J Conserv Dent 2021;24:36-40

1. Comparative evaluation of effect of
toothbrush-dentifrice abrasion on surface
roughness of resin composites with
different filler loading:” An in vitro study
Presented by
Dr Nadeem Aashiq
MDS 2nd year
Batch 2020
J Conserv Dent 2021;24:36-40.

2. Introduction
• The rising demands for esthetics united with marvellous
improvement in adhesive dentistry have resulted in a
progressively more extensive use of resin composite as restorative
materials.
• Restorative resin composites used for restoring all cavities in
anterior and posterior teeth require smooth surface finish which is
clinically important for long-lasting restoration in the oral cavity.
• Surface quality of dental restorations is a vital factor in
determining the success of the restorations.

3. • The surface roughness of restorative resin composite is
mainly dependent by the size, hardness, and quantity of filler
particles, which in turn affects the mechanical properties of
the material.
• Surface roughness is one of the contributing factors for
external discoloration of the composite restoration.
• The smooth surface of the restoration provides better
esthetics and little debris accumulation.
• A rougher surface can lead to decreased gloss and
discoloration of the material surface which further affects the
physical and mechanical properties of restorative material.

4. • Smooth surface adds to the patient’s comfort as already the
difference in surface roughness of 0.3 µm can be detected by the
tip of the patient’s tongue.
• Increasing surface roughness is correlated with amplified
accumulation of plaque. The mean roughness of 0.2 µm is the
crucial threshold assessment for bacterial retention.
• Abrasiveness of the dentifrice can cause changes in the external
roughness of some restorative resin composite and may
consequently affect the long-term esthetic steadiness of the
restorations.
• Abrasivity measurements are obtained by Relative Dentin
Abrasitivity (RDA). Different formulas of dentifrices present
different RDA values. The RDA values may vary from 40 to
200,Less than 250 being the American dental association
suggested limit.

5. AIM OF THE STUDY
• The aim of this in vitro study was to evaluate the effect of
toothbrush-dentifrice abrasion on surface roughness of
resin composites with different filler particles.

6. MATERIALS AND METHOD
Two posterior composites were used in this study, their
composition is depicted in Table 1. The simulated brushing of
the specimen was done using Colgate Total Plus Whitening
Dentifrice [Table 2].

8. Preparation of samples
• Specimen size was standardized by preparing them in customized
cylindrical plastic molds (5 mm diameter × 2 mm depth). Materials were
manipulated according to the manufacturer’s recommendations.
• The mold with specimen material covered with a Mylar strip on both sides
was placed over the glass slab then pressed between two glass slides to
remove excess flash.
• The glass slides were pressed steadily during the set to avoid the
occurrence of air bubbles and to get a smooth surface.
• Specimens were primed at room temperature (23.5°C ± 2°C). The
materials were polymerized by a light-emission diode light-curing unit
VALO Ultradent using 40 s exposure to each specimen’s top and bottom
surface.
• The space between the light source and specimen was standardized by
placing the curing light openly over the specimen.

9. • The light intensity of the curing light was checked regularly
with the radiometer during specimen preparation which
was constant at 700 mw/cm2.
• The top surfaces of all the specimens were then sequentially
polished with coarse followed by medium, fine, and
super-fine Shofu Super-Snap polishing discs (San Marcos,
USA) with slow speed hand piece under dry conditions.
Simulated tooth brushing
• Mechanical brushing was carried with cross-action power
(P&G’s oral B Ohio, USA) soft toothbrush of samples using
Colgate Total Plus Whitening Toothpaste (USA).

10. Testing of the samples
• The specimens were cleaned after polishing and the
specimen topography was evaluated by Veeco di CP-II
Atomic Force Microscope (AFM) at six different points:
two points at the center, two points at the periphery, and
two points at mid-distance from the periphery to the
center.
• Similarly, these specimens were again subjected to
evaluation after simulated toothbrushing using
dentifrice. In the AFM images, surface roughness
analysis was done using software provided, and the
following parameters were compared among specimens:
average roughness (Ra) and maximum peak-to-valley
distance (Rp-v) [Figures 1 and 2].

11. Figure 1: Atomic force microscope images of Z250 XT before
brushing (a and c) and after brushing (b and d)

12. Figure 2: Atomic force microscope image of Z350 XT before
brushing (a and c) and after brushing (b and d)

13. RESULTS
• The mean (standard deviation [SD]) changes in Ra were compared
in the two groups using independent Student’s “t”-test. For Z350,
the mean changes in Ra were less as compared to Z250, and this
difference was statistically significant.
• Hence, toothbrushing on restorative resin composite Z350 results in
significantly less change in Ra as compared to toothbrushing done
on Z250 [Tables 3 and 4]. The mean (SD) changes in Rp-v were
compared in the two groups using independent Student’s “t”-test.
For Z350, the mean change in Rp-v was less as compared to Z250,
and this difference was statistically significant. Hence,
toothbrushing on composite Z350 results in significantly less change
in roughness as compared to toothbrushing done on Z250 [Tables 5
and 6].

16. DISCUSSION
• Restorative materials used for restoration in teeth are exposed to
various factors affecting their quality in the oral cavity. Among all the
other factors, the most significant role is played by oral hygiene. The
prophylactic home procedures produce effects like surface roughness,
thus enhancing the bacterial growth and staining.
• In this present study, Filtek z350 showed better resistance to abrasivity
of toothpaste. Filtek Z250 showed more surface roughness and
discoloration.
• Mechanical brushing is suitable for simulating normal oral hygiene
procedures to standardize brushing application, distance, and
frequency of force on the specimens.
• While in an estimate, a person brushes their teeth for 2 min, twice a
day, each tooth experiences only a fraction of seconds. As an
approximation, each tooth may be brushed for 8 s/day that is
equivalent to each individual tooth for 4 s twice a day.

17. • In the present study, the composite samples were brushed for 720 s
equivalent to the revelation of restorative resin composite to the
prophylactic home measures for a period of 3 months.
• The relative dentin abrasivity (RDA) of the toothpaste is an additional
variable that persuades the surface roughness of the materials.
• McCabe JF et al. showed that the RDA of the toothpaste is the reason
for both the surface roughness and wear of dental materials.
• In the current study, dentifrice used had a RDA value of 180, thus
explaining the roughness formed in composites.
• According to Amaral et al., whitening dentifrices, such as the RDA 180,
contain explicit chemical mechanisms in their formulation, which
reduce staining irrespective of the corporal possessions on the material.

18. • According to Joiner et al.,whitening dentifrices were planned to optimize
cleaning and to diminish wear.
• Recent restorative resin composite differs much in filler concepts and filler
loading in addition to in matrix monomer composition.
• The resin matrix of Z250 have Bis GMA-Bisphenol A- glycidyl methacrylate,
UDMA- urethane dimethacrylate, Bis EMA and the resin matrix of Z350 has
Bis-EMA-ethoxylated bis phenol-A- Glycol dimethacrylate, UDMA and in
addition TEGDMA-tetraethylene glycol dimethacrylate,PEGDMA
Polyethylene glycol dimethacrylate to adjust viscosity in its resin matrix.
• The Z250 is a nanohybrid posterior composite with surface-modified
zirconia/silica with a median particle size of approximately ≤3 µ,
nonagglomerated 20 nm surface-modified silica.
• Z350 is a nanofilled posterior composite with a combination of non
agglomerated 20 nm silica filler, nonagglomerated 4 to 11 nm zirconia filler,
and aggregated zirconia/silica cluster filler (comprised 20 nm silica and 4 to
11 nm zirconia particles).

19. • Both filler grain volume and distribution and polymerization excellence of
the resins are presumably of major importance for the resistance to tooth
brushing of restorative resin composite. Therefore, it is important to
illustrate the restorative resin composite characteristics along with tooth
brushing effects to estimate possible relationships.
• The color change in Z250 specimens after brushing was due to matrix wear
when there was outward removal of filler particles, which was a physical
action rather than a chemical reaction.
• According to Hu et al. subjects are vulnerable to shear forces on the worn
surfaces. Due to the advanced modulus of elasticity of the particles in
comparison with the resin matrix, particles are able to bear outsized loads.
• However, the bond of particles to the matrix in Z250 is not as strong as the
stress produced by the filler particle rigidity, resulting in particle
disintegration or disarticulation and material loss. Therefore, the
restorative resin composite behavior was dissimilar during the replicated
procedures.

20. • Suzuki et al evaluated nano composite and nano hybrid resin for
surface roughness by simulated tooth brushing over 50,000 cycles
and concluded that there was significant differentiation in rates of
coarseness of composite resins The nano composites showed lower Ra
than nanohybrid restorative resin composite, which is similar to our
study where Z250 shows more wear, less color stability than Z350.
• These nanofilled composites also acquire differences in their organic
formulations, which may lead to dissimilar mechanical performance.
• The reduction in size and broad allocation of the nano fillers may
amplify filler load, as a result, progress the mechanical properties of
these novel materials, such as their polymerization shrinkage, tensile
strength, compressive strength, resistance to fracture, and reduced
wear.

21. • According to the manufacturer, the restorative resin composite Z350 XT
is nanofilled contrary to Z250 which is nanohybrid. Z350 XT consists of
an amalgamation of zirconia and silica nanoparticles in nano cluster
plummeting the interstitial space sandwiched between the particles and
increasing the quantity of load.
• The nano particles result in greater wear resistance and improved
physical properties, which means that during the abrasion, these nano
clusters wear at a speed analogous to the immediate resin matrix.The
result is a smooth, glossy, and durable polished surface.
• Garcia et al. in their study concluded that the grounds for less abrasion
of Z350 is because of homogeneous distribution of precured silica
particles in the organic matrix. In our study, Z350 exhibited the least
roughness. This study also showed similar results when Filtek Z350 was
compared to Filtek Z25017.

22. • The Ra parameter and Rp-v was used in this study. Ra is a true
amplitude measurement. Ra is the commonly employed parameter for
roughness measurement of a flat surface.
• AFM has become an important tool for imaging surfaces and analysis.
AFM allows a three-dimension imaging at nanometric resolution and is
budding as consistent in evaluation of surface roughness features of
composites.
• AFM can measure quantitative surface roughness with extremely high
resolution (horizontal resolution of 0.2–1.0nm and vertical resolution of
0.02 nm); the Ra value of a specimen was defined as the arithmetic
average height of roughness component irregularities from the mean
line measured within the sampling length;however, the only limitation
in using AFM is surface roughness measurement using AFM which is
restricted due to small scanning area.

23. CONCLUSIONS
• All restorative resin composites exhibit roughness after simulated
tooth brushing, the filler technology in restorative resin composite may
show variable results before and after simulated tooth brushing. The
surface roughness of the restorative resin composite increased over a
period of time when subjected to toothbrush-dentifrice abrasion and
varied depending on the filler particle. Thus, it is concluded that Z350
has better wear resistance and smoother surface even after being
subjected to tooth brushing as observed under AFM.

24. References
• Effects of Toothbrush Hardness on in vitro Wear and
Roughness of Composite Resins Kyoizumi H, Yamada J, Suzuki T, Kanehira M,
Finger WJ, Sasaki K. J Contemp Dent Pract 2013;14(6):1137-1144.
• 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).

25. • 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.

26. • Surface Roughness of Composite Resins after Simulated
Tooth brushing with Different Dentifrices Monteiro B, Spohr AM. J Int
Oral Health 2015;7(7):1-5.
• AIM: The aim of the study was to evaluate, invitro, the surface
roughness of two composite resins submitted to simulated
toothbrushing with three different dentifrices.
• Materials and Methods: Totally, 36 samples of Z350XT and 36
samples of Empress Direct were built and randomly divided into three
groups (n = 12) according to the dentifrice used (Oral-B Pro-Health
Whitening [OBW], Colgate Sensitive Pro-Relief [CS], Colgate Total
Clean Mint 12 [CT12]). The samples were submitted to 5,000, 10,000
or 20,000 cycles of simulated toothbrushing. After each simulated
period, the surface roughness of the samples was measured using a
roughness tester.

27. • Results: According to three-way analysis of variance, dentifrice (P =
0.044) and brushing time (P = 0.000) were significant. The composite
resin was not significant (P = 0.381) and the interaction among the
factors was not significant (P > 0.05). The mean values of the surface
roughness (μm) followed by the same letter represent no statistical
difference by Tukey’s post-hoc test (P <0.05): Dentifrice: CT12 =
0.269a; CS Pro- Relief = 0.300ab; OBW = 0.390b. Brushing time:
Baseline = 0,046ª; 5,000 cycles = 0.297b; 10,000 cycles = 0.354b;
20,000 cycles = 0.584
• Conclusion: Z350 XT and Empress Direct presented similar surface
roughness after all cycles of simulated tooth brushing. The higher the
brushing time, the higher the surface roughness of composite resins.
The dentifrice OBW caused a higher surface roughness in both
composite resins.

28. THANK YOU