Resin composite thickness' influence on L*a*b* coordinates and translucency.

OBJECTIVES: To evaluate if material thickness can influence the L*a*b* coordinates and translucency of different composite shades. MATERIALS AND METHODS: Twelve composite disc specimens made of three different resin composite materials (dentin A2, Essentia, GC; body shade A2, Brillant Everglow, Coltene-Whaledent; enamel skin neutral, Inspiro, Edelweiss DR) and of three different thicknesses 0.5, 1.0, and 1.5 mm were readied. L*a*b* coordinates of the 118 specimens were assessed by a calibrated reflectance spectrophotometer over a black as well as a white background. RESULTS: Over the black background, median ΔE00 values varied from 0.7 (Brilliant Everglow) to 1.5 (Inspiro SN) for 0.5-mm composite thickness (intrinsic color variation) and from 3.2 (Essentia) to 7.5 (Inspiro SN) for 1.0 mm, respectively 6.1 (Essentia) to 11.1 (Inspiro SN) for 1.5-mm composite thickness (color variation related to thickness). Over the white background, median ΔE00 values varied from 0.6 (Essentia) to 1.6 (Inspiro SN) for 0.5-mm composite thickness and from 2.9 (Inspiro SN) to 4.3 (Essentia) for 1.0 mm, respectively 4.9 (Inspiro SN) to 7.0 (Essentia) for 1.5-mm composite thickness. Transparency varied from 25.2% (Essentia) to 34.6% (Inspiro SN) for 0.5-mm composite thickness, from 20.3% (Essentia) to 27.5% (Inspiro SN) for 1.0-mm thickness and from 14.8% (Essentia) to 22.9% (Inspiro SN) for 1.5-mm thickness. CONCLUSIONS: Material thickness can influence the L*a*b* coordinates and translucency of different composite shades. CLINICAL RELEVANCE: L* a* b* coordinates are influenced by composite thickness.

In Vitro Evaluation of Marginal Adaptation of Direct Class II Composite Restorations Made of Different "Low-Shrinkage" Systems.

The present study evaluated the influence of various low-shrinkage restorative systems in class II direct composite restorations following simulated occlusal loading. Forty MOD class II cavities were prepared on freshly extracted human lower third molars with proximal margins located mesially 1.0 mm coronal to and distally 1 mm apical to the cementoenamel junction. The samples were randomly distributed into five experimental groups corresponding to the following restorative systems: a conventional resin composite (Tetric) as active control group, a low-shrinkage composite (Extra Low Shrinkage [ELS]) alone or combined with its corresponding flowable version (ELSflow) used as a 1- to 1.5-mm liner, a bulk-filling flowable composite (Surefil SDR) covered by a 1-mm layer of restorative composite (Ceram-X), and a restorative bulk-filling composite (SonicFill). All specimens were submitted to 1,000,000 cycles with a 100N eccentric load into saline. Tooth restoration margins were analyzed semiquantitatively by scanning electron microscopy before and after loading. The percentage of perfect adaptation to enamel varied from 94.15% (SonicFill) to 100% (ELS) before loading and from 69.22% (SonicFill) to 93.61% (ELS and ELSflow) after loading. Continuous adaptation to cervical dentin varied from 22.9% (Tetric) to 79.48% (SDR/Ceram-X) before loading and from 18.66% (Tetric) to 56.84% (SDR/Ceram-X) after loading. SDR/CeramX and SonicFill showed the best cervical dentin adaptation.

Shading concepts and layering techniques to master direct anterior composite restorations: an update.

Creating perfect direct composite restorations has been for long time a strict challenge due to many materials' limitations impacting either shade integration or surface quality, and possibly colour stability. Next to technological drawbacks, a certain complexity and lack of predictability in clinical application was inherent to the technique and made it elitist for a long time. Shading and layering concepts then progressively evolved from a simplistic, non histo-anatomical, bilaminar technique to a multi-layering approach (3 to 4 or more layers), following the Vita Classic™ system. One of the most achieved concepts is polychromatic layering which makes use of a variable number of layers (basically VITA™ or non-VITA™ opacious dentin, chromatic enamel and translucent/opalescent enamel), driven by the natural tooth optical composition. In parallel with this evolution, a simplified, non-VITA shading system was developed with a reduced number of layers (basically dentin &enamel layer, plus effect shades if required) known as the natural layering concept, aiming to the same optimal esthetic integration and natural colour reproduction/emulation. The latest improvements appear all driven by the same view of improved reliability and clinical simplification.

Comparative efficiency of plasma and halogen light sources on composite micro-hardness in different curing conditions.

OBJECTIVES: Recent developments have led to the introduction of high power curing lights, which are claimed to greatly reduce the total curing time. This study evaluated the effectiveness of a plasma-curing device (Apollo 95 E) and a halogen device (Heliolux DLX), in different curing conditions. METHOD: Vicker's micro-hardness values were performed on 1 and 2 mm thick composite discs cured in a natural tooth mold by direct irradiation or indirect irradiation through composite material (2 or 4 mm) and dental tissues (1 mm enamel or 2 mm enamel-dentin). Measures were, respectively, performed after a 1, 3, 6 s (SC, step curing mode) or 18 s (3xSC) exposure to the plasma light, and a 5, 10, 20 or 40 s exposure to the halogen light. RESULTS: With the PAC light used, a 3 s irradiation in the direct curing condition was necessary to reach hardness values similar to those obtained after a 40 s exposure to the halogen light. Using the indirect curing condition, hardness values reached after an 18 s exposure (3xSC mode) with the plasma light were either equivalent or inferior to those obtained with 40 s halogen irradiation. SIGNIFICANCE: Direct polymerization with the plasma light used requires longer exposure times than those initially proposed by the manufacturer. The effectiveness of plasma generated light was lowered by composite or natural tissues, and therefore requires an important increase in the irradiation time when applied to indirect polymerization. The practical advantage of this polymerization method is less than expected, when compared to traditional halogen curing.

Comparison of the color stability of ten new-generation composites: an in vitro study.

OBJECTIVES: The aim of this in vitro study was to evaluate the color stability of modern light-cured composites when subjected to various physico-chemical and staining conditions. METHODS: Ten brands were evaluated including hybrids, microfine hybrids and microfilled composites. Some universal shade samples underwent only staining tests, while others were subjected to one of the following experimental conditions: thermocycling, postcuring, polishing or a 1 wk immersion in saline, prior to staining. The coloring solutions used for the staining tests were: coffee, E 110 food dye, vinegar and erythrosin. A colorimetric evaluation according to the CIE L*a*b* system was performed after experimental periods of 1 and 3 wk. RESULTS: Erythrosin caused the greatest color change for the composites tested. A reduced susceptibility to staining was observed where surfaces had been polished. Low water sorption, a high filler-resin ratio, reduced particle size and hardness, and an optimal filler-matrix coupling system were related to improved composite resistance to discoloration. SIGNIFICANCE: Resistance of modern composites to discolorations still depends on their structure and manipulation.

Layering concepts in anterior composite restorations.

SUMMARY: With increasing patient demands for esthetic dentition, composite resin restorations enjoy great popularity due to excellent esthetics, acceptable longevity, and relatively low costs. Shading concepts used by manufacturers, however, may be confusing to many clinicians. PURPOSE: To review and describe the current main shading concepts, evaluate their potential for creating natural esthetics, and provide guidelines for application.

Evaluation of the marginal and internal adaptation of different ceramic and composite inlay systems after an in vitro fatigue test.

PURPOSE: The aim of this in vitro trial was to evaluate and compare the external and internal adaptation of Class II composite and ceramic inlays with scanning electron microscopy after mechanical loading and thermal cycling (fatigue). MATERIALS AND METHODS: Standardized cavities were prepared on human third molars with margins extending proximally 1 mm above or below the cemento-enamel junction (CEJ). A fine hybrid composite (Tetric), a hydrothermal glass (Ducera LFC), and a sintered spinell ceramic (In-Ceram) were used to fabricate the restorations. Combinations of Syntac classic--Variolink, ED primer--Panavia and Scotchbond MP--Variolink were used for cementation. RESULTS: For marginal adaptation in enamel, percentages of continuity varied from 85.4% to 99.6% and 85.1% to 98.2% for mesial and distal sites, respectively. Marginal adaptation in dentin showed continuity percentages varying from 63.6% (In-Ceram-Panavia) to 96.1% (Ducera LFC-Panavia). As regards internal adaptation, overall interface results varied from 32.1% (Tetric-Variolink) to 87.3% (Ducera LFC-Panavia). Gingival enamel showed the higher proportions of continuity (94.0%, all group-pooled data) compared to dentin locations (46.0% occlusally to 60.1% in gingival dentin). In all groups, debonding occurred mainly within the dentin--restoration interface and also, but to a lesser extent, between In-Ceram ceramic and both luting composites. When it occurred, adhesive failure to dentin consistently took place at or close to the hybrid layer surface. CONCLUSION: Despite important differences in their physical properties, no difference could be found under the present experimental conditions between Class II composite and ceramic inlays in terms of their marginal and internal adaptation.

Marginal and internal adaptation of stratified compomer-composite Class II restorations.

Different approaches have been proposed to improve the adaptation of Class II restorations, including applying low-elasticity modulus base liners. This in vitro fatigue test (or study) evaluated the influence of the compomer base-lining configuration on restoration adaptation. Direct Class II MOD box-shaped composite restorations with or without base and lining (n=3x8) were placed on intact human third molars with proximal margins 1 mm above or under the CEJ. The compomer (Dyract) was applied as a 1 mm-thick lining or as a base, closing proximo-gingival margins. Marginal adaptation was assessed before and after each phase of mechanical loading (250,000 cycles at 50N, 250,000 cycles at 75N and 500,000 cycles at 100N); internal adaptation was evaluated after test completion. Gold-sputtered resin replicas were observed in the SEM and restoration quality evaluated in percentages of continuity (C) at the margins and within the internal interface after sample section. Mechanical loading did not influence adaptation to enamel, while it adversely affected restoration adaptation to dentin for the full composite and compomer-base restorations (C varied, respectively, from 95.2 to 75.3% and from 98.0 to 10.6%). The internal adaptation quality showed the same general trend, however, with reduced scores of continuity. In this experimental condition, application of a low elasticity modulus layer under the restorative material proved advantageous but the compomer should not contact the gingival margins.

Esthetic restorations for posterior teeth: practical and clinical considerations.

The current abundance of posterior esthetic restorative materials and techniques may be confusing. This paper describes a simple and logical global concept that assists clinicians in choosing the appropriate therapeutic modality according to well-defined clinical criteria. Practical considerations about cavity preparation, base-lining, filling, luting, and finishing procedures are reviewed.

A clinical trial of four light-curing posterior composite resins: two-year report.

A 2-year study of the clinical performance of four posterior composite resins used for Class I and Class II restorations is reported. Seventy-seven obturations were reviewed from the patients selected for a previous 9-month study. Obturations were assessed macrophotographically and by scanning electron microscopic evaluation of marginal quality. The 2-year results were compared to those obtained at 9 months. The macrophotographic evaluation revealed a satisfactory clinical appearance in the majority of restorations. However, scanning electron micrographic observations demonstrated that moderate-to-medium marginal degradation occurred during the first 2 years of clinical service. Therefore the use of the products under investigation should be limited to selected cases in which esthetics is of primary concern.

An in vitro study of parameters related to marginal and internal seal of bonded restorations.

The wall-to-wall contraction of the cementing layer of bonded restorations is compensated for mainly by elastic and plastic tooth substrate-cement deformation but may result in adhesive fracture. Occlusally flattened teeth and corresponding computer-designed onlays, both positioned in a special device, were used to study marginal and internal seal of the adhesive interface with respect to four variables: rigidity of the restoration-substrate setup, cement thickness, adhesive configuration (enamel-dentin ratio and bonding agent), and luting agent. The results of dye infiltration tests revealed the significant influence of the adhesive configuration and rigidity of the setup. A high enamel-dentin ratio, use of a dentinal adhesive on dentinal margins and relative restoration-substrate "mobility" are required to preserve satisfactory marginal seal. However, in the present experimental conditions, no statistically significant differences were found among the diverse cement thicknesses or the luting agents evaluated.

Recent trends in esthetic restorations for posterior teeth.

The increase in the demands made by patients for esthetic or metal-free restorations, together with the ever-growing interest shown by the dental profession for tooth-colored materials and techniques, led to the current development of posterior adhesive restorations. This paper reviews critical elements such as adhesion to dental hard tissues as well as current properties of bases/liners, filling materials, and luting materials. A rationale for the successful use of currently available restorative systems is presented.

Current restorative modalities for young patients with missing anterior teeth.

The early loss of permanent teeth following trauma or congenital aplasia may be corrected by orthodontic or prosthetic means, sometimes combined with implant therapy. The orthodontic solution results usually in different anatomic, functional, and esthetic problems. Prosthetic and implant procedures, on the other hand, are very demanding and require long-term maintenance. Considering these limitations, a comprehensive diagnostic and treatment plan is mandatory to achieve the most satisfactory clinical result. Modern restorative modalities, such as recontouring, bleaching, and resin composite bonding, may improve the final clinical result after orthodontic space closure. In more difficult situations, veneers and crowns may also be indicated.

In vitro evaluation of marginal fit and morphology of fired ceramic inlays.

The marginal adaptation of fired ceramic inlays prepared by three dental technicians in two ceramic materials was evaluated in vitro. The thickness of the sealing gap varied between 46.4 and 57.6 microns, and the percentage of marginal ceramic defects ranged between 8.6% and 25.0% of the total inlay circumference. The incidence of marginal defects increased in areas of complex occlusal morphology. Differences observed in inlay adaptation were related to the technician rather than to the material used. The accuracy of ceramic inlays was comparable to that of metallic and porcelain-fused-to-metal crowns with butt-joint margins and fell within the range of clinically acceptable adaptation.

Marginal adaptation and seal of direct and indirect Class II composite resin restorations: an in vitro evaluation.

The aim of this in vitro study was to evaluate the marginal adaptation and seal of posterior composite resin restorations made with direct (three-sited multilayering) or indirect (extraoral inlay) techniques. The influence on the marginal quality of the cervical finishing design (butt or beveled) and residual enamel height (0.5, 1.0, and 1.5 mm up to the cementoenamel junction) was also evaluated. This trial was performed on sound, freshly extracted human molars. When residual enamel was less than 1.0 mm in height or 0.5 mm in thickness, indirect restoration resulted in superior marginal quality. For preparations with sufficient residual enamel height (greater than 1.0 mm), beveling of gingival margins appeared mandatory for good adaptation of direct restorations and beneficial to the adaptation of indirect restorations. Residual gingival enamel height and thickness demonstrated an influence on marginal quality only in indirect restorations with butt margins.

Influence of the restorative technique and new adhesives on the dentin marginal seal and adaptation of resin composite Class II restorations: an in vitro evaluation.

The aim of the present in vitro study was to evaluate the marginal adaptation and seal of direct and indirect (inlay) Class II resin composite restorations made with Z100/Scotchbond MP or Herculite/Optibond. The quality of margins in dentin was assessed for restorations made with or without a lining of glass-ionomer cement or resin-modified glass-ionomer material. The restored teeth were submitted to thermocycling and then to replication for scanning electron microscopic observation and to a dye infiltration test. In the present test conditions, the inlay technique proved its superiority over the direct restorative method. The quality of the dentinal margin of restorations made with Z100/Scotchbond MP appeared also slightly better. Both the glass-ionomer cement and the resin-modified glass-ionomer material, when applied as a lining, increased leakage and downgraded marginal adaptation. The full bonding with modern adhesives appeared to be the most efficient way to enhance the marginal quality of both direct and indirect restorations.

In vitro resistance to fracture of porcelain inlays bonded to tooth.

To assess the resistance to fracture of ceramic inlays, extracted sound human molars were restored with different ceramic materials and glass-ionomer or composite resin luting cement. Compression forces were applied to the specimens until they fractured, and maximal force developed, extent and location of fractures, and the micromorphology of the fractured surfaces were studied. Inlays made of Vitadur N with aluminum oxide profile and bonded with composite resin demonstrated the highest resistance among the restorative combinations, but their resistance was still lower than that of intact (control) teeth. The extent of fracture increased proportionally to the fracture resistance of the specimens. Scanning electron microscopic observation confirmed the effectiveness of the adhesion between composite resin and etched ceramic and the absence of sufficient micromechanical anchoring between glass-ionomer cement and etched ceramic.

Esthetic single-tooth replacement with implants: a team approach.

The range of indications for implant-borne prostheses in partially edentulous patients has expanded in recent years as a consequence of advances in regenerative techniques for bone and soft tissues. The esthetic demands of both patients and dentists have risen in parallel with these advances. Esthetic compromises in prostheses have become increasingly less tolerable, particularly in the anterior region of the maxilla. If the presenting situation is less than optimal, extensive preprosthetic measures may be required to prepare local tissues for acceptance of esthetically and functionally adequate prostheses. Particularly in difficult situations, collaboration by a team is recommended. The exchange of ideas and experience among specialists should begin as early as the treatment planning stage and extend over the entire course of therapy. The objective should be defined and the various steps of treatment should be coordinated with participation from all team members.

Bonded to tooth ceramic restorations: in vitro evaluation of the efficiency and failure mode of two modern adhesives.

Dentinal seal and the internal adhesive interface of bonded tooth ceramic overlays were evaluated in vitro, using a dye infiltration test and direct-indirect SEM observations. The new adhesives such as Optibond or Scotchbond MP demonstrated better performances in dentin bonding than former adhesives. With the large cementing space (300 microns), a rigid set-up restraining compensatory phenomena between the restoration and the tooth proved again to negatively influence the dentinal seal of bonded ceramic overlays. In the present test conditions, dentin bonding of the new adhesives remains perfectible, even if the total etch technique is applied. Failure modes of Optibond and Scotchbond MP showed some specific features. For both brands, bonding failures occurred mainly between the hybrid layer and the overlaying resins; these are not of an artefactual nature, as was demonstrated by indirect SEM observations. The cohesiveness of the adhesive interface does not appear optimal at the present time; the need for stress reduction in the cementing space therefore remains of primary concern in dentin bonded restorations.

Influence of a new experimental bonding agent on marginal seal of Class V restorations: an in-vitro study.

The performance of a new experimental dentin bonding agent (A.R.T. Bond) was evaluated in vitro. Its influence on the marginal seal of mixed class V restorations made on freshly extracted third molars, using 7 different restoration techniques was studied. When using the new dentin bonding agent, the results of the dye penetration test revealed the least dentinal leakage with the direct inlay technique. Dye penetration scores of bulk and incrementally placed restorations were higher, but not significantly different from the direct inlay. The absence of the dentin bonding agent in incrementally placed restorations resulted in significantly higher leakage values.