Effects of sonic and micro-vibration electric toothbrushes on the surface roughness and gloss of resin composites

Abstract

Objectives

Electric toothbrushes with various features are used as an alternative to manual toothbrushes to protect oral health. This study aimed to evaluate the effects of different types of electric toothbrushes on the surface topography and gloss of resin composites.

Materials and methods

In this study, microhybrid, nanohybrid and supra-nano resin composite specimens (10 × 2 mm) were prepared in a silicon mold. After polishing using diamond spirals, the initial topography (Ra, Sa) and gloss values ​​were measured. The specimens were then brushed with a conventional toothpaste for 4 and 8 min using sonic and micro-vibration electric toothbrushes. A manual toothbrush served as the control group. Following toothbrushing, the surface topography and gloss of the resin composites were evaluated. Surface roughness and gloss data were analyzed using two-way analysis of variance (ANOVA) (p < 0.05).

Results

The simulated toothbrushing process significantly increased the Ra and Sa values of the resin composites (p < 0.05). The greatest increase in surface roughness was observed among the microhybrid and nanohybrid composites (p < 0.05), while the supra-nano composite with spherical fillers exhibited the lowest Ra and Sa values. Sonic and micro-vibration electric toothbrushes increased the surface roughness of resin composites more than the manual toothbrush (p < 0.05). The initial surface gloss of the composites exceeded 80 GU. Electric toothbrushes caused a significantly greater reduction in surface gloss compared with the manual toothbrush (p < 0.05).

Conclusions

Electric toothbrushes increase the surface roughness and reduce the gloss of resin composites. The surface gloss and roughness of resin composites are influenced by filler particle size.

Clinical relevance

The use of electric toothbrushes increases the surface roughness of resin composites to a greater extent than manual toothbrushing, while simultaneously reducing surface gloss.

Introduction

Manual toothbrushes are preferred because they are inexpensive and relatively easy to use for maintaining oral health by removing bacterial plaque from tooth surfaces [1]. The plaque removal efficiency of electric toothbrushes has improved through design innovations such as enhanced brush head structures, optimized filament alignment, and increased motion dynamics [2]. Currently, electric toothbrushes featuring oscillation-rotation, micro-vibration, and high-frequency sonic technologies are among the most widely available commercial products worldwide [3].

Oral-B has introduced toothbrushes that combine the oscillation-rotation mechanism with micro-vibrations generated during plaque removal. This design employs a linear magnetic drive, differing from the gear-based motors used in previous oscillation-rotation models. Sonic toothbrushes, on the other hand, produce high-frequency acoustic vibrations through lateral oscillation of the brush filaments, reaching up to 40,000 movements per minute. The high-speed vibration of the filaments facilitates the mechanical removal of biofilm adhering to tooth surfaces [4].

Various antimicrobial agents are incorporated into chemical plaque control products such as toothpastes and mouthwashes to reduce the growth of dental biofilm. Toothpastes, available in numerous formulations, are designed not only to remove plaque but also to minimize color changes in teeth and restorations over time [5, 6]. However, prolonged toothbrushing with highly abrasive toothpastes may accelerate the degradation of restorative materials and compromise their esthetic appearance [7, 8].

Toothpastes contain numerous components, among which abrasives play a key role in removing stains from teeth and resin composites [9]. The abrasiveness of toothbrushing has a considerable impact on the performance of resin composite materials, as it increases surface roughness and consequently deteriorates the esthetic quality of restorations [10]. Previous studies have reported that abrasive agents negatively affect the color stability of restorations [11]. This effect has been associated with increased surface porosity, which enhances material mass loss and water sorption, ultimately leading to more pronounced color changes [12].

Throughout the development of resin composites, continuous efforts have been made to improve their physical, mechanical, chemical, and esthetic properties. Modern resin composites exhibit enhanced characteristics such as reduced polymerization shrinkage and increased compressive strength [13]. However, issues related to color stability and surface roughness remain inherent to these materials. Previous studies have reported that direct restorations fabricated with conventional composites exhibit changes in surface roughness over time [6, 11, 14, 15]. Surface roughness can be assessed quantitatively using profilometry and qualitatively using scanning electron microscopy (SEM) [16]. According to Bollen et al. [17], the threshold value for the optimal surface roughness of dental materials was determined to be 0.2 μm. The surface roughness of restorative materials plays a critical role in bacterial adhesion, biofilm formation, and surface staining.

The gloss of resin composites represents the material’s ability to reflect light from its surface. A higher gloss level provides better visual harmony with adjacent natural teeth [18]. Previous studies have shown that the polishing behavior of resin composites varies according to filler particle size, with smaller particles yielding higher gloss values after polishing [19]. Although aging and mechanical fatigue have been reported to contribute to gloss deterioration, toothbrushing has also been identified as a significant factor affecting the gloss of resin-based restorative materials [20].

With advances in technology, the design and performance features of electric toothbrushes continue to evolve. Therefore, it is important to evaluate the effects of newly developed electric toothbrushes used in daily oral hygiene on the surface characteristics of composite restorations. This study aimed to investigate the effects of sonic and micro-vibration electric toothbrushes on the surface roughness and gloss of resin composites. The null hypothesis was that the two types of electric toothbrushes would not alter the surface properties of composite restorations.

Materials and methods

Three types of conventional resin composites were used in this study: microhybrid (G-aenial Anterior, GC Corporation, Tokyo, Japan), nanohybrid (Clearfil Majesty ES-2 Classic, Kuraray Noritake, Tokyo, Japan), and supra-nano (Estelite Sigma Quick, Tokuyama Dental, Tokyo, Japan) (Table 1). The sample size was calculated using G*Power software (version 3.1; Heinrich-Heine-University, Düsseldorf, Germany) for a large effect size (f = 0.40), a significance level of α = 0.05, and a statistical power of 80% (1 − β = 0.80). A total of 108 specimens were prepared (n = 36 for each composite). Each group of resin composite specimens was further divided into three subgroups (n = 12) according to the brushing method: sonic electric toothbrush, micro-vibration electric toothbrush, and manual toothbrush (Fig. 1).

Table 1.

Resin composite materials used in the study and their composition details

Resin Composite	Filler type	Composition	Fillers particle size	Fillers ratio	Lot
G-aenial Anterior (GC Corporation, Tokyo, Japan)	Microhybrid	Monomer matrix: UDMA, dimethacrylate co monomers Inorganic filler: Prepolymerized silica, strontium and lanthanoid flüoride, Silica glass, fumed silica	Pre-polymerized fillers 16–17 μm Silica glass 850 nm, Fumed silica 16 nm	76 wt%	2,111,011
Clearfil Majesty ES-2 Classic (Kuraray Noritake, Tokyo, Japan)	Nanohybrid	Monomer matrix: Bis-GMA, Hydrophobic aromatic dimethacrylate Inorganic filler: Silanated barium glass filler, Pre-polymerized filler	Barium glass 0.37 μm to 1.5 μm.	78 wt%, including inorganic filler of 40 vol%	5C0151
Estelite Sigma Quick (Tokuyama Dental, Tokyo, Japan)	Supra-nano	Monomer matrix: Bis-GMA and TEGDMA Inorganic filler: silica-zirconia filler and composite filler	spherical submicron filler 0.2 μm	82% by weight (71% by volume)	E9024

Fig. 1.

Flowchart of the sampling distribution and study methodology

Preparation of specimens

Disc-shaped specimens with a diameter of 10 mm and a height of 2 mm were fabricated using a silicone mold. A composite spatula (ColoriSilikon 2.0/2.25, Carl Martin, Germany) was used to place the resin composite into the mold, which was then covered with a 1 mm-thick glass coverslip. The specimens were polymerized for 20 s at an irradiance of 1000 mW/cm² using an LED light-curing unit (DTE O-Light Plus, Germany) in direct contact with the glass coverslip. Polishing was performed by a single operator using an anguldruva (Goldspeed Evo S1-L, Stern Weber, Italy) connected to the same brand dental unit. A two-step finishing and polishing system (Clearfil Twist Dia, Kuraray Noritake, Tokyo, Japan) was employed for all specimens under water cooling (10,000 rpm) for 20 s. Following the polishing procedures, the specimens were stored in distilled water at 37 °C for 24 h in an incubator (FN 500, Nüve, Turkey).

Surface roughness measurement

The initial surface characteristics of the polished composite specimens were examined using a confocal microscope (Smartproof 5, Zeiss, Germany). Surface topography was quantified using the arithmetic mean roughness (Ra) and area-related mean arithmetic height (Sa) parameters. Prior to measurement, the confocal profilometer was calibrated according to the manufacturer’s instructions. Images were obtained from a 0.5 × 0.5 μm area using a 20×/0.7 objective lens and analyzed with surface metrology software (ConfoMap ST 9.3.10494, Zeiss, Germany). The same software was used to generate three-dimensional surface topography maps of the resin composite specimens. Surface roughness values of all specimens were determined as the mean of three measurements obtained from the central region of each specimen. After baseline measurements of all specimens, surface roughness was re-measured following 4 and 8 min of toothbrushing.

Gloss measurement

The surface gloss of the composite specimens was evaluated using a gloss meter (Novo-Curve, Rhopoint, UK). Each specimen was positioned in the measurement area of the device and shielded from external light with a black film container during measurement. The instrument was calibrated before each composite group measurement using the manufacturer-provided calibration plate (93.3 GU). Gloss measurements were performed over a 2 × 2 mm area at a 60° geometry according to ISO 2813. Gloss values of all specimens were determined as the mean of three measurements obtained from the central region of each specimen. After baseline measurements of all specimens, gloss was re-measured following 4 and 8 min of toothbrushing.

Simulated toothbrushing

After examining the surface properties of the composite specimens, they were brushed for 4 and 8 min using a conventional toothpaste (Colgate Total 12) and electric toothbrushes (Oral-B iO 6, Braun, Germany; and Philips Sonicare 5100, Philips, The Netherlands) [21]. The Philips Sonicare 5100 electric toothbrush was used in the standard mode with the Sonicare 2 W toothbrush head, while the Oral-B iO 6 electric toothbrush was used in the standard mode with the Oral-B iO ultimate clean toothbrush head. A slurry of toothpaste and distilled water (1:1 ratio) was used during the brushing process. The electric toothbrushing process was carried out using a setup similar to that described in the studies by Ximinis et al. [22] with the brush head in direct contact with the specimens (Fig. 2). The electric toothbrush was fixed to an assembly that allowed the brush head to be aligned parallel to the specimen surface, with the applied force maintained at a constant value. The brush head contacted the specimen surface with a force of 2 N. For each specimen, 0.2 g of toothpaste was mixed with an equal amount of water and applied by brushing, with the toothpaste being renewed every minute. A 120 s toothbrushing process corresponds to 2 min of brushing performed twice daily. In this study, the brushing time per tooth was determined based on an average daily brushing duration of 8 s. The 4 min brushing process of the specimens simulated approximately one month of brushing [21]. After brushing, all specimens were cleaned in an ultrasonic cleaner for 5 min, and the surface roughness of the composite specimens was measured again.

Fig. 2.

Toothbrushing mechanisms (a electric toothbrush; b manual toothbrush)

As a control group, a soft manual toothbrush (Gentle Care, Oral-B) was used in a brushing simulator (MF-100, Mod Dental, Turkey) (Fig. 2). After the resin composite specimens were fixed on the glass coverslip and placed in the brushing simulator, toothpaste (Colgate Total 12, diluted 1:1 with distilled water) was applied, and brushing was performed. Mozzaquatro et al. [23] reported in their study that a person brushes each tooth surface for 8 s per day at a frequency of 2 strokes per second, which corresponds to 16 strokes per tooth surface per day. Accordingly, a frequency of 585 strokes represents approximately one month of in vivo toothbrushing. In this study, to simulate 1 and 2 months of toothbrushing, a manual brush was used at a frequency of 585 and 1,170 strokes, respectively, at a rate of 2 strokes per second, using a 200 g toothbrush load, with a circular motion of 15 mm in diameter and a motion speed of 40 mm/s.

Scanning Electron Microscope (SEM)

One specimen from each group of resin composites used in the study was examined using a scanning electron microscope (SEM; ZEISS EVO 40, Germany). Prior to SEM analysis, the surfaces of the specimens to be examined were sputter-coated with gold using the Emitech K550 device. Each specimen was examined at an accelerating voltage of 20 kV and a magnification of 5,000x.

Statistical analysis

Statistical analysis was performed using SPSS software (version 22.0; IBM Corp., Armonk, NY, USA). The normality of surface roughness (Ra and Sa) data was assessed using the Kolmogorov–Smirnov test. Surface roughness and gloss data were analyzed using two-way analysis of variance (ANOVA) followed by Tukey’s post hoc test (p < 0.05).

Results

Electric toothbrushes caused statistically greater increases in the Ra and Sa values of resin composite compared to manual toothbrushes (p < 0.05). No statistically significant differences were found between the electric toothbrushes (Tables 2, 3 and 5). The highest Ra values were observed in the nanohybrid composite after 8 min of electric toothbrushing (Oral-B iO 6: 0.328 ± 0.01 μm; Philips Sonicare 5100: 0.342 ± 0.01 μm; p < 0.05). After 8 min of electric toothbrushing, the lowest Ra values were observed in the supra-nano resin composite (Oral-B iO 6: 0.198 ± 0.01 μm; Philips Sonicare 5100: 0.203 ± 0.02 μm). Electric toothbrushes caused a statistically significant increase in the Sa values of resin composites (p < 0.05). The highest Sa values were observed in the nanohybrid composite after 8 min of electric toothbrushing (Oral-B iO 6: 0.420 ± 0.03 μm; Philips Sonicare 5100: 0.444 ± 0.03 μm; p < 0.05). After 8 min of electric toothbrushing, the lowest Sa values were observed in the supra-nano resin composite (Oral-B iO 6: 0.240 ± 0.03 μm; Philips Sonicare 5100: 0.258 ± 0.03 μm). The surface roughness values (Ra and Sa) produced by electric toothbrushes on resin composites followed the order: nanohybrid > microhybrid > supra-nano resin composites.

Table 2.

Arithmetic mean roughness (Ra, µm) values of resin composites before and after simulated toothbrushing

Resin Composite / Toothbrush		Micro-vibration	Sonic	Manual Toothbrush
Microhybrid (G-aenial Anterior, GC Corporation, Japan)	Initial	0.214 ± 0.01a, A	0.224 ± 0.01a, A	0.201 ± 0.01a, A
	4 min	0.251 ± 0.01b, A	0.266 ± 0.02b, A	0.222 ± 0.01a, B
	8 min	0.270 ± 0.01c, A	0.285 ± 0.02c, A	0.239 ± 0.02b, B
Nanohybrid (Clearfil Majesty ES-2 Classic, Kuraray Noritake, Japan)	Initial	0.229 ± 0.01a, A	0.233 ± 0.02a, A	0.214 ± 0.01a, A
	4 min	0.301 ± 0.02d, A	0.315 ± 0.02d, A	0.236 ± 0.01b, B
	8 min	0.328 ± 0.02e, A	0.342 ± 0.01e, A	0.244 ± 0.01b, B
Supra-nano (Estelite Sigma Quick, Tokuyama Dental, Japan)	Initial	0.161 ± 0.01f, A	0.163 ± 0.01f, A	0.161 ± 0.01cA
	4 min	0.186 ± 0.01g, A	0.188 ± 0.01g, A	0.164 ± 0.01c, B
	8 min	0.198 ± 0.01g, A	0.203 ± 0.02g, A	0.179 ± 0.01d, B

Statistically significant differences in the arithmetic mean roughness (Ra, µm) values of the resin composites after toothbrushing are denoted by ^a–g, whereas differences according to toothbrush type are indicated by ^A–B (p < 0.05)

Table 3.

Area-related mean arithmetic height (Sa, µm) values of resin composites before and after simulated toothbrushing

Resin Composite / Toothbrush		Micro-vibration	Sonic	Manual Toothbrush
Microhybrid (G-aenial Anterior, GC Corporation, Japan)	Initial	0.257 ± 0.02a, A	0.267 ± 0.01a, A	0.249 ± 0.02a, A
	4 min	0.296 ± 0.02b, A	0.316 ± 0.03b, A	0.270 ± 0.01a, B
	8 min	0.315 ± 0.02c, A	0.335 ± 0.02bB	0.294 ± 0.02b, AB
Nanohybrid (Clearfil Majesty ES-2 Classic, Kuraray Noritake, Japan)	Initial	0.285 ± 0.02c, A	0.298 ± 0.03c, A	0.283 ± 0.01b, A
	4 min	0.401 ± 0.05d, A	0.408 ± 0.05d, A	0.313 ± 0.01c, B
	8 min	0.420 ± 0.03d, A	0.444 ± 0.03e, A	0.332 ± 0.02d, B
Supra-nano (Estelite Sigma Quick, Tokuyama Dental, Japan)	Initial	0.192 ± 0.02e, A	0.196 ± 0.02f, A	0.201 ± 0.01e, A
	4 min	0.222 ± 0.03f, A	0.228 ± 0.03g, A	0.218 ± 0.01ef, A
	8 min	0.240 ± 0.03f, A	0.258 ± 0.03g, A	0.232 ± 0.01f, B

Statistically significant differences in the area-related mean arithmetic height (Sa, µm) values of the resin composites after toothbrushing are denoted by ^a–g, whereas differences according to toothbrush type are indicated by ^A–B (p < 0.05)

Table 5.

Two-way ANOVA for surface properties

Surface Properties	Factor	p-value
Arithmetic Mean Roughness (Ra)	Resin Composite	< 0.001
	Toothbrush	< 0.001
	Toothbrushing Time	< 0.001
	Resin Composite x Toothbrush	< 0.001
	Resin Composite x Toothbrushing Time	< 0.001
	Toothbrush x Toothbrushing Time	< 0.001
Area-related Mean Arithmetic Height (Sa)	Resin Composite	< 0.001
	Toothbrush	< 0.001
	Toothbrushing Time	< 0.001
	Resin Composite x Toothbrush	< 0.001
	Resin Composite x Toothbrushing Time	< 0.001
	Toothbrush x Toothbrushing Time	< 0.001
Gloss	Resin Composite	< 0.001
	Toothbrush	< 0.001
	Toothbrushing Time	< 0.001
	Resin Composite x Toothbrush	< 0.001
	Resin Composite x Toothbrushing Time	< 0.001
	Toothbrush x Toothbrushing Time	< 0.001

3D surface analysis of the microhybrid and nanohybrid resin composites revealed that inorganic filler particles became exposed due to surface wear (Figs. 3 and 4). This wear was less pronounced in the supra-nano composite (Fig. 5). SEM analysis of the resin composites showed that the organic matrix was worn on the surface after brushing compared to the initial surface characteristics (Figs. 6 and 7, and 8). These changes were more evident in the microhybrid and nanohybrid composites. SEM analysis also indicated that the manual toothbrush caused less alteration on the surface of the resin composites than the electric toothbrush.

Fig. 3.

Three-dimensional surface profile analysis of microhybrid resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Fig. 4.

Three-dimensional surface profile analysis of nanohybrid resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Fig. 5.

Three-dimensional surface profile analysis of supra-nano resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Fig. 6.

SEM analysis of microhybrid resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Fig. 7.

SEM analysis of nanohybrid resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Fig. 8.

SEM analysis of supra-nano resin composites showing surface changes induced by electric and manual toothbrushes. a Oral-B iO 6 initial, b Oral-B iO 6 4 min, c Oral-B iO 6 8 min, d Philips Sonicare 5100 initial, e Philips Sonicare 5100 4 min, f Philips Sonicare 5100 8 min, g manual initial, h manual 585 strokes, i manual 1170 strokes

Initially, the gloss values of the resin composites ranged from 84.1 to 87.3 GU. After brushing, there was a statistically significant decrease in the gloss values of the resin composites (Tables 4 and 5). After 8 min of electric toothbrushing simulation, the gloss values ranged from 11.7 to 39.4 GU. Following manual toothbrushing simulation, gloss values ranged between 40.7 and 56.5 GU. The smallest gloss change in the resin composites was observed after manual toothbrushing. After brushing, the surface gloss values of all composites remained below the clinically acceptable level (50 GU). The greatest gloss reduction occurred in the microhybrid composite, while the supra-nano composite exhibited the least change (p < 0.05). There was no statistically significant difference between the sonic and micro-vibration electric toothbrushes (p > 0.05).

Table 4.

Gloss (GU) values of resin composites before and after simulated toothbrushing

Resin Composite / Toothbrush		Micro-vibration	Sonic	Manual Toothbrush
Microhybrid (G-aenial Anterior, GC Corporation, Japan)	Initial	84.5 ± 1.5a, A	84.1 ± 2.5a, A	84.2 ± 1.1a, A
	4 min	20.6 ± 4.6b, A	12.6 ± 1.1b, A	45.6 ± 3.9b, B
	8 min	12.2 ± 1.7c, A	11.7 ± 0.9b, A	40.7 ± 2.9b, B
Nanohybrid (Clearfil Majesty ES-2 Classic, Kuraray Noritake, Japan)	Initial	84.9 ± 3.2a, A	84.9 ± 1.6a, A	84.2 ± 1.2a, A
	4 min	35.3 ± 6.4d, A	26.6 ± 1.1c, A	46.9 ± 3.6b, B
	8 min	23.8 ± 3.8b, A	17.1 ± 2.1d, A	41.7 ± 2.6b, B
Supra-nano (Estelite Sigma Quick, Tokuyama Dental, Japan)	Initial	87.6 ± 2.1a, A	87.3 ± 3.3a, A	86.3 ± 2.3a, A
	4 min	54.1 ± 1.9e, A	51.5 ± 4.6e, A	56.5 ± 2.1c, B
	8 min	39.4 ± 3.7d, A	37.5 ± 4.7f, A	48.5 ± 2.8c, B

Statistically significant differences in the gloss (GU) values of the resin composites after toothbrushing are denoted by ^a–f, whereas differences according to toothbrush type are indicated by ^A–B (p < 0.05)

Discussion

The effect of electric toothbrush use on the surface roughness of resin composites was investigated in this study. The null hypothesis was rejected, as the surface roughness of the resin composites increased after 4 and 8 min of simulated electric toothbrushing.

The abrasiveness of toothpaste is measured by Relative Dentin Abrasivity (RDA). The abrasives contained in toothpaste are essential, as they help prevent tooth discoloration caused by extrinsic factors. However, the abrasivity of toothpaste must remain within a safe and tolerable range [24]. According to ISO 11,609, the upper limit for the dentin abrasivity of toothpaste is 250. Previous studies have reported that RDA values of ≤ 70 are classified as low abrasivity, those between 71 and 150 as medium abrasivity, and those above 150 as high abrasivity [25, 26]. The use of toothbrushes and toothpaste in combination is essential to achieve effective plaque removal [27]. In this study, electric toothbrushes were used with a conventional toothpaste (Colgate Total 12, RDA: 70).

Depending on their movement type and speed, electric toothbrushes can oscillate or vibrate. The bristles of vibrating toothbrushes move back and forth, aiding in plaque removal. The brush head of vibrating toothbrushes resembles that of a manual toothbrush [28]. It is important to actively move the vibrating brush, similar to a manual toothbrush. Rotary-oscillating toothbrushes, on the other hand, feature small, round brush heads that move in a circular motion to assist in plaque removal [28]. The brush head only needs to be moved from tooth to tooth for the rotating-oscillating mechanism to complete the cleaning [29]. In this study, sonic and micro-vibration electric toothbrushes, as well as a manual toothbrush, were used.

Electric toothbrushes are also classified according to their movement speed as conventional (normal) electric toothbrushes, sonic toothbrushes, and ultrasonic toothbrushes [29]. Sonic toothbrushes operate at a speed high enough to generate an audible humming sound. All electric toothbrushes with vibration frequencies above this limit are referred to as ultrasonic toothbrushes, while those with lower vibration speeds are classified as conventional electric toothbrushes [29]. Sonic and ultrasonic toothbrushes clean accessible tooth surfaces through mechanical polishing and also assist in the removal of surface stains and bacteria by combining fluid dynamics, shear forces, and the high-frequency vibration of their bristles [30].

The material composition of toothbrush bristles plays an important role in brushing effectiveness. Bristles can be manufactured from polyester compounds such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) [29]. These compounds are considered superior to nylon bristles because they are more durable, less water-absorbent, and generally less expensive. However, they tend to be relatively rigid, less flexible, and not as soft. To reduce overall production costs, polyester bristles are sometimes combined with nylon bristles.

To overcome the disadvantages of polyester bristles while maintaining their advantages, tapered-tipped polyester bristle designs have been developed [29]. The head plates of electric toothbrushes are typically produced through injection molding. Most bristles are made of nylon, a synthetic polyamide fiber [29]. Nylon is preferred in bristle manufacturing because it provides the desired balance of flexibility and softness, along with excellent resistance to chemicals, heat, and abrasion.

The length of toothbrush bristles varies according to their intended cleaning function. Longer bristles can reach deeper areas, whereas shorter bristles are generally more effective for cleaning the tooth surface. Within a single brush head plate, bristles may have equal or varying heights, allowing them to adapt to irregular tooth surfaces and access challenging regions such as interproximal spaces.

In addition to the differences in their target areas, bristles of different lengths also vary in stiffness. Shorter bristles tend to be stiffer than longer ones due to their reduced flexible base length [29].

The Sonicare W2 toothbrush used in this study has nylon bristles of medium hardness. The Oral-B iO ultimate clean toothbrush features bristles made of polyoxymethylene and polypropylene, arranged in a tuft-in-tuft configuration - shorter tufts are ideally positioned for surface cleaning, while longer tufts are designed for effective interdental cleaning in hard-to-reach areas [31]. However, the manufacturer provides no information regarding the bristle hardness of this model. The manual toothbrush used in this study has polypropylene bristles with soft hardness.

The inorganic fillers and organic monomers of resin composites influence their wear behavior [32, 33]. Filler size plays a critical role in this process; abrasion of composites with larger filler particles results in surface pores comparable to the original filler size, leading to higher surface roughness values [34]. In hybrid resin composites, this wear mechanism similarly produces surface pores approximately equal to the original filler size. In contrast, nanofilled and microfilled composites, in which all individual fillers are at the nanoscale, do not develop large voids or pits on the surface, resulting in superior polishability and polish retention [35]. Likewise, in nano-sized composites, smaller particle dimensions result in proportionally smaller pores after abrasion [34]. Furthermore, nanoclusters possess several advantages over micron-sized fillers, particularly in terms of finishing, polishing, and the preservation of surface smoothness after abrasion. During toothbrush abrasion, the agglomerated structure of nanoclusters tends to disintegrate rather than debond as a single large entity. Consequently, the nanoclusters wear at a rate similar to that of the surrounding nanoparticle-reinforced resin matrix, thereby maintaining a highly polished surface during abrasion. Moreover, nanoclusters may exhibit stronger filler–resin matrix bonding than micron-sized fillers due to their larger specific surface area [20].

Yu et al. [36] reported that surface roughness after simulated toothbrushing was material-dependent, with the nanofilled resin composites exhibiting the lowest Ra values, although the surface roughness of all groups increased significantly during the brushing process.

Similarly, Ferreira et al. [37] found that toothbrushing with toothpaste altered the surface topography of resin composite restorations and caused a significant increase in surface roughness across all specimens.

The results of the present study showed that both electric and manual toothbrushing increased the surface roughness values of resin composites; however, the supra-nano composite exhibited a smaller increase compared to the microhybrid and nanohybrid composites. The gradual loss of filler particles during brushing may account for this finding. The surface roughness of the material tends to increase with larger filler sizes, as greater filler removal occurs during abrasion [38].

Gloss is a parameter used to quantify the surface luster of a material and is based on specular reflection measured by a gloss meter at a specific angle and aperture size. In restorative dentistry, the objective is to achieve a gloss level comparable to that of the surrounding enamel. According to the literature, gloss values above 50 gloss units (GU) are considered clinically acceptable, while values around 80 GU are regarded as highly glossy by experienced clinicians [39].

Shimokawa et al. [40] reported that toothbrushing reduced gloss, increased surface roughness, and caused surface wear in all tested composites. Similarly, Yu et al. [36] revealed that gloss values decreased significantly after simulated toothbrush wear. Another study also demonstrated a statistically significant reduction in the gloss of resin composites when brushed with an electric toothbrush [41].

In the present study, the use of a new-generation electric toothbrush reduced the gloss of resin composites more than a manual toothbrush and resulted in gloss values falling below the clinically acceptable threshold of 50 GU.

Oscillating–rotating toothbrushes have been shown to be superior to manual and sonic toothbrushes in reducing dental plaque and gingivitis [42, 43]. The electric toothbrush types used in this study produced comparable surface roughness values on resin composites.

However, this study has certain limitations. The results may not fully reflect clinical conditions, as the study was conducted in vitro under simulated circumstances. Critical intraoral factors such as saliva, pH fluctuations, dietary habits, and occlusal stresses were not reproduced. Therefore, further clinical studies are required to more accurately determine the optimal combinations of resin composites and electric toothbrushes.

Conclusions

Within the limitations of this in vitro simulated study, electric toothbrushes increased the surface roughness and decreased the gloss of resin composites, with greater surface roughness observed for sonic and micro-vibration toothbrushes compared to manual toothbrushes; additionally, surface roughness was influenced by the particle size of the resin composite.

Authors’ contributions

M.B. and S.K.: Study design and drafting manuscript; M.B., K.A and N.A.: Conceived the ideas and data analysis; M.B., İ.K.Ç and N.A.: Data collection; M.B., F.O, B.E and S.K.: Performing statistical analysis; N.A. and M.B.: Concept and critical revision of the manuscript. All authors have read and approved the manuscript.

Funding

This research has not received any funding.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This article does not contain any studies with human participants or animals performed by any of the authors.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.