Evaluation of material waste, dimensional stability, and detail reproduction of polyvinyl siloxane impression materials mixed with different mixing tips.

STATEMENT OF PROBLEM: Redesigned mixing tips, promising less impression material waste, have been marketed. However, whether their use adversely affects the dimensional stability and detail reproduction of the impression material is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the dimensional stability, detail reproduction, and material waste of different polyvinyl siloxane impression materials (regular and light-body) mixed with 2 different mixing tips (MIXPAC T-Mixer mixing tip and MIXPAC helical mixing tip). MATERIAL AND METHODS: Six different polyvinyl siloxane impression materials were used in 2 different consistencies: Virtual Monophase and Virtual Light Body (Ivoclar Vivadent AG), Express XT Regular and Express XT Light Body (3M ESPE), and Panasil initial contact Regular and Panasil initial contact Light (Kettenbach). The polyvinyl siloxane impression materials were mixed with 2 different mixing tips: conventional helical and T-Mixer (n=10). The specimens were prepared in a metal matrix as per specification #19 of the American National Standards Institute/American Dental Association (ANSI/ADA) and International Organization for Standardization (ISO) 4823:2015. The materials were mixed with both mixing tips as per the manufacturer's instructions, inserted into a perforated custom tray on the matrix, and allowed to polymerize completely. The dimensional stability was calculated based on the measurement of the reproduction of lines engraved in the metal matrix. Detail reproduction was evaluated through analysis of continuity and reproducibility of those lines, immediately, 7 days, and 14 days after polymerization. Material waste was assessed by the difference between the initial (before mixing) and final weight (after complete polymerization) of both mixing tips. The data on dimensional stability and detail reproduction among the materials were submitted to the Kruskal-Wallis test, followed by the Student-Newman-Keuls test (α=.05). Comparison between the mixing tips was carried out with the Mann-Whitney test (α=.05), while the comparison among the periods of analysis (immediate, 7 days, and 14 days) was carried out with the Friedman test (α=.05). The data on material waste between the mixing tips were submitted to 1-way ANOVA, followed by the Tukey honestly significant difference tests (α=.05). RESULTS: The T-Mixer mixing tip resulted in reduced material waste. For dimensional stability, Virtual Light mixed with T-Mixer resulted in lower dimensional change (0.53 ±0.58%) compared with the helical mixing tip (1.09 ±0.43%). Among the materials, Panasil Light presented higher values of dimensional change at immediate and 7-day analysis when mixed with T-Mixer tip with a statistical difference compared with Express Light, Virtual Light, and Panasil Regular (P<.05). In general, both mixing tips provided similar results in all periods of analysis (P>.05) for qualitative analysis of detail reproduction. CONCLUSIONS: The T-Mixer tip resulted in less material waste compared with the helical mixing tip. In general, light-body materials showed higher dimensional stability when the T-Mixer tip was used compared with the conventional tip. In general, reduced detail reproduction was observed after periods longer than 7 days after impression making.

Relined fiberglass posts: influence of resin opacity on the bond strength to intraradicular dentin.

This study aimed to evaluate the bond strength between relined fiberglass posts with different composite resin opacities in different thirds of the intraradicular dentin. Thirty single-rooted premolars were endodontically treated and divided into three groups (n=10): fiberglass posts relined with translucent composite resin, fiberglass posts relined with opaque composite resin, and fiberglass posts without relining. After cementation of the posts, the specimens were cut perpendicular to the long axis of the tooth in slices of approximately 1.3 mm of each third to be analyzed (cervical, middle, and apical) and then subjected to the push-out test. The bond strength (MPa) data were subjected to Shapiro-Wilk normality tests and two-way repeated measures analysis of variance, considering the experimental groups and different regions as study factors. Tukey's post-hoc test (p<.05) was applied for comparisons between the groups. In the cervical third, higher values of bond strength were found for the group relined with translucent resin, with a statistically significant difference for the other groups. In the other regions, both opaque and translucent resins showed similar results, but both showed higher values of bond strength compared to fiberglass posts without relining. The bond strength of fiberglass posts to different thirds of intraradicular dentin is influenced by composite resin relining as well as the opacity of the resin. The use of translucent composite resin is a more effective alternative for fiberglass posts relining.

Influence of thickness and degree of opacity of lithium disilicate on the degree of conversion and bond strength of resin cements.

The aim of this study was to evaluate the influence of various opacities and thicknesses of lithium disilicate on the degree of conversion (DC) of two resin cements and on their bond strength (BS) to the ceramic. Two hundred and forty ceramic samples of lithium disilicate with high translucency (HT), low translucency (LT), and medium opacity (MO) were obtained from IPS e. max CAD in five different thicknesses. Light-cured and dual-cured resin cements were used for DC (n = 9) and BS (n = 8). Cement samples were light-cured under ceramic samples and analyzed using a Raman confocal spectrometer to determine the DC. For BS, resin cement cylinders were fabricated using ceramic samples which were thsen subjected to a microshear bond strength test. The mean values were provided for statistical analysis. The increase in thickness resulted in a decrease in DC for both cements under all experimental conditions, but only affected the BS of the light-cured cement for the MO ceramic. Comparing the opacities, the most translucent ceramics with particular thicknesses exhibited higher DC values than the less translucent ceramics. The LT and MO ceramics with certain thicknesses exhibited the highest BS values than the HT. The dual-cured cement generally showed highest values in both analyses than the light-cured cement. A thicker and more opaque ceramic material can reduce the DC of the cement. The BS decreases with the increasing thickness of the more-opaque ceramics.

Do different adhesives influence the color stability and fluorescence of composite restorations after aging?

This study aimed to evaluate the influence of dental adhesive color on the chromatic stability and fluorescence intensity of composite resin restorations of different thicknesses. Ninety bovine enamel samples were obtained and restored with resin composite varying thicknesses of restorative material and enamel (1.0 mm enamel and 1.0 mm composite; 1.5 mm enamel and 0.5 mm composite; 0.5 mm enamel and 1.5 mm composite). The restorations were made of composite resin (Opallis E-bleach H) using different types of dental adhesives: Ambar, Ambar APS, and Single Bond Universal (n=10). The samples were subjected to color measurement tests in a spectrophotometer using CIEDE2000 and fluorescence intensity measurements before and after aging in a red wine coloring solution. Data were subjected to analysis of variance (ANOVA) and Tukey's test (α = 0.05). There were no statistically significant changes in color stability or fluorescence intensity for restorations made of different materials or thicknesses (p>0.05). Single Bond Universal showed greater color stability at 0.5 mm thickness (ΔE00 = 4.4 ± 1.6) compared to other thicknesses of the same material (p=0.003), as well as a greater difference in fluorescence intensity after aging at 1.5 mm thickness (-414.9 ± 103.8) compared to other materials (p=0.0002). Overall, it was concluded that the different adhesive systems did not influence the color stability and fluorescence of restorations of different thicknesses.

Surface characterization of indirect restorative materials submitted to different etching protocols.

OBJECTIVES: This in vitro study aimed to evaluate the effect of different times and concentrations of hydrofluoric acid etching on the surface of indirect restorative materials obtained from blocks used in CAD-CAM technology. METHODS: Specimens (4 mm × 4 mm × 0.8 mm) were obtained for each indirect restorative material: zirconia-reinforced lithium monosilicate ceramic (Celtra Duo), nanoceramic resin (Lava Ultimate), and polymer-infiltrated ceramic network material (Vita Enamic). The materials were submitted to etching with 5% or 10% hydrofluoric acid for 20, 40, 60, or 90 s. A control group for each material was evaluated without any surface treatment, totaling nine experimental groups for each material (n = 10). The specimens were evaluated for surface roughness (Ra and Rz), confocal optical microscopy, the contact angle (θ), surface free energy (γs), total free interaction energy (∆G) using a goniometer, and microshear bond strength to resin cement. Specimen images were obtained using scanning electron microscopy, confocal optical microscopy, and atomic force microscopy. Data on the surface roughness, the contact angle, surface free energy, total free interaction energy, and bond strength were subjected to two-way ANOVA and Tukey´s test (α=0.05). RESULTS: In general, Celtra Duo showed better results after etching with 10% hydrofluoric acid for 40 or 60 s. Lava Ultimate showed better performance after etching with 10% hydrofluoric acid for 20 or 40 s, whereas Vita Enamic showed better results after etching with 5% hydrofluoric acid for 90 s. CONCLUSION: Each material showed different characteristics after etching with hydrofluoric acid. Knowledge of the proper protocol for each material is essential to ensure improvements in the adhesion process and durability of indirect restorations. In general, Celtra Duo presented mechanical properties superior to those of Lava Ultimate and Vita Enamic. CLINICAL SIGNIFICANCE: Specific etching protocols must be recommended for each indirect material because longer exposure to hydrofluoric acid can jeopardize the surface, thus affecting the mechanical and bond strength properties.

Color stability and surface roughness of chitosan- and nanodiamond-modified bisacrylic resin.

The aim of this study is to evaluate the effect of chitosan or nanodiamond incorporation on the color stability and surface roughness of a bisacrylic resin subjected to artificial aging. Four bisacrylic resins were evaluated, namely, control, chitosan-modified material, nanodiamond-modified material, and chitosan-nanodiamond-modified material. Twenty-four specimens were prepared for each material. The surface roughness was determined using a profilometer with a cut-off of 0.25 mm. The baseline color was measured according to the CIE L*a*b* system using a reflectance spectrophotometer. After these tests, the specimens were individually immersed in cola soft drink, red wine, or distilled water (n = 8) for 28 days. After the aging, the surface roughness and final color were re-evaluated. The color stability was determined using the difference between the coordinates obtained before and after the aging process. The data on roughness and color change were evaluated using ANOVA and the Tukey test (α = 0.05). The results show that the incorporation of nanodiamonds and chitosan into a bisacrylic resin provided a better color stability to the materials (p = 0.007). The storage in red wine resulted in a higher variation in the surface roughness values, especially when only the nanodiamond was incorporated to the material (p < 0.05). The incorporation of both chitosan and nanodiamonds are promising in providing an improvement in the properties of the bisacrylic resin when they are simultaneously incorporated in the product.

Relined fiberglass posts: influence of resin opacity on the bond strength to intraradicular dentin

Abstract This study aimed to evaluate the bond strength between relined fiberglass posts with different composite resin opacities in different thirds of the intraradicular dentin. Thirty single-rooted premolars were endodontically treated and divided into three groups (n=10): fiberglass posts relined with translucent composite resin, fiberglass posts relined with opaque composite resin, and fiberglass posts without relining. After cementation of the posts, the specimens were cut perpendicular to the long axis of the tooth in slices of approximately 1.3 mm of each third to be analyzed (cervical, middle, and apical) and then subjected to the push-out test. The bond strength (MPa) data were subjected to Shapiro-Wilk normality tests and two-way repeated measures analysis of variance, considering the experimental groups and different regions as study factors. Tukey's post-hoc test (p<.05) was applied for comparisons between the groups. In the cervical third, higher values of bond strength were found for the group relined with translucent resin, with a statistically significant difference for the other groups. In the other regions, both opaque and translucent resins showed similar results, but both showed higher values of bond strength compared to fiberglass posts without relining. The bond strength of fiberglass posts to different thirds of intraradicular dentin is influenced by composite resin relining as well as the opacity of the resin. The use of translucent composite resin is a more effective alternative for fiberglass posts relining.

Resumo Este estudo teve como objetivo avaliar a resistência de união entre pinos de fibra de vidro anatomizados com resinas compostas de diferentes opacidades em diferentes terços da dentina intrarradicular. Trinta pré-molares uniradiculares foram tratados endodonticamente e divididos em três grupos (n=10): pinos de fibra de vidro anatomizados com resina composta translúcida, pinos de fibra de vidro anatomizados com resina composta opaca e pinos de fibra de vidro sem anatomização. Após a cimentação dos pinos, os corpos de prova foram cortados perpendicularmente ao longo eixo do dente em fatias de aproximadamente 1,3 mm de cada terço a ser analisado (cervical, médio e apical) e posteriormente submetidos ao teste de push-out. Os dados de resistência de união (MPa) foram submetidos a testes de normalidade de Shapiro-Wilk e ANOVA dois fatores para análises repetidas, considerando os grupos experimentais e diferentes regiões como fatores de estudo. O teste post-hoc de Tukey (p=0,05) foi aplicado para comparações entre os grupos. No terço cervical foram encontrados maiores valores de resistência de união no grupo com anatomização com resina translúcida, com diferença estatisticamente significativa para os demais grupos. Nas demais regiões, tanto as resinas opacas quanto as translúcidas apresentaram resultados semelhantes, mas ambas apresentaram valores de resistência de união superiores aos pinos de fibra de vidro sem anatomização. A resistência de união dos pinos de fibra de vidro aos diferentes terços da dentina intrarradicular é influenciada pela anatomização da resina composta, bem como pela opacidade da resina. A utilização de resina composta translúcida é uma alternativa mais eficaz para a anatomização de pinos de fibra de vidro.

Minimum intervention management of diastema closure using cordless displacement system and laminate veneers: A 2-year follow-up.

This case report presents a minimally invasive diastema treatment using cordless gingival displacement system allowing a very conservative intervention. A 32-year-old female patient who presented with diastema in her upper front teeth opted for a treatment using laminate veneers to ensure achieving adequate tooth proportion and gingival levels. Having a displacement material that exerts excessive pressure during the displacement process can lead to disruption of the junctional epithelium and damage to periodontal tissues. This case report focuses on the effectiveness of the use of a minimally invasive method of gingival management. Two-year follow-up no infiltration, sensitivities, or fractures were detected on teeth, and indirect restorations, the purposed treatment allowed a quick, effective, and durable resolution for diastema.

Do different adhesives influence the color stability and fluorescence of composite restorations after aging?

Abstract This study aimed to evaluate the influence of dental adhesive color on the chromatic stability and fluorescence intensity of composite resin restorations of different thicknesses. Ninety bovine enamel samples were obtained and restored with resin composite varying thicknesses of restorative material and enamel (1.0 mm enamel and 1.0 mm composite; 1.5 mm enamel and 0.5 mm composite; 0.5 mm enamel and 1.5 mm composite). The restorations were made of composite resin (Opallis E-bleach H) using different types of dental adhesives: Ambar, Ambar APS, and Single Bond Universal (n=10). The samples were subjected to color measurement tests in a spectrophotometer using CIEDE2000 and fluorescence intensity measurements before and after aging in a red wine coloring solution. Data were subjected to analysis of variance (ANOVA) and Tukey's test (α = 0.05). There were no statistically significant changes in color stability or fluorescence intensity for restorations made of different materials or thicknesses (p>0.05). Single Bond Universal showed greater color stability at 0.5 mm thickness (ΔE00 = 4.4 ± 1.6) compared to other thicknesses of the same material (p=0.003), as well as a greater difference in fluorescence intensity after aging at 1.5 mm thickness (-414.9 ± 103.8) compared to other materials (p=0.0002). Overall, it was concluded that the different adhesive systems did not influence the color stability and fluorescence of restorations of different thicknesses.

Resumo O objetivo deste estudo foi avaliar a influência da cor do adesivo dental na estabilidade cromática e intensidade de fluorescência das restaurações de resina composta de diferentes espessuras. Foram obtidos noventa amostras de esmalte bovino que foram restaurados com resina composta, variando a espessura do material restaurador e do esmalte (1,0 mm de esmalte e 1,0 mm de compósito; 1,5 mm de esmalte e 0,5 mm de compósito; 0,5 mm de esmalte e 1,5 mm de compósito). As restaurações foram feitas de resina composta (Opallis E-bleach H) utilizando diferentes tipos de adesivos odontológicos: Ambar, Ambar APS, e Single Bond Universal (n=10). As amostras foram submetidas a testes de medição de cor em um espectrofotômetro usando CIEDE2000 e medições de intensidade de fluorescência antes e depois do envelhecimento em uma solução de coloração de vinho tinto. Os dados foram submetidos à análise de variância (ANOVA) e ao teste de Tukey (α = 0,05). Não houve mudanças estatisticamente significativas na estabilidade da cor ou intensidade de fluorescência para restaurações feitas de diferentes materiais ou espessuras (p>0,05). O Single Bond Universal mostrou maior estabilidade de cor a 0,5 mm de espessura (ΔE00 = 4,4 ± 1,6) em comparação com outras espessuras do mesmo material (p=0,03), bem como uma maior diferença na intensidade de fluorescência após o envelhecimento a 1,5 mm de espessura (-414,9 ± 103,8) em comparação com outros materiais (p=0,0002). Em geral, concluiu-se que os diferentes sistemas adesivos não influenciaram a estabilidade de cor e a intensidade de fluorescência das restaurações de diferentes espessuras.