The effect of tooth bleaching using violet LED (405-410 nm) on the properties of resin-based composites.

BACKGROUND: The objective of this study was to evaluate the effect of bleaching techniques, including or not the use of violet light (405-410 nm), on resin-based composites' color, surface roughness, nanohardness, and elastic modulus. METHODS: Ninety-six disk-shaped specimens (12 mm x 2 mm; n = 12) were prepared using Filtek Z350 XT (Z350) and IPS Empress Direct (ED) resin-based composites. After 24 h, specimens were stained in red wine for 28 days. After staining, specimens were divided into four experimental groups: 40 % Hydrogen Peroxide (HP); Violet Light (VL); 40 % Hydrogen Peroxide associated with Violet Light (HP+VL), and a control group - no treatment (NT). Specimens were evaluated at six experimental times: initial (24 h after light curing); after staining and after the 1st, 2nd, 3rd, and 4th bleaching sessions regarding the color change (ΔE00, L*, a*, b*, and WID); roughness (Ra), nanohardness and elastic modulus (GPa). Two-way analysis of variance for repeated measures was performed (α=0.05 %). RESULTS: There was a statistically significant difference between staining and the 1st bleaching session for all ED groups (p<0.05). After the last bleaching session, there were no differences between the experimental and the control groups of both resin-based composites. Bleaching using violet light did not change the roughness, nanohardness and elastic modulus of the tested resin-based composites (p>0.05). CONCLUSIONS: Although hydrogen peroxide and violet light remove pigments from resin-based composites without affecting their surface roughness, nanohardness, and elastic modulus, the color change was similar to the one obtained by immersion in distilled water.

Comparison between a bulk-fill resin-based composite and three luting materials on the cementation of fiberglass-reinforced posts.

Objectives: This study verified the possibility of cementing fiberglass-reinforced posts using a flowable bulk-fill composite (BF), comparing its push-out bond strength and microhardness with these properties of 3 luting materials. Materials and Methods: Sixty endodontically treated bovine roots were used. Posts were cemented using conventional dual-cured cement (CC); self-adhesive cement (SA); dual-cured composite (RC); and BF. Push-out bond strength (n = 10) and microhardness (n = 5) tests were performed after 1 week and 4 months of storage. Two-way repeated measures analysis of variance (ANOVA), 1-way ANOVA, t-test, and Tukey post-hoc tests were applied for the push-out bond strength and microhardness results; and Pearson correlation test was applied to verify the correlation between push-out bond strength and microhardness results (α = 0.05). Results: BF presented higher push-out bond strength than CC and SA in the cervical third before aging (p < 0.01). No differences were found between push-out bond strength before and after aging for all the luting materials (p = 0.84). Regarding hardness, only SA presented higher values measured before than after aging (p < 0.01). RC and BF did not present 80% of the maximum hardness at the apical regions. A strong positive correlation was found between the luting materials' push-out bond strength and microhardness (p < 0.01, R2 = 0.7912). Conclusions: The BF presented comparable or higher push-out bond strength and microhardness than the luting materials, which indicates that it could be used for cementing resin posts in situations where adequate light curing is possible.

Repair Bond Strength of Aged Composite Resins Using Different Surface Treatment Protocols.

This study evaluated shear bond strength (SBS) of thermally aged composite resins repaired using different surface protocols. Four-hundred composite resin samples were made using the following materials (100 samples per material): Filtek Z350XT (FXT); Spectra Smart (SSM); IPS Empress Direct (EDI); and Forma (FOR). Each group's samples were then divided into 10 groups (n = 10 samples per group): G1: no surface treatment; G2: phosphoric acid-etching + universal-adhesive (PU); G3: surface roughening + PU (RPU); G4: RPU + silane (RPSU); G5: surface roughening + hydrofluoric acid-etching + universal adhesive (RHU); G6: RHU + silane (RHSU); G7: dry sandblast + PU (DsPU); G8: DsPU + silane (DsPSU); G9: wet sandblast + PU (WsPU); and G10: WsPU + silane (WsPSU). G1 was freshly repaired, and G2 to G10 were thermally aged before repair. Specimens were tested for SBS, and the failure type was observed with a magnifying loupe. Representative images were obtained using a scanning electronic microscope. Data were analyzed by two-way analysis of variance and Tukey post hoc tests (P = .05). Differences were detected among different surface treatments and among different composite resins with equal surface treatments (P < .05). SBS means ranged from 10.48 (FOR:G2) to 20.70 (FXT:G7). The highest SBS values were seen in G7 to G10 (P > .05), while lowest values were generally observed for G2. G1 showed higher results compared to G2 (P < .05), except for EDI (P > .05). Most failures corresponded with cohesive type. In general, thermally aged composite resin presented a decreased repair bond strength potential when no additional surface treatment was applied. Sandblasting improved the SBS of repaired aged composite resins.

Role of non-carious cervical lesions multicausality in the behavior of respective restorations.

OBJECTIVES: To evaluate biocorrosion and eccentric occlusal loading interplay in marginal quality of cervical restorations. METHODS: Cervical wedge-shaped cavities were prepared in extracted premolars and restored with a composite. Premolars underwent either an erosive challenge (E: 1% citric acid/10 min), eccentric occlusal loading (EOL: 150 N/2.5 Hz/106 cycles), E before EOL (E + EOL), E intermediate to EOL (EOL/E/EOL), E after EOL (EOL + E), or no E or EOL (C: control). Marginal quality was analyzed based on a series of Optical Coherence Tomography images. Each of the margins was assigned a gap score (0, 1, 2, or 3) and measurement (µm). For each margin, scores data were analyzed with Kruskall Wallis and Dunn tests, and µm data, with Kruskall Wallis. Overall and for each group, the different margins were compared using Wilcoxon signed-rank test, and the correlation between scores and µm, Spearman's correlation coefficient (α = 0.05). RESULTS: E and EOL, even if associated, did not influence enamel marginal quality. EOL/E/EOL impaired dentin/cementum marginal quality only in the case of scores and compared to E. E + EOL, EOL + E or EOL and even C, without differences between each other, did not influence results differently from E or EOL/E/EOL. Margins in dentin/cementum always showed lengthier gaps. Except for C, E and EOL + E cervical margin, there was a strong positive correlation between scores and µm. CONCLUSIONS: Eccentric occlusal loading and/or biocorrosion cannot be assumed as causes of marginal failure of cervical restorations in wedge-shaped cavities. A relevant concern may still be the establishment of adhesive interfaces in dentin/cementum. CLINICAL SIGNIFICANCE: Although non-carious cervical lesions are strongly being recognized multifactorial and their respective restorations not always behave as expected, biocorrosion and eccentric occlusal loading interplay cannot serve as an explanation for marginal gaps they often present.

Mechanical Properties of the Mandible in Postmenopausal Women Under Aledronate Treatment.

AIMS: This study evaluated the mechanical properties of mandibular bone tissue retrieved from postmenopausal women under alendronate treatment. METHODS: Twenty postmenopausal women were divided into two groups: healthy postmenopausal subjects (control group) and osteoporotic subjects treated with alendronate (alendronate group). Mandibular bone samples were retrieved with a trephine bur at the time of dental implant placement and fixed in 4% formalin. Samples were processed for hard tissue histology, and the bone surface was analyzed for nanohardness measurement. Nanohardness and elastic modulus were evaluated by using a Berkovich tip with elastic modulus of 1.016x106 MPa, Poisson coefficient of 0.3, and a load of 100 mN. Each cycle was configured with a load time of 18 seconds (speed of 1 mN/second), the discharge time of 18 seconds, and a rest time of 5 seconds during indentation at a depth of 10 µm. RESULTS: The control group presented the highest values for nanohardness and elastic modulus (p less than 0.05) in relation to the osteoporotic subjects. CONCLUSIONS: Within the limitations of the study, it can be concluded that treatment with alendronate negatively influenced the mechanical properties of mandibular bone in postmenopausal women by reducing bone nanohardness and elastic modulus.

Effect of light curing units on the polymerization of bulk fill resin-based composites.

OBJECTIVE: To determine the potential effect of four different light curing units (LCUs) on the curing profile of two bulk fill resin-based composites (RBCs). METHODS: Four LCUs (Bluephase 20i, Celalux 3, Elipar DeepCure-S and Valo Grand) were used to light cure two RBCs (Filtek Bulk Fill Posterior Restorative and Tetric EvoCeram Bulk Fill). The effective tip diameter, radiant power, radiant emittance, emission spectrum and light beam profile of the LCUs were measured. Knoop microhardness was measured at the top and bottom surfaces of RBC specimens that were 12-mm in diameter and 4-mm deep (n=5). The distribution of the spectral radiant power that was delivered to the surface of the specimen and the light transmission through the 4-mm thick specimens was measured using an integrating sphere. Two-way ANOVA and Tukey tests (α=0.05) were applied. RESULTS: The Valo Grand produced the most homogeneous microhardness across the surfaces of the RBCs (p>0.05). When the Celalux 3, Bluephase 20i and Elipar DeepCure-S lights were used, the center of the specimens achieved greater hardness values compared to their outer regions (p<0.05). Approximately 10% of the radiant power delivered to the top reached the bottom of the specimen, although almost no violet light passed through 4mm of either RBC. A positive correlation was observed between the radiant exposure and microhardness. SIGNIFICANCE: The characteristics of the LCUs influenced the photoactivation of the RBCs. The use of a wide tip with a homogeneous light distribution is preferred when light curing RBCs using a bulk curing technique.

Light output from six battery operated dental curing lights.

Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p<0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p<0.01). The Bluephase G2 and Translux 2Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs.

Ability of four dental radiometers to measure the light output from nine curing lights.

OBJECTIVES: To evaluate the accuracy of four dental radiometers when measuring the output from nine light curing units (LCUs). METHODS: The light output from nine light-emitting diode LCUs was measured with a laboratory-grade power meter (PowerMax-Pro 150 HD) and four dental radiometers (Bluephase Meter II, SDI LED Radiometer, Kerr LED Radiometer, and LEDEX CM4000). Ten measurements were made of each LCU with each radiometer. Analysis of variance (ANOVA) followed by Tukey tests (α=0.05) were used to determine if there was a difference between the calculated irradiance values from the power meter and those from the radiometers. Where applicable, the LCUs were ranked according to their power and irradiance values. The emission spectra from the LCUs was measured using an integrating sphere attached to a fiber-optic spectrometer (N=10). The beam profile of the LCUs was measured with a beam profiler camera. RESULTS: Of the dental radiometers, only the Bluephase Meter II could measure power. ANOVA showed no significant difference between power values measured with the laboratory-grade meter and the Bluephase Meter II (p=0.527). The difference between the mean irradiance reported by the various radiometers for the same LCU was up to 479mW/cm2. The ranking of the power values obtained using the laboratory-grade meter was the same for the Bluephase Meter II. CONCLUSION: When compared to the calculated irradiance values from the laboratory-grade power meter, the Bluephase Meter II provided the most accurate data. CLINICAL SIGNIFICANCE: Considering the great variation between the irradiance values provided by radiometers and their overall inaccuracy when compared to a laboratory-grade meter, dentists should not place too much faith in the absolute irradiance value. However, hand-held radiometers can be used to monitor changes in the light output of LCUs over time.

Five second photoactivation? A microhardness and marginal adaptation in vitro study in composite resin restorations.

INTRODUCTION: Studies defining the characteristics of light curing units and photoactivation methods are necessary to allow the correct choices to be made in daily practice. This study aimed to determine whether different photoactivation protocols for composite resins [periodic level shifting (PLS) - 5 second and soft-start] are able to maintain or enhance the mechanical properties and marginal adaptation of restorations. METHODS: Restorations were placed in bovine teeth using the following photoactivation methods: continuous light for 20 seconds (control group); PLS technology (PLS - 5 second group); and continuous light and a light guide tip distance of 6 mm after which the tip was placed at the surface of the restoration (soft-start group). The teeth were transversely sectioned in the incisal-cervical direction. Thirty halves were randomly selected for Knoop microhardness testing (n = 10). The other 30 halves were subjected to scanning electron microscopy analysis. The images obtained were measured to identify the highest marginal gap, and statistical tests for variance analysis were conducted. RESULTS: Microhardness tests showed no statistically significant difference between the photoactivation methods analysed (P ≥ 0.01). The tests showed a difference among depths (P < 0.01), with the deeper layers being the hardest. In analysing marginal adaptation, no significant difference was identified between the higher marginal gap values in the continuous (mean = 10.36) and PLS - 5 second (mean = 10.62) groups, and the soft-start group (mean = 5.83) presented the lowest values (P < 0.01). CONCLUSIONS: The PLS - 5 second and soft-start protocols did not alter the hardness of the restorations. Moreover, the PLS - 5 second protocol did not alter the marginal adaptation, whereas the soft-start protocol improved marginal adaptation.

The effect of desensitizing dentifrices on dentin wear and tubule occlusion.

PURPOSE: To evaluate the effect of desensitizing dentifrices on dentin erosive wear, using a 5-day erosion-abrasion-remineralization cycling model. The effect of the dentifrices on dentin's tubule occlusion was also investigated. METHODS: 30 samples of root dentin were randomly divided into three groups (n = 10): (1) Colgate Total 12 Clean Mint (control, 1,450 ppm F); (2) Colgate Sensitive Pro-Relief (1,450 ppm F, Pro-Argin); and (3) Sensodyne Repair&Protect (1,450 ppm F, Novamin). Erosion was performed with a cola drink, for 5 minutes, 4x/day. Toothbrushing with the slurry dentifrices (1:2) was performed 2x/day, with electric toothbrushes, using standard pressure for 15 seconds. Surface loss (SL) was determined with optical profilometry at baseline and after the first, third and fifth days of cycling. Before treatment and in the end of the cycling, the amount of opened dentin tubules per area was evaluated in three randomly selected specimens from each group, by environmental scanning electron microscopy. The relative dentin abrasitivity (RDA) of the dentifrices was also measured. Data were statistically analyzed (α = 0.05). RESULTS: All the dentifrices showed a progressive increase in SL over time. However, no significant differences in SL among the dentifrices were observed at any time studied. Sensodyne Repair&Protect significantly reduced the number of opened dentin tubules when compared to the other groups. Colgate Total 12 Clean Mint showed the highest RDA, followed by Sensodyne Repair&Protect and then by Colgate Sensitive Pro-Relief. The desensitizing dentifrices tested produced a similar rate of erosive dentin wear to the conventional dentifrice; however, only Sensodyne Repair&Protect was able to promote tubule occlusion.

Influence of Curing Units and Indirect Restorative Materials on the Hardness of Two Dual-curing Resin Cements Evaluated by the Nanoindentation Test.

PURPOSE: To evaluate the hardness of a dual-curing self-adhesive resin cement (RelyX U200) and a conventional dual-curing resin cement (RelyX ARC) cured with different light curing units of different wavelengths (Elipar Freelight 2 LED [430 to 480 nm, conventional], Bluephase LED [380 to 515 nm, polywave], AccuCure 3000 Laser [488 nm]) by means of the nanoindentation test. MATERIALS AND METHODS: Bovine incisors were cleaned and then sectioned at the cementoenamel junction to remove the crown. After embedding in acrylic, dentin surfaces of the specimens were exposed and ground flat to standardize the surfaces. To simulate clinically placing indirect restorations, ceramic (IPS e.maxPress/Ivoclar Vivadent) or indirect composite resin (SR Adoro/Ivoclar Vivadent) slabs were cemented on dentin surfaces. The specimens were sectioned longitudinally at low speed under constant irrigation and then polished. In the positive control group, the cement was light cured without the interposition of indirect restorative material; in the negative control group, after the indirect restorative material was cemented, no light curing was performed, allowing only chemical polymerization of the cement. All specimens were stored in distilled water at 37°C for 7 days. Nanoindentadion hardness of the cement layer was measured under a 100-mN load. Data were statistically analyzed using ANOVA and Tukey's test (p < 0.05). RESULTS: Although the self-adhesive cement is technically simple, conventional cement showed the best polymerization performance. The polywave LED technology did not differ significantly from other light-curing units. The hardness of the resin cements evaluated was negatively influenced by the interposition of an indirect restorative material; only the LEDs were able to maintain the same degree of cement polymerization when an indirect restorative material was used. CONCLUSION: The photoactivation step is required during the cementation of indirect restorations to ensure adequate polymerization of dual-curing resin cements.

Estudo da atual utilização da TCFC pelos Cirurgiões-Dentistas nas diversas especialidades / Study of current use of Cone-Beam CT by dental surgeons in the various specialties

Objetivo: Determinar, dentre os profissionais de Odontologia, o grau de formação e informação quanto ao uso da tomografia computadorizada tipo cone-beam, assim como quantificar e discriminar o uso desta ferramenta diagnóstica no cotidiano das especialidades. Materiais e métodos: Profissionais cursando algum tipo de especialização tiveram que responder a um questionário de respostas certo/errado, que continha parâmetros sobre as indicações do uso da tomografia computadorizada na Odontologia, assim como perguntas que permitiram o levantamento de informações acerca desta ferramenta diagnóstica no tocante a influência do custo do procedimento, necessidade de treinamento específico para interpretação e necessidade de investimento por parte do profissional clínico. Resultados: Pudemos observar que a indicação da técnica não está totalmente esclarecida para muitos Cirurgiões-Dentistas. A porcentagem de desconhecimento foi significativa (27%), por se tratar de radiação ionizante, que pode causar riscos estocásticos e deletérios. Pudemos observar em nossos resultados que existe um embasamento geral da técnica, pois à medida que especialistas de uma certa área acertaram questões correspondentes a outras especialidades, notamos a ocorrência de equívocos de conceitos quando eram questionados sobre o protocolo de uso em sua própria área de conhecimento. Conclusão: A divulgação dos dados obtidos será de grande valia para o clínico geral, bem como para os especialistas, no intuito de reduzir a dose de exposição desnecessária quando da indicação da técnica. A necessidade de aprimorar o conhecimento será sempre necessária, para que não tenhamos apenas o conhecimento geral, mas o específico para a área de atuação de cada um.

Objective: To determine, among dental professionals, the degree of training and information regarding the use of CBCT, as well as to quantify and discriminate the use of this diagnostic tool in specialties daily basis. Materials and methods: Professionals attending specialization courses had to answer a right/wrong answers questionnaire containing parameters of indications for the use of computed tomography in dentistry. Beyond that, they had to answer questions that allowed the collection of information about this diagnostic tool regarding the influence of the cost of the procedure, the need for specific training in the interpretation and need for investment by the clinical professional. Results: We observed that the technique is not entirely clear for many dentists. The percentage of unawareness was significant (27%) considering it is about an ionizing radiation, which can cause deleterious and stochastic risks. We observed in our results that there is a general grounding of the technique, because on the one hand experts of a determined area showed a certain knowledge of other specialties, on the other hand we verified there were misunderstandings of concepts when questioned about the protocol used in their own area of knowledge. Conclusion: The release of the data obtained will be of great value to the general practitioner as well as to specialists in order to reduce the amount of unnecessary exposure in the indication of the technique. Improve knowledge will always be necessary so we will not only have general knowledge, but the specific one to the area of each dentistry professional.

A nanodureza e o módulo de elasticidade versus resistência de união da resina com a dentina / The nanohardness and elastic modulus versus bond strength of resin to dentin

Objetivo: Avaliar a nanodureza (Nn) e o módulo de elasticidade (ME) da região de adesão quando utilizados diferentes sistemas adesivos e correlacionar com a resistência adesiva (RA) à dentina. Método: Foram medidos a nanodureza e o módulo de elasticidade da resina composta junto à área de união, da camada de adesivo (Ad), da camada híbrida (Ch), e da dentina adjacente utilizando testes de nanoendentação. Quarenta molares (n=10) foram preparados de modo a obterem-se superfícies planas em dentina, sobre as quais os sistemas adesivos foram aplicados (Adper Scotchbond Multiuso, Adper Single Bond 2, Adper SE Plus e Clearfil SE Bond). Sobre essas superfícies foi inserida a resina composta. Os dentes restaurados foram seccionados para obterem-se corpos-de-prova com área aderida de 1mm2. Um palito de cada dente foi selecionado para análise da nanodureza e do módulo de elasticidade da interface adesiva. Os demais tiveram a resistência de união testada através do teste de microtração. Resultados: O teste ANOVA detectou diferença estatística entre todos os grupos, exceto para a variável nanodureza da camada híbrida. O teste de correlação de Pearson detectou significância para o módulo de elasticidade. Conclusões: Pôde-se concluir que as propriedades mecânicas (resistência adesiva, módulo de elasticidade e nanodureza do sistema adesivo e da camada híbrida) variam dependendo do sistema adesivo. Quanto maior o módulo de elasticidade da camada híbrida de um sistema adesivo maior é sua resistência adesiva e menor o módulo de elasticidade da camada de adesivo. Pôde observar que não houve correlação entre nanodureza e a resistência adesiva.

To evaluate the nanohardness (Nn) and the modulus of elasticity (ME) in the region of adhesion when used different adhesive systems and correlate with the bond strength to dentin (RA). We measured the nanohardness and the modulus of elasticity of the resin composed with the area of bond of the adhesive layer (Ad), hybrid layer (Ch) and adjacent dentin using nanodentition tests. Forty molars (n = 10) were prepared in order to obtain flat dentin surfaces on which the adhesive systems were applied (Adper Scotchbond Multipurpose, Single Bond 2, Adper SE Plus and Clearfil SE Bond). On these surfaces was inserted a composite resin. The restored teeth were sectioned to obtain body-of-proof with adhered area of 1mm2. A stick of each teeth was selected for the nanohardness analysis and the modulus of elasticity of the adhesive interface. The others had the bond strength tested using the microtensile test. The ANOVA detected statistical difference between all groups, except for the variable nanohardness of the hybrid layer. The Pearson’s correlation test found significance for the modulus of elasticity. It was concluded that the mechanical properties (bond strength, the modulus of elasticity and nanohardness of the adhesive system and the hybrid layer) vary depending on the adhesive system. The higher the modulus of elasticity of the hybrid layer of an adhesive system a greater adhesive strength will be and lower the modulus of elasticity of the adhesive layer. It can be observed that there was no correlation between nanohardness and bond strength.

Diferentes padrões tubulares dentinários de molares decíduos interferem na força de união de adesivos baseados no condicionamento ácido total e autocondicionantes? / Do different dentin tubular patterns of primary molars affect the bond strength of total-etching and self-etching adhesive systems?

Avaliar a resistência de união, pelo ensaio de tração, de sistemas adesivos autocondicionantes e baseados no condicionamento ácido total em diferentes superfícies dentinárias de molares decíduos e analisar a interface de união adesiva. Metodologia: Neste estudo in vitro, amostras de dentina de 35 a 65% de distância pulpar (dentina intermediária) foram obtidas do terço médio das faces vestibular e lingual/palatina de primeiros e segundos molares decíduos. As superfícies dentinárias foram polidas com lixas de carboneto de silício de granulação 400 e 600. Três sistemas adesivos (Prime & Bond NT, AdheSE e Clearfil SE Bond) foram empregados nas amostras dos primeiros e segundos molares (n=15); corpos de prova foram confeccionados em resina composta com uma área de adesão de 2 mm de diâmetro. Após 24 horas de armazenagem em água destilada a 37ºC, fez-se o ensaio de tração. Para a análise da interface de união adesiva entre sistema adesivo e dentina usando microscopia eletrônica, as amostras foram preparadas com os mesmos três sistemas adesivos (n=5). Resultados: Não foram observadas diferenças estatisticamente significantes nos valores de adesão entre primeiros e segundos molares (ANOVA; p>0,05). Os seguintes valores médios de adesão em MPa foram obtidos: 15,65±3,70 (Prime & Bond NT), 19,47±7,09 (AdheSE) e 17,14±5,35 (Clearfil SE Bond). Não foram observadas diferenças estatisticamente significantes entre os adesivos autocondicionantes. A formação de camada híbrida e tags foi observada em todos os grupos. Conclusões: Os sistemas adesivos contemporâneos apresentaram comportamentos similares em ambos os tipos de superfícies tubulares dentinárias dos molares decíduos. Estudos de seguimento são necessários para o acompanhamento do desempenho clínico desses materiais...

Aims: To evaluate the tensile bond strength of self-etching and total-etching adhesive systems to the different dentin surfaces of primary molars and to analyze the resin-dentin interface. Methodology: In this in vitro study, dentin samples 35 to 65% distant from the pulp (intermediate dentin) were obtained from buccal and lingual surfaces at the middle third of the crown of first and second primary molars. Dentin surfaces were prepared with 400 and 600-grit silicon carbide paper. Three adhesive systems (Prime & Bond NT, AdheSE and Clearfil SE Bond) were tested on the first and second primary molar surfaces (n=15); inverted truncated cones of resin composite with a 2.0 mm bonding diameter were built. After 24 hour storage in distilled water at 37°C, the specimens were submitted to the tensile bond strength test. To analyze the resin-dentin interface under scanning electron microscopy, samples were prepared with the same three adhesive systems (n=5). Results: No differences between first and second primary molar dentin substrates could be observed in mean bond strength values (ANOVA; p>0.05). The following mean bond strength values (MPa) were obtained: 15.65±3.70 (Prime & Bond NT), 19.47±7.09 (AdheSE) and 17.14 ±5.35 (Clearfil SE Bond). There were no statistically significant differences between the self-etching adhesive systems. The presence of hybrid a layer and tags were observed in all groups. Conclusions: Contemporary adhesive systems showed similar behaviors on both dentin tubular surfaces of primary molars. Follow-up studies of the clinical performance of these materials are needed...

Influência do método de fotoativação na dureza de uma resina composta / Influence of the photoactivation method on the hardness of a composite resin

Objetivo: avaliar a dureza de uma resina composta fotoativada com dois métodos diferentes, contínuo e soft-start, por meio da variação da distância entre a ponta fotoativadora e a resina composta (7 mm e 0 mm). Materiais e métodos: Foram confeccionados 20 corpos-de-prova, nos quais a superfície irradiada e a oposta foram analisadas, totalizando 40 superfícies divididas em quatro grupos (n = 10): Grupo 1, método contínuo superfície irradiada; Grupo 2, método contínuo superfície oposta; Grupo 3, método soft-start superfície irradiada; Grupo 4, método soft-start superfície oposta. Os corpos-de-prova foram confeccionados com o auxílio de matrizes pretas de polipropileno, com 4 mm de diâmetro e 2 mm de espessura, utilizando a resina composta Z350 (3M ESPE) na cor AO3 e o fotoativador Elipar Freelight 2 (3M ESPE). Os corpos-de-prova foram submetidos ao teste de microdureza Vickers, no microdurômetro HMV- 2000 (Shimadzu). Foram realizados cinco entalhes por superfície, com carga de 50 gf por 45 segundos. Para a análise estatística, foram realizados os testes de ANOVA e Tukey. Resultados: Não foi encontrada diferença estatisticamente signifi cante entre os métodos avaliados nas superfícies irradiadas. Entretanto, nas superfícies opostas, houve diferença entre os protocolos, sendo que o soft-start obteve menores valores de dureza. Quando comparadas as diferentes profundidades, houve redução nos valores de dureza para ambos os métodos de fotoativação, de forma que a porcentagem de dureza máxima de 80% não foi atingida na superfície oposta à irradiada. Relevância: O cirurgião-dentista, em sua prátic clínica, deve atentar para o método de fotoativação de suas restaurações, visto que este pode prejudicar a qualidade da polimerização de resinas compostas, especialmente na profundidade de 2 mm em resinas opaca.

Objective: to evaluate the hardness of a composite resin polymerized with two different methods, continuous and soft-start, by varying the distance between the activator tip and the composite resin (7 mm and 0 mm). Materials and Methods: Twenty test specimens were fabricated, in which the irradiated and the opposite surfaces were analyzed, totaling 40 surfaces divided into 4 groups (n = 10): Group 1, continuous method + irradiated surface; Group 2, continuous method + opposite surface; Group 3, soft-start method + irradiated surface; Group 4, soft-start method + opposite surface. The test specimens were prepared using black polypropylene matrices, with a diameter of 4 mm and thickness of 2 mm, Z350 composite resin (3M ESPE), shade AO3, and the Elipar Freelight 2 curing unit (3M ESPE). The test specimens were subjected to nthe Vickers hardness test in an HMV-2000 microhardness tester (Shimadzu). Five indentations were made per surface with a load of 50 gf for 45 seconds. The ANOVA and Tukey tests were used for the statistical analysis. Results: No statistically signifi cant difference between the evaluated methods was found in the irradiated surfaces; however, in the opposite surfaces, there were differences between protocols, in that the soft-start protocol achieved the lowest hardness values. When comparing the different depths, there was a reduction in hardness values for both activation methods, so that the maximum hardness percentage of 80% was not achieved in the opposite surface. Relevance: The dentist should be knowledgeable of the photoactivation method applied to his/her restorations, since it may reduce the polymerization quality, especially in depths of 2 mm when using opaque resins.

Effect of CO2 laser on root caries inhibition around composite restorations: an in vitro study.

The aim of the present study was to investigate the in vitro effect of CO2 laser on the inhibition of root surface demineralization around composite resin restorations. For this purpose, 30 blocks obtained from human molar roots were divided into three groups: group 1 (negative control), cavity prepared with cylindrical diamond bur + acid etching + adhesive + composite resin restoration; group 2, cavity prepared with cylindrical diamond bur + CO2 laser (5.0 J/cm(2)) + acid etching + adhesive + composite resin; and group 3, cavity prepared with cylindrical diamond bur + CO2 laser (6.0 J/cm(2)) + acid etching + adhesive + composite resin. After this procedure, the blocks were submitted to thermal and pH cycling. Root surface demineralization around the restorations was measured by microhardness analysis. The hardness results of the longitudinally sectioned root surface were converted into percentage of mineral volume, which was used to calculate the mineral loss delta Z (ΔZ). The percentage of mineral volume, ΔZ, and the percentage of demineralization inhibition of the groups were statistically analyzed by using analysis of variance and Tukey-Kramer test. The percentage of mineral volume was higher in the irradiated groups up to 80 µm deep. The ΔZ was significantly lower in the irradiated groups than in the control group. The percentage of reduction in demineralization ranged from 19.73 to 29.21 in position 1 (50 µm), and from 24.76 to 26.73 in position 2 (100 µm), when using 6 and 5 J/cm(2), respectively. The CO2 laser was effective in inhibiting root demineralization around composite resin restorations.

Influência do óxido de alumínio na colagem dos bráquetes linguais / The influence of the aluminun oxide on lingual brackets bonding

A descolagem acidental do bráquete é uma severa complicação no decorrer do tratamento ortodôntico, especialmente quando o tratamento é feito com bráquetes linguais. A força de adesão entre o bráquete e o dente é um importante requisito para o sucesso da Ortodontia Lingual na prática diária do consultório. O presente estudo analisou a influência do jateamento do óxido de alumínio na superfície lingual dos dentes antes do condicionamento do esmalte na colagem indireta do aparelho lingual. A força de cisalhamento foi medida 24 horas após a colagem dos bráquetes. Os dentes foram divididos em quatro grupos: G1 - 10 pré-molares com bráquetes da marca American Orthodontics com condicionamento de ácido ortofosfórico a 37%; G2 - 10 pré-molares com bráquetes da marca American Orthodontics com aplicação do jato de óxido de alumínio e ácido ortofosfórico a 37% no esmalte; G3 - 10 pré-molares com bráquetes da marca Ormco com condicionamento de ácido ortofosfórico a 37% e G4 - 10 pré-molares com bráquetes da marca Ormco com aplicação do jato de óxido de alumínio e ácido ortofosfórico a 37% no esmalte. Avaliou-se a resistência ao cisalhamento e observou-se que não ocorreu diferença estatisticamente significante entre os grupos quanto aos diferentes modos de preparo de esmalte. Com relação às marcas comerciais, os bráquetes da American Orthodontics apresentaram resistência à descolagem maior do que os bráquetes da marca Ormco. Concluindo, a resistência à descolagem dos bráquetes não foi aumentada com a aplicação prévia do jato de óxido de alumínio no esmalte hígido, nas duas marcas comerciais de bráquetes.

Accidental bracket debonding is a severe complication throughout orthodontic treatment, especially when using lingual brackets. The bond strength between the bracket and the tooth is an important requirement for the success of Lingual Orthodontics. This study has analyzed the influence of aluminum oxide blasting on the lingual surface of the teeth, before conditioning of the enamel, over indirect bonding of the lingual brace. Shear strength was measured 24 hours after brackets bonding. Teeth were divided into four groups: G1 - 10 premolar teeth with American Orthodontics brackets and 37% orthophosphoric acid conditioning; G2 - 10 premolar teeth with American Orthodontics brackets and application of aluminum oxide and 37% orthophosphoric acid blasting on the enamel; G3 - 10 premolar teeth with Ormco brackets and 37% orthophosphoric acid conditioning; G4 - 10 premolar teeth with Ormco brackets, application of aluminum oxide and 37% orthophosphoric acid blasting on the enamel. When evaluating the shear resistance through mechanical assay, it was not observed statistically significant difference between the groups regarding different enamel preparation modes. Concerning the different commercial brands, the American Orthodontics brackets showed higher debonding resistance than the Ormco brackets. It was concluded that, for both brands of brackets, the resistance to bracket debonding did not increase with the previous application of aluminum oxide blasting on the ename.

Lisura superficial de resinas compostas com nanopartículas após protocolos de acabamento e polimento / Smooth surface of nanoparticle composites after finishing and polishing protocols

O objetivo desse estudo foi avaliar a lisura de superfície de três resinas compostas por nanopartículas, após serem submetidas a três diferentes sistemas de acabamento e polimento. Foram obtidos 40 corpos de prova de cada resina (Filtek Z350 XT, Premise e Charisma Diamond) e distribuídos em quatro grupos experimentais (n=10): C (controle) - sem tratamento; SOF -Discos abrasivos Soflex; ENH - Pontas siliconadas Enhance e F/FF - Pontas diamantadas de granulação fina/extra-fina + disco de feltro e pasta diamantada. Após 24h da confecção e armazenamento, os sistemas de acabamento e polimento foram aplicados. A lisura superficial foi avaliada utilizando-se um rugosímetro, tendo sido realizadas cinco leituras em cada corpo de prova. A média dos valores de rugosidade de superfície [um] obtidos foi analisada através da ANOVA, dois fatores, seguido do teste de Tukey, com significância de 1%. Para todas as resinas testadas, houve diferença estatística entre os sistemas de acabamento e polimento testados (p<0,01). Para a resina Charisma, os valores de rugosidade foram: C - 0,10a; SOF - 0,24b; ENH - 0,23b; F/ FF - 0,32c. Para a Premisa: C-0,12a; SOF - 0,16ab; ENH - 0,22b; F/FF - 0,30<. Para a Filtek: C - 0,08'; SOF - 0,14ab; ENH - 0,20b<; F/FF - 0,26<. No grupo controle foram obtidos os melhores resultados de lisura de superfície para todas as resinas testadas. Em relação aos tratamentos, os grupos SOF e ENH promoveram as melhores lisuras de superfície, enquanto que o grupo F/FF resultou em superfícies com maiores rugosidades.

The aim of this study was to evaluate the smoothness surface of 3 composites by nanoparticles (Filtek Z350 XT, Premise e Charisma Diarnond], after being subjected to three different finishing and polishing systems. Were obtained 40 specimens of each resin selected and randomly divided into 4 experimental groups (n= 10): C (control) - no treatment; SOF - Abrasive discs Soflex; ENH - silicon tips Enhance; and F / FF - diamond tips fine/extra-fine granulation + felt disc and diamond paste. Twenty-four hours after the preparation and storage of the specimens in distilled water at 37°(, the finishing and polishing systems were applied. The smooth surface of the composites was evaluated using a rugosimeter, where five readings were taken on each specimen. The mean surface roughness (um) were analyzed by ANOVA, two factors, followed by Tukev's test, with significance of 1%. For ali resins tested, statistical difference was found between finishing and polishing systems tested (p<0,01). To the resin Charisma roughness values were: C - 0,10a; SOF - 0,24b; ENH - 0,23b; F/ FF - 0,32c. For the premise : C-0,12a; SOF - 0,16ab; ENH - 0,22b; F/FF - 0,30<. Para a Filtek: C - 0,08'; SOF - 0,14ab; ENH - 0,20b<; F/FF - 0,26<. The control group obtained better results of surface smoothness for ali composites tested. Regarding the treatments groups, SOF and ENH resulted on better smoothness surface, while the group FI FF resulted in surfaces with higher roughness.

Dental fracture and chocolate candies: case report.

A complaint by a customer to a food company claimed that the consumption of a chocolate candy fractured his anterior teeth, due to its hard consistency. Fragments of the fractured teeth and the chocolate candy that supposedly caused it were collected, examined and photographed. Fragments presented caries, large restorations, and suggested previous endodontic treatment. To evaluate causation, the food company requested a laboratory analysis, which simulated the human bite on chocolate candies of the same brand. Human teeth were assembled in a simulating device of masticatory functions of apprehension and incision. Teeth used were either sound or with non-restored endodontic accesses, to simulate previous conditions of the collected fragments. Twenty chocolate candies, cooled in a freezer to 0 °C for 2 h were used as test foods, and were positioned between the teeth of the device at the moment of the test. The set was put in a dynamometer, programmed to apply increasing forces (rate of advance of 5 mm/min), until rupture (either of the specimen or of the teeth). The applied force, in N, at the time of fracture was recorded and analyzed. The average force to fracture the test food was 233.23 N. No tooth was fractured in the experiment. Forces ranging from 191.3 to 275.2 N, applied to chocolate candies were not sufficient to neither fracture human teeth nor cause any structural damage. It was concluded that the dental fracture occurred because of previous oral health conditions of the customer.

Efeito da redução da intensidade de luz inicial na polimerização de uma resina composta fotoativada com luz halógena e distanciamento da ponta ativadora / Effect of the reduction of the initial light intensity on the polymerization of a composite resin photoactivated with halogen light and distancing of the activator point

Os objetivos deste estudo foram avaliar a dureza de uma resina composta fotoativada pelo método contínuo e compará-la com metodologias que utilizam menor intensidade de luz inicial, seguida pela intensidade máxima. Foram realizados 60 corpos de prova divididos em seis grupos.Os corpos de prova foram confeccionados a partir das matrizes de polipropileno pretas, utilizando a resina composta Z350 (3 M ESPE, Saint Paul, Estados Unidos), e ativadas com o fotoativador Degulus SoftStar 9DEGUSSA-HULS, Hanau, Alemanha). Os corpos de prova foram submetidos ao teste de microdureza Vickers, com o microdurômetro HMV-2000(SHIMADZU, kYOTO, JAPÃO), nas superfícies irradiadas e opostas, sendo comparadas as espessuras e os métodos de fotoativação utilizados. Após os testes de análise de variância e de Tukey, observou-se diferença estatisticamente significante entre os grupos controle, soft-star e variação da distância. A porcentagem de dureza máxima foi considerada aceitável ( menos do que 80 por cento) na superfície irradiada e em profundidades de 1 mm daquela oposta, porém nas de 2 mm os valores não atingiram o mínimo de 80 por cento da dureza máxima. Concluiu-se que os métodos de fotoativação progressiva diminuiram a microdureza da resina composta, quando comparados aos convencionais, sendo isso aceitável nas superfícies irradiadas e opostas à irradiada nos corpos de prova com 1 mm de espessura