Evaluación de la filtración apical al utilizar dos selladores biocerámicos / Evaluation of apical leakage when using two bioceramic sealers

Objetivo: Evaluar con técnica de diafanización el gra-do de filtración apical al utilizar dos selladores bio-cerámicos y la técnica de cono único con taper ex vivo. Materiales y métodos: Se utilizaron 60 premola-res inferiores humanos uniradiculares extraídos. La instrumentación se realizó con lima Primary 25/.07 (WaveOne Gold, Dentsply Maillefer), según protocolo del fabricante. Se irrigó con NaOCl 2,5% y EDTAC 17%. Para la obturación, la muestra se dividió aleatoria-mente en 4 grupos (n=15). Grupo 1: Cono único y Bio C Sealer. Grupo 2: Cono único y MTA Fillapex. Grupo control negativo: no se obturó. Grupo control positi-vo: Cono único y AH Plus. En todas las muestras se aplicaron dos capas de esmalte para uñas en toda la superficie dentaria con excepción del tercio apical y del grupo control positivo, que se esmaltó en su tota-lidad. Medio de filtración: tinta china negra por difu-sión pasiva. Se diafanizó con técnica de Robertson. Se usó programa AutoCad 2022, para medir filtración en milímetros lineales. Los datos se analizaron me-diante prueba de Kruskal-Wallis seguida por compa-raciones post hoc empleando el método de Conover (p<0,05, significativo). Resultados: La filtración con Bio C Sealer, MTA Fillapex, control negativo y control positivo tuvo una media (mínimo-máximo) de 0 (0-2), 1 (0-3), 6 (2-12) y 0 (0-0); sin diferencias significativas entre Bio C Sealer y MTA Fillapex (p>0,05), ni entre Bio C Sealer y control positivo (p>0,05); pero con di-ferencias significativas entre MTA Fillapex y control positivo (p<0,05), y entre control negativo y cual-quiera de los otros tres grupos (p<0,05). Conclusión: La obturación con Bio C Sealer lograría un nivel de sellado similar al que se obtiene con el control po-sitivo; mientras que la obturación con MTA Fillapex produciría un sellado ligeramente menos efectivo que el control positivo. Sin embargo, la filtración no variaría sustancialmente entre obturaciones con Bio C Sealer y MTA Fillapex (AU)

Objective: To evaluate the degree of apical filtration with diaphanization technique, using two bioceramic sealers and single cone technique with taper, ex vivo. Materials and methods: 60 extracted single-root human mandibular premolars were used. The instrumentation was carried out with primary file 25/.07 (WaveOne Gold, Dentsply Maillefer), according to the manufacturer's protocol. Irrigation was done with 2.5% NaOCl and 17% EDTAC. For obturation, the sample was randomly divided in 4 groups (n=15). Group 1: Single cone and Bio C Sealer. Group 2: Single cone and MTA Fillapex. Negative control group: it was not obturated. Positive control group: Single cone and AH Plus. In all samples, two layers of nail polish were applied to the entire tooth surface with exception of apical third and the positive control group, which was completely glazed. Filtration medium: black Chinese ink by passive diffusion. It was diaphanized with Robertson technique. AutoCad 2022 program was used to measure filtration in linear millimeters. Data were analyzed using Kruskal-Wallis test, followed by post hoc comparisons using Conover method (p < 0.05, significant). Results: Filtration with Bio C Sealer, MTA Fillapex, negative control and positive control had a mean (minimum-maximum) of 0 (0-2), 1 (0-3), 6 (2-12) and 0 (0-0); no significant differences between Bio C Sealer and MTA Fillapex (p > 0.05), nor between Bio C Sealer and positive control (p > 0.05); but with significant differences between MTA Fillapex and positive control (p < 0.05), and between negative control and any of the other three groups (p < 0.05). Conclusion: Obturation with Bio C Sealer would achieve a level of sealing similar to obtained with the positive control; while obturation with MTA Fillapex would produce a slightly less effective seal than the positive control. However, filtration would not vary substantially between fillings with Bio C Sealer and MTA Fillapex (AU)

Apexificación en una cita utilizando material biocerámico como tapón apical / Apexification in a single appointment using a bioceramic material as an apical plug

El objetivo fue realizar una técnica de apexificación en una cita, evaluando clínica y radiográficamente la formación de barrera dura apical, con seguimiento a nueve meses, al utilizar material biocerámico en dien-tes permanentes jóvenes. Se trataron 30 incisivos su-periores permanentes con ápice abierto y anteceden-tes de trauma, en pacientes de ambos géneros y 18-40 años. Las piezas (n=30) se dividieron en dos grupos (n=15). Grupo experimental: tratamiento de apexifica-ción con EndoSequence Root Repair Material (EERR), y grupo control: tratamiento con impresión apical. Se determinaron distribuciones de frecuencias y esta-dísticas descriptivas para cada variable, según es-cala de medición y distribución. Se realizaron IC 95%, test de Chi cuadrado con cálculo de residuos estan-darizados ajustados y test de Fisher. Se fijó nivel de significación p=0.05. Las diferencias de manifestacio-nes preoperatorias y postoperatorias según grupo fueron no significativas (p Fisher = 0.9140) y (p Fisher = 0.992), respectivamente. No se hallaron diferencias entre proporciones de hallazgos radiológicos preope-ratorios según grupo. Medidas trimestralmente, no hubo diferencias significativas entre proporciones de piezas con continuidad de cortical ósea y radiolucidez periapical postoperatoria según grupo, (p Fisher = 0.7780) y (p Fisher = 0.7909), respectivamente. Debi-do la escasa cantidad de trabajos que reportan el uso de EERR para esta técnica, se requiere de nuevos en-sayos clínicos con tamaños muestrales amplios, para compararlo con otros materiales y técnicas, y deter-minar si su tasa de éxito a largo plazo es mayor que a de los materiales y técnicas usadas actualmente (AU)

To perform apexification technique in one appointment, clinically and radiographically evaluating the formation of apical hard barrier, with follow-up at nine months, when using bioceramic material in young permanent teeth. Materials and methods: 30 permanent upper incisors with open apex and history of trauma were treated, in patients of both genders and 18-40 years of ages. The teeth (n=30) were divided into two groups (n=15). Experimental group: apexification treatment was performed with EndoSequence Root Repair Material (EERR), control group: treatment with apical impression. Frequency distributions and descriptive statistics were determined for each variable according to scale of measurement and distribution. 95% CI, Chi-square test with calculation of adjusted standardized residuals and Fisher's test were performed. The level of significance p=0.05 was set. The differences in preoperative and postoperative manifestations according to group were not statistically significant (Fisher's p = 0.9140) and (Fisher's p = 0.992), respectively. No differences were found between proportions of preoperative radiological findings according to group. Measured quarterly, there were no significant differences between proportions of teeth with bone cortical continuity and with postoperative periapical radiolucency according to group, (p Fisher = 0.7780) and (p Fisher = 0.7909), respectively. Due to the small number of works that report its use for this technique, is necessary to carry out new clinical trials with larger sample sizes, to compare it with other materials and techniques, and determine if its success rate in the long term is greater than that of currently used materials and techniques (AU)

Effect of whitening mouthrinses on color change of stained resin composites / Efeito de enxaguatórios clareadores na alteração de cor de resinas compostas previamente manchadas

Objective: The present study compared the effect of whitening mouthrinses (WM) on the color change of stained resin composites (RC). Material and Methods: Cylindrical specimens (6mm-diameter and 1mm-thickness) were prepared with the following RC (n=60/group): Filtek Z350XT (Z350- methacrylate-based), Admira Fusion (AD- ormocer-based), TPH3 (TPH- methacrylate-based), and Beautifil II (BII- giomer/methacrylate-based). The initial color was assessed with reflectance spectrophotometer using CIE L*a*b* system. The specimens were immersed in staining broth during 14 days, submitted to color evaluation (ΔE1) and randomly allocated in 4 subgroups (n=15), according to WM adopted: Listerine Whitening (LW-2% hydrogen peroxide), Plax Whitening (PW-1.5% hydrogen peroxide), Bromelain/papain (BP-experimental solution), and Deionized water (DW-negative control). The whitening cycle consisted of RC immersion in WM for 1 min and in artificial saliva for 30 min, simulating 12 weeks, and final color assessment was performed (ΔE2). Color change data were analysed by ANOVA and Tukey's tests (α=5%). Results: After staining, TPH showed the lowest ΔE1 values and Z350 showed the highest color change (p=0.001). The whitening effect promoted by LW was significantly higher than color alteration obtained with PW (ΔE2), and BII showed the highest color change values (ΔE2) after whitening cycle. Conclusion: LW exhibited the greatest whitening potential on stained RC, mainly with the Giomer (Beautifill II) and the Ormocer-based (Admira Fusion) materials. Bromelain/papain solution showed no whitening effect on stained RC. (AU)

Objetivo: O presente estudo comparou o efeito de enxaguatórios clareadores (EC) na alteração de cor de resinas compostas (RC) previamente manchadas. Material e Métodos: Espécimes cilíndricos (6mm de diâmetro e 1mm de espessura) foram preparados com as seguintes RC (n=60/grupo): Filtek Z350XT (Z350- metacrilato), Admira Fusion (AD- ormocer), TPH3 (TPH- metacrilato), e Beautifil II (BII- giomer/metacrilato). A cor inicial foi mensurada com espectrofotômetro de reflectância utilizando o sistema CIE L*a*b*. Os espécimes foram imersos em um caldo de manchamento durante 14 dias, submetidos a avaliação de cor (ΔE1) e alocados aleatoriamente em 4 subgrupos (n=15), de acordo com EC adotado: Listerine Whitening (LW-peróxido de hidrogênio a 2%), Plax Whitening (PW- peróxido de hidrogênio a 1,5%), Bromelina/papaína (BP-solução experimental), e Água deionizada (AD- controle negativo). O ciclo clareador consistiu na imersão da RC no EC por 1 min e na saliva artificial por 30 min, simulando 12 semanas, e a cor final foi mensurada (ΔE2). Os dados de alteração de cor foram analisados pelos testes ANOVA e Tukey (α=5%). Resultados: Após o manchamento, TPH apresentou o menor valor de ΔE1 e Z350 apresentou a maior alteração de cor (p=0,001). O efeito clareador promovido pelo LW foi significativamente maior que o obtido com o PW (ΔE2) e BII teve a maior alteração de cor (ΔE2) após o ciclo clareador. Conclusão: LW exibiu maior potencial clareador nas RC manchadas. BII apresentou maior alteração de cor em resposta à ação clareadora de ambos enxaguatórios à base de peróxido de hidrogênio testados.(AU)

Estudio tridimensional de reabsorciones internas obturadas con gutapercha inyectable o cono único de gutapercha más sellador biocerámico / Three-dimensional study of internal resorptions obturated with injected gutta-percha or single guttapercha cone and bioceramic sealer

Objetivo: Evaluar ex vivo, mediante reconstrucción tridimensional con tomografía computarizada de haz cónico, la presencia de vacíos, el volumen y la adaptación de la obturación a las paredes de conductos con reabsorciones dentinarias internas simuladas empleando gutapercha inyectable o cono único de gutapercha más sellador biocerámico. Materiales y métodos: Se utilizaron 10 incisivos centrales superiores humanos extraídos, en cada uno de los cuales se talló una reabsorción artificial para su obturación. La muestra fue sometida, de manera sucesiva, a dos condiciones experimentales diferentes: grupo 1, gutapercha inyectable con sistema EQ-V Master; grupo 2, cono de gutapercha más sellador biocerámico BioRoot RCS. Luego, se realizaron tomografías computarizadas de haz cónico y se hizo el estudio tridimensional. A continuación, se utilizó un programa para identificar los vacíos en la obturación y analizar cuantitativamente el volumen y la superficie cubierta por la obturación en los tercios coronario, medio (ampolla) y apical. Los datos fueron evaluados con la prueba de Wilcoxon (P<0,05). Resultados: El volumen de obturación y la superficie dentinaria en contacto con la obturación fueron similares para las dos técnicas empleadas. Las diferencias entre ambos grupos no fueron estadísticamente significativas (P>0,05). Conclusión: Aunque se observaron vacíos con ambas técnicas (en contacto con la superficie dentinaria cuando se empleó gutapercha inyectable, y en el interior de la obturación cuando se usó cono único de gutapercha más sellador BioRoot RCS), las dos rellenaron adecuadamente las reabsorciones simuladas (AU)

Aim: Ex vivo, tridimensional evaluation with cone beam computed tomography (CBCT), of the presence of voids, the obturation volume and adaption to the root canal walls with simulated internal root resorption, using injected gutta-percha or bioceramic sealer with single gutta-percha cone. Materials and methods: Ten maxillary extracted central human incisors were used and artificial internal root resorption was created in each one. For the root canal obturation, each tooth was subjected to two different experimental conditions successively, conforming two matched groups: Group I: EQ-V Master injected thermo plasticized gutta-percha system. Group II: gutta- percha point plus BioRoot RCS bioceramic sealer. First, the root canals were filled with injected gutta-percha and then, with the bioceramic sealer. Then the teeth were scanned with CBCT and subsequently a digital three-dimensional reconstruction was performed. The presence of voids, obturation volumne and the dentin wall surface covered by the filling material was quantitative analyzed through a software; at the coronal, middle (blister) and apical thirds. The data was analyzed by using Wilcoxon test (P<0.05). Results: The filling material volume and the dentin wall surface covered by it, was similar in both root canal obturation techniques. There was no significant difference between both groups (P>0.05). Conclusion: Although voids were observed in both groups (when the injected thermo plasticized gutta-percha system was used the voids were at the external surface and when BioRoot RCS + gutta-percha cone was used the voids were into the filling material), the obturation of simulated root canal resorption cavities was similar with both obturation techniques (AU)

Propriedades mecânicas e ópticas das cerâmicas feldspáticas e dissilicato de lítio: Revisão de literatura / Mechanical and optical properties of feldspathic ceramics and lithium disilicate: literature review

Objetivo: o objetivo dessa revisão de literatura é apresentar os dados existentes sobre capacidade estética e resistência à fratura das cerâmicas feldspáticas e dissilicato de lítio confeccionadas para o uso em CAD/CAM. Material e Métodos: para realizar o estudo foram levantados artigos originais sobre as cerâmicas feldspáticas e dissilicato de lítio em periódicos na base de dados PubMed e ScienceDirect, desde 2015 até 2020 utilizando como termos de busca "lithium disilicate AND esthetic AND CAD/CAM", "lithium disilicate AND fadigue AND CAD/CAM", "lithium disilicate AND fracture AND CAD/CAM", "feldspathic AND esthetic AND CAD/CAM", "feldspathic AND fadigue AND CAD/CAM", "feldspathic AND fracture AND CAD/CAM". Ainda, foram selecionados artigos de relevância publicados em datas anteriores selecionados pelos autores. Constam trabalhos longitudinais, de revisão de literatura, casos clínicos e pesquisas in vitro. Resultados: no total, 209 artigos foram encontrados e somente 16 foram incluídos para comparação. Os dados apresentaram boa capacidade estética para ambos materiais, sendo o dissilicato com maior resistência à fratura. Conclusão: concluiu-se que cerâmicas feldspáticas e dissilicato de lítio para CAD/CAM apresentam capacidade ópticas satisfatórias para restaurações estéticas quando utilizado os blocos multicores, devendo-se optar pelo dissilicato de lítio em situações de maior esforço mastigatório ou menor espessura da peça protética

Objective: this literature review presents the existing data on the esthetic capacity and fracture resistance of feldspathic and lithium disilicate ceramics made for CAD/CAM. Material and Methods: original articles on feldspathic ceramics and lithium disilicate were collected in journals in the PubMed and ScienceDirect databases from 2015 to 2020 using the search terms "lithium disilicate AND esthetic AND CAD/CAM," "lithium disilicate AND fatigue AND CAD/CAM," "lithium disilicate AND fracture AND CAD/CAM," "feldspathic AND esthetic AND CAD/CAM," "feldspathic AND fatigue AND CAD/CAM," "feldspathic AND fracture AND CAD/CAM." relevant articles published previously to 2015 were also selected by the authors. Longitudinal studies, literature reviews, clinical cases and in vitro studies were included. Results: in total, 209 articles were selected and 16 included for comparison. Data presented good esthetic capability for both materials, disilicate presented higher fracture strength. Conclusion: the study concluded that feldspathic ceramics and lithium disilicate for CAD/CAM have satisfactory optical capacity for esthetics restorations when multicolor blocks are used. Lithium disilicate should be chosen in situations of greater masticatory effort or thinness of the prosthetic piece

Efeito da pigmentação extrínseca nas cerâmicas à base de dissilicato de lítio submetidas aos processos de desgaste e biodegradação nas propriedades mecânicas e aderência bacteriana / Effect of extrinsic pigmentation on lithium disilicate-based ceramics subjected to wear and biodegradation processes on mechanical properties and bacterial adherence

O objetivo deste estudo foi avaliar se há alteração no comportamento mecânico e na aderência microbiológica da cerâmica à base de dissilicato de lítio com a técnica de pigmentação extrínseca aplicada, após ser submetida a diferentes condições experimentais. Foram confeccionadas 160 amostras, divididas em grupos com e sem pigmentação (n=80). Destes, cada grupo foi subdividido em Controle, Desgate, Biodegradação e Desgaste com Biodegradação (n=20).15 amostras de cada subgrupo foram submetidas ao teste de resistência à flexão e 5 para o teste de aderência microbiológica. As amostras passaram anteriormente por testes complementares para caracterização da superfície (rugosidade, perfilometria volumétrica e microscopia eletrônica de varredura (MEV)). Os resultados foram submetidos a análise estatística descritiva (média e desvio padrão) e inferencial, mediante o teste paramétrico de análise de variância (ANOVA) dois fatores e teste de Tukey ( = 0,05). O fator pigmentação extrínseca influenciou negativamente no comportamento mecânico da cerâmica, apresentando significância estatística (p = 0,000), assim como a interação entre o tipo de condição experimental e a pigmentação (p = 0,020). Entretanto, na aderência microbiológica, foi a condição experimental que influenciou negativamente no comportamento microbiológico (p = 0,000), assim como a interação entre a condição experimental e a pigmentação (p = 0,000). Nas análises complementares, observou-se que a interação entre os fatores aumentou a rugosidade superfial (p = 0,000) e aumentou o volume perdido pelo desgatse (p = 0,040). As microscopias da superficie mostram as características de cada grupo, mostrando as diferenças entre as condições experimentais com e sem pigmentação extrínseca. E as microscopias da aderência microbiológica ilustram e confirmam os resultados obtidos no teste estatístico. Concluiu-se que a pigmentação extrínseca altera as propriedades mecânicas da cerâmica de dissilicato de lítio, reduzindo a resistência à flexão e aumentando a rugosidade superficial e o desgaste. Porém, a aderência microbiológica foi aumentada pela condição experimental. Entretanto, a interação entre os fatores contribuiu para esse aumento e para agravar a alteração nas propriedades mecânicas(AU)

The objective of this study was to evaluate the mechanical and microbiological behavior of the ceramics based on lithium disilicate with extrinsic characterization. For this, 160 discs were made, divided into two large groups, with extrinsec characterization and without, after which each was divided into four groups (n = 20): Control, Wear, Biodegradation and Biodegradation with Wear. Fifteen samples from each group were submitted to the flexural strength test and 5 submitted to the microbiological adherence test. Prior to the destructive test of flexural strength, the representative samples of each group underwent complementary tests for surface characterization. The results were submitted to descriptive statistical analysis (mean and standard deviation) and inferential, using the parametric analysis of variance (ANOVA) two way and Tukey test ( = 0,05). The extrinsec characterization factor influenced the mechanical behavior of the ceramic, presenting statistical significance (p = 0.000), as well as the interaction between the type of experimental condition and the extrinsec characterization (p = 0.020). However, in the microbiological adherence, it was the experimental condition that influenced the microbiological behavior (p = 0.000), as well as the interaction between the experimental condition and the extrinsec characterization (p = 0.000). It was concluded that the makeup influenced the mechanical behavior of the ceramic, and the experimental condition influenced the microbiological adherence. The interaction between the factors influenced both the mechanical behavior and the microbiological adherence(AU)

Evaluation of the color stability of light cured composite resins according to the resin matrices / 대한치과재료학회지

The purpose of this study was to evaluate the color stability of light cured composite resins according to the resin matrices. Three kinds of resin matrices such as Bis-GMA (Venus® Diamond; VD), Silorane (FiltekTM P90; P90), and Ormocer (Admira; Ad) were selected. Each of them were used to prepare 30 specimens. The initial CIE L*a*b* values were measured by means of a Spectrophotometer (NF999, Nippon Denshoku, Japan). For accelerated aging process, the specimens were immersed in a circulating water bath with distilled water at 60℃. Spectrophotometric analyses were made after immersion of 8, 16, 24, 41 days and the color difference (ΔE*) was calculated. The L* value increased compared with initial L* value. VD had the greatest L* value change and Ad had the smallest L* value change (p<0.05). Ad had the greatest a* value change and VD had the smallest a* value change (p<0.05). The b* value of P90 increased steadily in positive value (+)(p<0.05). ΔE* of Ad had the smallest value and that of P90 had the greatest change with time. According to this study, the value of light cured composite resins was increased with water sorption and color of those changed into greenish and yellowish. And according to the evaluation of color stability, Ad with Ormocer as resin matrices had the best color stability with time in oral environment and P90 with Silorane as resin matrices had the lowest color stability with time. And VD had the greatest initial ΔE*.

Retreatment Efficacy of Endodontic Bioceramic Sealers: A Review of the Literature / Eficacia del retratamiento de cementos endodónticos biocerámicos: Revisión de Literatura

Abstract The endodontic retreatment is a feasible solution when post-operative apical periodontitis persists or develops. The complete removal of the filling materials is important in order to ensure the unobstructed contact of the intracanal disinfectants with the microbes. As a new generation of bioceramic endodontic sealers has emerged, their removal efficacy from the root canal system during retreatment is a matter of concern among clinicians. The aim of this article is to provide a comprehensive review of the current literature on the retreatability of these novel obturating materials. A significant amount of bioceramic sealer remnants in the root canal walls was observed in all studies. Even though canal cleanliness could not be obtained at an ideal level, the re-establishment of the working length and patency can be considered manageable and comparable to other endodontic sealers.

Resumen El retratamiento endodóntico es una solución factible cuando la periodontitis apical post-operatoria persiste o se desarrolla. La eliminación completa de los materiales obturadores es importante para garantizar el contacto y acción de los desinfectantes e irrigantes endodónticos con los microorganismos persistentes. A medida que ha surgido una nueva generación de selladores endodónticos biocerámicos, su eficacia de eliminación del sistema de conductos radiculares durante el retratamiento es motivo de preocupación entre los profesionales. El objetivo de este artículo es proporcionar una revisión exhaustiva de la literatura actual sobre la influencia o posibles limitantes del uso de este tipo de cementos bioactivos durante el retratamiento endodóntico. Los estudios determinaron una cantidad significativa de restos de selladores biocerámicos en las paredes del conducto radicular. Aunque la limpieza del canal no se pudo obtener a un nivel "ideal", el restablecimiento de la longitud de trabajo y la permeabilidad se puede considerar manejable y comparable a otros selladores endodónticos.

Do new matrix formulations improve resin composite resistance to degradation processes?

The aim of this study was to determine the degradation resistance of three new formulations-silorane-, Ormocer- and dimer-acid-based materials-and compare them to the traditional dimethacrylate-based materials. One silorane- (Filtek P90, P90), one Ormocer- (Ceram-X, CX), one dimer-acid- (N'Durance, ND) and two dimethacrylate-based (Filtek P60, P60; Tetric Ceram, TC) materials were investigated. Water sorption (Wsp) and solubility (Wsl) were determined after the materials were immersed in water for 28 days. Knoop hardness (KH) was determined before and after 24 h immersion in pure ethanol. The flexural-strength (FS) was determined by the bending test after one-week storage in a dry environment or after one-week immersion in pure ethanol. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95%). The three new formulations showed lower Wsp than the dimethacrylate-based formulation. CX (0.50 ± 0.17%) and ND (0.72 ± 0.19%) exhibited the lowest Wsp, whereas P90 (0.02 ± 0.03%) and P60 (0.04 ± 0.03%) showed the lowest Wsl. All resins showed reduced Knoop hardness number (KHN) after ethanol immersion. P60 presented the lowest decrease in KH value (19 ± 5%). TC (48 ± 3%) and P90 (39 ± 9%) showed the highest KHN decrease after ethanol storage. The FS of CX, ND and TC were affected by ethanol storage. The new formulations did not improve the degradation resistance, as compared with the traditional methacrylate-based materials.

[Degree of conversion of micro-hybrid, nano-hybrid and Ormocer composites using LED and QTH light-curing units]

The aim of this study was to measure the degree of conversion [DC] of three types of composite resins [micro-hybrid, nano-hybrid and Ormocer] with different light curing units [LED LCU and QTH LCU] in two depths. Three commercially available dental resin composites were used in this study: [Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade], [Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade], [Ceram X, Dentsply, Germany-M[2] shade]. Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit [Coltolux 75-Colten] and the other five specimens were cured by LED [Demi-Kerr]. Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR [Bruker-tensor 27]. The data were analyzed by 3-way ANOVA test. There was significant difference between tested composite resins [P<0.001]. The results of top surfaces were significantly different from those observed at 2-mm depth [P<0.001]. The type of curing unit affected the polymerization of Ceram X resin composite. This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites

A study of contraction shrinkage of composite resins and ormocers with various curing times / 대한치과보존학회지

Ormocer has organic-inorganic compound polymers. One of advantages of ormocer is reduced polymerization shrinkage. The purpose of this study was to compare the amount of contraction shrinkage of composite resins and ormocers. Additionally, the time of each material when there is no further change of contraction shrinkage was analysed. Four brands of composite resins (P-60, Surefil, Z-250 and Denfil) and two brands of ormocers (Definite and Admira) were used. 20 seconds, 40 seconds and 60 seconds of curing times were given. Contraction shrinkage of them were measured using a linometer for 80 seconds. The effect of material and curing time to contraction shrinkage at the time of 80 seconds was analysed by two-way ANOVA. The effect of time to contraction shrinkage was analysed by one-way ANOVA, and the time when there was no further change of the contraction shrinkage was analysed. The results are as follows : 1. P-60, Definite, Z-250 and Denfil had no further change of contraction shrinkage from the time of 20 seconds, and Surefil and Admira had no further change of contraction shrinkage from the time of 10 seconds. 2. Statistical analysis revealed volumetric shrinkage varied among material (p<0.05). No significant difference of contraction shrinkage among different curing times was found, and there was no effect of interaction between materials and curing times to contraction shrinkage. 3. Definite and Admira showed the statistically same contraction shrinkage with those of Z-250 and P-60, which is higher than that of Surefil and lower than that of Denfil (p<0.05).