Dentin Sensitivity Research Articles

Self-propelled bioglass janus nanomotors for dentin hypersensitivity treatment.

Dentin hypersensitivity treatment is not always successful owing to the exfoliation of the blocking layer. Therefore, efficiently delivering a desensitization agent into the dental tubule is critical. Nanomotors are widely used as in vivo drug delivery systems owing to their strong power and good biocompatibility. Herein, we report a kind of self-propelled bioglass Janus nanomotor with a Pt motion unit (nBGs@Pt) for application in dentin hypersensitivity that was prepared via a simple sol-gel method and magnetron sputtering method, with an average size of 290 nm. The Pt layer as the power unit provided the dynamics to deliver the bioglass (desensitization agent). Using hydrogen peroxide as a fuel, the nBGs@Pt could automatically move in different media. In addition, the nBGs@Pt with a mesoporous structure demonstrated good hydroxyapatite formation performance. An in vitro dentin pressure model was used to verify the blocking ability of the nBGs@Pt in dentin tubules. The dynamics of the nBGs@Pt was sufficient to resist the outflow of dentin fluid and movement into the dentin tubules, with a blocking rate of 58.05%. After remineralization, the blocking rate could reach 96.07% and the formation of hydroxyapatite of up to 10 μm or more occurred. It is expected that this study will provide a simple and feasible new strategy for the painless treatment of dentin sensitivity.

Piezo1-pannexin-1-P2X3 axis in odontoblasts and neurons mediates sensory transduction in dentinal sensitivity.

According to the "hydrodynamic theory," dentinal pain or sensitivity is caused by dentinal fluid movement following the application of various stimuli to the dentin surface. Recent convergent evidence in Vitro has shown that plasma membrane deformation, mimicking dentinal fluid movement, activates mechanosensitive transient receptor potential (TRP)/Piezo channels in odontoblasts, with the Ca2+ signal eliciting the release of ATP from pannexin-1 (PANX-1). The released ATP activates the P2X3 receptor, which generates and propagates action potentials in the intradental Aδ afferent neurons. Thus, odontoblasts act as sensory receptor cells, and odontoblast-neuron signal communication established by the TRP/Piezo channel-PANX-1-P2X3 receptor complex may describe the mechanism of the sensory transduction sequence for dentinal sensitivity. To determine whether odontoblast-neuron communication and odontoblasts acting as sensory receptors are essential for generating dentinal pain, we evaluated nociceptive scores by analyzing behaviors evoked by dentinal sensitivity in conscious Wistar rats and Cre-mediated transgenic mouse models. In the dentin-exposed group, treatment with a bonding agent on the dentin surface, as well as systemic administration of A-317491 (P2X3 receptor antagonist), mefloquine and 10PANX (non-selective and selective PANX-1 antagonists), GsMTx-4 (selective Piezo1 channel antagonist), and HC-030031 (selective TRPA1 channel antagonist), but not HC-070 (selective TRPC5 channel antagonist), significantly reduced nociceptive scores following cold water (0.1ml) stimulation of the exposed dentin surface of the incisors compared to the scores of rats without local or systemic treatment. When we applied cold water stimulation to the exposed dentin surface of the lower first molar, nociceptive scores in the rats with systemic administration of A-317491, 10PANX, and GsMTx-4 were significantly reduced compared to those in the rats without systemic treatment. Dentin-exposed mice, with somatic odontoblast-specific depletion, also showed significant reduction in the nociceptive scores compared to those of Cre-mediated transgenic mice, which did not show any type of cell deletion, including odontoblasts. In the odontoblast-eliminated mice, P2X3 receptor-positive A-neurons were morphologically intact. These results indicate that neurotransmission between odontoblasts and neurons mediated by the Piezo1/TRPA1-pannexin-1-P2X3 receptor axis is necessary for the development of dentinal pain. In addition, odontoblasts are necessary for sensory transduction to generate dentinal sensitivity as mechanosensory receptor cells.

Frequency of various intensities of dentine hypersensitivity versus good and bad oral hygiene practices within Pakistani population

Background: Dentine sensitivity presents as short, sharp pain due to exposed dentine. To keep ourselves abreast with thechallenging situation of increasing prevalence of dentine sensitivity within the country, this research was conducted to devise a better management strategy. The aim of this study was to evaluate the frequency and intensity of dentine sensitivity within patients reporting in Outpatient department (OPD) and to correlate good versus bad practices of dentine sensitivity patients with dentine sensitivity frequency.Methods: A questionnaire based cross sectional study was carried out in three dental institutes of Lahore, Pakistan over a period of four months. A sample size of 300 individuals was selected by non-probability convenient sampling technique. Information collected included demographic data, participant’s oral hygiene practices and intensity of dentine sensitivity in them. A numeric rating scale was used to record the degree of dentine sensitivity and descriptive statistics were presented as frequency and percentage.Results: 210 out of 300 patients reported dentine sensitivity (70%). Only 1/4th patients were highly qualified. 60% individuals were from low income group. 51% reported intensity as mild, 34% as moderate and 15% as severe sensitivity. Most common triggering factor was cold (36%). Good practices resulted in reduction in sensitivity.Conclusion: According to results, high frequency of dentine sensitivity is observed. More awareness needs to be created about factors leading to sensitivity focusing more on dietary patterns that cause erosive wear of enamel and reduction in aggressive brushing and parafunctional habits.

New Approach to Addison Disease: Oral Manifestations Due to Endocrine Dysfunction and Comorbidity Burden.

This review highlights oral anomalies with major clinical impact in Addison disease (AD), including dental health and dermatologic features, through a dual perspective: pigmentation issues and AD comorbidities with oral manifestations. Affecting 92% of AD patients, cutaneomucosal hyperpigmentation is synchronous with or precedes general manifestations by up to a decade, underlying melanocytic infiltration of the basal epidermal layer; melanophages in the superficial dermis; and, rarely, acanthosis, perivascular lymphocytic infiltrate, and hyperkeratosis. Intraoral pigmentation might be the only sign of AD; thus, early recognition is mandatory, and biopsy is helpful in selected cases. The buccal area is the most affected location; other sites are palatine arches, lips, gums, and tongue. Pigmented oral lesions are patchy or diffuse; mostly asymptomatic; and occasionally accompanied by pain, itchiness, and burn-like lesions. Pigmented lingual patches are isolated or multiple, located on dorsal and lateral areas; fungiform pigmented papillae are also reported in AD individuals. Dermoscopy examination is particularly indicated for fungal etiology; yet, it is not routinely performed. AD’s comorbidity burden includes the cluster of autoimmune polyglandular syndrome (APS) type 1 underlying AIRE gene malfunction. Chronic cutaneomucosal candidiasis (CMC), including oral CMC, represents the first sign of APS1 in 70–80% of cases, displaying autoantibodies against interleukin (IL)-17A, IL-17F ± IL-22, and probably a high mucosal concentration of interferon (IFN)-γ. CMC is prone to systemic candidiasis, representing a procarcinogenic status due to Th17 cell anomalies. In APS1, the first cause of mortality is infections (24%), followed by oral and esophageal cancers (15%). Autoimmune hypoparathyroidism (HyP) is the earliest endocrine element in APS1; a combination of CMC by the age of 5 years and dental enamel hypoplasia (the most frequent dental complication of pediatric HyP) by the age of 15 is an indication for HyP assessment. Children with HyP might experience short dental roots, enamel opacities, hypodontia, and eruption dysfunctions. Copresence of APS-related type 1 diabetes mellitus (DM) enhances the risk of CMC, as well as periodontal disease (PD). Anemia-related mucosal pallor is related to DM, hypothyroidism, hypogonadism, corresponding gastroenterological diseases (Crohn’s disease also presents oral ulceration (OU), mucogingivitis, and a 2–3 times higher risk of PD; Biermer anemia might cause hyperpigmentation by itself), and rheumatologic diseases (lupus induces OU, honeycomb plaques, keratotic plaques, angular cheilitis, buccal petechial lesions, and PD). In more than half of the patients, associated vitiligo involves depigmentation of oral mucosa at different levels (palatal, gingival, alveolar, buccal mucosa, and lips). Celiac disease may manifest xerostomia, dry lips, OU, sialadenitis, recurrent aphthous stomatitis and dental enamel defects in children, a higher prevalence of caries and dentin sensitivity, and gingival bleeding. Oral pigmented lesions might provide a useful index of suspicion for AD in apparently healthy individuals, and thus an adrenocorticotropic hormone (ACTH) stimulation is useful. The spectrum of autoimmune AD comorbidities massively complicates the overall picture of oral manifestations.

치수 내 신경분포에 관한 고찰

The dental pulp is innervated by nociceptive afferents. Information on the axons innervating dental pulp and their morphological change during their intrapulpal course, glutamate signaling associated with pulpal axons and on the sensory receptors and ion channel expressed in the pulpal axons help understand pathologic dental pain and dentin sensitivity. Two different types of axons innervate dental pulp;Myelinated and unmyelinated axons. Myelinated axons undergo morphological change during their extrapulpal course from trigeminal ganglion to teeth. Morphological change of the myelinated axons allows embedding of receptors and ion channels into axonal plasmamembrane and become functional. Myelinated and unmyelinated axons show different pattern in distribution of their varicosities within the dental pulp, which may be associated with regional difference in glutamate signaling between myelinated and unmyelinated axons.

Expression of Piezo1 in the Trigeminal Neurons and in the Axons That Innervate the Dental Pulp.

Information on the neurons and axons that express the mechanosensitive channel Piezo1 and its expression in axons innervating the dental pulp may help understand the nature of the Piezo1-mediated mechanosensation and the underlying mechanism of dentin sensitivity elicited by mechanical stimuli. For this, we here investigated the neurochemical properties of the neurons in the rat trigeminal ganglion (TG) and their axons in its sensory root that express Piezo1 and the expression of Piezo1 in the rat and human dental pulp by light and electron microscopic immunohistochemistry and quantitative analysis. Piezo1 was expressed mainly in medium-sized and large TG neurons. Piezo1-immunopositive (+) neurons frequently coexpressed the marker for neurons with myelinated axons, NF200, but rarely the markers for neurons with unmyelinated axons, CGRP or IB4. In the sensory root of TG, Piezo1 was expressed primarily in small myelinated axons (Aδ, 60.2%) but also in large myelinated (Aβ, 24.3%) and unmyelinated (C, 15.5%) axons. In the human dental pulp, Piezo1 was expressed in numerous NF200+ axons, which formed a network in the peripheral pulp and often “ascended” toward the dentin. Most Piezo1+ myelinated axons in the radicular pulp became unmyelinated in the peripheral pulp, where Piezo1 immunoreaction product was associated with the axonal plasma membrane, suggesting a functional role of Piezo1 in the peripheral pulp. These findings suggest that Piezo1 is involved primarily in mediating the acute pain elicited by high-threshold mechanical stimuli, and that the Piezo1-mediated dental mechanotransduction occurs primarily in the axons in the peripheral pulp.

Phototherapy Using Er,Cr:YSGG Laser as a Definitive Treatment for Dentin Hypersensitivity: A Systematic Review

PurposeTo assess the efficacy of Er,Cr:YSGG lasers in reducing dentine hypersensitivity (DH).MethodsElectronic literature were searched through various databases (MEDLINE, SCOPUS, ProQuest, LILACS and EBSCO) up to March 2022 for articles addressing the following focused question: “In patients with dentine hypersensitivity, does an Er,Cr:YSGG laser provide a better outcome in terms of pain reduction than other dentine desensitizer agents?”. The literature was searched using combinations of the following medical subject heading (MeSH) terms and keywords: (laser OR phototherapy OR Er,Cr:YSGG laser) AND (dentine hypersensitivity OR dentine sensitivity OR dental sensitivity).ResultsA total of 486 studies were found, of which 7 randomized controlled trials were included in the review. The Er,Cr:YSGG laser wavelengths, power density and duration of irradiation used in the studies were 2780 nanometers, 0.25–0.5 watts and 20–60 seconds, respectively. The follow-up assessments were conducted ranging from immediately to 3 months after treatment. All studies showed that the Er,Cr:YSGG laser was effective in alleviating DH.ConclusionThis systematic review suggests that the application of an Er,Cr:YSSG laser is effective in alleviating DH and may have limited adverse effects if adequate parameters are followed.

Barniz polimerizable de vidrio ionómero modificado con resina “Clinpro XT”: una alternativa de tratamiento para la sensibilidad dentaria. Revisión sistemática de la literatura

Introduction: In response to dentin sensitivity, multiple products have been developed, including Clinpro XT, a lightcuring resin-modified ionomer glass varnish with fluoride, calcium andphosphate.Methodology: A systematic review of the literature was carried out. The selection was based on title, abstract and full text according to the inclusion and exclusioncriteria.Results: Of 299 articles, systematic reviews, meta-analysis, in vivo and in vitro studies and 2 surveys were selected.Discussion: Clinpro XT reduces dentin permeability, occludes dentin tubules andinhibits their reopening, increases the bioavailability of minerals in saliva andpromotes enamel remineralization.Meaning greater protection of enamel and dentin immediately and in the long term.Conclusions: Clinpro XT was shown todecrease dentin hypersensitivity even 6 months after application.

Effect of hydroxyapatite based agents on the bonding properties of universal adhesives

Objective: To study the effect of hydroxyapatite (HA) based agents on the bonding properties of universal adhesive with different application modes, and to provide evidence for the use of adhesives after desensitization treatment. Methods: Sixty impacted third molars were extracted and selected (acquired from Department of Oral and Maxillofacial Surgery, College of Stomatology, Xi'an Jiaotong University). Four third molars were used to prepare 1 mm thick dentin disks and treated with 1% citric acid to simulate sensitive tooth models. The dentin surfaces were observed by scanning electron microscope (SEM) after treating with no desensitization (control group), desensitized by HA based toothpaste Biorepair and Dontodent Sensitive respectively (desensitizing toothpaste A group and B group), or HA paste treatment (desensitizing paste group ) (n=2 per group). The remaining teeth were selected to expose the mid-coronal dentin and establish dentin sensitivity models. Then, the specimens were divided into 4 former groups and received corresponding treatment. Each group was randomly divided into 2 subgroups, and intermediately strong universal adhesive (G-Premio Bond) was applied on the desensitized dentin by either etch-and-rinse mode or self-etch mode. Resin-dentin slice specimens (n=4 per subgroup), microtensile specimens (n=20 per subgroup) and slice specimens (n=6 per subgroup) were prepared. The microstructure and nanoleakage of the adhesive interfaces were observed by scanning electron microscopy (SEM). The microtensile strength (bond strength) and fracture mode were tested and recorded. The water permeability of the adhesive interface was observed by laser scanning confocal microscopy (LSCM). Results: SEM showed that desensitizing toothpaste and desensitizing paste could partially or entirely occlude most of the dentin tubules. For the etch-and-rinse mode, the bond strength of specimens treated with toothpaste A [(40.98±4.60) MPa], toothpaste B [(40.89±4.64) MPa] and HA paste [(41.48±3.65) MPa] was significantly higher than that of the control group [(38.58±4.28) MPa] (F=3.89,P<0.05). There was no statistically significant difference in bond strength among the 4 subgroups for self-etch modes (F=0.48,P>0.05). After desensitization, the bond strength of the control group and desensitizing groups in the self-etch mode was significantly higher than that in the etch-and-rinse mode (P<0.05). The overall fracture modes were mixed failure and interfacial failure in the control group and desensitizing groups. SEM showed speckled silver-stained particles deposited along the bottom of the hybrid layer on the bond interface of etch-and-rinse mode, and there were few silver-stained particles deposited on the bond interface of self-etch mode. LSCM showed continuous linear penetration in the hybrid layer of etch-and-rinse mode subgroups and discontinuous linear penetration in the hybrid layer of self-etch mode subgroups. Conclusions: HA based desensitizers have no adverse effect on the bond strength of intermediately strong universal adhesive and show good bonding performance accompanied with the self-etch mode.

Dentine sensitivity caused by illumination of intraoral scanner and light curing unit.

BackgroundPatients often compliant sensitivity to high-intensity light irradiated application during dental procedures. This study aims to investigate tooth sensitivity caused by high-intensity light irradiated from an intraoral scanner (IOS) and a light-curing unit (LCU). Material and MethodsForty-five teeth from 45 healthy volunteers were included. These were equally classified into three groups using the cold test (4 ± 1 °C) and NRS pain assessment; A=control, B=cavity without sensitivity, and C=cavity with sensitivity. Two thermocouple probes were attached to the cervical area of the experimental and control tooth with a composite resin. Tooth sensitivity response by participant grip force was monitored. The digital oscilloscope was used to record two surface temperatures and a pain response during an IOS or a LCU irradiation. The high-intensity light from a LCU and an IOS was randomly applied at 2 mm above the cervical area for 20s. The data were compared statistical with two-way repeated measures ANOVA and Pearson’s correlation. ResultsThe illumination caused increasing surface temperatures of about 22.98 ± 3.20 °C for a LCU and 5.86 ± 1.46 °C for an IOS from a 29.5 °C baseline. As the light intensity from the LCU generated more heat, participants reported more tooth sensitivity with a shorter response time (2.10s to 18.70s). There was a positive correlation between surface temperature and pain response (R2 = 0.232; p<0.01). ConclusionsThe heat from high-intensity light from a LCU and an IOS can cause tooth sensitivity in some individuals especially those who had a cervical cavity with dentine sensitivity. The higher light intensity would raise the surface temperature and cause a higher sensitivity response. Key words:Light curing unit, intraoral scanner, tooth temperature, dentine sensitivity.

Lack of Fluid Movement between Dentin Tubule and Pulp Tissue: An In Vitro Study

Objective: In vitro studies supporting the hydrodynamic theory have reported that cavity provocation results in fluid flow from dentin tubules via pulp tissue to a capillary connected apically. Our preliminary findings did not corroborate this. Therefore, the aim was to perform experiments closely following the descriptions in the mentioned articles to find out if there is a direct fluid flow communication from a prepared cavity to pulp tissue detectable with this method. Material and Methods: Class V cavities were prepared and provocations (air blast, scraping, temperature change) initiated within 1 hour of extraction in 17 teeth and after 1 week in 3 teeth. Fluid flow was monitored during and after stimulation using a microscope. Results: No fluid flow was registered during stimulations performed within an hour of extraction. One week after extraction fluid movement was registered during the air blast. Conclusions: The finding of no direct continuum in freshly extracted teeth from cavity surface via dentin fluid to pulp tissue to an apically placed capillary does not per se disprove the hydrodynamic theory. As the in vitro experiment by Brännström et al. has been a major foundation for the hydrodynamic theory, it may be time to investigate the true mechanism(s) of dentin sensitivity.

Effects of desensitizing dentifrices on dentin tubule occlusion and resistance to erosive challenges

BackgroundMany studies have demonstrated efficacy of casein phosphopeptide (CPP) containing products for dentin tubule occlusion for treatment of dentin sensitivity, but their effectiveness under dynamic erosive challenges remains to be elucidated. The purpose of the present study was to investigate the effectiveness of a desensitizing dentifrice containing CPP in occluding dentin tubules and resisting erosive challenges in comparison to that containing polyvinyl methyl ether/maleic acid (PVM/MA) copolymers.Methods A total of 33 dentin discs were prepared from coronal sections of human third molars and divided into 3 groups: a toothpaste containing CPP; a toothpaste containing PVM/MA and submicron silica; and a regular toothpaste (Controls). A soft-bristle toothbrush was used to brush the dentin discs with the dentifrices for 45 strokes in 30 s at a force of approximately 200 g. The brushing cycle was repeated after immersion of the dentin discs in artificial saliva overnight. The dentin discs were then challenged in orange juice for 10 min in an incubator rocking at 120 rpm. Three fields were randomly selected on each dentin disk surface to assess dentin tubule occlusions after each brushing cycle and after orange juice challenge with a 3D laser scanning microscope. Specimen cross sections were examined with a scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS).ResultsAfter the first and second cycles of brushing, dentin tubules were occluded on average by 56.3% and 85.7% in CPP group, 66.2% and 88.1% in PVM/MA group, and 0.0 and 13.0% in the controls, respectively. There were no statistically significant differences in dentin tubule occlusions between the CPP and PVM/MA groups after two cycles of brushing (p>0.05). After dynamic erosive challenges with orange juice, 20.3% of the dentin tubules in the CPP group, 79.1% in the PVM/MA group and none in the control remained occluded (P<0.05). SEM/EDS imaging showed that dentin tubules were blocked with plugs containing dentifrice substances in CPP and PVM/MA groups after treatments, but none in the controls.ConclusionsDesensitizing dentifrices containing CPP or PVM/MA could effectively occlude dentin tubules after two cycles of brushing. PVM/MA in combination with submicron silicon dioxide exhibited stronger resistance to dynamic erosive challenges by acidic beverages. Inorganic fillers that can enter dentin tubules and resist erosive challenges may be key for desensitizing dentifrices.

Comparison between effectiveness of dentine desensitizer and one bottle self-etch adhesive on dentine hypersensitivity.

Dentine hypersensitivity is one of the most common chief complaints of patients observed by dentists in their practice. However, there is a lack of universal consensus over the selection of reliable treatment modality. To compare the effectiveness between dentine desensitizer and self-etch adhesive in patients complaining of moderate to severe dentine hypersensitivity pain. A total of 254 patients with moderate to severe dentine hypersensitivity were randomly divided into Group A (Single Bond Universal Agent) and Group B (Seal & Protect Agent) according to the treatment provided. Sensitivity was assessed by means of mechanical (probing) and evaporative (air blast) stimuli. Discomfort Internal Scale (DIS) was explained to patients. DIS scores were recorded after one minute and one month following the application of both agents. Descriptive statistics were calculated. Stratification was done to control confounder and post stratification chi-square test was also applied. The statistically significant difference (p= 0.000) in effectiveness between the two groups was observed. The mean discomfort internal scale score at baseline, after 1minute and after 1month in Group A was 3.65 ± 0.60, 2.33 ± 0.64 and 0.41 ± 0.71 respectively, while in Group B, it was 3.55 ± 0.58, 2.40 ± 0.62 and 0.72 ± 0.92 respectively. Overall, 86.6% patients observed improvement in dentinal sensitivity in Group A while in Group B only 67.7% patients reported reduction in sensitivity. Self-etch adhesive significantly reduces dentin hypersensitivity, immediately after one minute of its application and is effective for a period of one month compared to desensitizing agent.

English

BACKGROUND Dentinal hypersensitivity is a common clinical disease that occurs as a result of dentin exposure. Though the term dentin hypersensitivity and dentin sensitivity is used interchangeably, dentin hypersensitivity is an exaggerated form of dentinal sensitivity which arises due to localized pulpal inflammation, pulpal nerve sprouting, and development of inflammatory sodium channels. It is characterised by short sharp pain emerging from exposed dentinal tubules in reaction to various stimuli. Such dentin exposure could be due to either enamel loss or cemental loss. This is followed by removal of smear layer by mechanical or chemical means. At present, the hydrodynamic theory, which describes fluid movement in response to stimuli within exposed dentinal tubules, is a commonly recognized explanation for dentin hypersensitivity. It is more common in premolars and canines, and it affects the facial surfaces of the teeth towards the cervical aspect. Studies suggested microscopic changes in the structure of sensitive dentin compared with normal dentin. The diagnosis of dentinal hypersensitivity requires careful clinical examination and eliciting the response using various stimuli. Dentinal hypersensitivity is usually managed by the use of physical or chemical agents. They work either by disturbing the neural response to pain stimulus or block fluid flow by occluding the tubule. The desirable features of a desensitising agent include the ability to give instant and longlasting pain relief, being simple to use, well accepted, not harmful to the pulp. It is recommended that the desensitizing agent is used for at least two weeks. Some of the newer agents used for management includes CPP-ACP, proarginine, nanomaterials, herbal products, propolis etc. In cases where there is tooth structure loss, appropriate restorative material is used to cover the exposed dentin. Root canal therapy is considered the last resort for pain relief after all other options have failed to provide relief. The present article outlines the etiopathogenesis, risk factors, diagnosis, prevention and treatment of dentinal hypersensitivity. KEY WORDS Dentinal Hypersensitivity; Dentin Sensitivity; Desensitizing Agents; Iontophoresis

Hydroxyapatite in Oral Care Products-A Review.

Calcium phosphate compounds form the inorganic phases of our mineralised tissues such as bone and teeth, playing an important role in hard tissue engineering and regenerative medicine. In dentistry and oral care products, hydroxyapatite (HA) is a stable and biocompatible calcium phosphate with low solubility being used for various applications such as tooth remineralisation, reduction of tooth sensitivity, oral biofilm control, and tooth whitening. Clinical data on these products is limited with varied results; additionally, the effectiveness of these apatite compounds versus fluoride, which has conventionally been used in toothpaste, has not been established. Therefore, this review critically evaluates current research on HA oral care, and discusses the role and mechanism of HA in remineralisation of both enamel and dentine and for suppressing dentine sensitivity. Furthermore, we position HA’s role in biofilm management and highlight the role of HA in dental applications by summarising the recent achievement and providing an overview of commercialised HA dental products. The review also indicates the existing limitations and provides direction for future research and commercialisation of apatite-based oral care products.

Mechanical Stimulation-Induced Calcium Signaling by Piezo1 Channel Activation in Human Odontoblast Reduces Dentin Mineralization.

Odontoblasts play critical roles in dentin formation and sensory transduction following stimuli on the dentin surface. Exogenous stimuli to the dentin surface elicit dentinal sensitivity through the movement of fluids in dentinal tubules, resulting in cellular deformation. Recently, Piezo1 channels have been implicated in mechanosensitive processes, as well as Ca2+ signals in odontoblasts. However, in human odontoblasts, the cellular responses induced by mechanical stimulation, Piezo1 channel expression, and its pharmacological properties remain unclear. In the present study, we examined functional expression of the Piezo1 channel by recording direct mechanical stimulation-induced Ca2+ signaling in dentin matrix protein 1 (DMP-1)-, nestin-, and dentin sialophosphoprotein (DSPP)-immunopositive human odontoblasts. Mechanical stimulation of human odontoblasts transiently increased intracellular free calcium concentration ([Ca2+]i). Application of repeated mechanical stimulation to human odontoblasts resulted in repeated transient [Ca2+]i increases, but did not show any desensitizing effects on [Ca2+]i increases. We also observed a transient [Ca2+]i increase in the neighboring odontoblasts to the stimulated cells during mechanical stimulation, showing a decrease in [Ca2+]i with an increasing distance from the mechanically stimulated cells. Application of Yoda1 transiently increased [Ca2+]i. This increase was inhibited by application of Gd3+ and Dooku1, respectively. Mechanical stimulation-induced [Ca2+]i increase was also inhibited by application of Gd3+ or Dooku1. When Piezo1 channels in human odontoblasts were knocked down by gene silencing with short hairpin RNA (shRNA), mechanical stimulation-induced [Ca2+]i responses were almost completely abolished. Piezo1 channel knockdown attenuated the number of Piezo1-immunopositive cells in the immunofluorescence analysis, while no effects were observed in Piezo2-immunopositive cells. Alizarin red staining distinctly showed that pharmacological activation of Piezo1 channels by Yoda1 significantly suppressed mineralization, and shRNA-mediated knockdown of Piezo1 also significantly enhanced mineralization. These results suggest that mechanical stimulation predominantly activates intracellular Ca2+ signaling via Piezo1 channel opening, rather than Piezo2 channels, and the Ca2+ signal establishes intercellular odontoblast-odontoblast communication. In addition, Piezo1 channel activation participates in the reduction of dentinogenesis. Thus, the intracellular Ca2+ signaling pathway mediated by Piezo1 channels could contribute to cellular function in human odontoblasts in two ways: (1) generating dentinal sensitivity and (2) suppressing physiological/reactional dentinogenesis, following cellular deformation induced by hydrodynamic forces inside dentinal tubules.

Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses

ObjectivesTo evaluate obliterating capability and biological performance of desensitizing agents. Methods50 dentin blocks were distributed according to the desensitizing agent used (n = 10): Control (Artificial saliva); Ultra EZ (Ultradent); Desensibilize Nano P (FGM); T5-OH Bioactive Glass (Experimental solution); F18 Bioactive Glass (Experimental solution). Desensitizing treatments were performed for 15 days. In addition, specimens were subjected to acid challenge to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after desensitizing procedures and acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid assay at 15 min, 24-h and 48-h time points. Scanning electron microscopy and energy dispersion X-ray spectroscopy were performed for qualitative analysis. Data of dentin permeability was analyzed by two-way repeated measures ANOVA and Tukey's test. For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests. Resultsfor dentin permeability there was no significant difference among desensitizing agents after treatment, but control group presented highest values (0.131 ± 0.076 Lp). After acid challenge, control group maintained highest values (0.044 ± 0.014 Lp) with significant difference to other groups, except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among groups. ConclusionBioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties. Clinical significanceThere is no gold standard protocol for dentin sensitivity. The study of novel desensitizing agents that can obliterate dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.

Time-course of the effect of potassium oxalate in the treatment of hypersensitive dentine in man

ObjectiveInvestigate the cause of hypersensitive dentine (HD) by recording the time course of changes in dentine sensitivity, sensory threshold to electrical stimulation (ET) and pulpal blood flow (PBF) following tubular occlusion using in vitro and clinical experiments. DesignNineteen teeth with HD and 13 with normal dentine from 8 participants were evaluated, and the intensity of any pain produced by various stimuli was recorded at different times after oxalate treatment. The participants used a visual-analogue scale (VAS) to indicate the intensity of any pain. The ET and PBF were recorded at the same times. ResultsPreliminary in vitro experiments showed that oxalate treatment had no effect on the method used to record PBF, and blocked the treated tubules immediately after application. Considering teeth with HD, a decrease in the median VAS evoked by all forms of stimulation was observed at all post-treatment times, except immediately after treatment (p < 0.05), while the treatment produced no significant effect in teeth with normal dentine. No significant changes in ET or PBF was observed in any of the groups. ConclusionsThe effect of oxalate in relieving the symptoms of HD is not only due to a reduction in the intensity of stimulation of sensory receptors sensitive to fluid flow in the dentinal tubules, but also to a reduce in the sensitivity of the receptors that respond to dentine stimulation. There was no evidence that acute pulpitis or central sensitization to pain, which would be associated with changes in PBF or ET, contributes to HD.

REMINERALIZING THERAPY IN THE PROCESS OF TEETH WHITENING

Resume. Nowadays, aesthetics plays an important role in dentistry due to the increased attention of people to the beauty and attractiveness of the smile, which is known as an effective tool in achieving both personal and professional purposes. Therefore, the whitening of discolored teeth is one of the promising directions in aesthetic dentistry. To date, there is much controversy among dentists about the effectiveness and, the most importantly, the safety of teeth whitening. The prevention of dentin hypersensitivity is among the main tasks associated with the safe and comfortable treatment and follow-up period for patients. In order to avoid the negative consequences of hyperesthesia, the teeth whitening procedure should be finished with remineralizing therapy. Thought there are a large number of techniques and products for the treatment of hyperesthesia, the question of their most appropriate selection and combination is remaining unresolved and is relevant to meet the steadily growing population demands.&#x0D; Purpose: to highlight the latest views on techniques and products for remineralizing therapy in the process of teeth whitening based on the analysis of relevant literature.&#x0D; Results. Numerous bleaching methods are mainly based on applying high concentrations of hydrogen peroxide. At present, the safety of whitening methods remains controversial and thus requiring further research. The problem of improving techniques aimed at preventing the side effects of professional whitening on the oral tissues and organs are remaining relevant. The problems associated with professional whitening include the decreased resistance of hard dental tissues, the appearance of areas of demineralization and hyperesthesia in the hard dental tissues. At present, a wide range of products has been proposed to treat and prevent the development of teeth hypersensitivity. However, the most effective of them, which could be offered to patients after professional whitening have not been identified yet. To prevent and treat dental hyperesthesia effectively, fluoride-containing remineralizing remedies are widely used to diminish dentin sensitivity. There are studies demonstrating the highest incidence of teeth hyperesthesia during light catalytic and chemical bleaching Therapeutic and prophylactic agents, which contain calcium, phosphorus and fluoride ions, which promote dental enamel remineralization, have been proposed. The use of remineralizing gels before the procedure of medical teeth whitening reduces the occurrence of dental hyperesthesia. That is why many manufacturers of bleaching systems have begun to add desensitizing components to their composition. Thus, Opalescence Boost PF gel contains potassium nitrate and fluorine, Philips Zoom whitening gel contains amorphous calcium phosphate, in addition; remineralizing gel Relief ACP with amorphous calcium phosphate is offered to reduce the occurrence of teeth hypersensitivity during whitening procedure. The results of our research have shown the most significant changes expressed by a decrease in organic acids, maximum increase in concentrations of calcium ions in oral fluid, occur when using photo-bleaching system Beyond Polus, while minimal changes are observed when using chemical activation system Opalescence Xtra Boost. The combination of a reminalizign remedies based on zinc-substituted hydroxyapatite carbonate with laser phonophoresis can be recommended be apply after any bleaching techniques and they have been proved to be the most effective.&#x0D; Conclusion. There is a wide range of techniques and products of remineralizing therapy applied in the process of teeth whitening. Various options of remineralizing therapy and applying different compounds reducing teeth sensitivity after teeth whitening procedure are described in the article. Many formulas have been already developed to ensure patient comfort after a whitening procedure, and in particular to prevent the development of hyperesthesia. Some manufacturers incorporate remineralizing remedies in the whitening system that allows dentists to solve the problem of teeth hypersensitivity effectively.

The control of pain due to dentin hypersensitivity in individuals with molar–incisor hypomineralisation: a protocol for a randomised controlled clinical trial

IntroductionDentin hypersensitivity (DH) is defined as high sensitivity of the vital dentin when exposed to thermal, chemical or tactile stimuli. Two mechanisms are required for the occurrence of DH: (1)...