Chinese Journal of Dental Research, 02/2023

Objective: To investigate the potential effect of small molecule nitazoxanide (NTZ) on the osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Methods: Cell counting Kit-8 assay was used to examine the effect of NTZ on proliferation of BMSCs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis were used to measure the expression of osteogenic and adipogenic marker gene. Alkaline phosphatase (ALP) staining and activity assay and Alizarin Red S (ARS) staining were used to investigate the effect of NTZ on osteogenesis. Oil red O (ORO) staining assay was used to assess the impact of NTZ on adipogenesis. Results: NTZ significantly suppressed the osteogenic differentiation but promoted the adipogenic differentiation of BMSCs. Mechanistically, NTZ regulated osteogenic/adipogenic differentiation of BMSCs by inhibiting the Wnt/β-catenin signalling pathway. The addition of Wnt/β-catenin signalling pathway activator, lithium chloride, could reverse the effect of NTZ on BMSCs. Conclusion: NTZ affected osteogenic and adipogenic differentiation of BMSCs with the involvement of Wnt/β-catenin signalling pathway. This finding expanded the understanding of NTZ pharmacology and indicated that NTZ might have an adverse effect on bone homeostasis. Keywords: adipogenesis, bone marrow mesenchymal stem cells, nitazoxanide, osteogenesis, Wnt/β-catenin pathway

Objective: To determine the appropriate method to use to repair defects after ablation of squamous cell carcinoma (SCC) of the floor of the mouth (FOM). Methods: A retrospective review of 119 patients who underwent surgical resections of SCC of the FOM and flap reconstructions was conducted. A Student t test was used to examine the statistical differences in operative time, length of hospital stay and complications among groups with different reconstructions. Results: Advanced-stage patients were repaired with more free flaps than local pedicled flaps that provided more reconstructions for small-to-medium defects. The most common recipient complication was wound dehiscence, and patients in the anterolateral thigh flap group developed a greater number of overall recipient site complications compared with those in other groups. Patients undergoing local flap reconstructions had shorter operative times compared with those with free flap reconstructions. Conclusion: In contrast to a radial forearm free flap as a more appropriate reconstruction for defects involving the tongue, an anterolateral thigh flap was better suited for defects with dead spaces. A fibular flap was appropriate for massive complex defects involving the mandible, FOM and tongue. A pectoralis major musculocutaneous flap provided the last line of reconstruction for patients with relapsed SCC or high-risk factors for microsurgical reconstructions. Keywords: complication, flap, floor of the mouth, squamous cell carcinoma

Objective: To investigate the accuracy of dimensional evaluation and representation of artefacts generated by different gutta-percha (GP) cones with or without sealer with CBCT using a reproducible, standardised phantom root methodology. Methods: The reproducible artificial phantom roots with six root canal sizes from #25 to #50 and 0.04 taper were aligned according to the jaw curvature in a stone model for dimensional measurements. Each root was scanned while empty and filled with four types of filling materials. The specimens were scanned using the CS 9300 3D (Carestream Dental, Rochester, NY, USA) (at two different resolutions), 3D Accuitomo (J Morita, Kyoto, Japan) and NewTom VGi (Verona, Italy) CBCT systems. The hyperdense and hypodense axial slice artefacts from root canal sizes #40, #45 and #50 were recorded. Results: Dimensions were significantly smaller and more accurate with CS 9300/0.09 mm voxel size than with other protocols. The hypodense band was found mostly in the CS 9300 3D system with 0.18 mm voxel size, especially in the buccal-lingual (95%) and coronal (64%) sections. The 3D Accuitomo CBCT system showed the lowest presence of the hypodense band. Areas of both light and dark artefacts were significantly larger in the coronal third than in the apical and middle thirds. Conclusion: Artefacts in the coronal locations and in buccal-lingual sections were more evident in the CS 9300 3D system with a 0.18-mm voxel size. Keywords: artefact, CBCT, gutta-percha, measurement, zirconium

Objective: To analyse the pan-genome of three black-pigmented periodontal pathogens: Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens. Methods: Pan-genome analyses of 66, 33 and 5 publicly available whole-genome sequences of P. gingivalis, P. intermedia and P. nigrescens, respectively, were performed using Pan-genome Analysis Pipeline software (version 1.2.1; Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, PR China). Phylogenetic trees were constructed based on the entire pan-genome and single nucleotide polymorphisms within the core genome. The distribution and abundance of virulence genes in the core and dispensable genomes were also compared in the three species. Results: All three species possess an open pan-genome. The core genome of P. gingivalis, P. intermedia and P. nigrescens included 1001, 1514 and 1745 orthologous groups, respectively, which were mainly related to basic cellular functions such as metabolism. The dispensable genome of P. gingivalis, P. intermedia and P. nigrescens was composed of 2814, 2689 and 906 orthologous groups, respectively, and it was enriched in genes involved in pathogenicity or with unknown functions. Phylogenetic trees presented a clear separation of P. gingivalis, P. intermedia and P. nigrescens, verifying the reclassification of the black-pigmented species. Furthermore, the three species shared almost the same virulence factors involved in adhesion, proteolysis and evasion of host defences. Some of these virulence genes were conserved across species whereas others belonged to the dispensable genome, which might be acquired through horizontal gene transfer. Conclusion: This study highlighted the usefulness of pan-genome analysis to infer evolutionary cues for black-pigmented species, indicating their homology and phylogenomic diversity. Keywords: core genome, pan-genome, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens

Objective: To evaluate the diagnostic ability and clinical imaging features in maxillofacial soft tissue hypervascular tumours by 64-slice multidetector spiral computed tomography (64-MDCT) contrast-enhanced scanning. Methods: In a retrospective study of 21 cases of hypervascular tumours, the degree of blood supply and indexes were assessed, and the pathological results were used as the diagnostic gold standard to evaluate the sensitivity and specificity of 64-MDCT plain scan and enhanced CT in the diagnosis of oral and maxillofacial soft tissue hypervascular tumours, using the receiver operating characteristic curve to analyse and evaluate the efficacy. Results: Among 21 patients, the diagnostic accuracy of 64-MDCT contrast-enhanced scan was 90.48%, the area under the curve of venous phase CT value was 0.80, the sensitivity was 83.30% and the specificity was 72.73%. Conclusion: 64-MDCT contrast-enhanced scan can be used to evaluate the blood supply of maxillofacial soft tissue hypervascular tumours before an operation. The CT value in the venous phase of tumours has the highest diagnostic effectiveness, which can reduce the risk of blood loss during surgery for maxillofacial hypervascular tumours. In addition, it has certain guiding significance for the formulation of clinical treatment plans. Keywords: contrast-enhanced computed tomography, hypervascular tumours, oral and maxillofacial, radiology, squamous cell carcinoma

Implant-retained removable partial dentures (RPDs) are commonly used to resolve the complications associated with traditional distal extension RPDs; however, this technology does not consider the necessity and importance of parallelism between the path of RPD insertion and the long axis of the implant. This clinical report presents a novel digital preparation technique that involves the preparation of parallel guiding planes on abutment teeth and implant insertion in the distal extension area using a computer-aided design and manufacturing template. This clinical case of implant-retained RPDs illustrates the fabrication and application of the digital template. Using this technique, the path of RPD insertion is parallel to the long axis of the implant. As a result, the components of the implant-retained RPD, including the abutment teeth, implants and attachments, can demonstrate greater longevity. Keywords: abutment teeth, digital preparation technique, distal extension, guide rods, guiding plane, implant, removable partial denture