- Email: [email protected]
Type IV gypsum compatibility with five addition-reaction silicone impression materials
Type IV gypsum compatibility with five addition-reaction silicone impression materials Rajeev Butta, BDS, MSc,a Christopher Jeremy Tredwin, BDS, BSc, MSc,b Michael Nesbit, MSc,c and David R. Moles, PhD, BDS, MSc, MScd Department of Conservative Dentistry, Eastman Dental Institute, University College London, London, England Statement of problem. The compatibility of current addition-reaction silicone impression materials and Type IV gypsum products is not completely understood.
Purpose. The purpose of this study was to compare surface detail reproduction between various combinations of contemporary addition-reaction silicone impression materials and Type IV gypsum products.
Material and methods. Under standardized conditions, 300 impressions were made of a ruled stainless steel die (ADA specification 19), using 5 addition-reaction silicones (Examix-NDS, Doric-ES Flo-Light, Panasil Contact Plus, Extrude Wash, and President Plus Jet). Fifteen impressions of each material were poured with each Type IV gypsum product (Silky-Rock, Fuji Rock, Suprastone, or Vel-Mix). Using 312 magnification, 2 independent examiners scored the reproducibility of a 20-mm line in both the impression and the resultant casts. Statistical analysis was performed using 2-way analysis of variance and post hoc Bonferroni testing (a=.05). Results. All impression materials tested fully reproduced the 20-mm line. Different impression materials showed different compatibility with different Type IV gypsum products. Only 25% of the Type IV gypsum casts completely reproduced the resultant 20-mm line with fine margins, and 88% of the completely reproduced casts were made from Suprastone. Conclusion. Not all combinations of impression material and Type IV gypsum products used exhibited similar compatibility. (J Prosthet Dent 2005;93:540-4.)
CLINICAL IMPLICATIONS This study demonstrated that for optimal compatibility, clinicians and technicians should carefully select the combination of silicone impression material and Type IV gypsum product.
T
he correct use of impression and die materials is essential for consistent and reliable fabrication of stone casts and dies. The use of incompatible materials may cause poor reproducibility, lack of surface detail, and bubbles in the definitive cast, which may result in an inaccurate die and a poorly fitting casting.1 The American National Standards Institute and American Dental Association (ANSI/ADA) Specification No. 19 specifies the use of an unmodified, a-hemihydrate gypsum in determining whether an impression material is compatible with dental stones.2 If a 20-mm-wide line in the surface of an impression material specimen is reproduced in the gypsum cast at between 34 and 312 magnification, the
a
Graduate student. Clinical Lecturer, Honorary Specialist Registrar in Restorative Dentistry. c Technical Instructor. d Senior Clinical Lecturer in Health Sciences Research. b
540 THE JOURNAL OF PROSTHETIC DENTISTRY
impression material has satisfied the ‘‘compatibility with gypsum’’ requirement. Differences in dimensional stability, wettability, and surface hardness have been identified for gypsum casts poured against various elastomeric impression materials.3 The hydrophobic characteristics of addition-reaction silicone impression materials are well known and make it difficult to pour a bubble-free stone cast.1 Although some studies have reported on compatibility between combinations of impression materials and dental stones, reports have been sparse in recent years regarding detail reproducibility of different brands of Type IV gypsum products and addition-reaction silicone impression materials.4-9 A lack of surface detail reproduction on the die is one manifestation of a compatibility problem. The purpose of this study was to compare the compatibility of 5 brands of addition-reaction silicone impression material with 4 brands of Type IV gypsum product, in relation to detail reproducibility. The null hypothesis was that there was no significant difference between the compatibility VOLUME 93 NUMBER 6
BUTTA ET AL
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 1. Photograph of ADA test die used in this study.
among these addition-reaction silicone impression brands and the 4 Type IV gypsum products.
MATERIAL AND METHODS The impression materials and Type IV gypsum products tested in this study are listed in Table I. The ADA test die (Ravensfield Design, Lancashire, UK) inscribed with 3 horizontal and 2 vertical lines is shown in Figures 1 through 3. The study was performed in accordance with ADA specification 19.2 Using each of the 5 impression materials, 60 impressions were randomly made of the ADA test block at 34°C and stored for 1 hour at ambient laboratory conditions (room temperature, 21°23°C, and humidity, 30%-40%). Fifteen impressions of each material were randomly assigned to be poured with 1 of the 4 Type IV gypsum products using manufacturer recommended water/powder ratios and vacuum mixing. Impressions were poured using vibration and a slight angulation. Using a microscope (Wild M5; Wild-Heerbrugg Ltd, Heerbrugg, Switzerland) at 312 magnification with standardized low angle (20 degrees) illumination, 2 independent examiners randomly examined both the impression material and the associated cast and scored the reproducibility of the middle 20-mm horizontal line (Figs. 1, 2, and 3). The criteria used to score the reproducibility were adapted from a previous study.5 A score of 4 represented perfect reproducibility of the original line on the ADA test block, which is a sharp V shape; a score of 3 represented slight loss of clarity with the V shape becoming rounded; a score of 2 showed that part of the line was not recorded, and a score of 1 showed that the line was not reproduced at all. Both examiners repeated the scoring for all the silicone and gypsum specimens on different days. The worst score obtained from the 2 examiners was used to provide the final score. Randomization throughout the experiment was achieved using a computer-generated random number JUNE 2005
Fig. 2. Diagrammatic representation of ADA test die shown in Figure 1. Surface detail reproducibility of impressions and associated casts was measured via qualitative assessment of Line b duplication. Table I. Materials tested in study Impression materials
Batch no.
Examix-NDS Doric-ES Flo-Light
0210081 510641
Panasil Contact Plus Extrude Wash President Plus Jet
30401 2-1112 MC533
Gypsum products Silky-Rock Fuji Rock
018503008 030127
Suprastone
3-1071
Vel-Mix
2-2127
Manufacturer
GC America, Alsip, Ill Davis, Schottlander & Davis, Letchworth, UK Kettenbach, Eschenburg, Germany Kerr, Orange, Calif Coltene AG, Altstatten, Switzerland. Whip Mix, Louisville, Ky GC Europe, Leuven, Belgium, Europe Kerr Italia, Salerno, Italy, Europe Kerr Italia, Salerno, Italy, Europe
list. The Kappa statistic (K) was used to assess interexaminer and intraexaminer agreement. Two-way analysis of variance (ANOVA) was used to test for any differences between impression material and Type IV gypsum product compatibility (a=.05). A conservative post hoc test correction was applied (Bonferroni multiple comparisons test) to see what difference occurred between the mean values of subgroups. 541
THE JOURNAL OF PROSTHETIC DENTISTRY
BUTTA ET AL
Fig. 3. Side profile diagrammatic representation of ADA test die, showing point A-A in Figure 2 enlarged.
Table II. Median reproducibility quality scores obtained for Type IV gypsum products related to impression materials from which poured Impression material
Type IV gypsum product
Examix-NDS
Doric-ES Flo-Light
Panasil Contact Plus
Extrude Wash
President Plus Jet
2 3 4 3
2 3 4 3
2 3 4 2
2 4 4 2
3 3 4 3
Silky-Rock Fuji Rock Suprastone Vel-mix
n = 15 for each combination of impression material and Type IV gypsum product.
Table III. Results of 2-way ANOVA tests between Type IV gypsum products, impression materials, and interaction between Type IV gypsum products and impression materials Source
Type III Sum of squares
df
149.5* 2581.3 120.0 6.7 22.7 47.2 2778.0 196.667
19 1 3 4 12 280 300 299
Corrected model Intercept Gypsum Impression material Gypsum 3 Impression material Error Total Corrected total
Mean square
7.9 2581.3 40 1.7 1.90 0.17
F
Significance
46.7 15313 237.3 9.9 11.2
.000 .000 .000 .000 .000
*R2=.76 (adjusted R2=.74).
Table V. Table shows results of multiple comparisons by impression material type using post hoc Bonferroni test Table IV. Results of multiple comparisons by Type IV gypsum product using post hoc Bonferroni test Fuji Rock
Silky-Rock Fuji Rock Suprastone
542
P,.001 – –
Suprastone
P,.001 P,.001 –
Vel-Mix
P=.177 P,.001 P,.001
Examix-NDS Doric-ES Flo-Light Panasil Contact Plus Extrude Wash
Doric-ES Flo-Light
Panasil Contact Plus
Extrude Wash
President Plus Jet
P=.464 – – –
P=1.000 P,.001 – –
P,.001 P=1.000 P,.001 –
P=.041 P=1.000 P,.001 P=1.000
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THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 4. Bar graph showing mean rank of each Type IV gypsum product by impression material.
RESULTS The Kappa statistic revealed a good agreement between the examiners on scoring of the specimens (K = 10.85). Intraexaminer agreement was also good, as the Kappa value for examiner 1 was 10.82 and 10.72 for examiner 2. All of the impression materials used in this study were able to fully reproduce (score 4) the 20-mm line. This was not the case for the resultant Type IV gypsum product dies that were poured. Table II shows the median quality scores obtained from the Type IV gypsum product dies and relates them to the impression material from which they were poured. Suprastone was the only Type IV gypsum product that achieved a median score of 4 with all the impression materials. Results of the 2-way ANOVA are summarized in Table III and reveal significant differences (P,.001) as a function of the Type IV gypsum products, the impression materials, and an interaction between Type IV gypsum products and impression materials. Multiple comparisons using the Bonferroni test for Type IV gypsum products and impression materials are shown in Tables IV and V, respectively. To allow direct comparison of each Type IV gypsum product by impression material combination, mean ranks were calculated and are illustrated graphically in Figure 4.
DISCUSSION The null hypothesis that there was no significant difference between the compatibility of the additionreaction silicone impression brands and the 4 Type IV gypsum products was rejected. The results of this study demonstrate that impression materials tested do not interact in the same way with the Type IV gypsum products tested. Clinically, this is important, as loss of JUNE 2005
surface detail can result in an inaccurate die and a poorly fitting casting.1 All of the impression materials used were able to fully reproduce the 20-mm line on all occasions. This is consistent with the results of previous studies.6,10 However, once the impressions were poured, some of the resultant Type IV gypsum product dies exhibited a loss of detail reproduction. The performances of the Type IV gypsum products were all significantly different with the exception of Silky-Rock and Vel-Mix. The following pairs of impression materials were significantly different: Examix-NDS and Extrude Wash, Examix-NDS and President Plus, Doric-ES Flo-Light and Panasil Contact Plus, Panasil Contact Plus and Extrude Wash, and Panasil Contact Plus and President Plus Jet. To the authors’ knowledge, this is the first study to suggest that different addition-reaction silicone materials may exhibit altered compatibility with different Type IV gypsum products. Future research is required to assess the size of any errors that may be generated in indirect restorations as a result of the loss of surface detail seen with some of the impression material and Type IV stone combinations. This study tested the compatibility of impression materials and gypsum products solely on the ability to reproduce surface detail in the cast. It should be noted that other factors, such as complete setting expansion, contact angle, the effect of impression material and liquid media on the surface hardness, compressive strength, and solubility of the Type IV gypsum product, should also be considered when selecting an impression material/gypsum combination. The use of the mean ranks used in Figure 4 allows the clinician/technician to select the most appropriate Type IV gypsum product to be poured against the 5 impression materials tested based solely on compatibility. It 543
THE JOURNAL OF PROSTHETIC DENTISTRY
also reports the relative performance of the different impression materials with the Type IV gypsum products. It should be noted that without exception, Suprastone exhibited the best compatibility with all the impression materials tested and, based on the results of this project, should be suggested as the Type IV gypsum product of choice to be used with the tested addition-reaction silicone impression materials.
CONCLUSIONS Within the limitations of this study, the following conclusions were drawn: 1. All of the impression materials tested met the ADA specification for surface detail reproducibility. Not all addition-reaction silicone impression materials tested were compatible with all of the Type IV gypsum products used in this study. 2. Suprastone exhibited the best compatibility with all of the addition-reaction impression materials tested. The authors thank the manufacturers for donating all the addition-reaction silicone impression materials and Type IV dental stones used in this study.
REFERENCES 1. Lorren RA, Salter DJ, Fairhurst CW. The contact angles of die stone on impression materials. J Prosthet Dent 1976;36:176-80. 2. American Dental Association. Council on Dental Materials and Devices. Revised American Dental Association Specification No.19 for non-aqueous, dental elastomeric dental impression materials. J Am Dent Assoc 1977;94:733-41.
544
BUTTA ET AL
3. Panichuttra R, Jones RM, Goodacre C, Mun˜oz CA, Moore BK. Hydrophillic poly(vinyl siloxane) impression materials: dimensional accuracy, wettability, and effect on gypsum hardness. Int J Prosthodont 1991;4:240-8. 4. Schelb E, Mazzocco CV, Jones JD, Prihoda T. Compatibility of Type IV dental stones with polyvinyl siloxane impression materials. J Prosthet Dent 1987;58:19-22. 5. Gerrow JD, Schneider RL. A comparison of the compatibility of elastomeric impression materials, Type IV dental stones, and liquid media. J Prosthet Dent 1987;57:292-8. 6. Schelb E, Cavazos E Jr, Troendle KB, Prihoda TJ. Surface detail reproduction of Type IV dental stones with selected polyvinyl siloxane impression material. Quintessence Int 1991;22:51-5. 7. Derrien G, Le Menn GL. Evaluation of detail reproduction for three die materials by using scanning electron microscopy and two-dimensional profilometry. J Prosthet Dent 1995;74:1-7. 8. al-Omari WM, Jones JC, Wood DJ. The effect of disinfecting alginate and addition cured silicone rubber impression materials on the physical properties of impressions and resultant casts. Eur J Prosthodont Restor Dent 1998;6:103-10. 9. Ragain JC, Grosko ML, Raj M, Ryan TN, Johnston WM. Detail reproduction, contact angles, and die hardness of elastomeric impression and gypsum die material combinations. Int J Prosthodont 2000;13:214-20. 10. Omana HM, Rinne VW, Truong TT. Compatibility of impressions and die stone material. Oper Dent 1990;15:82-5. Reprint requests to: MR CHRISTOPHER JEREMY TREDWIN UNIVERSITY COLLEGE LONDON EASTMAN DENTAL INSTITUTE 256 GRAYS INN ROAD LONDON, ENGLAND WC1X 8LD FAX: 144 (0) 207 915 1028 E-MAIL: [email protected] 0022-3913/$30.00 Copyright Ó 2005 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2005.04.006
VOLUME 93 NUMBER 6
Purpose. The purpose of this study was to compare surface detail reproduction between various combinations of contemporary addition-reaction silicone impression materials and Type IV gypsum products.
Material and methods. Under standardized conditions, 300 impressions were made of a ruled stainless steel die (ADA specification 19), using 5 addition-reaction silicones (Examix-NDS, Doric-ES Flo-Light, Panasil Contact Plus, Extrude Wash, and President Plus Jet). Fifteen impressions of each material were poured with each Type IV gypsum product (Silky-Rock, Fuji Rock, Suprastone, or Vel-Mix). Using 312 magnification, 2 independent examiners scored the reproducibility of a 20-mm line in both the impression and the resultant casts. Statistical analysis was performed using 2-way analysis of variance and post hoc Bonferroni testing (a=.05). Results. All impression materials tested fully reproduced the 20-mm line. Different impression materials showed different compatibility with different Type IV gypsum products. Only 25% of the Type IV gypsum casts completely reproduced the resultant 20-mm line with fine margins, and 88% of the completely reproduced casts were made from Suprastone. Conclusion. Not all combinations of impression material and Type IV gypsum products used exhibited similar compatibility. (J Prosthet Dent 2005;93:540-4.)
CLINICAL IMPLICATIONS This study demonstrated that for optimal compatibility, clinicians and technicians should carefully select the combination of silicone impression material and Type IV gypsum product.
T
he correct use of impression and die materials is essential for consistent and reliable fabrication of stone casts and dies. The use of incompatible materials may cause poor reproducibility, lack of surface detail, and bubbles in the definitive cast, which may result in an inaccurate die and a poorly fitting casting.1 The American National Standards Institute and American Dental Association (ANSI/ADA) Specification No. 19 specifies the use of an unmodified, a-hemihydrate gypsum in determining whether an impression material is compatible with dental stones.2 If a 20-mm-wide line in the surface of an impression material specimen is reproduced in the gypsum cast at between 34 and 312 magnification, the
a
Graduate student. Clinical Lecturer, Honorary Specialist Registrar in Restorative Dentistry. c Technical Instructor. d Senior Clinical Lecturer in Health Sciences Research. b
540 THE JOURNAL OF PROSTHETIC DENTISTRY
impression material has satisfied the ‘‘compatibility with gypsum’’ requirement. Differences in dimensional stability, wettability, and surface hardness have been identified for gypsum casts poured against various elastomeric impression materials.3 The hydrophobic characteristics of addition-reaction silicone impression materials are well known and make it difficult to pour a bubble-free stone cast.1 Although some studies have reported on compatibility between combinations of impression materials and dental stones, reports have been sparse in recent years regarding detail reproducibility of different brands of Type IV gypsum products and addition-reaction silicone impression materials.4-9 A lack of surface detail reproduction on the die is one manifestation of a compatibility problem. The purpose of this study was to compare the compatibility of 5 brands of addition-reaction silicone impression material with 4 brands of Type IV gypsum product, in relation to detail reproducibility. The null hypothesis was that there was no significant difference between the compatibility VOLUME 93 NUMBER 6
BUTTA ET AL
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 1. Photograph of ADA test die used in this study.
among these addition-reaction silicone impression brands and the 4 Type IV gypsum products.
MATERIAL AND METHODS The impression materials and Type IV gypsum products tested in this study are listed in Table I. The ADA test die (Ravensfield Design, Lancashire, UK) inscribed with 3 horizontal and 2 vertical lines is shown in Figures 1 through 3. The study was performed in accordance with ADA specification 19.2 Using each of the 5 impression materials, 60 impressions were randomly made of the ADA test block at 34°C and stored for 1 hour at ambient laboratory conditions (room temperature, 21°23°C, and humidity, 30%-40%). Fifteen impressions of each material were randomly assigned to be poured with 1 of the 4 Type IV gypsum products using manufacturer recommended water/powder ratios and vacuum mixing. Impressions were poured using vibration and a slight angulation. Using a microscope (Wild M5; Wild-Heerbrugg Ltd, Heerbrugg, Switzerland) at 312 magnification with standardized low angle (20 degrees) illumination, 2 independent examiners randomly examined both the impression material and the associated cast and scored the reproducibility of the middle 20-mm horizontal line (Figs. 1, 2, and 3). The criteria used to score the reproducibility were adapted from a previous study.5 A score of 4 represented perfect reproducibility of the original line on the ADA test block, which is a sharp V shape; a score of 3 represented slight loss of clarity with the V shape becoming rounded; a score of 2 showed that part of the line was not recorded, and a score of 1 showed that the line was not reproduced at all. Both examiners repeated the scoring for all the silicone and gypsum specimens on different days. The worst score obtained from the 2 examiners was used to provide the final score. Randomization throughout the experiment was achieved using a computer-generated random number JUNE 2005
Fig. 2. Diagrammatic representation of ADA test die shown in Figure 1. Surface detail reproducibility of impressions and associated casts was measured via qualitative assessment of Line b duplication. Table I. Materials tested in study Impression materials
Batch no.
Examix-NDS Doric-ES Flo-Light
0210081 510641
Panasil Contact Plus Extrude Wash President Plus Jet
30401 2-1112 MC533
Gypsum products Silky-Rock Fuji Rock
018503008 030127
Suprastone
3-1071
Vel-Mix
2-2127
Manufacturer
GC America, Alsip, Ill Davis, Schottlander & Davis, Letchworth, UK Kettenbach, Eschenburg, Germany Kerr, Orange, Calif Coltene AG, Altstatten, Switzerland. Whip Mix, Louisville, Ky GC Europe, Leuven, Belgium, Europe Kerr Italia, Salerno, Italy, Europe Kerr Italia, Salerno, Italy, Europe
list. The Kappa statistic (K) was used to assess interexaminer and intraexaminer agreement. Two-way analysis of variance (ANOVA) was used to test for any differences between impression material and Type IV gypsum product compatibility (a=.05). A conservative post hoc test correction was applied (Bonferroni multiple comparisons test) to see what difference occurred between the mean values of subgroups. 541
THE JOURNAL OF PROSTHETIC DENTISTRY
BUTTA ET AL
Fig. 3. Side profile diagrammatic representation of ADA test die, showing point A-A in Figure 2 enlarged.
Table II. Median reproducibility quality scores obtained for Type IV gypsum products related to impression materials from which poured Impression material
Type IV gypsum product
Examix-NDS
Doric-ES Flo-Light
Panasil Contact Plus
Extrude Wash
President Plus Jet
2 3 4 3
2 3 4 3
2 3 4 2
2 4 4 2
3 3 4 3
Silky-Rock Fuji Rock Suprastone Vel-mix
n = 15 for each combination of impression material and Type IV gypsum product.
Table III. Results of 2-way ANOVA tests between Type IV gypsum products, impression materials, and interaction between Type IV gypsum products and impression materials Source
Type III Sum of squares
df
149.5* 2581.3 120.0 6.7 22.7 47.2 2778.0 196.667
19 1 3 4 12 280 300 299
Corrected model Intercept Gypsum Impression material Gypsum 3 Impression material Error Total Corrected total
Mean square
7.9 2581.3 40 1.7 1.90 0.17
F
Significance
46.7 15313 237.3 9.9 11.2
.000 .000 .000 .000 .000
*R2=.76 (adjusted R2=.74).
Table V. Table shows results of multiple comparisons by impression material type using post hoc Bonferroni test Table IV. Results of multiple comparisons by Type IV gypsum product using post hoc Bonferroni test Fuji Rock
Silky-Rock Fuji Rock Suprastone
542
P,.001 – –
Suprastone
P,.001 P,.001 –
Vel-Mix
P=.177 P,.001 P,.001
Examix-NDS Doric-ES Flo-Light Panasil Contact Plus Extrude Wash
Doric-ES Flo-Light
Panasil Contact Plus
Extrude Wash
President Plus Jet
P=.464 – – –
P=1.000 P,.001 – –
P,.001 P=1.000 P,.001 –
P=.041 P=1.000 P,.001 P=1.000
VOLUME 93 NUMBER 6
BUTTA ET AL
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 4. Bar graph showing mean rank of each Type IV gypsum product by impression material.
RESULTS The Kappa statistic revealed a good agreement between the examiners on scoring of the specimens (K = 10.85). Intraexaminer agreement was also good, as the Kappa value for examiner 1 was 10.82 and 10.72 for examiner 2. All of the impression materials used in this study were able to fully reproduce (score 4) the 20-mm line. This was not the case for the resultant Type IV gypsum product dies that were poured. Table II shows the median quality scores obtained from the Type IV gypsum product dies and relates them to the impression material from which they were poured. Suprastone was the only Type IV gypsum product that achieved a median score of 4 with all the impression materials. Results of the 2-way ANOVA are summarized in Table III and reveal significant differences (P,.001) as a function of the Type IV gypsum products, the impression materials, and an interaction between Type IV gypsum products and impression materials. Multiple comparisons using the Bonferroni test for Type IV gypsum products and impression materials are shown in Tables IV and V, respectively. To allow direct comparison of each Type IV gypsum product by impression material combination, mean ranks were calculated and are illustrated graphically in Figure 4.
DISCUSSION The null hypothesis that there was no significant difference between the compatibility of the additionreaction silicone impression brands and the 4 Type IV gypsum products was rejected. The results of this study demonstrate that impression materials tested do not interact in the same way with the Type IV gypsum products tested. Clinically, this is important, as loss of JUNE 2005
surface detail can result in an inaccurate die and a poorly fitting casting.1 All of the impression materials used were able to fully reproduce the 20-mm line on all occasions. This is consistent with the results of previous studies.6,10 However, once the impressions were poured, some of the resultant Type IV gypsum product dies exhibited a loss of detail reproduction. The performances of the Type IV gypsum products were all significantly different with the exception of Silky-Rock and Vel-Mix. The following pairs of impression materials were significantly different: Examix-NDS and Extrude Wash, Examix-NDS and President Plus, Doric-ES Flo-Light and Panasil Contact Plus, Panasil Contact Plus and Extrude Wash, and Panasil Contact Plus and President Plus Jet. To the authors’ knowledge, this is the first study to suggest that different addition-reaction silicone materials may exhibit altered compatibility with different Type IV gypsum products. Future research is required to assess the size of any errors that may be generated in indirect restorations as a result of the loss of surface detail seen with some of the impression material and Type IV stone combinations. This study tested the compatibility of impression materials and gypsum products solely on the ability to reproduce surface detail in the cast. It should be noted that other factors, such as complete setting expansion, contact angle, the effect of impression material and liquid media on the surface hardness, compressive strength, and solubility of the Type IV gypsum product, should also be considered when selecting an impression material/gypsum combination. The use of the mean ranks used in Figure 4 allows the clinician/technician to select the most appropriate Type IV gypsum product to be poured against the 5 impression materials tested based solely on compatibility. It 543
THE JOURNAL OF PROSTHETIC DENTISTRY
also reports the relative performance of the different impression materials with the Type IV gypsum products. It should be noted that without exception, Suprastone exhibited the best compatibility with all the impression materials tested and, based on the results of this project, should be suggested as the Type IV gypsum product of choice to be used with the tested addition-reaction silicone impression materials.
CONCLUSIONS Within the limitations of this study, the following conclusions were drawn: 1. All of the impression materials tested met the ADA specification for surface detail reproducibility. Not all addition-reaction silicone impression materials tested were compatible with all of the Type IV gypsum products used in this study. 2. Suprastone exhibited the best compatibility with all of the addition-reaction impression materials tested. The authors thank the manufacturers for donating all the addition-reaction silicone impression materials and Type IV dental stones used in this study.
REFERENCES 1. Lorren RA, Salter DJ, Fairhurst CW. The contact angles of die stone on impression materials. J Prosthet Dent 1976;36:176-80. 2. American Dental Association. Council on Dental Materials and Devices. Revised American Dental Association Specification No.19 for non-aqueous, dental elastomeric dental impression materials. J Am Dent Assoc 1977;94:733-41.
544
BUTTA ET AL
3. Panichuttra R, Jones RM, Goodacre C, Mun˜oz CA, Moore BK. Hydrophillic poly(vinyl siloxane) impression materials: dimensional accuracy, wettability, and effect on gypsum hardness. Int J Prosthodont 1991;4:240-8. 4. Schelb E, Mazzocco CV, Jones JD, Prihoda T. Compatibility of Type IV dental stones with polyvinyl siloxane impression materials. J Prosthet Dent 1987;58:19-22. 5. Gerrow JD, Schneider RL. A comparison of the compatibility of elastomeric impression materials, Type IV dental stones, and liquid media. J Prosthet Dent 1987;57:292-8. 6. Schelb E, Cavazos E Jr, Troendle KB, Prihoda TJ. Surface detail reproduction of Type IV dental stones with selected polyvinyl siloxane impression material. Quintessence Int 1991;22:51-5. 7. Derrien G, Le Menn GL. Evaluation of detail reproduction for three die materials by using scanning electron microscopy and two-dimensional profilometry. J Prosthet Dent 1995;74:1-7. 8. al-Omari WM, Jones JC, Wood DJ. The effect of disinfecting alginate and addition cured silicone rubber impression materials on the physical properties of impressions and resultant casts. Eur J Prosthodont Restor Dent 1998;6:103-10. 9. Ragain JC, Grosko ML, Raj M, Ryan TN, Johnston WM. Detail reproduction, contact angles, and die hardness of elastomeric impression and gypsum die material combinations. Int J Prosthodont 2000;13:214-20. 10. Omana HM, Rinne VW, Truong TT. Compatibility of impressions and die stone material. Oper Dent 1990;15:82-5. Reprint requests to: MR CHRISTOPHER JEREMY TREDWIN UNIVERSITY COLLEGE LONDON EASTMAN DENTAL INSTITUTE 256 GRAYS INN ROAD LONDON, ENGLAND WC1X 8LD FAX: 144 (0) 207 915 1028 E-MAIL: [email protected] 0022-3913/$30.00 Copyright Ó 2005 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2005.04.006
VOLUME 93 NUMBER 6