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In vitro assessment of microleakage of pit and fissure sealants
Operative dentistry
In vitro assessment and fissure sealants
of microleakage
of pit
Jerome J. Rudolph, D.D.S., M&D.,* Ralph W. Phillips, D.Sc.,** and Marjorie 1. Swartz, M.S.*** Indiana University School of Dentistry, Indianapolis, Ind.
T
In an effort to reduce the vulnerability of the occlusal surfaces of posterior teeth to caries, a variety of materials and techniques have been employed to treat the pits and fissures. The most recent procedure is the application of resins of low viscosity which flow readily over the surface and, hopefully, into the pits and fissures, thereby sealing them against the penetration of deleterious agents. Several resin pit and fissure sealants are commercially available,l and in addition, a number of experimental formulations have been subjected to clinical trials.2-” The basic systems which have been tested include the BIS-GMA resin polyurethane, cyanoacrylates. and polycarboxylate cement. Certain problems were encountered with some of these materials, but in general, the results of clinical trials conducted with the BIS-GMA formulations are encouraging. The success of the pit and fissure sealants depends upon the efficacy of the resin to seal these vulnerable areas and to maintain the seal for a prolonged period. If complete sealing is not obtained or the seal is lost, even over a small area, the potential for the seaIant to act as an anticariogenic agent is jeopardized. The continuing leakage could conceivably even increase the potential for caries. It was the purpose of this study to examine, in vitro, the sealing ability of two commercially available pit and fissure sealants as well as an experimental material that had been previously used in clinical trials. This DE00433.
research
Portions of the M.S.D. *Presently **Assistant ***Professor
62
was
supported
of this report were degree. at Naval Graduate Dean
in part taken
and Research
of Dental
Materials.
Dental
by United
from
a thesis
School,
Professor
States
by the senior
Bethesda,
of Dental
Public
Md.
Materials.
Health author
Service in partial
Grant fulfillment
No.
Microleakage METHODS
of
pit and
fissure sealants
63
AND MATERIALS
The two commercial sealants employed in the study were Nuva-Seal* and Epoxylite 9075,t both based upon the BIS-GMA resin system. The experimental material1 was also a BIS-GMA resin. The materials were manipulated in accordance with the directions of the respective manufacturers. Pretreatment or conditioning of the tooth surface by acid etching was recommended for all materials, and the etching solutions were supplied with each of the sealants. All of the pretreatment solutions were phosphoric acid, although the acid concentrations varied. A silane primer was also supplied with the Epoxylite 9075 sealant. Sound human molars that had been stored in tap water immediately after extraction were used. Just prior to sealing the pits and fissures, the teeth were cleaned by means of a rubber cup and rotary handpiece with a slurry of flour of pumice. The occlusal surfaces were treated with the acid etchant for one minute, then rinsed with water and dried with clean compressed air. The Nuva-Seal and experimental sealants were then applied to the acid-treated surfaces. For Epoxylite 9075, a coat of primer was applied to the etched surface prior to placement of the sealant. After polymerization of the sealants, the teeth were immersed in water and stored at room temperature until tested. Sixty teeth were sealed with each system. Thirty were tested seven days after application of the sealant, and the remaining 30 were tested after three months. At each time period, 15 of the 30 teeth were subjected to a total of 2,500 temperature cycles over a five-day period (500 cycles per day) prior to assessment of leakage. Temperature cycling was accomplished by means of a device consisting of a wire basket by which the teeth were automatically transferred between two water baths, 15’ and 45’ C., at specified time intervals.“’ Thus the temperature differential between the baths was 30° C., and the dwell time in each bath was 30 seconds. Sealing ability was measured on the basis of the ability of the sealants to preclude the passage of 4”Ca. Leakage was revealed by autoradiographs made from tooth sections prepared through areas restored by pit and fissure sealants. The isotope technique has been described in previous publications.“, *:! Briefly, it consisted of sealing the root and crown areas of the teeth, except for the occlusal surfaces, by applying in successive layers fingernail polish, tinfoil, and fingernail polish. After the nail lacquer dried, the specimens were again returned to the water-storage medium for a minimum of one hour. The surfaces were then carefully blotted dry, and the teeth were immersed in an aqueous solution of *%a (Cl) Z (0.1 mci/ml., pH 5.5) for two hours. Upon removal, the teeth vvere rinsed in running water for one hour and the surfaces scrubbed with detergent and water. Each tooth was then sectioned into three parts by means of a Gillings-IIamco$ sectioning machine, the cuts being made through the pit and fissure areas. During *The
L. D. Caulk
Company,
*Lee Pharmaceuticals, $S. S. White Company, #Hamco
Machines,
Inc.,
Division of Dentsply
El Monte, Division Rochester.
Calif. of Pennwalt N. Y.
Corp.,
International, Philadelphia,
Milford, Pa.
Del.
64
Rudolph,
Fig. 1. Standard slight leakage:
Table
Phillips,
for
right.
I. Number
and Swartz
ranking sealed severe lrakape.
of teeth
with 1
Water stored 7 days Material
-0*
Nuva-Seal Epoxylite 9075 Experimental *No
/
St
/ u
teeth
with
respect
corresponding
degree
Thermal cycled 2500x--7 days water storage 0
/
s
/
left.
to leakage:
of leakage
i
Thermal cycled 2500x--3 r?L,,. water storage
Water stored 3 mo.
L
0
centc’r,
no lwkage:
/
s
/
L
o/s
L
14
0
1
1:i
0
II
14
1
0
14
0
1
11
1
0
13
0
0
1?
0
0
15
;I
0
15
0
0
15
II
0
1.5
0
0
1.5
(1
II
leakage.
tsuperficial
leakage.
SSignificant
leakage.
sectioning, copious amounts of water were directed onto the diamond rutting wheel in order to maintain it as free of radioactive debris as possible. Also, the blade was cleaned at frequent intervals by scrubbing with detergent and water. The pulp was removed from the tooth sections, and the surfaces were scrubbed with a detergent solution to avoid any possible contamination from the cutting wheel. The autoradiographs were prepared by placin g the sections on ultraspeed dental x-ray film for 17 hours. The films were developed by the usual procedures and examined for evidence of penetration of the isotope between the sealant and the orclusal surfare of the tooth. RESULTS The criteria used for evaluating the autoradiographs with respect to the degree of leakage are presented in Fig. 1, and the data are shown in Table I. Generally, all of the materials were effective in sealing the occlusal pits and fissures against the ingress of the -‘Wa , even when the specimens were subjected to thermal cycling. There were four instances of leakage among the 60 Nuva-Seal specimens, one instance was noted with Epoxylite 9075, and no leakage was detected among the teeth sealed with the experimental sealant. No explanation is offered for these somewhat isolated instances of leakage. It is possible that some deterioration or change in the viscosity of the resin resulted from exposure to the atmosphere.
Volume Number
32 1
Microleakage
01 pit and
fissure sealants
65
DISCUSSION
The results obtained in this study are similar to those obtained in a similar study by Woody, Moffa, and McCune.l” They also reported that the RIS-GMA materials effectively sealed occlusal pits and fissures. It must be recognized that application of the sealants in vivo is more difficult than application for in vitro tests on extracted teeth and that achieving an adequate seal clinically is unquestionably most difficult to attain. In addition, the tests here were of short duration, and the teeth were not subjected to mechanical stress or occlusal wear. However, the data do suggest that these materials possess an inherent potential to effectively seal occlusal pits and fissures. CONCLUSIONS
The sealing ability of two commercial and one experimental pit and fissure sealant on extracted teeth was evaluated in vitro by means of a radioisotope technique. The sealants exhibited little or no leakage following three months of storage in water, even when the teeth were subjected to thermal cycling. References 1. 2.
3. 4. 5.
6. 7. 8. 9. 10. 11. 12. 13.
Council on Dental Materials and Devices and Council on Dental Therapeutics: Pit and Fissure Sealants, J. Am. Dent. Assoc. 87: 1101-l 103, 1973. Buonocore, M. G.: Caries Prevention in Pits and Fissures Sealed With an Adhesive Resin Polymerized by Ultraviolet Light: A Two-Year Study of a Single Adhesive Application, J. Am. Dent. Assoc. 82: 1090-1093, 1971. Ripa, L. W., and Cole, W. W.: Occlusal Sealing and Caries Prevention; Results 12 Months After a Single Application of Adhesive Resins, J. Dent. Res. 49: 171-173, 1970. Rock, W. P.: Fissure Sealants: Results Obtained With Two Different Sealants After One Year, Br. Dent. J. 133: 146-151, 1973. Takeuchi, M., Kizo, T., Shimizu, T., Eto, M., and Amano, F.: Sealing of the Pit and Fissure With Resin Adhesive. II. Results of Nine Months Field Work, Bull. Tokyo Dent. Coil. 7: 60-71, 1966. McCune, R. J., Horowitz, S. B., and Cvar, J.: Pit and Fissure Sealants: One-Year Results From a Study in Kalispell, Montana, J. Am. Dent. Assoc. 87: 1177-1180, 1973. Parkhouse, R. C., and Winter, G. B.: A Fissure Sealant Containing Methyl-2-cyanoacrylate as a Caries Preventive Agent, Br. Dent. J. 130: 16-19, 1971. Roydhouse, R. H.: Prevention of Occlusal Fissure Caries by Use of a Sealant: A Pilot Study, J. Dent. Child. 35: 253-262, 1968. McCune, R. J.: Future Trends in Dental Materials, Contact Point 49: 38-40, 1970. Guzman, H. J., Swartz, M. L., and Phillips, R. W.: Marginal Leakage of Dental Restorations Subjected to Thermal Stress, J. PROSTHET. DENT. 21: 166-175, 1969. Swartz, M. L., and Phillips, R. W.: In Vitro Studies on the Marginal Leakage of Restorative Materials, J. Am. Dent. Assoc. 62: 141-151, 1961. Phillips, R. W., Gilmore, H. W., Swartz, M. L., and Schenker, S. J.: Adaptation of Restorations in Vivo as Assessed by Ca”s, J. Am. Dent. Assoc. 62: 9-20, 1960. Woody, R. D., Moffa, J. P., and McCune, R. J.: Assessment of Leakage of Four Pit and Fissure by Ca’z, Int. Assoc. Dent. Res. Abst. No. 717, 1972. DR.
RUDOLPH
NAVAL GRAIXJATE BETHESDA, MD.
DR. DENTAL
20014
SCHOOL
PHILLIPS
INDIANA
AND
MISS
UNIVERSITY SCHOOL OF DENTISTRY INDIANAPOLIS, IND. 46202
SWARTZ
In vitro assessment and fissure sealants
of microleakage
of pit
Jerome J. Rudolph, D.D.S., M&D.,* Ralph W. Phillips, D.Sc.,** and Marjorie 1. Swartz, M.S.*** Indiana University School of Dentistry, Indianapolis, Ind.
T
In an effort to reduce the vulnerability of the occlusal surfaces of posterior teeth to caries, a variety of materials and techniques have been employed to treat the pits and fissures. The most recent procedure is the application of resins of low viscosity which flow readily over the surface and, hopefully, into the pits and fissures, thereby sealing them against the penetration of deleterious agents. Several resin pit and fissure sealants are commercially available,l and in addition, a number of experimental formulations have been subjected to clinical trials.2-” The basic systems which have been tested include the BIS-GMA resin polyurethane, cyanoacrylates. and polycarboxylate cement. Certain problems were encountered with some of these materials, but in general, the results of clinical trials conducted with the BIS-GMA formulations are encouraging. The success of the pit and fissure sealants depends upon the efficacy of the resin to seal these vulnerable areas and to maintain the seal for a prolonged period. If complete sealing is not obtained or the seal is lost, even over a small area, the potential for the seaIant to act as an anticariogenic agent is jeopardized. The continuing leakage could conceivably even increase the potential for caries. It was the purpose of this study to examine, in vitro, the sealing ability of two commercially available pit and fissure sealants as well as an experimental material that had been previously used in clinical trials. This DE00433.
research
Portions of the M.S.D. *Presently **Assistant ***Professor
62
was
supported
of this report were degree. at Naval Graduate Dean
in part taken
and Research
of Dental
Materials.
Dental
by United
from
a thesis
School,
Professor
States
by the senior
Bethesda,
of Dental
Public
Md.
Materials.
Health author
Service in partial
Grant fulfillment
No.
Microleakage METHODS
of
pit and
fissure sealants
63
AND MATERIALS
The two commercial sealants employed in the study were Nuva-Seal* and Epoxylite 9075,t both based upon the BIS-GMA resin system. The experimental material1 was also a BIS-GMA resin. The materials were manipulated in accordance with the directions of the respective manufacturers. Pretreatment or conditioning of the tooth surface by acid etching was recommended for all materials, and the etching solutions were supplied with each of the sealants. All of the pretreatment solutions were phosphoric acid, although the acid concentrations varied. A silane primer was also supplied with the Epoxylite 9075 sealant. Sound human molars that had been stored in tap water immediately after extraction were used. Just prior to sealing the pits and fissures, the teeth were cleaned by means of a rubber cup and rotary handpiece with a slurry of flour of pumice. The occlusal surfaces were treated with the acid etchant for one minute, then rinsed with water and dried with clean compressed air. The Nuva-Seal and experimental sealants were then applied to the acid-treated surfaces. For Epoxylite 9075, a coat of primer was applied to the etched surface prior to placement of the sealant. After polymerization of the sealants, the teeth were immersed in water and stored at room temperature until tested. Sixty teeth were sealed with each system. Thirty were tested seven days after application of the sealant, and the remaining 30 were tested after three months. At each time period, 15 of the 30 teeth were subjected to a total of 2,500 temperature cycles over a five-day period (500 cycles per day) prior to assessment of leakage. Temperature cycling was accomplished by means of a device consisting of a wire basket by which the teeth were automatically transferred between two water baths, 15’ and 45’ C., at specified time intervals.“’ Thus the temperature differential between the baths was 30° C., and the dwell time in each bath was 30 seconds. Sealing ability was measured on the basis of the ability of the sealants to preclude the passage of 4”Ca. Leakage was revealed by autoradiographs made from tooth sections prepared through areas restored by pit and fissure sealants. The isotope technique has been described in previous publications.“, *:! Briefly, it consisted of sealing the root and crown areas of the teeth, except for the occlusal surfaces, by applying in successive layers fingernail polish, tinfoil, and fingernail polish. After the nail lacquer dried, the specimens were again returned to the water-storage medium for a minimum of one hour. The surfaces were then carefully blotted dry, and the teeth were immersed in an aqueous solution of *%a (Cl) Z (0.1 mci/ml., pH 5.5) for two hours. Upon removal, the teeth vvere rinsed in running water for one hour and the surfaces scrubbed with detergent and water. Each tooth was then sectioned into three parts by means of a Gillings-IIamco$ sectioning machine, the cuts being made through the pit and fissure areas. During *The
L. D. Caulk
Company,
*Lee Pharmaceuticals, $S. S. White Company, #Hamco
Machines,
Inc.,
Division of Dentsply
El Monte, Division Rochester.
Calif. of Pennwalt N. Y.
Corp.,
International, Philadelphia,
Milford, Pa.
Del.
64
Rudolph,
Fig. 1. Standard slight leakage:
Table
Phillips,
for
right.
I. Number
and Swartz
ranking sealed severe lrakape.
of teeth
with 1
Water stored 7 days Material
-0*
Nuva-Seal Epoxylite 9075 Experimental *No
/
St
/ u
teeth
with
respect
corresponding
degree
Thermal cycled 2500x--7 days water storage 0
/
s
/
left.
to leakage:
of leakage
i
Thermal cycled 2500x--3 r?L,,. water storage
Water stored 3 mo.
L
0
centc’r,
no lwkage:
/
s
/
L
o/s
L
14
0
1
1:i
0
II
14
1
0
14
0
1
11
1
0
13
0
0
1?
0
0
15
;I
0
15
0
0
15
II
0
1.5
0
0
1.5
(1
II
leakage.
tsuperficial
leakage.
SSignificant
leakage.
sectioning, copious amounts of water were directed onto the diamond rutting wheel in order to maintain it as free of radioactive debris as possible. Also, the blade was cleaned at frequent intervals by scrubbing with detergent and water. The pulp was removed from the tooth sections, and the surfaces were scrubbed with a detergent solution to avoid any possible contamination from the cutting wheel. The autoradiographs were prepared by placin g the sections on ultraspeed dental x-ray film for 17 hours. The films were developed by the usual procedures and examined for evidence of penetration of the isotope between the sealant and the orclusal surfare of the tooth. RESULTS The criteria used for evaluating the autoradiographs with respect to the degree of leakage are presented in Fig. 1, and the data are shown in Table I. Generally, all of the materials were effective in sealing the occlusal pits and fissures against the ingress of the -‘Wa , even when the specimens were subjected to thermal cycling. There were four instances of leakage among the 60 Nuva-Seal specimens, one instance was noted with Epoxylite 9075, and no leakage was detected among the teeth sealed with the experimental sealant. No explanation is offered for these somewhat isolated instances of leakage. It is possible that some deterioration or change in the viscosity of the resin resulted from exposure to the atmosphere.
Volume Number
32 1
Microleakage
01 pit and
fissure sealants
65
DISCUSSION
The results obtained in this study are similar to those obtained in a similar study by Woody, Moffa, and McCune.l” They also reported that the RIS-GMA materials effectively sealed occlusal pits and fissures. It must be recognized that application of the sealants in vivo is more difficult than application for in vitro tests on extracted teeth and that achieving an adequate seal clinically is unquestionably most difficult to attain. In addition, the tests here were of short duration, and the teeth were not subjected to mechanical stress or occlusal wear. However, the data do suggest that these materials possess an inherent potential to effectively seal occlusal pits and fissures. CONCLUSIONS
The sealing ability of two commercial and one experimental pit and fissure sealant on extracted teeth was evaluated in vitro by means of a radioisotope technique. The sealants exhibited little or no leakage following three months of storage in water, even when the teeth were subjected to thermal cycling. References 1. 2.
3. 4. 5.
6. 7. 8. 9. 10. 11. 12. 13.
Council on Dental Materials and Devices and Council on Dental Therapeutics: Pit and Fissure Sealants, J. Am. Dent. Assoc. 87: 1101-l 103, 1973. Buonocore, M. G.: Caries Prevention in Pits and Fissures Sealed With an Adhesive Resin Polymerized by Ultraviolet Light: A Two-Year Study of a Single Adhesive Application, J. Am. Dent. Assoc. 82: 1090-1093, 1971. Ripa, L. W., and Cole, W. W.: Occlusal Sealing and Caries Prevention; Results 12 Months After a Single Application of Adhesive Resins, J. Dent. Res. 49: 171-173, 1970. Rock, W. P.: Fissure Sealants: Results Obtained With Two Different Sealants After One Year, Br. Dent. J. 133: 146-151, 1973. Takeuchi, M., Kizo, T., Shimizu, T., Eto, M., and Amano, F.: Sealing of the Pit and Fissure With Resin Adhesive. II. Results of Nine Months Field Work, Bull. Tokyo Dent. Coil. 7: 60-71, 1966. McCune, R. J., Horowitz, S. B., and Cvar, J.: Pit and Fissure Sealants: One-Year Results From a Study in Kalispell, Montana, J. Am. Dent. Assoc. 87: 1177-1180, 1973. Parkhouse, R. C., and Winter, G. B.: A Fissure Sealant Containing Methyl-2-cyanoacrylate as a Caries Preventive Agent, Br. Dent. J. 130: 16-19, 1971. Roydhouse, R. H.: Prevention of Occlusal Fissure Caries by Use of a Sealant: A Pilot Study, J. Dent. Child. 35: 253-262, 1968. McCune, R. J.: Future Trends in Dental Materials, Contact Point 49: 38-40, 1970. Guzman, H. J., Swartz, M. L., and Phillips, R. W.: Marginal Leakage of Dental Restorations Subjected to Thermal Stress, J. PROSTHET. DENT. 21: 166-175, 1969. Swartz, M. L., and Phillips, R. W.: In Vitro Studies on the Marginal Leakage of Restorative Materials, J. Am. Dent. Assoc. 62: 141-151, 1961. Phillips, R. W., Gilmore, H. W., Swartz, M. L., and Schenker, S. J.: Adaptation of Restorations in Vivo as Assessed by Ca”s, J. Am. Dent. Assoc. 62: 9-20, 1960. Woody, R. D., Moffa, J. P., and McCune, R. J.: Assessment of Leakage of Four Pit and Fissure by Ca’z, Int. Assoc. Dent. Res. Abst. No. 717, 1972. DR.
RUDOLPH
NAVAL GRAIXJATE BETHESDA, MD.
DR. DENTAL
20014
SCHOOL
PHILLIPS
INDIANA
AND
MISS
UNIVERSITY SCHOOL OF DENTISTRY INDIANAPOLIS, IND. 46202
SWARTZ