Flowability of composites is no guarantee for contraction stress reduction.

Objectives: The purpose of this study was to measure the contraction stress development of three flowable resin-composite materials (Grandio Flow, VOCO GmbH, Cuxhaven, Germany; Tetric Flow, Ivoclar Vivadent, Schaan, Liechtenstein; Filtek Supreme XT Flowable Restorative, 3M ESPE, ST. Paul, MN, USA) and an universal micro-hybrid composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) during photopolymerization with a halogen curing light, using a novel stress-measuring gauge.

The influence of tip geometry and distance on light-curing efficacy.

This study investigated the influence of the light guide shape on the polymerization efficacy of a light-activated resin-based composite cured with LED units as a function of the distance between the tip and the restoration. Two different LED units, each with different light guides and shapes, were used. Their ability to cure a single restorative material was investigated.

Influence of thickness on color in multi-layering technique.

Objectives: The aim of the study was to evaluate the influence of layer thickness on the final color for different shade and opacity composite combinations in a laboratory set-up simulating a 2-layer stratification technique.

Methods: Resin disks of different thicknesses were made. From one composite system (Point4, Kerr Co.

Assessment of polymerization contraction stress of three composite resins.

Objectives: The purpose of this study was to measure the development of contraction stress of three composite resin restorative materials during photo-polymerization: a micro-hybrid composite (Filtek Z250, 3M ESPE, St. Paul, MN, USA); a nano-filled composite (Filtek Supreme, 3M ESPE, St. Paul, MN, USA); and a low-shrinkage composite (AElite LS, Bisco Inc.

Spectrophotometric and visual shade measurements of human teeth using three shade guides.

Purpose: To compare spectrophotometric vs. visual color identification of tooth shade on the basis of three different commercially available shade guides.

Methods: On 54 subjects, two operators (with >10 years experience) independently selected the best match of the middle third of one of the patient's upper central incisors, using consecutively three shade guides (Vita Lumin Vacuum, Chromascop, Vita 3D Master).

In vivo enamel fluid movement.

The aim of this study was to visualize fluid movement through dental enamel in vivo. Fifty permanent upper central incisors, from subjects aged 10-70 yr, and 5 permanent central just-erupted incisors, from subjects aged 6-7 yr, were included in the study. An impression was obtained by vinyl polyxiloxane, and replicas were then obtained by polyether impression material.

A clinical trial of Empress II porcelain inlays luted to vital teeth with a dual-curing adhesive system and a self-curing resin cement.

Purpose: The aim of the study was to clinically evaluate Empress II inlays cemented with a dual-curing bonding agent and a self-curing luting system.

Materials And Methods: Forty patients were selected to receive one Empress II inlay. Empress II is a heat-pressed glass ceramic containing lithium disilicate and lithium orthophosphate crystals, purported to provide higher stress resistance and improved strength.

Effect of the seating pressure on the adhesive bonding of indirect restorations.

Purpose: To evaluate the effect of two different techniques of seating pressure application on the adhesive-dentin bond of indirect restorations.

Methods: Eight non-carious human third molars were randomly divided in two treatment groups (four teeth each). Cylindrical composite blocks were luted with a resin cement (Panavia F).

Effect of dentin adhesives used as sealers and provisional cementation on bond strength of a resin cement to dentin.

Purpose: To evaluate the effects of dentin adhesives employed as resin sealers and provisional cementation on the bond strengths of a resin cement to dentin.

Methods: A two-step etch-and-rinse adhesive (Excite DSC--Group 1) and two-step self-etch adhesive (AdheSE--Group 2) were applied to exposed dentin surfaces prepared from human molars (N=4). Water was used instead of a resin sealer in control Groups 3 and 4.

The effect of application sustained seating pressure on adhesive luting procedure.

Objectives: To evaluate the effect of short versus long application seating pressure on the bond strength of resin blocks, luted with a dual-cured resin cement (Panavia F) to pre-coated or non pre-coated dentin with an hydrophobic light-cured adhesive (Clearfil Protect Bond).

Methods: Sixteen non-carious human third molars were randomly divided into six Groups (four teeth each). Cylindrical composite blocks were luted with Panavia F (Group Ia) and with Clearfil Protect Bond with Panavia F (Group IIa) and seating pressure was applied for 5s.

Advances in glass-ionomer cements.

This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.

In situ transformation of glass-ionomer into an enamel-like material.

Purpose: To assess the nature of clinically detectable alterations in glass-ionomer after long-term clinical service.

Methods: In addition to clinical macro pictures, SEM was carried out on replicas and on two sectioned primary molars SEM-EDAX analysis was performed to determine chemical transformation in the glass-ionomer. Also with SEM-EDAX, the composition was determined of a partially removed half-year old sealant.

Stress distributions in adhesively cemented ceramic and resin-composite Class II inlay restorations: a 3D-FEA study.

Objectives: The purpose of this study was to investigate the effect of differences in the resin-cement elastic modulus on stress-transmission to ceramic or resin-based composite inlay-restored Class II MOD cavities during vertical occlusal loading.

Methods: Three finite-element (FE) models of Class II MOD cavity restorations in an upper premolar were produced. Model A represented a glass-ceramic inlay in combination with an adhesive and a high Young's modulus resin-cement.

Color and opacity variations in three different resin-based composite products after water aging.

Objectives: Correct shade selection and clinical procedures may be invalidated as a result of intrinsic color shifting with time. The aim of this study was to test the influence of exposure to water on the color stability of three structurally different resin-based composites.

Methods: Six comparable Vita shades of three different resin-based composite systems were selected.

Polymerization efficiency of curing lamps: a universal energy conversion relationship predictive of conversion of resin-based composite.

A universal energy-conversion relationship (ECRu) predictive of conversion of a resin-based composite (RBC) polymerized with any light source has been described. This relationship was derived from an energy conversion relationship for RBC polymerized with a tungsten-halogen lamp and the lamp's efficiency relative to a hypothetical standard lamp. The ECRu was then used to predict conversion throughout RBC polymerized with an LED lamp using the lamp's relative efficiency compared to the standard lamp.

An energy conversion relationship predictive of conversion profiles and depth of cure for resin-based composite.

Predicting the polymerization throughout resin-based composite (RBC) has been reduced to a set of variables involving irradiance of the light source, exposure duration and RBC transmission properties, together with an energy-conversion relationship (ECR) derived from Fourier Transform Infrared Spectroscopic analysis (FTIR) of a single shade of photo-polymerized RBC. The ECR describes the localized energy density required to achieve a desired conversion independent of shade. Using this ECR, conversion was predicted and experimentally verified throughout different opacities of RBC based on knowledge of their transmission properties and the incident radiant energy density (irradiance times exposure time).

The effect of filler and silane content on conversion of resin-based composite.

Objective: This study examines the influence of filler loading and silane content on the conversion of photoactivated, resin-based composites as determined using Fourier transform infrared spectroscopy (FTIR).

Method: Zirconia/silica filler was processed with a silane coupling agent (gamma-methacryloxypropyltrimethoxysilane) to achieve a range of silane-to-filler compositions. Treated fillers were compounded with a photoactivated BisGMA/TEGDMA resin to yield a series of pastes all containing 72 wt% total solids.

In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases.

Composite inlays are indicated for large cavities, which frequently extend cervically into dentin. The purpose of this study was to compare in vitro the marginal and internal adaptation of class II fine hybrid composite inlays (Herculite, Kerr) made with or without composite bases, having different physical properties. Freshly extracted human molars were used for this study.

Marginal and internal adaptation of class II restorations after immediate or delayed composite placement.

Direct class II composite restorations still represent a challenge, particularly when proximal limits extend below the CEJ. The aim of this in vitro study was to evaluate the influence of the type of adhesive and the delay between adhesive placement and composite insertion on restoration adaptation. Direct class II MOD box-shaped composite restorations (n=8 per group) were placed on intact human third molars, with proximal margins 1mm above or under CEJ.

An SEM evaluation of several adhesive systems used for bonding fiber posts under clinical conditions.

Objectives: The objective of this investigation was to evaluate the effectiveness of three 'one-bottle' and two 'three step' adhesive systems (as controls) in the formation of resin tags, adhesive lateral branches and a resin dentin interdiffusion zone (RDIZ) when used to bond fiber posts under clinical conditions. This study was performed using standardized SEM observations and scoring resin tag formation and density.

Methods: Fifty root canal treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study.

Energy dependent polymerization of resin-based composite.

Objective: This study explores the relationship between the extent of polymerization and the radiant energy (dose) applied during the photopolymerization of resin-based composites.

Method: FTIR was used to measure the 5-min and 24-h conversion of four resin-based composites prepared in a thin film and polymerized under conditions of decreasing intensity and a constant exposure time (30s) using a tungsten halogen curing light. The measured conversion was obtained over a wide range of applied radiant energy.

Effect of surface treatments on the bond strength of glass ionomers to enamel.

Objectives: The objective of this study was to evaluate the effect of various surface treatments on the bond strength of several glass ionomers to enamel, and to examine the resulting bond interface.

Methods: Ground bovine enamel specimens were divided into groups which were pretreated with one of the following: (1) no pretreatment, (2) Vitremer primer, (3) 10% polyacrylic acid or (4) 35% phosphoric acid. A conventional glass ionomer and two resin-modified glass ionomers (RMGI's) were bonded to the pretreated enamel surfaces, stored in water for 24h and shear bond strengths measured.

Effect of adhesive layer properties on stress distribution in composite restorations--a 3D finite element analysis.

Objectives: Teeth, adhesively restored with resin-based materials, were modeled by 3D-finite elements analysis that showed a premature failure during polymerization shrinkage and occlusal loading.

Methods: Simulation of Class II MOD composite restorations with a resin bonding system revealed a complex biomechanical behavior arising from the simultaneous effects of polymerization shrinkage, composite stiffness and adhesive interface strain. Due to a polymerization contraction, shrinkage stress increases with the rigidity of the composites utilised in the restoration, while the cusp movements under occlusal loading are inversely proportional to the rigidity of the composites.