Analysis of resin tags formation in root canal dentine: a cross sectional study.

Aim: To evaluate the length, density and quality of resin tags formed by penetration of various types of adhesive systems into dentinal tubules at various cross section levels of the root canal in correlation to the density of dentinal tubules.

Methodology: Thirty mandibular premolars were instrumented and fibre posts were inserted with three different adhesive systems with and without activator: etch & rinse XP Bond and XP Bond/Self Cure Activator; self-etch (two-step) AdheSE and AdheSE/AdheSE DC Activator and self-etch (one-step) Hybrid Bond and Hybrid Bond/Hybrid Brushes. The resin tags were evaluated from slices obtained from sections perpendicular to the long axis of the teeth at 3, 6, and 9 mm from the root apex under a Confocal Laser Scanning microscope.

Is the soft-start polymerisation concept still relevant for modern curing units?

Shrinkage stress, degree of cure and mechanical properties are contradicting properties, forcing to a compromise between an adequate curing and low stress at the interface tooth-restoration. The purpose of this study was to quantify this relations for a micro-hybrid composite, by analysing in real time the development of degree of cure at depths of 2 and 6 mm, shrinkage stress and curing time until gelation, as well as the variation of micro-mechanical properties with depth, after curing with 13 regimes of one halogen and two light-emitting diode (LED) curing units. A nano-dynamic mechanical test was additionally performed on selected regimes (Ramp, Pulse and Fast Cure) of the same curing unit.

Polymerization composite shrinkage evaluation with 3D deformation analysis from microCT images.

Objectives: The aim of this study was to develop a method to experimentally determine and visualize the direction and amount of polymerization shrinkage.

Methods: We modified a composite to include 1.5 wt% traceable glass beads.

Metabolism of TEGDMA and HEMA in human cells.

Previous in vivo studies have shown that the comonomers triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) from dental materials can be metabolised to CO(2) by two postulated pathways: an epoxide and a valine pathway. In the epoxide pathway the formation of pyruvate is postulated and in valine pathway the formation of l-malate. The aim of this investigation was to quantify the formation of the intermediates pyruvate and l-malate to show which pathway may be preferred in A549 cells.

Development, methodology and potential of the new Universal Visual Scoring System (UniViSS) for caries detection and diagnosis.

Given the limitations of adjunct caries detection and diagnostic tools, e.g., imperfect validity and reproducibility, as well as the difficulties in controlling all possible confounding factors, the need for an objective visual caries detection and diagnosis system has become evident.

Are pit and fissure sealants needed in children with a higher caries risk?

The aim of this cross-sectional study was to analyse the preventive need of pit and fissure sealants (PFS) in a German population with a relatively high caries risk. The study involved 311 8- to 12-year-old children from the Ennepe-Ruhr District in North Rhine-Westphalia, Germany. Caries experience was scored according to WHO (1997) and ICDAS II criteria.

Eluted substances from unpolymerized and polymerized dental restorative materials and their Nernst partition coefficient.

Objectives: Components released from resin-based dental materials are important factors in the assessment of the biocompatibility of these materials. The study was performed to investigate the elution of substances from unpolymerized and polymerized composites (Tetric=TET; Arabesk=ARA), ormoceres (Admira)=ADM; Definite=DEF) and the compomere (Hytac=HYT).

Methods: Specimens were polymerized and immersed in either water or methanol.

Quantitative determination of TEGDMA, BHT, and DMABEE in eluates from polymerized resin-based dental restorative materials by use of GC/MS.

This study investigated the leaching of ingredients from several commercial dental composite resins cured with LED, and immersed in methanol or water for 24 h, respectively. The composites used were: Admira Dentin (VOCO), Artemis Schmelz (Enamel) (Ivoclar Vivadent), Els extra low shrinkage (Saremco Dental), Filtek Supreme XT Dentin (3 M ESPE), Gradia Direct (GC), Venus & Venus flow (Heraeus Kulzer), and XRV Herculite Prodigy Enamel (Kerr). From each dental composite four specimens with defined structure and 100-mg net weight were made.

Real-time xCELLigence impedance analysis of the cytotoxicity of dental composite components on human gingival fibroblasts.

Objectives: Aim of this study was by continuous monitoring to assay the proliferative capacity of human gingival fibroblasts (HGFs), to investigate cytotoxicity of the most common monomers/comonomers in dental resin composites: bisphenol-A-glycidylmethacrylate (BisGMA), hydroxyethylenemethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), and urethanedimethacrylate (UDMA) in HGFs during 24h exposure using the xCELLigence system.

Methods: xCELLigence cell index (CI) impedance measurements were performed according to the instructions of the supplier. HGFs were resuspended in medium and subsequently adjusted to 400,000, 200,000, 100,000, and 50,000 cells/mL.

Volatile methacrylates in dental practices.

Purpose: In recent years, an increase of occupational respiratory diseases, such as asthma caused by methacrylates, has been observed in dental personnel. In this study, the exposure of dental personnel to various volatile methacrylates was investigated.

Materials And Methods: The air levels of methacrylates were measured during filling treatment while bonding agents were used in 4 dental practices in Munich, Germany.

Development and application of a simplified sample preparation method for determination of TEGDMA and related metabolites.

Analysis of biological samples obtained from in vivo experiments can be often challenging. In general it is not possible to apply the commonly used matrices that are necessary for the experiments to the desired analysis systems without further conditioning or sample purification steps. Besides possible adverse effects for instruments, interference between analytes and matrices can affect the correct measurement of analytes.

Effect of different bonding agents on prevention of enamel demineralization around orthodontic brackets.

Introduction: Demineralization around the bracket is an undesired side effect of orthodontic treatment. The aim of this in-vitro study was to evaluate the efficacy of 5 bonding agents to prevent enamel demineralization. Two quantification methods were used.

In vitro stability of methylmethacrylic acid, TEGDMA and HEMA exposed to esterases.

Objectives: Comonomers used in dental restorative materials, e.g. triethylenglycoledimethacrylate (TEGDMA), hydroxyethylmethacrylate (HEMA) and methylmethacylic acid (MMA) are methacrylic acid esters.

Macro-, micro- and nano-mechanical investigations on silorane and methacrylate-based composites.

Objectives: Cationic ring-opening monomers with a reduced shrinkage stress--silorane--are being used as matrix resins for recently introduced dental composites. Since shrinkage and mechanical properties are generally opposite properties, our study aimed to analyze the mechanical behavior of the silorane-based composite in comparison to six homologous clinical successful methacrylate-based composites.

Methods: Mechanical properties were determined at macro- (strength and modulus of elasticity), micro- (hardness, modulus of elasticity and creep) and nano-scale (nano-dynamic-mechanical parameters: complex, storage, loss modulus and tandelta) after storing the materials for 24 h in distilled water as well as after aging (thermocycling and storing for 4 weeks in water, saliva or alcohol).

Investigations on mechanical behaviour of dental composites.

Since a direct comparison of composites efficacy in clinical studies is very difficult, our study aimed to analyse in laboratory tests under standardised and simulated clinical conditions a large variety of commercial composite materials belonging to eight different materials categories. Thus, 72 hybrid, nano-hybrid, micro-filled, packable, ormocer-based and flowable composites, compomers and flowable compomers were compared in terms of their mechanical behaviour. Flexural strength (FS), flexural modulus (FM), diametric tensile (DTS) and compressive strength (CS) were measured after the samples had been stored in water for 24 h at 37 degrees C.

Evaluation of the mechanical properties of dental adhesives and glass-ionomer cements.

Adhesives and lining/base materials should relieve the stresses concentrated at the tooth/restoration interface. The study aimed at comparing the mechanical properties of eight adhesives and six glass-ionomer cements (GICs). The adhesives were applied on dentin disks, whereas 2 mm x 3 mm x 2 mm GICs specimens were prepared in a teflon mold.

The toxicokinetics and distribution of 2-hydroxyethyl methacrylate in mice.

The cytotoxicity of dental composites has been attributed to the release of residual monomers from polymerized resin-based composites due to the degradation processes or the incomplete polymerisation of materials. 2-Hydroxyethyl methacrylate (HEMA) is one of the major components released from dental resin-based composites. It was shown in vitro that HEMA was released into the adjacent biophase from such materials during the first days after placement.

Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model.

Aim: To assess the antimicrobial efficacy of aqueous (1.25-20 microg mL(-1)) and gaseous ozone (1-53 g m(-3)) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model.

Methodology: Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono-species biofilms in root canals for 3 weeks.

Spatial and cure-time distribution of dynamic-mechanical properties of a dimethacrylate nano-composite.

Objective: The purpose of this study was to evaluate a nano-filled dental composite, with varying cure irradiation-time, in terms of the spatial distribution of dynamic-mechanical properties determined at nanometre scale and the resultant distinction between filler, matrix and inter-phase regions.

Materials And Methods: Specimen groups (n=5) of the composite Filtek Supreme XT were cured in 2mm deep molds for 5, 10, 20 and 40s, and stored for 24h in distilled water at 37 degrees C. Properties were measured at 2mm depth, on the lower specimen surfaces.

Clinical performance of the posterior composite QuiXfil after 3, 6, and 18 months in Class 1 and 2 cavities.

Objective: This longitudinal randomized controlled clinical trial evaluated direct composite restorations for clinical acceptability of posterior restoratives in single- or multisurface cavities and provided a preliminary survey of the 3-, 6-, and 18-month results.

Method And Materials: Three clinicians placed 46 QuiXfil (Xeno III; Dentsply DeTrey) and 50 Tetric Ceram (Syntac Classic; Vivadent) composite restorations in stress-bearing Class 1 and 2 cavities in first or second molars (43 adult patients). Clinical evaluation was performed at baseline and after 3, 6, and 18 months by 2 other clinicians using modified US Public Health Service criteria.

Excretion of dental resin monomers and metabolic intermediates via urine in guinea pigs.

Objective: Monomers like BisGMA (Bisphenol-A-glycidyldimethacrylate) and comonomers like TEGDMA (triethyleneglycoldimethacrylate) are used in dental restorative materials in order to build up the three-dimensional network of filling materials. Since earlier investigations revealed uptake and subsequent metabolism of unpolymerized remainders of (co)monomers, the present experiment investigates the metabolic urine pattern of guinea pigs (n=4) after application of TEGDMA or BisGMA (each dose=0.02 mmol/kg body weight=100%), respectively.

Three-year results of a randomized controlled clinical trial of the posterior composite QuiXfil in class I and II cavities.

This longitudinal randomized controlled clinical trial evaluated direct composite restorations for clinical acceptability as posterior restoratives in single- or multi-surface cavities and provides a survey of the 3-year results. Three dentists placed 46 QuiXfil (Xeno III) and 50 Tetric Ceram (Syntac Classic) composite restorations in stress-bearing class I and II cavities in first or second molars (43 adult patients). Clinical evaluation was performed at baseline and after 3 years by two other dentists using modified US Public Health Service criteria.

Clinical performance of a new laser fluorescence device for detection of occlusal caries lesions in permanent molars.

Objectives: To determine the clinical performance of a laser fluorescence device (DIAGNOdent pen, KaVo) to discriminate between different occlusal caries depths (D(0)-D(1-4); D(0-2)-D(3,4)) in permanent molars.

Methods: In this prospective, randomized two-centre-study 120 sound/uncavitated carious sites in 120 patients were measured after visual and radiographic caries assessment. In cases of operative intervention (n=86), the lesion depths after caries removal were recorded (reference).

SEM and microleakage evaluation of the marginal integrity of two types of class V restorations with or without the use of a light-curable coating material and of polishing.

Objectives: To evaluate the marginal integrity of class V restorations through an SEM observation and a microleakage test.

Methods: Teeth with class V cavities were restored with either a flowable composite (n=20) or a glass ionomer cement (GIC) (n=20). Ten restorations in each group were immediately polished.

Effect of ozone gas application on the mechanical properties of dental adhesives bonded to dentin.

Objectives: To assess the effect of ozone gas on the mechanical properties of different classes of dental adhesives.

Methods: Extracted molars were sectioned perpendicularly to their long axis for obtaining dentin slices to be bonded with one of the following adhesives: Prime&Bond NT (Dentsply), Excite (Ivoclar-Vivadent), Syntac/Heliobond (Ivoclar-Vivadent) and Silorane System Adhesive (3 M-ESPE). Prior to bonding, the slices were sectioned in two halves: one was treated with ozone gas for 120 s (4.