2026-07-08 | Provisional Shell Crown Technique in the Contemporary Management of Amelogenesis Imperfecta
The tooth preparation and provisionalisation stage in a complex fixed dental reconstruction treatment plan is inherently stressful for both the patient and the clinician. However, when multiple adjacent tooth preparations are deemed clinically indicated, all stakeholders tend to remain satisfied when the outcome of provisional treatment is biomechanically stable and aesthetically pleasing. Digital design and meticulous implementation of the plan can ensure that provisional restoration contours closely match the patient-approved predetermined smile design. Similarly, a careful approach during interim restoration with segmental splinted provisional crowns can lead to a stable restorative outcome, with retention security. This clinical tip article will exemplify the splinted provisional shell crown technique with a focus on the maxillary labial segment dentition.
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2026-05-22 | Kdf1 missense mutation caused enamel defects by disrupting cell adhesion and Hippo-YAP signaling in dental epithelium.
Amelogenesis imperfecta is a hereditary enamel defect arising from dental epithelium dysfunction. Although keratinocyte differentiation factor 1 (KDF1) acts as an intracellular regulator in epithelial cells, the underlying disease mechanism of the patient-derived KDF1 missense mutation in amelogenesis remains unclear. Here, we show that a patient-derived KDF1 mutation (c.908 G > C, p.R303P) causes enamel defects by disrupting cell adhesion and Hippo-YAP signaling. Immunohistochemistry revealed strong KDF1 expression throughout dental epithelium development, particularly at the cell membrane. Kdf1 mutation knock-in heterozygotes and homozygotes displayed graded defective enamel with reduced thickness, inadequate mineralization and disorganized microstructure. This phenotype correlated with a gradual reduction in enamel matrix proteins and proteases across genotypes. Bulk RNA sequencing of ameloblasts suggested marked changes in adhesion-related genes and the Hippo-YAP pathway. We characterized cellular consequences of this variant using both LS8 and ALC cell lines, which appeared abnormalities including accelerated proliferation, undermined differentiation, weakened adhesion, and enhanced migration. In vivo and in vitro findings supported a model wherein the KDF1 mutation impaired intercellular and cell-matrix adhesion in ameloblasts. As a result, ameloblast differentiation was hampered through excessive nuclear yes-associated protein (YAP) accumulation and overactivation of downstream proliferative genes. Pharmacological blockade of YAP and TEA domain family member 1 (TEAD1) interaction rescued the mutant phenotypes. Taken together, Kdf1 mutation compromised murine amelogenesis through adhesion defects and subsequent Hippo-YAP dysregulation.
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2026-04-24 | Slc13a5 Expression in Ameloblast-Like Cells and Tooth Organ Cultures: A Platform for Therapeutic Studies
Mutations in SLC13A5, encoding the sodium-dependent citrate transporter (NaCT), cause developmental and epileptic encephalopathy 25 (DEE25), a disorder characterized by severe neurological impairment and enamel defects, including hypoplastic amelogenesis imperfecta. Although the neurological features of DEE25 are well documented, the mechanisms underlying enamel abnormalities remain poorly understood. In this study, we established in vitro and ex vivo systems to investigate NaCT function in enamel development and to support future gene therapy approaches. Mouse ameloblast-like LS8 cells were transfected with Slc13a5 expression plasmids to evaluate transfection efficiency, as well as gene and protein expression. Transient overexpression of Slc13a5 resulted in increased mRNA levels and detectable NaCT protein, with peak transcript expression at 48 hours and maximal protein and GFP reporter signal at 72 hours post- transfection. Immunocytochemistry further confirmed successful NaCT expression. To model enamel defects ex vivo, tooth organ cultures were established from wild-type and Slc13a5 R337*/R337* mouse molars. Mutant tooth germs in culture reproduced key pathological features observed in vivo, including irregular, ectopic mineral deposition. These findings demonstrate that the organ culture system can partially recapitulate the in vivo phenotype and serve as a platform for evaluating short-term gene delivery efficiency. Together, these results validate LS8 cells and tooth organ cultures as complementary platforms for studying Slc13a5 function and optimizing gene delivery strategies. This work provides a foundational step toward the development of adeno-associated virus (AAV)-based therapeutic approaches aimed at mitigating NaCT function and improving enamel defects associated with DEE25.
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