Effect of irrigation protocols on smear layer removal, bond strength and nanoleakage of fiber posts using a self-adhesive resin cement.

Objectives: This study aimed to investigate the effect of the application method of 2% chlorhexidine (CHX) and its influence on the adhesion of fiberglass posts cemented with a self-adhesive resin cement. Materials and Methods: Sixty human mandibular premolars were endodontically treated and divided into 5 groups (n = 12), according to the canal irrigant and its application method: 2 groups with conventional syringe irrigation (CSI)-2.5% sodium hypochlorite (NaOCl) (control) and 2% CHX- and 3 groups with 2% CHX irrigation/activation-by passive ultrasonic irrigation (PUI), Easy Clean file, and XP-Endo Finisher file. Two roots per group were evaluated for smear layer (SL) removal by scanning electron microscopy. For other roots, fiber posts were luted using a self-adhesive resin cement. The roots were sectioned into 6 slices for push-out bond strength (BS) (7/group) and nanoleakage (NL) (3/group). Data from SL removal were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS and NL were evaluated by 2-way analysis of variance and Tukey's test (α = 0.05). Results: For SL removal and BS, the CHX irrigation/activation promoted better values than CSI with CHX (p < 0.05), but it was not significantly different from CSI with NaOCl (p > 0.05). For NL, the lowest values were obtained by the chlorhexidine irrigation/activation groups (p < 0.05). Conclusions: Active 2% CHX irrigation can be used to improve the post space cleaning and adhesion before fiber post cementation with self-adhesive resin cements.

Effect of surface treatments on repair strength, roughness and morphology in aged metal-free crowns

Aim: The roughness and micromorphology of various surface treatments in aged metal-free crowns and the bond strength of these crowns repaired with composite resin (CR) was evaluated in vitro. Methods: A CR core build-up was confectioned in 60 premolars and prepared for metal-free crowns. Prepared teeth were molded with the addition of silicone, and the laboratory ceromer/fiber-reinforced crowns (SR Adoro/Fibrex Lab) were fabricated. Subsequently, the crowns were cemented and artificially aged in a mechanical fatigue device (1.2 X 106 cycles), then divided into 4 groups (n = 15) according to the surface treatment: 1) phosphoric acid etching (PA); 2) PA + silane application; 3) roughening with a diamond bur + PA; and 4) sandblasting with Al2O3 + PA. After the treatments, the crowns (n = 2) were qualitatively analyzed by scanning electron microscope (SEM) and surface roughness (n = 5) was analyzed before and after the surface treatment (Ra parameter). The remaining crowns (n = 8) received standard repair with an adhesive system (Tetric N-Bond) and a nanohybrid CR (Tetric N-Ceram), and the microshear bond strength (SBS) test was performed (0.5 mm/min). Roughness and SBS data were analyzed by one- and two-way ANOVA, respectively, as well as Tukey's post-test (α = 0.05). Results: Sandblasting with Al2O3 + PA resulted in the highest final roughness and SBS values. The lowest results were observed in the PA group, whereas the silane and diamond bur groups showed intermediate values. Conclusion: It may be concluded that indirect ceromer crowns sandblasted with aluminum oxide prior to PA etching promote increased roughness surface and bond strength values

Effect of Conditioning Protocols and Ultrasonic Application of an Infiltrant Resin in White Spot Lesions.

The aim of this study was to evaluate different conditioning protocols and sonic/ultrasonic application of an infiltrant resin (IR) in artificial white spot lesions (AWSL). the V/L surfaces of 48 molars were induced to an AWSL and divided in 6 groups, according to the conditioning protocols and application technique: 15% hydrochloric acid (HA) + manual application of the IR; HA + 37% phosphoric acid (PA) + manual application of the IR; HA + ultrasonic application (U) of the IR; HA + sonic application (S) of the IR; PA+HA+S; and PA+HA+U. For the Penetration Depth (PD), the crowns were etched with HA for 120s. The IR Icon® (DMG) was applied according to the manufacturer`s instructions. The crowns were dye penetrated (0.1% red fluorophore rhodamine B isothiocyanate for 12h) and bleached with 30% hydrogen peroxide for 12 h. The discs were immersed in a 50% ethanol solution, containing 100 µM of sodium fluorescein. The PD (in µm) was measured using confocal laser scanning microscopy (20x). The bond strength (BS) was performed by michoshear test (0.5 mm/min). Data were submitted to 2-way ANOVA and Tukey (α=0.05). For BS, the interaction was not significant (p>0.05). For PD, the main factors were significant (application - p<0.001; conditioning technique - p=0.003). The ultrasonic application showed the highest PD values. PA+HA presented higher results than HA. The sonic/ultrasonic applications and the use of phosphoric acid prior to hydrochloric acid improved PD of the infiltrant resin. Conditioning protocols or application techniques did not influence BS values.

Effect of conditioning protocols and ultrasonic application of an infiltrant resin in white spot lesions

Abstract The aim of this study was to evaluate different conditioning protocols and sonic/ultrasonic application of an infiltrant resin (IR) in artificial white spot lesions (AWSL). the V/L surfaces of 48 molars were induced to an AWSL and divided in 6 groups, according to the conditioning protocols and application technique: 15% hydrochloric acid (HA) + manual application of the IR; HA + 37% phosphoric acid (PA) + manual application of the IR; HA + ultrasonic application (U) of the IR; HA + sonic application (S) of the IR; PA+HA+S; and PA+HA+U. For the Penetration Depth (PD), the crowns were etched with HA for 120s. The IR Icon® (DMG) was applied according to the manufacturer`s instructions. The crowns were dye penetrated (0.1% red fluorophore rhodamine B isothiocyanate for 12h) and bleached with 30% hydrogen peroxide for 12 h. The discs were immersed in a 50% ethanol solution, containing 100 µM of sodium fluorescein. The PD (in µm) was measured using confocal laser scanning microscopy (20x). The bond strength (BS) was performed by michoshear test (0.5 mm/min). Data were submitted to 2-way ANOVA and Tukey (α=0.05). For BS, the interaction was not significant (p>0.05). For PD, the main factors were significant (application - p<0.001; conditioning technique - p=0.003). The ultrasonic application showed the highest PD values. PA+HA presented higher results than HA. The sonic/ultrasonic applications and the use of phosphoric acid prior to hydrochloric acid improved PD of the infiltrant resin. Conditioning protocols or application techniques did not influence BS values.

Resumo: O objetivo deste estudo foi avaliar diferentes protocolos de condicionamento e a aplicação sônica/ultrassônica de uma resina infiltrante (RI) em lesões de mancha branca produzidas artificialmente (LMBA). As superfícies vestibulares/linguais de 48 molares foram induzidas à formação de LMBA e divididas em 6 grupos, de acordo com os protocolos de condicionamento e técnica de aplicação da resina infiltrante: ácido hidroclorídrico 15% (AH) + aplicação manual da RI; AH + ácido fosfórico 37% (AF) + aplicação manual da RI; AH + aplicação ultrassônica da RI (U); AH + aplicação sônica da RI (S); AF + AH + S; e AF + AH + U. para o grau de penetração (GP), condicionou-se as coroas com AH por 120 s. A RI Icon® (DMG) foi aplicada de acordo com as instruções do fabricante. As coroas foram coradas (rodamina B 0,1% por 12 h) e clareadas com peróxido de hidrogênio 30% por 12 h. os discos foram imersos em solução de etanol 50%, contendo 100 µM de fluoresceína sódica. O GP (em µm) foi mensurado por meio de microscopia confocal a laser (20´). A resistência de união (RU) foi calculada pelo teste de microcisalhamento (0,5 mm/min). Os dados foram submetidos ao teste ANOVA 2 fatores e Tukey (α=0,05). Para RU, a interação não foi significante (p>0,05). Para GP, os fatores principais foram significantes (técnica de aplicação - p<0,001; protocolos de condicionamento - p=0,003). A aplicação U mostrou os maiores valores de GP. AF+AH demonstrou resultados superiores ao grupo AH. As aplicações sônica/ultrassônica e o uso do ácido fosfórico antes do ácido hidroclorídrico aumentaram o GP da resina infiltrante. Os protocolos de condicionamento ou as técnicas de aplicação não influenciaram os valores de RU.

Influence of different burs and acid ultrasonic agitation on the bonding of fiber posts to root dentin

Aim: The objective is to evaluate the influence of different burs used to prepare the root canal space and acid ultrasonic agitation on bond strength (BS) between glass fiber posts (GFP) and root dentin. Methods: After endodontic treatment, the root canal spaces of 36 extracted human canines were prepared, according to the rotary instrument used (n=18): carbide bur (CB), provided by the post manufacturer and a diamond bur (DB). In both groups, the fiber posts were cemented with the adhesive system Ambar and resin cement Allcem, following the manufacturer`s instructions. Previously to the cementation procedures, the groups were subdivided into 2 groups (n=9), according to the phosphoric acid application mode: conventional etching (CE) and active etching (AE), performed by ultrasonic tip, both for 15s. Before the cementation procedures and after the acid application, 1 root of each group was randomly selected for ultrastructural morphological evaluation by SEM. After 1 week of the cementation, 8 specimens per group were transversely sectioned into six 1-mm thick slices, the root canal regions (cervical, medium and apical) were identified and the push-out test was performed to evaluate BS. Data were analyzed by 3-way ANOVA and Tukey test (α=0.05). Results: The results showed that the cross-product interaction of all factors was significant (P=0.035). Higher bond strength values were obtained when a DB with conventional etching, instead of CB, was used to prepare the root post space. Conclusion: It may be concluded that the use of diamond burs with conventional etching yields high BS values in all root canal thirds

Effect of the Bis-Dimethylamino Benzydrol Coinitiator on the Mechanical and Biological Properties of a Composite.

To examine the effect of the alternative coinitiator 4,4'bis dimethylamino benzydrol (BZN) in degree of conversion (DC), mechanical and biological properties of experimental composites. The coinitiator BZN was used in three concentrations (0.2, 0.5 and 1.2%), and the coinitiator DMAEMA was used as control at the same concentrations as above. The molar concentration of camphorquinone (CQ) and coinitiators was kept constant (1:1). The composites were manipulated and submitted to microhardness test (VHN), flexural and compressive strength (in MPa), elastic modulus (GPa), DC (FT-IR) and in vitro cytotoxicity (against 3T3 fibroblastic cells) of the experimental resins. Data were subjected to two-way ANOVA and Tukey post-test (α=0.05). The experimental composite resin with BZN showed higher DC values compared to control DMAEMA groups. For the mechanical properties, microhardness values were higher in BZN groups; flexural strength and elastic modulus were similar between all the groups. Compressive strength for groups BZN0.5 and DMAEMA0.5 were not statistically different, being the lowest values attributed to group BZN0.2. The experimental resins with BZN and DMAEMA were considered nontoxic against 3T3 fibroblasts. The inclusion of the coinitiator BZN in experimental composites was considered nontoxic against 3T3 fibroblast cells, without compromising DC and mechanical properties.

Effect of the Bis-Dimethylamino Benzydrol Coinitiator on the Mechanical and Biological Properties of a Composite

Abstract To examine the effect of the alternative coinitiator 4,4'bis dimethylamino benzydrol (BZN) in degree of conversion (DC), mechanical and biological properties of experimental composites. The coinitiator BZN was used in three concentrations (0.2, 0.5 and 1.2%), and the coinitiator DMAEMA was used as control at the same concentrations as above. The molar concentration of camphorquinone (CQ) and coinitiators was kept constant (1:1). The composites were manipulated and submitted to microhardness test (VHN), flexural and compressive strength (in MPa), elastic modulus (GPa), DC (FT-IR) and in vitro cytotoxicity (against 3T3 fibroblastic cells) of the experimental resins. Data were subjected to two-way ANOVA and Tukey post-test (α=0.05). The experimental composite resin with BZN showed higher DC values compared to control DMAEMA groups. For the mechanical properties, microhardness values were higher in BZN groups; flexural strength and elastic modulus were similar between all the groups. Compressive strength for groups BZN0.5 and DMAEMA0.5 were not statistically different, being the lowest values attributed to group BZN0.2. The experimental resins with BZN and DMAEMA were considered nontoxic against 3T3 fibroblasts. The inclusion of the coinitiator BZN in experimental composites was considered nontoxic against 3T3 fibroblast cells, without compromising DC and mechanical properties.

Resumo Analisar o efeito do co-iniciador alternativo 4,4'bisdimetilaminobenzidrol (BZN) no grau de conversão (GC) e nas propriedades mecânicas e biológicas de resinas compostas experimentais. O co-iniciador BZN foi utilizado em três concentrações (0,2, 0,5 e 1,2), e o co-iniciador DMAEMA como controle, nas mesmas concentrações acima. A concentração molar entre canforoquinona (CQ) e os co-iniciadores foi mantida constante (1:1). As resinas compostas foram manipuladas e submetidas aos testes de microdureza (VHN), resistência à compressão e flexural (em MPa), módulo de elasticidade (em GPa), GC (em %, por meio de espectroscopia micro-Raman e FTIR com KBr), citotoxicidade in vitro (frente às células fibroblásticas 3T3) das resinas experimentais. Os resultados foram submetidos ao teste ANOVA 1 fator e pós-teste de Tukey (α=0,05). As resinas compostas experimentais com o BZN apresentaram GC e propriedades mecânicas satisfatórias, além de serem consideradas atóxicas a fibroblastos 3T3. A inclusão do co-iniciador BZN à resina composta foi considerada não tóxica frente a células fibroblásticas 3T3 e sem comprometer o grau de conversão e as propriedades mecânicas da mesma.

Active and Passive Application of the Phosphoric Acid on the Bond Strength of Lithium Disilicate.

The objective of this study was to evaluate the effect of passive or active phosphoric acid (PA) application after hydrofluoric acid (HA) treatment on the microshear bond strength of lithium disilicate. Thirty ceramic discs were made with IPS Emax 2 (10 mm thick and 10 mm diameter). The specimens were divided into 3 groups, A: 9.6% HA application; AF: 9.6% HA application + cleaning with 37% PA in passive mode and AFF: 9.6% HA application + cleaning with 37% PA in active mode. For the microshear test, four tygons (0.9 mm diameter and 0.2 mm high) were filled with resin cement (RelyX Ultimate) and placed on the ceramic disks. After testing, the fracture modes were examined under scanning electron microscopy. Data were analyzed by one-way ANOVA and Tukey's post test (α=0.05). The bond strength values were significantly higher in Group AFF (11.0±2.5 MPa) compared with group A (8.1±2.6 MPa) (p<0.002). AF group was not statistically different (9.4±2.5 MPa) from Group A. It was concluded that the active application of 37% PA after 9.6% HA increases the microshear bond strength values between the resin cement and lithium disilicate ceramic.

Active and Passive Application of the Phosphoric Acid on the Bond Strength of Lithium Disilicate

Abstract The objective of this study was to evaluate the effect of passive or active phosphoric acid (PA) application after hydrofluoric acid (HA) treatment on the microshear bond strength of lithium disilicate. Thirty ceramic discs were made with IPS Emax 2 (10 mm thick and 10 mm diameter). The specimens were divided into 3 groups, A: 9.6% HA application; AF: 9.6% HA application + cleaning with 37% PA in passive mode and AFF: 9.6% HA application + cleaning with 37% PA in active mode. For the microshear test, four tygons (0.9 mm diameter and 0.2 mm high) were filled with resin cement (RelyX Ultimate) and placed on the ceramic disks. After testing, the fracture modes were examined under scanning electron microscopy. Data were analyzed by one-way ANOVA and Tukey's post test (α=0.05). The bond strength values were significantly higher in Group AFF (11.0±2.5 MPa) compared with group A (8.1±2.6 MPa) (p<0.002). AF group was not statistically different (9.4±2.5 MPa) from Group A. It was concluded that the active application of 37% PA after 9.6% HA increases the microshear bond strength values between the resin cement and lithium disilicate ceramic.

Resumo O objetivo desse estudo foi avaliar o efeito da aplicação passiva ou ativa do ácido fosfórico após o tratamento com ácido hidrofluorídrico na resistência de união ao microcisalhamento entre cimento resinoso e dissilicato de lítio. Trinta discos foram confeccionados com IPS Emax 2 (10 mm de espessura e 10 mm de diâmetro). Os espécimes foram divididos em três grupos (A: aplicação do ácido hidrofluorídrico 9,6%; AF: aplicação do ácido hidrofluorídrico 9,6% + limpeza com ácido fosfórico 37% em modo passivo; AFF: aplicação do ácido hidrofluorídrico 9,6% + limpeza com ácido fosfórico 37% no modo ativo). Para o teste de microcisalhamento, quatro tygons (0,9 de diâmetro e 0,2 mm de altura) foram preenchidos com cimento resinoso (RelyX Ultimate) e dispostos sobre os discos de cerâmica. Após o teste, os modos de fratura foram examinados por microscopia eletrônica de varredura. Os dados foram analisados estatisticamente por ANOVA e pós-teste de Tukey (α=0,05). Os valores de resistência de união foram significativamente superiores para o grupo AFF (11,0±2,5 MPa), comparado ao grupo A (8,1±2,6 MPa) (p<0,002), mas este não estatisticamente diferente do grupo AF (9,4±2,5 MPa). Concluiu-se que a aplicação ativa do ácido fosfórico 37% após o uso do ácido hidrofluorídrico 9,6% aumenta a resistência de união entre o cimento resinoso e a cerâmica de dissilicato de lítio.

Effect of bleaching agents containing fluoride or calcium on enamel microhardness, roughness and permeability

To evaluate the effect of different in-office bleaching agents on the permeability, roughness and surface microhardness of human enamel. Methods: For evaluation of roughness and microhardness, 40 hemi-faces of 20 premolars were subjected to initial roughness (Ra parameter) and microhardness (VHN) measurements. Thirty-two premolar's crowns were used for permeability test. Then, all specimens were randomly divided into four groups: C - without bleaching (control), HP35 - bleaching with 35% hydrogen peroxide (HP), HPF38 - 38% HP+fluoride, HPC35 - 35% HP+calcium. Final roughness (FR) and microhardness (FM) measurements were evaluated. For permeability, the 32 crowns were immersed in 1% sodium hypochlorite (20 min) and silver nitrate solutions (2 h) and subjected to developing solution under fluorescent light (16 h). Three sections from the crowns were analyzed in light microscope (100x) to evaluate the scores of permeability: Score 0 - no tracer agent penetration; Score 1 - less than half the thickness of enamel penetration; Score 2 - tracer agent reaching half the enamel thickness; Score 3 - entire enamel depth penetration, without reaching dentin and Score 4 - tracer agent reaching dentin. For roughness and microhardness evaluation were used one-way ANOVA and Dunnet post-test for independent samples, and t test for paired samples. For permeability, the data were analyzed by Kruskal Wallis and Dunn tests. Results: A significantly higher permeability and surface roughness were observed in groups HP35, HPF38 and HPC35 compared to the C group, as well as decreased microhardness (p<0.05). Conclusions: All bleaching agents increased permeability and surface roughness, and decreased microhardness of human enamel; thus, the addition of fluoride or calcium was not beneficial...

Clinical evaluation of the whitening effect of over-the-counter dentifrices on vital teeth.

This randomized clinical trial evaluated the whitening potential of commercially available toothpastes. Sixty patients were selected and randomly divided into 4 groups (n=15), according to the dentifrice used: GI (control) - Colgate Total 12, GII - Close-up White Now, GIII: Oral-B 3D White, GIV: Colgate Luminous White. Three daily brushings were performed for 2 to 3 min each, during a period of 15 days. Patients had the color of their teeth evaluated before and after the treatment by means of a spectrophotometer (Vita EasyShade - CIE L*a*b*). Data obtained from L values were analyzed by one-way ANOVA and t test. ∆E was also evaluated to calculate color alteration, by NBS criteria. Mean (standard deviation) of initial values were GI: 82.9 (4.9); GII: 83.9 (5.8); GIII: 83.9 (7.2); GIV: 86.4 (3.4) and final values were GI: 84.1 (6.3); GII: 84.6 (6.1); GIII: 84.2 (7.1); GIV: 88.2 (2.8). In conclusion, the dentifrices showed no lightening action on vital teeth, except for Colgate Luminous White; but according to NBS criteria, there was no noticeable visible change to the patients in any group.

Clinical Evaluation of the Whitening Effect of Over-the-Counter Dentifrices on Vital Teeth

This randomized clinical trial evaluated the whitening potential of commercially available toothpastes. Sixty patients were selected and randomly divided into 4 groups (n=15), according to the dentifrice used: GI (control) - Colgate Total 12, GII - Close-up White Now, GIII: Oral-B 3D White, GIV: Colgate Luminous White. Three daily brushings were performed for 2 to 3 min each, during a period of 15 days. Patients had the color of their teeth evaluated before and after the treatment by means of a spectrophotometer (Vita EasyShade - CIE L*a*b*). Data obtained from L values were analyzed by one-way ANOVA and t test. ∆E was also evaluated to calculate color alteration, by NBS criteria. Mean (standard deviation) of initial values were GI: 82.9 (4.9); GII: 83.9 (5.8); GIII: 83.9 (7.2); GIV: 86.4 (3.4) and final values were GI: 84.1 (6.3); GII: 84.6 (6.1); GIII: 84.2 (7.1); GIV: 88.2 (2.8). In conclusion, the dentifrices showed no lightening action on vital teeth, except for Colgate Luminous White; but according to NBS criteria, there was no noticeable visible change to the patients in any group.

Este estudo clínico randomizado avaliou o potencial clareador de cremes dentais disponíveis no mercado. Materiais e Métodos: Foram selecionados 60 pacientes, os quais foram divididos aleatoriamente em 4 grupos (n=15): GI - controle - Colgate Total 12; GII- Close-up White Now; GIII - Oral-B 3D White; GIV - Colgate Luminous White. Foram realizadas 3 escovações diárias pelo tempo de 2 a 3 minutos, durante um período de 15 dias. Os pacientes tiveram a cor de seus dentes avaliados antes e após o término do tratamento através do espectrofotômetro Vita EasyShade (escala CIE L*a*b*) Os valores de L* foram analisados por ANOVA um fator para amostras independentes e teste t para amostras pareadas. ∆E também foi calculado para verificar alterações de cor, de acordo com os critérios NBS. A média (desvio padrão) dos valores iniciais foi: GI: 82,9(4,9); GII: 83,9(5,8); GIII: 83,9(7,2); GIV: 86,4(3,4); e os valores finais - GI: 84,1(6,3); GII: 84,6(6,1); GIII: 84,2(7,1); GIV: 88,2(2,8), concluindo-se que os dentifrícios analisados neste estudo não apresentaram ação clareadora sobre dentes vitais, com exceção do dentifrício Colgate Luminous White, porém de acordo com os critérios do NBS, não houve alteração visível a olho nu para nenhum dos grupos.

Effect of finishing and polishing on surface roughness of composite resins after bleaching

AIM : To evaluate the influence of finishing and polishing techniques on the surface roughness of two composite resins (CRs) subjected to bleaching procedure. METHODS : Forty-eight CR specimens were divided into six groups (n=8). For G1 to G3, a microhybrid CR (Opallis; FGM) was used, and G4 to G6, received a nanohybrid CR (Brilliant NewLine; Coltène/Whaledent). All specimens were subjected to bleaching procedure with 35% hydrogen peroxide (two 45-min applications, with a 5-day interval). The surface roughness of all specimens was evaluated before and after the bleaching and/or finishing/polishing (Ra parameter) by a roughness meter. After bleaching, the groups were subjected to finishing and polishing procedures: G2 and G5 - felt discs + diamond pastes; and G3 and G6 - silicon rubber tips. The control groups (G1 and G4) had no finishing or polishing treatment after bleaching. Data were analyzed by ANOVA and Tukey's post-test, and t test for paired samples (a=0.05). RESULTS : bleaching treatment increased Ra values for the nanohybrid CR specimens, but both finishing/polishing techniques were able to reduce these values; for the microhybrid specimens, only finishing/polishing with silicon rubber tips decreased the roughness values. CONCLUSIONS : For both microhybrid and nanohybrid CRs, the silicon rubber tips were effective to reduce the surface roughness after bleaching procedure...

Shrinkage stress of resin composites: effect of material - sistematic review / Tensão de contração de resinas compostas: efeito da composição do material - revisão sistemática

The longevity of resin depends on its binding between the margin of restorations and the polymer, and one factor that influences this aspect is the shrinkage stress. Thus, the working group presents the following systematic review thatverifies the influence of composite resin composition on shrinkage stress. The following electronic databases were searched: MEDLINE (via Ovid and PubMed - 2004 to January 2014), with the keywords: shrinkage stress, degree of conversion, resin composite. For shrinkage stress,, the best results were found when the BISGMA monomer was used and for the inorganic composition, an inverse relationship was observed: the increased inorganic filler content decreases shrinkage stress.

A longevidade de resina depende da sua ligação entre a margem de restaurações e o polímero, e um fator que influencia a este aspecto, é a tensão de contração. Assim, o grupo de trabalho faz a seguinte análise sistemática para verificar a influência da composição das resinas composta na tensão de contração. As seguintes bases de dados eletrônicas foram pesquisadas: MEDLINE (via PubMed e Ovídio - de 2004 a janeiro de 2014), com as palavras-chave: estresse de contração, grau de conversão, resina composta. Para tensão de contração, os melhores resultados foram encontrados quando o monômero BISGMA foi utilizada e para a composição inorgânica, uma relação inversa foi observada: o aumento do teor de carga inorgânica diminui estresse de contração.

Evaluation of human enamel permeability exposed to bleaching agents

Aim: To evaluate the human enamel permeability after different external bleaching techniques.Methods: The coronal portions of 20 maxillary human incisors were covered with an acidresistant varnish, except the labial surface, to prevent dye penetration of silver nitrate. Thespecimens were divided randomly into four groups (n=5) according to the bleaching treatments:Group 1 (G1) - without bleaching agent (control group), Group 2 (G2) - 35% hydrogen peroxide(HP) – one session of three 10-min applications, Group 3 (G3) - 35% HP – 2 sessions of three10-min applications, and Group 4 (G4) - 6% HP – 14 days (1h/day). G1 was exposed to artificialsaliva only and in the other groups the bleaching agents were applied following the manufacturers’recommendations. After bleaching, teeth were immersed in a 50% silver nitrate solution for 2 hand photodeveloped for 16 h. Then, three longitudinal slices of each tooth were photographedby an optical microscope (100x). The degree of dye penetration was analyzed in the middle thirdof the dental crowns using a 0 to 4 score system (0= no dye penetration, 1= less than half theenamel thickness, 2= half of the enamel thickness, 3= full extent of enamel without reaching thedentin, and 4= tracer agent reaching dentin). The data were analyzed statistically by the Kruskal-Wallis and Dunn tests (α=0.05). Results: The median (1st/3rd interquartiles) ranges were: G1:0(0/0), G2: 2(2/3), G3: 3(3/3) and G4: 3(3/3). G2, G3 and G4 showed significantly higher dyepenetration compared with G1 (p=0.0017). Conclusions: The use of bleaching agents increaseddental enamel permeability, regardless of the bleaching technique.

Efeito do clareamento na susceptibilidade ao manchamento de uma resina composta / Effect of bleaching on staining susceptibility of a composite resin

Objetivo: verificar o efeito do clareamento (caseiro e em consultório) na susceptibilidade ao manchamento de uma resina composta e imersão em soluções corantes. Trinta espécimes de resina composta microhíbrida sofreram avaliação de cor inicial (Vita EasyShade) e aleatoriamente divididos em 6 grupos G1: sem clareamento, com imersão em café; G2: sem clareamento, com imersão em vinho; G3: clareado com peróxido de carbamida 10% (PC 10%) e imersão em café; G4: clareado com PC 10% e imersão em vinho; G5: clareado com peróxido de hidrogênio 35% (PH 35%) e imersão café e G6: clareado com PH 35% e imersão em vinho. Em seguida, houve avaliação final de cor. Os resultados foram analisados por ANOVA 2 fatores e Pós-teste de Tukey (α=0,05). Foram avaliados valores de L (luminosidade), sendo as médias (desvio-padrão) dos valores iniciais - G1: 88,22(1,62); G2:86,76(0,86); G3:82,52(2,90); G4:84,72(1,24); G5:85,64(1,92); G6:86,30(1,13), e os valores finais: G1: 78,32(2,24); G2: 76,46(1,61); G3: 74,60(0,92); G4: 65,00(3,97); G5: 75,56(1,76); G6: 72,48(4,69). Os valores de ΔE também foram calculados (critérios do NBS). Conclusão: a resina composta, submetida ao clareamento, caseiro sofreu maior alteração de cor quando imerso em vinho tinto, comparado aos demais grupos.

Objective: to evaluate the effect of at-home and in-office bleaching on staining susceptibility of a resin composite with immersion in staining solutions. Thirty specimens of a microhybrid composite were first evaluated with a spectrophotometer (Vita Easyshade), and randomly divided into 6 groups: G1: no bleaching, immersion in coffee; G2: no bleaching, immersion in red wine; G3: bleaching with 10% carbamide peroxide (PC10%) and immersion in coffee; G4: bleaching with PC10% and immersion in wine; G5: bleaching with 35% hydrogen peroxide (PH35%) and immersion in coffee; G6: PH35% and immersion in wine. The final color was evaluated for all groups. Color change values (CIELab), by means of L values - luminosity - were evaluated and statistically analyzed by ANOVA and Tukey's post-test. Results: means(standard-deviation) for initial L values were: G1:88.22(1.62); G2:86.76(0.86); G3:82.52(2.90); G4:84.72(1.24); G5:85.64(1.92); G6:86.30(1.13), e final L values were: G1:78.32(2.24); G2:76.46(1.61); G3:74.60(0.92); G4:65.00(3.97); G5:75.56(1.76); G6:72.48(4.69). ΔE values were also calculated, according to NBS criteria. Conclusion: there was an increased staining susceptibility of the resin composite submitted to at-home bleaching when immersed in red wine, compared to the another groups, by means of luminosity.

Efeito de diferentes agentes clareadores de uso caseiro na microdureza superficial de resinas compostas: microhíbrida X nanohíbrida / Effect of different at-home bleaching agents in microhardness surface of resin composites: microhybrid X nanohybrid

Avaliou-se o efeito de agentes clareadores de uso caseiro na microdureza de resinas compostas (RC) microhíbrida e nanohíbrida. Foram confeccionados 30 corpos-de-prova (cp), divididos em seis grupos (n=5). Os grupos G1 a G3 utilizaram RC microhíbrida (Opallis), e os grupos G4 a G6, RC nanohíbrida (BrilliantNewLine). Os agentes clareadores utilizados foram: peróxido de hidrogênio 6% (PH) (White Class Cálcio) e peróxido de carbamida 16% (PC) (Whiteness Perfect). Após a confecção dos cp, o clareamento foi realizado: G1 e G4: grupo controle sem agente clareador, G2 e G5: PH - 28 dias, G3 e G6: PC - 28 dias, de acordo com as recomendações dos fabricantes. Em seguida, o teste de microdureza foi realizado. Os dados obtidos foram analisados por ANOVA e Tukey (5%). Os resultados de microdureza (HV) e desvio-padrão foram: G1-26,56 ± 3,9, G2-25,98 ± 3,3 e G3-24,94 ± 4,4; G4-27,24 ± 3,3; G5-32,02 ± 6,4 e 37,72 G6- ± 8,1. O único grupo que apresentou diferenças significativas para os outros foi o G6 (p <0,05), mas não diferiu significativamente em relação ao G5 (p = 0,0058). Concluiu-se que o uso de agentes clareadores de uso caseiro não afetou negativamente a microdureza das resinas compostas testadas.

It was evaluated the effects of home bleaching agents on microhardness of microhybrid and nanohybrid composite resins. 30-of-body were made and divided into 6 groups (n=5). The groups G1 to G3 used a microhybrid CR (Opallis), while groups G4 to G6 used a nanohybrid CR (BrilliantNewLine). The bleaching agents used were: 6% hydrogen peroxide (PH) (White Class Cálcio) and 16% carbamide peroxide (PC) (Whiteness Perfect). After the specimens were prepared, the bleaching was realized as follows: G1 and G4: control group without bleaching agent, G2 and G5: PH - 28 days, G3 and G6: PC - 28 days, in accordance with the manufacturer's recommendations. After it, the microhardness test was performed. The data were statistically analyzed by ANOVA and Tukey's tests (5%). The results of microhardness (HV) and standard deviation of each group were: G1- 26.56±3.9; G2- 25.98±3.3; G3- 24.94±4.4; G4- 27.24±3.3; G5- 32.02±6.4 and G6- 37.72±8.1. The only group that showed significant differences to the anothers was the G6 (p<0.05), but did not differ significantly in relation to G5 (p=0.0058). It was concluded that the use of home bleaching agents didn't affect negatively the microhardness of the composite resins tested.

Effect of light-curing units on gap formation and microleakage of class II composite restorations

Aim: This in vitro study evaluated gap width formation and marginal microleakage in Class IIcomposite restorations light-cured with three different light-curing units. Methods: Standardizedcavities in the proximal surfaces of 36 human third molars were made with margins located belowthe cementoenamel junction. Cavities were restored with Filtek P60 (3M ESPE), inserted with aphotocondenser tip and light-cured with three different methods: GI - Optilux401 (halogen); GII –ColtoluxLED (LED) and GIII –UltraLumeLED5 (LED). After finishing the restorations, teeth weresubjected to a thermal cycling regimen of 500 cycles (5oC ± 2oC and 55oC ± 2oC), totalizing 500cycles. Thereafter, the teeth were sectioned in a buccolingual direction and in the center of therestorations. Half of the specimens (18) were used to evaluate marginal microleakage, by measuringof dye penetration in cross-sectioned specimens, and the other half was used to analyzed the gapformation width by SEM observations (1000X). Data were submitted to Kruskal-Wallis (α=0.05).Results: The mean values of gap width (μm) were: GI 3.28±3.34; GII 1.48±1.89 and GIII3.11±3.45, and microleakage was not affected by the light-curing units. Conclusions: Therewere no differences between the light-curing methods in gap formation and marginal microleakage.

Efeito de diferentes agentes clareadores na rugosidade superficial de resinas compostas / Effect of different bleaching agents on surface roughness of composite resins

O presente estudo avaliou o efeito de agentes clareadores na rugosidade superficial de resinas compostas (RC). Foram confeccionados 50 corpos-de-prova, divididos em 10 grupos (n=5). Os grupos G1 ao G5 utilizaram a RC Opallis (microhíbrida); G6 ao G10 a RC Brilliant NewLine (nanohíbrida). Os agentes clareadores foram: PH - Peróxido de hidrogênio 35% (Whiteness HP Max) e PC - Peróxido de carbamida 37% (Whiteness Super). Após 24 horas, realizou-se o clareamento: G1 e G6- sem agente clareador (controles); G2 e G7- uma sessão de PH com três aplicações; G3 e G8- duas sessões de PH com três aplicações cada; G4 e G9- uma sessão de PC com três aplicações e G5 e G10- duas sessões de PC com três aplicações cada. Após o clareamento, os cp foram avaliados no Rugosímetro. Os dados obtidos foram analisados por ANOVA com pós-teste de Bonferroni (α=0,05). Os resultados de rugosidade superficial (μm) foram: G1-0,07±0,02; G2-0,12±0,04; G3-0,40±0,33; G4-0,49±0,65; G5-1,33±1,76; G6-2,03±1,22; G7-1,15±0,46; G8-1,33±1,24; G9-0,56±0,59 e G10-1,87±1,31. Os resultados mostraram que para a RC Opallis, os valores de rugosidade aumentaram após o clareamento e para a RC Brilliant NewLine, os valores diminuíram. Concluiu-se que o uso de agentes clareadores afetou a rugosidade das resinas compostas testadas.

This study evaluated the effect of bleaching agents on surface roughness of composite resins (RC). 50-of-body were made and divided into 10 groups (n=5). In Groups G1 to G5 was used Opallis (a microhybrid RC), and in G6 to G10 Brilliant NewLine (a nanohybrid RC) was used. The bleaching agents were: PH-35% hydrogen peroxide (HP Max Whiteness) and PC-Carbamide peroxide 37% (Whiteness Super). After 24 hours, bleaching was performed: G1 and G6-without bleaching agent (control), G2 and G7-one session with three applications of PH, G3 and G8-two sessions of three applications of HP, G4 and G9-one session with three applications of PC and G5 and G10-two sessions of three applications of PC. After bleaching, specimens were evaluated in a roughness meter. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). The results of surface roughness (μm) were: G1-0.07 ± 0.02, G2-0.12 ± 0.04, G3-0.40 ± 0.33, G4-0.49 ± 0.65; G5-1.33 ± 1.76; G6-2.03 ± 1.22; G7-1.15 ± 0.46; G8-1.33 ± 1.24; G9-0.56 ± 0.59 and G10-1.87 ± 1.31. The results showed that Opallis roughness values increased after bleaching and Brilliant NewLine values decreased. It was concluded that the use of bleaching agents affected the roughness of composite resins tested.

Comparação da radiopacidade de cimentos resinosos pelos sistemas de radiografia convencional e digital / Comparison of radiopacity in luting resin cements using conventional and digital radiographic systems

Objective: To evaluate the radiopacity of three different resin composite luting cements using the histogram method (conventional radiography) and pixel counting method (digital radiography). Methods: Fifteen specimens were divided into 3 different resin composite luting cement groups: G-I) Cement-Post (Ângelus®, Londrina, Brazil), G-II) RelyX ARC (3MESPE, St. Paul, Minnesota, USA) and G-III) Variolink II (Ivoclar/Vivadent, Schaan, Liechtenstein). After 24 hours, conventional x-rays of the specimens were taken with a lead gauge, making a visual evaluation by scores, to classify the specimen?s radiopacity according to the scale shade (control); they were then scanned for the purposes of analyzing the histogram using Adobe Photoshop CS2, version 8.0. Using the same specimens, x-rays were taken using a Digital X-RAY Intra-Oral System (Gnatus DSR, Ribeirão Preto, Brazil). In this case, the capture of the digital images was performed using Cygnus Imaging® software and the digital radiopacity was measured by counting pixels, using the Image Tool® software (UTHSCSA). Results: The non-parametric Kruskal-Wallis test and Dunn?s post-test (p<0.05) showed that the means and respective standard deviation percentages of white pixels in the digital x-rays were: G-I) 48.94 ±3.16, G-II) 60.22 ±3.86 and G-III) 69.36 ±5.32. As for the conventional x-rays, the means and standard deviations of the histogram analyses that evaluated gray tones were: G-I) 71.98 ±13.02; G-II) 85.40 ±4.47; G-III) 130.51 ±5.82. Conclusion: In conclusion, regardless of the method used (conventional or digital x-rays), G-III obtained the largest radiopacity value.

Objetivo: Avaliar a radiopacidade de cimentos resinosos pelo método do histograma (radiografia convencional) e da contagem de pixels (radiografia digital). Métodos: Foram utilizados 15 corpos-de-prova divididos em três grupos de cimentos resinosos: Grupo I) Cement-Post (Ângelus®, Londrina, Brasil), Grupo II) RelyX ARC (3MESPE, St. Paul, USA) e Grupo III) Variolink II (Ivoclar/Vivadent, Schaan, Liechtenstein). Após 24 horas, foram realizadas radiografias convencionais dos corpos-de-prova juntamente com uma escala de chumbo, realizando assim uma avaliação visual por escores para classificar a radiopacidade dos corpos-de-prova de acordo com a tonalidade da escala (controle); e em seguida, foram escaneadas para análise do histograma no software Adobe Photoshop CS2 versão 8.0. Com os mesmos corpos-de-prova, realizaram-se tomadas radiográficas empregando-se o Sistema Intra-oral de Raio-X Digital (Gnatus, Ribeirão Preto, Brasil), sendo a captura das imagens digitais realizadas com o software Cygnus Imaging® e a radiopacidade digital mensurada pela contagem de pixels com o software Image Tool® (UTHSCSA). Resultados: O teste não-paramétrico de Kruskal-Wallis e Dunn (p<0,05) mostrou que as médias das porcentagens de pixels brancos das radiografias digitais e os seus respectivos desvios-padrão foram: Grupo I) 48,94 ±3,16; Grupo II) 60,22 ±3,86 e Grupo III) 69,36 ±5,32. Já nas radiografias convencionais, as médias e os desvios-padrão das análises do histograma avaliando tons de cinza foram: Grupo I) 71,98 ±13,02; Grupo II) 85,40 ±4,47 e Grupo III) 13,51 ±5,82. Conclusão: Pode-se concluir que utilizando tanto o sistema de radiografia convencional quanto o sistema digital, o Grupo III obteve uma maior radiopacidade.