Indiana University-Purdue University Indianapolis (IUPUI) / BACKGROUND Several studies have reported that harder enamel with higher contents of calcium (Ca), phosphorus (P) and fluorine (F) coupled with lower contents of carbonate (C), magnesium (Mg) and nitrate (N) was found to be more resistant to demineralization. Additionally, the hardness of dental enamel was found to have a strong correlation with its chemical content. However, yet to be established is the relation between the physical and chemical structure of enamel and its response to de- and remineralizing conditions. OBJECTIVES The aims of this laboratory study were: 1) To investigate the hardness and chemical content of sound enamel and their influence on demineralization; 2) To investigate these properties in demineralized enamel and their influence on remineralization; and 3) To investigate these properties in sound enamel and their influence on remineralization. MATERIALS AND METHODS Incipient subsurface caries lesions were created in 94 bovine enamel specimens using Carbopol C907 using three demineralization times. The specimens were then pH-cycled and treated using either 367 ppm F sodium fluoride or a placebo. Knoop surface microhardness (SMH), Energy dispersive X-ray spectroscopy (EDS) and Transverse microradiography (TMR) were performed on the specimens at all stages and compared between them. TMR variables included integrated mineral loss (ΔZ), Lesion depth (L) and maximum mineral density of the surface zone (SZmax). Data were analyzed using three- and four-way ANOVA and Pearson correlation coefficients were calculated. RESULTS SMH, ΔZ, L and SZmax were significantly different among stages, demineralization times and treatment. The weight% of F at the surface was significantly affected by treatment, irrespective of demineralization time. A statistically significant moderate correlation was found between SZmax and ΔZ and SZmax and L after pH cycling. SMH also correlated weakly to moderately with TMR data. CONCLUSIONS SMH and SZmax decreased while ΔZ and L increased with increased demineralization time. Both fluoride and non-fluoride specimens were able to remineralize, which emphasizes the role of saliva in mineralization. The Ca:P ratio remained stable at various stages, indicating the stoichiometric dissolution and redeposition of minerals. The greatest deposition of F was at the surface and its increase led to an increase in SMH and SZmax. SMH values showed that harder specimens at baseline and after demineralization remained hard after demineralization and pH-cycling, respectively, although this correlation was weak. Additionally, harder lesions showed less L and ΔZ and greater SZmax. RELEVANCE This in-vitro study will help better understand the caries process and the impact of physical and chemical characteristics of enamel on de- and remineralization challenges.

Identification of an appropriate material capable of enamel remineralization to fill a cavity after the removal of dental tissue is a new field of dental research. Elucidation of the associated factors involved in enamel defects remain in question including the mechanisms of enamel hypoplasia as well as improvement needed in our current treatment models. The purpose of this thesis is to evaluate the factors associated with enamel defects, to understand the mechanism by which they evolve, as well as look into a new method of treatment called, fluorapatite cement. This new treatment has shown promising affects to improve our current treatment to restore enamel defects, however, to find the best treatment we must understand the foundations of enamel and how defects arise. Enamel is the strongest tissue in the body because it must maintain resistance to factors such as bacterial adhesion, acidity, and temperature. Enamel defects can present as white spots, discoloration, or deep fissures in the enamel due to a disturbance that occurred during tooth oogenesis. Enamel hypoplasia provides favorable conditions for the early development of caries and the retention of plaque, which can progress and reach deep into the enamel and the dentin and cause sensitivity. Our current treatment is efficient and has been used for decades, however, requires the surrounding health enamel to be removed. This is a disadvantage and has encouraged scientists to continue researching for an effective way to remineralize enamel and avoid the loss of healthy enamel. Diseases such as coeliac disease have an influence on the formation of enamel that lead to defects. A recent study investigated if dentists can play a role in early diagnosis of diseases including coeliac disease by examining patients for enamel defects. The study discovered that there was not a significant difference in oral evaluations to determine upon early diagnosis, however, they did conclude that there was pattern in the types of defects that were found in coeliac patients. Specifically, grade I and II defects were found on the anterior teeth of coeliac patients, therefore, the study still recommends seeing the dentist for oral exams as well as supports further study. To understand the mechanism of how defects arise, scientists studied first permanent molars in children during their first three years of life with factors including, institutionalization, gender, medications, and diseases. Studies showed that females have a two-fold risk for enamel defects over males and institutionalized children have a three-to-four-fold risk of enamel defects. To improve our current treatment and avoid loss of healthy enamel and a costly procedure, scientists are looking into the use of hydroxyapatite (HA), a natural occurring mineral in our body, to create a possible new synthetic enamel called fluorapatite (FA) cement. Research analyzed fluorapatite cement compared to natural enamel and found that FA cement has a stronger resistance to acidity with a weight loss of 0.75% wt% compared to enamel with 1.2% and greater resistance to bacterial adhesion than natural enamel by three times. FA cement was also found to have more stability and higher cellular activity than hydroxyapatite. As for safety for dental application, FA cement and HA were placed in simulated body fluid to test for cytotoxicity levels, and none were present. Therefore, FA cement has a promising approach to restore enamel defects effectively and conveniently. Further research is recommended to understand the association of females and institutionalized children with enamel defects versus all children in a larger study group. The current reported results from fluorapatite cement are very promising. This cement can allow an inexpensive and more efficient method of treatment due to its abilities to remineralize enamel that even stronger than natural enamel. The recent hydroxyapatite and fluoride toothpaste products show the growing research that is being put into this idea of creating a synthetic enamel with our current mineral hydroxyapatite. This thesis supports the idea that FA cement has the potential as an alternative to current treatment for enamel defects and hopefully will be ready to undergo a clinical trial in the near future.

No description available.

No / Dental Enamel Hypoplasia has long been used as a common nonspecific stress indicator in teeth from archaeological samples. Most researchers report relatively minor linear and pitted hypoplastic defects on tooth crown surfaces. In this work we report a high prevalence and early age of onset of extensive enamel defects in deciduous and permanent molars in the subadults from the post-medieval cemetery of Broadgate, east central London. Analysis of the dentition of all 45 subadults from the cemetery, using both macroscopic and microscopic methods, reveals disturbed cusp patterns and pitted, abnormal and arrested enamel formation. Forty-one individuals from this group (93.2%) showed some evidence of enamel hypoplasia, 28 of them showing moderate or extensive lesions of molars, deciduous or permanent (63.6% of the sample). Scanning Electron Microscope images reveal many molars with grossly deformed cuspal architecture, multiple extra cusps and large areas of exposed Tomes' process pits, where the ameloblasts have abruptly ceased matrix production, well before normal completion. This indented, rough and poorly mineralized surface facilitates both bacterial adhesion and tooth wear, and when such teeth erupt fully into the mouth they are likely to wear and decay rapidly. We suggest that this complex combination of pitted and plane-form lesions, combined with disruption of cusp pattern and the formation of multiple small cusps, should henceforth be identified as Cuspal Enamel Hypoplasia.

Orientador: Renato Herman Sundfeld / Banca: André Luiz Fraga Briso / Banca: Paulo Henrique dos Santos / Banca: Marcelo Giannini / Banca: Márcio Grama Hoeppner / Resumo: O objetivo deste estudo clínico foi avaliar os efeitos da associação de técnicas clareadoras com peróxido de hidrogênio (clareamento de consultório) e de carbamida (clareamento caseiro), na alteração de cor, sensibilidade dental, na morfologia e rugosidade superficial do esmalte dental. Fizeram parte dessa pesquisa clínica 21 voluntários, com faixa etária de 18-25 anos. Foram utilizados, de acordo com as especificações do fabricante, o produto clareador a base de peróxido de hidrogênio a 38% Opalescence Boost PF (Ultradent Products Inc., UT, EUA) e o a base de peróxido de carbamida a 10% Opalescence (Ultradent Products Inc., UT, EUA). O fator em estudo foi a "técnica clareadora" em 2 níveis: Técnica 1 (clareamento de consultório associado com clareamento caseiro) e Técnica 2 (apenas clareamento caseiro). Inicialmente, os voluntários tiveram suas hemi-arcadas superiores direita ou esquerda submetidas ao clareamento de consultório com 3 aplicações de 15 minutos cada de peróxido de hidrogênio a 38% ou placebo (Fase 1), respectivamente, caracterizando assim, um delineamento tipo split-mouth ou de boca dividida. Durante os 7 dias seguintes à Fase 1, os voluntários realizaram o clareamento caseiro utilizando o peróxido de carbamida a 10%, por 4 horas diárias (Fase 2) em ambos os lados; a Fase 1 e 2 foram repetidas por mais uma vez na semana seguinte. A mensuração da variável alteração de cor foi realizada nos incisivos e caninos superiores, pelo método visual (Vita Classical, Vita Zahnfabrik, Germany) e digital (Vita Easyshade, Vita Zahnfabrik, Germany), antes e após a Fase 1 e ao final do experimento; a variável sensibilidade foi analisada pelo método analógico visual; enquanto que as alterações da superfície de esmalte e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this clinical study was to evaluate the association between two dental bleaching techniques - hydrogen peroxide bleaching (in-office bleaching) and carbamide peroxide (home bleaching) - and color change, dental sensitivity, morphology, and superficial roughness of dental enamel. Were performed two applications according to the manufacturer's specifications, one per week, of the in-office bleachingwith38% hydrogen peroxide. We applied the home bleaching technique for two weeks with 10% carbamide peroxide in a custom-made tray. The factor studied was the "bleaching technique" on 2 levels: Technique 1 (in-office bleaching associated with home bleaching) and Technique 2 (home bleaching only).The response variables were color change, dental sensitivity, morphology, and superficial roughness. According to a random draw, the volunteers had their maxillary right and left hemi arches submitted to in-office placebo treatment and to in-office bleaching, respectively (Phase 1), and at home bleaching (Phase 2) treatment for both hemi-arches, characterizing a split-mouth type of design. The color change was performed in the incisor and canine teeth by visual and digital evaluation before and after phase 1 and after the conclusion of each session of attendance. The dental sensitivity was assessed using the visual analogical method whereas the enamel surface changes and roughness were analyzed by electron microscopy (SEM) and by optical interferometry (IFM), through replicas clinically obtained based on central incisors before and after bleaching procedures. No differences were observed between the bleaching techniques for both the visual and digital analysis. There was a significant difference in the dental sensitivity... (Complete abstract click electronic access below) / Doutor

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

No description available.

published_or_final_version / abstract / Dentistry / Doctoral / Doctor of Philosophy

La microstructure de l'émail est étudiée depuis longtemps, mais ses modalités de formation sont encore floues. J'ai employé une approche multi-disciplinaire alliant paléontologie et biologie cellulaire dans une perspective évolution-développement afin de parvenir à une vision intégrée et en profondeur de la microstructure, de sa morphologie et de ses modes de formation. J'ai ainsi pu décrire en 2D l'évolution de la microstructure chez un grand groupe de mammifères fossiles et actuels, les cétartiodactyles, qui ont révélé que tous les caractères de l'émail ne se valent pas, et font état de différentes contraintes développementales les rendant plus ou moins labiles aux changements évolutifs. J'ai également travaillé au niveau cellulaire et en 3D avec des modèles actuels, en particulier des rongeurs, sur les rapports entre les prismes d'émail et leurs cellules sécrétrices, les améloblastes, révélant que l'agencement de ces derniers contribue en grande part à la morphologie de la microstructure. Enfin, j'ai réalisé une démarche de synthèse, en proposant un modèle de la microstructure de l'émail chez les mammifères sur la base de mes données 2D+3D. Il en est ressorti d'une part un nouveau logiciel de reconstruction virtuelle de la microstructure, Simulémail, et il a été mis en évidence différents moyens de générer la décussation chez les mammifères, ainsi que les probables mécanismes développementaux sous-jacents. / I approached enamel microstructure's morphology and modes of formation with a dual angle, combining paleontological and cellular biology observations, in 2D and 3D. Studying microstructure of extinct and extant Cetartiodactyla in a phylogenetic context, I discovered that some enamel characters are more likely to evolve and change than others, which is linked to different developmental constrains. I also explored microstructure through the relationship between enamel prisms and ameloblasts, the enamel-secreting cells, showing that the arrangement of the cells is directly associated with the prisms'. Then, combining these data, I constructed a model of mammalian enamel microstructure based on 2D and 3D observations and suggested underlying cellular mechanisms, and created a new software dedicated to enamel reconstruction, Simulémail, based on this model. It helped to show that microstructure is not always created the same way for different mammals, and allowed to explore enamel characters efficiently.

Orientador: Alessandra Nara de Souza Rastelli / Resumo: O objetivo deste estudo in vitro foi avaliar a eficácia de diferentes técnicas de clareamento dental, através das análises de dureza e contéudo mineral do esmalte dental clareado. Diferentes protocolos foram testados após manchamento dos espécimes com (café), como segue: G1: Whiteness HP Maxx (FGM); G2: Whiteness HP Maxx (FGM) + LED Azul - Twin Flex Evolution (MMOptics); G3: Whiteness HP Maxx (FGM) + LED Violeta - Bright Max Whitening (MMOptics); G4: Peróxido de Hidrogênio a 10% (FGM); G5: Peróxido de Hidrogênio a 10% (FGM) + Led Violeta - Bright Max Whitening (MMOptics); G6: Peróxido de Carbamida a 22% (FGM); G7: Peróxido de Carbamida a 22% (FGM) + LED Violeta - Bright Max Whitening (MMOptics) e G8: LED Violeta - Bright Max Whitening (MMOptics). Foram obtidos oitenta (n=80) espécimes de (4x4x2mm) da face vestibular de incisivos bovinos, após foram seccionados ao meio em máquina de corte, separando cada espécime em duas metades, uma metade foi utilizada como espécime sem procedimento clareador (controle) e a outra metade como espécime com procedimento clareador (tratado). Foi realizada análise em profundidade no esmalte, afim de verificar as possíveis alterações na superficíe (S) e subsuperficie (P), assim, cento e sessenta (n=160) espécimes foram avaliados quanto microdureza Knoop (n =10) e espectroscopia Raman (n = 5). Os diferentes protocolos para clareamento dental foram aplicados de acordo com os fabricantes dos produtos e dos equipamentos. Os espécimes permaneceram em s... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this in vitro study was to evaluate the effectiveness of different dental bleaching techniques through microhardness analysis and mineral content of bleached dental enamel. Different protocols were tested after spotting the specimens with (coffee), as follows: G1: Whiteness HP Maxx (FGM); G2: Whiteness HP Maxx (FGM) + Blue LED - Twin Flex Evolution (MMOptics); G3: Whiteness HP Maxx (FGM) + Violet Led - Bright Max Whitening (MMOptics); G4: 10% Hydrogen Peroxide (FGM); G5: 10% Hydrogen Peroxide (FGM) + Violet Led - Bright Whitening (MMOptics); G6: 22% carbamide peroxide (FGM); G7: 22% Carbamide Peroxide (FGM) + LED Violet - Bright Max Whitening (MMOptics) and G8: Violet LED - Bright Max Whitening (MMOptics). Eighty (4x4x2mm) specimens were collected from the bovine incisal vestibular surface, after being sectioned in the cutting machine, separating each specimen into two halves, one half was used as a specimen without bleaching procedure (control) and the other half as a specimen with bleaching procedure (treated). To verify the possible changes in surface (S) and subsurface (P), one hundred and sixty (n = 160) specimens were evaluated for Knoop microhardness (n = 10) and Raman spectroscopy (n = 5). The different dental bleaching protocols were applied according to the manufacturers of the products and equipment. The specimens remain in artificial saliva at 37 ° C throughout the experiment period and are replaced weekly. Changes in bovine dental enamel were eva... (Complete abstract click electronic access below) / Mestre