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Clinical observations of enamel after acid-etch procedure
T h e incisal halves of m and ibu lar rig ht central incisors in fo u r patients, ranging in ag e from 9 to 67 years, w ere etched w ith a com m ercial etchin g agent to d eterm in e rates at w hich en am el returns to norm al ap p earan ce. T h e tim e fo r co m p lete return to norm al ap p ea ran ce increased with th e patient's age, from ab o u t 96 hours in th e youngest to m ore than tw o w eeks in the oldest. How ever, even in th e o ld er patients, th e enam el had an alm ost norm al tex tu re afte r 4 8 hours.
Clinical observations of enamel after acid-etch procedure
Edward M. Arana, DDS, Carm el, C alif
The use of the acid-etch technique to improve adhesion of restoratives has gained wide accep tance since the time it was first reported by Buonocore.1 This technique has been used to improve marginal adaptations of restoratives, in the re pair of fractured incisal angles,2"7 for coating of erosion on the gingival third of a tooth,8-9 and for bonding of orthodontic brackets to enamel.1012 Some practitioners have been concerned about damage to sound tooth structure that could re sult from the use of acids. Tison,13 in 1970, chal lenged the use of acid etches on the basis of dam age to the surfaces of teeth. This concern may be traced back 25 years to work reported on the décalcification of teeth because of the ingestion of phosphoric and citric acid solutions.1416 Several investigators have found “ remineral ization” after acid etching to be fairly rapid. The term “ remineralization” is used to describe the return to normal appearance; the mechanism of this process has not been dearly identified. Buonocore,1 using 85% phosphoric acid, noted that the enamel surface appeared normal after a few days, except for a faint loss of luster. Sog1102 ■ JADA, Vol. 89, November 1974
nnaes17 reported complete “ remineralization” of the enamel surfaces in monkeys after a citric acid etch. Miiehlmann and co-workers18 found that the characteristic prism-end pattern of etched enamel disappeared in 2 to 48 days. Later, Retief and associates11 observed “ remineraliza tion” one week after treatm ent with 50% phos phoric acid. In an in vivo replication technique Lee and co-workers19 found almost complete “ remineralization” within 72 hours after etching with 50% citric acid. Albert and Grenoble20 found that calcium phosphate was deposited within one hour and that “ remineralization” was com plete after 96 hours in deciduous teeth etched with 50% phosphoric acid. Other workers found that acid etchants caused no detrimental effects. The purpose of this study was to determine and to record photographically over a two-week period the progress of “ remineralization” in vivo in teeth exposed to a two-minute acid etch. Pa tients of various ages were selected from a pri vate practice, and the teeth were etched in the exact manner in which they would have been treated before the application of restoratives.
Materials and methods The mandibular right central incisor was chosen because of accessibility and of photography ease. The four patients in this study were a 9year, 3-month-old boy; a 24-year, 7-month-old woman; a 55-year, 9-month-old man; and a 67year, 2-month-old woman. The rate of “ remineralization” was deter mined by isolating the bottom half of the tooth with black inlay wax, so that only the incisal half was available for etching. In this way, the two halves of the tooth could be compared. The wax was applied hot in the usual manner with a wax spatula. Etching was performed with the etchant avail able in a commercial Restodent* kit, which is a colored gel composition containing 50% phos phoric acid. This etchant was applied for two minutes and then washed off. Immediately after etching, the wax on the lower half of the tooth was removed with a carving instrument, and the tooth was photographed. Other photographs were taken two minutes after etching, and after 2, 6, 12, 24, 48, 96, 215, and 383 hours. Kodachrome II Daylight film with an 81A filter was used; most pictures were taken at F 19. N o in structions were given to the patients after the etch procedure.
Results The progress of “ remineralization” of the inci sor in the 9-year-old boy is shown in Figures 1 through 7, which show, respectively, the tooth immediately after etching, and after 2, 6, 12, 24, 48, and 96 hours. F or the other three patients, two pictures of each tooth are shown; one was taken immediately after etching and the other at a time when “ remineralization” was essentially completed. Figures 8 and 9 are pictures of the tooth of the 24-year-old woman, Figures 10 and 11 of the tooth of the 55-year-old man, and Fig ures 12 and 13 of the tooth of the 67-year-old woman. Inspection of the photographs indicates that, in the 9-year-old boy, the difference in shading of the enamel was very faint after 24 hours and had practically disappeared after 48 hours. A t the 96-hour check, the enamel had returned com pletely to normal appearance. In the 24-year-old woman, a faint differentiation existed after 24 hours; it became very slight 48 hours after etch
ing. A t 96 hours the difference had practically disappeared, and after 215 hours the difference was negligible. “ Remineralization” of the en amel in the 55-year-old man seemed to be well completed after 48 hours; the difference in color ation of the two parts of the tooth was only faint. This difference had become slight after 215 hours and essentially negligible after 383 hours. In the 67-year-old woman, the difference in the enamel after 96 hours was very faint, and essentially no difference was noted after 383 hours. In addition to showing the etched surfaces as they revert to normal appearance, these pictures also provide evidence for the absence of plaque formation on the treated as well as on the untreat ed teeth.
Discussion The photographs provide good pictorial evi dence that in vivo “ remineralization” takes place rapidly after an acid-etch procedure. Sim ilar conclusions had been reached previously18'20; however, the important variable included in this study is the patients’ ages. The data presented here show that “ remineralization” occurs faster in the younger patients. The reasons for this dif ference may be variations in saliva content, me tabolism, and other dietary factors. The question about the appearance of the etched tooth is answered in these pictures. They show clearly that, on the basis of the difference in shading between the treated and untreated halves of the teeth, the return to normal texture is essentially completed after 48 hours in all teeth, regardless of patient age. Any differences existing at that time are small and become essen tially negligible within a few days. Any effect of the patient’s sex on the rate of “ remineralization” cannot be determined from this study.
Conclusion The application of the acid-etch technique to im prove adhesion of restoratives to enamel causes temporary décalcification of the enamel surface. This study shows that, in the oral environment, “ remineralization” is essentially complete after 48 hours; no detrimental side effects such as more rapid plaque buildup in the treated sections were noted. In addition to presenting pictorially Arana: ENAMEL AFTER ACID ETCHING ■ 1103
“R em ineralization” in tooth of 9-year-old boy.
Fig 1 ■ Im m ediately after etching.
Fig 2 ■ At tw o hours after etching.
Fig 3 ■ At six hours after etching.
Fig 4 ■ At 12 hours after etching.
Fig 5 ■ At 24 hours after etching.
Fig 6 ■ At 48 hours after etching.
Fig 7 ■ At 96 hours after etching.
'R em ineralization" in tooth of 24-year-old wom an.
Fig 8 ■ Im m ediately after etching.
Fig 9 • At 215 hours after etching.
Fig 10 ■ Im m ediately after etching.
Fig 11 ■ At 383 hours after etching.
‘R em ineralization” in tooth of 55-year-old man.
‘R em ineralization” in tooth of 67-year-old woman.
Fig 12 ■ Im m ediately after etching.
Fig 13 ■ At 383 hours after etching.
the progress of “ remineralized,” the pictures show that any fears of damage caused by etch ing are essentially groundless.
Dr. Arana’s address is Fifth and Dolores St, PO Box 2101, Car mel, Calif 93921.
*Lee Pharmaceuticals, South El Monte, Calif 91733. 1. Buonocore, M.G. A simple method of increasing the adhe sion of acrylic filling materials to enamel surfaces. J Dent Res 34: 849 Dec 1955. 2. Groper, J.N. The etch technique for anterior tooth restor ations. J S Calif Dent Assoc 39:756 Sept 1971. 3. Laswell, H.R.; Welk, D.A.; and Regenos, J.W. Attachment of resin restorations to acid pretreated enamel. JADA 82:558 March 1971. 4. Robb, R.G. Restoration of fractured incisors using a plastic crown form and composite resin. J S Calif Dent Assoc 40:449 May 1972. 5. Ripa, L.W., and Cole, W.W. Occlusal sealing and caries pre vention: results 12 months after a single application of adhesive resin. J Dent Res 49:171 Jan-Feb 1970. 6. Buonocore, M. Adhesive caries prevention, with use of ultraviolet light. JADA 80:324 Feb 1970. 7. Buonocore, M. Caries prevention in pits and fissures sealed with an adhesive resin polymerized by ultraviolet light: a twoyear study of a single adhesive application. JADA 82:1090 May 1971.
8. Ibsen, R.L. Non-operative treatment for gingival erosion. Dent Surv 48:22 March 1972. 9. Portnoy, L. Retention studies of composite coating for gin gival erosion. Lee Pharmaceuticals Res Rep no. 72-107, 1972. 10. Retief, D.H., and Dreyer, C.J. Epoxy resins for bonding orthodontic attachments to teeth. J Dent Assoc S Afr 22:338 Nov 15, 1967. 11. Retief, D.H.; Dreyer, C.J.; and Gavron, G. The direct bond ing of orthodontic attachments to teeth by means of an epoxy resin adhesive. Am J Orthod 58:21 July 1970. 12. Miura, F.; Nakagawa, K.; and Masuhara, E.: New direct bonding system for plastic brackets. Am J Orthod 59:350 April 1971. 13. Letters. Tison, W.M. Use of sealant harmful? ADA NEWS Aug 3, 1970, p 2. 14. Gortner, R.A., and others. Factors influencing the destruc tive effects of acidic beverages on the teeth of white rats and hamsters. Arch Biochem 8:405 Aug 1945. 15. Bieri, J.G., and others. Further studies on in vivo tooth de calcification by acid beverages. Arch Biochem 11:33 Nov 1946. 16. Conboy, C.A., and Cox, G.J. Effects of food acids on human teeth in vitro. J Dent Res 50:520 March-April 1971. 17. Sognnaes, R.F. Dental hard tissue destruction with special reference to idiopathic erosions. Publ no. 75. American Associa tion for the Advancement of Science, 1963, p 91. 18. Miihlemann, H.R.;. Lenz, H.; and Rossinsky, K. Electron microscopic appearance o f rehardened enamel. Helv Odontol Acta 8:108 Oct 1964. 19. Lee, H., and others. Application of scanning electron mi croscopy to in vivo remineralization studies of human enamel. Lee Pharmaceuticals Res Rep no. 70-147, 1970. 20. Albert, M., and Grenoble, D.E. An in-vivo study of enamel remineralization after acid etching. J S Calif Dent Assoc 39:747 Sept 1971.
Foley’s Footnotes On the Edge of Evening (1946), the autobiography o f Cornelius Weygandt, who gained prominence as a University o f Pennsylvania professor and as a writer o f many good books, provided me with poignant values o f feeling and information. I recommend it to almost any reader because o f the author’s appealing offering o f warmly recorded recollections about persons, places, and personal enthu siasms. Reading Weygandt’s notes about writing, music, antiques, folklore, birds, lecturing, and his residences in Germantown and rural New Hampshire will pro vide you with a rare collection o f literary delights. Of special interest to us is Weygandt’s reporting of a meeting with a beggar immediately after a visit to a dental office and the beggar’s pathetic tribute to his own extracted teeth. You are waiting for Dr. Philips to haul you home by his car from the dentist’s office at Fifteenth and Locust Streets. You have lost five teeth. An old man comes up to beg of you. He sees your despoiled gums. The hand that pockets your nickel withdraws from the pocket’s depth a handful of teeth. “These are mine a dentist took out,” he says, ‘‘at a dollar apiece. See how sound they all are. I wonder will I ever be able to sell them again for what they cost me to have them pulled?” Perhaps there is a nuance in the beggar’s feeling, not spoken, that would prompt the reader to recall the eminent lines of Omar Khayyam (Rubaiyat XCV): “I wonder often what the Vintners buy / One half so precious as the stuff they sell.”
Gardner P. H. Foley
1106 ■ JADA, Vol. 89, November 1974
Clinical observations of enamel after acid-etch procedure
Edward M. Arana, DDS, Carm el, C alif
The use of the acid-etch technique to improve adhesion of restoratives has gained wide accep tance since the time it was first reported by Buonocore.1 This technique has been used to improve marginal adaptations of restoratives, in the re pair of fractured incisal angles,2"7 for coating of erosion on the gingival third of a tooth,8-9 and for bonding of orthodontic brackets to enamel.1012 Some practitioners have been concerned about damage to sound tooth structure that could re sult from the use of acids. Tison,13 in 1970, chal lenged the use of acid etches on the basis of dam age to the surfaces of teeth. This concern may be traced back 25 years to work reported on the décalcification of teeth because of the ingestion of phosphoric and citric acid solutions.1416 Several investigators have found “ remineral ization” after acid etching to be fairly rapid. The term “ remineralization” is used to describe the return to normal appearance; the mechanism of this process has not been dearly identified. Buonocore,1 using 85% phosphoric acid, noted that the enamel surface appeared normal after a few days, except for a faint loss of luster. Sog1102 ■ JADA, Vol. 89, November 1974
nnaes17 reported complete “ remineralization” of the enamel surfaces in monkeys after a citric acid etch. Miiehlmann and co-workers18 found that the characteristic prism-end pattern of etched enamel disappeared in 2 to 48 days. Later, Retief and associates11 observed “ remineraliza tion” one week after treatm ent with 50% phos phoric acid. In an in vivo replication technique Lee and co-workers19 found almost complete “ remineralization” within 72 hours after etching with 50% citric acid. Albert and Grenoble20 found that calcium phosphate was deposited within one hour and that “ remineralization” was com plete after 96 hours in deciduous teeth etched with 50% phosphoric acid. Other workers found that acid etchants caused no detrimental effects. The purpose of this study was to determine and to record photographically over a two-week period the progress of “ remineralization” in vivo in teeth exposed to a two-minute acid etch. Pa tients of various ages were selected from a pri vate practice, and the teeth were etched in the exact manner in which they would have been treated before the application of restoratives.
Materials and methods The mandibular right central incisor was chosen because of accessibility and of photography ease. The four patients in this study were a 9year, 3-month-old boy; a 24-year, 7-month-old woman; a 55-year, 9-month-old man; and a 67year, 2-month-old woman. The rate of “ remineralization” was deter mined by isolating the bottom half of the tooth with black inlay wax, so that only the incisal half was available for etching. In this way, the two halves of the tooth could be compared. The wax was applied hot in the usual manner with a wax spatula. Etching was performed with the etchant avail able in a commercial Restodent* kit, which is a colored gel composition containing 50% phos phoric acid. This etchant was applied for two minutes and then washed off. Immediately after etching, the wax on the lower half of the tooth was removed with a carving instrument, and the tooth was photographed. Other photographs were taken two minutes after etching, and after 2, 6, 12, 24, 48, 96, 215, and 383 hours. Kodachrome II Daylight film with an 81A filter was used; most pictures were taken at F 19. N o in structions were given to the patients after the etch procedure.
Results The progress of “ remineralization” of the inci sor in the 9-year-old boy is shown in Figures 1 through 7, which show, respectively, the tooth immediately after etching, and after 2, 6, 12, 24, 48, and 96 hours. F or the other three patients, two pictures of each tooth are shown; one was taken immediately after etching and the other at a time when “ remineralization” was essentially completed. Figures 8 and 9 are pictures of the tooth of the 24-year-old woman, Figures 10 and 11 of the tooth of the 55-year-old man, and Fig ures 12 and 13 of the tooth of the 67-year-old woman. Inspection of the photographs indicates that, in the 9-year-old boy, the difference in shading of the enamel was very faint after 24 hours and had practically disappeared after 48 hours. A t the 96-hour check, the enamel had returned com pletely to normal appearance. In the 24-year-old woman, a faint differentiation existed after 24 hours; it became very slight 48 hours after etch
ing. A t 96 hours the difference had practically disappeared, and after 215 hours the difference was negligible. “ Remineralization” of the en amel in the 55-year-old man seemed to be well completed after 48 hours; the difference in color ation of the two parts of the tooth was only faint. This difference had become slight after 215 hours and essentially negligible after 383 hours. In the 67-year-old woman, the difference in the enamel after 96 hours was very faint, and essentially no difference was noted after 383 hours. In addition to showing the etched surfaces as they revert to normal appearance, these pictures also provide evidence for the absence of plaque formation on the treated as well as on the untreat ed teeth.
Discussion The photographs provide good pictorial evi dence that in vivo “ remineralization” takes place rapidly after an acid-etch procedure. Sim ilar conclusions had been reached previously18'20; however, the important variable included in this study is the patients’ ages. The data presented here show that “ remineralization” occurs faster in the younger patients. The reasons for this dif ference may be variations in saliva content, me tabolism, and other dietary factors. The question about the appearance of the etched tooth is answered in these pictures. They show clearly that, on the basis of the difference in shading between the treated and untreated halves of the teeth, the return to normal texture is essentially completed after 48 hours in all teeth, regardless of patient age. Any differences existing at that time are small and become essen tially negligible within a few days. Any effect of the patient’s sex on the rate of “ remineralization” cannot be determined from this study.
Conclusion The application of the acid-etch technique to im prove adhesion of restoratives to enamel causes temporary décalcification of the enamel surface. This study shows that, in the oral environment, “ remineralization” is essentially complete after 48 hours; no detrimental side effects such as more rapid plaque buildup in the treated sections were noted. In addition to presenting pictorially Arana: ENAMEL AFTER ACID ETCHING ■ 1103
“R em ineralization” in tooth of 9-year-old boy.
Fig 1 ■ Im m ediately after etching.
Fig 2 ■ At tw o hours after etching.
Fig 3 ■ At six hours after etching.
Fig 4 ■ At 12 hours after etching.
Fig 5 ■ At 24 hours after etching.
Fig 6 ■ At 48 hours after etching.
Fig 7 ■ At 96 hours after etching.
'R em ineralization" in tooth of 24-year-old wom an.
Fig 8 ■ Im m ediately after etching.
Fig 9 • At 215 hours after etching.
Fig 10 ■ Im m ediately after etching.
Fig 11 ■ At 383 hours after etching.
‘R em ineralization” in tooth of 55-year-old man.
‘R em ineralization” in tooth of 67-year-old woman.
Fig 12 ■ Im m ediately after etching.
Fig 13 ■ At 383 hours after etching.
the progress of “ remineralized,” the pictures show that any fears of damage caused by etch ing are essentially groundless.
Dr. Arana’s address is Fifth and Dolores St, PO Box 2101, Car mel, Calif 93921.
*Lee Pharmaceuticals, South El Monte, Calif 91733. 1. Buonocore, M.G. A simple method of increasing the adhe sion of acrylic filling materials to enamel surfaces. J Dent Res 34: 849 Dec 1955. 2. Groper, J.N. The etch technique for anterior tooth restor ations. J S Calif Dent Assoc 39:756 Sept 1971. 3. Laswell, H.R.; Welk, D.A.; and Regenos, J.W. Attachment of resin restorations to acid pretreated enamel. JADA 82:558 March 1971. 4. Robb, R.G. Restoration of fractured incisors using a plastic crown form and composite resin. J S Calif Dent Assoc 40:449 May 1972. 5. Ripa, L.W., and Cole, W.W. Occlusal sealing and caries pre vention: results 12 months after a single application of adhesive resin. J Dent Res 49:171 Jan-Feb 1970. 6. Buonocore, M. Adhesive caries prevention, with use of ultraviolet light. JADA 80:324 Feb 1970. 7. Buonocore, M. Caries prevention in pits and fissures sealed with an adhesive resin polymerized by ultraviolet light: a twoyear study of a single adhesive application. JADA 82:1090 May 1971.
8. Ibsen, R.L. Non-operative treatment for gingival erosion. Dent Surv 48:22 March 1972. 9. Portnoy, L. Retention studies of composite coating for gin gival erosion. Lee Pharmaceuticals Res Rep no. 72-107, 1972. 10. Retief, D.H., and Dreyer, C.J. Epoxy resins for bonding orthodontic attachments to teeth. J Dent Assoc S Afr 22:338 Nov 15, 1967. 11. Retief, D.H.; Dreyer, C.J.; and Gavron, G. The direct bond ing of orthodontic attachments to teeth by means of an epoxy resin adhesive. Am J Orthod 58:21 July 1970. 12. Miura, F.; Nakagawa, K.; and Masuhara, E.: New direct bonding system for plastic brackets. Am J Orthod 59:350 April 1971. 13. Letters. Tison, W.M. Use of sealant harmful? ADA NEWS Aug 3, 1970, p 2. 14. Gortner, R.A., and others. Factors influencing the destruc tive effects of acidic beverages on the teeth of white rats and hamsters. Arch Biochem 8:405 Aug 1945. 15. Bieri, J.G., and others. Further studies on in vivo tooth de calcification by acid beverages. Arch Biochem 11:33 Nov 1946. 16. Conboy, C.A., and Cox, G.J. Effects of food acids on human teeth in vitro. J Dent Res 50:520 March-April 1971. 17. Sognnaes, R.F. Dental hard tissue destruction with special reference to idiopathic erosions. Publ no. 75. American Associa tion for the Advancement of Science, 1963, p 91. 18. Miihlemann, H.R.;. Lenz, H.; and Rossinsky, K. Electron microscopic appearance o f rehardened enamel. Helv Odontol Acta 8:108 Oct 1964. 19. Lee, H., and others. Application of scanning electron mi croscopy to in vivo remineralization studies of human enamel. Lee Pharmaceuticals Res Rep no. 70-147, 1970. 20. Albert, M., and Grenoble, D.E. An in-vivo study of enamel remineralization after acid etching. J S Calif Dent Assoc 39:747 Sept 1971.
Foley’s Footnotes On the Edge of Evening (1946), the autobiography o f Cornelius Weygandt, who gained prominence as a University o f Pennsylvania professor and as a writer o f many good books, provided me with poignant values o f feeling and information. I recommend it to almost any reader because o f the author’s appealing offering o f warmly recorded recollections about persons, places, and personal enthu siasms. Reading Weygandt’s notes about writing, music, antiques, folklore, birds, lecturing, and his residences in Germantown and rural New Hampshire will pro vide you with a rare collection o f literary delights. Of special interest to us is Weygandt’s reporting of a meeting with a beggar immediately after a visit to a dental office and the beggar’s pathetic tribute to his own extracted teeth. You are waiting for Dr. Philips to haul you home by his car from the dentist’s office at Fifteenth and Locust Streets. You have lost five teeth. An old man comes up to beg of you. He sees your despoiled gums. The hand that pockets your nickel withdraws from the pocket’s depth a handful of teeth. “These are mine a dentist took out,” he says, ‘‘at a dollar apiece. See how sound they all are. I wonder will I ever be able to sell them again for what they cost me to have them pulled?” Perhaps there is a nuance in the beggar’s feeling, not spoken, that would prompt the reader to recall the eminent lines of Omar Khayyam (Rubaiyat XCV): “I wonder often what the Vintners buy / One half so precious as the stuff they sell.”
Gardner P. H. Foley
1106 ■ JADA, Vol. 89, November 1974