Journal of Oral Rehabilitation, 1976, Volume 3, pages 311-313
Short communication The long term bonding of a polymeric fissm-e sealant to stannous fluoride treated enamel
T. LOW, J. A. VON F R A U N H O F E R and G. B. WINTER Institute of Dental Surgery, University of London
Summary A report is presented of extended studies of tensile bond strength of Nuva Seal to fluoride-treated enamel 1 week, 3 months and 9 months after application. The differences in strength were not statistically significant. The use of stannous fluoride as the topical agent did not lead to any marked evidence of enamel staining. Bonding studies It has previously been shown that the in vitro tensile bond strength of Nuva Seal (L. D. Caulk Co., Miiford, Delaware) to enamel is significantly increased when the etched enamel is treated with 8% freshly prepared stannous fluoride prior to the application ofthe fissure sealant (Low, von Fraunhofer & Winter, 1975). Study of the mechanism of the increased bond strength indicates the possibility of a chemical bond between Nuva Seal and the reaction products of stannous fluoride and the enamel surface (Low & von Fraunhofer, 1975). Although earlier studies on the bond strength of Nuva Seal to enamel have all shown an increase in tensile bond strength following water storage for periods of up to 6 months (Williams, von Fraunhofer & Winter, 1974), the stability of the bond strength to stannous fluoride treated enamel after prolonged contact with moisture is unknown. This short communication reports on the extended studies of the tensile bond strength of Nuva Seal to fluoridetreated enamel after 3 and 9 months in water. The test specimens and testing procedures have been reported previously (Low et al, 1975). Forty specimens were prepared, twenty being tested after immersion in distilled water at 3-7 ± TC for 3 months, and twenty after 9 months' immersion. The tensile bond strength of Nuva Seal to stannous fluoride treated enamel is shown in Table 1. The differences in the tensile bond strength at 1 week, 3 months and 9 months were statistically not significant (P>0-05). It is generally accepted that stannous fluoride tends to stain the enamel with a brownish colour. In this study, the enamel surfaces of all forty specimens were carefully examined for evidence of staining after they were tested in tension. It was found that only five of the total of forty experimental teeth showed any evidence of staining. In Correspondence: Dr J. A. von Fraunhofer, Institute of Dental Surgery, Eastman Dental Hospital, Gray's Inn Road, London WCIX 8LD, England.
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Table 1. Tensile bond strength of Nuva Seal and stannous fluoride-treated enamel Time 1 week 3 months 9 months
Tensile bond strength (±s.d.) (kg cm"^) 55-7±17-l 59-8±22-5 60-6±21-3
these five cases, the staining was minimal and required careful inspection after the teeth were dried before being detectable. The in vitro evidence suggests that staining is not a major problem in the use of stannous fluoride as a topical fluoridation agent prior to fissure sealing. None of the clinical studies on fissure sealants reported to date have recorded a 100 % sealant retention rate for periods of up to 2 years. In a clinical study where Nuva Seal was applied under normal school dental service conditions, only 39 % of the treated teeth were still fully sealed after a period of 6 months (Burt et al, 1975). To ensure maximum effectiveness of fissure sealing as a dental health measure, teeth which have lost their sealant coating must be retreated at the next follow-up visit. This would usually be at the following 6 monthly recall visit as it is not possible for the patient to detect loss of the fissure sealant. It is possible that the treated pits and fissures could become carious during the period between loss of sealant and the recall visit. It also may not be possible always to see the child regularly at 6 monthly intervals subsequent to the application of the fissure sealant. Murray, Winter & Hurst (1975), in a clinical trial of 5-year-old children with a fluoride varnish reported a 58 % loss of children from the trial after 1 year and emphasized the problem of the high wastage rate of children when employing a caries preventive agent that required 6 monthly application. An alternative method of protection that does not require such active patient co-operation is therefore highly desirable. It has been shown that a caries reduction of about 51 % can be obtained over a 2-year period with the temporary sealing of occlusal pits and fissures after topical fluoride application (Pugnier, 1972). The combined application of stannous fluoride and Nuva Seal appears to be the basis of a clinical caries preventive procedure which might overcome the problems of uncontrollable loss of the fissure sealant. A clinical study to investigate the effectiveness of such an approach will be initiated shortly. In a recent symposium on the acid-etch technique (British Dental Journal, 1975), the need to develop materials and techniques to improve the adhesion of resin to enamel was stressed. The use of stannous fluoride in combination with Nuva Seal appears to be such a development. The use of the application protocol described in this study and previously (Low et al, 1975) might require modification for routine clinical use. Adequate isolation of the treated teeth from moisture and saliva during the application of Nuva Seal is a critical factor for good retention. Numerous studies in the past have indicated the problem of obtaining adequate isolation, especially in the molar regions, resulting in a high rate of sealant loss (Rock, 1973; Williams, Casson & Winter, 1974; Burt et al, 1975). Extending the period of isolation by a further 4 min to permit the application of stannous fluoride complicates the procedure. Further in vitro studies on the suitability of a shorter fluoride application procedure are definitely indicated.
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References Acid-etch technique—an international symposium (1975) British Dental Journal, 138, 261. BURT, B.A., BERMAN, D.S., GELBIER, S. & SILVERSTONE, L.M. (1975) Retention of a fissure sealant six months after application. British Dental Journal, 138, 98. Low, T., VON FRAUNHOFER, J.A. & WINTER, G.B. (1975) The bonding of a polymeric fissure sealant to topical fluoride treated teeth. Journal of Oral Rehabilitation 2, 303. Low, T. & VON FRAtrNHOFER, J.A. (1976) In preparation. MURRAY, J.J., WINTER, G.B. & HURST, C-P- (1975) A feasibility study into the effectiveness of a fluoride varnish. Journal of Dental Research, 54, IADR abst. no. L 147. PUGNIER, V.A. (1972) Cyanoacrylate resins in caries prevention: a two year study. Journal of the American Dental Association, 84, 829. ROCK, W.P. (1973) Fissure sealants—results obtained with two different bis-GMA type sealants after one year. British Dental Journal, 134, 193. WILLIAMS, B., CASSON, M.H. & WINTER, G.B. (1974) A clinical study using a new ultra-violet polymerized fissure sealant. Journal of Dentistry, 2, 101. WILLIAMS, B., VON FRAUNHOFER, J.A. & WINTER, G.B. (1974) Tensile bond strength between fissure sealants and enamel. Journal of Dental Research, 53, 23.
Manuscript accepted 10 July 1975
Short communication The long term bonding of a polymeric fissm-e sealant to stannous fluoride treated enamel
T. LOW, J. A. VON F R A U N H O F E R and G. B. WINTER Institute of Dental Surgery, University of London
Summary A report is presented of extended studies of tensile bond strength of Nuva Seal to fluoride-treated enamel 1 week, 3 months and 9 months after application. The differences in strength were not statistically significant. The use of stannous fluoride as the topical agent did not lead to any marked evidence of enamel staining. Bonding studies It has previously been shown that the in vitro tensile bond strength of Nuva Seal (L. D. Caulk Co., Miiford, Delaware) to enamel is significantly increased when the etched enamel is treated with 8% freshly prepared stannous fluoride prior to the application ofthe fissure sealant (Low, von Fraunhofer & Winter, 1975). Study of the mechanism of the increased bond strength indicates the possibility of a chemical bond between Nuva Seal and the reaction products of stannous fluoride and the enamel surface (Low & von Fraunhofer, 1975). Although earlier studies on the bond strength of Nuva Seal to enamel have all shown an increase in tensile bond strength following water storage for periods of up to 6 months (Williams, von Fraunhofer & Winter, 1974), the stability of the bond strength to stannous fluoride treated enamel after prolonged contact with moisture is unknown. This short communication reports on the extended studies of the tensile bond strength of Nuva Seal to fluoridetreated enamel after 3 and 9 months in water. The test specimens and testing procedures have been reported previously (Low et al, 1975). Forty specimens were prepared, twenty being tested after immersion in distilled water at 3-7 ± TC for 3 months, and twenty after 9 months' immersion. The tensile bond strength of Nuva Seal to stannous fluoride treated enamel is shown in Table 1. The differences in the tensile bond strength at 1 week, 3 months and 9 months were statistically not significant (P>0-05). It is generally accepted that stannous fluoride tends to stain the enamel with a brownish colour. In this study, the enamel surfaces of all forty specimens were carefully examined for evidence of staining after they were tested in tension. It was found that only five of the total of forty experimental teeth showed any evidence of staining. In Correspondence: Dr J. A. von Fraunhofer, Institute of Dental Surgery, Eastman Dental Hospital, Gray's Inn Road, London WCIX 8LD, England.
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Short communication
Table 1. Tensile bond strength of Nuva Seal and stannous fluoride-treated enamel Time 1 week 3 months 9 months
Tensile bond strength (±s.d.) (kg cm"^) 55-7±17-l 59-8±22-5 60-6±21-3
these five cases, the staining was minimal and required careful inspection after the teeth were dried before being detectable. The in vitro evidence suggests that staining is not a major problem in the use of stannous fluoride as a topical fluoridation agent prior to fissure sealing. None of the clinical studies on fissure sealants reported to date have recorded a 100 % sealant retention rate for periods of up to 2 years. In a clinical study where Nuva Seal was applied under normal school dental service conditions, only 39 % of the treated teeth were still fully sealed after a period of 6 months (Burt et al, 1975). To ensure maximum effectiveness of fissure sealing as a dental health measure, teeth which have lost their sealant coating must be retreated at the next follow-up visit. This would usually be at the following 6 monthly recall visit as it is not possible for the patient to detect loss of the fissure sealant. It is possible that the treated pits and fissures could become carious during the period between loss of sealant and the recall visit. It also may not be possible always to see the child regularly at 6 monthly intervals subsequent to the application of the fissure sealant. Murray, Winter & Hurst (1975), in a clinical trial of 5-year-old children with a fluoride varnish reported a 58 % loss of children from the trial after 1 year and emphasized the problem of the high wastage rate of children when employing a caries preventive agent that required 6 monthly application. An alternative method of protection that does not require such active patient co-operation is therefore highly desirable. It has been shown that a caries reduction of about 51 % can be obtained over a 2-year period with the temporary sealing of occlusal pits and fissures after topical fluoride application (Pugnier, 1972). The combined application of stannous fluoride and Nuva Seal appears to be the basis of a clinical caries preventive procedure which might overcome the problems of uncontrollable loss of the fissure sealant. A clinical study to investigate the effectiveness of such an approach will be initiated shortly. In a recent symposium on the acid-etch technique (British Dental Journal, 1975), the need to develop materials and techniques to improve the adhesion of resin to enamel was stressed. The use of stannous fluoride in combination with Nuva Seal appears to be such a development. The use of the application protocol described in this study and previously (Low et al, 1975) might require modification for routine clinical use. Adequate isolation of the treated teeth from moisture and saliva during the application of Nuva Seal is a critical factor for good retention. Numerous studies in the past have indicated the problem of obtaining adequate isolation, especially in the molar regions, resulting in a high rate of sealant loss (Rock, 1973; Williams, Casson & Winter, 1974; Burt et al, 1975). Extending the period of isolation by a further 4 min to permit the application of stannous fluoride complicates the procedure. Further in vitro studies on the suitability of a shorter fluoride application procedure are definitely indicated.
Short communication
313
References Acid-etch technique—an international symposium (1975) British Dental Journal, 138, 261. BURT, B.A., BERMAN, D.S., GELBIER, S. & SILVERSTONE, L.M. (1975) Retention of a fissure sealant six months after application. British Dental Journal, 138, 98. Low, T., VON FRAUNHOFER, J.A. & WINTER, G.B. (1975) The bonding of a polymeric fissure sealant to topical fluoride treated teeth. Journal of Oral Rehabilitation 2, 303. Low, T. & VON FRAtrNHOFER, J.A. (1976) In preparation. MURRAY, J.J., WINTER, G.B. & HURST, C-P- (1975) A feasibility study into the effectiveness of a fluoride varnish. Journal of Dental Research, 54, IADR abst. no. L 147. PUGNIER, V.A. (1972) Cyanoacrylate resins in caries prevention: a two year study. Journal of the American Dental Association, 84, 829. ROCK, W.P. (1973) Fissure sealants—results obtained with two different bis-GMA type sealants after one year. British Dental Journal, 134, 193. WILLIAMS, B., CASSON, M.H. & WINTER, G.B. (1974) A clinical study using a new ultra-violet polymerized fissure sealant. Journal of Dentistry, 2, 101. WILLIAMS, B., VON FRAUNHOFER, J.A. & WINTER, G.B. (1974) Tensile bond strength between fissure sealants and enamel. Journal of Dental Research, 53, 23.
Manuscript accepted 10 July 1975
