Effectiveness of different surface treatments on bond strength between 3D-printed teeth and denture base.

PURPOSE: To investigate the effects of different surface treatments and thermal cycling on the shear bond strength between 3D-printed teeth and denture bases. MATERIAL AND METHODS: For the shear bond strength (SBS) test, the specimens were the maxillary central incisors (11 × 9 × 7 mm) bonded on a cylindrical base (20 × 25 mm). The control group was heat-cured polymethylmethacrylate (PMMA) (N = 20). The printed group was divided into five subgroups (N = 20): no treatment, sandblasting with aluminum oxide (Al2O3), methyl methacrylate monomer, acetone, and adhesive with urethane dimethacrylate. Half of the samples were subjected to 2000 thermal cycling cycles, and all samples were subjected to the SBS test. The failure mode was established as adhesive, cohesive, or mixed through stereomicroscopic analysis. The surface roughness test (Sa) was performed using optical profilometry, and the rectangular specimens (14 × 14 × 2.5 mm) were divided into four groups according to the surface treatments (N = 7 per group). Paired T and Wilcoxon tests were conducted to perform comparisons within the same group. The Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner post-hoc tests were conducted to compare the groups. RESULTS: Al2O3 sandblasting in the 3D-printed groups achieved high SBS values comparable to those of the control group in the thermal cycled (p = 0.962) and non-thermal cycled samples (p = 0.319). It was the only treatment capable of modifying the surface of the 3D-printed resin, thereby increasing the roughness (p = 0.016). CONCLUSIONS: Sandblasting is recommended to increase the bond strength between the tooth and denture bases.

Avaliação qualitativa de dentes artificiais de resina acrílica após escovação simulada / Qualitative evaluation of artificial acrylic resin teeth after simulated brushing

Introdução: os dentes artificiais de resina acrílica são amplamente utilizados na confecção de próteses, por apresentarem propriedades físicas, mecânicas e biológicas, além de características de fácil manuseio. No entanto, devido sua característica de baixa resistência à abrasão, a escovação pode levar à perda de massa dos dentes artificiais e aumento da rugosidade. Objetivo: avaliar de forma qualitativa a rugosidade superficial e polimento de dentes artificiais das marcas Hereaus Premium; Trilux e Vita, após período de 1 ano de escovação, com fotografias em Lupa Estereoscópica. Metodologia: para a realização deste estudo, serão utilizados 10 dentes artificiais de cada marca comercial (Trilux, Vita e Hereaus Premium). Os dentes serão fixados com resina ortoftálica em tubo de PVC de 15 mm de espessura. Para o teste de abrasão, será usada uma máquina de escovação simulada com escovas de dentes de cerdas macias e solução de pasta de dente. As imagens serão obtidas com câmera digital acoplada a lupa estereoscópica. A rugosidade superficial e o polimento serão analisados antes da escovação simulada e após 12 meses de escovação através das imagens. Resultados: após o teste de abrasão foi observado a presença de um desgaste superficial e/ou ranhuras na superfície dos dentes artificiais em todos os grupos. Porém não houve um padrão similar entre os corpos de prova de um mesmo grupo. Conclusão: Pode-se concluir que a escovação provocou o aumento da rugosidade superficial e alteração no polimento em todos os dentes artificiais utilizados.

Introduction: acrylic resin artificial teeth are widely used in the manufacture of dentures, as they have physical, mechanical and biological properties, in addition to easy handling characteristics. However, due to its characteristic of low abrasion resistance, brushing can lead to loss of mass of artificial teeth and increase in roughness. Objective: qualitatively evaluate the surface roughness and polishing of artificial teeth of Hereaus Premium brands; Trilux and Vita, after a 1-year brushing period, with photographs using a Stereoscopic Magnifying Glass. Methodology: for this study, 10 artificial teeth of each commercial brand will be used (Trilux, Vita and Hereaus Premium). Teeth will be fixed with orthophthalic resin in a 15 mm thick PVC tube. For the abrasion test, a simulated brushing machine with soft bristle toothbrushes and toothpaste solution will be used. Images will be obtained with a digital camera coupled to a stereoscopic magnifying glass. Surface roughness and polishing will be analyzed before simulated brushing and after 12 months of brushing through the images. Results: after the abrasion test, the presence of surface wear and/ or grooves on the surface of the artificial teeth was observed in all groups. However, there was no similar pattern between the specimens of the same group. Conclusion: it can be concluded that brushing caused an increase in surface roughness and change in polishing in all artificial teeth used.

The Effect of a Continuous Mechanical Polishing Protocol on Surface Roughness, Biofilm Adhesion, and Color Stability of Acrylic Resin Artificial Teeth.

PURPOSE: Acrylic resin properties are susceptible to change over the duration of use, thereby decreasing prosthesis longevity. To make the material less susceptible to the action of external agents such as stain-causing liquids and cleaning solutions, polishing procedures are recommended. A specific mechanical polishing procedure performed regularly was evaluated regarding the biofilm adhesion, surface roughness (Ra), color stability (ΔE), and mass changes in acrylic resin artificial teeth. MATERIALS AND METHODS: Sixty artificial teeth divided into two groups (n = 30) were immersed in distilled water (WT) and coffee (CF). These groups were then subdivided (n = 10) according to the type of polishing procedure administered: no polishing, biweekly polishing (once every 2 weeks) (pol 1), or monthly polishing (once a month) (pol 2), using aluminum oxide paste and a felt polishing wheel attached to an electric motor at a speed of 3000 rpm. Properties were evaluated at baseline and after 4, 8, 12, and 24 months of simulated immersion. At the end, the adhesion of Candida albicans and Streptococcus mutans multispecies biofilm in all groups was assessed. RESULTS: The CF group showed an increased Ra and weight, and a significantly greater ΔE compared to the WT group. The polishing procedure reduced Ra and minimized the stains caused by coffee, without losing mass, with the biweekly regime more effective than the monthly regime. Also, polishing reduced the adhesion of biofilm in the CF groups, again with the biweekly regime the most effective. CONCLUSIONS: When performed regularly, the mechanical polishing procedure tested reduces the changes in artificial teeth subjected to immersion in coffee, with the biweekly frequency most effective regarding the properties evaluated.

Alteração de cor em dentes de estoque após imersão em café e refrigerante / Color alteration in stock teeth after immersion in coffee and soft drink

Os dentes de estoque são dentes artificiais utilizados para a confecção de próteses, sendo que a resina acrílica tem sido o material de eleição devido às suas inúmeras vantagens, porém, assim como qualquer outro material, possui suas desvantagens, dentre elas: instabilidade de cor. O uso diário de bebidas ácidas em geral, como café e refrigerantes, tem tornando-se cada vez mais frequente, podendo comprometer a estética alterando a cor dos dentes artificiais. Assim, o avanço tecnológico tem almejado o melhoramento da composição dos dentes de estoque. Este estudo teve como objetivo analisar a alteração de cor de dentes de estoque de diferentes marcas após serem submetidos à submersão em dois líquidos com potencial de coramento. Foram selecionadas três marcas de dentes: Pop Dent (DentBras®), Biolux (Vipi®) e Trilux (Vipi®), sendo utilizados 15 incisivos centrais superiores direitos de cada marca. Tais dentes foram imersos em café e Coca-Cola®. A avaliação da alteração da cor foi feita por espectrofotometria, nos intervalos de 7, 15 e 30 dias, sendo os dados obtidos submetidos à análise estatística. Observou-se que os dentes Pop Dent (DentBras®) apresentaram alterações estatisticamente significantes nos três intervalos de tempo para os dois líquidos; os Biolux (Vipi®) apenas após 15 dias e os Trilux (Vipi®) evidenciaram alteração estatisticamente significante apenas com 30 dias para o café e 15 dias para a Coca-Cola®. O café e a Coca-Cola® apresentaram o potencial de manchamento semelhante um ao outro (AU).

Stock teeth are artificial teeth used to make prostheses, and acrylic resin has been the material of choice because of its numerous advantages, but, like any other material, it has its disadvantages, among them: color instability. The daily use of acidic beverages in general, as coffee and soft drinks, has become increasingly frequent and can compromise the aesthetics by altering the color of artificial teeth. So technological advance has been aiming the improvement of stock teeth composition. The aim of this study was to analyze color change of different brands of stock teeth after being submitted to submersion in two liquids with stain potential. Three different teeth brands were selected: Pop Dent (DentBras®), Biolux (Vipi®) and Trilux (Vipi®), 15 central superior incisors of each brand were used. These teeth were immersed in coffee and Coca-Cola®. The color change was evaluated by spectrophotometry, at intervals of 7, 15 and 30 days, the data was submitted to statistical analysis. It was observed that the Pop Dent teeth (DentBras®) presented statistically significant changes in the three time intervals for the two liquids; the Biolux (Vipi®) only after 15 days and the Trilux (Vipi®) showed statistically significant alteration only in 30 days for coffee and 15 days for Coca-Cola®. Coffee and CocaCola® showed the potential for staining similar to each other (AU).

Estabelecimento de uma proporção entre largura de dentes artificiais anteriores, medidos em curva e em linha reta / Establishing a ratio between the width of anterior artificial teeth measured in curved and straight configurations

Objetivo: estabelecer uma proporção única de redução entre a medida da largura dos seis dentes artificiais anteriores superiores, em curva e em linha reta. Material e métodos: foi utilizado um dispositivo pré-fabricado, simulando o plano de cera superior, no qual foram montados os dentes (Premium, Heraeus-Kulzer Inc. ­ Hanau, Alemanha) nos seguintes modelos: T2, O2, R2, S2, S4, O4, S6, R4, R6, T4 e T6. Em seguida, a largura em curva entre os dentes anteriores montados foi medida com uma régua flexível, tendo como referência a face distal dos caninos. A partir dos dados obtidos (mm) e dos valores das medidas fornecidos na carta molde do fabricante, realizou-se o cálculo da proporção entre essas duas medidas para cada modelo de dentes. Resultados: verificou-se redução entre a medida em curva e a medida em linha reta, variando de 4% a 19% para todos os tipos de modelos estudados. Assim, não foi possível estabelecer uma porcentagem padrão única de redução para todos os tipos de dentes do fabricante. Porém, agrupando-se a redução em milímetros, observou-se uma redução variável entre os modelos em curva e em linha reta: 2 mm para o modelo T2; 3 mm para os modelos O2, R2, S2 e S4; 4 mm para os modelos O4 e S6; 5 mm para os modelos R4, R6 e T4; e 9 mm para o modelo T6. Conclusão: é possível estabelecer uma redução aproximada (em mm) entre uma medição em curva e reta na seleção de dentes artificiais Premium/Heraeus-Kulzer.

Objective: this study aimed to establish a single rate reduction between the measurement of the width of the six artificial anterior upper teeth, in curved and straight configurations. Methods: for this, a prefabricated device simulating the upper wax rim was used and received artificial teeth (Premium, Heraeus-Kulzer Inc., Hanau, Germany) from T2, O2, R2, S2, S3, O4, S6, R4, R6, T4, and T6. Next, the width of the six anterior teeth in curvature was measured from the distal of both canines. After, based on the mold chart of the manufacturer, the ratio between the straight and curved configurations was generated. Results: there was a 4% to 19% in reduction between the curved and straight configurations. A single reduction percentage was not obtained for all tooth forms. However, the reductions were 2 mm for T2, 3 mm for O2, R2, S2 and S4; 4 mm for O4 and S6; 5 mm for R4, R6, and T4; and 9 mm for T6 models. Conclusion: it is possible to establish an approximated reduction (in mm) between the curved and straight configurations for Premium/Heraeus-Kulzer artificial teeth.

Bond Strength of Artificial Teeth Attached to a Microwave-Polymerized Denture Base Resin after Immersion in Disinfectant Solutions.

PURPOSE: To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. MATERIALS AND METHODS: Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (α = 0.05). RESULTS: Biotone IPN showed similar results among the groups (distilled water, 8.25 ± 1.81 MPa; chlorhexidine, 7.81 ± 3.34 MPa; hypochlorite, 7.75 ± 3.72 MPa; and Corega Tabs, 7.58 ± 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 ± 3.27 MPa) and chlorhexidine (6.08 ± 2.35 MPa). CONCLUSIONS: Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.

Nova técnica para a seleção da largura dos dentes anterossuperiores utilizando a proporção áurea / New technique to determine the width of maxillary anterior teeth using the golden ratio

A seleção da largura dos dentes anterossuperiores na ausência de referências dentais é um procedimento complexo, sendo proposta uma avaliação da relação entre a largura dos seis dentes anteriores superiores, a distância entre a linha média dos incisivos centrais superiores à distal do canino superior e a distância das vertentes vestibulares dos caninos com as falanges média e proximal do dedo médio das mãos, bem como com a distância entre as comissuras bucais utilizando a proporção áurea. Foram utilizados o compasso de proporção áurea e o paquímetro digital para mensuração das falanges média e proximal do dedo médio, da distância entre as comissuras bucais e diretamente sobre os dentes. Foi posicionada uma tira de papel demarcando a distal do canino superior do lado direito e esquerdo, a linha média entre os incisivos centrais e as vertentes dos caninos superiores e, posteriormente, medidas com paquímetro digital. Foram avaliados 150 indivíduos, com idade entre 18 e 40 anos, sem alterações na face ou mãos, com sorrisos considerados estéticos, com ausência de giroversões, aparelho ortodôntico e próteses. A falange proximal do dedo médio pode ser utilizada para determinar a largura dos seis dentes anteriores superiores. As vertentes dos caninos, bem como a distância da linha média do incisivo central à distal do canino do mesmo lado, não tiveram correlação com a comissura bucal, falange proximal e média. Concluiu-se que a utilização da falange proximal do dedo médio é uma opção segura para a obtenção da largura dos seis dentes anteriores superiores (AU)

The selection of the width of maxillary anterior teeth in the absence of remaining teeth is a complex procedure. Thus it is indicated an evaluation of the relationship between the width of the six maxillary anterior teeth, the distance between maxillary central incisors' midline to the upper canine distal, and the distance of the vestibular slopes of upper canines, using the middle and proximal phalanges of the middle finger, as well as the distance between oral commissures using the golden ratio. Golden proportion compass and the digital calipers were used to measure the middle and proximal phalanges of the middle finger, the distance between oral commissures and to obtain direct measure of the teeth. A strip of paper was placed to mark: the maxillary canine distal on the right and left side, the midline between central incisors and the slopes of upper canine that were subsequently measured using a digital caliper. This study has evaluated 150 subjects, age between 18 and 40 years, with no facial or hand alterations, with aesthetics smiles and no teeth rotations, teeth braces or prostheses. The proximal phalange of the middle finger may be used to determine the width of the six maxillary anterior teeth. There was no correlation between the distance from the maxillary central incisors' midline to the upper canine distal (same side) and oral commissure, proximal and middle phalanges. It was concluded that the use of the proximal phalanx of the middle finger is a safe option to determine the width of the six maxillary anterior teeth (AU)

Surface properties of multilayered, acrylic resin artificial teeth after immersion in staining beverages

AbstractObjective To evaluate the effect of staining beverages (coffee, orange juice, and red wine) on the Vickers hardness and surface roughness of the base (BL) and enamel (EL) layers of improved artificial teeth (Vivodent and Trilux).Material and Methods Specimens (n=8) were stored in distilled water at 37°C for 24 h and then submitted to the tests. Afterwards, specimens were immersed in one of the staining solutions or distilled water (control) at 37°C, and the tests were also performed after 15 and 30 days of immersion. Data were analyzed using 3-way ANOVA and Tukey’s test (α=0.05).Results Vivodent teeth exhibited a continuous decrease (p<0.0005) in hardness of both layers for up to 30 days of immersion in all solutions. For Trilux teeth, similar results were found for the EL (p<0.004), and the BL showed a decrease in hardness after 15 days of immersion (p<0.01). At the end of 30 days, this reduction was not observed for coffee and water (p>0.15), but red wine and orange juice continuously reduced hardness values (p<0.0004). Red wine caused the most significant hardness changes, followed by orange juice, coffee, and water (p<0.006). No significant differences in roughness were observed for both layers of the teeth during the immersion period, despite the beverage (p>0.06).Conclusions Hardness of the two brands of acrylic teeth was reduced by all staining beverages, mainly for red wine. Roughness of both layers of the teeth was not affected by long-term immersion in the beverages.

Color stability of artificial teeth after exposure to acid and staining agents / Estabilidade de cor de dentes artificiais após a exposição a agentes ácidos e corantes

Alterações na cor dos dentes artificiais ocorrem principalmente devido à ingestão de bebidas e uso de produtos de limpeza e desinfecção de próteses. Soluções mais agressivas de limpeza devem ser identificadas e o paciente deve ser informado, a fim de evitar ou reduzir a frequência de seu uso, para maior longevidade de próteses. O objetivo deste estudo foi avaliar as alterações na cor de dentes artificiais antes e após imersão em bebidas e soluções desinfetantes. Material e Métodos: noventa e seis dentes artificiais de resina foram aleatoriamente divididos em 8 grupos. Cada grupo foi imerso por 10 min em uma solução de teste (café, suco de limão, gluconato de clorexidina, vinho tinto, refrigerantes à base de cola, vinagre ou antisséptico com e sem álcool) e, em seguida, os espécimes foram armazenados em saliva artificial durante 23 horas e 50 min, perfazendo um período de 24 h. Este procedimento foi realizado durante 14 dias consecutivos e depois desse período a segunda medição de cor foi feita. Os dados obtidos com o espectrofotômetro usando o CIEL * a * b * foram analisados através de ANOVA não paramétrico, Kruskal-Walis e o teste de Dunn. Resultados: Foram verificadas diferenças na variação de cor para cada grupo experimental após o desafio. As diferenças estatisticamente significativas foram encontradas entre os grupos de café, vinho tinto e suco de limão. Conclusão: Todas as substâncias mudaram a cor dos dentes artificiais; café foi a substância que causou mais descoloração dos dentes artificiais, alterando a cor e luminosidade; os antissépticos bucais com e sem álcool promoveram clareamento dos dentes artificiais...

Changes in color of artificial teeth mainly occur due to ingestion of beverages and use of products for cleaning and disinfection. More aggressive solutions must be identified and the patient provided with explanations in order to avoid or reduce the frequency of their use, to higher longevity of dentures. The purpose of this study was to evaluate changes in color of artificial teeth before and after immersion in beverages and disinfectants. Material and Methods: 96 artificial resin teeth were randomly divided into 8 groups. Each group was immersed for 10 min into a test solution (coffee, lemon juice, chlorhexidine gluconate, red wine, cola-based soft drink, vinegar or antiseptic with and without alcohol) and then the specimens were stored in artificial saliva for 23 h and 50 min, completing a period of 24 h. This procedure was performed for 14 consecutive days and after this period the second color measurement was made. Data obtained with the spectrophotometer using the CIEL*a*b* system were statistically analyzed using ANOVA non parametric, Kruskal-Walis and the Dunn test. Results: There were found differences in color variation for each experimental group after the challenge. Statistically significant differences were found among coffee, red wine and lemon juice groups. Conclusion: All substances changed the color of artificial teeth; coffee was the substance that caused most staining of artificial teeth, altering color and luminosity; the oral antiseptics with and without alcohol promoted whitening of the artificial teeth...

A method of comparing the wear resistance of various materials used for artificial teeth / Um método de comparação de resistência de desgaste de materiais usados para dentes artificiais

OBJECTIVE: Abrasion resistance of three commercial brands of acrylic resin for artificial teeth, available on the domestic market (Biotone(r), Plus(r) and Vipi Dent Artiplus(r)) was evaluated by a new methodology called "Pirassununga Method ". METHODS: The Manufacturers produced the maxillary central incisor-shaped incisal resin specimens (n=27). These were embedded in chemically activated acrylic resin in an insulated metal matrix to fabricate test specimens, which were flattened on a lathe and refined manually with sandpaper. Wear testing was conducted in an experimental machine at the Vipi dental products factory. In the "Pirassununga Method" a polished metal sphere 4.8 mm in diameter, attached to a rotary device passes over the fixed specimens in programmable cycles, under 5N pressure, using distilled water as lubricant. In each sample, the groove caused by abrasion, was analyzed in two ways: Readout under a microscope to determine the breadth and depth of the groove caused by the ball, and by laser roughness meter readout, which obtained a value Rt. RESULTS: The nonparametric Kruskal Wallis test showed no statistically significant difference between the medians of brands evaluated in the cycles performed (p = 0.936). CONCLUSION: Artiplus(r) Brand showed a lower tendency to wear than commercial brands Biotone(r) and Plus(r) Vipi Dent, with the best performance shown for the IPN polymer. .

OBJETIVO: Avaliar a resistência ao desgaste por abrasão de três marcas comerciais de dentes artificiais de resina acrílica disponíveis no mercado nacional (Biotone(r), Vipi Dent Plus(r) e Artiplus(r)) por meio de uma nova metodologia. MÉTODOS: Os corpos de prova foram produzidos pelos fabricantes, com resina incisal em forma de incisivos centrais superiores (n=27). Esses dentes foram incluídos em resina acrílica ativada quimicamente dentro de uma matriz de metal isolada para confecção dos corpos de prova, e depois aplainados em torno mecânico e refinados com lixa d'agua manualmente. O ensaio do desgaste foi realizado em uma máquina experimental presente na fábrica de produtos odontológicos Vipi. No "Método Pirassununga" uma esfera metálica polida de 4,8 mm de diâmetro presa em um dispositivo que rotaciona, passa sobre os corpos de prova que estão fixos, em ciclos que podem ser programados, e tendo água destilada como lubrificante e pressão de 5N. O sulco provocado pela abrasão em cada corpo de prova foi analisado de duas maneiras: Leitura em microscópio para determinar a largura e a profundidade do sulco provocado pela esfera e rugosímetro de leitura a laser, do qual foi obtido o valor Rt. RESULTADOS: Por meio do teste não paramétrico de Kruskal Wallis observou-se que não houve diferença estatisticamente significante entre as medianas das marcas avaliadas nos ...

Microhardness in pressing layers of prefabricated modified acrylic resin teeth / Microdureza nas camadas de prensagem de dentes pré-fabricados em resina acrílica modificada

OBJECTIVE: The aim of this study was to evaluate the microhardness in pressing layers of prefabricated modified acrylic resin teeth. METHODS: Lower first molar teeth with two (Biotone(r) IPN and Bioform(r)) or three pressing layers (Artiplus(r), Trilux(r) Eurovipi, and Natusdent(r)) were hemisected in a bucco-lingual plane and embedded in a self-curing acrylic resin (n =10). Specimens were then ground flat and polished using 400, 600 and 1200 aluminium oxide paper in a rotatory polisher. In each pressing layer, microhardness was measured using a Knoop indenter in three different locations spaced 300 µm apart under a 10-g load, applied for 5 sec. RESULTS: Analysis of variance and Tukey's tests demonstrated that there was no difference in microhardness in the first layer of the teeth analyzed (p = 0.355), whereas in the second layer, the brand Artiplus(r) showed higher values when compared to the brand Natusdent(r) (p = 0.018). For the third layer, the brands Artiplus(r) and Trilux(r) Eurovipi revealed higher microhardness when compared to Natusdent(r) teeth (p < 0.001). CONCLUSION: For the outer most superficial layer of the artificial teeth, the microhardness of the different brands was similar, while differences were noted for the second and third layers among the artificial teeth, with Artiplus(r) teeth showing higher microhardness than Natusdent(r). .

OBJETIVO: Avaliar a microdureza nas camadas de prensagem de dentes fabricados em resina acrílica modificada. MÉTODOS: Primeiros molares inferiores pré-fabricados com duas (Biotone(r) IPN e Bioform(r)) ou três camadas de prensagem (Artiplus(r), Trilux(r) Eurovipi e Natusdent(r)), foram hemisseccionados no sentido vestíbulo-lingual e embutidos em resina acrílica autopolimerizável (n = 10). Os espécimes foram, então, planificados e polidos com lixas de óxido de alumínio nas granulações 400, 600 e 1200, em politriz giratória. Em cada camada de prensagem, a microdureza foi mensurada utilizando indentador Knoop em três diferentes localizações, espaçadas em 300 µm, sob carga de 10 g, aplicada por 5 s. RESULTADOS: Análises de variância e testes de Tukey demonstraram que os dentes avaliados não apresentaram diferenças de microdureza na primeira camada (p = 0,355), enquanto na segunda, os dentes da marca Artiplus(r) revelaram valores superiores em relação aos dentes da marca Natusdent(r) (p = 0,018). Na terceira camada, os dentes da marca Artiplus(r) e Trilux(r) Eurovipi apresentaram microdureza superior àquela verificada para os dentes Natusdent(r) (p < 0,001). CONCLUSÃO: Na camada externa, mais superficial, a microdureza dos dentes artificiais foi semelhante nas diferentes marcas. Apenas nas segunda e terceira camadas houve diferenças entre as marcas de dentes artificiais, sendo que os dentes da Artiplus(r) apresentaram microdureza superior aos dentes Natusdent(r). .

Masticatory efficiency in complete denture wearers with reduced dental arches--a randomised cross-over study.

One obstacle to placing artificial posterior teeth in manufacturing complete dentures is a reduction of the space between the maxilla and the mandible. Occasionally, second molar placement is not performed, as it does not affect aesthetics, phonetics or comfort. The aim of this study was to compare the masticatory efficiency between patients wearing maxillary and mandibular complete dentures with reduced dental arches (without second molars) (WSM) and with full dental arches (FDA). Twenty subjects were divided into two groups and randomly received new complete dentures. Patients in Group 1 were given dentures WSM, and those in Group 2 were given dentures with FDA. After the post-placement visits, an initial masticatory efficiency test was performed with Optocal, an artificial test food. Fifteen days later, second molars were placed in Group 1 and removed from Group 2, and a new test was performed. Comminuted material was treated and sieved under vibration. The mean and standard deviation of masticatory efficiency with FDA were 10.4 and 8.1, respectively. In the tests WSM, the mean and standard deviation were 8.4 and 3.3, respectively. After removing the second molars in Group 2 and adding them in Group 1, the mean and standard deviation were 15.7 and 14.7 for Group 1 and 12.5 and 10.4 for Group 2, respectively. Within the limitations of this study, placing artificial teeth up to the first molars can be performed when needed without compromising masticatory efficiency.

Comparação da largura dos dentes anteriores artificiais e naturais / Comparison of the width of artificial and natural anterior teeth

OBJETIVO: Verificar se a largura combinada dos seis dentes anteriores superiores artificiais fabricados e comercializados pela Dental Vipi Ltda. (Pirassununga, Brasil) é similar à mesma dimensão dos dentes naturais de brasileiros jovens e dentados. MÉTODOS: Participaram do estudo 49 estudantes jovens e dentados, sendo 20 do sexo masculino e 29 do feminino. Foram confeccionados modelos de gesso pedra para medir a largura dos seis dentes anteriores superiores por meio de uma régua milimetrada flexível. Os valores obtidos foram comparados aos valores fornecidos para os dentes artificiais, na carta molde, pelo fabricante. RESULTADOS: Foi encontrada uma média de 53,544 milímetros (desvio-padrão de 3,525) para a distância entre as faces distais dos caninos superiores, em curva. Os modelos de dentes artificiais atendem apenas a faixa de 40 a 50 milímetros de largura. CONCLUSÃO: Os dentes artificiais das marcas analisadas são substancialmente menores do que os dentes naturais da amostra em estudo.

OBJECTIVE: This study verified whether the combined width of the six artificial anterior maxillary teeth manufactured and marketed by VIPI (Dental Vipi Ltda., Pirassununga, Brazil), was similar to that of the respective natural teeth of young, dentate Brazilians. METHODS: Forty-nine dentate, healthy students (20 males and 29 females) participated in this study. Dental stone casts were made for measuring the combined width of the six anterior maxillary teeth with a flexible millimeter ruler. The combined width of the natural teeth was compared with that of the artificial teeth reported by the manufacturer in the selection chart. RESULTS: The mean anterior outside distance between the distal surfaces of the maxillary canines was 53.544 mm (standard deviation 3.525). The combined width of the artificial anterior teeth lies within the 40-50 millimeter range. CONCLUSION: The artificial teeth of the studied brand were substantially smaller than the natural teeth of the study sample.

Dimensional stability of distances between teeth in complete dentures comparing microwave polymerization and conventional cycles

Aim: This study investigated the tooth movement of complete dentures processed by micro wave activation and conventional processing method in water bath. Methods: Twenty maxillary complete dentures were fabricated and randomly assigned to 4 groups (n=5): Group I: Classico convention alheat-curing acrylic resin processed by microwave polymerization; Group II: Classico resinprocessed in water bath at 74°C for 9 h (control-group); Group III: QC-20 fast heat-curing acrylic resin processed in boiling water for 20 min; Group IV: Onda-Cryl microwave acrylic resin processed at the same conditions of Group 1. Metallic referential pins were placed on the incisal border of the central incisors, buccal cusp of the first premolars, and the mesiobuccal cusp of the second molars.Transversal and anteroposterior distances were measured before and after the complete dentures processing with a linear optical microscope (Olympus Optical Co., Tokyo, Japan) accurate to0.0005 mm. Data were subjected to A NOVA and Tukey’s test at 5% significance levels. Results:Inside each group, dentures showed some tooth movement but without statistical difference before and after the polymerization. Conclusions: Dentures processed by microwave energy presented similar performance to those subjected to conventional cycles in water bath for most of distances evaluated.

Effect of aluminium oxide particle sandblasting on the artificial tooth-resin bond.

AIM: The influence of tooth ridge-lap surface sandblasting with aluminium oxide particles was evaluated on the adhesion of artificial teeth to acrylic resins. METHODS: Specimens were made with the acrylic resin adhered to teeth (BioCler GII), according to an unmodified surface, glossy surface sandblasted with 50-µm particles and conventional (Classico) or microwaved (Onda Cryl) resin, and a glossy surface sandblasted with 100-µm particles and Classico or Onda Cryl resin. The shear bond test was performed in an Instron machine using a 500-N load cell and cross-speed of 1 mm/min. RESULTS: The analysis of variance revealed significant difference in the tooth-resin shear bond strength for resin, surface treatment, and interaction. For conventional resin, control, 50-, and 100-µm particles showed statistically-different values; for microwaved resin, the control showed less statistical difference when compared to 50- and 100-µm particle treatments; for between resins, only the 100-µm particle treatment showed statistically-different values, with lower values for the microwaved resin. Mixed failures (cohesive in the resin and adhesive) were predominantly observed in all groups. Mixed (cohesive in the tooth and adhesive) or adhesive failures were not observed. CONCLUSIONS: Sandblasting with different aluminium oxide particle sizes produced different effects on the shear strength values of the tooth-resin bond.

Effect of ridge lap surface treatment and thermocycling on microtensile bond strength of acrylic teeth to denture base resins

This study evaluated the effect of denture base polymer type (heat- and microwave-polymerized), ridge lap surface treatment (with and without methyl methacrylate-MMA etching) and thermocycling on the microtensile bond strength (µTBS) of Biotone acrylic teeth. Flat-ground, ridge-lap surface of posterior artificial teeth were bonded to cylinders of each denture base resin, resulting in the following groups (n=6): G1a - Clássico/with MMA etching; G1b - Clássico/without MMA etching; G2a - OndaCryl/with MMA etching; G2b - OndaCryl/without MMA etching. Rectangular bar specimens with a cross-sectional area of 1 mm² were prepared. Half of the bars in each group were thermocycled (5,000 cycles between 4ºC and 60ºC). µTBS testing was performed in an universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by three-way ANOVA (α=0.05). There was no statisticaly significant difference (p>0.05) for the factors (resin, surface treatment,and thermocycling) or their interactions. The mean µTBS values (MPa) and standard deviations were as follows: Thermocycling - G1a: 41.00 (14.00); G1b: 31.00 (17.00); G2a: 50.00 (27.00); G2b: 40.00 (18.00); No thermocycling - G1a: 37.00 (14.00); G1b: 43.00 (25.00); G2a: 43.00 (14.00); G2b: 40.00 (27.00). The µTBS of Biotone artificial teeth to the denture base acrylic resins was not influenced by the polymer type, surface treatment or thermocycling.

Este estudo avaliou o efeito do tipo de resina de base (termo-polimerizada e polimerizada por microondas), tratamento da superfície de união (com e sem aplicação de metil metacrilato) e termociclagem sobre a resistência adesiva à microtração (RAµT) do dente artificial Biotone. A superfície cervical dos dentes foi desgastada para se obter superfícies planas, as quais foram unidas a cada uma das resinas, constituindo os seguintes grupos (n=6): (G1a) Clássico/com MMA; (G1b) Clássico/sem MMA; (G2a) OndaCryl/com MMA; (G2b) OndaCryl/sem MMA. Corpos-de-prova retangulares com área transversal de 1 mm² foram preparados. Metade dos espécimes em cada grupo foi termociclado (5000 ciclos de 4ºC a 60ºC). O teste de resistência adesiva foi realizado numa máquina de ensaios universal (velocidade da carga: 1 mm/min). Os dados foram analisados estatisticamente por meio da ANOVA para 3 fatores (α=0,05). Os valores médios de RAµT e desvios-padrão foram: Termociclagem - G1a: 41,00 (14,00); G1b: 31,00 (17,00); G2a: 50,00 (27,00); G2b: 40,00 (18,00); Sem termociclagem - G1a: 37,00 (14,00); G1b: 43,00 (25,00); G2a: 43,00 (14,00); G2b: 40,00 (27,00). A RAµT entre os dentes artificiais e as resinas acrílicas para base de prótese não foi influenciada pelos fatores resina acrílica, tratamento de superfície ou termociclagem.