Showing 15 results for Color
J. Mahmodian , A. Kousari , Sh. Mortazavi ,
Volume 13, Issue 2 (5-2000)
Abstract
Dental enamel is the end product of amelogenesis, which can be considered to take place in three interrelated phases. When this complex sequence of cytological and physicochemica! events disrupted by genetic or environmental factors, the function of the ameloblasts may be disrupted permanently or temporarily. The result shows qualitative and quantitative defects that may range from a complete absence of enamel or a slight discoloration. The aim of this study was to determine the prevalence of enamel defects by DDE index in a randomly selection group of 1637 students age 7-12 years old in Isfahan (0.2-0.3 PPMF"). Enamel defects were present on one or more teeth in 27% of the cases. The most common affected tooth was the central maxillary and then first molar of maxilla. The most common affected surfaces were buccal. Hypoplastic defects were found in first molar however premolar and canine were affected by diffuse white lines opacity.
M. Ghavam , M. Poorhaghighi , M. Mohammadi ,
Volume 13, Issue 3 (10-2000)
Abstract
Discoloration of composite resins is considered to be a major factor in esthetic restoration failures. The aim of this study was to evaluate color stability of IDM composite (both light and self cure samples namely IL and IS), and to compare it with a self-cure composite (Degufill named DS) and a light cure ormocer composite (Definite, called DL in the Report). 60 disk shaped samples of each composite were prepared, according to ISO-7491. The samples were divided into 3 groups and aged as follows: A- (Control) 7 days in dark 37°c chamber B- Foil covered and kept in 100% humidity, and 37°c in xenotest chamber for 24 hours, then transferred to a dark 37°c chamber for 6 more days.C- Kept in 37°c, 100% humidity under the emission of xiiion lamp of xenotest chamber for 24 hours,and then transferred to 37°c dark chamber for 6 more days The lightness and chromaticity values of samples were measured both before and after aging using a spectrophotometer (Data Flash). The total color changes as well as changes in lightness and chromaticity values were measured in the CIE L * a * b * scale, and analyzed. Color change was recorded to be significant in all samples after aging. The maximum change belonged to IL, which was significantly
different from DL and DS. It seems, in order to have a durable esthetic restoration using IDM, more scientific and professional consideration is needed in the production process.
S. Zarrati , M. Nazari Marzjarani ,
Volume 15, Issue 2 (5-2002)
Abstract
Esthetic is a natural necessity among all human beings, and the reconstruction of the natural features of prosthesis is considered an important aspect in dentistry. Reconstruction of the natural features in removable prosthesis by characterization of denture base is one of the most important factors. In this regard esthetic, in removable prostheses, is achieved through different techniques such as: tooth selection and arrangement, designing the denture base and acrylic base color. The final goal for ail these effects is to achieve a natural appearance for denture. However, other factors such as treatment limitations, different personal needs and general health principles, should be taken into consideration. This article not only reviews the natural appearance of oral mucosa that is replaced by the denture base, but also discusses about the materials used in tinting acrylic denture base and their application techniques.
H. Jalali , S. Moradian , D. Jalaei ,
Volume 18, Issue 3 (5-2005)
Abstract
Background and Aim: With the introduction of porcelain veneers to fulfill patients’ esthetic needs, question raises about the ability of the veneers to cover the substructure discoloration. It seems that using shade modifiers under the porcelain veneers can neutralize the discoloration. The goal of this study was to determine the efficacy of shade modifiers in correcting tooth discoloration, when used with resin cements under porcelain veneers.
Materials and Methods: In this experimental study, 60 porcelain discs with two thicknesses of 0.7 mm and 2 mm (30 porcelain of each thickness) were made from ceramco porcelain powder. 40 of them were in A2 shade and 20 were made by the mixture of A2 shade porcelain powder and porcelain stain to represent tooth discoloration. Then all the laminate discs (0.7 mm) were cemented over the 2 mm thick discs to make groups of 10 samples as followed: 1- The first group: laminate discs + resin cement + 2mm thick discs with A2 shade. 2- The second group: laminate discs + resin cement + 2mm thick discolored discs. 3- The third group: laminate discs+ resin cement+ shade modifier+ 2mm thick discolored discs. The color of 30 specimens was measured by spectrophotometer in 2 conditions. 1- To include the specular reflection (SCI). 2- To exclude specular reflection (SCE). In each condition the specimens were measured on both a white background (W) and a black one (B). The mean color differences (E) of each specimen in the second and third group with the specimens of the first group were calculated. Data were analyzed using Paired sample t-test and P<0.05 of significance.
Results: Color measurements showed that in SCIW condition L was significantly different among the three groups except the first and the third. In SCEW condition all the parameters showed significant differences. In SCIB condition, E was not significantly different between the second and the third groups. Hue (h) parameter wasn’t different between groups one and three neither was chroma (c) among the three groups. In SCEB condition, E was not statistically different between groups two and three.
Conclusion: Considering the statistical results, shade modifier couldn’t completely match the color of the specimens in the third group with the first one. But, the lower E for the third group comparing to the second one means that shade modifier was successful in reducing the effect of substructure discoloration.
M. Mehran, M. Mohammadi Bassir, S. Jafari ,
Volume 21, Issue 4 (1-2009)
Abstract
Background and Aim: Black staining after taking iron drops on the primary teeth is always concern of parents. There is not an exact explanation for the mechanism of iron black staining. The purpose of this study was to compare tooth discolorations, atomic absorption and structural changes of primary teeth enamel caused by two kinds of iron drops[ Kharazmi(Iran) and Fer-in-sol(USA)].
Materials and Methods: In this ex-vivo study, 93 sound primary teeth in normal color range were divided into five groups. Two groups of samples were immersed into the Artificial Caries Challenge(ACC) for two weeks before getting exposured to iron drops: Group 1 Control(NS): sound enamel teeth which were kept in Normal Saline environment(NS)(13teeth). Group 2 (NS-KH): NS, kharazmi iron drop (20 teeth). Group 3 (ACC-KH): ACC, Kharazmi iron drop (20teeth). Group 4 (NS-F-in-S): NS, Fer-in-Sol iron drop (20teeth). Group 5 (ACC-F-in-S): ACC, Fer-in-Sol iron drop. Visual tooth discolorations were determined by a specialist in operative dentistry who was not aware of experimental groups. The iron concentration was measured by ICP system (Vista-pro, Australia) and the structural changes were studied by SEM (Philips, Netherland). The data of discoloration were studied with Kruskal-Wallis test and multiple comparison using Bonferroni type test, and with the data of atomic absorption were studied with oneway ANOVA test and Tukey HSD test.
Results: The discoloration in the teeth immersed into the ACC (ACC-KH, ACC-F-in-S) was more severe than the sound enamel surface (NS-KH, NS-F-IN-S) (p<0.001) and Kharazmi iron drop caused more discoloration in the teeth immersed into the ACC (p=0.018). The teeth immersed into the ACC, absorbed more iron than the sound enamel surface (p<0.001) and also the teeth immersed into the ACC absorbed more Kharazmi iron drop (p<0.001). In the Scanning Electron Microscopy study, at low magnification in the sound teeth the perikymata was arranged regular. At low magnification in the teeth immersed into the ACC, many fractures were observed. The fractures in group 3(ACC-KH) were more and deeper.
Conclusion: Being immersed into the ACC, caused more iron absorption, severe discoloration and structural changes in the enamel of primary teeth. Such changes were more distinct in the teeth exposed to Kharazmi iron drop than the teeth exposed to Fer-in-Sol iron drop.
M. Alikhasi, H. Siadat, A Monzavi, M. Naseri, S. Sheikhzadeh, F. Taghavi,
Volume 24, Issue 3 (6-2011)
Abstract
Background and Aims: The bond strength between veneer ceramics and zirconia frameworks is the weakest component in the layered ceramics. Due to the possible effect of adding pigments to the core materials on the bond strength between core and veneer as well as the introduction of new ceramic materials in dentistry, the aim of this study was to compare the zirconia core-veneer microtensile bond strength using two ceramic veneers with or without coloring the core.
Materials and Methods: In this experimental study, 12 disc-shaped specimens were fabricated using a manually aided design- manually aided manufactured (MAD/MAM) zirconia core (Zirkonzahn). Two veneering ceramics of Ceram Kiss and Zirkonzahn ICE were also used to veneer the specimens. Half of the Zirkonzahn discs were remained white and the others were colored by shade A2.Then, the discs were cut into microbars (30 for each group) and the microtensile bond strength of the core-veneer was calculated. The specimens were assessed using scanning electron microscopy (SEM) and the data were analyzed using two-way ANOVA and Student's t-test.
Results: Significant differences with respect to veneer layer were found (P<0.001). No significant differences were seen among colored and uncolored cores (P=0.69).
Conclusion: According to the apparent effect of veneering ceramics on the core-veneer bond strength, careful selection of these agents is essential to achieve adequate bond strength between core and veneer to prevent delaminating and chipping failures of zirconia veneered restorations.
Marzieh Alikhasi , Razieh Khanmohammadi, Somayeh Niakan ,
Volume 26, Issue 3 (8-2013)
Abstract
Background and Aims: Along with the advances in dental materials and invention of new techniques for ceramic producion, the demand for the beauty and matching restoration’s color with patient’s natural teeth is growing. Nowadays, zirconia systems are the focus of attention. Despite their strength, one of the problems with such systems is the high opacity and failing to provide the favored color. Considering few studies about the influence of shading on Zirconia, the purpose of this in vitro study was to evaluate the effect of different shading of zirconia-based ceramics on the biaxial flexural strength .
Materials and Methods: In this in vitro experimental study, Rainbow (Dentium, Korea) zirconia-based ceramics (the diameter of 15mm and 1mm in thick) were divided into four groups of 10 specimens. According to Vita shade guide system and manufacturer’s time recommendations (3 seconds), three groups of disc specimens were shaded to A3, B3 and D3 colors and other ten specimens remained uncolored as control group. The biaxial flexural strength test of discs was evaluated and the elements’ composition of colors was detected by Energy Dispersiue X-ray Microanalysisd (EDX). Finally, data were analyzed using one-way ANOVA and Post-hoc tests.
Results: The biaxial flexural strength in non colored specimens, A3 shaded discs, B3 shaded, and D3 shaded specimens were determined 1061.93, 819.16, 1100.10, and 825.48 MPa respectively which was statistically significant among groups (P<0.001). The statistical analysis revealed that the highest strength in B3 and non colored groups which were significantly higher than A3 and D3. EDX analysis showed significant differences among different colored compositions.
Conclusion: The biaxial flexural strength of zirconia cores are affected by shading and the specific selected color.
Farzaneh Farid, Pedram Etemadi, Farhad Shafiee,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: Increase of esthetic demands among dental patients has led to development and wide spread use of tooth colored ceramic systems for fabricating fixed restorations. However, they do not have same capability of matching the target color. The aim of this study was to compare the color coordinates of three widely used systems with A2 tab from a Vita Lumin Classic shade guide.
Materials and Methods: In this study, three ceramic systems were tested. The metal-ceramic(MCR) with 0.5 mm core and 1 mm Ceramco lll veneering layer; the all ceramic (CE) with 0.5 mm Cercon core and 1 mm Cercon Ceram veneering layer, and the all porcelain (VM7) with 1.5 mm Vita VM7. For each system, 15 disks (1.5mm×10mm) were made in Vita A2 shade. L*a*b* coordinates of the samples were measured by spectrophotometer and the color difference with Vita A2 shade was calculated. The data were analyzed using one way ANOVA and multiple Tukey tests.
Results: The color coordinates of the target shade was L*=72.45, a=1.59 and b*=14.11. The mean L*a*b* values for MCR were 72.61±0.38, 2.88±0.24, 15.51±0.64, for CE were 76.42±0.46, 2.77±0.14, 17.51±0.61, and for VM7 were 75.13±0.6, 2.15±0.19, 17.9±0.61, respectively. The difference between coordinates of each system with target shade was significant. Only for MCR group, ΔE was in acceptable range (1.98). For CE (Δ=5.38) and VM7 (Δ=4.72) groups, the difference was unacceptable.
Conclusion: Under the condition of this study, the metal-ceramic system had the best and acceptable match to the target shade.
Ladan Ranjbar Omrani, Masumeh Hasani Tabatabaei, Soma Faridi, Elham Ahmad,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: The aim of this study was to evaluate the effects of two fluoride containing mouth rinses on the color stability of two different resin composites.
Materials and Methods: 27 specimens (2×4×5 mm) were prepared from each of the following materials: a micro filled composite (Gradia, GC) and nanohybrid (Grandio). The specimens were polished by Soflex fine and superfine disks and then incubated in artificial saliva at 37°C for 24 h. The baseline color values (L, a, b) of each specimen were measured using an Easyshade spectrophotometer according to the CIELab color scale. The specimens were immersed in 20 mL of each mouth rinse and stored in an incubator at 37°C for 12 h. After incubation, the color values of all specimens were measured again, and the color change value (ΔE) was calculated. Data were analyzed by a 2-way analysis of variance at a significance level of 0.05.
Results: None of the mouth rinses created clinical significant color changes in the samples. There was no statistically significant difference among color susceptibility between resin composites (P=0.330). The interaction between the effect of mouth rinses and type of restorative materials was not statistically significant (P>0.05).
Conclusion: Accordance to the results of this study, the fluoride containing mouth rinses does not create color change in resin composites.
Seyyede Fateme Basri, Rafat Bagheri, Maryam Sadat Tavangar,
Volume 31, Issue 1 (6-2018)
Abstract
Background and Aims: Fracture and color change are among the most common causes of clinical failure of resin composite restorations. Therefore, this study aimed to examine the fracture toughness and color changes of 3 Nano-hybrid resin composites in dry and wet conditions.
Materials and Methods: Three resin composites were studied. A total of 36 rectangular specimens were prepared for each material, randomly divided into 2 groups, and stored at 37°C dry or soaked in distilled water. In each group, the specimens were subdivided into three groups (n=6) and stored for 1, 7, and 60 days. After each time interval, the specimens were tested for the fracture toughness and loaded at a cross-head speed of 0.5mm/min using a universal testing machine. The baseline and final color measurement was recorded for each specimen using a spectrophotometer. The collected data was analyzed using ANOVA and Kruskal-Wallis tests.
Results: After 60 days, the mean value of fracture toughness was lower in the wet condition compared to that of dry condition. However, it was not significantly different except for aura Bulkfil (P=0.001). Color change was significantly different for Tetric Evoceram and aura with a greater value in the wet condition compared to that of dry (P=0.004). The greatest color stability was found for aura and the least for Tetric Evoceram.
Conclusion: In this study, most of the materials stored in a dry condition showed a greater fracture toughness and color change.
Mehdi Abbasi, Aghil Rahmani, Ladan Ranjbar Omrani, Zohreh Moradi, Masumeh Hasani Tabatabaei, Sara Valizadeh,
Volume 31, Issue 3 (11-2018)
Abstract
Background and Aims: Color is the most important and complicated part of aesthetic dentistry. The tooth color matching of restorations is considered as one of the most difficult tasks in the restorative dentistry. The aim of this study to evaluate the effect of two training methods on the dental students’ ability in determining tooth color matching.
Materials and Methods: In this study, 40 dentistry students participated which randomly allocated into two groups. The first group consisted of students who learned teeth color matching methods practically. In the second group, training booklet was used for learning. Using Vita Classic shade guide series, 4 color samples were chosen and the students of each group were asked to determine samples’ color, before, after and one month after the training.
Results: Booklet learning group was more successful in determining fourth color sample. However, in no studied group and no used samples, the results of one month after learning were not better than that of before learning. Also generally, no significant relationship was found between the color matching accuracy, using glasses, and sex of participants.
Conclusion: The use of booklet learning was more effective than practical learning in color matching accuracy for dental students. Also, using glasses and sex were not effective on their color matching accuracy.
Abdolrahim Davari, Alireza Daneshkazemi, Mahsan Sheshmani, Haleh Karami, Elham Motallebi,
Volume 32, Issue 3 (11-2019)
Abstract
Background and Aims: The bleaching agents can lead to color and translucency changes in composite resins. Due to the increasing use of the nano composites and the silorane-based composites, this study aimed at examining the color and translucency changes of these restorations after bleaching agents.
Materials and Methods: In this experimental - laboratory study, 198 composite discs were divided into three groups of 66 specimens using three types of composite: the microhybrid composite Z250, the nanohybrid composite Z350 and the silorane-based composite P90. After acid etching, half of the specimens in each group were covered by a resin rebounding agent. Then, the color and translucency assessment was done by reflectance spectrophotometer, using CIE LAB system. Each group was divided into three subgroups of bleaching agents: the 40% hydrogen peroxide and 20% carbamide peroxide bleaching agents and the control group. After applying bleaching agents, the final color and translucency changes were assessed. Data were analyzed using Mann Whitney and Kruskal Wallis tests.
Results: The effect of composite and bleaching agent type and bonding agent were significant (P<0.001). The color changes in the microhybrid composite were higher than nanohybrid and silorane-based composites (P<0.001) (∆E>3.3). Also, the color changes by 20% carbamide peroxide were higher than that of hydrogen peroxide and control groups (P<0.001). The results of translucency changes were generally consistent with color-change measurements (∆E>3.3).
Conclusion: According to the present study, the most color changes appeared in the microhybrid composite and by 20% carbamide peroxide bleaching agent. Rebound samples were generally less affected by bleaching agents. The least color and translucency changes were related to nanohybrid composites.
Mansoureh Emami Arjomand, Seyde Sahar Masoumi, Haleh Heshmat, Zahra Nouralizadeh,
Volume 35, Issue 0 (5-2022)
Abstract
Background and Aims: Considering the preventive and therapeutic effects of resin infiltration (RI) and the unknown effect of bleaching on the enamel treated with this method, this in-vitro study aimed to assess the effect of bleaching on color stability of enamel lesions treated with RI.
Materials and Methods: In this in-vitro, experimental study, enamel-dentin samples measuring 5×5×3 mm were prepared on the buccal and lingual surfaces of 30 extracted humans third molars with no caries, cracks or enamel defects by a microtome. The specimens were divided into three groups of 10 specimens: 1) sound enamel (control), 2) demineralized enamel, 3) demineralized enamel plus RI. White spot lesions were artificially created by immersing the samples in hydroxyethyl cellulose demineralizing gel with a pH of 4.5 for 4 days. Next, Icon RI was applied on the samples in group 3. The baseline color of the specimens was measured using a spectrophotometer. Then, 35% hydrogen peroxide was applied on the specimens in three cycles and time interval of 10 min. After the end of the last cycle, the samples were completely washed for 1 min and then, underwent colorimetry again. Data were analyzed using one-way ANOVA.
Results: The results of this study showed that the highest level of color change (ΔE) in the demineralized group was 6.3±2.003, while the least amount of ΔE in the enamel lesion group treated with resin infiltration was 3.54±0.98 and in the control group ΔE was 4.13±1.14. Therefore, there was a significant difference between demineralized and treated by infiltratant groups (P=0.005). However, there was no significant difference between control group and treated with resin infiltration group (P=0.54).
Conclusion: Bleaching induced a less change in the color of the enamel lesions treated by resin infiltration compared with that of the demineralized teeth.
Fatemeh Mokhtarifatemeh Mokhtari, Mohammad Mohammadhoseini, Nooshin Fakhari, Alireza Yazdani Rostam,
Volume 35, Issue 0 (5-2022)
Abstract
Background and Aims: The aim of this study was to investigate the tooth discoloration caused by cold ceramic compared to MTA Angelus in contact with the washing solutions such as sodium hypochlorite (NaOCl) and normal saline.
Materials and Methods: 50 samples of extracted human maxillary anterior teeth were selected. After preparing the access cavity, they were divided into 4 experimental groups and 1 control group (10 in each group). The access cavities of teeth in groups 2 and 4 were rinsed with 5.25% sodium hypochlorite and those in groups 1 and 3 were rinsed with normal saline. Then, after drying, 3 mm thickness of cold ceramic (groups 1 and 2) and MTA Angelus (groups 3 and 4) were placed in the access cavities of the teeth. After setting of the materials, all specimens were restored with a resin modified glass ionomer. Based on the CIE Lab system, each sample’s total color change (∆E) was obtained before, one, and 90 days after application. Data were statistically analyzed using the Wilcoxon test.
Results: According to the results, there was no statistically significant difference in the average tooth discoloration between the groups filled with cold ceramic and in different time periods (P>0.05). While, in the groups filled with MTA Angelus, the difference in the average tooth discoloration in 90 days after application was significantly higher than one day (P<0.05).
Conclusion: The results of this study showed that compared to MTA Angelus, cold ceramic causes less tooth discoloration over time and therefore, it can be suggested as a more suitable alternative endodontic cement than MTA Angelus.
Fereshteh Naser Alavi, Ashkan Salari, Seyedeh-Maryam Tavangar, Reza Tayefeh Davalloo, Farideh Darabi, Zahra Farzi,
Volume 36, Issue 0 (5-2023)
Abstract
Background and Aims: The white color of teeth is one of the most essential factors in smile esthetics. Therefore, various whitening agents such as bleaching mouthwashes have been produced in response to the people’s high demand for having whiter teeth. The present study evaluated the efficacy of three whitening mouthwash products on tooth enamel whiteness.
Materials and Methods: In the present in vitro study, 32 bovine incisors were assigned to four groups in terms of the mouthwash used (n=8): control (C); Xenon Smart White (ZSW), containing pyrophosphate and triphosphate; Signal White Now (SWN), containing Blue Covarine; and Pasta Del Capitano whitening mouthrinse (PCW), containing Plasdone. Colorimetry was carried out using a spectrophotometer at the baseline and 2, 4, 8, and 12 weeks after treatment with mouthwashes. Data were analyzed using CIELab parameters with ANOVA, RM two-way ANOVA, and post hoc Tukey tests (α=0.05).
Results: The results showed that the whiteness created by the SWN mouthwash was clinically visible (ΔE>3.3). However, the functions of all the mouthwashes were statistically similar with no significant differences from the control group (P>0.05).
Conclusion: Although, Blue Covarine-containing mouthwash was somewhat effective in whitening of tooth enamel, none of the mouthwashes had significant efficacy compared to distilled water.
