Microtensile bond strength to phosphoric acid-etched dentin treated with NaF, KF and CaF2

Purpose: Fluoride compounds have been reported to play a protective role in the host-derived enzymatic degradation of demineralized dentin matrices. The objective of this study was to evaluate the effect of fluoride pretreatment on the immediate and long-term microtensile bond strength (mu TBS) of resin-dentin interfaces. Materials and methods: Mid-coronal dentin surfaces of ninety-nine teeth were etched with 32%wt phosphoric acid and randomly assigned to pretreatment with NaF, KF or CaF2 solutions (6, 24 and 179 mM F content) for 30 s before the application of bonding agent (Scothbond Multi-Purpose, 3 M ESPE). No fluoride pretreatment and a commercially available bonding agent with KF (Excite F, Ivoclar Vivadent) were used as controls. After composite built-up, the specimens were sectioned into TBS test beams, stored in artificial saliva at 37 degrees C for 24 h, 6 or 12 months and tested. Fracture types were evaluated under scanning electron microscope. The data were analyzed with ANOVA and Scheffe post-hoc tests (alpha = 0.05). Pearson Chi-Square test was used to compare the distribution of failure types. Results: Fluoride compound, fluoride concentration and storage time showed significant effect on TBS (p 0.05), except CaF2 179 mM (p <0.05). According to Chi-square test, fracture types were also significantly influenced from the test factors (p <0.05). Conclusions: NaF and KF treatment after acid-etching step of adhesive bonding procedures do not adversely influence the initial or long-term bond strength to dentin, and can improve the maintenance of bond strength durability.Peer reviewe

Exostosin 1 is expressed in human odontoblasts

Objective: Dental pulp is soft connective tissue maintaining the vitality of the tooth, while odontoblasts form the dentin. Our earlier DNA microarray analysis revealed expression of putative tumour suppressor exostosin 1 (EXT-1) in odontoblasts. EXT-1 is essential for heparan sulphate synthesis, which may play a role in the dentin mineralization. Since the absence of the functional EXT-1 causes bone tumours, expression in odontoblasts is interesting. Our aim was to analyse further the EXT-1 expression in human tooth. Designs: DNA microarray and PCR techniques were used to study the EXT-1 expression in mature native human odontoblasts and pulp tissue as well as in newly-differentiated cultured odontoblast-like cells. Immunohistochemistry was performed to study EXT-1 protein in mature human teeth, teeth with incomplete root and developing teeth. Results: Markedly higher EXT-1 was observed in mature odontoblasts than in pulp at mRNA level with DNA microarray and PCR techniques. Immunohistochemistry of mature tooth revealed EXT-1 both in odontoblasts and the predentin but not in the dentin. EXT-1 was also observed in the odontoblasts of incomplete root, but the localization of the staining was different. In developing foetal tooth, staining was detected in ameloblasts and the basal lamina. Conclusions: The detection of EXT-1 in both mature and newly-differentiated cells indicates a role in the odontoblast function, and EXT-1 staining in the predentin indicates a function in the dentin formation. Detection of EXT-1 in developing teeth indicates a role in tooth development.Peer reviewe

Influence of polar solvents on permeability, stiffness and collagen dissociation of demineralized dentin

The purpose of this in vitro study was to evaluate and compare the effect of dimethyl sulfoxide (DMSO) or ethanol on the permeability, stiffness and collagen dissociation of demineralized dentin. Dentin cubes (2 x 2 x 2 mm) were demineralized in EDTA and incubated in DMSO or ethanol (0.01, 0.1, 1, 5, 10, 20, 50 and 100%) (n = 10/group) for 30s, followed by 100% HEMA incubation. Extracted HEMA was quantified. For elastic modulus (E), demineralized dentin beams (6 x 2 x 1 mm) were incubated in DMSO or ethanol (1, 10, 20, 50 and 100%) for 10, 30 or 60 min at 3-point bending. Additional demineralized dentin discs (1 mm) were incubated in DMSO (1, 10, 50 and 100%) for 10, 30 and 60 min and the optical clearing effect was observed. The data were analyzed using ANOVA and Tukey's test (alpha = 0.05) using SigmaPlot (Systat Software Inc., San Jose, CA). Compared to controls, HEMA uptake was significantly higher with all DMSO concentrations, and with 0.1% or higher ethanol concentrations (p <0.05). HEMA uptake in DMSO-incubated specimens (0.01, 5 and 10%) was significantly higher than with the ethanol incubation. Significant increase in elastic moduli was observed with 50-100% DMSO- and only with 100% ethanol after 10 min incubation. The optical clearing effect of 50-100% DMSO-incubated dentin disks was observed starting from 10 min. The pretreatment of dentin surfaces with low concentrations of DMSO resulted in significant improvement of the penetration of monomers to demineralized dentin matrices. Increase in penetration of monomers combined with a reversible stiffening of dentin collagenous matrix may explain the previously shown increase in durability of wet- or dry-bonded adhesive interfaces with DMSO treatment.Peer reviewe

Estimating molar-incisor-hypomineralization among 8-year-olds based on 15-year public oral health practice-based data

Background:A wide range in the prevalence of molar-incisor-hypomineralization (MIH) has been reported. Population-based studies are recommended. However, such studies are expensive and time-consuming. Objectives:To estimate the magnitude of MIH condition among 8-year-olds based on routine oral health examinations and to associate first permanent molar (FPM) affection with that of other permanent teeth over time. Materials and methods:This retrospective study, with cross-sectional and longitudinal components, was based on electronic oral health records; all 8-year-olds examined between 2002 and 2016 were included. Results:The average estimated prevalence of MIH was 8.3%; yearly range was 4.8-15.9%. The mean number of affected teeth was 1.4; 62% had one affected tooth. One-surface defects were the most frequent (66%). Asymmetric distribution of affected teeth was observed. In follow-up, 10.7%, 8.4%, and 11.2% had at least one affected permanent canine, premolar, or second permanent molar, respectively. The proportion of children with other MIH-affected permanent teeth was higher in the group with >= 2 MIH-affected teeth than in group with one affected FPM at the age of 8. Conclusions:The average prevalence of MIH was comparable to that reported elsewhere. The number of MIH-affected teeth at early mixed dentition predicts the affection of other permanent teeth over time, mainly that of permanent canines. Further screening of children with MIH is recommended to improve individually tailored early preventive and restorative dental care.Peer reviewe

Estimating molar-incisor-hypomineralization among 8-year-olds based on 15-year public oral health practice-based data

Background:A wide range in the prevalence of molar-incisor-hypomineralization (MIH) has been reported. Population-based studies are recommended. However, such studies are expensive and time-consuming. Objectives:To estimate the magnitude of MIH condition among 8-year-olds based on routine oral health examinations and to associate first permanent molar (FPM) affection with that of other permanent teeth over time. Materials and methods:This retrospective study, with cross-sectional and longitudinal components, was based on electronic oral health records; all 8-year-olds examined between 2002 and 2016 were included. Results:The average estimated prevalence of MIH was 8.3%; yearly range was 4.8-15.9%. The mean number of affected teeth was 1.4; 62% had one affected tooth. One-surface defects were the most frequent (66%). Asymmetric distribution of affected teeth was observed. In follow-up, 10.7%, 8.4%, and 11.2% had at least one affected permanent canine, premolar, or second permanent molar, respectively. The proportion of children with other MIH-affected permanent teeth was higher in the group with >= 2 MIH-affected teeth than in group with one affected FPM at the age of 8. Conclusions:The average prevalence of MIH was comparable to that reported elsewhere. The number of MIH-affected teeth at early mixed dentition predicts the affection of other permanent teeth over time, mainly that of permanent canines. Further screening of children with MIH is recommended to improve individually tailored early preventive and restorative dental care.Peer reviewe

Cytotoxicity and effect on protease activity of copolymer extracts containing catechin

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Dentin bond optimization using the dimethyl sulfoxide-wet bonding strategy : A 2-year in vitro study

Objective. This study evaluated a new approach, named dimethyl sulfoxide (DMSO)-wet bonding, to produce more desirable long-term prospects for the ultrafine interactions between synthetic polymeric biomaterials and the inherently hydrated dentin substrate. Methods. Sound third molars were randomly restored with/without DMSO pretreatment using a total-etch (Scocthbond Multipurpose: SBMP) and a self-etch (Clearfil SE Bond: CF) adhesive systems. Restored teeth (n = 10)/group were sectioned into sticks and submitted to different analyses: micro-Raman determined the degree of conversion inside the hybrid layer (DC); resin dentin microtensile bond strength and fracture pattern analysis at 24 h, 1 year and 2 years of aging; and nanoleakage evaluation at 24h and 2 years. Results. DMSO-wet bonding produced significantly higher 24 h bond strengths for SBMP that were sustained over the two-year period, with significantly less adhesive failures. Similarly, DMSO-treated CF samples presented significantly higher bond strength than untreated samples at two years. Both adhesives had significant less adhesive failures at 2 years with DMSO. DMSO had no effect on DC of SBMP, but significantly increased the DC of CE DMSO-treated SBMP samples presented reduced silver uptake compared to untreated samples after aging. Significance. Biomodification of the dentin substrate by the proposed strategy using DMSO is a suitable approach to produce more durable hybrid layers with superior ability to withstand hydrolytic degradation over time. Although the active role of DMSO on dentin bond improvement may vary according to monomer composition, its use seems to be effective on both self-etch and etch-and-rinse bonding mechanisms. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Association of erosive tooth wear and dental caries in Northern Finland Birth Cohort 1966-an epidemiological cross-sectional study

Background: The main aim of this cross-sectional study was to investigate the prevalence and severity of erosive tooth wear and its association with dental caries and socio-demographic factors among middle-aged Finnish adults. Methods: Of the total Northern Finland Birth Cohort 1966 (n = 12,058), a convenience sample (n = 3181 adults) was invited for an oral health examination of which 1962 (61.7 %) participated, comprising the final study group. Clinical examinations were carried out by trained and calibrated dentists. Erosive tooth wear was assessed by sextants using the Basic Erosive Wear Examination Index (BEWE, 0-18) and dental caries at surface level using the ICDAS criteria (0-6). Socio-demographic data were obtained from a postal questionnaire. A logistic regression model was generated to test the association of the variables. Results: The prevalence of erosive tooth wear was 75 % and the mean of the BEWE sum score was 3.4 (SD 3.30). Almost half of the members needed non-invasive or invasive measures to prevent further progression of the condition. Of those with erosive lesions, 14.6 % suffered from severe erosive tooth wear. There was a strong positive relationship between the presence of severe erosive tooth wear (BEWE sum score >= 9) and male gender and restorative treatment need. Conclusions: Erosive tooth wear is a common finding in Finnish adult population; almost one in ten suffer from severe erosive tooth wear. Restorative treatment need seems to be associated with severe erosive tooth wear.Peer reviewe

Influence of dimethyl sulfoxide used as a solvent on the physical properties and long-term dentin bonding of hydrophilic resins

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Co-distribution of cysteine cathepsins and matrix metalloproteases in human dentin

It has been hypothesized that cysteine cathepsin's (CTs) along with matrix metalloproteases (MMPs) may work in conjunction in the proteolysis of mature dentin matrix. The aim of this study was to verify simultaneously the distribution and presence of cathepsins B (CT-B) and K (CT-K) in partially demineralized dentin; and further to evaluate the activity of CTs and MMPs in the same tissue. The distribution of CT-B and CT-K in sound human dentin was assessed by immunohistochemistry. A double-immunolabeling technique was used to identify, at once, the occurrence of those enzymes in dentin. Activities of CTs and MMPs in dentin extracts were evaluated spectrofluorometrically. In addition, in situ gelatinolytic activity of dentin was assayed by zymography. The results revealed the distribution of CT-B and CT-K along the dentin organic matrix and also indicated co-occurrence of MMPs and CTs in that tissue. The enzyme kinetics studies showed proteolytic activity in dentin extracts for both classes of proteases. Furthermore, it was observed that, at least for sound human dentin matrices, the activity of MMPs seems to be predominant over the CTs one. (C) 2016 Elsevier Ltd. All rights reserved.Peer reviewe