Root biomodification

Dr Deepu Mathews
Associate Professor
Malabar Dental College & Research Centre

1. ROOT BIOMODIFICATION 1

2. Deepu Mathews Associate Professor Malabar Dental College & Research Centre Manoor - Chekanoor Road, Manoor , Edappal , Kerala 679582 https://macity.edu.in/

3. Introduction The removal of bacterial deposits, arrest of periodontal disease and regeneration of periodontal tissues that are lost due to the disease process constitute the ideal and main goal in periodontal therapy . Thus , biocompatibility of root surface is of extreme importance for achieving success of periodontal therapy . 3

4. T he oldest and most frequently attempted type of periodontal regeneration, has involved chemical modification of tooth surface. The goal of this regeneration procedure is to determine the alterations in the diseased root surface that would create an appropriate and hospitable surface for cell attachment and eventual development of a fibre attachment. 4

5. Hence root biomodification procedures have been introduced by using a variety of agents, in order to detoxify, decontaminate and demineralize the root surface, thereby removing the smear layer and exposing the collagenous matrix of dentin and cementum 5

6. HISTORICAL BACKGROUND In 1833, Marshall presented a case of pocket eradication with “presumable clinical reattachment” after the use of aromatic sulfuric acid. In the 1890s; Stewart described the use of acids in conjunction with the mechanical removal of calculus and cementum . Urist (1965) that suggested that dentin following acid demineralization possessed inductive properties. 6

7. Urist (1973) demonstrated in a series of experiments that allogenic dentin matrix, following partial or total demineralization with O.6N HCl and transplanted in vivo in various animal models, possessed the ability to induce the formation of new bone or cementum . 7

8. Register et al., in (1973 ) performed the first controlled study on the use of acid on root surfaces. They investigated whether new attachment,cementogenesis and osteogenesis could be induced adjacent to tooth roots demineralized in vivo. Optimal cementogenesis and new connective tissue attachment occurred when roots were demineralized with citric acid, pH 1.0 for 2 -3min. 8

9. Root Biomodification Root biomodification is a periodontal regenerative procedure which involves chemical or mechanical modification of root surface . 9

10. Rationale : Root debriment generates a smear layer which contains micro-organisms & toxins, that interfere in periodontal healing . Acid treatment causes demineralization of root planed dentin Exposes collagen fibrils of dentin matrix Help in adhesion of blood clot to root surface & favor migration of fibroblasts Thus, the use of an agent to remove this smear layer and to expose the collagen fibers is an important factor to obtain biologically acceptable tooth surfaces . 10

11. Various Chemical Agents Used For Root Biomodification : Citric Acid Tetracycline Fibronectin EDTA-(Ethylene Diamine Tetra Acetic Acid.) Sodium Deoxycholate Human Plasma Fraction Growth Factor 11

12. Miscellaneous - Aqueous Ethyl Ether Lithium Aluminum Hydride Bile Salts Calcium Chelators Physical : Laser 12

13. Mechanical modification of root surface involves scaling and root planing . This includes removal of cementum removal of softened dentin, or the smoothening of surface irregularities.However such root modification may not completely remove contaminated cementum particularly in apical areas. A smear layer will inevitably cover the instrumented surface. 13

14. I-Citric Acid Most common chemical agent used for root biomodification . Citric Acid conditioning is based on the premise that- Demineralizies the root surface Expose the collagen fibers Forms a barrier against epithelial migration Removal of smear layer formed by Instrumentation 14

15. REGISTER & BURDICK (1976) Performed series of studies that showed- Citric Acid at 1 PH, when applied for 2-3 minutes on root surface causes:- 1) Surface demineralization 2)Induces cementogenesis & attachment of collagen fibers. He suggested that “It contains two or more groups in its molecule which can combine with calcium and act as chelating agent. It can participate in surface exchange; with citric ions replacing phosphate ions in the hydroxyapatite crystals. Citric acid acts on dentinal hydroxyapatite by releasing hydrogen ions which demineralizes the crystalline structure. 15

16. Mechanism of Action : 1. Antibacterial effect 2. Root detoxification 3. Exposure of root collagen 4. Removal of smear layer 5. Initial clot stabilization 6. Demineralization prior to cementogenesis 7. Enhanced fibroblasts growth 8. Attachment by direct linkage with or without cementogenesis 9. Prevent epithelial migration along denuded root surface 10. Accelerated healing and new cementum attachment 16

17. Recommended Technique : - By Register & Burdick (1975) ( i ) Raise a mucoperiosteal flap (ii) Throughly instrument the root surface-removing calculus & underlining cementum . (iii)Apply cotten pellets soaked in saturated solution of citric acid. *20-30 % concentration PH1(61 gm of citric acid per 100 ml of distilled water is added to achieve pH of 1) *Leave for 2-4 minutes (iv) Remove pellets *Irrigate root surface profusely with water . ( v) Replace the flap & suture it . 17

18. Technique of Register & Burdick : - Modified by Miller (1983) ( i ) Brushing application (Versus rubbing) (ii) 5 minutes application (iii)Use of high concentration 50% and PH 2 18

19. Strerret et al (1989) : Found that- use of miller's technique on native dentin removed the smear layer and opened the dentinal tubules. But did not expose collagen fibers. Han's (1985) Have reported increase in new attachment. Daly (1982) Immersed periodontally involved roots in citric acid at PH1 followed rinsing in 0.85% Nacl for 1 minute. Found significant reduction in the microflora in former. 19

20. The use of citric acid has also been recommended in conjunction with coverage of denuded roots using free gingival grafts. The drawback of Citric acid conditioning is that it creates an extremely acidic pH in the surrounding tissues, which may result in unfavorable wound healing responses and also denaturation of the collagen. 20

21. II- Tetracyclines Broad spectrum antibiotics & effective against periodontal pathogens. Have low PH in concentrated solution Act as calcium chelator resulting in deminerilazation . Action ( i ) Enhances binding of matrix proteins (ii)Stimulate the fibroblast attachment & growth. 21

22. Widening of Dentinal tubules after tetracycline application Narrowed dentinal tubules 22

23. ( iii)Suppress epithelial attachment & migration . (iv) Removes amorphous layer & exposes dentinal tubules. (v) Maintains anti-microbial activity for 14 days. In vitro treatment of the dentin surfaces with tetracycline increases binding of fibronectin,which in turn stimulates fibroblast attachment and growth while suppressing epithelial cell attachment and migration.It also removes an amorphous surface layer and exposes the dentin tubules. A human study showed a trend for greater connective tissue attachment after tetracycline treatment of roots. 23

24. Terranova et al. in 1986 have shown that the tetracycline treatment of root surface suppresses laminin binding and epithelial cell growth and attachment. Tetracycline treated dentin surfaces increased the binding of fibronectin and stimulate fibroblast attachment and growth. It can also inhibit bone resorption by inhibiting osteoblast and osteoclast derived MMPs, alteration of osteoclast response to extracellular Ca++ concentration. Tetracycline also been found to enhance osteoblast activity, increase collagen and bone formation when these processes are suppressed during the disease. 24

25. III- Fibronectin High glycoprotein found on the surface of the cells, in plasma, extracellular matrix and in basement membrane. It is a glycoprotein required by fibroblasts to attach to the root surfaces. Plays an important role in - Promoting attachment of cell to one another to extracellular matrix & collagen 25

26. Possess therapeutic utility in promoting connective tissue attachment for periodontal regeneration . Biologic mediator that enhances the tissue response in early phases of wound healing prevents seperation of flap & favours haemostasis & regeneration. 26

27. The use of fibronectin as a supplement to demineralization is, therefore, strongly supported by the following factors : The initial stage after demineralization and prior to new attachment is fibrin formation and linkage. 2. It is the coronal growth of cells from the periodontal ligament that is responsible for new attachment and fibronectin stimulates this growth. 3. Favours the growth and attachment of fibroblasts over epithelial cells to the root surface. 4. Speeds the linkage process by being Chemoattractive for fibroblasts and stabilizing the clot between the exposed root surface collagen and new fibers within the tissue. 27

28. Smith et al ., reported the effect of citric acid and fibronectin on healing after periodontal flap surgery in dogs. Results showed significant increase in new connective tissue attachment in all surgical sites where fibronectin had been applied. In another study 46 patients were evaluated after treatment with citric acid and fibronectin and reported significant gains in clinical attachment and probing depth reduction. Caffesse et al . evaluated the effect of citric acid root demineralization and fibronectin application on periodontal flap surgery wound healing in beagle dogs with naturally occuring periodontitis . They found that the use of citric acid and fibronectin in combination with flap procedure resulted in a greater gain of attachment 28

29. IV-EDTA (Ethylene Diamine Tetra acetic Acid) It is a polyaminocarboxylic acid and a colourless , water-soluble solid. EDTA is mainly synthesised from ethylenediamine, formaldehyde sodium cyanide Chelating agent, for treating mercury and lead poisoning Functions by forming a calcium chelate solution with calcium ions. Softens Root surface. Removes smear layer. Effects partial demineralization to a depth of 20-30 micro meter in 5 minutes. 29

30. A set of studies have shown that root surface demineralized by 18% EDTA facilitates the attachment, migration and contraction of fibroblasts. Results also showed that supersaturated (24%) solution of EDTA was significantly more effective than lower concentrations of EDTA with regard to smear removing capacity. 30

31. Growth factors Growth factors are polypeptide molecules, released by cells in the inflamed area, that regulate events in wound healing. These are the proteins responsible for coordinating these cellular repair processes. They can be considered hormones that are not released into the blood stream and have a very localized action. 31

32. Currently, the factors which are believed to contribute to periodontal regeneration include the Platelet Derived Growth Factor (PDGF) Insulin Like Growth Factor (IGF) Transforming Growth Factor (TGF) Epidermal Growth Factor (EGF) Fibroblast Growth Factor (FGF) Bone Morphogenetic Protein (BMP) 32

33. Platelet derived growth factor Platelet derived growth factor is composed of two disulfide bonded polypeptide chains that are encoded by two different genes (3 and 11), the PDGFA and PDGFB. PDGF can exist as a heterodimer (PDGF-AB) or a homodimer (PDGF-AA or PDGF-BB). Sources of PDGF include the alpha granules of platelet, monocytes , macrophage,fibroblasts , endothelial cells, and bone matrix. PDGF has been identified as a competence growth factor and act synergistically with progression growth factor such as the insulin like growth factor (IGF). 33

34. Bartold examine the effect of PDGF-BB on human gingival fibroblasts. He found that it significantly elevates hyaluronate synthesis which correlates with early events seen in wound healing and repair. Oates et al . found that TGF-b enhanced the response of the PDL cells to the PDGF. Together, PDGF and TGF-b also stimulated gingival fibroblast as measured by increased cell number In vivo study was done by Lynch et al ., which demonstrated that a topical application of PDGF and IGF-1 in beagles dog with naturally occuring periodontitis resulted in substantial new bone and cementum as well as the formation of the PDL 34

35. Transforming Growth Factor (TGF) TGF growth factor = sources included the platelets, osteoblast , macrophages. TGF-b main storage site is bone, and it is activated when there is a drop of pH as in during osteoclastic bone resorption . TGF-b also been reported to induce osteoblast chemotaxis and stimulate extracellular matrix formation via the synthesis of type I collagen, fibronectin , and osteonectin . In mature bone, it stimulate bone resorption by prostaglandin dependent mechanism. In immature bone, it stimulate bone proliferation and inhibit bone resorption by prostaglandin independent mechanism. 35

36. In vivo study of Lynch et al , which reported the topical application of TGF-b to epidermal wound in pig and caused inhibition of reepithelialization and increased connective tissue volume, collagen synthesis, and angiogenesis. Selvig et al . found no increase in bone regeneration when a combination of TGF-b1, IGF-2, and basic FGF topically applied to the surgically created defects in dogs 36

37. Fibroblast growth factor (FGF) Fibroblast growth factor (FGF) are a family of polypeptides that are potent mitogens and chemoattractants for endothelial cells as well as for a variety of mesenchymal cells, including the fibroblasts, osteoblasts , chondrocytes , smooth muscle cells and skeletal myoblasts . Acidic FGF and Basic FGF. Basic FGF is 30 times more potent A characteristic unique to the FGFs is that they are potent angiogenic factors critical to the wound healing and the formation of granulation tissue. 37

38. Terranova et al . reported that FGFs can stimulate mitogenesis and chemotaxis in PDL cells. Feres-Filho and Trackman reported that basic FGF down-regulated lysyl oxidase messenger RNA and enzyme activity in a dose and time dependent manner. Lysyl oxidase is the limiting enzyme for collagen cross linking to form collagen matrix, which is neccessary for the differentiation of osteoblastic cells and bone mineralization . 38

39. Insulin like growth factors (IGF) Insulin like growth factors (IGF) are a family of single chain serum protein that shared similar amino sequences and therefore similar spectrum of activities to that of insulin. Two most common members in this group are the IFG-1 and IFG-2 Lynch et al . reported the combination of IGF-1 and PDGF, resulted in 95% increase in epidermal thickness and a two fold increase in the width of the newly formed connective tissue. 39

40. Epidermal growth factor (EGF) Epidermal growth factor (EGF), is structurally related to TGF-a and possess similar property. Its major source are urine and salivary gland. In vitro, EGF stimulates DNA synthesis and cell growth of epithelial cells endothelial and mesodermal origin. Studies done in vitro has reported of EGF significantly enhance reepithelialization and wound healing in term of fibroblast proliferatoin and angiogenesis. 40

41. Bone Morphogenetic Protein (BMP) In 1965 Marshall and Urist demonstrated that cellular events associated with embryonic development could be reproduced in other sites In late 1960’s and 1970’s – dentin contains BMP’s 41

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43. Tissucol A fibrin — fibronectin sealing system (FFSS) has been commercially available ( Tissucol — Tisseel ) in Europe since 1975. It is a human plasma cryoprecipitate, which consists of highly concentrated fibrinogen, fibronectin,factor XIII, platelet — derived growth factor (PDGF antiplasmins and plasminogen . Aprotinin (bovine antiplasmin ), thrombin and calcium chloride are added 43

44. Enamel Matrix Protein (EMP) It is based on the biologic concept that the application of Enamel Matrix Protein ( amelogenins ) may promote periodontal regeneration as it mimics events that take place during the development of periodontal tissues In a clinical study long term effect of Enamel Matrix Protein treatment as an adjunct to modified Widman flap surgery vs modified Widman flap plus a placebo was assessed. The results in the EMP group were better, as shown by a gain in the clinical attachment level, probing depth reduction and restoration of bone radiographically 44

45. Microscopic examination after four months revealed formation of new acellular cementum , new PDL with inserting and functionally oriented collagen fibers, and associated alveolar bone.. 45

46. Emdogain It is a resorbable , implantable material that consists of enamel matrix proteins extracted from developing embryonic enamel of porcine origin supplied in sterile form. Emdogain contains a protein preparation that mimics the matrix proteins that induce cementogenesis . During root development, the Hertwig’s epithelial sheath deposits enamel matrix proteins on the newly formed root dentin surface. These proteins stimulate the differentiation of surrounding mesenchymal cells into cementoblasts , which form acellular cementum 46

47. The major constituents arc amelogenins . Other proteins identified include ameloblastin and enamelin . It uses propylene glycol alginate (PGA) as a carrier. EMD is absorbed into the hydroxyapatite and collagen fibers of the root surface, where it induces cementum formation followed by periodontal regeneration. Emdogain has two presentation forms: One is in liquid and powder form, in 2 separate bottles containing the vehicle and the protein powder and the other is in the form of gel in syringe. The material is stored in the refrigerator, at 2-8°C. It should be used in no more than 2 hours from opening, because it gelifies and hardens. 47

48. The technique by Mellonig Raise a mucoperiosteal flap Remove all granulation tissue and tissue tags, exposing the underlying bone, and remove all root deposits by hand, ultrasonic scaling, or both. Completely control bleeding within the defect. 4. Demineralize the root surface with citric acid pH 1, or preferably with 24% ethylene diamine tetracetic acid(EDTA Biora ) pH 6.7 for 15 seconds. This removes the smear layer and facilitates adherence of the Emdogain . 48

49. 5. Rinse the wound with saline and apply the gel to fully cover the exposed root surface. Avoid contamination with blood or saliva. 6. Close the wound with sutures. Perfect abutment of the flaps is necessary; if this cannot be obtained, correct the scalloping of the gingival margin or perform a slight osteoplasty . Although placement of the dressing is optional, it may protect the wound. 49

50. Laminin Laminin is a glycoprotein of high molecular weight. It is capable of adhering to various substrates. Laminin promotes gingival epithelial and fibroblast chemotaxis . It also promotes epithelial cell adhesion and growth to tetracycline and glycoprotein conditioned surfaces. 50

51. V- Sodium Deoxycholate & Human Plasma Fraction These agents dissociate endotoxin into subunits & detoxify the diseased root surfaces. Human - Plasma fraction- contains fibronectin Increases connective tissue attachment. Content - 69% alpha1 & alpha2 globulins 10% beta globulin 20% gamma globulin 51

52. VI- Miscellaneous Aqueous Ethyl Ether Used to extract endotoxin Lithium Aluminium Hydride Can cleave ester linkage in endotoxin . Bile Salts Dislocate endotoxin into sub units which reaggrate upon removal. 52

53. Laser Misra et al., showed that CO laser produced surface charring and carbonization, and were totally ineffective in exposing the dentinal tubules. The CO laser, when used with high-energy output, especially in a continuous wave mode, is not appropriate for root surface debridement due to major thermal side-effects, such as carbonization. In vivo study by Liu et al., showed no additional benefit when laser treatment was used secondary to traditional SRP therapy 53

54. Results from in vitro studies with Nd:YAG laser have shown its efficacy in removing the smear layer and inactivating the endotoxin in the superficial layer of the root surfaces. In vitro studies with Er:YAG laser have shown its efficacy in removing the smear layer. 54

55. Limitation of Chemical Substances May give rise to secondary endodontic involvement via dentinal tubules. Depth of action is not controlled. Increased size of dentinal tubules More penetration of micro-organism may cause root caries. Chemicals may infavourably alter the morophology of collagen. 55

56. COMPLICATION New attachment with regeneration is the ideal outcome of the therapy. However, certain complication may be seen (1) Healing with a long junctional epithelium. (2) Ankylosis and resultant root resorption (3) Recurrence of the pocket. (4) Combination of above 56

57. CONCLUSION The use of root biomodification is divided into two different schools of thought. Some authors favours it while others don’t. It is well established that the periodontally diseased root surface does not favour regeneration of the periodontium due to its surface characteristics. The in vivo and in vitro studies clearly indicate a greater potential for cell and fiber attachment to demineralized root surfaces. However evidence does not support the use of citric acid, tetracycline and EDTA to reduce probing depth or enhance clinical attachment levels. They may have a role in removal of smear layer and detoxification but this too has been proved only in in-vitro and animal studies . The best method for ascertaining the clinical efficacy of acid-treated root regeneration would be to conduct a randomized clinical trial with sufficient statistical power. 57

58. REFERENCES Periodontology 2000 Journal of clinical periodontology Text book of clinical periodontology - Carranza & Newman Textbook of clinical periodontology and implantology -Jan Lindhe 58

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