Dentine treatment

Hinoura, K., Moore, B. K. Phillips, R. W. (1986). Influence of dentin surface treatments on the bond strength of dentin-lining cements. Operative Dentistry, 11, 147-54. 

Although adsorbed carbonates on bone mineral and dentine can be easily removed by routine cleaning pre-treatment, the diagenetic fraction has proved more difficult and controversial. Attempts have been made to use sequential acid washing and density separation for bone, as described above, but, at present, the results are rather ambiguous. The carbonate fraction of dental enamel, however, has proved much more amenable, and significant progress... 

The relationship between the degradation of organic matrix and dentin lesion formation has been studied both in vitro and in situ. Several authors employed matrix destruction to assess the role of the matrix in de-and remineralization. For example, Apostolopoulos and Buonocore (1966) reported facilitated demineralization of dentin at pFl<5.5 after treatment with ethylene diamine. Inaba and coworkers (1996) found that removal of matrix from dentin lesions by hypochlorite promotes remineralization, consistent with a larger crystal surface available for mineral deposition after ashing (McCann and Fath, 1958). Flypochlorite-mediat-ed destruction also increases the permeability of mineralized dentin (Barbosa et ah, 1994). 

Inaba D, Ruben J, Takagi O and Arends J (1996) Effect of sodium hypochlorite treatment on remineralization of human root dentine in vitro. Caries Res 30, 218-224. 

Effect of matrix degradation on the rate of demineralization of incipient erosive lesions in root dentin. Specimens were subjected to daily alternating incubations with HAc pH 5.0 (V,Y) or pH 5.5 ( , ) and either collagenase (TM) or buffer (V,ni (n=5). Values represent mean SD. Levels of significance were calculated according to Student s t test. P<0,05, P<0,01 vs. buffer-treatment. 

In addition, peak VI (fig. 1) contained two compounds, one identified as lysinoalanine (table 1). Lysinoalanine is a well-known artefact of alkaline protein treatment but is supposed to be formed in dentin by the reaction between a collagen lysine- and a phosphoprotein phosphoserine residue (Fujimoto et al., 1981). Both compounds were not detected by HPLC after FMOC-derivatization, most likely because of fluorescence quenching inherent to the close vicinity of several FMOC groups attached to one molecule. Thus the unknown compound seems rather similar to lysinoalanine. We suggest the unknown compound is histidinoalanine, which is present in dentin (Fujimoto et al., 1982) and likely shows fluo-rence quenching in its FMOC derivate. 

In a parallel preliminary experiment, hypochlorite instead of colla-genase was employed for matrix degradation. After hypochlorite treatment, tubules in sound dentin beneath the lesions contained material positive for PAS- and Richardson s stains, which was not observed after the buffer- and collagenase treatments. The bacterial degradation of the organic matrix was, therefore, simulated enzymatically. 

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. 

The most common oral condition and dental emergency is dental caries, which is a destructive disease of the hard tissues of the teeth due to bacterial infection with Streptococcus mutans and other bacteria. It is characterized by destruction of enamel and dentine. Dental decay presents as opaque white areas of enamel with grey undertones and in more advanced cases, brownish discoloured cavitations. Dental caries is initially asymptomatic and pain does not occur until the decay impinges on the pulp, and an inflammation develops. Treatment of caries involves removal of the softened and infected hard tissues, sealing of exposed dentines and restoration of the lost tooth structure with porcelain, silver, amalgam, composite plastic, gold etc. 

Prior to the use of the adhesives, the dentin surface is etched with a conditioning solution which is usually an aqueous acidic solution of citric acid-ferric chloride, phosphoric acid, or even polyacrylic acid [192]. These solutions tend to demineralize the dentin and expose the collagen (organic fibers in the dentin) [193], and thereby result in higher bond strengths. The effects of various pre-conditioning treatments on the bond strength of 4-META to dentin have been discussed [194]. 

Dentin. Preliminary studies have been conducted to determine the feasibility of grafting onto dentin (53). With CAN as initiator, some modification of dentin occurred on treatment with methyl methacrylate. With other monomers, no increase in weight was found. Since dentin is the most highly mineralized collagenous substrate that has been studied, its lack of reactivity towards grafting is expected. 

The aim of this review is to look at some of the factors that can influence the outcome of in vitro studies into the de- and remineralisation of enamel and dentine. Intrinsic characteristics of artificial lesions, the effect of their environment, and the treatment regime to which they are subjected are all considered. 

The ability of tooth mineral itself to buffer pH, and hence restrict the cari-ogenic challenge from plaque acids, has been demonstrated in recent laboratory studies. Zaura et al. [60] showed that the pH at the bottom of in situ plaque, in grooves cut into different materials to simulate tooth fissures, decreased in the order polyacrylate > enamel > dentine after an in vitro glucose treatment, i.e. the inverse of the solubility. In chapter 3, Lynch describes his own in vitro work in which the presence of dentine adjacent to a block of enamel could act as a sacrificial source of Ca and Pi and inhibit enamel dissolution in solutions initially undersaturated with respect to both materials. 

FIG. 24 SECM images recorded over a slice of dentine after treatment of the surface with calcium oxalate. Images were recorded (A) with no pressure applied across the dentine slice and (B) with a fluid pressure of 2 kPa across the slice. The donor and receptor solutions each contains 10 mM K,Fe(CN), and 0.5 M KC1. (From Ref. 12.)... 

Fig. 31 Ablation depth per pulse d vs laser fluence F0 for the treatment of human enamel ( ) and human dentine (A).r=300 fs, A=615 nm, N=100. The straight lines are fits using a d ln(F0/Fth) dependence. Solid line human enamel dashed line human dentine [81]...

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