alveolitis is one of the most common postoperative complications following the 
 extraction of permanent teeth . it is a complication characterized by severe pain 
 starting between the first and third day after extraction , associated with an empty 
 socket completely or partially filled of a normal blood clot with or without 
 halitosis . in addition to the 
 local symptoms , acutely infected sockets can be associated with signs of systemic 
 infection , such as fever . the 
 incidence of alveolitis has been reported to range from 3 to 4% following routine dental 
 extractions , and from 1 to 45% after removal of mandibular third molars . the most widely accepted hypothesis points to increased fibrinolytic 
 disintegration of the blood clot triggered by infection and/or surgical trauma as the 
 etiologic factor of alveolitis . ( 1978 ) showed a possible role of anaerobic 
 microorganisms , which are also the predominant microorganisms in pericoronitis related 
 to the etiology of alveolitis . moreover , other factors are considered as contributors to 
 the occurrence of alveolitis , including female gender , tobacco use , oral contraceptives , 
 low operator experience , mandibular teeth , and overzealous irrigation or curettage of 
 the socket after extraction . the extreme distress and pain suffered 
 by patients with alveolitis , as well as the loss of work days and the need of numerous 
 treatment sessions , make this complication equally costly for patients and dentists . at 
 least 45% of patients will need four or more appointments in order to achieve a complete 
 solution of symptoms . the term " treatment " can be quite misleading when used in the context of alveolitis as 
 this condition can not be correctly treated in the absence of a firmly established 
 underlying etiology . clinical management is directed towards reassurance and prompt pain 
 relief until normal healing process starts . in an attempt to reduce the incidence of 
 alveolitis , different local and systemic approaches have been adopted ; namely , the use 
 of antibiotics , antiseptic agents with lavage , antifibrinolytic agents , obtundent 
 dressings , antiinflammatory drugs , and clot - supporting agents . considering that healing may be disturbed even in normal healthy patients , the assessment of healing in extraction 
 sockets , especially under disturbed healing , is considerably important , also considering 
 further rehabilitation with dental implants or other procedures . comparison of different 
 socket medicaments and their effects on alveolar wound healing and infection resolution 
 is a goal that can be achieved through the assessment of socket healing . in addition , 
 factors responsible for promoting or delaying healing can also be ascertained through 
 the same approach . however , several variables thought to be involved in disease 
 pathogenesis affecting the interpretation of human studies , and the exact mechanisms 
 involved in alveolitis onset are not completely known , therefore , making it difficult to 
 prevent and impairing the development of most effective therapeutic strategies . 
 consequently , experimental rat models may be extremely useful to alveolitis studies , 
 since they present several advantages including easy handling , availability of 
 experimental reagents and susceptibility of suppurative alveolitis induction . the aim of this study was to characterize a rat model of experimentally induced 
 alveolitis by investigating the levels of c - reactive protein ( crp ) and determining the 
 bacterial species present in inoculation material used for disease induction related to 
 the histometrical features of the delayed wound healing . thirty 10 week - old male wistar rats ( rattus novergicus albinus ) 
 weighing about 250 g were used in this study . the animals were submitted to 
 coproparasitological test in which pathogenic parasites were not found . the animals 
 were kept in individual cages previously disinfected and covered by sterile sawdust . 
 before and during the experimental phase , the animals were fed with solid chow 
 ( anderson & clayton s.a . , so paulo , sp , brazil ) , except for the first 24 
 postoperative hours , when ground chow was offered . the experimental protocol was 
 approved by the local institutional committee for animal care and use . for surgical interventions ( figure 1 ) , the 
 animals received a preanesthetic medication consisting of an intramuscular injection 
 of xylazine hydrochloride ( 15 mg / kg body weight ) in the back of the thigh . further 
 anesthesia followed by a combination of ketamine hydrochloride ( 25 mg / kg body weight ) 
 and xylazine hydrochloride ( 10 mg / kg body weight ) via intramuscular injection in the 
 same region . asepsis of the anterior portion of the maxilla was carried out with 2% 
 chlorhexidine solution and the maxillary right central incisor was 
 extracted . the animals were 
 randomly assigned to 2 groups : group i , in which the sockets were filled with blood 
 clot ( to allow the normal repair ) , and group ii , which received an intra - alveolar 
 application of epinephrine solution 1:1,000 ( ariston ind . ltda , so paulo , sp , 
 brazil ) with an absorbent paper point ( sybon kerr , orange , ca , usa ) during 1 min 
 followed by application of suppurative secretion obtained from donor rats using an 
 absorbent paper point during 1 min . a ) 
 luxation of right maxillary incisor ; b ) extraction ; c ) application of 
 adrenaline solution 1:1,000 1 min ; d ) inoculation of purulent secretion into 
 the socket ; e ) socket aspect after ischemia and contamination ; f ) socket aspect 
 after 3 days of contamination showing pus and gingival edema ; g ) right maxilla 
 specimen obtained to histological process . the suppurative secretion was obtained from rats that received the application of 
 absorbent paper points containing 1:1,000 epinephrine solution in socket immediately 
 after the extraction of right maxillary incisor 1 min followed by application of 
 reduction medium ( mrt ) using sterile paper points . however , due to 
 a high variability in the onset of experimental alveolitis , these animals were used 
 as previously standardized suppurative secretion donors . the collected alveolar 
 secretion was cultured in thioglycollate medium , stored at -196c , and then used as 
 aforementioned , resulting in a 100% efficacy of experimental alveolitis induction in 
 the test group , clinically similar to the one observed in the donor rats . at 6 , 15 , and 28 post - extraction days , 5 animals from each group were euthanized with 
 a massive dose of anesthetics . the presence of 39 subgingival species ( table 
 1 ) was investigated in the inoculation material by checkerboard dna - dna 
 hybridization . three 
 samples of secretion , before inoculation , were placed in separate eppendorf tubes 
 containing 0.15 ml te ( 10 mm tris - hcl , 1 mm edta , ph 7.6 ) . 0.15 ml of 0.5 m naoh was 
 added to each tube and the samples were dispersed using a vortex mixer . the samples 
 were boiled for 10 min and neutralized using 0.8 ml of 5 m ammonium acetate . the 
 released dna was then placed into the extended slots of a minislot-30 apparatus 
 ( immunetics , cambridge , ma , usa ) , concentrated onto a 15x15 cm positively charged 
 nylon membrane ( boehringer - mannheim , indianapolis , in , usa ) and fixed to the membrane 
 by baking at 120c for 20 min . the membrane was placed in a miniblotter 45 
 ( immunetics ) with the lanes of dna at 90 to the lanes of the device . digoxigenin - labeled whole genomic dna probes to 39 subgingival species were 
 hybridized in individual lanes of the miniblotter . after hybridization , the membranes 
 were washed at high stringency and the dna probes detected using antibody to 
 digoxigenin conjugated with alkaline phosphatase and chemiluminescence 
 detection . bacterial species investigated by checkerboard dna - dna hybridization strains from atcc ( american type culture collection , rockville , md ) strains from forsyth institute the levels of serum crp were determined in attempt to investigate a possible systemic 
 involvement of induced alveolar infection , as previously described . it was used a commercially available 
 agglutination kit ( labtest diagnstica , so paulo , sp , brazil ) . in brief , 50 l of 
 serum samples from 5 animals per group at 0 , 3 , 6 , 15 and 28 days 
 ( diluted 4 , 16 , 64 , 128 and 256 times ) , 50 l of 0.9% nacl and 50 l of a solution 
 containing latex beads coated with anti - crp antibodies were dispensed in 96-well 
 plates . the plate was agitated with circular movements for 2 min , and the macroscopic 
 evidence of agglutination was observed . for the semiquantification of crp levels , the 
 level of assay sensitivity ( > 6 mg / l ) was multiplied by the titre of crp of each 
 sample . samples were fixed in 10% buffered formalin for 7 days , decalcified in 4.7% edta ph 
 7.0 for 35 days , histologically processed , and embedded in paraffin wax . semi - serial 5-m - thick longitudinal 
 sections were obtained and stained with hematoxylin - eosin for evaluation by light 
 microscopy . for histometric analysis was used a 40x objective and 8x zeiss kpl 
 eyepiece containing a zeiss ii integration grid with 10 parallel lines and 100 points 
 symmetrically distributed over a quadrangular area . the histological quantified 
 variables were bone , connective tissue , inflammatory infiltrate , blood clot and empty 
 spaces . based on the 100-point grid , bone , connective tissue , inflammatory 
 infiltrate , blood clot and empty spaces count was expressed by density ( d ) . the 
 density is the total of points of each variable divided per 100 
 points of the grid . the results were expressed by mean of density observed in each 
 group and analyzed period . student 's t test or mann - whitney rank sum 
 test ( t ) was applied when group i and ii were compared in each period . one - way anova 
 or kruskal - wallis followed by tukey 's or dunn 's test took place when periods 6 , 15 
 and 28 days were compared in each group using graphpad prism 3.0 software ( graphpad 
 software inc . , san diego , ca , usa ) . spearman 's correlation test was also undertaken 
 in order to establish possible relationship among quantified variables . thirty 10 week - old male wistar rats ( rattus novergicus albinus ) 
 weighing about 250 g were used in this study . the animals were submitted to 
 coproparasitological test in which pathogenic parasites were not found . the animals 
 were kept in individual cages previously disinfected and covered by sterile sawdust . 
 before and during the experimental phase , the animals were fed with solid chow 
 ( anderson & clayton s.a . , so paulo , sp , brazil ) , except for the first 24 
 postoperative hours , when ground chow was offered . the experimental protocol was 
 approved by the local institutional committee for animal care and use . for surgical interventions ( figure 1 ) , the 
 animals received a preanesthetic medication consisting of an intramuscular injection 
 of xylazine hydrochloride ( 15 mg / kg body weight ) in the back of the thigh . further 
 anesthesia followed by a combination of ketamine hydrochloride ( 25 mg / kg body weight ) 
 and xylazine hydrochloride ( 10 mg / kg body weight ) via intramuscular injection in the 
 same region . asepsis of the anterior portion of the maxilla was carried out with 2% 
 chlorhexidine solution and the maxillary right central incisor was 
 extracted . the animals were 
 randomly assigned to 2 groups : group i , in which the sockets were filled with blood 
 clot ( to allow the normal repair ) , and group ii , which received an intra - alveolar 
 application of epinephrine solution 1:1,000 ( ariston ind . ltda , so paulo , sp , 
 brazil ) with an absorbent paper point ( sybon kerr , orange , ca , usa ) during 1 min 
 followed by application of suppurative secretion obtained from donor rats using an 
 absorbent paper point during 1 min . a ) 
 luxation of right maxillary incisor ; b ) extraction ; c ) application of 
 adrenaline solution 1:1,000 1 min ; d ) inoculation of purulent secretion into 
 the socket ; e ) socket aspect after ischemia and contamination ; f ) socket aspect 
 after 3 days of contamination showing pus and gingival edema ; g ) right maxilla 
 specimen obtained to histological process . the suppurative secretion was obtained from rats that received the application of 
 absorbent paper points containing 1:1,000 epinephrine solution in socket immediately 
 after the extraction of right maxillary incisor 1 min followed by application of 
 reduction medium ( mrt ) using sterile paper points . however , due to 
 a high variability in the onset of experimental alveolitis , these animals were used 
 as previously standardized suppurative secretion donors . the collected alveolar 
 secretion was cultured in thioglycollate medium , stored at -196c , and then used as 
 aforementioned , resulting in a 100% efficacy of experimental alveolitis induction in 
 the test group , clinically similar to the one observed in the donor rats . at 6 , 15 , and 28 post - extraction days , 5 animals from each group were euthanized with 
 a massive dose of anesthetics . the presence of 39 subgingival species ( table 
 1 ) was investigated in the inoculation material by checkerboard dna - dna 
 hybridization . three 
 samples of secretion , before inoculation , were placed in separate eppendorf tubes 
 containing 0.15 ml te ( 10 mm tris - hcl , 1 mm edta , ph 7.6 ) . 0.15 ml of 0.5 m naoh was 
 added to each tube and the samples were dispersed using a vortex mixer . the samples 
 were boiled for 10 min and neutralized using 0.8 ml of 5 m ammonium acetate . the 
 released dna was then placed into the extended slots of a minislot-30 apparatus 
 ( immunetics , cambridge , ma , usa ) , concentrated onto a 15x15 cm positively charged 
 nylon membrane ( boehringer - mannheim , indianapolis , in , usa ) and fixed to the membrane 
 by baking at 120c for 20 min . the membrane was placed in a miniblotter 45 
 ( immunetics ) with the lanes of dna at 90 to the lanes of the device . digoxigenin - labeled whole genomic dna probes to 39 subgingival species were 
 hybridized in individual lanes of the miniblotter . after hybridization , the membranes 
 were washed at high stringency and the dna probes detected using antibody to 
 digoxigenin conjugated with alkaline phosphatase and chemiluminescence 
 detection . bacterial species investigated by checkerboard dna - dna hybridization strains from atcc ( american type culture collection , rockville , md ) strains from forsyth institute the levels of serum crp were determined in attempt to investigate a possible systemic 
 involvement of induced alveolar infection , as previously described . it was used a commercially available 
 agglutination kit ( labtest diagnstica , so paulo , sp , brazil ) . in brief , 50 l of 
 serum samples from 5 animals per group at 0 , 3 , 6 , 15 and 28 days 
 ( diluted 4 , 16 , 64 , 128 and 256 times ) , 50 l of 0.9% nacl and 50 l of a solution 
 containing latex beads coated with anti - crp antibodies were dispensed in 96-well 
 plates . the plate was agitated with circular movements for 2 min , and the macroscopic 
 evidence of agglutination was observed . for the semiquantification of crp levels , the 
 level of assay sensitivity ( > 6 mg / l ) was multiplied by the titre of crp of each 
 sample . samples were fixed in 10% buffered formalin for 7 days , decalcified in 4.7% edta ph 
 7.0 for 35 days , histologically processed , and embedded in paraffin wax . semi - serial 5-m - thick longitudinal 
 sections were obtained and stained with hematoxylin - eosin for evaluation by light 
 microscopy . for histometric analysis was used a 40x objective and 8x zeiss kpl 
 eyepiece containing a zeiss ii integration grid with 10 parallel lines and 100 points 
 symmetrically distributed over a quadrangular area . the histological quantified 
 variables were bone , connective tissue , inflammatory infiltrate , blood clot and empty 
 spaces . based on the 100-point grid , bone , connective tissue , inflammatory 
 infiltrate , blood clot and empty spaces count the 
 density is the total of points of each variable divided per 100 
 points of the grid . the results were expressed by mean of density observed in each 
 group and analyzed period . student 's t test or mann - whitney rank sum 
 test ( t ) was applied when group i and ii were compared in each period . one - way anova 
 or kruskal - wallis followed by tukey 's or dunn 's test took place when periods 6 , 15 
 and 28 days were compared in each group using graphpad prism 3.0 software ( graphpad 
 software inc . spearman 's correlation test was also undertaken 
 in order to establish possible relationship among quantified variables . the bacterial species present in the inoculation material were capnocytophaga 
 ochracea , fusobacterium nucleatum ss nucleatum , prevotella melaninogenica , 
 streptococcus anginosus , treponema socranskii and streptococcus 
 sanguis ( table 1 ) . the serum levels of c reactive protein ( crp ) were evaluated at 0 , 3 , 6 , 15 and 28 
 days in both control ( non - infected ) and infected rats . the infected rats showed 
 higher levels of serum crp when compared to non - infected animals . at day 3 after 
 infection the infected rats presented the highest serum levels of crp , followed by a 
 progressive decrease from 6 to 28 days after infection , but crp levels remained still 
 higher in infected compared to non - infected rats ( figure 2a ) . increased serum crp and delayed alveolar healing in experimental alveolitis 
 rats . ( b to f ) histometric results : bone , 
 connective tissue , inflammatory infiltrate , blood clot and empty space density , 
 presented as means and standard deviations by group , in each period . data were 
 analyzed by groups using student s t test or mann- whitney rank sum test and by 
 periods using one - way anova or kruskal - wallis test and tukey s or dunn s test 
 for multiple comparisons . at 6 days post - infection , the connective tissue was organized with proliferation of 
 blood vessels around a central area still occupied by blood clot . tissue organization 
 allowed observation of a small number of thin newly formed bone trabeculae near of 
 the alveolar walls and resorptive lacunae , mainly in the buccal wall ( figures 3a and 3b ) . fifteen days after infection , the connective tissue was well 
 organized with a smaller number of blood vessels . the newly formed bone trabeculae 
 were still thin , but numerous , formed mainly from the lingual wall towards the 
 central area of the socket . focal areas of resorption are also observed at this 
 period ( figures 3c and 3d ) . when analyzed 28 days after infection , the connective tissue 
 was well organized with a smaller number of blood vessels . the newly formed bone 
 trabeculae were thick and numerous , with defined medullar spaces occupying almost all 
 the surface of the median third , including the central portion of the socket ( figures 3e and 3f ) . histological 
 longitudinal specimens of group i : 6 days postoperative ( a and b ) showing blood 
 clot ( bc ) and connective tissue ( ct ) filling the cervical portion of socket 
 ( a ) ; and buccal cortical plate resorption ( blue arrows ) in ( b ) ; 15 days 
 postoperative ( c and d ) showing rich vascularized connective tissue ( ct ) , bone 
 ( asterisk ) and blood clot ( bc ) in ( c ) ; new bone formation ( asterisk ) , buccal 
 cortical plate resorption ( blue arrows ) surrounded by connective tissue ( ct ) in 
 ( d ) ; 28 days postoperative ( e and f ) displaying thick bone trabeculae 
 ( asterisk ) and medular spaces surrounding the bone trabeculae . 
 hematoxylin - eosin at 6 days after infection the connective tissue was not organized with a central area 
 still occupied by blood clot and predominant polymorphonuclear ( pmn ) infiltrate near 
 to the bottom of the socket . no newly formed bone trabeculae were observed , and 
 resorption of alveolar walls was seen , mainly in the buccal wall ( figures 4a and 4b ) . fifteen days after infection , the connective tissue started to 
 present signs of organization , but pmn infiltrate and blood clot were still observed , 
 beyond buccal cortical plate resorption . newly formed bone trabeculae were not 
 evident in this period ( figures 4c and 4d ) . at day 28 after infection , the connective 
 tissue showed organization , but focal areas of pmn infiltrate and blood clot were 
 observed , besides buccal cortical plate resorption . isolated focuses of thin newly 
 formed bone trabeculae in apical third were observed in some specimens ( figures 4e and 4f ) . experimentally induced alveolitis result in delayed alveolar healing . histological longitudinal specimens of group ii : 6 days postoperative ( a and b ) 
 showing inflammatory infiltrate with an exuberant presence of bacteria ( ii ) 
 surrounded by connective tissue ( ct ) occupying the cervical portion of socket 
 ( a ) ; neutrophilic infiltrate predominant ( red arrows ) , osteoclasts ( blue 
 arrows ) resorbing buccal cortical plate in median portion of socket ( b ) ; 15 
 days postoperative ( c and d ) showing inflammatory infiltrate ( ii ) and blood 
 clot ( bc ) in ( c ) ; buccal cortical plate resorption ( blue arrows ) surrounded by 
 connective tissue ( ct ) in ( d ) ; 28 days postoperative ( e and f ) displaying 
 buccal cortical plate resorption ( blue arrows ) , persistent inflammatory 
 infiltrate and blood clot ( bc ) remains in median third of socket ( e ) ; modest 
 bone trabeculae ( asterisk ) attached to apical cortical plate ( c ) in apical 
 third of socket ( f ) . hematoxylin - eosin the bacterial species present in the inoculation material were capnocytophaga 
 ochracea , fusobacterium nucleatum ss nucleatum , prevotella melaninogenica , 
 streptococcus anginosus , treponema socranskii and streptococcus 
 sanguis ( table 1 ) . the serum levels of c reactive protein ( crp ) were evaluated at 0 , 3 , 6 , 15 and 28 
 days in both control ( non - infected ) and infected rats . the infected rats showed 
 higher levels of serum crp when compared to non - infected animals . at day 3 after 
 infection the infected rats presented the highest serum levels of crp , followed by a 
 progressive decrease from 6 to 28 days after infection , but crp levels remained still 
 higher in infected compared to non - infected rats ( figure 2a ) . increased serum crp and delayed alveolar healing in experimental alveolitis 
 rats . ( b to f ) histometric results : bone , 
 connective tissue , inflammatory infiltrate , blood clot and empty space density , 
 presented as means and standard deviations by group , in each period . data were 
 analyzed by groups using student s t test or mann- whitney rank sum test and by 
 periods using one - way anova or kruskal - wallis test and tukey s or dunn s test 
 for multiple comparisons . at 6 days post - infection , the connective tissue was organized with proliferation of 
 blood vessels around a central area still occupied by blood clot . tissue organization 
 allowed observation of a small number of thin newly formed bone trabeculae near of 
 the alveolar walls and resorptive lacunae , mainly in the buccal wall ( figures 3a and 3b ) . fifteen days after infection , the connective tissue was well 
 organized with a smaller number of blood vessels . the newly formed bone trabeculae 
 were still thin , but numerous , formed mainly from the lingual wall towards the 
 central area of the socket . focal areas of resorption are also observed at this 
 period ( figures 3c and 3d ) . when analyzed 28 days after infection , the connective tissue 
 was well organized with a smaller number of blood vessels . the newly formed bone 
 trabeculae were thick and numerous , with defined medullar spaces occupying almost all 
 the surface of the median third , including the central portion of the socket ( figures 3e and 3f ) . histological 
 longitudinal specimens of group i : 6 days postoperative ( a and b ) showing blood 
 clot ( bc ) and connective tissue ( ct ) filling the cervical portion of socket 
 ( a ) ; and buccal cortical plate resorption ( blue arrows ) in ( b ) ; 15 days 
 postoperative ( c and d ) showing rich vascularized connective tissue ( ct ) , bone 
 ( asterisk ) and blood clot ( bc ) in ( c ) ; new bone formation ( asterisk ) , buccal 
 cortical plate resorption ( blue arrows ) surrounded by connective tissue ( ct ) in 
 ( d ) ; 28 days postoperative ( e and f ) displaying thick bone trabeculae 
 ( asterisk ) and medular spaces surrounding the bone trabeculae . hematoxylin - eosin at 6 days after infection the connective tissue was not organized with a central area 
 still occupied by blood clot and predominant polymorphonuclear ( pmn ) infiltrate near 
 to the bottom of the socket . no newly formed bone trabeculae were observed , and 
 resorption of alveolar walls was seen , mainly in the buccal wall ( figures 4a and 4b ) . fifteen days after infection , the connective tissue started to 
 present signs of organization , but pmn infiltrate and blood clot were still observed , 
 beyond buccal cortical plate resorption . newly formed bone trabeculae were not 
 evident in this period ( figures 4c and 4d ) . at day 28 after infection , the connective 
 tissue showed organization , but focal areas of pmn infiltrate and blood clot were 
 observed , besides buccal cortical plate resorption . isolated focuses of thin newly 
 formed bone trabeculae in apical third were observed in some specimens ( figures 4e and 4f ) . experimentally induced alveolitis result in delayed alveolar healing . histological longitudinal specimens of group ii : 6 days postoperative ( a and b ) 
 showing inflammatory infiltrate with an exuberant presence of bacteria ( ii ) 
 surrounded by connective tissue ( ct ) occupying the cervical portion of socket 
 ( a ) ; neutrophilic infiltrate predominant ( red arrows ) , osteoclasts ( blue 
 arrows ) resorbing buccal cortical plate in median portion of socket ( b ) ; 15 
 days postoperative ( c and d ) showing inflammatory infiltrate ( ii ) and blood 
 clot ( bc ) in ( c ) ; buccal cortical plate resorption ( blue arrows ) surrounded by 
 connective tissue ( ct ) in ( d ) ; 28 days postoperative ( e and f ) displaying 
 buccal cortical plate resorption ( blue arrows ) , persistent inflammatory 
 infiltrate and blood clot ( bc ) remains in median third of socket ( e ) ; modest 
 bone trabeculae ( asterisk ) attached to apical cortical plate ( c ) in apical 
 third of socket ( f ) . regarding the use of rat socket , the method presented in this study was based on a 
 previous work that originated a 
 large number of studies . in this experimental model , even considering the differences 
 concerning to the animal resistance and chronology of alveolar healing , it may simulates 
 situations that could occur in humans . the histometric analysis of different 
 histological variables of alveolar healing in infected and non - infected alveolus is 
 important to establish possible relations among variables in both situations . the process of cellular repair occurs by secondary intention and is a fibroproliferative 
 response , mediated by growth factors and cytokines , which aims to restore tissue to its 
 original status . it is a complex 
 process that involves a sequence of events , has an onset marked by inflammation in 
 response to an initial injury to the tissue . the strength of the repair process is 
 represented by cellular differentiation and proliferation mediated by growth factors and 
 cytokines that act at different stages , among which include : pdgf , fgf , tgf- , tnf , 
 il-1 ; vegf . it is known that several 
 mechanisms are involved in the formation of mature bone tissue , and this process depends 
 on the formation of an initial blood clot stage . its chronology can be divided into four 
 stages after the formation and stabilization of the blood clot . the phase of cell 
 proliferation , which starts with vascular events and cellular inflammation , is 
 responsible for clot formation and development of tissue from the replacement of 
 granulation tissue , where many cells and fibroblasts derived from the periodontal 
 ligament and bone marrow differentiate and proliferate . in this phase , the activity of 
 fibroblasts is intense and they synthesize the collagen fibers and amorphous substance 
 that are essential to connective tissue maturation , a phase in which there is a 
 reduction of the number of cells and vessels . after begins the formation of organic 
 matrix by osteoblasts followed by matrix mineralization and formation of bone trabeculae 
 to the corresponding stage of differentiation and bone mineralization . bone tissue formation is dependent on 
 the activation and differentiation of osteoblasts , leading to the production of 
 different proteins ( collagenous and noncollagenous ) , and enzymes such as alkaline 
 phosphatase , which will be responsible for the mineralization of bone tissue 
 formation . in the present study , wistar rats ( rattus novergicus albinus ) subjected 
 to socket inoculation of a suppurative secretion including capnocytophaga 
 ochracea , fusobacterium nucleatum ss nucleatum , prevotella melaninogenica , 
 streptococcus anginosus , treponema socranskii and streptococcus 
 sanguis developed suppurative alveolitis , characterized by expression of 
 high levels of crp , clinical signs of suppurative infection and delayed alveolar 
 healing . the aforementioned bacteria were detected by checkerboard dna - dna 
 hybridization in the 
 suppurative secretion from donor rats used to the socket inoculation which resulted in 
 experimental alveolitis . these microorganisms were detected among a panel of 39 
 different bacterial species commonly present in the oral cavity ( table 1 ) . several of these species , specially the gram - negative 
 anaerobes have been associated with oral infections , such as periodontal diseases , 
 endodontic lesions and pericoronitis . ( 1978 ) showed a possible 
 relationship between anaerobic bacteria ( predominant in pericoronitis lesions ) and 
 alveolitis , demonstrating fibrinolytic activity in cultures of treponema 
 denticola , present in periodontal disease . melo jnior ( 2002 ) detected some 
 streptococci species , enterococcus , bacillus corineforme , 
 proteus vulgaris , pseudomona aeruginosa , citrobacter freundii and 
 escherichia coli in alveolar biological content in acutely infected 
 sockets of rats . several studies , including the present one , have shown that material 
 obtained from sites of pericoronitis teems with spirochetes and fusobacteria .. their presence in pericoronitis would be consistent 
 with the high incidence ( up 88% ) of alveolitis following extractions associated with 
 this inflammatory process . therefore , periodontopathogens 
 inoculated into the socket could simulate the pattern of disturbing presented in 
 clinical situations of alveolitis , based on microbial theories . however , it is important to state that other 
 microorganisms could be present in the inoculation material used in this study , which 
 were not investigated by the applied diagnostic test . some were related to other 
 alveolar infection studies , such as bacteriodes fragilis , enterococcus , bacillus 
 corineforme , proteus vulgaris , pseudomonas aeruginosa , citrobacter freundii , 
 escherichia coli , staphilococcus and other 
 streptococci . our findings demonstrate that the inoculation of suppurative secretion containing 
 gram - negative anaerobes and gram - positive facultative associated with pericoronitis and 
 periodontal disease in humans results in 100% of effectiveness of bacterial colonization 
 of the socket , and leads to the development of experimental suppurative alveolitis . in 
 fact , the experimental infection was really effective and the high levels of serum crp 
 were found after infection . similarly , high levels of crp were found during the course 
 of experimental periodontal disease in rats , establishing crp as interesting systemic 
 mediator of disseminated infection . 
 at present , no study has evaluated systemic parameters after induced alveolitis in 
 animals or clinical trials , such as crp serum levels . the results of the present study 
 illustrate the systemic dissemination of acutely infection that can possibly evolve to 
 bacteremia and other systemic infections in clinical situations . indeed , acutely 
 infected sockets are sometimes described as being associated with parameters of systemic 
 infection , such as fever . due to intense inflammatory reaction induced by the infection , the reparative process is 
 delayed , and furthermore is preceded by an extensive osteoclastic activity , which 
 sometimes causes sequester formation . at different times after the extraction , 
 granulation tissue starts growing into the alveolus through the perforations of the 
 lamina dura . the alveolar wound is gradually filled up from the bottom with granulation 
 tissue , and at the same time the reepithelization starts . after the socket has been 
 filled with granulation tissue and covered by epithelium , healing takes its normal 
 course . therefore , in spite of 
 pain , odor and other symptoms , acutely infected sockets go on a healing process , though 
 it is significantly delayed in comparison to healthy sockets . the histometric analysis showed a uniform bone formation in group i sockets , being 
 significant amongst themselves ( figure 2b ) . there 
 was correlation between the increase of bone tissue density and blood clot reduction 
 from 6 to 28 days , and significant connective tissue density reduction from 15 to 28 
 days correlated with inflammatory infiltrate density reduction ( table 2 ) . lower 
 increase of bone density among periods was also observed ( figure 2b ) . there was positive correlation between bone density and 
 connective tissue increase correlated with inflammatory infiltrate and blood clot 
 density reduction ( table 2 ) , showing slower 
 wound healing in this group . correlation analysis among the histometric parameters throughout the alveolar 
 healing in non - infected and infected rat sockets results of spearman 's correlation test ( rs ) and p value of variables in group i 
 and group ii . it may be concluded that this model mimics the characteristics of suppurative alveolitis 
 ( acutely infected socket ) , including pus formation at socket bottom , gingival edema , 
 similar bacteria involved , systemic involvement and disturbed alveolar healing . group i 
 ( non - infected ) showed higher bone density of at all studied periods , than group ii 
 ( infected ) , confirming the alveolar healing disturbing in infected sockets , which could 
 simulate clinical situations of dry socket . group ii presented higher crp levels at all 
 studied periods compared to group i , proving the potential of experimentally induced 
 infection . this model seems to be useful to study preventive or curative modalities of 
 alveolitis and other features involved in infected and non - infected alveolar wound 
 healing .
the pathogenesis of alveolitis is not well known and therefore experimental 
 situations that mimic some features of this disease should be developed.objectivein this study , the evolution of the experimentally induced infection in rat 
 sockets is characterized , which leads to clinical signs of suppurative alveolitis 
 with remarkable wound healing disturbs.material and methodsnon - infected ( group i ) and experimentally infected sockets in rattus 
 novergicus ( group ii ) were histometrically evaluated regarding the 
 kinetics of alveolar healing . 
 in addition , the characterization of the present 
 bacteria in inoculation material and the serum levels of c - reactive protein ( crp ) 
 were performed . 
 the detected species were capnocytophaga ochracea , 
 fusobacterium nucleatum ss nucleatum , prevotella melaninogenica , streptococcus 
 anginosus , treponema socranskii and streptococcus 
 sanguis.resultsall experimentally infected rats developed suppurative alveolitis , showing higher 
 levels of crp in comparison to those non - infected ones . 
 furthermore , infected rats 
 presented a significant delayed wound healing as measured by the histometric 
 analysis ( higher persistent polymorphonuclear infiltrate and lower density of 
 newly formed bone).conclusionthese findings indicate that rat sockets with experimentally induced infection 
 produced higher levels of serum crp , showing the potential of disseminated 
 infection and a disturb in the alveolar repair process in an interesting 
 experimental model for alveolitis studies .