Effect of finishing technique on the microleakage and surface texture of resin-modified glass ionomer restorative materials

Effect of protective coating agents on microleakage and flexural strength of glass ionomer cement and zirconomer. an in vitro study

PURPOSE

The objective of this study was to assess the microleakage and flexural strength of glass ionomer cement (GIC) and modified GIC (Zirconomer) when coated with protective coating agents such as COAT-IT and G-COAT plus.

METHODS

Sixty tooth specimens were grouped into two groups based on the type of restorations (GIC (n = 30) and Zirconomer (n = 30)). The samples were further divided into three subgroups (n = 10) based on the protective coating agent (Petroleum jelly, G-COAT Plus, or COAT IT) applied. This study evaluated the microleakage at the occlusal and cervical margins of class V restoration after being subjected to dye penetration and sectioning. Each specimen was viewed under a 40 × microscope and was given scores based on the depth of dye penetration. They were statistically analyzed using the Kruskal-Wallis test and compared within the groups using the Mann- Whitney Test. In addition, flexural strength was assessed using standardized cuboid (25 × 2 × 2 mm) specimens of restorative materials with and without protective coating agents. The mean flexural strength data of all the subgroups were statistically evaluated using a one-way analysis of variance (ANOVA) and compared within the subgroups using the student t test.

RESULTS

A statistically significant difference was found when occlusal margin microleakage scores were evaluated with G-COAT Plus demonstrating the lowest occlusal margin microleakage when applied over GIC restoration. The increasing order of occlusal margin microleakage scores is as follows: GIC with G-COAT Plus, Zirconomer with COAT-IT, GIC with COAT-IT, GIC, Zirconomer with G-COAT Plus, and Zirconomer. However, the cervical margin microleakage scores revealed no significant difference. While flexural strength was found to be highest for the GIC group coated with G-COAT Plus, it was observed that there was a significant improvement in the flexural strength of both GIC and Zirconomer when coated with either of the protective coating agents.

CONCLUSION

Within the limitations of this in vitro study, it was observed that the application of protective coating agents can significantly reduce the potential microleakage and improve the flexural strength of the restorative material especially when zirconia-reinforced GIC is the restorative material.

[Surface roughness, gloss and sequential polishing times of various chairside computer aided design/manufacturing restorative materials]

OBJECTIVE

To investigate the effect of polishing on surface roughness, gloss and optimum polishing time of various computer aided design/computer aided manufacturing (CAD/CAM) restorative materials and to provide a proper polishing procedure for dental clinicians.

METHODS

Five CAD/CAM restorative materials including vita mark Ⅱ (VM), vita enamic (VE), lava ultimate (LU), shofu block HC (SB) and brilliant crios (BC) were selected. Six specimens were prepared for each material. The specimen was fixed on a custom-made polishing apparatus and sequentially polished with Sof-Lex poli-shing disk system including medium disk (with abrasive particle sizes of 10-40 μm), fine disk (with abrasive particle sizes of 3-9 μm) and superfine disk (with abrasive particle sizes of 1-7 μm). Surface roughness (Ra value) and gloss value were measured every 10 seconds until the numerical values were no longer changed. Then the surface roughness, gloss value and polishing time were recorded and the specimen was moved to the next sequence of polishing. Finally, statistical analysis was performed using SPSS 24.0.

RESULTS

For all the restorative materials, the Ra values were significantly reduced (P < 0.05) and the gloss values were significantly increased (P < 0.05) after sequentially polishing with Sof-Lex disks. No significant difference was detected among Ra values of all the tested materials (P>0.05) after sequential polishing. The gloss values of LU [(68.1±4.5) GU] and BC [(68.2±5.8) GU] were significantly higher than those of VE [(48.1±8.1) GU] and BC [(53.2±5.8) GU], P < 0.05. To obtain optimal surface smoothness, VM cost the shortest polishing time [40 (30, 55) s] among all the restorative materials (P < 0.05). No significant differences in the total polishing time were observed among VE [140 (135, 145) s], LU [130 (120, 140) s], SB [140 (130, 150) s] and BC [130 (120, 140) s], P>0.05.

CONCLUSION

The surface roughness of all CAD/CAM restorative materials were decreased after sequentially polishing with Sof-Lex disk system. To obtain the smoothest surface, different types of restorative materials might need different polishing times using Sof-Lex polishing disk system. For ceramic restorative material VM, we recommend polishing only with medium disk for 40 s. For hybrid restorative material VE and composite restorative material LU, SB and BC, we recommend polishing with medium disk, fine disk and superfine disk in sequence for 130-140 s in total.

Influence of diazonium and surfactant modification of the mesoporous material on its adsorption properties

We describe a new and direct route to obtain Al-SBA-15-modified materials with different groups on their surface using diazonium salts. For comparison, modification using surfactants was also used. In the present study, we decided to examine the applicability of these materials in the adsorption of compounds released from dental fillings. The effectiveness of modification was proved by results of Fourier transform infrared spectroscopy and energy-dispersive spectrometry. The results indicate the formation of characteristic groups on the surface of the materials. The materials after modification are characterized by smaller surface area and pore volume, which is result of covering the surface with an aryl or surfactant layer. The adsorption properties change after modification and depend on the used modifier. Diazonium modification has a positive effect on sorptive properties when hydroxyl and dimethylamine groups are obtained. The methods of material modification presented in this work may in the future lead to the improvement in the properties of sorbents used in solid-phase extraction.

Press-on force during polishing of resin composite restorations

OBJECTIVE

To measure the press-on force during the polishing of composite restorations carried out by 10 dentists in a clinically simulated procedure.

METHODS

Composite restorations (Tetric EvoCeram Bulk Fill) were placed in standardized Class II two-surface cavities in first upper acrylic molars. The surfaces were roughened by sandblasting (50μm, 1bar). The tooth was mounted on a tailor-made device with a 3D force sensor (Kistler, Z21134-300, 10Hz). Ten dentists (7 male, 3 female) polished one Class II restoration each using the one-step polishing system OptraPol together with a dental handpiece and water spray. The dentists were allowed to use all shapes of the polishing system (small flame, large flame, cup, lens). During polishing, the press-on forces measured for up to 2 minutes. Simultaneously, the polishing procedure was recorded with a digital camera to correlate the forces with the polishing shapes and movements.

RESULTS

In total, 17,999 force measurements were available for analysis. The mean forces of all operators varied between 0.77(±0.63) N and 2.23(±1.48) N; the difference was statistically significant (ANOVA, post-hoc Tukey B, p<0.05). All dentists exerted maximum forces higher than 3 N (between 3.3N and 18.3N). Force values exceeded 2N during 25% of the polishing time. Female dentists polished with a statistically significant lower force than male dentists (ANOVA, p<0.001). Polishing with the large flame and the cup generated significantly higher forces than polishing with the small flame and the lens (ANOVA, post hoc Tukey B, p<0.01).

CONCLUSIONS

The press-on forces applied during polishing varied significantly between dentists and within the same dentist. In about 25% of the polishing time, forces were above the 2N limit, which is recommended by some manufacturers as the maximum polishing force. Test institutes and manufacturers should evaluate the polishing performance of polishing instruments with various press-on forces.

In vitro evaluation of microleakage in primary teeth restored with three adhesive materials: ACTIVA™, composite resin, and resin-modified glass ionomer

PURPOSE

Microleakage is one of the most important problems that can adversely affect the longevity of dental restorations. The aim of this in vitro study is to assess microleakage of a new BioActive-Restorative composite (ACTIVA™, Pulpdent, USA), in comparison to standard adhesive materials used in restoring class II cavities in primary teeth.

DESIGN

One hundred and four extracted human primary molars were randomly allocated into three groups. In each group, class II cavities were prepared and restored with one of the three restorative materials: ACTIVA, Filtek Z250, or Vitremer. Microleakage was assessed using dye penetration method under a stereomicroscope. Chi-square test was used followed by pairwise comparisons to assess the association between microleakage and the materials used. A significance level of 0.05 was assumed throughout the study.

RESULTS

According to leakage analysis per tooth, there were no statistically significant differences in microleakage percentages between ACTIVA and both Filtek Z250 and Vitremer. Leakage analysis per surfaces showed significantly higher leakage percentages in ACTIVA compared to Filtek Z250 at both occlusal and cervical margins and lower than Vitremer at occlusal margin.

CONCLUSION

ACTIVA can be a potential restorative material in class II cavities in primary molars; clinical studies are recommended.

Effect of protective coating on microleakage of conventional glass ionomer cement and resin-modified glass ionomer cement in primary molars: An In vitro study

Aim

The aim of this in vitro study was to evaluate and compare the effect of protective coating G-Coat Plus on microleakage of conventional glass ionomer cement (CGIC) and resin-modified glass ionomer cement (RMGIC) in primary molars.

Materials and Methods

A total of 120 samples were divided into four groups with 30 samples in each group. Group A - teeth restored with CGIC. Group B - teeth restored with CGIC coated with G-Coat Plus. Group C - teeth restored with RMGIC. Group D - teeth restored with RMGIC coated with G-Coat Plus. Microleakage was tested using 2% basic fuschin dye penetration and measured at ×40 original magnification under the stereomicroscope.

Results

The results of this in vitro study showed that coating with G-Coat Plus showed a reduction in microleakage in CGIC and complete absence of microleakage in RMGIC when compared to the noncoated groups, which was statistically significant. CGIC without G-Coat Plus showed highest microleakage followed by RMGIC without G-Coat Plus, followed by a relatively less microleakage in CGIC with G-Coat Plus.

Conclusion

Significant reduction in microleakage was seen in conventional GIC and RMGIC with G-Coat Plus when compared to conventional GIC and RMGIC without G-Coat Plus.

Effect of finishing/polishing techniques and time on surface roughness of esthetic restorative materials

Background

Surface roughness associated with improper finishing/polishing of restorations can result in plaque accumulation, gingival irritation, surface staining, and poor esthetic of restored teeth. The study aimed to evaluate the efficiency of various finishing and polishing systems and time using various procedures on surface roughness of some esthetic restorative materials.

Materials and Methods

In this in vitro study, samples of two composite materials, compomer and glass ionomer cement (GIC) materials, were fabricated. Finishing and polishing were done immediately (n = 40) and after 1 week (n = 40) using four systems (diamond bur + soflex discs; diamond bur + Astropol polishing brush; tungsten carbide bur + soflex discs; tungsten carbide bur + Astropol polishing brush). Surface roughness was measured using surface profilometer. Data were statistically analyzed by t-test (for each material and time period) and one-way analysis of variance followed by Tukey's post hoc (for finishing and polishing systems) at a significant level of P < 0.05.

Results

Analysis of time period, irrespective of finishing and polishing system showed that Ra values were greater (P < 0.05) in delayed polishing in GIC > Z100 > Filtek P90 > Dyract AP, suggesting immediate polishing is better. Among the materials, Filtek P90 had the least Ra values indicating the smoothest surface among all materials, followed by Z100, Dyract AP, and GIC. Comparison of polishing and finishing systems irrespective of materials showed that Ra values were lower (P > 0.05) in diamond + Astropol combination whereas diamond + soflex had the greatest Ra values.

Conclusion

It might be concluded that: (i) Filtek P90 showed least Ra values followed by < Z100 < Dyract < GIC; (ii) immediate (24 h) finishing/polishing of materials is better than delayed; and (iii) among all these polishing systems, diamond bur-Astropol and Astrobrush showed good surface finish.

Surface Roughness of Nanofill and Nanohybrid Composite Resin and Ormocer-based Tooth-colored Restorative Materials after Several Finishing and Polishing Procedures

The purpose of this study was to evaluate the effect of several finishing and polishing procedures on the surface roughness of nanofill and nanohybrid composites and ormocer-based dental restorative materials. The materials included a nanofill composite (Supreme); a nanohybrid composite (Grandio); and an ormocer (organically modified ceramic) (Admira). Forty specimens of each material were prepared using a Mylar strip (polyester strip) and randomly divided into four finishing and polishing groups (n 1/4 10): (I) Diamondbur/Super-snapRainbowTechniqueKit(Al2O2-coated, graded abrasive discs); (II) Diamond bur/Astropol and Astrobrush system (silicone abrasive polishers and brush system); (III) Tungsten carbide bur/Super-snap Rainbow Technique Kit; and (IV) Tungsten carbide bur/Astropol and Astro-brush system. The average surface roughness (Ra) in micrometers was measured using a “Mahr Perthometer S4P” Surface Roughness Tester and the data were compared using ANOVA at P 0.05. The results of this study indicated that the Mylar strip produced the smoothest surface on all materials and among the finishing-polishing methods the first and the third methods performed significantly smoother surfaces than the second and the fourth methods for the three restoratives. Ormocer (Admira) performed the lowest variability in initial surface roughness among the tested materials.This study has shown that Super-snap abrasive discs produced a smoother surface than the Astropol and Astrobrush silicone polishers for composite and ormocer-based restorative materials, but the results would be valid clinically for readily accessible and flat surfaces i.e., not for all areas in the mouth. Therefore silicone polishers are necessary for posterior areas and for concave and convex surfaces.

Effect of two prophylaxis methods on marginal gap of Cl Vresin-modified glass-ionomer restorations

Background. This study evaluated the effect of two prophylaxis techniques on the marginal gap of CI V resin-modified glass-ionomer restorations.

Methods. Standard Cl V cavities were prepared on the buccal surfaces of 48 sound bovine mandibular incisors in this in vitro study. After restoration of the cavities with GC Fuji II LC resin-modified glass-ionomer, the samples were randomly assigned to 3 groups of 16. In group 1, the prophylactic procedures were carried out with rubber cup and pumice powder and in group 2 with air-powder polishing device (APD). In group 3 (control), the samples did not undergo any prophylactic procedures. Then the marginal gaps were measured. Two-way ANOVA was used to compare marginal gaps at the occlusal and gingival margins between the groups. Post hoc Tukey test was used for two-by-two comparisons. Statistical significance was set at P < 0.05.

Results. There were significant differences in the means of marginal gaps in terms of prophylactic techniques (P < 0.001), with significantly larger marginal gaps in the APD group compared to the pumice and rubber cup group, which in turn exhibited significantly larger marginal gaps compared to the control group (P < 0.0005). In addition, the means of marginal gaps were significant in terms of the margin type (P < 0.001), with significantly larger gaps at gingival margins compared to the occlusal margins (P < 0.0005).

Conclusion. The prophylactic techniques used in this study had a negative effect on the marginal gaps of Cl V resin-modified glass-ionomer restorations.

Effect of finishing and polishing on color stability of a nanofilled resin immersed in different media

OBJECTIVE: The purpose of this study was to evaluate the effect of finishing and polishing on color stability of a nanofilled composite resin (Filtek Z350 XT) according to different immersion media.MATERIAL AND METHOD: Composite disks (10 mm diameter, 2 mm thickness) were prepared for each group (n = 6) using a stainless steel mold. The groups were divided according to the presence or absence of finishing and polishing procedure and immersion media (artificial saliva, artificial juice- KAPO(r) Coca-Cola(r)flavors: pineapple, orange, strawberry and grape). The finishing and polishing procedures were performed using Super -Snap(r) disks. The specimens were stored in artificial saliva for 24 hours (baseline) and were analyzed using a color spectrophotometer by CIELab system. Then, they were immersed in different media for 5 minutes, 3 times a day, every 4 hours during 60 days. They were stored in artificial saliva at 37 ± 1°C during the immersion intervals. After this time, new measure of color was performed. The data were analyzed using Kruskall-Wallis test and Mann- Whitney test. The significance level was 5%.RESULT: The results showed that the finishing/polishing not significantly influence the color stability of resin composite (p > 0.05). There was no statistically significant difference in the color stability of the studied resin after immersion in different media (p > 0.05).CONCLUSION: The finishing and polishing procedures and the immersion media did not have influence on color stability of nanofilled resin Filtek Z350 XT.

Roughness and morphology of composites: influence of type of material, fluoride solution, and time

This study evaluated the effect of fluoride solutions on surface roughness and morphology of composites in the short and long term. Specimens were randomly assigned to experimental groups (n=5) according to type of composite (nanofilled, microhybrid, microfilled) and immersion media (artificial saliva, 0.05% sodium fluoride solution, Fluordent Reach, Oral-B, and Fluorgard). Roughness was evaluated at time intervals: T 0 after 24 h in artificial saliva (baseline); T 60 after being in assigned immersion media for 1 min daily over 60 days; and T final after artificial aging (20,000 thermal cycles, 1,200,000 mechanical loading cycles, and continuous immersion for 1,825 min). Surface morphology was qualitatively analyzed by scanning electron microscopy (SEM) at T 60 and T final. Roughness data were submitted to analysis of variance for mixed repeated measures, Sidak, and Tukey tests at α=0.05. Micro-filled resin showed the highest roughness values. Fluoride solutions had no influence on roughness. Higher roughness values were observed after artificial aging. In SEM observations after the artificial aging, the specimens showed surface degradation, irrespective of immersion medium or type of composite. Nano-filled resin showed higher loss of resin matrix and protrusion of filler particles. Roughness was not influenced by fluoride solutions; however, it is material dependent and increases over time.

Comparative evaluation of microleakage of three restorative glass ionomer cements: An in vitro study

Purpose:

The aim of this study was to compare the microleakage of glass ionomers (conventional and resin modified) with that of recently introduced nanoionomers.

Materials and Methods:

Standardized class I and class V cavities were prepared on 120 young permanent teeth. Samples were equally divided into group I (class I restorations) and group II (class V restorations), and further divided into subgroups. The subgroups were restored with Fuji IX, Fuji II LC, and newly introduced Ketac^™ N 100 (KN 100). Samples were thermocycled and submerged in Acridine dye for 24 h. Samples were sectioned to view under fluorescent microscope and marginal leakage was evaluated by Chi-square and Kruskal — Wallis test.

Results:

Fuji IX showed the maximum leakage, followed by LC II and the least was observed in KN 100. In class I restorations, there was significant difference while comparing Fuji IX with Fuji LC II and KN 100 and nonsignificant difference between LC II and KN100. In class V restorations, Fuji IX and KN100, KN 100 and LC II showed significant difference. Fuji IX and LC II showed nonsignificant difference.

Conclusion:

Within the limitations of this study, Fuji IX showed the maximum microleakage. KN 100 showed minimum leakage, better sealing ability, and was more consistent.

A Comparative Evaluation of Microleakage of Glass Ionomer Cement and Chitosan-modified Glass Ionomer Cement: An in vitro Study

OBJECTIVE

To do a comparative study of microleakage of glass ionomer cement (GIC) and chitosan modified glass ionomer cement and evaluate which exhibited lesser microleakage.

MATERIALS AND METHODS

Sixty freshly extracted sound primary molar teeth were obtained. Two groups of samples were created for the study which comprised of group I (glass ionomer cement-GIC) and group II (Chitosan modified glass ionomer cement). Class V cavities were prepared on the buccal surfaces. All the tooth surfaces except the restoration and a 1 mm zone adjacent to its margins were covered with two coats of varnish. The specimens were then immersed in 2% basic fuschin dye solution for 24 hours. The teeth were sectioned into two halves buccolingually in an occlusoapical direction. Sections were viewed under stereomicroscope and the degree of microleakage was evaluated using specific scoring criteria. For comparative evaluation of microleakage scores between glass ionomer cement and chitosan modified cement, a nonparametric Mann-Whitney statistical analysis was done.

RESULTS

Statistical analysis showed no significant differences between groups I and II with the p-value at >0.05.

CONCLUSION

Chitosan modified GIC holds great promise for general dentistry as a future restorative material with microleakage properties similar to or better than GIC. How to cite this article: Abraham D, Thomas AM, Chopra S, Koshy S. A Comparative Evaluation of Microleakage of Glass Ionomer Cement and Chitosan-modified Glass Ionomer Cement: An in vitro Study. Int J Clin Pediatr Dent 2014;7(1):6-10.

Experimental initial partial polymerization method for Fuji II placement evaluated for microleakage with/without Fuji Coat

PURPOSE

This laboratory study evaluated an experimental 1-second initial partial polymerization (IPP) technique using Fuji II LC vs the manufacturer's standard placement (control), both with and without Fuji Coat, relative to microleakage.

METHODS

Class V restorative preparations were placed on the buccal and lingual aspects of 30 permanent, caries-free and restoration-free, third molar teeth. Fuji II LC restorations were placed either following manufacturer-specified guidelines or IPP for 1 second prior to contouring and full light curing. Half of the restorations were placed using the IPP experimental technique and half of the teeth were finished using Fuji Coat LC. Following thermocycling, specimens were sectioned and dye penetration was measured. SPSS 16 was used for statistical analysis (p<0.05).

RESULTS

Mean microleakage results: experimental/varnish (0.08 ± 0.15 mm), control/varnish (0.17 ± 0.35 mm), experimental/nonvarnish (0.33 ± 0.33 mm), and control/nonvarnish (0.58 ± 0.47 mm). Univariate analysis of variance demonstrated significantly less microleakage for the experimental technique (p<0.001), use of finishing varnish (p<0.001), and the combination of experimental/varnish (p=0.013).

CONCLUSIONS

The initial partial polymerization technique of Fuji II LC placement significantly reduces microleakage. Fuji Coat LC results in further diminished microleakage.

Evaluation of the Microleakage of Chlorhexidine-Modified Glass Ionomer Cement: An in vivo Study

AIM

Recent advances including the incorporation of antibacterial substances, such as chlorhexidine, into restorative materials such as glass ionoer cement (GIC), might alter the physical properties of the material, which might affect the marginal seal of the restorations. Hence, the objective of this study was to compare the marginal sealing ability of GC Fuji IX modified with 1% chlorhexidine diacetate and conventional GC Fuji IX.

MATERIALS AND METHODS

Sixty healthy molars were selected from the oral cavities of 30 children. The teeth were divided into two groups: Group I, teeth restored with 1% chlorhexidine diacetate modified GC Fuji IX and group II, teeth restored with GC Fuji IX. The restored teeth were extracted following 4 weeks and immersed in 2% basic fuchsin solution for 24 hours. They were then sectioned and scored under a light microscope of 10 × 10 magnification for dye penetration.

RESULTS

On statistical analysis difference between Chlorhexidine-Modified GIC group and GIC group with regard to grade of microleakage was found to be statistically nonsignificant (p = 0.543).

CONCLUSION

Since, addition of 1% chlorhexidine diacetate to GC Fuji IX showed comparable results with regard to microleakage, it can be considered a valuable alternative especially in atraumatic restorative treatment and for general clinical utility in restorative dentistry. How to cite this article: Mathew SM, Thomas AM, Koshy G, Dua K. Evaluation of the Microleakage of Chlorhexidine-Modified Glass Ionomer Cement: An in vivo Study. Int J Clin Pediatr Dent 2013;6(1):7-11.

Review: Finishing and polishing procedures of (resin-modified) glass ionomers and compomers in paediatric dentistry

BACKGROUND

A smooth surface has a beneficial effect on the aesthetic quality and longevity of a dental restoration, as well as on its biocompatibility with oral tissues. In this review studies on glass-ionomer cements (GIC), resin-modified glass-ionomer cements (RM-GIC), and compomers or polyacid-modified resin composites (PAM-C) were assessed as these are currently used in paediatric dentistry.

METHOD

Medline databases (USA National Library of Medicine) was searched using WinSpirs and Pubmed. This search used a keyword filter including dental materials, polishing procedures, and instrumentation including influencing factors.

FINDINGS

Although the literature shows different commercially available tools it seems that the ideal polishing instrumentation in paediatric dentistry for GIC and compomers is not yet on the market. Furthermore, the constant development of dental materials and polishing products impose a need for continuous scientific research.

Surface texture and roughness of polished nanofill and nanohybrid resin composites

Nanofiller-containing resin composites have gained appreciable market share in dentistry due to their claims of high mechanical strength and low polymerization contraction. In this study, the polishability of one nanofill (Filtek Supreme XT/FIL) and three nanohybrid materials (Grandio/GRA, Tetric EvoCeram/TET, Venus Diamond/VED) was investigated using surface profilometry and SEM. After the specimens were cured under a Mylar strip or pre-ground with 600-grit SiC paper, three polishing systems were applied and their polishing effects compared: diamond polishing points, a diamond paste, and urethane-backed aluminum oxide disks. Except for the profilometry results obtained by glass filler-containing GRA and VED with one polishing system that comprised the consecutive application of diamond particles and a diamond polishing paste, the final roughness (Ra) of all other specimens were lower than the clinically acceptable 0.2 microm threshold. The surface textures of the polished nanofill FIL and nanohybrid TET were uniformly smooth, whereas relief polishing effects and filler extrusion of varying extents were seen on the nanohybrid composites GRA and VED.

Glass ionomer cements and their role in the restoration of non-carious cervical lesions

Glass ionomer based materials are clinically popular in several areas of restorative dentistry, but restoration of cervical lesions has proven particularly successful. Various etiologies, conformations, locations and structural characteristics make non-carious cervical lesions more challenging to adhesive restorative procedures and marginal seal in the long run. Due to their characteristics, glass ionomer cements (GICs) have precise indication for these cases. Moreover, the use of a GIC base underneath composite resin, the so-called "sandwich" or mixed technique, allows associating the good characteristics of composite resins and GICs, and has been considered quite useful in the restoration of non-carious cervical defects. The aim of this paper is to critically review the literature and discuss peculiar features of GICs regarding their role in the restoration of non-carious cervical lesions.

Effect of dental finishing instruments on the surface roughness of composite resins as elucidated by atomic force microscopy

Roughness increases significantly after finishing procedures. The aim of this study was to assess by the atomic force microscope (AFM) the effect of finishing instruments on the surface roughness of composite resins. A nanofiller composite resin (Filtek Supreme, 3M-F) and a microhybrid composite resin (Point 4, Kerr-P) were selected. The finishing procedures were done with a 30-blade carbide bur (C) and a 30-microm finishing diamond bur (D). Standardized specimens were produced and divided into six experimental groups (n=4) according to (1) composite resin, (2) absence of finishing (Mylar matrix-M), and (3) finishing instrument (FM, PM, FC, FD, PC, PD). The mean surface roughness was evaluated by AFM in the contact mode. FM and PM groups were assessed statistically by the Student's T test, and FC, FD, PC, PD groups were submitted to variance analysis (ANOVA), both at 5% significance. The mean surface roughness values, in nanometers, were FM, 23.63 (b); FC, 283.88 (c); FD, 510.55 (d); PM, 12.52 (a); PC, 343.98 (c); PD, 531.64 (d). Microhybrid composite displayed less roughness than nanofiller composite in the absence of finishing procedures. The 30-blade carbide bur produced less roughness compared to the extra fine diamond bur.

The Effect of Polishing Techniques and Time on the Surface Characteristics and Sealing Ability of Resin Composite Restorations After One-year Storage

The results of this study suggest that immediate polishing procedures can result in improved short-term surface smoothness results but do not influence smoothness or sealing ability after one-year storage.

The Influence of One-step Polishing Systems on the Surface Roughness and Microhardness of Nanocomposites

One-step polishing systems exhibited similar or better surface roughness values when compared to multi-step polishing systems. In all groups, mylar-strip created surfaces showed lower microhardness values than polished surfaces. Different polishing procedures did not effect the microhardness of nanocomposites. One-step polishing systems may be a good choice for polishing nanocomposites, resulting in reduced chair time.

Evaluation of surface characteristics of dental composites using profilometry, scanning electron, atomic force microscopy and gloss-meter

The aim of this in vitro investigation was to compare various roughness and topography measurement methods to characterize the surface quality in several types of resin composites. The initial surface quality of several resin composites was compared. The materials evaluated were of three categories: i) hybrid: TPH Spectrum; ii) reinforced microfill: Micronew and iii) microhybrid: Synergy Duo, Esthet-X, Point.4 and Palfique Estelite. Three Groups of identical disk-shaped specimens (10 x 1.5 mm) were prepared from each material (n = 6) and polished with Soflex discs. Macro-roughness (Ra) was measured with Group 1 by 2-D profilometry. Atomic Force Microscopy (AFM) gave 3-D images and micro-roughness (Ra) of Group 2. Surface optical gloss at 60 degrees was determined for Group 3. Specimens of each material were also studied by scanning electron microscopy. Macro-Ra values (microm) ranged from 0.30 to 0.56. Micro-Ra values ranged from 0.03 to 0.14 and they differed from macro-Ra values in ranking order. Percentage Gloss values ranged from 30.6 to 70.1%. The results revealed that micro-roughness showed a high correlation with gloss values (r = 0.93), whilst macro-roughness did not (r = 0.62). Moreover, the AFM method showed higher capability to distinguish surface roughness compared with the 2-D profilometry and to reveal more detailed definition of surface texture than the examination under SEM.

Surface characteristics of aesthetic restorative materials ? an SEM study

To determine the degree of surface roughness of glass-ionomer cements (GICs) and polyacid-modified resin composite (PAMRC) after polishing and immersion in various foodstuffs. Three tooth-coloured restorative materials were used: a PAMRC (F2000), a conventional glass-ionomer cement (CGIC) (Fuji IX) and a resin-modified glass-ionomer cements (RM-GIC) (Fuji II LC). Disk-shaped specimens were prepared and tested with either a plastics matrix finish or after polishing with wet silicon carbide papers up to 2000-grit. All specimens were immersed in 37 degrees C-distilled water for 1 week, followed by three different foodstuffs (red wine, coffee or tea) for a further 2 weeks. Replicas of specimens were prepared by taking polyvinyl siloxane impressions, casting in epoxy resin, gold sputter-coating and examining using a Field-Emission Scanning Electron Microscope. The polished and matrix finish specimens of F2000 showed many microcracks at low magnification, and eroded surfaces with missing and protruding particles at high magnification in the polished specimens. The surface-polished specimens of Fuji II LC were considerably rougher than the matrix-finish specimens, with large voids and protruding filler particles. The effects of foodstuffs on Fuji II LC and F2000 were not noticeable. The CGIC became noticeably rougher after exposure to coffee and tea. All specimens had the smoothest surface when they were cured against a plastics matrix strip, and all materials had a rougher surface after polishing. None of the foodstuffs produced a perceptible increase in roughness on RM-GIC and PAMRC surfaces, whereas coffee and tea markedly increased the surface roughness of Fuji IX.

Adhesiveness of dental resin-based restorative materials investigated with atomic force microscopy

This study aimed to show that the polymerization contraction of dental methacrylate-based materials, when used as adhesives on hard substrate, produces voids at the material-substrate interface. This phenomenology is closely related with the nanoleakage and the sealing ability of these materials. One prime/bond system, three restorative composite resins, and one orthodontic bonding system were cured by using mirror-like glass slides as a compliance-free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam-scanning method. Nanoperiodic structure of three-dimensional (3D) images, section analysis, and roughness characteristics (R(a) and R(z)) indicated that polymerization contraction produced voids at the interface. When the adhesive surface was exposed to oral simulating fluids (water, ethanol, and lactic acid solutions), hydrolytic degradation involved some hundreds of nanometers in depth. In visible light-cured (VLC) materials, the interface porosity decreased when an irradiation pause ( approximately 2 min) was carried out during gelation.

Effect of polishing systems on the surface roughness of microhybrid composites

PURPOSE

This study was undertaken to examine the effect of three different polishing systems on surface roughness of five newly developed resin composites.

MATERIALS AND METHODS

Three microhybrid composites (Point 4, Kerr, Orange, CA; Esthet-X, Dentsply/Caulk, Milford, DE; Vitalescence, Ultradent, South Jordan, UT, USA), one microfilled composite (Renamel Microfill, Cosmedent, Chicago, IL, USA), and one experimental microhybrid composite (FZB, Ivoclar Vivadent, Schaan, Liechtenstein) were light cured with a Mylar strip. Fifteen specimens of each composite (6 mm in diameter and 3 mm in depth) were fabricated and randomly assigned to three groups. Specimens in each group were finished with a carbide bur (16 fluted) and three polishing systems (Astropol, Ivoclar Vivadent; Diagloss, Axis Dental, Irving, TX, USA; Sof-Lex, 3M, ESPE, St. Paul, MN, USA). The average surface roughness (Ra) and the mean peak spacing (Sm) were measured with a surface profilometer after polishing. Five tracings at different locations on each specimen were made. Data were analyzed by analysis of variance.

RESULTS

For Astropol, Ra ranged from 0.10 to 0.15 microm and Sm ranged from 24 to 40 microm for the five composites; for Diagloss, Ra ranged from 0.24 to 0.34 microm and Sm from 38 to 74 pm; for Sof-Lex, Ra ranged from 0.06 to 0.10 microm and Sm ranged from 16 to 22 microm. Significant differences between materials and polishing systems were observed. Polishing systems had the most important role in determining the surface roughness of resin composites.

CLINICAL SIGNIFICANCE

Of the polished systems tested, Sof-Lex discs provided the lowest roughness for polishing microfilled and microhybrid composites, and the microfilled resin composite showed the lowest roughness.

Effects of four prophylaxis pastes on surface roughness of a composite, a hybrid ionomer, and a compomer restorative material

PURPOSE

This study was undertaken to compare the effects of three prophylaxis pastes (Nupro with coarse, medium, or fine pumice) with a new paste (Clinpro with perlite) on the surface roughness of a resin composite (Dyract AP), a hybrid ionomer (Fuji II LC), and a compomer (TPH Spectrum).

MATERIALS AND METHODS

Twenty disks (2 mm thick x 10 mm in diameter) of each material were prepared in split molds and stored for 24 hours at 37 degrees C in a 100% relative humidity humidistat. Baseline Mylar surface roughness values were determined. A single operator polished each specimen for 10 seconds with each paste. Five tracings of each specimen of surface roughness (Ra, microm) were made using a surface profilometer. Means and standard deviations were calculated, and analyzed by two-way analysis of variance (three restorative materials and four prophylaxis pastes as factors) and compared using Tukey-Kramer intervals calculated at the 0.05 level of significance.

RESULTS

Analysis of variance showed significant differences among restorative materials (after polishing) and prophylaxis polishing agents. Tukey-Kramer intervals for comparisons were 0.04 and 0.05 microm, respectively. All polishing agents produced significant increased roughness compared with baseline, yielding the following results (X + SD, microm) for the three restorative materials (Fuji II LC, TPH Spectrum, Dyract AP): perlite, 0.16 +/- 0.07, 0.28 +/- 0.26, 0.79 +/- 0.64; course pumice, 0.36 +/- 0.17, 0.48 +/- 0.25, 0.88 +/- 0.46; medium pumice, 0.26 +/- 0.10, 0.35 +/- 0.30, 0.46 +/- 0.21; and fine pumice, 0.16 +/- 0.06, 0.34 +/- 0.30, 0.42 +/- 0.24). Fine pumice and perlite produced the least roughness on the hybrid ionomer, medium and fine pumice on the resin composite, and perlite on the compomer.

CLINICAL SIGNIFICANCE

Since prophylaxis pastes have the potential to increase the surface roughness of resin composite, hybrid ionomer, and compomer restorative materials, routine polishing during prophylaxis should be avoided.

Conference report. Direct adhesive materials: current perceptions and evidence--future solutions

This paper reports the proceedings, including the consensus views of an Australasian expert group convened to consider current perceptions, evidence and future solutions in the field of direct adhesive materials. This group, in anticipating a trend to preservative dentistry, formed the view that caries risk assessment should increasingly influence the selection of restorative materials. In low caries risk patients, aesthetic demands typically favour the use of resin-based composites. Interactive (biomimetic) materials based on glass-ionomer chemistry have particular application in high caries risk patients. Teaching in dental schools, continuing education programmes and research, both in the laboratory and in the clinical environment should be more attuned to the ever-increasing use of tooth-coloured restorative materials in everyday clinical practice. Linked to this trend are changes in patient--dentist relationships, whereby patients should be encouraged to become more involved in treatment decision-making. Expert group meetings are suggested to be of value in addressing some of the shortfall between the need for good evidence and the relentless challenge of the introduction of new products and concepts in the field of direct adhesive materials.