Dental materials: 1995 literature review

Pin-Retained Amalgam: An Intricate Restorative Case Study

Amalgam has made dental restorations more manageable, especially in difficult cases, due to its strength, durability, and relatively low cost. There can be pros and cons of each dental material depending on which class of cases it is applied or not applied for, depending on the patient's need, and, of course, the dentist's choice. These materials are used frequently for their hardness and durability and are ideal for extensive restoration procedures. On the other hand, composite resins are considered to be more aesthetic for the profitable areas where esthetics are more important. In contrast, glass ionomer cement is considered to be ideal for low-stress-bearing areas. The following case report of pin-retained amalgam restoration presents an example of its application in practical situations and the factors that must be considered to justify the use of this material against others. This paper explains various factors in considering pin-retained amalgam restorations and the procedure for a better and positive outcome.

Surveillance study on the application of titanium and its alloys to removable dental prostheses

This review describes individual studies of removable dental prostheses, evaluated their performance and clinical applicability for the proposal to expand health insurance coverage of titanium and its alloys to removable dental prostheses. Titanium and its alloys have become clinically applicable as prosthetic materials by improving dental casting systems. They have high biosafety and good mechanical properties, are excellent substitutes for the silver-palladium-gold alloys for casting, and are highly useful for removable dental prostheses. Therefore, the introduction of health insurance coverage for removable dental prostheses made of titanium and its alloys is worthy of consideration.

Massive Transformation in Titanium-Silver Alloys and Its Effect on Their Mechanical Properties and Corrosion Behavior

In order to investigate the relationship between phase/microstructure and various properties of Ti–xAg alloys, a series of Ti–xAg alloys with Ag contents ranging from 5 to 20 wt% were prepared. The microstructures were characterized using X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All of the Ti–xAg alloys showed a massive transformation from the β-Ti to α_m phase, which has a different crystal structure from that of the matrix phase, but it has the same composition as the matrix α-Ti phase. As a result of solid-solution strengthening of α-Ti and massive transformation phase, the Ti–xAg showed better mechanical properties than the commercially pure titanium (cp-Ti). Electrochemical results showed that the Ti–xAg alloys exhibited improved corrosion resistance and oxidation resistance than cp-Ti.

Influence of Er:YAG laser surface treatment and primer application methods on microtensile bond strength self-etching systems

OBJECTIVE

The aim of this in vitro study was to evaluate how surface preparation and primer application technique can influence the microtensile bond strength of self-etching system.

BACKGROUND DATA

One of the possible applications of dental lasers includes increasing the quality of bond strength.

MATERIALS AND METHODS

12 extracted, sound human molars were ground flat to expose occlusal dentin and were then divided into six groups (G1-G6)(n = 30-36) according to surface preparation and primer application (active or passive): G1-diamond bur (DB) + active primer (AP); G2-DB + passive primer (PP); G3-Er:YAG laser (EL) + AP; G4-EL + PP; G5-#600-grit paper disc (PD) + AP; G6-PD + PP. After adhesive procedure, 5-mm high composite buildups were created with Z 250. After storage in water at 37 degrees C for 24 h, teeth were vertically sectioned into serial 1- mm2 sticks. Samples were tested for tension in an Instron machine at 0.5 mm/min. Nine additional molars were prepared to morphological analysis. Regular grit diamond bur, Er:YAG laser, or #600-grit SiC paper was used for SEM observations of dentin surfaces of each group before and after treatment with self-etching primers. Microtensile data were submitted to statistical analysis.

RESULTS

G1-43.85 +/- 9.60 MPa; G2-24.28 +/- 8.90 MPa; G3-24.11 +/- 4.05 MPa; G4-23.30 +/- 4.21 MPa; G5-55.64 +/- 8.50 MPa; G6-56.45 +/- 12.05 MPa.

CONCLUSIONS

(1) Er:YAG laser and diamond burs are able to create distinct smear layers; however the resistance of dentin/adhesive interface is similar. In this way, we can use both instruments clinically without diminishing bond strength; (2) the #600-grit sandpaper disc least affects resistance and is highly recommended for in vitro studies to achieve standard preparation of dentinal surface; (3) active primer application is the method most recommended, despite the type of dentin preparation instrument used.

Assessment of the cytotoxicity of photocrosslinked dextran and hyaluronan-based hydrogels to vascular smooth muscle cells

The cytotoxicity of polysaccharide-based hydrogels and solutions was studied in vitro after 48h of indirect exposure of the materials with vascular smooth muscle cells. Dextran and/or hyaluronan were derivatized using glycidyl methacrylate, and hydrogels were formed in the presence of photoinitiators and ultraviolet radiation in multiwell inserts to avoid direct contact with cell monolayers. Observation of cell morphology indicated that dextran hydrogels, a blend of non-derivatized hyaluronan into dextran hydrogel. and a hyaluronan solution were highly cytocompatible. However, hydrogels made of derivatized hyaluronan were cytotoxic when compared to unexposed sham controls that contained multiwell inserts but no hydrogels. Results from quantitative assays for proliferation and viability corroborated the qualitative observations, and scrape wound assays revealed a significant increase in smooth muscles cell migration/proliferation after indirect exposure to several of the polysaccharide-based materials. Results from this study demonstrate that hydrogels made of dextran and hyaluronan solution show good cytocompatibility in vitro. making these degradable matrices interesting candidates for drug delivery purposes.

Dental materials: 1997 literature review

This review of the published literature on dental materials for the year 1997 has been compiled by the Dental Materials Panel of UK. It continues a series of annual reviews started in 1973. Emphasis has been placed upon publications, which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, ceramometallic restorations and resin-bonded bridges, ceramics, denture base resins and soft lining materials, impression materials, dental implant materials, orthodontic materials, biomechanics and image processing, resin composites, and casting investment materials and waxes). Three hundred and thirty three articles have been reviewed.

Surface chemistry of a high-copper dental amalgam

In amalgam, mercury is intended to take the form of stable intermetallic compounds. Any mercury leakage must therefore come from free mercury not involved in such compounds. Thus, a knowledge of the exact surface chemistry of dental amalgam is necessary if this phenomenon is to be understood. From XPS and EDS analyses, a model of the surface chemistry of amalgam is proposed which fully characterizes all the phases that are present. The data show the surface to have a composition different from that of the bulk, being comprised of a hydrocarbon deposit and adsorbed water covering the intermetallic phase gamma2 (Sn(6-8)Hg), tin (iv) oxide, and mercury in a free state. After amalgamation, the amount of mercury at the surface decreases with time and eventually attains a constant concentration, where it is all involved in the gamma2 phase, leaving no free mercury. A model is proposed for the surface of amalgam and the changes in this model with time.

New developments in jewellery and dental materials

This communication reviews the latest alloys introduced in the fields of jewellery and dental prostheses. For this we have scanned current patents and others to which we have access, and it is evident that, although not always correctly used, the words "antiallergic", "hypoallergic", "non-allergic", "to avoid allergies", etc., now appear frequently, indicating manufacturers' awareness of the problems that nickel can cause. On the other hand, the problems that may be associated with other sensitizing metals, such as cobalt and palladium, are not yet addressed.

Dental materials: 1996 literature review

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.

Dental materials citations: Part A, January to June 1997

OBJECTIVE

A search was conducted in biomedical journals published from January 1997 to June 1997 to identify all dental materials publications and sort them into major categories.

METHODS

Tables of contents for 79 journals for the period of January to June, 1997 were inspected and divided into 17 categories. Citations were analyzed by both frequency in journals and in categories, as well as compared to frequencies for previous years.

RESULTS

A total of 445 citations were detected in 79 journals for the period January 1997 to June 1997. Certain journals (n = 19) demonstrated a higher citation frequency (> or = 10 citations for 6 months) and represented 77.8% of all citations. The greatest number of citations continued to involve bonding (n = 97), resin-based restorative materials (composites; glass ionomers) (n = 95), prosthodontic materials (n = 51), and pulp protection/luting materials (n = 48). Frequencies by category were very similar to those for the last four years.

SIGNIFICANCE

The compiled literature citations provide a supplement for researchers and academicians seeking information in existing electronic databases.