In vitro remineralization of enamel by polymeric amorphous calcium phosphate composite: Quantitative microradiographic study

Abstract

Objective: This study explores the efficacy of an experimental orthodontic amorphous calcium phosphate (ACP) composite to remineralize in vitro subsurface enamel lesions microradiographically similar to those seen in early caries. Methods:Lesions were artificially created in extracted human molars. Single tooth sections a minimum of 120 μm thick were cut and individually placed in holders exposing only the carious enamel surface. The exposed surfaces were either left untreated (control) or coated with a 1 mm thick layer of the experimental ACP composite (mass fraction 40 % zirconiahybridized ACP and 60 % photo-activated resin), or a commercial fluoride-releasing orthodontic cement. The composite-coated sections were then photo-cured and microradiographic images were taken of all three groups of specimens before the treatment. Specimens were then cyclically immersed in demineralizing and remineralizing solutions for one month at 37 °C to simulate the pH changes occurring in the oral environment. Microradiographs of all specimens were taken before and after treatment. Results:Quantitative digital image analysis of matched areas from the contact microradiographs taken before and after treatment indicated higher mineral recovery with ACP composites compared to the commercial orthodontic F-releasing cement (14.4 % vs. 4.3 %, respectively), while the control specimens showed an average of 55.4 % further demineralization.Significance: Experimental ACP composite efficiently established mineral ion transfer throughout the body of the lesions and restored the mineral lost due to acid attack. It can be considered a useful adjuvant for the control of caries in orthodontic applications.

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Until recently, it was generally agreed that if there was sufficient time between the intake of foods (generally, 2-3 h) plus a damage was very limited, teeth could repair themselves by the ''passive mineralization '' process (LeGeros 1999). Data on increased remineralization of dental enamel by CaPO 4 -containing compounds (Cochrane et al 2008;Langhorst et al 2009;Weir et al 2012) are in support of this hypothesis.…”

New model to explain tooth wear with implications for microwear formation and diet reconstruction

“…Individual hydroxyapatite crystallites are glued together by a thin protein layer (no more than 2 nm thick) that holds the crystallites on the surface with its elastic polymeric backbone (24,25). Crystallites can only change position by breaking the protein layer; the crystallites do not link back up unless new proteins are formed, which is possible but may require that teeth be soaked in water or saliva for hours (26)(27)(28), during which Brownian motion cannot allow the nanometer-scale debris to sit still nearby. Herbivorous mammals can chew thousands or even tens of thousands of cycles per day, which should lead to debris removal and act against reattachment of crystallites and regrowth of enamel.…”

Effect of bleaching agents containing fluoride or calcium on enamel microhardness, roughness and permeability

“…Fluoride has proven to be effective in promoting remineralization and inhibiting enamel demineralization 8 . Fluoride is not the only way to ensure this remineralization, as calcium compounds also exhibit efficient recovery of lost mineral content 18 . With this objective, fluoride and calcium have been added to bleaching gels as alternatives to reduce these adverse effects caused by enamel bleaching 19 .…”