Properties of packable dental composites

A Historical Perspective on Dental Composite Restorative Materials

This review article will discuss the origin of resin-based dental composite materials and their adoption as potentially useful adjuncts to the primary material used by most dentists for direct restorations. The evolution of the materials, largely driven by the industry's response to the needs of dentists, has produced materials that are esthetic, strong, and versatile enough to be used in most areas of the oral cavity to replace or restore missing tooth structures. Significant advancements, such as the transition from chemical to light-curing materials, refinements in reinforcing particles to produce optimum polishing and wear resistance, formulating pastes with altered viscosities to create highly flowable and highly stiff materials, and creating materials with enhanced depth of cure to facilitate placement, will be highlighted. Future advancements will likely reflect the movement away from simply being a biocompatible material to one that is designed to produce some type of beneficial effect upon interaction within the oral environment. These new materials have been called "bioactive" by virtue of their potential effects on bacterial biofilms and their ability to promote mineralization of adjacent tooth structures.

Micromechanical interlocking structure at the filler/resin interface for dental composites: a review

Dental resin composites (DRCs) are popular materials for repairing caries or dental defect, requiring excellent properties to cope with the complex oral environment. Filler/resin interface interaction has a significant impact on the physicochemical/biological properties and service life of DRCs. Various chemical and physical modification methods on filler/resin interface have been introduced and studied, and the physical micromechanical interlocking caused by the modification of fillers morphology and structure is a promising method. This paper firstly introduces the composition and development of DRCs, then reviews the chemical and physical modification methods of the filler/resin interface, mainly discusses the interface micromechanical interlocking structures and their enhancement mechanism for DRCs, finally give a summary on the existing problems and development potential.

Fracture behavior of restored teeth and cavity shape optimization: Numerical and experimental investigation

OBJECTIVES

Since restored teeth are subject to more damages than intact teeth, investigating their fracture behavior is important. However, so far, improvement of the debonding behavior of the restoration and fracture of restored teeth considering the geometry of the restoration and different restorative materials has remained understudied. The aim of this paper is to numerically and experimentally investigate the debonding behavior of the restoration in premolar teeth in order to reduce the stress of restoration thereby reducing the mechanical failure.

METHODS

the fracture test for intact and Standard Class-II Mesial-Occlusal-Distal (MOD) restoration premolar teeth restored with several types of composite and conventional adhesive was performed in order to investigate their fracture behavior. The mechanical properties and fracture of composites as well as the adhesives used in experimental tests were obtained through separate standard mechanical tests. In addition, a number of composites and other adhesives were also chosen from other references, and by numerically simulating the fracture process of intact teeth and those restored with the materials of interest, the fracture behavior and yield load limit were investigated and predicted for them. Next, in order to reduce the stresses of bonding region and improve the damage behavior, using the stress-induced material transformation (SMT) optimization algorithm applied as code in finite element (FE) software, the shape of the restoration has been optimized based on different restorative materials. In order to confirm the numerical results, the fracture tests of teeth samples were performed with conventional and optimized restoration forms. Furthermore, using scanning electron microscopy (SEM) method, the fracture surface of the tested samples was examined.

RESULTS

since the fracture behavior of teeth restored with different materials is different, the optimized MOD restoration would be also different for each of these restorative materials. By selecting TU-shape for the restoration in each of the samples, the debonding resistance and final fracture of teeth compared to the MOD restoration increased 51% in P_d and 11% in P_f for numerical results and 40% in P_d and 4% in P_f for experimental results. The obtained results suggest that choosing a proper shape for the restoration based on the properties of restorative materials leads to diminished normal and shear stresses and enhanced debonding resistance. Also, the yield load limit of the defective teeth would also improve considerably.

SIGNIFICANCE

The clinical importance of this study is to predict strength of restored teeth and cavity shape optimization under variable conditions. Also, this paper introduces effective parameters on strength reduction/enhancement to dentists.

Influence of Dental Composite Viscosity in Attachment Reproduction: An Experimental in Vitro Study

Background: Attachments are composite auxiliaries that are used during a clear aligner orthodontic therapy to achieve difficult tooth movements. Two important factors are the planned configuration and the actual position of these auxiliary elements to obtain the desired force system. The aim of the present study was to evaluate the role of different composite materials in the correct reproduction of attachment shape and position. Methods: The materials that were considered in the study were a flowable resin, a dental restorative material, and an orthodontic composite. The attachments were created on three models of extracted teeth. Once the impressions were performed, 25 attachments of different shapes were added onto each virtual model to obtain the necessary templates to make the attachments. Each tested material was used to create a set of 25 attachments that were then scanned with an accuracy of 10μm. The resultant STL (stereolithography) files were superimposed onto the ones from the initial virtual plan, through Geomagic software, and the aligned scans were then compared while using a color map. The parameters that were calculated to make a comparison between the created attachments and the ideal ones were the maximum deviation in defect and in excess, the overflow, and the volume’s difference. In addition to these measurements comparing the three above-mentioned groups, the difference in volume between all the ideal and realized samples were analyzed. To test for differences among the three groups, a one-way Analysis of variance (ANOVA) was used with a Bonferroni post-hoc test. The level of significance was set at p < 0.05. Results: No statistically significant results were found between the three groups regarding the maximum value in defect, the maximum value in excess, and the minimum value as control, while a statistically significant difference was found between the overflow of orthodontic resin when compared to the flowable composite. Conclusions: The three materials that were used in this study were appropriate for attachment fabrication. The fidelity of attachment reproduction was similar when using the three different composites. The orthodontic composite showed more overflow when compared with the flowable one.

Trends in restorative composites research: what is in the future?

Clinical trials have identified secondary caries and bulk fracture as the main causes for composite restoration failure. As a measure to avoid frequent reinterventions for restoration replacement, composites with some sort of defense mechanism against biofilm formation and demineralization, as well as materials with lower susceptibility to crack propagation are necessary. Also, the restorative procedure with composites are very time-consuming and technically demanding, particularly concerning the application of the adhesive system. Therefore, together with bulk-fill composites, self-adhesive restorative composites could reduce operator error and chairside time. This literature review describes the current stage of development of remineralizing, antibacterial and self-healing composites. Also, an overview of the research on fiber-reinforced composites and self-adhesive composites, both introduced for clinical use in recent years, is presented.

Replacement of glass particles by multidirectional short glass fibers in experimental composites: Effects on degree of conversion, mechanical properties and polymerization shrinkage

OBJECTIVE

To test the null hypothesis that the replacement of a small fraction of glass particles with random short glass fibers does not affect degree of conversion (DC), flexural strength (FS), fracture toughness (FT) and post-gel polymerization shrinkage (PS) of experimental composites.

METHODS

Four experimental photocurable composites containing 1 BisGMA:1 TEGDMA (by weight) and 60vol% of fillers were prepared. The reinforcing phase was constituted by barium glass particles (2μm) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4mm in length, 7-13μm in diameter). DC (n=4) was obtained using near-FTIR. FS (n=10) was calculated via biaxial flexural test and FT (n=10) used the "single edge notched beam" method. PS at 5min (n=8) was determined using the strain gage method. Data were analyzed by ANOVA/Tukey test (DC, FS, PS) or Kruskal-Wallis/Dunn's test (FT, alpha: 5% for both tests).

RESULTS

DC was similar among groups (p>0.05). Only the composite containing 5.0% of fibers presented lower FS than the control (p<0.001). FT increased significantly between the control (1.3±0.17MPam(0.5)) and the composites containing either 5.0% (2.7±0.6MPam(0.5)) or 7.5% of fibers (2.8±0.6MPam(0.5), p<0.001). PS in relation to control was significantly reduced at 2.5% fibers (from 0.81±0.13% to 0.57±0.13%) and further reduced between 5.0% and 7.5% (from 0.42±0.12% to 0.23±0.07%, p<0.001).

SIGNIFICANCE

The replacement of a small fraction of filler particles with glass fibers significantly increased fracture toughness and reduced post-gel shrinkage of experimental composites.

Polymerization stress of experimental composites containing random short glass fibers

OBJECTIVE

To test the null hypotheses that (1) the replacement of particles by short fibers does not affect polymerization stress (PS), flexural modulus (FM) or volumetric shrinkage (VS) of experimental composites and (2) PS is not affected by specimen thickness.

METHODS

Three experimental composites were prepared, each containing similar mass fractions of BisGMA and TEGDMA and 60 vol% of fillers, being 0%, 3% or 6% constituted by 1.6-mm long glass fibers and the remaining by 1μm glass particles. PS (n=5) was tested in a high compliance system, using two specimen heights (1.5mm and 4.0mm). VS and maximum shrinkage rate were obtained in a mercury dilatometer (n=3). FM was tested in three-point bending (n=10). As an additional control, a commercial composite (Filtek Z250, 3M ESPE) was tested. Data were recorded 10min after the onset of photoactivation and analyzed by ANOVA/Tukey test (FM only) and Kruskal-Wallis (alpha: 5%).

RESULTS

At both specimen heights, the composite with 3% of fibers presented significantly higher PS than the controls (which showed similar PS values). Replacing 6% of particles by fibers did not increase PS significantly. FM was reduced in the presence of fibers, and 6% of fibers led to a decrease in VS. Shrinkage rate was not affected by the fibers.

SIGNIFICANCE

Replacing 3vol% of particles by fibers resulted in significantly higher PS, which was associated to a decrease in FM compared to the control. PS was not affected by specimen height for any of the tested materials.

Three-year Clinical Evaluation of Different Restorative Resins in Class I Restorations

The aim of the present study was to evaluate the three-year clinical performance of a nanofilled resin composite, a packable resin composite, and silorane-based resin restorations in Class I occlusal cavities. Twenty-eight patients with at least three similar-sized occlusal lesions in molar teeth participated in the study. A total of 84 Class I occlusal restorations were placed: 28 with nanofilled resin composite (Filtek Supreme), 28 with packable resin composite (P60), and 28 with silorane-based resin (Filtek Silorane). Filtek Supreme and P60 were used with their respective etch-and-rinse adhesive system, Adper Single Bond 2, and Filtek Silorane was used with its respective self-etch adhesive, Filtek Silorane Adhesive. All restorations were placed by the same operator. The restorations were evaluated at baseline, at six months, and annually for three years according to modified US Public Health Service criteria by two calibrated examiners who did not know which restorative resin had been used. The three restorative materials for each category were compared using the χ2 test at a significance level of 0.05. Cochran's Q test was used to compare the changes across the five time points for each restorative material. McNemar's test followed by Bonferroni adjustment was used when significance differences were found. At the end of the three years, 60 restorations were evaluated in 20 patients, with a recall rate of 71.4%. The retention rate was 100% for all restorative resins. Eight restorations from the P60 group, ten from the Filtek Supreme group, and nine from the Filtek Silorane group were rated Bravo for marginal discoloration. For marginal adaptation, three P60, five Filtek Supreme, and 11 Filtek Silorane restorations were rated Bravo. No statistically significant differences in overall clinical performance were found between the restorative materials except for marginal adaptation. P60 showed the best marginal adaptation at the end of the three years. No differences were observed between the restorative resins for any of the evaluation criteria tested (p&gt;0.05). None of the restorations showed postoperative sensitivity, secondary caries, or loss of anatomic form. All restorative resins performed equally well in clinical conditions during the three-year evaluation, and no significant differences were found among them, except for marginal adaptation, in which P60 showed superior results.

Investigation of the correlation between the different mechanical properties of resin composites

The aim of this study was to investigate the relationship between the different mechanical properties with the filler fraction of various resin composites. Mechanical properties of eighteen different resin composites were investigated in this study; flexural strength (FS), flexural modulus (FM), fracture toughness (FT), compressive strength (CS), diametral tensile strength (DTS), Barcol hardness (BH), Vickers hardness (HV), and Knoop hardness (HK). The mean values of mechanical properties and the filler fractions (V(f )) obtained from the literature and the manufacturer were analyzed using Pearson's correlation test at p<0.01. The relationships were compared with the data retrieved from previous studies. Strong correlations between Vf and BH/HV/HK and V(f) and FM were evident in the results of the present study and these results were supported by the retrieved data from previous studies. The other relationships between mechanical properties, such as that between FS and FM and between CS and HV were not significant.

Alternatives in polymerization contraction stress management

Polymerization contraction stress of dental composites is often associated with marginal and interfacial failure of bonded restorations. The magnitude of the stress depends on the composite's composition (filler content and matrix composition) and its ability to flow before gelation, which is related to the cavity configuration and curing characteristics of the composite. This article reviews the variations found among studies regarding the contraction stress testing method, contraction stress values of current composites, and discusses the validity of contraction stress studies in relation to results from microleakage tests. The effect of lower curing rates and alternative curing routines on contraction stress values is also discussed, as well as the use of low elastic modulus liners. Moreover, studies with experimental Bis-GMA-based composites and recent developments in low-shrinkage monomers are described.

Microhardness and polymerization shrinkage of flowable resins that are light cured using a blue laser

This study evaluated the microhardness and polymerization shrinkage of flowable resins that are cured using different light sources. Seven flowable resins and two light sources (diode-pumped solid-state (DPSS) laser (LAS) and Optilux 501 (OP)) were chosen for the study. To evaluate the microhardness, a mold (height: 2 mm, inner diameter: 4 mm) was filled with resin and then light cured. The microhardness was measured at the top and bottom surfaces after aging for 24 h. The level of polymerization shrinkage was evaluated for 130 s (during and after the light curing) by measuring the dimensions of the cylindrical shape resin filling. The light intensity of the LAS and OP was approximately 520 mW/cm(2) and 800 mW/cm(2), respectively. The data for the microhardness and polymerization shrinkage were analyzed statistically. The microhardness (Hv) of the specimens at the top and bottom surface ranged from 25.3 ± 0.6 to 55.3 ± 1.0 and 28.0 ± 2.6 to 63.0 ± 2.3, respectively. Admira flow, Grandio flow, and Filtek Z350 flow showed a slightly higher microhardness at the bottom surface than that at the top surface. The degree of polymerization shrinkage (μm) of the specimens ranged from 30.5 ± 1.3 to 45.9 ± 0.6 for LAS and from 35.1 ± 1.5 to 47.1 ± 1.0 for OP. The values obtained using LAS and OP showed a statistical difference, but in many cases, the difference between the absolute values was minor.

In vitro investigation of the performance of different restorative materials under cast circumferential clasps for removable dental prostheses

OBJECTIVES

The objective of this in vitro study was to investigate the behavior of different composite restorative materials under the load of cast circumferential clasps for removable dental prostheses (RDPs).

METHODS

In 60 human molars, standardized mesial-occlusal-distal cavities were prepared. The cavities were restored with the following materials: Definite, Tetric Ceram, SureFil, Heliomolar RO, Ariston pHc, and Oralloy, and provided with a rest seat. The rest seats were subjected to 5,000 cycles of thermal cycling and 1,200,000 masticatory cycles in a mastication simulator via cobalt-chromium circumferential clasps cast to standardized frameworks in a laboratory model designed to simulate the biomechanics of a free-end denture base. Fracture analysis of the restorations was performed by light microscopy. Before and after loading, material wear was measured with a 3D-laser scanner, and an analysis of the marginal quality was performed in an SEM at ×200 applying the replica technique.

RESULTS

No significant differences in the fracture behavior among the composite materials were found; the amalgam control group showed a significantly higher fracture resistance. Regarding the wear of the materials, the composites Definite and SureFil exhibited a behavior similar to that of amalgam. The other composites demonstrated higher wear rates. The initial marginal quality was significantly worse for Ariston pHc. The marginal adaptation decreased significantly after thermal and mechanical loading for Definite and Ariston pHc.

CONCLUSIONS

In terms of the investigated aspects of mechanical performance, the tested composites seemed to be inferior to amalgam. Further clinical studies are needed to evaluate the ability of composite restorations to provide support for RDP clasps.

CLINICAL RELEVANCE

The use of composites as direct restoration materials should be avoided in teeth, which serve as abutments for clasp-retained RDPs.

Effects of air-polishing powders on color stability of composite resins

OBJECTIVES

The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials.

MATERIAL AND METHODS

Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p<0.05).

RESULTS

According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil.

CONCLUSION

Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing after air-polishing.

Effect of filler size and temperature on packing stress and viscosity of resin-composites

The objective of this study was to investigate the effect of filler size on the packing stress and viscosity of uncured resin-composite at 23 °C and 37 °C. A precision instrument used was designed upon the penetrometer principle. Eight resin-composite materials were tested. Packing-stress ranged from 2.60 to 0.43 MPa and viscosity ranged from 2.88 to 0.02 MPa.s at 23 °C. Values for both properties were reduced significantly at 37 °C. Statistical analysis, by ANOVA and post hoc methods, were carried out to check any significant differences between materials tested (P < 0.05). Conclusions: Filler size and distribution will affect the viscosity and packing of resin-composites during cavity placement.

Microhardness of composite materials with different organic phases in deep class II cavities: an in vitro study

OBJECTIVE

This study compared the microhardness of three composite resins with different organic matrices in deep class II cavities.

MATERIALS AND METHOD

A total of 36 extracted molars were randomly assigned to six groups and standardized class II cavities were prepared. The cavity design comprised three steps in a mesiodistal direction with an increasing depth (2, 4, and 6 mm). Twelve cavities each were restored using Filtek Supreme (FS), Quixfil (QF), and Filtek Silorane (SI). The materials were applied in incremental layers of 2 mm and cured either with Halogen Translux Energy (HTE) (n=18) or LED Bluephase C8 (LED) (n=18). Subsequently, the specimens were cross-sectioned, and microhardness was determined in various depths and at two different distances from the matrix.

RESULTS

QF yielded the highest KHN microhardness values (92.67 ± 12.77), followed by FS (65.53 ± 19.52) and SI (57.67 ± 8.33). Composites cured with LED achieved higher KHN values. All materials showed the highest microhardness values within the superficial increments and at a distance of 1000 μm from the matrix.

Evaluation of Packable and Conventional Hybrid Resin Composites in Class I Restorations: Three-year Results of a Randomized, Double-blind and Controlled Clinical Trial

Long-term randomized, controlled, clinical trials of treatment outcomes are clearly needed to evaluate the long-term performance of composites in posterior teeth.

Effects of polishing procedures on color stability of composite resins

The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change ∆E*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (α=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish system (PdB and PdPB groups).

Six-year Clinical Evaluation of Packable Composite Restorations

As a posterior composite, Filtek P60 exhibited very good clinical performance in Class II cavities for six years.

Novel nano-particles as fillers for an experimental resin-based restorative material

The purpose of this study is to compare the properties of two experimental materials, nano-material (Nano) and Microhybrid, and two trade products, Clearfil AP-X and Filtek Supreme XT. The flexural strength and modulus after 24h water storage and 5000 thermocycles, water sorption, solubility and X-ray opacity were determined according to ISO 4049. The volumetric behavior (DeltaV) after curing and after water storage was investigated with the Archimedes principle. ANOVA was calculated with p<0.05. Clearfil AP-X showed the highest flexural strength (154+/-14 MPa) and flexural modulus (11,600+/-550 MPa) prior to and after thermocycling (117+/-14 MPa and 13,000+/-300 MPa). The flexural strength of all materials decreased after thermocycling, but the flexural modulus decreased only for Filtek Supreme XT. After thermocycling, there were no significant differences in flexural strength and modulus between Filtek Supreme XT, Microhybrid and Nano. Clearfil AP-X had the lowest water sorption (22+/-1.1 microg mm(-3)) and Nano had the highest water sorption (82+/-2.6 microg mm(-3)) and solubility (27+/-2.9 microg mm(-3)) of all the materials. No significant differences occurred between the solubility of Clearfil AP-X, Filtek Supreme XT and Microhybrid. Microhybrid and Nano provided the highest X-ray opacity. Owing to the lower filler content, Nano showed higher shrinkage than the commercial materials. Nano had the highest expansion after water storage. After thermocycling, Nano performed as well as Filtek Supreme XT for flexural strength, even better for X-ray opacity but significantly worse for flexural modulus, water sorption and solubility. The performances of microhybrids were superior to those of the nano-materials.

Clinicians choices of restorative materials for children

BACKGROUND

Recently, there has been an expansion in the range of tooth-coloured restorative materials available. In 1999, the National Health and Medical Research Council recommended clinicians use alternatives to amalgam in children 'where appropriate'.

METHODS

A three-part 29-item questionnaire was developed, tested in a focus group, and distributed to members of the Australasian Academy of Paediatric Dentistry (AA; paediatric dentists and paediatric dentistry postgraduate students; n=55), and the Australian and New Zealand Society of Paediatric Dentistry, Victorian Branch (SPD; general dentists and dental therapists; n=50). Participant information, material choices, and six hypothetical clinical scenarios were addressed.

RESULTS

The overall response rate was 74 per cent. For both groups, the first ranked factor influencing choice of restorative material for vital primary teeth was child age, and caries experience for vital first permanent molars. For moderate-sized Class I and II restorations in primary molars, a tooth-coloured material was chosen by 92 and 84 per cent respondents respectively. For restoring two separate proximal lesions in a primary molar, 65 per cent chose a tooth-coloured material followed by a stainless steel crown (27 per cent; all AA members), then amalgam (8 per cent). The SPD respondents were significantly more likely to choose glass ionomer cement for Class I and II restorations and for restoring two proximal lesions (all p=0.000) in primary molars than AA respondents, who were more likely to choose composite resins/compomers or amalgam/stainless steel crowns for these restorations. Younger respondents (21-40 years) were significantly more likely to choose composite resins/compomers or amalgam/stainless steel crowns (p=0.048) than older respondents (41-65 years), who were likely to choose glass ionomer cement.

CONCLUSIONS

For Class I and II restorations in primary molars, glass ionomer cement was the material chosen most frequently (SPD respondents); preference for amalgam or stainless steel crowns was low (both SPD and AA groups). The wide range of materials chosen for the hypothetical clinical scenarios suggests the need for guidelines on selection of restorative materials, and the need for longitudinal studies to follow actual clinical outcomes of the materials chosen.

Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials—A comparative study

OBJECTIVES

To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials.

METHODS

The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05).

RESULTS

DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage.

CONCLUSION

Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.

Water sorption and solubility of contemporary resin-based filling materials

PURPOSE

Evaluation of water sorption and solubility of contemporary resin-based filling materials.

METHODS

Specimens of Herculite (HE), Point 4 (P4), TetricCeram (TC), Miris (MI), TetricCeram HB (HB), Solitaire 2 (SO), SureFil (SU), Definite (DE), Admira (AD), Dyract AP (DY), Compoglass F (CO), and TetricFlow (TF) were prepared according to ISO 4049. Water sorption and solubility were measured after water storage at 37 degrees C for 7 days.

RESULTS

Water sorption was HE 14 microg mm(-3), P4 17 microg mm(-3), TC 12 microg mm(-3), MI 13 microg mm(-3), HB 9 microg mm(-3), SO 18 microg mm(-3), SU 9 microg mm(-3), DE 14 microg mm(-3), AD 27 microg mm(-3), DY 19 microg mm(-3), CO 23 microg mm(-3), and TF 19 microg mm(-3). Solubility was HE 3 microg mm(-3), P4 3 microg mm(-3), TC 1 microg mm(-3), MI 0 microg mm(-3), HB 0 microg mm(-3), SO 3 microg mm(-3), SU 0 microg mm(-3), DE 1 microg mm(-3), AD 2 microg mm(-3), DY 4 microg mm(-3), CO -2 microg mm(-3), and TF 1 microg mm(-3).

CONCLUSION

All materials met the corresponding requirement in ISO 4049. Filler load negatively correlated with water sorption but not with solubility. There was an influence of the resin matrix, too. No significant differences were found between composites, ormocers, and compomers.

Changes in color and staining of dental composite resins after wear simulation

OBJECTIVES

The objectives were to measure the discoloration as well as the change in staining of composite resins after wear simulation.

METHODS

Generalized wear simulation was performed with a three-body wear testing device for 400,000 cycles for six composite resins. A flat-planed stylus made with polyacetal resin was loaded perpendicularly under a load of 76-80 N. Color of nonworn and worn areas was measured with a spectrophotometer before and after staining with 0.5% methylene blue solution. Nonworn surface served as a control. Differences in color between nonworn and worn surfaces were calculated to indicate the change in color due to wear. Color change after staining with 0.5% methylene blue solution for nonworn and worn surfaces was calculated to observe the changes in staining.

RESULTS

Color difference (DeltaE(*) (ab)) between nonworn and worn surfaces was in the range of 0.8-1.4 before staining, which increased to 1.1-3.9 after staining. Color change by staining with methylene blue in nonworn surface was 6.8-20.6, and that in worn surface was 5.2-17.8. Therefore, staining in nonworn surface was higher than that in worn surface (p < 0.05). Generalized wear simulation for approximately 3 years of clinical service resulted in acceptable color change before staining (DeltaE(*) (ab) < 3.3). After staining, color difference between nonworn and worn surface increased to not-acceptable value in one composite resin investigated.

The effects of thermocycling on the flexural strength and flexural modulus of modern resin-based filling materials

OBJECTIVE

Evaluation of flexural strengths and flexural moduli of hybrids, packables, ormocers, compomers and flowables prior to, and after, thermocycling.

MATERIALS AND METHODS

Twenty specimens, size (25 +/- 2) mm x (2 +/- 0.1) mm x (2+/-0.1) mm, of Herculite (HE), Point 4 (P4), TetricCeram (TC), Miris (MI), TetricCeram HB, (HB), Solitaire 2 (SO), Surefil A (SU), Definte (DE), Admira (AD), Dyract AP (DY), Compoglass (CO) and TetricFlow (TF) were made according to ISO 4049. A three-point-bending test was carried out for the first 10 specimens after 24 h water storage at 37 degrees C and for the second 10 specimens after 30-day water storage at 37 degrees C, followed by 5000 thermocycles between +5 and +55 degrees C. For each test series flexural strengths and flexural moduli were calculated. Statistical significance was p < 0.05.

RESULTS

Flexural strengths of DY and CO missed the 80 MPa limit of ISO 4049 for occlusal fillings prior to and after thermocycling. AD missed it after thermocycling. HE, P4, TC, MI, HB, SO, SU, DE and TF did not significantly differ prior to and after thermocycling. Flexural strength of SO and AD significantly decreased after thermocycling. No change of the flexural moduli could be observed for any of the test materials. Only SU exceeded 10,000 MPa prior to and after thermocycling.

SIGNIFICANCE

Only DY and CO missed the flexural strength limit of ISO 4049 for occlusal fillings. Only SU exceeded a flexural modulus of 10,000 MPa prior to and after thermocycling.

Properties of a Dental Resin Composite with a Spherical Inorganic Filler

Of the materials tested in this study, the spherical filler composite (Estelite Σ) had similar properties as the nano-composite (Filtek Supreme). Thus, Estelite Σcan be used in anterior regions and restricted posterior restorations. All the materials had a similar shrinkage pattern, in that about 99% of the shrinkage occurred prior to 24 hours; thus, for direct resin composite restorations, a strong initial bonding strength with bonding agent would be necessary.

Fiber-reinforced packable resin composites in Class II cavities

OBJECTIVE

To evaluate the 6-year performance of two glass fiber-reinforced packable resin composites in Class II cavities.

METHODS

Sixty-three participants received 87 medium to large, cervically dentin bordered, Class II restorations of two fiber-reinforced resin composites, 42 Nulite F (N) and 45 Alert (A). The restorations were evaluated clinically, according to slightly modified USPHS criteria at baseline, after 6 months, and yearly during 6 years.

RESULTS

At 2 years the cumulative failure frequencies for N and A were 4.8% and 2.2%, respectively, which increased at 6 years to 25.0% and 12.8%. Reasons for failure were secondary caries, material and cusp fracture. The majority of the failures occurred after 3 years. Secondary caries occurred between 4 and 6 years. The incorporation of fibers resulted in very rough surface characteristics.

CONCLUSIONS

A rather high failure rate was observed for one of the fiber-reinforced resin composites, while the other fulfilled the ADA criteria. The occurrence of most failures after 3 years indicated the necessity of long-term evaluations of new materials.

Clinical Evaluation of a Nanofilled Composite in Posterior Teeth: 12-month Results

Nanofilled resin composite showed excellent clinical performance, similar to microhybrid and packable composites after 12-months.

Use of two surface analyzers to evaluate the surface roughness of four esthetic restorative materials after polishing

This study had two aims: determine how well four esthetic restorative materials lent themselves to polishing and compare the results obtained using two different techniques for evaluating surface roughness. The four materials used were two composites modified by the addition of resin, Dyract AP (Dentsply) and Dyract Flow (Dentsply); one composite designed for posterior restorations, SureFil (Dentsply) and one universal micromatrix composite, Esthet-X (Dentsply). Five test pieces were made with each product by inserting the material into cylindrical molds and polymerizing it layer by layer. A single operator polished the specimens on the same day using the Enhance system (Dentsply) and two aluminum oxide pastes. The surfaces were studied successively by means of two surface analyzers: a high-resolution optical profilometer (Nanosurf 488, SAS Technology) and a mechanical profilometer (Mitutoyo Surftest-SV 402). These measurements gave the mean roughness of the surface (Ra). Ten zones were examined for each specimen, and the specimens were observed under an optical microscope (PMG3 inverted metallographic microscope) at 50x magnification. The qualitative and quantitative analyses of the results showed good surface states for all materials. However, the composites based on nano- and micro-filler technology gave the smoothest surfaces after polishing. A comparison of the values obtained with each method of observation showed that mechanical profilometry tended to show roughness caused by polishing, while optical profilometry brought out roughness due to the structure of the material itself.

3-Year clinical evaluation of posterior packable composite resin restorations

This study evaluated the clinical performance of four packable resin composite restorative materials in posterior teeth (Class I and II) compared with one hybrid composite after 3 years. Eighty-four restorations were placed in 16 patients. The tested materials were: (i) Solitaire + Solid Bond; (ii) ALERT + Bond-1; (iii) Surefil + Prime & Bond NT; (iv) Filtek P60 + Single Bond and (v) TPH Spectrum + Prime & Bond 2.1. All restorations were made using rubber dam isolation, and the cavity design was restricted to the elimination of carious tissue. Deeper cavities were covered with calcium hydroxide and/or glass-ionomer cement. Each adhesive system and composite resin was placed according to the manufacturer's instructions. One week later, the restorations were finished/polished and evaluated according USPHS modified criteria. Fourteen patients attended the 3-year recall and 75 restorations were evaluated at that time based on the same evaluation criteria. Friedman repeated measures analysis of variance by rank and Wilcoxon sign-ranked test for pair-wise comparison was used for data analysis (alpha = 0.05). The analysis was performed only for the baseline and for the 3-year period. Solitaire showed some fractures at marginal ridges in 25% of the cases. Solitaire and ALERT showed some concerns related to colour match (43 and 77%, respectively) and surface texture (86 and 77%, respectively). TPH Spectrum showed a great percentage of colour mismatch after 3 years, around 50%. Surefil and Filtek P60 showed an excellent clinical performance after 3 years, similar to the hybrid resin tested, TPH Spectrum. Solitaire did not fulfil the ADA acceptance criteria for restorative materials and, therefore, is not recommended for use in posterior restorations.

Dynamic Viscoelastic Behavior of Dental Composites Measured by Split Hopkinson Pressure Bar

The present study evaluated the dynamic viscoelastic behavior of commercially available dental composites by a Split Hopkinson pressure bar (SHPB) test machine. Five commercially available composite resins--namely, two conventional hybrid composites (Filtek Z100, Z100; Filtek Z250, Z250), a packable composite (Filtek P60, P60), a flowable composite (Filtek Flow, FL), and a nanofill composite (Filtek Supreme, SU)--were evaluated. By means of SHPB technique, the dynamic stress-strain curve, storage modulus, and loss tangent of the five dental composites were calculated. All specimens exhibited a nonlinear stress-strain curve in the loading process, which resulted not only from the viscoelasticity--but also from the plasticity--of matrix. In terms of storage modulus, no significant differences were exhibited among the five dental composites (p > 0.05). In terms of loss tangent, Z100 showed a significantly higher value than P60, FL, and SU (p < 0.05). Within the limitations of this investigation using SHPB, it was indicated that the loss tangent increased with increasing filler content.

Can a single composite resin serve all purposes?

The consensus view less than a decade ago was that direct posterior composites should be restricted to small restorations, preferably in premolar teeth with little, if any, occlusal function. Major advances in adhesive systems, materials and restorative techniques have combined to allow us to question this view and our increased clinical evidence base makes it appropriate to reconsider this viewpoint.

Fatigue behavior of packable composites

The aim of this study was to investigate the flexural fatigue behavior of 11 packable composites. Of each material 30 rectangular samples (1.2 x 5 x 35 mm) for flexural fatigue test were prepared. The clamped fracture strength and flexural fatigue limit (FFL) of each material were determined using a custom-made fatigue machine, after storage of the samples for one month in water at 37 degrees C. All data were analyzed using one-way ANOVA and Bonferroni/Dunn's test for multiple comparisons (p<0.05). Regression analysis was used to evaluate the relationship between elastic modulus (Abe et al., 2001), clamped fracture strength or FFL and inorganic filler fraction (vol%). The fracture strengths of all but two materials were in between those of the compact-filled densified composites and the microfine ones. The FFL of the packable composites tested were significantly lower than those of the compact-filled densified composites. Three of the tested materials showed even significantly lower FFL than did the microfine composites. There were statistically significant relationships between both the elastic modulus and the volumetric filler fraction (R(2)=0.974, p=1.990 x 10(-7)). The great diversity in packable composites makes clinical assessment necessary with regard to a justified use in posterior teeth.

Does the wear resistance of packable composite equal that of dental amalgam?

BACKGROUND

There is little evidence that packable composites are sufficiently wear resistant to be used as an alternative to amalgam.

PURPOSE

The purpose of this study was to evaluate wear rates of packable composites compared with hybrid resin composites and amalgams by an in vitro wear test.

MATERIALS AND METHODS

The following composites were used: three packable composites (SureFil, Dentsply/Caulk, Milford, DE, USA; Alert, Pentron Clinical Technologies, Wallingford, CT, USA; and Solitaire, Heraeus Kulzer, Wehrheim, Germany), two hybrid resin composites (TPH Spectrum, Dentsply/Caulk; and Pyramid enamel, Bisco Inc., Schaumburg, IL, USA), and two amalgams (Tytin, Kerr Manufacturing Co., Romulus, MI, USA; and Dispersalloy, Dentsply/ Caulk). Cylindrical Class I cavities prepared on occlusally flattened, extracted human molars were restored with respective materials according to the manufacturers' instructions. Generalized, localized, and antagonistic enamel wear tests were carried out by a University of Alabama at Birmingham (UAB) wear simulator according to previously reported methods. Seven specimens were tested for each group, and the wear depths were measured on profilometric tracings. The data for each wear mode were independently analyzed by one-way analysis of variance and Fisher's exact test (p < or = .05).

RESULTS

The generalized wear values for SureFil (7.0 +/- 3.5 microm), Alert (8.6 +/- 1.8 microm), and Pyramid (3.9 +/- 0.5 microm) were not statistically different from those of amalgam materials (Tytin 5.8 +/- 0.7 microm, Dispersalloy 6.0 +/- 0.9 microm) but were different from those of Solitaire (23.9 +/- 2.6 microm) and TPH (30.6 +/- 5.5 microm). The localized wear values for SureFil (19.8 +/- 14.2 microm) and Alert (28.0 +/- 1.6 microm) were significantly smaller than for all other materials. For antagonistic enamel wear, Solitaire exhibited a minimal value (3.4 +/- 0.9 microm), whereas values of SureFil (12.6 +/- 5.6 microm) and Alert (12.0 +/- 6.6 microm) were not statistically different from those of TPH (11.0 +/- 4.0 microm) and amalgams (Tytin 14.5 +/- 4.3 microm, Dispersalloy 7.8 +/- 3.3 microm).

CONCLUSIONS

It can be concluded that SureFil and Alert packable composites possess similar wear resistance and abrasiveness to amalgam on the basis of the limitations of this study, which simulated 3 years of clinical wear.

Changes in surface characteristics of dental resin composites after polishing

The objectives of this study were (1) to determine in vitro changes in surface roughness and color of dental resin composites after application of three finishing and polishing systems; (2) to evaluate the difference in color stability after immersion in a dye solution after polishing; and (3) to evaluate the effects of surface condition, especially roughness, on measured color depending on the color measuring geometries of specular component excluded (SCE) and specular component included (SCI). Color and surface roughness (R(a)) of resin composites of four brands of A2 shade and one brand of Yellow Enamel shade were measured after polymerization, after polishing with Enhance (Dentsply), Sof-Lex (3M ESPE), or Super-Snap (Shofu) composite finishing and polishing systems. Color was also measured after immersion in 2% methylene blue solution. Color was measured according to the CIELAB color scale. Color changes (DeltaE*(ab)) after polishing/staining and by the measuring geometry were calculated by the equation; DeltaE*(ab) = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2). Ra value was measured with a surface roughness tester. DeltaE*(ab) and DeltaL* values after polishing and after staining varied among polishing systems when measured with SCE geometry. Composites polished with Super-Snap and Sof-Lex systems showed higher DeltaE*(ab) and DeltaL* values than those polished with Enhance polishing system with SCE geometry. DeltaE*(ab) and DeltaL* values between specimens with different surface conditions measured with SCE geometry were significantly higher than those with SCI (p < 0.01). Changes in R(a) value after polishing was insignificant in most cases.

Strength and fatigue performance versus filler fraction of different types of direct dental restoratives

The aim of this study was to evaluate the mechanical properties, such as Young's moduli, fracture strengths (FS), and flexural fatigue limits of todays resin composite dental restoratives. All materials have been subdivided into flowable, aesthetic hybrid and nano-filled hybrid composites as marketed by dental manufacturers and analyzed in terms of the actual filler configurations. Specimen bars have been manufactured in reference to ISO 4049 standard, light-cured for 20 s, and stored in distilled water before testing. The elastic moduli (EM), FS, and flexural fatigue limits (FFL) were measured after 14 days storage by using the four-point bending test. The FFL was determined for 10(4) cycles. The fatigue data were analyzed by using the "staircase" approach and statistically treated by ANOVA analysis. Flowable materials with a reduced filler content exhibited the lowest Young's moduli, compared with those measured for higher filled materials. A linear relationship has been found between elastic moduli and filler loading (r(2) = 0.798). Correlations of FS and fatigue data to different filler fractions could not be proved. FS ranged between 61.3 and 124.9 MPa. After 10(4) cycles of fatigue loading, the FS suffered from a decrease between 45.2 and 61.7%. However, materials providing high initial strengths do not obviously reveal the best fatigue resistance. A marketing-based grouping of direct restorative materials has no meaning toward laboratory testing of mechanical properties.

Alternatives in polymerization contraction stress management

Polymerization contraction stress of dental composites is often associated with marginal and interfacial failures of bonded restorations. The magnitude of stress depends on composite composition (filler content and matrix composition) and its ability to flow before gelation, which is related to the cavity configuration and curing characteristics of the composite. This article reviews variations among studies regarding contraction-stress-testing methods and contraction stress values of current composites, and discusses the validity of contraction stress studies in relation to results from microleakage tests. The effects of lower curing rates and alternative curing routines on contraction stress values are also discussed, as well as the use of low-elastic-modulus liners. Moreover, studies with experimental dimethacrylate-based composites and recent developments in low-shrinkage monomers are described.

Clinical evaluation of packable and conventional hybrid resin-based composites for posterior restorations in permanent teeth: results at 12 months

BACKGROUND

Packable resin-based composites and simplified resin bonding systems are marketed to offer many advantages over conventional posterior hybrid composites and total-etch bonding systems. The authors conducted a study to evaluate the initial clinical performances of a packable and a conventional hybrid resin-based composite used with a simplified bonding system.

METHODS

A total of 57 Class I and 45 Class II restorations were placed in the permanent teeth of 65 adult patients. The carious lesions were restored with either packable resin-based composite (SureFil, Dentsply DeTrey GmbH, Konstanz, Germany) or conventional hybrid resin-based composite (SpectrumTPH, Dentsply DeTrey GmbH), using a resin adhesive (Non-Rinse Conditioner and Prime & Bond NT, both manufactured by Dentsply DeTrey GmbH). The authors evaluated the restorations using U.S. Public Health Service-Ryge modified criteria (in which Alfa is the highest rating) and by using color transparencies and die stone replicas.

RESULTS

Three SureFil restorations failed before their baseline evaluation. There were no failures among the 78 SpectrumTPH restorations evaluated at 12 months. For both resin-based composites, Alfa ratings were 90 percent or higher for marginal discoloration, anatomical form, surface texture and surface staining. Lower percentages of restorations were rated Alfa for color match, marginal integrity and gingival health. Occasional mild postoperative sensitivity was reported for four SureFil restorations and one SpectrumTPH restoration. The mean occlusal wear rate was 38 micrometers for the larger SureFil restorations and 25 microm for the smaller SpectrumTPH restorations.

CONCLUSIONS

The 12-month clinical performances of the two restorative materials were satisfactory and not significantly different for each of the parameters evaluated.

CLINICAL IMPLICATIONS

A packable and a conventional hybrid resin-based composite placed with a simplified bonding system in posterior permanent teeth showed satisfactory and similar results after 12 months.

Surface Roughness of Packable Composite Resins Polished with Various Systems

PURPOSE

The aim of this study was to evaluate the surface roughness of four packable composite resins, SureFil (Dentsply, Petrópolis, Rio de Janeiro, Brazil), Prodigy Condensable (Kerr Co., Orange, CA, USA), Filtek P60 (3M do Brasil, São Paulo, Brazil), and ALERT (Jeneric/Pentron, Inc., Wallingford, CT, USA) and one microhybrid composite resin (Filtek Z250, 3M do Brasil) after polishing with four finishing systems.

MATERIALS AND METHODS

Twenty specimens were made of each material (5 mm in diameter and 4 mm high) and were analyzed with a profilometer (Perthometer S8P, Perthen, Mahr, Germany) to measure the mean surface roughness (Ra). The specimens were then divided into four groups according to the polishing system: group 1--Sof-Lex (3M do Brasil), group 2--Enhance (Dentsply), group 3--Composite Finishing Kit (KG Sorensen, Barueri, São Paulo, Brazil), and group 4--Jiffy Polisher Cups (Ultradent Products, Inc., South Jordan, UT, USA). The specimens were polished and then evaluated for Ra, and the data were subjected to analysis of variance, analysis of covariance, and Tukey's test (p = .05).

RESULTS

The mean Ra of SureFil polished with Sof-Lex was significantly lower than that of KG points. Prodigy Condensable polished with Enhance showed a significantly less rough surface than when polished with Sof-Lex. Filtek P60 did not exhibit a significant difference with the various polishing systems. For ALERT the lowest mean Ra was obtained with Sof-Lex and the highest mean Ra with KG points. Regarding Filtek Z250, polishing with KG and Jiffy points resulted in a significantly lower mean Ra than when polished with Enhance.

CONCLUSIONS

Packable composite resins display variable roughness depending on the polishing system used; the Sof-Lex disks and Jiffy points resulted in the best Ra values for the majority of the materials tested.

CLINICAL SIGNIFICANCE

The Sof-Lex disks and the Jiffy points produced the smoothest surfaces for the tested resin composites. As a result, they should be considered for clinical use as preferred polishing systems for these resin composites.

Total-etch versus self-etch adhesive

BACKGROUND

Self-etching adhesives are believed to prevent postoperative sensitivity when used under posterior resin-based composite restorations. The authors tested a twofold hypothesis: a self-etch, or SE, adhesive would result in less postoperative sensitivity than a total-etch, or TE, adhesive; an SE adhesive would result in poorer enamel marginal integrity than a TE adhesive.

METHODS

Patients were selected on the basis of requiring Class I and II restorations in molars and premolars. The authors placed 30 restorations with the SE material (Clearfil SE Bond, Kuraray America, New York) and 36 restorations with Prime & Bond NT (Dentsply Caulk, Milford, Del.), which uses 34 percent phosphoric acid to etch enamel and dentin simultaneously. Preparations were of standard design, with all margins in enamel without beveling. Upon rubber dam isolation, the authors conditioned the enamel and dentin walls with the self-etching primer (for Clearfil SE Bond) or etched with the proprietary 34 percent phosphoric acid (for Prime & Bond NT), followed by application of the corresponding dentin adhesive. Teeth were restored with the proprietary hybrid resin-based composite indicated for posterior restorations: Clearfil AP-X for Clearfil SE Bond or Esthet-X Micro Matrix Restorative for Prime & Bond NT. The restored teeth were evaluated preoperatively and at two weeks, eight weeks and six months postoperatively for sensitivity to cold (ice), air and masticatory forces, as well as for marginal discoloration.

RESULTS

Analysis of variance revealed no statistically significant differences in postoperative sensitivity between the SE and TE materials at any recall time. Marginal discoloration was rated as "absent" for all restorations at six months. Only one tooth displayed sensitivity to occlusal forces at six months.

CONCLUSION

The SE adhesive did not differ from the TE adhesive in regard to sensitivity and marginal discoloration.

CLINICAL IMPLICATIONS

Postoperative sensitivity may depend on the restorative technique rather than on the type of dentin adhesive used.

Two-year clinical evaluation of a packable resin-based composite

BACKGROUND

Packable resin-based composites were introduced in 1998, but few clinical studies have been conducted to evaluate them. The authors conducted a clinical study to determine the two-year performance of SureFil (Dentsply DeTrey GmbH, Konstanz, Germany) packable posterior resin-based composite in Class I and II restorations.

METHODS

An operator (L.S.T.) restored 55 cavities in 36 patients (16 Class I restorations and 39 Class II restorations). After cavity preparation, she etched the enamel with 34 percent phosphoric acid, applied Prime & Bond NT (Dentsply DeTrey GmbH) to dentin and etched enamel for 20 seconds and then cured it for 20 seconds. She restored the cavity using 3- to 5-millimeter increments of SureFil. Independent examiners assessed the restorations after placement and at six months, one year and two years for color matching, marginal discoloration, marginal adaptation, secondary caries, surface texture, anatomical form and postoperative sensitivity, using the Ryge criteria.

RESULTS

The authors assessed the changes in the parameters during the two-year period using a software program with Friedman test analysis with a Bonferroni adjustment at significant level of P = .05. At baseline, 31 restorations were graded as Bravo for color match. At the six-month and one-year recall periods (n = 55), 53 restorations remained unchanged. Two restorations from the same patient fell out after one month. After two years (n = 50), there were five Bravos for surface staining and three for marginal adaptation (P < .05).

CONCLUSION

After two years of clinical service, SureFil packable resin-based composite had a success rate of 96 percent, and the authors considered it successful in Class I and II restorations.

CLINICAL IMPLICATIONS

SureFil packable resin-based composite can be successful in clinical situations with limited-sized cavities and proper application of restorative techniques.