Readers’ round table
To
THE EDITOR:
As Caputo,
the creator and Trabert,
of
the “The
cyanoacrylate-cemented Relationship of
pin, I Cements,
Dental
object Pins,
to the report and Retention”
by
Hanson, (J. PROS-
DENT. 32: 428-434, 1974), because it is inaccurate and therefore misleading. Hanson, Caputo, and Trabert assumed from Fig. 1 of their report that the coarser thread of the TMS pin would give better retention than the finer thread of the Ellman and Beck pins. They produced data calculated to three decimal points (thousandths of a pound) to prove their preconceived idea. A coarser thread means more breakage when bending the pin. Perez, Schoeneck, and Yanaharal report a larger space between the regular self-threading pin and the dentin. This suggests more spare for marginal leakage and bacterial invasion. The first sentence under RESULTS proves that the figures on retention are false and contrived. The authors stated, “Visual examination of the pins after dislodgment revealed that virtually complete cement plugs were attached to all pins. This observation was common to all .variables tested.” (See Moffa photograph.*) This statement proves that there was no failure between the pins and the cement. The only possible variable factor would be a difference in retention between the luting agent and the dentin. Table II of their article shows retention figures of 6.680 pounds for the Ellman pin, 6.700 pounds for the TMS pin, and 5.578 pounds for the Beck pin when cemented with cyanoacrylate in a pinhole produced by an 0.027 inch drill. This proved that there was no difference in retention for various diameters or types of threaded pins. The significant variables are the depth and diameter of the pinhole which determine the length and diameter of the luting THET.
agent
plug and its subsequent retention A second serious error of this test, as well as all previous pin tests, is the assumption that covering a cemented pin with wax and then immersing it in water for seven days simulates intraoral cementing conditions. The professionally licensed N. Y. Testing Laboratory supplied the following retention data on cementing pins in a dry environmentp:
Ellman 5 15 30 60
0.023
inch
fiin
minutes minutes minutes minutes
with 10.0
24 hours
cyanoacrylate to
10.0
pounds
11.0
to
12.5
14.0
to
17.4
pounds pounds
14.9 22.1
to to
17.4 24.5
pounds pounds
TMS
22
0.024
to
27
inch
pin
pounds
The significant variable here is the time that the cyanoacrylate is permitted to polymerize before soaking it in water. The pin should be cemented under dry conditions (rubber dam can even be demanded) and then covered with amalgam or a composite resin which takes from 10 minutes to 24 hours to set. The preparation is then covered with a temporary crown until final crown is cemented over the amalgam or composite core. It is absurd to try to simulate these intraoral conditions by covering the pin with wax and then immersing the tooth in saline solution for seven days at 37” C. If the assumption that the tissue fluid difluses from the pulp and periodontal ligament through the dentinal tubules to the dentin-cement surface were true, then every crown or inlay cemented with zinc phosphate would fail within three months. All that is needed to remove hardened cement from a glass slab is to soak it for a few minutes in water, and the cement flakes off. Any dentist who has removed a crown knows that the cement clings to the dentin so tenaciously that it must be ground off. This would
224
*Personal
communication:
J. P. Moffa,
TPersonal
communication:
N.
Y. Testing
Oct.
24,
Laboratory,
1972. Feb.
8, 1973.
Volume 34 h’umber 2
Readers’
round
table
225
not be so if the tissue fluid had diffused through the dentinal tubules to the dentin-cement line. The third important area of criticism is that the authors considered the disadvantage of biologic trauma important enough to sacrifice the greater 27 pound retention of the TMS pin for the 14 pound retention of the zinc phosphate-cemented pin. However, when they compared the retention of the various cements, they disregarded the importance of chemical injury to the pulp by zinc phosphate cement and the pulp healing (biologic acceptability) of the cyanoacrylates. A fourth shortcoming of this test is the failure to recognize the findings of Moffa and associates’ that a cavity lining should be used with all pins to minimize leakage and prevent pulp injury from zinc phosphate cement. Moffa and associates showed that the cavity lining reduced the retention of cemented pins by 47 per cent. Since cyanoacrylate produces its own cavity lining and is nonirritating to the pulp, Bhaskar and co-workers3 stated that isobutyl cyanoacrylate needs no liner since it permits the pulp to repair itself. Carpenter and Bunge4 reported that two homologues of ethyl cyanoacrylate were not histotoxic to skin wounds. Assuming that the retention figures are accurate, correcting them for the use of a cavity liner will produce the following: TMS pin cemented with zinc phosphate, 14 pounds x 47 per cent = 7.4 pounds; TMS pin cemented with polycarboxylate, 8 pounds x 47 per cent = 4.2 pounds: and TMS pin cemented with cyanoacrylate remains at 6.7 pounds. A fifth shortcoming of all pin experiments is that they measure only tensile strength. The greater forces are compressive and lateral. This might explain the frequent failure of the self-threading pin. When compression is added to the strain produced by noncemented pins, the dentin fractures, causing pulpal injury.5 In summary, if a cavity lining is used, there is no difference in retention among pins or among cements. There may also be no retentive advantage for a self-threading pin over a cyanoacrylate-cemented pin if the N. Y. Testing Laboratory figures are more significant than the wax-immersion figures. With all the retention figures neutralized, the clinical advantages of the cyanoacrylate cemented pin are: (1) accidental exposures may repair, (2) no special instruments are needed as pins are easily inserted with a plier, and (3) the cyanoacrylate cement needs no mixing and cleanup. This may explain why two million Ellman pins have been successfully cemented with cyanoacrylate in three years. Four dentists have submitted letters testifying to the efficacy of the cyanoacrylate cement.* It is amazing how often tests like this, on extracted teeth, are accepted as dogma by intelligent researchers, who then close their minds to the clinical findings of thousands of dentists testing millions of pins over a period of three years. In the best interests of the practicing dentist and his patient, THE JOURNAL OF PROSTHETIC DENTISTRY should allow a prominent place for this letter in as early an edition as possible. This will enable the reader to better evaluate the clinical advantages of the cyanoacrylate-pin technique. IRVING A. ELLMAN, D.D.S. 558 WILLOW AVE. CEDARHURST, N.Y. 11516
*Personal communications: M. Sniderman, R. S. Krug, Aug. 21, 1974; and L. Baum, Aug.
Sept. 24, 20, 1974.
1974;
G. D. Kudler,
Aug.
22,
1974;
References 1. Perez,
E.,
Schoeneck, G., and Yanahara, H.: The Adaptation of Noncemented Pins, J. 26: 631-639, 1971. Moffa, J. P., Razzano, M. R., and Folio, J.: Influence of Cavity Varnish on Microleakage and Retention of Various Pin-Retaining Devices, J. PROSTHET. DENT. 20: 541-551, 1968. Bhaskar, S. N., Beasley, J. D., Ward, J. I’., and Cutright, D. E.: Human Pulp Capping With Isobutyl Cyanoacrylate, J. Dent. Res. 51: 58-61, 1972.
PROSTHET. DENT.
2. 3.
226 4. 5.
To
Readers’
round
table
,J. Prosthrt. Auwt,
Dent. 1975
Carpenter, W. M., and Bunge, J.: Tissue Response of Skin Wounds to Ethyl and Isobutyl Cyanoacrylate, Int. Assoc. Dent. Res. Abst. No. 657, May, 1974. Trabert, K. C., Caputo, A. A., Collard, E. W., and Standlee, J. P.: Stress Transfer to the Dental Pulp by Retentive Pins, J. PROSTHET. DENT. 30: 808-815, 1973.
THE EDITOR: Dr. Ellman, being the creator of the cyanoacrylate cemented-pin system, has failed to recognize any research other than his own. As yet, there have been no definitive clinical studies that complement and document laboratory studies. Therefore, at present, we must rely on the latter. For the most part, he considers this report inaccurate and misleading since it casts doubt on the cyanoacrylate system. For the benefit of the practicing dentist, we wish to place Dr. Ellman’s comments in the proper perspective with the following: ( 1) Our investigation was initiated and executed with complete objectivity and with no preconceived ideas concerning the outcome. It was our conviction to test various pin-cement combinations, thereby eliciting the optimum combination for retention. The practicing dentist may then have more guidance to follow in choice of a cemented-pin system. (2) The photograph in Fig. 1 was presented as being illustrative of the various pins employed in the study, and mention was neither made nor implied predicting their retentive capacities. In fact, the results did not indicate any correlation between coarseness and retention. The relative coarseness of threaded pins bears little relation to microleakage when employed in the cemented mode. Self-threading pins exhibit less adaptation to the channel wall than does a pin possessing a cement plug. It must be pointed out that reference No. 1 in Dr. Ellman’s letter does not relate to cemented pins. (3) Appropriate measuring procedures were followed to assure the accuracy of the retention values as reported. However, it should be noted that even rounding these values to tenths of a pound does not alter any of the results or conclusions. (4) Dr. Ellman carefully selected three vaIues of the 21 presented in Table II to prove a point. His attention should have been on all the figures, since this would have lead him to the conclusions presented in Table III. (5) Dr. Ellman, when carefully reading our report, will find that pins were not cemented into channels filled with moisture or debris. Cements were set for a minimum of 10 minutes in a dry environment before application of high-fusing inlay wax at the cement-tooth interface. Storage of specimens in physiologic saline for seven days preserved natural tooth hydration. This is a simulation of intraoral conditions where there is moisture present in the tooth. This moisture is maintained by the pulp and external tooth environment as was demonstrated by Wainwright and co-authors1 and Linden.21 s (6) Beech,4 using closely approximately flat surfaces with resultant small film thicknesses, showed that ethyl 2-cyanoacrylate manifested a high retention potential. Five minutes after cementation, the adherends were immersed in water and stored for varying periods of time up to seven days. However, with cemented pins, there exists a fairly large and variable film thickness between the pin and dentin wall. As a result, reduced retention is manifested. A recent article by the authors5 corroborates this line of reasoning. This article was concerned with the cementation of Whaledent Para-posts, employing minimal film thickness. The specimens used in this study, incidentally, utilized an inlay wax covering and were stored in physiologic saline for periods of up to 40 days. The results indicated no significant difference in retention among zinc phosphate, polycarboxylate, and cyanoacrylate cements. (7) Dr. Ellman states that cyanoacrylate has a potential pulp-healing effect. At present, there is only one actual in vivo human-pulp study demonstrating repair of an injured pulp. That was completed by Bhaskar and associates6 utilizing the isobutyl cyanoacrylate homologue (not ethyl 2-cyanoacrylate). The work of Carpenter and Bunger on rats, with ethyl 2-cyanoacrylate and isobutyl cyanoacrylate homologues, demonstrated no histotoxic reaction to either. Importantly though, this work did not involve a study of pulpal responses. (8) Copal resin varnishes, in most instances, should be applied to cut dentin in vital teeth
To
THE EDITOR:
As Caputo,
the creator and Trabert,
of
the “The
cyanoacrylate-cemented Relationship of
pin, I Cements,
Dental
object Pins,
to the report and Retention”
by
Hanson, (J. PROS-
DENT. 32: 428-434, 1974), because it is inaccurate and therefore misleading. Hanson, Caputo, and Trabert assumed from Fig. 1 of their report that the coarser thread of the TMS pin would give better retention than the finer thread of the Ellman and Beck pins. They produced data calculated to three decimal points (thousandths of a pound) to prove their preconceived idea. A coarser thread means more breakage when bending the pin. Perez, Schoeneck, and Yanaharal report a larger space between the regular self-threading pin and the dentin. This suggests more spare for marginal leakage and bacterial invasion. The first sentence under RESULTS proves that the figures on retention are false and contrived. The authors stated, “Visual examination of the pins after dislodgment revealed that virtually complete cement plugs were attached to all pins. This observation was common to all .variables tested.” (See Moffa photograph.*) This statement proves that there was no failure between the pins and the cement. The only possible variable factor would be a difference in retention between the luting agent and the dentin. Table II of their article shows retention figures of 6.680 pounds for the Ellman pin, 6.700 pounds for the TMS pin, and 5.578 pounds for the Beck pin when cemented with cyanoacrylate in a pinhole produced by an 0.027 inch drill. This proved that there was no difference in retention for various diameters or types of threaded pins. The significant variables are the depth and diameter of the pinhole which determine the length and diameter of the luting THET.
agent
plug and its subsequent retention A second serious error of this test, as well as all previous pin tests, is the assumption that covering a cemented pin with wax and then immersing it in water for seven days simulates intraoral cementing conditions. The professionally licensed N. Y. Testing Laboratory supplied the following retention data on cementing pins in a dry environmentp:
Ellman 5 15 30 60
0.023
inch
fiin
minutes minutes minutes minutes
with 10.0
24 hours
cyanoacrylate to
10.0
pounds
11.0
to
12.5
14.0
to
17.4
pounds pounds
14.9 22.1
to to
17.4 24.5
pounds pounds
TMS
22
0.024
to
27
inch
pin
pounds
The significant variable here is the time that the cyanoacrylate is permitted to polymerize before soaking it in water. The pin should be cemented under dry conditions (rubber dam can even be demanded) and then covered with amalgam or a composite resin which takes from 10 minutes to 24 hours to set. The preparation is then covered with a temporary crown until final crown is cemented over the amalgam or composite core. It is absurd to try to simulate these intraoral conditions by covering the pin with wax and then immersing the tooth in saline solution for seven days at 37” C. If the assumption that the tissue fluid difluses from the pulp and periodontal ligament through the dentinal tubules to the dentin-cement surface were true, then every crown or inlay cemented with zinc phosphate would fail within three months. All that is needed to remove hardened cement from a glass slab is to soak it for a few minutes in water, and the cement flakes off. Any dentist who has removed a crown knows that the cement clings to the dentin so tenaciously that it must be ground off. This would
224
*Personal
communication:
J. P. Moffa,
TPersonal
communication:
N.
Y. Testing
Oct.
24,
Laboratory,
1972. Feb.
8, 1973.
Volume 34 h’umber 2
Readers’
round
table
225
not be so if the tissue fluid had diffused through the dentinal tubules to the dentin-cement line. The third important area of criticism is that the authors considered the disadvantage of biologic trauma important enough to sacrifice the greater 27 pound retention of the TMS pin for the 14 pound retention of the zinc phosphate-cemented pin. However, when they compared the retention of the various cements, they disregarded the importance of chemical injury to the pulp by zinc phosphate cement and the pulp healing (biologic acceptability) of the cyanoacrylates. A fourth shortcoming of this test is the failure to recognize the findings of Moffa and associates’ that a cavity lining should be used with all pins to minimize leakage and prevent pulp injury from zinc phosphate cement. Moffa and associates showed that the cavity lining reduced the retention of cemented pins by 47 per cent. Since cyanoacrylate produces its own cavity lining and is nonirritating to the pulp, Bhaskar and co-workers3 stated that isobutyl cyanoacrylate needs no liner since it permits the pulp to repair itself. Carpenter and Bunge4 reported that two homologues of ethyl cyanoacrylate were not histotoxic to skin wounds. Assuming that the retention figures are accurate, correcting them for the use of a cavity liner will produce the following: TMS pin cemented with zinc phosphate, 14 pounds x 47 per cent = 7.4 pounds; TMS pin cemented with polycarboxylate, 8 pounds x 47 per cent = 4.2 pounds: and TMS pin cemented with cyanoacrylate remains at 6.7 pounds. A fifth shortcoming of all pin experiments is that they measure only tensile strength. The greater forces are compressive and lateral. This might explain the frequent failure of the self-threading pin. When compression is added to the strain produced by noncemented pins, the dentin fractures, causing pulpal injury.5 In summary, if a cavity lining is used, there is no difference in retention among pins or among cements. There may also be no retentive advantage for a self-threading pin over a cyanoacrylate-cemented pin if the N. Y. Testing Laboratory figures are more significant than the wax-immersion figures. With all the retention figures neutralized, the clinical advantages of the cyanoacrylate cemented pin are: (1) accidental exposures may repair, (2) no special instruments are needed as pins are easily inserted with a plier, and (3) the cyanoacrylate cement needs no mixing and cleanup. This may explain why two million Ellman pins have been successfully cemented with cyanoacrylate in three years. Four dentists have submitted letters testifying to the efficacy of the cyanoacrylate cement.* It is amazing how often tests like this, on extracted teeth, are accepted as dogma by intelligent researchers, who then close their minds to the clinical findings of thousands of dentists testing millions of pins over a period of three years. In the best interests of the practicing dentist and his patient, THE JOURNAL OF PROSTHETIC DENTISTRY should allow a prominent place for this letter in as early an edition as possible. This will enable the reader to better evaluate the clinical advantages of the cyanoacrylate-pin technique. IRVING A. ELLMAN, D.D.S. 558 WILLOW AVE. CEDARHURST, N.Y. 11516
*Personal communications: M. Sniderman, R. S. Krug, Aug. 21, 1974; and L. Baum, Aug.
Sept. 24, 20, 1974.
1974;
G. D. Kudler,
Aug.
22,
1974;
References 1. Perez,
E.,
Schoeneck, G., and Yanahara, H.: The Adaptation of Noncemented Pins, J. 26: 631-639, 1971. Moffa, J. P., Razzano, M. R., and Folio, J.: Influence of Cavity Varnish on Microleakage and Retention of Various Pin-Retaining Devices, J. PROSTHET. DENT. 20: 541-551, 1968. Bhaskar, S. N., Beasley, J. D., Ward, J. I’., and Cutright, D. E.: Human Pulp Capping With Isobutyl Cyanoacrylate, J. Dent. Res. 51: 58-61, 1972.
PROSTHET. DENT.
2. 3.
226 4. 5.
To
Readers’
round
table
,J. Prosthrt. Auwt,
Dent. 1975
Carpenter, W. M., and Bunge, J.: Tissue Response of Skin Wounds to Ethyl and Isobutyl Cyanoacrylate, Int. Assoc. Dent. Res. Abst. No. 657, May, 1974. Trabert, K. C., Caputo, A. A., Collard, E. W., and Standlee, J. P.: Stress Transfer to the Dental Pulp by Retentive Pins, J. PROSTHET. DENT. 30: 808-815, 1973.
THE EDITOR: Dr. Ellman, being the creator of the cyanoacrylate cemented-pin system, has failed to recognize any research other than his own. As yet, there have been no definitive clinical studies that complement and document laboratory studies. Therefore, at present, we must rely on the latter. For the most part, he considers this report inaccurate and misleading since it casts doubt on the cyanoacrylate system. For the benefit of the practicing dentist, we wish to place Dr. Ellman’s comments in the proper perspective with the following: ( 1) Our investigation was initiated and executed with complete objectivity and with no preconceived ideas concerning the outcome. It was our conviction to test various pin-cement combinations, thereby eliciting the optimum combination for retention. The practicing dentist may then have more guidance to follow in choice of a cemented-pin system. (2) The photograph in Fig. 1 was presented as being illustrative of the various pins employed in the study, and mention was neither made nor implied predicting their retentive capacities. In fact, the results did not indicate any correlation between coarseness and retention. The relative coarseness of threaded pins bears little relation to microleakage when employed in the cemented mode. Self-threading pins exhibit less adaptation to the channel wall than does a pin possessing a cement plug. It must be pointed out that reference No. 1 in Dr. Ellman’s letter does not relate to cemented pins. (3) Appropriate measuring procedures were followed to assure the accuracy of the retention values as reported. However, it should be noted that even rounding these values to tenths of a pound does not alter any of the results or conclusions. (4) Dr. Ellman carefully selected three vaIues of the 21 presented in Table II to prove a point. His attention should have been on all the figures, since this would have lead him to the conclusions presented in Table III. (5) Dr. Ellman, when carefully reading our report, will find that pins were not cemented into channels filled with moisture or debris. Cements were set for a minimum of 10 minutes in a dry environment before application of high-fusing inlay wax at the cement-tooth interface. Storage of specimens in physiologic saline for seven days preserved natural tooth hydration. This is a simulation of intraoral conditions where there is moisture present in the tooth. This moisture is maintained by the pulp and external tooth environment as was demonstrated by Wainwright and co-authors1 and Linden.21 s (6) Beech,4 using closely approximately flat surfaces with resultant small film thicknesses, showed that ethyl 2-cyanoacrylate manifested a high retention potential. Five minutes after cementation, the adherends were immersed in water and stored for varying periods of time up to seven days. However, with cemented pins, there exists a fairly large and variable film thickness between the pin and dentin wall. As a result, reduced retention is manifested. A recent article by the authors5 corroborates this line of reasoning. This article was concerned with the cementation of Whaledent Para-posts, employing minimal film thickness. The specimens used in this study, incidentally, utilized an inlay wax covering and were stored in physiologic saline for periods of up to 40 days. The results indicated no significant difference in retention among zinc phosphate, polycarboxylate, and cyanoacrylate cements. (7) Dr. Ellman states that cyanoacrylate has a potential pulp-healing effect. At present, there is only one actual in vivo human-pulp study demonstrating repair of an injured pulp. That was completed by Bhaskar and associates6 utilizing the isobutyl cyanoacrylate homologue (not ethyl 2-cyanoacrylate). The work of Carpenter and Bunger on rats, with ethyl 2-cyanoacrylate and isobutyl cyanoacrylate homologues, demonstrated no histotoxic reaction to either. Importantly though, this work did not involve a study of pulpal responses. (8) Copal resin varnishes, in most instances, should be applied to cut dentin in vital teeth
