With the advances of personal computer and application, data analysis has been familiar. Clinicians can easily analyze their own data. As an editor and reviewer for the submitted manuscripts, I often faces fundamental misuse of statistical analysis. In this manuscript, basic concepts of statistics are described to prevent common errors and misuse. For the application of regression analysis, advanced description are presented.

The human race is under constant threat from infections, including emerging infectious diseases such as outbreaks of new influenza viruses and Ebola hemorrhagic fever, epidemics of AIDS, and re-emergence of tuberculosis. The outbreak of the coronavirus disease 2019（COVID-2019）caused by a novel coronavirus has forced humans to change social lifestyles drastically. Furthermore, measures against infections caused by resident bacteria in the oral cavity, such as aspiration pneumonia, as well as opportunistic/nosocomial infections are urgently required in Japan, where the population is aging. Infectious diseases are caused by bacteria or viruses that enter and proliferate within the body. Some bacteria and viruses are capable of infecting hosts persistently for the rest of their lives and manifesting as symptoms when the hosts’ immunity weakens. In addition to microorganism-host interactions, intricately meshed bacteria-virus interactions are involved. Negative chain reactions between bacteria and viruses have increasingly been shown to play an important role in the onset of periodontal diseases that were previously attributed solely to bacterial infections. It is difficult to understand the whole picture of infectious diseases through conventional studies focusing solely on the oral cavity or a single microorganism.

We believe that elucidation of diverse microorganism-microorganism and microorganism-host crosstalk in pathogenicity, i.e., “bacteria-virus-host interactions,” will open a path to a new understanding of infectious diseases and development of new therapeutic and prophylactic means.

In the super-aged society, practice of oral care as a dental approach and prevention of oral flail will be essential in the future, and the importance of dental needs is attracting attention in the field of medical and nursing care for the elderly. In cases where it is difficult to rely on mechanical cleaning with a toothbrush alone, the combination of chemical cleaning with chemical solutions would be effective. Currently, the use of mouthwashes and mouthwashes at the discretion of dentists, dental hygienists, caregivers, and nurses is practiced based on their knowledge of the antimicrobial action of the products and empirical clinical experience. In the mechanism of action of mouthwashes and rinses, we have only studied the antimicrobial effects of mouthwashes and rinses on the bacteria that cause infection, but we have also studied the reactive oxygen species（ROS）from inflammatory cells that play an important role in oral inflammation and defense against bacterial infection. It is only reported that the antioxidant effects of ROS to reduce the oxidative stress caused by ROS has been investigated indirectly. Evidence for oral health care products that protect against oral infections should include not only antimicrobial activity but also antioxidant activity that reduces oxidative stress caused by ROS. Therefore, evidence for oral health care products that implement oral care to protect against oral infections requires not only an examination of antimicrobial action, but also an examination of antioxidant action by ROS. Since we have established an antioxidant evaluation method by electron spin resonance（ESR）method for the development of drugs, food and beverage products, and supplements, we used the antioxidant evaluation of mouthwashes and mouthwashes to investigate the antioxidant evaluation. The antimicrobial activity of Listerine^® natural care（Listerine NC）and Neustelline^® Green Gargle（Neostelline）, which are widely used as mouth rinses and mouthwashes, was confirmed in this study, but the antimicrobial effect of Listerine NC and Neosterine in the concentrations used was more than sufficient and comparable to that of hydrogen peroxide（H₂O₂）, which is used as a disinfectant. In the antioxidant effects of mouthwashes and rinses, some were found to have excellent antioxidant effects, such as Listerine NC and sodium bicarbonate, but others, such as Neustelin, did not have strong antioxidant effects. In this study, Listerine NC and sodium bicarbonate were found to have a coordinated effect on the antibacterial and antioxidant effects of mouthwashes and rinses. In addition, from the viewpoint of safe antimicrobial action, further evidence of appropriate concentration of antimicrobial action in the oral environment will be needed in the future by examining the effects of excessive concentrations of mouthwashes and rinses on the oral flora. We hope to develop mouthwashes and rinses based on these evidences in the future.

Since there are many ways of mouthwash and types of mouthwash products, they are often used in oral care and nursing situations without clear evidence of their use. It is very useful to select an appropriate mouthwash and to provide safe and efficient oral care in facilities and hospitals with limited time and human resources if it is possible to use the mouthwash not only according not only to the type of bacteria causing oral diseases but also to the stage of the disease. In this study, we report a comparison of the antibacterial, bactericidal, and ROS scavenging effects of Neostelin Green 0.2 ％ mouthwash solution^® and sodium bicarbonate, which are clinically used as mouthwashes, against periodontal pathogens, caries-causing bacteria, and Candida. The direct scavenging effects of ROS, hydroxyl radicals（HO^•）and superoxide（O₂^•－）, was measured by the electron spin resonance（ESR）method. Antimicrobial activity was estimated in reference to minimum inhibitory concentration（MIC）and minimum bactericidal concentration（MBC）using five bacteria, Candida albicans（C. albicans）, Streptococcus mutans（S. mutans）, Aggregatibacter actinomycetemcomitans（A. actinomycetemcomitans）, Porphyromonas gingivalis（P. gingivalis）, and Prevotella intermedia（P. intermedia）. HO^• scavenging effects of Neostelin were significantly lower than those of sodium bicarbonate. O₂^•－ scavenging effects were significantly higher in Neostelin compared to sodium bicarbonate. For Neostelin, the antimicrobial and fungicidal effects to both species were confirmed to be sufficient within the range of concentrations indicated for pharmaceutical use. Although sodium bicarbonate showed high concentrations of MBC against S. mutans and P. gingivalis, while MIC was 2 w/v％, a concentration usually applied in clinical practice. MBC and MIC against A. actinomycetemcomitans and P. intermedia were both less than 2 w/v％；MBC against C. albicans was not effective unless the concentration of sodium bicarbonate was high（10 w/v％）. In this study, the differences in antioxidant and antibacterial effects were confirmed between Neostelin and sodium bicarbonate. Therefore, the present results could contribute to the clinical practice of oral care in the near future.

ハイドロキシアパタイトは自家骨の代替材料として，これまで多数の基礎ならびに臨床研究が報告されている．また，近年の組織再生医工学の発展に伴い，アパタイトの有する骨伝導能に骨誘導を促進する成長因子を組み合わせた骨再生誘導法がin situ tissue engineeringとして臨床応用されるようになった．

そこで今回我々は，人工骨インプラントとして初めて骨再生を補助する3次元連通多孔体ハイドロキシアパタイト（ネオボーン^®）と，骨再生促進作用も有する皮膚潰瘍治療薬のFGF-2（フィブラストスプレー^®）による，FGF-2/ネオボーン複合体を作製した．複合体の骨再生を検討するために，MC3T3-E1（マウス骨芽細胞様株）を用いて，ネオボーン＋FGF-2群，ネオボーン＋生理食塩水群，FGF-2（コントロール）群に分けてin vitroで骨再生を検討した．細胞増殖能はMTTアッセイ，骨分化能はALP活性で検討を行った．

細胞増殖はすべての群で1日目から4日目まで同様に増加し，7日目に各群間で有意差が認められた．ALP活性は，すべての群で7日目から21日目まで増加したが有意差は認めなかった．本実験からネオボーンとFGF-2の複合体は骨再生誘導に有用と考えられた．

DPP-4阻害薬は2型糖尿病の治療薬として広く使用されている．近年，薬剤による口腔粘膜潰瘍が多数報告されており，代表的な薬剤としてはニコランジルや低用量のメトトレキサート，ビスフォスフォネート製剤などが挙げられる．

今回，我々はDPP-4阻害薬のシタグリプチン服用中に生じた口腔粘膜潰瘍の症例を経験したので報告する．患者は，64歳女性で，左口蓋の潰瘍を主訴として受診．ステロイド軟膏も奏功せず，シタグリプチン中止により3週間で上皮化を認めた．DPP-4阻害薬による口腔粘膜潰瘍の報告は我々の渉猟し得た限りでは1例のみで，本症例は2例目の報告である．