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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