1. bookVolume 39 (2021): Issue 2 (June 2021)
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2083-134X
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16 Apr 2011
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access type Open Access

Surface roughness analysis of prepolymerized CAD/CAM dental acrylic resins following combined surface treatments

Published Online: 14 Oct 2021
Volume & Issue: Volume 39 (2021) - Issue 2 (June 2021)
Page range: 209 - 218
Received: 03 May 2021
Accepted: 17 Aug 2021
Journal Details
License
Format
Journal
eISSN
2083-134X
First Published
16 Apr 2011
Publication timeframe
4 times per year
Languages
English
Abstract

Oral dentures are subjected to mechanical and chemical cleansing processes. However, these processes alter the physical and mechanical properties of denture acrylic resins. This study analyzes the surface roughness of conventional heat-cured (HC) polymethacrylate, light-cured (LC) urethane dimethacrylate, and prepolymerized computer-aided design/computer-aided manufacturing (CAD/CAM) dental acrylic resins. The materials were subjected to combined surface treatment of mechanical brushing, thermal cycling, and immersion in chemical disinfectants (corega, chlorhexidine gluconate [CHG], and sodium hypochlorite) to simulate 1 year of clinical use. The surface roughness of the resin specimens before and after surface treatment was evaluated using a noncontact profilometer. Statistical tests based on analysis of variance revealed significant interactions between resin type and disinfectants, indicating that the effects of these two factors were interdependent. The highest and lowest surface roughness was observed in HC resins immersed in CHG and CAD/CAM resins immersed in sodium hypochlorite. Among the materials, HC resins demonstrated the overall highest mean roughness, followed by LC and CAD/CAM resins. Regarding the disinfectant use, the highest mean roughness was observed in disks immersed in CHG, followed by those immersed in corega and sodium hypochlorite. The prepolymerized CAD/CAM acrylic resin demonstrated superior surface quality following combined surface treatments. The HC and LC resins exceeded the roughness threshold and the reported roughness values for acrylic resins following surface treatments. Among the disinfectants tested, sodium hypochlorite produced overall low roughness values.

Keywords

Introduction

Polymethylmethacrylate (PMMA) acrylic resins have been extensively used in the fabrication of denture bases for almost 8 decades because of their good mechanical, physical, and aesthetic properties [1,2,3]. However, they possess certain drawbacks, such as dimensional instability, residual monomers, fracture susceptibility, and increased risk of denture-related infections [4, 5]. Furthermore, the chances of surface and subsurface irregularities during processing affect the mechanical characteristics of the fabricated denture and the aesthetic and hygienic outcomes [1].

Light-cured (LC) resin materials have made substantial clinical advancements, reducing dependence on conventional resins. These resins are activated by light in the 460–470 nm range and are frequently based on higher-molecular-weight monomers [1]. Recently, technological advances have led to the incorporation of computer-aided design/computer-aided manufacturing (CAD/CAM) systems to design and fabricate complete dentures by either rapid prototyping or milling by computer numerical control (CNC). These techniques have allowed clinicians to fabricate dentures in only two appointments and made the data retrievable [6]. Since they are prepolymerized, CAD/CAM acrylic resin blocks offer several advantages over traditional processing techniques, including elimination of polymerization shrinkage and porosity, reduced residual monomer, increased denture retention, and overall patient satisfaction [7, 8].

Denture wearers are usually advised to maintain denture hygiene by either mechanical brushing and/or chemical cleansers to prevent biofilm accumulation and the development of oral infections. Although brushing is considered the most efficacious method, the best results could be achieved by combining it with chemical cleansers, especially for subjects with impaired manual dexterity [9]. However, it has been proved that soak-type cleansers alone may not be effective for removing heavy plaque, as demonstrated in an earlier study in which only about 34% of plaque was removed by soaking in perborate-containing tablets [10]. There has been serious concern regarding the effect of brushing and soaking on the surface roughness of the base materials of dentures; several investigators have reported that a rough acrylic surface promotes bacterial accumulation and plaque formation [9,10,11]. The use of a standard toothbrush produced no significant wear of heat-cured (HC), chemically cured, or LC PMMA. Still, significant wear was observed in all types of acrylic resin materials when brushing was combined with abrasive dentifrice [11].

The most commonly used commercial agent for denture immersion is alkaline peroxide (available as a tablet), containing solutions that subsequently release oxygen, leading to debris removal via mechanical means, which has proven effective [9]. It has been reported that the use of alkaline peroxide-containing solutions possibly alters the surface roughness of HC and chemically cured acrylic resin [12, 13]. Another well-known and effective solution is 0.2% chlorhexidine, which has been successfully used as a mouthwash to treat candida-associated denture stomatitis. In comparison, 2% suspension is used as an overnight denture disinfectant.

Chlorhexidine gluconate (CHG) has a bimodal action on Candida species since it is considered fungicidal even at very low concentrations, in addition to its capability to significantly suppress candida adhesion to both inorganic and organic substrates [14]. Both concentrations, i.e., 0.2% and 2%, effectively remove plaque biofilm when immersion is practiced in conjunction with brushing [15]. When 0.12% cleanser was used alone for 8 h, complete disappearance of Candida albicans on the acrylic resin was noted [16]. Immersion in chlorhexidine has been reported to have less effect on the surface roughness of the denture resins [13]. Sodium hypochlorite (NaOCl), when used as a chemical solution at 1%, has been effective against different microbial strains, e.g. Staphylococcus aureus, Pseudomonas aeruginosa, C. albicans, Streptococcus mutans, and Enterococcus faecalis [17]. It has been reported that immersion in NaOCl is less likely to affect the surface of HC or chemically cured acrylic resin. However, the immersion period plays a significant role [13].

The surface roughness of polished smooth acrylic resin may vary between 0.03 μm and 0.75 μm; however, significant bacterial colonization occurs if the surface roughness exceeds 0.2 μm [18, 19]. A recent study by Al-Dwairi et al. [20] reported that prepolymerized CAD/CAM acrylics have superior baseline surface roughness (average arithmetic roughness [Ra] ≤ 0.2 μm) values than HC PMMA. Although numerous studies have shown that prepolymerized CAD/CAM acrylics have better surface properties [7, 8, 20], the surface characteristics following different surface treatments over a prolonged period of use lack scientific evidence.

Therefore, this study aimed to evaluate in vitro the surface roughness of HC, LC, and prepolymerized CAD/CAM resin base materials following mechanical and chemical surface treatments. The null hypothesis was that there is no difference in surface roughness between the tested materials following combined surface treatments.

Materials and methods
Specimen preparation

Thirty round disks measuring 23 mm in diameter and in thickness were prepared from HC (Major.Base.20, Moncalieri, Italy), prepolymerized CAD/CAM (Opera system, Principauté de Monaco, France), and LC urethane dimethyl methacrylate (UDMA) (Eclipse®; Dentsply Sirona, York, PA, USA) resins (Figure 1A).

Fig. 1

(A) Prepared specimen; (B) power brush stabilized in the stand. CAD/CAM, computer-aided design/computer-aided manufacturing.

According to the manufacturer's instructions, specimens from HC resins were fabricated using the conventional flask and pressure-pack technique in a stainless steel mold. The fabricated disks were cleaned with a steam jet, and the excess flash was detached using carbide burs (Black Hawk cutter; Hopf, Ringleb, & Co. GmbH & Cie, Berlin, Germany). Finishing of the surface was done with silicon carbide waterproof paper under water cooling. The polishing of the disks was performed in a compact unit (Derotor, London, England) for the standardization process. The finished and polished disks were cleaned with water and soap using a regular toothbrush to remove any surface contaminants attached to the specimen surface.

UDMA-based LC disks were fabricated using a silicon putty mold. Separating medium was applied to the mold's inner surface, and the base-plate acrylic resin was compacted into the mold cavity by finger pressure. An air barrier coating (Eclipse; Dentsply Trubyte, York, PA, USA) was applied to the resin surface to prevent oxygen from inhibiting polymerization. Polymerization was accomplished in a light-curing unit (Eclipse Processing Unit; Dentsply Trubyte) by exposing the specimens to visible light in the range of 400–500 nm for 10 min.

For CAD/CAM specimens, the disk dimensions were designed using Zenotec CAD software (Wieland Digital Denture; Ivoclar Vivadent, Schaan, Liechtenstein). The CAD/CAM-PMMA blocks were milled using Zenotec selection (Wieland Digital Denture; Ivoclar Vivadent) to obtain the specimens. The finishing and polishing of the LC and CAD/CAM disks followed the same procedure as described above for HC resin disks.

The specimens were subjected to baseline surface roughness measurements using a Bruker 3D optical noncontact profilometer (Contour GT-I; Bruker, Tucson, AZ, USA). The different refractive indices of the components of white light are used in this noninvasive method to measure the differences in height in the specimen's topography. The emitted light beam diffracted by the surface roughness is split into two beams, one of which is directed to a standardized reference mirror and the other to the surface of the evaluated sample outside the lens. The deviation of the light beam on the mirror produces the profilometry image [21].

Several methods assess roughness, but the surface roughness (Ra) value is the most often used and reported in dentistry. The Ra is the average arithmetic height of the roughness irregularities across a specimen's surface area (in microns), calculated from a mean line along the length of the measurement [22]. In this study, the specimen surface was scanned using a 5 × Michelson magnification lens on a 1.5 × 1.5 mm field of view at a scan speed of 1 ×. Each disk was scanned at five different areas, and the roughness values were averaged for that specific specimen.

Surface treatments

The resin disks were subjected to mechanical brushing using an Oral-B power toothbrush (Oral-B Pro 1000; Oral-B, Leicester, United Kingdom) equipped with a brush head (Figure 1B). As per the manufacturer, the CrossAction bristles in the brush head are oriented at 16° angulation with a brushing rate of 20,000 pulsations and 8,800 rpm to perform 3D cleansing. The toothbrush was placed in the toothbrush stand [23], the resin disks were fixed onto the customized sample holder, and the resin surface facing the bristles was brushed with a load of 2 N for 60 min.

The load applied in the present study is in accordance with the International Organization for Standardization (ISO) technical report (ISO/TR 14569-1:2007) for guidance on testing of wear – “Part 1: Wear by toothbrushing for dental materials”. The report specifies a load between 0.5 N and 2.5 N against the specimen. The load was applied using weights suspended and pressed onto the toothbrush head [24].

The brushing time adopted in this laboratory study is consistent with a previously published study. Brushing with toothpaste for 2 min twice a day is recommended, which means that a given tooth surface will only be in contact with the toothbrush for a maximum of 5 s twice a day. As a result, 60 min of brushing simulates 1 year of tooth brushing aging in this study [25].

After brushing, the resin disks from each resin material were randomly allocated into three groups according to the disinfection solutions used. The disks were immersed either in a solution prepared by dissolving one corega tablet (Corega; GSK, Brentford, United Kingdom) in 250 ml of water, NaOCl (0.525%; household bleach diluted in water [1:10, v/v]; Clorox: National Cleaning Products Co., Dammam, Saudi Arabia), or CHG (0.2%; Avohex Mouthwash; Avalon Pharma, Riyadh, Saudi Arabia). The disks were immersed for 2,880 h at room temperature, with solutions being replaced every 8 h. The disks were cleaned and kept in distilled water at room temperature between the immersion processes.

Following immersion, the resin disks were aged by the process of thermal cycling in Huber 1100 thermocycler device (SD Mechatronik, Feldkirchen-Westerham, Germany). A total of 10,000 cycles in a water bath at a temperature between 5 °C and 55 °C, with 30 s dwell time and 15 s transfer time, was applied to simulate approximately 1 year of oral prosthesis use [26].

The final roughness of the specimen surface was determined similarly to the baseline roughness measurements.

Data analysis

Data were analyzed using SPSS (IBM Inc., Chicago, IL, USA) v.24.0 statistical software. Descriptive statistics followed by Tukey's post-hoc test were used to compare the mean surface roughness values of the three types of disinfectants and acrylic resin materials. Two-way analysis of variance (ANOVA) was used to analyze the effect of disinfectants and resin materials on the surface roughness values. The significance level was set at α ≤ 0.05.

Results

The results of ANOVA (Table 1) revealed significant interactions between resin type and disinfectants, indicating that the effects of these two factors were interdependent (F=6.60; p<0.001). In the model, both resin type (F=52.70; p<0.001) and disinfectants (F=7.90; p<0.001) are statistically significant.

Two-way repeated-measures ANOVA results for the interactions between resin type and disinfectants on the roughness values.

Source Type III SS* DF MS F-value p-value
Corrected model 145.99 8 18.24 18.45 0.000*
Intercept 235.61 1 235.61 238.28 0.000*
Resin 104.22 2 52.11 52.70 0.000*
Disinfectants 15.63 2 7.81 7.90 0.001*
Resins×Disinfectants 26.13 4 6.53 6.60 0.000*
Error 80.09 81 0.98
Total 461.70 90

Type III SS infers a significant effect and interaction of the resin type and disinfectants on the surface roughness.

F-value = variation between sample means/variation within the samples; p-value = probability value.

Statistically significant at p ≤ 0.05.

ANOVA, analysis of variance; DF, degrees of freedom (N-1); MS, mean square computed by dividing an SS value by the corresponding DFs; SS, sum of squares.

Table 2 presents the mean baseline surface roughness values of the tested acrylic resin materials. Among the tested materials, CAD/CAM resins demonstrated significantly lower roughness values (0.03±0.02), followed by the LC (0.17±0.03) and HC (0.24±0.06) materials. Although the resin materials underwent identical and standard finishing and polishing techniques, a significant difference was observed in the baseline roughness values (p<0.001).

Mean surface roughness (Ra, μm) of the acrylic resins at baseline.

Acrylic resins N Mean ± SD p-value
HC 30 0.24 ± 0.06 <0.001*
CAD/CAM 30 0.03 ± 0.02
LC 30 0.17 ± 0.03

Indicates statistically significant difference between the resin groups.

CAD/CAM, computer-aided design/computer-aided manufacturing; HC, heat-cured resin; LC, light-cured resin; Ra, average arithmetic height; SD, standard deviation.

Figure 2 presents the mean surface roughness of the acrylic materials following various surface treatments. The highest and lowest Ra values were observed in the HC-CHG (4.68±1.18 μm) and CAD/CAM-NaOCl (0.41±0.39 μm) materials. In the HC resins, the disks immersed in Corega and NaOCl did not show any significant differences in roughness values; however, both these disks were significantly different compared to the disks immersed in CHG (p<0.001). On the contrary, CAD/CAM and LC resins immersed in three different disinfectants showed significant differences in roughness values for the immersion mediums tested (p<0.001).

Fig. 2

Mean surface roughness of the acrylic resins at baseline and following surface treatments. Different lower case letters within the material groups indicate statistically significant differences (p<0.001) between the materials for the disinfectant used. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin; RT, roughness threshold (0.2 μm).

Among the materials, the HC resins demonstrated the overall highest mean roughness values (Ra = 3.27 μm), followed by LC (Ra = 1.58 μm) and CAD/CAM (Ra = 0.47 μm) resins. For the disinfectants used, the overall highest mean roughness value was observed in the disks immersed in CHG (Ra = 2.32 μm), followed by those in Corega (Ra = 1.71 μm) and NaOCl (Ra = 1.28 μm).

The pairwise comparison (Table 3) of the differences in final roughness values for the resin materials was statistically significant between each pair of resin materials tested (p<0.001). On the contrary, the mean difference between the disinfectants was statistically significant only for NaOCl and CHG (p<0.001). No significant difference was observed between the [Corega and CHG] (p=0.066) and [Corega and NaOCl] (p=0.328) groups.

Pairwise comparison of the final surface roughness for the acrylic resins and disinfectants tested.

Group (I) Comparison group (J) Mean difference (I–J) p-value
Acrylic resins

HC CAD/CAM 2.61 0.000*
LC 1.61 0.000*
CAD/CAM HC −2.61 0.000*
LC −0.99 0.001*
LC HC −1.61 0.000*
CAD/CAM 0.99 0.001*

Disinfectants

Corega NaOCl 0.41 0.328
CHG −0.60 0.066
NaOCl Corega −0.41 0.328
CHG −1.01 0.000*
CHG Corega 0.60 0.066
NaOCl 1.01 0.000*

Statistically significant (p≤0.05).

CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin.

The profilometer images of representative resin disks for each material and disinfectant are presented in Figure 3. The CAD/CAM materials showed slight surface profile alterations from the baseline to the final measurements for all the disinfectants tested. The maximum changes in specimen surface were found in the HC specimens, with wearing of the surface seen more evidently in disks immersed in CHG. The LC resins demonstrated moderate surface changes following immersion in the disinfectants tested, except for the disks immersed in NaOCl, which showed slight alterations.

Fig. 3

Surface roughness images of the specimens at baseline and following various surface treatments. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin.

Discussion

In the present study, we evaluated and compared the surface roughness values of prepolymerized CAD/CAM-PMMA acrylic resins with the values of conventional HC-PMMA- and LC-UDMA-based acrylic resin materials. For the same purpose, the acrylic resins were subjected to power brushing, immersion in disinfectant solutions, and aging by thermal cycling. The null hypothesis was rejected based on the study's outcome because there were differences in the surface roughness values among the HC, LC, and CAD/CAM acrylic denture base materials following different surface treatments.

In this study, surface roughness was measured using an optical noncontact profilometer, which is based on the principle of two-beam optical interferometry without any instrument part being physically in contact with the surface being analyzed. Furthermore, a profilometer is a commonly used tool for determining roughness as it provides a quantitative profile of the specimen surface. The average arithmetic height (Ra) was used to express the roughness measurement because of its simplicity in defining and calculating variations in height [27, 28].

The surface treatment protocol chosen for this study was based on commonly applied and effective denture hygiene methods with the aim of simulating the in vivo clinical conditions as meticulously as possible. Mechanical brushing is considered the most standard and common denture hygiene practice, and hence, it was applied to all the groups. Three types of chemical disinfectants were tested because of the usual practice of overnight immersion of dentures in either water or disinfectant solutions. The reported effect of the chemicals on the wear of acrylic resin surface has varied between studies [13]. Furthermore, aging by thermal cycling was applied in hot and cold water baths to clinically simulate the in vivo thermal changes of the resin material following exposure to repeated cyclic stresses [29].

The surface roughness of denture base materials is affected by the material's inherent characteristics, polishing methods, and the operator's manual skills [20]. Thus, the resin disks were prepared and finished by one operator following a standardized polishing protocol in the present study. However, the CAD/CAM resins demonstrated significantly lower roughness values before and after surface treatment, followed by LC and HC resins in that order.

A roughness value of 0.2 μm is considered the clinical threshold that prevents plaque retention and microorganism adherence to dental restorative surfaces [18, 30]. At the baseline, the roughness values were within the clinical threshold values for all the materials. However, following the surface treatments, all three tested materials demonstrated significantly increased roughness values compared to baseline measurements. These values exceeded the clinical threshold values. However, the values were within the range (Ra = 0.7–3.4 μm) reported by Zissis et al. [31] for denture materials, except for the HC-CHG specimens (Ra = 4.6 μm).

CAD/CAM materials are reported to have exceptional baseline surface quality compared to conventional HC-PMMA [7, 8, 20, 32, 33]. However, previous studies did not compare CAD/CAM resins with LC resins and did not follow surface treatment with disinfectants. Accordingly, a robust methodological approach was designed to compare the CAD/CAM resins with conventional resins following surface treatment. The study outcome demonstrates the dominance of CAD/CAM acrylic resin (Ra = 0.47 μm) in terms of surface roughness compared to both LC (Ra = 1.58 μm) and HC (Ra = 0.47 μm) resins.

This could be attributed to the exclusive processing technique of CAD/CAM-PMMA billets, which involves high temperature and pressure values during polymerization. Furthermore, CAD/CAM resins have less residual monomer and lower porosity, contributing to exceptional stability and lower microbial adhesion to the surface [34, 35].

This study was consistent with the findings of Shinawi [36], who demonstrated comparable CAD/CAM resin surfaces initially, as well as clinically acceptable surface characteristics following 3 years of brushing simulation. However, no comparable groups were used in that study. Al-Dwairi et al. [20] compared two brands of prepolymerized CAD/CAM resins with conventional HC-PMMA resins. The authors found encouraging surface characteristics compared to the HC groups. Differences were also found between the two brands of CAD/CAM groups, indicating that different brands of CAD/CAM-PMMA resins may present internal differences in surface properties.

LC resins produced substantially less roughness than HC-PMMA, similar to the results reported by Haselden et al. [11]. The better roughness values of the LC resins relative to HC-PMMA may be attributed to the former's structure, which contains a dimethacrylate resin with a large urethane backbone. Furthermore, an even distribution of the activating agent through the chain is likely to ensure fewer variations during polymerization [11].

Effervescent compounds such as sodium perborate or sodium bicarbonate are used in denture disinfectants. When the sodium perborate in these effervescent tablets dissolves in water, it decomposes to form an alkaline peroxide solution, releasing oxygen and loosening the debris mechanically. Furthermore, these effervescent compounds reduce the malodor by neutralizing the bacterial by-products [37]. Chemical denture disinfectants have different probabilities of producing a change in the surface roughness, and they also produce a varying effect on different materials [16, 38].

The variation in the roughness of the denture resin materials could be attributed to the molecular mechanisms that have been proposed for the alteration of the denture base surfaces following immersion in disinfecting agents. Firstly, the leaching of initiators, plasticizers (e.g. di-n-butyl phthalate), and free monomer present in the acrylic resins leads to an interaction of these components with the disinfectants, resulting in alteration of the physical properties of polymers and leading to the dissolution of particles. However, this interaction might depend on the ionic concentration of the disinfectant [39]. The second possible mechanism is that the acrylic PMMA resin, a known polar material, can absorb water and disinfectant solutions. Water molecules interfere with the attachment of polymer chains, thereby changing the physical properties of the polymer. Absorption of water initially causes softening of the polymeric resin, which affects the frictional forces between the polymer chains. These repeated absorption–desorption cycles may eventually cause irreversible damage to the material due to hydrolytic degradation of the polymer, thereby causing the formation of microcracks [40, 41]. However, these two mechanisms are highly dependent on the immersion time and the concentration of the disinfectant solutions, which might explain the varying surface roughness results in the literature [20].

The results of this study show that CHG (Ra = 2.32 μm) produced the most significant change in Ra values, followed by the corega (Ra = 1.71 μm) and NaOCl (Ra = 1.28 μm) groups, respectively. This outcome contrasts with the systematic review by Schwindling et al. [13]; however, the previous review did not include studies on CAD/CAMPMMA materials.

Regardless of the effectiveness of this solution in contributing to denture cleansing, few considerations could restrict their routine use. The use of chlorhexidine has been reported to affect patient compliance by contributing to brown stains on the acrylic resin [16]. Corega denture cleanser contains oxygen-releasing agents along with enzymes, supporting the hypothesis that oxidation in combination with a strongly alkaline solution can be harmful [42]. Although NaOCl is an effective and commonly recommended disinfecting agent, its use is restricted because it causes the whitening of acrylic resins [17, 43].

This study had a few limitations. Firstly, the study could not simulate the exact in vivo conditions despite the strong methodology applied. In the oral cavity, all three surface treatments (brushing + immersion + thermal cycling) occur simultaneously, whereas, in this study, it was applied independently. Thus, different roughness characteristics of the resin surface could be expected. Furthermore, the inconsistencies in brushing, immersion, and diet between individuals may limit the generalization of the study outcomes. Finally, this study's results could not be compared with previous literature due to the lack of studies on prepolymerized CAD/CAM blocks exposed to disinfectant solutions. Future studies should be directed toward relating the roughness values with plaque accumulation and microbial activity.

Conclusion

Within the limitations of the methodology and testing conditions, prepolymerized CAD/CAM acrylic resin demonstrated superior surface quality following different surface treatments. The roughness of the HC and LC resins exceeded the clinical threshold and the reported roughness values for acrylic resins following surface treatments. Among the disinfectants tested, NaOCl produced overall low roughness values compared to other disinfectants. CAD/CAM acrylic resins could be considered promising materials for the fabrication of dentures considering the quality of surface roughness presented. This could be beneficial in the prevention of plaque accumulation and colonization of microorganisms.

Fig. 1

(A) Prepared specimen; (B) power brush stabilized in the stand. CAD/CAM, computer-aided design/computer-aided manufacturing.
(A) Prepared specimen; (B) power brush stabilized in the stand. CAD/CAM, computer-aided design/computer-aided manufacturing.

Fig. 2

Mean surface roughness of the acrylic resins at baseline and following surface treatments. Different lower case letters within the material groups indicate statistically significant differences (p<0.001) between the materials for the disinfectant used. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin; RT, roughness threshold (0.2 μm).
Mean surface roughness of the acrylic resins at baseline and following surface treatments. Different lower case letters within the material groups indicate statistically significant differences (p<0.001) between the materials for the disinfectant used. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin; RT, roughness threshold (0.2 μm).

Fig. 3

Surface roughness images of the specimens at baseline and following various surface treatments. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin.
Surface roughness images of the specimens at baseline and following various surface treatments. CAD/CAM, computer-aided design/computer-aided manufacturing; CHG, chlorhexidine gluconate; HC, heat-cured resin; LC, light-cured resin.

Pairwise comparison of the final surface roughness for the acrylic resins and disinfectants tested.

Group (I) Comparison group (J) Mean difference (I–J) p-value
Acrylic resins

HC CAD/CAM 2.61 0.000*
LC 1.61 0.000*
CAD/CAM HC −2.61 0.000*
LC −0.99 0.001*
LC HC −1.61 0.000*
CAD/CAM 0.99 0.001*

Disinfectants

Corega NaOCl 0.41 0.328
CHG −0.60 0.066
NaOCl Corega −0.41 0.328
CHG −1.01 0.000*
CHG Corega 0.60 0.066
NaOCl 1.01 0.000*

Two-way repeated-measures ANOVA results for the interactions between resin type and disinfectants on the roughness values.

Source Type III SS* DF MS F-value p-value
Corrected model 145.99 8 18.24 18.45 0.000*
Intercept 235.61 1 235.61 238.28 0.000*
Resin 104.22 2 52.11 52.70 0.000*
Disinfectants 15.63 2 7.81 7.90 0.001*
Resins×Disinfectants 26.13 4 6.53 6.60 0.000*
Error 80.09 81 0.98
Total 461.70 90

Mean surface roughness (Ra, μm) of the acrylic resins at baseline.

Acrylic resins N Mean ± SD p-value
HC 30 0.24 ± 0.06 <0.001*
CAD/CAM 30 0.03 ± 0.02
LC 30 0.17 ± 0.03

Anusavice KJ, Shen C, Rawls HR, editors. Phillips’ science of dental materials. 12th ed. Philadelphia, U S A: Saunders; 2012. AnusaviceKJ ShenC RawlsHR editors Phillips’ science of dental materials 12th ed. Philadelphia, U S A Saunders 2012 Search in Google Scholar

Kanazawa M, Inokoshi M, Minakuchi S, Ohbayashi N. Trial of a CAD/CAM system for fabricating complete dentures. Dent Mater J. 2011;30:93–6. KanazawaM InokoshiM MinakuchiS OhbayashiN Trial of a CAD/CAM system for fabricating complete dentures Dent Mater J 2011 30 93 6 10.4012/dmj.2010-11221282882 Search in Google Scholar

Mahross HZ, Mohamed MD, Hassan AM, Baroudi K. Effect of cigarette smoke on surface roughness of different denture base materials. J Clin Diagn Res. 2015;9(9):ZC39–42. MahrossHZ MohamedMD HassanAM BaroudiK Effect of cigarette smoke on surface roughness of different denture base materials J Clin Diagn Res 2015 9 9 ZC39 42 10.7860/JCDR/2015/14580.6488460633926501010 Search in Google Scholar

Al-Dwairi ZN, Al-Quran FA, Al-Omari OY. The effect of antifungal agents on surface properties of poly(methyl methacrylate) and its relation to adherence of Candida albicans. J Prosthodont Res. 2012;56(4):272–80. Al-DwairiZN Al-QuranFA Al-OmariOY The effect of antifungal agents on surface properties of poly(methyl methacrylate) and its relation to adherence of Candida albicans J Prosthodont Res 2012 56 4 272 80 10.1016/j.jpor.2012.02.00622841909 Search in Google Scholar

Takahashi Y, Yoshida K, Shimizu H. Fracture resistance of maxillary complete dentures subjected to long-term water immersion. Gerodontology. 2012;29(2):e1086–91. TakahashiY YoshidaK ShimizuH Fracture resistance of maxillary complete dentures subjected to long-term water immersion Gerodontology 2012 29 2 e1086 91 10.1111/j.1741-2358.2012.00616.x22260149 Search in Google Scholar

Bidra AS, Farrell K, Burnham D, Dhingra A, Taylor TD, Kuo CL. Prospective cohort pilot study of 2-visit CAD/CAM monolithic complete dentures and implant-retained overdentures: Clinical and patient-centered outcomes. J Prosthet Dent. 2016;115(5):578–86. BidraAS FarrellK BurnhamD DhingraA TaylorTD KuoCL Prospective cohort pilot study of 2-visit CAD/CAM monolithic complete dentures and implant-retained overdentures: Clinical and patient-centered outcomes J Prosthet Dent 2016 115 5 578 86 10.1016/j.prosdent.2015.10.02326794695 Search in Google Scholar

AlHelal A, AlRumaih HS, Kattadiyil MT, Baba NZ, Goodacre CJ. Comparison of retention between maxillary milled and conventional denture bases: A clinical study. J Prosthet Dent. 2017;117(2):233–8. AlHelalA AlRumaihHS KattadiyilMT BabaNZ GoodacreCJ Comparison of retention between maxillary milled and conventional denture bases: A clinical study J Prosthet Dent 2017 117 2 233 8 10.1016/j.prosdent.2016.08.00727765399 Search in Google Scholar

Steinmassl PA, Wiedemair V, Huck C, Klaunzer F, Steinmassl O, Grunert I, et al. Do CAD/CAM dentures really release less monomer than conventional dentures? Clin Oral Investig. 2017;21(5):1697–705. SteinmasslPA WiedemairV HuckC KlaunzerF SteinmasslO GrunertI Do CAD/CAM dentures really release less monomer than conventional dentures? Clin Oral Investig 2017 21 5 1697 705 10.1007/s00784-016-1961-6544223627704295 Search in Google Scholar

Paranhos HF, Silva-Lovato CH, Souza RF, Cruz PC, Freitas KM, Peracini A. Effects of mechanical and chemical methods on denture biofilm accumulation. J Oral Rehabil. 2007;34(8):606–12. ParanhosHF Silva-LovatoCH SouzaRF CruzPC FreitasKM PeraciniA Effects of mechanical and chemical methods on denture biofilm accumulation J Oral Rehabil 2007 34 8 606 12 10.1111/j.1365-2842.2007.01753.x17650171 Search in Google Scholar

Keng SB, Lim M. Denture plaque distribution and the effectiveness of a perborate-containing denture cleanser. Quintessence Int. 1996;27(5):341–5. KengSB LimM Denture plaque distribution and the effectiveness of a perborate-containing denture cleanser Quintessence Int 1996 27 5 341 5 Search in Google Scholar

Haselden CA, Hobkirk JA, Pearson GJ, Davies EH. A comparison between the wear resistance of three types of denture resin to three different dentifrices. J Oral Rehabil. 1998;25(5):335–9. HaseldenCA HobkirkJA PearsonGJ DaviesEH A comparison between the wear resistance of three types of denture resin to three different dentifrices J Oral Rehabil 1998 25 5 335 9 10.1046/j.1365-2842.1998.00250.x9639156 Search in Google Scholar

Peracini A, Davi LR, de Queiroz Ribeiro N, de Souza RF, da Silva CH, Paranhos HD. Effect of denture cleansers on physical properties of heat-polymerized acrylic resin. J Prosthodont Res. 2010;54(2):78–83. PeraciniA DaviLR de Queiroz RibeiroN de SouzaRF da SilvaCH ParanhosHD Effect of denture cleansers on physical properties of heat-polymerized acrylic resin J Prosthodont Res 2010 54 2 78 83 10.1016/j.jpor.2009.11.00420083448 Search in Google Scholar

Schwindling FS, Rammelsberg P, Stober T. Effect of chemical disinfection on the surface roughness of hard denture base materials: A systematic literature review. Int J Prosthodont. 2014;27(3):215–25. SchwindlingFS RammelsbergP StoberT Effect of chemical disinfection on the surface roughness of hard denture base materials: A systematic literature review Int J Prosthodont 2014 27 3 215 25 10.11607/ijp.3759 Search in Google Scholar

Ellepola AN, Samaranayake LP. Oral candidal infections and antimycotics. Crit Rev Oral Biol Med. 2000;11(2):172–98. EllepolaAN SamaranayakeLP Oral candidal infections and antimycotics Crit Rev Oral Biol Med 2000 11 2 172 98 10.1177/10454411000110020301 Search in Google Scholar

Machado AL, Giampaolo ET, Pavarina AC, Jorge JH, Vergani CE. Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation. Gerodontology. 2012;29(2):e375–82. MachadoAL GiampaoloET PavarinaAC JorgeJH VerganiCE Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation Gerodontology 2012 29 2 e375 82 10.1111/j.1741-2358.2011.00484.x Search in Google Scholar

Aoun G, Saadeh M, Berberi A. Effectiveness of hexetidine 0.1% compared to chlorhexidine digluconate 0.12% in eliminating Candida albicans colonizing dentures: A Randomized Clinical in Vivo Study. J Int Oral Health. 2015;7(8):5–8. AounG SaadehM BerberiA Effectiveness of hexetidine 0.1% compared to chlorhexidine digluconate 0.12% in eliminating Candida albicans colonizing dentures: A Randomized Clinical in Vivo Study J Int Oral Health 2015 7 8 5 8 Search in Google Scholar

Orsi IA, Junior AG, Villabona CA, Fernandes FH, Ito IY. Evaluation of the efficacy of chemical disinfectants for disinfection of heat-polymerised acrylic resin. Gerodontology. 2011;28(4):253–7. OrsiIA JuniorAG VillabonaCA FernandesFH ItoIY Evaluation of the efficacy of chemical disinfectants for disinfection of heat-polymerised acrylic resin Gerodontology 2011 28 4 253 7 10.1111/j.1741-2358.2010.00400.x Search in Google Scholar

Bollen CM, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: A review of the literature. Dent Mater. 1997;13(4):258–69. BollenCM LambrechtsP QuirynenM Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: A review of the literature Dent Mater 1997 13 4 258 69 10.1016/S0109-5641(97)80038-3 Search in Google Scholar

Alp G, Johnston WM, Yilmaz B. Optical properties and surface roughness of prepolymerized poly(methyl methacrylate) denture base materials. J Prosthet Dent. 2019;121(2):347–52. AlpG JohnstonWM YilmazB Optical properties and surface roughness of prepolymerized poly(methyl methacrylate) denture base materials J Prosthet Dent 2019 121 2 347 52 10.1016/j.prosdent.2018.03.00130143239 Search in Google Scholar

Al-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ, Özcan M. A comparison of the surface properties of CAD/CAM and Conventional Polymethylmethacrylate (PMMA). J Prosthodont. 2019;28(4):452–7. Al-DwairiZN TahboubKY BabaNZ GoodacreCJ ÖzcanM A comparison of the surface properties of CAD/CAM and Conventional Polymethylmethacrylate (PMMA) J Prosthodont 2019 28 4 452 7 10.1111/jopr.1303330730086 Search in Google Scholar

Baysan A, Sleibi A, Ozel B, Anderson P. The quantification of surface roughness on root caries using noncontact optical profilometry–An in vitro study. Lasers Dent Sci. 2018;2(4):229–37. BaysanA SleibiA OzelB AndersonP The quantification of surface roughness on root caries using noncontact optical profilometry–An in vitro study Lasers Dent Sci 2018 2 4 229 37 10.1007/s41547-018-0041-4 Search in Google Scholar

Uppal M, Ganesh A, Balagopal S, Kaur G. Profilometric analysis of two composite resins’ surface repolished after tooth brush abrasion with three polishing systems. J Conserv Dent. 2013;16(4):309–13. UppalM GaneshA BalagopalS KaurG Profilometric analysis of two composite resins’ surface repolished after tooth brush abrasion with three polishing systems J Conserv Dent 2013 16 4 309 13 10.4103/0972-0707.114356374064023956531 Search in Google Scholar

Schätzle M, Sener B, Schmidlin PR, Imfeld T, Attin T. In vitro tooth cleaning efficacy of electric toothbrushes around brackets. Eur J Orthodont. 2010;32(5):481–9. SchätzleM SenerB SchmidlinPR ImfeldT AttinT In vitro tooth cleaning efficacy of electric toothbrushes around brackets Eur J Orthodont 2010 32 5 481 9 10.1093/ejo/cjp16620551084 Search in Google Scholar

ISO/TR-14569-1:2007. Dental materials-Guidance on testing of wear-Part 1: Wear by toothbrushing. Geneva: International Organization for Standardization; 2007. ISO/TR-14569-1:2007 Dental materials-Guidance on testing of wear-Part 1: Wear by toothbrushing Geneva International Organization for Standardization 2007 Search in Google Scholar

Hooper S, West NX, Pickles MJ, Joiner A, Newcombe RG, Addy M. Investigation of erosion and abrasion on enamel and dentine: A model in situ using toothpastes of different abrasivity. J Clin Periodontol. 2003;30(9):802–8. HooperS WestNX PicklesMJ JoinerA NewcombeRG AddyM Investigation of erosion and abrasion on enamel and dentine: A model in situ using toothpastes of different abrasivity J Clin Periodontol 2003 30 9 802 8 10.1034/j.1600-051X.2003.00367.x Search in Google Scholar

Gale MS, Darvell BW. Thermal cycling procedures for laboratory testing of dental restorations. J Dent. 1999;27(2):89–99. GaleMS DarvellBW Thermal cycling procedures for laboratory testing of dental restorations J Dent 1999 27 2 89 99 10.1016/S0300-5712(98)00037-2 Search in Google Scholar

Ayaz EA, Ustun S. Effect of staining and denture cleaning on color stability of differently polymerized denture base acrylic resins. Niger J Clin Pract. 2020;23(3):304–9. AyazEA UstunS Effect of staining and denture cleaning on color stability of differently polymerized denture base acrylic resins Niger J Clin Pract 2020 23 3 304 9 Search in Google Scholar

Asiry MA, AlShahrani I, Almoammar S, Durgesh BH, Al Kheraif AA, Hashem MI. Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires. Mater Res Express. 2018;5(2):026511. AsiryMA AlShahraniI AlmoammarS DurgeshBH Al KheraifAA HashemMI Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires Mater Res Express 2018 5 2 026511 10.1088/2053-1591/aaabe5 Search in Google Scholar

Kohli S, Bhatia S. Polyamides in dentistry-A Review. Int J Sci Study. 2013;1(1):20–5. KohliS BhatiaS Polyamides in dentistry-A Review Int J Sci Study 2013 1 1 20 5 Search in Google Scholar

Radford D, Challacombe SJ, Walter JD. Denture plaque and adherence of Candida albicans to denture-base materials in vivo and in vitro. Crit Rev Oral Biol Med. 1999;10(1):99–116. RadfordD ChallacombeSJ WalterJD Denture plaque and adherence of Candida albicans to denture-base materials in vivo and in vitro Crit Rev Oral Biol Med 1999 10 1 99 116 10.1177/10454411990100010501 Search in Google Scholar

Zissis AJ, Polyzois GL, Yannikakis SA, Harrison A. Roughness of denture materials: A comparative study. Int J Prosthodont. 2000;13(2):136–40. ZissisAJ PolyzoisGL YannikakisSA HarrisonA Roughness of denture materials: A comparative study Int J Prosthodont 2000 13 2 136 40 Search in Google Scholar

Ayman AD. The residual monomer content and mechanical properties of CAD CAM resins used in the fabrication of complete dentures as compared to heat cured resins. Electron Phys. 2017;9(7):4766. AymanAD The residual monomer content and mechanical properties of CAD CAM resins used in the fabrication of complete dentures as compared to heat cured resins Electron Phys 2017 9 7 4766 10.19082/4766 Search in Google Scholar

Kattadiyil MT, Jekki R, Goodacre CJ, Baba NZ. Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting. J Prosthet Dent. 2015;114(6):818–25. KattadiyilMT JekkiR GoodacreCJ BabaNZ Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting J Prosthet Dent 2015 114 6 818 25 10.1016/j.prosdent.2015.08.001 Search in Google Scholar

Cortés-Sandoval G, Martínez-Castañón GA, Patiño-Marín N, Martínez-Rodríguez PR, Loyola-Rodríguez JP. Surface roughness and hardness evaluation of some base metal alloys and denture base acrylics used for oral rehabilitation. Mater Lett. 2015;144:100–5. Cortés-SandovalG Martínez-CastañónGA Patiño-MarínN Martínez-RodríguezPR Loyola-RodríguezJP Surface roughness and hardness evaluation of some base metal alloys and denture base acrylics used for oral rehabilitation Mater Lett 2015 144 100 5 10.1016/j.matlet.2015.01.035 Search in Google Scholar

Bidra AS, Taylor TD, Agar JR. Computer-aided technology for fabricating complete dentures: Systematic review of historical background, current status, and future perspectives. J Prosthet Dent. 2013;109(6):361–6. BidraAS TaylorTD AgarJR Computer-aided technology for fabricating complete dentures: Systematic review of historical background, current status, and future perspectives J Prosthet Dent 2013 109 6 361 6 10.1016/S0022-3913(13)60318-2 Search in Google Scholar

Shinawi LA. Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base. Electron Phys. 2017;9(5):4281–88. ShinawiLA Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base Electron Phys 2017 9 5 4281 88 10.19082/4281549868928713496 Search in Google Scholar

Felton D, Cooper L, Duqum I, Minsley G, Guckes A, Haug S, et al. Evidence-based guidelines for the care and maintenance of complete dentures. J Prosthodont. 2011;20:S1–2. FeltonD CooperL DuqumI MinsleyG GuckesA HaugS Evidence-based guidelines for the care and maintenance of complete dentures J Prosthodont 2011 20 S1 2 10.14219/jada.archive.2011.0067 Search in Google Scholar

Arruda CN, Sorgini DB, Oliveira VD, Macedo AP, Lovato CH, Paranhos HD. Effects of denture cleansers on heat-polymerized acrylic resin: A five-year-simulated period of use. Br Dent J. 2015;26:404–8. ArrudaCN SorginiDB OliveiraVD MacedoAP LovatoCH ParanhosHD Effects of denture cleansers on heat-polymerized acrylic resin: A five-year-simulated period of use Br Dent J 2015 26 404 8 10.1590/0103-644020130012026312981 Search in Google Scholar

Brozek R, Rogalewicz R, Koczorowski R, Voelkel A. The influence of denture cleansers on the release of organic compounds from soft lining materials. J Environ Monit. 2008;10(6):770–4. BrozekR RogalewiczR KoczorowskiR VoelkelA The influence of denture cleansers on the release of organic compounds from soft lining materials J Environ Monit 2008 10 6 770 4 10.1039/b719825f18528545 Search in Google Scholar

Davi LR, Felipucci DN, Souza RF, Bezzon OL, Lovato-Silva CH, Pagnano VO, et al. Effect of denture cleansers on metal ion release and surface roughness of denture base materials. Br Dent J. 2012;23(4):387–93. DaviLR FelipucciDN SouzaRF BezzonOL Lovato-SilvaCH PagnanoVO Effect of denture cleansers on metal ion release and surface roughness of denture base materials Br Dent J 2012 23 4 387 93 10.1590/S0103-6440201200040001323207854 Search in Google Scholar

Pereira CJ, Genari B, Leitune VC, Collares FM, Samuel SM. Effect of immersion in various disinfectant solutions on the properties of a heat-cured acrylic resin. Re-vista Gaúcha de Odontologia. 2019;67:e20190052. PereiraCJ GenariB LeituneVC CollaresFM SamuelSM Effect of immersion in various disinfectant solutions on the properties of a heat-cured acrylic resin Re-vista Gaúcha de Odontologia 2019 67 e20190052 10.1590/1981-86372019000523090 Search in Google Scholar

Unlü A, Altay OT, Sahmali S. The role of denture cleansers on the whitening of acrylic resins. Int J Prosthodont. 1996;9(3):266–70. UnlüA AltayOT SahmaliS The role of denture cleansers on the whitening of acrylic resins Int J Prosthodont 1996 9 3 266 70 Search in Google Scholar

Salles MM, Oliveira VD, Souza RF, Silva CH, Paranhos HD. Antimicrobial action of sodium hypochlorite and castor oil solutions for denture cleaning in vitro evaluation. Br Oral Res. 2015;29:1–6. SallesMM OliveiraVD SouzaRF SilvaCH ParanhosHD Antimicrobial action of sodium hypochlorite and castor oil solutions for denture cleaning in vitro evaluation Br Oral Res 2015 29 1 6 10.1590/1807-3107BOR-2015.vol29.010426313346 Search in Google Scholar

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