Factors affecting intra-oral pH - a review

Effect of gastric acids on the mechanical properties of conventional and CAD/CAM resin composites - An in-vitro study

OBJECTIVES

Dental erosion in patients with gastroesophageal reflux disease (GERD) is a current and frequent condition that may compromise the mechanical properties and clinical durability of resin-based composites (RBCs). This study assessed the mechanical properties of conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) RBCs subsequent to simulated gastric acid aging.

MATERIALS AND METHOD

Three conventional and three CAD/CAM composites were assessed. They were divided into an experimental group (exposed to simulated gastric acid aging) and a control group (no aging). Both groups were analyzed for Vickers microhardness (VHN), wear and flexural strength over a period of six months. The failure rate probability for each RBC was calculated through the Weibull cumulative distribution function (m). Statistical analysis was conducted using repeated measures ANOVA, 3-way ANOVA, a non-parametric Kruskal-Wallis and U Mann-Whitney tests (α = 0.05).

RESULTS

The mechanical properties of all the RBCs dropped significantly after aging (p < 0.05). Lower VHN and flexural strength values, along with greater wear values were evident in the experimental groups, though the effects of the treatment varied between RBCs. The Weibull m of all the RBCs decreased over time.

CONCLUSION

Conventional RBCs might show greater reduction in mechanical properties compared to CAD/CAM RBCs when exposed to gastric acid attack. Thus, CAD/CAM composites may represent a suitable choice for the treatment of patients presenting erosive issues.

Does salivary pH affect postoperative sore throat in the head-down position of general anesthesia?

BACKGROUND

Tracheal intubation sometimes causes postoperative sore throat (POST) due to laryngeal damage. However, clinical observations suggest that the environment of the oral cavity may also affect POST.

OBJECTIVE

The purpose of this study was to investigate whether salivary pH in the oral cavity affects POST.

METHODS

After obtaining ethical approval, informed consent was obtained from all patients. Patients who underwent surgery in the supine position were enrolled as the control group. Patients who underwent laparoscopic surgery in the head-down position were enrolled as the intervention group. Immediately before both groups of patients were anaesthetised, expelled saliva was collected, and salivary pH was measured. Immediately postoperatively, the same measurement was carried out before the patient regained consciousness. The primary outcome was the change in salivary pH. The secondary outcome was POST. In our study, POST was defined as pharyngeal and swallowing pain in the glossopharyngeal and superior laryngeal nerves. The normal distribution of pH was tested using the Shapiro-Wilk test followed by analysis using repeated-measurements and one-way analysis of variance. Statistical significance was set at p < .05.

RESULTS

A total of 62 patients were enrolled, of whom two were excluded based on the exclusion criteria. Salivary pH in the intervention group was significantly lower than that in the control group. Five patients had POST in the intervention group, whereas none had POST in the control group had POST.

CONCLUSION

Acidotic-shifted saliva is considered one of the causes of POST.

Novel Functional Dressing Materials for Intraoral Wound Care

Intraoral wounds represent a particularly challenging category of mucosal and hard tissue injuries, characterized by the unique structures, complex environment, and distinctive healing processes within the oral cavity. They have a common occurrence yet frequently inflict significant inconvenience and pain on patients, causing a serious decline in the quality of life. A variety of novel functional dressings specifically designed for the moist and dynamic oral environment have been developed and realized accelerated and improved wound healing. Thoroughly analyzing and summarizing these materials is of paramount importance in enhancing the understanding and proficiently managing intraoral wounds. In this review, the particular processes and unique characteristics of intraoral wound healing are firstly described. Up-to-date knowledge of various forms, properties, and applications of existing products are then intensively discussed, which are categorized into animal products, plant extracts, natural polymers, and synthetic products. To conclude, this review presents a comprehensive framework of currently available functional intraoral wound dressings, with an aim to provoke inspiration of future studies to design more convenient and versatile materials.

Sleep bruxism: The past, the present, and the future-evolution of a concept

BACKGROUND

The concept of sleep bruxism (SB) has evolved exponentially over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB, from the early 1960s through the present. The role of peripheral factors, such as dental occlusion, in the pathogenesis of SB has been discarded.

TYPES OF STUDIES REVIEWED

The authors searched several electronic databases (ie, PubMed, Google Scholar, Web of Science, Embase, and Ovid MEDLINE) for studies on bruxism. The search was conducted from January 1961 through May 2023 and yielded 4,612 articles, of which 312 were selected for comprehensive review after eliminating duplicates and nonfocused articles.

RESULTS

There has been an evident progressive shift from the role of peripheral factors, such as dental occlusion, to more central factors, such as the involvement of a central pattern generator as well as the autonomic nervous system, in the genesis of bruxing movements. There is continued robust interest in the dental community to elucidate the contributing factors involved in SB.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The neurophysiology of SB appears to be leaning more toward central rather than peripheral factors. There is increasing evidence of the role of the autonomic nervous system, genetics, and comorbidities in the genesis of SB. The scientific literature seems to refute the role of dental occlusion in the causation of bruxing movements. As per the literature, there has been a paradigm shift in the definition and genesis of SB and its possible dental implications and management, which also highlights the need for succinct scientific studies in this regard.

The influence of oral cavity physiological parameters: temperature, pH, and swelling on the performance of denture adhesives - in vitro study

BACKGROUND

The various physical and chemical conditions within the oral cavity are hypothesized to have a significant influence on the behavior of denture adhesives and therefore the overall comfort of denture wearers. As such, this study aims to understand the influence of oral cavity physiological parameters such as temperature (17 to 52 °C), pH (2, 7, 10), and denture adhesive swelling due to saliva (20-120%) on the behavior of denture adhesives. This study further aims to emphasize the need for a collective approach to modelling the in-situ behavior of denture adhesives.

METHODS

Rheological measurements were carried out using the Super Polygrip Ultra fresh brand denture adhesive cream to evaluate its storage modulus (G´) and loss modulus (G´´) values at a range of physiologically relevant temperatures, pH values, and degrees of swelling, to represent and characterize the wide variety of conditions that occur within the oral cavity.

RESULTS

Rheological data was recorded with respect to variation of temperature, pH, and swelling. Overall, it can be seen that the physiological conditions of the oral cavity have an influence on the rheological properties of the denture adhesive cream. Specifically, our data indicates that the adhesive's mechanical properties are weakly influenced by pH, but do change with respect to the temperature in the oral cavity and the swelling rate of the adhesive.

CONCLUSIONS

Our results suggest that the collective inter-play of the parameters pH, temperature and swelling ratio have an influence on the behavior of the denture adhesive. The results clearly highlight the need for developing a multi-parameter viscoelastic material model to understand the collective influence of physiological parameters on the performance of denture adhesives. Multi-parameter models can also potentially be utilized in numerically simulating denture adhesives using finite element simulations.

Formulation optimization and evaluation of oromucosal in situ gel loaded with silver nanoparticles prepared by green biosynthesis

Treating oral diseases remains challenging as API is quickly washed out of the application site by saliva turnover and mouth movements. In situ gels are a class of application forms that present sol-gel transition's ability as a response to stimuli. Their tunable properties are provided using smart polymers responsible for stimuli sensitivity, often providing mucoadhesivity. In this study, antimicrobial in situ gels of thermosensitive and pH-sensitive polymers loaded with silver nanoparticles were prepared and evaluated. The nanoparticles were prepared by green synthesis using Agrimonia eupatoria L. extract. According to the data analysis, the in situ gel with the most promising profile contained 15 % of Pluronic® F-127, 0.25 % of methylcellulose, and 0.1 % of Noveon® AA-1. Pluronic® F-127 and methylcellulose significantly increased the viscosity of in situ gels at 37 °C and shear rates similar to speaking and swallowing. At 20 °C, a behavior close to a Newtonian fluid was observed while being easily injectable (injection force 13.455 ± 1.973 N). The viscosity of the formulation increased with temperature and reached 2962.77 ± 63.37 mPa·s (37 °C). A temperature increase led to increased adhesiveness and rigidity of the formulation. The critical sol-gel transition temperature at physiological pH was 32.65 ± 0.35 °C. 96.77 ± 3.26 % of Ag NPs were released by erosion and dissolution of the gel after 40 min. The determination of MIC showed effect against E. coli and S. aureus (0.0625 mM and 0.5000 mM, respectively). The relative inhibition zone diameter of the in situ gel was 73.32 ± 11.06 % compared to gentamicin sulfate. This work discusses the optimization of the formulation of novel antibacterial in situ gel for oromucosal delivery, analyses the impact of the concentration of excipients on the dependent variables, and suggests appropriate evaluation of the formulation in terms of its indication. This study offers a promising dosage form for local treatment of oral diseases.

Nanoemulsion-Based Orodispersible Film Formulation of Guava Leaf Oil for Inhibition of Oral Cancer Cells

Among natural sources, guava leaf oil (GLO) has emerged as a potential anticancer agent. However, its limited water solubility poses a significant challenge for its use. Oil-in-water nanoemulsions are used to address the limitation of water solubility of GLO prior to its incorporation into orodipersible films. Nanoemulsions containing GLO:virgin coconut oil (VCO) at a ratio of 50:50 to 70:30 presented a small droplet size of approximately 50 nm and a relatively low zeta potential. GLO:VCO at a ratio of 70:30 was selected for incorporation into sodium alginate film at various concentrations ranging from 1% to 30% w/w. Tensile strength and elongation at break relied on the concentration of nanoemulsions as well as the internal structure of films. Fourier transform infrared spectroscopy revealed that GLO was compatible with sodium alginate. Film containing 2% w/w of nanoemulsions (2G_ODF) exhibited effective in vitro antioral cancer activity, with an IC50 of 62.49 ± 6.22 mg/mL; furthermore, its anticancer activity showed no significant difference after storage at 25 °C for 1 year. Moreover, 2G_ODF at IC60 arrested colony formation and cell invasion. There is also evidence that cell death occurred via apoptosis, as indicated by nuclear fragmentation and positive Annexin-V staining. These findings highlight the potential of orodispersible films containing GLO nanoemulsions as a prospective oral anticancer agent.

Association between salivary characteristics and tooth wear: A systematic review and meta-analysis

OBJECTIVE

Literature was systematically reviewed to identify salivary characteristics and their association with tooth wear.

DATA

A protocol was developed a priori (PROSPERO CRD42022338590). Established systematic review methods were used for screening, data extraction, and synthesis. Risk of bias and the certainty of evidence were assessed using the JBI tools and GRADE, respectively. Direct and indirect association between tooth wear and salivary components and characteristics were assessed.

SOURCES

MEDLINE, Embase, SCOPUS, Web of Science, CINAHL, and additional sources were searched.

STUDY SELECTION

Studies reporting salivary characteristics in patients with tooth wear or models thereof were included. Animal and in-vitro studies and case reports were excluded.

RESULTS

One-hundred eleven studies were included. Qualitative analyses showed a negative association between tooth wear and salivary pH and flow rate in many studies. The higher the study size the higher the chances that an association with pH and flow rate was found. Xerostomia, buffer capacity and salivary consistency/viscosity had also some degree of association with tooth wear in fewer studies. Associations with the 39 salivary components were scarcer. Random effects meta-analyses (7 studies) showed that pH levels in stimulated whole saliva were lower in patient with tooth wear compared to controls (-0.07 [-0.10 to -0.04]). However, there was not enough evidence to establish a quantitative association with flow rate. The general risk of bias was unclear and the certainty of evidence was low or very low. A large diversity of methodologies limited the inclusion of all studies in quantitative synthesis.

CONCLUSION

From all potential risk factors, stimulated whole saliva pH showed a negative association, both quantitatively and qualitatively with tooth wear, indicating potential usefulness of pH monitoring in these patients. Moreover, associations between flow rate and tooth wear were observed qualitatively. However, in both cases the risk of bias was mostly unclear, and the certainty of evidence was low. No causal associations could be observed.

CLINICAL SIGNIFICANCE

Tooth wear is a prevalent condition that may lead to functional or esthetic impairments and pain. Knowing the potential risk factors like salivary pH or flow rate and their dynamics could be relevant during tooth wear monitoring and to intervene accordingly, especially in conditions like gastroesophageal reflux disease.

Sensors for in situ monitoring of oral and dental health parameters in saliva

OBJECTIVES

The oral cavity is an easily accessible unique environment and open system which is influenced by the oral fluids, microbiota, and nutrition. Little is known about the kinetics and dynamics of metabolic processes at the intraoral surfaces. Real-time monitoring of salivary biomarkers, e.g., glucose, lactate, fluoride, calcium, phosphate, and pH with intraoral sensors is therefore of major interest. The aim of this review is to overview the existing literature for intraoral saliva sensors.

MATERIALS AND METHODS

A comprehensive literature search was performed to review the most relevant studies on intraoral saliva sensor technology.

RESULTS

There is limited literature about the in situ saliva monitoring of salivary biomarkers. Bioadhesion and biofouling processes at the intraoral surfaces limit the performances of the sensors. Real-time, long-term, and continuous intraoral measurement of salivary metabolites remains challenging and needs further investigation as only few well-functioning sensors have been developed until today. Until now, there is no sensor that measures reliably beyond hours for any analyte other than glucose.

CONCLUSIONS

Saliva's complex and dynamic structure as well as bioadhesion are key challenges and should be addressed in the future developments. Consequently, more studies that focus particularly on biofouling processes and interferential effects of the salivary matrix components on sensor surfaces are required.

CLINICAL RELEVANCE

By monitoring fluids in the oral cavity, as the entrance to the digestive system, extensive information can be obtained regarding the effects of foods and preventive agents on the oral microbiota and the tooth surfaces. This may lead to a better understanding of strategies to modulate oral and general health.

Additively manufactured Ti-29Nb-21Zr shows improved oxide polarization resistance versus Ti-6Al-4V in inflammatory simulating solution

Retrieval studies in the past two decades show severe corrosion of titanium and its alloys in orthopedic implants. This damage is promoted by mechanically assisted crevice corrosion (MACC), particularly within modular titanium-titanium junctions. During MACC, titanium interfaces may be subject to negative potentials and reactive oxygen species (ROS), generated from cathodic activation and/or inflammation. Additive manufacturing (AM) may be able to produce new, corrosion-resistant titanium alloys and admixtures that are less susceptible to these adverse electrochemical events. In this study, we characterize the impedance and corrosion properties of three new AM titanium materials, including Ti-6Al-4V with added 1% nano-yttria stabilized ZrO2 , admixed Ti-29Nb-21Zr, and pre-alloyed Ti-29Nb-21Zr. We aim to elucidate how these materials perform when subjected to high ROS solutions. We include conventionally and additively manufactured Ti-6Al-4V in our study as comparison groups. A 0.1 M H2 O2 phosphate-buffered saline (PBS) solution, simulating inflammatory conditions, significantly increased biomaterial OCP (-0.14 V vs. Ag/AgCl) compared to PBS only (-0.38 V, p = .000). During anodic polarization, Ti-6Al-4V passive current density more than doubled from 1.28 × 10-7 to 3.81 × 10-7  A/cm2 when exposed to 0.1 M H2 O2 . In contrast, Ti-29Nb-21Zr passive current density remained relatively unchanged, slightly increasing from 7.49 × 10-8 in PBS to 9.31 × 10-8 in 0.1 M H2 O2 . Ti-29Nb-21Zr oxide polarization resistance (Rp ) was not affected by 0.1 M H2 O2 , maintaining a high value (1.09 × 106 vs. 1.89 × 106  Ω cm2 ), while Ti-6Al-4V in 0.1 M H2 O2 solution had significantly diminished Rp (4.38 × 106 in PBS vs. 7.24 × 104  Ω cm2 in H2 O2 ). These results indicate that Ti-29Nb-21Zr has improved corrosion resistance in ROS containing solutions when compared with Ti-6Al-4V based biomaterials.

The pH of Drinking Water and Its Effect on the pH of Urine

AIM

The aim was to determine whether urine pH changed or not with different pH values of drinking water. With the results obtained from animal studies, comments can be made about the effect of water with different pH levels that people drink on kidney stones.

METHOD

A total of 24 Wistar Albino rats were divided into three groups containing eight rats each: the first group was given water with pH 5.5, the second group was given water with pH 7 and the third group was given water with pH 8.2 in the same environment and conditions during 13 days. All rats consumed water in line with their natural feeding habits. All rats had urine pH measurements performed and recorded every day at the same time. The groups were later compared in terms of daily pH values.

RESULTS

When daily urine pH values were compared, there were statistically significant differences between pH measurements on the first, fourth and seventh day (p=0.02, p=0.017 and p=0.007, respectively). When first-day values are compared with post-hoc analyses, the urine pH in Group 2 was identified to be lower compared to Group 1 and Group 3 (p<0.001). When the fourth-day values were assessed, the urine pH of Group 2 was observed to be higher than Group 1 and Group 3 (p<0.001). On the seventh day, Group 3 had higher urine pH compared to the other groups (p<0.001).

CONCLUSION

The variation in drinking water pH does not directly change urine pH; however, it causes a change in the urine pH on different days.

The Effect of Gastric Acid on the Surface Properties of Different Universal Composites: A SEM Study

The aim of this study is to compare surface roughness and microhardness changes of three monochromatic (Omnichroma, Vittra Unique, and Charisma Diamond One) and three universal shade (Neo Spectra ST, G-ænial A'CHORD, and Nova Compo C) resin composites after exposure to simulated gastric acid. A total of 144 disc-shaped specimens (24 discs of each composite resin) were prepared using plexiglass molds (R = 5 mm × h = 2 mm) for evaluation from each material. Specimens of each material were divided into two main groups for the evaluation of the microhardness and surface roughness and also two subgroups for 7- and 14-day exposures to simulated gastric acid. Initial microhardness and surface roughness measurements of all samples were measured before immersion (T1) followed by exposing the samples to simulated gastric acid for 7 days (T2) and 14 days (T3), and then, the microhardness and roughness measurements were repeated. Randomly selected specimens of each material for each of the time intervals (T1, T2, and T3) were evaluated with scanning electron microscopy (SEM). One-way ANOVA revealed that the surface roughness and hardness values of all tested composite resin restorative materials show no statistically significant difference for the initial (T1) value (p > 0.05). Regarding the 7^th day (T2) and 14^th day (T3) surface roughness and microhardness value of all composites, there are statistically significant differences between the groups (p < 0.05), while there was no statistically significant difference between the surface hardness reduction percentage between the time intervals (p > 0.05). As a result of this in vitro study, increase in surface roughness and decrease in microhardness of the tested universal composite materials when exposed to simulated gastric acid were statistically significant.

Vinegar: A functional ingredient for human health

Vinegar is a well-known natural food product derived from alcoholic and subsequently acetous fermentation of carbohydrate-rich foods. Vinegar is widely used in the food industry; domestically for pickling vegetables and fruits, and as an ingredient in condiments like salad dressings, ketchups, and mayonnaise; and traditionally as a food seasoning and preservative. Historically, vinegar has been used for medicinal purposes such as a cure for stomach aches, wounds, burns, rashes, and oedema conditions. Different types of vinegar are found worldwide such as rice, black, balsamic, grain, and fruit vinegars. These are produced from different raw materials, and using different fermentation methods to give unique tastes and flavours. Vinegar, while enhancing physiological functions such as lipid metabolism, blood glucose level control, and body weight management, also possesses anticancer, antibacterial, antioxidant, and anti-infection properties. It is considered as a good source material for many bioactive compounds including organic acids, melanoidins, polyphenols, ligustrazine, and tryptophol. The pharmacological and metabolic benefits of vinegar are believed to be due to these bioactive compounds present in vinegar. Acetic acid (CH3COOH) is the essential component of vinegar; it is slightly volatile and has a strong and sour aroma and flavour. Regular consumption of vinegar-containing foods is considered important for keeping many life-style related diseases like diabetes, hypertension, hyperlipidaemia, cancers, and obesity in check. Therefore, the present review aims at highlighting the health benefits associated with vinegar consumption for the physiological well-being of an individual.

Assessment of the Erosive Potential of Mineral Waters in Bovine Dental Enamel

Background:

High intake of acidic foods and beverages has been often associated with the onset of dental erosive wear.

Objetive:

This study in vitro assessed the pH of different mineral waters marketed in Brazil and their effects on the properties and surface of dental enamel.

Methods:

Forty-eight bovine incisor specimens were divided into four groups (n=12): CG-control group, PeG-Perrier, PrG-Prata, and SLG-São Lourenço. The immersion cycles were performed after analysis of the pH of the waters, for 5 days (5 minutes in mineral water and 60 minutes in artificial saliva). Knoop micro-hardness was assessed by means of three indentations with a load of 50kgf for 15 seconds, and surface roughness with a cut off of 0.25mm. The data were analysed using Student's t-test, ANOVA, and Tukey test, with a significance level of 5%.

Results:

The groups of waters with lower pH (Perrier® and São Lourenço®) exhibited a reduction in Knoop micro-hardness (p<0.0001) and an increase in surface roughness (p=0.04 and p=0.004, respectively). The Prata water group did not exhibit significant changes in Knoop micro-hardness (p=0.07) and surface roughness (p=0.26).

Conclusion:

Mineral waters with a pH below the critical value can lead to a reduction in surface hardness and roughness in the bovine enamel.

Soft drinks and dental erosion during pediatric age: a clinical investigation

BACKGROUND

Dental erosion is an irreversible condition of loss of teeth hard tissues caused by intrinsic or extrinsic acids attack, without bacterial involvement. Common soft drinks have an acid pH and they release hydrogen ions and act as chelating agents, dissolving teeth mineral component. The aim of the study was to investigate the correlation between the consumption of soft drinks in children and the degree of dental erosion.

METHODS

A questionnaire of 15 multiple choice questions was addressed to the parents of the 231 children needing different dental treatments. Responses were compared with the level of dental erosion of their child, that was clinically investigated using the Basic Erosive Wear Examination (BEWE) index.

RESULTS

About 26.8% of subjects fall into a high-risk category of dental erosion while 24.2% in a low risk level. Socioeconomic status and oral hygiene habits are able to affect the degree of dental erosion. Toothpastes containing fluoride have not proved effective in preventing this phenomenon and no significant correlations were found between the type of toothbrush used and its frequency of use.

CONCLUSIONS

It is necessary to apply preventive measures such as information on the processes and causes of erosion, instruction about right home oral hygiene maneuvers and the possible use of specific products, to avoid the development of problems related to severe dental wear.

Experimental pastes containing niobophosphate and 45S5 bioactive glasses for treatment of dentin hypersensitivity: dentin permeability and tubule obliteration

OBJECTIVES

This study tested the ability of bioactive pastes containing niobophosphate and 45S5 glasses to reduce dentin permeability and to obliterate dentinal tubules, as a mean of reducing human dentin hypersensitivity.

MATERIALS AND METHODS

Experimental pastes with concentrations of 10, 20, and 30 wt% of two bioactive glasses (45S5 or niobophosphate [NbG]) were formulated. A paste without bioactive glass (placebo) and a commercial paste (Nano P, FGM) were used as controls. Forty dentin disc specimens were obtained from caries-free extracted third human molars and divided in 8 groups (n = 5). Percentage of permeability (%Lp) was assessed in a dental permeability machine considering hydraulic conductance, immediately after pastes application and at day 7, day 14, and day 21. The precipitates formed on the surface of the dentin discs (and dentinal tubules) were analyzed by SEM/EDS and micro-Raman spectra. Data of dentin permeability (%) 2-way repeated-measures (ANOVA) and Holm-Sidak post-tests (α = 0.05). Dentinal tubule obliteration was visually (and elemental) evaluated and descriptively reported.

RESULTS

The experimental bioactive glass pastes containing NbG and 45S5, regardless of the concentration, reduced dentin permeability in comparison with pastes without bioactive glasses (P < 0.05). The formulated placebo and commercial paste did not reduce permeability over time (P < 0.05). SEM/EDS and micro-Raman analyses showed that both type of bioactive pastes (NbG or 45S5-based) presented mineral precipitates obliterating the dentinal tubules at day 21. NbG seems to offer a better initial effect than 45S5, while at 21 days there is no difference between both glasses.

CONCLUSION

Experimental bioactive pastes containing NbG and 45S5 (at concentrations of 10%, 20%, or 30%) have potential to reduce dentin permeability (over time) in comparison with pastes without bioactive glasses; and this occurs on behalf of obliteration of dentinal tubules by microparticle and precipitate formation.

CLINICAL RELEVANCE

Bioactive pastes containing NbG and 45S5 may benefit patients presenting dentin hypersensitivity, because these pastes can start acting fast after application and maintain their action up to 21 days.

The Suitability of Questionnaires for Exploring Relations of Dietary Behavior and Tooth Wear

Tooth wear is a relevant oral health problem, especially at a young age. Although ongoing acid exposures may contribute to tooth wear, the role of acidic dietary components in this context remains unclear. To date, in tooth wear studies, dietary behavior has been assessed using traditional questionnaires, but the suitability of this approach has not been investigated so far. In our longitudinal study, we followed 91 participants (21.0 ± 2.2 years) over a period of 1 year (373 ± 19 days) and monitored tooth wear with an intraoral scanner. At baseline (T0) and at the end (T1), we assessed dietary behavior with questionnaires asking about the consumption frequencies of acidic dietary components and the acid taste preferences. Complete data were available from 80 subjects. The consumption frequencies of T0 and T1 correlated weakly to moderately. Taste preferences seem to be a more consistent measure, but there was predominantly no significant correlation with the corresponding consumption frequencies. None of the dietary parameters showed a significant relation with tooth wear. The suitability of dietary questionnaires to assess tooth-relevant dietary behavior seems to be limited.

Novel impacts of saliva with regard to oral health

The maintenance of balanced oral homeostasis depends on saliva. A readily available and molecularly rich source of biological fluid, saliva fulfills many functions in the oral cavity, including lubrication, pH buffering, and tooth mineralization. Saliva composition and flow can be modulated by different factors, including circadian rhythm, diet, age, drugs, and disease. Recent events have revealed that saliva plays a central role in the dissemination and detection of the SARS-CoV-2 coronavirus. A working knowledge of saliva function and physiology is essential for dental health professionals.

Enhancing resin-dentin bond durability using a novel mussel-inspired monomer

Numerous approaches have been developed to improve the resin-dentin bond performance, among which the bio-application of mussel-derived compounds have drawn great attention recently. To assess the performance of N-(3,4-dihydroxyphenethyl)methacrylamide (DMA), a mussel-derived compound, as a functional monomer in dental adhesive, its potential property to cross-link with dentin collagen and polymerize with adhesive will first be evaluated by transmission electron microscopy (TEM), attenuated total reflectance technique of Fourier transform infrared (ATR-FTIR), and atomic force microscopy (AFM) via Peakforce QNM mode. After validating the influence of DMA on collagen and adhesive separately, the overall performance of DMA/ethanol solution as a primer in dentin bonding was examined using micro-tensile bond strength (μTBS) testing, fracture pattern observation, and nanoleakage evaluation both immediately and after 10,000 times thermocycling aging. The inhibitory effect of DMA on endogenous metalloproteinases (MMPs) was evaluated by in situ zymography using confocal laser scanning microscopy (CLSM) and the cytotoxicity of DMA was evaluated using cell counting kit-8. Results demonstrated that DMA successfully cross-linked with dentin collagen via non-covalent bonds and had no influence on the polymerization and mechanical properties of the adhesive. Furthermore, even after 10,000 times thermocycling aging, the μTBS and nanoleakage expression of the DMA-treated groups showed no significant change compared with their immediate values. In situ zymography revealed reduced endogenous proteolytic activities after the application of DMA, and no cytotoxicity effect was observed for DMA concentration up to 25 ​μmol/L. Thus, DMA could be used as a novel, biocompatible functional monomer in dentin bonding.

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DMA acts as a functional monomer in dentin bonding system with high biocompatibility.

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DMA connects the adhesive and collagen network to resist various external attacks.

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DMA/ethanol inhibits the activity of MMPs and improve resin-dentin bond durability.

HPV Lesions and Other Issues in the Oral Cavity Treatment and Removal without Pain

Due to different oral and dental conditions, oral mucosa lesions such as those caused by the human papilloma virus and temporomandibular joint pathologies often have to be treated by surgical, ablative or extractive procedures. The treatment and control of pain and inflammation during these procedures is essential to guarantee the patient's well-being. For the foregoing reason, a hydrogel based on sodium alginate and hyaluronic acid containing 2% of ketorolac tromethamine has been developed. We characterized it physically, mechanically and morphologically. The rheological results suggest that the formulation can be easily and gently applied. Ex vivo permeation studies show that Ketorolac Tromethamine is able to penetrate through the buccal and sublingual mucosae, in addition to being retained in the mucosae's structure. Through an in vitro test, we were able to evaluate the role that saliva plays in the bioavailability of the drug, observing that more than half of the applied dose is eliminated in an hour. The histological and cytotoxic studies performed on pigs in vivo showed the excellent safety profile of the formulation, as well as its high tolerability. In parallel, a biomimetic artificial membrane (PermeaPad^®) was evaluated, and it showed a high degree of correlation with the oral and sublingual mucosa.

Potential of Salivary Biomarkers in Autism Research: A Systematic Review

The diagnostic process for autism spectrum disorders (ASD) is based on a behavioral analysis of the suspected individual. Despite intensive research, no specific and valid biomarker has been identified for ASD, but saliva, with its advantages such as non-invasive collection, could serve as a suitable alternative to other body fluids. As a source of nucleic acid of both human and microbial origin, protein and non-protein molecules, saliva offers a complex view on the current state of the organism. Additionally, the use of salivary markers seems to be less complicated not only for ASD screening but also for revealing the etiopathogenesis of ASD, since enrolling neurotypical counterparts willing to participate in studies may be more feasible. The aim of the presented review is to provide an overview of the current research performed on saliva in relation to ASD, mutual complementing, and discrepancies that result in difficulties applying the observed markers in clinical practice. We emphasize the methodological limitations of saliva collection and processing as well as the lack of information regarding ASD diagnosis, which is critically discussed.

Interaction between properties of commercial Australian honey and saliva: in vitro exploratory study of a potential mechanism in the treatment of oral mucositis

OBJECTIVES

Oral mucositis is a debilitating oncology treatment side effect, with honey identified as a viable management option due to established wound-healing abilities. However, effects of saliva on properties attributed to honey's wound-healing abilities is unknown. Therefore, this study aimed to identify interactions between saliva, and antioxidant characteristics and pH of honey.

METHODS

Saliva was collected from 15 healthy participants (Females n=9; mean age=34.1 ± 11.2 years). Centrifuged salivary supernatant, whole saliva, and water were independently used to dilute commercial Australian honeys (n=42). Antioxidant characteristics (DPPH and FRAP) and pH of diluted honeys were analysed, and differences between dilution conditions were determined.

RESULTS

Honey and saliva dilutions increased antioxidant characteristics compared to water, and addition of honey to saliva reduced pH compared with saliva alone. There were significant differences between dilutions for FRAP and pH, and water and salivary conditions for DPPH (p<0.001). No difference was observed between salivary conditions for DPPH (p=0.931), suggesting smaller cells remaining in the supernatant possess antioxidant abilities. However, differences observed for FRAP suggest precipitable molecules, including epithelial and food debris, could provide additional antioxidant power.

CONCLUSIONS

The addition of saliva to honey may support properties attributed to honey's wound-healing abilities and should be considered in the context of oral mucositis management.

The Impact of Carbohydrate Quality on Dental Plaque pH: Does the Glycemic Index of Starchy Foods Matter for Dental Health?

Sugary carbohydrate foods have long been associated with increased risk of dental caries formation, but the dental health impact of starchy carbohydrates, particularly those with a high glycemic index (GI), has not been well examined.

AIM

To investigate the effect of different starchy foods varying in their GI, on acute changes in dental plaque pH.

METHODS

In a series of sub-studies in healthy adults, common starchy carbohydrate foods, including white bread, instant mashed potatoes, canned chickpeas, pasta, breakfast cereals, white rice, and an oral glucose solution were consumed in fixed 25 g available carbohydrate portions. The change in dental plaque pH was assessed postprandially over 1 h and capillary plasma glucose was measured at regular intervals over 2 h.

RESULTS

Higher GI starchy foods produced greater acute plaque pH decreases and larger overall postprandial glucose responses compared to lower GI starchy foods (white bread compared with canned chickpeas: -1.5 vs. -0.7 pH units, p = 0.001, and 99 ± 8 mmol/L min vs. 47 ± 7 mmol/L min, p = 0.026). Controlling for other food factors (food form and nutritional composition), lower GI versions of matched food pairs produced smaller plaque pH excursions compared to higher GI versions of the same food. Using linear regression analysis, the GI value of starchy carbohydrate foods explained 60% of the variation in maximum plaque pH nadir and 64% of the variation in overall acute dental plaque pH excursion (p < 0.01).

CONCLUSION

The findings imply that starchy foods, in particular those with a higher GI, may play a role in increasing the risk of dental caries.

The application of novel mussel-inspired compounds in dentistry

OBJECTIVE

To give a current review of the mechanism of mussel adhesion, the application of mussel-inspired compounds in dentistry and the challenges associated with clinical application.

METHODS

Inspired by the wet adhesion property of 3,4-dihydroxyphenol-l-alanine (Dopa) in mussel plaques, various chemical compounds have been synthesized to mimic the mussel as an adhesion model for medical applications. Similar to mussels in the marine environment, dental materials in the oral environment have to endure long-term water hydrolysis, mechanical stress and other chemical challenges. These challenges have influenced an increasing number of studies that are exploring the translation of mussel-inspired adhesion to clinical applications. Therefore, this review discusses the mussel adhesion chemistry and its related application in dentistry.

RESULTS

Mussel-inspired compounds have achieved relatively acceptable performances in various dental fields, including surface coating, metal ions chelation, dentin bonding and mucosal adhesion. However, two practical problems remain to be comprehensively addressed, namely the protection of catechol groups from oxidation, and the feasibility for clinical application.

SIGNIFICANCE

The mussel's wet adhesion ability has attracted much research interest in the dental field because of its properties of moisture-resistant adhesion and surface coating. Despite the emergence of several mussel-inspired compounds in recent years, a comprehensive and timely review of their applications in dentistry is lacking. Therefore, the current review hopes to provide valuable information around the application of mussel-inspired compounds in dentistry with their pros and cons discussed.

Health Promoting Properties of Cereal Vinegars

Vinegar has been used for its health promoting properties since antiquity. Nowadays, these properties are investigated, scientifically documented, and highlighted. The health benefits of vinegar have been associated with the presence of a variety of bioactive components such as acetic acid and other organic acids, phenolic compounds, amino acids, carotenoids, phytosterols, vitamins, minerals, and alkaloids, etc. These components are known to induce responses in the human body, such as antioxidant, antidiabetic, antimicrobial, antitumor, antiobesity, antihypertensive, and anti-inflammatory effects. The diversity and levels of bioactive components in vinegars depend on the raw material and the production method used. Cereal vinegars, which are more common in the Asia-Pacific region, are usually made from rice, although other cereals, such as millet, sorghum, barley, malt, wheat, corn, rye, oats, bran and chaff, are also used. A variety of bioactive components, such as organic acids, polyphenols, amino acids, vitamins, minerals, alkaloids, melanoidins, butenolides, and specific compounds such as γ-oryzanol, tetramethylpyrazine, γ-aminobutyric acid, etc., have been associated with the health properties of cereal vinegars. In this work, the bioactive components and the related health effects of cereal vinegars are reviewed, and the most recent scientific literature is presented and discussed.

Evidence That Daily Vinegar Ingestion May Contribute to Erosive Tooth Wear in Adults

Vinegar ingestion at mealtime is gaining popularity for its antiglycemic effects; however, it is among the most acidic consumable substances. This study examined tooth wear in healthy adults participating in an 8-week randomized trial examining the effect of daily vinegar ingestion on insulin sensitivity and visceral fat reduction. Twice daily participants consumed a vinegar drink (two tablespoons vinegar in a cup of water; 3.6 g acetic acid) or a commercial vinegar pill (control, 0.045 g acetic acid) at mealtime. Participants were screened for dental erosion using the basic erosive wear examination (BEWE) by a blinded registered dental hygienist at trial baseline and week 8. Mean BEWE scores did not change in the control group but increased 18% in the vinegar group over the 8-week study (P = .038). Given the current popularity of vinegar as a medicinal agent, practitioners should caution patients who utilize this strategy on the possibility of erosive tooth wear. Trial registration: This trial was registered at ClinicalTrials.gov (NCT03577834) on July 5, 2018 and the institutional review board at Arizona State University provided ethical approval (STUDY00005418).

Bond strength of commercial veneering porcelain to experimental cast Ti-Cr alloy

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations.

Laryngopharyngeal reflux, gastroesophageal reflux and dental disorders: A systematic review

Objectives

To investigate the role of gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) in the development of dental disorders.

Methods

The first outcome was review of the role of reflux in the development of dental disorders in adults. The second outcome was review of the potential pathophysiological mechanisms underlying the association between reflux and dental disorders. Three investigators screened publications for eligibility and exclusion based on predetermined criteria through a literature search conducted on PubMed, Cochrane Library, and Scopus according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

Results

From 386 publications, 24 studies were kept for analysis. Objective approaches were used in 16 studies to confirm GERD diagnosis. Pharyngeal reflux episodes (LPR) were considered in 2 studies. No study considered nonacid reflux. The study results supported a higher prevalence of dental erosion and caries in reflux patients compared with healthy individuals. Patients with dental erosion have a higher prevalence of reflux than controls. The pathophysiological mechanisms would involve changes in the saliva physiology. No study investigated the microbiota modifications related to reflux although the findings are supporting the critical role of microbiota change in the development of dental disorders. There is an important heterogeneity between studies about diagnostic methods and clinical outcome evaluation.

Conclusion

The involvement of reflux in the development of dental disorders is not formally demonstrated and requires future investigations considering pharyngeal acid and nonacid reflux episodes and in particular their potential impact on oral microbiota.

Factores de riesgo de la atrición dental severa: un estudio de casos y controles

Objetivo: identificar los factores de riesgo de la atrición dental severa en pacientes que acudieron a instituciones de atención odontológica, públicas y privadas, de la ciudad de Cuenca, Ecuador. Materiales y métodos: fueron analizados 237 pacientes adultos, 79 casos con atrición dental grados 2, 3 y 4, según el índice de Smith y Knight, y 158 controles con atrición grados 0 y 1. Se realizó un examen clínico y fotográfico para determinar la relación entre la atrición dental y factores como edad, sexo, procedencia, número de dientes residuales, pH salival y bruxismo. Resultados: los pacientes mayores de 25 años (OR= 2,47 IC= 1,41 – 4,35 X2= 10,21 p= 0,001), con menos de 20 dientes en boca (OR= 4,95 IC= 1,47 – 16,62 X2= 7,97 p= 0,004) y con bruxismo (OR= 2,64 IC= 1,45 – 4,81 X2= 10,49 p= 0,001) tienen más probabilidades de presentar atrición dental severa. Luego de una regresión logística binaria se confirmó dicha relación: pacientes mayores de 25 años (OR= 2,03 IC= 1,08 – 3,818) con menos de 20 dientes en boca (OR= 3,90 IC= 1,07 – 14,19) y con bruxismo (OR= 3,22 IC= 1,70 – 6,10); sin embargo, se observó una capacidad predictora muy baja de la variables ajustadas según el R–cuadrado de Cox y Snell (0,123) y el R–cuadrado de Nagelkerke (0,172). Conclusiones: edad avanzada, menor cantidad de dientes en boca y bruxismo aumentaron la posibilidad de presentar atrición dental severa en los pacientes analizados. Mientras que el sexo masculino, la procedencia rural y el pH salival crítico (menor a 6) no se comportaron como factores de riesgo

Aspirin is associated with low oral pH levels and antacid helps to increase oral pH

Objective

Aspirin is a commonly used medicine for primary and secondary prevention of cardiovascular diseases. It is an acidic medicine associated with gastric irritation and acid reflux, which in turn can lead to low oral pH levels. Therefore, it is important to understand the association between aspirin and oral pH levels in order to achieve an optimum oral health condition among patients who take aspirin on prescription.

Results

Out of 373 patients, 162 (44%) were males and 245 (66%) were on aspirin. 71% of aspirin taking patients and 29% of non-aspirin taking patients had oral pH less than 6.5 (P < 0.01). Aspirin showed a significant association with low oral pH levels (odds ratio = 1.91, 95% CI 1.23–2.99, P < 0.01). 78 patients were given antacids and followed up for 4 weeks, 63 of them (81%) showed an improvement in oral pH and the improvement was marked in the group who had oral pH between 5.5–6.0 compared to the group who had oral pH between 6.0–6.5 (P = 0.03). The results show that aspirin therapy is associated with low oral pH and administration of an antacid with aspirin helps to increase the oral pH level.

Real-Time Metabolic Interactions between Two Bacterial Species Using a Carbon-Based pH Microsensor as a Scanning Electrochemical Microscopy Probe

We have developed a carbon-based, fast-response potentiometric pH microsensor for use as a scanning electrochemical microscopy (SECM) chemical probe to quantitatively map the microbial metabolic exchange between two bacterial species, commensal Streptococcus gordonii and pathogenic Streptococcus mutans. The 25 μm diameter H+ ion-selective microelectrode or pH microprobe showed a Nernstian slope of 59 mV/pH and high selectivity against major ions such Na+, K+, Ca2+, and Mg2+. In addition, the unique conductive membrane composition aided us in performing an amperometric approach curve to position the probe and obtain a high-resolution pH map of the microenvironment produced by the lactate-producing S. mutans biofilm. The x-directional pH scan over S. mutans also showed the influence of the pH profile on the metabolic activity of another species, H2O2-producing S. gordonii. When these bacterial species were placed in close spatial proximity, we observed an initial increase in the local H2O2 concentration of approximately 12 ± 5 μM above S. gordonii, followed by a gradual decrease in H2O2 concentration (>30 min) to almost zero as lactate was produced, and a subsequent decrease in pH with a more pronounced metabolic output of S. mutans. These results were supported by gene expression and confocal fluorescence microscopic studies. Our findings illustrate that H2O2-producing S. gordonii is dominant while the buffering capacity of saliva is valid (∼pH 6.0) but is gradually taken over by S. mutans as the latter species slowly starts decreasing the local pH to 5.0 or less by producing lactic acid. Our observations demonstrate the unique capability of our SECM chemical probes for studying real-time metabolic interactions between two bacterial species, which would not otherwise be achievable in traditional assays.

Salivary Immune and Metabolic Marker Analysis (SIMMA): A Diagnostic Test to Predict Caries Risk

By using ELISA and colorimetric tests, we have measured 25 compounds in individuals with and without dental caries at different time points of dental biofilm formation and time of the day. We find that some compounds appear to be affected by circadian rhythms, others by dental plaque maturity, and others show constant values during a 24 h period. Using univariate analysis and cross-validation techniques, we have selected six components measured at specific time points that maximize the diagnostic separation of health and disease conditions. Two out of the six selected compounds are related to immune competence, another two to the adhesion capacity of micro-organisms, and another two to acid production or pH buffering. We conclude that, in order to design a robust caries risk test, the time of saliva sampling must be standardized and biomarkers from different categories must be included. The preliminary data shown in this paper provide a proof of principle of a caries risk test based on risk-associated categories. Thus, the test will provide not only a general caries risk assessment, but also the likely biological origin of that risk, namely: immune imbalance, and/or a tendency to adhesion of cariogenic organisms, and/or a lack of acid buffering. When tested longitudinally and validated in larger cohorts, this could open the possibility to develop preventive and personalized treatments.

Halitosis Assessment and Changes in Volatile Sulfur Compounds After Chewing Gum: A Study Performed on Dentistry Students

OBJECTIVE

The objective of this study is to estimate the prevalence of halitosis (with subjective and objective methods), evaluate the immediate effect of chewing gum on volatile sulfur compounds (VSCs), assess the perception of halitosis by dentistry students, and estimate the distribution of positive and negative frequencies, when comparing objective and subjective methods for the diagnosis of halitosis.

METHODS

The study was performed on a sample of dentistry students attending the Faculty of Medicine and Health Sciences at the University of Barcelona. A questionnaire about halitosis perception was provided and a clinical examination, organoleptic test (OT), and gas chromatography were performed to determine the presence of halitosis. The subjects were also given chewing gum to modify their breath, and gas chromatography was carried out to evaluate possible changes in VSCs.

RESULTS

The sample comprised 80 individuals. Twenty-seven (33.75%) self-perceived halitosis during the period of evaluation; the OT was positive in 38 subjects (47.5%); and individuals positive for halitosis on gas chromatography were distributed as follows: H₂S in 25 (31.25%), CH₃SH in 28 (35%), and (CH₃)₂S in 70 individuals (87.5%). A statistical difference before and after chewing gum (P < .05) was found for each VSC; a difference in frequencies was observed between the variable OT and H₂S (P < .05) and between the OT and (CH₃)₂S (P < .001). There was no significant difference (P > .05) between the positive and negative frequencies retrieved between the variable OT and CH₃SH and between the OT and the student's halitosis perception.

CONCLUSION

Prevalence of halitosis in the studied sample is high, considering that it comprised healthy individuals. The relationship between the OT and gas chromatography is not completely established. Chewing gum could be considered a therapeutic alternative to decrease or neutralize the amount of VSCs present in oral breath.