Influence of curing rate on softening in ethanol, degree of conversion, and wear of resin composite.

PURPOSE: To investigate the effect of curing rate on softening in ethanol, degree of conversion, and wear of resin composites. METHOD: With a given energy density and for each of two different light-curing units (QTH or LED), the curing rate was reduced by modulating the curing mode. Thus, the irradiation of resin composite specimens (Filtek Z250, Tetric Ceram, Esthet-X) was performed in a continuous curing mode and in a pulse-delay curing mode. Wallace hardness was used to determine the softening of resin composite after storage in ethanol. Degree of conversion was determined by infrared spectroscopy (FTIR). Wear was assessed by a three-body test. Data were submitted to Levene's test, one and three-way ANOVA, and Tukey HSD test (alpha = 0.05). RESULTS: Immersion in ethanol, curing mode, and material all had significant effects on Wallace hardness. After ethanol storage, resin composites exposed to the pulse-delay curing mode were softer than resin composites exposed to continuous cure (P< 0.0001). Tetric Ceram was the softest material followed by Esthet-X and Filtek Z250 (P< 0.001). Only the restorative material had a significant effect on degree of conversion (P< 0.001): Esthet-X had the lowest degree of conversion followed by Filtek Z250 and Tetric Ceram. Curing mode (P= 0.007) and material (P< 0.001) had significant effect on wear. Higher wear resulted from the pulse-delay curing mode when compared to continuous curing, and Filtek Z250 showed the lowest wear followed by Esthet-X and Tetric Ceram.

Preservation in Young Patients of Pulp Vitality and Anatomical-Functional Restoration of the Lost Structure.

Often, young patients (≤30 years old) present with carious lesions that progress acutely, compromising a large amount of tooth structure. In these cases, a treatment to prevent the occurrence of pulp exposure and promote remineralization of caries-affected dentin is necessary to maintain healthy dental structure and allow more conservative interventions. The approach will be different when pulp exposure occurs: The therapeutic treatments will be focused on reparative dentin formation and prevention of microorganisms penetrating the pulp organ. Due to the different possible treatments that can be performed to avoid pulp necrosis and the various materials that can be used for this purpose, professionals may have some difficulties understanding all the indications for conservative pulp treatments. The objective of this article is to describe and discuss a successful pulp capping and stepwise excavation associated with restorative treatment for deep caries lesions of anterior upper teeth.

5-year clinical performance of resin composite versus resin modified glass ionomer restorative system in non-carious cervical lesions.

AIM: To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions. METHOD AND MATERIALS: One operator placed 70 restorations (35 resin modified glass ionomer restorations and 35 resin composite restorations) in 30 patients under rubber dam isolation without mechanical preparation. The restorations were directly assessed by 2 independent examiners, using modified USPHS criteria at baseline and 6, 12, 24 and 60 months. RESULTS: Twenty-two patients were available for recall after 5 years (73.3% recall rate) and 55 out of 70 restorations were evaluated. Excellent agreement was registered for all criteria between examiners (kappa > or = 0.85). Sixteen composite restorations were dislodged (51.5% retention) and 1 ionomer restoration was lost (96.4% retention). The McNemar test detected significant differences in resin composite restorations between baseline and 5-year recall for marginal integrity (p<0.001) and retention (p=0.004). For resin modified glass ionomer restorations, no significant differences were identified for all criteria (p>0.05). When comparing both materials, the Fisher exact test pointed out significant differences in retention (p=0.002) after 5 years of clinical service. CONCLUSIONS: After 5 years of evaluation, the clinical performance of resin modified glass ionomer restorations was superior to resin composite restorations.

Influence of pH of different adhesive systems on the polymerization of a chemically cured composite resin.

The purpose of this study was to investigate the effect of pH of different adhesive systems on the polymerization of a chemically cured composite resin (Adaptic--AD), by means of tensile bond strength testing. The adhesive systems tested were: ARM, Prime & Bond 2.1 (PB), Scotchbond Multi Purpose (SMP) and Single Bond (SB). Bond strength at the resin/adhesive system/resin interface was assessed. Five groups (n=5) were formed, according to following configuration: G1: AD/ARM/AD; G2: AD/PB/AD; G3: AD/SMP/AD; G4: AD/SB/AD; G5: AD/AD (no adhesive). A two-mold stainless steel matrix with a cone-shaped opening (1-mm-thick; 4 mm in diameter) was used to obtain resin discs. AD resin was inserted into the first mold, left-self curing and an adhesive layer was applied onto resin surface and light-cured. The second mold was assembled over the first and was filled with the resin. After 10 min, this setting was loaded in tension in a universal testing machine running at a crosshead speed of 0.5 mm/min. Data were submitted to one-way ANOVA and Tukey's test (p<0.05). Bond strength means (kgf) were: G1: 15.23 +/- 4.1; G2: 0.00 +/- 0.0; G3: 16.96 +/- 2.4; G4: 10.08 +/- 2.7; G5: 15.44 +/- 0.9. There were statistically significant differences (p<0.05) between G2-G1; G2-G3; G2-G4; G4-G1; G4-G3. The systems with the lowest pHs (PB and SB) yielded the lowest bond strength. The findings of this in vitro study demostrates that the pH of adhesive systems influences the polymerization and bond strength of chemically cured resin materials. The low pH simplified adhesive systems showed distinct degrees of incompatibility with the chemically cured resin, when compared to the conventional adhesive systems.

Effect of the cavity configuration factor on the marginal microleakage of esthetic restorative materials.

PURPOSE: To evaluate the effect of the cavity configuration factor (CF) on the marginal microleakage of cervical restorations with four aesthetic restorative materials. MATERIALS AND METHODS: Conventional cavities, 2.9 mm in diameter and 1.5 mm deep, with CF=2.7 and "saucer"-shaped ones with CF=2 were created in 60 extracted premolars. The following groups were established: G1: Z100/Single Bond, G2: Freedom/Stae, G3: Vitremer/Primer and G4: Durafill/Durafill Bond, following each manufacturer's directions. Thermocycling of the specimens was performed in an aqueous solution of 2% buffered methylene blue, with the temperature varying between 5 to 55 degrees C, for a total of cycles of 60 minutes per day, for 7 days. The specimens were then sectioned and evaluated by two observers using photographs acquired from a stereomicroscope. The values were subjected to Kruskal-Wallis analysis and the Dunn and Wilcoxon test. RESULTS: The averages of the microleakage scores observed in the conventional and "saucer"-shaped cavities were respectively: G1: 0.66/0.46; G2: 0.92/0.69; G3: 1.8/1.86; G4: 3.54/2.3.

Partial pulpotomy and tooth reconstruction of a crown-fractured permanent incisor: a case report.

Pulp exposure due to traumatic injuries in the anterior permanent teeth of adolescents is a common occurrence. A vital permanent maxillary incisor with complex crown fracture and pulp exposure was treated by partial pulpotomy and assessed clinically through pulpal sensitivity tests and radiographically for periapical healing. Partial pulpotomy consisted of pulp tissue removal to a depth of only 1 to 2 mm, then capping the pulpal wound with calcium hydroxide, lining with resin-modified glass-ionomer cement, and restoration with resin composite. At each recall (7, 15, 21, 50, 90, 150, and 250 days), no spontaneous pain was observed; the pulp showed signs of vitality and absence of periapical radiolucency after 90 days. For long-term success, partial pulpotomy is recommended as an option for cases of traumatic pulp exposure in permanent incisors with crown fractures.

Effect of caries preventive measures directed to expectant mothers on caries experience in their children.

The aim of this prospective study was to determine the effectiveness of caries preventive measures started during pregnancy on the caries experience of first-time mothers and their infants. Eighty-one pregnant women with low social background were selected on the basis of the presence of active carious lesions and were randomly divided into control (38) and experimental (43) groups. The initial dental status (DMFS and white spot lesions) was established through clinical examination. The prophylactic measures were repeated during pregnancy and 6 and 12 months after delivery. Both groups received primary care intervention. They were instructed in relation to the etiologic factors of dental caries and received oral hygiene kits. Oral hygiene instructions were reinforced through interactive brushing. The experimental group also received antimicrobial treatment (topical application of NaF and iodine solution immediately after prophylaxis and 3 and 5 days later) and restorative care using glass ionomer cement. By the time the children were 2 years of age, 33.3% of the infants in the control group and 14.7% in the experimental group had caries activity. A significant difference in caries prevalence was observed between children with and without visible dental plaque. The mean number of tooth surfaces with carious lesions (including areas of demineralization) was higher among the children in the control group compared to the experimental group (6.3 x 3.2), however, with no statistical significance. Maternal caries increase was a significant factor influencing the caries experience of the children. These data support the evidence of an association between caries prevalence in young children and clinical (dental plaque) and maternal factors.

Minimal alterations on the enamel surface by micro-abrasion: in vitro roughness and wear assessments.

OBJECTIVE: To evaluate the in vitro changes on the enamel surface after a micro-abrasion treatment promoted by different products. MATERIAL AND METHODS: Fifty (50) fragments of bovine enamel (15 mm × 5 mm) were randomly assigned to five groups (n=10) according to the product utilized: G1 (control)= silicone polisher (TDV), G2= 37% phosphoric acid (3M/ESPE) + pumice stone (SS White), G3= Micropol (DMC Equipment), G4= Opalustre (Ultradent) and G5= Whiteness RM (FGM Dental Products). Roughness and wear were the responsible variables used to analyze these surfaces in four stages: baseline, 60 s and 120 s after the micro-abrasion and after polishing, using a Hommel Tester T1000 device. After the tests, a normal distribution of data was verified, with repeated ANOVA analyses (p≤0.05) which were used to compare each product in different stages. One-way ANOVA and Tukey tests were applied for individual comparisons between the products in each stage (p≤0.05). RESULTS: Means and standard deviations of roughness and wear (µm) after all the promoted stages were: G1=7.26(1.81)/13.16(2.67), G2=2.02(0.62)/37.44(3.33), G3=1.81(0.91)/34.93(6.92), G4=1.92(0.29)/38.42(0.65) and G5=1.98(0.53)/33.45(2.66). At 60 seconds, all products tended to produce less surface roughness with a variable gradual decrease over time. After polishing, there were no statistically significant differences between the groups, except for G1. Independent of the product utilized, the enamel wear occurred after the micro-abrasion. CONCLUSIONS: In this in vitro study, enamel micro-abrasion presented itself as a conservative approach, regardless of the type of the paste compound utilized. These products promoted minor roughness alterations and minimal wear. The use of phosphoric acid and pumice stone showed similar results to commercial products for the micro-abrasion with regard to the surface roughness and wear.

The influence of "C-factor" and light activation technique on polymerization contraction forces of resin composite.

OBJECTIVES: This study evaluated the influence of the cavity configuration factor ("C-Factor") and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer). MATERIAL AND METHODS: Three different pairs of steel moving bases were connected to a universal testing machine (emic DL 500): groups A and B - 2x2 mm (CF=0.33), groups C and D - 3x2 mm (CF=0.66), groups e and F - 6x2 mm (CF=1.5). After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm³ in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm² for 5 s, 40 s interval, 600 mW/cm² for 20 s) and continuous pulse (600 mW/cm² for 20 s). Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N) x Time(s)) and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05). RESULTS: For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin. CONCLUSIONS: Pulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.

Impact of filler size and distribution on roughness and wear of composite resin after simulated toothbrushing.

OBJECTIVES: Nanofilled composite resins are claimed to provide superior mechanical properties compared with microhybrid resins. Thus, the aim of this study was to compare nanofilled with microhybrid composite resins. The null hypothesis was that the size and the distribution of fillers do not influence the mechanical properties of surface roughness and wear after simulated toothbrushing test. MATERIAL AND METHODS: Ten rectangular specimens (15 mm x 5 mm x 4 mm) of Filtek Z250 (FZ2), Admira (A), TPH3 (T),Esthet-X (EX), estelite sigma (ES), concept advanced (C), Grandio (G) and Filtek Z350 (F) were prepared according to manufacturer's instructions. Half of each top surface was protected with nail polish as control surface (not brushed) while the other half was assessed with five random readings using a roughness tester (Ra). Following, the specimens were abraded by simulated toothbrushing with soft toothbrushes and slurry comprised of 2:1 water and dentifrice (w/w). 100,000 strokes were performed and the brushed surfaces were reanalyzed. Nail polish layers were removed from the specimens so that the roughness (Ra) and the wear could be assessed with three random readings (µm). Data were analyzed by ANOVA and Tukey's multiple-comparison test (α=0.05). RESULTS: Overall outcomes indicated that composite resins showed a significant increase in roughness after simulated toothbrushing, except for Grandio, which presented a smoother surface. Generally, wear of nanofilled resins was significantly lower compared with microhybrid resins. CONCLUSIONS: As restorative materials suffer alterations under mechanical challenges, such as toothbrushing, the use of nanofilled materials seem to be more resistant than microhybrid composite resins, being less prone to be rougher and worn.

Clinical strategies for esthetic excellence in anterior tooth restorations: understanding color and composite resin selection.

Direct composite resin restorations have become a viable alternative for patients that require anterior restorative procedures to be integrated to the other teeth that compose the smile, especially for presenting satisfactory esthetic results and minimum wear of the dental structure. Technological evolution along with a better understanding of the behavior of dental tissues to light incidence has allowed the development of new composite resins with better mechanical and optical properties, making possible a more artistic approach for anterior restorations. The combination of the increasing demand of patients for esthetics and the capacity to preserve the dental structure resulted in the development of different incremental techniques for restoring fractured anterior teeth in a natural way. In order to achieve esthetic excellence, dentists should understand and apply artistic and scientific principles when choosing color of restorative materials, as well as during the insertion of the composite resin. The discussion of these strategies will be divided into two papers. In this paper, the criteria for color and material selection to obtain a natural reproduction of the lost dental structures and an imperceptible restoration will be addressed.

Thermal-induced polymerization shrinkage in silorane versus methacrylate based resin composite / Contração de polimeração induzida termicamenteem resinas compostas a base de silorano e metacrilato

Shrinkage is a limitation of resin composite, compromising the clinical longevity of the restorative procedure. In an attempt to reduce their harmful effects, researchers have studied monomers with lower values of contraction. As a result, low-shrinkage composites were developed. This study evaluated quantitatively the shrinkage as a function of power density increase based on methacrylates, comparing them with silorane based resin, and qualitatively regarding gap formation between the adhesive interface as function of tooth substrate. Resin Filtek P90 and Filtek Z250 were polymerized with the device Blue Star 3 with 200, 400, 600, 800 and 1000 mW/cm2 keeping volume constant in 12 mm3. For qualitative analysis of restorative interface, class V cavity preparations in bovine incisors were restored in (2x2x2 mm3), photoactivated with the same values of irradiance, and analyzed by scanning electron microscopy at the interface of the wall surrounding enamel, dentin and axial. The quantitative results of the polymerization shrinkage were analyzed by two-way ANOVA and Tukey's test (p<0.05), while qualitative data were submitedd to Mann-Whitney's, Kruskal-Wallis' and Miller's tests. The progressive increase in power density directly influenced the polymerization shrinkage of the materials studied, although the silorane based resin demonstrated significantly lower values. The marginal integrity was influenced by the dental substrate and the power density used.

Este estudo avaliou quantitativamente a contração de polimerização em função do aumento dos valores de densidade de potência irradiados em compósitos à base de metacrilatos e silorano, e qualitativamente a interface restauradora em relação à abertura de fendas marginais, em função da variação do tipo de substrato dentário. As resinas Filtek Z250 e Filtek P90 foram fotoativadas com 200, 400, 600, 800 e 1000 mW/cm2, em um volume constante de 12mm3, e os valores de contração foram aferidos por meio da máquina de ensaios universal. Para análise qualitativa da interface restauradora, preparos cavitários classe V de (2x2x2mm3) foram restaurados em incisivos bovinos, fotoativados com os mesmos valores de irradiância, e analisados em microscopia eletrônica de varredura nas interfaces da parede circundante em esmalte, parede circundante em dentina e parede axial. Os resultados quantitativos da contração de polimerização foram analisados pelo teste ANOVA a dois critérios e Tukey (p<0,05) enquanto para os dados qualitativos os testes Mann- Whitney, Kruskal-Wallis e Miller foram empregados. O aumento progressivo da densidade de potência influenciou diretamente na contração de polimerização dos materiais estudados, não obstante a resina composta à base de silorano ter demonstrado valores significativamente menores. A integridade marginal sofreu influência do substrato dentário bem como da densidade de potência utilizada, para as duas resinas estudadas.

Effect of light sources and curing mode techniques on sorption, solubility and biaxial flexural strength of a composite resin.

UNLABELLED: Adequate polymerization plays an important role on the longevity of the composite resin restorations. OBJECTIVES: The aim of this study was to evaluate the effect of light-curing units, curing mode techniques and storage media on sorption, solubility and biaxial flexural strength (BFS) of a composite resin. MATERIAL AND METHODS: Two hundred and forty specimens were made of one composite resin (Esthet-X) in a stainless steel mold (2 mm x 8 mm Ø), and divided into 24 groups (n=10) established according to the 4 study factors: light-curing units: quartz tungsten halogen (QTH) lamp and light-emitting diodes (LED); energy densities: 16 J/cm² and 20 J/cm²; curing modes: conventional (CM) and pulse-delay (PD); and permeants: deionized water and 75% ethanol for 28 days. Sorption and solubility tests were performed according to ISO 4049:2000 specifications. All specimens were then tested for BFS according to ASTM F394-78 specification. Data were analyzed by three-way ANOVA followed by Tukey, Kruskal-Wallis and Mann-Whitney tests (α=0.05). RESULTS: In general, no significant differences were found regarding sorption, solubility or BFS means for the light-curing units and curing modes (p>0.05). Only LED unit using 16 J/cm² and PD using 10 s produced higher sorption and solubility values than QTH. Otherwise, using CM (16 J/cm²), LED produced lower values of BFS than QTH (p<0.05). 75% ethanol permeant produced higher values of sorption and solubility and lower values of BFS than water (p<0.05). CONCLUSION: Ethanol storage media produced more damage on composite resin than water. In general the LED and QTH curing units using 16 and 20 J/cm² by CM and PD curing modes produced no influence on the sorption, solubility or BFS of the tested resin.

Accuracy of Single-Step versus 2-Step Double-Mix Impression Technique.

Objective. To investigate the accuracy of dies obtained from single-step and 2-step double-mix impressions. Material and Methods. Impressions (n = 10) of a stainless steel die simulating a complete crown preparation were performed using a polyether (Impregum Soft Heavy and Light body) and a vinyl polysiloxane (Perfectim Blue Velvet and Flexi-Velvet) in two consistencies, in one or two (without relief) steps. Accuracy of the stone dies was accessed at a measuring microscope, using a metallic crown with perfect fit to the reference crown preparation. Data were submitted to 2-way ANOVA and Tukey test (α = 0.05). Results. The single-step technique resulted in slightly larger dies, while the 2-step technique without relief produced significantly smaller dies, when compared to the original stainless steel die. Stone dies obtained from 2-step polyether impressions were significantly smaller when compared to dies obtained from 2-step vinyl polysiloxane impressions (Impregum 2-step: -290.94 ± 71.64 µm; Perfectim 2-step: -201.86 ± 28.58 µm). No significant differences were observed in dies obtained from either polyether or vinyl polysiloxane with the single-step technique (Impregum single-step: 63.52 ± 16.60 µm; Perfectim single-step: 79.40 ± 14.11 µm). Conclusion. Higher discrepancies were detected for the 2-step impression technique without relief for the investigated materials.

Conservative approaches for the management of failed resin-based posterior restorations: a case report.

Composite resin restorations have been shown to be functionally reliable and esthetically acceptable to patients, primarily due to improvements in their chemicophysical characteristics. Nevertheless, clinical limitations, such as marginal discoloration, disadaptation, and microleakage, are observed in some patients with these restorations. The choice of treatment pursued to repair such restorations depends primarily on the analysis of the compromised restoration with regard to these aforementioned imperfections. The most common procedures invoked to treat compromised restorations include resurfacing, repairing the restoration with or without the use of surface sealants, and completely replacing the compromised restoration. This case report describes the proper implementation of a simple technique, known as composite resin posterior restoration, that yields a satisfactory outcome for patients who have been characterized with these clinical limitations.

Conservative approach for a clinical resolution of enamel white spot lesions.

Enamel white spot lesions in anterior teeth that compromise esthetics are common. Microabrasion is indicated, since it affects enamel superficially. An acid-abrasive slurry with 37% phosphoric acid with pumice was used on the enamel for a controlled time period. Home bleaching with hydrogen peroxide was then used, further improving the final result. The method is safe, easy, and conservative and provides good esthetic results.

Nine-year clinical evaluation of composite resins in Class III restorations / Avaliação de nove anos de restaurações de classe III em resina composta

The aim of this study was to evaluate thenine-year clinical performance of Class III composite restorations using two microhybrid anterior composite resins [Magic™-Vigodent/(F) and Z100™-3M ESPE/(Z)]. Material and Methods: The study was a randomized controlled trial, following the splitmouth design. Seventy restorations were placed, thirty-five for each resin composite into 35 patients. The restorations were placed by one operator according to the manufacturers’ specifications. Two independent evaluators conducted the clinical evaluation using modified USPHS criteria. After nine years, 56 restorations (28F-28Z) were evaluated. Data were analyzed using Chi-square, Exact Fisherand McNemar tests (p < 0.05). Results: Nopost operative sensitivity, secondary caries and loss of anatomic form was observed after nine-years for both composites. There were no significant differences between the two composites tested at baseline and after nine-years. Significant differen ces for Z and Frestorations between baseline and nine-year with respect to color matching and for F regarding themarginal integrity were detected. Conclusion: The clinical performance of both materials was consideredacceptable after the 9-year evaluation...

Objetivo: O objetivo deste estudo foi avaliar após nove anos a performance clínica de restaurações de classe III em resina composta, utilizando-se duas resinas microhíbridas para dentes anteriores [Magic-Vigodent/(F) e Z100-3M ESPE/(Z)]. Material e Métodos: Trata-se de um estudo clínico controlado aleatório, o qual utilizou o desenho de boca dividida.Setenta restaurações foram realizadas em trinta e cinco pacientes, sendo trinta e cinco para cada resina composta. As restaurações foram realizadas por um único operador seguindo as especificações dos fabricantes. Dois avaliadores independentes avaliaram as restaurações utilizando-se o critério USPHS modificado. Após nove anos, 56 restaurações(38F – 28Z) foram avaliadas. Os dados foram analisados por meio dos testes Qui-quadrado, Exato de Fisher e McNemar (p < 0,05). Resultados: Não foram detectados sensibilidade pós-operatória, cárie secundária e perda de forma anatômica no período analisado para ambas resinas. Não houve diferenças entre o período inicial e de nove anos para as resinas testadas, exceto para Z e F foram em relação à a cor e para a integridade do material para F. Conclusão: O comportamento clínico das duas resinas testadas foi considerado adequado após nove anos de avaliação...

Two-year clinical evaluation of resinous restorative systems in non-carious cervical lesions.

This controlled clinical trial evaluated the 2-year clinical performance of a one-bottle etch-and-rinse adhesive and resin composite system (Excite/Tetric Ceram) compared to a resin-modified glass ionomer cement (RMGIC) (Vitremer/3M) in non-carious cervical lesions. Seventy cervical restorations (35 resin composite - RC- restorations and 35 RMGIC restorations) were placed by a single operator in 30 patients under rubber dam isolation without mechanical preparation. All restorations were evaluated blindly by 2 independent examiners using the modified USPHS criteria at baseline, and after 6, 12 and 24 months. Data were analyzed statistically by Fisher's exact and McNemar tests. After 2 years, 59 out of 70 restorations were evaluated. As much as 78.8% retention rate was recorded for RC restorations, while 100% retention was obtained for RMGIC restorations. Fisher's exact test showed significant differences (p=0.011) for retention. However, there were no significant differences for marginal integrity, marginal discoloration, anatomic form and secondary caries between the RC and RMGIC restorations. The McNemar test detected significant differences for Excite/TC between baseline and the 2-year recall for retention (p=0.02), marginal integrity (p=0.002) and anatomic form (p=0.04). Therefore, the one-bottle etch-and-rinse bonding system/resin composite showed an inferior clinical performance compared to the RMGIC.

Influence of pulse-delay curing on sorption and solubility of a composite resin.

The purpose of this study was to evaluate the sorption and solubility of a composite resin (TPH(3); Dentsply) cured with halogen light due to different storage media and curing modes. The methodology was based on the ISO 4049 standard. Two independent groups were established according to the storage time (7 days-G1; 60 days-G2). A stainless steel mould (2 mm x 8 mm Ø) was used. The selected curing modes were: I (Conventional - C): 40s - 600 mW/cm(2); II (Pulse I - PD): 3 s - 200 mW/cm(2) + 2 min (delay) + 39 s - 600 mW/cm(2); III (Pulse II): 10 s - 200 mW/cm(2) + 2 min (delay) + 37 s - 600 mW/cm(2); IV (Pulse III): 3 s- 600 mW/cm(2) + 2 min (delay) + 37 s -600 mW/cm(2). The media used were: distilled water, 75% ethanol and 100% chlorophorm. Five repetitions were made for each group. The specimens were placed in a desiccator at 37 masculineC for 24 h and, after that, at 23 masculineC for 1 h to be weighed until a constant mass (m1) was obtained. The discs were immersed separately into the 3 media for 7 days (G1) and 60 days (G2), and thereafter reweighed (m2). The reconditioning in the desiccator was done until a constant mass (m3) was obtained. Sorption and solubility were calculated and the data of G1 and the sorption data of G2 were subjected to two-way ANOVA and Tukey's tests (p=0.05). The solubility data of G2 were analyzed by Kruskal-Wallis test (p=0.05). For G1 and G2, no statistically significant differences were found in sorption among curing techniques (p>0.05). The solubility values were negative, which means that there was mass gain. Regarding the storage media, in G2 chlorophorm had the highest sorption values. It may be concluded that the curing modes (C and PD I, II and III) did not affect the sorption of the tested composite resin. However, different storage media influenced sorption behavior. The solubility test demonstrated negative data, masking the real solubility.

The effects of occlusal loading on the margins of cervical restorations.

BACKGROUND: Researchers have proposed the restoration of abfraction lesions, but limited information is available about the effects of occlusal loading on the margins of such restorations. Because abfraction is a well-recognized problem, the authors conducted a study to assess the effects of occlusal loading on the margins of cervical restorations. METHODS: The authors prepared 40 wedge-shaped cavities in extracted premolars and restored them with a resin-based composite. They subjected specimens to occlusal loading (150 newtons, 10(6) cycles) on the buccal cusp, on the central fossa or on the lingual cusp, and they stored the control group specimens in deionized water. The authors used fluorescein to delimit marginal defects and evaluated the defects by using laser scanning confocal microscopy. RESULTS: Results of chi2 and Kruskal-Wallis tests (P < .05) showed that specimens subjected to occlusal loading had a higher percentage of marginal gaps (53.3 percent) than did the control specimens (10.0 percent). There were no differences between groups in marginal defect formation or in defect location, length or width. CONCLUSIONS: Occlusal loading led to a significant increase in gap formation at the margins of cervical resin-based composite restorations. CLINICAL IMPLICATIONS: The clinician cannot underestimate the effects of occlusal loading when restoring teeth with cervical wedge-shaped lesions. If occlusal loading is the main factor contributing to lesion formation, the clinician should identify and treat it before placing the restoration or otherwise run the risk that the restorative treatment will fail because of marginal gap formation.