Citation preview
Summary
It is undeniable that in terms of ideal bone healing for implant
osseointegration, an au-
tograft offers the best clinical outcomes and is widely considered
“the gold standard.”
Nevertheless, replacement options are necessary, and a wide variety
of synthetically fab-
ricated alloplasts are available to fulll this task. The literature
is abundant with numerous
clinical studies reporting on the use of animal-derived bone
grafts, yet the quality of bone
that is regenerated with xenografts is still considered suboptimal.
Often understated are
the relevance and interest of synthetic bone substitute materials.
They offer the major
advantage of being manufactured in unlimited supply without the
variability that exists with
allografts. Considering the advantages and disadvantages of each of
the four classes of
bone grafts, synthetic materials have been shown to offer
regenerative potential that may
be preferred under certain clinical indications. This chapter
provides a background on
the numerous types of synthetically fabricated biomaterials and
compares their biologic
properties and resorption patterns. Furthermore, clinical case
examples are presented
with synthetic bone grafts, and their clinical indications are
discussed.
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It can be daunting to treatment plan with the ideal biomaterials
for each individual patient, especially considering the impact of
patient preferences due to their cultural and/or religious beliefs.
Interestingly, a patient survey was carried out in Turkey, a pre-
dominantly Islamic country, and porcine-derived biomaterials were
reported as least desired.1 Alloplastic grafts, however, were
preferred by more than 60% of the respondents. Synthetic materials
are free of any organic origin, and while exceedingly rare, prion
infection from medical bovine-derived products has been addressed
in the literature.2 Furthermore, many patients would prefer a
synthetically fabricated material as opposed to animal-derived
products simply based on their own personal, cultural, or religious
preferences. This chapter aims to detail the various synthetic
materials that are currently available and discusses their material
chemistry, composition, classication, and research reporting on
their use.
Nomenclature of Synthetic Biomaterials
Synthetic bone substitute materials are manufactured free of any
biologic source (human or animal). Nevertheless, their
nomencla-
ture is not always consistent. In dentistry, they are often termed
alloplasts or alloplastic, yet in other elds of medicine (such as
orthopedics) these terms are rarely used.3–5 This class of bone
substitutes encompasses many types of synthetically fabricated
materials including bioglasses, bioceramics, ceramics, glasses,
calcium sulfates, hydroxyapatites, and so forth. The naming of
these may be even further complicated when commercial trade- mark
names are included in the mix (Table 6-1). The Glossary of Oral and
Maxillofacial Implants denes alloplasts as “inorganic, synthetic,
or inert foreign material implanted into tissue.”6 Another
organization, the International Congress of Oral Implantologists
(ICOI), denes an alloplast as “synthetic, inorganic material used
as a bone substitute or as an implant, synonymous with al-
loplastic graft.”7 Synthetic materials are all derived from calcium
phosphate (CaPO4) apatites, the major component of human
mineralized tissues (bone, teeth, tendons).4 These tissues are
“biologic apatites” that provide structure and function. They can
be found elsewhere in the body as well, including as pathologic
soft tissue calcications, urinary stones, salivary stones, athero-
sclerotic plaques, and arthritic cartilage. They are also present
in toothpaste, various foods, fertilizers, antacids, and
detergents, among other products. Chemically pure calcium
phosphates are clear crystals, yet in powder form they become
white. Their chemical compositions vary depending on the phosphate
ion, giving the material various names including
orthophosphates,
TABLE 6-1 Synthetic bone material examples identied from the
reviewed literature
Product Manufacturer Description/constituents
Cerasorb Curasan Pure β-TCP
NovaBone Dental Putty
NovaBone 70% calcium phosphosilicate, with added polyethylene
glycol, embedded in glycerin
Ostim paste Osartis 35% nanohydroxyapatite in water
NanoBone Artoss Nanohydroxyapatite (as particulate or as paste with
silica gel)
nanoXIM Fluidinova Nanohydroxyapatite water-based paste
DentoGen Orthogen Calcium sulfate
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metaphosphates, pyrophosphates, or polyphosphates. For rele- vance
and simplicity, nearly all human calcied tissues comprise calcium
orthophosphates, and only these subtypes are detailed throughout
this chapter.
Calcium phosphates consist of three major elements, namely calcium,
phosphorus, and oxygen. Many also contain hydrogen, especially if
water is incorporated, and are differentiated by the number of
hydrogen ions (mono-, di-, tri, tetra-). Bioglasses and bioceramics
are inert, fragile, translucent materials derived from silica that
is heated into glass, such as window panes. In actuality, glass is
not a composition but a state of matter.5 Glass in fact does not
have an ordered crystalline structure; rather, it is randomly
arranged, and it is dened as any material that has cooled from the
melt without crystallizing. True glasses are amorphous, and
bioactive glasses, unlike window pane glass, are reactive in
biologic tissues. Conversely, ceramics are mainly comprised of
crystals. For example, zirconia crystals in restorative and implant
materials produce highly resilient ceramic materials. The term
glass-ceramics denotes a combination to improve their added
properties. Lithium disilicate of dental restorations is a
glass-ceramic.
Bioglass is technically a misnomer in the literature. The original
Bioglass is in fact a registered trademark name of the commercial
product invented at the University of Florida in the 1960s.8 The
alternative and correct term for these materials is bioactive
glass. One of the earliest uses of bioactive glass was the
insertion of original Bioglass cones into fresh extraction sockets
in 1987 as ridge-preservation devices/implants be- neath removable
dentures.9 Today, Bioglass is incorporated into the toothpaste
widely known as Sensodyne Repair & Protect
(GlaxoSmithKline).10
Curiously, window pane glass and bioactive glass are both comprised
of soda, lime, and silicate. However, bioactive glass contains much
less silicate and a lot more calcium and phos- phate, which aids
its dissolution in biologic tissues.5 When in- serted in a bone
defect site, the glass resorbs slowly, resulting in ion exchange.
The importance of calcium and phosphate ions during bone
regeneration has been shown in many studies. Phosphate ions are
known to regulate osteoblast apoptosis,11
osteopontin production,12 and the mineralization rate,13 and
calcium ions have been reported to have a profound effect on
osteoblast proliferation and regulation.14,15 The released bioac-
tive glass ions cause a rise in the pH of the local environment.
Calcium phosphate forms on the outer layer of the glass par- ticles
in the form of hydroxycarbonate apatite (HCA), which is very
similar to bone hydroxyapatite, thereby allowing the parti- cles to
bond to bone. After the formation of HCA, phagocytic macrophages
are activated, stem cells attach and differentiate, and a matrix is
generated that continues to mature.
The terms bioglass and bioceramic continue to be used inter-
changeably, albeit slightly incorrectly. Ultimately, these
materials
for use in regeneration of alveolar bone are under the umbrella of
calcium orthophosphates, which include hydroxyapatite, β-tricalcium
phosphate (β-TCP), and biphasic calcium phos- phates (BCPs), all of
which may generally be referred to as bioactive glass or
bioceramic, depending on their chemistry and structure.4,5
Biologic Background: Selecting Synthetic Materials
The absolute prerequisites for guided bone regeneration (GBR) are
graft stability and space maintenance. In the absence of a bone
material and/or barrier membrane, these functions are provided
(usually inadequately) by the blood clot. This is then the
rationale for using a bone substitute material. Scaffolds are
required to chemically and structurally aid the regeneration of
connective tissues, directing cell activity toward desired
phenotypes.16 Such a 3D construct must be able to exchange
signals—be it osteogenic, osteoinductive, or osteoconduc- tive—and
gradually be replaced by and/or incorporated into native bone.
Today a wide array of synthetically fabricated alloplasts exists on
the market, each featuring differences in material composition and
surface topography (Fig 6-1). For the regeneration of bone, the
orthopedic literature states that hydroxyapatite is the ideal
scaffold for bone repair, but this might not be true for all
applications of alveolar bone augmentation. For oral regeneration,
the clinician needs to consider the following:
• What is the planned current or future procedure? For example, is
the site to receive a dental implant, a xed prosthesis pontic, a
removable prosthesis, or no prosthesis?
• What is the timing of these procedures? Is a dental implant to be
inserted simultaneously with the GBR procedure? Is the implant to
be inserted later? If a socket is being grafted, when is re-entry
planned? What is the age of the patient? If craniofacial growth is
not yet complete, is delay for several years expected?
• To what degree will the implant be inserted into the bone
substitute material? What tissue will provide (the majority of) the
implant’s bony support? Native bone or augmented bone?
• What site is to be grafted? Maxillary sinus? Extraction socket?
Buccal defect? Crestal ridge defect? In the bone envelope or
outside? Will it be supported by adjacent teeth?
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FIG 6-1 Scanning electron microscope (SEM) images of several
synthetic bone substitutes, depicting their sur- face
characteristics. In general, Cerasorb (Curasan) has a more
roughened surface topography than the other bone grafts. Both
maxresorb (botiss) and Straumann BoneCeramic are extremely smooth
in their surface to- pographies.
Cerasorb (Curasan)
Hydroxyapatite
89
While there may never be a gold standard set of protocols to
address all of these raised questions, several factors highlighted
below should be addressed.
Resorption
The resorption of bone grafting materials is one feature that cli-
nicians consider very important, and there is signicant variability
among synthetic materials. It is widely reported that synthetic
hydroxyapatites take a long time to be replaced by native bone,
while tricalcium phosphates resorb rapidly.17 When resorbed, as
with the osteoclastic activity of natural bone, constituent ions
are released that stimulate bone formation. Konermann et al18
performed experimental analysis of osteoclast activity on both
xenograft hydroxyapatite (cerabone, botiss) and synthetic calcium
phosphate materials (maxresorb, botiss; NanoBone, Artoss).
Interestingly, cultured osteoclasts mixed with the bone substitute
materials all resorbed over time and released primar- ily calcium
phosphates to the surrounding microenvironment. NanoBone is a
material fabricated from hydroxyapatite em- bedded in silica and
thus releases silica when resorbed. After 5 days of culture with
osteoclasts, it was found that cerabone released two times more
calcium and phosphate into the lo- cal environment than NanoBone
did. It was further found that maxresorb released signicantly more
than the other materials, at approximately ve to six times the
concentrations.
Structurally, the micropores have also been described as be- ing a
prominent feature of bone substitute materials. Scanning electron
microscope (SEM) analysis of these materials showed that cerabone
has the fewest pores, while maxresorb has the most abundant
micropores. However, SEM analysis showed sparse osteoclast adhesion
to maxresorb versus abundant cellular adhesion to NanoBone and
cerabone. Despite the sparse cellular adhesion to maxresorb, the
concentrations of released ions were high. Moreover, Horvath et
al19 showed that calcium phosphate bone substitute material (Ostim,
Osartis) was still present in some human histology samples 7 months
after healing of periodontal defects. Future research is ongo- ing
to determine the various factors responsible for calcium phosphate
resorption, but variability certainly exists within the
literature.
Hydroxyapatite Pure hydroxyapatite (Ca10[PO4]6[OH]2) is among the
least soluble of the calcium phosphates and is not found in
biologic systems.4
This is somewhat different from bone hydroxyapatite, and here the
reader is strongly advised not to confuse sintered xenograft bone
hydroxyapatite (such as cerabone) with commercially, articially
prepared hydroxyapatite (such as Osbone [Curasan]). Synthetic
hydroxyapatite is prepared by numerous techniques, broadly divided
into (1) solid-state chemical reactions or (2) wet reactions
(precipitation, hydrothermal, or hydrolysis of other calcium
phosphates). These preparations have different sin- tering
temperatures (heated to very high temperatures) and have numerous
uses, including as additives to toothpastes and coatings of medical
implant devices.
Hydroxyapatite has been studied extensively in the literature in
human and animal models. In a histologic study, rabbit sinus- es
were augmented with hydroxyapatite derived from animal origin,
which produced more bone when compared to sinuses augmented with
synthetic hydroxyapatite.20 At 3 months, the amount of new bone was
rather minimal for all three materials studied, but the two
bovine-derived hydroxyapatites (Endo- bon, Zimmer Biomet; Bio-Oss,
Geistlich) produced more bone than the pure synthetic
hydroxyapatite (Osbone). The histologic slides demonstrated
intimate new bone contact with the residual graft particles and
large interconnecting bridges in the Bio-Oss samples. Bio-Oss
demonstrated microporosities or cavitations that the other
materials did not, which the authors relate to the improved
performance of the material, possibly enhancing os- teoblast
cellular attachment. Therefore, at present, synthetically pure
hydroxyapatite bone grafting materials have been shown to integrate
less efciently into host tissues when compared to animal-derived
hydroxyapatite.
In general, synthetic hydroxyapatites persist at augmentation sites
due to their low substitution rate.21 If grafting of the socket and
early re-entry for implant placement is planned, there may not be
adequate time for bone formation to take place. The implant is
therefore at greater risk for being inserted into nonliv- ing
material. Conversely, if the objective is to correct a contour
defect (for example, a buccal defect at a missing tooth site) and
the majority of the implant is inserted into native bone for
osseointegration, then a slowly replaced material would provide the
space maintenance over the long term. If a young patient lost a
tooth and has not yet completed craniofacial growth, then grafting
the socket as an attempt to preserve the ridge is more suitable
with a slowly resorbing biomaterial.
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Calcium Phosphosilicate As discussed, bioactive glass materials
typically contain calcium, phosphate, and silicate. Probably the
best-known example is NovaBone Dental Putty (NovaBone), a 70%
calcium phospho- silicate with added polyethylene glycol embedded
in glycerin. The paste is designed to improve the handling
properties for the clinician. Its use as a putty has therefore been
favored in many clinical situations. For example, Huwais and Meyer
re- ported its combination with implant osseodensication.22 In a
protocol termed the Versah lift, a transcrestal sinus membrane
elevation procedure propels bone into the sinus beneath the sinus
membrane (see Fig 6-6). As a grafting material, NovaBone is
recommended with a lower risk of perforation.
Similarly, Mahesh et al23 grafted human sockets with Nova- Bone
Dental Putty and compared bone formation to that achieved with
Bio-Oss (all socket grafts were sealed with a collagen plug). The
authors published some insightful human histology of the trephined
bone cores at 5 to 6 months of healing (Fig 6-2). Signicantly more
new bone formed from the bioactive glass putty, as much as 36% to
57%, between 4 and 6 months. Also, it was noted that NovaBone
resorbed at approximately 20% per month.23
β-Tricalcium Phosphate β-tricalcium phosphate (β-Ca3[PO4]2),
abbreviated as β-TCP, is one of the two polymorphs of tricalcium
phosphate. This mate- rial is notably different and cannot be
prepared from aqueous solutions. There are four ways in which β-TCP
is prepared, yet most bone substitute manufacturers do not
adequately report their processing techniques. Typically, β-TCP is
prepared by sintering calcium-decient hydroxyapatite to high
temperatures.4
It can also be prepared at lower temperatures in water-free me-
diums or by solid-state acid-base chemical interactions. Note that
ion-substituted β-TCP does occur in nature; as with pure
hydroxyapatite, pure β-TCP is not found in biologic systems.
Commercially available examples of β-TCP bone grafts include
maxresorb and Cerasorb (Curasan).
β-TCP is probably best known for its rapid resorption. One question
that intrigued many investigators was whether the timing of bone
graft resorption correlates with the rate of new bone formation.
Lambert et al24 compared the healing of rabbit sinuses augmented
with bovine hydroxyapatite (Bio-Oss), a BCP (Straumann
BoneCeramic), and pure β-TCP (Cerasorb).24 New bone formed from
each material, but the architecture differed. At 2 months, the
xenograft formed intimate bridges of bone
FIG 6-2 Histology of trephined cores harvested from grafted human
sockets at 6 months. (a to c) From bone grafted with synthetic
NovaBone. (d to f) From bone grafted with a xenograft (Bio-Oss).
The red tissue represents regenerated bone. (Reprinted with
permission from Mahesh et al.23)
a
d
b
e
c
f
Biphasic Calcium Phosphates
91
between the particles, but bone formation was sparse in the BCP
grafts and nonexistent in the β-TCP grafts. By 6 months, no
material remained within the β-TCP grafts. This study alludes to
the more rapid resorption of pure-phase TCP, demonstrating that
synthetic hydroxyapatite slows this process and that nat- ural
bovine-sintered hydroxyapatite resorbs even more slowly. Therefore,
in certain clinical situations, a slow-resorbing xeno- graft that
forms comparable bone is best suited. In another study, Jensen et
al25 created defects in minipig mandibles and grafted them with
either an autograft, xenograft (Bio-Oss), or β-TCP (Ceros, Thommen
Medical) and later harvested bone sections at 1, 2, 4, and 8 weeks.
Consistent with other studies, the autografts and β-TCP produced
slightly more new bone during initial healing (at 4 weeks).
Biphasic Calcium Phosphates
It is widely perceived that synthetic materials resorb completely
and do so rapidly, and xenogeneic bone substitutes are gen- erally
considered nonresorbable. The literature is abundant with research
reporting on materials termed biphasic calcium phosphates, one of
the earliest reports in dentistry being that by Ellinger et al26 in
1986 treating periodontal intrabony defects. Biphasic refers to a
combination of two materials, generally β-TCP and hydroxyapatite,
whose ratios are adjusted to poten- tially manipulate their
biomedical properties. BoneCeramic, for example, is biphasic,
consisting of 60% synthetic hydroxyapatite and 40% β-TCP. Another
method to control the resorption of calcium phosphates, other than
by creating a biphasic material, is by adding a doping agent such
as silicon, magnesium, or potassium.27 These also may have a
therapeutic effect when they are released into the local
environment (see chapter 21).
Grafting a socket with a substitute for re-entry and implant
placement may typically take place at 3 to 6 months postex-
traction. For sinuses, this may take even longer. Cordaro et al17
carried out a randomized controlled trial comparing bone healing at
grafted human sinuses at 6 to 8 months. Two mate- rials were
compared: a biphasic calcium phosphate (BoneCe- ramic) and a bovine
xenograft (Bio-Oss). Histologically, 23 synthetic bone samples
compared to 25 xenograft samples demonstrated the same amount of
new bone formation (syn- thetic 21.6% ± 10.0% versus xenograft
19.8% ± 7.9%). This amount of bone may be considered low, or lower
than the desired quantity to accommodate a dental implant, and yet
all 109 planned implants achieved appropriate primary sta- bility.
The materials differed at later healing, with less residual
synthetic material remaining than xenograft (26.6% ± 5.2% versus
37.7% ± 8.5%, P < .001). Thus, for sinus augmenta- tion
procedures, BCP bone grafts produced comparable new bone as
xenografts.
Dahlin et al28 also compared synthetic bone substitutes—an
experimental ratio of 10% hydroxyapatite and 90% β-TCP (Fig 6-3),
BoneCeramic (60% hydroxyapatite, 40% β-TCP), and Bio-Oss—and found
that the xenograft produced more new bone at 8 weeks.28
A new novel BCP biomaterial of the same ratio (10% hydroxy- apatite
and 90% β-TCP) was extensively tested by Miron et al.29
This synthetic (formerly VivOss by Straumann, currently Osopia by
Regedent) was compared to Bio-Oss as well as to autografts and
allografts, and all were investigated for their ability to form
ectopic bone in rat muscle. They concluded the following29:
• The xenograft material (Bio-Oss) did not form bone ectopically. •
The allograft (demineralized freeze-dried bone allograft
[DFDBA], LifeNet) formed bone ectopically. • The autograft formed
some bone ectopically, but it was rapidly
resorbed. • The synthetic BCP (formerly VivOss, currently Osopia)
formed
more bone ectopically.
FIG 6-3 Histology of an experimental β-TCP. Note the active
resorption of the β-TCP and the hydroxyapatite (HA) lined with new
bone (NB). (Reprinted with permis- sion from Dahlin et al.28)
β-TCP
NB
HA
Synthetic Bone Substitute Materials
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Contrasted to an experiment in the dog model, the same working
group found the following30:
• The xenograft (Bio-Oss) showed no ectopic bone formation and
little resorption.
• The allograft (DFDBA, Straumann) formed ectopic bone, but it was
rapidly resorbed by 8 weeks.
• The autograft also rapidly resorbed, and there was no ectopic
bone formation at slightly longer time points.
• The synthetic BCP (formerly VivOss, currently Osopia) con-
sistently formed ectopic bone by 8 weeks.
This new class of osteoinductive BCP is highlighted in chapter
7.
Synthetic Polymers
A variety of synthetic materials and admixtures of these have been
described in the literature and continue to be widely inves-
tigated. Tevlin et al31 reported on a composite material scaffold
of a hydroxyapatite and polylactic-co-glycolic acid (PLGA) core
that may be enriched with other materials such as bioactive growth
factors.31 However, experimental socket grafting with
PLGA/hydroxyapatite has demonstrated biocompatibility issues, with
numerous reported failures (though in a limited number of test
sites).32 Konopnicki et al33 evaluated 3D-printed β-TCP/
polycaprolactone scaffolds inserted into pig mandible
defects.33
The results were promising, showing greater cell penetration and
bone formation than in empty defects; however, comparative studies
with standard replacement materials such as allografts and
xenografts are still lacking. Notably, these biomaterials that
incorporate polymers are not widely commercially available yet and
are mostly limited to preclinical testing thus far. Future research
is ongoing.
Titanium Granules
The use of titanium granules as a synthetic bone graft material has
also been reported in the literature. They were rst utilized in
orthopedics in the mid-2000s.34 A study carried out by Arruda et
al35 histologically examined new bone formation in sockets grafted
with titanium granules at 1 month. The control (non- grafted)
sockets presented more new bone. In human subjects, Verket et al36
grafted maxillary sinuses and biopsied the grafts at 6 months; they
found histologic new bone of 16.1% (standard deviation of 9.4%).
This is notably low, and the titanium particles remained (25% of
the total defect volume). Furthermore, the
effect of drilling an osteotomy into titanium particles was not
discussed. Wohlfahrt et al37 debrided peri-implant defects with
chemical decontamination and grafted half of the defects with
porous titanium granules. While the improvement in radiographic
defect ll was reported as signicant, no other notable differenc- es
were observed. Apart from these studies, few studies have further
investigated the use of titanium particles as synthetic materials,
and their use is not clinically recommended at present.
Material Surface and Structure
The porosity of biomaterials has been cited as important for the
ingrowth of capillaries and the ability to form bone. Various
research groups have reported that submicron topography facilitates
osteoblast differentiation and mineralization potential. For
example, Hallman and Thor38 stated that material pore size needs to
be larger than 300 microns. Bohner et al27 stated that macropores
typically are bigger than 50 microns and allow cel- lular and
capillary passage that facilitates bone formation. Yet early
research of Haversian canal diameters in human mandible bone
reported their diameter as 60 to 80 microns.39
To date, no ideal architecture or porosity has been provided,
possibly due to each material’s different surface energy, chem-
istry, and hydrophilicity. Some commercially available products
identify their porosity, such as BoneCeramic, which states that the
material comes in a 90% porosity. SEM images may provide more
accurate depictions of these materials’ surfaces. Figure 6-4
provides high-resolution images of various commercially available
materials as highlighted below:
• Cerasorb: Very smooth surface, lobular, highly interconnected
material network, with pores or cavitations about 10 to 30 microns
in size
• maxresorb and BoneCeramic: Mostly at and smooth, slightly
rippled; highly fragmented; almost no interconnections, pores, or
cavitations
• NovaBone Dental Putty: Embedded in a putty, its surface appears
smooth and undulated, with microrough areas
• Perioglas (NovaBone): Microarchitecture highly similar to
Cerasorb, yet much smaller; highly interconnected, intricate
network of cavitations, about 1 to 5 microns in size; individual
particles are highly fragmented, with numerous larger pores 10 to
100 microns in size (not seen in Cerasorb)
• Osbone: Highly fragmented particles, with larger pores lost in
fragments; very rough surface; highly interconnected network of
cavitations at the 2-micron level
• Ostim: Embedded in a putty, the particles appear smooth, with no
pores; microrough at the <1-micron level
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Clinical Indications and Case Presentations of Bone
Regeneration
93
How each of these surface characteristics truly relates to clin-
ical outcomes and bone regeneration remains relatively under-
studied. Lambert et al20 reported on the surface topography of
xenograft hydroxyapatite compared to synthetic hydroxyapatite and
the effect on bone formation in animal sinus augmentations. At the
2-micron level, Bio-Oss appeared microrough compared to the other
xenograft (Endobon) and the synthetic material (Osbone). None had
large pores; all had micropores less than 1 micron in size, and
Bio-Oss appeared to have abundant pores. The newly formed bone from
Bio-Oss was nearly double that of the synthetic option (19.28% vs
11.93%).
A more informative study by Hinze et al40 compared allografts to a
synthetic nanohydroxyapatite (Ostim). Harvested human alveolar bone
samples were collected during routine dental surgeries. The
osteoblasts were cultured, added to the two bone grafting
materials, and compared for osteoblast activity. The authors
reported that osteoblasts did not proliferate well or spread on the
synthetic material (Ostim). Few vital cells were noted after 3
weeks of culture on the material. Proliferation
of osteoblasts on the allograft was far greater. Thus, this in
vitro study demonstrated a poor performance for the synthetic
nanohydroxyapatite.
Clinical Indications and Case Presentations of Bone
Regeneration
Figure 6-5 shows a case of ridge preservation prior to implant
placement. The mandibular right rst molar was extracted, and the
socket was grafted with maxresorb, a synthetic BCP (60%
hydroxyapatite, 40% β-TCP) particulate material, and sealed with a
collagen membrane (Jason, botiss). At 3 months, the site appears
well preserved (see Figs 6-5e and 6-5f). A tissue-level implant
(Straumann) was placed, osseointegrated, and restored (see Figs
6-5g to 6-5i).
FIG 6-4 (a) NovaBone Putty is an injectable biomaterial that forms
a relatively smooth surface but also features some topographic
differences, like- ly as a result of the putty-based composition.
(b) Cerasorb displays an extremely smooth surface. These surfaces
typically are not as conductive toward osteoblast differentiation
as roughened surfaces, presenting more micro- and nanotopographies.
(c) SEM image of Perioglas (NovaBone). Notice the roughened surface
morphology. (d) SEM image of Ostim paste. Notice the roughened
surface. (e) SEM image comparing two synthetic materials: maxresorb
and BoneCeramic. Notice the relatively smooth surfaces and lack of
porosity. (All images original magnication ×6,000.)
a b
d e
Cerasorb (Curasan) Perioglas (NovaBone)
Synthetic Bone Substitute Materials
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FIG 6-5 Socket grafting of a mandibular left rst molar site
followed by implant placement. (a) Minimally traumatic tooth
extraction due to an apical lesion. (b and c) A maxresorb synthetic
bone graft and a Jason membrane (botiss) are utilized within the
extraction socket. (d) Radiograph immediately postoperative. (e and
f) Clinical photograph and radiograph after 3 months of healing.
Notice the excellent maintenance of the site dimensions
postextraction. (g) Implant placement. (h) Radiograph showing the
implant and provisional crown. (i) Clinical photograph of the nal
crown. (Case performed by Dr Massimo Frosecchi.)
a b
Clinical Indications and Case Presentations of Bone
Regeneration
95
Figure 6-6 shows a case of transcrestal sinus elevation and
augmentation. Using osseodensication burs, a Versah lift was
carried out at the site of a missing maxillary right premolar that
had a vertical deciency. The unique nonextractive drilling sys- tem
propelled autogenous bone into the sinus, simultaneously
lifting the sinus membrane. The sinus was additionally augment- ed
by lling the osteotomy with 70% calcium phosphosilicate putty
(NovaBone), and the Versah burs were repeatedly applied into the
osteotomy, further propelling the graft material. A sig- nicant
vertical augmentation was achieved.
FIG 6-6 Versah lift at the site of a missing maxillary right second
premolar. A transcrestal sinus elevation was performed with
osseodensication burs, and the sinus was augmented with a synthetic
bone material (NovaBone) prior to implant placement. (a) Maxillary
right second premolar site with observed dimensional loss of bone
width. (b) Cone beam computed tomography (CBCT) of the implant
planning. (c) Osteotomy prepared with Versah burs. (d and e)
Injection of NovaBone (radiopaque). (f and g) Clinical images of
implant placement. (h) Final radiograph. Notice the radiopaque
NovaBone found within the sinus. (Case performed by Dr Jonathan Du
Toit.)
a b
Synthetic Bone Substitute Materials
96
06
Figure 6-7 shows a case of grafting the buccal gap during immediate
implant placement. A maxillary premolar was de- coronated and a
socket shield prepared. An immediate implant was placed, and the
buccal gap was grafted with NovaBone Putty. At the 1-year
follow-up, there appeared to be little or no collapse of the buccal
ridge (see Fig 6-7f).
Conclusion It is fair to state that the ideal synthetic bone graft
replacement has not yet been developed or conclusively proposed.
However, premanufactured synthetic scaffolds for the rehabilitation
of alve- olar bone defects continue to improve. There remains no
single graft material that is ideally suited for all clinical
situations in all patients. In the future, it is expected that
synthetic bone grafts will be the class of bone grafts with the
greatest improvements regarding their use in daily clinical
practice.
FIG 6-7 Socket-shield technique and immediate implant placement at
the site of a maxillary right rst premolar. The buccal gap was
augmented with a synthetic bone material (NovaBone Putty). (a and
b) The maxillary right rst premolar was partially extracted due to
decay; a portion of the tooth root was left in place to maintain
the buccal bone. (c) Injection of NovaBone synthetic bone putty.
(d) Implant placement. Notice the NovaBone on the buccal aspect of
the implant. (e and f) Radiograph and CBCT images 1 year after
surgery. (g) Clinical image demonstrating the excellent esthetic
result. (Case performed by Dr Howard Gluckman.)
a
c
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