Manoj, V (2010) A Comparative evaluation of bond strength and hardness of soft denture liners after thermocycling: An Invitro study. Masters thesis, Rajas Dental College and Hospital, Tirunelveli.
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Abstract
INTRODUCTION : The characterization of soft lining materials was done as early as in 1958 by Lammie and Storer. The use of tissue conditioning was first reported by Chase W.W. et al in 1961 for abused denture supporting tissues and to restore a normal healthy state. Travaglini et al later in 1960 studied the physical properties of various brands of acrylic based soft liners. Soft liners are provided to absorb some of the energy produced by masticator impact. Hence it serves as a shock absorber between the occlusal surfaces of a denture and the underlying oral tissue. The resilient lining materials are classified as temporary and soft permanent. The temporary materials are used for a limited period, approximately 7 days, to aid the healing of the tissues in contact with the denture. Soft permanent or long-term materials are used on complete dentures where it is necessary to absorb masticatory loads, and are indicated for patients who are unable to tolerate the pressures transmitted by the denture to the underlying mucosa of the edentulous ridge. The choice for a soft liner for clinical use should be based on the material’s biocompatibility, mechanical properties and durability in the oral environment. However, these lining materials may present physical and mechanical problems during clinical use such as color alteration, loss of plasticizer and resilience, poor rupture strength and porosity. In this context it is essential to study the physical properties of commonly used soft liners after subjecting to thermocycling (aging)Therefore, the purpose of this study was to compare the effect of the tensile bond strength and shear bond strengths and hardness of soft liner materials after thermocycling. AIM : The aim of the study was to evaluate and compare tensile bond strength, shear bond strength and Hardness of four soft denture liners after thermocycling. MATERIALS AND METHODS : Two silicone based soft liners (GC RelineTM soft, Ufigel-P) and two acrylic based soft liners (GC soft liner, visco-gel) were used in this study and a heat polymerized acrylic resin Fourty Eight specimens (25mm x 25mm x 3mm) were fabricated in stainless steel molds for testing Tensile and shear strength. Twenty disk shaped specimens (31mm x 6mm) were fabricated in stainless steel molds for hardness testing. These specimens were subjected to thermocycling (3000 cycles) between baths of 50 and 550C. The specimen preparation and test for hardness were carried out in accordance with the ISO Specification No. 10139 for soft denture liners. RESULT : After thermocycling, GC reline soft had higher tensile bond strength than (2.0185 MPa) Ufigel –P (1.5740 MPa), GC soft liner (1.1974 MPa) and visco-gel (0.5306 MPa) The shore A hardness values for GC reline soft, Ufigel – P, GC soft liner, visco-gel after thermocycling were (48.16, 28.4, 24.36, 5.68). The shear bond strength values were also higher for GC reline soft (2.5039MPa) compared to Ufigel – P (1.5675 MPa) GC soft liner (1.2161MPa) and visco-gel (0.4162 MPa) CONCLUSION : The silicone based soft liners (GC reliner, Ufigel –P) had higher values for tensile bond strength and shear bond strength, showing that they were more durable than acrylic based softliners. The acrylic based soft liners (viscogel, GC soft liner) showed lower values for hardness indicating they are more suitable for short term tissue conditioning.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Thermocycling, shore A hardness, soft denture liners, shear bond strength, tensile strength, Denture base resin. |
| Subjects: | DENTAL > Prosthodontics and Crown and Bridge |
| Depositing User: | Kambaraman B |
| Date Deposited: | 19 Jan 2018 02:17 |
| Last Modified: | 19 Jan 2018 02:17 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/5509 |
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