Color Stability of Acrylic Resin Teeth After Immersion in Staining Solutions / Análisis del Cambio de Color de Dientes Artificiales Tras Inmersión en Soluciones Colorantes

ABSTRACT: The objective of this study was to evaluate the color alteration of four brands of artificial teeth (Art Plus, Trilux, Bionote and Biolux), after immersion in color solutions of coffee, red wine and urucum. We used 80 artificial teeth, which were standardized with 2 mm thickness. Then, they were subjected to finishing and polishing, and divided into 4 groups (n = 05), which were immersed in one of the 3 types of dye, plus distilled water (control). The samples were immersed daily for 4 hours, then they were removed, washed in tap water, dried with absorbent paper and immersed in distilled water for the subsequent hours in a biological glasshouse at 37 ºC, for 21 days. The evaluation of the color change was made in the periods of 0, 7, 14 and 21 days, by means of the tristimulus colorimeter. The data were subjected to the ANOVA and Tukey test with a 5 % significance. The results showed that the urucum was the substance that caused the greatest staining while the coffee and the wine did not show statistical difference. Regarding trademarks, Trilux presented a statistical difference compared to the other commercial brands, revealing colorimetric alteration only in the 14-day period. It was concluded that the composition of the artificial teeth, the type of pigmenting agent and the immersion time determine the color change.

RESUMEN: El objetivo de este estudio fue evaluar la alteración de color de cuatro marcas de dientes artificiales (Art Plus, Trilux, Bionote y Biolux), después de inmersión en soluciones colorantes de café, vino tinto y urucum. Se utilizaron 80 dientes artificiales, los cuales fueron estandarizados con 2 mm de espesor. En seguida, los mismos fueron sometidos al acabado y pulido, y divididos en 4 grupos (n = 5), los cuales fueron inmersos en uno de los 3 tipos de colorante, más agua destilada (control). Las muestras permanecieron inmersas diariamente durante 4 horas, luego fueron retiradas, lavadas en agua corriente, secas con papel absorbente e inmersas en agua destilada por las horas subsiguientes en invernadero biológico a 37 ºC, por 21 días. La evaluación del cambio de color se realizó en los períodos de 0, 7, 14 y 21 días, por medio del colorímetro tristimulo. Los datos fueron sometidos a la prueba ANOVA y Tukey con un 5 % de significancia. Los resultados demostraron que el urucum fue la sustancia que provocó mayor manchado mientras que el café y el vino no presentaron diferencia estadística. En cuanto a las marcas comerciales, el Trilux presentó una diferencia estadística en comparación con las otras marcas comerciales, revelando alteración colorimétrica sólo en el período de 14 días. Se concluyó que la composición de los dientes artificiales, el tipo de agente pigmentante y el tiempo de inmersión determinan el cambio de color.

Spectrophotometric evaluation of 5-layer acrylic teeth hyperpigmentation caused by selected food colors: In vitro study.

BACKGROUND: Prosthetic treatment restores proper chewing function and facial aesthetics, and enhances the quality of life. The overall aesthetic result of the use of removable prostheses is correlated with the type of artificial teeth used and with the maintenance of aesthetic effect and color stability. OBJECTIVES: The aim of the study was to evaluate the formation and intensity of discoloration caused by the dyes present in selected 5-layer acrylic teeth. MATERIAL AND METHODS: The study material was a group of 90 5-layer acrylic teeth. Samples were immersed in black tea and dry red wine for 6 months. The control group was immersed in distilled water and consisted of 30 samples. The teeth were subjected to spectrophotometric examination at the start of the study, after 24 h, 7 days, 14 days, 1 month, 4 months, and 6 months. RESULTS: Among the teeth examined, in about 85% of the samples the color corresponded with the order. Teeth immersed in black tea became darker. From the 7th day to the 6th month, none of the samples changed their brightness. The teeth had the same degree of brightness. The teeth did not change tone during the experiment. Teeth immersed in dry red wine changed their shade to A starting on the 14th day, and by the 4th month all samples had changed shade to A or C. The 5-layer teeth had quite high shade stability until the 14th day of observation. In the control group, the teeth did not change tone and individual brightness changed more in the direction of brighter shades and less in the darker direction. In the study group, 93% of the samples did not change their brightness. CONCLUSIONS: Both black tea and dry red wine cause tooth discoloration, more intensely in the case of the 2nd fluid. Acrylic teeth with a 5-layer structure ensure good color stability over time. It improves the quality and aesthetics of the restorations used.

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).

Evaluation of methods for stain removal in acrylic resin denture teeth: in vitro study / Avaliação de métodos de remoção de manchas em dentes de resina acrílica para prótese total: estudo in vitro

Introduction: The staining of artificial teeth can be related to the acrylic resin abrasion caused by brushing, resulting in higher deposition of dyes from the beverage, and consequently higher aesthetic damage. Objective: The aim of this in vitro study was to evaluate methods for removal of stains from acrylic denture teeth using spectrophotometric analysis. Material and method: Artificial teeth were divided into twelve groups (n=10) according to the type of treatment (re-polishing - Re or immersion in Corega Tabs - Sp), staining solutions, coffee (Cf) and Coca-Cola® (Cc) or water (W) and with/without toothbrushing (B). The Sp specimens were submitted to seven immersion cycles (5 min each). The Re specimens were polished with pumice stone followed by Spain white paste. Color differences (ΔE) were captured by a spectrophotometer: T0 (baseline), T1 (after brushing/immersion in solutions) and T2 (after Re or Sp). Result: Statistically significant color change between T1 and T2 (paired T-test; α =.05) was observed for the group CfSp (p=.032); and for the groups BWRe (p=.000), BCfRe (p=.049) and CcRe (p=.042). Higher color changes were observed for the specimens submitted to toothbrushing (ANOVA two way; p<.001). Conclusion: It could be concluded that the immersion in sodium perborate (Corega Tabs) can be used for removal of coffee stains from denture teeth, and re-polishing for removal of Coca-Cola® stains. Still, toothbrushing produced greater color changes on denture teeth, regardless of the immersion solution.

Introdução: O manchamento dos dentes artificiais pode estar relacionado à abrasão da resina acrílica provocada pela escovação, resultando na maior deposição de corantes provenientes de bebidas, e consequentemente maior prejuízo estético. Objetivo: O objetivo do presente estudo foi avaliar métodos de remoção de manchas extrínsecas por meio de analise com espectofotômetro. Material e método: Dentes artificiais foram divididos em 12 grupos (n=10), de acordo com o tipo de tratamento (repolimento – Re ou imersão em perborato de sódio, Corega Tabs – Sp), tipo de solução de manchamento, café (Cf) ou Coca-Cola® (Cc) ou água (W) e com/sem escovação (B). Os métodos de remoção de manchas propostos (Re e Sp) foram realizados de acordo com protocolos pré-estabelecidos. Os espécimes Sp foram submetidos a 7 ciclos de imersão (5 minutos cada). O repolimento foi realizado com pastas de pedra pomes e branco de espanha, utilizando escovas de cerdas macias e rodas de feltro. As leituras de estabilidade de cor (ΔE) foram realizadas por meio de um espectrofotômetro: T0 (baseline), T1 (após escovação/imersão em bebidas), e T2 (após Re ou Sp). Resultado: Alterações de cor entre T1 e T2 (teste T pareado; α=0,05) foram observadas para o grupo CfSp (p=.032); e para os grupos BWRe (p=.000), BCfRe (p=.049) e CcRe (p=.042). Os dentes artificiais submetidos à escovação mostraram maior alteração de cor (ANOVA 2 fatores; p<0,001). Conclusão: Conclui-se que a imersão em perborato de sódio (Corega Tabs) pode ser utilizada para remoção de manchas de café e o repolimento para remoção de manchas de Coca-Cola®. Ainda, a escovação produziu as maiores alterações de cor nos dentes artificiais, independentemente da solução de imersão.

Influence of surface sealant agents on the surface roughness and color stability of artificial teeth.

STATEMENT OF PROBLEM: Although various surface sealant agents are available and recommended for chairside polishing procedures, their effect on the surface roughness and color stability of denture teeth is not clear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of various denture tooth materials. MATERIAL AND METHODS: Eighty disk-shaped specimens were prepared for each type of denture tooth material (SR Vivodent, PMMA; Vitapan, reinforced-PMMA; SR Phonares II, composite resin). The specimens were assigned to 4 groups according to the surface treatment used (n=20): surface sealant agents (Palaseal; Heraeus Kulzer GmbH, Optiglaze; GC Corp Biscover; Bisco Inc) and a conventional laboratory polishing technique (control group). A thermal cycling procedure was applied for half of the specimens (n=10). The surface roughness (Ra) values of thermocycled and nonthermocycled specimens were measured with a profilometer. The CIELab color parameters of both thermocycled and nonthermocycled specimens were measured with a spectrophotometer at baseline and after 7-day storage in a coffee solution. The color differences were calculated from the CIEDE2000 (ΔE00) formula. Data were statistically analyzed with 3-way ANOVA and the Tukey HSD test (α=.05). RESULTS: The type of tooth material, surface treatment technique, and their interactions were significant for Ra values, and each variable and their interactions were also significant for ΔE00 values (P<.05). Thermal cycling had a significant effect only on ΔE00 values (P<.05). CONCLUSIONS: Palaseal and Optiglaze sealant agents provided smoother and more color-stable denture tooth surfaces than the conventional polishing technique. The use of the Biscover agent with SR Vivodent and Phonares II teeth increased the Ra values. The color of conventionally polished SR Vivodent and Phonares II teeth changed more with thermal cycling.

A direct bonded fixed partial dental prosthesis: a clinical report.

A direct bonded fixed partial dental prosthesis, with a composite resin denture tooth as a pontic, a tri-n-butylborane initiated adhesive resin, and screw posts for reinforcement, was still functioning after an observation period of 20 years. The prosthesis was found to be reliable for long-term clinical use when chemically and mechanically reinforced.

Colour stability of acrylic resin denture teeth after immersion in different beverages.

The colour stability of acrylic resin denture teeth in beverages was investigated. A spectrophotometer measured the colour (CIE-L*a*b* system) of all specimens after storage in distilled water/for 24 h at 37 degrees C (T0). Specimens were then immersed in various beverages. After 15 days (T1) and 30 days (T2), for each material, the mean deltaE values were calculated and compared by two-way ANOVA and Tukey intervals (alpha = 0.05). In the deltaT0T1 period, specimens stored in red wine were significantly discoloured, compared to distilled water (P = 0.003). There was no difference between immersion solutions in deltaET0T2 (P = 0.772) and in deltaET1T2 (P = 0.058), and no difference between materials in all immersion periods.

Evaluation of staining susceptibility of resin artificial teeth and stain removal efficacy of denture cleansers.

OBJECTIVE: To assess the staining susceptibility of four acrylic resin (Ivostar, SR Vivodent PE, Major Dent, Integral) and a nanocomposite resin (Veracia) artificial teeth and to evaluate the stain removal efficacy of denture cleansers. MATERIALS AND METHODS: Sixty maxillary incisors of each brand (total = 300) were divided into three groups according to staining solution as coffee, red wine and tea. Baseline color measurements were performed with a spectrophotometer. Specimens were immersed in staining solutions for 14 h (2 h × 7 days) and then second color measurements were performed. Each group was further divided into four sub-groups according to denture cleanser as Corega tabs, Fittydent, NaOCl (0.5%) and distilled water (control) (n = 5). Specimens were immersed in denture cleansers for 8 h and third color measurements were made. Thus, the weekly simulation period was completed. This cycle was repeated 12 times to simulate a 3-month time period and measurements were performed at the end of the 4th, 8th and 12th cycles. ΔE values were calculated and data were analyzed with 3-way repeated measures ANOVA and Bonferroni tests. RESULTS: Significant color differences were found among the teeth and staining solutions, but all of the color differences were in the clinically acceptable range (ΔE < 5.5). Integral showed the highest ΔE values for all solutions, while Ivostar and Vivodent demonstrated the lowest ΔE values for red wine and tea solutions. There was no significant difference among the denture cleansers in terms of stain removal efficacy. CONCLUSIONS: Cross-linked acrylic (Integral) and nanocomposite (Veracia) resin teeth were more susceptible to staining. Denture cleansers were efficient on stain removal from artificial teeth.

An in vitro comparison of the shear bond strengths of two different gingiva-colored materials bonded to commercially pure titanium and acrylic artificial teeth.

PURPOSE: The purpose of this study was to compare shear bond strengths between two different gingiva-colored materials bonded to titanium alloy discs and acrylic resin artificial teeth. MATERIALS AND METHODS: For the first part of this study, 30 titanium alloy disc specimens were embedded in autopolymerizing resin. These discs were then divided randomly into two groups: Heat Cure (HT(1) ) and Pink Composite (CT(1) ). The discs were sandblasted with 100 µm aluminum oxide particles. For the HT(1) group using silicone molds, a wax-up was performed. After the wax removal step, heat-cured acrylic resin was applied and processed according to the manufacturer's recommendations. For the CT(1) group using silicone molds, metal primer II and gum opaque were applied and light cured; pink composite was then applied and light cured. For the second part of the study, 30 artificial resin first molar teeth were completely embedded in autopolymerizing resin. Teeth were then divided randomly into two groups: Heat Cure (HT(2) ) and Pink Composite (CT(2) ). For the HT(2) group using silicone molds, wax-up was performed. Specimens were then transferred to be processed in the heat-cured acrylic resin according to the manufacturer's recommendations. For the CT(2) group using silicone molds, composite primer followed by pink composite were applied and light cured. Shear bond tests were performed using an Instron 3345 universal testing machine. The shear load at the point of failure was recorded in Newtons. The force was calculated in MPa by calculating the failure load divided by the surface area. Two independent-samples t-tests were performed. A significance level of p < 0.05 was used for comparison. RESULTS: This study revealed that the difference in the shear bond strengths of two different gingiva-colored materials bonded to titanium discs was statistically significant (p = 0.012). The difference in the shear bond strengths of two different gingival-colored materials bonded to acrylic teeth was statistically significant (p < 0.001). CONCLUSION: In this in vitro study, heat-cured acrylic resins exhibited higher bonding strengths when bonded to titanium discs or acrylic artificial teeth in comparison to pink composite resins.

Effect of chemical and microwave disinfection on the surface microhardness of acrylic resin denture teeth.

PURPOSE: The purpose of this study was to evaluate the effect of simulated disinfections (2% glutaraldehyde, 1% sodium hypochlorite, and microwave energy) on the surface hardness of Trilux, Biocler, Biotone, New Ace, and Magister commercial artificial teeth. MATERIALS AND METHODS: Specimens (n = 10) were made with the teeth included individually in circular blocks of acrylic resin, leaving the labial surface exposed. Cycles of simulated chemical disinfection were accomplished with the specimens immersed in the solutions at room temperature for 10 minutes, followed by tap water washing for 30 seconds and storage in distilled water at room temperature for 7 days until the next disinfection. Simulated disinfection by microwave energy was carried out in a domestic oven with 1300 W at a potency of 50% for 3 minutes with the specimens individually immersed in 150 ml of distilled water. Control (no disinfection) and the experimental groups (first and third disinfection cycles) were submitted to Knoop hardness measurements with indentations at the center of the labial tooth surface. Data were submitted to repeated measure two-way ANOVA and Tukey's test (α = 0.05). RESULTS: Biocler, Magister, and Trilux showed lower surface microhardness when submitted to microwave. Lower microhardness for Biotone was promoted by hypochlorite, while no significant difference was shown for New Ace. The third disinfection cycle significantly decreased the tooth surface hardness only for microwave. CONCLUSIONS: Different disinfection methods promoted different effects on the microhardness of different types of artificial teeth. Surface microhardness of the teeth was less affected by the simulated chemical disinfections when compared to microwaved specimens.

Effects of ageing and staining on color of acrylic resin denture teeth.

OBJECTIVES: To assess the color stability of high-strength acrylic resin denture teeth after exposure to red wine, coffee and artificial ageing. METHODS: Four different shades of acrylic resin denture teeth were selected from three manufacturers. The teeth were evaluated in two phases: Phase I, upon staining for 7 days in distilled water (control Group A), red wine (experimental Group B) and coffee (experimental Group C), and Phase II, upon artificial ageing in a Weather-Ometer for a total exposure of 150 kJ/m(2) (control Group A; Phase I). Denture tooth positioning jigs were fabricated and color data recorded by means of an intra-oral spectrophotometer and expressed using the Commission Internationale d'Eclairage (CIE) L*a*b* color notation system. Means and standard deviations were determined. The staining data were analysed by three-way ANOVA, while the artificial ageing data were analysed by two-way ANOVA. Fisher's PLSD intervals were calculated at a significance level of P ≤ 0.05. RESULTS: In the staining experiment, the main effects of stains and denture teeth and the two-way and three-way interactions among stains, denture teeth and shades were significant (P ≤ 0.05). The same was true for the main effects of denture teeth and shades and their interactions in the ageing experiment. The smallest overall color change upon staining in red wine was recorded for Vita Physiodens denture teeth (ΔE*=0.9 ± 0.4), followed by SR Vivodent PE 1.2 (0.6) and Portrait IPN 2.4 (0.6). Corresponding values for staining in coffee were 2.0 (0.6), 1.7 (1.0) and 1.8 (0.8), while ageing-dependent changes in color were 1.7 (0.4), 2.4 (0.8) and 1.1 (0.4) for Portrait IPN, SR Vivodent PE and Vita Physiodens teeth, respectively. CONCLUSION: Although the null hypothesis has been partially rejected, because some statistically significant changes in color and color coordinates occurred upon staining and ageing, all evaluated denture teeth exhibited good color stability compared to the 50:50% acceptability threshold used in data interpretation. CLINICAL SIGNIFICANCE: Selection of a color stable and stain-resistant denture tooth can contribute to denture longevity and overall patient satisfaction.

Effect of experimental Ricinus communis solution for denture cleaning on the properties of acrylic resin teeth.

This study evaluated Knoop hardness, surface roughness and color alteration of artificial teeth for dentures after immersion in water, 1% sodium hypochlorite and an experimental solution of 2% Ricinus communis (RC). Thirty specimens of Vipi, Biolux and Trilux were analyzed. Tests of Knoop hardness, surface roughness and color alteration were conducted immediately after specimen preparation (T0) and after two immersion protocols for 15 days (ΔT(15)) and 183 days (ΔT(183)). Data variation (ΔT) were subjected to ANOVA and Tukey's test (p<0.05). At ΔT(15), Vipi presented hardness increase and Biolux presented the highest variation (p=0.01). RC caused the highest increase in hardness (p=0) and the lowest increase (p=0.005) in roughness. Biolux presented the lowest color alteration (p =0). At ΔT(183), Trilux underwent the highest hardness variation (p=0). Biolux presented an increase in roughness (p=0). There was no significant differences in color alteration among the artificial teeth (p=0.06) and among solutions (p=0.08) after 183 days of immersion. All solutions (distilled water, 1% sodium hypochlorite and 2% RC) caused alterations on the analyzed properties. Both immersion protocols caused alterations on the analyzed properties.

Effect of repeated microwave disinfections on bonding of different commercial teeth to resin denture base.

OBJECTIVE: To verify the influence of repeated microwave disinfections on the shear bond strength of two commercial types of teeth to acrylic resin, when the ridge lap surfaces were unmodified, bur abraded, bur grooved or etched by monomer. MATERIAL AND METHODS: Eighty specimens (n = 10) were adhered to the tooth ridge lap surface, polymerised in a water bath at 74°C for 9 h. Microwaved specimens were individually immersed in 150 ml of water and submitted to five simulated disinfections in a microwave oven calibrated at 650 W for 3 min. Control specimens were not microwave treated. Shear bond strength tests were performed in an Instron machine with a cross-speed of 1 mm/min. The fracture load values were transformed into shear bond strength as a function of the bonding area (0.28 cm(2)). Data were submitted to ANOVA and Tukey's test (α = 0.05). Fractured areas were classified as adhesive, cohesive (resin or tooth) or mixed failures. RESULTS: Repeated microwave disinfections increased the shear strength of the tooth/resin bond. Mechanical retention in microwaved and non-microwaved procedures improved the shear bond strength. CONCLUSIONS: The different commercial types of teeth influenced shear bond strength values, with Biotone teeth showing the lower values.

Bond of acrylic teeth to different denture base resins after various surface-conditioning methods.

The study examined the bond between different denture base resins and highly cross-linked acrylic denture teeth with different base surface-conditioning methods. One hundred fifty highly cross-linked resin denture teeth (SR-Antaris, No. 11, Ivoclar-Vivadent, FL) were divided into five groups with different surface-conditioning methods of the base surfaces of the teeth (C = control, no surface conditioning, MM = application of methyl methacrylate monomer, SB = sand blasting, SBB = sand blasting + bonding agent, TSS = tribochemical silica coating + silanization). Teeth were bonded to either a cold-cured denture base resin (ProBase Cold, Ivoclar-Vivadent, FL) or heat-cured denture base resins (SR Ivocap Plus, Ivoclar-Vivadent, FL and Lucitone 199, Dentsply, USA). After 24 h of storage in distilled water, compressive load was applied at 90° on the palatal surface of each tooth until fracture. Median failure load ranged between 103 and 257 N for Probase Cold groups, 91 to 261 N for Lucitone 199, and 149 to 320 N for SR Ivocap Plus. For Probase Cold, significant highest failure loads resulted when teeth were treated with SB, SBB, or TSS. For Lucitone 199, significant highest failure loads has been found with MM and TSS treatment. For SR Ivocap Plus, highest failure loads resulted using SBB and TSS. Conditioning of the base surfaces of the teeth prior to denture base processing is highly recommended. Tooth bond is significantly affected by the surface-conditioning method and applied denture base resin. Tribochemical silica coating + silanization method can be recommended for pre-treatment of teeth applying either heat-cured or cold-cured denture base resin.

Effect of experimental Ricinus communis solution for denture cleaning on the properties of acrylic resin teeth

This study evaluated Knoop hardness, surface roughness and color alteration of artificial teeth for dentures after immersion in water, 1 percent sodium hypochlorite and an experimental solution of 2 percent Ricinus communis (RC). Thirty specimens of Vipi, Biolux and Trilux were analyzed. Tests of Knoop hardness, surface roughness and color alteration were conducted immediately after specimen preparation (T0) and after two immersion protocols for 15 days (ΔT15) and 183 days (ΔT183). Data variation (ΔT) were subjected to ANOVA and Tukey's test (p<0.05). At ΔT15, Vipi presented hardness increase and Biolux presented the highest variation (p=0.01). RC caused the highest increase in hardness (p=0) and the lowest increase (p=0.005) in roughness. Biolux presented the lowest color alteration (p =0). At ΔT183, Trilux underwent the highest hardness variation (p=0). Biolux presented an increase in roughness (p=0). There was no significant differences in color alteration among the artificial teeth (p=0.06) and among solutions (p=0.08) after 183 days of immersion. All solutions (distilled water, 1 percent sodium hypochlorite and 2 percent RC) caused alterations on the analyzed properties. Both immersion protocols caused alterations on the analyzed properties.

Este estudo avaliou a dureza Knoop, rugosidade e alteração de cor de dentes artificiais após imersão em água, hipoclorito de sódio 1 por cento e solução de Ricinus communis 2 por cento (RC). Trinta espécimes de dentes das marcas Vipi, Biolux e Trilux foram analisados. Os testes de dureza, rugosidade e alteração de cor foram realizados após a obtenção dos espécimes (T0) e após dois protocolos de imersão nas soluções por 15 dias (Δ15) e 183 dias (Δ183). A variação dos dados (ΔT) foi submetida à ANOVA e teste de Tukey (p<0,05). Em ΔT15, Vipi apresentou aumento da dureza e Biolux, a maior variação (p =0,01). RC causou o maior aumento na dureza (p=0). RC causou o menor aumento na rugosidade (p=0,005). Biolux apresentou a menor alteração de cor (p=0). Em ΔT183, Trilux apresentou a maior variação na dureza. (p=0). Biolux apresentou aumento na rugosidade (p=0). Não houve diferença significante na alteração de cor entre dentes (p=0,06) e entre soluções (p=0,08) após 183 dias de imersão. Todas as soluções (água destilada, hipoclorito de sódio 1 por cento e RC) causaram alterações nas propriedades analisadas. Ambos os protocolos de imersão causaram alterações nas propriedades analisadas.

In vitro wear resistance, hardness and elastic modulus of artificial denture teeth.

In this study, the wear resistance, hardness, elastic modulus, and the correlations between them of artificial denture teeth at the sub-enamel layer were examined. Four types of tested artificial denture teeth consisted of 3 conventional acrylic resin teeth (Cosmo HXL, Major Dent, and Yamahachi FX), 1 high cross-linked acrylic resin teeth (Trubyte Bioform IPN), 2 composite resin teeth (SR Orthosit PE, and Yamahachi PX), and 1 porcelain teeth (ACE Teeth). The two-body wear test was performed using a custom made pin on disc apparatus. Volume and weight loss were measured. Hardness and elastic modulus were also assessed by using a nanoindentation system. The results suggested wear resistance varied among the denture tooth materials. Wear resistance of high cross-linked acrylic resin teeth was the lowest. A definite relation between wear resistance and mechanical properties of materials could not be found in this study.

Effect of embedded metal reinforcements and their location on the fracture resistance of acrylic resin complete dentures.

PURPOSE: This study evaluated the effect of metal reinforcement and its location on the flexural load at the proportional limit (FL-PL) and the flexural deflection of maxillary acrylic resin complete dentures. MATERIALS AND METHODS: Maxillary acrylic resin complete dentures reinforced with Remanium and without reinforcement were tested. The reinforcing material was embedded in the denture base resin in the doughy state and placed (1) under the ridge lap region; (2) in the anterior region; (3) in the middle region; and (4) in the anterior and posterior regions. The FL-PL (N) and the flexural deflection (mm) at 100 N of the reinforced maxillary denture specimens were tested using a load testing machine at a 5.0 mm/min crosshead speed. The data were analyzed statistically using one-way ANOVA; Tukey's post hoc comparisons test was applied when appropriate (95% confidence level). RESULTS: The FL-PL of the dentures without reinforcement (909 ± 195 N) and the dentures reinforced at the ridge lap (1094 ± 176 N) and in the middle (977 ± 215 N) regions were not significantly different (p > 0.05). The dentures reinforced in the anterior (1348 ± 205 N) and the anterior and posterior (1190 ± 191 N) regions had a higher FL-PL than the dentures without reinforcement (p < 0.05) and were not significantly different from each other (p > 0.05). The efficiency (times) of the reinforcing material on the dentures without reinforcement was 1.08 to 1.48. The flexural deflection of the dentures without reinforcement (0.133 ± 0.014 mm), the dentures reinforced at the ridge lap (0.125 ± 0.014 mm), in the anterior (0.122 ± 0.009 mm), and in the middle (0.132 ± 0.015 mm) regions were not significantly different (p > 0.05), and the dentures reinforced in the anterior and posterior (0.117 ± 0.011 mm) regions had significantly lower deflection than the dentures without reinforcement (p < 0.05). CONCLUSION: The location of the metal reinforcement affected the fracture resistance of the maxillary acrylic resin complete dentures.

Shear bond strength of orthodontic brackets bonded to various esthetic pontic materials.

INTRODUCTION: In this in-vitro study, we compared the shear bond strengths of orthodontic brackets bonded to various commonly used esthetic pontic materials. METHODS: Prefabricated denture teeth (acrylic resin, Trubyte, Dentsply, York, Pa) and samples made from Integrity (bis-acryl composite resin, Dentsply Caulk, Milford, Del) and Alike (polymethylmethacrylate resin, GC America, Alsip, Ill) were used to represent the more common esthetic provisional materials. Each material group contained 30 samples; a total of 90 samples were bonded in the same fashion with APC PLUS maxillary lateral incisor brackets (3M Unitek, Monrovia, Calif). Each material group was then divided into 2 testing subgroups. One subgroup was tested for shear bond strength 24 hours after bonding, and the other subgroup was tested after bonding and storage in distilled water at 37 degrees C for a week. Each bracket was loaded perpendicularly in a universal testing machine at a crosshead speed of 1.0 mm per minute until bonding failure. The mean shear bond strength and standard deviation were determined for each group. Analysis of variance (ANOVA, 2-factor and 1-factor) with Tukey HSD post-hoc tests, Student t tests, and Mann-Whitney U tests were used to test the main effects of pontic materials and time of loading (alpha = 0.05). The data were stratified, and 1-way ANOVA tests were performed with the Bonferroni adjustment (alpha = 0.01) to examine the effect of the pontic material on shear bond strength after either 1 day or 7 days of storage. RESULTS: Significant differences were found based on pontic material and time (P <0.05), but there was a significant interaction (P = 0.044), making the results uninterpretable. At 1 day, the Integrity material had a significantly higher mean shear bond strength than both Alike and the denture tooth materials (P <0.001). However, at 7 days, both Integrity and Alike had significantly higher mean shear bond strengths compared with the prefabricated denture tooth (P <0.001). CONCLUSIONS: Although the use of Integrity or Alike requires an additional armamentarium, necessitating individual pontic fabrication by the dental practitioner, indications for clinical use are evident with direct applications to multi-disciplinary treatment modalities.

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.