Sponastrime dysplasia is an extremely rare autosomal recessive spondyloepimetaphyseal dysplasia characterized by short stature, midface hypoplasia, nasal alterations, and dental anomalies. This is, to date, the first comprehensive report on oral and craniofacial findings, and on subjective oral health-related quality of life as clinically and radiologically examined in two adults with sponastrime dysplasia. Both subjects had typical features of sponastrime dysplasia with disproportionate short stature, hypertelorism and midface hypoplasia, and variants in the TONSL gene. One had a severe phenotype (adult height 91 cm), whereas the other exhibited moderate severity (adult height 135 cm). The notable variation in the disorder severity was also expressed in dental manifestations. Dentin dysplasia type I-like abnormalities were seen in tooth eruption and morphology. Dental roots were shortened in both individuals. The individual with severe growth failure had lost several permanent teeth and reported a moderate level of discomfort and impairment due to oral health issues, as evaluated with the Oral Health Impact Profile questionnaire. In contrast, the other individual had a full permanent dentition and minimal negative impact on oral health-related quality of life. Both had short jaw lengths and face height. The anteroposterior jaw relationships were normal. The jaws of the individual with a severe phenotype were retrognathic in relation to the skull base. Both had prominent forehead. Due to significant craniofacial and dental involvement, individuals with sponastrime dysplasia should be regularly followed by a multidisciplinary medical team including a dentist, to maintain individuals' oral health and oral health-related quality of life.

Nuclear factor I-C (NFIC) plays a critical role in regulating epithelial-mesenchymal crosstalk during tooth development. However, it remains largely unknown about how NFIC functions in dentin and enamel formation. In the present review, we aim to summarize the most recent discoveries in the field and gain a better understanding of the roles NFIC performs during tooth formation. Nfic-/- mice exhibit human dentin dysplasia type I (DDI)-like phenotypes signified by enlarged pulp chambers, the presence of short-root anomaly, and failure of odontoblast differentiation. Although loss of NFIC has little effect on molar crown morphology, researchers have detected aberrant microstructures of enamel in the incisors. Recently, accumulating evidence has further uncovered the novel function of NFIC in the process of enamel and dentin formation. During epithelial-mesenchyme crosstalk, the expression of NFIC is under the control of SHH-PTCH-SMO-GLI1 pathway. NFIC is closely involved in odontoblast lineage cells proliferation and differentiation, and the maintenance of NFIC protein level in cytoplasm is negatively regulated by TGF-β signaling pathway. In addition, NFIC has mild effect on ameloblast differentiation, enamel mineralization and cementum formation. NFIC plays an important role in tooth development and is required for the formation of dentin, enamel as well as cementum.

Dentin dysplasia is a rare hereditary disorder, transmitted by autosomal dominant mode, affecting both dentin and pulp. In Type I crown morphology is normal, but root dentin organization loss leads to shorter roots. Mutations in the SSUH2, VPS4B and SMOC2 genes have been reported as responsible for this condition. Orthodontic treatment was conducted on an 11-year-old female patient presenting the disorder along with bilaterally impacted permanent maxillary canines, in close proximity to the roots of the lateral and central incisors. Treatment plan included lateral incisors extraction, surgical exposure and traction of the impacted canines. Light forces were applied from a custom-made trans-palatal arch. Comprehensive orthodontic treatment was performed using edgewise appliances. After 3 years and 2 months, group function occlusion was achieved. The canines underwent composite resin restorations. At one year post-retention, the dentition remained stable. Family-based genetic analysis did not reveal any mutations in the aforementioned genes pointing to further genetic heterogeneity of this disorder. As dental medicine becomes more sophisticated and personalized, the association between mutation type/function and orthodontic treatment response may provide useful therapeutic insights. The positive treatment response of the presented case could be attributed to a more "benign" mutation awaiting to be identified.

VPS4B (vacuolar protein sorting 4B), a member of the ATPase associated with diverse cellular activities (AAA) protein family, is a component of the endosomal sorting complexes required for transport machinery which regulates the internalization and lysosomal degradation of membrane proteins. We previously reported that VPS4B is one of the pathogenic genes related to dentin dysplasia type I, although its function was largely unknown. To investigate the role of VPS4B in tooth development, we deleted the Vps4b gene in mice. We found that heterozygous knockout mice (Vps4b+/- ) developed normally and were fertile. However, homozygous deletion of the Vps4b gene resulted in early embryonic lethality of Vps4b-/- mice at approximately embryonic day 9.5 (E9.5). To investigate the underlying molecular mechanisms, we examined the molecular functions of VPS4B in vivo and in vitro. Cell experiments showed that VPS4B influenced the proliferation, apoptosis, and cell cycle of transfected human neuroblastoma cells (IMR-32 cells) with over-expression or knockdown of VPS4B. Moreover, qRT-PCR detection showed that the mRNA expression levels of apoptosis-, cell cycle-, and endocytosis-related genes was significantly down or up-regulated in RNA interference-mediated knockdown of VPS4B in IMR-32 cells and Vps4b+/- E12.5 embryos. We accordingly speculated that signal transduction disorders of cell endocytosis are a contributing factor to the prenatal lethality of Vps4b-/- mice.

Dentin dysplasia (DD) Type I is a developmental condition affecting dentin, inherited in an autosomal-dominant pattern or occurring due to a new mutation. Whilst the crowns of DD Type I affected teeth appear clinically normal, the roots are blunt and shortened. Pulp necrosis and periapical pathoses may be seen in the absence of obvious causes. Pulp stones and calcifications are frequently encountered. Endodontic management of DD may be challenging. A case of DD Type I, sub-classification d, in which spontaneous irreversible pulpitis developed on three mandibular incisors is documented. The case was managed by conventional endodontic treatment. Knowledge of this uncommon dental condition may assist dentists to adequately diagnose and manage these cases. Extraction should not be considered the first-line treatment option when sufficient root length is available to attempt endodontic treatment. Referral for medical evaluation is recommended to rule out systemic diseases which may mimic this condition.