Fluoridated bioceramics

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. 

There are multiple applications of fluoridated bioceramics, essentially as bone and tooth substitutes (Table 1), involving bulk ceramics, glasses, composite materials and coatings for medical devices and surface treatments. In some cases, fluoride ions can leach out of the material inducing a direct biological effect in a soluble form. However, considering the affinity of fluoride ions for apatite... 

Table 1. Applications of fluoridated bioceramics and related biomaterials...

The biological properties of fluoridated bioceramics depend on numerous factors besides the amount of fluoride (porosity, surface roughness, surface properties, degradation process) and it is often difficult to discern the specific role of fluoride. It seems useful to begin by summarising the biological properties of fluoride ions in solution. 

Overview of bioceramics and related biomaterials incorporating fluoride ions 281... 

OVERVIEW OF BIOCERAMICS AND RELATED BIOMATERIALS INCORPORATING FLUORIDE IONS... 

The fatigue behaviour of pure hydroxy- and fluorhydroxyapatite-sintered bioceramics has been studied in ambient air, distilled water and simulated human saliva [86]. The authors observed that, as a general trend, HA ceramics exhibited a lower resistance to fatigue than fluoridated ones. Another work [87] showed that the hardness remained essentially unchanged until 80% of OH were replaced with F , whereas it noticeably increased with greater fluoride contents. The elastic... 

An example of alternative processing methods is given by the use of a hydro-thermal treatment at moderate temperatures (100-500°C), positioning the sample either above the water or in total immersion (possibly in the presence of sodium fluoride) of the powder mixture, which was proposed [146] in view of the preparation of both stoichiometric and nonstoichiometiic apatite bioceramics, eventually followed by thermal treatment. 

A.J.S. Peaker, K.A. Hing, I.R. Gibson, L. DiSilvio, S.M. Best, L.L. Hench, W. Bonfield, Activity of human osteoblast-like cells on bioglass, hydroxyapatite and fluoride-sus-btituted hydroxyapatite. Bioceramics 11 (1998) 285-288. 

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