Evaluation of peri-implant hard tissues is an important issue affecting the success or failure of treatment during all stages, from treatment planning to follow-up. The main methods of hard tissue evaluation in clinical practice are radiographic diagnosis, implantation torque measurement, and resonance frequency analysis, and have already been proven to be effective methods in many basic and clinical research studies. To achieve a higher success rate in treatment, it is necessary to understand the bony changes in the peri-implant bone that cannot be evaluated using these methods. This article focuses mainly on the intra-osseous changes caused by differences among implantation techniques and by loading.

We believe that the accumulation of research data will lead to the development of a hard tissue evaluation method that enables preoperative evaluation of appropriate implantation technique, appropriate loading timing, and prediction of surrounding bone resorption in each case, in addition to ongoing evaluation criteria for avoiding anatomical risk and for implant placement at the appropriate site.

Dental implant treatment is one of the most useful treatment modalities for replacing missing teeth, and is backed by much scientific evidence. However, dental implant treatment has become more difficult and complex due to the aging of patients, administered medications, systemic diseases and higher demand for implant treatment.

Although the term “bone quality” has been clinically used, it is difficult to understand bone quality correctly and to evaluate or measure bone quality non-destructively and non-invasively.

This review introduces the concept of bone quality proposed by the National Institutes of Health in 2000. The scientific evidence regarding bone quality around dental implants with or without mechanical loaded conditions is explained based on our current and previous basic scientific research and non-clinical study. Moreover, a new clinical device to evaluate and measure bone quality non-destructively and non-invasively is introduced. It is important to properly understand bone quality around dental implants.

In recent years, CT has been introduced into dental clinical practice, and guided surgery has become more widespread, leading to an increase in medical institutions that provide safer medical care. This has contributed to a decreasing trend in the number of nerve damage cases caused by dental implants. However, if nerve damage does occur due to an implant, the patientʼs life can be drastically affected, and they may experience difficulties with daily activities or even lose their job. Therefore, accurate diagnosis is crucial, and treatment options are chosen based on that diagnosis. The selection of various drugs for nerve damage depends on the type of peripheral nerve pathology (type of damage) and the subsequent response (whether nerve repair surgery is performed or not). Additionally, in cases of partial or complete neurotmesis, traumatic neuroma often forms over time, making the use of drugs based on accurate diagnosis of these conditions important.

Those who perform implant treatment must understand the treatment flow for nerve damage, the rationale for drug selection, and their proper use. Furthermore, nerve repair surgery is an extremely specialized surgery that requires the use of surgical microscopes, and it is considered that it must be learned before the age of 40. Therefore, one should not attempt such surgery lightly. It is important to have the patient seen by a specialized oral surgeon capable of performing specialized nerve tests and nerve repair surgery as early as possible, rather than relying solely on medication or observation. If the specialized medical institution (referral) is far away, collaboration is required to proceed with diagnosis and treatment, so even primary medical institutions must understand Seddonʼs three classifications (neurapraxia, axonotmesis, neurotmesis)and drug use for neuropathic pain caused by traumatic neuroma.

Patients desiring implant treatment often have systemic complications and use drugs. In order to stabilize implants over the long term, it is essential to have appropriate knowledge not only of drugs prescribed by dentists, but also of drugs prescribed by doctors, and constant updating of knowledge is required.

As drugs prescribed by dentists, prophylactic administration of antibacterial agents should be given immediately before surgery for both tooth extraction and implant treatment；the use of amoxicillin is recommended in terms of antibacterial spectrum and bioavailability. As for analgesics, NSAIDs, which have many side effects such as renal damage, should be avoided；acetaminophen should be used.

On the other hand, as drugs prescribed by doctors, in patients using direct oral anticoagulant (DOAC), there is no effective monitoring index such as PT-INR for warfarin, but adjusting the start time of surgery to account for the half-life can reduce the risk of bleeding. Implant surgery is not contraindicated in patients with osteoporosis who are using antiresorptive agents, but it is desirable to perform it after careful consideration of the risk of medication-related osteonecrosis of the jaw (MRONJ). Implant-associated MRONJ is often triggered by peri-implantitis rather than by implantation surgery, so careful consideration is required when planning implant treatment.

Patients with rheumatoid arthritis (RA) have a risk of developing osteoporosis and often receive antiresorptive agents to prevent fragility fractures. However, these medications can lead to medication-related osteonecrosis of the jaw (MRONJ), a rare but serious complication. RA patients are at a higher risk of developing MRONJ than those with non-RA osteoporosis patients due to the administration of immunosuppressive drugs and glucocorticoids, which can increase their vulnerability to infection and slow healing. In addition to antiresorptive agents, local infections resulting from oral surgical procedures are a primary cause of MRONJ. Preventing MRONJ is critical for RA patients, and while withdrawing antiresorptive agents may not be effective, oral hygiene and thorough dental care prior to administration of antiresorptive agents are essential. Because managing MRONJ can be complex in patients with RA, cooperation between physicians and dentists is essential to minimize the incidence of MRONJ in RA patients and improve outcomes.

The present case was a partially edentulous patient whom we comprehensively treated with a wide-area jawbone support device that became covered by the health insurance system in 2012, orthodontic devices and bone augmentation. Five years and six months have passed since the superstructure was first attached. The patient was a 32-year-old female who visited our department in June 2016 seeking treatment for her masticatory disorder caused by movement of her mandibular anterior teeth. Although she had no past medical history, her family history revealed that her sister had congenital partial oligodontia. She had 18 missing teeth in the jaw and midline diastasis of the maxillary anterior teeth. Under general anesthesia, maxillary and maxillary deciduous teeth were extracted, and bone augmentation by autogenous bone grafting of maximally anterior teeth (collected from bilateral mandibular protuberance) was performed. We implanted nine fixtures (Nobel Active, Nobel Biocare, Göteborg, Sweden, Φ4.3×10 mm in 14 parts, Φ3.5×13 mm in 13 parts, Φ4.3×13 mm in 12 parts, Φ3.5×11.5 mm in 22 parts, Φ3.5×13 mm in 23 parts, Φ3.5×10 mm in 32 parts, Φ5×13 mm in 35 parts, Φ3.5×10 mm in 42 parts, and Φ5×13 mm in 45 parts, a total of 9 implants). A provisional bridge was attached in February 2017, 7 months after the operation, and the final superstructure was attached in November 2017. It has been 5 years and 6 months since the final superstructure was installed, and the patient is doing well.