Wear and surface roughness of current prosthetic composites after toothbrush/dentifrice abrasion

The Toothbrushing Effects on Surface Properties and Color Stability of CAD/CAM and Pressable Ceramic Fixed Restorations-An In Vitro Study

Pressable ceramic restorations have been introduced and investigated, and found comparable to CAD/CAM ceramic in terms of mechanical properties; however, the effect of toothbrushing on the pressable ceramic has not been thoroughly investigated. The objective of the current study was to assess the effect of artificial toothbrushing simulation on the surface roughness, microhardness, and color stability of different ceramic materials. Three lithium disilicate-based ceramics (IPS Emax CAD [EC], IPS Emax Press [EP]; (Ivoclar Vivadent AG), and LiSi Press [LP] (GC Corp, Tokyo, Japan)) were examined. For each ceramic material, eight bar-shaped specimens were prepared and subjected to 10,000 brushing cycles. Surface roughness, microhardness, and color stability (∆E) were measured before and after brushing. Scanning electron microscopy (SEM) was used for surface profile analysis. The results were analyzed using one-way ANOVA, Tukey's post hoc test, and paired sample t-test α = 0.05. The findings revealed a non-significant decrease in the surface roughness of EC, EP, and LP groups (p > 0.05), and both LP and EP have the lowest surface roughness values (0.64 ± 0.13, 0.64 ± 0.08 µm) after brushing, respectively. Toothbrushing showed a decrease in the microhardness of the three groups: EC and LP, p < 0.001; EP, p = 0.012). EP showed the lowest hardness value after brushing (862.45 ± 273.83). No significant changes (∆E) were observed in all groups (p > 0.05); however, the EC group was found to be considerably affected by color changes, in comparison to the EC and LP groups. Toothbrushing had no effect on surface roughness and color stability of all tested materials, but it decreased the microhardness. Material type, surface treatments, and glazing of ceramic materials contributed to the surface changes in the ceramic materials, necessitating further investigations in terms of the toothbrushing effect with different glazing as variables.

Toothbrush-Dentifrice Abrasion of Dental Sealants: An In Vitro Study

Objective  This study sought to investigate the toothbrush-dentifrice abrasion of dental sealants.

Materials and Methods  Weight loss (∆W) and depth loss (∆D) were used as abrasion indicators. Sealant samples from nine products were soaked in dentifrice slurry and abraded by using a toothbrushing machine with a brushing force of 300 g. The mean percentages of ∆W and mean values of ∆D after 24,000 and 48,000 strokes of brushing were compared by using paired t -test. A comparison of these mean values among sealant products was performed by using one-way ANOVA and multiple comparison analysis (Scheffe's test).

Results  Abrasive wear was observed in all sealants. Teethmate F-1 (Kuraray Noritake, Tokyo, Japan)—a fluoride-releasing unfilled sealant—exhibited the maximum abrasive wear, with ∆W and ∆D values of 1.14% ± 0.37% and 12.84 ± 4.28 µm, respectively. Delton (Dentsply Sirona, Charlotte, North Carolina, United States), a light-cured unfilled sealant, showed the minimum abrasive wear, with ∆W and ∆D values of 0.41% ± 0.09% and 2.93 ± 1.23 µm, respectively. No statistical differences were observed among unfilled sealants except when compared with Teethmate F-1. Similarly, no differences were observed when comparing among filled sealants and flowable composite.

Conclusion  Abrasive wear occurred in all sealants after brushing with dentifrice. Almost all unfilled sealants showed less wear compared with both filled sealants and flowable composite. However, the low abrasive values of all sealants after brushing with dentifrice implied that there is no clinical significance to this finding.

Gloss retention of direct composites and corresponding CAD/CAM composite blocks

Objectives

To compare gloss retention of four different resin composites with their corresponding CAD/CAM composite blocks.

Materials and methods

Four direct resin composites (Filtek Supreme XTE A2 Body (3M, USA), Tetric EvoCeram A2 (Ivoclar Vivadent, Liechtenstein), GrandioSO x‐tra A2 (VOCO, Germany), G‐aenial Universal A2 (GC, Japan)), and their corresponding CAD/CAM composite blocks were tested. A total of 288 samples were prepared and three different tests were performed: brushing, exposition to acidic fluoride gel and exposition to alcoholic solution. Gloss values were obtained by means of a glossmeter at T0 before aging and T60 after 1 h of aging.

Results

Mean gloss values ranged from 0.9 after brushing tests to 79.0 after the alcohol test witnessing a high gloss variability depending on the materials and the aging test. Statistical analysis by means of two‐way repeated measures ANOVA followed by Fisher's LSD post‐hoc test revealed significant differences between materials, storage media, and their interactions.

Conclusion

Gloss retention seems to be dependent on the composite type (direct or CAD/CAM block) and composite brand and varies in respect to the type of aging. CAD/CAM materials showed a higher resistance toward alcohol exposure.

A New Zinc Reinforced Glass Ionomer Cement: A Boon in Dentistry

Background:

Conventional glass ionomer cement (CGIC) has many beneficial properties, but it has poor physical and mechanical properties. Therefore, new glass ionomer cement (GIC) is manufactured by adding zinc to improve the mechanical properties of GIC ChemFil Rock. This material possesses better flexural tensile strength and compressive strength in comparison to conventional to CGIC.

Objectives:

The aim of this study was to compare four properties of ZRGI like fracture toughness, surface micro-hardness, abrasive wear, and roughness to other GIC material, which are commercially available as: resin-coated glass ionomer (EQUIA FIL).

Materials and Methods:

The study was done in dual phase. In phase-1, micro-hardness surface roughness, abrasion of four GIC and a composite resin as control was analyzed and in phase-2, fracture toughness of four GIC was done at 24 h interval so that all cement achieve its peak strength.

Results:

Micro-hardness value of ChemFil Rock was lowest among different GIC groups. All four GIC group exhibit similar abrasion capacities, while composite were more wear-resistant significantly. Roughness change was highest on ChemFil Rock compared to other GIC. EQUIA FIL has the highest fracture toughness, followed by ChemFil Rock.

Conclusion:

We can conclude that incorporating zinc in the matrix of chemfil rock increases fracture toughness and good abrasive wear, but it does not improve micro-hardness or surface roughness.

The Effects of Toothbrush Wear on the Surface Roughness and Gloss of Resin Composites with Various Types of Matrices

Objective: To evaluate and compare the surface roughness and gloss of a DMA-free composite and Bis-GMA-free composite with a DMA-based composite before and after toothbrushing simulation. Materials and Methods: Fifteen dimensionally standardised composite specimens of three nano-hybrid resin composites (Tetric EvoCeram, Admira Fusion, and Venus Diamond) were used. Five specimens from each composite were polished and then subjected to a toothbrushing simulator. Surface roughness (Ra) and gloss were measured before toothbrushing and after 5000, 10,000, 15,000, and 20,000 toothbrushing cycles. The data was analysed using 5 × 3 ANOVA to assess surface roughness and gloss values and pairwise comparisons in the form of Tukey post hoc tests were performed to interpret main effects. Results: For all tested materials, surface roughness increased, and gloss decreased after toothbrushing abrasion. Surface roughness (Ra) values ranged from 0.14 to 0.22 μm at baseline and increased to between 0.41 and 0.49 μm after 20,000 toothbrushing cycles. Gloss values ranged between 31.9 and 50.6 GU at baseline and between 5.1 and 19.5 GU after 20,000 toothbrushing cycles. The lowest initial Ra value was detected in Venus Diamond and the highest initial gloss value was detected in Tetric EvoCeram. Conclusions: Simulated toothbrushing abrasion led to an increase in surface roughness and a decrease in gloss for all tested materials. Venus Diamond had the smoothest surface and Tetric EvoCeram had the glossiest surface after polishing and following 20,000 cycles of toothbrushing abrasion. Admira Fusion demonstrated the roughest surface and had the lowest gloss values before and after toothbrushing abrasion.

Is Deterioration of Surface Properties of Resin Composites Affected by Filler Size?

Purpose

To investigate the effect of filler size on surface gloss and roughness of resin composites using a glossmeter and 3D noncontact surface topography, respectively, before and after tooth-brushing abrasion.

Materials and Methods

Seven model resin composites and one commercial were tested in the study. All materials were first polished, and then the surface gloss and 2D and 3D roughness parameters were recorded. Materials are then subjected to abrasion in a tooth-brushing simulator. Roughness parameters were recorded after 10,000 cycles, and after 20,000 cycles, both roughness and gloss were recorded. One-way ANOVA and Bonferroni post hoc test (p < 0.05) were used to analyze data.

Conclusion

Filler size is strongly correlated to gloss and surface roughness retention.

Effect of Antibacterial Silver-Releasing Filler on the Physicochemical Properties of Poly(Methyl Methacrylate) Denture Base Material

Colonization of polymeric dental prosthetic materials by yeast-like fungi and the association of these microorganisms with complications occurring during prosthetic treatment are important clinical problems. In previously presented research, submicron inorganic particles of silver sodium hydrogen zirconium phosphate (S-P) were introduced into poly(methyl methacrylate) (PMMA) denture base material which allowed for obtaining the antimicrobial effect during a 90 day experiment. The aim of the present study was to investigate the flexural strength, impact strength, hardness, wear resistance, sorption, and solubility during three months of storage in distilled water. With increasing S-P concentration after 2 days of conditioning in distilled water, reduced values of flexural strength (107-72 MPa), impact strength (18.4-5.5 MPa) as well as enhanced solubility (0.95-1.49 µg/mm3) were registered, but they were at acceptable levels, and the sorption was stable. Favorable changes included increased hardness (198-238 MPa), flexural modulus (2.9-3.3 GPa), and decreased volume loss during wear test (2.9-0.2 mm3). The percentage changes of the analyzed properties during the 90 days of storage in distilled water were similar for all materials.

Surface deterioration of monolithic CAD/CAM restorative materials after artificial abrasive toothbrushing

PURPOSE

The purpose of this in vitro study was to evaluate the effect of abrasive toothbrushing on the surface properties of monolithic computer-assisted design and computer-assisted manufacturing (CAD/CAM) materials stored in food-simulating liquids (FSLs).

MATERIALS AND METHODS

Fourty-eight disk-shaped test specimens of each material (Paradigm MZ100/PMZ, Lava Ultimate/LU, Vita Enamic/VE, and Vita Mark II/VMII) with a diameter of 10.0 mm and a thickness of 3.0 ± 0.05 mm were prepared. Specimens were divided into 4 subgroups (n=12) and stored in air, distilled water, 0.02 M citric acid, or 75% ethanol/water solution for 7 days at 36.5℃. Then, the specimens were brushed in a multi-station brushing machine under a vertical load of 2.0 N for 3 hours. Surface gloss (GU), roughness (Ra), and hardness (Vickers [VHN]) were measured after storage and brushing simulation. The data sets were statistically analyzed with 2 and 3-way ANOVAs followed by the Tukey's post-hoc comparisons (α=.05).

RESULTS

Statistically significant difference was found among the materials concerning the results of surface properties. VMII showed the highest VHN, while PMZ produced the lowest. Storage in FSLs significantly affected the VHN of PMZ and LU. VMII showed the lowest Ra and highest GU irrespective of FSLs and of abrasive toothbrushing. VE, LU, and PMZ produced significant decrease in GU and increase in Ra after toothbrushing.

CONCLUSION

Surface properties of monolithic CAD/CAM restorative materials were differently affected by the storage media and abrasive toothbrushing.

Effects of simulated gastric juice on color stability, surface roughness and microhardness of laboratory-processed composites

Medical problems such as gastroesophageal reflux disease can cause considerable damage to restorations in the oral environment. This study evaluated the effects of gastric juice on the surface characteristics of different types of laboratory-processed indirect composites with different filler particles and polymerization modes. Specimens were prepared from Tescera (TES; Bisco), Sinfony (SIN; 3M ESPE), Solidex (SOL; Shofu), and Adoro (AD; Ivoclar Vivadent). Before exposing the specimens to simulated gastric juice for 24 h, color, surface roughness, and microhardness were measured on one half of the polished flat surface of each specimen. After exposure to the simulated gastric juice, the same tests were repeated on the other half of specimen surface. Results indicated that gastric juice had a significant impact on color change (p<0.001). AD showed the largest surface roughness change among the resins (p<0.001). Gastric juice also significantly affected the microhardness of the materials, and AD and TES showed statistically similar change in microhardness (p>0.05).

In Vitro Analysis of Surface Roughness of Acrylic Resin Exposed to the Combined Hygiene Method of Brushing and Immersion in Ricinus communis and Sodium Hypochlorite

PURPOSE

To evaluate a solution based on Ricinus communis (Castor oil) for denture cleansing, comparing it to sodium hypochlorite (NaOCl) for the surface roughness of heat-polymerized acrylic resin.

MATERIALS AND METHODS

Forty polished and unpolished resin specimens (90 × 30 × 4 mm) were evaluated before and after their exposure to protocol hygiene: brushing the specimens with a specific denture brush and mild soap for 3 minutes, three times a day, and immersing them in hygiene solutions (0.25% NaOCl-S1 and 0.5% NaOCl-S2; 10% R. communis-S3; saline-S4: control) for 20 minutes. Surface roughness was evaluated by rugosimeter and scanning electron microscopy (SEM) before and after the protocol. For evaluation of surface roughness, polished and unpolished surfaces were used.

RESULTS

The roughness of the polished surface was not affected by time (p = 0.062), but was affected by solutions (p < 0.0001) and the interaction between factors (p = 0.005). For S1 and S4, the period did not influence the roughness. For S2, there was a change after 7 days, remaining stable after 14 days. For S3, there were changes, and stabilization occurred after 14 days. After 7 and 14 days, S2 and S3 promoted major changes, but after 21 days, there were no differences among solutions, except saline. The unpolished surface was not influenced by factors: period (p = 0.115), solution (p = 0.120), and their interaction (p = 0.382). SEM analysis showed similar results on the evaluation of surface roughness.

CONCLUSIONS

The polished surface of the prosthesis was more susceptible to changes when exposed to hygiene solutions, and although the 0.5% NaOCl solution promoted an increase in the surface roughness compared with the same solution at 0.25% and R. communis at 10%, the values are clinically acceptable.

The comparison of the effects of different whitening toothpastes on the micro hardness of a nano hybrid composite resin

Aim:

The aim of this study was to compare the micro hardness of a nanohybrid composite resin after brushing with two herbal and one non-herbal whitening toothpastes.

Materials and Methods:

We divided Eighty disk-shaped specimens of a nanohybrid composite (Tetric N Ceram, Ivoclar Vivadent, Asia) into 4 groups of 20 specimens each: Groups A, B, C, and D. Group A was control, Group B was brushed with Colgate total advanced whitening (Colgate-Palmolive (India) Limited), Group C with Salt and Lemon, Dabur (Dabur International Limited, Dubai, UAE), and Group D with HiOra Shine, Himalaya (The Himalaya Drug Company, India). The specimens were polished using medium, fine, and superfine discs (Sof-lex, 3M, ESPE, USA) and subsequently placed at 37°C in distilled water. They were brushed for 2 minutes twice daily with a soft motorized toothbrush (Colgate 360 sonic power battery-operated tooth brush, Colgate Palmolive, India) for 30 days. The samples were rinsed under running water to remove the toothpaste and stored in distilled water at 37°C until the readout was taken on the Vickers's hardness tester for microhardness.

Results:

The results revealed that the difference among the groups was statistically significant (P < 0.001). Tukey's test showed that reduction in microhardness for Group B was significantly higher than that for Group C and Group D (P < 0.001).

Conclusion:

Within the limitations of this study, non-herbal whitening toothpaste had a greater impact on the microhardness of nanohybrid resin composite than herbal whitening toothpastes.

An In vitro Evaluation of Flexural Bond Strength of Indirect Composites Fused to Metal

With the advent of newer indirect composite resin materials for crown and bridge prosthesis, it has become imperative to evaluate their strength to serve as long term replacements as a substitute to metal ceramic restorations. This study aimed to evaluate and compare the flexural bond strength of three composite resin veneering material to metal, cured by different methods. Specimen were fabricated with pattern resin by duplicating it with machined metal die and divided into three groups. Three composite resin materials were used in this study. Group (A) received Adoro, Group (B) received Targis and Group (C) received Tescera. The bond strength of all specimens was tested with Lloyd's universal testing machine under three point loading. The highest values for fracture resistance were displayed by light, heat and pressure cured composites followed by composites cured using a temperature of 104 °C and composites with curing temperature of 95 °C. The results indicate that there is a significant difference between the three groups, with the Tescera group specimens exhibiting the highest flexural bond strength. Of the other two groups, Adoro group exhibited higher flexural bond strength than Targis group. The results of this study suggest that Tescera group with curing temperature of 130 °C and pressure of 80 Psi, cured with metal halide unit exhibited the highest flexural bond strength when compared to Adoro and Targis groups.

Abrasion of 6 dentifrices measured by vertical scanning interference microscopy

Objectives

The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI).

Material and Methods

Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas.

Results

Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix^® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced.

Conclusion

Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials.

Denture hygiene habits among elderly patients wearing complete dentures

OBJECTIVE

To determine the denture hygiene habits in complete denture patients according to their age and time of dentures.

METHODS

In this study a self administered structured was developed to know the attitude of the patients regarding denture hygiene in the department of Prosthodontics. The total study sample consisted of 230 subjects including 124 (53.9%) males and 106 (46.1%) females. Data was analyzed using SPSS version 15.0 with chi-square test at p-value <0.05.

RESULTS

Nearly half of the subjects clean their dentures daily once. Participants from the younger age group and who had been wearing dentures since 2 years maintain better frequency of cleaning. The majority of these subjects used water and brush for denture cleansing. After seeing the condition, half of the dentures were rated as good 50.3%, followed by fair and poor as 29.5 and 20.2% respectively.

CLINICAL SIGNIFICANCE

Poor condition of complete dentures seen in the population is mainly due to irregularly cleansing habits and also less usage of cleansing solutions. Dentists should give proper instructions regarding maintenance of denture hygiene.

Effects of toothbrush hardness on in vitro wear and roughness of composite resins

AIM

To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins.

MATERIALS AND METHODS

Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p < 0.05).

RESULTS

Abrasion of the composite resins increased linearly with increasing number of brushing cycles (r² > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 µm), the lowest one on VEN (Ra < 0.3 µm). VEN specimens showed increased numbers of pinhole defects when brushed with hard toothbrushes, surfaces of VEP were uniformly abraded without level differences between the prepolymerized fillers and the glass filler-loaded matrix, VED showed large glass fillers protruding over the main filler-loaded matrix portion under each condition.

CONCLUSION

Abrasion and surface roughness of composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness.

CLINICAL SIGNIFICANCE

The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin.

Wear behavior of light-cured resin composites with bimodal silica nanostructures as fillers

To enhance wear behavior of resin composites, bimodal silica nanostructures including silica nanoparticles and silica nanoclusters were prepared and proposed as fillers. The silica nanoclusters, a combination of individually dispersed silica nanoparticles and their agglomerations, with size distribution of 0.07-2.70 μm, were fabricated by the coupling reaction between amino and epoxy functionalized silica nanoparticles, which were obtained by the surface modification of silica nanoparticles (~70 nm) using 3-aminopropyl triethoxysilane (APTES) and 3-glycidoxypropyl trimethoxysilane (GPS) as coupling agents, respectively. Silica nanoparticles and nanoclusters were then silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) to prepare composites by mixing with bisphenol A glycerolate dimethacrylate (Bis-GMA) and tri (ethylene glycol) dimethacrylate (TEGDMA). Experimental composites with various filler compositions were prepared and their wear behaviors were assessed in this work. The results suggested that composites with increasing addition of silica nanoparticles in co-fillers possessed lower wear volume and smoother worn surface. Particularly, the composite 53:17 with the optimum weight ratio of silica nanoparticles and silica nanoclusters presented the excellent wear behavior with respect to that of the commercial Esthet-X, although the smallest wear volume was achieved by Z350 XT. The introduction of bimodal silica nanostructures as fillers might provide a new sight for the design of resin composites with significantly improved wear resistance.

Surface roughness and color change of a composite: influence of beverages and brushing

This study evaluated the influence of beverages and brushing on the surface roughness(SR) and color change(∆E) of a composite resin.For this, 120-disks(10 mm×2 mm) of composite resin(Filtek-Z250) were prepared and polished. Initials SR(Ra-μm) and color(CIELab-system) were measured with rugosimeter and spectrophotometer; specimens were divided into four groups(red wine, soft drink, sugar cane spirit, or artificial saliva=control) and three subgroups(without brushing; brushed with Colgate or with Close-Up). Specimens were immersed in the beverage 5×/day, for 5', over 30 day, being two subgroups brushed(120 strokes/day). Color was measuredat 15th day, 30th day and after repolishment; SR at 30th day. ∆E-values were statistically different after immersion in the beverages(p<0.05). Red wine promoted the highest alteration, followed by soft drink=sugar cane spirit and finally saliva. At 30th day, specimens exhibited ∆E higher than 15th day; after repolishing, ∆E was similar to 15th day. Beverages and brushing negatively influenced the SR. Therefore, ∆E and SR can be influenced by beverages and brushing.

A comparison of microhardness of indirect composite restorative materials

The purpose of this study was to compare the microhardness of four indirect composite resins. Forty cylindrical samples were prepared according to the manufacturer’s recommendations using a Teflon mold. Ten specimens were produced from each tested material, constituting four groups (n=10) as follows: G1 - Artglass; G2 - Sinfony; G3 - Solidex; G4 - Targis. Microhardness was determined by the Vickers indentation technique with a load of 300g for 10 seconds. Four indentations were made on each sample, determining the mean microhardness values for each specimen. Descriptive statistics data for the experimental conditions were: G1 - Artglass (mean ±standard deviation: 55.26 ± 1.15HVN; median: 52.6); G2 - Sinfony (31.22 ± 0.65HVN; 31.30); G3 - Solidex (52.25 ± 1.55HVN; 52.60); G4 - Targis (72.14 ± 2.82HVN; 73.30). An exploratory data analysis was performed to determine the most appropriate statistical test through: (I) Levene's for homogeneity of variances; (II) ANOVA on ranks (Kruskal-Wallis); (III) Dunn's multiple comparison test (0.05). Targis presented the highest microhardness values while Sinfony presented the lowest. Artglass and Solidex were found as intermediate materials. These results indicate that distinct mechanical properties may be observed at specific materials. The composition of each material as well as variations on polymerization methods are possibly responsibles for the difference found in microhardness. Therefore, indirect composite resin materials that guarantee both good esthetics and adequate mechanical properties may be considered as substitutes of natural teeth.

Potential effects of tooth-brushing on human dentin wear following exposure to acidic soft drinks

This study used scanning electron microscopy and atomic force microscopy to examine the short-term potential effects of brushing time and the start-time of tooth-brushing after demineralization on primary dentin wear in vitro. Thirty-six noncarious primary central incisors were assigned to 12 experimental groups. Exposure to cola drinks was used to initiate the demineralization process. Three brushing times (5, 15 and 30 s) and four start-times of brushing (0, 30, 60 and 120 min) after an erosive attack were used for the abrasion process. Tooth-brushing the softened dentin surface led to increases in the open tubular fraction and microstructural changes on the dentin surface. Brushing immediately after exposure to cola resulted in the greatest irreversible dentin loss, whereas brushing 60 or 120 min after pretreatment resulted in the least irreversible dentin loss. However, brushing time had no effect on the irreversible loss of dentin wear. Based on these experimental results, tooth-brushing should be performed at least 60 min after consuming a cola drink to achieve the desired tooth cleaning and avoid the introduction of surface lesions on dentin.

Influence of laboratory light sources on the wear characteristics of indirect composites

The purpose of the current study was to evaluate the influence of light sources on the mechanical properties and wear characteristics of indirect composite materials. The two composite materials used were Estenia C&B and Epricord. The three laboratory polymerization units used, of which the wavelength range was 400-500 nm, were Hyper LII (two metal halide lamps of 4.82 mW/cm(2)), α-Light II (one halogen lamp and two fluorescent tubes of 3.60 mW/cm(2)), and Labolight LV-II (three fluorescent tubes of 0.63 mW/cm(2)). Three-body wear test was performed using indirect composite plate specimens, a gold alloy antagonist, and a polymer slurry. Wear depths of Estenia C&B polymerized with Hyper LII, α-Light II, and Labolight LV-II were 5.7, 18.5, and 64.2 µm respectively, whereas those of Epricord were 12.9, 18.7, and 48.5 µm respectively. Results showed that, after 100,000 cycles of localized loading, high-intensity light sources were effective in enhancing the wear resistance of both composite materials.

Indirect resin composites

Aesthetic dentistry continues to evolve through innovations in bonding agents, restorative materials, and conservative preparation techniques. The use of direct composite restoration in posterior teeth is limited to relatively small cavities due to polymerization stresses. Indirect composites offer an esthetic alternative to ceramics for posterior teeth. This review article focuses on the material aspect of the newer generation of composites. This review was based on a PubMed database search which we limited to peer-reviewed articles in English that were published between 1990 and 2010 in dental journals. The key words used were 'indirect resin composites,' composite inlays,' and 'fiber-reinforced composites.'

Complete denture hygiene and nocturnal wearing habits among patients attending the Prosthodontic Department in a Dental University in Brazil

OBJECTIVE

The aim of this study was to evaluate the overnight wearing and cleaning habits of complete denture wearers.

BACKGROUND

Successful complete denture treatment can be achieved when the patients are motivated and aware of appropriate denture wear and hygiene.

MATERIALS AND METHODS

A sample of 224 complete denture wearers (162 women) aged 37-89 years was studied. Inclusion criteria comprised edentulous subjects who had received their new complete dentures between 2000 and 2005 in the Dental Clinic of the Araçatuba and Araraquara Dental School, São Paulo State University. Ethical approval was sought and granted. Subjects were interviewed using questions related to overnight denture wearing and denture cleaning habits. Possible statistical relationships among some of items were analysed by the chi-square test at 5% significance level.

RESULTS

Of the patients, 55.8% removed their dentures during the overnight period and 88% did this every day. Among them, 66.4% removed both dentures. Most of the patients used brushing with toothpaste (105 patients - 46.87%) as a cleaning method. More than a half of the subjects (63.4%) showed biofilm and calculus on their dentures.

CONCLUSION

The patients need instructions and motivation concerning denture hygienic and denture removal overnight.

Dental casting alloys behaviour during power toothbrushing with toothpastes with various abrasivities. Part I: wear behavior

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the surface and mechanical properties of dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr, c.p. Ti) and one ceramic were chosen. Four specimens of each material were immersed in artificial saliva, brushed without or with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Mass loss was determined by difference in weight, microhardness and surface roughness were also measured. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens (478 microg/cm(2)) exhibited the most mass loss, whereas ceramic (282 microg/cm(2)) and Co-Cr (262 microg/cm(2)) exhibited the least. However, ceramic demonstrated the most volume loss (0.239 mm(3)). The abrasivity effect of the toothpaste correlated with the RDA values. Slight variations in microhardness were observed after toothbrushing and depended on the material but not on the toothpaste used. Material surfaces were slightly smoothed by toothbrushing but no significant differences were detected. Dental casting alloys and ceramic are susceptible to abrasion by brushing with an electric toothbrush depending on the RDA value of the toothpaste. Variations in microhardness and surface roughness were not clinically relevant.

Fabrication of a maxillary posterior fixed partial denture with a type 4 gold alloy and a dual-polymerizing indirect composite

The aim of the present study was to design and fabricate a maxillary posterior fixed partial denture (FPD) made of a type 4 gold alloy and an indirect composite. Unlike the conventional framework design of a resin veneered restoration, cut-back was extended approximately 1/4 to 1/3 width in the occlusal table of the buccal cusp. Multiple retentive beads 150-200 mum in diameter were placed on the metal surface to be veneered. The gold alloy was cast in a cristobalite mold using a centrifugal casting machine. The cut surface with the retentive beads was air-abraded with alumina, and a priming agent (Alloy Primer) that contained triazine dithione monomer (VTD) was applied. A tooth-colored veneer was then fabricated with a highly loaded light- and heat-cured composite material (Estenia). This design and procedure can be applied as a standardized laboratory technique for fabrication of maxillary posterior restorations and FPDs.

Edentulous patients' knowledge of dental hygiene and care of prostheses

OBJECTIVE

The aim of this study was to analyse denture users' oral care habits with regard to the use of their prostheses.

BACKGROUND

Rehabilitative treatment is only successful when patients are motivated and aware of correct prosthesis use and hygiene.

MATERIALS AND METHODS

Questionnaires were distributed to 150 complete denture users at the Federal University of Bahia School of Dentistry, the Esmeralda Natividade Health Center, the Bahian Science Development Foundation and a Salvador nursing home. The questionnaire included information on gender, age, length of prosthesis use, cleaning methods and materials, etc. The data were analysed using EpiInfo version 6 software. The chi-squared test was used for statistical analysis, with a significance level of 5%.

RESULTS

Questionnaire results showed that 78% of the subjects, with an average age of 67.3 years, had used the same complete denture for over 5 years. 64% slept with their prostheses and 44% removed them from the mouth only for cleaning. None of the patients interviewed knew anything about brushes designed specifically for complete dentures. 37.3% had a restricted diet and 44% believed that a complete denture would last for more than 10 years.

CONCLUSION

Within the limitations of this study, it was concluded that the edentulous patients surveyed had limited awareness of prosthetic hygiene and long-term oral care despite extended periods of denture use.

Surface Roughness of Nanofill and Nanohybrid Resin Composites after Polishing and Brushing

PURPOSE

The purpose of this study was to compare the surface roughness of nanofill (Filtek Supreme XT dentin shade and transparent shade, Filtek Z350, and Estelite Sigma), nanohybrid (Tetric EvoCeram, Ceram X, and Premise), and microhybrid resin composites (Filtek Z250, Tetric Ceram, and Clearfil AP-X) with the materials after polishing or brushing.

MATERIALS AND METHODS

Forty specimens of each resin composite were polymerized for 40 seconds under a matrix strip in cylindrical molds. Each type of polymer was divided into four subgroups: unpolished, polished with abrasive disks (Sof-Lex), polished with silicone-impregnated polishing devices (Astropol), and brushed with a toothbrush (Oral B) and toothpaste (Colgate). The surface roughness of each specimen was determined using a contact stylus profilometer and by observation under a scanning electron microscope.

RESULTS

No significant differences in surface roughness among the materials were found on unpolished surfaces. For the nanofill resin composites, there were no significant differences in surface roughness between the two polishing methods or among the unpolished surfaces. After brushing, the surfaces of all materials, except those made from Filtek Z350 and Filtek Supreme XT (dentin), had greater roughness than unpolished surfaces and surfaces polished with either abrasive disks or silicone devices. The scanning electron microscope studies revealed that the surface irregularities of the materials corresponded to the results obtained using the surface roughness tester.

CLINICAL SIGNIFICANCE

The use of nanofill resin composites made with nanoclusters demonstrated the smoothest surfaces after polishing and brushing.

Effect of a metal priming agent on wear resistance of gold alloy-indirect composite joint

The purpose of the current study was to evaluate the effect of a metal priming agent on wear resistance of gold alloy-composite joint. Four types of plate specimen were prepared: composite (Estenia C&B or Epricord) alone, type 4 gold alloy alone, alloy-composite joint without priming agent, and alloy-composite joint bonded with a priming agent (Alloy Primer). Three-body wear test was performed using the plate specimens, gold alloy antagonist, and polymer slurry. Joined specimens with priming exhibited less wear depth (in microm; 21.0 for Estenia and 24.9 for Epricord) than the joined specimens without priming (57.8 for Estenia and 46.7 for Epricord). Wear depth of the single plate specimens when abraded with the gold alloy antagonist was ranked as follows: Estenia (9.6), gold alloy (12.8), and Epricord (19.1). It was concluded that the use of a metal priming agent at the alloy-composite interface effectively enhanced the wear resistance of the joined area when under cycled loading.

Influence of centrifugal force on filler loading of resin composites

This study examined the influence of centrifugal force on the filler loading of composites using a light-polymerizing apparatus combined with a centrifuge. To assess uneven filler particle distribution resulting from specimen rotation, two low-viscosity composites (Palfique Estelite LV and Revolution Formula 2) were placed in test tubes, centrifuged, and subsequently light-polymerized with the apparatus. After each specimen was sliced into four disks (2-mm thickness), the inorganic filler content and Knoop hardness number (KHN) of each disk were determined. The results suggested that filler loading of composites could be increased by application of centrifugal force if the filler and monomer components were properly arranged.

Effects of Monomer Composition and Original Filler Content on Filler Loading in the Resulting Centrifuged Composites

This study examined the effects of monomer composition, original filler content, and application of centrifugal force on the resulting filler loading of composites. Either Bis-MPEPP or UDMA was mixed with TEGDMA at a molar ratio of 1 : 1. Silane-treated silica (14-20 wt%) was added to each mixture. After the mixtures were centrifuged and light-polymerized, rate of increase was determined as the filler increment of 2.0-mm-high, disk-shaped sections of specimen when compared against the uncentrifuged filler content. Both the original filler loading and monomer composition influenced the filler content of the centrifuged composites. Fillers in Bis-MPEPP-based composites exhibited a higher rate of condensation after application of centrifugal force than did UDMA-based composites. The results were suggestive of underlying relationships among the composition, component stability, and post-polymerization properties of flowable composites.

In vitro toothbrush-dentifrice abrasion of two restorative composites

BACKGROUND

Surface wear can be a problem with directly placed composites.

PURPOSE

This study evaluated the in vitro wear and surface roughness of two composites at different cycle intervals after being subjected to toothbrush-dentifrice abrasion.

MATERIALS AND METHODS

Twenty specimens of a microhybrid, Filtek Z250 (3M ESPE, St. Paul, MN, USA), and a nanofill composite, Filtek Supreme (3M ESPE), were prepared according to the manufacturer's directions. Each specimen was subjected to toothbrush-dentifrice abrasion (250 g vertical load) using a deionized water-dentifrice slurry (Close-Up, Lever Ponds Ltd., La Lucia, ZA) and toothbrush heads (Oral-B 40, Oral-B Laboratories, Delmont, CA, USA). A brushing sequence of 10,000, 20,000, 50,000, and 100,000 strokes was performed for all samples at a rate of 1.5 Hz. At baseline and each cycle interval, a surface profilometer was used to determine average surface roughness, Ra. At the same intervals, vertical loss of material was measured with a precision micrometer. Data were analyzed using repeated-measures analysis of variance at p value .05. Analyses with atomic force microscopy (AFM) and scanning electron microscopy (SEM) were also performed.

RESULTS

After 20,000, 50,000, and 100,000 cycles, Filtek Supreme showed less significant wear than Z250. Filtek Supreme demonstrated higher surface roughness than Z250 after 50,000 and 100,000 cycles. However, AFM and SEM images indicated a more uniform surface topography for Filtek Supreme than for Z250. Abrasion wear and surface roughness increased with each cycle interval for both materials.

CONCLUSIONS

Although the initial performance of both materials was similar, a greater number of brushing cycles revealed differences between the wear resistance and generated surface roughness of the materials.

CLINICAL SIGNIFICANCE

The wear resistance and roughness results of Filtek Supreme suggest that it is suitable for clinical use, mainly in areas that are more subject to abrasive wear, such as Class V restorations.

Changes in gloss after simulated generalized wear of composite resins

STATEMENT OF PROBLEM

Generalized wear of composite resins in the noncontact area may result in changes of gloss, which can influence esthetics of restorations.

PURPOSE

The purpose of this study was to determine the changes in gloss of composite resins after generalized wear simulation. Surface roughness and amount of wear were measured for comparison.

MATERIAL AND METHODS

Generalized wear simulation was performed with a wear tester for 400,000 cycles with 6 composite resins (Estelite Sigma, Esthet X improved, Filtek Supreme, Heliomolar, Renamel Microfill, and Tetric-Ceram). Composite resin was placed into a mold (8 mm in diameter, 3 mm in depth) in an acrylic resin block, and 8 specimens were prepared per group. A flat-planed stylus made with polyacetal was loaded perpendicularly. Gloss was measured after every 100,000 cycles with a glossmeter in gloss units (GU). Average surface roughness (R(a)) of each specimen before and after 400,000 cycles of wear was determined. The amount of wear was measured with a 3-dimensional profilometer. Changes in gloss were analyzed by repeated-measures analysis of variance, and mean values were compared by Fisher's PLSD interval (alpha=.05).

RESULTS

Gloss was influenced by the number of wear cycles and the composite resin, and there was a significant interaction (P=.000) between the number of wear cycles and the brand of composite resin. There were no significant correlations between the wear depth and the gloss or changes in gloss after 400,000 cycles.

CONCLUSION

Generalized wear simulation for approximately 3 years of clinical use resulted in gloss changes of 36 to 64 GU, and maximum wear depth was in the range of 35 to 75 mum. Change in gloss varied among the composite resins, but average surface roughness was not influenced by the various composite resins.

Comparative study of the surface roughness of Ormocer-based and conventional composites

The aim of this study was to evaluate the surface roughness of two Ormocer-based resin composites before and after mechanical toothbrushing. The study compared the brands Admira and Definite with composites based on conventional monomer systems (Bis-GMA, Bis-EMA, UEDMA e TEGDMA), Z250 and A110. Eight samples of each material with 4mm in diameter and 2mm in height were prepared using a metallic mold. After 24 hours they were polished and examined with a profilometer for measurement of the initial surface roughness (Ra, mm) before mechanical toothbrushing (30,000 cycles). After toothbrushing, the samples were taken to the profilometer once again to check the final surface roughness. The results were submitted to ANOVA and Tukey test (5%). The Admira composite presented a higher mean of surface roughness before toothbrushing (0.132mm), with a statistical difference from the composite A110 (0.082mm). Definite (0.110mm) and Z250 (0.105mm) composites showed no differences between themselves or among the other composites. No statistical differences were observed after toothbrushing between the composites Definite (0.178mm), Z250 (0.187mm), Admira (0.181mm), and A110 (0.193mm). All composites showed a statistically significant increase in the surface roughness after toothbrushing.

Surface roughness of composite resins after finishing and polishing

This study evaluated the effect of surface finishing methods on the average surface roughness of resin composites. Seven composites and two polishing systems were used. One hundred and twenty-six conical specimens of each material were prepared in stainless steel molds against a polyester strip. Forty-two of them remained intact and were used as controls. Each half of the remaining samples was polished with either diamond burs or diamond burs + aluminum oxide discs. The results showed no statistical difference in average surface roughness (Ra, microm) between the polyester strip and aluminum oxide discs (p > 0.05). However, finishing with diamond burs showed a statistically higher average roughness for all composites (p < 0.05). Statistical differences were detected among materials (p < 0.05) in the use of diamond burs.

Influence of abutment substrates on the colour of metal-free polymer crowns

New-generation composite materials have excellent strength and wear resistance, and thus can be used to make metal-free crowns. However, composite materials are translucent, and so when using them to make metal-free crowns, it is necessary to take the effect of the abutments into consideration. In this study, five types of materials including three types of new-generation composite materials, a conventional composite material, and a ceramic material were used to examine the translucency (contrast ratio) of the materials and the effects of the colour of the abutments on the final appearance of metal-free crowns. It was found that the materials varied slightly from one-another in translucency and that it was possible to reproduce the desired colour when gold alloy was used for the background. However, it was difficult to produce an adequate colour match when silver-palladium alloy was used for the background. When a tooth colour material that was darker than the target colour was used for the abutment teeth, some materials could not reproduce the target colour satisfactorily.

Veneering technique for a Ti-6Al-7Nb framework used in a resin-bonded fixed partial denture with a highly filled indirect composite

This article presents a veneering technique for fixed partial denture frameworks made from a Ti-6Al-7Nb alloy. The fixed partial denture framework was prepared with a magnesia-based mold material and a centrifugal casting machine. An esthetic veneer was fabricated with a highly filled dual-polymerized composite material and a metal-conditioning agent. This technique can be applied as a standardized veneering procedure for the titanium alloy, for which porcelain fusing is currently difficult.

A comparison of the wear resistance and hardness of indirect composite resins

STATEMENT OF PROBLEM

Various new, second-generation indirect composites have been developed with claimed advantages over existing tooth-colored restorative materials. To date, little independent research has been published on these materials, and the properties specified in the advertising materials are largely derived from in-house or contracted testing.

PURPOSE

Four second-generation indirect composites (Artglass, belleGlass, Sculpture, and Targis) were tested for wear resistance and hardness against 2 control materials with well-documented clinical application. Human enamel was also tested for comparison.

MATERIAL AND METHODS

Twelve specimens of each material were fabricated according to the manufacturers' directions and subjected to accelerated wear in a 3-body abrasion, toothbrushing apparatus. Vickers hardness was measured for each of the tested materials, and energy dispersive x-ray (EDX) spectroscopy was performed to determine the elemental composition of the composite fillers. The statistical tests used for wear and hardness were the Kruskal-Wallis 1-way ANOVA test with Mann-Whitney tests and 1-way ANOVA with multiple comparisons (Tukey HSD). The Pearson correlation coefficient was used to determine the existence of a relationship between the hardness of the materials and the degree to which they had worn. The level of statistical significance chosen was alpha=.05.

RESULTS

The control material Concept was superior to the other composites in wear resistance and hardness and had the lowest surface roughness. Significant relationships were observed between depth of wear and hardness and between depth of wear and average surface roughness. Enamel specimens were harder and more wear resistant than any of the composites. EDX spectroscopy revealed that the elemental composition of the fillers of the 4 new composites was almost identical, as was the composition of the 2 control composites.

CONCLUSION

The differences in wear, hardness, and average surface roughness may have been due to differences in the chemistry or method of polymerization of the composites. Further research in this area should be encouraged. It was also apparent that the filler present in the tested composites did not exactly fit the manufacturers' descriptions.