title: Ultrastructure of smear layer-covered intraradicular dentin after irrigation with BioPure MTAD.
abstract: The structure of mechanically instrumented intraradicular dentin after irrigation with NaOCl as the initial rinse and BioPure MTAD as the final rinse were examined from the coronal, middle, and apical parts of root canal walls using transmission electron microscopy. Sterile distilled water and EDTA as final rinses were employed as the respective positive and negative controls under the same experimental conditions. There were 2 to 5 mum thick smear layers produced on mechanically instrumented root canal walls that were completely removed by EDTA and BioPure MTAD under agitation. Both irrigants created a zone of demineralized collagen matrices in eroded dentin and around the dentinal tubules, with the mildly acidic BioPure MTAD being more aggressive than EDTA. These demineralized dentin zones create the opportunity for dentin hybridization by infiltration of hydrophilic adhesives/sealers. However, the potential consequences of compaction of hydrophobic sealers against air-dried, collapsed collagen matrices, and hydrolytic degradation of incompletely infiltrated matrices remain unresolved.
authors.affiliation: Pediatric Dentistry and Orthodontics, The University of Hong Kong, Pokfulam, Hong Kong SAR, China. kfctay@netvigator.com
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Loushine
authors.forename: Michael D
authors.initials: MD
authors.lastname: Doyle
authors.forename: W Trent
authors.initials: WT
authors.lastname: Gillespie
authors.forename: R Norman
authors.initials: RN
authors.lastname: Weller
authors.forename: Nigel M
authors.initials: NM
authors.lastname: King
mesh_terms: D001641:Bicuspid; D019343:Citric Acid / Q000494:pharmacology*; D003094:Collagen / Q000187:drug effects; D001840:Dental Bonding; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000648:ultrastructure*; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure; D003806:Dentin Permeability / Q000187:drug effects; D004318:Doxycycline / Q000494:pharmacology*; D004492:Edetic Acid; D006801:Humans; D046529:Microscopy, Electron, Transmission; D011136:Polysorbates / Q000494:pharmacology*; D012388:Root Canal Irrigants / Q000494:pharmacology*; D018915:Root Canal Preparation; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000494:pharmacology; D017001:Tooth Demineralization
chemical_list: C475043:MTAD (intracanal irrigant); D011136:Polysorbates; D012388:Root Canal Irrigants; D019343:Citric Acid; D003094:Collagen; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D004318:Doxycycline