Influence of silica nanocoating on stain susceptibility and superficial integrity of dimethacrylate-based composites.

The aim of this study was to investigate the ability of a novel silica (SiO2 )-based nanocoating approach to extend the superficial integrity of current composites. Cylindrical discs (7 × 2 mm) were produced from nanohybrid and nanofilled composites. Specimens in control groups were not coated, but SiO2 nanocoating was performed on specimens in experimental groups (n = 8). Specimens were stored for 24 h in distilled water at 37°C (baseline) and then artificially aged for 15, 90, or 180 d in a low-pH staining solution. Surface roughness (Ra) was measured using a profilometer, and a goniometer was used to determine surface free energy (SFE). Color change was evaluated by a reflectance spectrophotometer, applying the color distance metric, ΔE00 , according to the Commission Internationale de l'Eclairage (CIE) L*a*b* coordinates. Data were subjected to repeated-measures anova and the Tukey post-hoc test. Composites presented visually perceptible color changes (ΔE00  > 0.81) as early as 15 d of aging, with significantly higher ΔE00 values recorded over time. Nanocoating with SiO2 significantly reduced the SFE of composites at all storage times, and significantly lower Ra values were identified after aging. Nanohybrid and nanofilled composites were susceptible to substantial hydrolytic superficial degradation and staining, which was dramatically attenuated by the proposed SiO2 nanocoating approach. Nanocoating effectively lowered the SFE of composites, thus minimizing water-composite interactions, which contributed to reduced superficial deterioration and lower stain susceptibility over time.

Does the moment of fiber post cutting influence on the retention to root dentin?

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Does the Moment of Fiber Post Cutting Influence on the Retention to Root Dentin?

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Apesar das diversas vantagens associadas aos pinos de fibra de vidro pré-fabricados, o corte da sua porção coronária deve ser realizado para permitir seu uso em algumas situações clínicas. Entretanto, o corte do pino cimentado pode gerar tensões na interface adesiva e afetar a resistência de união. O objetivo deste estudo foi avaliar o efeito do momento do corte do pino na resistência de união ao canal radicular. Sessenta raízes de incisivos bovinos foram incluídas em cilindros de resina com simulação do ligamento periodontal. Pinos de fibra de vidro foram cimentados utilizando um cimento resinoso convencional RelyX ARC (3M ESPE) ou autoadesivo RelyX Unicem (3M ESPE). Os pinos foram cortados previamente à cimentação, imediatamente após a cimentação, ou após a reconstrução do núcleo de preenchimento (n=10). Após o armazenamento por 24 h, as amostras foram seccionadas e submetidas ao ensaio de cisalhamento por extrusão utilizando máquina de ensaio mecânico (EMIC DL 2000). Os dados foram analisados por ANOVA dois fatores (cimento resinoso x momento do corte do pino) e teste de Tukey (=0,05). O momento do corte do pino de fibra de vidro não afetou a resistência de união quando o RelyX Unicem foi utilizado. No entanto, o corte do pino imediatamente após a cimentação reduziu os valores de resistência de união quando o RelyX ARC foi utilizado. Em conclusão, o momento do corte do pino pode afetar a resistência de união ao canal radicular quando o cimento resinoso convencional for utilizado.

Influence of flowable composite and restorative technique on microleakage of class II restorations.

AIM: The aim of the present study was to evaluate the microleakage in class II cavities restored with dental composite by varying the thickness of two flowable composite resins and the restorative technique. METHODS: A total of 130 cavities were prepared on proximal surfaces of bovine teeth and randomly divided in 13 groups. Twelve experimental groups were performed using flowable composite resin as the liner, and they were divided according to the type of flowable composite resin (Filtek Z350 Flow-Z350F and SureFil SDR Flow-SUR), the thickness of the flowable composite (0.5, 1, or 2 mm), and the restorative technique (flowable composite applied at the cavosurface angle or amelodentinal junction) (n = 10). A control group was performed without using a flowable composite. Following restorative procedures and thermocycling, the samples were immersed in Methylene Blue for 2 h, and prepared for analysis in an absorbance spectrophotometer. All results were statistically analyzed (α = 0.05). RESULTS: There was no significant difference between the flowable composites (P > 0.05). The restorative techniques influenced microleakage and were flowable composite dependent (P ≤ 0.05). The lower thickness of the flowable composite provided less microleakage (P ≤ 0.05). CONCLUSION: The use a lower thickness of a flowable composite resin provided less microleakage, suggesting a better sealing tooth-restoration interface.

Direct restorative treatment of anterior weared teeth after re-establishment of occlusal vertical dimension: a case report.

OBJECTIVE: The loss of posterior teeth resulting in a lack of stability may lead to excessive mandibular load on some points of occlusion of the remaining teeth, causing wear. The rehabilitation of these cases must be carefully planned and the treatment requires a period of adaptation with a new vertical dimension. BACKGROUND: This case report describes the treatment of a patient with a loss of almost all posterior inferior teeth and a consequential loss of occlusal vertical dimension and accentuated wear of anterior elements. MATERIALS AND METHODS: Provisional removable partial dentures were manufactured and the patient used them for a period of adaptation prior to restoration of the anterior teeth. After the patient's adaptation with the new occlusal dimension, anterior restorations were made using a mycrohibrid resin composite with different color aspects for an optimal stratification. RESULTS: The restorations achieved an aesthetic configuration with ideal function as the final result and the occlusion showed a satisfactory stability for a provisional removable partial dentures. CONCLUSION: This article presents an anterior direct rehabilitation approach not only as an alternative option, but also as viable and less expensive treatment option with an optimally aesthetic and functional result.

Effect of immediate and delayed light activation on the mechanical properties and degree of conversion in dual-cured resin cements.

We evaluated the effect of activation mode (immediate or delayed light activation vs. no light activation) on diametral tensile strength (DTS), elastic modulus, ultimate tensile strength (UTS), and degree of conversion (DC) in dual-cured resin cements. Three resin cements were evaluated: Enforce, RelyX ARC, and Panavia F. The mixed cements were inserted into circular molds for the DTS test and into dumbbell-shaped molds for the UTS test. Inside the molds, the cements were light-activated either immediately or after 5 min (delayed light activation). If no light activation was performed, the materials were protected from light exposure (control). The DTS and UTS tests were performed until fracture. The elastic modulus was calculated using data from the DTS test, and DC was evaluated 24 h after manipulation using near-infrared spectroscopy. Data for each variable were individually analyzed by two-way ANOVA and the post-hoc Tukey test (α = 0.05). Regarding DTS, activation mode influenced only Panavia Fspecimens, which had the lowest DTS values in the absence of light activation. Activation mode did not influence the elastic modulus or UTS of any resin cement evaluated. Immediate light activation yielded higher DC values as compared with the absence of light activation.

Traumatismo dentário na hebiatria: relato de caso clínico / Dental traumatism in hebiatry: a clinical case report

Grande variedade de tratamento é indicada para dentes traumatizados, com fratura de esmalte e dentina, durante a infância e adolescência, dependente da quantidade de remanescente dentário. Dentre as possibilidades de tratamento para recuperação estética, funcional e biomecânica, materiais odontológicos que mimetizam propriedades das estruturas dentárias são almejados. Pinos de fibra de vidro tem sido cada vez mais utilizados pela capacidade de distribuir as tensões de forma favorável, minimizando o risco de fraturas em dentes com mínimo remanescente coronário, podendo ser associados à restaurações diretas e indiretas. O objetivo do presente relato de caso clínico é apresentar alternativa de tratamento com maior preservação de remanescente assegurando retenção do material restaurador, selamento do canal radicular e adequada longevidade de tratamento para dentes com fratura coronária com envolvimento de esmalte e dentina, em paciente hebiátrico.

Wide range of treatment is indicated for traumatized teeth with enamel and dentin fracture during childhood and adolescence, dependent on the amount of remaining. Among the treatment options for recovery aesthetic and functional biomechanics, dental materials that mimic properties of dental structures are desired. Glass fiber posts have been increasingly used for its ability to distribute stresses favorably, minimizing the risk of fractures in teeth with minimal remaining coronal, and may be associated with direct and indirect restorations. The purpose of this case report is to present an alternative treatment with greater preservation of remnant ensuring retention of the restorative material, sealing the root canal and adequate treatment for longevity of teeth with coronal fracture involving enamel and dentin of a hebiatric patient.

Does bonding to dentin reduce microleakage of composite restorations?

This study evaluated the effect of adhesive application only to enamel on the marginal microleakage of composite resin restorations performed with different adhesive systems. Standardized cylinder-shaped cavities were prepared on the buccal surface of eighty bovine incisors. Two etch-and-rinse (Adper Scotchbond Multi-purpose [3M ESPE, St. Paul, MN USA] and Adper Single Bond 2 [3M ESPE]) and two self-etching (Clearfil SE Bond [Kuraray, Osaka, Japan] and Adper Prompt [3M ESPE]) adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light-activation, the cavities were restored with composite resin. The samples were coated with two layers of nail polish, except an area of 1-mm wide around of the restoration, and immersed in a methylene blue solution. Afterwards, the specimens were ground in order to obtain powder which was immersed in absolute alcohol. The solutions were centrifuged and the supernatant was analyzed using an absorbance spectrophotometer. Linear regression was used to estimate the dye concentration. Data were analyzed using ANOVA and Tukey's tests (alpha = 0.05). The etch-and-rinse adhesives showed lower microleakage means compared to those of the self-etching adhesives. Adper Prompt presented higher microleakage means. There was no difference between the modes of application of the adhesive on the cavity for all adhesive systems, except for Clearfil SE Bond. This showed lower microleakage when applied to the whole cavity. Bonding to dentin may not reduce microleakage of composite restorations.

Effect of light-curing unit and adhesive system on marginal adaptation of class v composite restorations.

The aim of this study was to evaluate the effect of light-curing units (LED or halogen) on the marginal adaptation of composite restorations performed with etch-and-rinse and self-etching adhesive. Class V cavities were prepared on bovine teeth with the gingival margin on dentin and the incisal margin on enamel. The cavities were restored with a micro-hybrid resin composite using an etch-and-rinse (Single Bond 2--SB) or a self-etching adhesive (Clearfil SE Bond--CL). The light-activations were performed using halogen lamp (Optilux 501--QTH) or second-generation light-emitting diode (Radii-Cal--LED) (n = 10). After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed under scanning electronic microscopy with 500x of magnification. The greatest gap width at each margin was recorded. Data were submitted to Mann-Whitney and Wilcoxon tests (a = 0.05). SB and CL showed similar behavior of enamel margins when the light-activations were performed with QTH. The same was observed for dentin margins with LED. When the LED was used, higher gap measurements at enamel margins were observed with CL, while higher gap values in dentin were observed for SB within QTH. No significant difference between substrates was found when CL was used. However, SB had significantly higher gap measurements in dentin. The light-curing unit seems to affect the marginal adaptation of resin composite restorations. However this effect was dependent on the adhesive and the location of the margin.

Colagem de fragmento dentário: revisão sistemática da literatura associada a relato de caso clínico / Tooth reattachment: a systematic review and a case report

A colagem de fragmento dentário é alternativa estética e conservadora para dentes traumatizados. O objetivo deste trabalho foi realizar revisão sistemática da literatura científica de pesquisas clínicas que abordaram a colagem de fragmento dentário, compreendendo o período de 1955 até Março de 2012, associando-a a caso clínico para ilustrar técnica que parece ser adequada. Para a busca bibliográfica utilizou-se o site Pubmed/Medline com os seguintes descritores: "tooth fragment reattachment" e "dental bonding fragments". Foram obtidos 147 resumos, os quais foram lidos por dois revisores individualmente. Obtiveram-se 41 pesquisas laboratoriais, 6 pesquisas clínicas, 5 revisões de literatura e 94 casos clínicos. Porém, apenas 5 artigos foram considerados nesta revisão, de acordo com os critérios de inclusão e exclusão estabelecidos. Consideraram-se os seguintes aspectos: meio de armazenagem do fragmento, técnica de preparo do remanescente e do fragmento, materiais para a colagem e sucesso clínico. Adicionalmente, apresenta-se relato de caso clínico, de paciente de 8 anos de idade, envolvendo a colagem de fragmento após fratura coronária dos dentes 11 e 21 com acompanhamento clínico de 12 meses. Após avaliação sistemática da literatura, percebe-se que são poucos artigos que descrevem criteriosamente a técnica, abordando os critérios de interesse estabelecidos. A colagem de fragmento dentário demonstrou altas taxas de sucesso, principalmente nos primeiros 24 meses das avaliações clínicas. E parece ser eficaz quanto à manutenção da função mastigatória, à saúde periodontal e à satisfação do paciente. Além de conservadora, é fácil, rápida, de excelente resultado estético e funcional, resgatando ainda o equilíbrio emocional do paciente.

The tooth fragment reattachment is conservative and aesthetic alternative traumatized teeth. The aim of this study was realize systematic review of literature seeking clinical researches approaching of tooth fragment reattachment between the period of 1955 until 2012 march and associate it with a an clinical case, that illustrates a proper technique. For bibliographic search was used the PubMed / Medline website using the following keywords: "tooth fragment reattachment" and "dental bonding fragments." One hundread and forty seven abstracts were obtained, which were read by two reviewers, individually. Forty-one laboratorial researches, six clinical trials, five literature reviews and night-four clinical cases were obtained. However, only five were considered in this review, in accordance to the established inclusion and exclusion criteria. The following aspects were considered: medium storage of the fragment, preparation technique of dental remaining and fragment, bonding materials and clinical success. In addition, it was presented a case report of an 8 year old patient, involving the bonding of fragment after coronary fracture of teeth 11 and 21 with clinical follow up of 12 months. After systematic evaluation of the literature, it were found few articles with a careful description of the technique addressing the established interest criteria. The collage of fragments showed high success rates, especially in the first 24 months of clinical evaluations, and seems to be effective in maintenance of chewing, periodontal health and patient satisfaction. Besides being conservative, it's easy, fast, excellent both in cosmetic and functional outcome, and can also rescue the patient's emotional balance.

Panavia F: the role of the primer.

This study evaluated the rate of polymerization (R(p)) and degree of conversion (DC) of Panavia F when self- or dual-activated, and the influence of either using or not using a primer containing co-initiators (ED Primer) mixed with the material. The conversion reaction was monitored using real-time infrared spectroscopy with an attenuated total reflectance device. The cement was mixed, put onto the device and irradiated for 20 s (dual-cured). A self-cured group was also prepared. Similarly, dual- and self-cured groups were evaluated after mixing ED Primer with the cement. The DC was monitored for 1 h and the R(p) was calculated. For the dual-cured mode, the most significant effect of ED Primer was to reduce the R(p)(max). For the self-cured mode, the primer was shown to be essential for polymerization of Panavia F: without ED Primer, the reaction started only after approximately 500 s, with a final DC of 50%, whereas a continuous increase in conversion was observed for the group mixed with ED Primer, with a final DC of 74%. The ED primer is essential for proper polymerization of Panavia F; the cement becomes independent of the light when the primer is used.