Post on 06-Mar-2023
Platelet-rich plasma activity onmaxillary sinus floor augmentation byautologous bone
Ugo ConsoloDavide ZaffeCarlo BertoldiGiovanni Ceccherelli
Authors’ affiliations:Ugo Consolo, Carlo Bertoldi, Department ofNeurosciences, Head-Neck, Rehabilitation, Sectionof Dentistry and Maxillofacial Surgery, Universityof Modena and Reggio Emilia, Modena, ItalyDavide Zaffe, Department of Anatomy andHistology, Section of Human Anatomy, Universityof Modena and Reggio Emilia, Modena, ItalyGiovanni Ceccherelli, Immuno-transfusion Center,General Hospital of Modena, Modena, Italy
Correspondence to:Prof. Davide ZaffeDipartimento di Anatomia e IstologiaSezione di Anatomia Umana NormaleVia del Pozzo 71, Modena 41100, ItalyTel.: þ39 0594224800Fax: þ39 0594224861e-mail: zaffe@unimore.it
Key words: autologous bone, bone regeneration, maxillary sinus augmentation, platelet-
rich plasma
Abstract
Objectives: This work aims to evaluate the regenerative potential of platelet-rich plasma
(PRP) on an implant site of peculiar clinical impact, such as sinus augmentation.
Material and methods: Sixteen consenting patients (11 females and five males), with
symmetrical maxillary sinus atrophy, underwent bilateral sinus floor augmentation, using
autologous (iliac crest) bone on one side and PRP plus autologous bone contralaterally.
Implants were inserted 4, 5, 6 and 7 months after surgery in the patients randomly split into
four groups. Orthopantomographies, computed tomography with transverse image digital
reconstructions and densitometries were used to monitor the treatment progress. A core
biopsy was performed at the site of implant.
Results: Clinical performance across both sites showed no statistical significance (P¼0.414).
Densitometric values were higher at PRP sites (mean Hounsfield units �þ57%), even if
densitometry converged in the two sites 8 months after surgery. Histology documents
enhanced bone activities in sites treated with PRP, 4 months after surgery. Reduced bone
activity was observed in both sites 5, 6 and 7 months after surgery. Bone amount, higher in
sites treated with PRP (mean trabecular bone volume � þ37%), decreased in both sites
over time.
Conclusions: Our results seem to indicate a certain regenerative potential of PRP when
used with autologous bone. The effect of this enhancement of bone regeneration
appeared to be restricted to shorter treatment times. A progressive extinguishment of the
PRP effect is recorded after an interval longer than 6–7 months.
The rate of achievable bone regeneration
may be a decisive factor influencing the
success of implant dentistry. Bone resorp-
tion with aging increases the cavity and
reduces the thickness of the maxillary
sinus floor, thus influencing implant in-
sertion and stability in the posterior max-
illa (Hutton et al. 1995; Jensen 1999;
Misch 1999). Several authors (Adell et al.
1981; Cox & Zarb 1987; van Steenberghe
et al. 1987; Friberg et al. 1991; Jaffin &
Berman 1991; Furst et al. 2003) have
reported that a higher rate of implant fail-
ures occurs in the edentulous upper jaw
than other oral regions. Sinus floor aug-
mentation, as first described by Boyne &
James in 1980 and Tatum in 1986, consti-
tutes one of the most important procedures
for improving bone amount in pre-prosthe-
tic surgery. Although various grafting
materials are available, autogenous bone
is considered the best material owing to
its osteoinductive potential, histocompat-
ibility and satisfactory clinical outcomes
(Jensen et al. 1998). Bone-healing processes
have been analyzed in depth over the lastCopyright r Blackwell Munksgaard 2007
Date:Accepted 15 May 2006
To cite this article:Consolo U, Zaffe D, Bertoldi C, Ceccherelli G. Platelet-rich plasma activity on maxillary sinus flooraugmentation by autologous bone.Clin. Oral Impl. Res. 18, 2007; 252–262doi: 10.1111/j.1600-0501.2006.01330.x
252
few years and the biological fundamentals
better understood, taking into account
growth factor (GF) activities on bone for-
mation processes. Bone growth and differ-
entiation factors as well as the appropriate
extracellular matrix and stem cells are
needed for bone regeneration (Lynch et al.
1991; Bruder & Fox 1999; Ramoshebi &
Ripamonti 2000; Furst et al. 2003; Jakse
et al. 2003). These authors stated that the
combined use of GFs and graft material
might considerably improve bone healing,
fostering great expectations for their clin-
ical use.
Platelets are a natural source of GFs,
stored in a-granules. The b transforming
growth factor (TGF-b) family, which in-
cludes bone morphogenetic proteins
(BMPs), seems to be essential in tissue
regeneration (Centrella et al. 1986; Bone-
wald & Mundy 1990; Roberts & Spron
1993). The efficacy of BMPs and of GFs
in tissue regeneration has been documen-
ted in several studies (Urist 1965; Lynch
et al. 1991; Boyne 1996; Cochran et al.
1999; Terheyden et al. 1999; Ramoshebi &
Ripamonti 2000; Ruskin et al. 2000;
Boyne 2001; Roldan et al. 2004). When
platelets are activated by some factors,
such as thrombin or calcium, the a-granule
content is released into the surrounding
medium and GFs execute their regenera-
tion potential (Mannaioni et al. 1997;
Marx et al. 1998). The local application of
platelet-rich plasma (PRP) to achieve bone
regeneration in oral and maxillofacial sur-
gery was described by Marx et al. (1998).
This study indicated that the group treated
with supplementation of GFs, obtained by
mixing autologous PRP with bone graft,
had better bone healing and higher bone
density than the control group. Anitua
(1999) later used PRP to enhance success-
fully bone regeneration and improve soft
tissue healing in fresh extraction sites.
Kassolis et al. (2000) used PRP with
freeze-dried bone allografts in sinus floor
elevation and alveolar ridge augmentation.
Although the clinical advantages of PRP
use have been highlighted by several
authors (Marx et al. 1998; Anitua 1999;
Kassolis et al. 2000), the exact activity of
PRP on bone processes is still unknown
today (Schmitz & Hollinger 2001). The
aim of this study is to evaluate the regen-
erative potential of PRP on an implant site
of peculiar clinical relevance, which allows
clinical and histological comparative as-
sessments in the same subject. Bilateral
or unilateral sinus augmentations using
PRP and graft were recently performed in
experimental studies on animals (Jakse
et al. 2003; Furst et al. 2003; Roldan
et al. 2004; Suba et al. 2004). These studies
did not always yield equivalent results, but
they were almost always clinically suita-
ble. Our study was performed on consent-
ing patients, performing bilateral maxillary
sinus floor augmentation, using autologous
bone on one side and autologous bone plus
PRP contralaterally. The work intends to
analyze the PRP effect on bone regenera-
tion over time.
Material and methods
Preparation of PRP
Our protocol, optimized according to the
Immuno-transfusion Department of the
Modena Medical Center, required that
blood (about 450 ml) had to be drawn
24 h before surgery, using an ordinary blood
container containing acid citrate dextrose
solution (80 ml) as an anticoagulant. The
drawn sample was centrifuged (RC3C, Sor-
vall, Thermo Electron Corporation, Wal-
tham, MA, USA) at 1200 g for 6 min at
201C to obtain two moieties: FR1 (about
280 ml), plasma and platelets, and FR2
(about 250 ml), erythrocytes. FR2 was re-
infused into anemic patients. Immediately
before surgery, FR1 was centrifuged at
4400 g for 6 min at 141C to obtain the
two fractions: about 240 ml of platelet-
poor plasma and 40� 5 ml of PRP. Part
of the PRP was used to prepare the auto-
logous thrombin by calcium chloride addi-
tion (recalcification). PRP activation, i.e. a-
granules release, and a quick PRP gelation
was obtained by mixing PRP with autolo-
gous thrombin (3 : 1).
Clinical protocol
This study started in 1999 and patient
grafting ended before March 2002. The
preliminary results were communicated
at the Ninth International Congress on
Reconstruction and Preprosthetic Surgery,
Kiel D, 2001, whereas the local ethical
committee (Modena University, General
Hospital and Healthy District) was estab-
lished on December 2001. Moreover, we
obtained informed consent from the pa-
tients, in particular explaining the objec-
tives and protocol of the study, and possible
side effects. Patients were guaranteed spe-
cific and continual health assistance and
could opt out of the procedure at any phase
of the study.
Patient selection, criteria of inclusion andprocedures
All patients whose medical conditions
might increase surgical risks of the research
protocol were excluded from this study
(Table 1). All patients judged as being un-
reliable for continuity of care and availabil-
ity for follow-up were also excluded.
Patients included in the study had a bilat-
eral maxillary sinus pneumatization with
corresponding alveolar atrophy (similar in
both sinuses) of classes C and D (Jensen
Table 1. Clinical criteria for patient selection
Systemic contraindications Local contraindications
Diagnosis of severe medical conditions, or disorders causingmetabolic bone deterioration
Oral disease, diffuse acute gingivitis, complex periodontitisinadequately treated
Ongoing therapies unrelated to the present study Aggressive periodontitis, diagnosis or history, also medical historyOngoing radiotherapy or antiblastic therapy, or therapy completedwithin 36 months
Diagnosis of inadequately treated sinus disease, and poor outcomeof sinus disease
Neurotic and psychotic disorders or probably poor compliance Dental and/or rehabilitative therapies unrelated to the present studyPregnancy, puerperium or lactation Extreme alveolar atrophy of posterior maxilla with absence of
continuous bony sinus floorAlcoholism and/or habitual smokerTetracycline or non-steroidal anti-inflammatory drugs (NSAID)intoleranceUnderage or above 60 years Parafunctions
Consolo et al . PRP activity on sinus augmentation
253 | Clin. Oral Impl. Res. 18, 2007 / 252–262
1999). A total of 16 patients, 11 women
and five men, with age ranging between 18
and 60 years, were included in the study.
All patients underwent clinical and
radiographic evaluations before the trial
and during follow-up. Conventional radio-
graphs (e.g., orthopantomography), com-
puted tomography (CT) with orthogonal
image reconstruction and densitometric
evaluation, as bone quality index (Misch
1999), were performed on sites before and
after treatment. The same examiner per-
formed clinical analyses and roentgeno-
graphic evaluations. The radiologist
standardized the evaluation by choosing
six selected zones in each maxillary sinus,
so as to always repeat the densitometric
assessments in the same site. Zones were
selected considering the radiographic ap-
pearance of the floor to reach the greatest
efficiency value and the lowest attenuation
coefficient (Rao & Alfidi 1981). Only va-
lues relative to densitometric evaluations
of sites without overlapping of sinus aug-
mentation grafting and ridge atrophy cor-
rection were considered. The radiographic
and densitometric data of sites enabled us
to define the clinical classification of sinus
floor (Jensen 1999) in relation to the
implant insertion phase.
Two double-blinded teams assessed the
clinical success of the sinus augmentation,
after clinical and roentgenographic studies.
Full success of the surgical therapy was
designated if the sinus simultaneously
showed: (a) no complications due to ther-
apy, (b) usual healing time of treated zones
and (c) bone graft persistency (evaluated by
CT dental scan), which provided more than
8 mm (from the native alveolar ridge to the
upper limit of bone graft) of thickness of
uniform bone in relation to the prosthetic
plan. When the two assessments did not
reach the same conclusion, the less favor-
able evaluation was taken to avoid false
positives considering the clinical risks, in
particular from a therapeutic standpoint.
Surgery and follow-up
Each patient was clinically assessed in
great detail in relation to prosthetic requi-
sites and the need to perform a correct and
complete oral rehabilitation, according to
the indications and procedures stated by
Jensen (1999). Owing to the absence of
adequate clinical indications (class of sinus
atrophy) in patients (Jensen 1999), im-
plants were never inserted concurrent to
the sinus graft. In each patient, the side
treated with bone graft and PRP was ran-
domly chosen. The Langer & Langer
(1990) overlap flap, a modification of the
original technique (Boyne & James 1980;
Tatum 1986), was performed to gain access
to the maxillary sinus and to prepare it for
the floor augmentation. The modification
for the most part consisted in an incision
effected distant from the sinus access,
which guarantees a wide cover of both the
grafting site and alveolar ridge. Moreover,
surgery was planned to avoid ostium ob-
struction. Iliac crest was used as a donor
site. Autologous bone was harvested from
the anterior iliac crest. Conserving the
inguinal ligament and femoral cutaneous
nerve, a linear incision of soft tissue, along
the outer lip of the iliac crest (1 cm behind
the anterior superior iliac spine), was per-
formed. The periosteum was dissected in
the middle of the iliac crest and bone
harvested from a surgical operculum per-
formed by a chisel and a sharp spoon. One
sinus was grafted with bone and the con-
tralateral with bone mixed with PRP.
Patients were then randomized into four
groups (four patients each) to distribute the
patients according to the planned implant
insertion. Clinical and roentgenographic
evaluation of grafted sites were performed
to monitor treatment progress. Densitome-
tries were performed on patients about 15
days before implant insertion, in the same
sites as the pre-surgical phase. Implant
insertion, singly carried out in each of the
four groups 4, 5, 6 or 7 months after
surgery, concurred with the site biopsy.
Cylindrical core biopsies were obtained
through the surgical access of the grafted
site with a hollow mill at 600 r.p.m. under
saline jet for histology. Patients were trea-
ted with tetracycline (Bassado (doxycy-
cline) – 100 mg twice a day, for 3 days
starting 5 days before biopsy, Pharmacia
Upjohn, Nerviano MI, Italy) to gain addi-
tional information on bone formation. The
side of biopsy facing the oral mucosa was
labeled with methylene blue after saline
and heparin wash to remove clots.
Histology
Biopsies were treated and methacrylate
embedded according to Consolo et al.
(2006). Microradiographs and sections
(obtained and treated as reported in Con-
solo et al. 2006) were analyzed and photo-
graphed using an Axiophot microscope
(Carl Zeiss AG, Oberkochen, Germany)
under ordinary light. Thick sections were
analyzed under fluorescent light (mercury
lamp, fluorescent isothiocyanate filter
setup) to detect newly formed bone. Trabe-
cular bone volume (TBV) of all biopsies, an
index of the amount of bone tissue (Parfitt
et al. 1987), was evaluated on the micro-
radiograph of the thick section of each
biopsy using a suitable image analyzer
and software (VIDAS, Carl Zeiss AG).
Statistics
Evaluations of clinical success, as previou-
sly reported, were performed using the w2-
statistic (Glantz 2003). Numerical data
were evaluated by usual estimators (mean
(m), standard deviation (SD), standard error
(SE), median) to define the sample distribu-
tion. Comparisons were performed by
means of nonparametric Mann–Whitney
U-test, Friedman test and Kruskal–Wallis
followed by the Student–Newman–Keuls
multiple comparison test (Glantz 2003).
Simple linear regression and correlation
was applied to densitometric data to define
the trend with time, and the overall test of
coincidence of regression lines was used to
compare the two treatments (Glantz 2003).
The null hypothesis H0 was rejected for a
critical significance level of Po0.05.
Results
The 16 patients (11 female and five
male) of this study ranged in age from 37
to 57 years (FþM¼47� 5.84; F¼ 47.09
� 5.9; M¼46.8� 6.37 – m� SD). All
patients had the same degree of sinus
atrophy (class D – Jensen 1999), and they
showed an almost uniform atrophy of both
the right and left sinus.
The PRP produced by the patient’s
whole blood (starting concentration of
300,000� 50,000 platelets/ml) contained
1000,000� 250,000 platelets/ml; there-
fore, platelet concentration increased
more than threefold. Surgery generally pro-
duced positive results: a considerable re-
sorption of grafted bone of both sinuses was
only observed in one patient. However, the
densitometric values of this patient were
substantially coherent with those of the
other patients. Patients had a lower level
of local inflammation (swelling and red-
Consolo et al . PRP activity on sinus augmentation
254 | Clin. Oral Impl. Res. 18, 2007 / 252–262
ness) and fewer additional side effects on
the facial side corresponding to the sinus
treated with PRP. Roentgenographic eva-
luations (Figs 1 and 2) confirmed the over-
all positive outcome of bone graft surgery
both in the immediate post-operative and
follow-up period. At 4 months (Fig. 2), we
observed a substantial conservation of the
initial volume of the graft, without remark-
able differences between the site treated
with bone and bone plus PRP, both of
which showed an almost uniform radio-
graphic aspect. Conversely, skeletal mass
had a smaller size, in particular in the
sinuses treated with autologous bone alone,
mainly 7 months after surgery. Moreover,
the uneven radiographic aspect of grafted
bone was often observed in sites treated
with autologous bone alone.
Roentgenographic analyses and clinical
evaluations of operative and postoperative
outcome allowed us to define temporally
the general clinical result. The contingency
tables (Table 2), calculated using the defini-
tion stated in Material and Methods, point
out that failures increased slightly with
time. Excluding the comparison at 4
months, where data were equal, w2 was
always statistically insignificant (P40.4).
The various clinical pictures are considered
not statistically different, as the P value was
higher than the critical level of significance.
Densitometry
The basal bone densitometry of the max-
illary sinus of the 16 patients ranged from
33 to 104 Hounsfield units (HU) (Table 3).
The average densitometric results of grafted
sinuses obtained 15 days before implant
insertion (Table 4) highlighted the consis-
tently higher densitometric values of sites
treated with PRP. Densitometric evalua-
tions were compared with nonparametric
tests. Despite the limited number of data
per group, data distribution (Table 5)
showed median values very similar to
mean values and low variance, which
constantly decreased over time. The
Mann–Whitney U-test showed no statisti-
cal significance between right and left den-
sitometric values of sinuses before
treatment (P40.57). A significant statisti-
cal difference between the autologous bone
group and bone plus PRP was shown 4, 5, 6
and 7 months after sinus floor augmenta-
tion (Po0.05: Kruskal–Wallis test, fol-
lowed by the Student–Newman–Keuls
test). Conversely, longitudinal analysis
showed statistical significance only among
7 or 6 and 4 months, but not the other
comparisons in the autologous bone group.
Instead, excluding 4 and 5 months com-
parison, longitdinal analysis showed signif-
icant statistical differences among months
4–7 for the bone plus PRP group (Po0.05 –
Kruskal—Wallis test, followed by the Stu-
dent–Newman–Keuls test).
Although the bone plus PRP group had
higher values than the autologous bone
group (þ 71% at 4, þ81% at 5, þ48%
at 6 and þ 29% at 7 months), the general
performance of densitometric values de-
creased over time in both groups (Fig. 3).
The linear regression of densitometry from
4 to 7 months after sinus floor augmenta-
tion produced two equations with different
slopes (Fig. 4), both highly significant. The
overall test of coincidence of regression
lines for the two groups (HUB¼ 685.9–
42.63t; HUBP¼ 1460–136.6t; B, autolo-
gous bone; BP, bone plus PRP; t¼months)
produced a value of F¼ 111.97 correspond-
ing to a probability of P�0.0001, meaning
that the two regression lines were statisti-
cally different. The theoretical point of
intersection (i.e., the concurrence of
densitometric values of sites of the two
groups) corresponds to a densitometric va-
lue of 335.2 HU at 8.24 months after sinus
augmentation, independent of the sinus
graft.
No statistical differences were observed
for gender when comparing the initial den-
sitometric condition with time (4–7
months), even when elaborating the densi-
tometric data in relation to the two treat-
ments.
Fig. 1. Computed tomographs of the same patient before (a) and 4 months after (b) surgery. The right sinus [on the left of (b) image] was grafted with autologous bone plus
platelet-rich plasma, and the left sinus [on the right of (b) image] was grafted with only autologous bone.
Consolo et al . PRP activity on sinus augmentation
255 | Clin. Oral Impl. Res. 18, 2007 / 252–262
Histology
Four months after surgery, microradio-
graphs of biopsies of grafted sites (Fig. 5)
showed an indented surface (Howship’s
lacunae, due to osteoclastic erosive activ-
ity) of almost all autologous-bone trabe-
culae. Microradiographs documented an
appreciable amount of newly formed bone
(Fig. 5) in sites grafted with bone plus PRP.
In sites treated with only autologous bone,
histology highlighted a substantial quies-
cence in both osteogenesis processes, low
fluorescence (Fig. 6), very low expression of
alkaline phosphatase (ALP; Fig. 7) and
bone remodeling, few osteoclasts positive
to tartrate resistant acid phosphatase
(TRAP; Fig. 7). Fragments spared from
osteoclastic erosion (Fig. 5) had a typical
lamellar structure with ellipsoidal-shaped
lacunae, empty at optical microscopy (Fig.
7) in sites treated with autologous bone
alone. In contrast, live osteocytes inside
some grafted bone fragments (Fig. 7) were
detected in sites grafted with bone plus
PRP. Osteogenic activity, positive to tetra-
cycline labeling (Fig. 6) and ALP histo-
chemical reaction (Fig. 7), was high in
these biopsies. ALP expression was consid-
erable not only along bone surfaces but also
in the soft tissue of medullar cavities
(Fig. 7). Osteoclastic activity was scanty
or absent (Fig. 7). Five and six months
after surgery, the histological differences
between autologous bone grafts and bone
plus PRP were not only less noticeable but
sometimes even reversed. Bone formation
Fig. 2. Transverse image digital reconstructions of the same patient as in Fig. 1, before (a¼R; b¼L) and 4 months after (c¼R; d¼L) surgery. Reconstructions of image
(b) were mirrored to uniform the left sight. Note the similarity of graft aspect in the two sites.
Table 2. Clinical outcome of sinus flooraugmentation, with or without PRP
S F T
4 monthsAB 4 0 4ABþ PRP 4 0 4T 8 0 8
5 monthsAB 2 2 4ABþ PRP 4 0 4T 6 2 8
6 monthsAB 2 2 4ABþ PRP 4 0 4T 6 2 8
7 monthsAB 2 2 4ABþ PRP 3 1 4T 5 3 8
S, clinical success; F, clinical failure; AB, auto-
logous bone; PRP, platelet-rich plasma; T, total.
Consolo et al . PRP activity on sinus augmentation
256 | Clin. Oral Impl. Res. 18, 2007 / 252–262
or erosion activities were not necessarily
found in sites treated with PRP, particu-
larly 6 months after surgery, but some-
times appeared on the contralateral side.
A continued increasing deprivation of bone
graft fragments was found on both sides.
ALP expression gradually decreased,
whereas osteoclastic erosion sometimes
became relevant, without relation to the
graft type. Seven months after surgery, no
differences were detectable in the sites,
grafted with only bone or with bone plus
PRP. Histology showed the prevalence of
newly formed woven bone containing ty-
pical irregular-shaped osteocytes and few
residues of grafted bone on both sides.
Histochemical results were similar: osteo-
genic activity appeared to be rather low
(Fig. 8) and sometimes a feeble osteoclast
activity was observed. Little formation of
lamellar bone was recorded in sites treated
with PRP (Fig. 8).
Four months after surgery, TBV evalua-
tions (Fig. 9) revealed a significant differ-
ence (P¼ 0.021, Mann–Whitney U-test)
between the site grafted with autologous
bone and the contralateral (bone plus
PRP, TBV¼ þ66%). The Friedman test
was statistically significant (P¼0.048) for
comparison of the TBV values (Fig. 9)
between autologous bone (m� SD¼26
� 5.2) and bone plus PRP (m� SD
¼43.3� 9.1). Five months after surgery,
the Mann–Whitney U-test highlighted a
statistical significance (P¼0.043) between
the two sites, and the Friedman test
showed statistical significance (P¼0.046)
comparing the TBV values (Fig. 9) between
autologous bone (m� SD¼ 29.2� 4) and
bone plus PRP (m� SD¼ 39.3� 5.7).
Six months after surgery, the Mann–Whit-
ney U-test did not reveal statistical signifi-
cance (P¼ 0.061) between the two sites,
whereas the Friedman test showed statis-
tical significance (P¼0.046) comparing
the TBV values (Fig. 9) between autologous
bone and bone plus PRP (TBV of PRP
sites¼ þ29%). Seven months after sur-
gery, the Mann–Whitney U-test gave
P¼0.15 and the Friedman test P¼ 0.317,
both statistically insignificant, between
the two sites (TBV of PRP sites¼ þ 20%).
Table 3. Hounsfield units (HU) densitometric values of maxillary sinuses before augmentation surgery
N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
R 40.2 45.1 68.5 104 38.6 70 80 60.5 39 55 69.5 85.4 48.6 54.8 55.4 51.5L 42.4 43.2 70 102.4 33.8 63.1 75.2 69.2 37 48 63 91.1 43.5 50.7 48.3 47
N, patient number; R, right sinus; L, left sinus.
Table 4. Densitometric values of maxillarysinuses at 105, 135, 165 and 195 days aftersurgery (15 days before implant insertion)
N Bone Boneþ PRP
105 days3 503.5 8025 608 979
10 450.1 911.811 530 870
135 days2 550 9008 450.5 7809 450 750
14 400 850165 days
4 400 7057 360 700
12 450 50015 500 600
195 days1 470 5006 380 450
13 400 55016 320 500
PRP, platelet-rich plasma.
Table 5. Descriptive statistics of Hounsfield units (HU) densitometric values of sinusesbefore and after augmentation
Time Mean Median SD SE
R b.s. 60.3 55.2 18.31 4.58L 58 49.5 19.58 4.89Bone4 4 m.a.s. 522.9 516.8 65.73 32.87Boneþ PRP4 890.7 890.9 74.25 37.12Bone5 5 m.a.s. 462.6 450.2 62.88 31.44Boneþ PRP5 820 815 67.82 33.91Bone6 6 m.a.s. 427.5 425 60.76 30.38Boneþ PRP6 626.2 650 97.07 48.54Bone7 7 m.a.s. 392.5 390 61.85 30.92Boneþ PRP7 500 500 40.82 20.41
b.s., before surgery; m.a.s., months after surgery; PRP, platelet-rich plasma.
Fig. 3. Graph showing the densitometric behavior
(mean and SD values expressed as Hounsfield units
(HU) units) in all subjects of the two groups
(A¼ autologous bone; B¼ autologous bone plus
platelet-rich plasma), before surgery and up to
7 months (m) after surgery. Note how values de-
crease over time in both groups, but were higher in
group B.
Fig. 4. Graph showing the regression lines summar-
izing the relationship between mean densitometric
values (expressed as Hounsfield units (HU) units)
and time (m, months) of the two groups (A, auto-
logous bone; B, autologous bone plus platelet-rich
plasma). The regression line of group B has a greater
slope than that of group A: extrapolating data de-
monstrate that the lines intersect just over 8 months
after surgery.
Consolo et al . PRP activity on sinus augmentation
257 | Clin. Oral Impl. Res. 18, 2007 / 252–262
Discussion
The results indicate a role of PRP in sti-
mulating bone formation in human graft
sites. This agrees with some studies (Ani-
tua 1999; Marx 1999) that pointed to PRP
as a potential source of GFs for bone
regeneration. Although several authors
(Jakse et al. 2003; Suba et al. 2004) report
good outcomes, some studies carried out in
experimental animal did not achieve satis-
factory results (Furst et al. 2003; Roldan
et al. 2004). In humans, PRP has been used
with various graft materials. When applied
with autologous bone (Philippart et al.
2003), with the results analyzed without
suitable quantitative measures and on dec-
alcified specimens, PRP did not appear to
be a constituent capable of activating cells.
On the whole, the overall indications
gleaned from the literature are varied, as
some authors believe that results from
studies on sinus augmentation cannot be
suitably compared owing to the absence of
an adequate standardization (Wallace &
Froum 2003; Graziani et al. 2004). This
is the main reason that drove us to plan
accurately all the procedures of our study,
so as to standardize all predictable variables
before evaluating the results from PRP plus
autologous bone grafts.
The method that we adopted for the
preparation of PRP is commonly used in
many studies on PRP behavior in tissue
regeneration (Marx et al. 1998; Camargo
et al. 2002; Furst et al. 2003; Roldan et al.
2004). Institutional health facilities for
processing blood and its derivates can
guarantee a standardized preparation and
high a quality of PRP, due to their high
standard of competence in this specific
field.
The use of specific and restricted criteria
for inclusions of patients in this research
undoubtedly limited the number of pa-
tients enrolled, but also favored better re-
sults. In agreement with some studies
(Danesh-Meyer & Filstein 2001; Mazor
et al. 2004), we included a broad range of
age, characterized by skeletal system aging
(Dao et al. 1993), to study a large quota
lifespan. Although a wide span, patient age
ranged between 37 and 57 years, with a
mean age of about 50 years both in men
and women. This rather high mean was
mainly due to the indication of treatment
of severe bone atrophy taken unlikely to be
found in younger healthy patients. Statis-
tical analyses highlighted an age distribu-
tion matched for gender. All patients were
classified as class D (Jensen 1999), corre-
sponding to a thin sinus floor (1–3 mm)
and, consequently, to a more problematic
possibility of bone regeneration. The high
homogeneity between male and female
patients and also between the two sinuses
of each patient was essential to realize
reliable results.
No roentgenographic differences were
detected between the two sinuses in the
short term. The reduction of grafted bone
mass was observed clinically in both si-
nuses, but a slightly greater subsidence was
recorded in sinuses grafted with only auto-
logous bone in the medium term.
Our definition of full surgical success
attempted to classify the progress of treat-
ment without automatically jeopardizing
the implant insertion, in particular, after
longer times. Success was defined by in-
dicators (complications, recovery, morpho-
logic and dimensional features of bone
graft) expressing good viability and optimal
Fig. 5. Microradiographs of biopsies of the same patient performed in the sinus treated with only autologous
bone (group A – a and c) or with autologous bone plus platelet-rich plasma (group B – b and d) 4 months after
surgery. Note the newly formed (woven) bone ( ) showing the high density of irregular-shaped osteocytes.
Note how the grafted bone ( ) shows an indented outer surface, particularly pronounced in (c) the site treated
with only autologous bone. Note also in the latter how osteoclasts have broken the grafted bone into small
fragments. Field width a¼b¼ 6 mm; c¼d¼ 800mm.
Consolo et al . PRP activity on sinus augmentation
258 | Clin. Oral Impl. Res. 18, 2007 / 252–262
capability of graft for supporting implant-
based prosthetic rehabilitation (Branemark
1983; Nystrom et al. 1993; Cawood et al.
1994). The w2-test showed no statistical
significance between the clinical outcomes
of the two treatments. The poor outcome
bilaterally observed in one patient was
probably due to chronic sinusitis, later
acknowledged by the patient, which, more-
over, relapsed during the 7 months after
surgery.
Our densitometric results agree with
those obtained by Rodriguez et al. (2003),
who achieved a mean densitometric value
increase of 35% in the site treated with
PRP and Bio-Osss
, 4 months after surgery.
Our follow-up indicated a marked densito-
metric difference between sinuses: the
PRP-treated sides always showed a higher
mean densitometric value and a compara-
tive densitometric increase of 70% at 4
months. No densitometric differences
were instead recorded between males and
females, both of initial densitometric va-
lues and their progress. The autologous
bone group showed a statistically signifi-
cant uniform decrease of densitometric
values over time, whereas the PRP group
showed similar values up to 4–5 months
(plateau-like increase), followed by a
decline. Regression lines of data converged
at about 8 months after surgery. Agreeing
with Marx et al. (1998), our results suggest
that PRP might be more effective in hu-
mans for the interval of time up to 6–7
months after surgery, whereas no differ-
ences could be found between the two
grafted sites in the long term.
Histology revealed differences in biopsies
only for a short time. A greater osteogenic
activity was recorded in PRP-treated sites
at 4 months. In these sites, newly formed
bone surrounded several autologous bone
fragments showing viable osteocytes in-
side. This evidence may stem from the
greater cell viability maintained by PRP.
Instead, no marked difference in ALP ac-
tivity and fluorescence was observed in the
medium and long term between the two
group biopsies. A TBV decrease was re-
corded in sinuses from 4 to 7 months, in
particular in PRP-treated sites. In sites
grafted with only autologous bone, the
initial bony mass roentgenographically de-
creased over time, but the biopsies showed
an almost constant amount of bone (TBV).
In the PRP-treated sites, the bony mass
reduction was lower, although we recorded
a decreasing TBV and a steeper regression
line of densitometries. Although we do not
have data before 4 months after surgery, we
can speculate that the bony mass produced
by PRP stimulation during the first 4–5
months was abundant, causing a subse-
quent marked decrease, probably due to
the absence of mechanical loading.
Owing to the biologic features of max-
illary sinus, the clinician does not target a
bony mass greater than the graft in the
maxillary sinus. The clinician aims to
preserve an adequate and viable bony
mass (architecture and volume) to meet
implant–prosthetic requirements. The
bone results obtained are in agreement
with studies where PRP was used to heal
intrabony defects, such as periodontal
pockets and sockets in animal models or
humans (Camargo et al. 2002; Suba et al.
2004). In those sites, defined in a multi-
parietal bone condition, PRP appeared cap-
able of inducing relevant bone regeneration
and stabilizing the bone mass, also with
bone substitutes.
In conclusion, our results do not point
out statistical clinical differences between
sites treated or not treated with PRP,
whereas densitometric and histologic ana-
Fig. 6. Morphology (a and b) and fluorescences (c and d) of group A (a and c) and B (b and d) biopsies of the same
patient, 4 months after surgery. Note in c the only labeled (fluorescent) bone found in the whole biopsy. More
newly formed (labeled) bone can be observed in the group B biopsy (d). Field width a–d¼ 375mm.
Consolo et al . PRP activity on sinus augmentation
259 | Clin. Oral Impl. Res. 18, 2007 / 252–262
lyses indicate better short-term results for
PRP. Several studies (Marx et al. 1998;
Marx 1999; Schmitz & Hollinger 2001;
Rodriguez et al. 2003; Roldan et al. 2004)
describe a decrease of the grafted bone mass
using clinical observations and statistical
regression models. The same authors state
that no additional differences in a bone
graft outcome were achieved 1 year after
surgery, whether or not PRP was used.
Larger studies are warranted to clarify this
ostensible contrast.
Fig. 7. Morphology (a, b: toluidine blue stain; c, d: under polarized light, trypan blue stain) and histochemistry
(e, f: TRAP, tartrate-resistant acid phosphatase; g, h: ALP, alkaline phosphatase) of group A (a, c, e and g) and B
(b, d, f and h) biopsies of the same patient, 4 months after surgery. The red arrows in a point to the empty
lacunae of the grafted bone (which appeared lamellar in (c)), surrounded by newly formed woven bone. Note
how no osteoclast activity (e) and ALP expression (g) was found in the group A biopsies. The yellow arrows in b
point to living osteocytes (inside lacunae) of grafted bone (lamellar in (d)). Note in (f) how a few osteoclasts
resorb grafted bone fragments and in h the good ALP expression of soft tissues of the group B biopsy. Field width
a–h¼405 mm.
Fig. 8. Morphology (a: toluidine blue stain; b: under
polarized light, trypan blue stain) and histochemis-
try (c: alkaline phosphatase (ALP)) of a group B
(autologous bone plus platelet-rich plasma) biopsy
of the same patient, 7 months after surgery. The
yellow arrows in a point to the lamellar bone (whose
structure is displayed in b), containing the typical
ellipsoid-shaped osteocytes, newly formed in appo-
sition to the previously formed woven bone. Note in
c the low ALP expression of the soft tissues of the
group B biopsy. Field width a–c¼ 405mm.
Fig. 9. Graph showing the trabecular bone volume
(TBV) amount (express as bone percent of the whole
biopsy) of all group A (autologous bone – � ) and
group B (autologous bone plus platelet-rich plasma –
&) biopsies, 4, 5, 6 and 7 months (m) after surgery.
Bars correspond to the mean TBV value. Note how
TBV remains almost constant in group A biopsies
and decreases over time in group B biopsies,
although they always have higher mean values.
Consolo et al . PRP activity on sinus augmentation
260 | Clin. Oral Impl. Res. 18, 2007 / 252–262
Acknowledgements: We wish to
thank Prof. Michele Lalla for statistical
assistance and Dr John Pradelli, MD, for
assistance in manuscript draft and
revision. The FAR Fund and MIUR (Cofin
2003) Research Fund supported this
investigation.
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