Investigation of erosion and abrasion on enamel and dentine: a model in situ using toothpastes of different abrasivity

Surface roughness associated with bacterial adhesion on dental resin-based materials

This study investigates the surface quality and bacterial adhesion properties of various dental materials, including indirect composites, veneering composites, direct composites, polyether ether ketone (PEEK), and two millable polymethyl methacrylate (PMMA). Material specimens were processed following manufacturer instructions, initially evaluated for surface roughness and Streptococcus sanguinis (S. sanguinis) adhesion. Subsequently, toothbrushing simulation was employed to simulate aging, and changes in material surfaces were assessed via roughness measurements and bacterial adhesion testing. Prior to simulated aging, direct and indirect composites exhibited the lowest roughness values. However, after the simulated toothbrushing, veneering composites displayed the highest roughness levels. Both PMMA materials demonstrated the highest S. sanguinis adhesion levels, both before and after artificial aging. Interestingly, the indirect composite material showed a reduction in bacterial adhesion following toothbrushing simulation. Surprisingly, this study did not reveal a clear correlation between roughness and bacterial adhesion.

In Vitro Model to Evaluate the Development of Discolorations on Human Enamel Caused by Treatment with Mouth Rinses and Black Tea Considering Brushing

OBJECTIVES

 The study aimed to develop and test an in vitro model to investigate the staining potential of mouth rinses on human enamel, considering alternating intake of black tea and tooth brushing, thus mimicking the situation in the oral cavity more realistically.

MATERIALS AND METHODS

 Eight mouth rinses with six different active ingredients (benzydamine hydrochloride [BNZ], polyhexamethylene biguanide hydrochloride [PHMB], chlorhexidine digluconate [CHX], hexetidine gluconate [HEX], octenidine dihydrochloride [OCT] and octenidine dihydrochloride + 2-phenoxyethanol [OCTP]) and concentrations were tested. Sets of six halved human molar crowns were initially pretreated by soaking in artificial saliva (30 min). Afterward, the cyclic treatment was started by soaking in artificial saliva (2 min), staining with black tea (1 min), brushing with toothpaste (5 s), and soaking in the mouth rinse (30 s). Samples were rinsed with distilled water after each treatment step. The cyclic treatment was repeated 30 times, mimicking the consumer behavior after 15 days. Photographic images were taken after 0, 10, 20, and 30 cycles. Color measurements were conducted after each staining and brushing step using a VITA-Easyshade spectrophotometer to determine the difference in lightness ∆L and the total color difference ∆E.

STATISTICAL ANALYSIS

 Analysis of variance and post-hoc Tukey test (α = 0.05) were applied.

RESULTS

 The new testing model with included brushing sequences allowed to assess the staining behavior on human teeth and provided a clear differentiation between the different investigated products. In detail, up to cycle 10, ΔE values increased for all mouth rinses with each additional cycle number. However, while ΔE values continued to increase for 0.15% BNZ, 0.1% PHMB, and 0.2% CHX between treatment cycle 10 and 30, ΔE values only slightly increased after treatment with 0.08% OCTP, 0.1% OCTP, 0.1% OCT, and 0.1% HEX. After 20 and 30 cycles, significantly less staining was found for 0.08% OCTP, 0.1% OCT, 0.1% HEX as compared to 0.2% CHX, 0.15% BNZ, and 0.1% PHMB (p < 0.05). ΔE-values were significantly lower after treatment with 0.1% OCTP as compared to 0.2% CHX1 and 0.2% CHX2 (p < 0.05).

CONCLUSION

 The proposed new methodology was found to be appropriate for assessing the staining progression of mouth rinses over a simulated application period of 15 days. The model allows differentiation of products with different active ingredients and concentrations.

Characteristics of tin-containing fluoride toothpastes related to erosive tooth wear protection

OBJECTIVES

To assess the effect of different tin-containing toothpastes on the control of erosive tooth wear in enamel and dentin.

METHODS

Enamel and dentin slabs were randomly distributed into 7 experimental groups (n = 10/substrate): C-: negative control (Artificial saliva); AmF (regular fluoridated toothpaste without tin); Sn-1 (SnF2/NaF); Sn-2 (SnF2/NaF/SnCl2); Sn-3 (SnCl2/NaF); Sn-4 (SnF2/SnCl2); Sn-5 (SnCl2/AmF/NaF/chitosan). Specimens were submitted to 5-day erosion-abrasion cycling. Surface loss (SL) was determined with an optical profilometer. Tin deposition on the tooth surfaces and some characteristics of the toothpastes (pH, potentially available F-, %weight of solid particles, and RDA) were also assessed. Data were statistically analyzed (α = 0.05).

RESULTS

For enamel, the Sn-2 presented the lowest SL, not differing significantly from AmF, C+, and Sn-3. The SL of these groups was significantly lower than the C-, except for Sn-3. Sn-1 and Sn-4 were also not significantly different from C-. For dentin, C- significantly showed the highest SL values, whilst, Sn-1 presented the lowest SL, not differing significantly from AmF, Sn-2, C+, and Sn-3. There was a significant positive association between enamel SL and the pH and tin deposition. Dentin SL was significantly negatively associated with the %weight of solid particles and RDA.

CONCLUSIONS

Most of the tin-toothpastes were able to exhibit some protection against ETW. In this process, the toothpastes characteristics play a role, as lower enamel SL was significantly associated with lower pH values and tin deposition; and lower dentin SL was associated with higher %weight of solid particles and RDA of the toothpastes.

CLINICAL SIGNIFICANCE

Tin-containing toothpastes can be used for erosive tooth wear protection, but our study showed that their effect depends on the pH, amount of tin deposition, % weight of solid particles and RDA of the toohpastes.

The role of calcium in the prevention of erosive tooth wear: a systematic review and meta-analysis

OBJECTIVES

The loss of hard dental tissue due to recurrent acid challenges and mechanical stresses without bacterial involvement is known as erosive tooth wear (ETW). Many studies in the literature have concentrated on variables that may affect the ETW process and prevent its occurrence or reduce its advancement. However, to date, no previous systematic review has evaluated the role of calcium in preventing ETW. Therefore, the purpose of the present systematic review was to review and critically appraise the scientific evidence regarding the role of calcium formulations in the prevention of ETW.

METHODS

The review protocol was registered in the PROSPERO international prospective register of systematic reviews (Ref: CRD42021229819). A literature search was conducted in electronic databases to identify in situ randomized controlled trials evaluating the prevention of ETW following the application of calcium formulations. The outcomes studied included mean enamel loss, surface microhardness, surface roughness, mean erosion/softening depth, mineral loss/precipitation and remineralization. Study characteristics and outcomes of included studies were summarized. Cochrane's risk-of-bias tool 2.0 was used to assess the quality of eligible studies, and meta-analysis using a random effects model was performed.

RESULTS

The search retrieved 869 studies of which 21 were considered eligible. Regarding the results of the quality assessment for potential risk of bias in all included studies, overall, 5 studies were considered as being at low risk, another 12 at unclear risk and 4 at high risk of bias. The findings of the studies showed that the addition of calcium in juice drinks led to reduced enamel loss, with blackcurrant juice presenting 2.6 times statistically significant less enamel loss compared to orange juice (p = 0.0001, I2 = 89%). No statistically significant difference in mean surface microhardness of eroded enamel was recorded between chewing gum with or without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (p = 0.31, I2 = 71%). Contradictory were the results regarding the effect of milk and CPP-ACP pastes on prevention of ETW.

CONCLUSIONS

Calcium formulations play an important role in ETW prevention, mainly through their addition to acidic drinks.

Is the whitening effect of charcoal-based dentifrices related to their abrasive potential or the ability of charcoal to adsorb dyes?

OBJECTIVES

To evaluate if tooth color alteration of activated charcoal-based dentifrices may be attributed to the dye adsorption potential of charcoal (chemical action - C - slurry only) or to the association of dye adsorption with abrasion (chemo-mechanical action - CM- slurry/toothbrushing). Potential adverse effects in surface roughness, gloss, and wear were also assessed.

METHODS

Bovine enamel/dentin specimens were randomly allocated into the groups according to treatments and test model (n = 15): deionized water (negative control- NC); Colgate Maximum Anticaries Protection (conventional toothpaste- positive control- PC); Colgate Luminous White Activated Charcoal (LW); Oral-B 3D White Therapy Charcoal (WT); Curaprox Black is White (BW); Dermavita Whitemax (Activated charcoal powder- WP). Specimens were exposed to the C or CM models, in 28-day staining-treatment cycling. Color change (ΔE00), whiteness index (ΔWID), percentage of alteration of surface roughness (%Raalt), and gloss (%GUalt) were calculated. Additional specimens (n = 9) were indented with a Knoop diamond and subjected to 100,000 abrasion cycles. Enamel wear was determined by calculating the decrease in indentations geometry. Data were analyzed by ANOVA/Tukey tests (α = 0.05).

RESULTS

The CM-model produced lower color change (staining) than C (p = 0.0001). PC, LW, WT, BW, and WP showed similar color results for both models, differing from NC (p < 0.05).%Ra and%GU did not differ among the C-model groups (p > 0.05) and WP exhibited the highest variation (%Ra and%GU) under CM-model. Enamel wear values were lowest in the NC and PC groups, intermediate for LW, WT, BW, and highest for the WP (p < 0.05).

CONCLUSION

Activated charcoal-based dentifrices have a similar ability to minimize tooth staining as the conventional toothpaste, with increased enamel wear potential in the long term (after 100,000 cycles). The activated charcoal powder damaged the enamel surface, showing a higher deleterious effect on enamel roughness, gloss, and wear.

CLINICAL SIGNIFICANCE

Dentifrices containing activated charcoal do not provide superior results to minimize tooth staining compared to conventional toothpaste. Charcoal powder should be used with caution because it promotes higher superficial alterations on the enamel surface.

In Vitro Assessment of Different Toothbrush Designs on Enamel Surface Abrasion: A Profilometric Study

AIM

The purpose of this study was to evaluate the impact of three different toothbrush designs on enamel surface abrasion.

MATERIALS AND METHODS

Sixty intact freshly extracted maxillary central incisors were considered for the study. All of the extracted teeth's surfaces were severely trimmed, leaving only the labial surface intact. In the trial, a conventional teeth-whitening dentifrice slurry was utilized. A brushing model was created to deliver uniform force in unidirectional motion. Dontrix Gauge was used to control the tension of the spring. The force was kept constant at 180 ± 20 g. The mounted enamel samples were separated into three groups (20 samples each) at random: group A: toothbrushes have a flat trim bristle design, group B: toothbrushes have a zigzag pattern, and group C: toothbrushes have a bi-level bristle design. For 2 weeks, each sample was brushed twice daily for 2 minutes. A profilometer was used to measure the average surface roughness.

RESULTS

After toothbrushing, the maximum mean surface roughness score was found in zigzag pattern group (2.10 ± 0.23), followed by bi-level bristle design group (2.06 ± 0.12) and the least was in the flat trim bristle design group (1.96 ± 0.09). There was a significant difference between the different toothbrush bristle pattern groups (p < 0.001).

CONCLUSION

On conclusion, the results of this study showed that, in comparison to toothbrushes with zigzag patterns and bi-level bristle designs, flat trim toothbrush bristle designs cause the least amount of surface abrasion and are relatively safe to use.

CLINICAL SIGNIFICANCE

Toothbrushing with toothpaste contributes significantly to dental abrasion. A variety of parameters, including toothpaste abrasivity and concentration, brushing frequency, brushing length, brushing force, and toothbrush bristle stiffness, have the potential to influence the abrasion process of dental hard tissue.

The effect of phytosphingosine associated with tooth brushing on color change, surface roughness, and microhardness of dental enamel - an in vitro and in situ study

OBJECTIVE

This study evaluated the in vitro and in situ effects of phytosphingosine (PHS) associated with tooth brushing on color stability, surface roughness, and microhardness of dental enamel.

METHODS

Sixty-four specimens of bovine teeth (6 × 6 × 2 mm) were separated into 8 groups (n = 8): S + TB: PHS (spray) + tooth brushing; TB + S: tooth brushing + PHS (spray); I + TB: PHS (immersion) + tooth brushing; TB + I: tooth brushing + PHS (immersion); TB: tooth brushing; S: PHS spray; I: immersion in PHS solution, and Saliva: immersion in saliva. Tooth brushing simulation (Mavtec, Brazil) was performed (356 rpm on 3.8 cm area by the toothbrush - Soft Tek) for 1, 7, 15, and 30 days. PHS remained in contact with specimens for 15 min. The specimens were evaluated before and after tooth brushing for color alteration (Easy Shade, VITA), and surface roughness (Model SJ-201P Mitutoyo), and Knoop microhardness (HMV-2, Shimadzu Corporation). For the in situ analyses, 8 participants were recruited and received an intraoral device with 6 fragments of bovine enamel (6 × 6 × 2 mm). The properties evaluated were the same as those of the in vitro study. Participants were randomized following best results of in vitro tested protocols, for 15 days: TB, TB + S, I + TB. Data obtained by in vitro (two-way ANOVA, Tukey, p < .05) and in situ (one-way ANOVA, Tukey, p < .05) studies were analyzed.

RESULTS

The in vitro study showed that greater color change was found after 30 days. The greatest differences in surface roughness occurred between the initial value and after 1 day. Regarding microhardness, the highest values occurred after 15 and 30 days, which showed similar results. The in situ study showed greater color changes for the TB and I + TB, and greater surface roughness changes for TB as well as a similar increase in microhardness for the PHS protocols, which were higher than TB.

CONCLUSIONS

Phytosphingosine leads to an increase in performance regarding color stability, surface roughness, and microhardness when applied. In general, the application of PHS after brushing showed a positive impact on its performance.

CLINICAL RELEVANCE

Phytosphingosine proved to be interesting for compound prevention formulations in the dentistry field.

ISP Good Clinical Practice Recommendations for the management of Dentin Hypersensitivity

Dentin hypersensitivity (DH) is a rising concern in clinical dentistry that causes pain and discomfort and negatively affects the quality of life of patients. Indian Society of Periodontology conducted a nationwide survey, involving 3000 dentists in December 2020, which revealed significant knowledge gaps regarding DH, viz., under-diagnosis, incorrect differential diagnosis, and treatment strategies/recommendations for the management of DH patients in daily clinical practice. The current paper has been envisioned and conceptualized to update the practicing Indian dentists regarding the so-called enigma of dentistry "Dentin Hypersensitivity," based on the best available contemporary evidence. An expert panel was constituted comprising 30 subject experts from across the country, which after extensive literature review and group discussions formulated these recommendations. The panel advocated routine screening of all dentate patients for exposed dentin areas and DH to avoid under-diagnosis of the condition and suggested an early preventive management. Consensus guidelines/recommendations for the use of desensitizing agents (DAs) at home, including the use of herbal agents, are also provided within the backdrop of the Indian context. The guidelines recommend that active management of DH shall be accomplished by a combination of at home and in-office therapies, starting with the simplest and cost-effective home use of desensitizing toothpastes. A diagnostic decision tree and a flowchart for application in daily practice are designed to manage the patients suffering from DH or presenting with exposed dentin areas in dentition. Various treatment methods to manage DH have been discussed in the paper, including the insights from previously published treatment guidelines. Further, a novel system of classification of DH patients based on specific case definitions has been developed for the first time. Explicit charts regarding the available treatment options and the chronology of institution of the agent, for the management in different case categories of DH, have been provided for quick reference. The management strategy takes into account a decision algorithm based on hierarchy of complexity of treatment options and intends to improve the quality of life of the patient by long-term maintenance with an innovatively defined triple C's or 3Cs approach.

The Effect of Dentifrice on Micro-Hardness, Surface Gloss, and Micro-Roughness of Nano Filled Conventional and Bulk-Fill Polymer Composite-A Micro Indentation and Profilometric Study

The aim of the present study was to evaluate the effect of brushing with two whitening dentifrices (Colgate Optic White (COW) and Colgate Optic White Charcoal (COC)) on surface gloss, micro-roughness, and micro-hardness of nanostructured hybrid conventional (Z350) and bulk-fill (Tetric N Ceram bulk-fill) polymer composite. In total, 96 disk samples using two nano-hybrid composite polymers (Z350 and Tetric N Ceram Bulk-fill) were prepared. All specimens were exposed to two different dentifrices (COW and COC), resulting in four main subgroups in the study. Specimens were assessed for surface gloss, micro-roughness (Ra), and micro-hardness using standardized methodology. Means and standard deviations of properties compared using paired t-test, one-way and two-way ANOVA, and post hoc test. The presence of dentifrices did not show any significant difference in micro-hardness values of Z350 (p > 0.05), whereas micro-hardness of bulk-fill composite significantly reduced on dentifrices exposure (p ≤ 0.05). Bulk-fill polymer composite showed significant reduction in gloss after dentifrice exposure (p < 0.05), however, Z350 showed no significant loss of gloss due to dentifrices (p > 0.05). A significant increase in Ra was observed for both resin materials after exposure to dentifrices (COC and COW). Conventional resin composite (Z350) showed comparable surface hardness and gloss before and after dentifrice exposure, however, micro-roughness increased significantly due to dentifrice exposure. Bulk-fill resin (Tetric N Ceram) showed significant loss of micro-hardness and gloss and increase in micro-roughness on dentifrice exposure. Conventional nano-hybrid composite polymer showed better durability in resisting loss of surface properties compared to bulk-fill resin polymer in the present experiment.

Abrasion Behaviour of Different Charcoal Toothpastes When Using Electric Toothbrushes

OBJECTIVES

The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel.

MATERIALS AND METHODS

A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste-water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing.

RESULTS

The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets.

CONCLUSIONS

Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes.

CLINICAL RELEVANCE

As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

Progress and limitations of current surface registration methods when measuring natural enamel wear

OBJECTIVES

Our ability to detect dental wear on sequential scans is improving. This experiment aimed to determine if widely used surface registration methods were sufficiently accurate to distinguish differences between intervention groups on early wear lesions.

METHODS

Baseline measurements were taken on human molar buccal enamel samples (n = 96) with a confocal scanning profilometer (Taicaan, UK). Samples were randomly assigned to subgroups of brushing (30 linear strokes 300 g force) before or after an acid challenge (10 min citric acid 0.3% immersion) for four test dentifrices (medium abrasivity NaF, medium abrasivity SnF₂, low abrasivity NaF and a water control). Post-experimental profilometry was repeated. 3D step height was analysed using WearCompare (www.leedsdigitaldentistry.co.uk/wearcompare, UK). Percentage Sa change was calculated using Boddies (Taicaan Technologies, Southampton, UK). Data were analysed in SPSS (IBM, USA).

RESULTS

The mean 3D step height (SD) observed when samples were brushed before the erosive challenge was -2.33 µm (3.46) and after was -3.5 µm (5.6). No significant differences were observed between timing of toothbrushing or dentifrice used. The mean % Sa change for the low abrasivity group (water control and low abrasivity NaF) was -10.7% (16.8%) and +28.0% (42.0%) for the medium abrasivity group (medium abrasivity NaF and SnF₂).

CONCLUSIONS

Detectable wear scars were observed at early stages of wear progression. However standard deviations were high and the experiment was underpowered to detect significant changes. Brushing with a low abrasivity dentifrice or water control produced a smoother surface whereas brushing with a high abrasivity dentifrice produced a rougher surface.

CLINICAL SIGNIFICANCE

The methodology currently used to align sequential scans of teeth and measure change is too imprecise to measure early wear on natural enamel surfaces unless a large sample size is used. Further improvements are required before we can fully assess early wear processes on natural teeth using profilometry.

Effect of Photodynamic therapy and Er,Cr: YSGG laser on bond strength of bleached enamel to composite resin

OBJECTIVE

The purpose of the present study was bleached enamel reversal using conventional ascorbic acid (AA) and contemporary methods including Photodynamic therapy (PDT), Er, Cr: YSGG (ECL) on bond integrity to composite resin.

MATERIAL AND METHOD

Forty sound permanent mandibular premolars were collected from a dental clinical setting and disinfected. All forty samples were mounted vertically in a rubber mold exposing only the clinical crown. All samples were bleached using Opalescence Boost Professional Teeth Whitening. After the bleaching procedure, each sample was randomly allocated into four groups according to surface treatment. Samples in group 1 were treated with methylene blue photosensitizer (MBP). Samples in group 2 were exposed to 10% sodium ascorbate. Samples in group 3 were treated with Er, Cr: YSGG laser (ECL). Samples in group 4 were not treated (control). All Samples were treated with 37% phosphoric acid and a bonding agent was applied. A bulk-fill composite was cured to all specimens and all samples were treated in a thermocycler. Specimens were placed in a universal testing machine for shear bond strength (SBS) testing. Descriptive statistics were associated by analysis of variance (ANOVA) and Tukey's post hoc test maintaining level of significance (p<0.05) RESULTS: The lowest SBS scores were achieved in the bleached enamel (BE) group (15.25±1.745 MPa). Whereas, the highest bond integrity was attained by AA group (32.23±1.854 MPa). Samples treated with ECL (31.87±1.659 MPa) and AA (32.23±1.854) were comparable (p>0.05). Samples treated with PDT exhibited significantly different SBS (22.41±1.258) compared to other experimental groups CONCLUSION: ECL showed a reversal effect of BE compared to AA and has the potential to be used in clinical settings. BE reversal using MBP needs further investigation.

Effect of a sonic toothbrush on the abrasive dentine wear using toothpastes with different abrasivity values

Objective

This in vitro study aimed to investigate the effect of a sonic toothbrush on the resulting abrasive dentine wear using toothpastes with different abrasivities compared to the use of a manual toothbrush.

Methods

Ninety‐six bovine dentine samples were divided into six groups and subjected to a brushing sequence (sonic: 20 min, 0.9 N, 10 strokes/min; manual: 20 min, 1.6 N, 60 strokes/min) as follows: group 1: Elmex Sensitive Plus (RDA = 28) + manual toothbrush; group 2: Elmex Sensitive + sonic toothbrush; group 3: Elmex Kariesschutz (RDA = 65) + manual toothbrush; group 4: Elmex Kariesschutz +sonic toothbrush; group 5: Colgate Total Original (RDA = 121) + manual toothbrush; and group 6: Colgate Total Original +sonic toothbrush. The abrasive dentine wear was measured profilometrically.

Results

The median (IQR) abrasive dentine wear was as follows: Elmex Sensitive Plus (manual toothbrush: 2.7 µm (0.8), sonic toothbrush: 3.1 µm (1.9)); Elmex Kariesschutz (manual toothbrush: 4.9 µm (1.4), sonic toothbrush: 6.4 µm (2.1)); and Colgate Total Original (manual toothbrush: 5.2 µm (1.1), sonic toothbrush: 9.0 µm (3.1)). Differences in dentine wear between sonic and manual toothbrushes were statistically significant only in the groups brushed with Elmex Kariesschutz and Colgate Total Original (p ≤ 0.05).

Conclusion

Brushing with a sonic toothbrush could result in a higher abrasive dentine wear compared to manual toothbrush when combined with toothpastes with high abrasivity values.

Oral care product formulations, properties and challenges

This review explores the physical, chemical and structural properties of key components of oral care products, whilst looking at the challenges which need to be overcome to continue to improve the efficacy of oral care, and improve dental health. Oral care has been an essential part of all populations and cultures around the world for thousands of years. To maintain good oral health, dental plaque causing bacteria and malodour must be controlled whilst also strengthening and protecting the teeth to prevent dental caries. Advanced modern formulations need to provide controlled and extended release of ingredients vital for dental health. With modern day products such as toothpastes and mouthwashes, it has never been easier to maintain good oral hygiene and health, yet the incidence of dental caries is still on the rise. The complex formulations of modern toothpastes and mouthwashes makes them one of the most sophisticated pharmaceutical products on the market today. The demands of the consumer coupled with the complexity of the oral cavity make it one of the most challenging development processes.

Diagnosis of Occlusal Tooth Wear Using 3D Imaging of Optical Coherence Tomography Ex Vivo

The aim of this study was to assess the utility of 3D imaging of optical coherence tomography (OCT) for the diagnosis of occlusal tooth wear ex vivo. Sixty-three extracted human molars with or without visible tooth wear were collected to take digital intraoral radiography and 3D OCT images. The degree of tooth wear was evaluated by 12 examiners and scored using 4-rank scale: 1-slight enamel wear; 2-distinct enamel wear; 3-tooth wear with slight dentin exposure; 4-tooth wear with distinct involvement of dentin. The degree of tooth wear was validated by the histological view of confocal laser scanning microscopy (CLSM). The sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic analysis were calculated. Diagnostic accuracy was compared with the agreement with CLSM observation using weighted kappa. The results were statistically analyzed at a significance level of α = 0.05. Three-dimensional OCT showed significantly higher sensitivity (p < 0.05) for all the diagnostic thresholds of enamel wear and dentin exposure than digital radiography (0.82, 0.85, and 0.79 vs. 0.56, 0.52, and 0.57, respectively). Three-dimensional OCT showed higher AUC and kappa coefficients than digital radiography (p < 0.05), where mean AUC and Kappa values were 0.95 and 0.76 for OCT and 0.92 and 0.47 for radiography, respectively. No significant difference of specificity was observed (p > 0.05). Three-dimensional OCT could visualize and estimate the degree of tooth wear and detect the dentin exposure at the tooth wear surface accurately and reproducibly. Consequently, a new guideline for tooth wear assessment can be proposed using OCT.

Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures

Purpose

The aim of this study was to evaluate the effect of erosive/abrasive cycles and two different levels of abrasiveness of dentifrices over enamel and dentin subjected to bleaching.

Methods

Enamel and dentin bovine specimens were prepared and submitted to an at-home bleaching treatment using 9.5% hydrogen peroxide gel, which was applied daily (30 min/14 days). Concomitant with bleaching, an erosive cycle was performed using citric acid (0.3%, pH 3.8, 5 mins, 3×/day), followed by immersions in artificial saliva for remineralization (30 mins). Abrasion was done with two (high and low abrasiveness) dentifrices (2×/day, 120 seconds) after the first and third erosive immersion each day. Enamel and dentin softening were assessed by microhardness and erosive tooth wear by optical profilometry. Data were submitted to repeated measures ANOVA, followed by the Tukey’s test with a significance level of 5%.

Results

For the enamel and considering the erosive-abrasive cycle, significant differences were found between the groups tested, the bleaching, and the abrasiveness of the dentifrice tested; however, the final microhardness values were significantly lower than the initial ones. For dentin, differences were found between the eroded/abrasion and the non-eroded/abrasion groups, with the former presenting lower microhardness values compared with the latter. In addition, bleaching decreased the microhardness values only for the highly abrasive dentifrice, and the final values were lower than for the initial ones for all tested groups.

Conclusion

The use of high and low abrasiveness dentifrices during bleaching and concomitant with erosion/abrasion cycles is more harmful to dentin than to enamel.

Clinical Relevance

Although bleaching is considered a conservative treatment, it can cause deleterious effects to dental hard tissue. The association of an at-home bleaching technique with erosion and high- or low- abrasive dentifrices harms dentin more than enamel.

Baking soda as an abrasive in toothpastes: Mechanism of action and safety and effectiveness considerations

BACKGROUND

Toothpastes can be formulated with different abrasive systems, depending on their intended clinical application. This formulation potentially affects their effectiveness and safety and, therefore, requires proper understanding. In this article, the authors focused on abrasive aspects of toothpastes containing sodium bicarbonate (baking soda), which have gained considerable attention because of their low abrasivity and good compatibility, while providing clinical effectiveness (further detailed in the other articles of this special issue). The authors first appraised the role of toothpaste abrasivity on tooth wear, exploring some underlying processes and the existing methods to determine toothpaste abrasivity.

TYPES OF STUDIES REVIEWED

The authors reviewed the available data on the abrasivity of toothpastes containing baking soda and reported a summary of findings highlighting the clinical implications.

CONCLUSIONS

On the basis of the collected evidence, baking soda has an intrinsic low-abrasive nature because of its comparatively lower hardness in relation to enamel and dentin. Baking soda toothpastes also may contain other ingredients, which can increase their stain removal effectiveness and, consequently, abrasivity.

PRACTICAL IMPLICATIONS

Even those formulations have abrasivity well within the safety limit regulatory agencies have established and, therefore, can be considered safe.

Optical and Surface Properties of Monolithic Zirconia after Simulated Toothbrushing

This in vitro study investigated the impact of various dentifrices on the shade, translucency, gloss, and surface characteristics of polishing- or glazing-finished monolithic zirconia surfaces after simulated toothbrushing. Eighty square-shaped monolithic zirconia specimens were divided into two major groups based on the finishing methods—polished (P) and glazed (G). Next, specimens from the two major groups were categorized into four subgroups: stored in distilled water (DW, control); brushed with a fluoride-free conventional dentifrice (C); brushed with a fluoride dentifrice (F); and brushed with a whitening dentifrice (W). Overall, eight groups were created—PDW, PC, PF, PW, GDW, GC, GF, and GW (n = 10 each). Shade, translucency, surface gloss, surface roughness, crystalline phase, and superficial topography data were obtained. Repeated-measures ANOVA and two-way ANOVA were used for intergroup comparison (all α = 0.05). The color differences (ΔE₀₀) between pre- and posttreatment were 0.3158 (PDW), 0.7164 (PC), 0.7498 (PF), 0.8106 (PW), 0.1953 (GDW), 0.301 (GC), 0.3051 (GF), and 0.4846 (GW). A statistically significant difference was observed among the ΔE₀₀, surface gloss, and surface roughness of monolithic zirconia. Thus, brushing with several dentifrices markedly affects the optical properties and surface characteristics of monolithic zirconia finished with polishing or glazing methods.

Tooth wear and cleaning effect of an abrasive-free dentifrice

Background/purpose

To evaluate the degree of wear on human teeth and the cleaning effect of abrasive-free dentifrice. A sodium pyrophosphate and cellulose-containing abrasive-free dentifrice and calcium carbonate-containing control dentifrice were evaluated.

Materials and methods

Dentin and enamel specimens were subjected to 109,500 successive double strokes and 5480 double strokes in pH-cycling condition. A profilometer measured abrasion depth. The cleaning effect of dentifrices on artificial stain was evaluated by cleaning power (modified Stookey method) and by removal of colored stain on artificial tooth.

Results

The experimental results were evaluated using Mann–Whitney U test. The abrasion depth in dentin specimens was 13.97–26.73 times smaller with abrasive-free dentifrice than with control dentifrice. The abrasion depth of enamel specimen was 2.17 ± 0.66 μm with control dentifrice. The values for abrasive-free dentifrice were too small to measure. In pH-cycling conditions using dentin specimens, abrasion depth was 14.28–19.00 times smaller with abrasive-free dentifrice than with control dentifrice. The cleaning power and removing effect of colored stain were statistically insignificant between abrasive-free dentifrice and control dentifrice (P > 0.05).

Conclusion

The abrasive-free dentifrice was as effective as control dentifrice in its cleaning effect on artificial stain and can significantly reduce tooth wear more than control dentifrice.

Is the dentifrice containing calcium silicate, sodium phosphate, and fluoride able to protect enamel against chemical mechanical wear? An in situ/ex vivo study

OBJECTIVES

The aim of this study was to investigate the effect of a dentifrice that contains calcium silicate, sodium phosphate, and fluoride on erosive-abrasive enamel wear.

MATERIAL AND METHODS

This randomized, single-blind in situ/ex vivo study was conducted with four crossover phases of 5 days (one group tested per phase). Bovine enamel blocks (n = 256) were allocated to 16 volunteers and 8 groups. The groups under study were test dentifrice, with calcium silicate, sodium phosphate, and 1450 ppm sodium monofluorophosphate; tin dentifrice, with 3500 ppm stannous chloride, 700 ppm amine fluoride, and 700 ppm sodium fluoride; conventional dentifrice, with 1450 ppm sodium monofluorophosphate; and control (deionized water). Half of the enamel blocks were subjected to erosion and the other half to erosion plus abrasion. The daily extraoral protocol consisted in four citric acid exposures (2 min) and two applications of dentifrice slurry on all blocks for 30 s; after, half of the blocks were brushed for 15 s. The response variable was enamel loss. Data were analyzed by two-way ANOVA and Fisher's test (p < 0.05).

RESULTS

For erosion, the test dentifrice promoted less enamel loss than water (4.7 ± 3.1 and 5.8 ± 2.5 μm, respectively, p < 0.05), and did not differ from tin (4.8 ± 2.5 μm) and conventional (4.8 ± 1.4 μm) dentifrices (p > 0.05). However, the test dentifrice (7.7 ± 3.8 μm) promoted higher wear after erosive plus abrasive procedures than tin (5.4 ± 1.5 μm) and conventional (6.2 ± 1.7 μm, p < 0.05) dentifrices, and did not differ from water (6.9 ± 2.0 μm).

CONCLUSIONS

The investigated dentifrice reduced enamel loss against acid challenge but had no effect against acid and brushing challenge.

CLINICAL RELEVANCE

Little is known regarding the preventive effect of dentifrices indicated for dental erosion. The tested anti-erosive dentifrice was unable to protect enamel when erosion was associated to toothbrushing abrasion.

The Role of Occlusal Factors in the Presence of Noncarious Cervical Lesions in Young People: A Case-Control Study

Objective:

The aim of this retrospective case-control study was to evaluate the influence of different occlusal characteristics and self-referred bruxism in the presence of noncarious cervical lesions (NCCLs).

Methods and Materials:

The participants were 280 students (140 cases and 140 controls), with an average age of 24.5 years, from six schools of dentistry in Spain. Clinical examination was carried out to record the NCCLs and the static and dynamic occlusal characteristics. The side of mastication and bruxism was collected by questionnaire. Data variables were analyzed by means of univariate and multivariate logistic regression. Odds ratios and the respective 95% confidence intervals were calculated (p&lt;0.05).

Results:

The presence of NCCLs was significantly more likely in subjects with protrusive interferences (odds ratio [OR]=1.82); with lateral interferences, especially on the nonworking side (OR= 1.77); or who were self-reported bruxists (OR=1.72). In the multivariate analysis, protrusive interferences, bruxism, age, and the presence of attrition were risk factors for the development of NCCLs. These factors resulted in a model with an area under the receiver-operating characteristic curve of 0.667 and a positive predictive value of 61.43%.

Conclusions:

There was no significant relationship between most occlusal factors and the presence of NCCLs. Only bruxism, protrusive interferences, age, and occlusal wear were risk factors. The predictive model was not sufficiently explanatory. Occlusal factors alone do not appear to be sufficient to explain the presence of NCCLs.

Effect of four different dentifrices applied by customized automated brushing device on enamel surface abrasion: An in vitro profilometric study

Aim:

The aim of this study is to evaluate the enamel surface abrasion using four different dentifrices and a customized automated brushing machine under a profilometer.

Materials and Methods:

A total of 30 enamel blocks (9 mm × 9 mm × 2 mm) were prepared from freshly extracted maxillary central incisors which were randomly divided into five equal groups (Group 1: specimens brushed with Colgate Total, Group 2: specimens brushed with Colgate Lemon and Salt, Group 3: specimens brushed with Colgate Visible White, Group 4: specimens brushed with Colgate Sensitive, and Group 5: intact enamel surface). Samples were brushed using a customized automated toothbrushing machine for 60 min. A profilometric read out (Ra value) was taken for each group subjected to brushing and also for the control group.

Statistical Analysis:

Statistical analysis used in this study was one-way analysis of variance followed by post hoc Tukey's test.

Results:

Statistically significant differences (P < 0.05) were observed in the values of enamel abrasion (Ra) among Group 1–Group 4 whereas Group 5 (control group) had no significant difference in enamel abrasion (P > 0.05).

Conclusion:

The highest enamel abrasion was observed in the group with Colgate Visible White toothpaste, and the least enamel abrasion was seen in the group with Colgate Sensitive Plus.

Use of "Surface Analyzer" to evaluate the Effect of Two Polishing Systems on Surface Texture of Four Newer Composites

Composites polymerized with a clear matrix on the surface will leave a resin-rich surface layer that is easily abraded in the oral environment, exposing unpolished, rough, inorganic filler material. The purpose of this study was to evaluate the polishing effect of two different polishing systems: One-step (PoGo) system and Sof-Lex (multistep) system on four different resin composites: Synergy D6, Clearfil APX Esthetics, Filtek Z 350 XT, Ceram X Mono. After polishing, the specimens were analyzed for average surface roughness using a two-dimensional surface profilometer. How to cite this article: Garg S, Goel M, Verma S, Mahajan N, Kaul B, Garg V. Use of "Surface Analyzer" to evaluate the Effect of Two Polishing Systems on Surface Texture of Four Newer Composites. Int J Clin Pediatr Dent 2018;11(4):266-270.

A guide to the clinical management of attrition

Attrition is an enigmatic condition often found in older individuals and often as a result of bruxism which can take place as a result of either day bruxism, night bruxism or both. Various studies and systemic reviews clearly shown that tooth wear is an age-related phenomena and the last Adult Dental Health Survey showed that 15% of participants showed moderate wear and 3% severe wear with 80% of patients over 50 years of age showing signs of wear. This review examines current theories around the aetiological factors contributing to attrition together with the clinical management of attrition focusing on minimal intervention where possible.

A randomised exploratory clinical evaluation of dentifrices used as controls in dentinal hypersensitivity studies

OBJECTIVES

To explore relative efficacy of six negative-control dentifrices utilised as controls in clinical studies compared with two dentine hypersensitivity (DH)-relief dentifrices used 2×/day for 8 weeks.

METHODS

Six control dentifrices differing in terms of fluoride source (sodium fluoride/sodium monofluorophosphate), abrasive base (silica/dicalcium phosphate), relative dentine abrasivity (RDA) (∼17 to ∼180) and colour (white/blue/multicoloured stripes) were compared with a depolarising dentifrice (5% KNO₃; RDA ∼70-97; 'Test 1') and an occlusion-technology dentifrice (0.454% SnF₂; RDA ∼160-180; 'Test 2'). DH was assessed using tactile and evaporative (air) (measured by Schiff Sensitivity Scale and a visual rating scale [VRS]) stimuli.

RESULTS

In total 249 subjects were randomized. All dentifrices yielded statistically significant improvements from baseline on all endpoints. The two DH-relief dentifrices ranked highest in terms of improvement in scores over the control dentifrices. While there was a clear differentiation between Test 1 and control dentifrices on both measures at 4/8 weeks, for Test 2, statistically significant improvements in Schiff scores were observed over all controls at Week 4 but only over three at Week 8. At Week 4 none of the controls separated from Test 2 on tactile threshold; all separated by Week 8. VRS scores did not separate test and control dentifrices. Dentifrices were generally well-tolerated.

CONCLUSIONS

The six negative-control dentifrices can be used to assess dentifrices considered to be effective in reducing DH. Although response ranges for commercially available negative controls varied, these results may begin to set acceptable performance ranges for control dentifrices in DH trials.

Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement

Objective

The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces.

Methods

Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05).

Results

The mean (standard deviation) surface loss was 21.03 (±1.26) μm for the sonic toothbrush, 15.71 (±0.85) μm for the oscillating-rotating toothbrush, 6.13 (±1.24) μm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) μm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05.

Conclusion

Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5—year simulation.

A novel approach to study in situ enamel erosion and abrasion lesions

OBJECTIVES

This study investigated previous hypotheses that the tongue can abrade acid softened/eroded enamel surfaces.

METHODS

Twelve upper removable appliances each retaining 2 anterior and 2 posterior human enamel specimens were constructed. Each specimen was exposed to acid on both surfaces, but only one surface was allowed contact with the tongue. Therefore, 96 surfaces were assessed. Appliances were worn from 9.30 to 17.00 Monday to Friday for 22days. Acid eroded lesions were created by immersing the specimens for 5min in 50ml orange juice three times daily. Enamel loss was measured using Quantitative light- induced fluorescence (QLF) and Non- contact profilometry (NCLP) and the differences (D) between tongue (D_t) and palate facing (D_P) surfaces determined.

RESULTS

%ΔF_D(t-p) from the two anterior specimens were greater than from those placed posteriorly with mean values of 15.9% (±9.1) and 14.4% (±8.4), 5.6% (±8.7) and 4.5% (±6.6) respectively. Similarly, NCLP data showed anterior specimens had greater differences for mean step height (MSH) between tongue- facing and the palate- facing (control) surfaces than posterior specimens. MSH_D(t-p) values were 59.4μm (±30.3) for anterior tongue facing surfaces and 55.5μm (±29.4) for posterior palate facing surfaces. For the posterior specimens MSH was 48.1μm (±26.1) and 51.7μm (±30.4) respectively (p<0.05).

CONCLUSION

The greater enamel surface loss of the anterior specimens demonstrates that abrasion by the tongue on acid softened/eroded enamel in situ is likely.

Are Pediatric Antibiotic Formulations Potentials Risk Factors for Dental Caries and Dental Erosion?

Introduction:

One of the most frequent parents’ concerns is that oral antibiotic formulations induce dental damage in their children’s. This study aimed to assess the cariogenic and erosive potentials of 29 pediatric antibiotics.

Materials and Methods:

Replicates of each antibiotic were analyzed for the concentration of sugars (sucrose, glucose and fructose) and sorbitol by high performance liquid chromatography (HPLC). The pH was determined by digital pHmeter. Titratable acidity was determined in triplicate using the same pHmeter by gradual addition of 0.1N sodium hydroxide (NaOH) until pH 7.0. Viscosity measurements were carried out using a viscosimeter. In order to rank the relative performance of each medicine, the DEA (Data Envelopment Analysis) methodology was used.

Results:

Sucrose was present in most samples (n=24) with concentrations ranging from 26 to ≈ 100g% (w/w). Only one antibiotic contained sorbitol (66.9g%). Twenty seven antibiotics presented pH values ranging from 4.1 to 6.9 and most of them (n=15) showed the pH below the critical value for dissolution of hydroxyapatite. The values of titratable acidity and viscosity ranged from 0.26 to 40.48 ml and from 20 to 1780cP, respectively. DEA methodology showed that two medicines were distant from the performance frontier (Klaricid^® 50mg and Zinnat^® 250mg), which means that these medicines showed the worst performance and, therefore, greater potential for dissolution of dental enamel.

Conclusion:

Many antibiotics presented high concentration of sugars, high titratable acidity, pH below the critical value and high viscosity which can be considered risk factors for dental caries and erosion, when consumed frequently.

Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin--An In Vitro Study

Aim

The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin.

Materials and Methods

Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis.

Results

With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group.

Conclusions

Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions.

Protective effects of resin sealant and flowable composite coatings against erosive and abrasive wear of dental hard tissues

OBJECTIVES

To test the effectiveness of sealant and flowable composite coating on eroded enamel, dentin and cementum under erosive/abrasive challenges in vitro.

METHODS

A total of 108 tissue sections (36 each for enamel, dentin and cementum) from third molars were assigned to three groups: Seal & Protect sealant (S&P), Tetric EvoFlow composite (TEF) and control. Erosive/abrasive lesions were created on each specimen by citric acid and brushing with toothpaste. S&P and TEF were applied to the lesions and subjected to erosive/abrasive cycling included 24 cycles of immersion in citric acid (pH 3.6) for 60min, followed by remineralization for 120min and brushing with toothpastes for 600 strokes at 150g. Erosive wear of materials or dental tissues were measured with 3D scanning microscopy and data were analyzed using ANOVA.

RESULTS

Treatments with S&P and TEF created a protective material coating of 42.7±17.8μm and 150.8±9.9μm in thickness, respectively. After 24 cycles of erosive/abrasive challenges, tissue losses were -346.9±37.3μm for enamel, -166.5±26.3μm for dentin and -164.7±18.2μm for cementum in untreated controls, as compared to material losses of -24.4±3.3μm for S&P, and -10.8±4.4μm for TEF, respectively. Both S&P and TEF were effective in protecting enamel, dentin and cementum against erosive tooth wear (p<0.01). S&P exhibited faster wear than TEF (p<0.01) and showed spotted peeling in a third of the specimens. TEF remained intact on all three types of dental tissues at the end of the 24 cycles of erosive/abrasive challenges.

CONCLUSIONS

A thin coating of flowable composite resin 150μm in thickness may provide long-term protection against erosive/abrasive tooth wear. Resin sealant may provide adequate protection for dental hard tissues in short-term and may require repeated applications if long-term protection is desired.

Comparative evaluation of surface properties of enamel and different esthetic restorative materials under erosive and abrasive challenges: An in vitro study

Introduction:

Noncarious tooth surface loss is a normal physiological process occurring throughout the life, but it can often become a problem affecting function, esthetics or cause pain.

Aim:

The purpose of this study was to assess the effect of erosive and abrasive challenges on the surface microhardness and surface wear of enamel and three different restorative materials, that is, nanofilled composite, microfilled composite and resin-modified glass ionomer cement (RMGIC) by using Vickers microhardness tester and profilometer respectively.

Subjects and Methods:

Nanofilled composite (Filtek^™ Z350 × T), microfilled composite (Heliomolar^®) and RMGIC (Fuji II LC) were used in the study.

Results:

Nanofilled composite resin has the best resistance to erosion and/or abrasion among all the materials tested, followed by microfilled composite and RMGIC respectively.

Conclusion:

Toothbrush abrasion has a synergistic effect with erosion on substance loss of human enamel, composites, and RMGIC. The susceptibility to acid and/or toothbrush abrasion of human enamel was higher compared to restorative materials.

Three-dimensional in vitro measurements of tooth wear using fluoridated dentifrices

BACKGROUND

The aim of this study was to compare differences in wear of human enamel and dentine in vitro using a 3D measurement method comparing silica versus non-silica containing fluoridated dentifrices (Colgate Total(™) [CT] or Fluor Protector Gel(™) [FPG]).

METHODS

Mounted native enamel (n = 36) and polished dentine (n = 36) samples were subjected to 10 wear cycles. Each cycle consisted of: (1) 1 hour remineralization in artificial saliva (AS); (2) 10 minute erosion (0.3% citric acid; pH = 2.8); (3) 2 minute toothbrush abrasion in AS (G1, control) or a slurry of 3:1 by weight of AS:dentifrice (G2 = CT; G3 = FPG) under a load of 2 N. Each group contained 12 enamel and 12 dentine samples. Paired pre- and post-wear scans made with a contacting scanner were digitally superimposed using ball bearings as datum.

RESULTS

Mean and (SD) enamel wear was G1 = 21.9 μm (6.4); G2 = 15.2 μm (2.8); G3 = 16.9 μm (3.2). Enamel wear was not different between dentifrices (p = 0.99). Both dentifrices resulted in less enamel wear compared to the control (p < 0.05). Dentine wear was G1 = 41.3 μm (8.1); G2 = 29.1 μm (4.4); G3 = 22.1 μm (3.5). Differences in measurements were observed between dentifrices and control (p < 0.05) and between dentifrices (p = 0.014) with FPG showing less dentine wear than CT.

CONCLUSIONS

FPG offered protection against erosive/abrasive tooth wear in dentine compared to CT. FPG did not offer such protective effect on enamel wear.

Remineralization and repair of enamel surface by biomimetic Zn-carbonate hydroxyapatite containing toothpaste: a comparative in vivo study

Consumption of acidic foods and drinks and other factors that cause enamel wear are responsible for the daily enamel loss and degradation. Use of some toothpastes that have been showed to possess different properties of remineralisation and/or repair of the enamel surface may help to protect tooth enamel. The aim of this study was to evaluate whether the use of toothpaste containing Zn-carbonate hydroxyapatite (CHA) nanostructured microcrystals may exert remineralization/repair effects of the enamel surface. Two groups of patients, aged between 18 and 75 years, used a Zn-CHA nanocrystals-based toothpaste (experimental group) and a potassium nitrate/sodium fluoride toothpaste (active control group) for 8 weeks. At the end of this period, extractions were performed in five subjects per study group. Negative controls consisted of two subjects treated with non-specified fluoride toothpaste. Teeth were processed for morphological and chemical-physic superficial characterizations by means of Scanning Electronic Microscopy with Elementary analysis, X-Ray Diffraction analysis and Infrared analysis. In this study, the use of a Zn-CHA nanocrystals toothpaste led to a remineralization/repair of the enamel surface, by deposition of a hydroxyapatite-rich coating. On the other hand, the use of both a nitrate potassium/sodium fluoride and non-specified fluoride toothpastes did not appreciably change the enamel surface. In conclusion, this study demonstrates that the toothpaste containing Zn-CHA nanostructured microcrystals, differently from nitrate potassium/sodium fluoride and non-specified fluoride toothpastes, may promote enamel superficial repair by means of the formation of a protective biomimetic CHA coating.

Dentifrice fluoride and abrasivity interplay on artificial caries lesions

Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

Use of dentifrices to prevent erosive tooth wear: harmful or helpful?

Dental erosion is the loss of dental hard tissues caused by non-bacterial acids. Due to acid contact, the tooth surface becomes softened and more prone to abrasion from toothbrushing. Dentifrices containing different active agents may be helpful in allowing rehardening or in increasing surface resistance to further acidic or mechanical impacts. However, dentifrices are applied together with brushing and, depending on how and when toothbrushing is performed, as well as the type of dentifrice and toothbrush used, may increase wear. This review focuses on the potential harmful and helpful effects associated with the use of dentifrices with regard to erosive wear. While active ingredients like fluorides or agents with special anti-erosive properties were shown to offer some degree of protection against erosion and combined erosion/abrasion, the abrasive effects of dentifrices may increase the surface loss of eroded teeth. However, most evidence to date comes from in vitro and in situ studies, so clinical trials are necessary for a better understanding of the complex interaction of active ingredients and abrasives and their effects on erosive tooth wear.

Characterization of Dentifrices Containing Desensitizing Agents, Triclosan or Whitening Agents: EDX and SEM Analysis

Dentifrices with different compositions are available on the market, but there is limited information about their properties. The aim of this in vitro study was to evaluate the physicochemical characteristics of 12 dentifrices divided into three categories, as containing desensitizing agents, Triclosan or whitening agents. Desiccation loss/residue analysis: 5 g of dentifrice was weighed five times for each group. pH analysis: 5 g of dentifrice were diluted in three parts of distilled water and analyzed using a digital potentiometer. Scanning electron microscopy (SEM): analysis of ashes, shape and size of the particles. Energy-dispersive x-ray spectroscopy (EDX): identification of the abrasive elements. Data were analyzed using ANOVA, Bonferroni post hoc test (α=0.05). Desiccation loss: 38.21% to 65.83%. Dentifrices containing Triclosan and desensitizing agents showed statistically significant differences among them (p<0.05). Whitening dentifrices showed statistically significant differences between Close-Up Whitening and Sensodyne Branqueador (44.72%, 65.83%, respectively). Most dentifrices presented neutral or basic pH. Different shape and size particles were observed in the SEM analysis. Abrasive elements were identified in the EDX. These results demonstrate that the evaluated dentifrices had different properties and their composition influences directly their characteristics, thus resulting in a more or less abrasive action on tooth surface. Knowing the characteristics of the dentifrices is important to indicate the ideal product for each case.

Influence of different toothpaste abrasives on the bristle end-rounding quality of toothbrushes

OBJECTIVES

To evaluate the influence of different toothpaste abrasives on the bristle wear and bristle tip morphology of toothbrushes with different degrees of hardness.

MATERIAL AND METHODS

Ninety samples of bovine incisor teeth were used in this study. The samples were randomly divided into three groups according to the bristle hardness of the toothbrush used: soft bristles (S); extra-soft bristles (ES); hard bristles (H). The toothbrushes of each group were randomly divided into six subgroups with five toothbrushes each, according to the abrasive of the toothpaste used in the simulation: Negative control (distilled water); toothpaste 1 (silica); toothpaste 2 (hydrated silica); toothpaste 3 (calcium carbonate, calcium bicarbonate and silica); toothpaste 4 (tetrapotassium pyrophosphate, silica and titanium dioxide); toothpaste 5 (calcium carbonate). The samples were placed in a toothbrushing simulating machine that simulating three months of brushing. The toothbrush bristles were evaluated by the bristle wear index, and the bristle tips morphology was evaluated by the bristle tip morphology index.

RESULTS

The ES brush presented the highest bristle wear among the toothbrushes. Additionally, the S brushes showed better morphology of the bristles followed by ES and H brushes. The type of abrasive only influenced the bristle tip morphology of the ES brushes. The toothpaste 3 induced the worse bristle tip morphology than all the other toothpastes.

CONCLUSIONS

Different abrasives have influence only on the bristle tip morphology of the ES brushes.