Chinese Journal of Dental Research

Dentine, the predominant structural element of the tooth, exhibits varying structural components, properties and mineralisation patterns across different regions. During dentinogenesis, diverse non-collagenous proteins (NCPs) play essential and varied roles in the mineralisation process. This paper systematically reviews the spatial distribution of NCPs across different dentine substructures and highlights their multifarious functions and collaborative interplay in governing the intricate mineralisation process. Specifically focusing on phosphorylated and glycosylated proteins, this review underscores their precisely programmed dynamic balance in orchestrating a series of distinct morphological patterns of dentinal substructures with varying degrees of mineralisation. By discussing the collaboration and balance of NCPs in dentine mineralisation, this paper also aims to advance the understanding of biomineralisation and provide valuable insights into developing highly biomimetic remineralisation strategies for dental applications. Keywords: biomineralisation, collagen matrix, dentine, hydroxyapatite, non-collagenous proteins

Cystic lesions in the jaws are frequently associated with impacted teeth, and include dentigerous cysts, odontogenic keratocysts, unicystic ameloblastoma and adenoid odontogenic tumours. The most common treatment modality is enucleation of cysts with removal of the impacted tooth. Marsupialisation is a more conservative treatment modality than enucleation and is considered the first-line treatment, especially in the initial management of benign cystic lesions during the mixed dentition period. Depending on the size of the lesion, the position of the impacted tooth and the available space, the majority of teeth can erupt spontaneously after marsupialisation. A multidisciplinary approach has been used in recent years for management of these lesions. Orthodontic traction is sometimes performed on the impacted tooth to guide tooth eruption postoperatively. When an impacted tooth or teeth within cystic lesions are preserved and functional occlusion is obtained, the patient’s quality of life can improve significantly. Prospective clinical trials with a larger patient cohort are necessary to determine the clinical benefit of the conservative approach with marsupialisation or surgical-orthodontic treatment of impacted teeth in cystic lesions since only studies of small groups of patients or case reports have been published to date. Keywords: cystic lesions, enucleation, impacted tooth, marsupialisation, orthodontic traction

Objective: To explore the differential translation profiles and coding products of human jaw bone marrow mesenchymal stem cells (h-JBMMSCs) during osteogenic differentiation. Methods: Ribo-seq was used to examine the differential translated genes (DEGs), open reading frames (ORFs) and genes associated with the osteogenic differentiation phase of h-JBMMSCs. Western blotting (WB) was performed to detect the expression of osteocalcin (OCN) and bone sialoprotein (BSP). Alkaline phosphatase (ALP) activity and alizarin red staining (ARS) were used to detect osteogenic differentiation. A lentivirus containing 5’UTR-ORF-GFPmut was designed to transfect h-JBMMSCs, and fluorescence and green fluorescent protein (GFP) expression were analysed. The SNHG1 peptide was synthesised for osteogenic induction and to detect osteogenic markers. Results: A total of 53,432 ORFs were detected and 199 candidate translation sORFs, including lncRNA SNHG1, were identified after removing the annotated protein-coding genes. In addition, the 5’UTR-ORF-GFPmut showed green fluorescence and expressed GFP. Knockdown of the lncRNA SNHG1 increased the ALP activity of h-JBMMSCs, promoted the expression of OCN and BSP, and enhanced the intensity of ARS and calcium ion content. However, overexpression of lncRNA SNHG1 and the SNHG1 polypeptide inhibited the osteogenic differentiation of h-JBMMSCs. Conclusion: LncRNA SNHG1 inhibited the osteogenic differentiation of h-JBMMSCs. LncRNA SNHG1 can encode a peptide of 19-amino acid and inhibit the osteogenic differentiation of h-JBMMSCs. Keywords: h-JBMMSCs, lncRNA SNHG1, osteogenic differentiation, peptide, ribosome profiling

Objective: To assess the clinical efficacy of 5-aminolaevulinic acid photodynamic therapy (5-ALA-PDT) in treating oral potentially malignant disorders (OPMDs) and investigate the utility of toluidine blue staining and autofluorescence examination for monitoring the efficacy of 5-ALA-PDT. Methods: A prospective cohort study was conducted, including 75 OPMDs patients who underwent 5-ALA-PDT and follow-up observation. The patients’ lesion size and clinical presentation were recorded to evaluate the clinical efficacy of 5-ALA-PDT. Toluidine blue staining and autofluorescence examination were performed as auxiliary monitoring methods, aiming to assess their diagnostic capabilities as non-invasive examinations for detecting pathological oral epithelial dysplasia (OED) and explore their monitoring value for the clinical efficacy of 5-ALA-PDT. Results: Toluidine blue staining showed a sensitivity of 62.2% and a specificity of 42.9% for diagnosing OED, whereas autofluorescence examination showed a sensitivity of 67.2% and a specificity of 64.3%. The parallel combination of both examinations increased the sensitivity to 77.0%, whereas the series combination increased the specificity to 71.4%. After 5-ALA-PDT, 38.7% of patients with OPMDs achieved complete remission, with an overall response rate of 92%. Persistent positive toluidine blue staining after 5-ALA-PDT treatment was significantly associated with treatment failure. The clinical efficacy of 5-ALA-PDT gradually decreased in patients with aggravation, stable or improved lesions from non-invasive examinations both before and after treatment. Conclusion: 5-ALA-PDT demonstrates significant efficacy in treating OPMDs by effectively eliminating lesions. Toluidine blue staining and autofluorescence examination have certain diagnostic capabilities for OED and can be used for monitoring efficacy during 5-ALA-PDT treatment. Keywords: autofluorescence imaging, oral potentially malignant disorders, photodynamic therapy, toluidine blue

Objective: To investigate the role of the biosynthetic gene cluster BGC3 of Streptococcus mutans (S. mutans) in the process of dental caries. Methods: BGC3 and ∆BGC3 S. mutans strains were constructed and their growth curves were evaluated. Acid production capacity was assessed by evaluating pH reduction levels over identical culture periods. The survival of bacteria in phosphate citrate buffer solution (pH 3.0) was quantified. The expression levels of virulence genes (atpF, gtfC, gtfD, spaP, vicR and ftf) were analysed using the qPCR. Co-culture experiments were conducted to evaluate bacterial adaptability. Bacterial viability was determined by microscopical examination of live/dead staining. Results: Deletion of BGC3 did not significantly impact S. mutans growth or acid production in biofilms. The ∆BGC3 strain exhibited enhanced acid resistance and higher expression levels of virulence genes compared to the wild type. In addition, ∆BGC3 exhibited superior bacterial viability in the co-culture system. Conclusion: BGC3 affected the acid resistance and expression of caries-related genes in S. mutans. The BGC3 knockout strain exhibited a more robust survival capability than the wild-type strain. Keywords: biofilm, biosynthetic gene clusters, dental caries, Streptococcus mutans, virulence genes

Objective: To establish a rapid and high-throughput clinical matrix-assisted laser desorption ionisation-time of flight mass spectrometry (CLIN-MALDI-TOF-MS) method for identifying oral microorganisms and to determine the distinct representative species across various oral sites. Methods: Samples were collected from 54 volunteers from four oral sites: saliva, supragingival plaque, oral mucosa and dorsum of the tongue. Microorganisms were cultured on brain heart infusion (BHI) plates and identified using CLIN-MALDI-TOF-MS after processing with specific reagents for mass spectrometry. Results: The method identified 15 species and 12 genera of microorganisms, revealing significant differences in microbial composition among the oral sites, and different oral cavity sites harboured distinct relatively representative species. Conclusion: The CLIN-MALDI-TOF-MS method offers a rapid and efficient approach for large-scale microbial identification in the oral cavity, providing a suitable approach for future experimental teaching and highlighting the importance of site-specific microbial communities in oral health research. Keywords: CLIN-MALDI-TOF-MS, oral microbe identification, rapid and high-throughput identification, representative species differences

Objective: To determine whether the targeting age should be adjusted for the National Children’s Pit and Fissure Sealant (PFS) Programme. Methods: Statistical analysis was conducted on the results of oral health examination results of school-aged children in regions covered by the National Children’s Oral Disease Comprehensive Intervention Programme (NCODCIP) in 2018. We analysed the eruption status and dental caries condition of the children’s four first permanent molars (FPMs) and performed statistical tests for the data. Results: Data analysis from 811,855 children aged 6 to 9 years showed that the complete eruption rate (CER) of the FPMs in Chinese children aged 6 years was 67.2%, and reached 94.1% by age 9. Before the implementation of the PFS Programme, the prevalence of dental caries in 6-year-olds was 11.0%, and 23.2% by age 9. Caries prevalence was higher in girls than boys. The growth rate of caries prevalence slowed with age. Conclusion: Our study indicated that the eruption time of FPMs in Chinese children has been earlier than predicted, and the caries prevalence was more severe than expected. Therefore, it is recommended that the targeting age for the National PFS Programme be lowered from 7 years old to 6 years old. Keywords: caries prevalence, complete eruption rate, first permanent molars, pit and fissure sealant