Tooth eruption is a localised event whereby the signals for eruption for a given tooth are synthesised in the dental follicle of that tooth with a possible cross talk of signals coming from the adjacent stellate reticulum. The eruption process requires alveolar bone resorption that is primarily regulated by the dental follicle. This is reflected by the fact that failures of eruption often can be traced to either osteoclast deficiencies or to dental follicle abnormalities. Recent advances in application of molecular techniques to animal models allowed for better understanding of gene regulatory events involved in the physiology of tooth eruption. This article attempts to consolidate and organise the facts that offshoot from animal studies.
Tooth Eruption ; Dental Sac ; Molecular Biology

Occlusal rehabilitation is an effective means of treating tooth wear, edentulous jaws and other oral diseases. Among them, full-mouth fixed occlusal reconstruction can effectively restore aesthetics and function, but the complexity of the clinical process, the high sensitivity of the technique, and the high incidence of various complications have always drawn much attention. With the application and development of digital technology in occlusal rehabilitation, the treatment outcome has been improved compared with traditional treatment. However, there are many kinds of digital technology with different efficacy, how to build an efficiently standardized digital clinical technical solution is a current difficulty. Therefore, combined with the long-term work of the department of prosthodontics in our hospital, in this paper, the minimum (occlusal perception of thickness) and maximum (centric relation) geometric quantities which should be paid attention to during reconstruction are put forward. We systematically organized the clinical procedure of digital full-mouth fixed occlusal rehabilitation used in our department for a long time. In conclusion, a 5-stage 19-step or n-step solution (5-19N for short) characterized by "from large to small" restorative space splitting logic is proposed. It has a certain reference value for the future use of digital technology to deal with complex occlusal rehabilitation cases.
Humans ; Dental Occlusion ; Computer-Aided Design ; Mouth, Edentulous/rehabilitation*

OBJECTIVES: This study aimed to investigate the incidence, imaging characteristics, and clinical manifestations of the eruption failure of deciduous molars using panoramic radiographs to provide a foundation for diagnosis and treatment in this population. METHODS: This study retrospectively reviewed panoramic radiographs of children aged 4-8 years obtained from Stomatology Hospital, Zhejiang University School of Medicine between January 2021 and December 2023. A total of 31 331 subjects were included for the radiographic assessment of the tooth eruption failure of deciduous molars. Incidence, radiographic characteristics, and associated complications were documented. Statistical analysis was performed using SPSS 26.0. RESULTS: The incidence of the eruption failure of deciduous molars among children aged 4-8 years was 0.94% (296/31 331). The rate was 1.55 times higher in females than in males, demonstrating a significant gender difference (P<0.001). Among the affected deciduous molars, mandibular first deciduous molars accounted for 76.4%, followed by the mandibular second deciduous molars (13.8%), and the maxillary deciduous molars collectively comprised 9.8%. The severity of eruption disorders was significantly associated with the mesial and distal tilting of adjacent teeth and elongation of the antagonist (P<0.001). CONCLUSIONS The incidence of the eruption failure of deciduous molars in children aged 4-8 years was 0.94%, with a high prevalence in females and a predilection for the mandible, particularly the mandibular first deciduous molar. For deciduous molars with severe eruption failure, early intervention is crucial to mitigate complications such as malocclusion and space loss.
Humans ; Child ; Child, Preschool ; Tooth, Deciduous/diagnostic imaging* ; Female ; Molar/physiopathology* ; Male ; Retrospective Studies ; Tooth Eruption ; Radiography, Panoramic ; Incidence

OBJECTIVES: Through the investigation of the microhardness and microstructure of permanent tooth enamel at various eruption stages during childhood, this research offers references for the early prevention of childhood dental caries. METHODS: Forty-five premolars extracted due to orthodontic reasons were collected and screened. These premolars were divided into three experimental groups according to the time since eruption: Group A (erupted for 0-1 year), Group B (erupted for 1-3 years), and Group C (erupted for 3-5 years). Additionally, the third molars that were extracted due to impaction and had not erupted were selected as the control group, with 15 teeth in each group. Samples were prepared, and the surface microhardness, microstructure, and elemental composition of the enamel were measured using Vickers microhardness tester, scanning electron microscope, and electron probe, respectively. RESULTS: Compared with that in the control group, the microhardness of enamel in groups A, B, and C increased with prolonged eruption time, the surface porosity structure decreased considerably, the contents of Na and Mg on the surface decreased, and that of F increased (P<0.05). CONCLUSIONS The microhardness and microstructure of enamel in permanent teeth at different stages vary. Permanent teeth are at a substantially higher risk of caries within one year after eruption, and early prevention should be emphasized.
Dental Enamel/ultrastructure* ; Humans ; Hardness ; Dental Caries/prevention & control* ; Microscopy, Electron, Scanning ; Tooth Eruption ; Bicuspid/chemistry* ; Dentition, Permanent ; Child ; Child, Preschool

Tooth resorption is the degradation of dental hard tissue due to the continuous action of odontoclasts. External cervical resorption refers to the cervical resorption of a tooth due to destruction and/or defects of the periodontal ligament or subepithelial cementum. In this paper, we report a case of maxillary central incisor with external cervical resorption after dental trauma and orthodontic treatment. The resorption site and morphology of the affected tooth were thoroughly analyzed by cone beam computed tomography prior to the operation. Dental operating microscope and layered external repair with composite resin and bioceramics ensured a perfect restoration of the resorption, and the vital pulp was preserved. The 6-year follow-up indicated a favorable treatment effect.
Humans ; Composite Resins ; Cone-Beam Computed Tomography ; Incisor/surgery* ; Maxilla ; Microsurgery/methods* ; Tooth Resorption/etiology*

Long-term dental implant stability is governed by the synergistic regulation of multiple factors, with occlusal parameters and marginal bone loss (MBL) progression being of paramount importance. Progressive MBL undermines mechanical retention, predisposing implants to micromotion and jeopardizing their long-term survival. Accumulating evidence has revealed that homeostatic occlusion imbalance, characterized by excessive occlusal loading, aberrant occlusal contacts, and dysfunctional guidance, significantly increases the incidence of peri-implant bone loss, thereby disrupting biomechanical homeostasis. Therefore, this manuscript delineates the mechanistic role of steady-state occlusal imbalance in driving peri-implant MBL and proposes a homeostatic occlusion-based strategy for preventing and controlling such bone loss, aiming to enhance the long-term stability of dental implants.
Humans ; Dental Implants ; Homeostasis ; Dental Occlusion ; Alveolar Bone Loss/prevention & control* ; Biomechanical Phenomena

Objective: To determine the effect of the impacted position of the maxillary canine on the root resorption of the adjacent incisor using Cone-beam Computed Tomography (CBCT) imaging. Methods: This was an analytic quantitative study. The research sample determined CBCT images of treatment patients at the Orthodontic Specialist Policlinic in Dental Hospital of Airlangga University over a three-year period and secondary data taken from Pramita Laboratory. CBCT photos that met the inclusion criteria, including mesially impacted canine or close to central or lateral incisors with completely formed anatomy were then analyzed. Multiple linear regression was used to determine x-axis, y-axis, z-axis position of the impacted canine on the severity of root resorption of the adjacent incisor, and the effect of impacted canines on all axes simultaneously on the severity of root resorption of the adjacent incisors. Results: The position of the impacted canine in the x-axis and z-axis planes had a significant influence on the root resorption of the adjacent incisor. Meanwhile, impacted canine from the y-axis plane showed non-significant influence on the root resorption. Conclusion The position of the impacted canine when viewed in all planes of the tooth axis has a significant effect on the severity of root resorption of the adjacent incisor
Root Resorption ; Cone-Beam Computed Tomography

Objective: To detect and analyze the characteristics of oral microbiota in species composition, function and metabolism among caries, periodontitis and oral healthy individuals, hunting for the microbiome-derived biomarkers with specificity and sensitivity to estimate the occurrence of these two diseases. Methods: Saliva samples were collected from 10 patients with high caries risk [decayed-missing-filled teeth (DMFT)≥6, HC group] in Department of Endodontics, 10 patients with periodontitis of grade Ⅱ A-Ⅲ C (PG group) in Department of Periodontology and 10 oral healthy individuals (HH group) from School of Stomatology, The Fourth Military Medical University during from March 2022 to June 2022. A baseline examination was conducted on all participants, including their oral conditions of caries and periodontal health. Metagenomic sequencing (Illumina PE150 platform) and liquid chromatography-mass spectrometry were used to detect microorganisms and their metabolites in the samples respectively. The sequencing data were analyzed to obtain the information of microbial taxonomic composition, functional genes and metabolites in each group of samples. The basic oral conditions and saliva samples of subjects in each group were evaluated and collected by the same professional endodontist. Results: There were no significant difference in baseline characteristics such as age and sex among the subjects in each group (P>0.05). DMFT in HC group (9.0±1.7) was significantly higher than that in HH group (0) and PG group (0) (F=243.00, P<0.001). Sequencing data analysis showed that the taxonomic compositions of salivary microbiota in each group were mainly Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria at the phylum level, and Streptococcus, Neisseria, Rothia, Prevotella at the genus level. Differential analysis showed that, compared with the HH group, HC group and PG group had significant differences in taxonomic composition (P<0.05), and the most significant among them was Prevotella. At the species level, Prevotella pallens was the most significant change in HC group, and Porphyromonas gingivalis in PG group. Metabolite analysis showed that there were significant differences in metabolites between HC group and PG group. The results showed that, compared with the HH group, the most significant metabolite change was 3-hydroxy-1, 5-diphenylpentan-1-one in HC group (P=0.001) and N1 acetylspermine in PG group (P=0.002) respectively. Compared with the PG group, the metabolite of HC group with the most significant difference is D-glucosamine 6-phosphate (P=0.006). The metabolism gene function analysis showed that, the enrichment of carbohydrate metabolism related genes was highest in HC group, followed with HH group, and it was lowest in PG group. In addition, compared with the HH group, the abundance of functional genes related to glucose metabolism, such as ABC transporter and phosphotransferase system, were significantly decreased in PG group (P<0.05), but significantly increased in HC group (P<0.05). Conclusions: There is a significant correlation between the alternation of carbohydrate metabolism of salivary microbiota with the occurrence of caries and periodontitis. In the future, Prevotella pallens and 3-hydroxy-1, 5-diphenylpentan-1-one may be the potential biomarkers of caries; while Porphyromonas gingivalis and N1 acetylspermine work in the predictions of periodontitis.
Humans ; Saliva/microbiology* ; Dental Caries Susceptibility ; Periodontitis/microbiology* ; Microbiota/genetics* ; Porphyromonas gingivalis/genetics* ; RNA, Ribosomal, 16S/genetics*

OBJECTIVE: To investigate the effects of novel bioactive glasses (BG) including PSC with high phosphorus component and FBG with fluorine-doped element on promoting remineralization of artificial dentin caries. METHODS: (1) BGs were used in this study as follows: PSC (10.8%P₂O₅-54.2%SiO₂-35.0%CaO, mol.%) were synthesized using phytic acid as the phosphorus precursor through sol-gel method. FBG (6.1%P₂O₅-37.0%SiO₂-53.9%CaO-3.0%CaF₂, mol.%) and 45S5(6.0%P₂O₅-45.0%SiO₂-24.5%CaO-24.5%Na₂O, mol.%) were synthesized by traditional melt method. (2) The above BGs were soaked in simulated body fluid (SBF) for 24 hours. Then X-ray diffraction (XRD) was used to analyze the formation of hydroxyapatite (HA) crystals. (3) Prepared 1 mm thick dentin slices were soaked in 17% ethylene diamine tetraacetic acid (EDTA) for 1 week to demineralize the dentin. Then the dentin slices treated by BG were soaked in SBF for 1 week. Field emission scanning electron micro-scopy (FE-SEM) was used to observe the surface morphology of the dentin slices. (4) Four cavities were prepared to 1 mm depth in each 2 mm thick dentin slice, then were treated with lactic acid for 2 weeks to form the artificial dentin caries. Wax, mineral trioxide aggregate (MTA), PSC and FBG were used to fill four cavities as blank control group, MTA group, PSC group and FBG group respectively. Then the spe-cimens were soaked in SBF for 4 weeks. The changes of depth and density of demineralized dentin were analyzed using Micro-CT before filling and after 2 and 4 weeks filling. RESULTS: (1) PSC and FBG promoted mineral formation on the surfaces of the demineralized dentin. And the speed was faster and crystallinity was higher in PSC group than the FBG and 45S5 groups. (2) The increased mineral density of artificial dentin caries in PSC group were (185.98 ± 55.66) mg/cm³ and (213.64 ± 36.01) mg/cm³ 2 and 4 weeks after filling respectively, which were significantly higher than the control group [(20.38 ± 7.55) mg/cm³, P=0.006; (36.46 ± 10.79) mg/cm³, P=0.001]. At meanwhile, PSC group was also higher than MTA group [(57.29 ± 10.09) mg/cm³; (111.02 ± 22.06) mg/cm³], and it had statistical difference (P=0.015; P=0.006). The depth of remineralized dentin in PSC group were (40.0 ± 16.9) μm and (54.5 ± 17.8) μm 2 and 4 weeks respectively, which were also statistically different from the control group (P =0.010;P=0.001). There were no statistical differences between the control group and MTA group. The above effects of FBG group were between PSC and MTA. CONCLUSION PSC has advantages in the speed, quality and depth of mineral deposition in the demineralized layer of artificial dentin caries. It would be expected to be an ideal material to promote the remineralization of dentin caries.
Dentin ; Silicon Dioxide/pharmacology* ; Dental Caries Susceptibility ; Minerals/pharmacology* ; Phosphorus/pharmacology* ; Tooth Remineralization/methods*

OBJECTIVES: This study aimed to analyze the bacteria in dental caries and establish an optimized dental-ca-ries diagnosis model based on 16S ribosomal RNA (rRNA) data of oral flora. METHODS: We searched the public databa-ses of microbiomes including NCBI, MG-RAST, EMBL-EBI, and QIITA and collected data involved in the relevant research on human oral microbiomes worldwide. The samples in the caries dataset (1 703) were compared with healthy ones (20 540) by using the microbial search engine (MSE) to obtain the microbiome novelty score (MNS) and construct a caries diagnosis model based on this index. Nonparametric multivariate ANOVA was used to analyze and compare the impact of different host factors on the oral flora MNS, and the model was optimized by controlling related factors. Finally, the effect of the model was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: 1) The oral microbiota distribution obviously differed among people with various oral-health statuses, and the species richness and species diversity index decreased. 2) ROC curve was used to evaluate the caries data set, and the area under ROC curve was AUC=0.67. 3) Among the five hosts' factors including caries status, country, age, decayed missing filled tooth (DMFT) indices, and sampling site displayed the strongest effect on MNS of samples (P=0.001). 4) The AUC of the model was 0.87, 0.74, 0.74, and 0.75 in high caries, medium caries, low caries samples in Chinese children, and mixed dental plaque samples after controlling host factors, respectively. CONCLUSIONS The model based on the analysis of 16S rRNA data of oral flora had good diagnostic efficiency.
Humans ; Child ; Bacteria/genetics* ; Dental Caries/microbiology* ; Dental Caries Susceptibility ; Microbiota/genetics* ; RNA, Ribosomal, 16S