Etiological Mechanisms and Genetic/Biological Modulation Related to PTH1R in Primary Failure of Tooth Eruption.

Primary failure of eruption (PFE) is a rare disorder that is characterized by the inability of a molar tooth/teeth to erupt to the occlusal plane or to normally react to orthodontic force. This condition is related to hereditary factors and has been extensively researched over many years. However, the etiological mechanisms of pathogenesis are still not fully understood. Evidence from studies on PFE cases has shown that PFE patients may carry parathyroid hormone 1 receptor (PTH1R) gene mutations, and genetic detection can be used to diagnose PFE at an early stage. PTH1R variants can lead to altered protein structure, impaired protein function, and abnormal biological activities of the cells, which may ultimately impact the behavior of teeth, as observed in PFE. Dental follicle cells play a critical role in tooth eruption and root development and are regulated by parathyroid hormone-related peptide (PTHrP)-PTH1R signaling in their differentiation and other activities. PTHrP-PTH1R signaling also regulates the activity of osteoblasts, osteoclasts and odontoclasts during tooth development and eruption. When interference occurs in the PTHrP-PTH1R signaling pathway, the normal function of dental follicles and bone remodeling are impaired. This review provides an overview of PTH1R variants and their correlation with PFE, and highlights that a disruption of PTHrP-PTH1R signaling impairs the normal process of tooth development and eruption, thus providing insight into the underlying mechanisms related to PTH1R and its role in driving PFE.

Three years of follow-up of otodental syndrome in 3-year-old Chinese boy: a rare case report.

BACKGROUND: Otodental syndrome is an exceptionally rare autosomal dominant condition characterized by a delayed eruption of posterior teeth, globodontia, lisping, and sensorineural hearing loss. In this case report, we reported a 3-year-old Chinese boy with the otodental syndrome. CASE PRESENTATION: A 3-year-old Chinese boy was referred to our hospital with complaint of no eruption of primary canines and molars. Three years follow-up showed lately erupted bulbous primary canines with hypoplastic enamel spot, globe-shaped primary molars and sensorineural hearing loss at 4 and a half-year-old age. We diagnosed otodental syndrome in the patient's mother with hearing loss at 16-year-old age. Gene sequencing and analysis of deafness-related genes GJB2, GJB3, SLC26A4, and mtDNA did not reveal any mutation or SNPs in the patient and his mother. CONCLUSIONS: This case report highlights the importance of detailed medical, dental, and family history examination, as well as multi-disciplinary teamwork for diagnosis and treatment of otodental syndrome.

Separated root tip formation associated with a fractured tubercle of dens evaginatus: A case report.

BACKGROUND: Several previous studies have reported an unusual root formation in which a fractured apical fragment of an immature root continued to develop independent of the main root after trauma to an immature tooth. To date, there have been only rare reports of the continuing apical formation of the fractured root associated with dens evaginatus (DE). This paper presents a case of a separated root tip formation associated with a fractured tubercle of DE. CASE SUMMARY: An 11-year-old boy was referred for gingival sinus on the buccal side of the right mandibular second premolar (tooth # 45). Clinically, tooth # 45 was free of caries, but there was a sign of a fractured tubercle of DE on the occlusal surface. Radiography showed that the root canal of tooth # 45 was widely radiolucent. A separated root apex was found apically under the main root and was nearly completely formed with an apical orifice at the apical tip. Tooth # 45 was diagnosed as tubular fracture of DE with chronic apical periodontitis. A revascularization technique was recommended to treat the tooth. At 3-mo and 1-yr follow-up, the patient remained asymptomatic. Periapical radiography revealed that the separated root tip distally drifted with closure of the apex. However, the root length and thickness of the main root did not increased. CONCLUSION: Clinicians should be aware that even if tubercle of DE is fractured in an immature tooth, the root tip may be separated from the main root and completely formed.

[Construction and validation of a three-dimensional finite element model of cranio-maxillary complex with sutures in unilateral cleft lip and palate patient].

PURPOSE: To explore an effective method to construct and validate a finite element model of the unilateral cleft lip and palate(UCLP) craniomaxillary complex with sutures, which could be applied in further three-dimensional finite element analysis (FEA). METHODS: One male patient aged 9 with left complete lip and palate cleft was selected and CT scan was taken at 0.75mm intervals on the skull. The CT data was saved in Dicom format, which was, afterwards, imported into Software Mimics 10.0 to generate a three-dimensional anatomic model. Then Software Geomagic Studio 12.0 was used to match, smoothen and transfer the anatomic model into a CAD model with NURBS patches. Then, 12 circum-maxillary sutures were integrated into the CAD model by Solidworks (2011 version). Finally meshing by E-feature Biomedical Modeler was done and a three-dimensional finite element model with sutures was obtained. A maxillary protraction force (500 g per side, 20° downward and forward from the occlusal plane) was applied. Displacement and stress distribution of some important craniofacial structures were measured and compared with the results of related researches in the literature. RESULTS: A three-dimensional finite element model of UCLP craniomaxillary complex with 12 sutures was established from the CT scan data. This simulation model consisted of 206 753 individual elements with 260 662 nodes, which was a more precise simulation and a better representation of human craniomaxillary complex than the formerly available FEA models. By comparison, this model was proved to be valid. CONCLUSIONS: It is an effective way to establish the three-dimensional finite element model of UCLP cranio-maxillary complex with sutures from CT images with the help of the following softwares: Mimics 10.0, Geomagic Studio 12.0, Solidworks and E-feature Biomedical Modeler.

[Children's temperament characteristics and dental fear].

OBJECTIVE: To evaluate the relationship between children's temperament and dental fear. METHODS: 254 children(aged 4-6 years) during first dental treatment took part in the investigation. Their parents answered the Chinese preschool children's temperament scales (CPTS). The Frankl method was used to classify the degree of the children's dental fear. The K independent samples test and One-way ANOVA test were performed to find the differences of the type of temperament and the scores of temperament dimension among three groups. RESULTS: Among the 254 children(aged 4-6 years), 104 had no fear, 80 had fear and 70 had extreme fear. The incidence of dental fear in children was 59.06%. There were no statistical differences (P > 0.05) of dental fear between boys and girls. There were statistically significant differences for the type of temperament among no fear group, fear group and extreme fear group. The scores of adaptability and quality of mood were higher in the extreme fear group and fear group than that in the no fear group. The differences in scores of adaptability and quality of mood was statistically significant between the extreme fear group and no fear group. But the scores of other seven temperament dimensions had no statistical significant differences among three groups. CONCLUSION: Children's dental fear is correlated to their temperaments. The tendencies of negative mood and slow adaptability should be considered that the patients were at risk of developing dental fear problem.

[The characteristics of uncooperative children's temperament during dental treatment].

PURPOSE: To compare the temperament of uncooperative and cooperative children during dental treatment, and find out the characteristics of the uncooperative children's temperament. METHODS: Fifty-two cooperative children (aged from 3 to 7 years) and thirty-five uncooperative children (aged from 3 to 7 years) during dental treatment were included in the investigation. Their parents were asked to answer the Chinese Preschool Children's Temperament Scale (CPTS). The two independent sample's Mann-whitney test and Student's t test were performed to find the difference of the type of temperament and the temperamental dimension between the two groups. RESULTS: (1) There was a statistically significant difference (P<0.05) in the type of temperament between the uncooperative group and the cooperative group. In the uncooperative group, the number of difficult temperament children was significantly larger than that in the uncooperative group. (2) The scores of adaptability and quality of mood were significantly higher in the uncooperative group than that in the cooperative group. CONCLUSIONS: Children's cooperation in pediatric dentistry was correlated to their temperament. The tendencies of negative mood and slow adaptation and difficult temperament should be considered patients at risk of uncooperation in pediatric dentistry.