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Quaternary dating by electron spin resonance (ESR) applied to human tooth enamel
Carvajal,Eduar; Montes,Luis; Almanza,Ovidio A.;
Earth Sciences Research Journal , 2011,
Abstract: this paper presents the results obtained from using electron paramagnetic resonance (epr) to analyse tooth enamel found at the aguazuque archaeological site (cundinamarca, colombia), located on the savannah near bogota at 4° 37' north and 74°17' west. it was presumed that the tooth enamel came from a collective burial consisting of 23 people, involving men, women and children. the tooth enamel was irradiated with gamma rays and the resulting free radicals were measured using an electron spin resonance (esr) x-band spectrometer to obtain a signal intensity compared to absorbed doses curve. fitting this curve allowed the mean archaeological dose accumulated in the enamel during the period that it was buried to be estimated, giving a 2.10 ± 0.14 gy value. rosy software was used for estimating age, giving a mean 3,256 ± 190y before present (bp) age. these results highlight epr's potential when using the quaternary ancient ruins dating technique in colombia and its use with other kinds of samples like stalagmites, calcite, mollusc shells and reefs.
Quaternary dating by electron spin resonance (ESR) applied to human tooth enamel  [cached]
Carvajal Eduar,Montes Luis,Almanza Ovidio A.
Earth Sciences Research Journal , 2011,
Abstract: This paper presents the results obtained from using electron paramagnetic resonance (EPR) to analyse tooth enamel found at the Aguazuque archaeological site (Cundinamarca, Colombia), located on the savannah near Bogota at 4° 37' North and 74°17' West. It was presumed that the tooth enamel came from a collective burial consisting of 23 people, involving men, women and children. The tooth enamel was irradiated with gamma rays and the resulting free radicals were measured using an electron spin resonance (ESR) X-band spectrometer to obtain a signal intensity compared to absorbed doses curve. Fitting this curve allowed the mean archaeological dose accumulated in the enamel during the period that it was buried to be estimated, giving a 2.10 ± 0.14 Gyvalue. ROSY software was used for estimating age, giving a mean 3,256 ± 190y before present (BP) age. These results highlight EPR's potential when using the quaternary ancient ruins dating technique in Colombia and its use with other kinds of samples like stalagmites, calcite, mollusc shells and reefs.
Restoration of Tooth Enamel Caries by Hydrolysis of | TCP  [PDF]
MA Ying,LI Si-Wei,FENG Zu-De
无机材料学报 , 2009, DOI: 10.3724/sp.j.1077.2009.00275
Abstract: A novel method was developed to grow hydroxyapatite (HA) coatings on the surface of enamel. The coatings were formed by hydrolysis of | TCP for 6h at 37 The detailed characterizations of the microstructure and mechanical properties of the coatings, and cytotoxicity of | TCP hydrolysis solution were performed. SEM and TEM analysis show that the HA coatings, approximate 20| in thickness grow perpendicularly to the enamel surface, contacting well to the surface of enamel. Vickers microhardness and weara2resistance tests indicate that there is no statistical significant difference of the hardeness and weara2resistance between the coatings and healthy natural enamel. The grade of cytotoxicity of | TCP hydrolysis solution is I grade, satisfying the relevant criterion on biomaterials. The study suggests that the hydrolysis of | TCP is a promising method to effectively and conveniently restore and prevent early enamel caries.
Bond strength of adhesive systems to human tooth enamel
Paradella, Thaís Cachuté;Fava, Marcelo;
Brazilian Oral Research , 2007, DOI: 10.1590/S1806-83242007000100001
Abstract: the purpose of this study was to evaluate in vitro three adhesive systems: a total etching single-component system (g1 prime & bond 2.1), a self-etching primer (g2 clearfil se bond), and a self-etching adhesive (g3 one up bond f), through shear bond strength to enamel of human teeth, evaluating the type of fracture through stereomicroscopy, following the iso guidance on adhesive testing. thirty sound premolars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin, polished up to 600-grit sandpapers, and randomly assigned to three experimental groups (n = 20). composite resin cylinders were added to the tested surfaces. the specimens were kept in distilled water (37°c/24 h), thermocycled for 500 cycles (5°c-55°c) and submitted to shear testing at a crosshead speed of 0.5 mm/min. the type of fracture was analyzed under stereomicroscopy and the data were submitted to anova, tukey and chi-squared (5%) statistical analyses. the mean adhesive strengths were g1: 18.13 ± 6.49 mpa, (55% of resin cohesive fractures); g2: 17.12 ± 5.80 mpa (90% of adhesive fractures); and g3: 10.47 ± 3.14 mpa (85% of adhesive fractures). in terms of bond strength, there were no significant differences between g1 and g2, and g3 was significantly different from the other groups. g1 presented a different type of fracture from that of g2 and g3. in conclusion, although the total etching and self-etching systems presented similar shear bond strength values, the types of fracture presented by them were different, which can have clinical implications.
Tooth Enamel, the Result of the Relationship between Matrix Proteins and Hydroxyapatite Crystals  [PDF]
Carmen Mihaela MIHU,Diana DUDEA,Carmen MELINCOVICI,Bianca BOC?A
Applied Medical Informatics , 2008,
Abstract: Enamel, a structure of epithelial origin, represents a protective tooth cover. The cells responsible for the formation of enamel, ameloblasts, are lost at the time of tooth eruption, so that enamel becomes an acellular structure that can no longer regenerate. In order to compensate for this particular phenomenon, enamel has acquired a complex structural organization and a high mineralization degree, in its mature state. This reflects the particular life cycle of ameloblasts and the unique physico-chemical characteristics of matrix proteins, which regulate the formation of the extremely long crystals of enamel. These characteristics differentiate enamel from all the other tissues of the organism.
Extrinsic Tooth Enamel Color Changes and Their Relationship with the Quality of Water Consumed  [PDF]
Kathleen Rebelo de Sousa,Marília Jesus Batista,Juliana Rocha Gon?alves,Maria da Luz Rosário de Sousa
International Journal of Environmental Research and Public Health , 2012, DOI: 10.3390/ijerph9103530
Abstract: The quality of the consumed drinking water may affect oral health. For example, the presence of iron in drinking water can cause aesthetic problems related to changes in dental enamel color. This study assessed the prevalence of extrinsic enamel color changes and their relationship with the quality of the water in the town of Caapiranga/AM-Brazil. Three hundred and forty six residents of the urban area were examined, and they also answered a questionnaire on eating habits and self-perceived oral health. As the initial results indicated an insufficient number of observations for the application of variance analysis (one-way ANOVA), the Student t test was chosen to compare levels of iron content in the water coming from two sources. The change in tooth color had a prevalence of 5.78% (20 people). The majority of the population (n = 261, 75.43%) consumed well water. Those who presented extrinsic stains were uncomfortable with the appearance of their teeth (15.09%). We conclude that while there is excess of iron in the water in this region of Brazil, no association between extrinsic stains on the enamel and the level of iron in the water was found. There was a low prevalence of extrinsic stains in Caaparinga, being found only in children and adolescents. In the present study, an association between the presence of stains and the consumption of a?ai was determined, and those who presented them felt uncomfortable about their aesthetics.
XRD Characterization of Crystallinity of Human Tooth Enamel under Influence of Mechanical Grinding  [PDF]
Jose Reyes-Gasga, Olga Koudriavtseva, Raul Herrera-Becerra, Arturo Escobosa
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.66050
Abstract: Crystallinity refers to the degree of structural order in a solid and has a big influence on hardness, density, transparency and diffusion. Even within materials that are crystalline completely, the degree of structural perfection can vary, reflecting size and elastic strain of many independent crystalline regions (grains or crystallites) of which these materials are composed. In this work it was attempted to reduce the crystallinity of human enamel using a technique of mechanical grinding (MG) with an ultra-compact FRITSCH Mini-Mill PULVERISETTE 23 machine. Variation in the crystallinity through the MG was monitored by X-ray diffraction (XRD) by broadening of the diffraction peak and examined using the Williamson-Hall plot method. Crystallites in human enamel are regularly arranged and oriented (in the [001] direction) perpendicularly to the interface of enameldentin junction. The results showed an anisotropic feature in crystallinity. Reduction of the crystallinity along the a-axis is due to the crystal strain rather than to the refinement of crystal, and vice versa along the c-axis. After 230 h of the MG, the length of crystallites decreased from 100 nm to 30 nm and width from 40 nm to 37 nm approximately.
Effect of several tooth-colored restorative materials on reinforcement of unsupported enamel
Mohammadreza Malekipour,Farzaneh Shirani,Parvin Mirzakoucheki,Samaneh Alaei
Journal of Isfahan Dental School , 2012,
Abstract: Introduction: Adhesive restorations properly transmit and distribute functional stresses at the bonding interface to tooth structures and have the potential to reinforce remaining weakened tooth structures after removal of extensive carious lesions. This study evaluated the effect of a number of adhesive restorative materials on reinforcing unsupported enamel. Materials and Methods: Seventy-five extracted sound maxillary premolars collected over 3 months and stored in 0.2% thymol solution received MOD cavities; the lingual cusps were reduced up to the pulp level. The specimens were divided into five groups (n=15). In group 1 (the positive control), dentinal tissue of the buccal wall was preserved. In other groups the buccal dentin was completely removed. In group 2 (the negative control), no restorative material was used to replace the lost dentin. The removed buccal dentin was replaced with composite resin, flowable composite resin and glass-ionomer in groups 3, 4 and 5, respectively. After thermocycling, the specimens were tested in an Instron universal testing machine. Data were analyzed with ANOVA and LSD test (a < 0.05). Results: The mean and standard deviations of fracture loads of the five groups were 122.97 ± 15.11, 44.71 ± 14.23, 78.32±17.58, 81.17 ± 19.53, and 85.33 ± 22.07 Newtons, respectively. One-way ANOVA revealed significant differences between the groups (p value = 0.00). There were significant differences in fracture loads between groups 1 and 2 and others (p value = 0.00). The difference in fracture loads between group 3 and 4 (p value = 0.678), groups 3 and 5 (p value = 0.344), and groups 4 and 5 (p value = 0.589) were not significant. Conclusion: It can be concluded that the three types of adhesive restorative materials in this study can reinforce unsupported enamel to a certain degree. Key words: Composite resin, Dental adhesives, Reinforcement, Tooth enamel.
Histologic evaluation of effectiveness of Enamel Matrix Derivative in surgical defect of sheep tooth
Pak Nejad M.,Rokn AM.,Semyari H.
Journal of Dental Medicine , 2001,
Abstract: "nAbstract: The aim of the present study was the histological evaluation of Enamel Matrix Derivative (EMD) effectiveness for regeneration of periodontal defects. EMD activates cementum synthesis, PDL and bone during the maturation stage of follicole. In this research, EMD was used in surgical defects of premolar teeth in four adult sheep. Muccoperiosteal flap was reflected in buccal site of teeth. The buccal bone plate was removed from mesial to distal in 4 mm depth. After eliminating the cementum by bur and its etching, EMD was applied on exposed dentine and flap was sutured. In opposite sites of those teeth (control sites) the same process was performed without etching. After 100 days, sheep were sacrificed and histological study through light microscopic was performed on black sections of operation sites. The results showed that in test sites, regeneration of cementum and bone was 62/5% and 42/5-50% respectively. But in control sites regeneration of cementum and bone was 37.5% and 32/5-42/5% respectively. Also the migration of junctional epithelium in control sites was 8-10% more than test sites. The important point is that in test sites, cementum was completely attached to undermining dentine. But, in control sites, the gap between cementum and dentine was visible. As a result, this study suggests that EMD promotes periodontal regeneration, and EMD application is a successful achievement in regenerative periodontal therapy.
Effects of Ion-Releasing Tooth-Coating Material on Demineralization of Bovine Tooth Enamel  [PDF]
Koji Kawasaki,Masaki Kambara
International Journal of Dentistry , 2014, DOI: 10.1155/2014/463149
Abstract: We compared the effect of a novel ion-releasing tooth-coating material that contained S-PRG (surface-reaction type prereacted glass-ionomer) filler to that of non-S-PRG filler and nail varnish on the demineralization of bovine enamel subsurface lesions. The demineralization process of bovine enamel was examined using quantitative light-induced fluorescence (QLF) and electron probe microanalyzer (EPMA) measurement. Ion concentrations in demineralizing solution were measured using inductively coupled plasma atomic (ICP) emission spectrometry and an ion electrode. The nail varnish group and the non-S-PRG filler group showed linear demineralization. Although the nail varnish group and the non-S-PRG filler group showed linear demineralization, the S-PRG filler group did not. Further, plane-scanning by EPMA analysis in the S-PRG filler group showed no changes in Ca ion distribution, and F ions showed peak levels on the surface of enamel specimens. Most ions in the demineralizing solution were present at higher concentrations in the S-PRG filler group than in the other two groups. In conclusion, only the S-PRG filler-containing tooth-coating material released ions and inhibited demineralization around the coating. 1. Introduction In recent years, oral health in developed countries has improved, with the majority of people keeping more sound teeth for longer duration [1–7]. In particular, considerable interest has been directed at detecting caries at early stages, with the development of the International Caries Detection and Assessment System (ICDAS) [8, 9] and quantitative light-induced fluorescence (QLF) method [10, 11]. In current daily dental practice and oral health care programs, the inhibition of initial tooth enamel demineralization and the promotion of remineralization are the most important targets [12–14]. Surface-reaction type prereacted glass-ionomer (S-PRG) filler [15, 16] has been reported to have biological efficacy in reducing dental plaque formation [17, 18], inhibition of dentin demineralization [19], fluoride release and recharge potential [20], and prevention of demineralization in surrounding orthodontic brackets [21]. These efficacies might be due to the ability of S-PRG filler to release various ion species (fluoride, strontium, aluminum, sodium, etc.) as well as its capacity as an acid buffer [22]. S-PRG filler can therefore be found in various dental products, such as composite resin, root canal sealer, orthodontic resin bonding systems, and denture base resin [19, 23–28]. We developed a novel ion-releasing tooth-coating material
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