Topical fluoride as a cause of dental fluorosis in children.

BACKGROUND: This is an update of a review first published in 2010. Use of topical fluoride has become more common over time. Excessive fluoride consumption from topical fluorides in young children could potentially lead to dental fluorosis in permanent teeth. OBJECTIVES: To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis in permanent teeth. SEARCH METHODS: We carried out electronic searches of the Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase, three other databases, and two trials registers. We searched the reference lists of relevant articles. The latest search date was 28 July 2022. SELECTION CRITERIA: We included randomized controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies, and cross-sectional surveys comparing fluoride toothpaste, mouth rinses, gels, foams, paint-on solutions, and varnishes to a different fluoride therapy, placebo, or no intervention. Upon the introduction of topical fluorides, the target population was children under six years of age. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane and used GRADE to assess the certainty of the evidence. The primary outcome measure was the percentage prevalence of fluorosis in the permanent teeth. Two authors extracted data from all included studies. In cases where both adjusted and unadjusted risk ratios or odds ratios were reported, we used the adjusted value in the meta-analysis. MAIN RESULTS: We included 43 studies: three RCTs, four cohort studies, 10 case-control studies, and 26 cross-sectional surveys. We judged all three RCTs, one cohort study, one case-control study, and six cross-sectional studies to have some concerns for risk of bias. We judged all other observational studies to be at high risk of bias. We grouped the studies into five comparisons. Comparison 1. Age at which children started toothbrushing with fluoride toothpaste Two cohort studies (260 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing at or before 12 months versus after 12 months and the development of fluorosis (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.81 to 1.18; very low-certainty evidence). Similarly, evidence from one cohort study (3939 children) and two cross-sectional studies (1484 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing before or after the age of 24 months (RR 0.83, 95% CI 0.61 to 1.13; very low-certainty evidence) or before or after four years (odds ratio (OR) 1.60, 95% CI 0.77 to 3.35; very low-certainty evidence), respectively. Comparison 2. Frequency of toothbrushing with fluoride toothpaste Two case-control studies (258 children) provided very uncertain evidence regarding the association between children brushing less than twice per day versus twice or more per day and the development of fluorosis (OR 1.63, 95% CI 0.81 to 3.28; very low-certainty evidence). Two cross-sectional surveys (1693 children) demonstrated that brushing less than once per day versus once or more per day may be associated with a decrease in the development of fluorosis in children (OR 0.62, 95% CI 0.53 to 0.74; low-certainty evidence). Comparison 3. Amount of fluoride toothpaste used for toothbrushing Two case-control studies (258 children) provided very uncertain evidence regarding the association between children using less than half a brush of toothpaste, versus half or more of the brush, and the development of fluorosis (OR 0.77, 95% CI 0.41 to 1.46; very low-certainty evidence). The evidence from cross-sectional surveys was also very uncertain (OR 0.92, 95% CI 0.66 to 1.28; 3 studies, 2037 children; very low-certainty evidence). Comparison 4. Fluoride concentration in toothpaste There was evidence from two RCTs (1968 children) that lower fluoride concentration in the toothpaste used by children under six years of age likely reduces the risk of developing fluorosis: 550 parts per million (ppm) fluoride versus 1000 ppm (RR 0.75, 95% CI 0.57 to 0.99; moderate-certainty evidence); 440 ppm fluoride versus 1450 ppm (RR 0.72, 95% CI 0.58 to 0.89; moderate-certainty evidence). The age at which the toothbrushing commenced was 24 months and 12 months, respectively. Two case-control studies (258 children) provided very uncertain evidence regarding the association between fluoride concentrations under 1000 ppm, versus concentrations of 1000 ppm or above, and the development of fluorosis (OR 0.89, 95% CI 0.52 to 1.52; very low-certainty evidence). Comparison 5. Age at which topical fluoride varnish was applied There was evidence from one RCT (123 children) that there may be little to no difference between a fluoride varnish application before four years, versus no application, and the development of fluorosis (RR 0.77, 95% CI 0.45 to 1.31; low-certainty evidence). There was low-certainty evidence from two cross-sectional surveys (982 children) that the application of topical fluoride varnish before four years of age may be associated with the development of fluorosis in children (OR 2.18, 95% CI 1.46 to 3.25). AUTHORS' CONCLUSIONS: Most evidence identified mild fluorosis as a potential adverse outcome of using topical fluoride at an early age. There is low- to very low-certainty and inconclusive evidence on the risk of having fluorosis in permanent teeth for: when a child starts receiving topical fluoride varnish application; toothbrushing with fluoride toothpaste; the amount of toothpaste used by the child; and the frequency of toothbrushing. Moderate-certainty evidence from RCTs showed that children who brushed with 1000 ppm or more fluoride toothpaste from one to two years of age until five to six years of age probably had an increased chance of developing dental fluorosis in permanent teeth. It is unethical to propose new RCTs to assess the development of dental fluorosis. However, future RCTs focusing on dental caries prevention could record children's exposure to topical fluoride sources in early life and evaluate the dental fluorosis in their permanent teeth as a long-term outcome. In the absence of these studies and methods, further research in this area will come from observational studies. Attention needs to be given to the choice of study design, bearing in mind that prospective controlled studies will be less susceptible to bias than retrospective and uncontrolled studies.

Use test with l-carvone in toothpaste on sensitized individuals.

BACKGROUND: The mint flavour carvone (l-carvone) is considered a weak contact allergen. However, contact allergy to carvone is more prevalent in patients with oral lichen planus or oral lichenoid lesions (OLP/OLL). OBJECTIVE: Our aim was to investigate how carvone affects sensitized individuals through a use test with toothpaste containing carvone. Non-flavoured toothpaste served as control. METHODS: Subjects were patch tested prior to the use test-14 subjects allergic to carvone (11 with OLP/OLL), 20 subjects with OLP/OLL and 3 healthy controls. The month-long use test comprised of using toothpaste twice daily. Subjects were examined fortnightly. Clinical signs were assessed with a mucosal scoring system. The subjects' oral health-related quality of life was measured with the oral health impact profile (OHIP-49). RESULTS: Local reactions to the carvone toothpaste presented as aggravated OLL (7/10) and peri-oral eczema (2/10) in allergic subjects. They also had significantly higher mucosal and OHIP scores compared with those receiving non-flavoured toothpaste. CONCLUSION: In sensitized individuals, oral exposure to carvone gives aggravated oral lesions and/or peri-oral eczema. The lesions mimic OLP and allergic individuals are therefore at risk of not being assessed with regard to flavour contact allergy.

Longterm abrasive and erosive effect of whitening toothpaste on dentin surface.

PURPOSE: To evaluate the amount of dentin loss following immersion in or toothbrushing with whitening toothpaste (WT) containing hydrogen peroxide (HP) and citric acid (CA). Additionally, the amount of dentin loss after brushing with a WT alone or in combination with a conventional toothpaste was assessed, and the effects of HP and CA solutions on the dentin surface were investigated. METHODS: Bovine dentin specimens (n= 350) were randomly assigned to seven solutions of various compositions as toothpaste: The specimens assigned to each solution were then further divided into five treatment groups (n=10 each) : Group A = 1-hour immersion in each solution (ES); Group B = 10,000 brushing in ES; Group C = 1-hour immersion in ES + 10,000 brushing in ES; Group D = 1-hour immersion in ES + 10,000 brushing in reference slurry (RS); Group E = 10,000 brushing in ES + 10,000 brushing in RS. The amount and pattern of dentin loss were determined, and the surfaces were observed using noncontact profilometry. RESULTS: The WT (pH 5.0) caused lower dentin loss than RS after a single brushing cycle; however, the extent of dentin loss after 1 hour of immersion in the WT was significantly greater than that in the RS. Among the specimens treated with WT, a significant difference in dentin loss was observed between Group C and Groups D and E (P< 0.05) but not between Groups D and E. The surfaces exposed to CAS1, CAPB, and WT exhibited U-shaped patterns of dentin loss after brushing or immersion, whereas a wedge-shaped pattern was observed in those that underwent brushing with the RS. CLINICAL SIGNIFICANCE: The effects (dentin abrasion) of a whitening toothpaste containing hydrogen peroxide and citric acid when used in combination with a conventional toothpaste were similar to those seen with the continuous use of a conventional toothpaste alone.

Effects of a commercial whitening toothpaste containing hydrogen peroxide and citric acid on dentin abrasion and erosion.

BACKGROUND: Hydrogen peroxide (HP) and citric acid (CA), key contributors to toothpaste acidity, can lead to dental loss. This study aimed to compare the amount of abrasion or loss of dentin based on pH, buffering, and concentration of HP and CA in commercial and experimental toothpastes after toothbrushing or immersion. METHODS: Bovine dentin specimens were randomly assigned to nine solutions. The prepared solutions included two commercial toothpastes (whitening toothpaste [WT] with HP and CA; conventional toothpaste [CT] without HP and CA), reference slurry (RS), two CA solutions (1.92%, CAS1; 0.001%, CAS2), basic solution (7.16% sodium phosphate dibasic [SPDS]), CA phosphate buffer solution (3.58% SPDS and 0.96% CA [CAPB]), HP solution (4%, HPS), and distilled water (DW). Dentin specimens were performed in two treatments: one with only abrasion (10,000 brushings) and one with only immersion (1 h). After treatments, the amount of dentin loss and surface images were measured and observed using noncontact profilometry. Data were analyzed using an one-way analysis of variance and the Tukey test as a post hoc analysis (p < 0.05). RESULTS: WT with pH 5.0 had lower dentin abrasion than CT and RS after brushing but had higher dentin loss than both after immersion. The dentin surfaces of CAS1, CAPB, and WT were damaged after immersion, whereas HPS, CAS2, CT, SPDS, RS, and DW remained intact after soaking. CAS2 and HPS, which had a pH of 5.0 like WT, did not significantly differ from those of DW after brushing. CONCLUSIONS: WT containing HP and CA did not cause significant dentin abrasion but may cause additional dentin loss even without brushing. After brushing or immersion, the CA concentration may affect the dentin surface more than the HP concentration included in WT. The amount of abrasion or loss of dentin after brushing or soaking can vary based on the composition, concentration, and buffer in the solution, even if the pH of the solution is similar to pH 5.0.

Relative dentin and enamel abrasivity of charcoal toothpastes.

OBJECTIVES: Very little data are known about charcoal toothpastes. The aim of this study was to counteract the missing data by determining the relative dentin abrasivity (RDA) and relative enamel abrasivity (REA) values of charcoal toothpastes. METHODS: Radioactively charged dentin and enamel samples were randomly divided into groups of eight specimens. Each group was brushed with two of total 12 charcoal toothpaste slurries and with a standard abrasive with a known RDA and REA value. The measured radioactivity in counts per minute within the slurries corresponds to the amount of dentin or enamel abraded. RDA and REA values of the charcoal toothpastes were expressed relative to the known value of the standard slurry. RESULTS: The RDA and REA values of the charcoal toothpastes have a broad range of 24-166 and 0-14, respectively. CONCLUSIONS: The RDA and REA values do not differ significantly from previously tested commercially available toothpastes. However, the lack of fluoride compounds in many of the investigated charcoal toothpastes can have a less beneficial effect for the consumers. It is very important to educate patients accordingly.

[Dental materials and oral care products that can cause contact allergies]. / Tandheelkundige materialen en mondverzorgingsproducten die contactallergieën kunnen geven.

Various restorative and prosthetic materials, dental implants, medicines and cosmetic materials, such as toothpaste and denture cleaning products, are used in oral care. In principle, these materials can cause contact allergies, which can manifest as lichenoid reaction, cheilitis and angioedema. It is usually a local reaction of the oral mucosa and surrounding tissues, but a systemic reaction can also occur elsewhere in the body. If a patient develops complaints from dental materials that could be due to an allergy, it makes sense to investigate this allergologically, although these do not yet show full specificity or sensitivity. After a positive allergological examination, it is possible to examine more specifically whether the patient's complaints match the test result and it can be decided whether it is sensible to replace the dental material and, if so, which material could be an alternative. After removal of the causative allergens, the complaints should disappear completely.

Side effects of sodium lauryl sulfate applied in toothpastes: A scoping review.

PURPOSE: To perform a scoping review on the available literature regarding the side effects of sodium lauryl sulfate (SLS) used in toothpastes. METHODS: A scoping review was performed according to the PRISMA extension using PubMed. The electronic search was supplemented with a manual search for a complete overview. A customized data collection form was used to map data which was developed to register the extracted relevant data. The results of the selected articles were classified according to effects in the mouth, on the mucous membrane or elsewhere in the body and the healing effects of SLS-free toothpaste on aphthous ulcers. The outcomes from each category were reported in separate data forms and the studies with incomplete information were excluded from the assessment. RESULTS: Possible harmful effects of SLS were reported as mucosal desquamation, irritation or inflammation of oral mucosa or the dorsal part of the tongue, ulcerations, and toxic reactions in the oral cavity. CLINICAL SIGNIFICANCE: There is limited evidence that patients with recurrent aphthous ulcers can benefit from the use of SLS-free toothpastes in terms of decrease in the number of ulcerations, duration of the ulcerations and the intensity of the pain caused by the ulcerations. It is essential to create awareness for the side effects of SLS in toothpastes but further research is needed on its effect on oral and gastrointestinal systems when used in toothpastes.

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.

Biomarkers for the Assessment of Exposure to Fluoride in Adults.

To monitor deficient or excessive intakes of biologically available fluoride (F), various biological samples have been tested for use as biomarkers of human exposure to F. Most such studies have concerned children and often have only involved measurement of F in 1 or 2 types of sample. The present study investigated the relationships of F concentrations in biomarkers of F exposure; including plasma, saliva, hair, finger- and toenails, and daily urinary F excretion (UFE) with the total daily F intake (TDFI) of adults. TDFI was assessed in 60 healthy adults, aged ≥20 years; 31 lived in a low-F water area (LFA, 0.04 mg F/L) and 29 in a high-F water area (HFA, 3.05 mg F/L) of Nigeria. All volunteers provided at least 1 biomarker sample from the above list and completed a questionnaire to evaluate F intake from the diet and toothpaste ingestion. TDFI, UFE and F concentrations of biomarkers were statistically significantly higher in the HFA than in the LFA. There were strong statistically significant positive correlations between TDFI and UFE (ρ = 0.730, p < 0.001); plasma F (ρ = 0.729, p < 0.001); fasting whole saliva F (ρ = 0.653, p < 0.001) and hair F (ρ = 0.603, p < 0.001). The statistically significant positive correlations between TDFI and fingernail F (ρ = 0.502, p < 0.001) and between TDFI and toenail F (ρ = 0.556, p < 0.001) were moderate. In conclusion, this study has indicated the usefulness of 24-h UFE as well as F concentration in plasma, fasting whole saliva and hair as biomarkers of contemporary or sub-chronic F exposure in groups of adults. However, they do not appear to have the necessary sensitivity to predict F exposure in individuals.

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.

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.

Awareness of the Benefits and Risks Related to Using Fluoridated Toothpaste Among Doctors: A Population-Based Study.

BACKGROUND This study aimed to assess the awareness of dentists and non-dental doctors regarding the benefits and risks of using fluoridated toothpaste. MATERIAL AND METHODS A self-administered questionnaire was used to collect information in this study. Multistage cluster sampling method was used to enroll doctors in 5 districts or counties in Chongqing, China. A total of 403 doctors (160 dentists and 243 non-dental doctors) completed the questionnaire. RESULTS The awareness of the anti-caries efficacy and the usage of fluoridated toothpaste in dentists was significantly higher than those of non-dental doctors (P<0.001). Most (about 60%) dentists and non-dental doctors had concerns about fluoridated toothpaste. Only 31.3% of dentists and 25.9% of non-dental doctors had a good understanding of the benefits and risks of use of fluoridated toothpaste in children under 3 years of age to 49.4% of dentists and 73.3% of non-dental doctors did not understand the benefits and risks in children 3~6 years old, and 40.0% of dentists and 67.5% of non-dental doctors did not understand the risks and benefits in individuals living in high-fluoride areas. Most dentists (76.3%) and non-dental doctors (87.3%) did not understand the benefits and risks in pregnant women. CONCLUSIONS Dentists and non-dental doctors were concerned about the potential risks of use of fluoridated toothpaste, and they lacked adequate knowledge about the benefits and risks of use of fluoridated toothpaste. Health education is needed to improve doctors' knowledge about use of fluoridated toothpaste.

In vivo evaluation of fluoride and sodium lauryl sulphate in toothpaste on buccal epithelial cells toxicity.

OBJECTIVES: The present study addresses the effect of fluoride and sodium lauryl sulphate content of toothpaste on oral epithelial cells in vivo conditions. SUBJECTS AND METHOD: Forty volunteers were assigned into two experimental groups, each of them applying the different brand of toothpaste. Every group has been using three different types of toothpaste (non-fluoride and non-SLS, fluoride and non-SLS, and the fluoride and SLS) of the same brand for 6 months, each for 2 months. The buccal epithelial cells were sampled at baseline and 30, 60, 90, 120, 150 and 180 days after the beginning of the research. Effect on DNA damage was analyzed by micronucleus assay Results: After 60 days of use, for both tested kinds of toothpaste with fluoride and without SLS, all studied parameters were not significantly different from the results obtained at the time when the participants used a non-fluoride toothpaste. While, after 60 days of use, for one kind of toothpaste with SLS and fluoride, was observed significantly higher incidence of pyknotic cells (2.20 ± 0.95, 0.00 ± 0.00 vs. 0.05 ± 0.22, respectively; p = .001), cells with karyorrhexis (2.35 ± 1.14, 0.85 ± 0.93 vs. 0.40 ± 0.68, respectively; p = .001), and nuclear buds (1.35 ± 0.68, 0.45 ± 0.51 vs. 0.45 ± 0.60, respectively; p = .001), compared to toothpastes of the same brand with fluoride and without SLS, and without fluoride and without SLS, for the same period. CONCLUSIONS: Based on the results, can be concluded that there is no fluorine-dependent cytotoxic or genotoxic effect, while SLS dentifrice increases the number of nuclear morphological changes in buccal epithelial cells.

Opinion of the Scientific Committee on Consumer safety (SCCS) - Final opinion on water-soluble zinc salts used in oral hygiene products.

The SCCS has estimated that exposure to water-soluble zinc salts via toothpaste and mouthwash at the concentrations of 1 and 0.1%, respectively, may lead to a daily intake level of 3.54 mg for adults and children aged 6-17 years. This exposure constitutes between 14 and 35% of the Upper Limit (UL) for these age groups. Therefore, the SCCS considers that the use of zinc in toothpaste and mouthwash per se is safe for adults and children aged 6-17 years. The SCCS has estimated that exposure to water-soluble zinc salts via toothpaste at the concentrations of 1% may lead to a daily intake level of 1.0-2.00 mg for children aged 0.5-5 years. This exposure constitutes between 10 and 29% of the UL for this age group. Therefore, the SCCS considers that the use of zinc in toothpaste per se is safe for children aged 0.5-5 years. Exposure to zinc may also occur from sources other than oral hygiene products. An important source of zinc in the population is the diet. This assessment has not taken into account the daily dietary intake of zinc. The dietary zinc intake (estimated by EFSA in 2014) ranges from 6.8 to 14.5 mg/day in adolescents aged 10 to < 18 years, from 5.5 to 9.3 mg/day in children aged 3 to < 10 years and from 4.6 to 6.2 mg/day in children aged 1 to <3 years. Therefore, exposure to zinc via the diet may already exceed or be close to exceeding the upper limits of 18, 13, 10 and 7 mg/day for the age groups 11-14, 7-10, 3-7 and 1-3 years, respectively. Any additional source of exposure, including cosmetics, may lead to exceeding the upper limits for children. The SCCS cannot advise which portion of the upper limit should be allocated to exposure from cosmetic products. When assessing exposure to chemicals, allocation factors that reflect a reasonable level of exposure while still being protective may be applied. For exposure via toys or drinking water, for example, allocation factors of 10% or 20% of the reference value may be considered as safe. In the case of zinc, the use of 1% in toothpaste and 0.1% in mouthwash constitutes between 10 and 35% of the upper limit depending on the age group. The SCCS is aware that upper limits may be exceeded in some cases because the default values used in this Opinion are based on conservative estimates.

Assessment of cytotoxic and genotoxic effects of conventional and whitening kinds of toothpaste on oral mucosa cells.

OBJECTIVE: This study aimed to evaluate possible DNA damages to oral epithelial cells exposed to whitening kinds of toothpaste considering the effect of conventional non-whitening toothpaste. MATERIALS AND METHODS: Sixty volunteers were assigned into three experimental groups, each of them using a different regular toothpaste for the initial 2 months, followed by the use of whitening kind of toothpaste of the same brand for next 2 months. The oral epithelial cells were sampled prior and 30, 60, 90 and 120 days after the beginning of the use of tested kinds of toothpaste. Chromosomal damages were analyzed by micronucleus assay. RESULTS: For just one kind of tested whitening toothpaste was observed the significant increase in the number of micronucleated cells after 60 days of use compared values obtained 60 days of usage of conventional non-whitening toothpaste (6.35 ± 3.67 and 2.8 ± 1.91; p < .05). There was no statistically significant difference in other micronucleus assay endpoints between tested types of toothpaste at either of the sampling times during the period of toothpaste application. CONCLUSIONS: Based on the results, it can be concluded that the use of certain whitening kinds of toothpaste may cause a limited biologically insignificant genotoxic effect on buccal epithelial cells.

Quantification of l-carvone in toothpastes available on the Swedish market.

BACKGROUND: Toothpastes have widespread use in the population, and contain flavours to give a pleasant and often minty aroma. Flavours are prevalent allergens in toothpastes, and adverse reactions often present as perioral dermatitis or stomatitis. l-Carvone, a mint flavour found in spearmint oil, is one of these allergens. There are few studies on contact allergy to l-carvone, and some of them have indicated a positive relationship with oral lichenoid lesions. OBJECTIVES: To qualitatively and quantitatively investigate the presence of l-carvone in commercially available toothpastes on the Swedish market. METHODS: l-Carvone in 66 toothpastes was analysed with straight-phase high-performance liquid chromatography. The product labels were studied with regard to limonene. RESULTS: l-Carvone was found in 64 of 66 toothpastes (concentration: 0.00005-0.35%). In 10 of these, the concentration exceeded 0.1%. Higher concentrations of l-carvone were found if limonene was listed on the label. CONCLUSION: The majority of toothpastes on the Swedish market contain l-carvone, but the concentration hardly relates to the advertised flavour or labelled ingredients. It is hitherto unknown whether the found concentrations are sufficient for induction of contact allergy in individuals with healthy oral mucosa or in those with oral lichenoid lesions or other mucosal disease.

The abrasive effect of commercial whitening toothpastes on eroded enamel.

PURPOSE: To evaluate the in vitro abrasive effect of commercial whitening toothpastes on eroded bovine enamel samples in respect to erosive tooth wear. METHODS: 72 bovine crowns were embedded, polished and subjected to the baseline profile analysis. The samples were then protected in 2/3 of the enamel surface and were randomly assigned to six groups (n= 12/group): G1: Oral-B 3D White, G2: Close-up Diamond Attraction Power White, G3: Sorriso Xtreme White 4D, G4: Colgate Luminous White, G5: Crest (conventional toothpaste), G6:erosion only (control). All samples were submitted to an erosive pH cycling (4 x 90 seconds in 0.1% citric acid, pH 2.5, per day) and abrasive challenges (2 x 15 seconds, per day) for 7 days. After the first and the last daily cycles, the samples were subjected to abrasive challenges, using a toothbrushing machine, soft toothbrushes and slurry of the tested toothpastes (1.5 N). Between the challenges, the samples were immersed in artificial saliva. The final profile was obtained and overlaid to the baseline profile for the calculation of the erosive tooth wear (µm). The data were subjected to Kruskal-Wallis/Dunn tests (P< 0.05). RESULTS: G1 promoted the highest enamel wear (3.68±1.06 µm), similarly to G3 (3.17± 0.80 µm) and G4 (3.44± 1.29 µm). G3 and G4 performed similarly between them and compared with G5 (2.35± 1.44 µm). G2 (1.51± 0.95 µm) and G6 (0.85± 0.36 µm) showed the lowest enamel wear, which did not differ between them and from G5. Oral-B 3D White showed the highest abrasive potential while Close-up Diamond Attraction Power White showed the lowest abrasive potential on eroded enamel in vitro. CLINICAL SIGNIFICANCE: This study showed that some commercial whitening toothpastes, especially those containing pyrophosphate associated with hydrated silica, enhanced enamel erosive wear.

Protocol for measurement of enamel loss from brushing with an anti-erosive toothpaste after an acidic episode.

Tooth erosion from an acidic insult may be exacerbated by toothbrushing. The purposes of this study were to develop an in vitro methodology to measure enamel loss after brushing immediately following an acidic episode and to investigate the effect of brushing with an anti-erosive toothpaste. The null hypotheses tested were that tooth erosion after brushing with the toothpaste would not be different from brushing with water and that a 1-hour delay before brushing would not reduce tooth erosion. Forty bovine enamel slabs were embedded, polished, and subjected to baseline profilometry. Specimens were bathed in hydrochloric acid for 10 minutes to simulate stomach acid exposure before post-acid profilometry. Toothbrushing was then simulated with a cross-brushing machine and followed by postbrushing profilometry. Group 1 was brushed with water; group 2 was brushed with a 50:50 toothpaste-water slurry; and groups 3 and 4 were immersed in artificial saliva for 1 hour before brushing with water or the toothpaste slurry, respectively. The depth of enamel loss was analyzed and compared using 1-way analysis of variance and post hoc testing (α = 0.05). Greater enamel loss was measured in groups brushed with toothpaste than in groups brushed with water. One-hour immersion in artificial saliva significantly reduced enamel loss when teeth were brushed with water (group 3; P < 0.05) but not with toothpaste (group 4). This study established a protocol for measuring enamel loss resulting from erosion followed by toothbrush abrasion. The results confirmed the abrasive action of toothpaste on acid-softened enamel.

Relationship between toothpastes properties and patient-reported discomfort: crossover study.

OBJECTIVES: This study aims to correlate patient-reported reactions with in vitro analyses of the pH, abrasive quality, and cytotoxicity of four toothpastes. MATERIALS AND METHODS: One hundred twenty-one patients received non-identified samples of toothpaste to be used for 6 days and answered a questionnaire about their sensations. In vitro analysis: the pH of toothpastes was measured with a pH meter. The abrasivity of toothpastes was evaluated against composite resin specimens (n = 10). A toothbrushing machine was used to simulate wear, which was indirectly measured by mass loss using a scale. Cell culture media conditioned with toothpaste were used to assess the cytotoxicity. Confluent cells were kept in contact with the conditioned media or control for 24 h. The cell viability was measured using the 3-(bromide, 4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium (MTT)-reduction assay. The obtained data on the pH, weight loss, and cell viability were compared by ANOVA/Tukey's tests (p < 0.05). RESULTS: With the exception of the bleaching effect paste, the Oral B® paste produced the highest frequencies of irritation reports, tooth sensitivity, taste discomfort, and texture discomfort in the clinical study; patients also reported rougher teeth, soft tissue peeling, dry mouth, thrush, tingling, and taste changes in response to this paste. The in vitro analysis demonstrated that Oral B® had the lowest pH, the highest abrasivity, and produced the lowest cell viability (p < 0.01). CONCLUSION: Results suggest that low pH toothpastes that are highly abrasive and cytotoxic may cause undesirable reactions in patients. CLINICAL RELEVANCE: Toothpaste's properties should be well known for indication to patient therefore minimizing discomfort reports.

[Durability of protective effect of resin-based coating material on root surface].

OBJECTIVE: To compare the durability of resin-based root-surface coating material and all-in-one self-etching adhesive on root surface in vitro. METHODS: Human extracted premolars or molars with intact roots were selected. The cementum was removed using a periodontal scaler to expose root dentin. The root surface was coated with an acid-resistant nail varnish, leaving a window of 3 mm×3 mm on the exposed dentin.The window was covered with either PRG Barrier Coat (PRG) or Clearfil S3 Bond (CS3). After water aging for 14 d, specimens were immersed in acid buffer at pH 4.5 for 4 d and the demineralization buffer was changed every 24 h. Then the specimen was split longitudinally through the center of the 'window' and the cross-sectional surface was observed with scanning electron microscope (SEM). After fixed and dehydrated, the prepared samples were coated with platinum. The coating material, root dentin and the interface was observed by scanning electron microscope (SEM). The thickness of the coating material was measured on the SEM images. Regarding toothbrush wear test, coronal dentindisks were prepared and covered with PRG and CS3, respectively. After storage in water for 24 h, the specimen was subjected to the toothbrush wear tester for 100, 200, 300, 500, 700, 1 500 brushing cycles. A slurry of fluoride toothpaste (1:2 ratio of toothpaste and deionized water by weight) was used and the brushing load was 300 N. The surface microstructure of remaining coating material was analyzed using SEM. The wear depths were determined by a profilometer. Statistical analysis was performed with SPSS 20.0 by one-way ANOVA. The level of significance was at 0.05. RESULTS: Application of PRG Barrier Coat produced a coating layer of (47.1±27.3) µm, while CS3 presented a thin film of (5.7±2.1) µm in thickness. The exposed dentin was hermetically sealed and no obvious gap was observed at the interface in both PRG and CS3 groups. There was no dentin demineralization observed in both groups after water aging. The wear depths of PRG and CS3 increased along with the numbers of brushing cycles. PRG wore at a significant lower pace than CS3 did (P<0.05). CONCLUSION: PRG coating resin had similar performances as CS3 on protecting root dentin from demineralization after water aging. What's more, PRG demonstrated a higher toothbrush wear resistance than CS3. We concluded that PRG Barrier Coat contained S-PRG filler may be an effective coating material for protecting exposed root from both chemical and mechanical challenges. Further studies should be carried out to evaluate the long-term reliability of the rootsurface coating materials under the clinical setting.