Effect of different brushing parameters on erosive tooth wear in primary bovine enamel and dentin.

This in-vitro study aimed to analyse the effect of brushing and different brushing parameters (kind of toothpaste, kind of toothbrush, brushing force) on erosive tooth wear of primary bovine enamel and dentin. Specimens were prepared from primary bovine enamel or dentin (each group n = 12) and cyclically eroded (6 × 60 s/d, citric acid, pH 2.4) and brushed with children's toothbrushes (2 × 15 s/d) over 5 days. The brushing parameters under investigation were: toothpaste (fluoridated, fluoride-free), toothbrush (manual; rotating-oscillating and sonic, each at two different activation modes) and brushing force (1 N, 2 N). Specimens that were only eroded and not brushed served as controls. Enamel and dentin wear was quantified using widefield confocal microscopy. Statistical analysis was performed using three- and one-way ANOVAs followed by Scheffe's (enamel) or Tamhane's (dentin) post-hoc tests (p < 0.05). Brushing with the fluoridated toothpaste was able to significantly reduce erosive wear in enamel (by 15 to 37%, 6 of 10 groups) and in dentin (by 58 to 72%, all groups), while brushing with the fluoride-free toothpaste was not different from the controls. Considering the kind of toothpaste and brushing force, slight differences between the toothbrushes were observed in enamel, but not in dentin. Within the same toothbrush and activation mode, almost no differences between 1 and 2 N brushing force were detected. In conclusion, erosive tooth wear on primary bovine dental hard tissue mainly depends on the kind of toothpaste, rather than on the kind of toothbrush and the brushing force.

Impact of toothbrush head configuration and dentifrice abrasivity on non-carious cervical lesions in-vitro.

OBJECTIVE: To investigate the effect of toothbrush head configuration and dentifrice slurry abrasivity on the development of simulated non-carious cervical lesions (NCCLs) in vitro. METHODS: Extracted premolars were randomly allocated into 15 groups (n = 16) generated by the association between toothbrush head configuration (flat-trimmed, rippled, cross-angled/multilevel/rubbers added, cross-angled/multilevel/flex head, feathered) and dentifrice slurry abrasivity (low/medium/high). Teeth were mounted on acrylic blocks and had their roots partially covered with acrylic resin, leaving 2-mm root surfaces exposed. Toothbrushing was performed for 35,000 and 65,000 double-strokes. Specimens were analyzed using non-contact profilometry for dental volume loss (mm3) and lesion morphology. Data was analyzed using ANOVA with pairwise comparisons and Kruskal-Wallis tests. RESULTS: The two-way interaction between toothbrush head configuration and slurry abrasivity was significant (p = 0.02). At 35,000 strokes, the flat-trimmed and cross-angled/multilevel/rubbers added toothbrushes caused the highest loss, when associated to the high-abrasive slurry (p<0.05); whereas cross-angled/multilevel/flex head showed the least loss, when associated to the low-abrasive (p<0.05). At 65,000, more dental loss was observed for all toothbrushes when associated to the high-abrasive slurry, with flat-trimmed causing the highest loss (p < 0.05). Lower dental loss rates were observed for cross-angled/multilevel/flex head associated to the low-abrasive slurry when compared to the other toothbrushes (p < 0.05), except to feathered (p = 0.14) and rippled (p = 0.08). Flat lesions (mean internal angle ± standard-deviation: 146.2°± 16.8) were mainly associated with low-abrasive slurry, while wedge-shaped lesions (85.8°± 18.8) were more frequent with medium- and high-abrasive slurries. CONCLUSION: The development, progression and morphology of simulated NCCLs were modulated by both toothbrush head configuration and dentifrice abrasivity. CLINICAL SIGNIFICANCE: Dental professionals should consider both the type of toothbrush and dentifrice abrasivity in the management plan of patients at risk of developing NCCLs.

The effect of location/site on polished human enamel after mechanical and chemical wear.

OBJECTIVE: To compare profilometry and microhardness of polished occlusal and buccal human enamel following a mechanical and chemical wear regime. METHODS: Enamel from polished human molars were sectioned into buccal and occlusal surfaces and randomly allocated into two groups (n = 10) and then exposed to 0.3 % citric acid at pH 2.7 for 10, 20, 40 and 60 mins each followed by abrasion with non-fluoridated toothpaste for 240 strokes in a reciprocating brushing machine. A white light profilometer with a spot size of 12 um measured mean step-height following each cycle. Microhardness indentations were conducted following the final cycled 60 mins erosion/abrasion using 0.01, 0.02, 0.1, 0.5 and 2.5 kgf indentation load. Statistical disparity were evaluated using a two-way ANOVA and post-hoc Sidak's multiple comparisons tests at α = 0.05. RESULTS: After erosion/abrasion, the mean (SD) step-heights on occlusal and buccal surfaces were not significantly different until 60 mins, when occlusal surfaces exhibited greater step-heights, 32.9 µm (2.8) and 31.1 µm (1.8) and p = 0.02, respectively. Buccal and occlusal microhardness was statistically lower following erosion/abrasion at loads of 0.01 kgf (p = 0.0005) and 0.02 kgf (p = 0.0006) but no significant differences were observed in the microhardness between the surfaces at any loads. CONCLUSION: The occlusal and buccal surfaces were not statistically different for microhardness or step height suggesting the susceptibility to wear is not related to the anatomy and structure of the tooth and is more likely related to other factors such as the environment. CLINICAL SIGNIFICANCE: The study emphasizes that a notable difference in wear between occlusal and buccal enamel surfaces emerges only after prolonged exposure to simultaneous chemical and mechanical stress. This finding necessitates a preventive dental approach that accounts for both the duration of exposure and environmental factors.

Supplementation of Energy Drinks with Green Tea Extract: Effect on In Vitro Abrasive/Erosive Dentin Wear.

PURPOSE: To investigate the effect of the supplementation of energy drinks with green tea extract on abrasive and erosive dentin wear. MATERIALS AND METHODS: Six groups, each comprising 15 bovine dentin samples, were prepared, yielding a total of 90 samples. Erosion was performed by immersing the samples in Red Bull and Red Bull light with and without green tea extract. Tap water with and without green tea extract was used as the control groups. The samples were subjected to abrasive/erosive cycling for five days. The following cycling was performed daily: toothbrush abrasion (20 brushstrokes; 2.5 N); eight erosive cycles (2 min storage in the respective solutions); in between the erosive cycles, storage in artificial saliva (60 min) and again toothbrush abrasion (20 brushstrokes; 2.5 N). During the night, samples were again stored in artificial saliva. Abrasive/erosive dentin wear was measured using a stylus profilometer (µm, accuracy = 40 nm). The measured dentin loss results from the vertical position shift on the y-axis from base to final profile after the wear process in 2D. Pairwise comparisons between the groups were carried out using Wilcoxon signed-rank test. RESULTS: The following dentin wear (median [IQR]) was measured: Red Bull: 1.9 µm (0.5); Red Bull Light: 1.3 µm (0.3); Red Bull with green tea extract: 0.8 µm (0.3); Red Bull Light with green tea extract: 0.3 µm (0.5); Tap water with green tea extract: -0.2 µm (0.7); Tap water: -1.0 µm (1.2). The comparison of all tested groups to each other proved to be statistically significant (p < 0.05). CONCLUSION: The supplementation of energy drinks with green tea extract provide a protective effect against erosive/abrasive wear in vitro.

Interaction between Hexametaphosphate, Other Active Ingredients of Toothpastes, and Erosion-Abrasion in Enamel in vitro.

Sodium hexametaphosphate (HMP) as toothpaste additive is claimed to reduce erosive tooth wear and to stabilize stannous ions. However, little is known about the impact of concentration and its interactions with fluoride (F) or stannous+fluoride ions (F/Sn) on enamel erosion and erosion-abrasion. In a 10 day cyclic in vitro erosion-abrasion model, 320 flat human enamel specimens were divided into ten groups (n = 32 each) and daily subjected to six erosive challenges (0.5% citric acid, 2 min) and two toothpaste suspension applications (2 min, 1:3 F-free toothpaste:mineral-salt solution, 0.23% sodium gluconate). Half of specimens per group were additionally brushed twice/day (200 g, 15 s) during suspension immersion. Nine suspensions contained HMP (0.25%, 1.75%, 3.25%), either on its own or combined with F (373 ppm F-) or F/Sn (800 ppm Sn2+, 373 ppm F-). One suspension contained sodium gluconate only (NegContr). After 10 days, specimens' surfaces were analysed with profilometry, energy dispersive X-ray spectroscopy, and scanning electron microscopy. Tissue loss (µm, mean ± standard deviation) in NegContr was 10.9 ± 2.0 (erosion), 22.2 ± 1.6 (erosion-abrasion). Under erosive conditions, only 0.25% HMP in any combination and 1.75% HMP with F/Sn reduced loss significantly (-28% to -54%); 3.25% HMP without F and F/Sn increased loss significantly (+35%). With additional abrasion, no suspension reduced loss significantly compared to NegContr, instead, in groups without F and F/Sn or with 3.25% HMP loss was increased (+15% to +30%). Conclusively, at higher concentrations, HMP increased erosive tooth wear and seemed to reduce anti-erosive effects of fluoride and stannous ions.

The subsurface lesion in erosive tooth wear.

OBJECTIVES: This study compared the surface change on natural and polished enamel exposed to a joint mechanical and chemical wear regimen. METHODS: Human enamel samples were randomly assigned to natural (n = 30) or polished (n = 30) groups, subjected to erosion (n = 10, 0.3% citric acid, 5 min), abrasion (n = 10, 30 s), or a combination (n = 10). Wear in the form of step height was measured with a non-contact profilometer, and surface changes were inspected with SEM on selected sections. Data was normalised and underwent repeated measures MANOVA, accounting for substrate and erosive challenge as independent variables, with Bonferroni correction for significant post hoc interactions. RESULTS: After four cycles, polished samples had mean step heights of 3.08 (0.40) µm after erosion and 4.08 (0.37) µm after erosion/abrasion. For natural samples, these measurements were 1.52 (0.22) µm and 3.62 (0.39) µm, respectively. Natural surfaces displayed less wear than polished surfaces under erosion-only conditions (p<0.0001), but the difference disappeared with added abrasion. SEM revealed a shallow subsurface layer for polished surfaces and natural ones undergoing only erosion. However, natural surfaces exposed to both erosion and abrasion showed deeper subsurface changes up to 50 µm. CONCLUSION: Natural enamel, when exposed to erosion alone, showed less wear and minimal subsurface alterations. But with added abrasion, natural enamel surfaces saw increased wear and notable subsurface changes compared to polished ones. CLINICAL SIGNIFICANCE: The pronounced subsurface lesions observed on eroded/abraded natural enamel surfaces highlight how combined wear challenges may accelerate tooth tissue loss.

Susceptibility of fluorotic enamel to dental erosion-abrasion.

Dental hard tissue conditions can be of pre- or post-eruptive nature, such as enamel fluorosis and erosive tooth wear (ETW), respectively. Dental enamel fluorosis is caused by the chronic and excessive intake of fluoride during enamel development, leading to increased fluoride concentration and increased porosity. ETW has become a common clinical condition and often impairs dental function and aesthetics. This in vitro study tested the hypothesis that fluorotic enamel presents different susceptibility to dental erosion-abrasion. It consisted of a 3×3×2 factorial design, considering a) fluorosis severity: sound (TF0), mild (TF1-2), moderate (TF3-4); b) abrasive challenge: low, medium, and high; and c) erosive challenge: yes or no. A total of 144 human teeth were selected according to the three fluorosis severity levels (n=48), and subdivided into six groups (n = 8) generated by the association of the different erosive and abrasive challenges. Enamel blocks (4×4 mm) were prepared from each tooth and their natural enamel surfaces subjected to an erosion-abrasion cycling model. After cycling, the depth of the lesions in enamel was assessed by profilometry. ANOVA showed that the three-way and two-way interactions among the factors were not significant (p > 0.20). Enamel fluorosis level (p=0.638) and abrasion level (p = 0.390) had no significant effect on lesion depth. Acid exposure caused significantly more enamel surface loss than water (p < 0.001). Considering the limitations of this in vitro study, fluorosis did not affect the susceptibility of enamel to dental erosion-abrasion.

Polyphenols for Preventing Dental Erosion in Pre-clinical Studies with in situ Designs and Simulated Acid Attack.

Dental erosion is a chemical process characterized by acid dissolution of dental hard tissue, and its etiology is multifactorial. Dietary polyphenols can be a strategy for dental erosion management, collaborating to preserve dental tissues through resistance to biodegradation. This study describes a comprehensive review to interpret the effects of polyphenols on dental erosion of pre-clinical models with in situ designs and simulated acid attacks on enamel and dentin samples. We aim to evaluate evidence about Polyphenols' effects in the type of dental substrate, parameters of erosive cycling chosen in the in situ models, and the possible mechanisms involved. An evidence-based literature review was conducted using appropriate search strategies developed for main electronic databases (PubMed, Scopus, Web of Science, LILACS, EMBASE, LIVIVO, CINAHL, and DOSS) and gray literature (Google Scholar). The Joanna Briggs Institute checklist was used to evaluate the quality of the evidence. From a total of 1900 articles, 8 were selected for evidence synthesis, including 224 specimens treated with polyphenols and 224 control samples. Considering the studies included in this review, we could observe that polyphenols tend to promote a reduction in erosive and abrasive wear compared to control groups. However, as the few studies included have a high risk of bias with different methodologies and the estimated effect size is low, this conclusion should not be extrapolated to clinical reality.

Influence of different ultra-soft toothbrushes on erosive tooth wear.

OBJECTIVE: To investigate the influence of different ultra-soft toothbrushes on the progression of erosive tooth wear (ETW). METHODS: Bovine enamel and dentin specimens (n = 10) were submitted to a 5-day erosive-abrasive cycling model (0.3% citric acid for 5 min, artificial saliva for 60 min, 4x/day). Toothbrushing was carried out 2x/day for 15 s, with the different toothbrushes tested (A- Edel White: flexible handle, tapered bristles; B- Oral-B Gengiva Detox: regular handle, criss-cross tapered bristles; C- Colgate Gengiva Therapy: flexible handle, tapered bristles, high tuft density; d- Oral-B Expert Gengiva Sensi: regular handle, round end bristles, high tuft density; E- Oral-B Indicator Plus: soft brush, round end bristles (control). Surface loss (SL, in µm) was assessed by optical profilometry. The toothbrush characteristics were evaluated by a surgical microscope. Data were statistically analyzed (α=0.05). RESULTS: For enamel, toothbrush C showed the highest SL (means±SD: 9.86 ± 1.28) and it did not differ significantly from A (8.60 ± 0.50), both with flexible handles. The lowest SL was observed for the toothbrush Control E (6.76 ± 0.63), which differed significantly from A and C, but not from the other toothbrushes. For dentin, the highest SL was found for toothbrush D (6.97 ± 1.05) and it did not differ significantly from E (6.23 ± 0.71). The lowest SL was observed for B (4.61 ± 0.71) and C (4.85 + 0.83), without significant differences from A (5.01 ± 1.24). CONCLUSIONS: The ultra-soft toothbrushes had different impacts on the progression of ETW on the dental substrates. On enamel, higher ETW values were observed for the flexible handle toothbrushes, while for dentin, round-end bristles (ultra-soft and soft) caused more ETW. CLINICAL SIGNIFICANCE: Knowledge about the effect of different ultra-soft toothbrushes on ETW can help clinicians to recommend the most suitable types for their patients, bearing in mind that toothbrushes can impact enamel and dentin differently.

Epidemiology, aetiology and prevention of tooth wear.

Tooth wear is a commonly reported finding globally; however, many patients are unaware of having tooth wear. Identifying early signs of erosion, abrasion or attrition and determining the risk factors contributing to a patient's tooth wear may help to prevent further loss of enamel and dentine in the future. Appropriate prevention should be instigated, or appropriate referral made to other health professionals, when conditions such as gastroesophageal reflux or eating disorders are suspected. This paper presents the epidemiology and aetiological factors for tooth wear, as well as identifying the common clinical presentations of tooth wear. Patient perspectives on tooth wear and preventive techniques that can be utilised are also discussed.

Abrasive Enamel and Dentin Wear Resulting from Brushing with Toothpastes with Highly Discrepant Relative Enamel Abrasivity (REA) and Relative Dentin Abrasivity (RDA) Values.

PURPOSE: To investigate the absolute wear caused by toothpastes with highly discrepant REA (Relative Enamel Abrasivity) and RDA (Relative Dentin Abrasivity) values on both enamel and dentin: Candida Peppermint (CP; REA: 1; RDA: 42), Colgate Total Original (CTO; REA: 4; RDA: 100), Signal White System (SWS; REA: 8; RDA: 143), and Candida White Diamond (CWD; REA 244; RDA: 12). MATERIALS AND METHODS: Eighty (80) bovine enamel samples and 80 dentin samples were divided into four groups each (n = 20) and investigated after a 6-h brushing procedure (21,600 cycles, 60 cycles/min, load of 2.5 N) with the four toothpastes. The abrasive enamel and dentin wear were registered using a contact profilometer. The median and interquartile range (IQR) of the abrasive enamel and dentin wear were calculated for each group. Pairwise comparisons were conducted using the Wilcoxon signed-rank exact test, and the p-value was adjusted according to Holm (statistical significance set at 0.05). RESULTS: CWD led to the highest abrasive enamel wear (9.86 µm [5.77]). CTO caused the highest abrasive dentin wear (166.70 µm [69.90]), being statistically significantly higher than the wear for CP (54.20 µm [24.00]) and CWD (17.00 µm [7.80]) (p = 0.00001). The abrasive dentin wear for CWD was statistically significantly lower in comparison to all other groups (p = 0.00001). CONCLUSION: Toothpastes with highly discrepant REA and RDA values presented statistically significantly different absolute wear on enamel and dentin. REA and RDA values should both be declared for every toothpaste.

Effect of brushing force on the abrasive dentin wear using slurries with different abrasivity values.

OBJECTIVE: The aim of this study was to investigate the resulting abrasive dentin wear using abrasive slurries with different RDA values and applying increasing brushing forces. METHODS: Forty-five bovine incisors were randomly allocated in three groups (A, B, C, n = 15). One hundred and eighty dentin samples were prepared from these incisors and allocated to twelve groups (A1-A4, B1-B4, C1-C4; n = 15). The groups were subjected to a brushing cycle (120 strokes/min, 25 min) as follows: groups A1 to A4 with an abrasive slurry (RDA = 71) applying increasing brushing forces (1, 2, 3 and 4 N). Groups B1 to B4 were brushed using an abrasive slurry (RDA = 85) and C1 to C4 (RDA = 133) applying the same above-mentioned brushing forces. Abrasive dentin wear was recorded using a stylus profilometer and compared amongst the groups using robust models. Pairwise comparisons in each model were tested and corrected after Tukey's method (α = 0.05). RESULTS: Applying 1-N brushing force resulted in the same amount of abrasive dentin wear in all groups regardless of the abrasivity of the used slurry. Increasing the brushing force to 2 N resulted in statistically significantly higher abrasive wear in all groups. This increase in abrasive wear was much higher when the slurry with high abrasivity was used (RDA = 133) compared with the lower abrasive slurry (RDA = 71). CONCLUSION: The abrasivity of the used slurry does not add to the resulting abrasive wear when the brushing force is kept at 1 N. It seems better to advise and help the patients (showing signs of non-carious cervical lesions) calibrating their brushing force to 1 N, than only to advise them to use toothpastes with lower abrasivities.

The in vitro Effect of Dentifrices With Activated Charcoal on Eroded Teeth.

AIM: The objective of this research was to compare the abrasive potential of dentifrices containing activated charcoal with those of a conventional dentifrice on the development of erosive tooth wear (ETW) in vitro. METHODS: Enamel and dentin samples were divided into toothpastes (n = 12): group (G)1-Colgate Triple Action (1450 ppm F) (positive control); G2-Colgate Natural Extracts (1450 ppm F); G3-Colgate Luminous White Activated Carbon (1450 ppm F); G4-Oral-B Whitening Therapy Charcoal (1100 ppm F); G5-Oral-B 3D White Mineral Clean (1100 ppm F); G6-Curaprox Black Is White (950 ppm F); and G7-erosion only (no abrasion, negative control). All samples were submitted to erosive pH cycles and G1 to G6 to abrasive challenges (15 seconds) using toothpastes' slurries plus 45 seconds of treatment for 7 days. The final profile was overlaid to the baseline one for the ETW calculation (µm). The data were subjected to analysis of variance/Tukey or Kruskal-Wallis/Dunn tests (P < .05). RESULTS: Oral-B 3D White (13.0 ± 1.0, 9.37 [1.36] µm), Oral-B Whitening Therapy (15.1 ± 1.2, 8.58 [1.71] µm), and Colgate Luminous White (13.6 ± 1.0, 7.46 [0.94] µm) toothpastes promoted the greatest enamel and dentin wear. On the other hand, Colgate Triple Action (12.2 ± 1.2, 5.30 [1.26] µm), Colgate Natural Extracts (10.8 ± 1.1, 4.16 [1.11] µm), and Curaprox Black Is White (11.5 ± 1.5, 4.06 [0.92] µm) toothpastes promoted lower wear values, similar to erosion only (4.16 [0.94] µm) in the case of dentin but not enamel (7.1 ± 0.8 µm). CONCLUSIONS: Toothpastes containing charcoal combined with pyrophosphate may have a high abrasive effect on eroded tooth surfaces. Many patients influenced by digital marketing use toothpastes containing activated charcoal with the aim of bleaching their teeth. However, care should be taken when using these products, as they may have a high abrasive effect.

Simulation of Non-Carious Cervical Lesions by Computational Toothbrush Model: A Novel Three-Dimensional Discrete Element Method.

Non-carious cervical lesions (NCCLs) are saucer-shaped abrasions of a tooth. NCCLs can form due to various etiologies, including toothbrushing wear, acid erosion, and mechanical stress. Owing to this complex interplay, the mechanism of NCCLs in tooth abrasion has not been established. This study aims to develop a numerical method using a computational toothbrush to simulate NCCLs. The forces acting on the teeth and the amount of abrasion generated were evaluated. The discrete element method using in-house code, connected particle model, and Archard wear model were applied for brushing. In the toothbrush model, 42 acrylic tufts were fixed into a toothbrush head. The teeth models with enamel properties comprised four flat plates and two grooves to simulate the anterior teeth and NCCLs. The brushing speed and depth for one cycle were established as simulation parameters. The force applied within the ununiform plane was concentrated on several bristles as the toothbrush passed through the interproximal space. The brushing force (depth) had a greater effect on tooth abrasion than the brushing speed. Toothbrushing abrasion was mainly concentrated in the interproximal space. Therefore, forceful tooth brushing can cause NCCLs from the interproximal space to the cervical area of the tooth.

Diamond particles in toothpastes: in-vitro effect on the abrasive enamel wear.

BACKGROUND: Diamond particles have recently been used as abrasives in toothpastes, which raises questions about its abrasive behaviour towards enamel. This study was carried out to investigate the abrasive enamel wear caused by three diamond-loaded toothpastes (Candida White Diamond: CWD, Swiss Smile Diamond Glow: SSDG, Emoform F Diamond: EFD) and to compare it with a traditional toothpaste with silica abrasive (Colgate Total Original CTO). METHODS: Eighty bovine enamel samples were divided into four groups (n = 20) and brushed for 21,600 cycles (60 cycles/min) for 6 h at 2.5-N brushing force. The abrasive enamel wear was recorded with a contact profilometer. The median and interquartile range (IQR) of the abrasive enamel wear was calculated in each group. Pairwise comparisons were conducted using Wilcoxon signed rank exact test and the p value was adjusted according to Holm. Significance level was set at 0.05. RESULTS: Diamond-loaded toothpastes caused statistically significantly higher abrasive wear than the traditional toothpaste (p < 0.0001). SSDG caused statistically significantly higher enamel wear (19.0 µm (11.2)) than CWD (8.4 µm (4.6)) and EFD (7.3 µm (3.9)) (p < 0.0001). CONCLUSIONS: Diamond-loaded toothpastes cause higher enamel wear than toothpastes with traditional abrasives and also exhibit different abrasivity behaviour compared to each other.

Effect of tapered-end and round-end bristles on the abrasive dentine wear applying increasing brushing forces.

OBJECTIVE: To investigate the effect of toothbrush bristles end configuration on the abrasive dentine wear at different brushing forces. MATERIAL AND METHODS: One hundred and sixty bovine dentine samples were randomized into eight groups (n = 20). Groups (1 to 4) were brushed with tapered-end bristles at 1-, 2-, 3-, and 4-N brushing forces, respectively. Groups (5 to 8) were brushed with round-end bristles with the same brushing forces. The brushing sequence was carried out using an abrasive slurry (RDA = 121) for 25 min. Profiles were recorded using a contact profilometer. Mean and standard deviation were calculated for the abrasive dentine wear in each group. Two-way ANOVA was used to locate any significance. The significance values were corrected after Tukey (α = 0.05). RESULTS: Brushing with tapered-end bristles resulted in statistically significantly less abrasive dentine wear than round-end bristles regardless of the applied brushing force (1 N: 4.4 ± 1.5 vs. 7.7 ± 2.0 µm; 2 N: 7.7 ± 2.1 vs. 12.2 ± 2.7 µm; 3 N: 11.3 ± 2.6 vs. 19.4 ± 3.7 µm; 4 N: 11.2 ± 2.1 vs. 25.3 ± 4.8 µm). The interaction between bristle configuration and brushing force was statistically significantly (p < 0.001). CONCLUSION: Tapered-end toothbrushes might be a safer choice for patients, especially when showing signs of non-carious cervical lesion. However, other toothbrush properties should also be considered.

Effect of the toothbrush tuft arrangement and bristle stiffness on the abrasive dentin wear.

The geometrical properties of toothbrushes play a role in developing abrasive tooth wear and non-carious cervical lesions. This study investigated the interplay between the toothbrush tuft arrangement (crossed vs. parallel) and bristle stiffness (soft vs. medium) on the abrasive dentin wear using three slurries with different levels of abrasivity (RDA: 67, 121 and 174). Twelve groups of bovine dentin samples (n = 20) were brushed with a combination of the aforementioned variables. Abrasive dentin wear was recorded with a profilometer and the resulting abrasive wear of each group was calculated and compared with each other using two-way ANOVA and pairwise tests. Toothbrushes with parallel tuft arrangement caused statistically significantly higher dentin wear compared to crossed tuft arrangement, regardless of the abrasivity level of the used slurry and the bristle stiffness. Soft crossed tuft toothbrushes caused statistically significantly higher abrasive dentin wear than medium crossed tuft toothbrushes, while soft and medium parallel tuft toothbrushes caused the same amounts of dentin wear, regardless of the RDA value of the used slurry. These results could be helpful for dentists and dental hygienists when advising patients. Crossed tuft toothbrushes could be a less-abrasive choice in comparison to parallel tuft toothbrushes.

Micro computed tomography analysis of abrasivity of toothpaste tablets compared to conventional toothpaste.

PURPOSE: To evaluate with microCT dentin and enamel abrasion depth caused by toothpaste tablets when compared to conventional toothpastes. METHODS: Dentin (N= 64) and enamel blocks (N=64) were randomized into four experimental groups of 16 specimens each for dentin and enamel. CP: Colgate Cavity Protection, served as the low abrasive toothpaste; AW: Colgate Total Advanced Whitening was used to represent a highly abrasive toothpaste. Two different types of toothpaste tablets were used. DT: Denttabs and BT: Bite tabs. To prepare the slurries, 40 mL of water was added to 25 g of each toothpaste and 4.4 g of each toothpaste tab. Blocks were brushed for a total of 10,000 and 40,000 strokes for dentin and enamel, respectively following ISO standard 11609. On completion of brushing, specimens were scanned with a microCT system. Tomographic 3D reconstruction followed by abrasion depths measurements were performed. Kruskal-Wallis procedure tested abrasion depths among the different groups. Tests of hypotheses were two-sided with an alpha level at 0.05. RESULTS: There was a statistically significant difference in dentin abrasion depth among the groups (P< 0.001). The mean dentin/enamel abrasion depths in microns were 25.3/4.4, 36.8/4.4, 66.8/3.0, and 230.3/15.5 for DT, BT, CP, and AW respectively. Dentin and enamel abrasion depth of AW was the highest and was different from all other groups after multiple comparisons (P< 0.05). CLINICAL SIGNIFICANCE: Dentin abrasivity of toothpaste tabs is negligible as determined with microCT.

Impact of Brushing Protocols on Dentin Abrasion Caused by Different Abrasive Slurries.

PURPOSE: To determine the impact of the brushing protocol on dentin wear by comparing continuous to intermittent brushing, with the same total time of brushing. MATERIALS AND METHODS: Dentin specimens (n = 120) were evently distributed into six groups (A-F). The samples were brushed with slurries of different relative dentin abrasivity (RDA): Groups A+B (Sident 2480-1; RDA 85), groups C+D (Zeodent 113; RDA 67), and groups E+F (Zeodent 103; RDA 174). Groups A+C+E were brushed continuously (25 min) with one slurry preparation, while groups B+D+F were brushed intermittently (25 x 1 min) with a renewal of the slurry after each sequence. Dentin wear was determined using surface profilometry and statistically analysed with ANOVA and post-hoc tests. RESULTS: Neither the mode of brushing (p = 0.72) nor the interaction (p = 0.18) of the brushing mode with the type of abrasive particles had a significant influence on the abrasive dentin wear. Only the type of abrasive particles had a statistically significant influence on abrasive dentin wear (p < 0.001). CONCLUSION: The mode of brushing (continuously or intermittently) has no influence on abrasive dentin wear.

Effect of toothbrush bristle stiffness and toothbrushing force on the abrasive dentine wear.

OBJECTIVE: To investigate the influence of toothbrush bristle stiffness and applied brushing force on the resulting abrasive dentine wear in vitro. METHODS: One hundred sixty bovine dentine samples were randomly allocated in eight groups (n = 20). Groups one to four were brushed with a soft-bristle toothbrush with soft bristles applying 1, 2, 3 and 4 N brushing force, respectively. Groups five to eight were brushed with a medium-bristle toothbrush applying the same aforementioned brushing forces (120 strokes/min, abrasive slurry (RDA = 121), 25 min). Profiles were recorded before and after the brushing sequence, and the median and interquartile range of abrasive dentine wear were calculated and compared using two-way ANOVA and pairwise tests corrected after Tukey (α = 0.05). RESULTS: At 1, 2 and 3 N brushing force, the tested toothbrushes caused no significantly different abrasive dentine wear. At 4 N brushing force, the medium-bristle toothbrush caused statistically significantly higher abrasive force than the soft-bristle toothbrush. Using the medium-bristle toothbrush, abrasive dentine wear statistically significantly increased with increasing brushing force from 1 to 3 N. However, increasing the brushing force to 4 N did not result in statistically significantly higher wear. Using the soft-bristle toothbrush, abrasive dentine wear statistically significantly increased with increasing brushing force from 1 to 2 N. However, increasing the brushing force to 3 or 4 N did not result in statistically significantly higher wear. CONCLUSION: The soft-bristle toothbrush tends to cause less abrasive wear with increasing brushing force than the medium-bristle toothbrush.