ABSTRACT
The resistance of the cavity walls of non-vital premolars to vertically applied occlusal forces was studied. Standardized MOD cavities were prepared, restored, and vertical forces were applied to each of the cuspal tips by the Instron machine. Results suggest that bevelled etched-enamel margins and dentine-bonded posterior composite resin restorations significantly improved (by 33%) the resistance of the remaining cavity walls compared to amalgam restorations. In a control group, in which no restorations were carried out in the prepared cavities, the resistance of the walls was significantly smaller than in both restored groups.
Subject(s)
Composite Resins , Dental Amalgam , Dental Restoration, Permanent/methods , Tooth Fractures/prevention & control , Bicuspid , Bite Force , Dental Stress Analysis , Equipment Design , Humans , MolarABSTRACT
Two hundred and forty root canals of extracted single-rooted teeth were prepared to the same dimension, and Dentatus posts of equal size were cemented without screwing them into the dentine. Five cleansing solutions and two dentine adhesive systems were evaluated prior to post-cementation using chemical-cure composite resin. 'Pull-out' tests were then conducted in order to evaluate the bond strength of these intra-pulpal posts. The use of Conclude (composite luting cement) alone, with or without the cleansing solutions, resulted in significantly lower pull-out forces. Scotchbond Dental Adhesive gave significantly better results, regardless of the cleansing solution used. Gluma Dentine Adhesive significantly increased the pull-out forces only when used with its supplied cleanser or Tubulicid.
Subject(s)
Acrylates , Aldehydes , Crowns , Dental Cements , Dentin/drug effects , Denture Retention , Glutaral , Methacrylates , Polymethacrylic Acids , Post and Core Technique , Resin Cements , Root Canal Irrigants/pharmacology , Acrylic Resins , Bisphenol A-Glycidyl Methacrylate , Chlorhexidine , Citrates , Citric Acid , Dental Bonding/methods , Dental Stress Analysis , Dentin/ultrastructure , Dequalinium , Evaluation Studies as Topic , Humans , Phosphoric Acids , Post and Core Technique/instrumentationABSTRACT
Preparation design for posterior composite restorations should differ from that for amalgam restorations in the following manner. Occlusal form should be narrower and the depth shallower. The proximal extensions (facial and lingual) should be placed in areas that can be seen, probed, and polished. Internal line angles should be rounded and retenive grooves placed in proximal line angles (axiofacial and axiolingual) and the gingival wall. Beveling is recommended for proximal margins but not for occlusal margins.
Subject(s)
Composite Resins , Dental Cavity Preparation/methods , Dental Restoration, Permanent , Dental Enamel , Humans , Surface PropertiesABSTRACT
Sixty-three No. 4 Dentatus threaded posts were cemented in extracted teeth and tested for tensile strength. The cementing medium was Silar composite alone or in combination with a conventional bonding agent or Scotchbond dental adhesive, or both. Results indicate that: Retention was greater when the posts were cemented with the Silar composite preceded with the application of Scotchbond. Retention was less with Silar composite alone or combined with a conventional bonding agent. Scotchbond is suggested for use as a bonding agent when cementing Dentatus posts with composites.