title: Effect of 10% formalin on radiographic optical density of bone specimens.
abstract: OBJECTIVE
  The aim of this work was to determine whether the fixation process with 10% formalin modifies the radiographic optical density of bone.
  
  
  METHODS
  Eight rabbit tibiae were placed in separate containers with one of the following fixative solutions: 10% formalin (n = 3), 10% phosphate-buffered formalin (n = 3) or 10% calcium carbonate-buffered formalin (n = 2). Radiographs were obtained at 5 different times: before fixation (time zero), then 1 day, 15 days, 30 days and 90 days following immersion in the fixative solution. Radiographs were scanned and optical density was determined using ImageTool software.
  
  
  RESULTS
  There was no significant difference in radiographic optical density among the specimens fixed in 10% formalin (146.60+/-32.44), 10% phosphate-buffered formalin (149.84+/-32.43) and 10% calcium carbonate-buffered formalin (146.61+/-35.92). Regardless of buffering, optical density at time zero was significantly higher than that at 15 days, 30 days and 90 days. However, while optical density at 1 day was significantly higher than that at 30 days and 90 days, it did not differ from that at 15 days. There was also no significant difference in density between 30 days and 90 days (ANOVA, Tukey, at 5% level of significance).
  
  
  CONCLUSIONS
  The radiographic optical density of specimens stored in 10% formalin diminishes with time, irrespective of buffering, which suggests the occurrence of bone demineralization.
authors.affiliation: Stomatology Department, Pontifical Catholic University of Rio Grande do Sul, Hospital São Lucas PUCRS, Porto Alegre, RS 90610000, Brazil.
authors.forename: A A
authors.initials: AA
authors.lastname: Fonseca
authors.forename: K
authors.initials: K
authors.lastname: Cherubini
authors.forename: E B
authors.initials: EB
authors.lastname: Veeck
authors.forename: R S
authors.initials: RS
authors.lastname: Ladeira
authors.forename: L P
authors.initials: LP
authors.lastname: Carapeto
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D002021:Buffers; D002119:Calcium Carbonate / Q000008:administration & dosage; D003720:Densitometry; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000187:drug effects; D004838:Epiphyses / Q000000981:diagnostic imaging / Q000187:drug effects; D005404:Fixatives / Q000494:pharmacology*; D005557:Formaldehyde / Q000008:administration & dosage / Q000494:pharmacology*; D010710:Phosphates / Q000008:administration & dosage; D011817:Rabbits; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging* / Q000187:drug effects; D013997:Time Factors; D016707:Tissue Fixation
chemical_list: D002021:Buffers; D005404:Fixatives; D010710:Phosphates; D005557:Formaldehyde; D002119:Calcium Carbonate; C018279:sodium phosphate