The 'strip method': a simple method for plaque pH assessment

Effects of Hydroxyapatite-Containing Toothpastes on Some Caries-Related Variables: A Randomised Clinical Trial

OBJECTIVES

This randomised clinical trial was designed and carried out with the aim to evaluate the capacity of fluoride-substituted hydroxyapatite (HAF) toothpaste to modulate oral microflora composition and biofilm acidogenicity in schoolchildren.

METHODS

In all, 610 children (4 to 5 and 6 to 7 years) were enrolled. Four toothpastes were randomly administered during 24 months: 2 contained fluoride-substituted hydroxyapatite (HAF1000 and HAF1450; 1000 and 1450 ppmF) and magnesium-, strontium-, and carbonate-substituted hydroxyapatite in a chitosan matrix, and 2 were monofluorophosphate fluoridated toothpastes (F1000 and F1450; 1000 and 1450 ppmF). Caries lesions were assessed by International Caries Detection and Assessment System scores, supragingival plaque was sampled from the approximal sites between primary molars using sterile Gracey curettes for microbiological analysis, and plaque pH curves after sucrose challenge were assessed at baseline and reevaluated after 1 year and after 2 years. The minimum and maximum pH decrease was calculated for caries-free patients and participants with a caries lesion(s) at baseline and at the end of the experimental period (24 months). Differences amongst measurements were analysed with 1-way analysis of variance.

RESULTS

During the trial, the minimum pH value increased statistically significantly in all groups; in HAF1000 and HAF1450, the increase was greatest. At the end of trial, in the 2 HAF groups all primary cariogenic bacteria were statistically significantly lower with respect to F groups (P = .03 for Streptococcus mutans and sobrinus, for Lactobacillus casei, and for Lactobacillus fermentum).

CONCLUSIONS

The trial provides robust but still inconclusive evidence on the efficacy of HAF toothpastes compared to traditional fluoridated toothpastes to reduce caries risk factors and to prevent caries lesions.

O-pH: Optical pH Monitor to Measure Oral Biofilm Acidity and Assist in Enamel Health Monitoring

OBJECTIVE

Bacteria in the oral biofilm produce acid after consumption of carbohydrates which if left unmonitored leads to caries formation. We present O-pH, a device that ca measure oral biofilm acidity and provide quantitative feedback to assist in oral health monitoring.

METHOD

O-pH utilizes a ratiometric pH sensing method by capturing fluorescence of Sodium Fluorescein, an FDA approved chemical dye. The device was calibrated to a lab pH meter using buffered fluorescein solution with a correlation coefficient of 0.97. The calibration was further verified in vitro on additional buffered solution, artificial, and extracted teeth. An in vivo study on 30 pediatric subjects was performed to measure pH before (rest pH) and after a sugar rinse (drop pH), and the resultant difference in pH (diff pH) was calculated. The study enrolled subjects with low (Post-Cleaning) and heavy (Pre-Cleaning) biofilm load, having both unhealthy/healthy surfaces. Further, we modified point-based O-pH to an image-based device using a multimode-scanning fiber endoscope (mm-SFE) and tested in vivo on one subject.

RESULTS AND CONCLUSION

We found significant difference between Post-Cleaning and Pre-Cleaning group using drop pH and diff pH. Additionally, in Pre-Cleaning group, the rest and drop pH is lower at the caries surfaces compared to healthy surfaces. Similar trend was not noticed in the Post-Cleaning group. mm-SFE pH scope recorded image-based pH heatmap of a subject with an average average diff pH of 1.5.

SIGNIFICANCE

This work builds an optical pH prototype and presents a pioneering study for non-invasively measuring pH of oral biofilm clinically.

Study protocol for a randomized clinical trial to evaluate the effect of the use of Xylitol gum in the prevention of caries lesions in children living in Ladakh-the Caries Prevention Xylitol in Children (CaPreXCh) trial

Background

Xylitol use is reported to be able to reduce dental plaque amount and cariogenic bacteria and, as a consequence, the caries increment. Only few data on the oral health of Ladakh’s population are available. The aim of the present protocol will be to record the caries prevalence of primary and permanent molars of schoolchildren living in Ladakh and to implement a school-based Xylitol programme, named the Caries Prevention Xylitol in Children (CaPreXCh) trial, using chewing gums.

Methods

The protocol is designed as a triple-blind randomized, controlled, parallel-group clinical trial in children aged 5–14 years. The study should have been carried out from August 2021 to August 2024 in Zanskar Valley (Ladakh), but the COVID-19 pandemic does not allow today to make predictions on the exact start. Participants will be randomly allocated into two groups: subjects who will receive a chewing gum with Xylitol (70% w/v) as only sweetener, and those who will receive a sugared chewing gum containing Maltitol (23% w/v). The subjects will be instructed to chew a total of 6 pellets for 5 min divided into 3 intakes a day (2 in the morning, 2 after the midday meal and 2 in the afternoon) for one school year. Clinical examination will comprise an oral examination in which caries index (ICDAS scores), bleeding on probing and plaque pH evaluation after sucrose challenge will be recorded at baseline (t₀); the clinical examination will be repeated after 12 months since the beginning of the chewing gum administration period (t₁), after another 12-month period (t₂) and finally after further 12 months (t₃) (24 months from the end of the chewing gum use). The primary outcome will be the caries increment measured both at enamel and dentinal levels on primary and permanent molars. Data analysis will be conducted through Kaplan-Meyer graphs to evaluate caries increment. A comparison of the methods will be carried out with Cox regression with shared frailty. The net caries increment for initial, moderate and severe caries levels, using ICDAS (Δ-initial, Δ-moderate and Δ-severe), will be calculated.

Discussion

This trial will be the first trial conducted in India assessing the efficacy of a school-based caries preventive programme through the use of chewing gum containing only Xylitol as a sweetener. The findings could help strengthen the evidence for the efficacy of Xylitol use in community-based caries prevention programmes in children.

Trial registration

Clinical trials.govNCT04420780. Registered on June 9, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05828-y.

Salivary parameters and their correlation with neutrophil counts in children with acute lymphoblastic leukemia

BACKGROUND

Chemotherapy for Acute Lymphoblastic Leukemia (ALL) is known to render children immuno-deficient. A concomitant suppression of local defence mechanisms, such as saliva may further aggravate the adverse consequences of chemotherapy. The present study was conducted to evaluate alterations in salivary flow rate, pH and buffering capacity and to correlate these parameters with Absolute Neutrophil Counts (ANC).

METHODS

A cohort of 43 patients, aged 3-12 years were evaluated for the aforementioned parameters at baseline, post-induction and post-consolidation phases. Salivary collection was done and ANC was measured from routine haematological reports.

RESULTS

A decrease in the salivary parameters was observed at the end of Induction phase as compared to baseline, with a statistically significant decrease in unstimulated salivary flow rates (p < 0.01). Statistically significant positive correlations were found between ANC and salivary flow rate (p = 0.005), pH (p < 0.00) and buffering capacity (p < 0.00). On testing the significance of these correlations, all the values for these parameters were found to be statistically significant.

CONCLUSION

Salivary parameters showed derangements over the phases of chemotherapy, with maximum decrease at the end of induction phase. The positive correlations of salivary parameters with ANC of the subjects may be considered indicative of a concomitant immunological compromise in these children.

Approximal plaque pH lowering after sugar intake in a periodontally infected dentition

OBJECTIVES

The aim of this study was to evaluate the effect of periodontal inflammation on the approximal plaque pH after a sucrose rinse.

MATERIALS AND METHODS

Thirty-two periodontitis patients (aged 38-72 years; 9M/23F) were included. All patients were in need of periodontal surgery. Two non-adjacent interdental spaces, one healthy (no bleeding on probing [BoP] and probing pocket depth [PPD] < 4 mm) and one periodontally diseased (BoP and PPD ≥5 mm) were selected. Before and after surgery, the approximal plaque pH was measured before and after 2, 5 and 10 min after a 1-min rinse with sucrose solution.

RESULTS

In periodontally diseased interdental spaces, a significant pH drop was seen 5 min after rinsing. In healthy spaces and after surgery, a significant pH drop was seen after 2 min. A multilevel regression analysis showed that greater probing pocket depths were significantly associated with pH change measured 5 min after rinsing (p < .05). Further on, the approximal pH drop after a sucrose rinse tended to be delayed in dentitions with ≥10% of PPD ≥5 mm (p = .052).

CONCLUSIONS

The results suggest that an ongoing periodontal inflammation could temporarily neutralize acidic metabolic products after a sugar challenge. This may further suggest that plaque pH measured after a sugar rinse might be used to identify an ongoing periodontal disease.

Effect of drops containing Lactobacillus reuteri (DSM 17938 and ATCC PTA 5289) on plaque acidogenicity and other caries-related variables in orthodontic patients

BACKGROUND

The purpose of the study was to investigate the effect of probiotics on biofilm acidogenicity and on the number of salivary Streptococcus mutans and lactobacilli in orthodontic patients.

METHODS

This RCT was conducted on 28 young adults who were undergoing orthodontic treatment. The short-term prospective clinical trial lasted for three weeks. The test group rinsed daily with drops containing two Lactobacillus reuteri strains diluted in water, while the placebo group used drops without probiotics. The subjects were enrolled eight months since the beginning of orthodontic treatment. Plaque-pH, saliva and dental biofilm samples were obtained at baseline, one week and three weeks post intervention.

RESULTS

Twenty-seven subjects successfully completed the trial period, only one drop out in the test group. No side effects were reported. A statistically significant increase in plaque pH at three weeks post-intervention was found for the test group (p < 0.05), while insignificant changes in the pH value were found for the placebo group in comparison to baseline (p > 0.05). In addition, the AUC_7.0 showed a significant difference at three weeks between the test and placebo (p = 0.00002). The three-week samples of stimulated whole saliva showed a statistically insignificant difference in the number of S. mutans and lactobacilli between the two groups (p > 0.05). The qPCR analysis showed the ability of the two strains to get colonized in the dental biofilm without a significant effect on the microbial counts.

CONCLUSION/CLINICAL IMPLICATIONS

A mixture of Lactobacillus reuteri has the ability to reduce the pH fall at the three-week follow-up. However, the short-term use of probiotics does not appear to have an effect on the number of salivary Streptococcus mutans and lactobacilli in saliva and on the dental biofilm.

TRIAL REGISTRATION

Clinicaltrial.gov (Identifier: NCT04593017 / (19/10/2020)).

Biofilm formation following chitosan-based varnish or chlorhexidine-fluoride varnish application in patients undergoing fixed orthodontic treatment: a double blinded randomised controlled trial

Background

Orthodontic treatment poses an increased risk of plaque accumulation and demineralisation of enamel leading to white spot lesion around the brackets. This parallel arm trial aims to assess the degree of bacterial plaque formation adjacent to orthodontic brackets, following the application of a chitosan-based varnish or chlorhexidene-fluoride varnish.

Methods

A total of 200 teeth from 20 patients undergoing fixed orthodontic therapy were assessed and biofilm formation around the brackets were recorded using the Bonded Bracket Index (Plaque index) at baseline and weekly for 6 weeks. The bacterial count and plaque pH at corresponding weekly intervals were also recorded. Following bracket bonding, the patients were cluster randomised to receive chitosan-based varnish-CHS (UNO Gel Bioschell, Germiphene corp., Brantford, Canada) or chlorhexidine-fluoride varnish-CFV (Cervitec F, Ivoclar Vivadent, Schaan, Liechtenstein) every week on the representative teeth respectively. BBI proportions were compared between groups at all time intervals using Chi square test. Mean plaque bacterial count and plaque pH were compared using Mann Whitney U test and Tukey’s HSD test respectively.

Results

Baseline characteristics were similar between the groups: Mean age was CHS = 23 and CFV = 21; male to female ratio was CHS = 5/5, CFV = 7/3. At the end of 6 weeks, chitosan-based varnish performed equal to chlorhexidine-fluoride varnish (P > 0.05) with 98% and 95% of teeth with acceptable scores respectively. The plaque bacterial count significantly reduced at 6 weeks for both varnish compared to the baseline; The value for CHS was 0.43 ± 0.4 × 10⁴ and CFV was 0.77 ± 0.64 × 10⁴ CFU (P < 0.05), with no difference between both the varnishes. Both varnishes had no effect on the plaque pH that remained neutral.

Conclusion

This trial showed that both chitosan-based varnish and chlorhexidine-fluoride varnish reduced bacterial count, while the plaque pH remained neutral over a period of six weeks in patients undergoing fixed orthodontic therapy. The anti-plaque effects of the natural biopolymeric chitosan-based varnish was similar to that of chlorhexidine-fluoride varnish, a known chemotherapeutic agent.

Registration: This trial protocol was registered with https://www.ctri.nic.in (CTRI/2019/05/018896). (Date of registration 02/05/2019).

Protocol: The protocol was not published before trial commencement.

Profuse diversity and acidogenicity of the candida-biome of deep carious lesions of Severe Early Childhood Caries (S-ECC)

Introduction: The retentive niches of deep caries lesions have a distinct biome. Methods: We evaluated the site-specific (occlusal and proximal) Candida-biome of Severe-Early Childhood Caries (S-ECC) in 66- children (132 lesions). Asymptomatic primary molars fitting the definition of the International Caries Detection and Assessment-(ICDAS)-caries-code 5/6 were analyzed. Deep-dentinal sampling and simultaneous assessment of pH were performed. Clinical isolates were speciated using multiplex-PCR and evaluated for their acidogenic and aciduric potential.Results: Surprisingly, a high prevalence of Candida species (72.7%), either singly or in combination, was noted from both the proximal and occlusal cavities. C. tropicalis was the most prevalent species (47%; 34/72), followed by C. krusei (43.1%; 31/72) and C. albicans (40.3%; 29/72), with C. glabrata being the least (9.7%; 7/72). Over 45% low-pH niches (pH <7) of both sites yielded either dual or triple species of Candida. Genotyping revealed three distinct C. albicans genotypes (A, B, and C) with (14/29; 48.3%) of strains belonging to Genotype A. All four evaluated Candida species exhibited acidogenic and aciduric potential, C. tropicalis being the most potent.Conclusion: This, the first report of the high-density, multispecies, yeast colonization of deep-dentinal lesions in S-ECC, suggests that the Candida-biome plays a significant etiologic role in the condition, possibly due to their profound acidogenicity in milieus rich in dietary carbohydrates.

Effect of Lactobacillus brevis CD2 containing lozenges and plaque pH and cariogenic bacteria in diabetic children: a randomised clinical trial

Objective

The short-term effect (60 days) of Lactobacillus brevis CD2 lozenges vs placebo on variables related to caries and gingivitis in type 1 diabetic children was evaluated.

Material and methods

Eight diabetics (4–14 years old) were assigned to two groups (n = 34 subjects each), probiotic lozenges and placebo. Stimulated saliva for microbiological analysis and plaque pH were assessed at baseline (t₀), 30 days (t₁), 60 days (t₂) and in the follow-up period (90 days from baseline, t₃). Gingival status was assessed at t₀, t₂ and t₃. Two-way ANOVA assessed differences between groups.

Results

In the probiotic group, Streptococcus mutans bacterial density mean scores dropped from 3.11 ± 1.13 at baseline to 1.82 ± 0.72 (t₂) and to 2.06 ± 0.56 (t₃), while in the placebo group, the scores were 3.09 ± 0.8 (t₀), 2.82 ± 0.47 (t₂) and 3.11 ± 0.43 (t₃) (p < 0.01). Lowest and maximum pH fall increased in the probiotic group, from 5.37 ± 0.41 at baseline to 5.49 ± 0.24 at t₃ (p < 0.01) and from 1.20 ± 0.46 to 0.98 ± 0.29 (p = 0.02). Bleeding score decreased significantly in both groups, showing a statistically significant lower bleeding score at t₂ in the probiotic group (25.6%, 95% CI 21.5–32.7 vs 29.5%, 95% CI 25.2–34.9, p = 0.02).

Conclusions

Lactobacillus brevis CD2 has shown to improve caries-related risk factors and gingival health in diabetic children.

Clinical relevance

Lactobacillus brevis CD2 might contribute to improved oral health in type 1 diabetic children.

Electronic supplementary material

The online version of this article (10.1007/s00784-020-03342-0) contains supplementary material, which is available to authorized users.

Wearable Lab on Body: Combining Sensing of Biochemical and Digital Markers in a Wearable Device

Wearables are being widely researched for monitoring individual's health and wellbeing. Current generation wearable devices sense an individual's physiological data such as heart rate, respiration, electrodermal activity, and EEG, but lack in sensing their biological counterparts, which drive the majority of individual's physiological signals. On the other hand, biosensors for detecting biochemical markers are currently limited to one-time use, are non-continuous and don't provide flexibility in choosing which biomarker they sense. We present "wearable lab on body", a platform for active continuous monitoring of human biomarkers from the biological fluid. Our platform contains both digital sensors such as IMU for activity recognition, as well as an automated system for continuous sampling of biomarkers from saliva by leveraging already existing paper-based biochemical sensors. The platform could aid with longitudinal studies of biomarkers and early diagnosis of diseases.

Optical pH measurement system using a single fluorescent dye for assessing susceptibility to dental caries

Sugar-rich diets and poor dental hygiene promote the formation of a biofilm (plaque) that strongly adheres to the dental enamel surface and fosters the evolution of aciduric bacteria. The acid contributes to demineralization of the exterior tooth enamel, which accelerates after the pH drops below a critical value (∼5.5) for extended time periods resulting in the need for restorative procedures. Preventative techniques to alert the dentist and caries-susceptible patients regarding vulnerability to dental decay require a clinical measure of plaque activity. Therefore, there is a need to evaluate the acid production capability of plaque deposits in the pits and fissures of occlusal and interproximal regions. A ratiometric fluorescence pH-sensing device has been developed using an FDA-approved dye and LED excitation. Fluorescein spectral profiles were collected using a spectrometer and analyzed with a spectral unmixing algorithm for calibration over the pH range of 4.5 to 7. An in vivo pilot study on human subjects was performed using a sucrose rinse to accelerate bacterial metabolism and to measure the time-dependent drop in pH. The optical system is relatively immune to confounding factors such as photobleaching, dye concentration, and variation in excitation intensity associated with earlier dye-based pH measurement techniques.

Dental pH Opti-Wand (DpOW): measuring oral acidity to guide enamel preservation

Undetected caries can lead to painful cavities and surgical restorations. Lack of proper detection tools makes caries prevention dependent on dentist's expertise and presents obstacles in oral health monitoring. To overcome this problem, we have developed a new approach to predict early stages of enamel demineralization caused by oral bacteria. These bacteria metabolize sugars in our food and produce organic acids that lead to cavities. Measuring the acidity level can help predict early stages of tooth decay. pH paper or pH electrodes can be used to monitor acidity, but neither are able to track pH levels in all dental locations. Our device, DpOW, is a noncontact optics-based pH device that uses changes in the spectral fluorescence of FDA allowed fluorescein dye to measure acidity levels in difficult to access dental locations such as occlusal fissures. A prototype has been tested over a wide pH range (7.12 to 3.89) and shown to track the change in pH with 0.94 correlation coefficient.

Presence of Helicobacter pylori and Campylobacter ureolyticus in the oral cavity of a Northern Thailand population that experiences stomach pain

Objective: To investigate oral diseases and microbiological conditions, such as the presence of ureolytic bacteria in dental plaque, in relation to experience of stomach pain in a remote adult Asian population. Methods: Ninety-three adults, 40-60-years old, from the Karen Hill tribe in Northern Thailand with no regular access to dental care were examined. Clinical registrations were performed and interproximal gingival plaque samples were collected and analyzed with the checkerboard (CKB) method for the presence of 14 oral bacterial species. Results: A number of 61 subjects reported daily stomach pain while 32 subjects had no symptoms from the stomach. The subjects with stomach pain had fewer remaining teeth (p < 0.05), higher caries experience (p < 0.05) and less BoP (p < 0.01). Most of the bacterial species were clustered statistically in three factors in a factor analysis, which together explained 65% of the microbiological variance. Factor 1, explaining 43.0% of the variance, was statistically associated with stomach pain (p < 0.001). Conclusions: The interproximal plaque/biofilm in adults of the study population showed a common presence of two gastrointestinal pathogens H. pylori and C. ureolyticus. The study also indicates for the first time a potential association between C. ureolyticus and stomach pain.

Carious status and supragingival plaque microbiota in hemodialysis patients

Objective

The aim of this study was to evaluate the carious status and the microbial profiles of supragingival plaque in patients with chronic kidney disease undergoing hemodialysis.

Methods

This study included 30 patients with chronic kidney disease undergoing hemodialysis as well as 30 control subjects. Dental examination was performed and the decayed-missing-filled-teeth was recorded. Supragingival plaque was taken and analyzed using 16S rRNA gene amplicon by Illumina MiSeq sequencing to detect microbial composition and community diversity and structure.

Results

The level of decayed-missing-filled-teeth was higher in the hemodialysis group than that in the control group. Microbial analysis showed a decrease in α diversity and a increase in relative abundance and prevalence of many acidogenic and aciduric caries related species in the supragingival plaque samples of the hemodialysis patients, including Streptococcus mutans, Lactobacillus salivarius, Lactobacillus fermentum, Lactobacillus vaginalis, Scardovia wiggsiae F0424, and Actinomyces naeslundii.

Conclusion

Our results suggested that the hemodialysis patients were more susceptible to caries. More attentions for caries prevention and treatment should be paid to improve their life quality, and even to reduce their cardiovascular events and survival.

Improved pH-ratiometry for the three-dimensional mapping of pH microenvironments in biofilms under flow conditions

Confocal microscopy-based monitoring of pH in biofilms is gaining increasing interest, as it allows for a quick assessment of horizontal pH gradients without mechanically perturbing the biofilm. Ratiometric monitoring of pH with the fluorescent dye C-SNARF-4 has been used to reliably map extracellular pH in the basal layers of biofilms, but only under static conditions. Here, we expand this methodology to measurements of vertical gradients in multispecies in vitro-grown and in situ-grown dental biofilms of different age, and to pH measurements in in vitro-grown biofilms under flow conditions. After static incubation with glucose, young in vitro-grown biofilms (30h) were more acidogenic than older biofilms (120h). However, under dynamic conditions mimicking the oral salivary flow, low pH was only preserved in older biofilms. As both types of biofilm were of similar thickness (~20 μm), these findings highlight the importance of cell density and biofilm matrix maturation for pH developments. In both in vitro-grown and in in situ-grown biofilms, horizontal and vertical pH gradients were observed. Under static conditions, the surface layer of the biofilms tended to be more acidic, whereas the bottom layer became more acidic under dynamic conditions. Compared to in vitro-grown biofilms, 120 h in situ-grown biofilms showed higher acidogenicity during static incubation. This study shows that pH ratiometry with C-SNARF-4 is well-suited to monitor extracellular pH in thin biofilms in all three dimensions. The different pH dynamics observed under static and dynamic conditions argue for the implementation of flow during real-time assessment of biofilm pH.

Evaluation of the difference in caries experience in diabetic and non-diabetic children-A case control study

Aim

To evaluate the caries prevalence and related variables in Type 1 diabetic and non-diabetic children and among the diabetic children according to their metabolic status.

Methods

Sixty-eight diabetic and 136 non-diabetic children, matching by gender and age (4–14 years) were enrolled. The diabetic children were divided: a) 20 children in good metabolic control (Hb1ac≤7.5) and b) 48 children in bad metabolic control (Hb1ac>7.5). Dietary and oral hygiene habits were investigated. Caries status was registered using the International Caries Detection and Assessment System. Oral microflora was analysed using the checkerboard DNA-DNA hybridisation method. Plaque acidogenicity was recorded after a sucrose rinse.

Results

Sugared beverage and snack intake was higher in diabetic group compared to non-diabetic group (p = 0.03 and p = 0.04, respectively) and in subjects in bad metabolic control (p = 0.03 and p<0.01, respectively). Oral hygiene habits were similar, except for the use of fluoridated adjuvants, higher in non-diabetic children (p = 0.04). No statistically significant differences were observed regarding caries figures, but a higher number of caries free subjects was found in diabetic subjects in good metabolic control (p<0.01). Significant difference for the main cariogenic bacteria was found between diabetic and non-diabetic subjects (p<0.05). The pH values showed statistically significant differences between diabetic and non-diabetic subjects and between diabetic subjects in good and bad metabolic control (p<0.01).

Conclusions

Diabetic children in good metabolic control might even be considered at low caries risk, while those in bad metabolic control showed an oral environment prone to a high caries risk.

The Influence of Pregnancy on Sweet Taste Perception and Plaque Acidogenicity

Objectives Women undergo different physiological and oral changes during pregnancy and this may increase the risk of dental caries and other oral diseases. The aim of the present study was to investigate changes in biofilm acidogenicity and correlate them to sweet taste perception in pregnant and non-pregnant women. Methods Three groups of Saudi women participated in this cross-sectional study: (1) women in early pregnancy (n = 40/mean age 29.6 years/DMFT 10.7), (2) women in late pregnancy (n = 40/29.5 years/DMFT 10.8) and (3) non-pregnant women (n = 41/27.7 years/DMFT 12.3). Changes in plaque pH were determined by using colour-coded indicator strips before and after a 1-min rinse with a 10% sucrose solution. A taste perception test determining sweet preference and threshold levels was also performed. Results A significant difference regarding plaque pH was seen between the early, late and non-pregnant women when calculated as the area under the curve (p < 0.05). Regarding the taste perception tests, taste preference and threshold were correlated (p < 0.001, r = 0.6). Between the three groups, a statistically significant difference was seen in taste threshold and taste preference respectively (p = 0.001 and p < 0.001). Conclusions The findings in this study suggest that pregnant women may undergo taste changes and experience lower plaque pH, which may result in an increased risk of dental caries.

The caries preventive effect of 1-year use of low-dose xylitol chewing gum. A randomized placebo-controlled clinical trial in high-caries-risk adults

Objectives

The caries preventive effect of long-term use (1 year) of low-dosage (2.5 g/die) of xylitol chewing gum in a high-caries-risk adult population was evaluated.

Materials and methods

In this randomized clinical trial, 179 high-caries-risk adults were assigned to two experimental groups, xylitol and polyols. Caries status, salivary mutans streptococci (MS), and plaque pH were re-evaluated after 2 years from baseline in 66 xylitol and 64 polyol subjects. Outcomes (the net caries increment for initial, moderate, and extensive caries lesions and for the caries experience) were evaluated using the nonparametric Mann–Whitney U test.

Results

The total caries experience increment was 1.25 ± 1.26 in the xylitol group and 1.80 ± 2.33 in the polyol group (p = 0.01). Subjects treated with xylitol chewing gums had a reduction of risk rate at tooth level of 23% with respect to those treated with polyols with a number needed to treat of 55 teeth. The area under the curve at pH 5.7 was statistically significantly lower (p = 0.02) during the experimental period in the xylitol group. A decrease of the concentration of salivary MS was noted in the xylitol group (p < 0.01).

Conclusions

Subjects using the low-dose xylitol chewing gum showed a significantly lower increment of initial and extensive caries lesions and overall a lower increment of caries experience.

Clinical relevance

One-year use of chewing gums provides an effective means for the prevention of caries disease.

Trial registration number

NCT02310308

Plaque pH in caries-free and caries-active young individuals before and after frequent rinses with sucrose and urea solution

OBJECTIVE

To examine pH in the approximal dental biofilm after acid and alkali formation from sucrose and urea, after an adaptation period to these substances, in caries-free (CF) and caries-active (CA) individuals. Saliva flow and buffer capacity, and aciduric bacteria in saliva and plaque were also examined.

MATERIAL AND METHODS

Twenty adolescents and young adults (15-21 years) with no caries (n = 10, D(m + i)MFS = 0) or ≥1 new manifest lesions/year (n = 10, DmMFS = 3.4 ± 1.8) participated. After plaque sampling, interproximal plaque pH was measured using the strip method before (baseline) and up to 30 min (final pH) after random distribution of a 1-min rinse with 10 ml of 10% sucrose or 0.25% urea. This procedure was repeated after a 1-week adaptation period of rinsing 5 times/day with 10 ml of the selected solution. After a 2-week washout period the second solution was similarly tested. Mutans streptococci, lactobacilli and pH 5.2-tolerant bacteria were analyzed by culturing.

RESULTS

In the CF group, acid adaptation resulted in lowering of baseline and final plaque pH values after a sugar challenge, and in increased numbers of bacteria growing at pH 5.2, which was increased also after alkali adaptation. In the CA group, the final pH was decreased after acid adaptation. No clear effects of alkali adaptation were seen in this group.

CONCLUSION

One-week daily rinses with sucrose and urea had the most pronounced effect on the CF group, resulting in increased plaque acidogenicity from the sugar rinses and increased number of acid-tolerant plaque bacteria from both rinses.

Effects of lactose-containing stevioside sweeteners on dental biofilm acidogenicity

The aim of this study was to evaluate the effect of a commercial lactose-containing stevioside sweetener on biofilm acidogenicity in vivo. Nine volunteers refrained from brushing their teeth for 3 days in five phases. On the 4th day of each phase, the pH of the biofilm was measured by the "Strip method". Interproximal plaque pH was measured before and up to 60 minutes after a 10 mL mouthrinse for 1 minute with the test solutions: I - sweetener with 93% lactose and 7% stevioside; II - sweetener with 6.8% saccharin, 13.6% cyclamate, and 0.82% stevioside; III - 18% sucrose solution (positive control); IV - mineral water (negative control); and V- 93% lactose solution. The results revealed that the most pronounced pH fall was found with sucrose (positive control), followed by the 93% lactose solution, the sweetener with lactose + stevioside, the sweetener with saccharin + cyclamate + stevioside, and finally water (negative control). According to the area under the curve, the two sweeteners containing stevioside were significantly different, and the sweetener with lactose + stevioside was significantly different from water but not from sucrose. The critical pH for dentin demineralization (pH ≤ 6.5) was reached by all volunteers after rinsing with sucrose solution, lactose solution, and the stevioside + lactose sweetener. Analysis of the data suggests that lactose-containing stevioside sweeteners may be cariogenic, especially to dentin.

Dental plaque pH and ureolytic activity in children and adults of a low caries population

OBJECTIVES

The aim of this study was to evaluate the plaque pH level and ureolytic activity among children and adults of Karen Hill tribes.

METHODS

Thirty-four children aged 6-10 years and 46 adults aged 20-38 years were interviewed regarding oral hygiene practices, sucrose intake and betel chewing. Caries experience (DMFT and DT), calculus, bleeding on probing (BoP) and Plaque index (PlI) were registered. Ureolytic activity in supragingival plaque was tested at two interproximal sites (11/12 and 41/42) with the rapid urease test (RUT). Registration of plaque pH was performed at two interproximal sites (15/16 and 31/41) before, during and 30 min after rinsing with an urea solution (0.25%). Four interproximal plaque samples (one from each quadrant) per individual were collected to test the bacterial composition using the checkerboard technique.

RESULTS

Children and adults had similarly low DMFT and DT values. Children had a higher baseline pH and a higher ureolytic activity in the maxilla (p < 0.05) compared with adults. A significant correlation (r (2) = 0.63) was found between baseline pH and urease activity in the mandibular anterior teeth. Caries-free individuals had a higher baseline pH compared with caries active individuals in the anterior mandibular region (p < 0.01). The microbiological composition was characterized by an anaerobic low acidiogenic microbiota.

CONCLUSIONS

Dental plaque pH is related to the ureolytic activity, which explains the low acidogenic plaque microflora and the low caries levels in the Karen population.

Clinical and biological indicators of dental caries and periodontal disease in adolescents with or without obesity

OBJECTIVE

This study aims to assess clinical, microbiological and inflammatory parameters as indicators for caries and periodontal disease in adolescents with obesity.

MATERIAL AND METHODS

Twenty-seven adolescents with obesity [body mass index (BMI) 37 ± 4 kg/m(2)] and 28 controls (BMI 20 ± 2 kg/m(2)) answered questionnaires and were investigated regarding salivary parameters, plaque pH drop after a 1-min glucose rinse, oral clinical parameters, inflammatory markers in gingival crevicular fluid (GCF) and sub-gingival mirobiota.

RESULTS

Compared with controls, adolescents with obesity had a lower stimulated salivary secretion rate (1.55 ± 0.63 vs. 2.05 ± 1.05 mL/min, p < 0.05), higher concentrations of secretory immunoglobulin A (sIgA) (p < 0.001), more decayed tooth surfaces (3.4 ± 6.6 vs. 0.8 ± 1.1, p < 0.05) and more gingivitis (p < 0.01) after controlling for possible confounders. Overall, similar snacking habits, plaque amounts and numbers of deep periodontal pockets were observed. Following the glucose rinse, a slightly more pronounced drop in plaque pH was observed in the obesity group (p > 0.05). No differences in sub-gingival inflammatory or microbial indicators were detected (p > 0.01).

CONCLUSIONS

More caries and gingival inflammation were observed in adolescents with obesity. Of the indicators tested, salivary secretion rate was lower and sIgA levels were higher in the obesity group. We are unable to confirm whether differences in caries and gingival inflammation are due to systemic changes that are associated with obesity or due to possible irregular dietary/oral hygiene habits.

CLINICAL RELEVANCE

Customised oral health preventive programmes and appropriate collaboration with medical personnel in selecting the best diet, medication and psychological support can help improve the general well-being, including oral health, of children with obesity. This may even reduce the risk of oral diseases.

Effect of a sugar-free chewing gum containing magnolia bark extract on different variables related to caries and gingivitis: a randomized controlled intervention trial

The effect of magnolia bark extract (MBE) on different variables related to caries and gingivitis administered daily through a sugar-free chewing gum was evaluated. The study was performed with healthy adult volunteers at high risk for caries as a randomized double-blind interventional study. 120 subjects with a salivary mutans streptococci (MS) concentration ≥10(5) CFU/ml and presence of bleeding on probing >25% were enrolled and divided into three groups: magnolia, xylitol and control. The study design included examinations at baseline, after 7 days, after 30 days of gum use and 7 days after the end of gum use. Plaque pH was assessed using the strip method following a sucrose challenge. Area under the curve (AUC(5.7) and AUC(6.2)) was recorded. Whole saliva was collected and the number of salivary MS (CFU/ml) was counted. Bleeding on probing was recorded as a proxy of dental plaque. Data were analyzed using ANOVA repeated measures. Magnolia gum significantly reduced plaque acidogenicity, MS salivary concentration and gingival bleeding compared to xylitol and control gums. Subjects from the magnolia and xylitol groups showed both MS concentration (p = 0.01 and 0.06, respectively) and AUC(5.7) (p = 0.01 and 0.04, respectively) to be significantly lower compared to baseline. Thirty-day use of a chewing gum containing MBE showed beneficial effects on oral health, including reduction of salivary MS, plaque acidogenicity and bleeding on probing.