Análise molecular vibracional da interface adesivo-dentina após aplicação de múltiplas camadas de sistemas adesivos convencionais de dois passos

O propósito do presente estudo foi analisar o efeito da aplicação de múltiplas camadas consecutivas de dois sistemas adesivos convencionais de dois passos na difusão resinosa e padrão de distribuição dos componentes monoméricos resinosos. Dezesseis terceiros molares humanos hígidos foram tratados com os sistemas adesivos convencionais de dois passos de acordo com as instruções dos fabricantes ou com aplicações em múltiplas camadas consecutivas. Os espécimes foram seccionados paralelamente aos túbulos dentinários e as superfícies submetidas ao polimento com lixas 600, 1200, 1800, 2000 e 4000. Os espectros Raman foram coletados ao longo de uma linha perpendicular a interface adesivo-resina em intervalos de 1 ou 2 m. As medidas de difusão da resina adesiva e distribuição dos componentes monomériccos foram avaliadas pelos picos Raman de 1113 cm-1, 1609 cm-1 e 1454 cm-1. O gradiente de desmineralização usado na determinação da região de hibridização foi avaliado pelo pico de 960 cm-1 da apatita. De acordo com os resultados obtidos, a aplicação de múltiplas camadas apresentou uma tendência de homogeneização dos componentes poliméricos, dependente da composição química da resina adesiva.

Nanoindentation measurements of bone viscoelasticity as a function of hydration state

Bone is an anisotropic material, and its mechanical properties are determined by its microstructure as well as its composition. Mechanical properties of bone are a consequence of the proportions of, and the interactions between, mineral, collagen and water. Water plays an important role in maintaining the mechanical integrity of the composite, but the manner in which water interacts within the ultrastructure is unclear. Dentine being an isotropic two-dimensional structure presents a homogenous composite to examine the dehydration effects. Nanoindentation methods for determining the viscoelastic properties have recently been developed and are a subject of great interest. Here, one method based on elastic-viscoelastic correspondence for 'ramp and hold' creep testing (Oyen, J. Mater. Res., 2005) has been used to analyze viscoelastic behavior of polymeric and biological materials. The method of 'ramp and hold' allows the shear modulus at time zero to be determined from fitting of the displacement during the maximum load hold. Changes in the viscoelastic properties of bone and dentine were examined as the material was systematically dehydrated in a series of water:solvent mixes. Samples of equine dentine were sectioned and cryo-polished. Shear modulus was obtained by nanoindentation using spherical indenters with a maximum load hold of 120s. Samples were tested in different solvent concentrations sequentially, 70% ethanol to 50% ethanol, 70 % ethanol to 100% ethanol, 70% ethanol to 70% methanol to 100% methanol, and 70% ethanol to 100% acetone, after storage in each condition for 24h. By selectively removing and then replacing water from the composite, insights in to the ultrastructure of the tissue can be gained from the corresponding changes in the experimentally determined moduli, as well as an understanding of the complete reversibility of the dehydration process. © 2006 Materials Research Society.

Caries-induced changes in the expression of pulpal neuropeptide Y

Recent evidence suggests that the sympathetic nervous system may have a role in modulating neurogenic inflammation and bone remodelling. Neuropeptide Y (NPY) is a well-characterized neuropeptide transmitter in the peripheral sympathetic nervous system. NPY is known to be present in human dental pulp; however, quantitative data on NPY levels in pulpal health and disease in an adult population remain to be determined. The aims of the current study were to assess, quantitatively, NPY levels by radioimmunoassay and confirm the distribution of NPY fibres by immunocytochemistry in carious and non-carious adult human pulp tissue. Our results suggest changes in the levels and distribution of NPY in human dental pulp during the caries process, with significantly higher levels of NPY in carious compared with non-carious adult human teeth. Within the carious samples studied, our finding, that NPY levels were significantly elevated in mild/moderate caries, concurs with the hypothesis that NPY could have a modulatory role in pulpal inflammation and in reparative dentine formation. © 2006 Eur J Oral Sci.

Thermographic investigation of contemporary resin-containing dental materials

This is the sixth paper that I have published involving thermography. In this research we were using thermogrphy to measure the temperature increases generated during photocuring of a range of clinical materials. The materials investigated were all commonly used products. The work also investigated the insulation potential of various thicknesses of human dentine when placed between the curing materials and the thermal imaging camera. From a clinical perspective this work may be used to influence the methods used to place restorative dental materials

Functional expression of thermo-sensitive TRP channels in human odontoblasts

Introduction: Accumulating evidence supports a role for odontoblasts in initiating tooth pain, however direct ionic mechanisms underlying dentine nociceptive function remain unclear. The transient receptor potential (TRP) ion channels are directly related to cellular mechanisms of nociception and thermo-sensitive function but their expression by human odontoblasts remains to be determined. Objectives: To investigate the expression and functionality of the thermo-sensitive TRP channels TRPV1, TRPV4, TRPM8 and TRPA1 in human odontoblasts. Methods: Human odontoblasts were derived from dental pulp of immature permanent third molars by explant method. Cell lysates of odontoblasts were subject to SDS- polyacrylamide gel electrophoresis and proteins were blotted onto nitrocellulose membranes. Blots were probed with primary antibodies to TRPA1, TRPM8, TRPV4 and TRPV1. Detection of bound primary antibodies was achieved using appropriate anti-species antibody conjugates and chemiluminescent substrates. Functionality of the channels was determined with Ca2+ microfluorimetry, where cells grown in cover slips and incubated with Fura 2AM prior to stimulation with capsaicin (TRPV1 agonist), 4 alpha-phorbol 12,13-didecanoate (4áPDD) (TRPV4 agonist), icilin (TRPA1 agonist) and menthol (TRPM8 agonist). Emitted fluorescence was measured and the fluorescence ratio (R) was calculated as F340/F380 to determine the level of [Ca2+]i. Results: Western blotting confirmed the molecular localisation of thermo-sensitive TRP channels in human odontoblasts. Functionality assays revealed increase in [Ca2+]i in response to capsacin, icillin, methanol and 4áPDD indicating functional expression of TRPV1, TRPA1, TRPM8 and TRPV4 respectively. Conclusions: Functional expression of thermo-sensitive TRP channels in human odontoblasts may indicate a crucial role for odontoblasts in thermally induced dental pain. (Supported by a Research Grant from the Royal College of Surgeons of Edinburgh)

The prevalence of caries in patients referred for orthodontic assessment in Northern Ireland – A retrospective study

Objectives: To determine the prevalence of untreated carious lesions in permanent teeth in patients (under the age of 18) referred for an orthodontic assessment in specialist practice. In addition, the figures shall be compared with national data for Northern Ireland (as outlined in the recent Child Dental Health Survey 2013)
The Gold standard would be that 100% of patients would be caries free upon presentation.

Methods: The clinical records and radiographs (OPT of quality grading 1 or 2) of 337 patients were reviewed. This encompassed patients who had an orthodontic assessment carried out in specialist practice over a 6 month period (following referral from their general dental practitioner)

Results: A total of 337 patient records were examined. Of these, 149 were male (44.2%) and 188 were female (55.8%), with an age range of 7-17 years at the time of new patient assessment. It was found that 36 patients (10.7%) had evidence (clinical and/or radiographic) of active and untreated dental caries. Of those affected, 14 were male and 22 were female.
Breaking the data down in terms of age, we can also get some indication as to how this cohort compares with national data for Northern Ireland :⃰

7-10 years (Mean = 9.3) = 14.3% caries (versus NI average of 6% for 8 year olds)
11-13 years (Mean = 12.1) = 10.1% caries, (versus NI average of 16% for 12 year olds)
14-17 years (Mean = 15.2) = 9.1% caries (versus NI average of 15% for 15 year olds)

⃰using the diagnostic threshold “Decay into dentine (visual dentine caries excluded)”


Conclusion: In this sample group, a total of 10.7% of patients (9.4% of males, 11.7% of females) presented with evidence of undiagnosed caries upon being assessed as a new patient in specialist orthodontic practice. Hence, the gold standard was not met.

Chasseurs de bisons : apports de l’archéozoologie et de la biogéochimie isotopique à l’étude palethnographique et paléoéthologique du gisement épigravettien d’Amvrosievka (Ukraine)

Réalisé en cotutelle avec le Département de Préhistoire du Muséum national d’Histoire naturelle (Paris, France), École doctorale « Sciences de la nature et de l’Homme » (ED 227)

Évolution des pratiques alimentaires en cours de vie : une étude isotopique multi-matérielle de la population du cimetière Saint-Matthew (Québec, 1771-1860)

En tant que population majoritairement immigrante, les protestants inhumés au cimetière Saint-Matthew, ville de Québec (1771-1860) ont dû s'adapter à un nouvel environnement à leur arrivée au Québec, et donc à de nouvelles ressources. Parallèlement, les 18e et 19e siècles sont marqués par un contexte socio-économique en pleine mutation avec l'arrivée graduelle de la période industrielle, et la ville de Québec, avec son contexte portuaire, a ainsi été au coeur de ces changements. L'objectif de ce mémoire est d'évaluer si la géochimie des isotopes stables appliquée à plusieurs matériaux du squelette humain (collagène et apatite de l'os, collagène de la dentine, et carbonate de l'émail) permet de mieux comprendre comment les comportements alimentaires des individus analysés provenant de ce cimetière cosmopolite (n=40) ont évolué en cours de vie. L'alimentation étant influencée par des conditions socio-économiques, culturelles et environnementales, cela peut nous informer indirectement sur les processus d'adaptation et l'identité d'un individu. C'est dans cette perspective d'écologie culturelle que nous avons interprété les données recueillies lors de ce projet, en complément aux analyses effectuées précédemment par Morland (2009) et Caron (2013). Nos résultats corroborent les tendances déjà observées, soit des pratiques alimentaires semblables à celles que l'on retrouve en Europe, et des immigrants provenant majoritairement des Îles Britanniques. Ils démontrent également une légère augmentation de la consommation de ressources C4, comme le maïs et la canne à sucre, à l'âge adulte pour 90% des individus analysés, de même qu'une baisse du niveau de protéines. Par ailleurs, les individus étudiés ont généralement eu tendance à conserver le même niveau alimentaire les uns par rapport aux autres tout au cours de leur vie, même si les pratiques étaient moins diversifiés à l'âge adulte. Finalement, on constate des similarités de comportements avec les populations irlandaises et britanniques plus pauvres durant l'enfance, alors qu'ils ressemblent davantage à ceux visibles dans la vallée laurentienne en fin de vie, notamment en ce qui concerne l'apport en protéines. Nos résultats suggèrent donc des changements alimentaires significatifs, fort possiblement liés aux processus de migration et à une adaptation constante à un nouvel environnement de la part des individus étudiés.

Influence of pulse repetition rate of Er : YAG laser and dentin depth on tensile bond strength of dentin-resin interface

The study evaluated the in vitro influence of pulse-repetition rate of Er:YAG laser and dentin depth on tensile bond strength of dentin-resin interface. Dentin surfaces of buccal or lingual surfaces from human third molars were submitted to tensile test in different depths (superficial, 1.0 and 1.5 mm) of the same dental area, using the same sample. Surface treatments were acid conditioning solely (control) and Er:YAG laser irradiation (80 mJ) followed by acid conditioning, with different pulse-repetition rates (1, 2, 3, or 4 Hz). Single bond/Z-250 system was used. The samples were stored in distilled water at 37 degrees C for 24 h, and then the first test (superficial dentine) was performed. The bond failures were analyzed. Following, the specimens were identified, grounded until 1.0- and 1.5-mm depths, submitted again to the treatments and to the second and, after that, to third-bond tests on a similar procedure and failure analysis. ANOVA and Tukey test demonstrated a significant difference (p < 0.001) for treatment and treatment X depth interaction (p < 0.05). The tested depths did not show influence (p > 0.05) on the bond strength of dentin-resin interface. It may be concluded that Er:YAG laser with 1, 2, 3, or 4 Hz combined with acid conditioning did not increase the resin tensile bond strength to dentin, regardless of dentin depth. (C) 2007 Wiley Periodicals, Inc.

Microstructure and Mineral Composition of Dental Enamel of Permanent and Deciduous Teeth

Purpose: This study evaluated and compared in vitro the microstructure and mineral composition of permanent and deciduous teeth`s dental enamel. Methods: Sound third molars (n = 12) and second primary molars (n = 12) were selected and randomly assigned to the following groups, according to the analysis method performed (n = 4): Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Energy dispersive X-ray spectrometer (EDS). Qualitative and quantitative comparisons of the dental enamel were done. The microscopic findings were analyzed statistically by a nonparametric test (Kruskal-Wallis). The measurements of the prisms number and thickness were done in SEM photomicrographs. The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Chemical phases present in both types of teeth were observed by the XRD analysis. Results: The mean thickness measurements observed in the deciduous teeth enamel was 1.14 mm and in the permanent teeth enamel was 2.58 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enamel-dentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The percentage of Ca and P was higher in the permanent teeth enamel. Conclusions: The primary enamel structure showed a lower level of Ca and P, thinner thickness and higher numerical density of rods. Microsc. Res. Tech. 73:572-577, 2010. (C) 2009 Wiley-Liss. Inc.

High-power diode laser in the disinfection in depth of the root canal dentin

Objective. The objective of this study was to evaluate the disinfection degree of dentine caused by the use of diode laser after biomechanical procedures. Study design. Thirty teeth were sectioned and roots were autoclaved and incubated for 4 weeks with a suspension of Enterococcus faecalis. The specimens were randomly divided into 3 groups (n = 10): G1, instrumented with rotary files, irrigated with 0.5% sodium hypochlorite and 17% EDTA-T, and then irradiated by 830-nm diode laser at 3 W; G2, the same procedures as G1 but without laser irradiation; and G3, irrigation with saline solution (control). Dentin samples of each third were collected with carbide burs and aliquots were sowed to count viable cells. Results. The disinfection degree achieved was 100% in G1 and 98.39% in G2, when compared to the control group (G3). Conclusion. Diode laser irradiation provided increased disinfection of the deep radicular dentin in the parameters and samples tested.

Determination of dental decay rates with optical coherence tomography

We report the use of optical coherence tomography (OCT) to detect and quantify demineralization process induced by S. mutans biofilm in third molars human teeth. Artificial lesions were induced by a S. mutans microbiological culture and the samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9, and 11days. The OCT system was implemented using a light source delivering an average power of 96 mu W in the sample arm, and spectral characteristics allowing 23 mu m of axial resolution. The images were produced with lateral scans step of 10 pan and analyzed individually. As a result of the evaluation of theses images, lesion depth was calculated as function of demineralization time. The depth of the lesion in the root dentine increased from 70 pm to 230,urn (corrected by the enamel refraction index, 1.62 @ 856 nm), depending of exposure time. The lesion depth in root dentine was correlated to demineralization time, showing that it follows a geometrical progression like a bacteria growth law. [GRAPHICS] Progression of lesion depth in root dentine as function of exposure time, showing that it follows a geometrical progression like a bacteria growth law(C) 2009 by Astro Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA

Dentin hypersensitivity clinical study comparing LILT and LEDT keeping the same irradiation parameters

Dentin hypersensitivity is a common condition associated with high dental pain. A new LED-based (light emitting diode) light source has been used as an experimental tool in some studies. Purpose: The main objective was to compare these two light sources emitting in the same spectral band (red from 625 to 660 nm) to promote pain relief. Material and methods: A total of 6 sessions were accomplished, being three irradiation sessions and three follow-up sessions. This single-blind study compared a control group (Placebo) and two other groups with different equipments: low laser intensity treatment (LILT) and a light emitting diode system treatment (LEDT). Results: The results showed that there is no statistical difference between LILT and LEDT groups, however, both were better than control group (p=0.01) in terms of treatment efficiency; there is no difference between the second and the third sessions for both treatment, it means that the third session was not necessary; finally, the improvement at the end of the entire research (follow up care of 30 days) was very expressive in comparison to pre-treatment situation for all teeth (p=0.01). Conclusion: LILT and LEDT were equally effective to treat dentine hypersensitivity, a 3rd treatment session was not necessary/two sessions are enough.

Comparing external and internal dorsal-spine bands to interpret the age and growth of the giant lantern shark, Etmopterus baxteri (Squaliformes: Etmopteridae)

The giant lantern shark, Etmopterus baxteri, is taken as bycatch of commercial fisheries that operate in deepwater off southeastern Australia. Bands on the second dorsal spine were used to obtain age estimates. The number of bands on the external surface of the spine and within the inner dentine layer increased with animal length. Most spines had more bands on the external surface, and the rate of band formation was significantly different between the external surface and the inner dentine layer. Females had a maximum of 57 external bands and 26 internal bands, while males had up to 48 external bands and 22 internal bands. Age estimates from external bands suggest maturity (A ₅₀) at 20 years for males and 30 years for females. Internal band age estimates suggest maturity at 10.5 years for males and 11.5 years for females. Although there is a large discrepancy between these two preliminary (i.e., unvalidated) age estimates, they both suggest that E. baxteri is a long-lived and late maturing species that is likely to be susceptible to over fishing.

Biological vulnerability of two exploited sharks of the genus Deania (Centrophoridae)

Life-history parameters of Deania calcea and Deania quadrispinosa suggested that their productivity was very low. Maturity (L_T50) occurs at c. 80% of maximum observed total lengths (L_T) for both species and sexes. A large proportion of mature females were neither pre-ovulatory nor pregnant, and the reproductive cycle included a distinct resting phase after pregnancy. For D. calcea, mean ovarian fecundity was 12 and maximum observed litter size was 10 (average of six); D. quadrispinosa averaged 17 pups per litter. Birth L_T was 28-33 cm for D. calcea and 23-25 cm for D. quadrispinosa. The male and female reproductive cycles were aseasonal, and consequently, the length of the reproductive cycle could not be determined. Preliminary ageing data from dorsal-spine growth bands suggested that female D. calcea lived to 31-36 years and males to 24-32 years. The L_T-at-age data using external bands on the spines showed maturity occurring at 15·5 years (males) and 21·5 years (females), whereas banding on the internal dentine indicated maturity at 10·5 and 17·5 years for males and females. Thus, a female lifetime of 31-36 years allowed for a maximum of 7 litters if a 2 year cycle is assumed or only five litters with a 3 year cycle, resulting in a lifetime fecundity of only 42 pups (2 year cycle) or even lower (3 year cycle).