Knoop Microhardness and FT-Raman Spectroscopic Evaluation of a Resin-Based Dental Material Light-Cured by an Argon Ion Laser and Halogen Lamp: An in Vitro Study

Objective: The purpose of this study was to evaluate in vitro the Knoop microhardness (Knoop hardness number [KHN]) and the degree of conversion using FT-Raman spectroscopy of a light-cured microhybrid resin composite (Z350-3M-ESPE) Vita shade A3 photopolymerized with a halogen lamp or an argon ion laser. Background Data: Optimal polymerization of resin-based dental materials is important for longevity of restorations in dentistry. Materials and Methods: Thirty specimens were prepared and inserted into a disc-shaped polytetrafluoroethylene mold that was 2.0 mm thick and 3 mm in diameter. The specimens were divided into three groups (n = 10 each). Group 1 (G1) was light-cured for 20 sec with an Optilux 501 halogen light with an intensity of 1000 mW/cm(2). Group 2 (G2) was photopolymerized with an argon laser with a power of 150 mW for 10 sec, and group 3 (G3) was photopolymerized with an argon laser at 200 mW of power for 10 sec. All specimens were stored in distilled water for 24 h at 37 degrees C and kept in lightproof containers. For the KHN test five indentations were made and a depth of 100 mu m was maintained in each specimen. One hundred and fifty readings were obtained using a 25-g load for 45 sec. The degree of conversion values were measured by Raman spectroscopy. KHN and degree of conversion values were obtained on opposite sides of the irradiated surface. KHN and degree of conversion data were analyzed by one-way ANOVA and Tukey tests with statistical significance set at p < 0.05. Results: The results of KHN testing were G1 = 37.428 +/- 4.765; G2 = 23.588 +/- 6.269; and G3 = 21.652 +/- 4.393. The calculated degrees of conversion (DC%) were G1 = 48.57 +/- 2.11; G2 = 43.71 +/- 3.93; and G3 = 44.19 +/- 2.71. Conclusions: Polymerization with the halogen lamp ( G1) attained higher microhardness values than polymerization with the argon laser at power levels of 150 and 200 mW; there was no difference in hardness between the two argon laser groups. The results showed no statistically significant different degrees of conversion for the polymerization of composite samples with the two light sources tested.

Fiber-reinforced composite fixed dental prostheses: Studies of the materials used as pontics

Fiber-reinforced composite fixed dental prostheses – Studies of the materials used as pontics University of Turku, Faculty of Medicine, Institute of Dentistry, Department of Biomaterials Science, Finnish Doctoral Program in Oral Sciences – FINDOS, Annales Universitatis Turkuensis, Turku, Finland 2015 Fiber-reinforced composites (FRC), a non-metallic biomaterial, represent a suitable alternative in prosthetic dentistry when used as a component of fixed dental prostheses (FDPs). Some drawbacks have been identified in the clinical performance of FRC restorations, such as delamination of the veneering material and fracture of the pontic. Therefore, the current series of studies were performed to investigate the possibilities of enhancing the mechanical and physical properties of FRC FDPs by improving the materials used as pontics, to then heighten their longevity. Four experiments showed the importance of the pontic design and surface treatment in the performance of FRC FDPs. In the first, the load-bearing capacities of inlay-retained FRC FDPs with pontics of various materials and thicknesses were evaluated. Three different pontic materials were assessed with different FRC framework vertical positioning. Thicker pontics showed increased load-bearing capacities, especially ceramic pontics. A second study was completed investigating the influence of the chemical conditioning of the ridge-lap surface of acrylic resin denture teeth on their bonding to a composite resin. Increased shear bond strength demonstrated the positive influence of the pretreatment of the acrylic surfaces, indicating dissolution of the denture surfaces, and suggesting potential penetration of the monomer systems into the surface of denture teeth. A third study analyzed the penetration depth of different monomer systems on the acrylic resin denture teeth surfaces. The possibility of establishing a durable bond between acrylic pontics and FRC frameworks was demonstrated by the ability of monomers to penetrate the surface of acrylic resin denture teeth, measured by a confocal scanning type microscope. A fourth study was designed to evaluate the load-bearing capacities of FRC FDPs using the findings of the previous three studies. In this case, the performance of pre-shaped acrylic resin denture teeth used as pontics with different composite resins as filling materials was evaluated. The filling material influenced the load-bearing capacities, providing more durable FRC FDPs. It can be concluded that the mechanical and physical properties of FRC FDPs can be improved as has been shown in the development of this thesis. The improvements reported then might provide long lasting prosthetic solutions of this kind, positioning them as potentially permanent rehabilitation treatments. Key words: fiber-reinforced composite, fixed dental prostheses, inlay-retained bridges, adhesion, acrylic resin denture teeth, dental material.

Projecte per a la realització d'un vídeo pel crèdit 9 del cicle formatiu de grau mitjà : cures auxiliars d'infermeria : l'assistència en la clínica dental. 'Proyecto para la realización de un vídeo para el crédito 9 del ciclo formativo de grado medio : curas auxiliares de enfermería : la asistencia en la clínica dental'.

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Deposition of SiOx Thin Films on Y-TZP by Reactive Magnetron Sputtering: Influence of Plasma Parameters on the Adhesion Properties Between Y-TZP and Resin Cement for Application in Dental Prosthesis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spectroscopic study of ejected dental tissue after Er : YAG laser ablation

By means of IR spectroscopy, we determined the teeth ablation mechanism by an Er:YAG laser oscillating at 2.94 mum. Ejected dental material, ablated by the laser from human teeth, was deposited on an IR window and the absorption spectra were measured in the range 2500-20,000 nm. Sound teeth were used, and the corresponding film spectra were compared to spectra obtained by traditional methods. The films spectra obtained do not differ appreciably from those obtained by the traditional method for sound teeth, indicating that the material ejected by an Er:YAG represents the tooth condition.The obtained results confirm that a spectroscopic analysis of a tooth treated with an Er:YAG laser can be done measuring the absorbance of a film composed of ejected material without the need to slice it. In addition, we could determine that the laser absorption occurs mainly by the interstitial water, and the temperature elevation of the ejected material does not exceed 60degreesC. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Response of human dental pulp to dentin adhesive systems

Many in vivo studies have stated that the response of the dentin/pulp complex does not depend on the dental material used as the liner or pulp-capping agent. However, several in vitro studies have reported the metabolic cytotoxic effects of resin components applied to fibroblast and odontoblast cell lines. The aim of this study was to evaluate the human pulp response following direct pulp capping with current bonding agents and calcium hydroxide (CH). Sound premolars scheduled for orthodontic extraction had their pulp tissue mechanically exposed. After hemorrhage control and total acid conditioning, the experimental bonding agents, including All Bond 2, Scotchbond MP-Plus, Clearfil Liner Bond 2, and Prime & Bond 2.1 were applied on the pulp exposure site. CH saline paste was used as the control pulp-capping agent. All cavities were restored with Z-100 resin composite according to the manufacturer's instructions. Following extractions, the teeth were processed for microscopic evaluation. In the short term, the bonding agents elicited a moderate inflammatory pulp response with associated dilated and congested blood vessels adjacent to the pulp exposure site. A mild inflammatory pulp response was observed when Clearfil Liner Bond 2 or CH was applied on the pulp exposures. With time, macrophages and giant cells engulfing globules and components of all experimental bonding agents displaced into the pulp space were seen. This chronic inflammatory response did not allow complete pulp repair, which interfered with the dentin bridge formation. Pulp exposures capped with CH exhibited an initial organization of elongated pulp cells underneath the coagulation necrosis. CH stimulated early pulp repair and dentin bridging that extended into the longest period. The bonding agents evaluated in the present study cannot be recommended for pulp therapy on sound human teeth.

Effect of brushing with conventional versus whitening dentifrices on surface roughness and biofilm formation of dental ceramics

The aim of this study was to evaluate the effect of conventional and whitening dentifrices on the weight loss, surface roughness, and early in situ biofilm formation on the surface of dental ceramics. Standardized feldspar ceramic specimens (Vita VM7 and Vita VM13) were submitted to the following experimental conditions: no brushing; brushing without a dentifrice; brushing with a conventional dentifrice; and brushing with a whitening dentifrice. A brushing machine was used to simulate brushing. The mass and surface roughness of all specimens from the test groups were evaluated prior to and after brushing. Ten participants used an oral device for eight hours to evaluate the biofilm formed in situ on the specimens. Scanning electron microscopy was used for qualitative and quantitative analysis of the biofilm. ANOVA and Tukey tests were used to analyze the results of weight loss, surface roughness, and presence of bacteria. A one-way Kruskal-Wallis test was used for bacterial colonization results. For both ceramics, brushing with a whitening dentifrice resulted in weight loss that was significantly greater when compared to brushing without a dentifrice or with a conventional dentifrice. Increased surface roughness was noticed on VM13 ceramic samples with both dentifrices, whereas only conventional dentifrice had a significant effect on the surface roughness of VM7 samples. For both VM7 and VM13, no difference was found between the experimental conditions with regard to the presence or number of bacteria. Cocci and short rods were the predominant microbial morphotypes. Granular or fibrillar acellular material partially covered the specimens. Brushing with a whitening dentifrice resulted in significant weight loss of ceramic restorations, while brushing with both conventional and whitening dentifrices can roughen ceramic surfaces. The increase in roughness was not clinically significant to contribute to increased biofilm formation.

Dental students' familiarity with the medical management of dental patients at Brazilian dental schools

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Argon ion laser and halogen lamp activation of a dark and light resin composite: microhardness after long-term storage

The objective of this study was to evaluate in vitro light activation of the nano-filled resin composite Vita shade A1 and A3 with a halogen lamp (QTH) and argon ion laser by Knoop microhardness profile. Materials and methods: Specimens of nanofilled composite resin (Z350-3 M-ESPE) Vita shade A1 and A3 were prepared with a single increment inserted in 2.0-mm-thick and 3-mm diameter disc-shaped Teflon mold. The light activation was performed with QTH for 20 s (with an intensity of approximately 1,000 mW/cm(2) and 700 mW/cm(2)) and argon ion laser for 10 s (with a power of 150 mW and 200 mW). Knoop microhardness test was performed after 24 h and 6 months. The specimens were divided into the 16 experimental groups (n = 10), according to the factors under study: photoactivation form, resin shade, and storage time. Knoop microhardness data was analyzed by a factorial ANOVA and TukeyA ` s tests at the 0.05 level of significance. Results: Argon ion laser was not able to photo-activate the darker shade of the nanofilled resin composite evaluated but when used with 200 mW it can be as effective as QTH to photo-activate the lighter shade with only 50% of the time exposure. After 6 months storage, an increase in the means of Knoop microhardness values were observed. Conclusions: Light-activation significantly influenced the Knoop microhardness values for the darker nanofilled resin composite.

Laboratory evaluation of the physicochemical properties of a new root canal sealer based on Copaifera multijuga oil-resin

Aim To compare a new root canal sealer based on Copaifera multijuga oil-resin (Biosealer) using three other established sealers (Sealer 26 (R), Endofill (R) and AH plus (R)) in terms of their physicochemical properties. Methodology The study was carried out according to the requirements of Specification Number 57 of the American Dental Association (ADA) and consisted of the following tests: setting time, flow, film thickness, dimensional stability, radiopacity and solubility/disintegration. Data were analysed statistically using anova and Tukey`s test for multiple comparisons. The significance level was set at 5% for all analyses. Results Sealer 26 (R) and AH Plus (R) had the longest setting time (P < 0.05). All materials presented flow in with the ADA`s guidelines. Regarding film thick-ness, Sealer 26 (R) did not have a satisfactory performance, as it had a higher mean value than the maximum allowed by the ADA (0.05 mm), being significantly different from the other materials (P < 0.05), which had mean values for film thickness in accordance with the ADA`s recommendations. Regarding the solubility and disintegration, only Endofill (R) did not meet the ADA`s specifications and presented the worst results of all materials (P < 0.05). Sealer 26 (R) presented the greatest dimensional changes and differed significantly from all other sealers (P < 0.05). Biosealer had the lowest radiopacity values and was significantly different from the other sealers (P < 0.05). Conclusion The experimental sealer based on Copaifera multijuga oil-resin presented satisfactory results in the physicochemical tests required by the ADA.

Comparação dos valores de desgaste abrasivo e de microdureza de 13 resinas compostas usadas em odontologia através do método do disco retificado

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term evaluation of the pulpo-dentin complex response to a resin-modified glass-ionomer cement and a bonding agent applied in deep cavities

Objectives. To evaluate the response of the pulpo-dentin complex following application of a resin-modified glass-ionomer cement or an adhesive system in deep cavities performed in human teeth.Methods. Deep class V cavities were prepared on the buccal surface of 26 premolars. In Group I the cavity walls (dentin) and enamel were conditioned with 32% phosphoric acid and the dentin adhesive system One Step (Bisco, Inc., Itasca, IL, USA) was applied. In Groups 2 and 3, before total etching and application of bonding agent, the cavity floor was lined with the resin-modified glass-ionomer cement-Vitrebond (3M ESPE Dental Products Division, St. Paul, MN, USA) or the calcium hydroxide cement-Dycal (control group, Dentsply, Mildford, DE, USA), respectively. The cavities were restored using light-cured Z-100 composite resin (3M ESPE). The teeth were extracted between 5 and 30 days and prepared for microscopic assessment. Serial sections were stained with H/E, Masson's trichrome, and Brown and Brenn techniques.Results. In Group 1, the inflammatory response was more evident than in Groups 2 and 3. Diffusion of dental material components across dentinal tubules was observed only in Group 1, in which the intensity of the pulp response increased as the remaining dentin thickness decreased. Bacteria were evidenced in the lateral walls of two samples (Group 2) which exhibited no inflammatory response or tissue disorganization.Conclusions. Based on the experimental conditions, it was concluded total acid etching followed by application of One Step bonding agent cannot be recommended as adequate procedures. In this clinical condition the cavity walls should be lined with a biocompatible dental material, such as Vitrebond or Dycal. 2003 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Mechanical and biological characterization of resin-modified glass-ionomer cement containing doxycycline hyclate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biocompatibility of a resin-modified glass-ionomer cement applied as pulp capping in human teeth

Purpose: to evaluate the human pulp response following pulp capping with calcium hydroxide (CI-I, Group 1), and the resin-modified glass-ionomer Vitrebond (VIT, Group 2). Materials and Methods: Intact teeth with no cavity preparation were used as control Group (ICG, Group 3). Buccal Class V cavities were prepared in 34 sound human premolars. After exposing the pulps, the pulp capping materials were applied and the cavities were Filled using Clearfil Liner Bond 2 bonding agent and Z100 resin-based composite. The teeth were extracted after 5, 30, and from 120 to 300 days, fixed in 10% buffered formalin solution, and prepared according to routine histological techniques. 6-mu m sections were stained with hematoxylin and eosin, Masson's trichrome, or Brown gr Brenn technique for bacterial observation. Results: At 5 days, CH caused a large zone of coagulation necrosis, the mononuclear inflammatory reaction underneath the necrotic zone was slight to moderate. VIT caused a moderate to intense inflammatory pulp response with a large necrotic zone. A number of congested venules associated with plasma extravasation and neutrophilic infiltration was observed. Over time, only CH allowed pulp repair and complete dentin bridging around the pulp exposure site. VIT components displaced into the pulp tissue triggered a persistent inflammatory reaction which appeared to be associated with a lack of dentin bridge formation. After 30 days a few histological sections showed a number of bacteria on the lateral dentin walls. In these samples the pulp response was similar to those samples with no microleakage. VIT was more irritating to pulp tissue than CH, which allowed pulp repair associated with dentin bridge formation. These results suggested that VIT is not an appropriate dental material to be used in direct pulp capping for mechanically exposed human pulps.