Sinus floor augmentation withsimultaneous placement of dentalimplants in the presence of platelet-richplasma or recombinant human bonemorphogenetic protein-7
J. Camilo RoldánS�ren JepsenChristian SchmidtHelge KnüppelDavid C. RuegerYahya AçilHendrik Terheyden
Authors’ affiliations:J. Camilo Roldán, Christian Schmidt, HelgeKnüppel, Yahya Açil, Hendrik Terheyden,Department of Oral and Maxillofacial Surgery,University of Schleswig-Holstein, Campus Kiel,GermanyS�ren Jepsen, Department of Periodontology,Operative and Preventive Dentistry, University ofBonn, GermanyDavid C. Rueger, Stryker Biotech, Hopkinton, MA,USA
Correspondence to:Juan Camilo Roldán MD, DMDDepartment of Oral and Maxillofacial SurgeryUniversity of Schleswig-HolsteinCampus KielArnold-Heller-Str. 1624105 KielGermanyTel.: þ49 431 597 2820Fax: þ49 431 597 2950e-mail: [email protected]
Key words: anorganic bovine bone, bone morphogenetic proteins, dental implants,
platelet-rich plasma, sinus floor augmentation
Abstract: The aim of the present study was to evaluate the possible benefit of platelet-rich
plasma (PRP) in sinus grafting as compared with recombinant human bone morphogenetic
protein-7 (rhBMP-7). For this purpose, we performed a bilateral sinus augmentation with
anorganic bovine bone and simultaneous insertion of a titanium screw implant in five
miniature pigs. Six hundred microliters of PRP and 15%-vol. autologous bone, which was
collected with a trap during preparation of the implant recipient site, were added to the
right sinus and 420ml rhBMP-7 to the left sinus. A polychrome sequential labeling was
performed. The animals were sacrificed 6 weeks after surgery. Undecalcified ground
sections were evaluated by microradiography, digitized histomorphometry and under
fluorescent light. The mean bone–implant contact using rhBMP-7 was 45.8% and 5.7%
under PRP (P¼0.002). The mean height of newly mineralized bone in the augmented area
using rhBMP-7 amounted to 8.3mm as opposed to 3.6mm under PRP (P¼0.013). Using PRP,
the mean area of the newly formed bone was enhanced (51.3%) as compared with rhBMP-7
(33.1%); however, this difference was not statistically significant (P¼0.081). In conclusion,
under the selected experimental conditions the use of rhBMP-7 led to superior outcomes
with regard to the osseointegration of dental implants and the height of new bone as
compared with the use of PRP.
The advanced atrophy of the maxilla and
the subsequent pneumatization of themax-
illary sinus imply a challenge for the im-
plant rehabilitation. Boyne & James (1980)
introduced the sinus augmentation with
autogenous bone graft for implant surgery.
This technique became a standard method
with good results (Raghoebar et al. 1997;
Lorenzetti et al. 1998). Nevertheless, the
limited amount of disposable bone of the
jaws for grafting purposes and the need for
iliac bone to fulfill the expected bone
volume for reconstruction make it neces-
sary to find a substitute of autologous bone
to reduce morbidity and patient discomfort
associated with bone grafting (Smiler &
Holmes 1987). The introduction of hydro-
xylapatite (Smiler & Holmes 1987) and of
the anorganic bovine bone (Wentzel et al.
1995; Hürzeler et al. 1996; Hass et al.
1998; Valentini et al. 1998) to augment
the sinus floor showed a realistic alterna-
tive to the autologous bone. The most
critical aspect of the latter approach is the
longer time needed for bone healing (Moy
et al. 1993; Lorenzetti et al. 1998; Yildirim
et al. 2001). Lynch et al. (1991) reported
about the increase of the bone–implant
contact (BIC) after the application of re-
combinant human platelet-derived growth
factor (rhPDGF) and recombinant human
Insulin growth factor-I (rhIGF-I) 7 days
after operation. In 1998, Marx et al.
(1998) introduced the local application ofCopyright r Blackwell Munksgaard 2004
Date:Accepted 8 January 2004
To cite this article:Roldán JC, Jepsen S, Schmidt C, Knüppel H, RuegerDC, Açil Y, Terheyden H. Sinus floor augmentationwith simultaneous placement of dental implants in thepresence of platelet-rich plasma or recombinant humanbone morphogenetic protein-7.Clin. Oral Impl. Res. 15, 2004; 716–723doi: 10.1111/j.1600-0501.2004.01070.x
716
autologous platelet-rich plasma (PRP) to
accelerate the maturation of grafted bone
in maxillofacial surgery. Growth factors
released by platelets like PDGF, IGF-I and
transforming growth factor-b (TGF-b) areinvolved in reparative processes including
osteogenesis (Ross et al. 1986; Noda &
Camilliere 1989; Pfeilschifter et al. 1990;
Nash et al. 1994). Lynch (1999) proposed
the use of PRP in combination with a bone
substitute for the treatment of small bone
defects in periodontal and implant surgery.
Since 2000, clinical studies have been
published to evaluate the benefit of PRP
in sinus surgery (Kassolis et al. 2000;
Rosenberg & Torosian 2000; Lozada et al.
2001; Philippart et al. 2003; Rodriguez
et al. 2003;Wiltfang et al. 2003). At present,
there are no data available from experimen-
tal in vivo studies on the histomorpho-
metric evaluation of new bone formation
and osseointegration of dental implants in
the presence of PRP.
Bonemorphogenetic proteins (BMPs), on
the other hand, are able to induce me-
senchymal stem cells to differentiate into
osteoblasts and to produce new bone tissue
(Urist 1965). BMPs have been shown to
shorten the healing time of sinus augmen-
tation in combination with a bone substi-
tute and to increase the osseointegration of
dental implants (Boyne et al. 1997; Ha-
nisch et al. 1997; Margolin et al. 1998;
Terheyden et al. 1999). Therefore, the aim
of the present study was to evaluate the
pattern of bone formation using PRP com-
pared with the well-documented effects of
a recombinant BMP in the miniature pig
model for sinus augmentation.
Material and methods
The study was approved by the Ministry of
Nature, Environment and Forestry of Schles-
wig-Holstein in accordance with the ethics
committee of this institution (V 252-72241.
121-14). Five miniature pigs (Ellengard Göt-
tingen Minipigs ApS, Dalmose, Denmark),
18 months of age, which weighed 40kg,
were operated. They were fed with 2 �250 g standard soft diet (Altromin 9023s
Atronium International GmbH, Lange,
Germany) and water ad libitum.
Anesthesia was induced with 30mg Ke-
tamine (Ketavets, Upjohn GmbH, Hep-
penheim, Germany) and 1mg Xylazine
(Rompuns 2%, Bayer AG, Leverkusen,
Germany). An intratracheal intubation
was performed with a Miller size 4 laryn-
goscope and a standard straight 5.5mm ID
tube with cuff (Portex, Kent, UK). An-
esthesia was maintained with gas (66%
N2O and 32% O2 (Forenes, Abbot
GmbH, Wiesbaden, Germany)). One gram
Clemizol–Penicillin (Clemizol–Penicillins
i.m. forte, Grünenthal GmbH, Aachen,
Germany) was given preoperatively as a pro-
phylactic antibiotic. Postoperative pain relief
was achieved before extubation by inject-
ing 500mg metamizol i.m. (Novalgins,
Hoechst AG, Bad Soden, Germany), con-
tinuing with 2 � 50mg/day p.o. Tramadol(Tramals, Grünenthal GmbH, Aachen,
Germany).
Preparation of PRP
Seventeen milliliters of blood were col-
lected in two vacuum tubes of 8.5ml
each (S-Monovettes, CPDA-1, Starstedt
AG, Nümbrecht, Germany) from the
vena jugularis interna in general anesthesia
just before surgery. The method proposed
by Marx et al. (1998) on how to prepare
PRP was modified according to the small
sample of blood after a statistically vali-
dated method (Roldán et al. 2004). The
volumes handled were proportional to the
volumes described by Marx et al. (1998).
The PRP was produced as follows: the
whole blood was centrifuged for 7min at
1700 rpm without brake. The plasma was
decanted down to the erythrocyte sediment
and then centrifuged again for 10min at
3000 rpm with brake. Finally, the plasma
was decanted and the sediment was resus-
pendedwith 2.3ml plasma, resulting in the
same concentration of PRP as the one
described by Marx et al. (1998). The plate-
lets in whole blood and PRP were counted
manually in the Neubauer chamber in
which the thrombocytes were stained
with a specific reagent (TTV 55-Thrombo-
zyten-Einzeltests KABE Labortechnik
GmbH, Nümbrecht-Eisenroth, Germany).
The PRP was kept in a sample shaker for
a mean of 30min at room temperature.
The PRP for clinical usewas activatedwith
human lyophilized thrombin (Tissucols,
Baxter, Heidelberg, Germany). The throm-
bin was combined with CaCl2 10% in
a proportion of 250 IU thrombin/500 mlCaCl2 10%. Three hundred and eighty
microliters of activated thrombin were
mixed with 600ml PRP. Nine hundred
and eighty microliters of this solution
were used in combination with the anor-
ganic bovine bone and 15% vol. autologous
bone for implantation in the right sinus.
Experimental procedure
After harvesting of blood to prepare PRP, the
cheek was shaved and cleaned with povi-
done–iodine solution and drapedwith sterile
towels. The augmentation of the sinus was
achieved by an infraorbital access and sub-
periosteal preparation of the facial maxillary
bone, the crista zygomaticoalveolaris and
the malar prominence, as previously de-
scribed (Terheyden et al. 1999). The access
to the sinus was achieved by thinning the
facial wall with a surgical bur. The Schnei-
derian membrane was carefully elevated
within the sinus, particularly below the
malar prominence, where the dental im-
plant in a latero-cranial direction was in-
serted. The malar bone, as an implant site,
was reduced to a height of 5mm for stan-
dardization according to the clinical situa-
tion (Tidwell et al. 1991; Triplett & Schow
1996). Solid screw titanium implants (SLA-
ITIs, Strauman AG, Waldenburg, Switzer-
land), 16mm long with a diameter of
4.1mm, were used. The right sinus was
augmentedwith 3ml anorganic bovine bone
(Bio-Osss Granulat 0.25–1mm, E. Geis-
tlich Söhne AG, Wolhusen, Switzerland),
15%-vol. autologous bone collected during
preparation of the implant recipient site
with a bone trap in a suction device (Kno-
chenfilter T2, SchlumbohmOHGs, Broch-
stedt, Germany) and 600ml PRP. The leftsinus was augmented with 3ml Bio-Osss
and 420ml recombinant BMP-7 (rhBMP-7)(Stryker Biotech, Hopkinton MA, USA) in
600ml acetate buffer. No autologous bonewas grafted into the left sinus.
Polychrome sequential labeling
A polychrome sequential labeling of miner-
alizing tissues according to Rahn (1976)
was performed as previously described (Ter-
heyden et al. 1999). Intraperitoneal injec-
tion of fluorochromes under i.m. anesthesia
with 250mg Zolazepam/250mg Tiletamin
(Tilests 500 Parke-Davis, Freiburg, Ger-
many) started 2 weeks after the surgical
procedure and continued for 3 weeks with
one labeling per week as follows: xylenolor-
ange (6% in 2%NaHCO3 solution, 1.5ml/
kg body weight), calcein green (1% in 2%
NaHCO3 solution, 5ml/kg body weight),
Roldán et al . Sinus floor augmentation in presence of PRP or rhBMP-7
717 | Clin. Oral Impl. Res. 15, 2004 / 716–723
alizarin complexon (3% in 2% NaHCO3solution, 0.8ml/kg body weight) and dox-
ycyclines (1mg/kg body weight, Doxy-
cyclin-Rathiopharm SFs, Rathiopharm
GmbH & Co., Ulm, Germany).
Sacrifice
The animals were sacrificed 6 weeks post-
surgery in general anesthesia (see above)
by an intravital and intracardial perfusion.
For this purpose, the ascending aorta, after
a median thoracotomy, was canulated
through an incision of the left ventricle.
Prior to this, heparin 40 IU/kg (Liquemins
N 2500, Hoffmann-La Roche AG, Gren-
zach-Wyhlen, Germany) had been admi-
nistered. The right atrium was opened by
an incision to release the venous blood
flow. Two liters of Ringer solution was
perfused at a temperature of 36–371C under120mmHg pressure in order to wash out
the blood. Subsequently, the animals were
perfused for tissue fixation with a 500ml
solution composed of 25% glutaraldehyde
(2.5%), formaldehyde (1.5%) and Sören-
sen’s phosphate buffer (100mMKH2PO4,
100mMNa2HPO4 � 2H2O, pH 7.4). Acoronal computed tomography (CT) Scan
(Siemens Somatom Plus, Siemens AG,Mu-
nich, Germany; 120kV, 33mA) was con-
ducted. The explanted sinus was immersed
in 10% formalin, Sörensen’s phosphate buf-
fer and 70% isopropyl alcohol for 10 days.
Histology
Undecalcified specimens were prepared ac-
cording to themethod described by Donath
& Breuner (1982). The process consists in
a gradual dehydration of the specimen
in ethyl alcohol and a final embedding in
acrylic resin (Fluka Chemie AG, Buchs,
Switzerland). The block was cut in the
coronal plane after placing an implant abut-
ment that indicated the axis of the implant
body. The retrieved specimens, in 0.5mm
slices, were fixed on an acrylic carrier and
ground and polished down to approxi-
mately 90 ml. A microradiograph (Type1A, Microchrome Technology Inc., San
José, CA, USA) was taken at 3mA and
25kV using a microradiography device
(Faxitron X-ray systems, Hewlett Packard
GmbH, Böblingen, Germany). The histo-
morphometry of the total core was evalu-
ated after digitalization of the microscope
image. The software detected a variety of
different gray tones, which allowed to
distinguish the newly mineralized bone
(Q500MCs, Leach Cambridge Ltd., Cam-
bridge, UK). Fluorescence microscopy was
performed under UV light. The parameters
to be evaluated according to Parfitt et al.
(1987) were the following:
� Bone–implant contact: Mineralizedbone in direct contact to the implant
(%), where 100% is the total length of
the implant in the augmented sinus.
� The area of newly mineralized bone inthe lower third of the augmented area
(mm2)
� Height of newly mineralized bone inthe augmented area (mm).
Statistical analysis
The data for the three outcome variables
were analyzed with a paired t-test. The
correlation in the thrombocyte count in
whole blood and PRP was analyzed with
a Spearman test. The significance level
was set at Po0.05.
Results
Validity of the preparation of PRP
The mean number of thrombocytes in
whole blood was 450.20 � 103 cells/ml.The PRP mean platelet count was
1.592 � 103 cells/ml. Thus, the concentra-tion of the thrombocytes in PRP was in-
creased by a factor of 3.5. The thrombocyte
count in whole blood in the different ani-
mals was variable, ranging from 173 � 103
to 620 � 103 cells/ml. No statistically sig-nificant correlation between the thrombo-
cyte concentration in the whole blood and
in PRP could be observed (P¼ 0.1).
CT scan
Six weeks after the operation no signs of
infection in themaxillary sinus, of any loss
of implant integration or any apparent
differences in the imaging of the augmenta-
tion with PRP or with rhBMP-7 could be
observed (Fig. 1).
Fig. 1. Coronal CT Scan (Siemens Somatom Plus, 120 kV, 33mA) of the midface of a miniature pig 6 weeks
after sinus-lift with anorganic bovine bone in association with platelet-rich plasma and 15%-vol. autologous
bone on the right side and with bone morphogenetic protein-7 on the left side. A titanium screw implant was
primarily inserted into the zygomatic bone in a latero-cranial direction on both sides. No sinus pathology or
apparent difference in the radio-opacity of the augmentation is seen on both sides. The right maxillary sinus is
outlined in red, the left sinus in blue; the infraorbital nerve (n) is demarked in yellow on both sides.
Roldán et al . Sinus floor augmentation in presence of PRP or rhBMP-7
718 | Clin. Oral Impl. Res. 15, 2004 / 716–723
Microradiography
In the presence of PRP, the apposition of
new bone could be seen in the proximity of
host bone but not on top of the augmenta-
tion (Fig. 2a). The formation of new bone
in the presence of rhBMP-7 appeared to be
homogeneous in the whole augmented area
and limited to the area augmented with
bone substitute (Fig. 2b).
Toluidine blue histology
No inflammatory reaction was seen on
any section and individual animal. An
enhancement of bone apposition in the
proximity of host bone in the presence
of PRP was clearly detected; however,
the osseointegration of the dental im-
plants was not improved in this site. The
tip of the dental implant was surround-
ed by connective tissue in all cases treated
with PRP (Fig. 3a). In contrast, bone
marrow was observed in the whole aug-
mented sinus in the presence of rhBMP-7
and the implants were surrounded
by newly formed bone in all the cases
(Fig. 3b).
Fluorescence microscopy
The apposition of new bone was observed
in the presence of rhBMP-7 after the second
week postsurgery; in the presence of PRP it
occurred 1 week later, as indicated by the
second labeling (Fig. 4). Bone apposition
was enhanced on the sinus floor showing
wider labeled bands in both experimental
groups. No bone apposition was seen on
the tip of the implants in sites treated with
PRP. In the presence of rhBMP-7, however,
a homogeneous bone apposition on the top
of the implants and around the Bio-Osss
Fig. 2. Solid screw titanium implant (ITIs) in the maxillary sinus augmented with anorganic bovine bone (Bio-Osss) 6 weeks postoperatively. (a) Situation following
application of platelet-rich plasma and 15%-vol. autologous bone graft: the apposition of new bone takes place in a gradual fashion from the host bone to the top of the
augmentation. The sinus wall is outlined in red, see Fig. 1. (b) Situation following application of recombinant human bonemorphogenetic protein-7: Homogeneous new
bone formation in thewhole augmented sinus. The formation of new bonewas determined by the shape of the implantedmaterial and did not exceed it. The sinus wall is
outlined in blue, see Fig. 1. (Microradiography of undecalcified ground sections.)
Fig. 3. Solid screw titanium implant (ITIs) in the maxillary sinus augmented with anorganic bovine bone (Bio-Osss) 6 weeks postoperatively. (a) Situation following
application of platelet-rich plasma and 15%-vol. autologous bone graft: The apposition of new bone takes place in a gradual fashion from the host bone to the top of the
augmentation. Enhanced bone apposition on the sinus floor is evident; however, osseointegration is not improved. Bio-Osss particles on top of the dental implant are
surrounded by connective tissue. The sinus wall is outlined in red; the arrow indicates apposition of new bone on the implant. (b) Situation following application of
recombinant human bone morphogenetic protein-7: Homogeneous new bone formation with bone marrow in the whole augmented sinus. Osseointegration of the
titanium implant is seen on its entire length. The sinus wall is outlined in blue; the arrow indicates apposition of new bone on the tip of the implant (toluidine blue
staining).
Roldán et al . Sinus floor augmentation in presence of PRP or rhBMP-7
719 | Clin. Oral Impl. Res. 15, 2004 / 716–723
particles could be seen after the second
postoperative week.
Histomorphometry
In all but one specimen, apposition of bone
on dental implants was seen in the PRP
group. The mean BIC in the presence of
PRP amounted to 5.76%, whereas in the
rhBMP-7 group BIC was observed over the
entire implant length with a mean value of
45.8%. This difference was statistically
significant (P¼ 0.002). The mean heightof the newly formed bone in the augmented
area in rhBMP-7 treated sites was 8.3mm,
which is in contrast to a mean height
of 3.6mm in the PRP group (P¼ 0.013).The area of the newly mineralized bone
on the sinus floor was larger in the pre-
sence of PRP (51.32%) than in the presence
of rhBMP-7 (33.12%); however, this
difference was not significant (P¼ 0.081)(Table 1).
Discussion
Since the first description of local applica-
tion of PRP produced by a gradient density
cell separator (Electro Medics 500s, Med-
tronics, Minneapolis, MN, USA) to accel-
erate the maturation of bone transplants in
maxillofacial surgery (Marx et al. 1998),
many methods have been proposed to pro-
duce PRP by using a conventional centri-
fuge to facilitate its application for implant
surgery in clinical practice (Landesberg et al.
2000; Weibrich et al. 2001). In the present
study, we chose a validated method to
produce PRP (Roldán et al. in press), which
resembles the method of Marx et al. (1998),
but is adapted to the handling of smaller
volumes of blood according to the animal
model. The mean value of the concentra-
tion factor of thrombocytes in PRP was 3.5,
which is comparable with the factor 3.4
reported by Marx et al. (1998). Neverthe-
less, a statistical correlation between the
thrombocyte count in whole blood and in
PRP was not seen, possibly due to the small
sample size (n¼ 5). Moreover, a high varia-bility in the thrombocyte count in the
whole blood of the experimental animals
was observed (maximum: 620 � 103 cells/ml and minimum: 173 � 103 cells/ml). Thisis a critical aspect because the application of
thrombocytes and the contained growth
factors is not standardized. Experiments on
local application of recombinant growth
factors showed a dose-dependent effect
(Noda & Camilliere 1989; Pfeilschifter et al.
1990; Nash et al. 1994; Ripamonti et al.
1997). The effect of the local application of
growth factors also depends on the applica-
tion site (Fujimoto et al. 1999), age and
animal model (Ripamonti et al. 1997).
The effect of TGF-b has been shown to bebiphasic depending on the dose; at a high
concentration an inhibition of osteoblast
proliferation has been seen (Centrella et al.
1994; Fujimoto et al. 1999). Further inves-
tigations have to be undertaken to clarify
the interaction of growth factors at higher
levels in a PRP model.
In the literature, no data are reported on
the influence of PRP on BIC. BMPs, pre-
viously shown to be an effective approach
to enhance osseointegration of dental im-
plants applied in a mineral or collagen
scaffold (Bessho et al. 1999; Terheyden
et al. 1999), were chosen as a control group
Table 1. Parameters (mean values and standard deviation) of bone formation 6 weeks aftersinus augmentation with 3 ml anorganic bovine bone (Bio-Osss) and primary insertion of atitanium implant (ITIs) combined with 600ll of PRP (in 15%-vol. autologous bone) or420ll of rhBMP-7
Bio-Osss-15%-vol.autologous bone/PRP
Bio-Osss/rhBMP-7
P-valuesBMP vs. PRP
Bone–implant contact (%) 5.76 � 11.8 45.80 � 18.58 0.002n
Area of newly mineralized boneon the sinus floor (%)
51.32 � 20.83 33.12 � 13.65 0.081
Height of the newly mineralizedbone in the augmented area (mm)
3.58 � 3.3 8.35 � 2.74 0.013n
nStatistically significant difference (t-test).
rhBMP, recombinant human bone morphogenetic protein; PRP, platelet-rich plasma.
Fig. 4. Basal aspect of the augmented sinus with anorganic bovine bone (Bio-Osss) and primary inserted ITIs-Implant 6 weeks postoperatively. (a) Situation following
application of platelet-rich plasma and 15%-vol. autologous bone graft: Beginning of the bone apposition after the third postoperatively week (calcein green). The arrow
indicates newly formed non-fluorochrom-labeled bone, indicating bone formation after the fifth postoperative week; implant (n). (b) Situation following application of
recombinant human bone morphogenetic protein-7: Homogeneous bone apposition after the first labeling, injected in the second postoperative week; implant (n).
(Fluorescence microscopy in composite slides technique).
Roldán et al . Sinus floor augmentation in presence of PRP or rhBMP-7
720 | Clin. Oral Impl. Res. 15, 2004 / 716–723
in order to evaluate the efficiency of PRP
to improve BIC. In the present study, the
achieved BIC 6 weeks following PRP ap-
plication was 5.76% compared with
45.8% in the presence of rhBMP-7. The
achieved BIC in the PRP model has to be
considered inadequate in a clinical setting
and does not show a benefit compared with
reported studies on sinus augmentation
with Bio-Osss alone, as shown by Hass
et al. (1998), who informed about a BIC of
27.4% 12 weeks after sinus augmentation
in sheep. Others reported about a BIC of
63% in beagles (Schlegel et al. 2003) or
38% in miniature pigs (Terheyden et al.
1999) after an observation period of 6
months. Lynch et al. (1991) demonstrated
a statistically significant enhancement of
the BIC 7 days after the application of
rhPDGF und rhIGF-I. This positive effect
of growth factors on osseointegration sug-
gests that in the present study the required
concentration of growth factors contained
in PRP may not have been achieved.
The mean BIC in sites conditioned with
rhBMP-7 was 45.8%. Terheyden et al.
(1999), using the same experimental
model, reported a mean BIC of 80% after
6 months for the rhBMP-7 group. The
present study shows the strong effect of
BMP at the very beginning after applica-
tion. In vitro studies by the same authors
on Bio-Osss loaded with rhBMP-7 showed
a release of 98% of BMP into simulated
body fluid within 24h (Jepsen et al. 1999).
The evaluation of the effectiveness of BMP,
compared with PRP after 6 weeks, is there-
fore appropriate. An evaluation of the effect
of BMP or PRP after 6 or 9 months is not
appropriate, because a bone integration of
anorganic bone in the absence of bone-
stimulating factors is to be expected after
that time (Hürzeler et al. 1996; Hass et al.
1998; Valentini et al. 1998).
The area of newly mineralized bone on
the sinus floor is expected to be larger in
the vicinity of the residual host bone (Qui-
ñones et al. 1997). In the present study, the
area of newly mineralized bone on the floor
of the sinus was higher in the presence of
PRP (51.32%) than under the influence of
rhBMP-7 (33.12%), although this differ-
ence was not statistically significant. The
observed increase in trabecular bone area
on bone grafts treated with PRP by Marx
et al. (1998) declined from the second to
the sixth month after surgery. Schmitz &
Hollinger (2001) discussed this work, and
extrapolated the curve of the area of the
trabecular bone in the bone graft to 1 year
and concluded that in the long term there
may be no observable advantage in bone
density of treated bone grafts with PRP.
Fürst et al. (2003) performed sinus eleva-
tion procedures in mini-pig using hydroxy-
lapatite for augmentation. PRP was added
to the test side; however, no dental implant
was inserted. An enhanced bone density
was seen on the base of the sinus in the
presence of PRP 3 weeks after surgery; at 6
weeks the bone density declined and at 12
weeks there was no difference to the con-
trol side (Fürst et al. 2003). The observed
enhancement of the trabecular bone area at
the beginning of the observational period
could be of no clinical interest in the long
term, as it has to be realized that the
trabecular bone area will undergo contin-
uous remodeling in response to the me-
chanic and the endocrine demands.
In the present study, the mean height of
newly mineralized bone in the augmented
areawas 8.3mm in the presence of rhBMP-
7, which corresponded to the total height of
the implanted anorganic bovine bone. In
the presence of PRP, the achieved value
was 3.6mm. It is expected that the aug-
mentation of the sinus with Bio-Osss in
the absence of bone-stimulating factors has
to be integrated into new bone, if it takes
6–9 months (Hürzeler et al. 1996; Hass
et al. 1998; Valentini et al. 1998). The very
slow resorption rate of Bio-Osss, a prop-
erty of this material that is often criticized
(Skoglund et al. 1997), could be of advan-
tage in sinus surgery (Schlegel et al. 2003),
because it permits a full bone integration of
implanted anorganic bovine bone before
the resorption of the scaffold starts, as
demonstrated by Hürzeler et al. (1996)
and Hass et al. (1998).
The rationale of adding autologous bone
to PRP was to supply osteoblasts to support
the proposed mitogenic effect of PRP (Wei-
brich et al. 2002). As shown in the extra-
skeletal model in the rat PRP is not os-
teoinductive and could not enhance bone
formation on Bio-Osss in skeletal sites
(Roldán et al. 2004). Because of the known
osteoinductive effects of BMPs, no autolo-
gous bone was grafted into the correspon-
dent sinus.
Autologous bone (15% vol.) collected
during the preparation of the implant site
was mixed with Bio-Osss to enhance bone
formation in the presence of PRP as it is
recommended when Bio-Osss is applied in
the clinical setting (Yildirim et al. 2001). In
spite of the addition of autologous bone to
Bio-Osss in the PRP model, vital bone
could only be seen in the proximity to the
sinuswalls. In the future, it has to be tested
if the addition of more autologous bone can
improve the osteogenesis in a PRP model.
However, if more bone than 15% vol. has
to be applied, it will be necessary to harvest
the additional bone-graft from a second
donor site. The augmentation of the sinus
with Bio-Osss in the presence of rhBMP-7
was carried out without the addition of
autologous bone. Nevertheless, homoge-
neous bone formation was seen in the
whole implanted area.
To our knowledge, this is the first report
to compare the effect of rhBMP-7 and PRP
in implant surgery. PRP could not improve
the osseointegration of dental implants in
regenerated sinus bone after an observation
time of 6 weeks. Our data support the
concept that recombinant BMPs in combi-
nation with an appropriate matrix carrier
may become clinically effective to improve
and accelerate osseointegration of dental
implants.
Acknowledgements: The authors
thank Mrs. M. Hermann and G. Otto, of
the Department of Experimental
Maxillofacial Surgery of the University
of Kiel, for their excellent technical
assistance.
Résumé
Le but de l’étude présente a été d’évaluer le bénéfice
possible du plasma riche en plaquettes (PRP) dans le
greffage sinusal comparé à la protéine-7 morpho-
génétique osseuse humaine recombinante (rhBMP-
7). Un épaississement du sinus bilatéral a été effec-
tué avec de l’os bovin anorganique et l’insertion
simultanée d’un implant vis en titane chez cinq
mini-porcs. Six cents ml de PRP et 15% /vol d’osautogène, qui avait été prélevé dans une trappe
durant la préparation du site implantaire receveur,
ont été placés dans le sinus droit et 420 ml de rhBMP-7 dans le sinus gauche. Un marquage séquentiel
polychrome a ensuite été effectué. Les animaux ont
été euthanasiés six semaines après la chirurgie. Des
coupes épaisses non-décalcifiées ont été évaluées par
microradiographies, histomorphométrie digitale et
sous lumière à fluorescence. Le contact os-implant
moyen en utilisant rhBMP-7 était de 45,8% et 5,7%
sous PRP (p¼ 0,002). La hauteur moyenne de l’os
Roldán et al . Sinus floor augmentation in presence of PRP or rhBMP-7
721 | Clin. Oral Impl. Res. 15, 2004 / 716–723
minéralisé nouveau dans la partie épaissie rhBMP-7
montait à 8,3 mm contre 3,6 mm pour le PRP
(0,013). En utilisant PRP, l’aire moyenne de l’os
néoformé était augmentée (51,3%) comparée à
rhBMP-7 (33,1%), cette différence n’étant cepen-
dant pas significative (p¼0,081). En conclusion,sous des conditions expérimentales sélectionnées,
l’utilisation de rhBMP-7 apporte des avantages
supérieurs en ce qui concerne l’ostéoı̈ntégration
des implants dentaires et la hauteur de l’os néoformé
comparé à l’utilisation du PRP.
Zusammenfassung
Sinusbodenelevation mit gleichzeitiger Platzierung
von dentalen Implantaten mit plättchenreichem
Plasma oder rekombiniertem menschlichem kno-
chenmorphogenetischem Protein-7
Das Ziel der vorliegenden Studie war, dem mögli-
chen positiven Effekt von plättchenreichem Plasma
(PRP) im Vergleich zu rekombiniertem menschli-
chem knochenmorphogenetischem Protein-7
(rhBMP-7) bei der Sinusbodenelevation zu untersu-
chen. Zu diesem Zweck wurde bei fünf Minipigs
eine bilaterale Sinusbodenelevation mit anorga-
nischem bovinem Knochen und gleichzeitig die
Implantation eines Schraubenimplantats durchge-
führt. Sechshundert ml PRP und 15%-vol. autologerKnochen, welcher bei der Präparation des Implan-
tatbettes gewonnen wurde, wurden im rechten Si-
nus dazu gefügt und 420 ml rhBMP-7 wurden in denlinken Sinus eingebracht. Es wurde eine polychrome
Sequenzmarkierung durchgeführt. Sechs Wochen
nach dem Eingriff opferte man die Tiere. Die nicht
entkalkten Schliffpräparate wurden mittels Mikror-
adiographie, digitalisierter Histomorphometrie und
unter fluoreszierendem Licht untersucht. Der
mittlere Knochen-Implantat-Kontakt betrug mit
rhBMP-7 45.8% und mit PRP 5.7% (P¼0.002).Die mittlere Höhe an neu gebildetem mineralisier-
tem Knochen im Augmentat erreichte 8.3mm bei
rhBMP-7 und 3.6mm bei PRP (P¼ 0.013). Mit PRPwar die Fläche an neu gebildetem mineralisiertem
Knochen grösser (51.3%) als mit rhBMP-7 (33.1%),
jedoch war dieser Unterschied nicht statistisch sig-
nifikant (P¼ 0.081). Es wird die Schlussfolgerunggezogen, dass unter den ausgewählten experimentel-
len Bedingungen die Verwendung von rhBMP-7 im
Vergleich zu plättchenreichem Plasma zu besseren
Resultaten bezüglich Osseointegration von Dental-
implantat und der Höhe von neuem Knochen führt.
Resumen
La intención del presente estudio fue evaluar el
posible beneficio del plasma rico en plaquetas
(PRP) en el injerto del seno en comparación con la
proteı́na-7 morfogenética ósea humana recombi-
nante (rhBMP-7). Para este propósito, llevamos a
cabo aumento del seno bilateralmente con hueso
bovino anorgánico e inserción simultanea de un
implante roscado en cinco cerdos miniatura. Se
añadieron 600 ml de PRP y 15%-vol. de huesoantólogo, que fue recolectado usando una trampa
durante la preparación del lugar receptor del im-
plante, al seno derecho y 420 ml de rhBMP-7 alseno izquierdo. Se llevó a cabo un marcado poli-
cromo secuencial. Los animales se sacrificaron seis
semanas tras la cirugı́a. Se evaluaron las secciones
descalcificadas microrradiograficamente, histomor-
fometricamente y bajo luz fluorescente. El contacto
hueso a implante medio usando rhBMP-7 fue 45.8%
y 5.7% bajo PRP (P¼ 0.002). La altura media delhueso neomineralizado en el área aumentada usando
rhBMP-7 llegó a 8.3mm frente a 3.6mm bajo PRP
(P¼ 0.013). Usando el PRP, el área media de huesoneoformado aumentó (51.3%) en comparación con
rhBMP-7 (33.1%), sin embargo esta diferencia no fue
estadı́sticamente significativa (P¼ 0.081). En con-clusión, bajo las condiciones experimentales selec-
cionadas, el uso se rhBMP-7 condujo a unos
resultados superiores respecto a la osteointegración
de implantes dentales y a la altura del nuevo hueso
en comparación con el uso de plasma rico en
plaquetas.
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