ABSTRACT
STATEMENT OF PROBLEM: The Composipost dowel is made of stretched, aligned carbon fibres embedded in an epoxy-resin matrix. It is widely used in Europe and Canada for the restoration of endodontically treated teeth and was introduced in the United States 2 years ago as the C-Post dowel. PURPOSE: This retrospective study evaluated treatment outcome of the Composipost system after 2 to 3 years. MATERIAL AND METHODS: A total of 236 patients treated during a 1-year period by seven Swedish dental practitioners were included. Of those, 146 patients consented and data were collected from the dental records of the remaining patients. Thus, the material comprised 236 teeth restored with carbon fiber-reinforced epoxy resin post, 130 maxillary and 106 mandibular teeth, with a mean restoration time of 32 months (range 27 to 41). Periodontal conditions, radiographic signs, and prosthodontic results were recorded. RESULTS: Five teeth (2%) had been extracted for reasons unrelated to the Composipost system. Periodontal conditions such as plaque accumulation, gingival health, bleeding on probing, and pocket depth around the teeth with Composipost dowels were similar to the control teeth. No dislodgment or root or post fractures were observed clinically or on radiographs. Radiographic examination of bone height measured from the apex to the bone margin mesially and distally showed differences on the mesial side but not on the distal surface (p < 0.05) between the Composipost-treated teeth and the controls. CONCLUSIONS: Promising results after 2 to 3 years of clinical service indicate that this system can be a viable alternative to conventional post-and-core systems.
Subject(s)
Carbon , Dental Prosthesis Design , Epoxy Resins , Post and Core Technique/instrumentation , Adult , Aged , Aged, 80 and over , Alveolar Process/diagnostic imaging , Carbon/chemistry , Carbon Fiber , Dental Plaque/pathology , Dental Restoration Failure , Epoxy Resins/chemistry , Evaluation Studies as Topic , Female , Follow-Up Studies , Gingival Diseases/pathology , Gingival Hemorrhage/pathology , Humans , Male , Middle Aged , Periodontal Pocket/pathology , Radiography , Retrospective Studies , Root Canal Therapy , Tooth Apex/diagnostic imaging , Tooth Fractures/etiology , Tooth Root/injuries , Treatment OutcomeABSTRACT
The accuracy of rubber impression materials was evaluated by taking impressions of a steel model, pouring it with stone and comparing certain measurements between steel and stone models. It is assumed that acceptance is achieved when the difference in measurements is within permissible limits, defined by clinical criteria. A mathematical formulation of these criteria will lead to the concept of probability of acceptance. The probability is affected when the limits are changed. The particular case of satisfying two acceptance criteria that contain variables which are not statistically independent is considered, leading to the application of the bivariate normal distribution in the evaluation of acceptance probability.
Subject(s)
Dental Impression Materials/standards , Dental Materials/standards , Dental Implants/standards , Models, Theoretical , Polyvinyls/standards , Resins, Synthetic/standards , Rubber/metabolism , Rubber/standards , Siloxanes/standards , SteelABSTRACT
Residual strains are important for dimensional accuracy of impression materials. When these strains are being calculated, knowledge of thermophysical constants is needed. This paper describes determination of thermal diffusivity, thermal conductivity, specific heat, heat of polymerization rate, and total heat of polymerization. The first two constants mentioned were obtained from an experiment in which transient heat conductivity was studied. The evaluation was based on an analytical solution of this problem. The remaining constants were derived by means of standard differential scanning calorimetry, DSC. Results from accurate, cost-efficient methods are given for three silicones and one polyether.
