<p>The aim of this laboratory based study is to assess the efficiency of a tooth bleaching agent by measuring the degree of color change with a spectrophotometer (Konica Minolta, CM 2600d) and not by the usual subjective visual guide methods. Objectives of the study are: To determine tooth shade with a spectrophotometer prior to staining the tooth (baseline). To determine which insult causes the most discoloration numerically. To measure the efficiency of the bleaching agent used in the study with periodic color change pectrophotometer readings.&nbsp / To assess if the baseline tooth shade can be regained by the bleaching agent.</p>

AIM: To analyze staining properties of aesthetic brackets. MATERIAL & METHODS: A total of 400 tooth-coloured brackets from 10 brands 5 ceramic and 5 plastic) were investigated. Cumulative effects of staining agents were analyzed at simulated light and heavy consumption levels. Study groups were immersed in the staining agents consecutively at 37°C. The control group was exposed to artificial saliva. Samples were analyzed digitally to obtain the L*, a*, and b* (lightness, red-green, and yellow-blue) colour readings. Using these values total colour change (ΔE*) was also calculated. A general linear model (ANOVA) test was used for statistical comparisons. RESULTS: Significant differences were observed in L*, and b* values of ceramic brackets at all consumption levels (p≤.0001). All values had significant differences amongst the plastic brackets (p≤.0001), except for L* with heavy exposure. Total ΔE* values for ceramic and plastic brackets were 11 and 26, respectively. CONCLUSIONS: Both plastic and ceramic brackets showed changes in colour when exposed to staining agents, with plastic brackets being the most affected.

AIM: To analyze staining properties of aesthetic brackets. MATERIAL & METHODS: A total of 400 tooth-coloured brackets from 10 brands 5 ceramic and 5 plastic) were investigated. Cumulative effects of staining agents were analyzed at simulated light and heavy consumption levels. Study groups were immersed in the staining agents consecutively at 37°C. The control group was exposed to artificial saliva. Samples were analyzed digitally to obtain the L*, a*, and b* (lightness, red-green, and yellow-blue) colour readings. Using these values total colour change (ΔE*) was also calculated. A general linear model (ANOVA) test was used for statistical comparisons. RESULTS: Significant differences were observed in L*, and b* values of ceramic brackets at all consumption levels (p≤.0001). All values had significant differences amongst the plastic brackets (p≤.0001), except for L* with heavy exposure. Total ΔE* values for ceramic and plastic brackets were 11 and 26, respectively. CONCLUSIONS: Both plastic and ceramic brackets showed changes in colour when exposed to staining agents, with plastic brackets being the most affected.

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: [37]-41)

Thesis--Catholic University of America. / Bibliography: p. 30-31.

Determining the depositional environment and the postmortem alterations to a set of remains are aspects of forensic investigations that are necessary to explain the circumstances surrounding the death of the individual. Further research on the taphonomic agents that can impact skeletal material can aid in the differentiation between various postmortem alterations that impact a single set of remains. The present study focuses on organic staining as a method for reconstructing the deposited environment of the remains and the taphonomic agents in which they came into contact. Organic staining results largely from tannins leaching from plant materials, including wood and leaves, and therefore can be seen on bone deposited in wooden coffin environments or on terrestrial surfaces. The present study hypothesized that the degree of staining observed on skeletal elements would increase as the length of exposure to the organic matter increased and that different plant materials, and environments, would leave different patterns or colorations of staining. The skeletal elements consisted of 150 commercially available pig (Sus scrofa) femora that had the epiphyses removed and were completely defleshed without utilizing chemicals or boiling. The sample was divided into three groups with differing conditions and/or types of organic material introduced. Some were buried in a marshy environment within wooden boxes constructed of ten wood types commonly utilized in coffin construction throughout U.S. history: hickory (Carya sp.), walnut (Juglans sp.), cherry (Prunus sp.), soft maple (Acer sp.), mahogany (Swietenia sp.), yellow pine (Pinus sp.), poplar (Populus sp.), cedar (Cedrus sp.), oak (Quercus sp.), and spruce (Picea sp.). Additional femora were deposited in plastic containers lined with the same wood types as above and filled with tap water. Five control bones were deposited in a container with tap water and five additional bones were placed in a container with commercial tannic acid. The final group of femora was deposited on the ground surface surrounded by four types of dead vegetation: evergreen pine needles (Pinus strobus), northern red oak leaves (Quercus rubra), sugar maple leaves (Acer saccharum), and acorns (Quercus rubra) collected from the Boston area. The bones were removed once a month from their experimental environments and left overnight to dry. The level of staining that manifested on the osseous material was recorded qualitatively using the Munsell Soil Color Chart under a consistent indoor 40- watt daylight light bulb. The staining was recorded after two months upon initiation of the study and every following month until the study’s completion. After the color staining was recorded, the bones were returned to their experimental environments until the next interval of data collection. An additional sample of 15 bones, which were previously buried with direct soil contact, was also analyzed. These bones were either buried within the O, A, or C soil horizons for an interval of 1, 2, or 3 years prior to analysis. They were photographed and the staining was classified on one occasion after which the bones were permanently withdrawn and not returned to the experimental environment. In all of the experimental environments, staining was present after two months of exposure, and the color darkened across the bone surface with each episode of data collection. Both groups exposed to the wood types displayed staining across the entire bone surface with a few major colors on the bone shaft, while minor colors were only expressed along the margins or as small patches along the shaft. As the buried boxes began to break down, which is commonly observed in coffin burials, soil was able to infiltrate the boxes and contact the bones. This process resulted in multiple shades of brown to be present in the staining across bones in multiple wood types. The bones in the plastic containers with wood exhibited a larger variation in color staining likely due to a higher concentration of tannins restricted to a smaller area around the bones combined with a lack of water inflow. The staining ranged from red for bones with mahogany to brown for bones with cedar to even dark gray or black on bones with walnut and tannic acid, respectively. The bones in plant matter differed in that the organic staining was sporadic, often with large areas of very pale brown or yellowish brown coloration and with smaller patches of shades of darker brown. The staining present on the buried soil bones was intermediate to the other samples, in that it was diffuse across the shaft with a large range of colorations present. The results from the present study indicate that staining can manifest on bone within a relatively short time frame once skeletonization occurs and a variety of colorations or patterns of staining can manifest based on the plant material. The present research demonstrates the potential of organic staining to aid in estimations of the postmortem interval as well as an environmental reconstruction through species identification.

Resumo: O objetivo deste estudo foi avaliar a influência da fonte de luz na estabilidade de cor da resina composta nanoparticulada Filtek Supreme submetida a diferentes meios e tempos de imersão. Para isso, foram utilizadas três fontes de luz: um LED UltraLume LED 5/ UltraDent; um aparelho de lâmpada halógena convencional - Curing Light XL 3000/ 3M/ESPE; e um de luz halógena de alta densidade de potência - Jet Lite 4000 Plus/ JMorita. Os espécimes (n=180) foram confeccionados em matriz de metal circular (10mm x 2mm) apoiada em placa de vidro e tira de poliéster. A resina composta foi inserida na matriz num único incremento e fotoativada por 40 segundos. Os espécimes foram divididos em três grupos (equipamento de fotopolimerização) e quatro subgrupos experimentais (meios de imersão: café, Coca-Cola®, chá e saliva artificial). Os espécimes permaneceram imersos em saliva artificial por 24 horas e foram submetidos à análise da cor no espectrofotômetro de colorimetria (CB-6807 color-guide /BYK-Gardner) pelo sistema CIELab. A partir desse período, passaram a ser mergulhados nos diferentes meios por cinco minutos, três vezes ao dia, por 60 dias, e nos intervalos foram mantidos em estufa à 37°C ± 1°C. A leitura da alteração de cor foi realizada após 24 e 48 horas, 7, 14, 21, 30 e 60 dias do início da imersão. Os dados foram analisados pelo teste não-paramétrico Kruskall-Wallis para os fatores fonte de luz e meio de imersão (p<0,05), enquanto, para o fator tempo, utilizou-se o teste ANOVA a dois critérios e o teste de Fisher (p<0,05). Os resultados mostraram que, para o fator fonte de luz, o Ultralume LED 5 apresentou a menor alteração de cor em comparação aos aparelhos halógenos. Em relação ao meio de imersão, o café mostrou a maior alteração de cor e de luminosidade (ΔE=8,40; _L=-5,21), a Coca-Cola® apresentou os menores valores... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the influence of light sources on color stability of a composite resin and the effect of immersion media. In this test, three light sources were used: a conventional halogen curing light unit (XL3000 - 3M/ESPE), a high power density halogen unit (Jet Lite 4000 Plus - JMorita) and a high power density LED unit (Ultralume LED 5 - Ultradent). There were four media immersion: coffee, tea, Coke® and artificial saliva. One nanofilled composite resin was selected: Filtek Supreme. A stainless steel matrix (10mmx2mm) was used to prepare 180 specimens. After this, all specimens were immersed in artificial saliva for 24hs at 37oC ± 1ºC and its initial color was measured with a spectrophotometer (Color Guide 45/0, BYKGardner) by CIELab system. Then, the specimens were divided into 4 subgroups according to each medium and were immersed in the respective medium three times a day during 5 minutes for 60 days. Color changes were recorded after 24hs, 48hs, 7, 14, 21, 30 and 60 days of immersion. Data from the color change and luminosity were analyzed and subjected to Kruskall-Wallis test to light source and immersion media factor (p<0,05). To immersion time, data were subjected to two-way ANOVA test and Fisher's test (p<0,05). The light source that more contributed to color stability was Ultralume LED 5. In relation to solutions, coffee caused an intense color alteration (ΔE=8,40; ΔL=-5,21) and Coke® showed the lowest color changes (ΔE=1,43; ΔL=0,36). Then, it might be concluded that Ultralume LED 5 was the light-curing unit that allowed better color stability and coffee was the immersion medium that promoted the highest influence on color stability of the studied composite resin. / Orientador: Patrícia Petromilli Nordi Sasso Garcia / Coorientador: Regina Guenka Palma-Dibb / Banca: Flávia Magnani Bevilacqua / Banca: Silmara Aparecida Milori Corona / Banca: Marcelo Ferrarezi de Andrade / Banca: Welingtom Dinelli / Doutor

Magister Scientiae Dentium - MSc(Dent) / Summary: Aim: The aim of this laboratory study is to assess the efficacy of a tooth bleaching agent by evaluating the degree of color change with the use of a spectrophotometer and not by the usual subjective, visual methods. Methodology: Twenty specimens of human teeth will be collected, polished and divided into two groups. A baseline color measurement by the CIE L* a* b* with a spectrophotometer against a white background will be taken before one group is immersed in coffee and the other in red wine for two weeks. Bleaching of the specimens will be done according to manufacturer’s instructions for two weeks. Color readings will be taken before bleaching, weekly during bleaching and 1 and 2 weeks after the bleaching treatment. Color change (ΔE) will be calculated mathematically as Δ E = [ (Δ L*)2 + (Δ a*)2 + (Δ b*)2 ]1/2. An observation of whether the baseline color reading will be regained by the bleaching process will be made. Results: Data collected will be recorded on an Excel spreadsheet. Advice from a qualified statistician will be sought to analyze the data. Results will be discussed in comparison with the existing literature on this subject. / South Africa

Purpose: Solution-induced corneal staining (SICS) has been the subject of much debate in the clinical literature. While it has been suggested that this form of staining indicates toxicity of the cornea, microscopy studies have suggested that cells treated with multi-purpose solutions (MPS) known to produce SICS in vivo are undamaged. There is further debate in the literature as to whether or not sodium fluorescein (‘fluorescein’) actually enters epithelial cells or not. The aim of this work was to investigate the cellular mechanisms involved in SICS by developing an in vitro cell culture model to mimic the clinical presentation of this phenomenon. Methods: An in vitro model of SICS was developed using cultured cells that were exposed overnight to ReNu MultiPlus® (Bausch + Lomb) MPS. After addition of fluorescein, cells were imaged using an automated fluorescence microscope. Hyperfluorescent cells were identified using predetermined threshold of intensity in fluorescence microscope, and confocal microscopy was used to investigate where fluorescein was situated within the cells. The extent of cell toxicity was assessed using propidium iodide and Annexin V. In order to examine the contribution of passive and active transport mechanisms in fluorescein uptake and release, levels of hyperfluorescent staining were measured at 37°C and 4°C. In all described experiments, fluorescein staining was expressed by the proportion of hyperfluorescent cells in the total cells. Results: All cultured cells readily took up fluorescein at room temperature, however a sub-population of cells stained more intensely with fluorescein. These cells were termed ‘hyperfluorescent’ cells. Exposure to ReNu MultiPlus® resulted in a significant increase in the proportion of hyperfluorescent cells compared with control cells. In addition, the staining profiles of individual cells showed no correlation between cell death and hyperfluorescence. The data also showed that hyperfluorescence did not occur extensively in deliberately lysed cells.Addition of fluorescein to the cells at 4°C resulted in very low levels of hyperfluorescence compared to high levels at 37°C. Fluorescein was rapidly released from cells at 37°C but not from those at 4°C. Conclusion: In this work, an effective in vitro model of SICS was developed in order to provide a better understanding of the mechanisms involved in fluorescein staining. This work suggests that corneal fluorescein staining may reflect a simple cellular uptake of fluorescein. Levels of staining in the cells appear to be unrelated to cellular toxicity or cell damage. Staining appears to occur in the cytoplasm and the nucleus of the cells. Finally, fluorescein uptake and release are likely to occur through active transports mechanisms.

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