Strictly, “Biologic Width” is defined as added value of vertical distances of junctional epithelium and supra-crestal attached tissues. It can be assumed that junctional epithelium which is a significant area with protectively physiological barrier would be named as “Biologic Width” because healthy periodontal tissues are affected by destruction of the epithelial areas. In this review paper, the author describes the following issues closely related to biologic width, including historic background, usefulness of fixed value, prosthesis margin, newly established aesthetic dentistry invading biologic width such as BTA (Biologic Tissue Adaptation) and BOPT (Biologic Oriented Preparation Technique), orthodontic intrusion movement, significance of Caffesseʼs experiment, opinions of World Workshop 2017 on the prosthesis margin, and conclusion and clinical validity proposed by the Workshop that the term of biologic width should be changed to supra-crestal attached tissues.

The bonding of direct composite restorations can be divided into two types: those that use phosphoric acid etching and those that use self-etching techniques. When phosphoric acid etching is applied to dentin, the demineralization of the untreated dentin surface goes deep, and the bonding resin does not fully penetrate the exposed collagen fiber layer. It has been confirmed that this results in deterioration of the collagen fiber layer in the long term. Among the self-etching adhesive materials, the two-step type exhibits excellent long-term bonding durability due to sufficient penetration of the bonding resin into the demineralized layer of the dentin surface, while the onestep type often has insufficient bonding to enamel, and selective enamel etching with phosphoric acid is generally recommended. Selective enamel etching with phosphoric acid is generally recommended. In order to form a durable adhesive layer, sufficient polymerization should be done. In cavity preparation, protection of the inner layer of caries dentin leads to pulp protection. The flowable resin composite liner is very effective in inhibiting gap formation in the cavity.

We report a case in which a fractured surgical carbide bur fragment strayed into the extraction socket during surgical extraction of a wisdom tooth. A 22-year-old woman visited a dentist for surgical extraction of a horizontally impacted left mandibular wisdom tooth. During the crown division procedure, the carbide bur broke, thus panoramic X-ray imaging was performed, which revealed a single opaque object in the extraction socket, thought to be a piece of the broken bur. It was difficult to perform removal of the bur piece at the dental clinic, and thus the patient was referred to our department on the same day. Bleeding from the extraction socket was noted at the initial examination and hemostasis was performed, then an antibacterial drug was prescribed for inflammation. Two months later, the carbide bur fragment that had strayed into the impacted wisdom tooth socket was removed under general anesthesia.

The position of the central incisal edge of a maxillary complete denture is affected by the height of the bite rim. When the height of the bite rim differs greatly from the intraoral condition upon taking a bite, it takes time to adjust or/and reline the denture. For the purpose of updating a standard height of the bite rim based on the average height, the front view of new upper and lower complete dentures was extraorally photographed, and the position of the incisal edge of the maxillary central incisor was measured on the photographs. For the investigation, the distance from the mucolabial fold near the maxillary labial frenum to the mucolabial fold near the mandibular labial frenum (A) and the distance from the mucolabial fold near the maxillary labial frenum to the incisal edge of the maxillary central incisor (B) of 186 new dentures were measured, and the A:B ratio was calculated. The average ratio of A:B in edentulous patients is reported to be 1:0.57, but in this study, the ratio was 1:0.64. This result suggests that the incisal edge of maxillary central incisors in complete dentures is located lower than that of natural teeth. This result can be used as a reference when fabricating a maxillary bite rim.

The national government has introduced a project called “Promotion of prevention of undernutrition and oral cavity, medication and lifestyle-related diseases in the elderly”, but some people including bedridden people who require nursing care at home cannot receive health checkups and relevant face-to face guidance as a hospital or clinic visit already poses a challenge. As such, the Gifu Dental Association was commissioned to conduct a home-visit dental checkup project for people cared at home from 2008 to 2008. This report describes the findings of the checkup. For three years from 2016 to 2018, dentists and dental hygienists provided home dental checkups and oral health guidance to 56 elderly persons requiring nursing care (nursing care level 3-5) who were at home in Gifu City and who had applied for and were not receiving dental treatment or in-home care management guidance. The data of the health examination results were anonymized. Statistical analysis was performed to determine the association between the level of care required, the number of teeth present, the occlusal relationship of molars, and the evaluation of oral function (palpation of masticatory muscles, tongue placement, coughing, gargling, and RSST) by Spearman's rank correlation coefficient. The statistical significance level was set at 0.05. Statistical analysis of the data from this examination revealed a correlation between the occlusal relationship of the molars, coughing, and RSST. This result suggests that there may be a relationship between changes in occlusal relationship and pharyngeal muscle groups. In addition, there was a correlation between the tongue and palpation of masticatory muscles, coughing, gargling, and RSST. Therefore, it is suggested that the examination of the tongue may be one of the indicators to infer the functional decline of the muscle groups related to the oral cavity, such as the masticatory muscle, the orbicularis oris muscle, and the pharyngeal muscle group.

Purpose: Persistence of root canal treatment depends mainly on reliable mechanical preparation of the root canal. The improved method is evaluated together with the stainlesssteel file and the Ni-Ti rotary file. Material & Method: A single root canal tooth with a relatively straight root canal is used as an experimental tooth, and the inside of the root canal is stained with a staining solution, and then performed were ① root canal enlargement by hand stainlesssteel file (MANI), ② Root canal enlargement by Ni-Ti rotary file (VDW) of X Smart plus engine (Dentsply) specification, and the improved method ③ Root canal enlargement using both ① and ② after bucco-lingually expanding the coronal 1/2 to 1/3 of the root canal. The magnified evaluation was performed by simple X-ray photography, and the wall surface of the root canal after division was evaluated by direct observation. Results: Improvement of root canal cleaning condition was observed in the improved method. It was suggested that the enlargement time could be shortened and the enlargement along the anatomical root canal could be achieved by utilizing the characteristics of the instruments.

The timing of visits to the dentist by children with a chief complaint of malocclusion depends on the awareness of the guardians. To find out the timing of the first time visit and the treatment outcomes, the clinical data on 485 children aged 1 to 11 years who visited our clinic was investigated. The outcomes were classified into 3: (1) Growth observation until the optimal time to start treatment (growth observation group), (2) immediate start of treatment (treatment group), and (3) no wish for management (including second opinion, no wish group). The patients in Group (1) and Group (2) were further classified according to occlusal classification. The most common age at initial visits was 8 years, followed by 9 years. The treatment outcomes were as follows: (1) 134 patients (27.6%) in the growth observation group, (2) 107 patients (22.1%) in the treatment group, and (3) 244 patients (50.3%) in the no wish group. The most common malocclusions in the growth monitoring group were maxillary protrusion and crowding, while those in the treatment group had cross bites, followed by eruption disorder and open bite. In the treatment group, the most common malocclusions were maxillary protrusion and crowding. However, this period, when parents are interested, can be considered as an important time to convey the ideal future oral function.

Since 2015, we have been holding a vocational experience project, "Let's know the work of the hospital" for high school students who are thinking about co-medical employment in the future. This project introduces the work of medical technicians at our hospital to high school students, who wish to enter medical technology-related occupations, and to foster future medical technicians. With the number of students passing the national examination for dental technicians on the decline, how are dental technicians perceived by high school students who wish to pursue a career in medical technology? The analysis was based on a preliminary questionnaire survey of 162 participants from 18 high schools in the vicinity conducted upon the 2019 event as well as the result of a questionnaire survey on dental technicians for high school students who wanted to enter other professions. The results showed that dental technician was the most unpopular occupation. The dental care community needs to know the status of aspirations for dental technicians within medical technology related occupations.

The basic principle of periodontal treatment in dental hygiene is the removal of plaque, which is the etiological factor. Oral hygiene instruction, scaling and root planing performed by dental hygienists are recognized as the most important interventions not only for periodontal diseases, but also for prevention. The oral hygiene instructions are based not only on the patient's gender and age which can be obtained through history taking, but also the patient's lifestyle, habits, and personality as well as other information that can be acquired through further communication. Based on this information, it is important to provide guidance that is tailored to the patient's life stage. In this case, the patient was able to achieve good self-care through tailormade guidance.

It has been pointed out that crowns fabricated by the indirect method tend to be too high compared to the adjacent teeth at try-ins. According to Ohyama and Yuki, this excessive height at try-ins is caused by the physiological tooth mobility caused by occlusal contact with the crown made on a working model obtained in a resting state without occlusal contact. They recommend a method for manufacturing a prosthesis, which requires a little occlusal adjustment. With reference to this, we examined a working model adjustment method for cases with a few defects. After taking an impression, the occlusion is obtained using a silicone bite registration material; the omission of this silicone bite is carefully marked on the model; the bite material is divided and fitted; and the working model is adjusted with consideration for physiological tooth mobility and is mounted on an articulator with a bite material inbetween upper and lower models to obtain a tight fit—for crown fabrication. We tried to adjust such a working model. As a result, the amount of adjustment at the time of try-ins was significantly reduced, so it was suggested that the work model adjustment method for marking the omission of the bite material is effective.