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Journal of Oral Science & Rehabilitation No. 3, 2016

Journal of Oral Science & Rehabilitation 40 Volume 2 | Issue 3/2016 P u l p r e s p o n s e a f t e r c a p p i n g w i t h P D G F These preliminary findings indicate that PDGF- BB does not elicit pulpalinflammatoryresponse, nor induce extensive dentin matrix deposition, suggesting that this growth factor could be safelyapplied in human pulp capping.According to previous human models that proved the effi- cacy of growth factors in noninflamed exposed pulp,15 this study was performed on healthy and freshlyexposed pulps. However, Rutherford and Gudemonstratedthefailureofatreatmentstrat- egy utilizing BMP-7 proteins for management of inflamed pulpalwounds.25 Despitethis, it maybe supposed that the therapeutic activity of PDGF- BB is mainly due to the promotion of tissue re- generation than to the resolution of the inflam- matory process. Further studies should thus investigate the efficacy of PDGF in promoting newly formed dentin bridges in inflamed pulps and compare this treatment with a biological agent to the gold standard pulp capping agent (MTA).9 The role and mechanism of action of PDGF in healing of damaged dental pulp and dentin bridge formation are not completely un- derstood. PDGF plays a role in cell chemotaxis, proliferation and differentiation at each stage of wound healing.19, 20 In periodontics, clinical stud- ies have been conducted since PDGF demon- strated an important role in regeneration of ce- mentum, periodontal ligament and alveolar bone.26 In a clinical trial, Nevins et al. evaluated the healing and regeneration of infrabony peri- odontal defects treated with highly purified re- combinant human PDGF-BB and a ʹ-tricalcium phosphate scaffold and demonstrated the effi- cacy of PDGF-BB in accelerating and improving periodontal soft-tissue healing and bone regen- eration.27 In addition, clinicaltrials have suggest- ed the promotion of bone turnover during the repair process of tooth-supporting osseous de- fects.28 A histochemical and immunohistochemical study has evaluated the effects of three PDGF dimers (PDGF-AA, -BB and -AB) on odontoblast differentiation of dental pulp cells.23 The au- thors observed dentin formation during the repairprocess in damageddentalpulp.Theyalso observed that PDGF-AB and -BB stimulated the differentiation of odontoblast cells, increasing the number of mature odontoblast cells. In con- trast, PDGF-AA exerted inhibitory effects on odontoblast differentiation.23 These findings suggest a role of PDGF-BB in dentinogenesis in the dental pulp and in differentiation of odon- toblasts during repair processes after injury to the mature pulp. The importance of PDGF in the dental pulp regenerative process is due to the role that this growth factor plays during em- bryonic development. PDGFs and platelet- derived growth factor receptors (PDGFRs) play a role in gastrulation,29 development ofthe cra- nial and cardiac neural crests,30 and formation ofthe palate.31 Studies have shownthat PDGF-ʸ and PDGFR-ʸ are expressed in developing mouse molars, regulate epithelial–mesenchy- mal interaction during mammalian tooth mor- phogenesis, and have a critical function in dif- ferentiation of dental pulp cells and in the development of dental cusps.31, 32 Conclusion Within its limitations, this study suggests that PDGF-BB appears to be a safe pulp capping agent. PDGF-BB may stimulate dentinogenesis, promoting differentiation of odontoblasts after dental pulp injury. It appears that differentiated odontoblasts produce tubular and compact re- parative dentin, without tunnel defects, and do not obliterate the pulp chamber. Competing interests The authorsdeclarethattheyhave nocompeting interests.

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