Comprehensive and sequential management of an impacted maxillary central incisor with severe crown-root dilacerations.

Tooth dilaceration refers to a dental anomaly characterized by an abrupt deviation in the longitudinal axis of tooth. Crown-root dilaceration is diagnosed in teeth with sharp angles at the cement-enamel junction. The greater the bending degree is, the less chance there is for successful teeth preservation and relocation. In this report, a clinical case of an impacted maxillary central incisor with severe crown-root dilacerations was described by means of an operative evaluation using three-dimensional dental computed tomography and a multidisciplinary approach that included surgical, orthodontic, endodontic, prosthetic and periodontal therapy.

Long-term dental intervention and laboratory examination in a patient with Vitamin D-dependent rickets type I: A case report.

RATIONALE: Vitamin D-dependent rickets type I (VDDR-I) is a rare form of rickets, which is an autosomal recessive disease caused by 1α-hydroxylase enzyme deficiency. However, long-term dental management and microscopic morphology of teeth remain largely unclear. PATIENT CONCERNS: We report the case of a 10-year-old Chinese boy complaining of yellowish-brown teeth with extensive caries. DIAGNOSES: Clinical and laboratory examinations were performed, and VDDR-I was confirmed. Scanning electron microscopy confirmed amelogenesis imperfecta. INTERVENTIONS: The patient had been taking drugs intervention for VDDR-I from the age of 3 years. The decayed teeth were treated, and metal-preformed crowns were placed to prevent further impairment. Sequence tooth extraction and remineralization therapy were also performed. OUTCOMES: After 3 years of follow-up, the patient exhibited normal tooth replacement and an acceptable oral hygiene status. However, the new erupted teeth had amelogenesis imperfecta. LESSONS: This case is the first to confirm amelogenesis imperfecta in a patient with VDDR-I that was not prevented by drug intervention. Importantly, it provides evidence that long-term dental intervention in patients with VDDR-I can result in an acceptable oral hygiene status. Therefore, early and long-term dental intervention is necessary in VDDR-I patients.

[Mechano-growth factor regulated cyclic stretch-induced osteogenic differentiation and MMP-1, MMP-2 expression in human periodontal ligament cells by activating the MEK/ERK1/2 pathway].

PURPOSE: To explore the role and mechanism of mechano-growth factor (MGF) in cyclic stretch (CS)-induced osteogenic differentiation and MMP-1, MMP-2 expression in human periodontal ligament cells (hPDLCs). METHODS: HPDLCs were isolated and transfected with si-MGF, or stimulated with MGF or MEK/ERK pathway inhibitor U0126. Cells were cultured in Flexercell system with 10% elongation at 0.1 Hz. An alkaline phosphatase (ALP) kit was used to detect ALP activity. QRT-PCR assay was performed to determine the transcript levels of MGF and osteogenic genes, including ALP, runt-related transcription factor 2 (Runx2) and osteopontin (OPN). Western bot was used to evaluate the effect on MEK/EKR1/2 signaling. Statistical analysis was performed using SPSS 19.0 software package. RESULTS: CS induced the expression of MGF in hPDLCs in a time-dependent manner (P＜0.05). In contrast to the control group, transfection with si-MGF inhibited the expression of MGF in hPDLCs (P＜0.05). Moreover, cessation of MGF dramatically suppressed ALP activity (P＜0.05) and the expression of osteogenic gene ALP, Runx2 and OPN (P＜0.05) in hPDLCs. Furthermore, down-regulation of MGF restrained the expression of MMP-1 and MMP-2, in contrast to CS group (P＜0.05). Conversely, stimulation with MGF further enhanced the effects of CS on osteogenic differentiation of hPDLCs and MMP-1, MMP-2 expression (P＜0.05). Additionally, MGC silencing abrogated CS-induced expression of p-ERK (P＜0.05), which was further enhanced following MGF treatment (P＜0.05). Simultaneously, precondition with U0126 antagonized MGF-enhanced effects on CS-triggered osteogenic differentiation and MMP-1, MMP-2 expression (P＜0.05). CONCLUSIONS: Mechano-growth factor regulates cyclic stretch-induced osteogenic differentiation and MMP-1, MMP-2 expression in human periodontal ligament cells by activating MEK/ERK1/2 signaling pathway.

Response of mandibular condyles of juvenile and adult rats to abnormal occlusion and subsequent exemption.

OBJECTIVE: The adaptation capacities of the mandibular condyle in response to mechanical stimuli might be different between juveniles and adults, but has not been compared. This study aimed to investigate whether abnormal molar occlusion and subsequent molar extraction could lead to different remodeling responses in the mandibular condyles of juvenile and adult rats. METHODS: Abnormal molar occlusion (AMO) was established in the 5- and 16-wk old rats by moving their maxillary left and mandibular right third molars distally. AMO was removed in the molar extraction group at 4 weeks but remained in the AMO group. All rats were sacrificed at 8 weeks. Micro-computed tomography, histomorphology, immunohistochemistry and real-time PCR were adopted to evaluate the remodeling of condylar subchondral bone. RESULTS: Condylar subchondral bone loss and increased osteoclastic activities were observed in both juvenile and adult AMO groups, while increased osteoblastic activities were only seen in the juvenile AMO group. Decreased bone mineral density, bone volume fraction and trabecular thickness, but increased trabecular separation, number and surface of osteoclasts and mRNA levels of TRAP, cathepsin-K, RANKL in the juvenile AMO group were all reversed after molar extraction (all P<0.05). However, these parameters showed no difference between adult AMO and extraction groups (all P>0.05). CONCLUSIONS: Abnormal molar occlusion led to degenerative remodeling in the mandibular condyles of both juvenile and adult rats, while exemption of abnormal occlusion caused significant rescue of the degenerative changes only in the juvenile rats.

Clinical, pathological and genetic evaluations of Chinese patients with autosomal-dominant hypophosphatasia.

OBJECTIVES: Hypophosphatasia (HPP) is an inherited disorder characterised by defective bone and tooth mineralisation and deficient serum and bone alkaline phosphatase activity, and it results from mutations in alkaline phosphatase (ALPL) encoding tissue-nonspecific alkaline phosphatase (TNAP). The objective of the present work was to explore the correlations between genotype and phenotype in a Chinese family affected by autosomal-dominant HPP. DESIGN: We examined all individuals of a HPP family by clinical and radiographic examinations as well as laboratory assays. Furthermore, a prematurely exfoliated tooth was observed histopathologically. Based on the clinical and pathological manifestations, the causative gene ALPL was selected for further analysis and screened for mutations. RESULTS: The proband presented the characteristic clinical features of childhood HPP such as rachitic skeletal changes, early loss of primary teeth, and short root anomalies of the permanent teeth. Histopathological evaluation of a tooth revealed a "shell" structure, severe mineralisation defects of dentin, and an absence of cementum. The patient's mother and grandfather were clinically diagnosed with adult HPP. The family showed autosomal-dominant moderate hypophosphatasia. DNA sequencing and analysis revealed a novel missense mutation (c.251A>T) in exon4 of ALPL. This mutation (p.E84V) is located in the secondary structure of TNAP's homodimer interface, and it was predicted to have a dominant negative effect. CONCLUSION: Our findings suggest the missense transversion (c.251A>T, p.E84V) should be responsible for the HPP phenotype in this Chinese family.

[Immunization with the fusion protein of GBD of Streptococcus mutans glucan binding protein-A against dental caries in SD rats].

PURPOSE: To observe the effect of immunization with the fusion protein of GBD of Streptococcus mutans glucan binding protein-A against dental caries. METHODS: Purified fusion protein of GBD of Streptococcus mutans glucan binding protein-A was used to immune SD rats by subcutaneous injection route. The rats were fed with Keyes Diet 2000 and infected by S.mutans. The caries level was determined and the result was analyzed by t test. RESULTS: The caries score of SD rats decreased in the group of immunized with GBD fusion protein,P<0.01. CONCLUSION: Immunization with GBD fusion protein resulted in significantly reduced dental caries after infection with S.mutans Ingbritt. Supported by PLA Tenth Five-Year Key Project (01Z089).