title: Osteoinductive potential and bone-bonding ability of ProRoot MTA, MTA Plus and Biodentine in rabbit intramedullary model: Microchemical characterization and histological analysis.
abstract: To study the in vivo osteoinductive potential, bone-bonding ability (bioactivity) and bone biomineralization of current hydraulic calcium silicate cements used as graft materials and placed in contact with medullary bone.
  
  
  
  ProRoot MTA, MTA Plus and Biodentine were used to fill surgical bone defects (2-mm diameter through the entire cortical thickness to reach the medullary bone) in the tibia of mature male rabbits. Tibiae were retrieved after 30days and submitted to histological analysis and microchemical characterization using Optical Microscopy (OM) and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis (ESEM-EDX). Bone neoformation and histomorphometric evaluations, degree of mineralization (by Ca/P, Ca/N and P/N ratios) and the diffusion of material elements were studied.
  
  
  
  Bone neoformation was observed in response to all materials. No sign of necrosis were found on the walls of the pre-existing cortical bone. No osteoclasts and no formation of fibrous tissue were evident. Sign of angiogenesis were present. EDX (element content, line profile and element mapping) showed the increase in Ca and P and decrease in C, S and N from the mature bone towards the mineralizing interface. Ca/P, Ca/N and P/N ratios showed differences in the degree of mineralization/maturation stage of bone. MTA Plus and ProRoot MTA exhibited close contact with the pre-existing bone and good bone-bonding with neoformed bone juxtaposed on the medullary side of the materials without interposed connective tissue or resorption lacunae or gaps. The materials showed a dense appearance with 100% of residual materials and no colonization by fluids and cells. No migration of Bi or Al material elements to the newly formed bone was found. Biodentine showed newly formed trabecular bone with marrow spaces and sparse traces of residual material (≈9%).
  
  
  
  The in vivo osteoinductive properties with dynamic biomineralization processes around these calcium silicate materials extruded in medullary bone in appropriate animal model have been demonstrated by ESEM-EDX in association with OM. Good biocompatibility was evident as only slight inflammatory infiltrate and no sign of necrosis at the interface with the pre-existing bone were found. MTA Plus and ProRoot MTA exhibited bioactive potential as they can bond to bone directly without interposed connective tissue. Biodentine was replaced by newly formed bone.
  
  
  
  The results of the study demonstrate the capacity of calcium silicate cements to allow osteoid matrix deposition by activated osteoblasts and favour its biomineralization, and to achieve a direct bond between the (bioactive) materials surface and the mineralized bone matrix.
authors.affiliation: Laboratory of Biomaterials and Oral Pathology, Dental School, Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy; Endodontic Clinical Section, Dental School, Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy. Electronic address: mgiovanna.gandolfi@unibo.it.
authors.forename: M G
authors.initials: MG
authors.lastname: Gandolfi
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti Scalo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Iezzi
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti Scalo, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Piattelli
authors.affiliation: Endodontic Clinical Section, Dental School, Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Prati
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti Scalo, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Scarano
mesh_terms: D017607:Aluminum Compounds; D000818:Animals; D001846:Bone Development; D017610:Calcium Compounds; D004338:Drug Combinations; D008422:Materials Testing; D010087:Oxides; D000068437:Pemetrexed; D011817:Rabbits; D012387:Root Canal Filling Materials; D017640:Silicates
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; D000068437:Pemetrexed; C506393:tricalcium silicate
keywords: Biodentine; Bone-bonding (bioactivity); Ca/N ratio; Ca/P ratio; Hydraulic calcium silicate cements; MTA Plus; Mineralization degree; Osteoinduction; P/N ratio; ProRoot MTA