the ultimate goal of periodontal therapy includes not only the arrest of progressive 
 periodontal disease but also the restitution of those parts of the supporting apparatus 
 which have been destroyed by disease .
regenerative procedures have been evaluated in 
 several studies using grafting materials , root surface conditioning , guided tissue 
 regeneration and application of growth factors .
different materials have been introduced for bone defect filling , i.e. , autografts , 
 xenografts , allografts , and alloplasts . among the various subgroups of alloplastic bone 
 grafts ,
bioactive glass ( bg ) is a type of bioactive ceramic with the ability to improve 
 bone formation that has been assessed in experimental models .
previous studies have shown that bg particles , when implanted in vivo , 
 incorporate into the connective tissue and undergo chemical transformation increasing 
 the ph of the site to approximately 10 .
this process leads to 
 the formation of a silica gel on the surface of the particles and subsequently an 
 amorphous calcium phosphate layer is formed by the interaction between calcium and 
 phosphate from the bg and the surrounding medium .
hench and polak ( 2002 ) have shown that the release of ions ( na , ca , and si ) from bg 
 materials controls the cell cycle leading to the differentiation and proliferation of 
 bone cells , modulating the expression of genes that regulate osteogenesis , and the 
 synthesis of growth factors .
growth factors are vital modulators during this process which can induce the migration , 
 attachment , proliferation and differentiation of periodontal progenitor cells . 

platelet - rich plasma ( prp ) is a preparation of autologous plasma that contains a higher 
 platelet concentration , allowing it to deliver a greater concentration of autologous 
 growth factors such us platelet - derived growth factor ( pdgf ) , transforming growth factor 
 beta ( tgf- ) , vascular endothelial growth factor ( vegf ) , insulin - like growth 
 factor ( igf - i ) , and epithelial growth factor ( egf ) , that regulate cell proliferation , 
 chemotaxis and differentiation . some specific platelet growth factors , like pdgf and tgf- ,
could promote the 
 growth and differentiation of the periodontal ligament and alveolar bone cells and could 
 be responsible for the clinical improvement observed in experimental sites
. other interesting feature of prp is its 
 sticky consistency due to its high fibrin content .
the fibrin component of prp may work 
 as a haemostatic agent aiding in stabilizing the graft material and the blood 
 clot .
blood clot 
 immobilization has been suggested as an important event in the early phases of wound 
 healing of periodontal regenerative procedures .
studies using histological techniques suggested that prp preparations may enhance local 
 bone formation , while 
 others did not confirm these 
 findings .
clinical studies have reported that treatments with a combination of prp and 
 demineralized freeze - dried bone graft allograft ( dfdba ) improve clinical parameters in 
 intrabony periodontal defects . in 
 the other hand
did nt find additional 
 benefit in the reduction of pocket depth , clinical attachment gain and defect filling 
 using prp with bg in the treatment of intrabony defects .
the use of prp associated with biomaterials is an alternative treatment approach that 
 may favor the process of bone tissue regeneration and should be investigated .
therefore , 
 the goal of this study was to evaluate , histomorphometrically , the healing of surgically 
 created intrabony defects in dogs treated with prp+bg .
nine adult female mongrel dogs ( mean weight=15 kg ) were included in the experiment .
the 
 study protocol was approved by the institutional animal research committee , state 
 university of campinas ( protocol # 686 - 1 ) .
the surgical procedures were performed under 
 general anesthesia with intravenous injection of a 3% sodium pentobarbital solution ( 0.5 
 ml / kg ) .
the mandibular second and fourth premolars had been previously extracted and the 
 extraction sites had been allowed to heal for 2 months . after this period , buccal and 
 lingual mucoperiosteal flaps were elevated and 3-wall intrabony defects ( 4x4x4 mm ) were 
 created at the mesial and distal aspect of the left and right mandibular first molar 
 ( figure 1 ) . following root planning , aiming cementum removal ,
a reference 
 notch was made with curettes on the root surface at the cement - enamel junction .
clinical view of the surgically created 3-wall intrabony defect ( 4x4x4 mm ) at the 
 mesial aspect of the first mandibular molar before that the gingival flaps have been positioned and sutured , a tofflemire matrix 
 involved by cotton ligature was adapted over the tooth surface and the remaining defect 
 was filled with gutta - percha ( figure 2 ) .
so , the 
 defects were exposed to plaque accumulation for a period of one month before the 
 treatment .
after that , scaling and root planing was performed and a regimen of daily 
 brushing plus topical application of 0.1% chlorhexidine gluconate was instituted for 7 
 days prior to the surgical procedures .
clinical view of the insertion of gutta - percha in the defect blood was obtained several min before the administration of anesthesia .
four 5-ml 
 tubes containing 0.5 ml of 3.2% sodium citrate solution ( an anticoagulant ) were drawn 
 from each dog .
the blood was thus separated into 3 basic parts : red blood cells ( at the 
 bottom of the tube ) , platelet enriched plasma ( a discrete grey line in the middle of 
 the tube ) and platelet poor plasma ( at the top of the tube ) .
the portion 
 corresponding to the platelet poor plasma was discarded from each tube and the 
 remaining content was centrifuged again at 1,200 rpm for 15 min .
four hundred 
 microliters of the middle portion , corresponding to the platelet enriched plasma , 
 were pipetted from each tube . in order to obtain the gel ,
30 l of 10% calcium 
 chloride was added to prp and heated in a water bath at 37c .
the gel was achieved 
 after a period of 10 to 15 min . a tube with a sample of whole blood 
 as well as a sample of prp , retrieved before adding calcium chloride of 10% , was sent 
 to a clinical veterinary laboratory to perform a platelet counting .
in the moment of the defect treatment , an apical reference notch was made with 
 curettes on the root surface at the remaining bone level .
each defect in each animal 
 ( a total of 4 defects/ animal ) was randomly assigned to one of the following 
 treatments ( the treatments with prp were located at the same side that was randomly 
 determined ) : control : the defect was naturally filled with coagulum ; 
 bg ( perioglas , us biomaterials , alachua , fl , usa ) : bg particles 
 were applied , filling the defect ; prp : after obtaining the prp gel , 
 it was immediately applied on the defect ; prp+bg : bg was 
 incorporated to the prp ( 1:1 ) and this assemblage was immediately taken to a water 
 bath at 37c for formation of a mixture of the gel and the bg graft .
primary , tension - free wound closure was accomplished following defect treatment , with 
 the gingival flaps positioned and sutured with interrupted sutures ( vicryl , ethicon 
 inc , so jos dos campos , sp , brazil ) at their presurgical position . 

immediately after the surgeries , an intramuscular injection of penicillin ( 1.5 ml  
 150,000 iu ) was given to the animal .
postoperative plaque control was performed by irrigation with a solution of 1% 
 chlorhexidine gluconate ( every other day ) .
after 90 days , under general anesthesia , 
 the animals were sacrificed with a perfusion of 10% neutral formalin solution .
the 
 jaws were dissected and the blocks containing the experimental specimens were 
 removed , and decalcified in a solution of equal parts of 50% formic acid and 20% 
 sodium citrate for 5 months .
the decalcified specimens were washed in running water , 
 dehydrated and embedded in paraffin .
five sections representing the midbuccal portion of each defect were selected for the 
 histometric procedures .
the 
 following distances were measured : total epithelium ( sulcular and junctional epithelium ) : from the 
 gingival margin to the apical border of the junctional epithelium . connective tissue adaptation ( without cementum ) : from the apical 
 border of the junctional epithelium to the coronal end of new cementum .
new cementum : from the apical notch to the most coronal part of new 
 cementum . new bone ( bone position ) : from the apical notch to the most coronal 
 extent of new bone .
negative values would be assigned if the bony crest was located 
 apically to the apical notch .
new bone area : area of newly formed bone filling the defect area 
 ( limited by the distance between the two notches in an apico - coronal direction and 4 
 mm away from the root surface in a lateral direction ) .
the area of new bone was 
 measured with an image analysis system that allowed the placement of a lattice on the 
 image of the created bone defect .
the intersection lines localized on bone were 
 marked to calculate the new bone area whereas intersections lines localized on bg 
 particles were not marked and therefore were not included for this purpose .
the measurements were performed using a microscope ( zeiss axioskop 2 , carl zeiss 
 instruments , gottingen , lower saxony , germany ) with a 1.25/.035 objective associated 
 with a video camera / computer / software ( image pro plus version 3.0 , media cybernetics , 
 silver spring , md , usa ) .
the mean values for all 
 groups were determined using the individual means from the 9 dogs .
the hypothesis 
 that there were no differences among the groups was tested by one - way anova .
if a statistical 
 difference was detected , tukey s pairwise multiple comparison test was used .
four 5-ml 
 tubes containing 0.5 ml of 3.2% sodium citrate solution ( an anticoagulant ) were drawn 
 from each dog .
the blood was thus separated into 3 basic parts : red blood cells ( at the 
 bottom of the tube ) , platelet enriched plasma ( a discrete grey line in the middle of 
 the tube ) and platelet poor plasma ( at the top of the tube ) .
the portion 
 corresponding to the platelet poor plasma was discarded from each tube and the 
 remaining content was centrifuged again at 1,200 rpm for 15 min .
four hundred 
 microliters of the middle portion , corresponding to the platelet enriched plasma , 
 were pipetted from each tube . in order to obtain the gel ,
30 l of 10% calcium 
 chloride was added to prp and heated in a water bath at 37c .
the gel was achieved 
 after a period of 10 to 15 min . a tube with a sample of whole blood 
 as well as a sample of prp , retrieved before adding calcium chloride of 10% ,
in the moment of the defect treatment , an apical reference notch was made with 
 curettes on the root surface at the remaining bone level . each defect in each animal 

( a total of 4 defects/ animal ) was randomly assigned to one of the following 
 treatments ( the treatments with prp were located at the same side that was randomly 
 determined ) : control : the defect was naturally filled with coagulum ; 
 bg ( perioglas , us biomaterials , alachua , fl , usa ) : bg particles 
 were applied , filling the defect ; prp : after obtaining the prp gel , 
 it was immediately applied on the defect ; prp+bg : bg was 
 incorporated to the prp ( 1:1 ) and this assemblage was immediately taken to a water 
 bath at 37c for formation of a mixture of the gel and the bg graft .
primary , tension - free wound closure was accomplished following defect treatment , with 
 the gingival flaps positioned and sutured with interrupted sutures ( vicryl , ethicon 
 inc , so jos dos campos , sp , brazil ) at their presurgical position . 

immediately after the surgeries , an intramuscular injection of penicillin ( 1.5 ml  
 150,000 iu ) was given to the animal .
postoperative plaque control was performed by irrigation with a solution of 1% 
 chlorhexidine gluconate ( every other day ) .
after 90 days , under general anesthesia , 
 the animals were sacrificed with a perfusion of 10% neutral formalin solution .
the 
 jaws were dissected and the blocks containing the experimental specimens were 
 removed , and decalcified in a solution of equal parts of 50% formic acid and 20% 
 sodium citrate for 5 months .
the decalcified specimens were washed in running water , 
 dehydrated and embedded in paraffin .
five sections representing the midbuccal portion of each defect were selected for the 
 histometric procedures .
the 
 following distances were measured : total epithelium ( sulcular and junctional epithelium ) : from the 
 gingival margin to the apical border of the junctional epithelium . connective tissue adaptation ( without cementum ) : from the apical 
 border of the junctional epithelium to the coronal end of new cementum .
new cementum : from the apical notch to the most coronal part of new 
 cementum . new bone ( bone position ) : from the apical notch to the most coronal 
 extent of new bone .
negative values would be assigned if the bony crest was located 
 apically to the apical notch .
new bone area : area of newly formed bone filling the defect area 
 ( limited by the distance between the two notches in an apico - coronal direction and 4 
 mm away from the root surface in a lateral direction ) .
the area of new bone was 
 measured with an image analysis system that allowed the placement of a lattice on the 
 image of the created bone defect .
the intersection lines localized on bone were 
 marked to calculate the new bone area whereas intersections lines localized on bg 
 particles were not marked and therefore were not included for this purpose .
the measurements were performed using a microscope ( zeiss axioskop 2 , carl zeiss 
 instruments , gottingen , lower saxony , germany ) with a 1.25/.035 objective associated 
 with a video camera / computer / software ( image pro plus version 3.0 , media cybernetics , 
 silver spring , md , usa ) .
mean values for each parameter were obtained per defect . the mean values for all 
 groups
the hypothesis 
 that there were no differences among the groups was tested by one - way anova .
if a statistical 
 difference was detected , tukey s pairwise multiple comparison test was used .
all 
 groups presented a similar healing pattern characterized mainly by the presence of 
 new cementum covering most of the root surface associated with the defect and new 
 bone , up to the top of the defect , with a small amount of connective tissue and 
 epithelium ( figure 3 ) .
the periodontal ligament 
 was characterized by the presence of collagen fibers obliquely oriented to the root 
 surface , extending between the new cementum and the newly formed bone .
photomicrographs of the treated 3-wall intrabony defect showing new bone and 
 cementum formation extending coronally to the apical notch ( h&e , original 
 magnification x20 ) .
a ) control ; b ) prp ; c ) bg ; d ) bg+prp .
note the remaining 
 particles of bg surrounded by new bone and connective tissue ( c and d ) .
arrows 
 indicate areas with new bone in contact with bg particles in the defects treated with bg , it was possible to observe that part of the material 
 seemed to be resorbed and replaced by bone , while some of the remaining bg particles 
 showed dissolution of their central part with newly formed bone inside of them . some 
 defects presented bone in direct contact and/or surrounding the bg particles ( figure 4 ) .
almost all defects that received bg 
 presented a dense connective tissue surrounding the remaining particles and areas 
 suggesting the formation of new bone .
new bone formation observed in the 3-wall intrabony defect treated with bg 
 ( h&e , original magnification x100 ) .
arrows indicate bone in direct contact 
 with bg particles the histometric results are shown in table 1 . 

a superior area of new bone was observed in the sites treated with prp+bg and bg 
 ( 13.802.32 mm and 15.632.64 mm , 
 respectively ) . in the other groups ,
the new bone area was 8.191.46 
 mm ( control group ) and 8.811.47 mm ( prp ) . although 
 the difference in the new bone area , no significant difference was found in the 
 linear parameter new bone , e.g. bone position : from the apical notch to the most 
 coronal extent of new bone ( 4.370.44 mm , 4.240.68 mm , 
 4.370.46 mm and 4.440.42 mm , for control group , bg , prp and prp+bg , 
 respectively ; p=0.85 ) . mean and standard deviation ( sd ) for the parameters evaluated after all the 
 treatments ( control , bg , prp and bg+prp ) .
means followed by different letters 
 are statistically different at 5% data analysis showed no significant differences among the groups regarding the 
 initial defect extension ( 4.550.17 mm , 4.480.20 mm , 4.480.28 
 mm and 4.570.32 mm , for control group , bg , prp and prp+bg , respectively ; 
 p=0.74 ) .
in addition , intergroup analysis demonstrated that no significant difference 
 was observed among the groups in the following parameters : total epithelium extension 
 ( 2.240.58 mm , 1.940.37 mm , 1.970.37 mm and 1.810.61 , 
 for control group , bg , prp and prp+bg , respectively ; p=0.45 ) , connective tissue 
 extension ( 0.900.28 mm , 0.840.41 mm , 1.070.27 mm and 
 1.150.32 mm , for control group , bg , prp and prp+bg , respectively ; p=0.59 ) and 
 new cementum extension ( 2.630.70 mm , 2.560.36 mm , 2.370.38 mm 
 and 3.100.47 mm , for control group , bg , prp and prp+bg , respectively ; 
 p=0.85 ) .
the results from the histometric measurements , i.e. , epithelial 
 length ( the portion of epithelium located on the root ) , connective tissue adaptation 
 and new cementum formation , expressed as the percentage of the distance between the 
 coronal and the apical notch are presented in figure 
 5 .
no undesirable events like inflammation and foreign body reactions were observed . all 
 groups presented a similar healing pattern characterized mainly by the presence of 
 new cementum covering most of the root surface associated with the defect and new 
 bone , up to the top of the defect , with a small amount of connective tissue and 
 epithelium ( figure 3 ) .
the periodontal ligament 
 was characterized by the presence of collagen fibers obliquely oriented to the root 
 surface , extending between the new cementum and the newly formed bone .
photomicrographs of the treated 3-wall intrabony defect showing new bone and 
 cementum formation extending coronally to the apical notch ( h&e , original 
 magnification x20 ) .
a ) control ; b ) prp ; c ) bg ; d ) bg+prp .
note the remaining 
 particles of bg surrounded by new bone and connective tissue ( c and d ) .
arrows 
 indicate areas with new bone in contact with bg particles in the defects treated with bg , it was possible to observe that part of the material 
 seemed to be resorbed and replaced by bone , while some of the remaining bg particles 
 showed dissolution of their central part with newly formed bone inside of them . some 
 defects presented bone in direct contact and/or surrounding the bg particles ( figure 4 ) .
almost all defects that received bg 
 presented a dense connective tissue surrounding the remaining particles and areas 
 suggesting the formation of new bone .
new bone formation observed in the 3-wall intrabony defect treated with bg 
 ( h&e , original magnification x100 ) .
a superior area of new bone was observed in the sites treated with prp+bg and bg 
 ( 13.802.32 mm and 15.632.64 mm , 
 respectively ) . in the other groups , the new bone area was 8.191.46 
 mm ( control group ) and 8.811.47 mm ( prp ) . although 
 the difference in the new bone area , no significant difference was found in the 
 linear parameter new bone , e.g. bone position : from the apical notch to the most 
 coronal extent of new bone ( 4.370.44 mm , 4.240.68 mm , 
 4.370.46 mm and 4.440.42 mm , for control group , bg , prp and prp+bg , 
 respectively ; p=0.85 ) . mean and standard deviation ( sd ) for the parameters evaluated after all the 
 treatments ( control , bg , prp and bg+prp ) .
means followed by different letters 
 are statistically different at 5% data analysis showed no significant differences among the groups regarding the 
 initial defect extension ( 4.550.17 mm , 4.480.20 mm , 4.480.28 
 mm and 4.570.32 mm , for control group , bg , prp and prp+bg , respectively ; 
 p=0.74 ) .
in addition , intergroup analysis demonstrated that no significant difference 
 was observed among the groups in the following parameters : total epithelium extension 
 ( 2.240.58 mm , 1.940.37 mm , 1.970.37 mm and 1.810.61 , 
 for control group , bg , prp and prp+bg , respectively ; p=0.45 ) , connective tissue 
 extension ( 0.900.28 mm , 0.840.41 mm , 1.070.27 mm and 
 1.150.32 mm , for control group , bg , prp and prp+bg , respectively ; p=0.59 ) and 
 new cementum extension ( 2.630.70 mm , 2.560.36 mm , 2.370.38 mm 
 and 3.100.47 mm , for control group , bg , prp and prp+bg , respectively ; 
 p=0.85 ) .
the results from the histometric measurements , i.e. , epithelial 
 length ( the portion of epithelium located on the root ) , connective tissue adaptation 
 and new cementum formation , expressed as the percentage of the distance between the 
 coronal and the apical notch are presented in figure 
 5 .
the use of different regenerative approaches in the treatment of periodontal defects has 
 demonstrated a variable clinical result .
some techniques have been used in association , aiming to increase 
 their effect on periodontal regeneration .
the present study was 
 designed to evaluate , histomorphometrically , the healing process of 3-wall intrabony 
 defects treated with bg , prp and their association .
prp has become a focus of current studies due to its potential to accelerate wound 
 healing .
it has been previously shown that prp stimulated pdl 
 cells and fibroblastic cell proliferationbut suppressed 
 epithelial cell division in vitro .
consequently , by ordering these cellular responses into a series 
 of related events , prp may facilitate wound - healing and tissue regeneration .
the claimed 
 ability to suppress epithelial cell proliferation seems advantageous for periodontal 
 regeneration by favoring the formation of a new connective tissue attachment and new 
 cementum on the root surface .
the 
 results of the present study failed to demonstrate that the use of prp can promote an 
 additional effect in terms of cementum formation when treating 3-wall intrabony defects . 

cementum formation for bg and prp followed the same trend observed for the control group 
 ( bg=2.5 mm/57% , prp=2.4 mm/53% , control=58% ) while the prp+bg showed a slightly greater 
 cementum formation ( prp+bg=3.10 mm/68% ) , but the differences among the groups were not 
 statistically significant . in this respect
, it should be recognized that a non - contained 
 osseous defect might have favored the discrimination of quantitative differences among 
 the treatments . in a previous histological study
, kim , et al ( 2004 ) evaluated the healing patterns following flap surgery in 
 experimentally induced 1- , 2- and 3-wall intrabony defects . according to the authors , 
 one- and 3-wall intrabony defects
can be considered pre - clinical models that are 
 relatively easy to manage and from which homogeneous healing outcomes may be expected . 

they suggested that these defects appear to be reproducible models to evaluate candidate 
 technologies for periodontal regeneration .
regarding the 3-wall intrabony defect , they reported a mean 
 cementum formation of approximately 70% of the initial defect extension . in the present 
 study ,
a period of 1 month of plaque accumulation was allowed as a way to obtain some 
 chronification of the defect .
the control group showed 2.6 mm ( 58% ) of the original 
 defect covered with new cementum .
this result confirms the high regenerative potential 
 of this type of defect that provides favorable anatomic characteristics for clot 
 stabilization and protection .
it is well accepted that healing of intrabony defects is positively correlated to the 
 number of bone walls limiting the defect .
therefore , the 3-wall intrabony defect used in 
 the present study provides ideal extent and location of tissue resources , cells and 
 vascularity circumscribing the defect , which might have favored bone formation .
the 
 linear measurement of the new bone height revealed an impressive coronal bone formation 
 for all the groups , with no significant differences among the treatments .
the claimed osteoinductive properties of prp could not be supported by the results of the present study .
it 
 has been suggested that prp could be used to increase the bone deposition rate and the 
 quality of bone regeneration when augmenting sites prior to or in conjunction with 
 dental implant placement .
nevertheless , more recent animal studies could not find 
 increased bone regeneration when prp was used .
recently , bioactive glass has been used as a way to achieve bone and periodontal 
 regeneration based on its osteoconductive properties . the need for an 
 alternative to autologous and allogenic bone grafts
have encouraged the search of a 
 material that could be safe , surgically convenient and predictably promote regeneration 
 with a reduced morbidity . in this study ,
the use of bg was not associated with any 
 foreign body reaction , showing biocompatibility with periodontal tissues .
histological observations after treatment of periodontal defects with bg in nonhuman 
 primates showed a significant increase of new cementum and inhibition of downgrowth of 
 junctional epithelium .
when bg is 
 implanted in vivo , the ph of the site increases , a layer rich in silica 
 gel is formed on the surface of the particles and subsequently an amorphous calcium 
 phosphate layer is formed by the interaction between calcium and phosphate from the bg 
 and the surrounding medium .
its 
 superficial bioactivity may stimulate a rapid formation of a connective tissue seal that 
 is supposed to have the ability to block the epithelium migration and allow for the 
 repopulation of the previously contaminated area by periodontal ligament cells . in the present study ,
almost all defects 
 that received bg presented a dense connective tissue surrounding the remaining particles 
 in accordance with observations of previous studies . in the groups
treated with bg , the area of new bone was 13.802.32 mm 
 ( prp+bg ) and 15.632.64 mm ( bg ) , respectively . in the groups that did 

not receive this material , the new bone area was 8.191.46 mm 
 ( control group ) and 8.811.47 mm ( prp ) . based on the significant 
 differences observed in the area of newly formed bone when groups with and without bg 
 were compared the present study corroborates the hypothesis that this material could act 
 as an osteoconductive graft .
in addition , it was observed that some remaining bg 
 granules showed dissolution of their core with newly formed bone , as described in the 
 literature . aiming to increase the periodontal and bone regeneration
, some studies evaluated the 
 additional effect of prp , combined with different types of grafting materials , on the 
 treatment of intrabony defects . in spite of some clinical results showing a greater 
 reduction of pocket depth and
gain in clinical attachment level , other clinical studies 
 failed to demonstrate an additional effect . in 3-wall periimplant defects in dogs 
 treated with prp associated to xenogenic bone graft ,
the same 
 authors also reported no significant effect with the addition of prp to xenogenic bone 
 grafts on bone mineral density or graft maturity .
these observations are in agreement with the results of the 
 present study , which could not demonstrate an additional effect of prp in periodontal 
 and bone regeneration of 3 wall intrabony defects .
the histomorphometric findings 
 demonstrated that the sites treated with prp+bg showed a similar amount of new bone 
 ( 13.802.32 mm ) when compared with the sites that only received bg 
 ( 15.632.64 mm ) .
the ideal platelet and growth factor concentration to promote periodontal regeneration 
 has not yet been established . to the date , there is insufficient information about 
 growth factor interactions and how they influence the activations of gene expression and 
 protein production . in the present study ,
the achieved percentage mean of platelet 
 concentration was 227.02% ( mean of 463.015 platelets / ml ) in relation to blood platelets 
 count .
( 2003 ) 
 reported that growth factors may act at specific times and at appropriate concentrations 
 and this may be other explanation for the different results obtained in studies 
 evaluating the use of prp .
the great variability in the outcomes of the studies with prp 
 may also be explained by the diversity of methods to obtain it .
the technique to produce 
 prp in the present study was used in other animal studies by our research 
 group .
this technique enables the production of a platelet 
 concentration generally four times greater than the whole blood . according to landsberg , 
 et al .
( 1998 ) , thrombin promotes the 
 release of antibodies to coagulation factors v and vi , which could be a potentially 
 life - threatening event .
these antibodies cross - react with human factor v thereby , 
 causing a factor v deficiency that can be sufficiently severe to induce excessive 
 bleeding and even death . considering that , the use of thrombin in this type of study is 
 not allowed in our country . in the present study , instead of thrombin
, 10% calcium 
 chloride was added to prp and heated in a water bath at 37c .
( 2003 ) measured the concentrations of 
 bfgf , vegf , pdgf - bb and tgf-1 released from platelet concentrate and whole 
 blood , before and after the addition of calcium alone , thrombin alone and various 
 concentrations of calcium and thrombin .
those authors observed that calcium chloride , 
 regardless of the use of thrombin , released platelet growth factors . in this 
 study ,
the concentration of 
 growth factors that was released was sufficient to promote endothelial cell 
 proliferation in vitro .
recently , the tissue engineering science has provided a new possibility of cell therapy 
 as a future alternative for the use of conventional regenerative techniques .
this strategy that exploits the 
 regenerative capacity of stem cells grown in a three - dimensional scaffold and 
 subsequently implanted into the defect , in the presence of molecule modulators , may help 
 overcoming several limitations of current regeneration modalities .
in an in vitro study , 
 the application of growth factors found in prp ( tgf-1 and igf - i ) in cultures of 
 periodontal ligament cells , increased their mitotic activity and their capacity for 
 adhesion on the root fragments surface . the use of platelet 
 growth factors associated with cell therapy could be an alternative favoring the process 
 of periodontal regeneration .
within the limits of this animal model study , it may be concluded that the association 
 of prp with bg did not exert an additional effect to periodontal regeneration of 3-wall 
 intrabony defects in dogs .
further studies are necessary to investigate the advantages 
 and limitations of these materials in the treatment of periodontal defects .
 objectivethis study was designed to evaluate , histomorphometrically , the association of 
 platelet - rich plasma ( prp ) and bioactive glass ( bg ) in the treatment of 
 periodontal intrabony defects.material and methodsnine mongrel dogs were included in the study . 
 three - wall intrabony defects were 
 surgically created at the mesial and distal aspect of first mandibular molar and 
 exposed to plaque accumulation for 1 month . 
 the defects were randomly assigned to 
 the groups : control , bg , prp , prp+bg . 
 dogs were sacrificed 90 days after the 
 surgeries . 
 the histometric parameters evaluated were : length of sulcular and 
 junctional epithelium , connective tissue adaptation , new cementum , new bone , 
 defect extension and area of new bone filling the defect.resultsa superior area of new bone was observed in prp+bg and bg ( 13.802.32 
 mm2 and 15.632.64 mm2 , respectively ) when 
 compared to the other groups ( 8.191.46 mm2 and 8.811.47 
 mm2 for control and prp , respectively ) . 
 no statistically significant 
 differences were observed in the remaining parameters.conclusionwithin the limits of this study , it may be concluded that prp failed to provide 
 statistically significant improvements in the histometric parameters . 