- Email: [email protected]
Study on degradation of posterior composite resins: II. Structural changes in subsurface damage layer of resins under alkaline conditions
152
.J.Dent.
1988;
16: No. 3
particles and resin matrix initially, followed later by swelling of the resin matrix. After 1 week, partial or total destruction of resin surfaces was observed. With MFR-type resin, the degradation of silane binders resulted in small gaps between prepolymerized fillers and resin matrix, and these gaps propagated with time. For SFR-type resins, the resin surfaces showed swelling initially, and later large cracks were produced between prepolymerized fillers comprising submicron spherical filler particles and matrix resin. The presence of alkaline and alkaline earth elements, such as Ba in filler particles, accelerated degradation of composite resin showing filler dissolution and resin exfoliation and greater destruction than observed in resins without alkaline and alkaline earth elements. (23 references) H. Hisamitsu
Study on degradation of posterior composite resins: II. Structural changes in subsurface damage layer of resins under alkaline conditions. Hosoda H., Yamada T. and lnokoshi S. (1987) Jap. J. Conserv Dent 30, 1251-l 265. The degradation process of 15 posterior composite resins under alkaline conditions was examined periodically on sectioned surfaces by SEM up to 1 week following immersion in 0.1 N NaOH solution at 60°C. Examination focused on the structural changes in the subsurface damage layer of resins. Of the resins tested P-30 (3M. USA), Ful-Fil (Caulk, USA) and Clearfil PhotoPosterior (Kuraray, Japan) showed the least degradation. The structural changes in the subsurface damage layer of resins generally showed crack formation between filler particles and the resin matrix, partial dissolution and exfoliation of filler particles, and also swelling of resin matrix. These features were observed to varying degrees depending upon the individual resin. The immersion test in 0 1 N NaOH solution at 60°C is considered an appropriate method to forecast rapidly the durability of posterior composites in vivo. (8 references) H. Hisamitsu
Metronidazole in cariology: II. The bactericidal efficacy of metronidazole in viwo against bacteria in lesions of human carious dentine. lwaku M., Hoshino E.,Kota K. et al. (1987) Jap. J. Conserv Dent. 30, 1444-1448. The aim of this study was to clarify the bactericidal efficacy of metronidazole against the bacteria in lesions of human carious dentine, and to find ways to adopt metronidazole effectively in caries treatment. The efficacy was estimated by measuring bacterial recovery from the lesions with or without application of metronidazole to the lesions in viva. More than 10” colony-forming units (CFUs) of bacteria were recovered from samples of carious dentine. However, none was recovered from samples of dentinal lesions which had been covered by aTCP cement containing metronidazole in situ for 1 day, 28 days and/or 1 year in vivo. While a_TCP cement itself
was reported not to be bactericidal, the bactericidal efficacy of metronidazole in situ is clearly demonstrated, suggesting that its topical application is effective in caries treatment to disinfect bacteria which remain in the smear layer, under restorations, intentionally in the deep layers of acute dentine caries, or invade subsequently from tooth surfaces. (16 references) H. Hisamitsu
A study on dye penetration methods of assessing adaptation of composite resin fillings to cavity walls. Fujitani M., Suzuki Y., Negishi T. et al. (1987) Jap. J. Conserv Dent. 30, 898-9 10. This study re-examined dye penetration methods in an attempt to identify one which would assess marginal leakage and adaptation of resin fillings. Saucer cavities were prepared on the cervical areas of 180 intact bovine teeth and then filled with either Clearfil FII New Bond (CIFII) or Clearfil Posterior New Bond (Cl P) (Kuraray, Japan). The application time of the dye solutions was varied, as was the combination of various dyes and solvents, and the staining response to the resin-tooth boundaries was estimated and compared. Basic fuchsin dye showed better dyeability than acid red dye regardless of their solvents, and the aqueous solutions of these two dyes exhibited better staining on the boundaries than their propylene glycol solution. A long application time was required to detect the interface with Indian ink, while a combination of 20 per cent silver nitrate and equivalent sodium hydroxide aqueous solutions needed the shortest time. However, the dentine around the resin fillings was so discoloured black by these solutions that boundaries were indiscernible. If the application time of the dye solutions was increased, there appeared to be better interface infiltration. Relatively wide gaps, which were present at resin-tooth boundaries using Cl P, allowed more rapid dye penetration compared to Cl FII. The staining behaviour of self-polymerized bonding agents (Clearfil New Bond) by various dye solutions was variable according to the hardening time. Basic fuchsin aqueous solution (O-5 per cent), basic fuchsin propylene glycol solution (0.5 per cent) and silver nitrate aqueous solution (20 per cent) exhibited good dyeability to the bonding agents hardened under any environment. A partially cured bonding agent could be stained with 1 per cent acid red aqueous solution and 1 per cent acid red propylene glycol solution as well as the three solutions mentioned above. On the contrary, it could not be dyed with Indian ink, or 0.5 per cent and 15 per cent acid fuchsin aqueous solutions. Acid fuchsin aqueous solution (15 per cent) showed the same degree of staining on the boundaries as basic fuchsin aqueous solution (0.5 per cent). These findings suggest that there appears to be a risk of making unreliable assessment under given experimental conditions. Application of 16 per cent acid fuchsin aqueous solution for more than 3 s may allow adequate evaluation in the examination of the adaptation of resin fillings. (44 references) H. Hisamitsu
.J.Dent.
1988;
16: No. 3
particles and resin matrix initially, followed later by swelling of the resin matrix. After 1 week, partial or total destruction of resin surfaces was observed. With MFR-type resin, the degradation of silane binders resulted in small gaps between prepolymerized fillers and resin matrix, and these gaps propagated with time. For SFR-type resins, the resin surfaces showed swelling initially, and later large cracks were produced between prepolymerized fillers comprising submicron spherical filler particles and matrix resin. The presence of alkaline and alkaline earth elements, such as Ba in filler particles, accelerated degradation of composite resin showing filler dissolution and resin exfoliation and greater destruction than observed in resins without alkaline and alkaline earth elements. (23 references) H. Hisamitsu
Study on degradation of posterior composite resins: II. Structural changes in subsurface damage layer of resins under alkaline conditions. Hosoda H., Yamada T. and lnokoshi S. (1987) Jap. J. Conserv Dent 30, 1251-l 265. The degradation process of 15 posterior composite resins under alkaline conditions was examined periodically on sectioned surfaces by SEM up to 1 week following immersion in 0.1 N NaOH solution at 60°C. Examination focused on the structural changes in the subsurface damage layer of resins. Of the resins tested P-30 (3M. USA), Ful-Fil (Caulk, USA) and Clearfil PhotoPosterior (Kuraray, Japan) showed the least degradation. The structural changes in the subsurface damage layer of resins generally showed crack formation between filler particles and the resin matrix, partial dissolution and exfoliation of filler particles, and also swelling of resin matrix. These features were observed to varying degrees depending upon the individual resin. The immersion test in 0 1 N NaOH solution at 60°C is considered an appropriate method to forecast rapidly the durability of posterior composites in vivo. (8 references) H. Hisamitsu
Metronidazole in cariology: II. The bactericidal efficacy of metronidazole in viwo against bacteria in lesions of human carious dentine. lwaku M., Hoshino E.,Kota K. et al. (1987) Jap. J. Conserv Dent. 30, 1444-1448. The aim of this study was to clarify the bactericidal efficacy of metronidazole against the bacteria in lesions of human carious dentine, and to find ways to adopt metronidazole effectively in caries treatment. The efficacy was estimated by measuring bacterial recovery from the lesions with or without application of metronidazole to the lesions in viva. More than 10” colony-forming units (CFUs) of bacteria were recovered from samples of carious dentine. However, none was recovered from samples of dentinal lesions which had been covered by aTCP cement containing metronidazole in situ for 1 day, 28 days and/or 1 year in vivo. While a_TCP cement itself
was reported not to be bactericidal, the bactericidal efficacy of metronidazole in situ is clearly demonstrated, suggesting that its topical application is effective in caries treatment to disinfect bacteria which remain in the smear layer, under restorations, intentionally in the deep layers of acute dentine caries, or invade subsequently from tooth surfaces. (16 references) H. Hisamitsu
A study on dye penetration methods of assessing adaptation of composite resin fillings to cavity walls. Fujitani M., Suzuki Y., Negishi T. et al. (1987) Jap. J. Conserv Dent. 30, 898-9 10. This study re-examined dye penetration methods in an attempt to identify one which would assess marginal leakage and adaptation of resin fillings. Saucer cavities were prepared on the cervical areas of 180 intact bovine teeth and then filled with either Clearfil FII New Bond (CIFII) or Clearfil Posterior New Bond (Cl P) (Kuraray, Japan). The application time of the dye solutions was varied, as was the combination of various dyes and solvents, and the staining response to the resin-tooth boundaries was estimated and compared. Basic fuchsin dye showed better dyeability than acid red dye regardless of their solvents, and the aqueous solutions of these two dyes exhibited better staining on the boundaries than their propylene glycol solution. A long application time was required to detect the interface with Indian ink, while a combination of 20 per cent silver nitrate and equivalent sodium hydroxide aqueous solutions needed the shortest time. However, the dentine around the resin fillings was so discoloured black by these solutions that boundaries were indiscernible. If the application time of the dye solutions was increased, there appeared to be better interface infiltration. Relatively wide gaps, which were present at resin-tooth boundaries using Cl P, allowed more rapid dye penetration compared to Cl FII. The staining behaviour of self-polymerized bonding agents (Clearfil New Bond) by various dye solutions was variable according to the hardening time. Basic fuchsin aqueous solution (O-5 per cent), basic fuchsin propylene glycol solution (0.5 per cent) and silver nitrate aqueous solution (20 per cent) exhibited good dyeability to the bonding agents hardened under any environment. A partially cured bonding agent could be stained with 1 per cent acid red aqueous solution and 1 per cent acid red propylene glycol solution as well as the three solutions mentioned above. On the contrary, it could not be dyed with Indian ink, or 0.5 per cent and 15 per cent acid fuchsin aqueous solutions. Acid fuchsin aqueous solution (15 per cent) showed the same degree of staining on the boundaries as basic fuchsin aqueous solution (0.5 per cent). These findings suggest that there appears to be a risk of making unreliable assessment under given experimental conditions. Application of 16 per cent acid fuchsin aqueous solution for more than 3 s may allow adequate evaluation in the examination of the adaptation of resin fillings. (44 references) H. Hisamitsu