Effect of Cyanoacrylate on Die Stone

7/29/2019 Effect of Cyanoacrylate on Die Stone

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Effects of cyanoacrylates on die stoneHabib H. Chahremannezhad, D.M.D.,* Shawky E. Mohamed, D.D.S., M.S.,**Gregory P. Stewart, Ph.D.,*** and Roger Weinberg, M.S., Ph.D.***Louisiana State University Medical Center, New Orleans, La., and Southern Illinois University, Edwardsville, III

S veral techniques have been proposed to improvethe properties of gypsum products when used as diematerials in the construction of crowns and fixedpartial dentures. These techniques use several prod-ucts, including acrylic resins, copal varnish, polyure.thane, polyvinyl resins, soap solutions, sulfonated fa tt!acids, epoxy resins, and amyl acetates.le5The resultshave been debatable and inconclusive. Most recentlyFukui et al. studied the effect of cyanoacrylates on diestones. Cyanoacrylate resin sets rapidly, does notrequire special equipment for processing, and seems obe a promising material for use in prosthodontics. Thisstudy reports the effects of the application of cyanoac-rylates on die stone, including changes in the dimen-sions of the die, in the hardness of the die surface, andin the numbers of layers of resin that can be appliedsafely.MATERIAL AND METHODS

The effects of two types of cyanoacrylates on twotypes of dental stone, mixed with either distilled wateror a hardener, were studied. The arrangement of thevariables and the types of material studied are shown inTable I.To simulate clinical conditions as closely as possible,molds for stone blocks were made of polysiliconeputty/wash impression material (Optosil/Xantopren,Unitek Corp., Monrovia, Calif.) using custom-madeacrylic resin trays. Each die stone was mixed withdistilled water or hardener, according to the manufac-

Read before the Carl 0. Boucher Prosthodontic Conference, Colum-bus, Ohio.Supported by a grant from Louisiana State University MedicalCenter, School of Dentistry.

*Senior Resident in prosthodontics, Louisiana State UniversityMedical Center.**Professor of Fixed Prosthodontics, Louisiana State UniversityMedical Center.

**Associate Professor and Head, Section of Biomaterials, SouthernIllinois University, School of Dental Medicine.

****Professor of Biometry, Louisiana State University MedicalCenter.

THE 1OURNAL OF PROSTHETIC DENTISTRY

Fig. 1. A micrometer is used to measure changes inheight of stone block on application of cyanoacryiateresin on each of 10 test sites.

Fig. 2. Scratch resistance instrument.turers recommendations and American Dental Associ-ation specifieations,5 using a water-to-powder ratio of0.23. The mixes were vibrated into the polysiliconemolds and allowed to set for 1 hour. The stone blockswere removed from the mold, which was then cleansed,rinsed with distilled water, and allowed to dry beforebeing used to fabricate another stone block. All stoneblocks were allowed to remain at room temperature(22 to 24 C) for at least 24 hours before being

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GHAHREMANNEZHAD ET AL

Table I. Distribution of variables and groups in the experimental designVariables

StoneVel-Mix (Kerr

Mfg. Co.,Romulus,Mich.)Silky Rock(Whip-MixCorp.,Louisville, Ky.)

LiquidDistilled water

Stalite hardener (BuffaloDental Mfg. Co.,Brooklyn, N.Y.)

CyanoacrylateMDS (McDonald

Severy Products,Inc., Orange, Calif.)

Eastman 910 (EastmanChemical Co.,Kingsport, Tenn.)

Groups1. Vel-Mix, distilled water, MDS2. Vel-Mix, distilled water, Eastman 9103. Vel-Mix, Stalite, MDS4. Vel-Mix, Stalite, Eastman 9105. Silky Rock, distilled water, MDS6. Silky Rock, distilled water, Eastman 91C7. Silky Rock, Stalite, MDS8. Silky Rock, Stalite, Eastman 910

Table II. Mean for dimensional changes of stone on application of different numbers of coats ofcyanoacrylate resin (in micrometers)

Type of cyano-No. acrylate resin Type of liquid Type of stoneof Eastman Silky Overallcoats MDS 910 Water Hardener Vel-Mix Rock mean SD* SEMt

1 0.67 1.29 1.04 0.92 0.96 1 0.98 0.6 0.022 2.21 4.38 3.29 3.29 3.31 3.3 3.3 1.03 0.043 7.25 9.86 8.63 8.48 8.61 8.5 8.55 1.71 0.074 17.3 20.1 18.6 18.8 18.83 18.53 18.68 2.92 0.12p < .05p


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EFFECTS OF CYANOACRYLATES ON DIE STONE

Average ncrease in heightof stone (urn)252015105t.,J

Numberof coatsof cyanoacrylates Numberof coatsof cyanoacrylatesFig. 3. Increase in height of stone blocks made of typeIV dental stone and number of coats of cyanoacrylates Fig. 4. Changes in surface hardness (KHN) of type IVdental stone following application of cyanoacrylateapplied to surface. resin coats.

AverageKnoopHardnessNumber6050403020100

Table III. Mean for Knoop hardness of stone on application of different numbers of coats ofcyanoacrylate resin_- -_-. _ _ _Type of cyano-

No. _ acrylate resin Type of liquid Type of stoneof Eastman Silky Overall

coats MVS 910 Water Hardener Vel-Mix Rock moan SW SEMt0 21.61 55.32 42.13 30.64 26.4

21.6 18 25.252.8 48.4 59.739.7 35.4 46.430.6 32.4 28.826.8 27 26.1

not significant (paired f-test)

21.6 21.654 5440.1 41.830.3 30.827.5 25.6

21.6 1.26 0.0454 6.26 0.2240.9 4.87 0.1730.6 4.44 0.1626.6 4.63 0.16

p < .os(Student-Neuman-Keuls,original data)

*SD = Standard deviation.+SEM = Standard error of the mean

block for 24 hours, following the manufacturers rec-ommendations.Scratch resistance

three-coat, and four-coat subgroups. The blocks wereplaced in a 50 C oven for 1 hour to ensure moisture-free blocks and constant weight during the test. Theblocks were then handled with surgical gloves.A total of 200 stone blocks was made in eight groups A machine was constructed specifically for thisof 25 each. Each group was divided randomly into five purpose after Toreskog et al. It allowed the stonesubgroups as follows: control, one-coat, two-coat, blocks to be attached to a carriage that moved back andTHE JOURNAL OF PROSTHETIC DENTISTRY 641


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Mean weight lossdue to abrasion (grams150-45 -40 -35 -30 -25 -

?0 I I I I0 1 2 3 4Numberof coatsof cyanoacrylatesFig. 5. Mean weight loss of stone blocks after beingsubjected to scraping by a No. 10 Bard Parker blade inscratch resistance instrument and foilowing appiica-tion of increasing number of coats of cyanoacry-late resin.forth a distance of approximately 8 cm at the approxi-mate rate of 3 cm/set. An arm was suspended abovethe stone block on which weights and scraping instru-ments could be attached (Fig. 2).The cyanoacrylate resin was applied on the surfaceof the stone block and the excess removed by an airblast at approximately 30 psi. As in the surfacehardness test this cyanoacry late coat, as well as the lastcoat in multiple applications, was allowed to set for 24hours to ensure maximum hardness. The stone blockwas then placed on the carriage of the testing machine,and with a 250 gm load and a new No. 10 Bard Parkersurgical blade the carriage was allowed to.move backand forth 50 times. The stone block was cleaned byapplying a blast of compressed air. The stone block wasweighed before and after applying the scratch resis-tance test, using a laboratory scale (Sauter LaboratoryScale, August Sauter of Amerika, Inc., New York,N.Y.) with the smallest reading at 0.0001 gm. Theprocedure was repeated for the remaining control andexperimental groups.Surface morphology

Samples of the stone blocks, approximately 3 x4 X 2 mm, representing the eight experimental groups642


and containing no coats and one, two, three, and fourcoats of cyanoacrylates were used for this part of thestudy. The samples were metal coated with platinum/palladium and observed under the scanning electronmicroscope (SEM) using different magnifications.RESULTSDimensional change

Type IV dental stone blocks increased in height byapproximately 1 pm when one layer of cyanoacrylatewas applied to the surface and the excess removed by ablast of air. The application of additional coats of resinincreased the height of the stone blocks (Fig. 3 andTable II). These findings generally agree with those ofFukui et al6 The increase in height when the MDSbrand was used was slightly less than that whenEastman 910 was used, but the difference did not seemto be significant clinically.Surface hardness

The surface hardness (Knoop Hardness Number[KHN] ) of type IV dental stone increased from 21.6 to54 on application of one coat of cyanoacrylate. As thenumber of coats of applied cyanoacrylates increased,the surface hardness decreased (Fig. 4 and TableIII). These differences were statistically significant(p < .OS) using the Student-Neuman-Keuls analysis ofvariance. The KHN of uncoated dental stone mixedwith hardener was higher than that of uncoated dentalstone mixed with distilled water by 28.6%. Applyingone coat of cyanoacrylate to the surface of set dentalstone mixed with distilled water increased the hardnessby 169% (from 18 to 48.8 KHN); stone mixed withhardener increased by 136% (from 25.2 to 59.7 KHN).These differences were significant (p < .02) using thepaired t-test. The results are in agreement with those ofEames et al. and Fukui et a1.6Scratch resistance

The average loss of weight for uncoated stone blockswhen subjected to the scratch test was 0.43 gm. Whenone coat of cyanoacrylate resin was applied to thesurface and allowed to harden, mean weight loss foreach block became 0.29 gm. As more coats of resin wereapplied, the weight loss was 0.33 gm (two coats), 0.35gm (three coats), and 0.37 gm (four coats) (Fig. 5 andTable IV).The difference between the two types of resins usedwas statistically significant but was so small that itappeared to be insignificant clinically.Uncoated stone blocks mixed with hardener were26% more resistant to scratches than uncoated stoneblocks mixed with distilled water.

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Fig. 6. SEM photograph of uncoated dental stone that was mixed with distilled water.Silky Rock and Vel-Mix were similar in appearance. (Original magnification X1,000.)

Table IV. Mean for scratch resistance of stone blocks on application of different numbers of coatsof cyanoacrylate resin (in grams)* --Type of cyano-No. -

acrylate resinof Eastman

coats MDS 910

Type of liquid

Water Hardener

Type of stone_.Silky OverallVel-Mix Rock mean

0 0.43 0.43 0.48 0.38 0.43 0.431 0.29 0.3 0.33 0.26 0.29 0.292 0.32 0.33 0.36 0.29 0.33 0.323 0.34 0.36 0.38 0.32 0.35 0.354 0.37 0.38 0.41 0.34 0.37 0.37

p < .02 p < .Ol(paired t-test) (paired t-test) not significant(paired t-test) --Both standard deviation and standard error of the mean are less than 0.01.*The lower the number, the higher the scratch resistance.

0.430.290.330.350.37

;7 < .05(Student-

Neuman-Keuls,original data)

Surface morphologySEM photographs of uncoated samples of type IVdental stone are shown in Figs. 6 and 7. Where dentalstone was mixed with distilled water, the prisms of thecrystalline structure of CaSO, were clearly evident(Fig. 6). When stone was mixed with hardener, theprismatic configuration changed into more inte-grated crystals with rounded edges and corners, thusproviding more physical support for the crystals

(Fig. 7).

When one coat of cyanoacrylate resin was applied tothe surface of the stone, areas between the crystalsseemed o develop a slightly glassy appearance, indicat-ing the filling-in of the pores (Figs. 8 to 11). Thedifference between the two types of adhesives did notseem to he appreciable. As the number of coats appliedincreased, the glassy layer became more ,evident andcontinuous. Clumps of set resin appeared on thesurface when four or five coats of resin were applied(Figs. 12 to 14).

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Fig. 7. SEM photograph of uncoated dental stone that was mixed with hardener(Stalite). Crystals are becoming more integrated with each other, giving appearance of anetwork. (Original magnification X1,000.)

DISCUSSIONOne-coat applicationThe results of this study showed that the applicationof one coat of cyanoacrylate resin on the surface of typeIV dental stone followed by removal of the excess resinby a blast of air resulted in (1) increased thickness ofthe die by approximately 1 brn, an insignificantamount; (2) increase in surface hardness by about150%; (3) increase in the stones resistance to scratch by

sharp instruments by 48%; and (4) closing of the poresand production of a shiny surface. This can be of helpin detecting scratches on the surface of the die made bynodules present inside metallic copings or crowns.The application of the resin on the scribed margin ofa die will also render the pencil line more permanent,obviating the necessity for repeated marking of themargin and making it easier to detect any chipping ofthe edges.Two-coat or more application

When two coats of cyanoacrylate resin were appliedon the surface of the die stone, the changes from theoriginal uncoated surface were as follows: (1) heightincrease was approximately 3 pm, which is stillinsignificant clinicallv; (2) surface hardness was more

than that o f the uncoated surface but less than theincrease in surface hardness on the application of onecoat; (3) scratch resistance increased from that of theuncoated surface, but the increase was less than whenone coat was applied; and (4) surface morphologychanges were similar to those observed on the applica-tion of one coat but were more numerous.The application of more than two coats produceddimensional changes of 8 pm or more. Surface hardnessand scratch resistance continued to decrease from thoseseen on one- and two-coat applications. Clumpsappearing on the surface of the stone die may alter thetopography of. the area of the margin of a crownpreparation and make the restoration deficient.CLINICAL APPLICATION

We recommend that after dies are sectioned andtrimmed, the margins be marked by a suitable pencil,undercuts blocked, and die spacer applied. A drop ofcyanoacrylate is dispensed on paper or disposable pads.A toothpick is used to apply the cyanoacrylate on thecoronal portion of the die, the marked margins, andslightly beyond the margin in an apical direction.Immediately after the resin is applied, the excess resinshould be blown away with compressed air. Care

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Figs, 8 to 11. SEM photographs of type IV dental stone after application of one coat ofcyanoacrylate resin. Pores are filled in slightly, and surface takes on a glassy appearance.(Original magnification X1,000.)

Figs. 12 to 14. When more than one coat of cyanoacrylate resin is applied to stone sur-face, glassy layer becomes more evident and appears thicker. Clumps of set resin beginto appear when four or more coats of resin are applied. (Original magnification Xl,O@O.)

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should be taken to avoid getting water in the air hoseand spraying excess resin on objects or persons close by.Compressed air is our favored method for removingexcess resin; in its absence gauze or lint-free paper maybe used. Best results are obtained when the die isnot completely dry before the application of theresin. Cyanoacrylates should not be applied to pinchannels.SUMMARY

An evaluation was made of the effects of theapplication of an increasing number of coats of cyano-acrylate on die stone. The application of one coat ofcyanoacrylate adhesive on the surface of trimmed andmarked dies increases the surface hardness, increasesthe scratch resistance, will not change the dimensions ofthe die appreciably, and renders the margin markingmore permanent. Excess resin should be removedimmediately by compressed air. The use of hardenerinstead of water is recommended for mixing Type IVdental stone. Use of the cyanoacrylate method will aidthe dentist and the technician in achieving an accuratecrown fit.

We would like to thank Dr. Nikhil Sarkar, Acting Head,Department of Biomaterials, and Dr. Lars V. Christensen, Depart-ment of Fixed Prosthodontics, for their assistance.

REFERENCES1.

2.3.

4.

5.6.

7.

8.

Eshleman, J. R.: Surface hardness and dimensional accuracy ofstone dies impregnated with acrylic resin. J Dent Res 50~507,1971.Mason, H. J.: Impregnation of stone dies with acrylic resin.J PROSTHETDENT !23:96, 1970.Hosada, H., Otani, H., Hirano, T., and Fusayama, T.:Measurement and reinforcement of the superficial hardness ofindirect stone models. J Dent Res 41:752, 1962.Conney, J. P ., and Jeannet, D. J.: Treatment of stone dies witha cyanoacrylate cement. J Dent Res 59~522, 1980 (Abstr No.1013).Guide to Dental Materials and Devices, ed 7. Chicago, 1974,American Dental Association, p 86.Fukui, H., Lacy, A. M., and Jendresen, M. D.: Effectiveness ofhardening films on die stone. J PROSTHET DENT 44:57,1980.Toreskog, S ., Phillips, R. W., and Schnell, R. J.: Properties ofdie materials: A comparative study. J PROSTHETDENT 16~119,1966.Eames, W. B ., Edwards, Jr., C. R., and Buck, Jr., W . H.:Scraping resistance of dental die materials: A comparison ofbrands. Oper Dent 3~66, 1978.

Reprint requests o:DR. SHAWKYE. MOHAMEDLOUISIANASTATE UNIVERSITYSCHOOLOF DENTISTRY1100 FLORIDA AVE.NEW ORLEANS,LA 70119

Bound volumes available to subscribersBound volumes of the JOURNAL FFROSTHPZICENTISTRY are available to subscribers (only) for the 1983 issues from thepublisher at a cost of $39.00 ($49.00 international) for Vol. 49 (January-June) and Vol. 50 (July-December). Shippingcharges are included. Each bound volume contains a subject and author index, and all advertising is removed. Copies areshipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the journalname, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mr. DeansLynch at The C. V. Mosby Co., 11830 Westline Industrial Drive, St. Louis, MO 63141, USA.Subscriptions must be in force to qualify. Bound volumes are not available in place of a regularJOURNAL. ubscription.

646 MAY 1983 VOLUME 49 NUMBER 5

Effect of Cyanoacrylate on Die Stone

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