f luting Donna Kevin University Kentucky, Iowa City,
L. Dixon, R. Lilly”
agents DMD,”
Larry
with
an implant
C. Breeding,
DMD,
system:
MSEd,b
Part
II
and
of Alabama at Birmingham, School of Dentistry, Birmingham, Ala., the University of College of Dentistry, Lexington, Ky., and the University of Iowa, College of Dentistry, Iowa
The purposes of this study were to determine the amount of die space necessary to reduce seating discrepancies of castings cemented onto implant abutments and to determine the effect that this space created for the luting-agent has on crown retention. Noble metal castings were made with 0.000 inch, 0.001 inch, 0.002 inch, and 0.003 inch spacing for premanufactured titanium implant abutments. The castings were cemented onto the abutments with three permanent luting agents. Seating discrepancies of each casting/abutment combination were measured, and the castings were pulled from the abutments by use of tensile force. The results of this study indicate that the use of die spacing decreased seating discrepancies and increased retentive values under the test conditions. (J PROSTHET DENT 1992;68:885-90.)
any current implant systems have abutments onto which superstructures can be cemented. Some dentists prefer cementation of fixed prostheses instead of attachment to the implant abutments by screws. The cementation technique mimics conventional fixed prosthodontic procedures used with teeth. The luting agent space existing between the crown and abutment allows for minor discrepancies in the fit of the prosthesis, The use of such a cemented superstructure, however, does not permit its removal for future maintenance. When cementing fixed prostheses to teeth and implant abutments, the dentist should be concerned not only with retention but also with the film thickness of the luting agent. Unacceptable marginal openings and large postcementation occlusal discrepancies may result from excessive film thicknesses. One method of compensation is the use of spacers painted on dies before crown fabrication.ld5 The effect of die spacer on seating discrepancies (marginal openings) of crowns fabricated for teeth has been examined by numerous authors. l, 2,4,5 Marker et a1.6in 1987 examined the use of die spacers on prepared Ivorine teeth (Columbia Dentoform Corp., New York, N.Y.) and the resulting seating discrepancies of cemented crowns. All of the articles cited indicated that a decrease in seating discrepancy occurred with die spacer addition. A wide range in the necessary thickness of die spacer to reduce seating discrepancies has been reported.lm5 The thickness and unifor-
aAssistant Professor, Department of Restorative versity of Alabama at Birmingham. bAssociate Professor, Department of Oral Health versity of Kentucky. CSenior dental student, University of Iowa. 10/l/40875
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Dentistry, Practice,
Uni-
mity of thickness of die spacers has also received attention,7-g with all reports indicating an inconsistency in the amount and uniformity of spacing. Zinc phosphate luting agent was used in all of these studies; however, only one investigation to date has shown resulting marginal seating discrepancy with the use of resin luting agents on teeth.lO The effect of die spacer application on the retention of castings has been reported with a wide range of values.l, 3,4 Eames et a1.l reported an average 25 % increase in retention with the addition of die spacer and the use of zinc phosphate luting agent. Vermilyea et al3 stated that that addition of die spacer caused an average 32% decrease in retention of crowns cemented with zinc phosphate luting agent. Hembree and Cooper4 found no effect on retention with the use of die spacers. The effect of die spacer on the retention of castings cemented with resin luting agents was reported in only one investigation.ll An increase in crown retention with the amount of spacing up to 75 pm was shown in this study. Similar seating discrepancy problems must be anticipated during the fabrication and cementing of fixed prostheses onto implant abutments. Of course, sensitivity or recurrent decay would not occur as a result of a crown/implant seating discrepancy; however, occlusal discrepancies and leakage, causing loss of retention, may be problems with inadequate seating of the prosthesis. The purpose of this investigation was to determine the amount of space necessary to reduce seating discrepancies of crowns cemented onto implant abutments and to determine the effect this would have on crown retention.
Uni-
MATERIAL
AND
METHODS
Twelve machined cementable implant abutments were obtained (Core-Vent, Core-Vent Corp., Encino, Calif.).
885
DIXON,
Table
I. Experimental
cementation
BREEDING,
AND
LILLY
sequences
Test sequence l-0.003 inch spacing A. ZRC B. ZCR C. RZC D. RCZ E. CRZ F. CZR Test sequence 2-0.002 inch spacing Repeat cementation sequence from 1 above. Test sequence 3-0.001 inch spacing Repeat cementation sequence from Test sequence 4-0.000 inch spacing
1 above.
Repeat cementation sequence from 1 above. 2, Zinc phosphate;
R, Resiment;
C, Core Paste.
Wax was placed 7 mm from the end of one abutment to form a 0.5 mm circumferential shoulder. A vinyl polysiloxane impression (Reprosil, Caulk Div., Dentsply Int. Inc., Milford, Del,) was then made of this waxed abutment and improved dental stone was used to form two dies from the impression. Next, one layer of 0.001 inch platinum foil was adapted on the occlusal surface and the axial surfaces of one die, and the impression and die formation procedures were repeated. Subsequently, 0.002 inch and 0.003 inch spaced dies were formed in the same manner. Twelve wax patterns were then made on each die by use of a dip-wax technique. A wax loop was attached to the occlusal portion of each pattern. The patterns were invested and cast in an alloy with high palladium content (Spartan Plus, Williams Gold Co., Buffalo, N. ‘II.) by conventional methods. After divesting and sprue removal, the castings were sandblasted with 125 pm A1203, all internal casting nodules were removed, and adaptation to the abutments was evaluated with the use of a disclosing medium (Fit-Checker, G-C Industrial Dental Corp., Tokyo, Japan). To standardize the surface characteristics of the castings throughout the investigation, the castings were placed in a burnout furnace at 1125” F for 1% hours and then immersed in a cement-removal solution (Removalon-I, Premier Dental Products Co., Norristown, Pa.) in an ultrasonic unit for 30 minutes. One casting of each relief value was arbitrarily assigned to each machined abutment. The 12 abutments were then subdivided into six groups (A through F) of two abutments each with their corresponding four castings each. Each casting was cemented onto its corresponding abutment with zinc phosphate luting agent (Z) (Flecks Zinc Cement, Mizzy, Inc., Cherry Hill, N. J.), Resiment resin luting agent (R) (AGUDA North America, Liberty, MO.), and Core Paste resin luting agent (C) (Den-Mat Corp., Santa Maria, Calif.) in the sequence shown in Table I. The luting agents were mixed according to the manufacturers’ instructions and placed in each casting with a plastic instrument. During luting, the castings were held on the abutments with finger pressure for 10 seconds and were then placed under a 6 kg constant weight for 10 minutes. Before and imme-
886
Fig. 1. Diagrammatic representat,ion of vertical measurement (AB) made in three places on each casting/abutment combination.
diately
after each cementation, the vertical distance bepoints, scribed in three places on each casting and on the abutment, was measured with a traveling microscope (Mitutoyo, Mitutoyo Mfg. Co., Tokyo, Japan) to determine seating discrepancy values (Fig. 1). The vertical distance at each of the three points was measured three times and recorded by the same investigator. One hour after cementation, each crown was pulled from each abutment with a 500 kg load cell at a crosshead speed of 0.5 cm/min on an Instron Universal testing machine (Instron Corp., Canton, MA). Residual luting agent was removed by hand. Only remaining residual luting agent was removed by placement in the burnout furnace for 1% hours at 1125” F before immersion in the ultrasonic solution. During the course of this investigation, each casting was cemented once with each of the three luting agents. Each abutment, therefore, had four castings cemented with each of the three luting agents for 12 total cementations. The seating discrepancies and luting agent retentive strength values were compared by use of appropriate statistical analyses. tween
DECEMBER
1992
VOLUME
68
NUMBER
6
LUTING
AGENTS
AND
IMPLANT
SYSTEM
Table II. Calculated retentive strength data for each luting agent Spacing
group
(inch)
N
Mean
(kg)
SD
SEM
Variance
cv
0.000 Core Paste Resiment Zinc Phosphate 3.001 Core Paste Resiment Zinc Phosphate 0.002 Core Paste Resiment Zinc Phosphate 0.003 Core Paste Resiment Zinc Phosphate
III.
Table
agent Paste
Resiment
Zinc
Phosphate
*Significant
124.833 118.292 40.833
8.558 10.212 6.962
2.471 2.948 2.010
73.242 104.294 48.470
6.856 8.633 17.050
12 12 12
145.667 129.350 51.833
12.934 17.041 9.139
3.734 4.919 2.638
167.288 290.406 83.515
8.879 13.175 17.631
12 12 12
144.500 136.750 49.875
14.759 16.592 11.556
4.260 4.790 3.336
217.818 275.295 133.551
10.214 12.133 23.171
12 12 12
145.167 129.792 60.500
21.219 11.303 11.922
6.125 3.263 3.442
450.242 127.748 142.136
14.617 8.708 19.706
One-way ANOVA comparison of retentive strength values by luting agent group
Luting Core
12 12 12
source
DF
Sum of squares
Model Error Corr. total Model Error Corr. total Model Error Corr. total
3 44 47 3 44 47 3 44 47
3708.9167 9994.5000 13703.4167 2095.8608 8775.1783 10871.0392 2344.0990 4484.3958 6828.4948
square
F Value
P*
1236.3056 227.1477
5.44
0.0029
698.6203 199.4359
3.50
0.0230
781.3663 101.9181
7.67
0.0003
at 01
L. Dixon, R. Lilly”
agents DMD,”
Larry
with
an implant
C. Breeding,
DMD,
system:
MSEd,b
Part
II
and
of Alabama at Birmingham, School of Dentistry, Birmingham, Ala., the University of College of Dentistry, Lexington, Ky., and the University of Iowa, College of Dentistry, Iowa
The purposes of this study were to determine the amount of die space necessary to reduce seating discrepancies of castings cemented onto implant abutments and to determine the effect that this space created for the luting-agent has on crown retention. Noble metal castings were made with 0.000 inch, 0.001 inch, 0.002 inch, and 0.003 inch spacing for premanufactured titanium implant abutments. The castings were cemented onto the abutments with three permanent luting agents. Seating discrepancies of each casting/abutment combination were measured, and the castings were pulled from the abutments by use of tensile force. The results of this study indicate that the use of die spacing decreased seating discrepancies and increased retentive values under the test conditions. (J PROSTHET DENT 1992;68:885-90.)
any current implant systems have abutments onto which superstructures can be cemented. Some dentists prefer cementation of fixed prostheses instead of attachment to the implant abutments by screws. The cementation technique mimics conventional fixed prosthodontic procedures used with teeth. The luting agent space existing between the crown and abutment allows for minor discrepancies in the fit of the prosthesis, The use of such a cemented superstructure, however, does not permit its removal for future maintenance. When cementing fixed prostheses to teeth and implant abutments, the dentist should be concerned not only with retention but also with the film thickness of the luting agent. Unacceptable marginal openings and large postcementation occlusal discrepancies may result from excessive film thicknesses. One method of compensation is the use of spacers painted on dies before crown fabrication.ld5 The effect of die spacer on seating discrepancies (marginal openings) of crowns fabricated for teeth has been examined by numerous authors. l, 2,4,5 Marker et a1.6in 1987 examined the use of die spacers on prepared Ivorine teeth (Columbia Dentoform Corp., New York, N.Y.) and the resulting seating discrepancies of cemented crowns. All of the articles cited indicated that a decrease in seating discrepancy occurred with die spacer addition. A wide range in the necessary thickness of die spacer to reduce seating discrepancies has been reported.lm5 The thickness and unifor-
aAssistant Professor, Department of Restorative versity of Alabama at Birmingham. bAssociate Professor, Department of Oral Health versity of Kentucky. CSenior dental student, University of Iowa. 10/l/40875
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Dentistry, Practice,
Uni-
mity of thickness of die spacers has also received attention,7-g with all reports indicating an inconsistency in the amount and uniformity of spacing. Zinc phosphate luting agent was used in all of these studies; however, only one investigation to date has shown resulting marginal seating discrepancy with the use of resin luting agents on teeth.lO The effect of die spacer application on the retention of castings has been reported with a wide range of values.l, 3,4 Eames et a1.l reported an average 25 % increase in retention with the addition of die spacer and the use of zinc phosphate luting agent. Vermilyea et al3 stated that that addition of die spacer caused an average 32% decrease in retention of crowns cemented with zinc phosphate luting agent. Hembree and Cooper4 found no effect on retention with the use of die spacers. The effect of die spacer on the retention of castings cemented with resin luting agents was reported in only one investigation.ll An increase in crown retention with the amount of spacing up to 75 pm was shown in this study. Similar seating discrepancy problems must be anticipated during the fabrication and cementing of fixed prostheses onto implant abutments. Of course, sensitivity or recurrent decay would not occur as a result of a crown/implant seating discrepancy; however, occlusal discrepancies and leakage, causing loss of retention, may be problems with inadequate seating of the prosthesis. The purpose of this investigation was to determine the amount of space necessary to reduce seating discrepancies of crowns cemented onto implant abutments and to determine the effect this would have on crown retention.
Uni-
MATERIAL
AND
METHODS
Twelve machined cementable implant abutments were obtained (Core-Vent, Core-Vent Corp., Encino, Calif.).
885
DIXON,
Table
I. Experimental
cementation
BREEDING,
AND
LILLY
sequences
Test sequence l-0.003 inch spacing A. ZRC B. ZCR C. RZC D. RCZ E. CRZ F. CZR Test sequence 2-0.002 inch spacing Repeat cementation sequence from 1 above. Test sequence 3-0.001 inch spacing Repeat cementation sequence from Test sequence 4-0.000 inch spacing
1 above.
Repeat cementation sequence from 1 above. 2, Zinc phosphate;
R, Resiment;
C, Core Paste.
Wax was placed 7 mm from the end of one abutment to form a 0.5 mm circumferential shoulder. A vinyl polysiloxane impression (Reprosil, Caulk Div., Dentsply Int. Inc., Milford, Del,) was then made of this waxed abutment and improved dental stone was used to form two dies from the impression. Next, one layer of 0.001 inch platinum foil was adapted on the occlusal surface and the axial surfaces of one die, and the impression and die formation procedures were repeated. Subsequently, 0.002 inch and 0.003 inch spaced dies were formed in the same manner. Twelve wax patterns were then made on each die by use of a dip-wax technique. A wax loop was attached to the occlusal portion of each pattern. The patterns were invested and cast in an alloy with high palladium content (Spartan Plus, Williams Gold Co., Buffalo, N. ‘II.) by conventional methods. After divesting and sprue removal, the castings were sandblasted with 125 pm A1203, all internal casting nodules were removed, and adaptation to the abutments was evaluated with the use of a disclosing medium (Fit-Checker, G-C Industrial Dental Corp., Tokyo, Japan). To standardize the surface characteristics of the castings throughout the investigation, the castings were placed in a burnout furnace at 1125” F for 1% hours and then immersed in a cement-removal solution (Removalon-I, Premier Dental Products Co., Norristown, Pa.) in an ultrasonic unit for 30 minutes. One casting of each relief value was arbitrarily assigned to each machined abutment. The 12 abutments were then subdivided into six groups (A through F) of two abutments each with their corresponding four castings each. Each casting was cemented onto its corresponding abutment with zinc phosphate luting agent (Z) (Flecks Zinc Cement, Mizzy, Inc., Cherry Hill, N. J.), Resiment resin luting agent (R) (AGUDA North America, Liberty, MO.), and Core Paste resin luting agent (C) (Den-Mat Corp., Santa Maria, Calif.) in the sequence shown in Table I. The luting agents were mixed according to the manufacturers’ instructions and placed in each casting with a plastic instrument. During luting, the castings were held on the abutments with finger pressure for 10 seconds and were then placed under a 6 kg constant weight for 10 minutes. Before and imme-
886
Fig. 1. Diagrammatic representat,ion of vertical measurement (AB) made in three places on each casting/abutment combination.
diately
after each cementation, the vertical distance bepoints, scribed in three places on each casting and on the abutment, was measured with a traveling microscope (Mitutoyo, Mitutoyo Mfg. Co., Tokyo, Japan) to determine seating discrepancy values (Fig. 1). The vertical distance at each of the three points was measured three times and recorded by the same investigator. One hour after cementation, each crown was pulled from each abutment with a 500 kg load cell at a crosshead speed of 0.5 cm/min on an Instron Universal testing machine (Instron Corp., Canton, MA). Residual luting agent was removed by hand. Only remaining residual luting agent was removed by placement in the burnout furnace for 1% hours at 1125” F before immersion in the ultrasonic solution. During the course of this investigation, each casting was cemented once with each of the three luting agents. Each abutment, therefore, had four castings cemented with each of the three luting agents for 12 total cementations. The seating discrepancies and luting agent retentive strength values were compared by use of appropriate statistical analyses. tween
DECEMBER
1992
VOLUME
68
NUMBER
6
LUTING
AGENTS
AND
IMPLANT
SYSTEM
Table II. Calculated retentive strength data for each luting agent Spacing
group
(inch)
N
Mean
(kg)
SD
SEM
Variance
cv
0.000 Core Paste Resiment Zinc Phosphate 3.001 Core Paste Resiment Zinc Phosphate 0.002 Core Paste Resiment Zinc Phosphate 0.003 Core Paste Resiment Zinc Phosphate
III.
Table
agent Paste
Resiment
Zinc
Phosphate
*Significant
124.833 118.292 40.833
8.558 10.212 6.962
2.471 2.948 2.010
73.242 104.294 48.470
6.856 8.633 17.050
12 12 12
145.667 129.350 51.833
12.934 17.041 9.139
3.734 4.919 2.638
167.288 290.406 83.515
8.879 13.175 17.631
12 12 12
144.500 136.750 49.875
14.759 16.592 11.556
4.260 4.790 3.336
217.818 275.295 133.551
10.214 12.133 23.171
12 12 12
145.167 129.792 60.500
21.219 11.303 11.922
6.125 3.263 3.442
450.242 127.748 142.136
14.617 8.708 19.706
One-way ANOVA comparison of retentive strength values by luting agent group
Luting Core
12 12 12
source
DF
Sum of squares
Model Error Corr. total Model Error Corr. total Model Error Corr. total
3 44 47 3 44 47 3 44 47
3708.9167 9994.5000 13703.4167 2095.8608 8775.1783 10871.0392 2344.0990 4484.3958 6828.4948
square
F Value
P*
1236.3056 227.1477
5.44
0.0029
698.6203 199.4359
3.50
0.0230
781.3663 101.9181
7.67
0.0003
at 01
