of seating Shane Victor University
force on film thickness
IV. White, BA, BDentSc, Kipnis, PhD” of Southern
California,
MS, MA,a Zhaokun
School of Dentistry,
Yqb
of new adhesive
and
Los Angeles, Calif.
This study examined the effect of seating force on the film thickness of new adhesive luting agents. The method was in compliance with American National Standards/American Dental Association Specification No. 8 for zinc phosphate cement. The materials tested were zinc phosphate cement, glass ionomer cement, polyearboxylate cement, and a resinous cement with a dentinal bonding agent. All materials were manipulated exactly as described in the manufacturer’s instructions, and an electronic gauge with an accuracy of 0.5rm was used. Each class of material was measured 10 times at six different seating forces. Analysis of variance and multiple comparisons testing disclosed that the seating force and class of material strongly influenced the film thicknesses of luting agents. A mathematical model describing the response of zinc phosphate cement within the range tested was reported. (J PROSTHET DENT 1992;68:476-81.)
lthough zinc phosphate cement (ZP) has long been the principal luting agent for the cementation of castings,l several new classes of adhesive luting agents (ALA) have more recently been introduced. These include glass ionomer cements (GI), polycarboxylate cements (PC), and various types of resinous cements (R), most based on Bis-glycidylmethacrylate (Bis-GMA) with some inorganic filler.lm3 Some new ALAS have been shown to reduce microleakage, increase retention, and improve physical properties, compared with zinc phosphate cements.2-6 Differing components, particle sizes, viscosities, amounts of filler, and types of setting reaction may substantially influence the hydraulic response and therefore the film thicknesses of different classes of ALA. The time available for flow before set may not allow all classes of material sufficient opportunity to reach optimal minimal film thickness. Jorgensen7 has demonstrated that the film thickness of zinc phosphate cement is influenced by seating force, but appreciable differences were only recorded with loads below 5 kg. This may not be true for new ALAS. This study investigated the effect of seating force on the film thicknesses of new adhesive luting agents.
Presented at the annual meeting of the Pacific Coast Society of Prosthodontists. aResearch Assistant Professor and Director of Restorative Research, Department of Restorative Dentistry, University of California, School of Dentistry. bAssociate Professor, Department of Biomaterials Science, Research Institute of Stomatology, Beijing Medical University, Beijing, China. CAssistant Professor, Department of Preventive Medicine, University of California, School of Medicine. 10/1/39414
476
MATERIAL
AND
METHODS
The method was in compliance with American National Standards/American Dental Association Specification No. 8 for zinc phosphate cement, section 4.3.4.8 Tests were conducted at a room temperature of 23O C and with a relative humidity of 67 % , and all materials were manipulated exactly as described in the manufacturer’s instructions. A capsulated glass ionomer cement was mixed in an amalgam triturator (Capmix, ESPE, Seefeld/Oberbay, Germany). Prior to testing, two experienced investigators calibrated their techniques until uniformity was achieved. One investigator then made all the test specimens. A portion of the standard mix of cement was positioned between two flat, rounded glass plates of uniform thickness, with a surface area of 2 cm2. The same pair of plates was used in identical orientation for each measurement. Before each specimen was prepared, the plates were cleaned with water, then with acetone, and were allowed to volatilize. After each manufacturer’s recommended mixing time, various loads were applied vertically to the plates. An electronic gauge (Minicon Electronic Gauge, Seimitsu, Tokyo, Japan) with an accuracy of 0.5pm and a scale range of 300pm was selected, and measurements were recorded to the nearest micron. All measurements were recorded 10 minutes after mixing commenced. Applied loads of 1,3, 5,9, 15, and 23 kg were used to measure the film thickness of the control, zinc phosphate cement, and the three different classes of ALA. The instrument was recalibrated at each load on the cleaned glass plates before each measurement. Each ALA was measured 10 times independently at each load. The classes of material tested were: zinc phosphate cement (Flecks Zinc Phosphate, Keystone, Cherry Hill, N. J.); resinous cement with a dentinal bonding agent (DBA)
SEPTEMBER1992
VOLUME68
NUMBER3
EFFECT
OF SEATING
FORCE
ON FILM
Table I. Means and standard thickness
THICKNESS
deviations
Force (kg)
Material
Glass ionomer
Polycarboxylate
Zinc phosphate
23.5 22.6 19.9 20.4 19.5 16.9
1.6 1.2 1.3 1.6 1.6 1.6
1
48.6 29.9 27.1 24.5 21.0 15.8
4.0 2.0 3.2 1.6 2.2 1.5
3 5 9 15 23
78.6 66.0 67.3 46.8 41.7 36.4
2.8 2.9 2.1 1.3 0.5 2.0
1 3 5 9 15 23
42.2 35.3 32.5 32.1 28.1 27.0
3.6 1.9 1.8 2.4 2.6 1.4
DBA, Dentinal bonding agent
(Den-Mat Thin Film Cement and Tenure, Den-Mat, Santa Maria, Calif.); glass ionomer cement (Ketac-Cem Caplet, ESPE); and polycarboxylate cement (Durelon, ESPE). Based on the experimental design, a completely randomized two-way analysis of variance (ANOVA) was conducted to determine the effect and interaction of the two factors (ALA material and force applied) on the film thickness. The significance level for main effect was established at 5 % . If a significant two-way interaction was verified, the main effect ANOVA was anticipated with a simple main effect analyses. The differences between varying loads within each ALA group and between various ALAS at the same loads were analyzed by a series of one-way ANOVAs. The significance level for the follow-up tests were adjusted according to the Bonferroni’s inequality to keep the significance of the experiment identical to the main effect analyses. In all cases of significant differences, the Tukey’s multiple comparisons test was performed to determine which ALA groups and/or loads were statistically different or similar. An exploratory regression analysis was computed to de-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Main effect ANOVA
Source of variation
1 3 5 9 15 23
1
II.
Table
Mean (am)
3 5 9 15 23
Resin + DBA
of film
Material (M) Force (F) Interaction of h4 with F Error
Table
III.
ALAS within Load (kg)
DF
Sum of squares
3 5 15
42729 15156 7133
216
1020
3015 642 101
p-Value
force on film thickness
IV. White, BA, BDentSc, Kipnis, PhD” of Southern
California,
MS, MA,a Zhaokun
School of Dentistry,
Yqb
of new adhesive
and
Los Angeles, Calif.
This study examined the effect of seating force on the film thickness of new adhesive luting agents. The method was in compliance with American National Standards/American Dental Association Specification No. 8 for zinc phosphate cement. The materials tested were zinc phosphate cement, glass ionomer cement, polyearboxylate cement, and a resinous cement with a dentinal bonding agent. All materials were manipulated exactly as described in the manufacturer’s instructions, and an electronic gauge with an accuracy of 0.5rm was used. Each class of material was measured 10 times at six different seating forces. Analysis of variance and multiple comparisons testing disclosed that the seating force and class of material strongly influenced the film thicknesses of luting agents. A mathematical model describing the response of zinc phosphate cement within the range tested was reported. (J PROSTHET DENT 1992;68:476-81.)
lthough zinc phosphate cement (ZP) has long been the principal luting agent for the cementation of castings,l several new classes of adhesive luting agents (ALA) have more recently been introduced. These include glass ionomer cements (GI), polycarboxylate cements (PC), and various types of resinous cements (R), most based on Bis-glycidylmethacrylate (Bis-GMA) with some inorganic filler.lm3 Some new ALAS have been shown to reduce microleakage, increase retention, and improve physical properties, compared with zinc phosphate cements.2-6 Differing components, particle sizes, viscosities, amounts of filler, and types of setting reaction may substantially influence the hydraulic response and therefore the film thicknesses of different classes of ALA. The time available for flow before set may not allow all classes of material sufficient opportunity to reach optimal minimal film thickness. Jorgensen7 has demonstrated that the film thickness of zinc phosphate cement is influenced by seating force, but appreciable differences were only recorded with loads below 5 kg. This may not be true for new ALAS. This study investigated the effect of seating force on the film thicknesses of new adhesive luting agents.
Presented at the annual meeting of the Pacific Coast Society of Prosthodontists. aResearch Assistant Professor and Director of Restorative Research, Department of Restorative Dentistry, University of California, School of Dentistry. bAssociate Professor, Department of Biomaterials Science, Research Institute of Stomatology, Beijing Medical University, Beijing, China. CAssistant Professor, Department of Preventive Medicine, University of California, School of Medicine. 10/1/39414
476
MATERIAL
AND
METHODS
The method was in compliance with American National Standards/American Dental Association Specification No. 8 for zinc phosphate cement, section 4.3.4.8 Tests were conducted at a room temperature of 23O C and with a relative humidity of 67 % , and all materials were manipulated exactly as described in the manufacturer’s instructions. A capsulated glass ionomer cement was mixed in an amalgam triturator (Capmix, ESPE, Seefeld/Oberbay, Germany). Prior to testing, two experienced investigators calibrated their techniques until uniformity was achieved. One investigator then made all the test specimens. A portion of the standard mix of cement was positioned between two flat, rounded glass plates of uniform thickness, with a surface area of 2 cm2. The same pair of plates was used in identical orientation for each measurement. Before each specimen was prepared, the plates were cleaned with water, then with acetone, and were allowed to volatilize. After each manufacturer’s recommended mixing time, various loads were applied vertically to the plates. An electronic gauge (Minicon Electronic Gauge, Seimitsu, Tokyo, Japan) with an accuracy of 0.5pm and a scale range of 300pm was selected, and measurements were recorded to the nearest micron. All measurements were recorded 10 minutes after mixing commenced. Applied loads of 1,3, 5,9, 15, and 23 kg were used to measure the film thickness of the control, zinc phosphate cement, and the three different classes of ALA. The instrument was recalibrated at each load on the cleaned glass plates before each measurement. Each ALA was measured 10 times independently at each load. The classes of material tested were: zinc phosphate cement (Flecks Zinc Phosphate, Keystone, Cherry Hill, N. J.); resinous cement with a dentinal bonding agent (DBA)
SEPTEMBER1992
VOLUME68
NUMBER3
EFFECT
OF SEATING
FORCE
ON FILM
Table I. Means and standard thickness
THICKNESS
deviations
Force (kg)
Material
Glass ionomer
Polycarboxylate
Zinc phosphate
23.5 22.6 19.9 20.4 19.5 16.9
1.6 1.2 1.3 1.6 1.6 1.6
1
48.6 29.9 27.1 24.5 21.0 15.8
4.0 2.0 3.2 1.6 2.2 1.5
3 5 9 15 23
78.6 66.0 67.3 46.8 41.7 36.4
2.8 2.9 2.1 1.3 0.5 2.0
1 3 5 9 15 23
42.2 35.3 32.5 32.1 28.1 27.0
3.6 1.9 1.8 2.4 2.6 1.4
DBA, Dentinal bonding agent
(Den-Mat Thin Film Cement and Tenure, Den-Mat, Santa Maria, Calif.); glass ionomer cement (Ketac-Cem Caplet, ESPE); and polycarboxylate cement (Durelon, ESPE). Based on the experimental design, a completely randomized two-way analysis of variance (ANOVA) was conducted to determine the effect and interaction of the two factors (ALA material and force applied) on the film thickness. The significance level for main effect was established at 5 % . If a significant two-way interaction was verified, the main effect ANOVA was anticipated with a simple main effect analyses. The differences between varying loads within each ALA group and between various ALAS at the same loads were analyzed by a series of one-way ANOVAs. The significance level for the follow-up tests were adjusted according to the Bonferroni’s inequality to keep the significance of the experiment identical to the main effect analyses. In all cases of significant differences, the Tukey’s multiple comparisons test was performed to determine which ALA groups and/or loads were statistically different or similar. An exploratory regression analysis was computed to de-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Main effect ANOVA
Source of variation
1 3 5 9 15 23
1
II.
Table
Mean (am)
3 5 9 15 23
Resin + DBA
of film
Material (M) Force (F) Interaction of h4 with F Error
Table
III.
ALAS within Load (kg)
DF
Sum of squares
3 5 15
42729 15156 7133
216
1020
3015 642 101
p-Value
