Can whitening toothpastes maintain the optical stability of enamel over time?

Abstract Besides the effects on the health of individuals, cigarette smoking can also interfere with the appearance of their teeth. Objective: To evaluate the effect of cigarette smoking-toothbrushing-cycling (CSTC) with whitening toothpastes on the roughness and optical behavior of bovine enamel for eight weeks. Material and Methods: Thirty bovine dentin/enamel discs, 8.0 mm in diameter and 2.0 mm thick, were randomly divided into three groups according to the toothpastes: whitening (Colgate Luminous White - CW and Oral B 3D White - OW), and a non-whitening (Colgate - C). The roughness, color (CIE L*a*b* system), translucency and gloss were measured before and after the specimens were submitted to CSTC. The topography of the specimens was analyzed by scanning electron microscopy. During the first week, the specimens were daily subjected to the consumption of 20 cigarettes and brushed (40 strokes/100 g) with the toothpastes' slurries. Thereafter, the CSTC was weekly applied in an accumulated model (140 cigarettes/280 strokes) for seven weeks. The data were submitted to two-way ANOVA, Tukey's HSD test, and paired-t test (α=0.05). Results: The three toothpastes produced significant changes in roughness, color, translucency and gloss (p<0.05). After eight weeks, the roughness and the gloss produced by the three toothpastes were similar (p>0.05), while OW produced the lowest color change and the translucency of C was lower than that of CW (p<0.05). The three toothpastes produced a significant decrease in L* values and a significant increase in a* values after eight weeks (p<0.05). No significant difference in the b* coordinate was found for OW (p=0.13) There were topographic changes in the enamel surfaces. Conclusions: The whitening toothpastes increased the roughness, changed the topography and were not able to maintain the optical stability of enamel exposed over eight weeks.

Characterization of Conventional and High-Translucency Y-TZP Dental Ceramics Submitted to Air Abrasion

Abstract This study evaluated the effect of air-abrasion on t®m phase transformation, roughness, topography and the elemental composition of three Y-TZP (Yttria-stabilized tetragonal zirconia polycrystal) dental ceramics: two conventional (Lava Frame and IPS ZirCad) and one with high-translucency (Lava Plus). Plates obtained from sintered blocks of each ceramic were divided into four groups: AS (as-sintered); 30 (air-abrasion with 30 mm Si-coated Al2O3 particles); 50 (air-abrasion with 50 mm Al2O3 particles) and 150 (air-abrasion with 150 mm Al2O3 particles). After the treatments, the plates were submitted to X-ray diffractometry; 3-D profilometry and SEM/EDS. The AS surfaces were composed of Zr and t phases. All treatments produced t®m phase transformation in the ceramics. The diameter of air-abrasion particles influenced the roughness (150>50>30>AS) and the topography. SEM analysis showed that the three treatments produced groove-shaped microretentions on the ceramic surfaces, which increased with the diameter of air-abrasion particles. EDS showed a decrease in Zr content along with the emergence of O and Al elements after air-abrasion. Presence of Si was also detected on the plates air-abraded with 30 mm Si-coated Al2O3 particles. It was concluded that irrespective of the type and diameter of the particles, air-abrasion produced t®m phase transformation, increased the roughness and changed the elemental composition of the three Y-TZP dental ceramics. Lava Plus also behaved similarly to the conventional Y-TZP ceramics, indicating that this high translucency ceramic could be more suitable to build monolithic ceramic restorations in the aesthetic restorative dentistry field.

Resumo Este estudo avaliou o efeito da abrasão a ar na transformação de fase t®m, na rugosidade, topografia e composição elementar de três cerâmicas Y-TZP (Zircônia tetragonal policristalina estabilizada por ítrio): duas convencionais (Lava Frame e ZirCad) e uma de alta translucidez (Lava Plus). Placas obtidas de blocos sinterizados de cada cerâmica foram divididos em quatro grupos: AS (pré-sinterizado); 30 (jateamento com partículas de Al2O3 de 30 mm cobertas com Si); 50 (jateamento com partículas de Al2O3 de 50 mm) e 150 (jateamento com partículas de Al2O3 de 150 mm). Após os tratamentos, as placas foram submetidas à difratometria de Rx, perfilometria 3-D e microscopia eletrônica de varredura com espectroscopia de energia dispersiva de Rx (SEM/EDS). As superfícies pré-sinterizadas apresentaram predominantemente Zr e fase tetragonal. Todos os tratamentos superficiais produziram transformação t®m nas cerâmicas avaliadas. A topografia e a rugosidade foram influenciadas pelo diâmetro das partículas abrasivas (150>50>30>AS). A análise através de SEM mostrou que os três tratamentos produziram fendas retentivas nas superfícies das cerâmicas, por influência do tamanho das partículas. A análise através de EDS mostrou uma diminuição da concentração de Zr, paralela ao surgimento de O e Al, após o jateamento. No grupo tratado com partículas de Al2O3 de 30 mm cobertas com Si foi também observado um aumento de Si após o jateamento. Concluiu-se que, independente do tipo e do diâmetro das partículas, o jateamento produziu transformação t®m, aumentou a rugosidade e alterou a composição elementar das cerâmicas avaliadas. A Lava Plus apresentou comportamento semelhante às cerâmicas convencionais, indicando que esta cerâmica de alta translucidez pode ser mais adequada à confecção de restaurações monolíticas no campo da odontologia estética restauradora.

Effects of different surface treatments on bond strength of an indirect composite to bovine dentin.

Background: Several surface treatments could be used to improve the bond strength (BS) between indirect composites and cement. Aim: To evaluate the BS of an indirect composite submitted to different surface treatments, cemented to bovine dentin. Settings and Design: One hundred and fifty conical cavities were prepared in slices of bovine dentin and bulk filled with the composite. Materials and Methods: After curing and removal from the cavity, the restorations were treated according to the groups (n = 10): C‑untreated, S‑Sandblasting; SS‑Sandblasting + silane; F‑hydrofluoric acid; FS‑hydrofluoric acid + silane; SF‑Sandblasting + hydrofluoric acid; SFS‑Sandblasting + hydrofluoric acid + silane; E‑ethanol; ES‑ethanol + silane; SE‑Sandblasting + ethanol; SES‑Sandblasting + ethanol + silane; P‑H2O2; PS‑H2O2 + silane; SP‑Sandblasting + H2O2; SPS‑Sandblasting + H2O2 + silane. After cementation, push‑out test was performed in a universal testing machine. Statistical Analysis: Data were submitted to nonparametric tests (Kruskal–Wallis and Mann–Whitney U‑tests, α = 0.05). The failure mode was observed under a stereomicroscope and the topography by scanning electronic microscopy (SEM). Results: Sandblasted groups led to the highest BS values, (P < 0.001), except for the SFS group. SE, SES, and SPS led to higher BS values than S and SS groups (P < 0.05). F, E and P groups showed the lowest BS values. The number of cohesive or mixed failures was related to higher BS values. SEM evaluation showed major irregularities only for sandblasted groups. Conclusions: Sandblasting was a safe surface treatment for the indirect composite, increasing the BS values. Hydrofluoric acid applied after sandblasting damaged the BS values and should not be recommended while ethanol and H2O2, when applied after sandblasting, were effective in increasing BS values.

Degradation of Resin Composites in a Simulated Deep Cavity

The aim of this study was to analyze the sorption and solubility of a nanofilled (Filtek Z350) and a midifilled (Filtek P60) resin composite in oral environment-like substances, in a simulated deep cavity. A cylindrical cavity prepared in a bovine incisor root was incrementally filled with resin composites. The obtained resin composite cylinders were cut perpendicularly to the axis to obtain 1-mm-thick discs that were divided into fifteen groups (n=5) according to depth (1, 2, 3, 4 and 5 mm) and immersion media (distilled water - DW, artificial saliva - AS and lactic acid - LA). The sorption and solubility were calculated based on ISO 4049:2000. Additionally, the degree of conversion (DC%) was calculated by FT-IR spectroscopy. Data were analyzed using multifactor analysis of variance (MANOVA) followed by Tukey's HSD post-hoc test and linear regression analysis (a=0.05). The DC% was higher for the midifilled resin composite and was negatively influenced by cavity depth (p<0.05). The nanofilled resin composite presented higher sorption and solubility than did the midifilled (p<0.05). The immersion media influenced the sorption and the solubility as follows: LA>AS>DW, (p<0.05). Both phenomena were influenced by cavity depth, with the sorption and solubility increasing from 1 to 5 mm (p<0.05). The degradation of resin composite restorations may be greater in the deepest regions of class II restorations when the composite is exposed to organic acids present in the oral biofilm (lactic acid).

O objetivo deste estudo foi analisar a absorção e a solubilidade de uma resina composta nanopartículada (Filtek Z350) e de uma híbrida (Filtek P60) em substâncias simuladoras do ambiente oral em um modelo de cavidade profunda. Uma cavidade cilíndrica, construída em uma raiz de um incisivo bovino, foi preenchida incrementalmente com as resinas compostas. Os cilindros obtidos foram seccionados perpendicularmente ao eixo para obtenção de discos com 1 mm de espessura, que foram divididos em 15 grupos (n=5) de acordo com a profundidade (1, 2, 3, 4 e 5 mm) e o meio de imersão (água destilada - AD, saliva artificial - SA e ácido lático - AL). A absorção e a solubilidade foram calculadas com base na norma ISO 4049:2000(E). Adicionalmente, o grau de conversão (GC%) foi calculado através de espectroscopia FT-IR. Os dados obtidos foram analisados usando análise de variância multifatorial, teste de Tukey HSD e análise de regressão linear (a=0,05). A resina composta híbrida apresentou o maior grau de conversão, sendo este influenciado pela profundidade da cavidade (p<0,05). A resina composta nanopartículada apresentou maiores valores de absorção e solubilidade (p<0,05). O meio de imersão influenciou a absorção e a solubilidade: AL>SA>AD (p<0,05). Ambos os fenômenos foram influenciados pela profundidade da cavidade, com os valores aumentando de 1 para 5 mm (p<0,05). A degradação de restaurações de resinas compostas pode ser maior em regiões profundas de restaurações classe II e quando o material é exposto à ácidos orgânicos produzidos pelo biofilme oral (ácido lático).

Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R), Variolink II (V), Enforce (E) and All Cem (A), after immersion in distilled water (DW), lactic acid (LA) and artificial saliva (AS) and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch) and dual (D). In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System) was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 ) were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA) and Tukey's HSD test for media comparisons (α=0.05). Results Sorption was higher after immersion in LA (p<0.05) and increased significantly with time (p<0.05). Sorption was influenced by the activation mode: Ch>D (p<0.05). The lowest solubility was presented by R (p<0.05). Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements. .

A critical analysis of the degree of conversion of resin-based luting cements

OBJECTIVE: This study analyzed the degree of conversion (DC percent) of four resin-based cements (All Ceram, Enforce, Rely X ARC and Variolink II) activated by two modes (chemical and dual), and evaluated the decrease of DC percent in the dual mode promoted by the interposition of a 2.0-mm-thick IPS Empress 2 disc. MATERIAL AND METHODS: In the chemical activation, the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. In the dual activation, after mixing, the cements were light-activated at 650 mW/cm² for 40 s. In a third group, the cements were light-activated through a 2.0-mm-thick IPS Empress 2 disc. The DC percent was evaluated in a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The data were analyzed by two-way ANOVA and Tukey's HSD test. RESULTS: For all resin-based cements, the DC percent was significantly higher with dual activation, followed by dual activation through IPS Empress 2, and chemical activation (p<0.05). Irrespective of the activation mode, Rely X presented the highest DC percent (p<0.05). Chemically activated Variolink and All Ceram showed the worst results (p<0.05). The DC percent decreased significantly when activation was performed through a 2.0-mm-thick IPS Empress 2 disc (p<0.05). CONCLUSION: The results of the present study suggest that resin-based cements could present low DC percent when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of IPS-Empress 2.

Influence of post-cure treatments on hardness and marginal adaptation of composite resin inlay restorations: an in vitro study

OBJECTIVES: The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments. MATERIAL AND METHODS: For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130ºC); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5 percent was adopted for all analyses. RESULTS: The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 µm for any of the experimental conditions. CONCLUSION: The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values.

Eficácia do ultrassom na remoção de retentores intra-radiculares metálicos fundidos / Efficacy of ultrasound in cast post and core removal

Este estudo comparou a eficácia de três aparelhos de ultrassom na remoção de retentores intra-radiculares metálicos fundidos. Utilizou-se 45 incisivos centrais superiores humanos, que receberam tratamento endodôntico e retentores (liga de Ni-Cr) fixados com cimento de fosfato de zinco. A amostra foi dividida em três grupos (n = 15), de acordo com o aparelhode ultrassom empregado (G1 = Enac OE3; G2 =JET Sonic Total; G3 = Profi III Bios) e mensurou-se o tempo de remoção (s). O teste de Tukey (5%) revelou que G3 (797s) > G1 (67,73s) = G2 (151,60s). Em G3, apenas três retentores foram removidos. Concluiu-se que G1 e G2 obtiveram igual sucesso na remoção dos retentores.

Cytotoxicity of current adhesive systems: in vitro testing on cell culture of L929 and balb/c 3T3 fibroblasts / Citotoxicidade de sistemas adesivos atuais: teste in vitro em cultura de células fibroblásticas L929 e balb/c 3T3

Purpose: The aim of this study was to evaluate the cytotoxicity of three current adhesives: Prime&Bond NT (PBNT), Single Bond (SB) and XENO III (XENO). Methods: After embedding and curing circles of filter paper with the tested adhesives, the filters were placed in contact with the solidified agar surface over L929 monolayer cells plated in 6-well cell culture plate and incubated for 24 h. The inhibition zone around the filter papers was measured in mm. MTT assay was performed using fibroblasts Balb/c 3T3 cell lines in multiwell culture plates. All assays were done in triplicate. Results: All materials were cytotoxic (Kruskal-Wallis, P<0.05) in a similar level to latex (P>0.05). For intra-groups analysis, SB presented the lowest cytotoxicity (P<0.01), while there was no statistical difference between PBNT and XENO (P>0.05). MTT assay confirmed the cytotoxicity of the tested adhesives. Conclusion: Considering the limits of this work, all adhesives tested were as cytotoxic as latex.

Objetivo: O objetivo deste estudo foi avaliar a citotoxicidade de três adesivos: Prime & Bond NT (PBNT), Single Bond (SB) e XENO III (XENO). Metodologia: Após embebição e polimerização de filtros de papel com os referidos adesivos, estes foram colocados em contato com a superfície de agar solidificada sobre a monocamada de células L929 plaqueadas em cultura celular de 6-poços e incubadas por 24 h. A zona de inibição formada ao redor dos filtros de papel foi medida em milímetros. Outro teste realizado foi o do MTT, utilizando fibroblastos Balb / c 3T3 em placas de multi-poços, sendo os ensaios realizados em triplicatas. Resultados: Todos os materiais testados foram citotóxicos (Kruskal-Wallis, P < 0,05) e semelhantes ao látex (P > 0,05). Para a análise intra-grupos, o SB apresentou a mais baixa citotoxicidade (P < 0,01), enquanto não houve diferença estatística entre PBNT e XENO (P > 0,05). O ensaio de MTT confirmou a citotoxicidade dos adesivos. Conclusão: Considerando as limitações deste trabalho, todos os adesivos testados foram tão citotóxicos quanto o látex.

Relationship between the degree of conversion, solubility and salivary sorption of a hybrid and a nanofilled resin composite

This study analyzed the relationship between the degree of conversion (DC), solubility, and salivary sorption of a hybrid (Filtek P 60) and a nanofilled resin composite (Filtek Supreme), and evaluated the influence of the light-activation mode on these properties. Two light-activation modes were used: Conventional (C; 850 mW/cm² for 20 s) and Soft-start (SS; 100-1,000 mW/cm² for 10 s + 1,000 mW/cm² for 10 s). The DC ( percent) was evaluated by FT-Raman spectroscopy. The solubility and salivary sorption were measured after immersion in artificial saliva for 7 days. Data were analyzed by ANOVA and Student-Newman-Keuls' test and linear regression analysis (a = 0.05). The DC varied from 50.52 percent (nanofilled composite) to 57.15 percent (hybrid composite), and was influenced by the light-activation mode: C > SS. The solubility (0.45 mg/mm³) and salivary sorption (8.04 mg/mm³) of the nanofilled composite were greater than those of the hybrid composite (0.40 mg/mm³ / 6.87 mg/mm³), and were influenced by the light-activation mode: SS > C. Correlation was found between DC and solubility (r = - 0.89, p<0.05), as well as between solubility and salivary sorption (r = 0.95). These findings suggest that nanofilled composites may present higher degradation in the oral environment than hybrid ones. Soft-start light-activation mode may increase the solubility of resin composites.

Relationship between the degree of conversion, solubility and salivary sorption of a hybrid and a nanofilled resin composite: influence of the light-activation mode

This study analyzed the relationship between the degree of conversion (DC), solubility, and salivary sorption of a hybrid (Filtek P 60) and a nanofilled resin composite (Filtek Supreme), and evaluated the influence of the light-activation mode on these properties. Two light-activation modes were used: Conventional (C; 850 mW/cm2 for 20 s) and Soft-start (SS; 100-1,000 mW/cm2 for 10 s + 1,000 mW/cm2 for 10 s). The DC (%) was evaluated by FT-Raman spectroscopy. The solubility and salivary sorption were measured after immersion in artificial saliva for 7 days. Data were analyzed by ANOVA and Student-Newman- Keuls’ test and linear regression analysis (= 0.05). The DC varied from 50.52% (nanofilled composite) to 57.15% (hybrid composite), and was influenced by the light-activation mode: C > SS. The solubility (0.45 µg/mm3) and salivary sorption (8.04 µg/mm3) of the nanofilled composite were greater than those of the hybrid composite (0.40 µg/mm3 / 6.87 µg/mm3), and were influenced by the light-activation mode: SS > C. Correlation was found between DC and solubility (r = - 0.89, p<0.05), as well as between solubility and salivary sorption (r = 0.95). These findings suggest that nanofilled composites may present higher degradation in the oral environment than hybrid ones. Soft-start light-activation mode may increase the solubility of resin composites.

Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm) were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days), the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05). RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

Influência do protocolo de fotoativação no selamento de restaurações com compósitos / Influence of light-curing mode on the sealing of resin composite restorations

O propósito deste estudo foi avaliar a influência do protocolo de fotoativação no selamento de restaurações classe V com compósitos. Sessenta cavidades com margem oclusal em esmalte e margem apical em dentina, preparadas nas superfícies vestibular e lingual de pré molares humanos, foram hibridizadas com o sistema adesivo Single Bond e restauradas com três compósitos (A110, P60 e Point 4). Para cada compósito, foram produzidos dois grupos de acordo com os protocolos de fotoativação (n = 10): Convencional-500 mW/cm2/40 segundos e Softstart-250 mW/cm2/40 segundos + 500 mW/cm2/20 segundos. Após acabamento/polimento das restaurações e armazenagem durante 7 dias em água destilada a 37°C, os dentes foram submetidos à termociclagem. Os espécimes foram impermeabilizados com esmalte de unha e imersos em solução neutra de azul de metileno a 2 % por 24 horas. Os dentes foram seccionados e o grau de penetração do corante foi avaliado em uma escala ordinal de 0-3. Os dados foram submetidos aos testes de Kruskal-Wallis e Mann-Whitney (α = 0,05). Não houve diferença estatística entre os grupos ativados com os dois protocolos de fotoativação. A microinfiltração foi maior nas margens em dentina do que nas margens em esmalte (p < 0,01). Esses achados sugerem que o protocolo de fotoativação soft-start não apresentou influência no selamento de cavidades restauradas com compósitos fotopolimerizáveis

This study investigated the effect of light-curing modes on cervical sealing of resin composite restorations. Sixty cavities with the occlusal margins in enamel and the gingival margins in dentin, prepared on the labial and lingual surfaces of human premolars were treated with Single Bond adhesive system and restored using a bulk technique with three resin composites (A110, P60 and Point 4). For each composite, two groups of 10 cavities were created according to the two light-curing modes: Standard (S)-500 mW/cm2 / 40 seconds and Soft-start (SS) - 250 mW/cm2 / 40 seconds + 500 mW/cm2 / 20 seconds. The specimens were submitted to thermocycling prior to immersion in 2% neutral solution of methylene blue for 24 hours. The teeth were sectioned and the degree of dye penetration was scored on a 0-3 ordinal scale. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). No significant difference in the microleakage scores was observed among the groups polymerized with the two light-curing modes. The microleakage was greater in dentin margins than in enamel margins (p < 0.01). These results suggest that soft-start light-curing mode did not have any influence on resin composite restoration sealing

Depth of cure of dental composites submitted to different light-curing modes

OBJECTIVE: This study evaluated the depth of cure of five dental composites submitted to different light-curing modes. MATERIAL AND METHODS: Canal-shaped cavities with 5mm of length were prepared on the buccal surfaces of extracted third molars, and restored using P-60, A-110, Admira, Z-250 and Supreme resin composites. Materials were light-cured from the top, according to three modes (Group 1- Conventional (C): 500 mW/cm² / 40 s; Group 2 - Soft-Start (SS): 250 mW/cm²/ 20 s + 500 mW/cm²/ 20 s + 500 mW/cm²/ 10 s and Group 3 - LED: 250 mW/cm²/ 40 s). After that, cavity longitudinal surfaces were polished and marked with a millimeter scale of 4mm of length. Depth of cure was evaluated by means of Knoop hardness number (KHN), so that five indentations were performed at each millimeter. Original data were submitted to three-way ANOVA and Fisher's LSD test (alpha = 0.01). RESULTS: All materials presented a significant reduction on KHN from first to third millimeter. Regarding depth of cure, the results obtained for Conventional and Soft-Start modes were similar, but statistically superiors to those found for group 3 (LED). CONCLUSION: This performance may be related to the differences among energy densities obtained with different light-curing modes.

OBJETVO: Este estudo avaliou a profundidade de polimerização de cinco compósitos fotopolimerizáveis submetidos a diferentes métodos de fotoativação. MATERIAL E MÉTODO: Cavidades em forma de canaleta com 5 mm de comprimento, preparadas nas faces vestibulares de terceiros molares, foram restauradas com os compósitos P-60, A-110, Admira, Z-250 e Supreme. Os materiais foram fotoativados pelo topo das cavidades com três técnicas (Grupo 1 - Convencional (C): 500 mW / cm² / 40 s; Grupo 2 - Soft-Start (SS): 250 mW / cm² / 20 s + 500 mW / cm² / 20 s + 500 mW / cm² / 10 s e Grupo 3 - LED: 250 mW / cm² / 40 s). Após a fotoativação, as superfícies longitudinais dos materiais foram polidas e marcadas com uma escala milimetrada com 4 mm de comprimento. A profundidade de polimerização foi avaliada através do número de dureza Knoop (NDK), com cinco indentações a cada milímetro. Os dados originais foram submetidos à Análise de Variância de três fatores e teste de Fisher para comparações entre médias (alfa = 0,01). RESULTADOS: Todos os materiais apresentaram diminuição do NDK do primeiro para o terceiro milímetro (p < 0,01). Os resultados obtidos com os Grupos Convencional e Soft-Start foram similares e superiores ao Grupo LED (p < 0,01). CONCLUSÃO: Este desempenho pode ser relacionado às diferenças nas densidades de energia obtidas com os métodos de fotoativação utilizados.

Depth of cure of dental composites submitted to different light-curing modes%Profundidade de polimerização de compósitos restauradores submetidos a diferentes métodos de fotoativação

OBJETVO: Este estudo avaliou a profundidade de polimerização de cinco compósitos fotopolimerizáveis submetidos a diferentes métodos de fotoativação. MATERIAL E MÉTODO: Cavidades em forma de canaleta com 5 mm de comprimento, preparadas nas faces vestibulares de terceiros molares, foram restauradas com os compósitos P-60, A-110, Admira, Z-250 e Supreme. Os materiais foram fotoativados pelo topo das cavidades com três técnicas (Grupo 1 - Convencional (C): 500 mW / cm2 / 40 s; Grupo 2 - Soft-Start (SS): 250 mW / cm2 / 20 s + 500 mW / cm2 / 20 s + 500 mW / cm2 / 10 s e Grupo 3 - LED: 250 mW / cm2 / 40 s). Após a fotoativação, as superfícies longitudinais dos materiais foram polidas e marcadas com uma escala milimetrada com 4 mm de comprimento. A profundidade de polimerização foi avaliada através do número de dureza Knoop (NDK), com cinco indentações a cada milímetro. Os dados originais foram submetidos à Análise de Variância de três fatores e teste de Fisher para comparações entre médias (a = 0,01). RESULTADOS: Todos os materiais apresentaram diminuição do NDK do primeiro para o terceiro milímetro (p < 0,01). Os resultados obtidos com os Grupos Convencional e Soft-Start foram similares e superiores ao Grupo LED (p < 0,01). CONCLUSÃO: Este desempenho pode ser relacionado às diferenças nas densidades de energia obtidas com os métodos de fotoativação utilizados

Restaurações em dentes tratados endodonticamente / Endodontically treated teeth restorations

O objetivo deste trabalho é apresentado de maneira didática, os principais conceitos envolvidos em restaurações de dentes tratados endodonticamente, retentores intra-radiculares diretos e indiretos. Novos aspectos técnico-científicos e materiais foram apresentados e discutidos, priorizando a observação e o suporte de fundamentos biomecânicos, onde características como a rigidez e o comprimento do pino podem representar destacada influência na integridade da estrutura dental remanescente

Influência do protocolo de aplicação no mecanismo de adesão de um sistema adesivo gel / Influence of application protocol in adhesion mechanism of gel adhesive system

Este estudo avaliou a influência do protocolo de aplicação no mecanismo de adesão do adesivo One Coat Bond. Foram avaliadas a resistência adesiva e as características ultra-estruturais da camada híbrida produzidas em dentina bovina. Três grupos experimentais foram produzidos: Grupo I (controle) - esfregamento por 20s; Grupo II - esfregamento por 10s e Grupo III - esfregamento por 30s. Não foi observada diferença estatística significante entre os grupos (p>0.05). Todos os espécimes apresentaram camada híbrida entre 3-3,5 µm de espessura. Concluiu-se que o mecanismo de adesão do adesivo One Coat Bond não foi afetado pelos protocolos alternativos avaliados

Análise térmica da câmara pulpar em dentes humanos submetidos ao clareamento com laser de diodo: estudo in vitro / Thermal analysis in pulp chamber during diode laser bleaching: an in vitro study

Este trabalho objetivou avaliar in vitro o aumento de temperatura gerado na câmara pulpar de incisivos inferiores permanentes humanos, em decorrência do clareamento a laser, utilizando dois métodos: termopar e câmera termográfica. No primeiro, um termopar tipo K, conectado a um sistema de medida de temperatura, foi introduzido através do ápice radicular de 72 espécimes até sua câmara pulpar. Dois agentes clareadores - Whiteness HP (HP) e Hi Lite (HL) - ambos peróxido de hidrogênio a 35 por cento, foram testados, tendo sido aplicados às faces vestibulares dos espécimes e irradiados por 30s, com um laser de diodo (808 5nm) em regime contínuo, nas intensidades de 21,3W/cm2, 28,7W/cm2, 34,4W/cm2, 37,9W/cm2, 50,9W/cm2 e 61,1W/cm2. O mesmo laser e clareadores foram empregados na análise de 36 espécimes com a câmera termográfica nas intensidades de 21,7W/cm2, 30,9W/cm2, 37,2W/cm2, 38,5W/cm2, 54,9W/cm2 e 66,2W/cm2. Os resultados mostraram que as médias das máximas elevações de temperatura na câmara pulpar quando utilizado o HP foram estatisticamente superiores às do HL, independente do método de medida [termopar (p < 0,01): HP = 5,2ºC X HL = 4,4ºC; câmera termográfica (p < 0,1): HP = 2,9ºC X HL = 2,1ºC]. Com o termopar, verificou-se que o aumento de temperatura (5,9ºC) gerado pela maior intensidade de irradiação (61,1W/cm²) destacou-se dos demais mostrando semelhança estatística apenas com a intensidade de 50,9W/cm² (5,4ºC). As interações desses dois mais altos parâmetros com o HP foram responsáveis por temperaturas superiores a 5,5ºC (6,4ºC com 50,9W/cm² e 7,0ºC com 61,1W/cm²), considerada como limite para evitar danos pulpares...