Surface characteristics of finished posterior composite resins

Comparative evaluation of mechanical and physical properties of a new bulk-fill alkasite with conventional restorative materials

PURPOSE

The physical and mechanical performance of a newly commercialized dental restorative material (alkasite) was compared with glass ionomer cement (GIC) and nano-hybrid composite.

METHODOLOGY

Human extracted premolars were used to investigate the shear bond strength. Restorative materials were placed on the dentine surface and were aged in deionized water for 14 days. The 3-D surface roughness was evaluated before and after chewing simulation cycles (50,000). The samples were fatigued mechanically using a chewing simulator and investigated with a scanning electron microscope (SEM).

RESULTS

For shear bond strength, alkasite showed significantly high values than GIC, whereas non-significant difference was observed between alkasite and nano-hybrid composite. After the chewing simulation (50,000 cycles), non-significant difference was found between GIC and nano-hybrid composite, where surface roughness values were highest for GIC and lowest for alkasite.

CONCLUSION

The newly developed restorative material (alkasite) has shown better results than existing restorative materials.

Biofilm formation affects surface properties of novel bioactive glass-containing composites

OBJECTIVES

This study investigated the effects of bacterial biofilm on the surface properties of novel bioactive glass (BAG)-containing composites of different initial surface roughness.

METHODS

BAG (65 mol% Si; 4% P; 31% Ca) and BAG-F (61% Si; 31% Ca; 4% P; 3% F; 1% B) were synthesized by the sol-gel method and micronized (size ∼0.1-10 μm). Composites with 72wt% total filler load were prepared by replacing 15% of the silanized Sr glass with BAG, BAG-F, or silanized silica. Specimens (n=10/group) were light-cured and divided into 4 subgroups of different surface roughness by wet polishing with 600 and then up to 1200, 2400, or 4000 grit SiC. Surface roughness (SR), gloss, and Knoop microhardness were measured before and after incubating in media with or without a Streptococcus mutans (UA 159) biofilm for 2 weeks. Results were analyzed with ANOVA/Tukey's test (α=0.05).

RESULTS

The SR of the BAG-containing composites with the smoothest surfaces (2400/4000 grit) increased in media or bacteria; the SR of the roughest composites (600 grit) decreased. The gloss of the smoothest BAG-containing composites decreased in bacteria and media-only, but more in media-alone. The microhardness of all of the composites decreased with exposure to media or bacteria, with BAG-containing composites affected more than the control.

SIGNIFICANCE

Exposure to bacterial biofilm and its media produced enhanced roughness and reduced gloss and surface microhardness of highly polished dental composites containing a bioactive glass additive, which could affect further biofilm formation, as well as the esthetics, of restorations made from such a material.

Comparison of two-step versus four-step composite finishing/polishing disc systems: evaluation of a new two-step composite polishing disc system

OBJECTIVE

The purpose of this study was to evaluate surface finish and gloss of a two-step composite finishing/polishing (F/P) disc system compared with two multistep systems on five composites.

METHODS

Seventy-five disc-shaped composite specimens (D=10.0 mm, 2 mm thick, n=15 per composite) were made of microfill (Durafill-D), nanofill (Filtek Supreme-FS), nanohybrid (Premise-PR), and microhybrids (Filtek Z250-FZ, Esthet-EX). One side of each specimen was initially finished with a carbide bur. Five specimens of each resin composite were randomly assigned to receive full F/P by each of the disc systems: two-step (Enhance Flex NST-EF) and four-step (Sof-Lex-SL, Super-Snap-SS). Surface gloss was measured with a glossmeter and surface roughness was measured with a profilometer. Results were analyzed by two-way analysis of variance (ANOVA)/Tukey's (α<0.05).

RESULTS

No difference in gloss was noted among the three F/P systems when used with D and EX; no difference between SL and EF when used with any composite, except for FS; and no difference between SL and SS when used with any composite. SL and EF showed similar surface roughness when used on all composites, except for EX. EF and SS showed similar surface roughness on PR. SL and SS showed similar surface roughness values on every composite, except for FZ.

CONCLUSIONS

EF was capable of providing similar gloss and surface roughness to SL on four composites evaluated but was not able to produce as glossy or as smooth a surface as SS for three of the five composites.

Surface Texture of Four Nanofilled and One Hybrid Composite After Finishing

Compared to a hybrid composite, with one exception, nanocomposites were significantly smoother after finishing with rigid rotary instruments and after using Sof-Lex discs. Using a 30 μm diamond caused detrimental surface alteration on nanofiller and hybrid composites.

Perioesthetic Approach to the Diagnosis and Treatment of Carious and Noncarious Cervical Lesions: Part II

Several classes of tooth-colored materials are available for restoring carious and noncarious cervical lesions. Included are the composite resins, which can be bonded into the cervical area to provide predictable form, function, and esthetics. Part I of this two-part report reviewed the etiology of noncarious cervical lesions and provided a series of clinical case reports showing the importance of the periodontal aspect of lesion management. In part II we present information about adhesive preparation design and esthetic restoration of the noncarious cervical lesion.

CLINICAL SIGNIFICANCE

When used with proper attention to preparation design and restoration placement and finishing, resin composites can be used to successfully restore form, function, and esthetics to defective cervical areas of teeth.

Surface roughness of glass-ceramic insert-composite restorations: assessing several polishing techniques

The authors compared the effectiveness of seven polishing methods on glass-ceramic insert-composite restorations placed in plastic resin squares. The polishing methods used carbide dental finishing burs and diamond polishing paste, diamond abrasive finishing burs and diamond polishing paste, diamond abrasive finishing burs and composite resin finishing disks, diamond abrasive finishing burs and composite resin polishing points, diamond abrasive finishing burs only, diamond abrasive finishing burs followed by resin impregnated disks and an aluminum oxide polishing abrasive paste, and diamond abrasive finishing burs followed by diamond polishing paste. All systems achieved comparable smoothness except the carbide finishing burs, which damaged the insert-composite margin.

Cutting effectiveness of diamond points on commercial core composite resins and cements

In dental clinics, composite resin and cement cores are routinely cut and polished during abutment tooth preparation. To identify their characteristics during cutting, weight-load cutting tests were performed on eight commercial core composites and two cements, using diamond points driven by an air-turbine handpiece. It became evident that the cutting effectiveness of the diamond points on nine workpieces exceeded that on natural tooth dentine, while that on one composite containing Si3,N4 filler was analogous to that on dentine. With continued use, the cutting effectiveness of the diamond point on all workpieces gradually declined. SEM observations revealed that diamond particles of the diamond point wore out with repeated use. It is clinically advised to select the core material with material characteristics during cutting and mechanical strength similar to those of dentin.

Effects of finishing and polishing procedures on the surface texture of resin composites

OBJECTIVES

This study was designed to investigate the effects of finishing and polishing procedures on the roughness and color of resin composite surfaces.

METHODS

Four composites and three different polishing systems were evaluated. Forty disc (10 mm x 2 mm) specimens of each composite were prepared. Thirty of them were ground wet through 320-grit paper, and the ground surfaces were used as the base line for the finishing procedure. Ten Mylar-covered specimens were used as controls. A color meter was applied to determine the color differences and a roughness meter was used to measure the surface roughness (Ra).

RESULTS

Microfilled composite demonstrated significantly less roughness (p < or = 0.01) than hybrid composite systems as tested by ANOVA and Scheffé's tests. Polishing procedures produced a decrease in the roughness, ranging from 26 to 74%. Relative to the shade guide, the mean color difference values for all the composites after polishing were significantly greater than for the controls (p < or = 0.01) and ranged from 1.08 to 8.15 units. A positive relationship between mean color differences and Ra values was determined by regression analysis (r = 0.55).

SIGNIFICANCE

A Mylar strip can create a smoother surface than the other types of tested polishing procedures. Because of the greater values in color differences and surface roughness, the shades of tested resin composites were lighter after the polishing procedures. A custom-made shade guide is suggested based on the results of this study.

Quantitative analysis of six composite polishing techniques on a hybrid composite material

Determining the best technique for finishing and polishing composite resins is important to ensure longevity of the restoration and prevention of recurrent decay and periodontal disease. This study quantitatively compared the surface roughness of a small particle hybrid composite material finished and polished using six different techniques. Five composite samples were randomly assigned to one of six polishing techniques. Uniform composite surfaces were prepared by finishing samples with a 600-grit carborundum disk prior to polishing. The unpolished surfaces were analyzed with the Taylor-Hobson Talysurf 10 surface texture measuring instrument. The surfaces were then polished and analyzed again. There were no statistical differences among treatment groups prior to polishing. There was a statistical difference between treatment groups after polishing. The smoothest surfaces were obtained using Centrix System rubber points alone, Centrix System rubber points plus Caulk's Prisma Gloss fine and super-fine pastes, and Caulk's Enhance disks plus Caulk's Prisma Gloss fine and super-fine pastes. There was no statistical difference between these methods and 3M Sof-flex disks alone. The roughest surface was produced by the Enhance disks only without using the Prisma Gloss pastes. There was no statistical difference between this method, however, and the use of Sof-flex disks plus Kerr's Lustre Paste. Lustre Paste, included with Herculite kits, did not improve a surface polished with Sof-flex disks.

Three composite finishing systems: a multisite in vitro evaluation

Selection of appropriate finishing and polishing devices is critical to the optimal appearance and longevity of composite resin restoratives. This report compares the effectiveness of three specific finishing and polishing systems when used to prepare the surfaces of composite restorative materials provided by the respective manufacturers. Profilometer surface roughness analyses were conducted at two separate laboratories to cross-correlate numerical smoothness data in this study. Statistically significant differences in mean surface roughness were found between various finishing system/composite resin pairings. Surprisingly, a hybrid composite resin finished and polished with its respective finishing/polishing system gave a significantly smoother surface than a microfill composite surface prepared with its corresponding sequentially coated abrasive disc system. This finding was corroborated at a second site using a separate methodology for profilometer analysis.

Characterization of inorganic fillers in visible-light-cured dental composite resins

Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.

Direct posterior composite resin restorations: a review. 2. Clinical technique

Despite the increased use of composite resin to restore posterior teeth, there is evidence that clinicians should be selective in their use of these restorations. This paper describes the clinical technique--preparatory procedures, preparation of the cavity, preparation for placement of composite resin, placement of composite resin and finishing of the restoration--for the relatively conservative use of composite resin in posterior teeth and reviews the literature to discuss briefly many of the controversial aspects of the technique.

The nature and effects of composite finishing pastes

Specimens of composite resins, contoured and finished with a series of microfine diamonds, were finished with a selection of commercially available composite finishing pastes. The resulting surfaces were examined using scanning electron microscopy (SEM) and surface profilometry. Samples of the pastes were investigated using SEM and energy dispersive X-ray spectroscopy. All the paste systems employed an abrasive of similar composition and particle size. The selection of finishing pastes produced marked improvements of the surfaces of the composite resins. The small differences measured between the performances of the four finishing pastes included in this study could not be corroborated by SEM evaluation. Therefore, within the limitations of this study, there was little evidence to suggest that any one paste system was superior to the others. The results of this study indicate that commercially available composite resin finishing pastes of the type investigated may be used to improve the surface of all types of contemporary composite resins and may be of particular value in finishing the concave surfaces of restorations of composite resins following contouring and finishing with microfine diamond burs.