Correction: University engagement of dental students related to educational environment: A transnational study.

[This corrects the article DOI: 10.1371/journal.pone.0259524.].

University engagement of dental students related to educational environment: A transnational study.

OBJECTIVES: To investigate the validity and reliability of the University Student Engagement Inventory (USEI) in its complete and reduced versions with Brazilian and USA students, and to evaluate the influence of gender and academic level on students' university engagement in both countries. METHODS: A cross-sectional observational study with a non-probability sample was conducted. The sample comprised dental students of both genders, 154 from a university in New York, USA (response rate 91.1%) and 459 from two universities in Brazil (response rate 79.1%). University engagement was measured using the USEI. The samples were characterized by gender and academic level. RESULTS: The refined reduced version of the USEI presented adequate fit to the samples from both countries. Gender was associated with the behavioral engagement factor of the USEI in Brazilian students. In the USA sample, gender was associated with the behavioral and cognitive engagement factors. There was a significant effect of academic level on behavioral and emotional engagement for the Brazilian and USA samples, respectively. CONCLUSION: The refined reduced USEI presented adequate psychometric qualities for the study samples.

Magnification loupes in dentistry: A qualitative study of dental students' perspectives.

INTRODUCTION: The nature of the oral operating field makes it a challenge for dentists to work while maintaining musculoskeletal health. Strategies have been studied in recent years to improve visualisation of the operating field, and the use of magnification systems has been recommended for providing additional benefits. Despite the growing body of evidence suggesting that the use of magnification improves visual acuity, the dentist's posture and the quality of dental procedures, few studies have analysed users' perspectives on these devices in terms of their adaptation process. These types of studies are important because they provide insight into the reality of the adaptation process required by magnification systems so that adjustments and improvements can be made to adapt these systems to the users' reality. Thus, we sought to explore the perspectives held by second-year students in an undergraduate dental program on the use of dental loupes during pre-clinical laboratory activities. MATERIALS AND METHODS: A total of 24 second-year dental students participated in semi-structured interviews exploring their perspectives of wearing dental loupes during their pre-clinical activities. Data collection and analysis were consistent with the qualitative content analysis methodology. All interview data were analysed using version 10 of the NVivo® analytical software. RESULTS: Participants described that magnification can lead to the improvement of their work postures, hand skills and quality of dental procedures. Nevertheless, they reported a need for an adaptation period and for adjustments to the technical features of the magnification system. CONCLUSION: The students had positive perspectives on the use of magnification in their dentistry training program, including improvements in posture, hand skills and procedure quality.

Cross-infection control in clinical training: Development of a device for storing a composite resin in restorative dentistry.

This study presented a biosafety device for the hygienic storage of composite resin during restorative procedures in teaching clinics, RESTAURASAFE, and to compare the color stability, surface hardness, and degree of conversion of the composite resin made with the proposed device to those of conventionally made resins. Esthet-X HD composite was manipulated directly from the syringe, fractionated doses, dappen dish or RESTAURASAFE. Disc-shaped specimens were immersed in artificial saliva and coffee for 60 days and the color stability and the Vickers surface hardness were evaluated during 60 days. Degree of conversion was assessed after immersing specimens in saliva (baseline). The surface morphology analysis of composite resin has taken by scanning electron microscopy (SEM). The data were evaluated statistically by repeated measures ANOVA (α=.05). No difference of color stability was observed for saliva and coffee regardless of storing devices. The resin manipulated directly from the syringe presented lower hardness, and fractionated doses presented lower degree of conversion than the RESTAURASAFE. SEM analysis showed that after artificial aging in coffee for 60 days, the specimens prepared with fractionated doses of resin displayed the fewest changes in surface morphology, followed by those prepared with the RESTAURASAFE. We conclude that RESTAURASAFE allows to obtain similar color stability, higher hardness, and degree of conversion of the composite in comparison to the other storing devices.

Effect of adhesive mode and chlorhexidine on microtensile strength of universal bonding agent to sound and caries-affected dentins.

OBJECTIVE: The main objective of this study is to assess the effect of the adhesive mode and chlorhexidine (CHX) on the microtensile strength of a universal bonding agent to sound and caries-affected dentins. MATERIALS AND METHODS: Six intact third molars and six decayed third molars were sectioned to obtain two middle dentin specimens per tooth. Prime and Bond Elect Universal (Dentsply) was applied to specimens in two different modes: Etch-and-rinse (ER, phosphoric acid for 15s) and self-etch (SE, no phosphoric acid). 2% CHX (Cavity Cleanser, Bisco) was applied to both dentins for 30 s. Specimens were randomly assigned into eight groups (n = 3) according to the treatments applied to sound and caries-affected dentins: SE; ER; SE + CHX; and ER + CHX. All specimens were restored with TPH Spectra High Viscosity (Dentsply) composite resin and sectioned to obtain specimens of 0.8 ± 0.1 mm2. The microtensile bond strength test was conducted at 1 mm/min. The data were statistically analyzed by ANOVA and multiple comparisons' test (α = 0.05). RESULTS: There was no significant difference between sound dentin and caries-affected dentin (P = 0.132). The highest bond strength was obtained with the application of the ER (31.81MPa). SE + CHX promoted the lowest bond strength with no statistical difference to ER + CHX (P > 0.05). CONCLUSIONS: ER mode for the universal bonding agent yielded the highest bond strength to sound and caries-affected dentins. CHX reduced the bond strength to both dentins regardless the application of phosphoric acid. CLINICAL SIGNIFICANCE: The universal bonding agent increased the bond strength to sound and caries-affected dentins when applied by the ER mode.

Validity and reliability of the Disabilities of Arm, Shoulder, and Hand scale in dental students: A transnational study.

This study aimed to evaluate the validity and reliability of the Disabilities of Arm, Shoulder, and Hand (DASH) scale in Brazilian and American dental students and assess the influence of demographic variables on disability in them. A cross-sectional observational study was conducted with a nonprobabilistic sample. The sample was composed of students of both genders from the School of Dentistry of Araraquara, State University of São Paulo (UNESP) (n = 288), and students from Stony Brook University, New York, NY, USA (n = 149). The disabilities of the upper limbs were estimated using the DASH scale. The samples were characterized by collecting information on gender, academic year, and sports and work activities. The refined bifactorial model presented goodness-of-fit indices for both countries. There was a significant effect of the variables gender and academic year for the Brazilian sample and the variable sports practices for the American sample. The refined bifactorial model was valid and reliable for the Brazilian and American populations. In this model, the removal of item 17 for the Brazilian sample and items 3, 13, and 23 for the American sample was necessary. Demographic variables such as gender, academic year, and sports practice contributed significantly to the level of disability in the study populations.

Antibacterial activity of glass ionomer cement modified by zinc oxide nanoparticles.

This study evaluated the antibacterial activity of zinc oxide nanoparticles incorporated into self-cured glass ionomer cement (GIC) and light-cured resin-reinforced GIC on Streptococcus mutans biofilm. The GICs, Fuji II (GC America) and Fuji II LC (GC America), were incorporated with nanoparticles at concentrations of 0%, 1%, and 2% by weight, and the biofilm maturation time was one and seven days. Circular specimens of each GIC type were prepared. The antibacterial activity was evaluated by determining the number of colony forming units of S. mutans strain per milliliter. Morphology of the biofilm was analyzed by scanning electron microscopy (SEM). The data obtained for each GIC were analyzed by two-way ANOVA (α = 5%). For chemically activated GIC, no significant difference was observed in relation to the time of biofilm maturation (p = 0.744), concentration of nanoparticles (p = 0.966), and their interaction (p = 0.800). The results from analysis of GIC modified by light-polymerized resin showed that only of the maturing time significantly affected the number of adhered cells on the biofilm (p = 0.034, F = 4.778). The more mature the biofilm, higher the number of cells. SEM analysis showed no change in cell morphology in relation to the type of GIC, maturation time, and nanoparticles concentration. We conclude that the inclusion of zinc oxide nanoparticles at concentrations of 1% and 2% by weight into the GICs evaluated here, did not promote their antimicrobial activity against S. mutans.

Influence of light curing units and fluoride mouthrinse on morphological surface and color stability of a nanofilled composite resin.

Composite resin is a dental material susceptible to color change over time which limits the longevity of restorations made with this material. The influence of light curing units and different fluoride mouthrinses on superficial morphology and color stability of a nanofilled composite resin was evaluated. Specimens (N = 150) were prepared and polished. The experimental groups were divided according to the type of light source (halogen and LED) and immersion media (artificial saliva, 0.05% sodium fluoride solution-manipulated, Fluordent Reach, Oral B, Fluorgard). Specimens remained in artificial saliva for 24-h baseline. For 60 days, they were immersed in solutions for 1 min. Color readout was taken at baseline and after 60 days of immersion. Surface morphology was analyzed by Scanning Electron Microscopy (SEM) after 60 days of immersion. Color change data were submitted to two-way Analysis of Variance and Tukey tests (α = 0.05). Surface morphology was qualitatively analyzed. The factor light source presented no significant variability (P = 0.281), the immersion media, significant variability (P < 0.001) and interaction between factors, no significant variability (P = 0.050). According to SEM observations, no difference was noted in the surface of the specimens polymerized by different light sources, irrespective of the immersion medium. It was concluded that the light source did not influence the color stability of composite, irrespective of the immersion media, and among the fluoride solutions analyzed, Fluorgard was the one that promoted the greatest color change, however, this was not clinically perceptible. The immersion media did not influence the morphology of the studied resin.

Effects of immersion media and repolishing on color stability and superficial morphology of nanofilled composite resin.

This study evaluated the influence of fluoride mouth rinses and repolishing on the superficial morphology and color stability of nanofilled resin. About 150 specimens were prepared and polished using aluminum oxide discs for 15 s with a pressure of 2 kg. The experimental groups were divided according to the immersion medium (artificial saliva, 0.5% sodium fluoride, Fluordent Reach, Oral B, Fluorgard) and repolishing procedure (without and with). The specimens were continuously immersed for 1 week. Thereafter, half of each sample was repolished. A color reading was performed after 24 h of immersion in the artificial saliva baseline, after continuous immersion, and after repolishing. The superficial morphology was examined using scanning electron microscopy (SEM) in a qualitative way. Color change (∆E) data were submitted to a mixed analysis of variance using a Shapiro-Wilk test (p>0.05 for the different immersion media) and Sidak's test (p<0.05 for the differences between groups). In the interaction between the repolishing and the immersion media, Fluorgard showed a statistical difference between the ∆E values with and without repolishing (p<0.0001). On the SEM observations, both Fluordent Reach and Fluorgard caused degradation of the superficial resinous matrix of the composite after continuous immersion. This matrix was removed after repolishing.

Color stability of a nanofilled resin: influence of polishing andFinishing and fluoride solutions according to time

AIM: The aim of the study was evaluate the finishing and polishing effect of the color stability of the composite resin Filtek Supreme XT, according to different fluoride solutions and time. MATERIAL AND METHODS: Specimens were prepared n=140 with half of the samples finished and polished. The experimental groups were divided according to the presence or absence of finishing and polishing and immersion solutions artificial saliva, sodium fluoride solution at 0.05% b manipulated, Fluordent Reach, Oral B, Fluorgard. The specimens remained in artificial saliva for 24 hours and were subjected to an initial color analysis using a spectrophotometer CIELab system. Then, they were immersed in the experimental solutions for 1 minute a day. The readings of the color change were made after 24 and 48 hours, 7, 14, 21, 30 and 60 days after the first immersion. The three bway mixed Analysis of Variance (ANOVA) "finishing/polishing", "immersion medium" and “time” were performed. For multiple comparisons, the Sidak test for repeated measure was used, with a 5% level of significance. RESULTS: The finishing and polishing factor showed significant variability, independently of the immersion media (p<0.001). CONCLUSION: Finishing and polishing procedures yielded better color stability to composite resin over time, regardless of the immersion media.

Influência dos hábitos de sucção na manifestação de dor têmporo-mandibular: revisão sistemática / Influence of oral sucking habits on symptoms of temporomandibular dysfunction: a systematic review

Este estudo teve como objetivo realizar uma revisão sistemática da literatura para avaliar os efeitos dos hábitos parafuncionais de sucção sobre a ATM e estruturas adjacentes em crianças. Os artigos incluídos foram identificados por meio de pesquisas bibliográficas da Bireme, Pubmed, ClinicalTrials.gov, The National Research Register e Pro-Quest Dissertation Abstracts and Thesis, usando os termos de busca temporomandibular joint, sucking behavior and fingersucking. As pesquisas sobre os hábitos atuais ou anteriores de chupar o dedo e/ou uso de mamadeiras e chupetas e a presença de dor na ATM com crianças até 12 anos foram incluídas. Oito estudos foram selecionados, e 4 apresentaram uma associação, mas sem significância estatística. Os achados científicos demonstram uma associação baixa ou ausente de DTM com hábitos de sucção parafuncionais.

Objective: To assess the attitudes and knowledge about hepatitis by scholars and dental practitioners from Recife and its metropolitan region. Method: The research protocol was submitted and approved by the Ethics and Human Research Committee of the Federal University of Pernambuco. There were included 230 undergraduate students in dentistry and 104 dentists who exercise their professional activity in Recife and its Metropolitan Region. They signed a consent form and answered a questionnaire, the evaluative instrument, with objective questions about biosafety, transmission of hepatitis and sexually transmitted diseases. Results: About the types of hepatitis 133 (57.8%) students and 61 (58.7%) professionals claimed to know the types A, B and C. Concerning transmission 31 (13.5%) students and 25 (24.0%) professionals said that the main route of transmission were sexual and bloodstream respectively. Relating to imunization 221 (96.1%) students and 99 (95.2%) professionals reported that have been vaccinated against hepatitis B, however, only 126 (54.8%) students and 55 (52.9%) professionals have followed the immunization's schema. Regarding the cleaning of the office equipment, 18.7% of the students replied that they do not know who does it. 56.7% of professionals said that it was performed with alcohol 70 ° GL.Conclusions: The findings indicate that there is a concern for biosafety but the knowledge about the forms of hepatitis transmission and biosecurity measures need to be better settled.

Efeito das perfurações radiculares na resistência adesiva de pinos defibra de vidro e cimentos resinosos / Effects of root perforations on the adhesive resistance of fiberglass pins and resin cements

O objetivo deste estudo foi avaliar o efeito das perfurações radiculares na resistência adesiva de pinos de fibra de vidro cimentados com dois cimentos resinosos à dentina intra-radicular. Quarenta dentes humanos unirradiculares hígidos receberam tratamento endodôntico e foram preparados para a cimentação de pinos de fibra de vidro (Exacto Mini, Angelus). Os dentes foram divididos em 4 grupos experimentais (n=10) de acordo com a condição radicular (perfuração presente ou ausente) e o cimento resinoso utilizado: G1: perfuração ausente + cimento Rely X™ U100 (3M ESPE); G2: perfuração ausente + Panavia F2.0 (Kuraray); G3: perfuração presente + Rely X™ U100 (3M ESPE); G4: perfuração presente + Panavia F2.0 (Kuraray). A perfuração foi realizada na superfície radicular com ponta diamantada e selada com agregado de trióxido mineral branco (MTA). Os espécimes foram seccionados para a realização do teste de extrusão por cisalhamento (Push-out) com velocidade de 1mm/min. e célula de carga de 50kgf. Os dados obtidos foram submetidos à Análise de Variância e ao Teste de Tukey (5%). Pôde-se verificar que o cimento resinoso Rely X U100 promoveu os maiores valores de resistência adesiva, independentemente da presença ou não de perfuração radicular; e, ainda, que a presença de perfuração promoveu redução nos valores de resistência adesiva dos cimentos resinosos. Concluiu-se que a presença de perfuração radicular teve efeito direto sobre a resistência adesiva dos pinos de fibra de vidro e dos cimentos resinosos, promovendo redução nos valores de resistência adesiva à dentina intra-radicular

The objective of this paper is to present evaluation of the effect of root perforations on the adhesive resistance (or bond strength) of fiberglass pins – bonded by two resin cements – over the intra-root dentin.. Forty human and sound one--root teeth were subject to endodontic treatment and prepared for having fiberglass pins cemented to them (Exacto Mini, Angelus). The teeth were divided into four experimental groups (n=10), according to the root condition (with or without perforations) and to the resin cement: G1, no perforation, cement Rely X™ U100 (3M ESPE); G2: no perforation+ Panavia F2.0 (Kuraray); G3,: existing perforation + Rely X™ U100 (3M ESPE); G4: existing perforation+ Panavia F2.0 (Kuraray). Perforation was performed on the root surface with diamond tip and sealed with white mineral trioxide aggregate (MTA). The samples were sectioned and a push out test was performed (1mm/minute speed, 50 kgf). The obtained data was submitted to statistical analysis and Tukey test (5%).It was found that the resin cement Rely X U100 caused the highest levels of adhesive resistance regardless of the root perforation and also that perforation produced a reduction of the adhesive resistance of resin cement. The conclusion was that root perforation had a direct effect over the adhesive resistance of fiberglass pins and of resin cement and also produced a reduction in the values of adhesive resistance to the intra-root dentin

Promoção da saúde bucal em bebês: [revisão] / Promotion of oral health in babies: [review]

O objetivo deste trabalho é realizar uma revisão da literatura sobre promoção de saúde bucal em bebês, ressaltando-se a relevância do atendimento preventivo precoce, sendo esta uma estratégia fundamental na abordagem preventivo-promocional. Concluiu-se que: 1- A atenção precoce visa reduzir as chances de desenvolvimento de cárie em bebês e sua ambientação ao consultório odontológico, além da criação de hábitos de higiene bucal, tanto pelas crianças de pouca idade quanto pelos pais, principais responsáveis pela educação dos filhos. 2- A alta prevalência de cárie em bebês evidencia a necessidade de programas voltados para a promoção de saúde na primeira infância, visando manter a saúde bucal dessas crianças. 3- Uma vez que o sucesso da promoção de saúde bucal em bebês depende da conscientização dos pais sobre a importância da higiene bucal, este fato deve ser levado em consideração durante o planejamento e desenvolvimento de programas voltados a essa faixa etária.

This study is a literature review about promotion of oral health in babies and it discusses the importance of early preventive treatment. The conclusions are: 1- The early treatment aims to reduce the dental caries prevalencein babies and to make familiar the dentistry's office. It is important the creation of oral habits in children andin their parents. 2- The high prevalence of dental caries in babies shows the necessity of programs with health promotion in the first infancy. The aim is to keep the oral health of these children. 3- The success of the oral health promotion in babies depends on the awareness of the parents about the importance of oral hygiene. This fact must be considered during the planning and development of programs to this age.

Influence of topical acidulated phosphate fluoride on surface roughness of human enamel and different restorative materials / Influência da aplicação tópica de flúor fosfato acidulado sobre a rugosidade superficial do esmalte humano e de diferentes materiais restauradores

Purpose: The aim of this study was to assess the influence of topical acidulated phosphate fluoride on the surface roughness of both human enamel and different restorative materials. Methods: Resin-modified glass ionomer (Vitremer = V), microhybrid composite resin with fluoride (Tetric Ceram = T), and nanofiller composite resin without fluoride (Z350 = Z) were evaluated. Acidulated phosphate fluoride (APF, 1.23%) was applied to half of the specimens (groups VF, TF, ZF and EF). Ten intact human third molars were used to obtain enamel specimens (E). Six experimental groups (n=10) and two control groups (n=10) were formed. The mean surface roughness (Ra) of both the restorative materials and enamel, with and without fluoride, was evaluated with a profilometer. Data were analyzed with an ANOVA, Tukey's test, Student's t-test, and Dunn-Bonferroni test at the 5% significance level. Results: The mean values of surface roughness, in micrometers, were as follows: Z=0.60; TF=1.00; ZF=1.05; VF=1.18; T=2.10; V=2.70; E=16.99; and EF=21.19. Both E and EF presented significantly higher surface roughness than the other experimental groups. Conclusion: It was concluded that APF increased the surface roughness of enamel and decreased the surface roughness of both resin-modified glass-ionomer cement and microhybrid composite resin with fluoride. The surface roughness of the nanofiller composite resin was not modified by APF.

Objetivo: Este estudo avaliou a influência da aplicação tópica de flúor fosfato acidulado sobre a rugosidade do esmalte e de diferentes materiais restauradores. Metodologia: Amostras de cimento de ionômero de vidro modificado por resina (Vitremer - V), resina composta microhíbrida com flúor (Tetric Ceram - T) e resina nanopartículada sem flúor em sua composição (Z350 - Z) foram confeccionadas. Metade das amostras recebeu aplicação tópica de flúor fosfato acidulado a 1,23% (FFA) (grupos VF, TF, ZF e EF) e a outra metade não, totalizando 6 grupos experimentais (n=10). Dez terceiros molares humanos hígidos foram utilizados para confecção de amostras de esmalte (E), constituindo os grupos controles (n=10). A rugosidade média superficial (Ra) dos materiais restauradores e do esmalte, com e sem flúor, foi analisada pelo rugosímetro. Os dados foram submetidos à análise de variância, testes de Tukey, t-Student e de Dunn-Bonferroni (5 % de significância). Resultados: Os valores médios de rugosidade, em micrômetros, foram: Z=0,60; TF=1,00; ZF=1,05; VF=1,18; T=2,10; V=2,70; E=16,99 e EF=21,19. E e EF apresentaram Ra significativamente superior aos grupos experimentais. Conclusão: Concluiu-se que o FFA aumentou a rugosidade do esmalte, diminuiu a do cimento de ionômero de vidro e da resina microhíbrida com flúor e não alterou a rugosidade da resina nanoparticulada sem flúor.

Influência de diferentes dispositivos de microtração nos valores de resistência coesiva / Influence of different devices on microtensile strength

O objetivo deste estudo foi avaliar a influência de dispositivos de microtração sobre a resistência coesiva de blocos de resina acrílica. Vinte blocos de resina acrílica termopolimerizável (Onda-Cryl Clássico) foram confeccionados e distribuídos em 4 diferentes grupos experimentais (n=5) de acordo com o dispositivo de microtração empregado: G1: Paquímetro modificado; G2: Dispositivo de Andreatta Filho; G3: Dispositivo de Borges; G4: MT-jig. Os blocos foram seccionados em palitos de lmm2 e submetidos ao teste de microtração (EMIC DL 1000). Os dados foram avaliados pela Análise de Variância e pelo Teste de Tukey, a 5% de significância. Os menores valores de resistência mecânica foram obtidos com os dispositivos de Andreatta Filho (34,22 MPa) e de Borges (34,49 MPa), e os maiores valores com o Paquímetro modificado (49,44 MPa) e o MT-jig (48,40 MPa). Concluiu-se que os valores de resistência mecânica são influenciados pelos dispositivos de microtração utilizados e que não podem ser comparados entre si.

The aim of this study was to assess the influence of different devices on microlensile strength of acrylic resin blocks. Twenty thermo polyrnerized acrylic resin blocks (Onda-Cryl Clássico) were produced and divided into four experimental groups (n=5) according to microtensile device used: G I: Modified caliper; G2: Andreatta Filho’s device: G3: Borges' device: G4: MT-jig. Blocks were sectioned into sticks with a crosssection of I rnm2- and tested to failure in tension mode (EMIC DL 1000). The data were submitted to l-way analysis of variance (AOVA), followed by Tukey’s test (a=.05). The lowest mean microtensile strengths were obtained with Andreatta Filhos (34.22 MPa) and Borges' (34.49 MPa) devices. Paquimeter (49.44 MPa) and MT-jig (48.40 MPa) promoted the highest mean microtensile strengths, 1t was concluded that microtensile devices influence mechanical strength values.

Selected mechanical and physical properties and clinical application of a new low-shrinkage composite restoration.

Polymerization shrinkage is a major concern for bonded direct posterior restorations. Recently, a new low-shrinkage composite resin restorative material was developed. However, few data are available regarding clinical manipulation of this composite. Silorane-based composites represent an alternative to conventional methacrylate-based composites for direct posterior restorations. This article critically discusses the latest peer-reviewed reports related to polymerization, bonding, polishing, and color stability of silorane composite, focusing on its clinical application. Initial evaluation of this new category of composite material shows acceptable mechanical and physical properties.

Surface roughness of enamel and four resin composites.

PURPOSE: To assess surface roughness of resin composites submitted to different polishing techniques compared to intact human enamel. METHODS: Nanofilled (Filtek Supreme XT), microhybrid (Point 4), hybrid (Tetric Ceram), and microfilled (Durafill VS) resin composites were selected. Four polishing techniques were tested (TO: Mylar matrix - control; TI: aluminum oxide discs; T2: felt + diamond paste; T3: aluminum oxide discs + felt + diamond paste) with each resin composite. The specimens were assigned to 16 experimental groups and one control group (n = 4). Flat buccal surfaces of four human maxillary central incisors were used for the analysis of enamel roughness and served as control. The mean roughness was evaluated under atomic force microscopy in the contact mode. The obtained data were submitted to Student's t-test, ANOVA, and Tukey's Test, at 0.05 level of significance. RESULTS: The roughness of enamel was 46.6 +/- 10.7 nm. The smoothest surface was obtained for the Mylar matrix with nanofiller (23.6 +/- 3.0 nm), microhybrid (12.8 +/- 1.4 nm), or hybrid resin (15.2 +/- 1.9 nm). Microfilled resin showed the lowest roughness with aluminum oxide discs (43.0 +/- 5.2 nm). Diamond paste increased the roughness of composites, whereas aluminum oxide discs yielded the smoothest surfaces.

Microtensile bond strengths and scanning electron microscopic evaluation of self-adhesive and self-etch resin cements to intact and etched enamel.

STATEMENT OF PROBLEM: The longevity of indirect adhesively cemented restorations is directly related to the bond quality of resin cements to dental tissues. Bonding to cervical enamel can generate significantly lower bond strengths than bonding to other enamel areas. The effect of enamel pretreatment on bond strengths of self-etch and self-adhesive resin cements to cervical enamel remains undetermined. PURPOSE: The purpose of this study was to evaluate cervical enamel bond strengths of self-adhesive, self-etch resin cements according to acid pretreatment, using a total-etch resin cement as the control. MATERIAL AND METHODS: The proximal surfaces of 20 extracted molars were sectioned to obtain 40 enamel rectangles with an area of 8.0 x 4.0 mm. The rectangular enamel specimens were assigned to 1 of 5 enamel experimental groups: intact enamel + RelyX Unicem (UN), etched enamel + UN (UNpa), intact enamel + Multilink (ML), etched enamel + ML (MLpa), and the total-etch-based RelyX ARC (RX; control group). Standard 8.0 x 4.0 x 6.0-mm composite resin blocks (Z250) were cemented to all specimens. The bonded enamel surfaces were sectioned into sticks with a cross-section of 0.8 +/-0.2 mm(2) and tested to failure in tension mode at a crosshead speed of 1 mm/min. The data were submitted to 1-way analysis of variance (ANOVA), followed by Tukey's HSD post hoc test (alpha=.05). Additionally, the enamel etching pattern was investigated for all experimental groups using field-emission electron microscopy. RESULTS: Statistical analysis showed significant differences among different resin cements (P<.001) and phosphoric acid etching (P<.002). The highest mean (SD) bond strengths were obtained with UNpa (32.92 (4.23)) > RX (19.40 (9.47)). Acid etching of enamel before application of self-etch resin cement did not improve the mean bond strengths (SD) for self-etch resin cement [ML (5.38 (5.97)); MLpa (5.23 (1.1))]. Self-adhesive and self-etch resin cements yielded the lowest significant mean bond strengths (SD) when applied on intact enamel: UN (13.03 (2.82)) > ML (5.38 (5.97)). Scanning electron microscopy showed a consistent etching pattern for phosphoric acid-etched specimens. Self-etch and self-adhesive resin cements applied directly to intact enamel showed inconsistent areas of etching. CONCLUSIONS: Etching cervical enamel surfaces resulted in significantly higher bond strengths for self-adhesive resin cement. For self-etch resin cement, etching did not improve bond strength.

Effect of dental finishing instruments on the surface roughness of composite resins as elucidated by atomic force microscopy.

Roughness increases significantly after finishing procedures. The aim of this study was to assess by the atomic force microscope (AFM) the effect of finishing instruments on the surface roughness of composite resins. A nanofiller composite resin (Filtek Supreme, 3M-F) and a microhybrid composite resin (Point 4, Kerr-P) were selected. The finishing procedures were done with a 30-blade carbide bur (C) and a 30-microm finishing diamond bur (D). Standardized specimens were produced and divided into six experimental groups (n=4) according to (1) composite resin, (2) absence of finishing (Mylar matrix-M), and (3) finishing instrument (FM, PM, FC, FD, PC, PD). The mean surface roughness was evaluated by AFM in the contact mode. FM and PM groups were assessed statistically by the Student's T test, and FC, FD, PC, PD groups were submitted to variance analysis (ANOVA), both at 5% significance. The mean surface roughness values, in nanometers, were FM, 23.63 (b); FC, 283.88 (c); FD, 510.55 (d); PM, 12.52 (a); PC, 343.98 (c); PD, 531.64 (d). Microhybrid composite displayed less roughness than nanofiller composite in the absence of finishing procedures. The 30-blade carbide bur produced less roughness compared to the extra fine diamond bur.