Research Spotlight

Yu, F. Y., Q. Q. Wang, M. Li, Y. H. Cheng, Y. L. Cheng, Y. Zhou, X. Yang, F. Zhang, X. Ge, B. Zhao and X. Y. Ren (2020). “Dysbiosis of saliva microbiome in patients with oral lichen planus.” BMC Microbiol 20(1): 75.

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BACKGROUND: Oral microbiota is not only important for maintaining oral health but also plays a role in various oral diseases. However, studies regarding microbiome changes in oral lichen planus (OLP) are very limited. To the best of our knowledge, there has been only two studies investigating salivary microbiome changes in OLP. Therefore, the purpose of this study was to identify the characteristic microbial profile in the saliva of OLP patients, with or without erosive lesions, and compare that with recurrent aphthous ulcer (RAU), a common oral immunological disorder that also shows multiple erosive/ulcerative lesions. Whole saliva samples were collected from 20 patients with OLP (erosive E, n = 10 and non-erosive NE, n = 10), 10 patients with RAU (U) and 10 healthy controls (C). DNA was extracted from the saliva samples, and the 16S rDNA gene V4 hypervariable region was analyzed using Illumina sequencing. RESULTS: We obtained 4949 operational taxonomic units (OTUs) from the V4 region in all saliva samples. Community composition analysis showed a clear decreased relative abundance of genera Streptococcus and Sphingomonas in saliva from RAU patients when compared to the other three groups. Relative abundance of Lautropia and Gemella were higher in E group, whereas relative abundance of Haemophilus and Neisseria were higher in NE group when compared to C group. Abiotrophia and Oribacterium were higher in OLP (combining E and NE groups), while Eikenella and Aggregatibacter were lower when compared to C group. There was statistically significance in alpha-diversity between E and RAU groups(p < 0.05). Significant differences in beta-diversity were detected in bacteria between E and C; NE and C; as well as E and NE groups. The LDA effect size algorithm identified the g_Haemophilus might be the potential biomarker in NE group. CONCLUSIONS: We found that salivary microbiome in erosive OLP was significantly different from that found in RAU; and these changes may be related to the underlying disease process rather than presence of ulcerative/erosive lesions clinically. In addition, our findings in bacterial relative abundance in OLP were significantly different from the previously reported findings, which points to the need for further research in salivary microbiome of OLP.

Wu, J., H. Li, L. Han, T. Sun, Y. Tian and X. Wang (2020). “The spatiotemporal expression pattern of Syndecans in murine embryonic teeth.” Gene Expr Patterns Mar 24;36:119109. [Epub ahead of print].

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The hierarchical interactions between the dental epithelium and dental mesenchyme represent a common paradigm for organogenesis. During tooth development, various morphogens interact with extracellular components in the extracellular matrix and on the cell surfaces to transmit regulatory signaling into cells. We recently found pivotal roles of FAM20B-catalyzed proteoglycans in the control of murine tooth number at embryonic stages. However, the expression pattern of proteoglycans in embryonic teeth has not been well understood. We extracted total RNA from E14.5 murine tooth germs for semi-quantitative RT-PCR analysis of 29 proteoglycans, and identified 23 of them in the embryonic teeth. As a major subfamily of FAM20B-catalyzed proteoglycans, Syndecans are important candidates being potentially involved in the tooth development of mice. We examined the expression pattern of Syndecans in embryonic teeth using in situ hybridization (ISH) and immunohistochemistry (IHC) approaches. Syndecan-1 is mainly present in the dental mesenchyme at early embryonic stages. Subsequently, its expression expands to both dental epithelium and dental mesenchyme. Syndecan-2 is strongly expressed in the dental mesenchyme at early embryonic stages, then shifts to the stratum intermedium and inner dental epithelium at cap stages. Syndecan-3 shows a gradually increased expression that initially in the dental epithelium of both incisors and molars and then in the inner dental epithelium and stratum intermedium in molars alone. Syndecan-4 is localized in the dental epithelium in incisors and the dental follicle mesenchyme in molars at early cap stage. The spatiotemporal expression pattern of Syndecans in murine embryonic teeth suggest potential roles of these proteoglycans in murine tooth morphogenesis.

Revilla-Leon, M., L. Raney, W. Piedra-Cascon, J. Barrington, A. Zandinejad and M. Ozcan (2020). “Digital workflow for an esthetic rehabilitation using a facial and intraoral scanner and an additive manufactured silicone index: A dental technique.” J Prosthet Dent 123(4): 564-570.

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The present article describes a digital workflow for planning an esthetic treatment by using a facial and intraoral scanner, the dental and open-source software design of a facially generated diagnostic waxing, and additive manufactured (AM) clear silicone indices. A virtual design was created to fabricate a unique 3-piece AM index composed of flexible, clear silicone at the labial and lingual aspects and a rigid clear custom tray. The 3-piece AM clear indexes provided advantages compared with conventional procedures, including accurate reproduction of the digital diagnostic waxing, control of index thickness, various insertion paths of the silicone indices, flexibility of the indices, and online storage of the designs.

Park, S. H., W. Piedra-Cascon, A. Zandinejad and M. Revilla-Leon (2020). “Digitally Created 3-Piece Additive Manufactured Index for Direct Esthetic Treatment.” J Prosthodont Mar 6. [Epub ahead of print].

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Facial and intraoral scanners as well as additive manufacturing (AM) technologies can be integrated to virtually plan restorative procedures. The present article describes a digital workflow protocol for treatment planning an esthetic rehabilitation using direct composite restorations. The combination of facial digitalization and intraoral scans allowed a facially driven diagnostic waxing, while additive manufacturing technologies facilitate the translation of the digital waxing into the patient s mouth through an AM 3-piece silicone index which was designed into a buccal and a lingual clear flexible silicone indices that were fitted into a clear and rigid custom tray. This procedure facilitated the treatment planning procedures as well as assisted the direct composite restoration procedures, providing several advantages compared with conventional procedures such as precise translation of the digital diagnostic waxing into the patient s mouth, horizontal path of insertion of the silicone index, and minimized time of the clinical intervention.

Liang, Y., Z. Hu, B. Chang and X. Liu (2020). “Quantitative characterizations of the Sharpey’s fibers of rat molars.” J Periodontal Res 55(2): 307-314.

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BACKGROUND AND OBJECTIVE: The Sharpey’s fibers of periodontal ligament (PDL) anchor the PDL to alveolar bone and cementum and are essential for the function of PDL. While qualitative analyses of the Sharpey’s fibers have been widely explored, a comprehensive quantitative characterization of the Sharpey’s fibers is not available. In this work, we selected rat molars as a model and comprehensively characterized the PDL Sharpey’s fibers (diameter, density, length, embedding angle, and insertion angle). MATERIALS AND METHODS: A total of 24 rat mandibular molars, eight maxillary first molars, and their surrounding alveolar bone were harvested, fixed, rendered anorganic and observed under scanning electron microscopy (SEM). The mandibles and maxillae (n = 4) were harvested, processed, sectioned, and stained with Sirius red for histological observation. SEM images were used for quantitative analyses of diameters and densities of the Sharpey’s fibers, while Sirius red staining images were used to measure lengths and angles. The Sharpey’s fibers were comprehensively characterized in terms of positions (cervical, middle, and apical thirds), PDL fiber groups (alveolar crest, horizontal, oblique, apical, and interradicular groups), sides (cementum and bone sides), and teeth (mandibular first, second, third molars, and maxillary first molar). RESULTS: Our results showed that the characteristic parameters of the Sharpey’s fibers varied in different positions, fiber groups, sides, and teeth. Specifically, the median diameter of the Sharpey’s fibers on the bone side was significantly greater than that on the cementum side, while the median density of the Sharpey’s fibers on the bone side was significantly lower than that on the cementum side, regardless of the positions and teeth. For the same tooth, the median length of the embedded Sharpey’s fibers on the bone side was more than two times greater than that on the cementum side. Among all fiber groups, the alveolar crest group had the maximum length of the Sharpey’s fibers on the bone side and the minimal length of the Sharpey’s fibers on the cementum side. There is an approximate 5-15 degrees difference between the embedding angle and the insertion angle in each group. The oblique group had the smallest embedding angles on both the bone and cementum sides. CONCLUSION: This study provides a comprehensive and quantitative characterization of the Sharpey’s fibers using rat molars as a model. Overall, these parameters varied according to different vertical positions, fiber groups, teeth, and jawbones. The quantitative information of the Sharpey’s fibers presented in this work facilitates our understanding of PDL functions and advances the development of biomimetic materials for periodontal tissue regeneration.