Dental practice has conventionally evolved with analogue technology. However, with the recent digitalization trend of society, digital technology has rapidly pervaded the field of dentistry in various ways as well. The introduction of digital dentistry, including electronic clinical charts, appointment management software, online systems for confirming qualifications, and digital X-ray systems and cone beam CT, may contribute not only to better patient services but also to the wider availability of three-dimensional diagnosis in clinical settings. Furthermore, as intra-oral scanners (IOS) and computer-aided design/computer-aided manufacturing (CAD/CAM) have become widespread, the new concept of digital workflow is readily innovating the conventional style of dental practice. Digital transformation in implant treatment has many advantages, including the following:

1. Providing stable and high-quality implant treatment

2. Reducing treatment cost and time

3. Providing comfort, safety, and reliability in implant treatment

4. Serving as an effective tool for patient communication and obtaining informed consent

5. Offering easy-to-manage data before and after treatment

It is important to understand both the advantages and disadvantages of using digital equipment in dental practice and to conduct proper training on how to correctly operate the devices.

In dental implant treatment, the application of digital technology to the treatment process has attracted increasing attention in recent years. In particular, guided surgery, which guides the implant placement based on simulations assuming prosthetic devices, can not only realize safe surgery that avoids complications, but also acquire an ideal placement position considering the prosthetic device. Guided surgery, a prosthetic-driven implant treatment that applies this digital technology, has become an essential procedure for implant treatment.

With guided surgery, there is a static guide method and a dynamic guide method. The static guide method of achieving accurate implant placement using surgical templates has been applied to various cases and has obtained good treatment results. However, since surgery is performed by attaching a surgical template to the oral cavity, it may be difficult to accurately place an implant in the extraction fossa or the posterior molars. On the other hand, the dynamic guide method using a 3D navigation system that has recently appeared enables freehand surgery in which 3D information is guided in real time, enabling accurate implant surgery even in cases where static guiding is difficult.

In this paper, we report the current status and usefulness of guided surgery, which has become an essential surgical procedure for implant treatment. Furthermore, the features and points to note of the static and dynamic guide methods are explained through clinical cases.

In the realm of oral implant treatment, the application of digital technology has advanced, particularly in the utilization of digital jaw movement measuring devices for jaw movement diagnosis. Analyzing the movement of the mandibular incisor region has facilitated the evaluation of jaw and oral function. Additionally, digital technology allows for a detailed analysis of condylar movements in the temporomandibular joint equivalent region. Particularly, the ability to analyze the condition where the working-side condyle moves posteriorly in the canine relationship known as D-type is considered beneficial.

Furthermore, the application of digital jaw movement analysis data to the fabrication of prosthetic devices has become feasible. This enables the setup of a virtual articulator, providing an occlusion during jaw movements that avoids interference with the posterior teeth. However, challenges exist in communication between digital and analog methods, with the accurate mounting of the maxilla being a crucial issue. Additionally, there is an unresolved issue regarding whether the measured data of lateral movement pertains to the condylar path or a condylar-like induced path of teeth (tooth-guided path). When measuring the tooth-guided path, jaw movement measurement as a means of transitioning from provisional restoration with a physiological occlusion to the final prosthetic device becomes necessary. Utilizing jaw movement data specific to the temporomandibular joint, excluding the tooth-guided path, for adapting to the final prosthetic device represents a distinct approach.

Purpose : This study aimed to clarify the correlation between implant insertion torque (IT value) and implant stability quotient (ISQ value) for different types of bone quality and drill protocols.

Methods : The IT value and ISQ value were measured in two experimental groups, one in which the same implant socket was formed in each simulated bone assuming various bone qualities and the other in which a different implant socket was formed in the simulated bone of the same bone quality.

Results : In the experimental group in which the same implant socket was formed in each simulated bone assuming various bone qualities, the correlation coefficient between the IT value and the ISQ value was 0.67, showing a positive correlation. In addition, the correlation coefficient when limited to IT values of 35 Ncm or less showed a strong positive correlation of 0.81, and the correlation coefficient when limited to IT values of 45 Ncm or more showed a positive correlation. Among the experimental groups in which different implant sockets were formed in the simulated bone of the same bone quality, the correlation coefficients between the IT value and ISQ value of the D2-3 and D2 groups were 0.67 and 0.03, respectively ; the former showed a positive correlation, and the latter showed no correlation. In addition, the correlation coefficient when limited to IT values of 35 Ncm or less showed a strong positive correlation of 0.71, and the correlation coefficient when limited to IT values of 45 Ncm or more showed a negative correlation.

Conclusion : Higher IT values provide higher primary stability for the same implant socket with different bone quality. However, it was suggested that the primary stability decreases in the case of an implant socket with an IT value of 45 Ncm or more, such as when bone density is high and excessive adaptation techniques are used.

The number of cases where natural teeth and dental implants coexist has been increasing. In some cases following implant treatment, it becomes necessary to extract the remaining teeth and carry out additional implant procedures. However, there are no established guidelines for assessing implants previously placed by other clinics. This case report introduces criteria for evaluating such implants and explores the long-term outcomes of subsequent implant procedures.

In 2002, a patient underwent implant treatment involving a removable denture at a different clinic. However, desiring a fixed prosthetic device, the patient visited our department. A new prosthetic solution was required, especially near the existing implants at positions #15 and #25. On the upper right side, an implant at #16 was inserted ; it was linked to the existing implant at #15 with the construction of a distal cantilever prosthesis. Similarly, on the upper left side, implants at #23 and #24 were placed and connected to the implant at #25.

We suggest the following criteria for integrating the evaluation of implants placed by other clinics into the treatment plan : 1) evaluation of the implant body, 2) condition of peri-implant tissue, 3) oral hygiene status, 4) material considerations, 5) implant placement site, 6) assessment of surgical risks, 7) evaluation of esthetic risks, and 8) patient explanation.

Despite meticulous treatment planning, the patient eventually required an additional implant (#21) post-treatment. This development led to no further complications, and long-term follow-up affirmed the efficacy of the treatment approach.

In recent years, various factors other than bacterial infection related to peri-implant bone resorption have been attracting attention, and overload is one of the important factors. However, it is very difficult to distinguish whether the cause of bone resorption around the implant is overload or infection. In this study, we report a case in which bone resorption around the implant was improved by occlusal treatment.

The patient was a 49-year-old woman with the chief complaint of gingival swelling with 37. She had mandibular protrusion with open occlusion, 37 showed root fracture and there was bone resorption around the 47 implant. Implant placement was performed for 36 at 2 months after tooth extraction, anterior guidance was provided by a temporary prosthesis, and occlusal dissipation of the molars was improved. Bone resorption of parts of 47 fitted with the final superstructure was observed, and 9 years after the operation, the patient is doing well.

In recent years, Japan has become a super-aging society, and the number of people with dementia who require nursing care is increasing. Due to the spread of dental implant treatment and long-term prognosis, the maintenance and management of dental implants in patients requiring nursing care has become a problem. We report a case of medication-related osteonecrosis of the jaw (MRONJ) caused by peri-implantitis in a patient with dementia. The patient was an 87-year-old woman. She had a history of Alzheimer's dementia, thoracolumbar compression fractures, and osteoporosis. She presented to our department with chief complaints of swelling in her right cheek and pain in her right submandibular region. She had right cheek swelling, submandibular fistula, and purulent drainage. Redness, swelling, and purulent drainage were noted in the peri-implant gingiva of her right lower jaw. CT images showed segregation and bone sclerosis around the implant body. She was diagnosed with peri-implantitis and MRONJ stage 3, and implant removal and isolation was performed under local anesthesia. Since the number of patients with dementia and osteoporosis undergoing implant treatment is expected to increase in the future, prevention of the development of peri-implantitis and MRONJ is important, as well as appropriate measures after the onset of these diseases.

A 45-year female visited our department with a chief complaint of difficulty in chewing. Her mandibular bilateral first molars had been lost, and her mandibular bilateral second molars showed class Ⅱ mobility. After gaining sufficient informed consent, 37 and 47 were temporarily splinted to the provisional restorations of the implants installed at positions 36 and 46, respectively. After elimination of tooth mobility, a single crown restoration was set on each tooth and implant, and they have been making favorable progress. We consider that care is needed when planning the temporary splinting of natural teeth to implants, as the standard for this method is not clear.

Background : Intraoral scanners (IOS) are capable of acquiring three-dimensional color images of the teeth. Therefore, the detection of areas with plaque adhesion stained by plaque-disclosing solutions using an IOS could potentially serve as a method for evaluating oral hygiene. This study aimed to assess the utility of obtaining O'Leary's plaque control record (PCR)measurements using an IOS in clinical practice.

Methods : Eight patients were included in the study. Plaque was stained with gel, and PCR values were assessed visually using the 6-point method with O'Leary's PCR. Subsequently, the teeth were scanned using an IOS, and digital images were recorded. PCR values were measured again from the IOS images displayed on a monitor. Following the PCR measurement, oral hygiene instructions were provided to the patients based on the IOS images on the monitor. After the maintenance procedure, patients were asked to complete a questionnaire regarding their discomfort level with IOS imaging and their understanding of plaque staining sites. The evaluation was conducted by comparing the PCR values measured visually and those obtained from the IOS images. The questionnaire was also used to evaluate discomfort during IOS imaging and the ability to identify plaque-stained areas on the labial and palatal sides of the anterior teeth as well as on the buccal and lingual sides of the molars.

Results : Red-stained dental plaque was visible in the IOS images, also revealing restorative steps, thin stained areas, and staining of the cervical area. The captured IOS images could be rotated and magnified to confirm the tooth surfaces on the palatal and center surfaces, which can be challenging to discern through visual inspection. Generally, the PCR values derived from the IOS images were higher than those obtained by visual examination. Furthermore, the questionnaire results indicated that the discomfort experienced during IOS imaging was comparable to that during intraoral examination. Patients displayed a good level of comprehension of the IOS imaging.

Conclusion : These results demonstrate the utility of IOS in assessing oral hygiene. Nevertheless, certain challenges persist, including the difficulty of inserting the IOS tip when acquiring images of the most posterior molars in cases with limited mouth opening and issues related to the reflection of gingival color on the surfaces of all-metallic crowns. We aim to employ the oral hygiene instruction evaluation method using IOS across a range of cases in the future to further validate its effectiveness.