- Email: [email protected]
Use of luting agents with an implant system: Part II
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 <0.05.
RESULTS
JOURNAL
IV. Tukey HSD comparison of retentive strength values for luting agent groups
Table
Table II displays the calculated retentive strength data for each of the three luting agents. An analysis of variance was performed (a (0.05) for comparison of the differently spaced castings within each luting agent group. The results from this analysis are presented in Table III. A significant difference was found to exist within each group; therefore, a Tukey Honestly Significantly Different (HSD) test (a <0.05) was performed to determine where the differences existed between spaced groups (Table IV). Within the Core Paste group, the 0.000 inch spaced castings were found to exhibit a significantly lower mean retentive strength than the other spaced castings. The Resiment group 0.000 inch spaced castings exhibited a mean retentive strength that was significantly lower than that of the 0.002 inch spaced group. The 0.000 inch spaced castings cemented with zinc phosphate were found to be signidicantly lower in mean retentive strength than the 0.003 inch spaced group.
TEE
Mean
OF PROSTHETIC
DENTISTRY
Luting Core
agent
Mean (kg)
Tukey group
0.001 0.003 0.002 0.000
145.667 145.167 144.500 124.833
A A A B
Resiment
0.002 0.003 0.001 0.000
136.750 129.792 129.350 118.292
A AB AB B
Zinc
0.003 0.001 0.002 0.000
60.500 51.833 49.875 40.833
A AB AB B
Means
Paste
Spacing (inch)
Phosphate
with
the same letter
are not significantly
different
at a <0.05.
887
DIXON,
Table
V. One-way Spacing
ANOVA
(inch)
comparison
of retentive
SOUl-Ce
DF 2 33 35 2 33 35 2 33 35 2 33 35
52394.3472 2486.0625 54880.4097 60319.0467 5953.3033 66272.3500 66244.8750 6893.3125 73138.1875 48824.6806 7921.3958 56746.0764
Error
Corr. total Model
0.001
Error
Corr. total Model Error Corr. total Model
0.002
0.003
Error
Corr. total *Significant
AND
group F Value
P”
26197.1736 75.3352
347.74
0.0001
30159.5233 180.4031
167.18
0.0001
33122.4375 208.8883
158.57
0.0001
24412.3403 240.0423
101.70
0.0001
Mean
LILLY
square
at a <0.05.
Table VI. Tukey HSD comparison values for the spacing groups Spacing group (inch)
Luting
agent
of retentive
Mean
(kg)
strength
Tukey
group
0.000
Core Paste Resiment Zinc Phosphate
124.833 118.292 40.833
A A B
0.001
Core Paste Resiment Zinc Phosphate
145.667 129.350 51.833
A B C
0.002
Core Paste Resiment Zinc Phosphate
144.500 136.750 49.875
A A B
Core Paste Resiment Zinc Phosphate
145.167 129.792 60.500
A A B
0.003
values by spacing
Sum of squares
Model
0.000
strength
BREEDING,
Means with the came letter
are not significantly
different
at a <0.05.
Analysis of variance was used to ascertain whether differences existed between the luting agents within the differently spaced groups of castings (a <0.05) (Table V). Significant differences were found within each group, and a Tukey HSD test (a! <0.05) was then done to determine between which luting agent groups these differences occurred (Table VI). Within each spacing group, zinc phosphate luting agent was found to have a significantly lower mean retentive strength than the Core Paste and Resiment luting agents. Core Paste luting agent was found to exhibit a similar mean retentive strength to Resiment luting agent in the 0.000 inch, 0.002 inch, and 0.003 inch groups. Within the 0.001 inch spaced group, all mean retentive strength values were shown to be significantly different. The changes in the precementation and postcementation distances between each of the three sets of points located on each casting/abutment pair were averaged. The result-
ing calculated seating discrepancies are shown in Table VII. Table VIII displays the results from an analysis of variance comparison (LY <0.05) of seating discrepancy values by spacing group. A significant difference was found within the 0.000 inch, 0.001 inch, and the 0.002 inch spaced groups. Following a Tukey HSD test (Table IX), it was observed that Core Paste cemented castings generated the largest mean seating discrepancies within the 0.000 inch, 0.001 inch, and 0.002 inch spaced groups. Resiment and zinc phosphate cemented specimens within the 0.001 inch and 0.002 inch spaced groups were found to generate similar seating discrepancies.
DISCUSSION The technique used to produce the series of die spacings in this investigation produced a uniform luting agent space between the entire casting/abutment interface. This is different from conventional fixed prosthodontic laboratory techniques in which the marginal areas of the dies are not spaced. Unless the premanufactured abutments are prepared clinically to produce a marginal area similar to a tooth preparation, the experimental technique used in this investigation would mimic clinical practice. The unspaced casting/abutment combinations produced the lowest retentive strength values and highest seating discrepancies for all three luting agents. Brukl et al.1° also evaluated seating discrepancies with zinc phosphate and a resin luting agent. With unvented castings made with no die relief and cemented onto a tooth, this group of investigators obtained mean seating discrepancies of 0.321 mm to 0.378 mm with the resin luting agent and 0.064 mm with zinc phosphate. These values are very similar to those obtained in this study for Core Paste (0.310 mm) and zinc phosphate (0.054 mm) luting agents. The use of 0.001 inch spacing reduced the seating discrepancies of zinc phosphate (0.003 mm) and Resiment (0.017 mm) luting agents. Core Paste luting agent required spacing of 0.003 inch to reach the same value as the 0.001 inch spaced Resiment group (0.017 mm). The 0.003 inch spaced zinc phosphate
DECEMBER
1992
VOLUME
68
NUMBER
6
LUTING
AGENTS
Table
VII.
AND
IMPLANT
SYSTEM
Calculated seating discrepancy data for each luting agent
Spacing group (inch)
N
Mean seating discrepancy (mm)
SD
SEM
Variance
CV
0.000
Core Paste
Resiment Zinc Phosphate 0.001 Core Paste Resiment Zinc Phosphate 0.002 Core Paste Resiment Zinc Phosphate 0.003 Core Paste Resiment Zinc Phosphate
Table
0.1871 0.0541
0.0824 0.0708 0.1254
0.0238 0.0204 0.0362
0.0068 0.0050 0.0157
-26.601 -38.852 -231.695
12 12 12
0.1661 0.0173 0.0032
0.1382 0.0558 0.0459
0.0399
0.0161 0.0132
0.0191 0.0031 0.0021
-83.196 -322.896 -1412.114
12 12 12
0.1007 0.0028 0.0022
0.1297 0.0600 0.0839
0.0374 0.0173 0.0242
0.0168 0.0036 0.0070
-128.862 -2117.846 -3872.389
12 12 12
0.0167 0.0230 -
0.1354 0.1465 -
0.0391
0.0183 0.0215 -
-811.206 -636.241 -
0.3096
0.0423 -
One-way ANOVA comparison of seating discrepancy values by spacing group
VIII. Spacing
12 12 12
(inch)
source
DF
Sum
of squares
Mean
square
Model Error Corr. total
2 33 35
0.3918 0.3028 0.6947
Model Error Corr. total
2 33 35
0.1956 0.2675 0.4631
0.0978
0.002
Model Error Corr. total
2 33 35
0.0771 0.3022 0.3793
0.003
Model Error Corr. total
1 22 23
0.0002 0.4379 0.4382
0.000
0.001
P*
F Value
21.35
0.0001
12.06
0.0001
0.0385 0.0092
4.21
0.0235
0.0002 0.0199
0.01
0.9134
0.1959
0.0092
0.0081
*Significant at ol 10.05.
specimens were not measured for seating discrepancies because the 0.002 inch spaced group had already exhibited very low values. Any seating discrepancy would result in a change in occlusion from the time of precementation to postcementation. During this investigation, a value of 25 lrn was arbitrarily established as an acceptable seating discrepancy. Even this small value, however, would result in the need for postcementation
occlusal
JOURNAL
OF PROSTHETIC
Spacing
(inch)
DENTISTRY
Luting
agent
Mean
(mm)
Tukey
group
0.000
Zinc Phosphate Resiment Core Paste
0.0541 0.1871 0.3096
A B C
0.001
Zinc Phosphate Resiment Core Paste
0.0033 0.0173 0.1661
A A B
0.002
Zinc Phosphate Resiment Core Paste
0.0022 0.0028 0.1007
A A B
0.003
Core Paste Resiment
0.0167 0.0230
A A
adjustment.
There was no significant difference between the mean retentive values recorded with the groups where spacing was used for any of the luting agents. The use of a thick luting agent space between the superstructure and abutment, without loss of retentive strength, could potentially allow the Ming agent to act as a shock absorber for occlusal forces.
THE
Table IX. Tukey HSD comparison of seating discrepancy values for the spacing groups
Means with the same letter are not significantly differentata
~0.05.
889
DIXON,
CLINICAL
IMPLICATIONS
The use of die spacing in the fabrication of cementable implant-supported superstructures can reduce seating discrepancies and, therefore, occlusal discrepancies, without reducing retentive values for the three luting agents tested. ONCLUSIONS The results from this investigation show the following conclusions. 1. Spacing did not reduce retentive values for any of the specimen groups. The resin luting agent groups exhibited consistently higher retentive strength than the zinc phosphate specimens. 2. Zinc phosphate and Resiment luting agents exhibited seating discrepancy values below 25 pm with 0.001 inch luting agent spacing. Core Paste cemented specimens required 0.003 inch spacing to show values below 25 pm. REFERENCES 1. Eames WB, O’Neal SJ, Mont&o J, Miller C, Roan JD, Cohen KS. Techniques to improve the seating of castings. J Am Dent Assoc 1978;96:432-37. 2. Grajower R, Zuberi Y, Lewinstein I. Improving the fit of crowns with die spacers. J PROSTHET DENT 1989;61:555-63.
Availability
of
JOURNAL
BREEDING,
AND
LILLY
3. Vermilyea SG, Kuffler MJ, Huget EF. The effects of die reiief agent on the retention of full-coverage castings. J PROSTHET DENT 1983;50:20710. 4. Hembree JH, Cooper EW. Effect of die relief on retention of cast crowns and inlays. Oper Dent 1979;4:104-7. 5. Van Nortwick WT, Gettleman L. Effect of internal relief, vibration, and venting on the vertical seating of cemented CI‘OWIIS. J PROSTHET DENT 1981;45:395-99. 6. Marker VA, Miller AW, Miller BH, Swepston JH. Factors affecting the retention and fit of gold castings. J PROSTHET DENT 1987;57:425-30. 7. Oliva RA, Lowe JA. Effect of die spacer on the seating of cast restorations on composite core preparations. J PROSTHET DENT 1987;58:29-35. 8. Rieger MR, Tanquist RA, Brose MO, Ali M. Measuring the thickness of a paint-on die spacer. J PROSTHET DENT 1987;58:305-8. 9. Campbell SD. Comparison of conventional paint-on die spacers and those used with the all-ceramic restorations. J PROSTHET DENT 1990;63:151-55. 10. Brukl CE, Nicholson JW, Norling BK. Crown retention and seating on natural teeth with a resin cement. J PROSTHET DENT 1985;53:618-22. 11. Lee H, Schwartz ML. Evaluation of a composite resin crown and bridge luting agent. J Dent Res 1972;51:756-66. Reprint requests to: DR. DONNA L. DIXON DEPARTMENT OF RESTORATIVE DENTISTRY UNIVERSITY OF ALABAMA AT BIRMINGHAM Box 82, SDB 1919 ~TH AVE. SOUTH BIRMINGHAM. AL 35294
back
issues,
1986-1991
Back issues of THE JOURNAL OF PROSTHETIC DENTISTRY are available for purchase from the publisher, Mosby-Year Book, Inc., at a cost of $7.00 per issue. (Foreign postage is not included.) The following quantity discounts are available: 25 % off on quantities of 12 to 23, and one third off on quantities of 24 or more. Please write to Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, or call (800)325-4177, ext. 4351, or (314)453-4351 for information on availability of particular issues for that period from 1980 to 1991. If unavailable from the publisher, photocopies of complete issues are available from University Microforms International, 300 N. Zeeb Rd., Ann Arbor, MI 48106, (313)761-4700.
890
DECEMBER
1992
VOLUME
68
NUMBER
6
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 <0.05.
RESULTS
JOURNAL
IV. Tukey HSD comparison of retentive strength values for luting agent groups
Table
Table II displays the calculated retentive strength data for each of the three luting agents. An analysis of variance was performed (a (0.05) for comparison of the differently spaced castings within each luting agent group. The results from this analysis are presented in Table III. A significant difference was found to exist within each group; therefore, a Tukey Honestly Significantly Different (HSD) test (a <0.05) was performed to determine where the differences existed between spaced groups (Table IV). Within the Core Paste group, the 0.000 inch spaced castings were found to exhibit a significantly lower mean retentive strength than the other spaced castings. The Resiment group 0.000 inch spaced castings exhibited a mean retentive strength that was significantly lower than that of the 0.002 inch spaced group. The 0.000 inch spaced castings cemented with zinc phosphate were found to be signidicantly lower in mean retentive strength than the 0.003 inch spaced group.
TEE
Mean
OF PROSTHETIC
DENTISTRY
Luting Core
agent
Mean (kg)
Tukey group
0.001 0.003 0.002 0.000
145.667 145.167 144.500 124.833
A A A B
Resiment
0.002 0.003 0.001 0.000
136.750 129.792 129.350 118.292
A AB AB B
Zinc
0.003 0.001 0.002 0.000
60.500 51.833 49.875 40.833
A AB AB B
Means
Paste
Spacing (inch)
Phosphate
with
the same letter
are not significantly
different
at a <0.05.
887
DIXON,
Table
V. One-way Spacing
ANOVA
(inch)
comparison
of retentive
SOUl-Ce
DF 2 33 35 2 33 35 2 33 35 2 33 35
52394.3472 2486.0625 54880.4097 60319.0467 5953.3033 66272.3500 66244.8750 6893.3125 73138.1875 48824.6806 7921.3958 56746.0764
Error
Corr. total Model
0.001
Error
Corr. total Model Error Corr. total Model
0.002
0.003
Error
Corr. total *Significant
AND
group F Value
P”
26197.1736 75.3352
347.74
0.0001
30159.5233 180.4031
167.18
0.0001
33122.4375 208.8883
158.57
0.0001
24412.3403 240.0423
101.70
0.0001
Mean
LILLY
square
at a <0.05.
Table VI. Tukey HSD comparison values for the spacing groups Spacing group (inch)
Luting
agent
of retentive
Mean
(kg)
strength
Tukey
group
0.000
Core Paste Resiment Zinc Phosphate
124.833 118.292 40.833
A A B
0.001
Core Paste Resiment Zinc Phosphate
145.667 129.350 51.833
A B C
0.002
Core Paste Resiment Zinc Phosphate
144.500 136.750 49.875
A A B
Core Paste Resiment Zinc Phosphate
145.167 129.792 60.500
A A B
0.003
values by spacing
Sum of squares
Model
0.000
strength
BREEDING,
Means with the came letter
are not significantly
different
at a <0.05.
Analysis of variance was used to ascertain whether differences existed between the luting agents within the differently spaced groups of castings (a <0.05) (Table V). Significant differences were found within each group, and a Tukey HSD test (a! <0.05) was then done to determine between which luting agent groups these differences occurred (Table VI). Within each spacing group, zinc phosphate luting agent was found to have a significantly lower mean retentive strength than the Core Paste and Resiment luting agents. Core Paste luting agent was found to exhibit a similar mean retentive strength to Resiment luting agent in the 0.000 inch, 0.002 inch, and 0.003 inch groups. Within the 0.001 inch spaced group, all mean retentive strength values were shown to be significantly different. The changes in the precementation and postcementation distances between each of the three sets of points located on each casting/abutment pair were averaged. The result-
ing calculated seating discrepancies are shown in Table VII. Table VIII displays the results from an analysis of variance comparison (LY <0.05) of seating discrepancy values by spacing group. A significant difference was found within the 0.000 inch, 0.001 inch, and the 0.002 inch spaced groups. Following a Tukey HSD test (Table IX), it was observed that Core Paste cemented castings generated the largest mean seating discrepancies within the 0.000 inch, 0.001 inch, and 0.002 inch spaced groups. Resiment and zinc phosphate cemented specimens within the 0.001 inch and 0.002 inch spaced groups were found to generate similar seating discrepancies.
DISCUSSION The technique used to produce the series of die spacings in this investigation produced a uniform luting agent space between the entire casting/abutment interface. This is different from conventional fixed prosthodontic laboratory techniques in which the marginal areas of the dies are not spaced. Unless the premanufactured abutments are prepared clinically to produce a marginal area similar to a tooth preparation, the experimental technique used in this investigation would mimic clinical practice. The unspaced casting/abutment combinations produced the lowest retentive strength values and highest seating discrepancies for all three luting agents. Brukl et al.1° also evaluated seating discrepancies with zinc phosphate and a resin luting agent. With unvented castings made with no die relief and cemented onto a tooth, this group of investigators obtained mean seating discrepancies of 0.321 mm to 0.378 mm with the resin luting agent and 0.064 mm with zinc phosphate. These values are very similar to those obtained in this study for Core Paste (0.310 mm) and zinc phosphate (0.054 mm) luting agents. The use of 0.001 inch spacing reduced the seating discrepancies of zinc phosphate (0.003 mm) and Resiment (0.017 mm) luting agents. Core Paste luting agent required spacing of 0.003 inch to reach the same value as the 0.001 inch spaced Resiment group (0.017 mm). The 0.003 inch spaced zinc phosphate
DECEMBER
1992
VOLUME
68
NUMBER
6
LUTING
AGENTS
Table
VII.
AND
IMPLANT
SYSTEM
Calculated seating discrepancy data for each luting agent
Spacing group (inch)
N
Mean seating discrepancy (mm)
SD
SEM
Variance
CV
0.000
Core Paste
Resiment Zinc Phosphate 0.001 Core Paste Resiment Zinc Phosphate 0.002 Core Paste Resiment Zinc Phosphate 0.003 Core Paste Resiment Zinc Phosphate
Table
0.1871 0.0541
0.0824 0.0708 0.1254
0.0238 0.0204 0.0362
0.0068 0.0050 0.0157
-26.601 -38.852 -231.695
12 12 12
0.1661 0.0173 0.0032
0.1382 0.0558 0.0459
0.0399
0.0161 0.0132
0.0191 0.0031 0.0021
-83.196 -322.896 -1412.114
12 12 12
0.1007 0.0028 0.0022
0.1297 0.0600 0.0839
0.0374 0.0173 0.0242
0.0168 0.0036 0.0070
-128.862 -2117.846 -3872.389
12 12 12
0.0167 0.0230 -
0.1354 0.1465 -
0.0391
0.0183 0.0215 -
-811.206 -636.241 -
0.3096
0.0423 -
One-way ANOVA comparison of seating discrepancy values by spacing group
VIII. Spacing
12 12 12
(inch)
source
DF
Sum
of squares
Mean
square
Model Error Corr. total
2 33 35
0.3918 0.3028 0.6947
Model Error Corr. total
2 33 35
0.1956 0.2675 0.4631
0.0978
0.002
Model Error Corr. total
2 33 35
0.0771 0.3022 0.3793
0.003
Model Error Corr. total
1 22 23
0.0002 0.4379 0.4382
0.000
0.001
P*
F Value
21.35
0.0001
12.06
0.0001
0.0385 0.0092
4.21
0.0235
0.0002 0.0199
0.01
0.9134
0.1959
0.0092
0.0081
*Significant at ol 10.05.
specimens were not measured for seating discrepancies because the 0.002 inch spaced group had already exhibited very low values. Any seating discrepancy would result in a change in occlusion from the time of precementation to postcementation. During this investigation, a value of 25 lrn was arbitrarily established as an acceptable seating discrepancy. Even this small value, however, would result in the need for postcementation
occlusal
JOURNAL
OF PROSTHETIC
Spacing
(inch)
DENTISTRY
Luting
agent
Mean
(mm)
Tukey
group
0.000
Zinc Phosphate Resiment Core Paste
0.0541 0.1871 0.3096
A B C
0.001
Zinc Phosphate Resiment Core Paste
0.0033 0.0173 0.1661
A A B
0.002
Zinc Phosphate Resiment Core Paste
0.0022 0.0028 0.1007
A A B
0.003
Core Paste Resiment
0.0167 0.0230
A A
adjustment.
There was no significant difference between the mean retentive values recorded with the groups where spacing was used for any of the luting agents. The use of a thick luting agent space between the superstructure and abutment, without loss of retentive strength, could potentially allow the Ming agent to act as a shock absorber for occlusal forces.
THE
Table IX. Tukey HSD comparison of seating discrepancy values for the spacing groups
Means with the same letter are not significantly differentata
~0.05.
889
DIXON,
CLINICAL
IMPLICATIONS
The use of die spacing in the fabrication of cementable implant-supported superstructures can reduce seating discrepancies and, therefore, occlusal discrepancies, without reducing retentive values for the three luting agents tested. ONCLUSIONS The results from this investigation show the following conclusions. 1. Spacing did not reduce retentive values for any of the specimen groups. The resin luting agent groups exhibited consistently higher retentive strength than the zinc phosphate specimens. 2. Zinc phosphate and Resiment luting agents exhibited seating discrepancy values below 25 pm with 0.001 inch luting agent spacing. Core Paste cemented specimens required 0.003 inch spacing to show values below 25 pm. REFERENCES 1. Eames WB, O’Neal SJ, Mont&o J, Miller C, Roan JD, Cohen KS. Techniques to improve the seating of castings. J Am Dent Assoc 1978;96:432-37. 2. Grajower R, Zuberi Y, Lewinstein I. Improving the fit of crowns with die spacers. J PROSTHET DENT 1989;61:555-63.
Availability
of
JOURNAL
BREEDING,
AND
LILLY
3. Vermilyea SG, Kuffler MJ, Huget EF. The effects of die reiief agent on the retention of full-coverage castings. J PROSTHET DENT 1983;50:20710. 4. Hembree JH, Cooper EW. Effect of die relief on retention of cast crowns and inlays. Oper Dent 1979;4:104-7. 5. Van Nortwick WT, Gettleman L. Effect of internal relief, vibration, and venting on the vertical seating of cemented CI‘OWIIS. J PROSTHET DENT 1981;45:395-99. 6. Marker VA, Miller AW, Miller BH, Swepston JH. Factors affecting the retention and fit of gold castings. J PROSTHET DENT 1987;57:425-30. 7. Oliva RA, Lowe JA. Effect of die spacer on the seating of cast restorations on composite core preparations. J PROSTHET DENT 1987;58:29-35. 8. Rieger MR, Tanquist RA, Brose MO, Ali M. Measuring the thickness of a paint-on die spacer. J PROSTHET DENT 1987;58:305-8. 9. Campbell SD. Comparison of conventional paint-on die spacers and those used with the all-ceramic restorations. J PROSTHET DENT 1990;63:151-55. 10. Brukl CE, Nicholson JW, Norling BK. Crown retention and seating on natural teeth with a resin cement. J PROSTHET DENT 1985;53:618-22. 11. Lee H, Schwartz ML. Evaluation of a composite resin crown and bridge luting agent. J Dent Res 1972;51:756-66. Reprint requests to: DR. DONNA L. DIXON DEPARTMENT OF RESTORATIVE DENTISTRY UNIVERSITY OF ALABAMA AT BIRMINGHAM Box 82, SDB 1919 ~TH AVE. SOUTH BIRMINGHAM. AL 35294
back
issues,
1986-1991
Back issues of THE JOURNAL OF PROSTHETIC DENTISTRY are available for purchase from the publisher, Mosby-Year Book, Inc., at a cost of $7.00 per issue. (Foreign postage is not included.) The following quantity discounts are available: 25 % off on quantities of 12 to 23, and one third off on quantities of 24 or more. Please write to Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, or call (800)325-4177, ext. 4351, or (314)453-4351 for information on availability of particular issues for that period from 1980 to 1991. If unavailable from the publisher, photocopies of complete issues are available from University Microforms International, 300 N. Zeeb Rd., Ann Arbor, MI 48106, (313)761-4700.
890
DECEMBER
1992
VOLUME
68
NUMBER
6