Root caries, root surface restorations and lifestyle factors in adult Danes

Predictors of survival of large non-occlusal non-incisal glass-ionomer restorations in older adults

PURPOSE

This study aimed to investigate the predictors of survival of non-occlusal non-incisal glass-ionomer restorations as a surrogate for root surface restorations among older adults.

METHODS

In a retrospective cohort analysis using the University of Iowa College of Dentistry electronic dental records, we included 721 patients aged 65+ who received 2+ surface non-occlusal non-incisal glass ionomer restorations placed from January 2005 - December 2011. Restorations were followed until September 2017 or until they were deemed to have failed.

RESULTS

At baseline, participants' mean age was 77.6 ± 8.2 years, and 45.8% were females. Most patients were self-pay (65.2%). Most restorations were placed by residents and dental students (82.7%) and included only two surfaces (95.6%). About half (49.1%) failed during follow-up, with a median survival time of 3.7 years. The time ratio for lower incisors compared to other teeth was 0.6 (p = .006), for three-and-four-surface restorations compared to two was 0.7 (p = .007), for faculty as providers compared to residents and students was 1.4 (p = .039), and for the Geriatric & Special Needs Clinic compared to others was 0.8 (p = .013). Time ratios less than one indicate association with shorter durations for restorations, and time ratios greater than one indicate association with longer durations for restorations.

CONCLUSION

Tooth type, number of restored surfaces, provider type, and clinic were all significant factors associated with survival of these restorations.

Prevalence of root caries in Indian population - a systematic review and meta-analysis

AIM

To evaluate the pooled prevalence of root caries among Indian population through systematic review and meta-analysis.

MATERIALS AND METHODS

The study protocol adhered to the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines and was registered in PROSPERO (CRD42022367365). Research articles published in English language till July 2022 were evaluated with the use of databases like PubMed, Science Direct, Google Scholar, Cochrane, and Scopus and employed standard Boolean operators.

RESULTS

The search turned up a total of 194 articles; however, only 14 of those matched the requirements for inclusion and were used to compile the meta-analysis. MedCalc® Statistical Software version 20.2 was used to determine the pooled estimates. Using the random effect model, the analysis was carried out. By estimating the heterogeneity using Higgins' I2 statistics, the extent and importance of differences between the chosen studies were ascertained. Publication bias was assessed using the funnel plot and Egger's test. The random effects model yielded a pooled prevalence of 27.617 (95% CI = 17.422-39.154).

CONCLUSION

Three out of ten persons in India may be affected by root caries, which is a serious health issue. To enhance the quality of life for the aged population, oral health policies and preventive actions should concentrate on this issue.

The prevalence and common risk indicators of root caries and oral health service utilization pattern among adults, a cross-sectional study

Background

Root caries is a prevalent oral health concern among adults, yet there remains a need for a comprehensive understanding of its occurrence and associated risk indicators. The present study was aimed to investigate the prevalence of root caries and to determine significantly associated indicators with it among adults.

Methods

The residents aged 35-74 years old were enrolled in a cross-sectional study in which dental examination were taken and structured questionnaires were collected in Zhejiang Province, China. All data were recorded in an electronic system and analyzed.

Results

The prevalence of decayed and filled root caries in 1,076 respondents was 31.9%. Elder age, greater attachment loss, and exposed root surface were associated with higher odds of incidence for decayed/filled roots and decayed roots. In the last 12 months, 27.4% of adults with decayed or filled roots and 23.2% of others utilized oral health services. Carious adults who had a very poor/poor oral health status were 2.905 times likely to report dental visits. People with sound roots who were female (OR = 2.103, P < 0.001), perceived their oral health status as moderate (OR = 1.802, P = 0.015), or poor/very poor (OR = 4.103, P < 0.001) were more likely to visit a dentist in the past 12 months.

Conclusions

Age, attachment loss and root exposure were most significantly associated with the prevalence of root caries. Individuals who recognize their poor or very poor oral health status should feel encouraged to make use of oral health services.

Systematic Review of the Effect on Caries of Sugars Intake: Ten-Year Update

An update of the systematic review of evidence on the association between amount of sugars intake and dental caries, as well as on the effect of restricting sugars intake to <10% and <5% energy (E) on caries, was conducted, almost 10 y since the review that informed the World Health Organization (WHO) Guideline on Sugars. The aim was to systematically review epidemiological data published from 2011 to 2020 on the amount of sugars consumption and levels of caries and to report the findings for adults and children. Data sources included MEDLINE, EMBASE, Cochrane Database, Cochrane Central Register of Controlled Trials, Latin American and Caribbean Health Sciences, China National Knowledge Infrastructure, Scopus, and Google Scholar. Eligible studies reported the amount of sugars and caries, measured as prevalence, incidence, or severity. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Risk of bias was assessed using the Office of Health Assessment and Translation tool. Vote counting and harvest plots provided the basis for evidence synthesis. From 488 new papers identified, 23 studies were eligible: 4 cohort, 1 case-controlled, 12 cross-sectional, and 6 ecological. Eleven of 15 studies in children and 6 of 8 studies in adults reported at least 1 positive association between sugars and caries. Six of 7 studies in children and 4 of 4 studies in adults, with data enabling comparison of caries levels with sugars intakes >10%E and <10%E, showed lower caries when sugars intake was <10%E. Amalgamating with original studies yielded 64 of 78 studies showing at least 1 positive association, 20 of 78 a null association, and 3 of 78 a negative association between sugars and caries. GRADE profiles of new and original cohort data confirmed "moderate-quality" evidence that caries is lower when sugars intake is <10%E. Furthermore, new cohort data upgraded the quality of evidence (from "very low" to "low") for lower caries when free sugars are <5%E. The findings support and strengthen original evidence underpinning the WHO recommendations for sugars.

Relationship between Chinese Baijiu consumption and dental caries among 55- to 74-year-old adults in Guangdong, southern China: a cross-sectional survey

Background

Whether an association between alcohol consumption and dental caries exists is still unclear. Chinese Baijiu is the most common alcohol consumed by middle-aged and elderly Chinese individuals. This study aimed to assess the relationship between alcohol consumption (Chinese Baijiu) and dental caries in Guangdong Province, southern China.

Methods

A cross-sectional study was conducted in Guangdong Province using a multistage, stratified, equal-sized, random sampling strategy. In total, 576 individuals aged 55–74 were recruited to fill out a questionnaire through face-to-face and one-on-one interviews and to undergo a series of dental examinations with a Community Periodontal Index (CPI) probe. According to the standard for clinical dentition examination of the WHO 2013 criteria, the presence of dental caries was determined by the DFT/DFRoot (decayed-filled tooth/root) index. The ratios of males to females and urban people to countrymen were both 1:1. Then, the chi-square test and rank-sum tests were used to compare the differences in caries between subgroups, and multivariate logistic regression analyses, as well as negative binomial regression analyses, were executed to identify the potential relationship between alcohol consumption and caries.

Results

The prevalence of crown caries was 79.17% with a DFT index of 3.19, while that of root caries was 61.28% with a DFRoot index of 2.08. The prevalence and mean tooth of crown caries of females were higher than those of males. The prevalence and mean DFRoot of root caries in rural areas were higher than those in urban areas. The results of the multivariate logistic regression analysis and negative binomial regression analysis showed that there was a statistically significant negative correlation between the consumption frequency of Chinese Baijiu and caries (often vs. never/rarely, crown caries: odds ratio (OR) = 0.54, 95% confidence interval (CI): 0.26–1.13, P = 0.103, incidence rate ratio (IRR) = 0.63, 95% CI: 0.44–0.92, P = 0.015; root caries: OR = 0.47, 95% CI: 0.24–0.93, P = 0.030, IRR = 0.52, 95% CI: 0.32–0.54, P = 0.008).

Conclusions

Within the limitations of this study, frequent consumption of Chinese Baijiu was a protective factor for caries in middle-aged and elderly people in Guangdong Province. However, considering the harm of alcohol to one’s general health, it is recommended to drink moderately and avoid alcohol abuse.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02453-x.

Association between root/coronal caries and individual factors in institutionalised elderly using ICDAS severity and activity

Background

Caries in the elderly has been associated with dependence, oral-health status and -care practices. This cross-sectional study aimed to investigate the association between root/coronal caries and individual factors among institutionalised elderly people in Bogotá, Colombia, using the International Caries Detection and Assessment System severity and activity criteria (ICDAS).

Methods

A total of 226 institutionalised elderly were clinically examined for root and coronal caries in 40 institutions. Caries risk was assessed with Cariogram, and demographics, oral health knowledge and practices, oral health-related quality of life and denture-use habits using a questionnaire.

Results

Participants (mean age: 80.1 ± 9.3 years; 63.7% female) presented a mean number of 10.8 ± 7.3 teeth and 19.4 ± 18.8 exposed root surfaces. Prevalence of Coronal-ICDAS caries experience (C-ICDAS DF) was of 100% and of 54.4% for C-ICDAS D; mean number of C-ICDAS DFS was 16.76 ± 27.36, with 50.9% of subjects having ≥ one active C-ICDAS DS. Prevalence of Root Caries Index was of 49.1% and of R-ICDAS DF of 46%; mean number of R-ICDAS DFS was 2.03 ± 2.78, with 40.3% of subjects having ≥ one active R-ICDAS DS. Most individuals had a systemic condition (94.2%) and required oral-hygiene assistance (58%). Logistic regression analyses showed significant associations (p < 0.05): for coronal active caries when having over six teeth (OR: 2.7), and for root caries, when having coronal caries (OR: 2.41), being a man (OR: 1.95), and having over 14 teeth (OR: 0.30). Those presenting with > eight exposed root surfaces were 4.04 more likely to have root caries and 2.4 times more likely to have active root caries.

Conclusion

In the institutionalised elderly population in Bogotá significant associations were found, both for the presence as for the activity status of root and coronal caries, with individual clinical factors including coronal caries, exposed root surfaces and number of teeth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01520-4.

Tests to detect and inform the diagnosis of root caries

BACKGROUND

Root caries is a well-recognised disease, with increasing prevalence as populations age and retain more of their natural teeth into later life. Like coronal caries, root caries can be associated with pain, discomfort, tooth loss, and contribute significantly to poorer oral health-related quality of life in the elderly. Supplementing the visual-tactile examination could prove beneficial in improving the accuracy of early detection and diagnosis. The detection of root caries lesions at an early stage in the disease continuum can inform diagnosis and lead to targeted preventive therapies and lesion arrest.

OBJECTIVES

To assess the diagnostic test accuracy of index tests for the detection and diagnosis of root caries in adults, used alone or in combination with other tests.

SEARCH METHODS

Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 31 December 2018); Embase Ovid (1980 to 31 December 2018); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 31 December 2018); and the World Health Organization International Clinical Trials Registry Platform (to 31 December 2018). We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

We included diagnostic accuracy study designs that compared one or more index tests (laser fluorescence, radiographs, visual examination, electronic caries monitor (ECM), transillumination), either independently or in combination, with a reference standard. This included prospective studies that evaluated the diagnostic accuracy of single index tests and studies that directly compared two or more index tests. In vitro and in vivo studies were eligible for inclusion but studies that artificially created carious lesions were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and in duplicate using a standardised data extraction and quality assessment form based on the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) specific to the review context. Estimates of diagnostic test accuracy were expressed as sensitivity and specificity with 95% confidence intervals (CI) for each dataset. We planned to use hierarchical models for data synthesis and explore potential sources of heterogeneity through meta-regression.

MAIN RESULTS

Four cross-sectional diagnostic test accuracy studies providing eight datasets with data from 4997 root surfaces were analysed. Two in vitro studies evaluated secondary root caries lesions on extracted teeth and two in vivo studies evaluated primary root caries lesions within the oral cavity. Four studies evaluated laser fluorescence and reported estimates of sensitivity ranging from 0.50 to 0.81 and specificity ranging from 0.40 to 0.80. Two studies evaluated radiographs and reported estimates of sensitivity ranging from 0.40 to 0.63 and specificity ranging from 0.31 to 0.80. One study evaluated visual examination and reported sensitivity of 0.75 (95% CI 0.48 to 0.93) and specificity of 0.38 (95% CI 0.14 to 0.68). One study evaluated the accuracy of radiograph and visual examination in combination and reported sensitivity of 0.81 (95% CI 0.54 to 0.96) and specificity of 0.54 (95% CI 0.25 to 0.81). Given the small number of studies and important differences in the clinical and methodological characteristics of the studies we were unable to pool the results. Consequently, we were unable to formally evaluate the comparative accuracy of the different tests considered in this review. Using QUADAS-2 we judged all four studies to be at overall high risk of bias, but only two to have applicability concerns (patient selection domain). Reasons included bias in the selection process, use of post hoc (data driven) positivity thresholds, use of an imperfect reference standard, and use of extracted teeth. We downgraded the certainty of the evidence due to study limitations and serious imprecision of the results (downgraded two levels), and judged the certainty of the evidence to be very low.

AUTHORS' CONCLUSIONS

Visual-tactile examination is the mainstay of root caries detection and diagnosis; however, due to the paucity of the evidence base and the very low certainty of the evidence we were unable to determine the additional benefit of adjunctive diagnostic tests for the detection and diagnosis of root caries.

Dietary patterns associated with dental caries in adults in the United States

OBJECTIVES

Dental caries experience, which affects 91% of US adults, is a consequence of a carious process influenced by diet. Although individual foods have been implicated, we hypothesized that dietary patterns might be important predictors of caries presence.

METHODS

We analysed data from 4467 people ≥18 years old participating in the 2013-2014 National Health and Nutrition Examination Survey, a nationally representative sample of the US population. Data from 24-hour dietary recalls were classified into standard food categories and reduced to three dietary patterns using principal components (PCs) analysis. We used regression to model the log-transformed decayed, missing and filled teeth (DMFT) score and the prevalence of any caries experience by quartiles of PC scores, controlling for potential confounders. Dietary patterns differed by age with respect to dental caries so 18-30-year-olds (n = 1074) and >30-year-olds (n = 3393) were analysed separately.

RESULTS

Similar dietary patterns existed among individuals aged 18-30 and >30 years, but the prevalence of DMFT score >0 and the median of DMFT was greater in those >30:78.7% (95% CI: 76.1, 81.3) vs 92.6% (95% CI: 91.4, 93.7) and 4 (95% CI: 4, 5) vs 12 DMFT (95% CI: 11, 13), respectively. In those 18-30, no dietary pattern was associated with greater prevalence or severity of dental caries experience. Among those >30, the prevalence of DMFT>0 was higher by 2% for those in each subsequent quartile of a diet high in sugar-sweetened beverages and sandwiches (adjusted PR: 1.02, 95% CI: 1.001, 1.03)-thus, the prevalence of dental caries experience was 6% higher among those in the uppermost quartile than in the lowest quartile. For every subsequent quartile in the same pattern, there was a 1.98% higher (95% CI: 0.15, 3.85) DMFT score. However, analysis using the two strongest loading food groups from any of the PCs did not identify any predictors of caries experience.

CONCLUSIONS

Dietary patterns were associated with the prevalence of dental caries experience, with differing findings by age. Although effect sizes were small, the population impact may be substantial. While food groups high in sugar were associated with caries prevalence and severity, associations were more apparent in the context of overall diet. Prospective studies are needed to confirm whether particular dietary patterns are causally related to the development of dental caries.

Factors associated with development of root caries in dentition without root caries experience in a 2-year cohort study in Japan

OBJECTIVES

To investigate factors associated with the development of root caries in dentition without root caries experience and interactive relationships between risk factors.

METHODS

We conducted surveys, consisting of an oral examination (oral hygiene, assessment of the number of teeth, coronal and root caries) and a self-reported questionnaire, among employees of a company in Tokyo, Japan in 2016 and 2018. Questionnaires collected data on smoking status, oral hygiene habits, sugar intake, and frequency of dental visits. Multiple logistic regression and decision tree analyses were used to determine factors associated with the development of root caries.

RESULTS

A total of 299 participants aged 25-63 years were included in the analysis. Males, older adults, smokers/past smokers had a significantly greater risk of developing root caries. The risk of developing root caries was significantly associated with the number of teeth with gingival recession at baseline (6-9 teeth, odds ratio [OR]: 7.69, 95 % confidence interval [CI]: 2.31-25.56; 10+ teeth, OR: 9.19, 95 % CI: 2.73-30.95, relative to ≤5 teeth); and with the number of coronal decayed and filled (DF) teeth (11-13 teeth, OR: 3.21, 95 % CI: 1.12-9.24; and ≥14 teeth, OR: 3.60, 95 % CI: 1.27-10.20, relative to ≤10 teeth). Other factors associated with root caries development differed according to the number of teeth with gingival recession and included drinking sugar-sweetened beverages, and the amount of toothpaste used.

CONCLUSIONS

Gingival recession and number of coronal DF teeth were associated with the development of root caries.

CLINICAL SIGNIFICANCE

Multiple factors are associated with root caries development. The effect of risk factors such as drinking sweetened beverages and less toothpaste use is greater in individuals with greater gingival recession and more coronal decayed and filled teeth. Dental practitioners should focus on modifiable risk factors to prevent root caries.

Global and regional estimates of the prevalence of root caries - Systematic review and meta-analysis

Aim

To evaluate the pooled prevalence of root caries through a systematic review and meta-analysis.

Methods

A keyword search was done in Scopus, Pubmed and CINAHL databases using all the synonyms of root caries in the published literature (till January 1st, 2018). The search was supplemented with standard Boolean operators and other keywords like prevalence, epidemiology in the title, abstract and MeSH terms. Data was extracted and exported to Covidence software for screening and removal of duplicates.

Results

The search revealed a total of 492 documents from Scopus (n = 95), Pubmed (n = 220) and CINAHL (n = 177). Random effects model was used as there was a high degree of heterogeneity was seen among the studies published (I² = 99.62%). A total of 74 publications were included in the analysis of the pooled prevalence of root caries which yielded a prevalence of 41.5 (36.9–46.1).

Conclusion

Root caries is a significant problem, and four out of ten adults might be affected.

Root caries analysis in working population of 35-44 years of age (Spain)

Background

The aim of this study was to analyse the influence of socio-demographic variables, toothbrushing frequency, frequency of snacking between meals, and tobacco and alcohol consumption, in root caries in the Spanish working population of Valencia and Murcia regions.

Material and Methods

Cross sectional study of 458 workers 35-44 years of age, who underwent a routine work-related check-up, from June 2009 to April 2010, and were also examined, following the WHO methodology, by a calibrated dentist. Stratified random sampling. Participants fulfilled a questionnaire comprising demographic data, toothbrushing frequency, snacking frequency and tobacco and alcohol consumption.

Results

The DFS index (root caries) in the employed population of 35-44 years was 0.45 ± 1.3, with a root caries prevalence of 18.6% and an active root caries prevalence of 13.5%. Higher root caries prevalence and active root caries prevalence were associated with male gender, manual occupations, foreign country of origin, lower levels of education and income, lower brushing frequency and higher frequency of snacking between meals. The DFS index was associated with all studied socio-demographic variables, but gender, and it was also associated with brushing frequency. The mean number of root decayed teeth was associated with all socio-demographic variables, but country of origin, and it was also associated with brushing frequency.

Conclusions

Adult workers 35-44 years of age showed worse root condition in regard to caries than general population of this age cohort. In this study, the frequency of toothbrushing and snacking between meals were the variables that influenced more in root caries.

Key words:Root caries, working population, epidemiological studies, toothbrushing, snacking.

Toxicological impact of waterpipe smoking and flavorings in the oral cavity and respiratory system

Waterpipe smoking (WS), an emerging trend has major health concerns. It is prevalent worldwide as a recreational activity both indoors and outdoors. The aim of this review was to assess the impact of waterpipe smoke on the oral and respiratory system (oral cavity and pulmonary tissues). A number of studies have shown that periodontal health status is compromised in waterpipe smokers when compared with nonsmokers. Some studies have associated WS with oral premalignant and malignant lesions; however, due to the poor quality of these studies, the presented outcomes should be interpreted with caution. Although cigarette smoking has been considered as a potential risk factor for dental caries; there are no studies in indexed literature that have shown an association to exist between dental caries and WS. Inhaled waterpipe smoke imposes oxidative stress and inflammatory responses and compromises the ventilatory capacity of the lungs and may lead to an increased risk of decline in lung function. WS may cause oral and pulmonary diseases, such as periodontal disease and chronic obstructive airway disease, respectively. The association between WS and development of dental caries and oral pre-cancer and their relationships with chronic airways disease requires investigations. This review discusses the current evidence of waterpipe smoke effects on the oral health and respiratory system based on basic and clinical science and provides future directions for research and regulatory science on how WS can affect the oral cavity and the respiratory/pulmonary system.

Randomized Clinical Trial on Preventing Root Caries among Community-Dwelling Elders

Dental root caries is a common disease among elders. More efforts on preventing this disease are needed. Silver diammine fluoride (SDF) is known to prevent dental caries in primary teeth. However, clinical evidence of its efficacy in preventing root surface caries is limited. This clinical trial aimed to compare the effectiveness of SDF in preventing root caries among elders in a water fluoridated area. A total of 323 elders who had at least 5 teeth with exposed root surfaces and who had self-care ability were randomly allocated into 3 intervention groups: group 1 (placebo control), annual application of tonic water; group 2, annual application of SDF solution; group 3, annual application of SDF solution, immediately followed by potassium iodide (KI) solution. Oral hygiene instructions and fluoride toothpaste were provided to all subjects. Status of dental root surface was assessed every 6 mo by the same independent examiner. After 30 mo, 257 (79.6%) elders were reviewed. The mean numbers of root surface with new caries experience in the control, SDF, and SDF/KI groups were 1.1, 0.4, and 0.5, respectively (analysis of variance, P < 0.001). Scheffe’s multiple comparison showed that elders who received placebo developed more new root caries lesions ( P < 0.05), while the difference between the SDF and SDF/KI groups was not statistically significant ( P > 0.05). Moreover, elders who had higher visible plaque index scores at 30-mo examination (analysis of covariance, P < 0.001) and those who had higher baseline DMFT scores (analysis of covariance, P = 0.005) developed more new root caries. It is concluded that annual application of SDF or SDF/KI solution is effective in preventing root caries among community-dwelling elders in a fluoridated area ( ClinicalTrials.gov NCT02360124).

Knowledge Transfer Statement: Annual topical application of silver diammine fluoride or silver diammine fluoride / potassium iodide solution is effective in preventing dental root surface caries among community-dwelling elders in a fluoridated area.

Whole-Saliva Fluoride Levels and Saturation Indices in 65+ Elderly during Use of Four Different Toothpaste Regimens

BACKGROUND

Elderly individuals suffering from subnormal saliva secretion combined with inadequate oral hygiene may develop rampant caries and caries in parts of the dentition not normally affected by caries if preventive measures are not undertaken. Such measures include elevating fluoride levels at the saliva/biofilm/tooth interface.

AIM

To analyse whole-saliva fluoride levels and mineral saturation indices during different fluoride toothpaste regimens in home-living elderly.

MATERIALS AND METHODS

Whole saliva was collected from 27 subjects (7 males and 20 females, mean age 73.5±6.1 years) at ten time points covering the whole day during five 2-week periods. During the first period, participants used their normal toothpaste without instructions (baseline). This was followed by TP1: 1,450-ppm NaF toothpaste; TP2: 1,450-ppm monofluorophosphate (MFP) toothpaste with addition of calcium; TP3: 5,000-ppm NaF toothpaste, and TP4: the same toothpaste with additional 'smearing' of toothpaste on the teeth, twice daily. During TP1-TP4, the participants were instructed to brush 3 times per day using 1.5 g of toothpaste without rinsing.

RESULTS

Salivary fluoride levels increased with toothpaste fluoride content (p<0.001), although major interindividual and intraindividual variations were observed. The highest fluoride values appeared in the morning and at night (p<0.001). Saturation indices for calcium fluoride were affected by the fluoride content in pastes (p<0.05). Concerning hydroxyapatite and fluorapatite, indices were highest with the MFP toothpaste and extra calcium (NS to p<0.05).

CONCLUSIONS

Use of a high-fluoride toothpaste resulted in significantly increased fluoride levels in whole saliva and mineral saturation indices were indeed influenced by choice of toothpaste.