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Journal of Oral Science & Rehabilitation 36 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 mentwere selectedfromtwo patients (onetooth from each patient) with the following inclusion criteria: (a) no systemic diseases or metabolic bone disorders; (b) not pregnant; and (c) no his- tory of malignancy, radiotherapy or chemother- apy for a malignancy in the past five years. Fur- thermore, in order to standardize the age-related prognostic factor, subjects aged between 18 and 39 were enrolled.24 The exper- imentalteethwere clinicallyand radiographical- ly examined and presented superficial enamel decay; however, the teeth were asymptomatic, without periapical lesions and responded posi- tively to the cold stimulus test performed by applying HYGENIC ENDO-ICE F frozen gas (Coltène/Whaledent, Mahwah, N.J., U.S.)for5 s to the buccal surfaces. P r o c e d u r e s e m p l o y e d Forty days before the extraction, after local and intraligament anesthesiawith lidocaine contain- ing 1:80,000 epinephrine to control pain and bleeding from the exposed pulp, the selected molars were isolated with a rubber dam and dis- infected with topical antiseptic. Class I cavities ontheocclusalsurfacesoftheexperimentalteeth were prepared by means of diamond burs (1 mm in diameter) andthe pulpswere exposed. On one tooth(SiteA),aperforationof1mm×1mm(eval- uated at the level of the pulp chamber) was per- formed; and on the other tooth (Site B), the per- foration was 3 mm × 3 mm. After rising with sterile water to remove the debris, establishing hemostasis with a sterile cotton pellet soaked in saline solution and drying with a sterile cotton pellet, the pulp was cappedwith sterile cotton embedded in a PDGF- BB solution and covered with zinc oxide cement (CAVIT, 3M ESPE, Seefeld, Germany). During the days after capping, the patients completed a questionnaire on pain occurrence. After 40 days, the experimental teeth were tested for pulp vitality by applying HYGENIC ENDO-ICE F and were carefully extracted without root separation or crown fracture. H i s t o l o g i c a l a n a l y s i s Immediatelyafter extraction, the teeth were im- mersion fixed in a 10% formalin/0.1 M phos- phate-buffered saline (pH 7.4) for 24 h at room temperature. The dental crown was separated from the roots using a round bur in a low-speed handpiece and then decalcified for 30 days in a solution containing formic acid (625 cm3 in 625 cm3 of distilled/purified water) and sodium citrate (250 g in 125 cm3 ofdistilled/purifiedwa- ter). Decalcification of dental tissue was verified byradiograph.Afterrinsing underrunningwater for48 h,the samplewas routinelydehydrated in increasing concentrations ofethanol(from 50to 100%), immersed in xylol for 12 h and then em- bedded in paraffin. Serial buccolingual sections were obtained from 4 to 5 mm and then hydrat- ed in xyloland decreasing concentrations ofeth- anol (from 100 to 70%) and finally immersed in distilled water. Sections were stained with he- matoxylin and eosin (H&E)to evaluatethetissue morphology and with Masson’s trichrome stain to distinguish the connective matrix from cells. The sections were viewed and photographed under a light microscope (Eclipse E600, Nikon, Tokyo, Japan) equipped with a calibrated digital camera (DXM 1200, Nikon). Multiple centralsec- tionswereusedtoperformanoverallassessment foreachtooth.The hard-tissue bridge formation (continuity, morphology, localization and thick- ness) and the dental pulp reaction (inflammato- rycell response andtissue disorganization)were described. Results Both patients (Aand B)who completedthe study were female, nonsmokers, and 23 and 26 years old, respectively. A total of two teeth were ana- lyzed. After the experimental pulp capping, the patients did not report anysymptoms oranalge- sic intake. At the extraction appointment, both teethwerevitaland both cavities stillclosedwith CAVIT. At the histological evaluation, the thick- ness (mm) of the newly formed hard tissue was measured at three different points ofthe bridge: alongside the dentinal wall (on the mesial side and distal side) and in the center. Table 1 shows the mean thickness of the newly formed bridge. S i t e A In allofthe sections,the drill-created cavitycon- tained debris and bacteria along all of the cavity walls (Fig. 1). An incomplete dentin bridge lined the pulp exposure site and was formed by well-organized tubular reparative dentin, with a clearpredentin layerand odontoblastic-like cells (Fig. 2). No extensive dentin matrix deposition