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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Efeito da Adição de teobromina sobre as propriedades do cimento de ionômero de vidro / Vision effect of the theobromine about the properties of the glass ionomer cement

Fabricio Marcelo Cevallos Gonzalez 18 June 2018 (has links)
A proposta deste trabalho experimental in vitro foi avaliar se a incorporação de 1% - em peso - do alcalóide teobromina (Sigma Aldrich, Darmstadt, Alemanha) ao cimento de ionômero de vidro (CIV) convencional (GC Gold Fuji 9, GC Corp, Japão) tem a capacidade de alterar as propriedades físico-químicas desse material. Para tanto, dois grupos experimentais foram propostos: G1 - CIV convencional e G2 - CIV com adição de teobromina. Foram confeccionados 160 discos de CIV de acordo com as instruções do fabricante, utilizando matrizes circulares. Para analisar as mencionadas propriedades, os discos foram submetidos a testes específicos, de acordo com as normas da International Standard Organization (ISO) para cada uma das propriedades. Discos de 15mmx1mm de diâmetro foram utilizados para as provas de sorção (n=5) e de solubilidade (n=5), com o auxílio de balança analítica, dissecadores e estufa a 23 e 37ºC por várias semanas. O ensaio de microdureza foi realizado em amostras (n=20) de 15mm×1mm submetidas a cinco edentações, com carga de 25 gramas e 30 segundos, à temperatura ambiente. Para a avaliação da cor, discos (n=20) de 15mm×1mm foram submetidos ao espectrofotômetro, adotando-se a guia colorimétrica da Comissão internacional de Iluminação (CIE). No ensaio de resistência flexural, os espécimes (n=60) de 12mm×1mm foram armazenados em estufa a 37ºC durante 24 horas para posterior analise na máquina de ensaios universal. Para avaliar a influência da teobromina adicionada ao CIV na formação de biofilme por Streptococcus mutans,, sobre os corpos da prova (n=40) de 12mm×1mm biofilmes foram desenvolvidos. As cepas de S.mutans foram cultivadas em Tryptic Soy Agar (TSA, Difco) a 37°C. Também a dosagem de flúor foi avaliada, em discos de prova (n=10) armazenados em saliva artificial e submersos em solução TISAB para posterior análise com eletrodo de flúor e obtenção da curva da liberação dessa substância. Os dados obtidos nos testes de sorção e solubilidade, microdureza, cor e resistência flexural foram submetidos à análise de variância ANOVA um fator e ao teste de Tukey para comparação entre os grupos, adotando-se 5% de nível de significância (p<0,05). O ensaio da influência da teobromina adicionada ao CIV na quantidade de biofilme de Streptococcus mutans formado e o teste de dosagem de flúor foram submetidos à análise de variância two-way ANOVA e ao teste de Tukey, com nível de significância de 5% para comparação entre os grupos experimentais. O segundo fator avaliado nestes dois ensaios foi o tempo. Os resultados não revelaram alteração da sorção e da solubilidade no CIV que recebeu teobromina (p>0,05). A microdureza aumentou com a adição de teobromina ao CIV (p<0,05). Não houve alteração de cor do CIV que recebeu teobromina (p>0,05). A resistência na flexão biaxial diminuiu quando da adição de teobromina ao CIV (p<0,05). Já a quantidade de biofilme formado foi menor em G2 (p<0,05). Em relação à liberação de flúor, observou-se que a adição de teobromina não altera essa propriedade do CIV (p>0,05). Com base em tais achados, conclui-se que a adição de teobromina a 1% ao cimento do ionômero de vidro convencional não produz alterações significativas nas propriedades desse material, podendo até mesmo otimizar algumas dessas propriedades. Ainda assim, estudos adicionais sobre o assunto devem ser realizados. / The purpose of this experimental in virtro work, was to evaluate if the incorporation of the 1% in weight of an alkaloid: theobromine (Sigma Aldrich Darmstadt, Germany) to the conventional glass ionomer cement (GIC) (GC Gold Fuji 9; GCC Japan Corp) has the capacity to change the properties physicochemical of this material. Whereby, it was proposed two experimental groups: G1 - Conventional GIC and G2 GIC incorporated with theobromine. According to the instructions of the creator, there were created 160 specimens, for which it was used circular matrices. To analyze the mentioned properties, the specimens were analyzed under the International Standard Organization (ISO) for each property. It was used matrices of 15mmx1mm diameter for the sorption (n=5) solubility (n=5) tests. With the help of an analytical balance, desiccators and a stove at 23º and 37° for various weeks; it was made essays of micro firmness using 20 matrices of 15mmx1mm, were submitted to five indentations with a charge of 26 grams and 30 seconds in environmental temperature. For the color evaluation it was used 20 matrices of 15mmx1mm, that were submitted to a spectrophotometer following the colorimetric guide of the International Commission of Illumination (CIE). An essay of biaxial flexural strength was made in 60 matrices of 12mmx1mm that were stored in a stove at 37º for 24 hours, for a later analysis in a universal testing machine. To evaluate the influence of the theobromine incorporated to the glass ionomer cement (GIC) in the creation of biofilm Streptococcus mutans, there were developed 40 matrices of 12mmx1mm of biofilm. The strains of the Streptococcus mutans were cultivated in Tryptic Soy-Agar at 37°. It was also evaluated the fluorine release capacity using 10 test matrices stored in artificial saliva and submerged in TISAB substance for a later analysis with an fluorine electrode, to obtain the release curve of that substance. The obtained information from the test of sorption, solubility, micro strength, color and biaxial flexural strength, were submitted to an analysis of variance ANOVA one factor and Tukey\'s test for a comparison between groups assuming the 5% level of significance (p <0,05). The essay of the influence of the theobromine added to the GIC in the amount of biofilm Streptococcus mutans formed and the test of fluorine release were submitted to the Bidirectional Variance Analysis ANOVA and Tukey\'s test, with a significant level of 5% to the comparison between experimental groups; the second factor evaluated in this two essays was time. The results didn\'t show an alteration in the sorption and solubility in the GIC that received theobromine (p >0,05). The micro strength increased with the addition of the theobromine to the GIC (p< 0,05). There were not any alterations in the color of the GIC that received theobromine (p >0.05). The resistance to the biaxial flexural strength decreased when the theobromine was added to the GIC (p <0.05). The amount of formed biofilm was less in the G2. In relation to the fluorine release it was observed that the addition of theobromine does not change the properties of GIC (p >0.05). Based on these findings, it is concluded that the addition of theobromine in 1% to the conventional glass ionomer cement, does not produce significant changes over this material properties and also, it can optimize some of these properties. However, more studies should be done about this topic.
32

Micro-leakage and Enamel demineralisation : a comparative study of three different adhesive cements

Elshami, Marrow January 2016 (has links)
Magister Scientiae Dentium - MSc(Dent) / Introduction: Micro-leakage and enamel demineralization is still a major challenge in dental practice. It can lead to formation of demineralization lesions around and beneath the adhesive–enamel interface (Mali et al., 2006). Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. The prevention of demineralization during orthodontic treatment is therefore essential for aesthetic reasons and to circumvent the onset of caries. Aim: To assess micro-leakage and enamel demineralization around orthodontic direct attachments (brackets) using three different orthodontic cements. Materials and methods: In this in-vitro study, intact (non carious) extracted human premolars were used to compare the micro-leakage and enamel demineralization of three different cements (Fuji Ortho LC, Rely X luting 2 and Transbond XT). The dye penetration technique was used to evaluate micro-leakage on extracted human premolars. Micro-hardness testing was performed on 21 teeth to determine enamel demineralization. Sixty teeth were randomly divided into 3 groups of twenty teeth each. Direct attachments were cemented on each tooth using 3 different cements; Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan), (group 1), Rely X luting 2 cement (3M ESPE dental product, USA), (group 2), Transbond XT Light Cure (3M Unitek, Monrovia, Calif), (group 3). After the orthodontic direct attachments were fitted, they were exposed to 500 thermo-cycles between 5°C and 55°C, with a dwell time of 15 seconds in a buffered (pH 7) 1% methylene blue dye solution (Grobler et al, 2007). The specimens were viewed under a stereomicroscope (Nikon, Japan) at magnification of 40 times. Photographs of each specimen were taken with a Leica camera (Leica DFC 290 micro-systems, Germany) fitted onto a stereomicroscope. The ACDsee photo editing programme was used to transfer the photographs to a computer to measure the dye penetration along the enamel–adhesive and adhesive–bracket interfaces, both on the gingival and occlusal edge at × 40 magnification. For the demineralization sample, 21 teeth were divided into 3 groups of seven teeth each, where direct attachments were cemented using each of the 3 cements, group 1, Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan); group 2, Rely X luting 2 cement (3M ESPE dental product, USA) and group 3, Transbond XT Light Cure (3M Unitek, Monrovia, Calif). A digital hardness tester with Vickers diamond indenter (Zwick RoellIndentec (ZHV; Indentec UK) was used to measure surface micro-hardness of enamel before and after attaching the brackets. Ten indentations were made on the enamel surface of each tooth before bonding the brackets with a 300g load applied for 15 seconds to establish the baseline hardness value. After de-bonding the brackets, the hardness was measured again in the same area as mentioned above to determine the degree of enamel demineralization (softening). Result: The result showed statistically significantly lower levels of micro-leakage for Transbond XT (P= <0.001). The amount of micro-leakage on the margins was significantly higher in the gingival portion (P <0.05) as compared with the occlusal margin. Enamel micro-hardness tests before bonding using the three different cements showed that the variances are not significantly different (Chi-squared = 3.051, df = 2, p-value = 0.218). However, the micro-hardness tests done after bonding and thermo-cycling was statistically significantly different (Chi-squared = 13.435, df = 2, p-value = 0.001). Clearly, the Transbond XT group had less hardness, implying greater demineralization than the Fuji Ortho LC and Rely X luting 2 groups. Two sample t-tests show that mean value for the Fuji Ortho and Rely X luting 2 were not significantly different from each other (t = -0.636, df = 12, p-value = 0.537). The mean value for Transbond XT differed significantly from both the other two means: Transbond XT vs Fuji Ortho LC (t = 3.249, df = 6.9, p-value = 0.014). Transbond XT vs Rely X luting 2 (t = 3.493, df = 6.8, p-value = 0.011). Conclusions: This study showed that Fuji Ortho LC and Rely X luting 2 show more micro-leakage than Transbond XT. However Transbond XT had significant lower micro-leakage, less hardness (greater demineralization) than the Fuji Ortho LC and Rely X luting 2. This may have been due to the fluoride release which significantly reduces demineralization. Therefore the Fuji Ortho LC and Rely X luting 2 may be recommended for prevention of demineralization during orthodontic treatment.
33

Fragment reattachment with light-cured glass-ionomer

Minutillo, Anthony L., 1965- January 1996 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This investigation examined the relationships among light cured glass ionomer liner, light cured glass ionomer base, and composite resin material in the reattachment of fractured anterior tooth fragments. Seventy-five bovine incisor teeth were fractured and luted back together with three different materials (Universal Bonding Agent/TPH Composite Resin; VariGlass VLC Liner; VariGlass VLC Base, LD Caulk Div Dentsply Int Inc, Milford, DE) of equal number. The reattached fragments were subjected to thermocycling with a 40° C differential and then were loaded until the force required to detach the fragment was reached. The mean dislodgment strengths were 36.8 (± 25.6)kg for the composite resin, 36.4 (± 26.7)kg for the glass ionomer base, and 31.4 (± 29.S)kg for the glass ionomer liner. Analysis of variance demonstrated no significant difference between the three groups at p≤0.05. Also examined was the type of fracture after reattachment. Of the sixty-five teeth that were studied microscopically, 84.6 percent of the fractures were cohesive in nature, thus a breakdown occurred within the material itself.
34

Evaluation of the Tensile Bond Strength of Orthodontic Bracket Bases Using Glass Ionomer Cement as an Adhesive

Burns, Richard D., Jr. January 1992 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The search for an orthodontic bonding adhesive that has chemical adhesion to enamel and releases fluoride into the oral environment has led to experimentation with glass ionomer cements. This study compared the tensile bond strength of eight different orthodontic bracket base designs in vitro and assessed the amount of adhesive remaining on the bracket pad after debonding. Each bracket base design included in this study had unique characteristics warranting their inclusion. The groups contained brackets with 60, 80, and 100 gauge mesh pads; 100 gauge mesh sandblasted pads; perforated metal bases; Micro-Lock™ photo-etched bases; Dyna-Lock™ integral bracket/bases; and ceramic silane-coated bracket pads. Groups contained 20 to 22 specimens that were bonded to bovine incisor teeth embedded in a self-curing acrylic block that could be held in the testing machine. Pre-encapsulated glass ionomer cement (Ketac-Fil™) was the experimental adhesive. The adhesive was mixed according to the manufacturer's instructions in a dental amalgamator. The specimens were thermocycled between water oaths of 15°C and 55°C. The specimens spent 30 seconds in each bath for a total of 2,500 cycles and were stored in a humidor until debonding. After 14 days, the specimens were subjected to a tensile force using an Instron mechanical testing machine until failure occurred. The Micro-Loc™ photo-etched base had significantly higher mean tensile bond strength (p<0.05) than all other brackets tested. The ceramic brackets were unable to be tested due to the extremely weak bond strength which did not allow preparation of the samples for debonding. Following debonding, the percentage of adhesive remaining attached to the bracket base was determined using a grid in the ocular of a light microscope. In general, the site of bond failure involved the base/adhesive interface. The Dyna-Lock™ integral bracket/base and 80 gauge mesh base had a greater mean percent of adhesive remaining attached to the base. (Dyna-Lock™ 45 percent and 80 gauge mesh 43 percent vs. all other < 20 percent.) The results indicate that the bracket base design can influence the bond strength when GIC is used as an orthodontic adhesive and suggests that development of GIC with increased fracture toughness might increase bond strength.
35

AN INVESTIGATION OF EFFECTS OF NOVEL POLYMERIC STRUCTURES ON PHYSICAL PROPERTIES OF CONVENTIONAL GLASS-IONOMER CEMENTS

Moshaverinia, Alireza 22 July 2009 (has links)
No description available.
36

Longevity of Crown Margin Repairs Using Glass Ionomer: A Retrospective Study

Watson, Justin I. January 2020 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Objectives: Repair of crown margins may extend the functional life of existing crowns. However, the longevity of such treatment is unknown. This study determined the survival time of crown margin repairs (CMR) with glass-ionomer (GI) and resin-modified glass-ionomer cements. Methods: We queried axiUm (Exan Group, Coquitlam, BC, Canada) database for permanent teeth that underwent CMR in the Graduate Operative Dentistry Clinic, Indiana University School of Dentistry (IUSD), Indianapolis, Ind., USA, from January 1, 2006 through January 1, 2018. Since there is no CDT code for the CMR procedure, CDT codes for resin-composite and GI restorations (D23XX) were queried; these patients also had treatment notes that indicated CMR. The final data set included patient ID, birth date, gender, dates of treatments, CDT codes, tooth type, tooth surface and existing findings. Two examiners developed guidelines for record review and manually reviewed the clinical notes of patient records to confirm CMR. Only records that were confirmed with the presence of CMR were retained in the final dataset for survival analysis. Survival time was calculated by Kaplan-Meier statistics and a Cox Proportional Hazards model was performed to assess the influence of selected variables (p < 0.05). Results: 214 teeth (115 patients) with CMR were evaluated. Patient average age was 69.4  11.7 years old. Posterior teeth accounted for 78.5 percent (n = 168) of teeth treated. CMRs using GI had a projected 5-year survival rate of 62.9 percent (K-M Analysis) and an 8.9 percent annual failure rate. Cox Proportional Hazards Regression analysis revealed that none of the factors examined (age, gender, tooth type) affected time to failure. Conclusion: CMRs may extend the longevity of crowns with defective margins. Larger EHR studies or case control studies are needed to investigate other variables, such as the caries risk status or the severity of defects that may affect the survival rate of CMRs.
37

The pharmacological management of dentine to protect against plaque microorganism degradation.

Knight, Geoffrey Macdonald January 2008 (has links)
Background There is a transition towards minimally invasive restorative techniques in restorative dentistry based upon reducing bacterial viability and encouraging remineralization of caries infected tissue. To improve the predictability of the antibacterial and remineralization potential of carious dentine by either the application of medicaments or placement of restorative materials that encourage remineralization would be a significant benefit in disease management. Materials and Methods An experimental model was developed using a chemostat for in vitro analysis of the effects of silver fluoride followed by potassium iodide (AgF/KI) and ozone treatment on non demineralized and demineralized dentine. Electron Probe Micro Analysis (EPMA) and Scanning Electron Microscopy (SEM) on the treated dentine were conducted to investigate ion transfer, and biofilm formation. Bacteria growth was measured by optical density. An in vitro caries model using a chemostat was developed to determine the ability of glass ionomer cement and composite resin to inhibit dentinal degradation in adjacent dentine and to measure ion exchange at the restorative interface. Tests were made to determine the bond strength between dentine and glass ionomer cement after application of silver fluoride to the surface of the dentine. Results S. mutans migrated through all dentine samples. Samples treated with AgF/KI had significantly lower optical densities than the corresponding controls. Optical density readings were significantly lower in demineralized dentine treated with AgF/KI than non demineralized dentine. There were lower but not significant differences in the optical density readings between ozonated and non ozonated dentine. An S. mutans biofilm covered all control discs. No biofilm was detected on discs treated with AgF/KI and these discs were significantly more resistant to further demineralization than the control discs. Detectable amounts of silver and fluoride were found up to 450 μm in the AgF and AgF/KI sections. Ozone infusion prevented S. Mutans and L. acidophilus biofilm formation on all the treated dentine samples, biofilm was present on all control specimens. There was calcium and phosphorus present in all auto cure glass ionomer cements to a depth beyond 50 microns. Aluminium and strontium ions were also present in dentine except strontium subjacent to Ketac Molar restorations. Fluoride uptake was significantly higher under glass ionomer cement restorations where the dentine was pretreated with AgF/KI compared to non treated specimens. Silver and iodine deposits were present in demineralized dentine treated with AgF/KI. Calcium and phosphorus levels up to 130 microns from the restorative interface were similar to non demineralized dentine adjacent to auto cure glass ionomer cements and half that adjacent to composite resin. There was significant surface degradation in auto cure glass ionomer cements compared to composite resin. Washing away the AgF/KI precipitate produced higher bond strengths to dentine than samples where the precipitate remained. Conclusions Under the conditions of these in vitro studies, the application of AgF/KI and ozone pharmacologically reduces the initiation and rate of dentine caries. Glass ionomer cements were shown to protect dentine from experimental carious degradation and assist with remineralization. AgF/KI application enhances remineralization beneath glass ionomers and does not interfere with bond strengths. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1344616 / Thesis (Ph.D.) - University of Adelaide, Dental School, 2008
38

Comparative in vitro study of selected physical properties of Activa, Cention N and Vitremer

Khair, Ro’aa Mohammed Jafar Mohammed Mohammed January 2021 (has links)
Magister Chirurgiae Dentium (MChD) / Background: This study aimed to determine the association between dimensional change and surface roughness (Ra) of Vitremer, Activa and Cention N after immersing them into two different media: acidic and artificial saliva media for the period of a year. Measurements were made at 10 time intervals during the observation period. Methodology: This was a quantitative and qualitative study. For the quantitative part, a total of 60 specimens were tested, 20 specimens for each material. The 20 specimens were further divided into 10 specimens. Ten were immersed in acidic media and the rest in saliva media. A measurement of the weight, height, and Ra was carried out as follows: day 0, day 1, day 2, day 7, day 21, day 28, day 60, day 90, day 180 and day 365. Scanning electron microscopy (SEM) was used to examine the surface of each material qualitatively pre and post immersion in the two media. For fluoride measurements, an additional five samples from each material were left suspended in the de-ionized water by the use of dental floss. The materials were moved to new specimen jars after the completion of day 1, 2, 3, 4, 5, 6, 7, 14, 21 and 28. All the specimen jars had been kept for the fluoride measurements. Results: Non-parametric tests were used to analyze the data. Linear regression analysis was used to measure the association between weight, height or surface roughness (Ra) and immersion time for a year. The result of this test showed that Vitremer had a significant association between the weight (p = 0.000), height (p = 0.007) and Ra (p = 0.001) when it was immersed in acidic media. On the other hand, when Vitremer was immersed in saliva media, only the weight variable showed a significant association (p = 0.002). For Cention N, significant association was found for only Ra when immersed in acidic media (p = 0.000). Finally, for Activa, all the studied associations; the weight, height and Ra in both media were found to be insignificant. For saliva media, there was a significant weight change between the three materials during all 10 periods of time (p = 0.000). In the first six months, Cention N demonstrated a significant increase in weight changes followed by Vitremer, then Activa. Yet, after a year, the difference between Cention N and Vitremer became insignificant and Activa showed the least weight changes. There was not a significant difference between the materials in terms of height and Ra measurements. The fluoride experiment was not successful due to technical issues during pH measurements of the collected solutions. For comparison of the studied parameters between the three materials, the Kruskal-Wallis test was used. In acidic media, there was a significant difference between the materials in term of weight change in 10 periods of time (p = 0.000). In particular, after a two month period, Cention N had the highest weight, followed by Vitremer and then by Activa. The difference between Vitremer and Activa became insignificant throughout the rest of the experimental time frame. All the height measurements between the three materials were found to be insignificant except for day 365 (p = 0.048), where both Activa and Cention N were found to be significantly higher than Vitremer. For the Ra comparison, in the first two weeks, particularly day 1, 7 and 14, Cention N had significantly the lowest Ra among the other materials. As the three materials aged in the acidic media (day 180), Vitremer had significantly the highest Ra values. Cention N showed higher Ra values than Activa; nonetheless this difference was not significant. The SEM images showed loss of some particles in all post-experimental images of the materials in acidic media. Vitremer showed the widest cracks with the loss of fillers. In saliva media, there was also loss of particles but to a lesser extent than in acidic media. Yet, the post-experimental image of Activa in saliva resembled the pre-experimental one. Conclusion: Within the limitations of the study, the best material to resist Ra from prolonged acidic attack was Activa followed by Cention N and then Vitremer. Except for Vitremer, no significant changes in the Ra of the other materials were detected when the three materials were immersed in saliva media in the long term. In acidic media Vitremer tended to lose weight and height faster than Cention N and Activa over a year. Cention N is the best material to resist dimensional change. However, in artificial saliva Vitremer gained water rapidly. Activa did not absorb a lot of water and did not reject a lot of water; Activa demonstrated good dimensional stability and this property may be beneficial when compared to the other two materials tested. The clinical significance of the study: All the materials studied were subjected to dimensional and Ra changes following long-term exposure to acidic substances, but the newer materials (Cention N and Activa) seemed to be more dimensionally stable and resistant to Ra changes than the older, well-known material (Vitremer). This may influence a clinician’s choice of restorative material for use in pediatric dentistry.
39

Enamel conditioning effect on penetration and microleakage of glass ionemer-based sealants

Ahmed, Senan Raad January 2009 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / While most sealants available are resin-based, glass ionomer-based cements can be used as sealants, with the advantage of being more tolerant to moisture during placement and of releasing fluoride. The objective of this study was to evaluate the influence of different fissure conditioning techniques on penetration and microleakage of glass ionomer (GI) and resin-modified glass ionomer cements (RMGI) used as sealants. Clinically sound extracted human molars were distributed into nine experimental groups (n = 15 each). Group 1 (control) was sealed with resin-based sealant (Delton) following clinically accepted techniques. Groups 2 through 6 were sealed with RMGI (Vitremer) after having the fissure conditioned with either polyacrylic acid (RMGI-control), 35-percent H3PO4, low viscosity 35-percent H3PO4 with a surfactant, self-etch conditioner, or 35-percent H3PO4 followed by self-etch conditioner. Groups 7 through 9 were sealed with GI sealant (Fuji Triage) after having the fissures conditioned with either polyacrylic acid (GI-control), 35- percent H3PO4 or low viscosity 35-percent H3PO4 with a surfactant. After aging through thermocycling (2500 cycles), specimens were incubated in methylene blue for four hours and sectioned at multiple locations. Digital images were obtained using a digital stereomicroscope, and microleakage was determined by scoring the dye penetration along the enamel-sealant interface. The penetration of the material was determined by calculating the percentage of the total length of the fissure penetrated by the material. Results: The use of self etch-conditioner significantly increased RMGI penetration, while surface conditioning with 35-percent phosphoric acid with surfactant significantly decreased microleakage of GI. The resin-based sealant placed after 35-percent phosphoric acid surface conditioning showed the best penetration and the least level of microleakage. In conclusion, results from this study suggest that the placement of glass ionomer-based sealants can be enhanced by modifying current conditioning methods.
40

In-vitro wear and hardness of new conventional glass ionomer cement coated with nano-filled resin

AlJamhan, Abdullah Saleh January 2011 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Background: Since the introduction of glass ionomer cements (GICs) in the 1970s, many attempts have been made to improve them and expand their application in restorative dentistry. Recently, GC America introduced a new glass ionomer restorative system called EQUIA. The manufacturer claims that this material has improved wear resistance by coating the surface of high-strength GIC with a nano-filled resin coating. Objective: The objective of this study was to measure the wear resistance and hardness of EQUIA and to compare it to other current restorative materials. Materials and Methods: Four different materials were used in this study: EQUIA, Fuji IX GP Extra, Fuji II LC and Z-100. Six specimens of each material were made and then tested in a toothbrush abrasion machine for 20,400 cycles, after which the amount of volume loss was calculated. Eight specimens of each material were made and tested in a three-body Alabama wear testing machine under a load of 75 N for 400,000 cycles. Four surface profiles were obtained from each specimen and volume loss was calculated using computer software. Five specimens of each material were made and Knoop microhardness was determined by using the mean of the three values from the top surface of the specimen. Results of each test were collected and compared with the other materials using one-way analysis of variance (ANOVA) at a significance level of 0.05. Results: Wear-resistance results showed that EQUIA has wear-resistance values comparable to composite resin and higher values than those for the high-strength GIC. The results also showed that Fuji II LC had the highest wear among all tested materials. Microhardness results showed that EQUIA has significantly lower microhardness than Fuji IX GP Extra and Z-100. Conclusion: Based on the results of the present study, it can be concluded that coating the surface of glass ionomer restorations with a nano-filled resin coat results in increasing the wear resistance and decreasing the microhardness of the material. Within the limitations of this study, EQUIA has comparable wear resistance to composite resin.

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