Abstract This study evaluated the effect of implantoplasty on different bone insertion levels of exposed implants. A model of the Bone Level Tapered implant (Straumann Institute, Waldenburg, Switzerland) was created through the Rhinoceros software (version 5.0 SR8, McNeel North America, Seattle, WA, USA). The abutment was fixed to the implant through a retention screw and a monolithic crown was modeled over a cementation line. Six models were created with increasing portions of the implant threads exposed: C1 (1 mm), C2 (2 mm), C3 (3 mm), C4 (4 mm), C5 (5 mm) and C6 (6 mm). The models were made in duplicates and one of each pair was used to simulate implantoplasty, by removing the threads (I1, I2, I3, I4, I5 and I6). The final geometry was exported in STEP format to ANSYS (ANSYS 15.0, ANSYS Inc., Houston, USA) and all materials were considered homogeneous, isotropic and linearly elastic. To assess distribution of stress forces, an axial load (300 N) was applied on the cusp. For the periodontal insert, the strains increased in the peri-implant region according to the size of the exposed portion and independent of the threads’ presence. The difference between groups with and without implantoplasty was less than 10%. Critical values were found when the inserted portion was smaller than the exposed portion. In the exposed implants, the stress generated on the implant and retention screw was higher in the models that received implantoplasty. For the bone tissue, exposure of the implant’s thread was a damaging factor, independent of implantoplasty. Implantoplasty treatment can be safely used to control peri-implantitis if at least half of the implant is still inserted in bone.

O estudo avaliou a profundidade de polimerização de um cimento resinoso dual, através da dureza Knoop (KHN), ativado em diferentes distâncias e espessuras de compósito resinoso. A dentina bovina foi planificada e embutida em resina, coberta com filme de PVC, onde um molde (0,8 mm x 5 mm) sobreposto foi preenchido com cimento e coberto com outro filme de PVC. A fotoativação (40 s) foi realizada através de discos de compósito (2, 3, 4 ou 5 mm-espessura) com a luz a 0, 1, 2 ou 3 mm de distância da superfície do compósito. Após armazenagem, os espécimes foram seccionados e a KHN medida (superfície, centro e base). Os dados foram submetidos à ANOVA com parcelas subdivididas e teste de Tukey (a=0.05). A espessura do compósito diminuiu a dureza do cimento. O aumento da distância de fotoativação diminuiu a dureza na superfície do cimento. Espécimes mostraram menores valores de dureza na região de base e os maiores valores no centro. A dureza do cimento resinoso foi influenciada pela espessura da restauração indireta e pela distância entre a ponta da unidade fotoativadora e a superfície do cimento resinoso.

This study evaluated the Knoop hardness and polymerization depth of a dual-cured resin cement, light-activated at different distances through different thicknesses of composite resin. One bovine incisor was embedded in resin and its buccal surface was flattened. Dentin was covered with PVC film where a mold (0.8-mm-thick and 5 mm diameter) was filled with cement and covered with another PVC film. Light curing (40 s) was carried out through resin discs (2, 3, 4 or 5 mm) with a halogen light positioned 0, 1, 2 or 3 mm from the resin surface. After storage, specimens were sectioned for hardness measurements (top, center, and bottom). Data were subjected to split-plot ANOVA and Tukey's test (a=0.05). The increase in resin disc thickness decreased cement hardness. The increase in the distance of the light-curing tip decreased hardness at the top region. Specimens showed the lowest hardness values at the bottom, and the highest at the center. Resin cement hardness was influenced by the thickness of the indirect restoration and by the distance between the light-curing unit tip and the resin cement surface.

This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC) activated solely by chemical reaction (control group) or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram) or composite (Artglass) disc. Light curing was carried out using conventional halogen light (XL2500) for 40 s (QTH); light emitting diodes (Ultrablue Is) for 40 s (LED); and Xenon plasma arc (Apollo 95E) for 3 s (PAC). Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height) was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C), the samples (n = 5) were sectioned for hardness (KHN) measurements, taken in a microhardness tester (50 gF load 15 s). The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05). The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

Este estudo avaliou a dureza Knoop do cimento resinoso Enforce ativado pelos modos químico/físico ou somente físico, fotoativados diretamente e através de cerâmica (HeraCeram) ou compósito (Artglass). A fotoativação foi realizada com luz halógena convencional (QTH; XL2500) por 40 s, e com arco de plasma de xenônio (PAC; Apollo 95E) por 3 s. Incisivos bovinos tiveram suas faces vestibulares planificadas e hibridizadas. Sobre esta superfície foi assentada matriz, a qual foi preenchida com cimento. Um disco de material para faceta foi assentado sobre este conjunto para fotoativação. Após armazenagem (24 h/37ºC), as amostras (n=10) foram seccionadas para leitura de dureza (KHN), realizadas em aparelho micro-durômetro (50 gf / 15 s). Os dados foram submetidos à análise de variância e ao teste de Tukey (a = 0,05). Foi verificado que o cimento no modo dual apresentou maiores valores de dureza, comparado ao modo físico, exceto para fotoativação direta e através de Artglass com QTH. Valores mais altos de dureza foram observados com QTH comparado ao PAC, exceção aos grupos Artglass/dual, em que valores similares foram obtidos. Baixos valores de dureza Knoop foram obtidos com PAC com ambos o materiais Artglass e HeraCeram. Os valores de dureza dos cimentos resinosos podem ser influenciados pelo material restaurador indireto e também pelo tipo de aparelho fotoativador utilizado.

This study evaluated the Knoop hardness of Enforce resin cement activated by the either chemical/physical or physical mode, and light cured directly and through ceramic (HeraCeram) or composite resin (Artglass). Light curing were performed with either conventional halogen light (QTH; XL2500) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. Bovine incisors had their buccal surfaces flattened and hybridized. On these surfaces a mold was seated and filled with cement. A 1.5-mm-thick disc of the veneering material was seated over this set for light curing. After storage (24 h/37ºC), specimens (n=10) were sectioned for hardness (KHN) measurements in a micro-hardness tester (50 gf load/ 15 s). Data were submitted to ANOVA and Tukey's test (alpha=0.05). It was observed that the dual cure mode yielded higher hardness compared to the physical mode alone, except for direct light curing with the QTH unit and through Artglass. Higher hardness was observed with QTH compared to PAC, except for Artglass/dual groups, in which similar hardness means were obtained. Low KHN means were obtained with PAC for both Artglass and HeraCeram. It may be concluded that the hardness of resin cements may be influenced by the presence of an indirect restorative material and the type of light-curing unit.

Este estudo avaliou, por meio do teste de dureza Knoop, a profundidade de polimerização do cimento resinoso dual (Rely-X) ativado quimicamente (grupo controle) ou química/fisicamente (dual), fotoativado através de uma faceta de cerâmica com 1,5mm de espessura (HeraCeram). Incisivos bovinos tiveram sua face vestibular planificada e hibridizada. Sobre esta superfície, uma matriz de borracha (5mm de diâmetro e 1mm de altura) foi preenchida com cimento. Uma tira de poliéster ou um disco de material de faceta foi assentado sobre essa matriz. No grupo dual, a fotoativação foi realizada com aparelho de lâmpada halógena convencional (XL2500), por 40s (QTH); luz emitida por diodos (Ultrablue Is), por 40s (LED); ou por luz emitida por arco de plasma de Xenônio (Apollo 95E), por 3s (PAC). No grupo controle, a presa do cimento ocorreu somente por ativação química. Após armazenamento em ambiente seco e escuro (24h/37ºC), as amostras (n=5) foram seccionadas para mensuração dos valores de dureza (KHN) em três diferentes profundidades, obtidos em um aparelho microdurômetro (50gf/15s). Os dados foram submetidos à análise de variância e ao teste de Tukey (a=0,05). O cimento Rely-X apresentou maiores valores de dureza Knoop após fotoativação com QTH e LED, comparados ao grupo controle e PAC. A fotoativação com PAC resultou em valores de dureza inferiores ao grupo controle. A dureza do cimento foi menor em regiões mais profundas.

This study evaluated, using Knoop hardness test, the polymerization depth of Rely-X dual-cured resin cement activated by chemical reaction alone (control group) or by chemical/physical mode with light curing through a 1.5-mm-thick ceramic layer (HeraCeram). Bovine incisors had their buccal surface flattened and hybridized. On this surface, a rubber mould (5 mm diameter; 1 mm high) was bulk filled with cement. Either a polyester strip or a 1.5-mm-thick disc of the veneering material was seated over this set. Light curing was performed with either conventional halogen light (QTH; XL2500) for 40 s, light-emitting diode (LED; Ultrablue Is) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. In a control group, cement setting occurred by chemical reaction alone. After storage dry in dark (24 h/37ºC), the specimens (n=5) were sectioned for hardness (KHN) measurements at three depths in a microhardness tester (50 gf load/15 s). Data were submitted to ANOVA and Tukey's test (a = 0.05). Rely-X cement presented higher Knoop hardness values when the QTH and LED LCUs were used, compared to the control group and PAC. Light curing with PAC resulted in lower hardness compared to the control group. Cement hardness was significantly lower in deeper regions.

A comparison was made of the hardness of Z250 and Esthet-X composites light cured with different light sources. Cavities (3 mm diameter x 6 mm deep) were prepared in 240 bovine incisors. The composite was bulk inserted and light-cured using halogen light, LED or xenon plasma arc (PAC) with different irradiances and exposure times, maintaining the same energy density. The specimens were stored in an incubator at 37 °C for 24 hours prior to sectioning for hardness measurements. Three measurements were taken at each depth: surface, 1, 2, 3, 4 and 5 mm. The data were analyzed by ANOVA and Tukey's test (p < 0.05). No statistically significant differences were found for LED up to 2 mm, for PAC up to 3 mm, and for halogen light up to 5 mm. Photoactivation with intermediate power density and exposure time resulted in the highest Knoop hardness values.

Este estudo teve como objetivo avaliar o efeito do aumento da densidade de energia na dureza Knoop das resinas compostas Z250 e Esthet-X. Cavidades cilíndricas (3 mm de diâmetro X 3mm de profundidade) foram preparadas na superfície vestibular de 144 incisivos bovinos. As resinas compostas foram inseridas em incremento único e fotopolimerizadas com diferentes unidades e tempos de fotopolimerização: luz halógena convencional (700 mW/cm²; 20 s, 30 s and 40 s); LED (diodo emissor de luz; 440 mW/cm²; 20 s, 30 s and 40 s); PAC (arco de plasma de xenônio; 1700 mW/cm²; 3 s, 4,5 s and 6 s). Os espécimens foram armazenados a 37°C durante 24 h, previamente à realização das leituras de dureza Knoop. Foram realizadas três leituras por profundidade: superfície, 1 mm e 2 mm. Os dados foram submetidos à ANOVA e ao teste de Tukey (p<0,05). Independente da unidade de fotopolimerização ou da densidade de energia, a dureza do compósito Z250 foi estatisticamente superior do que o compósito Esthet-X (p<0.05). A dureza dos compósitos fotoativados por PAC foi estatisticamente inferior em relação aos compósitos fotoativados por luz halógena ou LED (p<0.05) que, por sua vez, não diferiram entre si, independentemente da profundidade. O aumento do tempo de exposição produziu compósitos com maiores valores de dureza Knoop quando se utilizou LED ou PAC (p<0.05). Para luz halógena o aumento do tempo de exposição não influenciou os valores de dureza (p>0.05). Os valores de dureza Knoop diminuíram com o aumento da profundidade. O aumento da densidade de energia produziu compósitos com maior dureza Knoop quando o LED e o PAC foram utilizados como fontes de polimerização.

The aim of this study was to evaluate the effect of the increase of energy density on Knoop hardness of Z250 and Esthet-X composite resins. Cylindrical cavities (3 mm in diameter X 3 mm in depth) were prepared on the buccal surface of 144 bovine incisors. The composite resins were bulk-inserted and polymerized using different light-curing units and times: conventional QTH (quartz-tungsten-halogen; 700 mW/cm²; 20 s, 30 s and 40 s); LED (light-emitting diode; 440 mW/cm²; 20 s, 30 s and 40 s); PAC (xenon plasma arc; 1700 mW/cm²; 3 s, 4.5 s and 6 s). The specimens were stored at 37°C for 24 h prior to sectioning for Knoop hardness assessment. Three measurements were obtained for each depth: top surface, 1 mm and 2 mm. Data were analyzed statistically by ANOVA and Tukey's test (p<0.05). Regardless of the light source or energy density, Knoop hardness of Z250 was statistically significant higher than that of Esthet-X (p<0.05). Specimens cured with PAC had lower hardness than those cured with QTH and LED (p<0.05). Higher Knoop hardness was obtained when the energy density was increased for LED and PAC (p<0.05). No statistically significant differences (p>0.05) were found for QTH. Knoop hardness values decreased with the increase of depth. The increase of energy density produced composites with higher Knoop hardness means using LED and PAC.