We present the new classification and diagnostic criteria for peri-implant diseases, which were introduced as the consensus report in 2018, jointly produced by American Academy of Periodontology and European Federation of Periodontology. This manuscript outlines the practical application of these criteria.

The diagnosis of peri-implant mucosal inflammation is based on visible signs, such as redness, swelling, bleeding on probing (BOP), or suppuration from the peri-implant pocket. Tissue destruction is diagnosed by comparing radiographic images and probing pocket depth (PPD) at two different time points, indicating progressive bone resorption or deepening of PPD in the peri-implant bone. In the absence of such follow-up data, bone loss of 3 mm or more, or PPD of 6 mm or more, is diagnosed as tissue destruction. Healthy peri-implant tissue is characterized by the absence of inflammation and tissue destruction, while peri-implant mucositis is diagnosed in the presence of inflammation but absence of tissue destruction. Peri-implantitis is diagnosed when both inflammation and tissue destruction are present.

Compared to periodontal disease, the interpretation of BOP, suppuration from the peri-implant pocket, PPD, and pathological bone resorption differs in the diagnosis of peri-implant diseases. Furthermore, accurately detecting changes in radiographic images or PPD for peri-implant tissue can be difficult. Additionally, while periodontal disease is diagnosed at the patient level, peri-implant disease is diagnosed at the implant level. Therefore, it is suggested to record specific data for peri-implant tissue on a separate sheet from the periodontal chart and to present both periodontal disease at the patient level and peri-implant disease at the implant level in clinical practice.

Implant therapy is already a well-established method of restoring masticatory function. However, a certain percentage of patients develop complications such as peri-implant mucositis and peri-implantitis after treatment. A new classification of this disease was published in 2017, enabling the actual status of the disease to be accurately understood. It is now necessary to accurately understand the new classification, ascertain the actual status of the disease, and use this as a basis for establishing evidence regarding risk factors for disease onset, prevention methods, and treatment methods. In Japan, where the number of elderly people is increasing, it is necessary to develop standards to provide correct treatment for patients by gathering evidence, assuming that patients who cannot receive maintenance and treatment of complications at treatment facilities will also be treated in the future. To this end, we have summarized what is currently known about the classification of peri implant diseases, risk factors, and treatment methods, as well as the issues that must be resolved in the future.

A new classification of periodontal disease based on a joint American Academy of Periodontology (AAP) and European Federation of Periodontology (EFP) workshop was published in 2018. The diagnosis of peri-implantitis according to the new criteria is based on bleeding on probing (BOP), probing pocket depth (PPD), and bone resorption on a radiographic examination. It was specified that the diagnosis is based on an increase in PPD, an increase in bone resorption on X-ray, and BOP or drainage of pus compared with the results of an examination after placement of the implant superstructure. In the absence of previous examination data, the criteria were positive BOP, PPD ≥6 mm, and bone resorption ≥3 mm, with the caveat that BOP should be performed at ≤25 g or at an equally low pressure. Increased bone resorption on a radiographic examination was described as bone resorption beyond the initial bone remodeling. This remodeling is bone resorption that occurs within six months to one year after the upper portion of the implant has been exposed to the oral cavity, such as after abutment placement following secondary surgery in two-stage implants. This is a normal bone resorption image according to biologic width or supracrestal tissue attachment. By using a non-matching morse taper type abutment with a smaller diameter than the implant, the vertical epithelial descent can be reduced by changing the direction of the epithelial descent to the horizontal direction. This non-matching morse taper type is called platform switching. To avoid mistaking this normal remodeling for bone resorption due to peri-implantitis, a clear distinction was made. Factors that influence bone remodeling are the connection pattern of the implant-abutment junction and the depth of implant placement. The vertical position of the microgap between the implant and the superstructure is important.

In recent years, the safety of implant treatment seems to have improved as a result of advances in diagnostic techniques and medical safety measures. However, reports of medical accidents and medical lawsuits still persist. Unlike other dental treatments, complaints and dissatisfaction from patients associated with implant treatment are characterized by the fact that they occur during the maintenance period after a certain period of good progress has been made after the completion of implant treatment. Patients become “verbal medical consumers”, claiming satisfaction with treatment and their rights. The characteristics of medical disputes involving implants, the peculiarities of complaints from implant patients, and problems in informed consent will be explained from the practitioner's point of view.

The prevention and resolution of medical disputes depends on the cause of the dispute. In the case of medical errors, sincere apologies are required, and the cause of the error must be investigated and removed. Even in the absence of malpractice, disputes may arise due to an accident or a patient's belief. In both cases, thorough informed consent is helpful, but persuasion by a third party or legal resolution may be necessary. Because dentistry affects the appearance of the patient, especially in the case of free dental care, claims may arise due to the patient's subjective preferences. However, itis important for patients to understand in advance that dentistry is a treatment and is distinct from cosmetic dentistry. Dentists, on the other hand, should take patients' complaints seriously and deal with them appropriately without neglecting them. In a recent case, a patient died because the person was left unattended after lidocaine poisoning, and another patient was left with sequelae due to nerve palsy caused by a mandibular implant. A survey by the National Consumer Affairs Center revealed that some dentists are unaware of the need for postoperative maintenance of implants. The best way to prevent conflicts is to improve dentists' skills and knowledge.

It has been suggested that dental implant therapy is highly effective for restoring and maintaining masticatory function. However, the relationship between the effect of dental implant therapy and each of the evaluation items used to diagnose oral hypofunction, and oral health-related quality of life (QOL) has not been elucidated. In this case report, we describe the results of oral function tests and oral health impact profile scores before and after dental implant treatment for five patients with oral hypofunction.

Five patients with oral hypofunction who underwent prosthetic treatment with dental implants for missing teeth including first and second molars were included in this study. The results of oral function tests and OHIP score were compared before and after treatment.

All cases showed improvement in oral function and in oral health related QOL as a result of the treatments.

Dental implant surgery can cause fatal breathing problems due to accidental injury to surrounding tissues. In this paper, we report a case of a hematoma on the floor of the mouth that required emergency tracheal intubation due to hemorrhage of the floor of the mouth caused by dental implant surgery.

A 53-year-old female underwent vestibuloplasty procedures during second-stage implant surgery on the left mandibular molar at a dental clinic in March 2018. The wound was closed with a releasing incision on the periosteum of the lingual gingiva. After returning home on the same day, she became aware of rapid swelling in the lower part of the jaw and returned to the same clinic. During hemostatic treatment, she complained of respiratory distress. She was transported to our hospital's emergency room. At the time of initial examination, her level of consciousness was JCS (Japan Coma Scale) Ⅰ-1, and she was unable to open her mouth. The swelling was observed from the lower part of the left side of the jaw to the midline of the muscle. There was no active bleeding in the oral cavity. CT showed a 38×27 mm hypo-absorptive area with an air-containing image in the left parapharyngeal space, and the airway deviated to the right and was stenotic. The patient was admitted to the ICU on the same day, and emergency tracheal intubation was performed. SBT/ABPC 6 g, carbazochrome sodium sulfonate hydrate 50 mg, and tranexamic acid 1 g were administered daily. The patient was extubated on hospital day 6 and transferred to the general ward. She was discharged from the hospital on day 14 after good progress.

Previous studies have suggested that low serum zinc levels can contribute to the development of recurrent aphthous stomatitis. We treated a 64-year-old female patient with recurrent aphthous stomatitis that was suspected to be associated with low serum zinc levels. We administered zinc supplementation therapy and concurrently performed implant treatment to address her bilateral maxillary molar defects. We first provided zinc supplementation therapy and strategically timed the implant placement during a period when stomatitis was not actively present. We consider it desirable to perform implant placement in patients with recurrent aphthous stomatitis accompanied by low serum zinc levels after treating the root cause such as by zinc supplementation.

Since 1996, the Department of Dental Implant Clinic, Tokyo Medical and Dental University Hospital (former Dental Implant Clinic, Tokyo Medical and Dental University Dental Hospital) has been reporting on the trends in new patients every five years. The total number of new patients, gender distribution, age distribution and reasons for their visit for each five-year span were calculated and analyzed considering the social background. The following results were obtained.

The number of new patients increased markedly from 275 in 1996 to 1,643 in 2011, then showed a decreasing trend until 2021. The male-female ratio was 1 to 2 almost every year. The most common age brackets of new patients were 40s and 50s in 1996, 50s in 2001, 50s and 60s in 2006, 60s in 2011 and 50s in 2021. About 80% of the reasons for visits were requests for dental implant treatment. The number of patients who had complaints about implant treatments at other clinics increased from 1996 to 2011, in 2016 was almost the same as in 2011, then decreased in 2021.

We assumed that the number of new patients and the decrease in number of elderly patients were related to the impact of the coronavirus pandemic.