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Comparison of bond strength between a conventional resin adhesive and a resin-modified glass ionomer adhesive: an in vitro and in vivo study
REVIEWS AND ABSTRACTS
Book reviews and article abstracts Alex Jacobson, DMD, MS, PhD Birmingham, Ala
THESIS ABSTRACTS
In vitro evaluation of threedimensional orthodontic mechanical force systems Rick Daniel Alter Department of Orthodontics, Virginia Commonwealth University, Richmond
Orthodontic tooth movement occurs in response to the application of controlled mechanical force systems. The purpose of this study was to improve understanding of those force systems by evaluating differences between the results of 2-dimensional and 3-dimensional orthodontic appliance activations. An in vitro model was constructed, and a forcemoment gauge was used to measure the forces and moments produced. Comparisons were made between 2-dimensional and 3-dimensional V-bend activations and among various 3-dimensional arch forms with V-bend activations. Locations of V-bends resulting in zero moment at the molar, zero moment at the incisor, and zero equilibrium forces were all found to be significantly closer to the molar for the 3-dimensional wires. Smaller differences were found among 3-dimensional arch forms. These results suggest that there are consistent and predictable differences between the resultant force systems from 3-dimensional orthodontic appliances and those described by 2-dimensional models. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.34
Comparison of bond strength between a conventional resin adhesive and a resin-modified glass ionomer adhesive: an in vitro and in vivo study Andrew Summers, DDS, Peter Ngan, DMD, Elizabeth Kao, DMD, MS, Jeffery Gilmore, DDS, MS, and Erdogan Gunel, PhD School of Dentistry, West Virginia University, Morgantown
The purposes of this study were (1) to compare the in vivo survival rate of orthodontic brackets bonded with a resinmodified glass ionomer adhesive (RMGI, Fuji Ortho LC, GC America) after conditioning with 10% polyacrylic acid and a conventional resin adhesive (Light Bond, Reliance Orthodontic Products) after etching with 37% phosphoric acid; (2) to deter-
mine the in vitro bond strength between the 2 adhesives; (3) to determine the bracket failure interface with the adhesive remnant index (ARI); and (4) to determine the morphology of the enamel surface after etching with 37% phosphoric acid or conditioning with 10% polyacrylic acid with scanning electron microscopy (SEM). For the in vitro part of the study, 50 extracted premolars were randomly divided into 4 groups. In groups I and II, brackets were bonded to enamel conditioned with 10% polyacrylic acid using Fuji Ortho LC for 30 minutes and 24 hours. In groups III and IV, brackets were bonded to enamel etched with 37% phosphoric acid using Light Bond for 30 minutes and 24 hours. Debonding force was determined with an Instron testing machine with a crosshead speed of 1 mm/min. Data were analyzed with ANOVA and paired t tests at P ⬍ .05. A significant difference was found among all 4 test groups. Light Bond tested at 24 hours had the greatest average debonding force at 18.46 Mpa followed by Light Bond tested at 30 minutes (16.19 Mpa). Fuji Ortho LC tested at 24 hours averaged 9.56 Mpa, and Fuji Ortho LC at 30 minutes had the lowest bond strength at 6.93 Mpa. Bond failure interface showed a significant difference at P ⬍ .05 between the 2 adhesives. Fuji Ortho LC had a mean ARI value of 4.92, and Light Bond had a mean ARI value of 4.31. For the in vivo study, 22 participants were bonded with a split-mouth technique using contralateral quadrants. A total of 199 teeth were bonded with Fuji Ortho LC, and 199 teeth were bonded with Light Bond. Bracket survival rates and distributions were obtained by following these patients for 1.3 years. Data were analyzed with the Kaplan-Meier product-limit estimates of survivorship function. No significant difference was found between the 2 adhesives. Fuji Ortho LC had a failure rate of 6.5%, and Light Bond’s failure rate was 5.0%. Bond failure interface was determined on the failed brackets. The ARI showed no significant differences between the 2 materials. The morphology of enamel treated with 37% phosphoric acid and 10% polyacrylic acid was examined with SEM. The 37% phosphoric acid for 30 seconds produced a much rougher surface with more surface irregularities than the surface treated with 10% polyacrylic acid, which showed some smooth precipitate. These results suggest that the clinical bond strength for RMGI conditioned with 10% polyacrylic acid is adequate to withstand the occlusal forces of chewing and biting. Although the shear bond strength of RMGI is lower than that of the conventional resin, the survival rate of the 2 materials is similar after following the survival distribution for 1.3 years. Most of the adhesive remained on the bracket for the Fuji Ortho LC group, but more adhesive remained on the enamel for the conventional resin group. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.39
American Journal of Orthodontics and Dentofacial Orthopedics /January 2003
99
Book reviews and article abstracts Alex Jacobson, DMD, MS, PhD Birmingham, Ala
THESIS ABSTRACTS
In vitro evaluation of threedimensional orthodontic mechanical force systems Rick Daniel Alter Department of Orthodontics, Virginia Commonwealth University, Richmond
Orthodontic tooth movement occurs in response to the application of controlled mechanical force systems. The purpose of this study was to improve understanding of those force systems by evaluating differences between the results of 2-dimensional and 3-dimensional orthodontic appliance activations. An in vitro model was constructed, and a forcemoment gauge was used to measure the forces and moments produced. Comparisons were made between 2-dimensional and 3-dimensional V-bend activations and among various 3-dimensional arch forms with V-bend activations. Locations of V-bends resulting in zero moment at the molar, zero moment at the incisor, and zero equilibrium forces were all found to be significantly closer to the molar for the 3-dimensional wires. Smaller differences were found among 3-dimensional arch forms. These results suggest that there are consistent and predictable differences between the resultant force systems from 3-dimensional orthodontic appliances and those described by 2-dimensional models. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.34
Comparison of bond strength between a conventional resin adhesive and a resin-modified glass ionomer adhesive: an in vitro and in vivo study Andrew Summers, DDS, Peter Ngan, DMD, Elizabeth Kao, DMD, MS, Jeffery Gilmore, DDS, MS, and Erdogan Gunel, PhD School of Dentistry, West Virginia University, Morgantown
The purposes of this study were (1) to compare the in vivo survival rate of orthodontic brackets bonded with a resinmodified glass ionomer adhesive (RMGI, Fuji Ortho LC, GC America) after conditioning with 10% polyacrylic acid and a conventional resin adhesive (Light Bond, Reliance Orthodontic Products) after etching with 37% phosphoric acid; (2) to deter-
mine the in vitro bond strength between the 2 adhesives; (3) to determine the bracket failure interface with the adhesive remnant index (ARI); and (4) to determine the morphology of the enamel surface after etching with 37% phosphoric acid or conditioning with 10% polyacrylic acid with scanning electron microscopy (SEM). For the in vitro part of the study, 50 extracted premolars were randomly divided into 4 groups. In groups I and II, brackets were bonded to enamel conditioned with 10% polyacrylic acid using Fuji Ortho LC for 30 minutes and 24 hours. In groups III and IV, brackets were bonded to enamel etched with 37% phosphoric acid using Light Bond for 30 minutes and 24 hours. Debonding force was determined with an Instron testing machine with a crosshead speed of 1 mm/min. Data were analyzed with ANOVA and paired t tests at P ⬍ .05. A significant difference was found among all 4 test groups. Light Bond tested at 24 hours had the greatest average debonding force at 18.46 Mpa followed by Light Bond tested at 30 minutes (16.19 Mpa). Fuji Ortho LC tested at 24 hours averaged 9.56 Mpa, and Fuji Ortho LC at 30 minutes had the lowest bond strength at 6.93 Mpa. Bond failure interface showed a significant difference at P ⬍ .05 between the 2 adhesives. Fuji Ortho LC had a mean ARI value of 4.92, and Light Bond had a mean ARI value of 4.31. For the in vivo study, 22 participants were bonded with a split-mouth technique using contralateral quadrants. A total of 199 teeth were bonded with Fuji Ortho LC, and 199 teeth were bonded with Light Bond. Bracket survival rates and distributions were obtained by following these patients for 1.3 years. Data were analyzed with the Kaplan-Meier product-limit estimates of survivorship function. No significant difference was found between the 2 adhesives. Fuji Ortho LC had a failure rate of 6.5%, and Light Bond’s failure rate was 5.0%. Bond failure interface was determined on the failed brackets. The ARI showed no significant differences between the 2 materials. The morphology of enamel treated with 37% phosphoric acid and 10% polyacrylic acid was examined with SEM. The 37% phosphoric acid for 30 seconds produced a much rougher surface with more surface irregularities than the surface treated with 10% polyacrylic acid, which showed some smooth precipitate. These results suggest that the clinical bond strength for RMGI conditioned with 10% polyacrylic acid is adequate to withstand the occlusal forces of chewing and biting. Although the shear bond strength of RMGI is lower than that of the conventional resin, the survival rate of the 2 materials is similar after following the survival distribution for 1.3 years. Most of the adhesive remained on the bracket for the Fuji Ortho LC group, but more adhesive remained on the enamel for the conventional resin group. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.39
American Journal of Orthodontics and Dentofacial Orthopedics /January 2003
99