ABSTRACT
STATEMENT OF PROBLEM: The increased use of adhesive resin cements in bonded prosthetic restorations has led to restorations debonding under function. PURPOSE: This investigation evaluated the differences in the flexural strength of new adhesive resin cements as a function of specimen age and storage condition. MATERIALS AND METHODS: Four new dual-cure cements were compared to C/B Metabond. Twenty specimens of each of the five cements were prepared in a rectangular glass mold (25 x 2 x 2 mm). The new cements were light-activated with a 550 mW/cm(2) lamp for 80 seconds on both the top and bottom surfaces. The auto-cured cement was allowed to set according to manufacturer's directions. Half the specimens were tested immediately after curing while the other half were stored in distilled water at 37 degrees C for 30 days. A three-point bending test was performed using an Instron at a crosshead speed of 1 mm/min. The results were analyzed by analysis of variance and Scheffé tests ( p < 0.05) to examine the effect of specimen age and storage condition. RESULTS: RelyX ARC exhibited a significantly higher flexural strength compared with Calibra and Panavia F when tested immediately. The standard cement, C/B Metabond, deformed and did not fracture at the immediate test time. After storage, the flexural strength had significantly improved from the immediate test time for Calibra, Cement-It, Panavia F, and C/B Metabond. However, there were no significant differences in the flexural strength among the cements when tested after 30 days in water at 37 degrees C. CONCLUSION: Immediately after curing, these new adhesive resin cements are not equivalent, as evidenced by the significant variability in the measured flexural strength. The distinctions among the cements diminish after aging in water, which may be due to residual polymerization or a plasticizing effect from water absorption. CLINICAL SIGNIFICANCE: When light-cured, all the new adhesive resin cements have greater early strengths than the auto-cured cement; however, the wide variation in immediate bending strength suggests that some cements may be more appropriate for use in high-stress clinical situations such as resin-bonded fixed partial dentures.
Subject(s)
Resin Cements/chemistry , Absorption , Bisphenol A-Glycidyl Methacrylate/chemistry , Boron Compounds/chemistry , Composite Resins/chemistry , Dental Bonding , Dental Stress Analysis/instrumentation , Humans , Materials Testing , Methacrylates/chemistry , Methylmethacrylates/chemistry , Plasticizers/chemistry , Pliability , Polyethylene Glycols/chemistry , Polymers/chemistry , Polymethacrylic Acids/chemistry , Stress, Mechanical , Temperature , Time Factors , Water/chemistryABSTRACT
Bar-and-clip attachments for dental implants are a common and versatile device for improving the retention and stability of a removable prosthesis. Manufactured clips may be unsubstantial and may not always fit or provide the desired amount of retention for the bar. The purpose of this article is to describe a technique for custom fabrication of clip attachments. The wax pattern of the clips is fabricated and then cast in dental gold alloy. The gold clips are then cut to an appropriate size that will allow for a variety of clinical applications.
