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The Effect of Sucrose on Plaque pH in the Primary and Permanent Dentition of Caries-inactive and -active Kenyan Children
Abstract
The hypothesis that the Stephan pH responses of dental plaque would be different in caries-active and -inactive individuals was tested in 20 seven-year-old and 19 14-year-old Kenyan children. In each age group, half the children had greater than or equal to 2 dentin cavities; the other half had no such lesions. With a palladium-touch microelectrode, interdental plaque pH was monitored between m1/m2 in each quadrant in the primary dentition and in the four molar/premolar regions in the permanent dentition. pH was also monitored in caries cavities in the occlusal surfaces of lower first molars and on the tongue. pH was measured before and up to 60 min after the children rinsed with 10 mL of 10% sucrose. Caries status of the individual was unrelated to plaque pH in comparable non-carious sites in both of the age groups. The pH minimum in the maxilla was about 0.5 pH units lower than that in the mandible. Active occlusal caries lesions had a resting pH value of about 5.5, about 1 pH unit lower than that of sound surfaces. The pH dropped to about 4.5 in caries lesions and recovered slowly. In sound occlusal sites, a pH drop to about 6.0 was followed by a relatively rapid return to the resting value. Thus, when the mean values were considered, the classic Stephan curve response was evident. However, when the pH changes at single sites were considered at various time intervals, a substantial, erratic fluctuation was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
... Measurement of dental biofilm pH, especially pH before and up to two hours after a sugar rinse was proposed in 1940s [16] as shown in Fig. 2(a). Since then, several studies have examined this pH curve, commonly named as the Stephan curve, and found different sections of the curve: resting pH [17], [18], minimum pH after the sugar rinse [19], [20], time taken to return to resting pH [21], related to caries activity. Most prior pH studies [22], [23] have used pH micro-electrodes to measure dental biofilm pH. ...
... Although O-pH has the potential to be non-contact and thus nondestructive to the dental biofilm, this current spot-based pH sensing has clear drawbacks, especially in reliably testing the same spot before and after a sugar rinse. The lack of replicability in probe placement directly impacts the accuracy of pH drop measurements and has been identified as a source of variability in previous microelectrode measurements [17]. Imaging plays an important role in mapping as dental biofilm pH is highly variable spatially and is a critical enhancement for measuring pH difference. ...
... For example, the level of 10% sucrose solution used for the O-pH and mmSFE case study could be raised to 20% sucrose concentration which shown by Lingström's et al. [20] results in higher diff pH. In another example, several studies [17], [20], [44] have shown that at times it may take up to 5 mins to reach the lowest pH after a sugar rinse. So monitoring the drop pH every minute for 5 minutes can perhaps give a better pH differentiation between caries and sound enamel surfaces. ...
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.
... Several classical electrode-based studies have highlighted the importance of saliva flow for biofilm pH. Maxillary sites exhibit a significantly lower pH under resting conditions than mandibular sites [14][15][16], which may be explained by the estimated 10-fold higher saliva velocity in the mandibula [16]. Following a sucrose challenge, biofilm pH is restored at a speed that depends on the amount and velocity of saliva present [14,17], and masticatory activity increases the saliva flow to an extent that may prevent the pH from dropping below critical values. ...
... Several classical electrode-based studies have highlighted the importance of saliva flow for biofilm pH. Maxillary sites exhibit a significantly lower pH under resting conditions than mandibular sites [14][15][16], which may be explained by the estimated 10-fold higher saliva velocity in the mandibula [16]. Following a sucrose challenge, biofilm pH is restored at a speed that depends on the amount and velocity of saliva present [14,17], and masticatory activity increases the saliva flow to an extent that may prevent the pH from dropping below critical values. ...
Introduction: Fluid flow has a prominent influence on the metabolism of surface-attached biofilms. Dental biofilms are covered by a thin saliva film that flows at different rates in different locations under stimulated and unstimulated conditions.
Methods:The present study employed pH ratiometry to study the impact of different flow velocities, saliva film thicknesses and saliva concentrations on microscale pH developments in Streptococcus mutans biofilms of different age.
Results:While saliva flow at a velocity of 0.8 mm/min (unstimulated flow) had little impact on biofilm pH, stimulated flow (8 mm/min; 80 mm/min) affected vertical pH gradients in the biofilms and raised the average pH in 48-h biofilms, but not in 72-h and 168-h biofilms. The saliva film thickness had a strong impact on biofilm pH under both static and dynamic conditions. pH drops were significantly higher in biofilms exposed to a thin saliva film (≤ 50 µm) than a thick saliva film (> 50 µm). pH drops in the biofilms were also strongly dependent on the saliva concentration and thus the buffer capacity of the salivary medium. For 48-h and 72-h biofilms, but not for 168-h biofilms, pH drops in distinct microenvironments were more pronounced when the local biofilm thickness was high.
... However, measurement of pH enables examination of plaque as a metabolic unit and a significant indicator for caries activity. 12 Originally proposed by Frostell, plaque sampling was mandated to be performed in 5-minute cycles after exposing the oral environment to the cariogenic substrate. Jensen modified this protocol to include both pre and postrinse sampling. ...
Introduction:
People all over the world use a wide variety of infant formulas to nourish the infants. Recent studies demonstrated the high caries-inducing potential of infant formulas. This indicates a need for awareness toward the possible role of the infant formulas in the etiology of early childhood caries (ECC).
Aim:
The present study was undertaken to evaluate and comparatively assess the change in plaque pH solutions after fermenting four commonly used infant milk formulas.
Materials and methods:
This simple randomized study was carried out on 40 healthy children aged 4-6 years old. The children received full-mouth prophylaxis before examination. They were asked not to implicate oral hygiene for 24 hours and not to have anything at least 2 hours prior the study. Supragingival plaque from the buccal surface of posterior teeth was collected using a Hu-Friedy's curette. Four commonly used infant milk formulas were prepared and given to children for rinsing. The pH of plaque samples were measured at 30 and 60 minutes at 37°C.
Results:
The present study showed that all of the four infant milk formulas decreased the mean pH values in plaque solutions significantly after 30 and 60 minutes of preparation.
Conclusion:
Our results showed that the plaque pH varied in response to the oral rinsing with the various infant formulas and most of infant formulas were able to reduce the pH significantly below the pH before the rinse. Based upon this study further evaluation of the cariogenicity of infant formulas is recommended.
How to cite this article:
Pandey A, Pathivada L, Kajapuram P, et al. Assessment of Cariogenicity by pH-value Decrement of Plaque Solution with Four Infant Milk Formulas: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(3):263-266.
... Acidic biofilm continuously adhering to the teeth leads to the dissolution of enamel and the occurrence of caries [204,205]. In particular, sugars present in daily diet are consumed by oral pathogens such as S. mutans, which are responsible for the rapid growth of EPS and acidic aggravation of the biofilm (pH ∼4.5) [206][207][208][209]. ...
The emergence and spread of antibiotic resistance is one of the biggest challenges in public health. There is an urgent need to discover novel agents against the occurrence of multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. The drug-resistant pathogens are able to grow and persist in infected sites, including biofilms, phagosomes, or phagolysosomes, which are more difficult to eradicate than planktonic ones and also foster the development of drug resistance. For years, various nano-antibacterial agents have been developed in the forms of antibiotic nanocarriers. Inorganic nanoparticles with intrinsic antibacterial activity and inert nanoparticles assisted by external stimuli, including heat, photon, magnetism, or sound, have also been discovered. Many of these strategies are designed to target the unique microenvironment of bacterial infections, which have shown potent antibacterial effects in vitro and in vivo. This review summarizes ongoing efforts on antibacterial nanotherapeutic strategies related to bacterial infection microenvironments, including targeted antibacterial therapy and responsive antibiotic delivery systems. Several grand challenges and future directions for the development and translation of effective nano-antibacterial agents are also discussed. The development of innovative nano-antibacterial agents could provide powerful weapons against drug-resistant bacteria in systemic or local bacterial infections in the foreseeable future.
... Simultaneously, dietary sucrose and other ingredients are fermented by cariogenic bacteria to produce lactic acid and switch the surrounding microenvironment acidic (pH 4.5-5.5) [6][7][8]. Acidic conditions are favorable for further EPS synthesis and continuous proliferation of cariogenic bacteria, ultimately leading to dental caries [9]. EPS is poorly permeable to antibiotics and other antibacterial agents, and these agents are therefore easily removed by saliva; as a result, effective drug concentrations cannot be maintained in the oral cavity for continuous periods [10,11]. ...
The efficacious delivery of antimicrobial drugs to intractable oral biofilms remains a challenge due to inadequate biofilm penetration and lack of pathogen targeting. Herein, we have developed a microenvironment-activated poly(ethylene glycol) (PEG)-sheddable nanoplatform to mediate targeted delivery of drugs into oral biofilms for the efficient prevention of dental caries. The PEGylated nanoplatform with enhanced biofilm penetration is capable of deshielding the PEG layer under slightly acidic conditions in a PEG chain length-dependent manner to re-expose the bacteria-targeting ligands, thereby facilitating targeted codelivery of ciprofloxacin (CIP) and IR780 to the bacteria after accumulation within biofilms. The nanoplatform tends to induce bacterial agglomeration and suffers from degradation in the acidic oral biofilm microenvironment, triggering rapid drug release on demand around bacterial cells. The self-modulating nanoplatform under near-infrared (NIR) irradiation accordingly displays greatly augmented potency in oral biofilm penetration and disruption compared with drugs alone. Topical oral treatment with nanoplatforms involving synergetic pharmacological and photothermal/photodynamic trinary therapy results in robust biofilm dispersion and efficacious suppression of severe tooth decay in rats. This versatile nanoplatform can promote local accumulation and specific drug transport into biofilms and represents a new paradigm for targeted drug delivery for the management of oral biofilm-associated infections.
Dental biofilm pH is the most important determinant of virulence for the development of caries lesions. Confocal microscopy-based pH ratiometry allows monitoring biofilm pH with high spatial resolution. Experiments performed on simplified biofilm models under static conditions identified steep pH gradients as well as localized acidogenic foci that promote enamel demineralization. The present work used pH ratiometry to perform a comprehensive analysis of the effect of whole saliva flow on the microscale pH in complex, in situ-grown 48-h and 96-h biofilms (n = 54) from 9 healthy participants. pH was monitored in 12 areas at the biofilm bottom and top, and saliva flow with film thicknesses corresponding to those in the oral cavity was provided by an additively manufactured microfluidic flow cell. Biofilm pH was correlated to the bacterial composition, as determined by 16S rRNA gene sequencing. Biofilm acidogenicity varied considerably between participants and individual biofilms but also between different areas inside one biofilm, with pH gradients of up to 2 units. pH drops were more pronounced in 96-h than in 48-h biofilms (P = 0.0121) and virtually unaffected by unstimulated saliva flow (0.8 mm/min). Stimulated flow (8 mm/min) raised average biofilm pH to near-neutral values but it did not equilibrate vertical and horizontal pH gradients in the biofilms. pH was significantly lower at the biofilm base than at the top (P < 0.0001) and lower downstream than upstream (P = 0.0046), due to an accumulation of acids along the flow path. pH drops were positively correlated with biofilm thickness and negatively with the thickness of the saliva film covering the biofilm. Bacterial community composition was significantly different between biofilms with strong and weak pH responses but not their species richness. The present experimental study demonstrates that stimulated saliva flow, saliva film thickness, biofilm age, biofilm thickness, and bacterial composition are important modulators of microscale pH in dental biofilms.
Previous research indicated that there is an aggregate of microorganism in oral cavity which takes part in promoting the occurrence of dental caries, but few studies on anticaries materials for these 'core microbiome' were developed. And We've found that DMAEM monomer has an obvious inhibitory effect on the growth of Streptococcus mutans and saliva biofilm, but the effect of that on the "core microbiome" of caries need further research. Thus, the objectives of this study were to explore the effect of DMAEM monomer on the core microbiota of dental caries, and to further study its anticaries effect. The changes of microbial structure and metabolic activity of the core microbiota biofilm were detected through measuring lactic acid yield, viable bacteria counts and demineralization depth, et al., and the anticaries potential in vivo of DMAEM monomer was evaluated by rat caries model. Meanwhile, high-throughput sequencing was used to analyze the microbial diversity change of saliva samples of rats. The results showed that DMAEM monomer could inhibit the growth of the core microbiota biofilm, decrease the metabolic activity and the acid production, as well as reduce the ability of demineralization under acidic conditions. Moreover, the degree of caries in the DMAEM group was significantly reduced, and the diversity and the evenness of oral microecology in the rats were statistically higher. In summary, DMAEM monomer could respond to acidic environment, significantly inhibit the cariogenic ability of the 'core microbiome' of caries, and help to maintain the microecological balance of oral cavity.
Background:
Dental caries results from long-term acid production when sugar is metabolized by a bacterial biofilm, resulting in a loss of calcium and phosphate from the enamel. Streptococcus mutans is a type of acid-producing bacteria and a virulent contributor to oral biofilms. Conventional treatment options, such as cefazolin and ampicillin, have significant levels of bacterial resistance. Other topical agents, such as fluoride, tend to be washed away by saliva, resulting in low therapeutic efficacy.
Highlight:
This review aims to highlight the solubility issues that plague poorly water-soluble therapeutic agents, various novel polymeric, and lipid-based nanotechnology systems that aim to improve the retention of therapeutic agents in the oral cavity.
Conclusion:
In this review, different formulation types demonstrated improved therapeutic outcomes by enhancing drug solubility, promoting penetration into the deep layers of the biofilm, facilitating prolonged residence time in the buccal cavity, and reducing the emergence of drug-resistant phenotypes. These formulations have a strong potential to give new life to therapeutic agents that have limited physicochemical characteristics.
Previously, we studied the clearance rates of KCl from agarose gels positioned at different locations in the mouth, and showed that the rates were much slower than when clearance was into a well-stirred solution. We designed the present in vitro study to test the effect on KCl clearance of the velocity of a 0.1-mm-thick film of water flowing over an agarose gel of the same diameter and composition as those used in vivo. The thickness of the salivary film overlying dental plaque has been estimated to be about 0.1 mm, and we assumed that when clearance rates in vitro matched those found in vivo, velocities of the fluid film (in vitro) and the salivary film (in vivo) must be equal. On this basis, it was calculated in the present experiments that when salivary flow was unstimulated, the velocity of the salivary film at the level of the teeth varied between about 0.8 mm/min (upper-anterior buccal region) and 8.0 mm/min (lower-anterior lingual region). When salivary flow was stimulated, this was estimated to increase the velocity of the salivary film from 2 to 40 times, depending on the location in the mouth. It is postulated that the slow movement of the salivary film when flow is unstimulated allows for accumulation of diffusants from dental plaque, which reduces the concentration gradient for diffusion from plaque and prolongs the clearance time of such metabolic products as acid.
The thickness of decayed material and the size of the clinical openings of cavities were correlated with the initial pH and the pH response to glucose and phosphate buffer. Using visual and X-ray measurements, cavities were classified into the following types: (I) small clinical openings and thick layers of decay, (II) wide clinical openings and thick layers of decay, and (III) wide clinical openings and thin layers of decay. The three types of cavities had different mean initial pH values and responded differently to a 10% glucose solution. The average pH value of all Type I cavities was lowest both initially and during the 30 min period after glucose. Type III cavities under similar conditions had the highest average pH value. After isolation, 0.1 M phosphate buffer (pH 6.8) was added to cavities and Type III cavities were found to reach a pH of 6.8 in a shorter length of time than Types I and II. Following removal of the phosphate buffer, Type III cavities reverted to their initial pH values in a shorter length of time than the other cavity types.
Changes in plaque pH (Stephan curves) after sugar mouth rinses, observed by the method of Frostell [1970], may be used to test the effect of factors possibly related to caries. Relationships observed between the Stephan curves and the salivary responses (pH and flow rate) suggest that the pH of saliva is a major factor controlling plaque pH. Modification of the Stephan curve may be more readily achieved by increasing the neutralising action of the saliva than by altering the acid-producing potential of the plaque.Copyright © 1976 S. Karger AG, Basel
A system for the measurement of plaque pH in vivo has been developed, using an in-dwelling miniature glass electrode. The reliability of the electrode and the closeness of the experimental conditions to natural ones compared favourably with previous techniques for measuring plaque pH. The effect on plaque pH of sucrose and saccharin rinses, and a chlorhexidine mouthwash were studied. Continuous small, rapid fluctuations in the pH of both stimulated and resting plaques were consistently observed and larger changes of pH were noted on opening the mouth and swallowing.
The aim of this study was to assess the applicability of palladium touch microelectrodes, connected to battery-run pH meters, for in vivo plaque pH measurements in children. The pH was assessed in 20 7-year-old and in 19 14-year-old caries-active and caries-inactive rural Kenyan children. The resting pH was measured at non-carious interproximal and occlusal sites and in open dentine cavities. Independent repeated measurements were performed at given sites at intervals of 15 s and 5 min and on different days. The resting plaque pH varied widely among the children, and there was no significant difference between caries-active and caries-inactive groups. The most striking feature was the considerable erratic fluctuations of pH at a given site with time, both in resting and in sucrose-challenged plaque. These fluctuations were sensitively recorded by palladium touch microelectrodes. After a sucrose rinse, not all sites in the same mouth behaved in a similar fashion, and thus the classical 'Stephan curve' was not always apparent. In conclusion, the palladium touch microelectrodes are highly applicable for plaque pH measurements in children, even under extreme field conditions.
Recent studies have indicated that saliva in the mouth is present as a film only about 0.1 mm thick, and that this film moves at different rates (about 0.8 to 7.6 mm/min) in different regions of the oral cavity. The clearance rates of KCI, as a model diffusant, from agarose gels at different sites in the mouth have also been found to vary markedly, and it has been proposed that these variations are related to differences in the velocity of the salivary film.
A computer model has been developed for prediction of clearance half-times for substances diffusing from plaque of variable dimensions into a film of fluid 0.1 mm thick, moving at different velocities. The results show that over the range of velocities calculated to occur in the mouth, the clearance half-times are directly related to the length of plaque over which the fluid passes, and inversely related to the salivary film velocity. The predictions of the model are in good agreement with experimental results from a physical model. Tests were made of the predicted effect of salivary film velocity on the shape of the pH curve initiated by exposure of plaque to a saturated sucrose solution, followed by normal salivary clearance. With a low salivary film velocity, the fall in pH was greater and more prolonged. These results are relevant to the site-specificity of caries, since they imply that, given two plaque samples of identical area, depth, and microbial composition, the sample located in a region of the mouth where the salivary film velocity is lower will show a more extensive and prolonged pH fall after exposure to fermentable carbohydrate.