Sangeetha, Duraisamy (2005) Comparative evaluation of fluoride release and shear bond strength of a polyacid - modified composite resin, a resin modified glass ionomer cement and a conventional composite resin: An Invitro study. Masters thesis, Tamil Nadu Government Dental College and Hospital, Chennai.
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Abstract
The use of composite resins for direct bonding of orthodontic brackets has become a routine procedure in present day orthodontics. Despite several advantages of direct bonding systems, the development of enamel decalcification around bonded orthodontic appliances continues to be a great clinical concern. Several fluoride-releasing materials have been introduced as orthodontic bonding materials including glass ionomer cements, resin modified glass ionomer cement and poly acid modified composite resin in an attempt to minimize the incidence of decalcification around the orthodontic appliance. The present study was designed to evaluate the amount of fluoride release and the shear bond strength of a polyacid modified composite resin (Python light cure material) and to compare it with a resin modified Glass Ionomer cement (Fuji Ortho LC) and a conventional composite resin material (Transbond XT). The following conclusions were drawn from the results of the study: 1. The amount of fluoride released by the poly acid modified composite resin (Python) is significantly less than the amount of fluoride released by the resin modified glass ionomer cement (Fuji Ortho LC) , and significantly higher than the amount of fluoride released by conventional composite resin material (Transbond XT) in distilled water and artificial saliva through out the study period. 2. The type of storage medium created a significant difference in fluoride release for the resin modified glass ionomer cement (Fuji Ortho LC) through out the study period and for the poly acid modified composite resin (Python) at day 1 and 7.Both of them released more amount of fluorine in distilled water. At day 30, the type of storage medium did not created a significant difference in fluoride release for Python. 3. Although the fluoride release later declined with time, the amount of fluoride released by the poly acid modified composite resin (Python) and the resin modified glass ionomer cement (Fuji Ortho LC) were above the proposed effective range of 0.63 – 1.23 mg/cm2/d for inhibition of enamel demineralization. 4. The mean shear bond strength of the all the three adhesives tested was significantly higher at 24 hours than at 30 minutes. 5. The final (24 hours) bond strength of Python light cure adhesive was significantly greater than the final (24 hours) bond strength of the resin modified glass ionomer cement (Fuji Ortho LC), but was not significantly different from that of the conventional composite resin, (Transbond XT). 6. The highest weibull modulus of 3.83 was recorded with Transbond XT indicating the greatest bond reliability, followed by Python light cure adhesive. The highest characteristic strength was recorded with Transbond XT indicating the higher bond strength of the adhesive system followed by Python light cure adhesive. 7. All the adhesives tested in this investigation produced shear bond strength greater and within the range of 5.9 to 7.8 Mpa considered in the literature to be adequate for routine clinical uses, except the initial bond strength of resin modified glass ionomer cement. 8. The mode of bond failure for Python was adhesive or cohesive failure at bracket adhesive interface. The predominant bond failure of Transbond XT was more of adhesive bond failure at bracket adhesive interface. The predominant mode of bond failure of Resin modified Glass Ionomer cement was more of adhesive bond failure at bracket enamel interface. 9. There is a significant correlation between the adhesive remnant index and the bond strength for all the six groups. Fluoride releasing adhesives have shown the potential to absorb and re-release fluoride after exposure to topical fluoride treatment. Further, leaching of fluoride ions from the resin matrix may weaken the bond strength of the material. The present study has evaluated only the fluoride release of the adhesive materials for a period of 30 days only and the bond strength of the materials at 30 min and 24 hours. The study on fluoride release and re-release of the orthodontic bonding materials should be done for a longer period of time to determine the amount of fluoride release throughout the estimated treatment period. The studies should be carried out in samples kept under running water or artificial saliva provided by a digital flow controller, with intermittent exposure to fluoride, to simulate the clinical condition. The bond strength should be evaluated at monthly intervals to determine the effect of fluoride release on the shear bond strength of the material. Clinical trials are recommended to evaluate the bond survival rate and potency of these poly acid modified composite material to prevent decalcification of the enamel.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | fluoride release, shear bond strength, polyacid, modified composite resin, resin modified glass ionomer cement, conventional composite resin. |
| Subjects: | DENTAL > Orthodontics and Dentofacial Orthopedics |
| Depositing User: | Kambaraman B |
| Date Deposited: | 24 Jan 2018 03:54 |
| Last Modified: | 24 Jan 2018 03:54 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/5542 |
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