This study investigates the microstructural and mechanical characteristics of primary teeth affected by ROD. A total of two ROD-affected primary teeth from two different cases underwent clinical examinations. In addition to control samples of caries-free retained primary teeth, the affected samples were examined using micro-computed tomography (micro-CT), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and nanoindentation analysis. Clinical findings revealed yellowish discoloration, rough surfaces, and root resorption on the affected teeth. Radiographs indicated hypocalcified enamel, widened pulp chambers, and delayed development of permanent teeth. Micro-CT showed affected teeth with thinner and uneven enamel, disordered dentin, and reduced mineral density. XRD analysis found reduced crystallinity. SEM and TEM analyses revealed hypoplastic and loosely packed enamel crystals, whereas dentin exhibited disorganized collagen fibrils and poorly mineralized crystals. EDS analysis showed a reduced calcium/phosphorus ratio and an increased magnesium/calcium ratio in the affected enamel. Nanoindentation tests found reduced hardness and elastic modulus in ROD-affected enamel compared with control teeth. ROD-affected primary teeth display significant microstructural abnormalities and compromised mechanical properties, underscoring the need for early intervention and long-term monitoring to prevent complications.

Regional odontodysplasia (RO) is a rare developmental anomaly affecting dental tissue formation, typically confined to a single quadrant. It manifests through hypoplastic enamel, irregular dentin, short roots with open apices, and a characteristic "ghost-like" radiographic appearance. Its etiology remains unclear, with vascular, genetic and inflammatory factors proposed. In this study, we report the case of a 15-year-old female with mandibular RO affecting canine, premolars, and molars, focusing on the clinical, radiographic, and microscopic analysis of the affected teeth, including mineral density evaluation. The 2nd premolar and first and second molars (teeth 35, 36, 37) exhibited severe morphological defects and were extracted due to extreme root shortening (40 %, 90 %, and >95 % reduction), while alveolar bone height remained preserved. The canine and 1st premolar were affected to a lesser extent and were conserved upon orthodontic treatment plan. Scanning electron microscopy revealed slight decreases in the number and diameter of the dentinal tubules in the affected teeth compared with those in the control teeth. Contrary to many reported cases of RO, mineral density analysis of enamel and dentin revealed no significant differences between affected and normal teeth. The observations reported in this case suggest that resorptive changes, possibly influenced by inflammatory factors, could contribute to the observed root anomalies. The preservation of alveolar bone height provides a favourable prognosis for prosthetic rehabilitation. These findings help elucidate the structural and functional implications of ROs. This study highlights the importance of early diagnosis and multidisciplinary management for optimal outcomes.

Regional odontodysplasia (RO) is a rare developmental dental anomaly with unknown prevalence. Current knowledge is largely limited to individual case reports. This study aims to present epidemiological data, clinical features, and radiographic characteristics of pediatric and adolescent patients with RO in South Korea. In this multicenter cohort study, we prospectively and retrospectively recruited participants from 11 university dental hospitals. Patients aged < 19 years diagnosed with RO were included in this study. In prospective cases, epidemiological information, family history, and clinical and radiographic data were collected after obtaining parental consent. All data were anonymized and stored using a study-specific data management system. Age at diagnosis ranged from 2 to 12 years, with a higher incidence in males. RO was more commonly observed in the maxilla, and all patients exhibited delayed eruption and development. The treatment approaches vary widely and include observation, extraction, pulp therapy, crown restoration, prosthetic rehabilitation, and orthodontic treatment. This multicenter study provides the first comprehensive dataset on RO in Korean children and adolescents. These findings will contribute to the development of clinical guidelines and inform future healthcare policies for the management of rare dental anomalies.

Regional odontodysplasia (RO) is a rare developmental anomaly involving both mesodermal and ectodermal dental tissues. It is characterized by hypoplasia and hypomineralization of enamel and dentin affecting a group of neighboring teeth and may involve primary, permanent dentition or both. Wide pulp chambers and thin, poorly defined hard tissue outlines, described as "ghost teeth," are typical radiographic features. A case of the long-term management of a young girl suffering from RO in the left maxilla is described in the present report. The patient was 3 years old when first presented in the clinic and was treated for the subsequent 12 years by a multidisciplinary team comprised of a pediatric dentist, orthodontist, and prosthodontist. The report encompasses a detailed description of the clinical and radiographic findings of the patient. It also describes the prosthodontic treatment applied to alleviate the aesthetic handicap brought by the extraction of the affected teeth, as well as the orthodontic interventions to establish the normal eruption and settlement of the remaining dentition. A continuing and steady follow-up of RO cases is necessary in order to keep pace with the needs arising from the loss of affected teeth and to ensure the normal growth of the oral issues.

Diseases that affect teeth can change their structure and the distribution and expression of amelogenin (AMELX) and dentin-sialophosphoprotein (DSPP). This study aimed to conduct a histopathological, ultrastructural, and immunohistochemical comparison of AMELX and DSPP in teeth from patients with amelogenesis imperfecta (AI), dentinogenesis imperfecta (DI), osteogenesis imperfecta (OI), regional odontodysplasia (ROD), and control teeth. Additionally, a model of the structure of the affected primary teeth is proposed. This case series study examined 27 affected teeth with various diseases and 14 control teeth. Some teeth were analysed using light microscopy, polarised light, and scanning electron microscopy, while others underwent decalcification for histological analysis and immunohistochemistry with AMELX and DSPP antibodies. Teeth with hypoplastic AI exhibited thin enamel and abnormal or absent prismatic structure. In hypomineralised AI, the prismatic structure displayed minor alterations, while severe cases revealed remnants of enamel matrix and the presence of amelogenin. Teeth showing both types of AI and controls presented DSPP in peritubular dentin. DI and OI cases showed reduced dentinal tubule density, with loss of parallelism and varying diameters. The principal difference between DI and OI was seen with anti-DSPP antibody; in OI, a strong peritubular and intertubular immunolabeling was observed, while DI displayed minimal labeling in peritubular dentin. In ROD, enamel and dentin were thin with irregular prisms and tubules, with anti-AMELX and anti-DSPP demonstrating mild immunostaining. The study of teeth with AI, DI, OI, and ROD contributes to differentiating these pathosis, with DSPP immunostaining particularly distinguishing DI from OI.