Papers by Panos Lagouvardos
Prosthesis
Purpose: This study investigated the color and translucency changes of denture teeth after immers... more Purpose: This study investigated the color and translucency changes of denture teeth after immersion in disinfectant solutions. Material and Methods: Ten denture teeth (Optostar/Heraeus Kulzer) were immersed in nine different solutions (ethanol 78%, 2-propanol 75%, NaOCl 1%, H2O2 0.5%, glutaraldehyde 2.6%, chlorhexidine 0.12%, povidone-iodine 1%, Listerine Naturals, distilled water) for 3 min to 180 min. L*, a* and b* values were measured before and after their immersion with a contact colorimeter (FRU-WR18/Shenzhen Wave Electronics) over a white and black background, and ΔΕ*ab, ΔΕ00, ΔΤPab and ΔTP00 differences were calculated from baseline measurements. Two-way rmANOVA was used to analyze the data for significant differences among solutions and immersion times at α = 0.05. Results: ΔΕ*ab and ΔΕ00 values were significantly different only across solutions (p < 0.001), with mean differences from 0.24 to 1.81 ΔΕ*ab or 0.12 to 0.93 in ΔΕ00 units. TPab or TP00 translucency parameters...
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Aims of this study were the measurement of curing light intensity and curing ability in relation ... more Aims of this study were the measurement of curing light intensity and curing ability in relation to an increase of the light tip distance from the composite surface, during polymerization. Several curing lights were measured for their light intensity, as the distance of the tip was increasing from 0mm to 10mm. The results revealed that the light intensity of most curing lights dropped below 300mW/cm2 at a distance of 8mm, but some of them dropped already from the 4mm distance. Degree of composite polymerization as measured by the microhardness test, found to be decreased up to 71% on the surface and up to 36% on the bottom of a 3mm thick material, at a tip distance of 8mm. Additional polymerization of the top surface of the material, for a total of 90sec, did not proved able to give back the full microhardness, of the top surface of the material at distances more than 4mm and of the bottom surface at all distances
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The repair of Hybrid glass ionomers is sometimes useful in clinical practice. Bend strength tests... more The repair of Hybrid glass ionomers is sometimes useful in clinical practice. Bend strength tests of HGI revealed that the repair strength of a Resin modified glass ionomer can reach 65% of their original (intact) strength, while the polyacid modified resins can reach the 77%-100% of their intact strength, depending on the repairing technique and the material.
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Articles on high speed cutting rotary instruments are appearing from time to time in the dental l... more Articles on high speed cutting rotary instruments are appearing from time to time in the dental literature. The articlew usually investigate the ways of using these instruments, their shape, their quality, and their cutting ability. The precision of cutting a cavity and the quality of prepared margins, especially by worn out burs, are not fully investigated. The purpose of this study was to investigate these parameters. Carbide and diamond round burs of three different sizes were used to prepare cavities on the buccal and lingual surfaces of extracted human molar teeth. The burs rotating in two different handpieces, held by hand, were used to open 32 cavities, 2mm in depth within enamel. The bur diameter, before cutting the cavity, and the cavity diameter were measured for all bur-handpiece combinations in selected preparations. The quality of margins in the prepared cavities was assessed by light and scanning electron microscopy and classified into five different categories. Caviti...
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Odontology
Recording fluorescence using flash photography, may help reduce time of capture and apply effecti... more Recording fluorescence using flash photography, may help reduce time of capture and apply effectively in clinical practice. To test methods for visualizing composite resins fluorescence by direct digital photography. Sixty-four specimen discs (1.5 × 10 mm) were prepared from 8 different composite resin brands. Their CIELAB color coordinates (L*, a*, b*) and fluorescence were measured using a portable colorimeter and a fluorescence spectrophotometer. The mean of three measurements was recorded and then specimens were photographed by a DSLR camera with two different filters (365 nm and 405 nm) mounted on a commercial macro flash. RGB values of all specimens on the photographs were measured by using Photoshop software and converted to CIELab. Data were then analyzed using Kruskal–Wallis and Dunn’s multiple comparisons tests. Correlation and regression analyses were also used to relate fluorescence and color parameters on the photographs at α = 0.05. Fluorescence and color data indicate...
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: This study investigates the quantitative and qualitative absorption of carbon, from the investm... more : This study investigates the quantitative and qualitative absorption of carbon, from the investment material and/or the crucible, in two dental alloys. One of them is a high Pd, contains 88% Pd and the other is a Co-Cr contains 33% Co and 27%Cr. Both of these alloys are used in the construction of metal-ceramic restorations. A graphite and a non graphite investment material, as well as two kinds of crucibles, one graphite and the other ceramic were used in combination, for the production of specimens. For each investment-crucible combination, 5 specimens were produced for each alloy and measurements were taken for every one of them, using an energy dispersive x-ray analyser. Specimens produced with the same way were burnt off to verify the quantitative analysis of carbon which had been previously obtained. The results suggest that it is reasonable to avoid utilizing a graphite crucible in combination with a graphite investment material, when a high Pd or a Co-Cr alloy is used.
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It has been claimed that symmetry of upper central incisors, coincidence of upper lip midline wit... more It has been claimed that symmetry of upper central incisors, coincidence of upper lip midline with upper or lower teeth midlines, ratio of the widths of one tooth to another in the anterior upper teeth seen from the front, and ratio of the anterior teeth width to smile width seen also from the front, are parameters closely related to the esthetics of the mouth. In the present study the above mentioned parameters were analyzed for their relations to the upper arch form and sex, over a number of 525 individuals.The results indicated that upper arch form was related to all above parameters (sex, symmetry, coincidences and width ratios). The results also indicated a 62.8 percent of oval arch type, a 60.9 percent of symmetry of upper central incisors, a 75.0 percent of coincidence of upper teeth and lip midlines and a 24.0 percent of coincidence of upper and lower teeth midlines.
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Composite resins need most of the times finishing and polishing. Many systems in the market are s... more Composite resins need most of the times finishing and polishing. Many systems in the market are supposed to give the expected luster to the resins but since always new resin materials appear in the market, the search on polishing systems that can give a better result continues. The aim of this study was to evaluate the polishing action and result of three finishing-polishing systems (CompoSite Technique Kit / Shofu, Brilliant Gloss / Coltene and Sof-Lex system / 3M) on four hybrid composite resins (Tetric Ceram / Vivadent, Spectrum TPH / Dentsply, Synergy Cavifil / Coltene, Microhybrid Composite / Saremco). 30 discoid specimens from each resin material, embedded in a resin matrix, were abraded first by a SiC paper to receive the same roughness and then using a standard set up, the resin surfaces were finished and polished with the three different finishing-polishing systems. The surface roughness of all specimens before and after finishing were evaluated and the results showed that ...
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Roughening of a metallic or a ceamic surface, bonding strength to various cements is normally inc... more Roughening of a metallic or a ceamic surface, bonding strength to various cements is normally increased, since roughening increases the area for cement mechanical interlocking.Air-abrasion devices have been used intra-orally to roughen restorative material surfaces for a better bond with adhesive materials but little is known on the relation of surface quality and the variables that influence the roughening process. Amalgam, porcelain metal alloy and composite resin surfaces were abraded with an air-abrasion device for 3sec and 6sec, using 25μm, 50μm, 75μm and 100μm aloumina particles, the duration of particle flow and the tip distance. However there were differences between materials as to the degree of roughness which probably depends on the brittleness differences of the materials.
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Objective: Nylon is chosen in certain clinical cases as denture base material but the effect of d... more Objective: Nylon is chosen in certain clinical cases as denture base material but the effect of disinfection methods on its properties is unclear. The purpose of this study was to determine the influence of disinfection methods on color, gloss and 3-D topography of nylon denture base material in comparison to heat polymerized. Method: Sixty disks were made from nylon (Valplast) and heat-polymerized acrylic denture base material (Paladon 65). Ten specimens from each material were immersed in water (control), Val-Clean (peroxide cleanser) and Corega Extradent plus 2 min at 450W microwaving for a period simulating 30 days of daily disinfection. Color, gloss and 3-D topographic parameters (Sa, Sdr) were measured before and after disinfection cycles, using a colorimeter, a gloss meter and an interferometric profilometer. Mann-Whitney, Kruskal-Wallis, unpaired t-tests and regression analysis were used to analyze the data at α= .05 level of significance. Result: The results showed signific...
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Objectives: The purpose of this study was to investigate the relationship of colour vision defici... more Objectives: The purpose of this study was to investigate the relationship of colour vision deficiency and colour discrimination ability of young individuals with their dental shade matching ability. Methods: 150 dental students, aged 19-25, were tested for a) possible red-green colour vision deficiency using the Ishihara test on a computer screen, b) their colour discrimination ability using the Farnsworth-Munsell 100-Hue test and c) their shade matching performance using a custom made 16-disc Vita-Lumin-Vacuum shade guide and 12 duplicated shades of the guide, carefully selected and made. FM-100Hue test and shade matching tests were conducted in a booth under D65 illumination. Results: Ishihara test, revealed a 2% of students with a red-green colour vision deficiency and a 4% with questionable normal colour vision. FM-100Hue test, indicated a 60% of males and a 49% of females with a superior colour discrimination ability, with no difference between them (p=0.171). Shade matching te...
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Odontostomatologike proodos, 1990
The need of amalgam to resist fracture becomes a more evident necessity when restoration margins ... more The need of amalgam to resist fracture becomes a more evident necessity when restoration margins are taken into consideration. Marginal microcracks permit bacteria to pass beneath the restoration resulting in cement base dessalution, secondary caries and pulp inflammation. Fracture toughness of amalgam is usually studied indirectly from the maximum force required to fracture the amalgam, during compressive, tensile or bend stresses, through its ability to deform plastically or its surface hardness. Important information on fracture toughness of amalgams can be also taken from metallographic studies of their microstructures, during or after the formation of a crack. This study was planned to evaluate the microcracks produced on the surface of different amalgams, with a Vickers pyramid head of a hardness tester and their relation to the different phases of the amalgam structure. Seven amalgams were studied: Amalcap-F, Tytin, Cupralloy, Ana-2000 and three experimental combinations of t...
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International journal of paediatric dentistry / the British Paedodontic Society [and] the International Association of Dentistry for Children, 2008
To correlate the DIAGNOdent readings (LF) with those of direct visual (DV) examination, indirect ... more To correlate the DIAGNOdent readings (LF) with those of direct visual (DV) examination, indirect visual (IDV) examination, bitewing radiography (BWR), and pit and fissure opening (PFO) for the detection of occlusal caries in primary teeth; to determine the validity of this device using PFO as reference; and to evaluate its reliability. Two calibrated operators examined 130 teeth with 405 examination sites using DV, IDV and radiographic examinations, and LF. Of the 405 sites, 155 were visually scored for caries after pit and fissure opening. Pit and fissure opening was found to significantly correlate with all methods (rhoLF = 0.48, rhoBWX = 0.48, rhoDV = 0.44, rhoIDV = 0.41). For enamel lesions, higher sensitivity (0.76) was found with DV, while higher specificity (0.88) with the LF. For lesions into dentin, however, higher sensitivity (0.78) was found with the LF, while higher specificity (0.98) with the BWR. The device's accuracy was found to be 0.61 for enamel lesions, while ...
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Odontostomatologike proodos
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Hellenika stomatologika chronika. Hellenic stomatological annals
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Odontostomatologike proodos
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Hellenika stomatologika chronika. Hellenic stomatological annals
Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutec... more Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure.
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Stomatologia
This article presents the results of a clinical study conducted in the department of Operative De... more This article presents the results of a clinical study conducted in the department of Operative Dentistry of the University of Athens. The reasons for placing and replacing restorations, the restorative material used, patient's age and sex, teeth and surfaces involved and age of replaced restorations were the variables studied in 1520 restorations. The results revealed that 53.2% of the restorations were placed for the first time. 92.6% of the new restorations were placed due to primary caries. Secondary caries were the reasons for the 35% of the replaced with amalgam restorations. Secondary caries and color mismatch were the reasons for the 25% and 23.2% respectively of the replaced with composite restorations.
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Hellenika stomatologika chronika. Hellenic stomatological annals
Since the number of dental journals grows bigger every year it becomes important for the practiti... more Since the number of dental journals grows bigger every year it becomes important for the practitioner researcher teacher and editorial stuff to be informed for the content of the journals. The scientific reports in four Greek dental journals were recorded and evaluated according to several parameters. All the reports published in the years 1982-1986 were recorded and these were covering more than 90% of the total number of Greek scientific articles of this period. The results revealed an association between field and journal as well as between type of the report and journal, type and number of reports, type and number of authors, type and volume of the report, type and presence of tables, figures or photographs, type and number of references and type and cost of the report. It was also shown that in their largest percent the reports were dealing with Oral Medicine (16%), were of the review type (56.1%), were written by only one author (37.1%), contained no tables (58.8%) or diagrams...
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Papers by Panos Lagouvardos