Growth Factors and Periodontal Regeneration

Self-Study Examination

Instructions: After studying the text answer the following true/false or multiple choice questions.  Remember, there's only one answer to each question.

1. Regeneration implies that the architecture and function in a healing wound have been restored to pre-wounding status. Repair implies that the wound has been healed by a tissue that is unable to completely restore architecture or function.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

2. Growth factors are polypeptide hormones or biological factors that mediate:

a) Many cellular processes necessary for growth
b) Induction of phenotypic expression
c) Metamorphosis of totipotent germ cells into pluripotent stem cells
d) All of the above

3. Polypeptide growth and differentiation factors (GDFs) are:

a) A class of biological mediators
b) Essential for stimulation and regulation of the wound healing process
c) # 1 only
d) # 1 and 2

4. The cellular processes mediated by growth factors are:

a) Stimulation/inhibition of growth and development/differentiation
b) Regeneration, repair, and wound healing
c) Mitogenesis, chemotaxis, metabolism, angiogenesis, and apoptosis
d) All of the above

5. Apoptosis is the process of programmed cell death.

a) true
b) false

6. In healing by primary intention, the wound edges are apposed and there is minimal tissue loss.

a) true
b) false

7. Gingivitis is described as the inflammation that is limited to the gingival tissue that is demarcated from the deep subcrestal periodontal tissues by crestal and transseptal fibers.

a) true
b) false

8. Healing by secondary intention is characterized by wound edges that are separated with a more extensive tissue loss.

a) true
b) false

9. Repair occurs through the process of:

a) Hemorrhage and clotting
b) Organization via granulation tissue
c) Fibrosis with the appearance of a scar in mature tissue
d) All of the above

10. Depending on their environment, the regenerated epithelial cells differentiate, respectively, into the junctional, oral sulcular, and oral gingival epithelium. Hence, the gingival tissues associated with gingivitis are capable of almost complete regeneration.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

11. In a976, a theory was proposed that the first cells to repopulate the exposed root surface are the ones to establish the nature of the attachment that develops. Thus, the potential for repair may depend on which cell type wins the race to populate the root surface first.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

12. If epithelial cells populate the root surface first, specifically growing on the surface of the gingival granulation tissue, a long junctional epithelium will be the consequence.

a) true
b) false

13. If gingival connective tissue cells populate the root surface first, the attachment will be one of connective tissue adhesion, and root resorption is likely to occur.

a) true
b) false

14. If bone cells are the first to proliferate and make contact with the tooth surface, root resorption and ankylosis are the result.

a) true
b) false

15. If periodontal ligament cells are the first to migrate and cover the denuded root surface, then new connective tissue attachment forms and this is the ideal attachment.

a) true
b) false

16. Of the four healing patterns listed immediately above, proliferation of new connective tissue by periodontal ligament cells and new bone formation constitute regeneration. The other healing patterns are associated with repair.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

17. Epithelial cells migrate more quickly than connective tissue cells with no physical barrier to hamper their apical migration. Epithelial cells from wound margins proliferate on the surface of granulation tissue resulting in a long junctional epithelium.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

18. If the tissue framework is not severely damaged, regeneration may occur in very limited areas at wound margins. After conventional periodontal treatments, healing results in repair not regeneration.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

19. Cells originating from periodontal ligament are the only cells with the ability to produce a new connective tissue attachment.

a) true
b) false

20. In the 1980’s various histologic and clinical studies supported the theory that new connective tissue can attach to a previously exposed root surface if cells derived from the periodontal ligament are stimulated to proliferate.

a) true
b) false

21. Guided tissue regeneration is a form of periodontal therapy that employs the use of an occlusive membrane to selectively guide cells derived from the periodontal ligament to populate the denuded root surface.

a) true
b) false

22. The phenotype is defined as the total characteristics seen in an organism resulting from the interaction between the genotype and the environment regardless of the actual genotype of the organism.

a) true
b) false

23. Various growth factors have been isolated from dentin or cementum.

a) true
b) false

24. Whether surgical or nonsurgical techniques are selected in the conventional approach to periodontal therapy, the instrumentation used in debridement and surgery results in:

a) A wound in the already inflamed dentogingival tissues
b) A subsequent surge of cellular and molecular events that initiate wound repair
c) # 1 only
d) # 1 and 2

25. Numerous cellular and molecular events that are part of the healing process for periodontal wounds are analogous to those seen in wounds located in the rest of the body. The exception is that there is a mineralized tissue located at the junction of epithelium and connective tissue in periodontal wounds.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

26. The clot performs various vital functions:

a) The clot acts as a reservoir of growth factors and cytokines.
b) Growth factors and cytokines are released from the clot by degranulation of activated platelets and serve as a provisional matrix for cell migration.
c) Growth factors and cytokines in the fibrin clot may provide the signals that initiate wound repair.
d) All of the above

27. Neutrophils eliminate bacterial debris by releasing enzymes and toxic oxygen products that damage host tissues. The greater the number of contaminating bacteria in the wound, the greater the potential there is for neutrophil-mediated destruction of host tissues.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

28. The following statements apply to macrophages:

a) Macrophages continue to provide for the phagocytosis of bacterial, cellular and matrix debris in the wound.
b) Macrophages maintain synthesis of growth factors and cytokines and secrete them into the wound locale.
c) Macrophages maintain the wound repair signals that were initiated by degranulating platelets and neutrophils.
d) All of the above

29. The formation of granulation tissue is normally initiated approximately d days after wounding occurs. Primarily, it is composed of new capillaries, macrophages, fibroblasts and some loose connective tissue.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

30. Transforming growth factor-ba has been associated with pathofibrotic conditions which may account for scarring and contraction of adult wounds. Antibodies have been shown to neutralize the effects of transforming growth factor-ba in healing wounds and diminish scarring.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

31. In normal, healthy subjects, abundant amounts of growth factors are found in the provisional matrix. Addition of the proper growth factor may be advantageous in systemic conditions, such as diabetes, that exhibit a reduced availability of various growth factors.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

32. Histological evidence is mounting that the formation of cementum is integral for normal maturation of the periodontium during development and also during periodontal tissue regeneration.

a) true
b) false

33. Enamel matrix proteins may stimulate cementoblast activity including proliferation, migration/adhesion, as well as cell differentiation, and this is the key rationale that supports the use of enamel matrix derivative.

a) true
b) false

34. Osteocalcin may be one of the molecules that regulate the mineral-to-ligament ratio. Thus it favors formation of the periodontal ligament region rather than ankylosis.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

35. The local effect of growth factors is ensured by their short half-life and their relationship with extracellular matrix and growth factor–binding proteins.

a) true
b) false

36. Specific cell surface receptors enable extracellular matrix molecules and growth factors to exert their effects. Binding of the cell surface receptor enables it to interact with cytoplasmic effector molecules to initiate a complex cascade of intracellular events that ultimately alter gene function.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

37. Bone morphogenetic proteins perform many functions, including:

a) Regulation of cell growth
b) Differentiation and apoptosis in osteoblasts, neural cells, epithelial cells and various other cell types
c) #2 only
d) #1 and 2

38. Cementoblasts are cells that line the root surface and appear to have a restricted function in health, but they may be activated to participate in the wound healing process.

a) true
b) false

39. Various different agents can be categorized as regulators of periodontal tissue regeneration that stimulate formation of bone, cementum, and the periodontal ligament. They include:

a) Cell occlusive membranes and bone replacement grafts
b) Root conditioning agents, such as citric acid and ethylenediaminetetraacetic acid
c) Growth and attachment factors, such as bone morphogenetic proteins, platelet-derived growth factor and enamel matrix derivative
d) All of the above

40. Granulation tissue is a repository of cytokines that demonstrate chemoattractive, mitogenic and other regulatory functions. Growth factors, also found in granulation tissue, are derived mostly from macrophages at this stage of healing.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

41. Cells must possess the ability to interact with the local environment, to be attracted to the site of action, and to remain there. Cells accomplish this via receptor-ligand interactions.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

42. Sialoprotein and osteopontin recruit and support selective cells at the root surface. They may also control mineralization along the root surface as well.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

43. During wound healing, platelet-derived growth factor and platelet-derived growth factor-receptor have been localized to periodontal tissues. Retaining adequate amounts of a specific factor at the local site is thought to be a limitation to current regenerative therapies.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

44. Osteocalcin may be one of the molecules that regulate the mineral-to-ligament ratio; and thus, favors formation of the periodontal ligament region rather than ankylosis.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

45. Growth factors display different effects on cells subject to the specific factor, the type of cell, and the stage of maturation. The local effect of growth factors is ensured by their short half-life and their relationship with extracellular matrix and growth factor–binding proteins.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

46. There are several factors that limit the predictable delivery of agents to the root surface and complicate the healing process in a periodontal wound:

a) Transmucosal environment of the mineralized tooth surface and complex nature of the attachment apparatus
b) Microbes that contaminates wounds at the interface between soft and hard tissues and may alter the release kinetics of delivery devices
c) Occlusal forces that impact on the tooth complex
d) All of the above

47. While the extracellular matrix (ECM) of cementum resembles the composition of other mineralized tissues, it possesses a unique physiology and includes molecules that have not been found in other tissues.

a) true
b) false

48. Periodontal disease severely compromises the structural integrity and biochemical composition of the cementum matrix by depositing bacterial endotoxins into it. Periodontal healing generates a provisional matrix that is different from cementum.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

49. The soft-tissue attachment in cememtum has to be re-established because cementum exerts a regulatory role in periodontal regeneration.

a) true
b) false

50. A factor originally named cementum-derived growth factor is currently thought to be an insulin-like growth factor-I–like molecule, and it may be discovered in the future to possess properties similar to those of insulin like growth factor-I.

a) true
b) false

51. A variety of growth factors and their receptors play a role in the process of re-epithelialization, such as:

a) Transforming growth factor (TGF)-a a member of the epidermal growth factor (EGF) family
b) Heparin-binding EGF (HB-EGF)
c) Keratinocyte growth factor (KGF, also called FGF-7) and TGF-ß
d) All of the above

52. Within 24 hours after an injury occurs, the expression of keratinocyte growth factor is enhanced by 100-fold.

a) true
b) false

53. Platelet-derived growth factor (PDGF) is mitogenic to fibroblasts and other mesenchymal cells and stimulates cell division. PDGF is a significant growth factor in wounds and gingival epithelium.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

54. Transforming Growth Factor-ß (TGF-ß) and connective tissue growth factor (CTGF) both activate fibroblast collagen synthesis. Both TGF-ß and PDGF play an active role in wound contraction.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

55. The degree of injury and the quantity of lost tissue that must be filled are important determinants as to whether wounds heal by regeneration or repair.

a) true
b) false

56. Two vital factors influence the potential for regeneration versus repair:

a) Accessibility of necessary cell types
b) Presence of cues and signals needed to recruit and stimulate these cells
c) Neither of the above
d) Both #1 and 2

57. Diffusible factors such as growth factors and cytokines provide the signals; but it is the extracellular matrix that controls how the cells act in response to the signals.

a) true
b) false

58. Researchers have now confirmed that most tissues contain the cells needed for regeneration. These cells are represented by two types: the stem cells that are removed from terminal differentiation by several stages, and the progenitor or precursor cells in the stage immediately preceding full differentiation.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

59. Two molecules unique to cementum are IGF-I isoform, also called cementum growth factor (CGF), and cementum attachment protein (CAP).

a) true
b) false

60. There is one significant pathological change in periodontal disease and that is the deposition of bacterial plaque substances, including their bacterial endotoxins. Attachment loss occurs in response to the destruction of connective tissue fibers.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

61. When the cementum surface is exposed to periodontal pockets the following occur:

a) The damage to cementum becomes irreversible.
b) Periodontal disease leads to changes in the biochemical composition of cementum.
c) The active substances are lost and the inhibitors such as endotoxins are deposited.
d) All of the above.

62. The growth and attachment of connective tissue cells are inhibited by diseased cementum, setting the stage for the formation of an epithelial attachment. This led to the rationale for the development of new therapeutic approaches in which diseased roots could be conditioned to stimulate connective tissue attachment.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

63. The formation of new cementum and restoration of the soft-tissue attachment to cementum is a very significant objective of regenerative periodontal therapy.

a) true
b) false

64. Various studies have identified growth factors in cementum including:

a) IGF-I and FGFs
b) EGF, BMPs, and TGF-ß
c) #2 only
d) #1 and 2

65. The anatomy of cementum is a unique mineralized ‘interface’ tissue connecting mineralized dentin and non-mineralized fibrous periodontal ligament. In the case of cementum regeneration, its anatomy suggests that to be successful, a delivery system must reconcile these two very different environments.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

66. The ability to direct the agents/cells to the tooth root surface is considered the rate limiting step in the re-engineering of periodontal structures including cementum.

a) true
b) false

67. Molecules that are thought to induce or control periodontal regeneration have short half-lives at the healing site that may diminish their effects in vivo.

a) true
b) false

68. The capacity to transfer genetic material into specific cells provides a technique that may assist in prolonging the effect of the targeted factor. Gene transfer can be accomplished by either in vivo or ex vivo transfer of the appropriate transgene.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

69. Gene therapy may be utilized to deliver factors into the wound site that regulate:

a) Angiogenesis and proliferation
b) Attachment and differentiation
c) #1 only
d) #1 and 2

70. Various studies have evaluated gingival crevicular fluid and salivary levels of growth factors for their potential to diagnose periodontal disease, including epidermal growth factor, transforming growth factor-Your browser may not support display of this image. and-Your browser may not support display of this image. , platelet-derived growth factor, and vascular-endothelial growth factor.

a) true
b) false

71. Significantly lower concentrations of transforming growth factor-Your browser may not support display of this image. were present in the gingival crevicular fluid of patients with severe periodontal disease.

a) true
b) false

72. Significant correlations were found between the concentrations of transforming growth factor-Your browser may not support display of this image. in gingival crevicular fluid and pocket depth measurements, bleeding on probing, and radiographic bone loss.

a) true
b) false

73. While the correlation between levels of growth factors and periodontal disease remains unclear, researchers theorized that since transforming growth factor-Your browser may not support display of this image. is associated with the wound healing process, the absence of this factor may lead to a delay in periodontal regeneration during progression of the disease.

a) true
b) false

74. Polypeptide growth factors such as platelet-derived growth factor (PDGF) have demonstrated the capacity to stimulate both cementogenesis and osteogenesis.

a) true
b) false

75. Recent developments in gene therapy now enable scientists to deliver recombinant proteins to tissues over extended time periods up to c5 days. Recombinant adenoviral vectors encoding for the PDGF-A gene enable delivery of platelet-derived growth factor transgenes to cells.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

76. The use of DNA-lipid complexes and adenovirus are examples of gene delivery methods for the short-term expression of genes. Normally, the regulation of wound repair takes place in a controlled manner over a defined period of time.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

77. It is the ability of the adenovirus to remain extrachromosomal as a nonintegrating virus that enables the expression pattern to be transient. Researchers evaluated the feasibility of platelet-derived growth factor (PDGF) for gene delivery because it consistently stimulates periodontal tissue regeneration.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

78. Other methods thought to be promising in the promotion of tissue repair are:

a) Biodegradable polymers to deliver PDGF DNA
b) Adenovirus to deliver bone morphogenetic protein (BMP) genes to orthotopic wounds by ex vivo (in vitro) approaches
c) Transducing wounds via in vivo microseeding
d) All of the above.

79. In b00a Giannobile demonstrated for the first time the use of growth factor gene delivery to root lining cells.

a) true
b) false

80. Evidence indicates that matrix-metalloproteinases are the primary mediators of connective tissue breakdown so characteristic of chronic inflammatory diseases such as periodontitis.

a) true
b) false

81. Not only is transforming growth factor-beta 1 a key mediator in the regulation of matrix-metalloproteinases, but also in the limitation of inflammation and its resolution.

a) true
b) false

82. As treatment modalities, scaling and root planing are effective in curtailing or preventing the progression of periodontal diseases, but they do not directly address the host response component of periodontal disease.

a) true
b) false

83. Evidence indicates that tetracyclines inhibit collagenolytic activity by inhibiting matrix-metalloproteinases. When tetracyclines suppress events that are mediated by matrix-metalloproteinases, there is a decrease in the breakdown of connective tissue and the resorption of bone.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

84. In a999 the Food and Drug Administration approved a specially formulated subantimicrobial dose doxycycline (SDD) as an adjunct to non-surgical periodontal therapy.

a) true
b) false

85. Transforming growth factor-betaa (TGF-ß1) plays an essential role in mediating the resolution of gingival inflammation and in initiating wound healing by:

a) Stimulating proliferation of fibroblasts
b) Increasing production of extracellular matrix molecules and inhibitors of MMPs
c) Inhibiting synthesis of matrix-metalloproteinase
d) All of the above

86. Since bone loss does not occur in gingivitis, this might be a reflection of the remodeling of alveolar bone by transforming growth factor-beta1.

a) true
b) false

87. Periodontitis is the most common bone disease affecting humans. It is only in the last decade that scientists began to use signaling molecules such as growth factors in their quest to restore tooth support that had been destroyed by periodontal disease.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

88. There are several key factors required to enhance healing in the attempt to achieve the most effective regeneration of periodontal structures:

a) Control of microbial infection to eliminate or reduce offending bacteria
b) Stabilization and maintenance of the wound compartment to facilitate migration of mesenchymal cells back into the periodontal defect
c) Release of chemotactic, inductive, and growth factors (GFs) to stimulate proliferation and subsequent attachment of cells believed to participate in regeneration of lost periodontal tissues
d) All of the above.

89. Clinicians have utilized a variety of surgical procedures:

a) Root-conditioning agents
b) Osteoconductive and osteoinductive grafting material such as autogenous, allograft and xenograft bone materials
c) Guided tissue regeneration (GTR) using a cell occlusive barrier
d) All of the above

90. Basic fibroblast growth factor:

a) Promotes human periodontal ligament and endothelial cell attachment and proliferation on dentin slices from teeth
b) Is constitutively expressed in human periodontal tissues
c) Is upregulated in early periodontal wounds for up to 7 days
d) All of the above.

91. In all of the in vivo experiments with basic fibroblast growth factor sites, no instances of epithelial downgrowth, ankylosis or root resorption were observed. Bone morphogenetic proteins demonstrated the greatest potential because they are strong osteoinductive growth factors.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

92. In human studies on the use of EMD, human histology confirmed 'true regeneration in patients treated with enamel matrix derivative. EMD is not an osteoinductive factor, but with threshold concentrations, it is osteopromotive.

a) true
b) false

93. There are two critical steps in the approach to gene therapy:

a) Delivery of DNA to the appropriate target cells
b) Expression of transgene encoded proteins in a therapeutic fashion
c) None of the above
d) Both #1 and 2

94. For in vivo and ex vivo approaches, growth factor gene therapy for tissue engineering uses the insertion of GFs or wound-healing cytokines into transiently expressing viral vectors.

a) true
b) false

95. Hughes described cytokines as “soluble, secreted glycoproteins which act as local signaling molecules to control and co-ordinate cellular behavior and function”. Cytokines function as ligands binding to cell-surface receptors, which then trigger serial intracellular signaling events, eventually leading to the modulation of gene expression in their target cells.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

96. Studies indicate that mature osteoblasts have an average lifespan of about a month. They then undergo apoptosis with two further options: they may be replaced by newly differentiated osteoblasts, or about one-third of these cells may be incorporated into deposited bone matrix as osteocytes.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

97. Achieving sufficient substantivity (duration of contact) for the factor to provide a continual therapeutic dose over a lengthy period of time is probably one of the main critical determinants of success for these treatments.

a) true
b) false

98. Platelet-rich plasma is obtained from a patient's own platelets. It is an autologous preparation rich in a number of growth factors, including platelet-derived growth factor and trefoil factor family-ß.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

99. Growth factors are delivered into the extracellular matrix where they are released during matrix degradation. They subsequently interact with surface receptors on the target cells which then stimulates intracellular signaling pathways to induce transcription of mRNA and proteins necessary for the regenerative process.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

100. There are no concerns about immunogenic reactions and disease transmission between individuals because PRP is an autologous product.

a) true
b) false

101. Growth factors have been associated with the growth of tumors and the actions of monocyte/macrophages and inflammatory processes could be involved in this mechanism.

a) true
b) false

102. Treatment with PRP resulted in significantly higher levels of growth factors. PRP considerably suppressed inflammation by promoting secretion of lipoxin A4 (LXA4), a natural mediator of inflammation resolution.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

103. Lipopolysaccharide inhibits the proliferation of gingival fibroblasts. Platelet-derived growth factor decreases this inhibitory effect.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

104. PDGF-BB stimulates the adherence of periodontal ligament cells to root surfaces.

a) true
b) false

105. PRP is an important source of EGF, VEGF, and FGF-ß. FGF-ß demonstrated chemotactic and mitogenic properties for fibroblasts in the periodontal ligament.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

106. VEGF is now known to be critically important in forming new blood capillaries in healing wounds and is necessary for the integrity of the vasculature endothelial lining.

a) true
b) false

107. Regeneration is inhibited by excess or chronic inflammation. PRP promotes healing by regulating the local inflammatory response.

a) The first statement is 'true; the second statement is 'false
b) The first statement is 'false; the second statement is 'true
c) Both statements are 'true
d) Both statements are 'false

108. The system used to deliver growth factors may have a significant impact on the regenerative response that is achieved. Investigators are especially interested in the following:

a) Surface area and surface properties for cell-surface interactions
b) Inflammatory and immune reactions
c) Degradation kinetics
d) All of the above

109. Delivery systems that have been reported for growth factors are collagen as a sponge, membrane, or gel and gelatin with varying degrees of cross-linking.

a) true
b) false

110. The degradation kinetics of bioabsorbable carriers, or how fast they break down, appears to affect or modify the type of new tissue that is formed.

a) true
b) false

111. Important goals of periodontal therapy are:

a) Reduction or elimination of tissue inflammation induced by bacterial plaque and its by-products
b) Correction of defects or anatomical problems caused by the disease process
c) Regeneration of lost periodontal tissues as a consequence of disease destruction
d) All of the above

112. The process of periodontal regeneration is complicated by factors such as:

a) Presence of multiple, specialized cell types and attachment complexes
b) Stromal-cellular interactions
c) Diverse microbial flora and avascular tooth surfaces.
d) All of the above

113. Based on years of research in wound healing and tissue regeneration, it is now an accepted fact that regeneration is inhibited by excess inflammation or chronic inflammation.

a) true
b) false