement of the graft material in the IBD to reduce the chances of graft material displacement. Once the graft material is placement is complete, the final suturing process includes just tying the already placed sutures to complete the surgical procedure) using 3-0 silk suture and a mixture of PerioGlas® with patient's own blood was placed in the IBD.
In case of test Group II
After Step 3 [Figure 2], the IBD site was thoroughly inspected and was presutured using 3-0 silk suture and PRF clot, with its red blood cell (RBC) layer coming in contact with the base of the IBD site being placed.
|Figure 2: After debridement, autologous platelet-rich fibrin was placed in the intrabony defect distal to tooth no. 36|
Click here to view
Method of obtaining autologous PRF clot – antecubital vein was venipunctured. This blood was immediately transferred into a 10 ml disposable vacuum test tube without anticoagulant and centrifuged in a centrifugation machine at 3000 rpm for 10 min. After blood centrifugation PRF is obtained in the middle of the tube, with RBCs at the bottom and acellular plasma at the top. PRF was transferred in a sterile dappen dish by preserving a small RBC layer using a sterile tweezers and scissors [Figure 3].
The treated sites in all the three groups were covered with the periodontal dressing.
Postoperative instructions were given. Patients were prescribed amoxicillin 500 mg capsule for 5 days, three times daily, and diclofenac sodium 50 mg tablet for 3 days, thrice a day. Sutures removal was done after 7 days.
Recall was performed at 6 and 9 months [Figure 4].
Radiographic assessment was done using RadioVisioGraphy and AutoCAD software [Figure 5] and [Figure 6].
|Figure 5: Postoperative RadioVisioGraphy (RVG) – parallel lines showed the base of the defect and crest of alveolar bone|
Click here to view
|Figure 6: Postoperative RVG – parallel lines showed the base of the defect and crest of alveolar bone|
Click here to view
Descriptive statistical analysis was carried out in the present study. The results on continuous measurements were presented on mean and standard deviation (SD). Significance was assessed at 5% level of significance. The following assumptions on data were made.
(1) Dependent variables should be normally distributed. (2) Samples drawn from the population should be random. (3) Cases of the samples should be independent. Student's t-test (paired and unpaired) was used to find the significance of the study parameters on continuous scale within each group.
Sample size estimation
Proportion known populations:
n = ([z2 × p × q] + ME2)/(ME2 + z2 × p × q/N)
ME: is the margin of error, measure of precision; Z is 1.96 as critical value at 95% confidence interval.
N: population size; n: Sample size; σ: SD; z: Critical value based on normal distribution at 95%.
| Results|| |
Compared to baseline, 3 months postoperatively after periodontal surgery, the mean probing pocket depth reduction results were for:
- Control Group: 1.02 mm ± 0.72
- Test Group I: 3.49 mm ± 1.08
- Test Group II: 3.60 mm ± 0.84.
Compared to baseline, 6 months postoperatively after periodontal surgery, the mean probing pocket depth reduction results were for:
- Control Group: 2.07 mm ± 0.75
- Test Group I: 4.67 mm ± 1.10
- Test Group II: 4.89 mm ± 0.78.
Compared to baseline, 9 months postoperatively after periodontal surgery, the mean probing pocket depth reduction results were for
- Control Group: 3.07 mm ± 0.69
- Test Group I: 5.40 mm ± 1.06
- Test Group II: 5.90 mm ± 0.81.
From the above values, it can be concluded that from baseline to 3, 6, and 9 months of periodontal surgery, there was a statistically significant reduction of probing pocket depth in case of both test Groups I and II as compared to the Control group (P < 0.05). However, the reduction in probing pocket depth was statistically insignificant when test Groups I and II results were compared (P > 0.05).
Relative attachment level
Compared to baseline, 3 months postoperatively after periodontal surgery, the mean relative attachment level (RAL) gain results were for:
- Control Group: 2.20 mm ± 0.60
- Test Group I: 3.36 mm ± 1.10
- Test Group II: 3.43 mm ± 1.86.
Compared to baseline, 6 months postoperatively after periodontal surgery, the mean RAL gain results were for:
- Control Group: 3.18 mm ± 0.65
- Test Group I: 4.08 mm ± 1.28
- Test Group II: 4.50 mm ± 1.12.
Compared to baseline, 9 months postoperatively after periodontal surgery, the mean RAL gain results were for:
- Control Group: 3.49 mm ± 0.58
- Test Group I: 4.44 mm ± 1.38
- Test Group II: 5.10 mm ± 1.48.
From the above values, it can be concluded that from baseline to 3, 6, and 9 months of periodontal surgery, there was a statistically significant gain of RAL in case of both test Groups I and II as compared to the Control group (P < 0.05). However, the gain in RAL was statistically insignificant when test Groups I and II results were compared (P > 0.05).
For each surgical site, RadioVisioGraphy and long-cone paralleling technique were used. Radiographic images were saved to the computer in the JPEG image form.
Radiographs were used to make the following calculations
Amount of defect fill = initial defect depth–defect depth at a recalled time interval. Percentage (%) of defect fill = Amount of defect fill/baseline defect depth × 100.
Bone defect depth was measured at baseline and 6 and 9 months.
Based on this study results, it can be concluded that from baseline to 6 and 9 months, defect fill was best with autologous PRF (test Group II), followed by PerioGlas® (test Group I) and then access flap alone (control group) for 3- and 2-wall IBDs, P < 0.05 [Table 2] and [Table 3]. For 1-wall IBDs, from baseline to 6 and 9 months, defect fill was best with autologous PRF (test Group II) as compared to access flap alone (Control group), P < 0.05 [Table 4]. Furthermore, the influence of 3-wall IBDs was maximum in defect depth reduction combined with autologous PRF.
| Discussion|| |
In this study, 1-wall periodontal IBDs were allotted to either Control group (access flap alone) or test Group II (access flap and autologous PRF) and 3-wall and 2wall periodontal IBDs were allotted to either Control group (access flap alone) or test Group I (access flap and PerioGlas®), or test Group II (access flap and autologous PRF).,
For 2-wall and 3-wall IBDS, from baseline to 9 months, all the three groups showed clinical and radiographic improvements. Both test Group I and test Group II showed statistically significant improvements as compared to the Control group. However, when the results of test Groups I and II were compared, autologous PRF showed slightly better outcomes than PerioGlas® though not statistically significant. Furthermore, this study is in accordance with the studies which conclude that 3- and 2-wall IBDs show greater potential for regeneration than 1-wall IBDs.,
In case of 1-wall IBDs, Control group and test Group II treatment options showed improvements from baseline to 9 months. However, test Group II provided far better results as compared to the Control group.
The improvement in clinical and radiographic parameters can be attributed to the beneficial effects of both bioactive glass (PerioGlas®) and autologous PRF. Thus, this study is in accordance with the conclusion of a systematic review that the use of specific biomaterials/biologicals was more effective than access flap alone in improving attachment levels in intraosseous defects.
Bioactive glass was chosen for this study as compared to other alloplastic materials due to its ability to bond to both soft tissues and bone (Hench et al. 1971) and soft tissues, significantly less junctional epithelium migration at the treated IBD sites and ease of handling and manipulation. Autologous PRF was the other promising biomaterial chosen for this study as compared to other platelet concentrates like platelet-rich plasma, owing to its properties like reduced biochemical handling of blood and reduced risks associated with using bovine-derived thrombin and its fibrin architecture obtained due to slow polymerization process which is very favorable to the healing process.
However, in terms of a range of applicability (i.e., 3-, 2-, and 1-wall periodontal IBDs), in this study, we observed that autologous PRF was a preferred regenerative material as compared to PerioGlas®.
Reasons for choosing autologous PRF over bioactive glass (PerioGlas®) in 1-wall periodontal IBDs were (1) this biomaterial may not require physical support and containment offered by the bone walls, which otherwise is one prerequisite for using bioactive glass, (2) bioactive glass (PerioGlas®) may show limited regenerative outcome of 1-wall IBDs considering first, the concept that decreased number of bone walls affects the availability of vascular and cellular elements required to regenerate the IBD and second, the mechanism of action of bioactive glass (PerioGlas®) is osteostimulative and osteoconductive only and hence, in case of 1-wall IBDs, the recipient site being only one bony wall, limits the availability of native bone cells and thus may compromise the clinical outcomes, (3) however, unlike PerioGlas®, autologous PRF has an inherent osteoconductive and/or osteoinductive property which benefits bone regeneration and the mechanism by which autologous PRF act is by directly leading to angiogenesis due to three-dimensional structure of fibrin gel, action of trapped cytokines in the fibrin mesh, fibrin binding of growth factors like basic fibroblast growth factor, vascular endothelial growth factor, angiopoietin, and PDGF; trapping the circulating stem cells brought to the injured site due to initial neovascularisation; and the presence of leukocytes enabling self-regulation of infectious and inflammatory processes thus, acting as an adjunct to the natural healing process, and (4) healing of wide osseous defects requires medullar stem cell accumulation and their conversion to osteoblast phenotype. For obtaining osseous defect regeneration, the fibrin matrix of autologous PRF is seen to provide an optimal support to transplanted mesenchymal stem cells.,
According to recent study results, infected granulation tissue is seen to contain pluripotent stem cells which contribute to healing of the gingival tissue, also the granulation tissue obtained from the IBDs during surgery contains mesenchymal stem cell populations. Thus, going by the understanding that, removal of granulation tissue during periodontal flap surgery is not critical for efficient healing of periodontal tissues, we felt it was important to revisit the practice of complete removal of granulation tissue, especially in one wall IBDs cases during periodontal surgery once the infection was controlled by thorough SRP.
Thus, the dual effect of the presence of mesenchymal stem cells from the granulation tissue and the ability of the well-organized fibrin matrix of autologous PRF to efficiently direct stem cell harnessing and accelerate physiologic healing phenomenon may reason out the statistically significant outcomes of test Group II (access flap and autologous PRF) as compared to Control group (access flap alone) when treating the 1-wall IBDs in our study.
| Conclusion|| |
The present study demonstrated that, in the treatment of periodontal IBDs, using regenerative materials either PerioGlas® or autologous PRF with access flap shows better results than access flap alone.
Clinical and radiographic outcomes for autologous PRF when used along with access flap showed better results than PerioGlas® when used along with access flap in treating 3- and 2-wall periodontal IBDs though statistically insignificant.
In terms of a range of applicability in different types of periodontal IBDs, autologous PRF was found to be superior to bioactive glass (PerioGlas®).
To the best of our knowledge, this is one of its kind study which tries to assess the efficacy of autologous PRF and PerioGlas® in treating 3-, 2-, and 1-wall periodontal IBDs based on the clinical and radiographic parameters.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Papapanou PN, Tonetti MS. Diagnosis and epidemiology of periodontal osseous lesions. Periodontol 2000 2000;22:8-21.
Kornman KS, Robertson PB. Fundamental principles affecting the outcomes of therapy for osseous lesions. Periodontol 2000 2000;22:22-43.
Schallon RA. Diagnosis and management of vertical bone defects in periodontal disease. Gen Dent 2012;60:290-7.
Hench LL. The story of BioGlass. J Mater Sci Mater Med 2006;17:967-78.
Paolinelis G, Banerjee A, Watson TF. An in vitro
investigation of the effect and retention of bioactive glass air-abrasive on sound and carious dentine. J Dent 2008;36:214-8.
Kobayashi M, Saito H, Mase T, Sasaki T, Wang W, Tanaka Y, et al
. Polarization of hybridized calcium phosphoaluminosilicates with 45S5-type bioglasses. Biomed Mater 2010;5:25001.
Imran F, Zonera I, Umer F, Leghari A, Humera A. Bioactive glass: A material for the future. WJD 2012;3:199-201.
Hench LL, Hench JW, Greenspan DC. Bioglass A Short History and Bibliography. J Aust Ceram Soc 2004;40:1-42.
Chang IC, Tsai CH, Chang YC. Platelet-rich fibrin modulates the expression of extracellular signal-regulated protein kinase and osteoprotegerin in human osteoblasts. J Biomed Mater Res A 2010;95:327-32.
Huang FM, Yang SF, Zhao JH, Chang YC. Platelet-rich fibrin increases proliferation and differentiation of human dental pulp cells. J Endod 2010;36:1628-32.
Dohan DM, Choukroun J, Diss A, Dohan SL, Dohan AJ, Mouhyi J, et al
. Platelet-rich fibrin (PRF): A second-generation platelet concentrate. Part II: Platelet-related biologic features. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101:e45-50.
Dohan DM, Del Corso M, Charrier JB. Cytotoxicity analyses of Choukroun's platelet-rich fibrin (PRF) on a wide range of human cells: The answer to a commercial controversy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:587-93.
Subbaiah R, Thomas B. Efficacy of a bioactive alloplast, in the treatment of human periodontal osseous defects-a clinical study. Med Oral Patol Oral Cir Bucal 2011;16:e239-44.
Chacko NL, Abraham S, Rao HN, Sridhar N, Moon N, Barde DH. A clinical and radiographic evaluation of periodontal regenerative potential of PerioGlas®
: A synthetic, resorbable material in treating periodontal infrabony defects. J Int Oral Health 2014;6:20-6.
Rosamma Joseph V, Raghunath A, Sharma N. Clinical effectiveness of autologous platelet rich fibrin in the management of infrabony periodontal defects. Singapore Dent J 2012;33:5-12.
Panda S, Sankari M, Jayakumar ND, Varghese S. Additive effect of platelet rich fibrin in treatment of Intrabony defects- A systematic review and meta-analysis. JPR: Bio Med Rx An Int J 2013;1:700-6.
Reynolds MA, Kao RT, Nares S, Camargo PM, Caton JG, Clem DS, et al
. Periodontal regeneration – Intrabony defects: Practical applications from the AAP regeneration workshop. Clin Adv Periodontics 2015;5:21-29.
Kim CS, Choi SH, Chai JK, Cho KS, Moon IS, Wikesjö UM, et al
. Periodontal repair in surgically created intrabony defects in dogs: Influence of the number of bone walls on healing response. J Periodontol 2004;75:229-35.
Trombelli L, Heitz-Mayfield LJ, Needleman I, Moles D, Scabbia A. A systematic review of graft materials and biological agents for periodontal intraosseous defects. J Clin Periodontol 2002;29 Suppl 3:117-35.
Wilson J, Noletti D, “Bonding of Soft Tissues to Bioglass”, in Handbook of Bioactive Ceramics vol. 1: Bioactive Glasses and Glass-Ceramics, edited by T. Yamamuro, L.L. Hench and J. Wilson (CRC Press, Boca Raton, Florida, 1990).
Fetner AF. Manigan MS, Low SH. Periodontal repair using Perioglas in nonhuman primates: Clinical and histologic observations. Compendium Com Educ Dent 1994:15:912-39.
Sunitha Raja V, Munirathnam Naidu E. Platelet-rich fibrin: Evolution of a second-generation platelet concentrate. Indian J Dent Res 2008;19:42-6.
Hu YC, Zhong JP. Osteostimulation of bioglass. Chin Med J (Engl) 2009;122:2386-9.
Chandran P, Shivdas A. Platelet rich fibrin and its role in periodontal regeneration. Saudi J Oral Dent Res 2014;5:117-22.
van Hinsbergh VW, Collen A, Koolwijk P. Role of fibrin matrix in angiogenesis. Ann N Y Acad Sci 2001;936:426-37.
Khiste SV, Tari RN. Platelet-rich fibrin as a biofuel for tissue regeneration. ISRN Biomaterials 2013;2013:1-6.
Choukroun J, Diss A, Simonpieri A, Girard MO, Schoeffler C, Dohan SL, et al
. Platelet-rich fibrin (PRF): A second-generation platelet concentrate. Part IV: Clinical effects on tissue healing. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101:e56-60.
Bensaïd W, Triffitt JT, Blanchat C, Oudina K, Sedel L, Petite H. A biodegradable fibrin scaffold for mesenchymal stem cell transplantation. Biomaterials 2003;24:2497-502.
Yamada Y, Boo JS, Ozawa R, Nagasaka T, Okazaki Y, Hata K, et al
. Bone regeneration following injection of mesenchymal stem cells and fibrin glue with a biodegradable scaffold. J Craniomaxillofac Surg 2003;31:27-33.
Ronay V, Belibasakis GN, Schmidlin PR, Bostanci N. Infected periodontal granulation tissue contains cells expressing embryonic stem cell markers. A pilot study. Schweiz Monatsschr Zahnmed 2013;123:12-6.
Hung TY, Lin HC, Chan YJ, Yuan K. Isolating stromal stem cells from periodontal granulation tissues. Clin Oral Investig 2012;16:1171-80.
Lindhe J, Nyman S. Scaling and granulation tissue removal in periodontal therapy. J Clin Periodontol 1985;12:374-88.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]