title: Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.
abstract: Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.
authors.affiliation: Department of Dental Research & Implantology, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Timarpur, Delhi, 110054, India, manukrishnanin@yahoo.co.in.
authors.forename: Manu
authors.initials: M
authors.lastname: Krishnan
authors.forename: Brijesh
authors.initials: B
authors.lastname: Tiwari
authors.forename: Saraswathy
authors.initials: S
authors.lastname: Seema
authors.forename: Namitha
authors.initials: N
authors.lastname: Kalra
authors.forename: Papiya
authors.initials: P
authors.lastname: Biswas
authors.forename: Kotikalapudi
authors.initials: K
authors.lastname: Rajeswari
authors.forename: Madireddy Buchi
authors.initials: MB
authors.lastname: Suresh
authors.forename: Roy
authors.initials: R
authors.lastname: Johnson
authors.forename: Nitin M
authors.initials: NM
authors.lastname: Gokhale
authors.forename: Satish R
authors.initials: SR
authors.lastname: Iyer
authors.forename: Sanjay
authors.initials: S
authors.lastname: Londhe
authors.forename: Vimal
authors.initials: V
authors.lastname: Arora
authors.forename: Rajendra P
authors.initials: RP
authors.lastname: Tripathi
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry / Q000494:pharmacology; D000537:Aluminum Oxide / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003764:Dental Materials / Q000138:chemical synthesis* / Q000494:pharmacology*; D004955:Esthetics, Dental; D057809:HEK293 Cells; D006244:Hardness; D006801:Humans; D017616:Magnesium Compounds / Q000737:chemistry / Q000494:pharmacology; D008277:Magnesium Oxide / Q000737:chemistry* / Q000494:pharmacology*; D008422:Materials Testing; D016910:Orthodontic Brackets; D012031:Refractometry; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D017607:Aluminum Compounds; D003764:Dental Materials; D017616:Magnesium Compounds; C111130:spinell; C110424:aluminum magnesium oxide; D008277:Magnesium Oxide; D000537:Aluminum Oxide