Macromolecular leakage beneath full cast crowns. Part I: The diffusion of lipopolysaccharide and dextran

A Comparison Between Screw- and Cement-Retained Implant Prostheses. A Literature Review

Implant-supported restorations can be secured to implants with screws (screw-retained), or they can be cemented to abutments which are attached to implants with screws (cement-retained). This literature review discusses the advantages and disadvantages of each method of retention from different aspects. These aspects include: ease of fabrication and cost, esthetics, access, occlusion, retention, incidence of loss of retention, retrievability, clinical prosthesis fit, restriction of implant position, effect on peri-implant tissue health, provisionalization, immediate loading, impression procedures, porcelain fracture, and clinical performance. Peer-reviewed literature published in the English language between 1955 and 2010 was reviewed using PubMed and hand searches. Since the choice of using either method of retention is still controversial, this review article offers some clinical situations that prefer one method of retention over the other. The review demonstrated that each method of retention has certain advantages and disadvantages; however, there are some clinical situations in which it is better to select one method of retention rather than the other.

Cytotoxicity and sealing properties of four classes of endodontic sealers evaluated by succinic dehydrogenase activity and confocal laser scanning microscopy

The objectives of this study were to evaluate the cytotoxicity and sealing properties of four classes of endodontic sealers (PCS/Kerr, RoekoSeal/Roeko, TopSeal/Dentsply, and EndoREZ/Ultradent). For cytotoxicity testing (MTT method), the materials were either placed immediately in contact with cultured cells or 24 h after setting, then evaluated at three subsequent time points (24 h, 48 h, or 1 wk). For the leakage study, extracted human roots were obturated with acrylic cones and sealers and immersed for 48 h into rhodamine-labeled lipopolysaccharide. The roots were then observed under a confocal laser scanning microscope to estimate (semiquantitatively) the presence of the rhodamine-lipopolysaccharide (LPS) inside the canal. The results showed that cytotoxicity generally increased with time, and that most materials pose significant cytotoxic risks, particularly in the freshly mixed condition. Further, all materials showed significant leakage although there was large variation among teeth. Overall, the silicon-based material (Roeko Seal) was less cytotoxic and more effective in sealing root canals against LPS leakage than other materials.

Macromolecular leakage beneath full cast crowns: A two-year in vitro investigation

STATEMENT OF PROBLEM

Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials such as lipopolysaccharides (LPSs) or cell wall materials that have been shown to provoke inflammatory reactions in the dental pulp.

PURPOSE

This investigation evaluated the leakage (diffusion) of fluorescently labeled LPS and dextran beneath cast-gold crowns luted with 3 cements.

MATERIAL AND METHODS

Thirty extracted molars were prepared for crowns. Ten crowns with access ports (facial or lingual) were cast in gold and luted with zinc phosphate, glass ionomer, and an adhesive resin cement onto their preparations. Teeth and crowns with filters inserted into the ports were immersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) and evaluated for leakage every month for 24 months. Filters were retrieved and analyzed with fluorescent microscopy.

RESULTS

All filters retrieved from crowns luted with zinc phosphate, glass ionomer, and adhesive resin cements demonstrated no detectable leakage and were negative for both FITC-dextran and TRITC-LPS for all evaluation periods.

CONCLUSION

For the 24 months of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of LPS and dextran to the level of the access ports.

Review of dental materials citations: Part B, July to December 1995

OBJECTIVE

A lag of many months occurs between journal issue publication and updates to electronic databases. The objective of this literature analysis was to identify and categorize all of the dental materials citations in biomedical journals that were published from July 1995 through December 1995.

METHODS

Seventeen primary and 51 secondary journals were searched using their tables of contents to detect and record dental materials publications from July to December of 1995. Those journals that were typically rich in dental materials articles were classified as primary ones. Citations were categorized into 17 topics and divided into subsections. The review excluded case reports, most literature related primarily to dental implants, and most articles on biomedical materials used outside of the field of general dentistry.

RESULTS

The greatest number of citations was related to topics of dentin bonding and resin-based restorative filling materials (composites and glass ionomers). There was no major change in the number of dental materials publications per year reported from 1993 (n = 786) to 1995 (n = 751).

SIGNIFICANCE

This citation list provides a comprehensive resource for use by academicians and researchers to bridge the gap between initial publication and access to electronic searching methods for major databases.

Macromolecular leakage benath full cast crowns. Part II: The diffusion of lipopolysaccharide and dextran

Fifteen extracted molars were prepared for crowns. Crowns with access ports (one facial, one lingual) were cast in gold. Teeth and crowns luted with provisional cement with filters inserted into the ports were immersed in a solution of labeled macromolecules (FITC-dextran, TRITC-LPS) and evaluated for leakage. Filters were retrieved and analyzed by use of fluorescent microscopy. Leakage of LPS and dextran occurred as early as 2 weeks beneath crowns luted with a provisional cement (NoGenol).