Dental caries and enamelin haplotype

In the literature, the enamelin gene ENAM has been repeatedly designated as a possible candidate for caries susceptibility. Here, we checked whether ENAM variants could increase caries susceptibility. To this aim, we sequenced coding exons and exon-intron boundaries of ENAM in 250 children with a severe caries phenotype and in 149 caries-free patients from 9 French hospital groups. In total, 23 single-nucleotide polymorphisms (SNPs) were found, but none appeared to be responsible for a direct change of ENAM function. Six SNPs had a high minor allele frequency (MAF) and 6 others were identified for the first time. Statistical and evolutionary analyses showed that none of these SNPs was associated with caries susceptibility or caries protection when studied separately and challenged with environmental factors. However, haplotype interaction analysis showed that the presence, in a same variant, of 2 exonic SNPs (rs7671281 and rs3796704; MAF 0.12 and 0.10, respectively), both changing an amino acid in the protein region encoded by exon 10 (p.I648T and p.R763Q, respectively), increased caries susceptibility 2.66-fold independent of the environmental risk factors. These findings support ENAM as a gene candidate for caries susceptibility in the studied population.

Common SNPs of AmelogeninX (AMELX) and dental caries susceptibility

Genetic approaches have shown that several genes could modify caries susceptibility; AmelogeninX (AMELX) has been repeatedly designated. Here, we hypothesized that AMELX mutations resulting in discrete changes of enamel microstructure may be found in children with a severe caries phenotype. In parallel, possible AMELX mutations that could explain resistance to caries may be found in caries-free patients. In this study, coding exons of AMELX and exon-intron boundaries were sequenced in 399 individuals with extensive caries (250) or caries-free (149) individuals from nine French hospital groups. No mutation responsible for a direct change of amelogenin function was identified. Seven single-nucleotide polymorphisms (SNPs) were found, 3 presenting a high allele frequency, and 1 being detected for the first time. Three SNPs were located in coding regions, 2 of them being non-synonymous. Both evolutionary and statistical analyses showed that none of these SNPs was associated with caries susceptibility, suggesting that AMELX is not a gene candidate in our studied population.

Vulnérabilité socialedes consultants d'odontologie d'un hôpital public

There are social inequalities in oral and dental health. It can be useful to identify people in socially vulnerable or marginalised situations because they require a particular kind of care. Through a survey of patients in a dentistry services in a public hospital, we sought to identify those people in a precarious socio-economic situation by the use of a tool designed and validated by multi-disciplinary experts. The tool includes five criteria, and is presented in the format of an index card which is filled in by the patient upon his arrival. This data collection was carried out in two distinctly separate period of time (winter and summer). 865 cards were collected, and the rate of collection of complete data was 73%. 94% of the cards allowed us to determine the socio-economic status of the patient, and 48% (n=382) of them were classified as having a socially vulnerable situation. Among them, 69% of them benefited from CMU or AME, and 59% of them do not have any supplementary health insurance. 47% of them admit to having difficulties in paying for their medications or covering the cost of their medical consultations, and 48% perceive a social service aide. The prevalence of social vulnerability of the dental centre's patients is estimated at 32%. This data collection tool has made it possible to measure the significance and the nature of the social vulnerability of the patients who receive care and services from this public hospital's dentistry unit. Its capacity to identify patients whose care needs are often not met remains to be seen, as well as the capacity of the hospital to make up for these lost opportunities thus remains to be highlighted.

Calcium-deficient apatite: a first in vivo study concerning bone ingrowth

Biphasic calcium phosphate (BCP) materials are increasingly used to restore bone loss in surgery. Calcium-deficient apatites (CDA), the precursors of BCP, are closer in structure to biological apatites and can be associated with therapeutic agents to form drug-delivery systems. The purpose of this first in vivo study of CDA was to evaluate the osteoconductive properties of two composites, consisting of 40-80 microm granules carried by a cellulose-derived polymer, used to fill critical size bone defects in rabbit femoral ends. Animals were sacrificed 2 or 3 weeks after implantation. Histomorphometric analysis of scanning electron microscopy implant surface files was performed using gray level threshold that distinguish between bone or materials (white) and noncalcified tissue (black). Quantitative results for new bone formation showed no significant differences between the composites or the implantation periods. However, nearly all of the CDA disappeared early while supporting more extensive bone colonization than biphasic calcium phosphates implanted in the same conditions.

Clinical evaluation of the Carisolv chemomechanical caries removal technique according to the site/stage concept, a revised caries classification system

The objective of the present study was to assess the efficiency and benefit of a chemomechanical system for carious dentin removal, Carisolv, in general practice. A revised caries classification, the site/stage concept, was used to describe the clinical situations of all carious lesions treated. The study was performed by 12 investigators, and 120 carious lesions were treated with Carisolv. Sixty percent of the cases were treated without anaesthesia, and we found a significant correlation between chemomechanical treatment without anaesthesia and absence of pain ( P=0.01). In 78.3% of the cases, carious dentin was totally removed with Carisolv, and in 21.7%, the dentin treatment was completed by drilling. In cases performed with Carisolv alone, the time required to remove carious dentin was 11.1+/-9.51 min (mean+/-SD). Treatment time was equivalent for all sites and increased significantly with each successive stage of lesion progression ( P<0.001). In 82.5% of cases, the clinicians were satisfied with Carisolv, and in 99.2%, so were the patients. We conclude that, using clinical examination methods, Carisolv seems to remove carious dentin at all sites and stages of carious lesions but must be made more efficient for use in general practice.

Quantitative immunogold labeling of bone sialoprotein and osteopontin in methylmethacrylate-embedded rat bone

Methylmethacrylate (MMA) embedding of undecalcified bone is routinely employed for histomorphometric analyses. Although MMA-embedded bone has been used for immunolabeling at the light microscopic level after removal of the resin, there are no such reports for electron microscopy. The aim of the present study was to determine whether MMA embedding can be used for ultrastructural immunolabeling and how it compares to LR White (LRW), an acrylic resin frequently used for immunocytochemistry of bone. Rat tibiae were fixed by vascular perfusion with aldehyde and embedded either in MMA or LRW resin. Thin sections were processed for postembedding protein A-gold immunolabeling with antibodies to rat bone sialoprotein (BSP) and osteopontin (OPN). The density of gold particles over bone was quantified. The density and distribution of immunolabeling for BSP and OPN respectively, were comparable between MMA and LRW. These results indicate that MMA performs as well as LRW for the ultrastructural immunolabeling of noncollagenous bone matrix proteins.

Effects of Er:YAG and Nd:YAP laser irradiation on the surface roughness and free surface energy of enamel and dentin: an in vitro study

Sixty-seven extracted molars were selected (134 samples). Dentin and enamel samples were prepared by buccal and lingual surface sectioning to expose a planar enamel or dentin surface. For the roughness study, 80 samples were randomly assigned to eight groups. Enamel and dentin surfaces were etched with a 37% phosphoric acid solution, irradiated with an Er:YAG laser or irradiated with a Nd:YAP laser. Samples were then observed in SEM using BSE. For the free-surface energy study, 54 samples received the same treatment as above. Two contact angle measurements were made on each surface using a goniometer. Data were analyzed by a non-parametric statistical test. Morphological changes on enamel and dentin were greater with acid-etch and Er:YAG laser than with Nd:YAP laser. Free surface energy was significantly greater with acid-etch or Er:YAG laser than with Nd:YAP laser (p < 0.001).

Study of the maturation of the organic (type I collagen) and mineral (nonstoichiometric apatite) constituents of a calcified tissue (dentin) as a function of location: a Fourier transform infrared microspectroscopic investigation

Fourier transform infrared microspectroscopy (FTIRM) was used to investigate the organic and mineral phases of a calcified tissue (dentin) as a function of its location from predentin toward enamel. Thin dentin slices (decalcified or not) were fixed in formaldehyde and embedded in glycolmethylmethacrylate (GMA). Fixation did not denature collagen, and GMA did not interact with organic or mineral constituents of dentin. The v1v3 PO4 domain was studied in particular in order to estimate mineral maturity and amide I, II, A, and B to obtain data on protein conformation. The results showed that dentin apatite became increasingly mature (stoichiometric) from the mineralization front toward the enamel, especially through loss of HPO4(2-) groups and vacancies. Moreover, collagen fibrils became less and less hydrated, suggesting that intrafibrillar mineralization partially dehydrated the collagen. Combined study of the organic and mineral fractions of calcified tissues may help clarify their relationships in physiological and pathological tissues.

Development of a monoclonal antibody against dentin phosphophoryn: a tool to study odontoblastic activity

The role played by phosphophoryn, one of the major noncollagenous proteins of dentin extracellular matrix, in the mineralization process has not been fully characterized. The purpose of our work was to produce monoclonal antibodies (MAbs) against dentin phosphophoryn and to test their reactivity with primary culture of odontoblasts. Dentin phosphophoryn (DPP) was extracted after the mechanical dissociation of teeth and dialyzed against guanidine and EDTA solutions followed by CaC1(2) precipitation. These extracts were characterized by SDS-PAGE and staining with Coomassie blue and Stains-All. After immunization of mice with these extracts, we produced MAb 7G4, which reacted with dentin phosphophoryn as revealed by Western blot. MAb 7G4 reactivity was tested against a primary culture of pig odontoblasts, revealing filaments specifically stained by the anti-DPP antibody. This antibody will be of great interest to study the mineralization process and dental pulp reaction after capping with various calcium phosphate materials.

Proteins of the mineral compartment of bovine fetal enamel share common antigenic determinants with serum proteins

Two fractions were separated from the proteins of the mineral compartment of bovine developing enamel on the basis of their affinity for the lectin concanavalin-A. A monoclonal antibody was prepared by the hybridoma technique against the Con-A-binding fraction. This antibody and a commercial polyclonal antibody against bovine serum albumin were used to examine the relationship between those proteins, serum albumin and alpha-2HS glycoprotein, two proteins concentrated within dentin and bone matrices. The Con-A-unbound fraction reacted with the anti-albumin antibody and the antibody against the Con-A-binding fraction recognized the alpha-2HS glycoprotein. These data fully support the presence of significant levels of proteins related to serum components in the mineral compartment of developing enamel matrix.