You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
the aim of this study was to evaluate the difference in the shade between the readily available shade guide namely vita classical and ivoclar chromascop , and the fired and glazed porcelain samples fabricated using vita vmk 95 and ivoclar classic materials , respectively .
the objectives of this study were to obtain the mean difference in color between the vita classical shade guide and samples fabricated using vita vmk 95 and to obtain the mean difference in color between the ivoclar chromascop shade guide and samples fabricated using ivoclar classic .
the objective of this study was to obtain a matching brand of material that has a particular shade tab among the brands used .
the samples were made from specific form , size , and were of the suggested dimensions from investing self - cure acrylic strips made using a metal mold [ figures 1 and 2 ] , to casted nicr specimens using laser technology so as to get exactitude of normal dimensions .
the size of the specimens were 20 mm long , 10 mm breadth on one aspect and 3 mm breadth on the opposite aspect , of a preset form and 1.5 mm thick . to work out the thickness of the porcelain layers , 2 templates namely -the dentin template [ figure 4 ] and also the enamel template [ figure 5 ] were used .
the samples were divided into2 groups . metal template for acrylic specimens paint on technique for opaque layer group 1 consisted of 40 samples in which
every twenty samples were sub grouped and utilized for vita zahnfabrik vmk 95 ceramic powder shade c2 , d2 .
group 2 consisted of 40 specimens in which every twenty samples were sub grouped and utilized for ivoclar - classic ceramic powder shades of c2 , d2 .
two layers of opaque of individual manufacturer recommendations were applied to all the nickel - chromium specimens using brush on technique [ figure 3 ] and fired which amounts to an approximate thickness of 0.1 mm adequate to mask the metal .
the dentin porcelain powder of shade c2 of ivoclar classic was mixed with the modeling liquid , and applied onto the nickel chromium metal substructure over the opaque layer in the 20 specimens placed inside the depression in the dentin metal template [ figure 6 ] .
the slurry of dentin porcelain was condensed using the custom made covering lid for the metal mold [ figure 7 ] , to a predetermined thickness of 0.7 mm .
likewise , 40 specimens were finished with ivoclar classic porcelain material , and another 40 specimens were finished with vita zahnfabrikvmk95 porcelain material .
all 10 samples with dentine layer custom made covering lid for metal mold firing of all 10 samples at one time color research continued to evolve based on the munsell color model . in 1976 , the cie , an international color research group founded in 1931 , published the cielab color system . in this three - dimensional color system
, l * refers to brightness ( 0100 ) , a * represents red ( + a * ) versus green ( a * ) , and b * indicates yellow ( + b * ) versus blue ( b * ) .
when a * and b * are zero , the l value represents the continuum of black to white .
this allows the cielab system to measure color differences that are meaningful in industrial applications . since the development of the original 1976 cielab color system
the color coordinates of each of the 80 specimen were measured with a spectrophotometer ( minolta cm 3600d , japan ) set to the standard illumination source d65 with a 2-degree observation angle according to the cie recommendation .
the data were displayed in l * , a * , and b * values according to the cie lab system .
shades of the control specimen , i.e. , shade tab of c2 , d2 shades of vita classical [ figure 9 ] , and ivoclar chromascop [ figure 10 ] was evaluated spectrophotometrically . before each measurement session
, the spectrophotometer was calibrated according to manufacturer 's recommendations by using the supplied white calibration standard .
the mean and standard deviation estimated from the specimen of each subgroup was statistically analyzed .
a standardized t - test was done to compare the two brands of ceramic to the shade guide , and the results were statistically analyzed .
vitapan classic shade tab ivoclar chromoscope shade tab in this study , there are two main groups to be compared to the standard specimen so the standard t - test was used .
mean color difference for vita c2 samples ranges from 2.8 to 5.0 , with a mean of 3.4 and ivoclar c2 samples ranges from 2.1 to 3.7 with a mean of 2.6 [ table 1 ] .
mean color6 difference for vita d2 samples ranges from 2.5 to 3.5 , with a mean of 3.2 and ivoclar d2 samples ranges from 1.9 to 2.8 with a mean of 2.9 [ table 2 ] .
mean color difference between shade guide and sample for ivoclar c2 samples mean color difference between shade guide and sample for ivoclar d2 samples it can be inferred that from the above statistical analysis , ivoclar samples matched the standard ivoclar chromascop shade tab better than the vita group .
the aim of this study was to evaluate the difference in the shade between the readily available shade guide namely vita classical and ivoclar chromascop , and the fired and glazed porcelain samples fabricated using vita vmk 95 and ivoclar classic materials , respectively .
the objectives of this study were to obtain the mean difference in color between the vita classical shade guide and samples fabricated using vita vmk 95 and to obtain the mean difference in color between the ivoclar chromascop shade guide and samples fabricated using ivoclar classic .
the objective of this study was to obtain a matching brand of material that has a particular shade tab among the brands used .
the aim of this study was to evaluate the difference in the shade between the readily available shade guide namely vita classical and ivoclar chromascop , and the fired and glazed porcelain samples fabricated using vita vmk 95 and ivoclar classic materials , respectively .
the objectives of this study were to obtain the mean difference in color between the vita classical shade guide and samples fabricated using vita vmk 95 and to obtain the mean difference in color between the ivoclar chromascop shade guide and samples fabricated using ivoclar classic .
the objective of this study was to obtain a matching brand of material that has a particular shade tab among the brands used .
the samples were made from specific form , size , and were of the suggested dimensions from investing self - cure acrylic strips made using a metal mold [ figures 1 and 2 ] , to casted nicr specimens using laser technology so as to get exactitude of normal dimensions .
the size of the specimens were 20 mm long , 10 mm breadth on one aspect and 3 mm breadth on the opposite aspect , of a preset form and 1.5 mm thick . to work out the thickness of the porcelain layers , 2 templates namely -the dentin template [ figure 4 ] and also the enamel template [ figure 5 ] were used .
metal template for acrylic specimens paint on technique for opaque layer group 1 consisted of 40 samples in which every twenty samples were sub grouped and utilized for vita zahnfabrik vmk 95 ceramic powder shade c2 , d2 .
group 2 consisted of 40 specimens in which every twenty samples were sub grouped and utilized for ivoclar - classic ceramic powder shades of c2 , d2 .
two layers of opaque of individual manufacturer recommendations were applied to all the nickel - chromium specimens using brush on technique [ figure 3 ] and fired which amounts to an approximate thickness of 0.1 mm adequate to mask the metal .
the dentin porcelain powder of shade c2 of ivoclar classic was mixed with the modeling liquid , and applied onto the nickel chromium metal substructure over the opaque layer in the 20 specimens placed inside the depression in the dentin metal template [ figure 6 ] .
the slurry of dentin porcelain was condensed using the custom made covering lid for the metal mold [ figure 7 ] , to a predetermined thickness of 0.7 mm .
likewise , 40 specimens were finished with ivoclar classic porcelain material , and another 40 specimens were finished with vita zahnfabrikvmk95 porcelain material .
all 10 samples with dentine layer custom made covering lid for metal mold firing of all 10 samples at one time
color research continued to evolve based on the munsell color model . in 1976 , the cie , an international color research group founded in 1931 , published the cielab color system . in this three - dimensional color system
, l * refers to brightness ( 0100 ) , a * represents red ( + a * ) versus green ( a * ) , and b * indicates yellow ( + b * ) versus blue ( b * ) . when a * and b * are zero , the l value represents the continuum of black to white .
this allows the cielab system to measure color differences that are meaningful in industrial applications . since the development of the original 1976 cielab color system
the color coordinates of each of the 80 specimen were measured with a spectrophotometer ( minolta cm 3600d , japan ) set to the standard illumination source d65 with a 2-degree observation angle according to the cie recommendation .
the data were displayed in l * , a * , and b * values according to the cie lab system . shades of the control specimen , i.e. , shade tab of c2 , d2 shades of vita classical [ figure 9 ] , and ivoclar chromascop [ figure 10 ] was evaluated spectrophotometrically . before each measurement session ,
the spectrophotometer was calibrated according to manufacturer 's recommendations by using the supplied white calibration standard .
the mean and standard deviation estimated from the specimen of each subgroup was statistically analyzed .
a standardized t - test was done to compare the two brands of ceramic to the shade guide , and the results were statistically analyzed .
in this study , there are two main groups to be compared to the standard specimen so the standard t - test was used .
mean color difference for vita c2 samples ranges from 2.8 to 5.0 , with a mean of 3.4 and ivoclar c2 samples ranges from 2.1 to 3.7 with a mean of 2.6 [ table 1 ] .
mean color6 difference for vita d2 samples ranges from 2.5 to 3.5 , with a mean of 3.2 and ivoclar d2 samples ranges from 1.9 to 2.8 with a mean of 2.9 [ table 2 ] .
mean color difference between shade guide and sample for ivoclar c2 samples mean color difference between shade guide and sample for ivoclar d2 samples it can be inferred that from the above statistical analysis , ivoclar samples matched the standard ivoclar chromascop shade tab better than the vita group .
all the forty samples fabricated using the vita material and the corresponding two shade tabs from the vita classical shade guide were spectrophotometrically analyzed .
all the forty samples fabricated using the ivoclar material and the corresponding four shade tabs from the ivoclar chromascop shade guide were spectrophotometric ally analyzed .
after statistical analysis , the following inference was obtained . within the limitations of the study
, the obtained results showed that the samples fabricated using ivoclar material had the least mean color difference [ tables 3 and 4 ] . hence
, ivoclar samples matched the chromascop shade guide better than the vita samples matching the vita classical shade guide .
all the forty samples fabricated using the ivoclar material and the corresponding four shade tabs from the ivoclar chromascop shade guide were spectrophotometric ally analyzed .
within the limitations of the study , the obtained results showed that the samples fabricated using ivoclar material had the least mean color difference [ tables 3 and 4 ] .
hence , ivoclar samples matched the chromascop shade guide better than the vita samples matching the vita classical shade guide .
in fact , corrections of esthetic problems have a positive effect on the self - esteem .
a smile has been said to be one of the most important interactive communication skills of a person .
the ultimate objective of esthetics in dentistry is to create a beautiful smile , with teeth of pleasing inherent proportions to one another , and a pleasing tooth arrangement in harmony with the gingiva , lips , and face of the patient .
the phenomenon of color is a psychophysical response to the physical interaction of light energy with an object , and the subjective experience of an individual observer .
three factors can influence the perception of color , namely , the light source , the object being viewed , and the observer viewing the object . the light source can emit radiant energy of a range of wavelengths , and this is characterized by the relative amount of energy emitted at each wavelength in the visible spectrum . the light source that illuminates an object affects color perception , since individual sources contain varying quantities of each of the visible wavelengths of light .
the spectral reflectance ( or transmittance ) of an object characterizes the color makeup of that object .
problems identified were that porcelains do not match the shade guides to which they are compared and shade variations exist between different lots of porcelain from the same manufacturer .
the following difficulties were reported with the fabrication of custom shade guide : ( 1 ) the problem of matching a thin piece of porcelain to a shade guide several millimeters thick , ( 2 ) the variations of porcelain powder batches that do not match the shade guide consistently , and ( 3 ) the difficulty of predicting the final color of the typical layered veneer of opaque , dentin , and enamel .
the study results and outcome also come close to those of earlier studies by van der burgt et al .
the significance of the interaction indicates that some shades produced better match with some brands . in this study
the inadequacies of dental shade guide in terms of range and systemic distribution in the tooth color phase have been described .
significant advances in the shade guide organization and coverage of natural tooth color space arrangement of  virtually all existing natural tooth shades  need to be researched and developed for the future of prosthodontics outcome . on comparing the intragrou p values of the various shades evaluated from the table 1 ,
the shade of c2 in the samples fabricated using ivoclar material was found to be more close to the ivoclar chromascope shade guide comparing to the other shades of ivoclar b2,c2 , d2 with the ivoclar chromascop shade guide .
on spectrophotometric color analysis the mean color difference between the ivoclar samples were lower than that of the vita samples .
therefore the samples fabricated using ivoclar classic matched the ivoclar chromascop shade guide closely than the samples fabricated using the vita zahnfabrikvmk95 material matched the vita classical shade guide .
to conclude , ivoclar material matched the chromascop shade guide better than the vita material matched the vita classic shade guide .
introduction : smile is one of the most important interactive communication skills of a person . a smile is the key factor for an aesthetic appearance . 
 hence aesthetics is one of the motivating factor for the patients to seek dental care . 
 correction of unaesthetic appearance gives a positive effect to the self esteem of the patient.aim:the aim of this study was to compare the difference in the shade between the commercially available shade guides namely vita classical and ivoclar chromascop and the fired porcelain samples fabricated using vita zahnfabrik vmk 95 and ivoclar classic materials respectively.objectives:the objective of this study was to obtain a matching brand of material that has a particular shade tab among the brands used.conclusion:to conclude , ivoclar material matched the chromascop shade guide better than the vita material matched the vita classic shade guide .