Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS)

Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS).Material and Methods A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated.Results The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76).Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

Surface roughness of orthodontic band cements with different compositions

OBJECTIVES: The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. MATERIAL AND METHODS: Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP), compomer (C), resin-modified glass ionomer cement (RMGIC) and resin cement (RC). Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0) or 0.1 M lactic acid solution (pH 4.0) for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200) before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions) or paired t-test (comparison before and after the storage period) at 5 percent significance level. RESULTS: The values for average surface roughness were statistically different (p<0.001) among cements at both baseline and after storage. The roughness values of cements in a decreasing order were ZP>RMGIC>C>R (p<0.001). After 15 days, immersion in lactic acid solution resulted in the highest surface roughness for all cements (p<0.05), except for the RC group (p>0.05). Compared to the current threshold (0.2 µm) related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. CONCLUSIONS: Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.

in vitro evaluation of marginal leakage using invasive and noninvasive technique of light cure glass ionomer and flowable polyacid modified composite resin used as pit and fissure sealant.

Aim: This study compared the microleakage of light cure glass ionomer and flowable compomer as pit and fissure sealant, with and without tooth preparation. Materials and Methods: One hundred premolars that were extracted for orthodontic purpose were used. After adequate storage and surface debridement, the teeth were randomly divided into four groups. In Group I and III, the occlusal surfaces were left intact, while in Group II and Group IV, tooth surfaces were prepared. Teeth in Group I and Group II were sealed with Light cure glass ionomer, whereas flowable compomer was used to seal teeth in Group III and IV. The sealed teeth were then immersed in dye. Subsequently, buccolingual sections were made and each section was examined under stereomicroscope for microleakage followed by scoring. Results: In group I, microleakage score ranged from 2 to 4 with mean of 3.64 (±0.757), while in group II the range was observed to be 1-4 with mean of 2.88 (±1.236). Group III recorded a range of 0-4 with the mean of 2.20 (±1.443) while 0-2 and 0.60 (±0.707) being the range and mean observed, respectively, for group IV. Conclusion: Flowable compomer placed after tooth preparation showed better penetration and less marginal leakage than the light cure glass ionomer.

Effect of different topical fluoride applications on the surface roughness of a colored compomer

OBJECTIVE: The aim of this study was to evaluate the effect of neutral sodium fluoride (NNaF) gel and acidulated phosphate fluoride (APF) gel on the surface roughness of colored compomer (Twinky Star), conventional compomer (Compoglass F) and resin-modified glass-ionomer cement (RMGIC) (Photac-Fil). MATERIAL AND METHODS: A total of 45 standardized disc-shaped specimens were prepared for each material. After 24 h, finishing and polishing of specimens were done with aluminum oxide disc. Surface treatments with topical fluoride agents or distilled water (control) were performed four times, and interspersed with 8 pH cycles, simulating high cariogenic challenges. After the treatment, the surface roughness (Ra) was determined using a profilometer. In each group, specimens with Ra closest to the mean were examined with a scanning electron microscope (SEM) at ×1,000 and ×3,500 magnifications. Two-way ANOVA was used to evaluate Ra measurements, and the differences in Ra values between subgroups for each material and each topical applications were compared by Tukey's highly significant difference pairwise comparisons. RESULTS: No statistically significant difference in Ra between the Twinky Star and Compoglass F was found. However, Photac Fil showed significantly higher Ra than these materials after all surface treatments. There was a general trend of Ra increase from controls to NNaF and APF gels for all materials. SEM observations revealed that the surface micromorphology of Twinky-Star did not differ significantly from that of Compoglass F. CONCLUSION: Both the compomers and the RMGIC showed significantly higher surface roughness when subjected to APF gel application.

Fluoride release frompolyacid modified composites (compomers) in artificial saliva and lactic acid / Liberação de flúor por compósitos poliácidos modificados (compômeros) em saliva artifical e ácido lático

OBJECTIVES: The aim of this study was to assess the effect of different extraction media and time on the amount and pattern of fluoride release from compomers. MATERIAL AND METHOD: 42 specimens (n = 7 per group) in disc forms (7 mm diameter, 2 mm thickness) from three different compomers (were placed in artificial saliva (pH = 7.0) and lactic acid (pH = 5.2). The amount of the fluoride in these solutions were measured at 1st, 7th, 14th, 21th and 28th day time intervals by means of the fluoride ion selective electrode. The fluoride amount was calculated by concentration (ppm). The amount and the pattern of fluoride release was dependent on both the material, the storage medium and time. RESULTS: Fluoride release was evident for all the compomers but the rate of release varied considerably between the materials. Significant differences were also found between the different types of compomer (p < 0.01). A time dependent increase in the fluoride content was observed for all the compomers in both media. For all the tested materials, the fluoride release was higher in the lactic acid (p < 0.01). The amount of fluoride release was the most from Compoglass followed by Dyract AP and Glasiosite at 28th days, in both artificial saliva and lactic acid respectively. The least amount of fluoride release was observed at the first day.

OBJETIVOS: O objetivo deste estudo foi determinar o efeito de diferentes meios e tempo na quantidade e padrão de liberação de flúor por compômeros. MATERIAL E MÉTODO: 42 espécimes (n = 7 por grupo) em discos (7 mm de diâmetro, 2 mm de espessura), três compômeros diferentes, foram colocados em saliva artificial (pH 7,0) e ácido lático (pH 5,2). A quantidade de flúor nas soluções foram medidas a intervalos semanais, do 1º ao 28º dias (quatro semanas) por meio de eletrodos seletivos para íons flúor. A quantidade de flúor foi calculdada por concentração(ppm). A quantidade e o padrão da liberação de flúor variou consideravelmente tanto do material, do meio de armazenamento e tempo. RESULTADOS: A liberação de flúor foi evidente por todos os compômeros, mas a taxa de liberação variou consideravelmente entre os diferentes tipos de compômeros (p < 0.01). Um aumento relacionado com o tempo no conteúdo de flúor foi observado para todos os compômeros em ambos os meios. Para todos os materiais testados, a liberação de flúor foi maior no ácido lático (p < 0.01). A quantidade de liberação de flúor foi maior pelo Compoglass®, seguido pelo Duract AP® e Glasiosite® aos 28 dias, tanto na saliva artificial como no ácido lático respectivamente. A menor liberação de flúor foi observada no primeiro dia.

The interaction of polyacid-modified composite resins ("compomers") with aqueous fluoride solutions

OBJECTIVE : The aim of this study was to investigate how the release of fluoride from two compomers and a fluoridated composite resin was affected by exposure to KF solution. MATERIAL AND METHODS: Two compomers (Dyract AP and Compoglass F) and one fluoridated composite (Wave) were prepared as discs (6 mm diameter and 2 mm thick), curing with a standard dental lamp. They were then stored in either water or 0.5% KF for 1 week, followed by placement in water for periods of 1 week up to 5 weeks total. Fluoride was determined with and without TISAB (to allow complexed and decomplexed fluoride to be determined), and other ion release (Na, Ca, Al, Si, P) was determined by ICP-OES. RESULTS: Specimens were found not to take up fluoride from 100 ppm KF solution in 24 h, but to release additional fluoride when stored for up to five weeks. Compomers released more fluoride cumulatively following exposure to KF solution (p<0.001), all of which was decomplexed, though initial (1 week) values were not statistically significant for Dyract AP. Other ions showed no variations in release over 1 week, regardless of whether the specimens were exposed to KF. Unlike the compomers, Wave showed no change in fluoride release as a result of exposure to KF. CONCLUSIONS: Compomers are affected by KF solution, and release more fluoride (but not other ions) after exposure than if stored in water.

Influence of flowable materials on microleakage of nanofilled and hybrid Class II composite restorations with LED and QTH LCUs.

Background: Class II composite restorations are more frequently being placed with margins apical to the cementoenamel junction (CEJ) and margins within the dentin are prone to microleakage. Aims: This in vitro study was used to evaluate the influence of flowable composite and flowable compomer as gingival liner on microleakage in Class II composite restorations and compare a light-emitting diode (LED) unit with a quartz tungsten halogen (QTH) unit for light-activating composite resins. Materials and Methods: Mesioocclusal and distoocclusal Class II cavity preparations were made in 72 sound extracted premolars. The buccolingual width was 2.5 mm and the gingival margins of all the cavities were placed 1.0 mm apical to the CEJ. The boxes were prepared 1.5 mm deep axially, making 144 slot cavities. Teeth were randomly divided into the following two groups (n = 72): (I) Universal Filtek Supreme XT; Universal Filtek Supreme XT + Flwable Filtek XT and Universal Filtek Supreme XT + Dyract Flow and (II) Filtek Z250; Filtek Z250 + Flwable Filtek XT and Filtek Z250 + Dyract Flow. Flowable materials were injected into the gingival floor of the cavity to a thickness of 1.0 mm. Each increment was cured for 20 s. One-half of the subgroups in each group were cured with QTH and the other half with LED light curing units (LCUs). After 1 week of incubation at 37°C, the specimens were thermocycled (5-55°C, x1500), immersed in 0.5% basic fuchsine dye for 24 h and sectioned and microleakage was evaluated at the gingival margin by two examiners using a 0-3 score scale. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: The groups utilizing flowable liners had significantly less microleakage (P < 0.05). No significant difference was identified between Universal Filtek Supreme XT and Filtek Z250 composites with and without flowable materials. There was no significant between utilizing flowable composite or flowable compomer and between each similar subgroup when polymerized with either the LED or the QTH LCUs. Conclusions: A layer of flowable materials at the gingival floor of Class II composite restorations may be recommended to improve the marginal seal of a restoration.

Marginal adaptation and performance of bioactive dental restorative materials in deciduous and young permanent teeth

OBJECTIVE: The aim of this study was to investigate the adaptation of different types of restorations towards deciduous and young permanent teeth. MATERIAL AND METHODS: Class V cavities were prepared in deciduous and young permanent teeth and filled with different materials (a conventional glass-ionomer, a resin-modified glass-ionomer, a poly-acid-modified composite resin and a conventional composite resin). Specimens were aged in artificial saliva for 1, 6, 12 and 18 months, then examined by SEM. RESULTS: The composite resin and the polyacid-modified composite had better marginal adaptation than the glass-ionomers, though microcracks developed in the enamel of the tooth. The glass-ionomers showed inferior marginal quality and durability, but no microcracking of the enamel. The margins of the resin-modified glass-ionomer were slightly superior to the conventional glass-ionomer. Conditioning improved the adaptation of the composite resin, but the type of tooth made little or no difference to the performance of the restorative material. All materials were associated with the formation of crystals in the gaps between the filling and the tooth; the quantity and shape of these crystals varied with the material. CONCLUSIONS: Resin-based materials are generally better at forming sound, durable margins in deciduous and young permanent teeth than cements, but are associated with microcracks in the enamel. All fluoride-releasing materials give rise to crystalline deposits.

A comparison of impact strength of fragment-bonded anterior teeth using three different restorative materials: an in vitro study.

BACKGROUND AND OBJECTIVE: The purpose of this investigation was to estimate the impact strength of fractured anterior teeth reattached using three different restorative materials and compare their impact strengths to those of control. MATERIALS AND METHODS: Sixty human maxillary permanent central incisors were selected and divided into control and experimental groups. The teeth in the experimental groups were fractured and then bonded using Composite resin, Compomer and resin-modified GIC. Intact teeth served as control. All the specimens were then tested in an impact testing machine. RESULTS: The results revealed statistically significant differences between Compomer and resin-modified GIC groups, control and experimental groups. No statistically significant differences were observed between Composite resin and Compomer groups. CONCLUSION: Thus the fractured fragments bonded with Composite resin and Compomer provided better adhesion than resin-modified GIC.

Microhardness and fluoride release of restorative materials in different storage media

This study evaluated the surface microhardness and fluoride release of 5 restorative materials - Ketac-Fil Plus, Vitremer, Fuji II LC, Freedom and Fluorofil - in two storage media: distilled/deionized water and a pH-cycling (pH 4.6). Twelve specimens of each material, were fabricated and the initial surface microhardness (ISM) was determined in a Shimadzu HMV-2000 microhardness tester (static load Knoop). The specimens were submitted to 6- or 18-h cycles in the tested media. The solutions were refreshed at the end of each cycle. All solutions were stored for further analysis. After 15-day storage, the final surface microhardness (FSM) and fluoride release were measured. Fluoride dose was measured with a fluoride-specific electrode (Orion 9609-BN) and digital ion analyzer (Orion 720 A). The variables ISM, FSM and fluoride release were analyzed statistically by analysis of variance and Tukey's test (p<0.05). There was significant difference in FSM between the storage media for Vitremer (pH 4.6 = 40.2 ± 1.5; water = 42.6 ± 1.4), Ketac-Fil Plus (pH 4.6 = 73.4 ± 2.7; water = 58.2 ± 1.3) and Fluorofil (pH 4.6 = 44.3 ± 1.8; water = 38.4 ± 1.0). Ketac-Fil Plus (9.9 ± 18.0) and Fluorofil (4.4 ± 1.3) presented higher fluoride release in water, whereas Vitremer (7.4 ± 7.1), Fuji II LC (5.7 ± 4.7) and Freedom (2.1 ± 1.7) had higher fluoride release at pH 4.6. Microhardness and fluoride release of the tested restorative materials varied according to the storage medium.

Este estudo avaliou as propriedades de microdureza de superfície e liberação de flúor de 5 materiais restauradores (Ketac-Fil Plus, Vitremer, Fuji II LC, Freedom e Fluorofil) em dois meios de imersão: água destilada/deionizada e modelo de ciclagem de pH (4,6). Doze corpos-de-prova de cada material foram confeccionados e tiveram a microdureza de superfície inicial (MSI) determinada utilizando o microdurômetro Shimadzu HMV-2000 Micro Hardness Tester (carga estática Knoop). Os corpos-de-prova foram submetidos a ciclos de 6 e 18 h para os dois meios de imersão. A cada final de ciclo as soluções foram substituídas e armazenadas. Após 15 dias de imersão, a microdureza de superfície final (MSF) e a liberação de flúor foram determinadas. A dosagem de flúor foi feita com um eletrodo específico combinado para íon flúor (9609 BN - Orion) e analisador de íons digital (Orion 720 A). As variáveis MSI, MSF e liberação de flúor foram submetidas à análise de variância e teste de Tukey (p<0,05). Houve diferença estatisticamente significante na MSF entre os meios de imersão para o Vitremer (pH 4,6 = 40,2 ± 1,5; água = 42,6 ± 1,4), Ketac-Fil Plus (pH 4,6 = 73,4 ± 2,7; água = 58,2 ± 1,3) e Fluorofil (pH 4,6 = 44,3 ± 1,8; água = 38,4 ± 1,0). O Ketac-Fil Plus (9,9 ± 18,0) e o Fluorofil (4,4 ± 1,3) liberaram mais flúor na água; o Vitremer (7,4 ± 7,1), Fuji II LC (5,7 ± 4,7) e o Freedom (2,1 ± 1,7) no pH 4,6. A microdureza e liberação de flúor dos materiais restauradores estudados variaram de acordo com o meio de imersão.

Effect of light-activation methods and water storage on the flexural strength of two composite resins and a compomer

O presente estudo analisou a resistência à flexão de três compósitos recomendados para restaurações estéticas diretas: um compósito poliácido-modificado (Dyract AP), uma resina composta unimodal (Filtek Z250) e uma resina composta híbrida (Point 4). Os fatores de variação, além do tipo de compósito, foram o método de fotoativação e o período de armazenagem em água. Os materiais foram fotoativados continuamente por 40 s (500 mW/cm²) ou com intensidade de luz crescente (0-800 mW/cm² por 10 s seguidos de 30 s a 800 mW/cm²). Os períodos de armazenagem foram de 24 horas ou 30 dias em água destilada a 37°C. Os dados foram submetidos à análise de variância e ao teste de Tukey para comparações múltiplas (a = 0,05). A resina composta Z250 apresentou a maior média de resistência à flexão (166,74 MPa) e a Dyract AP, a menor (129,76 MPa). A armazenagem por 30 dias diminuiu a resistência à flexão para o método de fotoativação crescente (24 h: 156,64 MPa; 30 dias: 135,58 MPa). O método de fotoativação isoladamente não conduziu a diferentes valores de resistência à flexão.

Microleakage of restorative materials: an in vitro study.

The present study was conducted with the aim of evaluating and comparing the microleakage of glass ionomer, composite resin and compomers. Class V cavities were made in thirty intact caries free premolars and restored with restorative materials to be tested respectively. The teeth were thermocycled and subjected to silver nitrate dye penetration. They were subsequently sectioned buccolingually. Microleakage was evaluated under a stereomicroscope and data subjected to statistical analysis. The study concluded that microleakage was evident in all restorative materials, with glass ionomer showing maximum leakage followed by composite resin. Compomer demonstrated the best results with minimum leakage.

Microhardness of resin-based materials polymerized with LED and halogen curing units

O objetivo deste estudo foi avaliar a microdureza de materiais resinosos polimerizados com unidades de fotoativação LED (diodos emissores de luz) e halógena. Vinte espécimes cilíndricos (3,0 mm de diâmetro e 2,0 mm de altura) foram preparados para cada material testado (Z100, Definite e Dyract). Os espécimes foram fotoativados na face superior (topo), utilizando duas unidades de fotoativação (Ultraled and Curing Light 2500), com tempos de 40 s e 60 s. As medidas de dureza foram realizadas nas superfícies do topo e da base de cada espécime. A análise estatística foi realizada por ANOVA e teste de Tukey (p<0,05). Não houve diferença significante na dureza na face superior entre as unidades LED e halógena para a Z100 e o Dyract. Por outro lado, a dureza foi menor quando a Definite foi polimerizada com o LED do que com a unidade halógena. Na base, a dureza de todos os materiais foi menor com o LED do que com a unidade halógena. A Z100 apresentou maior dureza que o Dyract e que a Definite independentemente da unidade de fotoativação. Não houve diferença significante na dureza entre os dois tempos de fotoativação para a face superior. Na base, a dureza foi maior quando os materiais foram polimerizados por 60 s. O LED não foi capaz de produzir a mesma dureza que a unidade halógena nos materiais resinosos testados.

Visual evaluation of in vitro cariostatic effect of restorative materials associated with dentifrices

O objetivo deste trabalho foi avaliar, in vitro, o efeito cariostático de 6 materiais restauradores contendo ou não flúor (Fuji II LC, F-2000, Degufil Mineral, Sure Fil and Z-250) associados à aplicação de dentifrícios (fluoretado e não-fluoretado; Sensodyne Fórmula Original and Sensodyne Sodium Bicarbonate) em esmalte dental humano. Cavidades classe V foram preparadas no esmalte de 240 fragmentos dentais, aleatoriamente divididos em 12 grupos (6 materiais e 2 dentifrícios). Após serem restauradas as cavidades, os fragmentos foram submetidos a ciclos térmicos e de desmineralização e remineralização, simulando um alto desafio cariogênico. Sobre os fragmentos restaurados, ainda, foram aplicados dentifrícios contendo ou não flúor, 5 min por dia. As diferenças no desenvolvimento de lesões experimentais de cárie adjacente às restaurações foram avaliadas por 5 examinadores calibrados, através de inspeção visual, atribuindo-se escores de 0 a 3. Os resultados foram avaliados pelo teste de Kruskal-Wallis seguido pelo teste de comparações múltiplas (a=0,05). Quando associados ao dentifrício fluoretado, os materiais restauradores não diferiram entre si em relação ao potencial cariostático (p>0,05). Quando os materiais foram utilizados em associação com o dentifrício não-fluoretado o Ketac-Fil apresentou o maior potencial cariostático, seguido pelo Fuji II LC e pelos demais materiais. O Ketac-Fil foi o único material que não diferiu significativamente quando associado com o dentifrício com ou sem flúor. Sob as condições experimentais do estudo, a associação dos materiais restauradores ao dentifrício fluoretado resultou em uma maior ação cariostática, exceto para o cimento de ionômero de vidro convencional, que não diferiu com a aplicação dos dentifrícios.

Evaluación clínica de la restauración con el compómero Compoglass en molares primarios / A clinical evaluation of the restoration with Compoglass compomer in primary molars

El propósito de este estudio fue evaluar la efectividad clínica del compómero Compoglass como material de obturación para caries de molares primarios. Se seleccionaron cuarenta niños entre 6 y 8 años con caries. Cada uno recibió dos restauraciones diferentes. Se colocaron ochenta restauraciones, cuarenta con el compómero Compoglass y cuarenta con resina Tetric. Se realizaron tres evaluaciones clínicas a tres, seis y doce meses, utilizando los criterios de USPHS. No hubo diferencias estadísticamente significativas con relación a la intergridad marginal y pigmentación. Al año de colocación, no se presentó reincidencia de caries en ningún caso de Compoglass, cinco de los molares restaurados con resina presentaron reincidencia de caries (p<0,05). Los compómeros, por sus propiedades anticariogénicas y estéticas son una buena alternativa para restauraciones en molares primarios.

Comparison of shear bond strength of composite, compomer and resin modified glass ionomer in primary and permanent teeth: an in vitro study.

The aim of this study was to determine the difference in shear bond strength between Composite, Compomer and Resin modified glass ionomer cement in primary and permanent teeth. Thirty extracted primary molars and thirty premolars were selected and buccal surfaces of all the teeth were made smooth with the help of 300 grit silicon carbide paper. These specimens were then divided into 6 groups. Restorative materials were placed on the buccal surfaces of respective specimens with the help of acrylic template. All the specimens were subjected to thermocycling and shear bond strength was tested under the Honsfield testing machine and results were recorded in megapascals (MPa). The resultant scores were tabulated and statistically analysed. It was observed that in case of primary teeth resin modified glass ionomer exhibited significantly higher shear bond strength as compared to composite and compomer, where as on permanent teeth composite demonstrated a significantly higher shear bond strength than that of the resin modified glass ionomer and compomer, where as compomer gave poor shear bond strength in both primary and permanent teeth.

The marginal seal of a flowable composite, an injectable resin modified glass ionomer and a compomer in primary molars--an in vitro study.

The present study was carried out to compare the marginal microleakage of some newer materials viz. a flowable composite, an injectable resin modified glass-ionomer and a compomer in Class I cavities of 30 non carious primary molars. After 0.5% basic fuchsin dye penetration and sectioning, the teeth were studied under stereomicroscope. The results obtained revealed that flowable composite showed significantly lower microleakage (p<0.05) as compared to injectable resin-modified glass ionomer and compomer. However, no significant difference was observed when injectable resin modified glass-ionomer cement was compared to compomer. This concludes that flowable composite materials adhere better to the primary teeth than resin modified glass ionomer and compomer.

Comparison of the effect of topical fluorides on the commercially available conventional glass ionomers, resin modified glass ionomers and polyacid modified composite resins--an in vitro study.

This study was undertaken to assess the effect of a single application of three professionally applied topical fluoride agents (Sodium fluoride 2%, Stannous fluoride 8% and APF 1.23%) on the surfaces of six modern esthetic restorative materials used in pediatric dentistry viz., two conventional glass ionomers (Fuji II and Shofu-restorative), two resin modified glass ionomers (Vitremer, with and without glaze, and Photac-fil Quick) and two Polyacid modified composite resins (Luxat and Hytac Aplitip). Mean surface roughness and surface micro hardness (SMH) measurements were the parameters employed for comparison. Results showed that APF gel applications significantly increased the surface roughness measurements and decreased SMH of all tested materials, which was pronounced in conventional glass ionomers when compared with resin modified glass ionomers and polyacid modified composite resins. NaF and SnF2 produced a statistically significant increase in the surface roughness of conventional glass ionomers without any significant change in surface roughness and SMH on rest of the materials tested, except for NaF on SMH values of Fuji II, which was statistically significant.

Materiales restauradores convencionales y adhesivos en molares temporarios: adaptación marginal / Conventional and adhesive restorative materials in primary molars: marginal adaptation

La problemática que plantea el reducido espesor de tejidos dentarios en elementos primarios, amplitud y escasa profundidad cavitaria, junto a la necesidad de buscar una "integración diente-restauración", con la mejor adaptacion, sellado marginal, baja incidencia de caries secundaria y la amplia gama de materiales restauradores que nos ofrece el mercado odontológico, motivó la realización del presente trabajo. El propósito de este estudio fue comprobar el grado de adaptación marginal por medio de microscopía electrónica de barrido (M.E.B.). Se emplearon 36 molares temporarios superiores y/o inferiores, recientemente extraídos. Se realizaron prepraaciones cavitarias clase I. Aleatoriamente fueron divididos en 6 grupos según el material restaurador: Grupo I: amalgama convencional; Grupo II: amalgama adherida; grupo III: resina compuesta; Grupo IV: cermet; grupo V: vitro-ionómero-resina; grupo VI: compómero. Posterioremente se obtuvieron réplicas que fueron metalizadas y analizadas con microscopía electrónica de barrido, a diferentes magnificaciones. Las mediciones se realizaron a nivel del BCP, tercio medio de las paredes de contorno y del ángulo axiopulpar. Las pruebas de comparaciones múltiples mostraron que el mejor comportamiento correspondió al compómero, con un valor medio de adaptación de 0,86_m, seguido del grupo III y V con 0,88_m y 1,14_m respectivamente. Los valores medios para el grupo II y IV fueron de 1,31_m en la amalgama adherida y 1,69_m para el cermet. El análisis de varianza determinó que la zona del ángulo axiopulpar mostró la más alta desadaptación en todos los materiales con diferencias significativas (p<0,0005) con respecto al BCP y pared axial que no difieren significativamente entre sí. Puede concluirse que las diferencias histológicas de los elementos temporarios con respecto a los permanentes y las dificultades en la estabilización de uniones fuertes a la dentina primaria serían la causa de las significativamente más bajas fuerzas de adhesión de los sistemas utilizados sobre todo a nivel del ángulo axiopulpar