Oral Biology

Corrigendum to "Efficacy of different strategies to treat root dentin eroded by liquid or gaseous hydrochloric acid associated with brushing abrasion" [Arch. Oral Biol. Vol. 89 (2018), Pages 65–69] Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Juliana Jendiroba Faraoni, Carmen Victoria Torres Toro, Laís Lopes Machado de Matos, Regina Guenka Palma-Dibb

The pH-dependent effect of cationic and non-ionic delmopinol on planktonic and biofilm bacteria Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Torgny Sjödin Abstract Objectives The primary purpose was to evaluate the antimicrobial effects of cationic and non-ionic delmopinol on planktonic and biofilm bacteria. Methods Determination of the minimum inhibitory concentrations on planktonic and biofilm bacteria was performed below and above the pKa-value of delmopinol. Test bacteria were Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Comparisons were made with three antimicrobial agents and "quaternary" delmopinol. Synergy testing of delmopinol was determined with serial dilutions of delmopinol with the other compounds in a checkerboard fashion, and the fractional inhibitory concentration index (FIC) was calculated. Results Delmopinol showed minor differences between its MIC- and MBEC-values for all bacterial strains (MBEC/MIC-ratios of 1–2). For the other compounds the difference between their MIC- and MBEC-values were higher and varied considerably between the bacteria. The MIC- and MBEC-concentrations were lower at pH where the non-ionic form of delmopinol dominates. "Quaternary" delmopinol showed the same MIC-concentrations as delmopinol, but needed much higher concentrations to kill biofilm bacteria. Synergy testing showed FIC-indices of 0.5–1. Conclusions The biofilm penetration of non-ionic delmopinol is better than for cationic delmopinol. Likewise, the cationic test reference samples exerted limited biofilm penetration. The increased efficacy of non-ionic delmopinol is probably due to reduced binding to negative groups in the extracellular matrix of polymeric substances surrounding biofilm bacteria. It is also proposed that the non-ionised form of delmopinol deposits on the biofilm surface. Higher amounts of delmopinol than expected will therefore accumulate. Combinations of delmopinol with other compounds suggests an additive antimicrobial effect.

Tea polyphenols: The application in oral microorganism infectious diseases control Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Yuan Li, Xiaoge Jiang, Jianqi Hao, Yifei Zhang, Ruijie Huang Abstract One of the most popular drinks worldwide, tea is rich in polyphenols and is beneficial to our health because it contributes to the prevention of many diseases. In the human oral cavity, there are more than 750 different species of bacteria living together within dental plaque. Some of the bacteria are pathogens that contribute to the development of oral diseases such as dental caries, periodontitis, pulpitis, mucosal disease, or halitosis through their virulence factors and their metabolites. Until now, many studies have reported that tea polyphenols (TPs) have evident inhibitory effects on some oral pathogenic microorganisms by suppressing pivotal steps of their pathogenic processes. The aim of this review is to summarize the effectiveness and mechanisms of TPs in inhibiting microorganisms, so as to provide new ideas for the prevention and treatment of oral diseases, and to contribute to the global dental public health.

Influence of adjuvant therapy with green tea extract in the treatment of experimental periodontitis Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Juliano Milanezi de Almeida, Bianca Mayara Marques, Vivian Cristina Noronha Novaes, Fred Lucas Pinto de Oliveira, Henrique Rinaldi Matheus, Luiz Guilherme Fiorin, Edilson Ervolino Abstract Aim This study evaluated the effects of topical green tea extract solution (GTE) as adjuvant therapy to mechanical debridement for the treatment of experimental periodontitis (EP). Material and methods We used 120 male rats (Rattus norvegicus albinus – Wistar), divided into the following four groups: NEP (sham) (n = 30): no experimental periodontitis (NEP), only simulation of EP by installation and removal of a ligature; EP (n = 30): EP induction by ligature; SRP (n = 30): EP, scaling and root planing (SRP), and irrigation with physiological saline solution; SRP/GT (n = 30): EP, SRP, and irrigation with GTE. Histologic analysis and immunohistochemistry were performed for detection of interleukin (IL)1ß, tumor necrosis factor-alpha (TNF-α), IL-10, and anti-tartrate resistant acid phosphatase (TRAP) in the furcation area. The percentage of bone in the furcation (PBF) was considered the primary variable and evaluated at 14, 22, and 37 days. The data from the histological analysis and the IL- 1B, TNF- A, and IL-10 were submitted to a Kruskal-Wallis variance test and Dunn's posttest (p ≤ 0.05). The histometric data and TRAP were submitted to analysis of variance (ANOVA) and Tukey's posttest (p ≤ 0.05). Results The SRP/GT group showed lower inflammatory process, lower immunolabeling pattern of IL-1ß and TNF-α, and greater immunolabeling pattern of IL-10 compared with the EP and SRP groups at 22 days. Fewer TRAP-positive multinucleated osteoclasts were observed in all periods in the SRP/GT group (5.22 ± 0.65; 7.33 ± 0.80; 8.55 ± 1.15) compared with the SRP group (30.67 ± 8.55; 13.22 ± 0.77; 13.87 ± 0.77). Higher PBF was observed in all periods in the SRP/GT group (74.65 ± 7.14; 76.61 ± 5.36; 79.24 ± 3.75) compared with the SRP group (61.60 ± 9.48; 54.84 ± 9.06; 53.25 ± 9.66). Conclusion GTE adjuvant to SRP reduced inflammation, osteoclastic activity, and alveolar bone loss in EP.

Autophagy in periodontal disease: Evidence from a literature review Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Alejandro I. Lorenzo-Pouso, Pablo Castelo-Baz, Mario Pérez-Sayáns, Jason Lim, Yago Leira Abstract Objective To summarize evidence and data relating to the implications of autophagy in periodontal disease (PD) and to describe potential nutraceuticals or pharmaceuticals that could modulate this cell death subtype. Design Literature searches of various electronic databases (Medline via PubMed, SCOPUS, Web of Science, and EMBASE) using appropriate keywords (e.g., periodontal disease, periodontitis, alveolar bone loss, periodontal infection, tooth loss, autophagy, programmed cell death, and type 2 cell death) were performed. Then, a comprehensive literature review of the current understanding of this link was elaborated. Results Autophagy plays a pivotal role in PD, and its regulation seems to be an interesting avenue for future periodontal research, according to several in vivo and in vitro reports. Conclusion Today's research has ascertained the role of autophagy in PD, especially its role in the host's defence against periodontal disease drivers. A bulk of the research recognised several pharmaceuticals and nutraceuticals that could potentially modulate this kind of cell death and serve as useful therapies. However, further research is warranted to reach a clinical translation, which could help in the discovery of novel host modulation therapies for PD.

Characterization of titanium surface coated with epidermal growth factor and its effect on human gingival fibroblasts Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Taisa Nogueira Pansani, Fernanda Gonçalves Basso, Isabela dos Reis Souza, Josimeri Hebling, Carlos Alberto de Souza Costa Abstract Objectives Different strategies, such as modifications on the implant abutments surface have been proposed to accelerate and improve the formation of the biological seal (BS). The aim of this study was to characterize a titanium (Ti) surface impregnated with epidermal growth factor (EGF) and to assess its influence on the metabolism and adhesion of oral mucosal cells. Design Ti discs were coated with EGF (100 nM) conjugated with a fluorophore and analyzed by fluorescence microscopy. The surface roughness analysis (Ra) of the EGF-coated Ti was performed by confocal microscopy. The EGF released in the wet environment was determined at 0, 24, 48 and 72 h by fluorimetric quantification. For assessment of the biological effects of EGF-coated Ti, gingival fibroblasts were seeded (5 × 104 cells) onto the substrate coated or not with this growth factor. After 24 h, cell adhesion and viability were evaluated by ANOVA and Tukey tests, α = .05. Results Immediate release of EGF as well as its incorporation by fibroblasts within 1 h after cells were seeded was observed. EGF-coated Ti discs presented significantly enhance surface roughness. Increased cell viability was observed on the EGF-coated discs. Conclusion EGF applied to Ti discs stimulated the adhesion and metabolism of gingival fibroblasts and could be considered as an interesting alternative for improving the BS.

Acetaminophen reduces apical root resorption during orthodontic tooth movement in rats Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Masato Kaku, Taeko Yamamoto, Yuka Yashima, Jin Izumino, Haruka Kagawa, Kazutaka Ikeda, Kotaro Tanimoto Abstract Objective The present study aimed to investigate the inhibitory effect of acetaminophen on apical root resorption during orthodontic tooth movement by controlling inflammation in the periodontal ligament and apical pulp tissue. Methods Human periodontal ligament and pulp cells were subjected to 10 kPa of cyclic tensile force (CTF) in a Flexcell Strain Unit for 48 h. Then, 10 and 100 μM acetaminophen were added to the culture medium, and the expression of interleukin (IL)-1B, receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor (TNF)α, and colony stimulating factor 1 (CSF1) were evaluated. In an animal experiment, the upper first molars of 7-week-old rats were moved mesially by applying 10 g of orthodontic force. After 30 days of force application, the effects of acetaminophen on apical root resorption were examined. Results In both the periodontal ligament and pulp cells, the expression levels of IL-1B, TNFα, RANKL, and CSF1 were significantly higher in the CTF-treated group than in the control group. However, the expression levels of these factors were decreased by acetaminophen administration. High expression of IL-1B, TNFα, RANKL, and CSF1 at the root apex were also detected immunohistochemically in rats after tooth movement, but were decreased by acetaminophen administration. In addition, the number of odontoclasts and the amount of apical root resorption were significantly decreased in the acetaminophen group. Importantly, no significant difference in tooth movement was observed between the acetaminophen and control groups. Conclusions These results suggest that acetaminophen can reduce severe root resorption in the apex area without disturbing orthodontic tooth movement.

Combination of estrogen deficiency and excessive mechanical stress aggravates temporomandibular joint osteoarthritis in vivo Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Yuyun Wu, Chiho Kadota-Watanabe, Takuya Ogawa, Keiji Moriyama Abstract Objective It has been suggested that degenerative conditions of the temporomandibular joint (TMJ), such as osteoarthritis (OA) and progressive condylar resorption, are caused by multiple etiological factors, such as hormonal imbalance and excessive mechanical stress. However, it is unclear whether these factors interrelate in the degenerative process of the condyle. The aim of this study was to observe the effects of combined hormonal imbalance and excessive mechanical stress on the condyle using a mouse model. Materials and methods Ovariectomy (OVX) was performed in 8-week-old female mice. Three weeks after OVX, a build-up resin was bonded to the right maxillary molars to create imbalanced occlusion (increased occlusal vertical dimension, iOVD). Mice were divided into four groups: control, OVX, iOVD, and OVX + iOVD. Results Histomorphometric analysis showed the lowest cartilage thickness and the highest TMJ-OA score in the OVX + iOVD group. Bone structural analysis showed significantly lower subchondral bone mass in all experimental groups. Additionally, the OVX + iOVD group showed up-regulated osteoclastic activity and increased apoptosis in the condyle. Gene expression analysis showed significantly elevated expression of pre-inflammatory cytokines in the OVX + iOVD group. These data showed that the OVX + iOVD group exhibited the most severe inflammatory TMJ-OA. Upregulation of ERα and activation of the ERK pathway was observed in the OVX + iOVD group. Conclusions Additive effects of estrogen deficiency and excessive mechanical stress on the condyle exacerbate TMJ-OA. Furthermore, estrogen deficiency and excessive mechanical stress combined may exacerbate TMJ-OA though activation of the ERK pathway.

Small molecules enhance neurogenic differentiation of dental-derived adult stem cells Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Boon Chin Heng, Shan Jiang, Baicheng Yi, Ting Gong, Lee Wei Lim, Chengfei Zhang Abstract Objective Dental-derived stem cells originate from the embryonic neural crest, and exhibit high neurogenic potential. This study aimed to investigate whether a cocktail of eight small molecules (Valproic acid, CHIR99021, Repsox, Forskolin, SP600125, GO6983, Y-27632 and Dorsomorphin) can enhance the in vitro neurogenic differentiation of dental pulp stem cells (DPSCs), stem cells from apical papilla (SCAPs) and gingival mesenchymal stem cells (GMSCs), as a preliminary step towards clinical applications. Materials and Methods Neural induction was carried out with a small molecule cocktail based two-step culture protocol, over a total duration of 14 days. At the 8 and 14 day timepoints, the cells were analyzed for expression of neural markers with immunocytochemistry, qRT-PCR and Western Blot. The Fluo 4-AM calcium flux assay was also performed after a further 14 days of neural maturation. Results More pronounced morphological changes characteristic of the neural lineage (i.e. neuritogenesis) were observed in all three cell types treated with small molecules, as compared to the untreated controls. This was corroborated by the immunocytochemistry, qRT-PCR and western blot data, which showed upregulated expression of several early and mature neural markers in all three cell types treated with small molecules, versus the corresponding untreated controls. Finally, the Fluo-4 AM calcium flux assay showed consistently higher calcium transient (F/Fo) peaks for the small molecule-treated versus untreated control groups. Conclusions Small molecules can enhance the neurogenic differentiation of DPSCs, SCAPs and GMSCs, which offer much potential for therapeutic applications.

Experimental study of rhBMP-2 chitosan nano-sustained release carrier-loaded PLGA/nHA scaffolds to construct mandibular tissue-engineered bone Publication date: June 2019 Source: Archives of Oral Biology, Volume 102 Author(s): Nan Deng, Jian Sun, Yali Li, Liqiang Chen, Chen Chen, Yutong Wu, Zhihao Wang, Li Li Abstract Objectives To develop PLGA/nHA scaffold containing BMP-2 cell growth factor chitosan sustained release system as tissue engineered bone for repairing large jaw defects, test its sustained release rhBMP-2 efficiency in vitro, and evaluate its Osteogenesis in rabbit mandibular defects. Methods Tissue engineered bone scaffold complexes were prepared by complexing rhBMP-2 loaded chitosan (CS / rhBMP-2) nano sustained release carrier with PLGA / nHA scaffold carrier by 3D printing. In vitro, the porosity, pore size and degradation rate and the dose-time effect relationship of cytokine release were examined. Micro-CT, hematoxylin/eosin staining, Masson staining and immunohistochemistry were determined at week 4, week 8 and week 12 in 18 rabbits. Results In vitro, the porosity was (73.64 ± 1.82)%, and the average pore diameter was (431.31 ± 18.40) μm. The cumulative release was only 9.54 ± 0.86% within 48 h and 61.38 ± 2.39% on the 30th day. In vivo, Micro-CT examination showed that the BMD and the bone volume fraction at 4, 8, and 12 weeks were higher in the implantation group than in the control group. In the 12th week, Masson staining showed that new bone occupied 19.2% of the defect area in the control group, whereas the proportion of new bone reached 45.5% in the experimental group. Conclusions PLGA/nHA/CS/rhBMP-2 scaffold complex effectively controlled the early burst effect of rhBMP-2. The bone tissue engineering scaffold complex had good biocompatibility and induced osteogenic effects. It successfully repaired the experimental bone defect area of the rabbit mandible.