Review on bone morphogenetic proteins and their role in periodontal regeneration

1. Bone Morphogenetic
Proteins
SEMINAR PRESENTED BY-
SHASHI KIRAN
8/5/2020
1

2. Contents
1. History
2. Structure of BMP
3. Classification of BMPs
4. Characteristics of BMPs
5. Mechanism of action
6. Delivery systems
7. Role in periodontal regeneration
8. Role in ridge augmentation and
sinus augmentation
9. Complications
10. Contraindications
11. Conclusion
12. References
2

3. History
In 1938, Levander implanted living bone fragments 1 to 1.5 cm in length either
subcutaneously or intramuscularly Bone formation occurred.
He proposed that there must be some stimulating agent which originated from the
graft itself, possibly a substance which was soluble in the lymph tissue.
After subsequent experiments,
Levander concluded that there is an extractable substance from bone which is able
to activate mesenchymal cells to form bone tissue.
3

4. Urist and co-workers in 1965 "'discovered" that control samples of
untreated decalcified bone implanted into muscle pouches of rabbits and
rats resulted in new cartilage and bone formation.
This led to the hypothesis of bone formation by auto-induction, in which an
inductor, acts upon an induced cell, causing it to differentiate into either an
osteo-progenitor or a chondro-progenitor cell.
He subsequently demonstrated that this activity could be extracted from
the organic component of bone using chaotropic agents, and that a
protein or proteins were responsible for this activity
Urist termed this hypothetical bone inducing substance as ‘Bone
Morphogenetic Protein’
4

5. Implantation of this protein
component of bone matrix resulted in
a complex series of cellular events
including:
mesenchymal cell infiltration,
cartilage formation, vascularization,
bone formation, and ultimately
remodeling of the new bone tissue
along with population by
hematopoietic bone marrow elements
5
oWozney JM. Overview of bone morphogenetic proteins. Spine.
2002 Aug 15;27(16S):S2-8.

6. 1. Bone-derived BMPs are manufactured starting with bovine bone-
These include removal of the fat and mineral component of bone, followed by extraction of
BMPs from the bone matrix.
The BMP extract then is purified using a series of chromatography steps.The resulting
purified extract contains a mixture of BMP molecules, each of which may possess a slightly
different activity as well as other contaminating proteins
6

7. 2. Recombinant DNA biotechnology process using mammalian cells- the
human BMP DNA coding sequence is placed in a vector system.This vector is transfected into
the mammalian cell host of choice, in this case Chinese hamster ovary (CHO) cells
As mammalian cells are used to synthesize these BMPs, the molecules are dimerized,
processed (i.e., by removal of the propeptide), and glycosylated (by the addition of sugar
moieties), as are the naturally occurring molecules
The advantages of this recombinant production system include its reproducibility, ability to
ensure the consistent purity and activity of the BMP, and ability to ensure freedom from
adventitious agents.
7

8. Classification
The human genome encodes 20 BMPs
1. The first subclass contains BMP-2 and BMP-4, highly
related molecules that differ mainly in the amino
terminal region, with BMP-2 containing a heparin-
binding domain
2. In the second subclass are BMP-5, BMP-6, and BMP-7,
also known as osteogenic protein-1 (OP-1), and BMP-8
(OP-2).These are slightly larger proteins and there an
approximate 70% amino acid identity between the
subgroups
3. In the third subclass, and more distantly related to these
factors, is BMP-3, also called osteogenin.
8
oJain AP, Pundir S, Sharma A. Bone morphogenetic
proteins:The anomalous molecules. Journal of Indian
Society of Periodontology. 2013 Sep;17(5):583.

9. Characteristics of BMPs
9
oRao SM, Ugale GM,Warad SB. Bone morphogenetic proteins: periodontal
regeneration. North American journal of medical sciences. 2013 Mar;5(3):161.

10. Chemical structure
Bone morphogenetic proteins are members of TGF-
β(Transforming growth factor-β) super family, a large
family of growth factors.
The structure of most of the BMPs comprising three
portions, i.e.,
signal peptide,
propeptide,
and a mature region
The propeptide and mature region contain seven
conserved cysteine residues characteristic ofTGF-β
superfamily heterodimers or homodimers
10
oJain AP, Pundir S, Sharma A. Bone morphogenetic
proteins:The anomalous molecules. Journal of Indian
Society of Periodontology. 2013 Sep;17(5):583.

11. 11
oJain AP, Pundir S, Sharma A. Bone morphogenetic
proteins:The anomalous molecules. Journal of Indian
Society of Periodontology. 2013 Sep;17(5):583.

12. BMPs act as growth and differentiation factors and chemotactic agents. They stimulate
angiogenesis and migration, proliferation and differentiation of mesenchymal stem cells
into cartilage and bone forming cells.
A steep dose–response curve is observed, with low doses resulting in small amounts of
cartilage and bone formation. However, at no concentration is stable cartilage formation
observed.The cartilage always is replaced by bone
Larger doses result in more substantial bone formation and earlier osteoinduction.
Interestingly, when higher concentrations of BMPs are applied, bone forms at the same time as
cartilage formation, suggesting that BMP can result in direct (intramembranous) ossification.
12

13. Several of the BMPs appear to have indistinguishable activities, including BMP-2, BMP-7 (OP-
1), and BMP-6. These all result in similar cellular events, culminating in bone induction, and
similar amounts result in similar amounts of bone.
Other BMPs, such as BMP-5, require higher doses for similar amounts of osteoinduction.
The most abundant BMP in bone, BMP-3 (osteogenin), appears to be inactive in this assay
system, and may even be a negative modulator of bone formation.
13

14. Signalling mechanism
Most of the biological action of BMPs are mediated
through the BMP receptors which initiate signaling from
the cell surface when bind to two distinct type I and II
serine/threonine kinase receptors, required for signal
transduction
BMP receptors are composed of three parts:
1. a short extracellular domain,
2. a single membrane-spanning domain, and
3. an intracellular domain with active serine/threonine
region
14
oDavis H, Raja E, Miyazono K,TsubakiharaY, Moustakas A. Mechanisms of
action of bone morphogenetic proteins in cancer. Cytokine & growth factor
reviews. 2016 Feb 1;27:81-92.

15. Signalling mechanism
The type II receptor is the primary binding site of the ligand
and upon its activation, phosporylation of type I receptor
occurs. It is the type I receptor(or activin receptor-like kinases)
that determines the nature of biologic response..
The BMP receptors target Smad1, Smad5, and Smad8.
Phosphorylation of receptor-regulated Smads induces
their association with Smad4, the “common-partner”
Smad, and stimulates accumulation of this complex in the
nucleus, where it regulates transcriptional responses.
Cell proliferation and differentiation
15

16. Spatial and temporal regulation
The activity of BMPs is tightly
controlled at many levels.Outside
the cell, soluble inhibitory proteins can
bind certain of the BMPs and inhibit
their binding to cell surface receptors.
It has been found that BMPs can
upregulate the expression of some
of these inhibitors, suggesting a
negative feedback loop that limits the
activity of BMPs
16

17. Inside the cell, the activity of BMPs is controlled
through the combination of signal-transducing
Smad proteins and inhibitory Smad proteins.
Again, BMPs can upregulate expression of the
inhibitory Smad proteins.
All of these regulatory mechanisms together
cause the bone-induction process to be
controlled tightly and self-limiting.
Thus, bone induction is observed only locally at
the site of BMP and matrix implantation, as
defined by the volume of the matrix, and is
limited temporally only to the time when the
BMP is present.
17

18. Signalling pathway
BMPs bind to their
cell surface receptors
on mesenchymal
cells
Signals are sent via
specific proteins to
the cell nucleus
Expression of genes
that lead to synthesis
of macromolecules
involved in cartilage
and bone formation
Mesenchymal cell
becomes a
chondrocyte or an
osteoblast
Cartilage formation,
vascularization, bone
formation and
ultimately
remodelling of bone
tissue
18

19. Functions of BMPs
1. Role in Embryogenesis
2. Role inTooth morphogenesis
3. Role in osseoinduction
4. Role in wound healing.
19

20. Role in embryogenesis
The BMPs play pivotal roles in the development of brain, eyes, heart, skin, bones and teeth
Their actions include the establishment of body plan, initiation and maintenance during
regeneration of bone, formation of skeletal tissue during embryogenesis, growth and
remodelling, and the induction and creation of new bone.
BMP-2 has been strongly implicated in playing multiple roles in morphogenesis and pattern
formation in the vertebrate embryo, not only with the developing skeleton, but also in
other tissues and organ systems. (Lyons et al, 1990)
20

21. Perhaps the greatest evidence for involvement of the BMPs in embryogenesis comes from the
isolation of mRNAs for the BMPs in various tissues, again suggesting multiple roles in both
morphogenesis and pattern formation outside of the skeletal system.
mRNAs for BMP-1, BMP-2 and BMP-4 have been found m the brain, heart, lung, kidney,
spleen, and liver (Wozney et al. 1990)
21

22. Role in tooth morphogenesis
I. BMP’s are expressed during epithelial-mesenchymal
interactions.
II. BMP-2,4,7 expressed in dental epithelium.
III. Expressed in enamel knot-BMP2,7 & associated with
differentiating odontoblasts & ameloblasts.
IV. BMP-3,7 immunolocalized to developing PDL,
cementum, alveolar bone.
V. BMP-2 promote dental follicle to differentiate to
cementoblastic/osteoblastic phenotype
22
Nakashima, 2003

23. Role inOsseo-induction
Urist first described the process of bone induction
from an implant of acellular, devitalized, decalcified
bone matrix (Urist 1965)
Following implantation of inductively active
demineralized bone matrix or BMP, three phases of
osteoinduction are observed, these being:
1. Chemotaxis,
2. Mitogenesis,
3. Differentiation (Urist et al, 1968b, Reddi et al.
1987)
23

24. Osseo-induction
1. Chemotaxis initially brings polymorphonuclear leukocytes into the implant area, followed
by fibroblasts and cell attachment to the matrix
2. In mitosis, we see proliferation of mesenchymal cells at day 3 (Reddi et al. 1987).
Coinciding with the aggregation of mesenchymal cells is an increase ofType I collagen
mRNA, which may be an indicator of increased activity in these cells (Sakano et al, 1993)
3. Differentiation of mesenchymal cells into chondroblasts takes place by day 5.This is
believed to occur through the close matrix-cell interaction, and results in the synthesis of
extracellular matrix components typical of cartilage
24

25. 4. Following vascular invasion by day 9, maturation of chondrocytes and mineralization of
cartilage takes place. Osteoblasts appear at days 10 through 12 and form new bone matrix
while chondrocytes are active in removing the calcified cartilage
5. From days 12 through 18, osteoclasts remodel the newly-formed bone and selectively
dissolve the implanted matrix, resulting in an ossicle of new bone complete with marrow by
day 21 (Reddi et al. 1987),
Apparently, the only biological difference between induced heterotopic bone and orthotopic
bone is the lack of a true periosteum in heterotopic bone, which "might explain why such
bones do not proliferate or regenerate after cessation of inductive stimuli" (Wlodarski 1992)
25

26. Role in wound healing
The importance of BMP in experimental fracture healing of the
rabbit mandible has been observed by immunohistochemical
methods.
It would appear, then, that upon fracture. BMP is liberated in
the fracture gap and acts as a transcription factor to regulate
the proliferation and differentiation of mesenchymal cells.
(Campbell & Kaplan 1992. Nakase et al. 1994).
26

27. 1. Initially, large numbers of positively stained mesenchymal cells migrate and proliferate in
the fracture gap during the hematoma stage within 3 days
2. In the callus formation stage at day 7, mesenchymal cells accumulate around the
periosteum and also within the bone marrow
3. Positively stained osteoblasts are observed at day 14 along with bone and cartilage
formation.
4. By days 21 and 30, with the maturation of new bone mass bridging the fracture gap, the
number of positively stained mesenchymai cells decreases (Lianjia &Yan 1990)
27

28. Delivery systems
28

29. Delivery systems
Although utilization of a matrix is not essential, it does provide advantages:
1. immobilization of the protein in a specific area and retaining it at the site
for the time necessary for induction to occur
2. allows a lesser amount of BMP to be effective
3. define the shape of the resulting bone
4. Protection from degradation
29

30. Three major strategies for growth factor delivery:
1. Protein therapy systemic or local
2. Gene therapy,
3. Cell therapy
30

31. Systemic protein therapy
The observation of elevated serum BMP levels in growing children and decreased levels in
patients suffering from osteoporosis (Einhorn, 1992) gave rise to the idea of the systemic
application of BMPs to treat osteoporosis patients
However, the systemic application of BMPs still requires the development of an appropriate
carrier molecule that protects BMPs from proteolytic deactivation without impeding their
function
The major concern regarding systemic delivery is that only a small amount of the injected
protein arrives at the diseased target tissue.
31

32. Local protein therapy
Requirements of delivery systems:
Ideally, the carrier for BMP should be
1. Noncollagenous
2. Biocompatible
3. Immunogenically inert
4. Osteoconductive
5. Bioabsorbable (Miyamoto et al, 1993, Kenley et al, 1993),
6. As well as support angiogenesis and subsequent vascularization (Holiinger & Chaudhari
1992)
7. Optimal cost and handling properties
32
oLee MB. Bone morphogenetic proteins: background and implications for oral reconstruction:
a review. Journal of clinical periodontology. 1997 Jun;24(6):355-65.

33. The degradation rate of the carrier matrix should be in synch with the rate of bone
regeneration.
If the matrix degrades too slowly, it will inhibit bone growth and retard the remodeling
process.
However, if the carrier matrix degrades too quickly, the risk is that the defect shape will no
longer be detected by the matrix, which often serves as a template for new tissue.
33

34. The pharmacokinetics of BMP release from a matrix is generally characterised by two
phases. After application, a short initial burst of BMP is followed by a second phase of delayed
release
In the first phase: concentrations far above a physiological level of BMP doses may diffuse,
causing systemic and local toxicity. Furthermore, dose escalation seems to cause a decrease in
the number of responding cells, resulting in a slower rate of bone formation.
During the second phase: an effective factor level must be maintained over time, supporting
mitosis and cell differentiation, and resulting in bone formation.
34

35. A fast degradation and fast release of BMP-2 induced bone formation to a greater extent,
whereas cementum formation was significantly greater with the slow degrading and slow
releasing BMP gelatin carrier. (King GN, 1998)
35

36. 36
Inorganic : Hydroxyapatite, as an example of an inorganic matrix, has been used as a delivery vehicle
alone and as a composite carrier with tricalcium phosphate, collagen, and coral.
The major advantages of an inorganic matrix are its strength in supporting the surrounding tissue
and preserving bone function, and its ability to allow osteoconductive bone formation. Additional
benefits are immunological inertness and the slow biodegradation of some of the materials.
Organic : Among the organic matrices, collagen and synthetic polymer delivery vehicles currently
show the greatest potential for clinical use.
create various delivery vehicles: collagen sponges, strips, gels, membranes, and others

37. An absorbable collagen sponge (ACS) was the first BMP
carrier technology to be approved by the US Food and Drug
Administration (FDA).The absorbable collagen sponge is a
bovine type I collagen matrix that is soak loaded with a
BMP solution before surgical implantation
however, it is vulnerable to tissue compression.
A small percentage of patients develop antibodies to
bovine collagen (4-6%) or rhBMP-2 (Hollinger et al., 2000).
The problems of bovine material have been addressed with
the development of synthetic polymers.
37

38. 38
Synthetic polymers:
Polylactide co-glycolide (PLGA) not only combines the absorptive ability of polylactide with the
mechanical strength of polyglycolide, making this material particularly interesting for craniofacial
surgery, it can also be manufactured in various forms, depending on the intended clinical use
Metals: BMP has also been tested in various forms with titanium. Kawai et al, infused titanium sponges
2 mm in diameter with partially purified bovine BMP, sealed them in gelatin capsules and implanted
them in mice.
However, the average of new bone obtained from the BMP-Ti composite was slightly less than the
control which received BMP only.

39. There are some disadvantages associated with the carriers such as lack of bone induction:
1. with BMPs combined with hydroxyapatite alone – probably as a result of the lack of
resorption of hydroxyapatite and the tight binding affinity between BMPs and
hydroxyapatite;
2. moreover, immunogenecity and risk of disease transmission with the use of demineralized
bone matrix
3. acidic breakdown products of synthetic polymers which might prove detrimental to wound
healing.
39

40. FDA approved products
There are currently two main collagen-
based products containing BMP-2 or BMP-
7 that were approved by the FDA in recent
years for human clinical use:
Infuse Bone Graft (Medtronik, US;
Wyeth, UK), containing rhBMP-2, and
BMP-2 Infuse bone graft was approved for
certain interbody fusion procedures in
2002, for open tibial fractures in 2004, and
for alveolar ridge and sinus augmentations
in 2007 (McKay et al., 2007).
The INFUSE® Bone Graft consists of two
components–recombinant human Bone
Morphogenetic Protein-2 (rhBMP-2) placed on an
absorbable collagen sponge (ACS).
40

41. Osigraft (Stryker Biotech), containing rhBMP-7, known by the designation of OP-1
(osteogenic protein-1).
BMP-7Osigraft was approved for long bone fractures and as an alternative to autografts in
patients requiring posterolateral lumbar spinal fusion
41

42. Gene therapy
An alternative strategy, regional gene
therapy, attempts to overcome these
problems by providing a time- and
dose-controlled delivery of growth
factors, cytokines, or morphogens for
inducing bone formation
Gene therapy can be classified as in
vivo or ex vivo:
42
Fisher, 2011

43. This study utilized ex vivo BMP-7 gene transfer to stimulate tissue engineering of alveolar
bone wounds. Syngeneic dermal fibroblasts (SDFs) were transduced ex vivo with adenoviruses
encoding either green fluorescent protein (Ad-GFP or control virus), BMP-7 (Ad-BMP-7), or an
antagonist of BMP bioactivity, noggin (Ad-noggin). Transduced cells were seeded onto
gelatin carriers and then transplanted to large mandibular alveolar bone defects in a rat
wound repair model.
These results demonstrate the first successful evidence of periodontal tissue engineering
using ex vivo gene transfer of BMPs and offers a new approach for repairing periodontal
defects
J Periodontol 2003;74:202-213.
43

44. Large osteotomy defects were created in the edentulous ridge areas followed by the
placement of dental implant fixtures. Recombinant adenoviral vectors encoding either the
BMP-7 or the luciferase gene were delivered to the osseous defects using a collagen matrix.
The results revealed sustained, targeted transgene expression for up to 10 days at the
osteotomy sites with nearly undetectable levels by 35 days.Treatment of dental implant
fixtures with Ad/BMP-7 resulted in enhancement of alveolar bone defect fill, coronal new
bone formation, and new bone-to-implant contact. In vivo gene therapy of BMP-7 offers
potential for alveolar bone engineering applications.
44

45. 2008:This study evaluated a novel approach to regeneration of the periodontal attachment
apparatus using a combination of ex vivo autologous bone marrow mesenchymal stem cells
(MSCs) engineered by replication-defective adenovirus to express the BMP-2 gene and
Pluronic F127 (PF127).Twenty-four periodontal defects were surgically created in 12 New
Zealand white rabbits
This approach regenerated not only cementum with Sharpey’s fiber insertion, but also
statistically significant quantities of bone, re-establishing a more normal relationship
among the components of the regenerated periodontal attachment apparatus
45

46. The BMP-2/7 gene expression vector was introduced via electroporation into the target site
in the periodontal tissues of the first molar of the rat maxilla.
The findings demonstrate that the combination of the BMP-2/7 non-viral vector and in vivo
electroporation represents a promising candidate non-surgical strategy for alveolar bone
regeneration therapy.
46

47. Role in periodontal
regeneration
47

48. Tissue engineering
Three key elements:
1. cells
2. scaffold
3. signals and growth factors
Ex –vivo or In-vivo (ERM)
48
Nakashima, 2003

49. Role in periodontal regeneration
The rationale for growth factor administration in periodontics is to enhance and/or
accelerate the physiological wound healing capacity that may be insufficient to promote a
complete healing of the affected structures.
Over the past two decades, numerous studies have explored the potential of using biologic
proteins and peptides in periodontal regeneration.
In previous experiments, the efficacy of bone-derived BMPs (BMP-2, osteogenin, osteoprotein-1)
for regeneration in surgically created large furcation defects in the mandibular first and second
molar was investigated in adult male baboons (Papio ursinus). Histological analysis showed that
BMPs, in conjunction with the collagenous matrix, induced cementum, periodontal ligament,
and alveolar bone regeneration. (Ripamonti U, 1994)
49

50. Another study reported that partially purified osteogenin, isolated from human bone matrix, when
reconstituted with allogenic freeze dried deminerlized bone matrix, enhanced new connective tissue
attachment, and alveolar bone regeneration in a root submerged environment in a series of human
biopsies (Bowers G, 1991)
The effect of rhBMP-2 was evaluated in the surgically created critical size, supra alveolar
periodontal defects in mandibular premolar teeth in beagle dogs which were implanted with
rhBMP-2/ ACS at different concentrations. Extensive alveolar regeneration and limited cementum
regeneration were observed. However, ankylosis was observed in all teeth receiving rhBMP-2/ACS
without apparent correlation with rhBMP-2 concentration or dose.The ankylotic union was observed
in the coronal aspect of supra alveolar defects (Wikesjö UM, 1999)
50

51. Other studies using rhBMP-2 or rhOP-1 in various carriers also provide evidence of ankylosis in large
experimental periodontal defects in rodent, canine, and nonhuman primate models. (Ishikawa I, 1994)
(Wikesjö UM, 1999)
51

52. Osteogenetic protein-1 (BMP-7) has been evaluated for periodontal wound healing regeneration using
surgically induced mandibular molar class II furcation defects in baboons. Defects implanted with
rhOP-1 at 0, 100, and 500 μg/g bovine bone insoluble collagen matrix were subject to histometric analysis
following an 8-week healing interval. Sites receiving rhOP-1 showed significant cementogenesis,
including inserting sharpey fibers (Ripamonti U, 1996)
A similar study using a 24-week healing interval showed that rhOP-1 at 0.5 and 2.5 mg/g collagen matrix
induced significantly greater periodontal ligament (PDL) and alveolar bone formation.These
observations demonstrate beneficial effects of OP-1 as a candidate therapeutic agent for periodontal
wound healing/regeneration (Ripamonti U, 2002)
52

53. 1991:The purpose of this study was to determine if osteogenin combined with demineralized
freeze dried bone allograft (DFDBA), a bone-derived matrix, and with a bovine tendon-
derived matrix will enhance regeneration of intrabony defects in humans.
There were no significant differences between the tendon-derived matrix plus osteogenin and
the tendon-derived matrix alone in either the submerged or nonsubmerged environment.
53

54. 2004: purpose of this study was to evaluate the effect of the pool of bovine BMPs on the
treatment of intrabony defects.
The test defects were treated with combination of a pool of bovine bone morphogenetic and
resorbable hydroxyapatite carrier (BMPs- HA), bovine demineralized bone matrix (MB) and
coverage by a bovine collagen barrier membrane.The control defects were treated with MB-HA
and covered by a bovine collagen membrane.
There were no significant differences between the test and controls subjects.These findings
suggest that the use of a pool of bovine BMPs do not provide added effects to GTR in the
treatment of intrabony defects.
54

55. 55
oLin Z, Rios HF, Cochran DL. Emerging regenerative approaches for periodontal reconstruction: a systematic review
from the AAP RegenerationWorkshop. Journal of periodontology. 2015 Feb;86:S134-52.

56. 2016: A randomized double-blind controlled trial was carried out, wherein rhBMP-2 was used in
the test group after open flap debridement (OFD).The control group was only OFD.The same
examiner carried out both clinical and radiographic measurements at baseline, 6 and 9 months.
The results obtained in this study suggest that rhBMP performs effectively in intrabony
defects, providing clinical reduction in pocket depth, improvement in CAL as well as
radiographic defect depth fill and defect resolution.
56

57. 2017:A randomized controlled clinical trial conducted where in the IBDs were treated with
either autologous PRF with open flap debridement (OFD) or recombinant rhBMP 2 with OFD
or OFD alone.
Within the limits of the present study, results suggest that in terms of hard tissue
regeneration, rhBMP 2 has shown significantly better outcome in treatment of IBDs.
However, PRF encourages superior soft tissue healing compared to rhBMP 2.
57

58. It was found that rhBMP-2 showed statistically significant results with respect to radiographic defect
resolution, CAL, and PD reduction at 9 months compared to open-flap debridement but showed
statistically significant results only with respect to radiographic bone fill when compared with
platelet-rich fibrin at 6 months.
Conclusion: The rhBMP-2 may provide a promising alternative to traditional grafting procedures
that can enhance periodontal regeneration in patients having intrabony defects. Due to limited
human studies, it can be concluded that no definitive evidence exists to ascertain the effectiveness
of rhBMP-2 in the treatment of intrabony defects in periodontal diseases.
58

59. Alveolar ridge augmentation
Three rhBMP-2 concentrations – 0.43, 0.75, and 1.5 mg/mL – were used. Mean rhBMP-2 dose
ranged from 0.3 to 1.9 mg.
Fiorellini and colleagues in 2005 in a large study demonstrated that rhBMP-2/ACS inlays (rhBMP-2 at
1.5 mg/ mL) maintained the alveolar ridge height at extraction socket sites, whereas sites that did
not receive treatment lost 1.2 mm. This trial identified 1.50 mg/ml as the optimal dosage of rhBMP-2
for grafting purposes
Case series suggested that combining rhBMP-2/ACS with a titanium reinforced mesh (Hart & Bowles,
2012; Misch, 2011; Ribeiro Filho, Francischone, Oliveira, Ribeiro & do Prado, 2015) or with allogenic
bone grafts (Misch, 2017) was a successful treatment option for ridge augmentation prior to implant
placement.
59

60. In particular, rhBMP-2/ACS combined with a titanium mesh showed comparable regenerative outcomes
to an autogenous bone graft/titanium mesh at 6 months of healing in patients in need for horizontal ridge
augmentation (de Freitas, Susin, Spin-Neto, Marcantonio & Wikesjo, 2013)
Likewise, a composite graft combining rhBMP-2/ACS, crushed cancellous freeze-dried allogeneic bone and
platelet-rich plasma (PRP) combined with a titanium mesh resulted in the regeneration of large vertical
ridge defects as predictably as autogenous cancellous bone/titanium mesh (Marx, Armentano, Olavarria &
Samaniego, 2013)
60
The adverse events associated with the use of rhBMP-2 /ACS were transient and consistent with the surgical
procedure performed and included moderate swelling, oedema and few cases of mild erythema (Cochran,
Jones, Lilly, Fiorellini & Howell, 2000; Howell et al., 1997; Misch, 2010).

61. Peri-implant defects
More recently, in an RCT, implants that were placed in bone augmented with DBBM and a collagen
membrane with or without the addition of rhBMP-2 showed no significant differences in terms of
radiographic and clinical parameters up to 5 years after loading (Jung et al., 2003, 2009)
In a pilot study, clinical examination at 3-year follow-up of dental implants placed into sites treated with
rhBMP-2/ACS revealed stable marginal bone levels and healthy peri-implant tissues (Cochran et al.,
2000). Histological biopsies collected during implant placement revealed that the quality of the newly
formed bone was similar to the surrounding native bone
61

62. Maxillary sinus augmentation
Three rhBMP-2 concentrations (0.43, 0.75, and 1.5 mg/mL) were used.The mean rhBMP-2
dose ranged between 2.9 and 20.8 mg per site.
Studies in humans on application of bone morphogenic proteins in sinus augmentation indicate that
rhOP-1/demineralized bone matrix has the potential to induce bone formation following sinus
augmentation. [(Boyne PJ, 1997), (HowellTH, 1997), (Sailer, 1994), (Groeneveld, 1999), (van den Bergh
JP, 2000), (Boyne PJ, 2005), (Moghadam HG, 2001), (Warnke PH, 2004)]
Boyne et al, 2006 implanted collagen sheets soaked in rhBMP-2 solution in the maxillary sinuses of 12
edentulous or partially edentulous patients with severe atrophy of the maxilla. The subsequent increase
in height of the treated maxilla varied between 2.3 and 15.7 mm.
62

63. BMP-2 concentrations of 0.75 mg/mL and 1.50 mg/mL induced bone formation of similar quantity and
quality to autogenous bone or a combination of autogenous bone and allogeneic bone, and they were
associated with greater amount of facial oedema and erythema but less pain within the first 4 post-
operative months (Boyne, Lilly, Marx, Moy & Nevins, 2005;Triplett, Nevins, Marx, Spagnoli & Oates,
2009).
63
Contrary to the previous findings, other studies did not report a significant benefit when using BMP-2
for sinus augmentation. In particular, better clinical and radiographic outcomes were associated with
autogenous bone grafts compared to the combination of a bovine organic osseous matrix and bovine
BMP (Serra, Ricardo de Albergaria Barbosa & Mazzonetto, 2006).
Likewise, the histomorphometric and CT outcomes after sinus augmentation with rhBMP-2 delivered in
either HA or BCP carrier failed to show any superior osteoconductivity of these grafting materials
compared with DBBM (Kim,Chung, et al., 2015; Kim, Lee, et al., 2015).

64. 2014: rhBMP-2/ACS yielded clinically meaningful bone formation for maxillary sinus
augmentation that would allow placement of regular dental implants without consistent
differences between rhBMP-2 concentrations. Nevertheless, the statistical analysis showed
that sinus augmentation following autogenous bone graft was significantly greater.
In extraction sockets, rhBMP-2/ACS maintained alveolar ridge height while enhancing alveolar
ridge width. Safety reports did not represent concerns for the proposed indications.
Conclusions: rhBMP-2/ACS appears a promising alternative to autogenous bone grafts for
alveolar ridge/maxillary sinus augmentation; dose and carrier optimization may expand its
efficacy, use, and clinical application.
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65. 2016:Ten studies met the criteria for systematic review; eight studies were included in the
meta-analysis. Five studies assessed localized alveolar ridge augmentation andThree studies
assessed maxillary sinus floor augmentation
Adverse events were inconsistently reported, ranging from no complications to widespread
adverse events.
In localized alveolar ridge augmentation this meta-analysis demonstrated that rhBMP-2
significantly increases bone height.
rhBMP-2 does not perform as well as autograft or allograft in maxillary sinus floor
augmentation. Long-term clinical success and adverse events need to be reported with more
consistency before definitive conclusions can be made.
65

66. Complications related to BMP use
Complications of rhBMP-2 Use in Lumbar Spine Surgery
Cahill reported the following complications with 22 their respective means:
vertebral osteolysis (44%), graft subsidence (27%) and graft migration(31%), formation of
neutralizing antibodies against BMP-2 (26%), ectopic/heterotopic bone formation (7%), and
hematoma formation (3%).
On the other hand, concerns were raised by the Food and Drug Administration (FDA) with
regards to rhBMP-2 use in anterior lumbar interbody fusion (ALIF) and retrograde ejaculation
(RE).
The FDA reported retrograde ejaculation (RE) events (8%) in the rhBMP-2 groups compared
with (1.4%) in the control group
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67. Carcinogenesis
The latest independent review of all published and unpublished data on safety and
effectiveness of rhBMP-2 by the Yale University Open Data Access Project (YODA) concluded
that at 24 months, cancer risk was increased with rhBMP-2 use. (Fu et al, 2013)
67

68. Contraindications
1. Known hypersensitivity
2. Active malignant disease or history of malignant disease
3. Skeletally immature patients (<18 years of age or no radiographic evidence
of epiphyseal closure).
4. Pregnant women
5. Active infection at site
68

69. Future challenges
Developing an Appropriate carrier technology for controlled release
Conducting Well designed clinical trials in humans evaluating periodontal
regeneration
Establishment of safety regarding BMP use
Evaluation of Gene therapy for periodontal tissue engineering
69

70. Conclusion
After decades of intense research BMPs have been shown in preclinical and clinical studies to
enhance periodontal regeneration. BMPs have demonstrated beyond doubt their role as a
superior alternative of autogenous bone graft.
However, much of the data in BMP research has been derived from animal studies which are
important as far as providing base line data for further clinical studies is concerned.
The available data on use of rhBMP-2 and 7 in humans are promising in showing an
osteoinductive potential in periodontal regeneration, but not conclusive in the predictability
and consistency in results to allow clinical use at this stage, other than in well-designed clinical
trials.
70

71. The true efficacy and safety of these agents for different scenarios must be established in
carefully designed prospective randomized clinical trials before they are approved for use.
A disconcerting issue however, is the cost of BMP which limits their clinical use.
Current active areas of research are centered on tissue engineering and gene therapy
strategies that may result in more predictable regenerative outcomes in the future.
71

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76. Thank you! Stay safe!
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