ABSTRACT
UNLABELLED: Provision of partial and complete dentures constructed from resin is commonplace and a satisfactory outcome requires the consideration of the properties of the resin, the oral tissues and prosthodontic principles. This second of a two-part series examines the advantages and disadvantages of flexible nylon denture base resins, which have found popularity for the provision of partial dentures. Adverse effects of denture base resins are examined and the benefits and shortcomings of softliners are explored. Chairside adjustment and polishing, and denture hygiene are also discussed. CLINICAL RELEVANCE: Knowledge of contemporary denture base resin systems will help to achieve optimal outcomes in removable prosthodontics.
Subject(s)
Dental Materials/chemistry , Denture Bases , Denture, Partial , Nylons/chemistry , Acrylic Resins/adverse effects , Acrylic Resins/chemistry , Allergens/adverse effects , Biocompatible Materials/adverse effects , Biocompatible Materials/chemistry , Dental Abutments , Dental Clasps , Dental Disinfectants/chemistry , Dental Materials/adverse effects , Dental Polishing/methods , Denture Cleansers/chemistry , Denture Design , Denture Liners , Denture Retention , Humans , Nylons/adverse effects , Oral Hygiene , Pliability , Silicone Elastomers/chemistry , Stomatitis, Denture/etiology , Surface Properties , TorqueABSTRACT
UNLABELLED: Provision of partial and complete dentures constructed from resin is commonplace and a satisfactory outcome requires the consideration of the properties of the resin, the oral tissues and prosthodontic principles. Conventional acrylic resin has been widely adopted as a popular denture base material since the 1930s. In this first of a two-part series, the benefits and shortcomings of acrylic resin are discussed alongside contemporary 'enhancements' to the material which can improve its properties. In the second part of the series, flexible and other alternative denture base resins, soft-linings, adverse effects of denture base materials and maintenance will be discussed. CLINICAL RELEVANCE: Knowledge of contemporary denture base resin systems will help to achieve optimal outcomes in removable prosthodontics.
Subject(s)
Acrylic Resins/chemistry , Dental Materials/chemistry , Denture Bases , Biocompatible Materials/chemistry , Biomechanical Phenomena , Dental Restoration Failure , Denture Design , Denture, Complete , Denture, Partial, Removable , Elastic Modulus , Esthetics, Dental , Glass/chemistry , Humans , Mouth Mucosa/anatomy & histology , Pliability , Polyethylene/chemistry , Polymethyl Methacrylate/chemistry , Prosthesis Coloring , Surface PropertiesABSTRACT
OBJECTIVE: To compare the Shear Bond Strength (SBS) of resin-bonded metal/enamel bonds with the Fatigue Limit and Fatigue Life of identical joints. METHODS: 285 discs of Ni/Cr-alloy (dia 5 mmx4 mm) were cast and treated by either (1) Sandblasting with aluminium oxide or (2) Sandblast+15 min electrolyticetch in HCl. The discs were bonded to etched enamel (37% HPO4/30 s) using 3 bonding systems. Ten discs of each group were subjected to a shear bond test (SBT) in a Universal Testing Machine5 (CHS=50 mm/min). Seventeen discs of each group were used to determine the Fatigue Limit using the Staircase method (5000 cycles, 4 kg increment). Further batches of 10 discs were subjected to cyclic loads of either 5, 10, or 20 kg to determine the number of cycles at failure (Fatigue Life). The SBS and Fatigue Limit results were compared by correlation analysis. The Fatigue-Life cycles were compared by Weibull analysis to determine the beta (reliability) and alpha (number of cycles) coefficients for the 3 loads. RESULTS: For all materials and treatments, the Fatigue-Limit results were much lower than the SBS and there was no correlation between the values (r=0.49, p=0.18). The Fatigue Limit for the samples using 5000 cycles ranged from 10.7 to 16.1 MPa. In the Fatigue-Life study, the stress at which the samples were reliably able to withstand more than 1 million cycles (beta>5) was 2.5 MPa. CONCLUSION: The Fatigue Limit of the bonds was much lower than the SBS and there was no correlation between the two values. In this study the Fatigue Limit was not a good predictor of the long term Fatigue-Life failure of the specimens.
Subject(s)
Chromium Alloys/chemistry , Dental Bonding , Dental Enamel/ultrastructure , Resin Cements/chemistry , Acid Etching, Dental/methods , Aluminum Oxide/chemistry , Dental Etching/methods , Dental Stress Analysis/instrumentation , Electrolysis , Humans , Hydrochloric Acid/chemistry , Materials Testing , Methacrylates/chemistry , Polymethacrylic Acids/chemistry , Shear Strength , Stress, MechanicalABSTRACT
OBJECTIVE: The purpose of this study was to determine the shear bond strength of new composite to water aged composite with and without interfacial surface treatment. METHODS: Two hundred and eighty cylindrical samples were prepared for each of three resin composites (Spectrum, Dentsply; Durafill, Kulzer; Herculite, Kerr). Seventy samples of each material were bonded immediately and the remaining were stored in water. After 1, 4 and 12 weeks 70 samples were removed and the surface treated prior to bonding a second fresh increment. The treatments were: (1) no treatment, (2) abrasion with pumice, (3) a layer of Prime and Bond (Dentsply), (4) abrasion+Prime and Bond, (5) a layer of Optibond Solo Plus (Kerr), (6) abrasion+Optibond and (7) a layer of bis-GMA/TEGDMA. The specimens were loaded to failure in shear mode with a crosshead speed of 50 mm/min until fracture. The fracture surface of a number of specimens were examined in a scanning electron microscope. RESULTS: At all time intervals the treatment that resulted in the highest bond strengths (>20 MPa) was treatment with the dentine bonding agents (DBS) Prime and Bond or Optibond Solobond Plus. No treatment or abrasion alone resulted in very low bond strengths even after 1 week in water. When used in conjunction with DBS's abrasion did not increase the bond strength over the use of the DBS alone. The bis-GMA/TEGDMA was not as effective as the DBS's. SIGNIFICANCE: When bonding new composite to composite that has been underwater it is essential to treat the original composite surface. The results of this study indicated that the application of a dentine bonding agent significantly enhanced the bond. Abrasion alone did not produce an adequate bond.
