Biological aspects of modern dental composites.

Biological evaluation of resin-based dental composites has traditionally been based on in vitro endpoint tests with different methods to determine loss of cell viability and cell morphology changes after exposure to the material or monomer constituents. The data reveals a potential for biological effects, but clinical relevance of such data is limited. Positive allergy tests and allergic clinical reactions to dental monomers are observed in dental personnel and patients.

Shear bond strength of resin bonded zirconia and lithium disilicate - effect of surface treatment of ceramics and dentin.

The purpose of the study was to investigate the effect of ceramic surface pretreatment, effect of resin cement and dentin surface roughness on shear bond strength. Zirconia rods ( = 140) were randomly assigned to air born particle abrasion with aluminum oxide (AlO) or hot etching with potassium hydrogen difluoride (KHF). Lithium disilicate rods (LDS;  = 50) etched with hydrofluoric acid served as reference material.

The effect of minimally invasive sacroiliac joint fusion compared with sham operation: study protocol of a prospective double-blinded multicenter randomized controlled trial.

Background and purpose - The sacroiliac joint is increasingly recognized as a cause of pain in 15-30% of patients with low back pain. Nonoperative management is not always successful and surgical treatment with fusion of the joint is increasingly recommended. According to the literature, minimally invasive fusion reduces pain and improves function compared with nonoperative treatment.

The influence of the resin-based cement layer on ceramic-dentin bond strength.

The purpose of the study was to measure the cement thickness obtained when ceramic rods were luted to dentin and to analyze the relation between cement thickness and the previously published tensile bond strength of similar test specimens. In addition, the ISO standard 4049:2019 method was used to determine the film thickness of the used cements. Zirconia (n = 100) and lithium disilicate (n = 50) rods were cemented to bovine dentin using one of five different resin-based cements.

Dentin to dentin adhesion using combinations of resin cements and adhesives from different manufacturers - a novel approach.

Aims: The aims of this study were to present a novel method to analyse dentin bond strength and to evaluate the bond strength of combining adhesive systems and resin cement from different manufacturers.

Methods: Human wisdom teeth were ground flat to the dentin on parallel surfaces and axially cut into two parts. Dentin cylinders (Ø 3 mm) were drilled from one half of each tooth.

Effect of thermal cycling on temperature changes and bond strength in different test specimens.

To investigate temperature changes in various test specimens during thermal cycling and to evaluate difference in micro-tensile repair bond strength in specimens cut from the inner or the outer area of composite blocks after thermal cycling. Four rectangular composite blocks of various sizes were fabricated, and thermocouples placed in the centre of the specimens or halfway from the surface to the centre. Composite cylinders were made on ground flat extracted molars, as intended for micro-tensile and shear bond testing, with a thermocouple placed at the centre of the cylinder radius between composite and dentin.

Does radiopaque cement conceal periprosthetic bone loss around femoral stems?

Background: Periprosthetic bone remodelling may increase fracture risk and deplete bone stock around hip implants. These changes are in part caused by implant design, advocating an early evaluation of bone remodelling properties of new implants. This can be done by repeated dual-energy x-ray absorptiometry (DXA) measurements.

The dental monomer HEMA causes proteome changes in human THP-1 monocytes.

Resin-based biomaterials are widely used in medical and dental treatment, and both clinicians and patients are exposed to the materials. The knowledge of toxicity is mainly based on in vitro studies at exposure concentrations that induce cell death. However, severe cell damage and cell death signaling may overshadow essential cellular events caused by a possible toxicant.

Digital evaluation of marginal and internal fit of single-crown fixed dental prostheses.

The present study used a new, digitized version of the impression replica technique, namely the dual-scan technique, to evaluate the adaptation of single-crown fixed dental prostheses (FDPs). Scans of the bare master model and of the master model with a silicone layer representing the cement layer were superimposed and analyzed using designated software. Single crowns produced using the lost-wax metal casting technique were included.

Optimizing quality and safety of dental materials.

This paper discusses aspects of quality and safety improvement of the most commonly used dental restorative materials, the resin-based composites. From a patient's perspective, long-lasting resin-based restorations without complications are important. Recurrent caries and fracture are the most common causes for restoration failures.

Higher cartilage wear in unipolar than bipolar hemiarthroplasties of the hip at 2 years: A randomized controlled radiostereometric study in 19 fit elderly patients with femoral neck fractures.

Background and purpose - The use of unipolar hemi-arthroplasties for femoral neck fractures is increasing in some countries due to reports of higher reoperation rates in bipolar prostheses. On the other hand, it has been proposed that bipolar hemiarthroplasties have clinical advantages and less cartilage wear than unipolar hemiarthroplasties. We compared cartilage wear between bipolar and unipolar hemiarthroplasties using radiostereometric analyses (RSA), in patients aged 70 years or older.

Internal fit of three-unit fixed dental prostheses produced by computer-aided design/computer-aided manufacturing and the lost-wax metal casting technique assessed using the triple-scan protocol.

Suboptimal adaptation of fixed dental prostheses (FDPs) can lead to technical and biological complications. It is unclear if the computer-aided design/computer-aided manufacturing (CAD/CAM) technique improves adaptation of FDPs compared with FDPs made using the lost-wax and metal casting technique. Three-unit FDPs were manufactured by CAD/CAM based on digital impression of a typodont model.

Effect of curing and silanizing on composite repair bond strength using an improved micro-tensile test method.

To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed. Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane.

Internal fit of single crowns produced by CAD-CAM and lost-wax metal casting technique assessed by the triple-scan protocol.

Statement Of Problem: Whether single crowns produced by computer-aided design and computer-aided manufacturing (CAD-CAM) have an internal fit comparable to crowns made by lost-wax metal casting technique is unknown.

Purpose: The purpose of this in vitro study was to compare the internal fit of single crowns produced with the lost-wax and metal casting technique with that of single crowns produced with the CAD-CAM technique.

Material And Methods: The internal fit of 5 groups of single crowns produced with the CAD-CAM technique was compared with that of single crowns produced in cobalt-chromium with the conventional lost-wax and metal casting technique.

Silanising agents promote resin-composite repair.

Objective: The aim of this study was to investigate the effect of silane in the repair of old and new resin-composite restorations.

Method: Part 1: repair of old composite was performed on 60 resin-composite substrates that were 6 years old and were made of six different brands of composite. Three experiments were performed.

element release and biological aspects of base-metal alloys for metal-ceramic applications.

The aims of this study were to investigate the release of element from, and the biological response to, cobalt-chromium alloys and other base-metal alloys used for the fabrication of metal-ceramic restorations. Eighteen different alloys were investigated. Nine cobalt-chromium alloys, three nickel-chromium alloys, two cobalt-chromium-iron alloys, one palladium-silver alloy, one high-noble gold alloy, titanium grade II and one type III copper-aluminium alloy.

Low wear, high stability - promises of success in a moderately cross-linked cup?

Purpose: Cross-linking has proven effective in reducing polyethylene wear in total hip replacements. However, increasing the amount of cross-links will impair other mechanical properties of the polyethylene. The optimal threshold of crosslinking has still not been established.

TEGDMA and filler particles from dental composites additively attenuate LPS-induced cytokine release from the macrophage cell line RAW 264.7.

Objectives: Due to incomplete curing and material degradation, cells in the oral cavity may be exposed to monomers and filler particles from dental composite fillings. The objective of the present study was to investigate if combined exposures to particles and a methacrylate monomer from composite fillings resulted in additive effects on the macrophage immune response.

Material And Methods: Two filler particles, Nanosilica (12 nm) and Quartz (1 μm), were studied at concentrations 0.

More than 50% reduction of wear in polyethylene liners with alumina heads compared to cobalt-chrome heads in hip replacements: a 10-year follow-up with radiostereometry in 43 hips.

Background And Purpose: Excessive wear of acetabular liners in hip replacements may lead to osteolysis and cup loosening. Different head materials are currently used. We measured differences in wear between alumina and cobalt-chrome heads with the same polyethylene liner.