Effects of tooth-brushing force with a desensitising dentifrice on dentine tubule patency and surface roughness

doi:10.1016/j.jdent.2017.02.015

Journal of Dentistry

Volume 60, May 2017, Pages 50-55

https://doi.org/10.1016/j.jdent.2017.02.015 Get rights and content

Abstract

Objectives

To investigate the effects of a 5% NovaMin containing dentifrice on dentine tubule patency and surface roughness at 100 g and 400 g tooth brush abrasion forces.

Methods

75 polished human dentine samples were prepared and randomly allocated into one of five groups; control (1), Na₂PFO₃ 100 g abrasion force (2), NovaMin 100 g (3), Na₂PFO₃ 400 g (4) and NovaMin 400 g (5). The control group underwent two 2-min cycles of artificial saliva (AS), one 2-min erosion cycle; the rest underwent two toothbrush abrasion cycles in an AS/dentifrice slurry and one 2-min erosion cycle. All samples were imaged at baseline and post intervention using Tandem Scanning Microscopy and Profilometry to analyse tubule patency and roughness.

Results

Mean tubule patency increased significantly between baseline and post intervention in groups 1,2 and 4 and decreased significantly post intervention in groups 3 and 5 (p < 0.01). Post intervention, there were statistically significant differences in mean patent tubules between NovaMin and the Na₂PFO₃ and control groups (p < 0.001). Surface roughness increased for all groups between baseline and post interventions (P < 0.001); mean (SD) roughness increases for groups 1, 2, 3, 4 and 5 were 0.14 (0.05) μm, 0.18 (0.04) μm, 0.16 (0.06) μm, 0.19 (0.07) μm and 0.21 (0.02) μm respectively. Differences between group 1 and 5 were significant (p < 0.01).

Conclusions

Brushing with NovaMin resulted in significant dentine tubule occlusion at 100 g and 400 g, but brushing with Na₂PFO₃ resulted in increased tubule patency. Surface roughness increased significantly at 400 g brushing with NovaMin. There was no correlation between tubule patency and surface roughness.

Clinical significance

A NovaMin desensitising dentifrice resulted in tubule occlusion even at high brushing forces. There was minimal increase in surface roughness at the lower (100 g) brushing force.

Introduction

Dentine hypersensitivity is defined as a short duration, sharp dental pain response to stimuli in the absence of any other pathology [1], [2]. The generally accepted mechanism behind dentine hypersensitivity is the hydrodynamic theory [2], [3]. This involves the rapid transmission of fluid through dentinal tubules triggering neuroreceptors located in the pulp in response to stimuli such as cold and air [4]. The condition is very prevalent in Europe (42%) and especially the UK [5], [6]. Diet [7] as well as tooth-brushing [8], [9] are important aetiologies.

In order for the fluid flow in the hydrodynamic theory to be possible, the dentinal tubules must be patent (open). Studies have identified that teeth diagnosed with dentine hypersensitivity possess a greater number of patent tubules on the dentine surface [10], [11]. It is therefore not surprising that the number of patent tubules on the dentine are used to assess the efficacy of desensitising (tubule occluding) products [12]. Olley et al. developed a robust reproducible method to quantify patent tubules in dentine samples. Dentine samples were scanned using Tandem Scanning Microscopy (TSM) and the images analysed using a software program to quantify the number of patent dentinal tubules [13]. This method was used in a further study investigating the effects of three toothbrush abrasion forces on tubule patency using a standard Na₂PFO₃ toothpaste [9]. This study reported an association between increased tubule patency and increased abrasion after one erosion-abrasion cycle, with significant differences at the 100 g and 400 g abrasion forces [9]. However, the effects of a densensitising (tubule occluding) dentifrice at these brushing forces (100 g and 400 g) and whether the higher brushing force could increase tubule patency despite the dentifrice are unknown. This study investigates if there is a protective effect (reduced tubule patency) of a desensitising dentifrice (5% NovaMin, GlaxoSmithKline Consumer Healthcare, Brentford, UK) at both 100 g and 400 g toothbrush abrasion forces in an erosion/abrasion regime. NovaMin is a bioactive glass with calcium sodium phosphosilicate as the active ingredient. It is reputed that this can react in the oral environment to form a hydroxy-carbonate apatite (HCA) over time and is similar to the natural tooth mineral composition [14], [15], [16]. It has been previously shown when comparing two NovaMin containing dentifrices, control and water, that the NovaMin results in dentine tubule occlusion [13].

It should not be supposed from this study that the effect of a desensitising dentifrice might offset the detrimental effect to dentine at higher brushing forces and therefore enable this to occur. The 400 g brushing force is represented as an overzealous regime to investigate the effects on the dentine surface.

In addition, the measurement of surface topography is widely used within dental material science, with rapidly evolving developments [17]. Surface roughness measurements are often used to identify changes in tooth structure following erosive wear and to investigate the efficacy of anti-erosion and remineralising products [18], [19], [20], [21]. Furthermore, tribology studies use roughness parameters to make associations between wear patterns and diet [22], [23]. To the authors’ knowledge a correlation between surface roughness and tubule patency has not been investigated. It can be supposed that a change in the tubule patency of dentine, could effect the surface roughness of dentine due to the surface nature of dentine hypersensitivity [24]. Therefore surface roughness may prove a useful indicator of tubule patency.

The overall aim of this study was to investigate the effects of a 5% NovaMin containing dentifrice on dentine tubule patency and surface roughness at two abrasion forces (100 g and 400 g). The null hypothesis was that there would be no difference in tubule patency and surface roughness brushing with a NovaMin containing dentifrice at 100 g and 400 g tooth-brushing forces. Also, that tubule patency is not associated with surface roughness.

Section snippets

Sample preparation

Unrestored and caries free human molars were collected under ethical agreement (12/LO/1836) and sterilised in sodium hypochlorite for a minimum of 72 h. The roots were removed and the crowns sectioned using a circular diamond saw (XL 12205, Benetec Ltd., London, UK) to produce 75 sections, no samples were discounted during the study. The sections were embedded in bisacryl composite (Protemp4 3 M ESPE, Germany) using custom made trays to make samples. Sample size calculations were based on Sehmi

TSM

The mean patent tubules at baseline and post intervention for all groups are shown in Table 1. Between baseline and post intervention, there were statistically significant increases in dentine tubule patency in the control and Na₂PFO₃ groups whereas there were significant decreases in tubule patency for the NovaMin groups. For group 1, control, the mean (SD) number of dentine tubules at baseline was 188 (60) which statistically significantly increased to 245 (49) post erosion (p < 0.01). For

Discussion

This study showed that a 5% NovaMin desensitising dentifrice significantly decreased tubule patency post acid challenge at both 100 g and 400 g abrasion forces. There was a significant difference in roughness change with the 5% NovaMin at 400 g compared to control, but no significant difference in roughness change using the 5% NovaMin at 100 g or the Na₂PFO₃ dentifrice at 100 g and 400 g. However, there were no statistically significant direct associations between DH and surface roughness. Thus the

Conclusion

Brushing with 5% NovaMin containing dentifrice resulted in significant dentine tubule occlusion at both 100 g and 400 g abrasion forces. Surface roughness only increased significantly at 400 g toothbrush abrasion force with NovaMin; there was minimal increase in surface roughness at 100 g brushing. There was no correlation between tubule patency and surface roughness.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of interest

None.

Declaration of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

References (40)

P. Charoenlarp et al.
Pain and the rate of dentinal fluid flow produced by hydrostatic pressure stimulation of exposed dentine in man
Arch. Oral Biol.
(2007)
N.X. West et al.
Prevalence of dentine hypersensitivity and study of associated factors: a European population-based cross-sectional study
J. Dent.
(2013)
R.C. Olley et al.
The relationship between incisal/occlusal wear, dentine hypersensitivity and time after the last acid exposure in vivo
J. Dent.
(2015)
H. Sehmi et al.
The effect of toothbrush abrasion force on dentine hypersensitivity in-vitro
J. Dent.
(2015)
L.H. Gracia et al.
An in vitro evaluation of a novel high fluoride daily mouthrinse using a combination of microindentation, 3D profilometry and DSIMS
J. Dent.
(2010)
S.L. Zhou et al.
In vitro study of the effects of fluoride-releasing dental materials on remineralization in an enamel erosion model
J. Dent.
(2012)
E.S. Gadelmawla et al.
Roughness parameters
J. Mater. Process. Technol.
(2002)
M. Sedlaček et al.
Correlation between standard roughness parameters skewness and kurtosis and tribological behaviour of contact surfaces
Tribol. Int.
(2012)
R.C. Olley et al.
An in situ study investigating dentine tubule occlusion of dentifrices following acid challenge
J. Dent.
(2012)
M. Addy et al.
Can tooth brushing damage your health? Effects on oral and dental tissues
Int. Dent. J.
(2003)

Z. Wang et al.

Effect of desensitising toothpastes on dentinal tubule occlusion: a dentine permeability measurement and SEM in vitro study

J. Dent.

(2010)

J. Field et al.

Quantifying and qualifying surface changes on dental hard tissues in vitro

J. Dent.

(2010)

R.H. Dababneh et al.

Dentine hypersensitivity—an enigma? A review of terminology, mechanisms, aetiology and management

Br. Dent. J.

(1999)

P. Dowell et al.

Dentine hypersensitivity—a review. Aetiology, symptoms and theories of pain production

J. Clin. Periodontol.

(1983)

M. Brännström et al.

The hydrodynamics of the dental tubule and of pulp fluid

Caries Res.

(1967)

R.C. Olley et al.

Validation of the basic erosive wear examination

Caries Res.

(2014)

R.C. Olley et al.

Validation of a cumulative hypersensitivity index (CHI) for dentine hypersensitivity severity

J. Clin. Periodontol.

(2013)

E.G. Absi et al.

Dentine hypersensitivity. A study of the patency of dentinal tubules in sensitive and non-sensitive cervical dentine

J. Clin. Periodontol.

(1987)

E.G. Absi et al.

Dentine hypersensitivity. The development and evaluation of a replica technique to study sensitive and non-sensitive cervical dentine

J. Clin. Periodontol.

(1989)

K. Markowitz et al.

Discovering new treatments for sensitive teeth: the long path from biology to therapy

J. Oral Rehabil.

(2008)

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Comparison of meteorology created by profilometry and digital microscopy on polished dentine in an erosion/abrasion model
2021, Journal of Dentistry
Digital microscopy offers the ability to scan surfaces to produce 3D reconstructions, allowing step height measurements with high accuracy. The aims of this study were to compare the step heights from the gold standard, non-contact profilometry, to digital microscopy in an erosion/abrasion model.
Dentine specimens (n = 60) were immersed in deionised water, 1450 ppm and 5000 ppm fluoride as sodium fluoride for 3 min, eroded for a total of 25 min in a cycled protocol in 0.3% citric acid (pH 2.7) and abraded with 120 and 240 brushing strokes. Samples were scanned by a non-contacting profilometer with a 0.1 μm vertical resolution and then the same samples imaged with a digital microscope and the step heights compared. Data were analysed in GraphPad Prism 7.00. Data were normally distributed and a 3 way ANOVA with post hoc analysis used to assess for differences between groups. Agreement between the measurement method was assessed using IntraClass Correlations and Bland Altmans plots.
The mean step heights from the profilometry and the digital microscope on the same samples were not statistically significant different. The magnitude of the differences was less than 0.5 μm. The results of the ANOVA demonstrated that the individual factors fluoride concentration and number of strokes were significant (P<0.05), however, the method of analysis was not (p = 0.74). ICC's between the two methods of analysis were excellent (0.996, p<0.001) with no proportional bias.
This study reports that step height on dentine from a digital microscopy and non-contact profilometry were not significantly different. The digital microscope, although slower, allows visual inspection of the samples as well as measurement.
Digital microscope's offer the ability to scan, 2D or 3D images and perform meteorological analysis of samples. In this investigation both showed that 5000 ppm fluoride prevents erosive tooth wear in vitro.
The ability of a potassium oxalate gel strip to occlude human dentine tubules; a Novel in vitro: In situ Study
2020, Journal of Dentistry
To determine if an oxalate strip reduced fluid flow in dentine samples and whether this reduction was maintained following a 14 day intra-oral period.
Dentine tubule fluid flow was measured by a modified Pashley cell in 40 acid-etched dentine discs 1 mm thick, diameter >10 mm, with an acquired pellicle, pre-equilibrated with Hartmann’s solution and conditioned by toothbrushing, pre and post treatment (10 min) with an oxalate (3.14 %) gel strip or no treatment. One control and one test sample were exposed in-situ for 14 days to the oral environment in 20 healthy adult volunteers, and fluid flow re-measured. The appliance containing the two samples was removed for brushing with water after mealtimes when the participant brushed their teeth and for a 2 min daily soak in chlorhexidine.
Fluid flow rate was reduced significantly immediately following treatment with the oxalate strip compared to baseline flow rate by 58 %. Following 14 days in-situ oral environment phase, a significant further reduction in fluid flow compared to baseline was identified in both control and oxalate strip treated samples, both (p < 0.0001), but the reduction was greater in the test samples, 94 % vs 87 %, p < 0.01.
This novel investigation is the first to show fluid flow measurement using the Pashley model in dentine samples that have been housed in the mouth for 14 days. Treatment with an oxalate strip designed for dentine hypersensitivity alleviation reduced dentine fluid flow more than control providing evidence that the oxalate treatment withstood the oral environment over a prolonged time.
This study demonstrated the efficacy and durability of the oxalate precipitate over a 14 day period in achieving and maintaining dentine tubule occlusion when participants had no dietary restrictions. This demonstrates the suitability of the oxalate strip for the treatment of patients suffering from dentine hypersensitivity pain.
Effect of silver-containing agents on the ultra-structural morphology of dentinal collagen
2020, Dental Materials
This study investigated the effect of silver diammine fluoride (SDF), nano-silver (AgNPs) and nano-silver/potassium fluoride (AgNPs/KF) on the morphology of dentin collagen and color staining on the dentin. Also, we investigated the anti-caries properties in terms of anti-bacterial effects and potentiality of dentin remineralization at collagen level.
Dentin specimens obtained from bovine tooth roots were finished with #2000 SiC and sonicated for 5 min. Specimens were divided into two main groups: sound and demineralized dentin. Each group was subdivided into five subgroups according to treatment solution: control (no treatment), SDF, nano-silver (AgNPs), AgNPs/KF and KF. Specimens were analyzed using transmission electron microscope (TEM), spectrophotometer, scanning electron microscope (SEM) and antibacterial test. Repeated Measures ANOVA was used for statistical analysis of color change while one-way ANOVA was used for CFU analysis.
Regarding color change, SDF showed the highest values while the other groups exhibited insignificant changes. SDF showed alteration in the collagen fibrils while the other groups showed normal intact fibrils. Regarding antibacterial activity, SDF and AgNPs/KF showed the greatest antibacterial effect.
SDF altered the dentin collagen morphology and inferior ethetics, but still providing intrafibrillar remineralization. Nano-silver fluoride preparations (AgNPs/KF) can be an alternative material for SDF as it can preserve the dentin collagen, showing no color change overtime, and provide a high anti-caries property including intrafibrillar remineralization with a significant anti-bacterial effect.
Measurement of eroded dentine tubule patency and roughness following novel dab-on or brushing abrasion
2020, Journal of Dentistry
Citation Excerpt :
Furthermore, other measures of surface roughness have shown purpose in differentiating the nature of tooth wear patterns [19]. However, previous work using Non-Contacting Laser Confocal Profilometry found no correlation between surface roughness and the degree of tubule patency within a worn dentine lesion [10]. This may be due to the nature of non-contacting measurements.
To investigate the effect of dab-on or brushing of stannous-fluoride SnF2 or sodium-fluoride NaF dentifrice on eroded dentine tubule patency, surface and inter-tubular dentine roughness, using Confocal-Laser-Scanning-Microscopy (CLSM), Atomic-Force-Microscopy (AFM), Energy-Dispersive-X-ray-Spectroscopy (EDX), Scanning-Electron-Microscopy (SEM) and Contact-Profilometry (CP).
75-polished human dentine samples were prepared and eroded in agitated 6% citric acid to expose patent tubules and ‘initiate’ DH. Samples were randomly allocated into 5 intervention groups; artificial saliva control (1); electric tooth-brushing with NaF (2) or SnF2 (3), and dab-on application of NaF (4) or SnF2 (5). Samples underwent three cycles of intervention followed by further acid challenge. Patent tubules, likely to cause DH clinically, were measured using validated biocomputational methods with CLSM images of dentine surfaces taken baseline and post-intervention. Randomised samples (n = 15, 20 %) were investigated using AFM, EDX and SEM to study surface and sub-surface tubular occlusion. Dentine surface and inter-tubular roughness were measured using CP and AFM respectively.
At baseline, mean tubule patency in all samples was 216 (SD 58) with no significant inter-group differences. Post-intervention, the mean patency was 220 (40) and 208 (35) in groups 1 and 2 respectively (p ≥ 0.06), but decreased to 62 (41), 62 (21) and 63 (19) in groups 3, 4 and 5 respectively (p < 0.0001). Patency was confirmed using AFM, SEM and EDX. SnF2 interventions created greater sub-surface occlusion (p < 0.01), and increased CP surface roughness (p = 0.015). Significant negative correlation (-0.6) existed between CP surface roughness and tubule patency (p = 0.009).
Dab-on with NaF and SnF2 or brushing with SnF2 reduces DH in eroded dentine with ongoing acid challenges. Contacting surface roughness measures indicate risk of DH.
Dab-on is a convenient supplementary method of dentifrice application to reduce DH; it beneficially avoids brushing post-erosion or overzealous brushing, enables re-establishment of an appropriate brushing regime post-DH and supports oral health. Significant modes of action of SnF2 in reducing DH are revealed. Finally, CP roughness measures provide indication of dentine lesions that may cause DH clinically.
Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion
2020, Heliyon
Citation Excerpt :
The authors would add that it is sensible to avoid over-zealous brushing and to not brush immediately following acidic consumption to enable remineralisation. In another previous study, a significant increase in surface roughness was observed following a 400 g (but not lower 100 g) brushing force on eroded dentine using a Novamin dentifrice, compared to the control (eroded only) dentine group [20]. That previous study also showed that a similar effect on surface roughness did not occur following brushing with a sodium fluoride control dentifrice [20].
To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Profilometry (CP) measures investigating brushing or dab-on of stannous-fluoride dentifrice on early aggressive dentine erosion.
75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; artificial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-fluoride NaF (2) or stannous-fluoride SnF₂ (3), and dab-on application of NaF (4) or SnF₂ (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and profiled using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples.
Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p = 0.01). There were no significant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF₂ brushing (3) increased micro-hardness more than control (1) (p = 0.03), NaF (4) and SnF₂ dab-on (5) (p ≤ 0.001), and increased surface roughness more than control (p = 0.02), NaF brushing (2) and NaF dab-on (4) (p ≤ 0.017). Dab-on of SnF₂ (5) produced rougher surfaces than control (1) (p = 0.014) and reduced hardness compared with NaF brushing (p = 0.04).
Good agreement and correlation exists between CLSM and CP measures in dentine. There were no significant differences in surface loss after interventions between groups. Compared with control, SnF₂ application increased dentine surface roughness and SnF₂ controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine.
Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-fluoride brushing, and dab-on application offer no benefits following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.
Influence of desensitizing and anti-erosive toothpastes on dentine permeability: An in vitro study
2019, Journal of Dentistry
Citation Excerpt :
We supposed that these toothpastes could have an additional effect on dentine permeability. Although the literature shows a range of studies testing the effect of toothpastes on dentine permeability and tubule occlusion in vitro [16–20], none of them tested the effect of anti-erosive toothpastes. Furthermore, there is a lack of studies analyzing the effect of the toothpastes on reducing dentine permeability when they are applied regularly, during an abrasion challenge and between several erosive challenges.
This study analyzed the effect of desensitizing and/or anti-erosive toothpastes on dentine permeability.
One-mm dentin discs were prepared from human molars and exposed to EDTA solution (5 min, 17%). Initial dentine permeability was measured, under constant pressure. Specimens were randomly allocated into 10 groups: four anti-erosive toothpastes (calcium silicate + sodium phosphate, potassium nitrate, stannous chloride + chitosan, oligopeptide-104); four desensitizing toothpastes (arginine + calcium carbonate, calcium sodium phosphosilicate, strontium acetate, stannous fluoride); and two controls (regular fluoridated toothpaste, and human saliva). They were submitted to a 5-day erosion-abrasion cycling model. Erosion consisted of immersion in citric acid (2 min, 0.3%, natural pH ˜ 2.6, 4x/day), followed by 1 h exposure to human saliva. Specimens were brushed for 15 s (2 N, 45 strokes) with the toothpaste slurries (total exposure time of 2 min). After 5 cycles, the final dentine permeability was determined. Dentine permeability change was calculated as a percentage of the initial hydraulic conductance (%Lp). Data were analyzed with one-way ANOVA and Tukey tests ( $α = 0.05$ ).
The toothpastes calcium silicate + sodium phosphate and potassium nitrate, showed significant decrease in %Lp, with no difference between them. The regular fluoridated toothpaste also decreased the %Lp, not differing from potassium nitrate. No desensitizing toothpaste showed change in %Lp. Human saliva, oligopeptide-104 and stannous chloride + chitosan presented significant increase in %Lp, without difference between them.
Calcium silicate + sodium phosphate, potassium nitrate, and the regular fluoridated toothpaste decreased dentine permeability, whereas the desensitizing toothpastes tested did not.
Toothpastes had distinct impacts on dentine permeability, which may reflect a variable effect on the treatment of dentine hypersensitivity. Within the limitations of a laboratory-based study, toothpastes with an anti-erosive claim could also be effective in reducing the pain in dentine hypersensitivity.

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Effects of tooth-brushing force with a desensitising dentifrice on dentine tubule patency and surface roughness

Abstract

Objectives

Methods

Results

Conclusions

Clinical significance

Introduction

Section snippets

Sample preparation

TSM

Discussion

Conclusion

Conflicts of interest

Declaration of funding

Arch. Oral Biol.

J. Dent.

J. Dent.

J. Dent.

J. Dent.

J. Dent.

J. Mater. Process. Technol.

Tribol. Int.

J. Dent.

Int. Dent. J.

J. Dent.

J. Dent.

Dentine hypersensitivity—an enigma? A review of terminology, mechanisms, aetiology and management

Br. Dent. J.

Dentine hypersensitivity—a review. Aetiology, symptoms and theories of pain production

J. Clin. Periodontol.

The hydrodynamics of the dental tubule and of pulp fluid

Caries Res.

Validation of the basic erosive wear examination

Caries Res.

Validation of a cumulative hypersensitivity index (CHI) for dentine hypersensitivity severity

J. Clin. Periodontol.

Dentine hypersensitivity. A study of the patency of dentinal tubules in sensitive and non-sensitive cervical dentine

J. Clin. Periodontol.

Dentine hypersensitivity. The development and evaluation of a replica technique to study sensitive and non-sensitive cervical dentine

J. Clin. Periodontol.

Discovering new treatments for sensitive teeth: the long path from biology to therapy

J. Oral Rehabil.