The research, led by Svanishvili Nino and colleagues at Tbilisi State Medical University in Georgia, together with a collaborator at the University of Brescia in Italy, employed scanning electron microscopy with energy-dispersive X-ray spectroscopy, or SEM-EDX, to quantify elemental composition at the enamel surface, the dentin–enamel junction, and the peripulpal dentin that sits closest to the tooth’s living pulp. Forty-five extracted human teeth were longitudinally sectioned under continuous water cooling, yielding ninety paired specimens. One half of each tooth served as an untouched baseline control, while its counterpart was subjected to an acid-induced demineralization protocol designed to mimic the cyclic chemistry of dental caries.

The demineralization model was deliberately realistic. For ten days, the experimental halves cycled between an acidic acetate buffer at pH 4.3, containing calcium and phosphate ions, for six hours each weekday, and a neutral artificial saliva solution for the remaining eighteen hours. This pH-cycling regimen reproduces the repeated acid attacks and recovery periods that occur naturally in the oral cavity, rather than the crude single-soak approaches used in older laboratory models. After the cycling was complete, and again after a subsequent ten-day remineralization phase, the researchers reassessed elemental concentrations in all three zones using the same SEM-EDX technique.

At baseline, the data confirmed the classic structural hierarchy of tooth tissues. Enamel showed mean calcium levels of 27.51 percent, roughly three times higher than the values recorded at the dentin–enamel junction, which averaged 9.01 percent, and peripulpal dentin, which averaged 9.99 percent. Phosphorus followed the same pattern, peaking at 13.63 percent in enamel and dropping to around 6.7 percent in both dentin regions. Fluoride, by contrast, was uniformly scarce across all zones, with concentrations hovering between 0.044 and 0.055 percent—a reminder that, in the absence of topical fluoride exposure, the natural fluoride content of dental hard tissues is minimal.

What happened next was more revealing. After the acid challenge, calcium and phosphorus fell significantly in every zone, with paired statistical analysis confirming the reductions were highly significant at p < 0.0001. But the damage was not distributed evenly. Enamel, with its dense crystalline architecture, lost relatively little calcium, declining from 27.51 to 25.20 percent. The dentin–enamel junction and peripulpal dentin fared far worse, with calcium dropping to 6.18 and 6.01 percent respectively. Most striking of all, fluoride became completely undetectable in every demineralized sample, suggesting that even the small natural reservoir of fluoride in tooth tissue is stripped away under sustained acidic conditions.

The complete disappearance of fluoride is arguably the study’s most provocative finding. The authors argue that this makes fluoride a sensitive marker of mineral loss, one that vanishes entirely rather than declining gradually. It also extends a principle previously established for superficial enamel—that fluoride is rapidly depleted under acid challenge—into the deeper architecture of the tooth. Under severe acid exposure, the structural fluoride reservoir appears to be depleted comprehensively across the tooth cross-section, not just at the surface, underscoring the vulnerability of the underlying dentin zones that traditional caries research has often overlooked.

Following demineralization, the experimental halves were randomly assigned to one of three fluoride-based remineralization protocols, with fifteen specimens in each group. The first received a daily application of fluoride varnish for ten days. The second was treated twice daily with fluoride toothpaste, followed by light rinsing. The third underwent the identical toothpaste regimen but without rinsing, leaving the residual paste in contact with the tissue. After the treatment period, all three groups showed partial restoration of calcium and fluoride levels, confirming that fluoride-based interventions can drive meaningful mineral redeposition even in a laboratory setting.

The differences between the protocols were subtle but telling. Fluoride varnish produced the highest fluoride incorporation in enamel, reaching 0.316 percent—more than three times the level achieved by either toothpaste regimen—and this difference was statistically significant at p < 0.05. The no-rinse toothpaste group showed slightly higher fluoride retention than the rinsed group, a pattern consistent with the argument that prolonged ion availability is essential for diffusion past the superficial layers. However, when it came to calcium and phosphorus recovery, no statistically significant differences emerged among the three treatment groups in any zone, and the varnish’s fluoride advantage did not translate into superior crystal-lattice restoration in the dentin regions.

This disconnect carries an important implication. The authors suggest that the organic collagen matrix of dentin acts as a rate-limiting barrier to mineral precipitation, meaning that high superficial fluoride accumulation does not automatically guarantee uniform, tooth-wide remineralization. In other words, the chemistry of rebuilding mineral in enamel, which is almost entirely inorganic, differs fundamentally from the chemistry of rebuilding mineral in dentin, which is interwoven with a protein scaffold that responds to ionic changes in its own way. This three-dimensional view of intra-tooth mineral dynamics—tracking elemental fluxes simultaneously across enamel, the junction, and deep dentin within a paired split-sample design—is what the authors identify as the study’s principal contribution to the literature.

The findings arrive amid a growing global concern about dental caries, which remains one of the most widespread chronic diseases worldwide and is driven by a multifactorial interplay of biofilm composition, dietary habits, saliva properties, and oral hygiene. By demonstrating that dentin—particularly at the dentin–enamel junction and near the pulp—is more susceptible to demineralization than enamel, and that different fluoride delivery methods produce regionally distinct remineralization profiles, the study offers a more nuanced framework for designing preventive protocols. The authors caution that their ex vivo model cannot fully replicate the complexity of the oral environment, that the sample size was constrained by specimen availability, and that the broad age range of donors, from sixteen to sixty years, was not stratified. Future work, they note, should incorporate microhardness testing and micro-CT imaging to assess structural recovery alongside elemental composition, and should be conducted under conditions more closely approximating clinical reality. For now, the message is clear: fluoride works, but where and how well it works depends on which part of the tooth you ask.

Subject of Research: Elemental changes in tooth enamel and dentin during demineralization and fluoride-induced remineralization measured by SEM-EDX

Article Title: Elemental changes in tooth hard tissues during demineralization and fluoride-induced remineralization: an SEM-EDX study

Article References: Nino, S., Marina, M., Labanca, M., & Dea, V. (2026). Elemental changes in tooth hard tissues during demineralization and fluoride-induced remineralization: an SEM-EDX study. Acta Biochimica Polonica, 73, Article 16706. https://doi.org/10.3389/abp.2026.16706

Image Credits: AI Generated

DOI: 10.3389/abp.2026.16706

Keywords: dental caries, tooth enamel, dentin, fluoride, remineralization, SEM-EDX, demineralization, oral health, Elemental, changes, tooth, hard

The study, published in JBMR Plus on August 25, 2026, centers on the ALPL gene, which provides the instructions for making an enzyme called tissue-nonspecific alkaline phosphatase, or TNAP. This enzyme is essential for the proper mineralization of hard tissues, the chemical process by which bone and tooth structures become rigid and strong. When ALPL mutations impair TNAP function, minerals fail to deposit correctly, and the skeleton and dentition become vulnerable. The severity of hypophosphatasia spans a remarkable spectrum, from perinatal forms that are life-threatening to odonto forms that seem to affect little more than the teeth. Understanding what drives that spectrum has been one of the field’s persistent puzzles.

To attack the problem experimentally, the Osaka team created knock-in mouse models carrying three ALPL variants that had been identified in patients. Rather than studying the most severe end of the disease, the researchers focused their detailed analysis on two models representing milder forms, precisely the cases most likely to slip under the clinical radar. Both models showed reduced density of the bone surrounding the teeth and a weakening of the tissues that anchor teeth in place, the periodontal structures that in healthy mouths hold each tooth firmly within its socket.

The comparison between the two models proved especially revealing. One model carried the p.R184W variant, a single amino acid substitution in the TNAP enzyme. In these animals, the rest of the skeleton showed little obvious change, yet the teeth told a different story: abnormalities appeared in the dentin, the hard tissue beneath the enamel; in the cementum, the thin mineralized layer that covers the tooth root and anchors it to the surrounding ligament; and in the tooth-supporting tissues more broadly. The second model, carrying a combination of the c.1559delT deletion and the p.F327L variant, presented a somewhat different picture. These mice showed mild skeletal changes together with broader dental defects, including reduced mineralization of both enamel and dentin and thinner dentin overall.

Perhaps the most consequential finding is what did not explain the differences. Blood levels of TNAP, the enzyme whose deficiency defines the disease, could not account for the variation in dental symptoms between the two models. In clinical practice, circulating TNAP activity is a key diagnostic marker, and lower levels generally correlate with more severe disease. But the Osaka results indicate that within the milder spectrum, the specific ALPL variant itself, not merely how much enzyme is measurable in the blood, influences how oral symptoms develop. That distinction matters, because it suggests that the local environment inside the jaw and the tooth, where TNAP acts directly on mineralizing surfaces, responds to different mutations in different ways.

The clinical implications reach well beyond the laboratory. Dentists are frequently the first clinicians to encounter hypophosphatasia, even when neither the patient nor the family suspects anything systemic is happening. A child who loses multiple primary teeth early, without trauma or gum disease, may be exhibiting the odonto form of the condition. The new models give researchers a controlled platform for studying exactly how the disease erodes the cementum and periodontal ligament, the structures whose failure leads to tooth shedding. With such a platform, interventions can be tested systematically rather than piecemeal, from treatments aimed at preventing tooth loss to strategies for protecting the jawbone around the teeth.

Orthodontic care represents another area where the models could change practice. Patients with hypophosphatasia face elevated risks during orthodontic treatment, because moving teeth through already compromised bone and periodontal tissue can accelerate damage. A model system that faithfully reproduces the dental manifestations of specific variants would allow researchers to evaluate the safety of orthodontic approaches for different disease severities, potentially giving clinicians a firmer evidence base for treatment decisions that are currently guided largely by caution and case reports.

The research also underscores a broader principle in rare disease medicine: the mouth can serve as a diagnostic window. Because dental symptoms can appear before any obvious skeletal problems, heightened awareness among dental professionals could lead to earlier recognition of hypophosphatasia. Early diagnosis has become increasingly important as enzyme replacement therapy and other management strategies have developed, since intervening before irreversible loss of dentition or bone may preserve outcomes. The Osaka team’s work provides a mechanistic foundation for connecting what a dentist observes in a child’s mouth to the specific genetic variant underlying it.

Associate Professor Rena Okawa, who led the work, emphasized the human stakes of the models. Some patients, she noted, are diagnosed only after their baby teeth fall out early, even though they show almost no bone symptoms. Her hope is that these models will help the field develop dental treatments tailored to each patient’s symptoms, an approach that acknowledges two patients with the same diagnosis may need very different dental care depending on which variant they carry. That philosophy, precision dentistry for a rare bone disease, reflects a wider shift in genetics toward treating the mutation, not just the syndrome.

The path to publication carried its own distinctive mark of community engagement: the study was supported in part by a crowdfunding campaign involving 443 donors, a reminder that for ultra-rare conditions affecting small patient populations, public enthusiasm can help bridge funding gaps that conventional grants may not cover. As the knock-in mice move into wider use, they offer something the field has lacked, a way to reproduce patient-specific genetics in a controlled animal setting and to watch, tooth by tooth and bone by bone, how a single changed letter in the ALPL gene reshapes the architecture of the smile. For the children whose early tooth loss has long been the disease’s quiet calling card, that visibility may finally translate into earlier answers and better-protected teeth.

Subject of Research: Mouse models of hypophosphatasia revealing variant-specific dental manifestations

Article Title: Teeth reveal hidden signs of a rare bone disorder

Article References: Teeth reveal hidden signs of a rare bone disorder. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: hypophosphatasia, ALPL gene, TNAP enzyme, dentin, cementum, tooth loss, mouse models, mineralization, rare disease, periodontal tissue, orthodontics, University of Osaka

The sensors in question are Piezo1 and Piezo2, ion channels that open in response to mechanical stimulation and allow calcium and other charged particles to flood into cells. Since their discovery, Piezo channels have been implicated in everything from the sense of touch to blood pressure regulation, and previous work had shown that they are expressed in tooth-forming cells and participate in postnatal tooth development. What remained murky was their precise role in odontoblast differentiation, the process by which progenitor cells in the outermost layer of the dental pulp transform into mature, dentin-secreting odontoblasts. That gap in knowledge mattered, because dentin formation is the foundation of tooth structure, and defects in odontoblast maturation can produce structurally weakened teeth that are vulnerable throughout life.

To close that gap, a research group led by Professor Man-Kyo Chung and Dr. Xuguang Nie of the University of Maryland Baltimore turned to genetic mouse models in which the Piezo genes could be selectively deleted. Their findings, published in Volume 18, Article number 61 of the International Journal of Oral Science on 10 September 2026, provide the first in vivo demonstration that Piezo channels drive the terminal differentiation of odontoblasts, and they identify the Wnt signaling pathway as the molecular bridge between mechanical sensing and tooth formation. The work was supported by the National Institutes of Health grant R35 DE030045, with additional support to researcher Kelley Huang through the R25 DE32530 Maryland Program in Dental Research Experience.

Explaining why the team took this approach, Professor Chung noted that although earlier studies had reported that Piezo1 and Piezo2 are expressed in tooth-forming cells, their roles in tooth development in living animals remained poorly understood. By using a conditional knockout strategy, the researchers could remove the genes at specific times and places rather than eliminating them throughout the embryo, which allowed them to focus on the cells that actually build teeth. The Wnt1-Cre2 system they employed deletes target genes specifically in cells of neural crest origin, a lineage that includes odontoblasts, giving the team a precise genetic scalpel for the job.

The first experiments produced a surprise. When the researchers generated mice lacking either Piezo1 or Piezo2 alone in these neural crest-derived cells, tooth development proceeded essentially normally. This result pointed to a functional redundancy between the two channels, a phenomenon that has been documented in many other tissues and biological processes, where one channel can compensate for the loss of its sibling. To test that idea, the team engineered mice lacking both genes simultaneously, creating the Piezo1/Piezo2 double knockout model that would become the centerpiece of the study.

At the embryonic stage, the double knockout mice still showed no obvious defects in tooth development, suggesting that the earliest steps of tooth patterning do not depend on these mechanosensitive channels. But the picture changed dramatically at birth. Newborn double knockout mice exhibited a striking reduction in odontoblast height, a hallmark of immature odontoblasts, along with decreased expression of the key proteins that define odontoblast differentiation: dentin sialophosphoprotein, known as Dspp, alkaline phosphatase, or Alpl, and collagen type 1, or Col1a1. Together, these molecular and cellular changes signaled a clear impairment of odontoblast maturation. The double knockout animals did not survive beyond the first day after birth, likely reflecting the broader importance of Piezo channels in craniofacial and systemic development, but in the tissue that could be examined at this most advanced stage of survival, dentin matrix was present only in some areas, and overall tooth development was atypical.

With a differentiation defect firmly established, the researchers turned to the question of mechanism. Wnt signaling is one of the master regulators of tooth development, controlling multiple stages from initiation to maturation, and previous studies had reported correlations between Wnt signaling and Piezo1 activity in a variety of biological contexts. That made the Wnt pathway an obvious suspect. The team therefore measured the expression of Wnt10a and β-catenin, two central components of the canonical Wnt signaling cascade that operates during odontoblast differentiation. In the double knockout mice, both factors were significantly downregulated, and the suppression extended downstream as well: Axin1, a known target of β-catenin signaling, was also reduced. The mechanical sensors, it appeared, were feeding directly into one of developmental biology’s most important signaling networks.

The most compelling evidence came from a rescue experiment. When the researchers supplied exogenous Wnt10a to the deficient mice, odontoblast differentiation and Wnt signaling were partially restored, demonstrating that the loss of Wnt activity was not merely a side effect of the differentiation failure but a causal link in the chain. In a complementary approach, the team treated pregnant wild-type mice with Yoda1, a pharmacological activator of Piezo1, and observed increased odontoblast differentiation, increased matrix deposition, and elevated expression of Wnt10a and β-catenin in the embryos. In other words, turning up the mechanical signal turned up the tooth-building program. Taken together, these experiments show that Piezo1 and Piezo2 contribute to the terminal differentiation of odontoblasts, at least in part, by modulating canonical Wnt signaling.

The implications of the work extend beyond basic developmental biology. Dentin malformations and inherited dentin defects, such as those seen in genetic conditions affecting dentin sialophosphoprotein and related pathways, remain difficult to treat because dentin, unlike many other tissues, cannot regenerate once the odontoblasts that formed it are lost or dysfunctional. Dr. Nie emphasized the translational potential of the findings, remarking that this is the first study to reveal the roles of Piezo1 and Piezo2 in odontoblast differentiation in an in vivo model, and that the molecular links between the Piezo channels and Wnt signaling could potentially be harnessed to develop therapeutic strategies for dentin malformations or inherited dentin defects. If pharmacological manipulation of Piezo channels, as the Yoda1 experiment suggests, can enhance odontoblast maturation and matrix deposition, similar approaches might one day strengthen dentin formation in patients with congenital tooth defects or even support regenerative dental therapies.

The study also adds an important chapter to the rapidly expanding field of mechanobiology, the discipline that explores how physical forces influence gene expression and cell fate. The idea that a developing tooth needs to sense its mechanical environment in order to mineralize properly is a vivid illustration of how deeply embedded mechanical signaling is in embryonic development. Odontoblasts, after all, will spend their entire postnatal lives as mechanosensitive sentinels of the tooth, detecting stimuli that travel through dentin and orchestrating responses such as tertiary dentin formation. The new findings suggest that this mechanical sensitivity is not a late addition to the odontoblast toolkit but a fundamental requirement for the cells to reach their mature, dentin-forming state in the first place. As researchers continue to map the intersections between ion channels, mechanical forces, and developmental signaling pathways, the humble tooth is proving to be a powerful model for understanding how the body translates physical cues into biological structure, one calcified matrix molecule at a time.

Subject of Research: The role of mechanosensitive Piezo1 and Piezo2 ion channels in odontoblast differentiation and dentin formation during tooth development

Article Title: Mechanosensitive ion channels regulate tooth development

Article References: Mechanosensitive ion channels regulate tooth development. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Piezo1, Piezo2, odontoblasts, dentin, tooth development, Wnt signaling, mechanosensitive ion channels, mechanobiology, conditional knockout mice, International Journal of Oral Science, dentin defects, Wnt10a