Implant treatment involves decision-making processes spanning multiple domains, including imaging diagnosis, surgical planning, prosthetic design, risk assessment, and estimation of cost and treatment duration. Patients, meanwhile, seek clarification regarding treatment options, intraoperative and postoperative complication risks, cost validity, and considerations aligned with their personal circumstances and values. However, meaningful dialogue is often constrained by limited consultation time and privacy concerns. This paper proposes a design concept for a generative AI-based informed consent support system for implant treatment, explicitly assuming that the system does not replace medical diagnosis or treatment decisions. The architecture employs Retrieval-Augmented Generation (RAG), which generates responses by referring to predefined prior knowledge, and is governed by an AI agent with clearly defined roles and constraints. The design aims to integrate evidence grounding, explicit indication of uncertainty, and response suppression in situations requiring professional medical judgment, thereby prioritizing safety. Furthermore, the knowledge base is structured into three layers consisting of public evidence, abstracted clinical knowledge, and institutional or regional information, under an operational framework compliant with relevant legal requirements. This paper does not present empirical validation；rather, it organizes key design considerations and requirements for applying generative AI to informed consent support in the medical domain.

Artificial intelligence (AI) has rapidly advanced with improvements in computational power and the development of deep learning technologies. In dentistry, AI-based research has expanded markedly, particularly in diagnostic support using panoramic radiographs, cone-beam computed tomography (CBCT), and intraoral images. AI has been applied not only to the detection of dental caries and periodontal disease, but also to diagnosis support and treatment planning support.

This article reviews the basic concepts of AI and recent technological advances relevant to dental research. It then summarizes current trends in dental AI, with a particular focus on image-based diagnostic support. In addition, we introduce our recent studies, including the development of an AI model for predicting debonding of CAD/CAM composite resin crowns in prosthodontic treatment and another AI model for assisting in the selection of implant drilling protocols based on CBCT images. The article also discusses explainable AI (XAI), which is important for the clinical interpretation of AI outputs, as well as the integration of AI with robotics in dentistry.

Although AI has considerable potential to support dental diagnosis and treatment planning, several challenges remain, including explainability, external validity, reproducibility, ethics, and safety. For AI to make a meaningful contribution to dentistry, it is essential not only to improve technical performance but also to evaluate its clinical usefulness and limitations appropriately and to promote its safe and effective implementation.

Purpose: The present study investigated the effects of occlusal contact points of the superstructure on strain, deflection, and gap formation in the collar portion of implants.

Materials and Methods：Implants were fabricated from titanium subjected to severe plastic deformation, and the superstructure (18.5 mm in length, 8 mm in width, and 8 mm in height) was made of quenched steel. Strain was measured by attaching the superstructure to implants inclined at 10°, 20°, and 30° using strain gauges. A universal testing machine applied loads from 50 N to 800 N. Occlusal contact points were identified according to the mesiodistal width (12 mm) of the lower first molar: the central point (C point) of the superstructure, and points A (6 mm from C on the side opposite the tilt) and B (3 mm from C). Gap formation and width were assessed using computer tomography. Five specimens were used for each measurement. Data were analyzed by a one-way analysis of variance followed by significance testing（p＝0.05）.

Results: At point A under a load of 800 N, strains (％) were ≥0.3 at inclinations of 10° and 20°, and ≤0.1 at 30°, with significant differences （p<0.001）. At point B, strains were 0.11 (10°), 0.035 (20°) , and 0.05 (30°) , showing significant differences (p＝0.032) . At point C, strains were 0.18 (30°) , 0.14 (20°) , and 0.1(10°) , with significant differences between 20° and 10°/ 30° (p＝0.020) and between 10° and 30°（p<0.001）. Deflection at point A was greater at 10° and 20° than at 30°, with significant differences (p<0.001) , whereas no significant differences were observed at points B and C. Regarding gap width (μm）, significant differences were found between 24.0 (10°) and 12.0 (20°) at point A (p＝0.002) , while no gaps were observed at points B and C.

Conclusion: Occlusal contact points and implant inclination angles affected strain, deflection, and gap formation in the collar portion of implants.

Purpose: To evaluate the use of rigid polyurethane bone-simulating blocks with densities of 40 pcf, 30 pcf, and 20 pcf for implant site preparation training, this study compared the internal structure, mechanical strength, and cutting torque values of these blocks with those of oak, white pine, and balsa wood ─ materials that Misch used to simulate the sensation of bone drilling.

Methods: The internal structures of the various simulated bone blocks and wood samples were observed using a scanning electron microscope (SEM), and Vickers hardness and three-point bending strength were measured. Cutting torque values during implant site preparation were also measured using pilot and final drills, and statistical analysis was performed using one-way analysis of variance (ANOVA) and the Kruskal–Wallis test (α＝0.05).

Results: SEM observations revealed that the various simulated bone materials consisted of spherical voids ranging from 100 to 400 μm in size, with differences in their number and distribution. Similarly, differences were observed in the shape, proportion, and distribution of voids in the wood samples. The mean Vickers hardness (Hv) values for the various samples (40 pcf, 30 pcf, 20 pcf, oak, white pine, and balsa) were 43.7, 22.8, 15.3, 22.0, 14.5, and unmeasurable, respectively, while the mean values for three-point bending strength (MPa) were 25.7, 15.4, 6.3, 82.5, 83.2, and 25.2. The average cutting torque values (N・cm) for the pilot drill were 5.25, 2.08, 1.43, 7.22, 3.32, and 1.24, and for the final drill were 11.35, 7.28, 2.53, 27.2, 13.8, and 2.6.

Conclusion: The results of significance tests comparing Vickers hardness, three-point bending strength, and cutting torque values among various simulated bone blocks and Misch-classified woods showed that, in terms of Vickers hardness, the 20 pcf simulated bone was equivalent to white pine, while the 30 pcf and 40 pcf samples were equivalent to oak. In terms of threepoint bending strength, the 40 pcf sample was equivalent to balsa wood. Regarding cutting torque values, for both pilot and final drills, the 20 pcf block was equivalent to balsa wood, while the 40 pcf block was equivalent to white pine and oak.

Zirconia is highly chemically stable, making it difficult to achieve reliable adhesion to resin cement. In this study, a zirconia bonding system was optimized by hydrophilizing the zirconia surface using acidified hydrogen peroxide treatment (hydrochloric acid [HCl] added to 30 wt％ hydrogen peroxide [H₂O₂]) and by combining a two-bottle zirconia primer containing zirconium alkoxide with a two-bottle silane primer containing c‑methacryloyloxypropyltrimethoxysilane (γ‑MPTS).Mirror-polished zirconia specimens were immersed at 80℃ for 10-30 min, and water contact angles were measured. The contact angle decreased with increasing HCl concentration and immersion time, reaching the minimum after treatment with 30 wt％ H₂O₂＋3 N HCl for 30 min. Specimens treated under this condition were primed and bonded, and shear bond strength was compared at c-MPTS working concentrations of 0.021─0.100 mol/L. The maximum bond strength was 8.4±1.1 MPa at 0.061 mol/L, and the failure mode shifted from interfacial failure to mixed failure with resin cement remnants. The optimized zirconia bonding system showed significantly higher bond strength than a commercial 10‑methacryloyloxydecyl dihydrogen phosphate (MDP)-based bonding system (6.0-6.4 MPa；p<0.05), suggesting that the optimized system may provide greater chemical bonding performance than the conventional MDP-based approach.

Prosthetic rehabilitation following extensive maxillary defects after resection of malignant tumors remains a major clinical challenge in terms of functional recovery. This report describes a case in which favorable occlusal rehabilitation was achieved using a fixed prosthesis supported by bone anchored devices for wide edentulous areas after maxillary reconstruction with a vascularized fibula free flap.

A 58-year-old man presented with discomfort and masticatory difficulty while wearing a maxillary obturator prosthesis. Because the patient desired functional recovery with a fixed prosthesis, implant therapy using bone anchored devices for wide edentulous areas was planned. These devices were placed in the reconstructed fibula bone, and flap thinning combined with vestibuloplasty was performed during second-stage surgery. A screw-retained fixed definitive prosthesis was subsequently delivered to restore occlusion.

After delivery of the definitive prosthesis, satisfactory masticatory function and oral hygiene were maintained. During more than 7 years of follow-up, no biological or technical complications were observed in the peri-device tissues or the prosthetic superstructure.

This case suggests that fixed prosthetic rehabilitation using bone anchored devices for wide edentulous areas after maxillary reconstruction with a fibula free flap can provide stable long-term functional outcomes when appropriate bone reconstruction and soft tissue management are achieved.

Implant therapy in patients with severe periodontitis is considered to carry a high risk of postoperative complications and implant loss. We report a case of severe periodontitis in which a favorable long-term prognosis was achieved through appropriate assessment and diagnosis, periodontal intervention including tissue regeneration prior to implant therapy, and continuous maintenance.

The patient was a 40-year-old woman who visited our clinic seeking a second opinion after being advised elsewhere that 24 of her teeth required extraction. Examination revealed mobility in multiple teeth, deep periodontal pockets, and significant vertical bone resorption in addition to horizontal bone resorption. Thorough periodontal treatment was administered to save as many teeth as possible and reduce inflammation prior to implant therapy. Periodontal tissue regeneration was performed on multiple teeth during surgery, followed by orthodontic treatment and subsequent implant placement. SPT was conducted every two to three months thereafter. Although one tooth was lost due to root fracture five years into SPT, no teeth were lost due to the patient’s history of severe periodontitis, nor was there any sign of peri-implantitis. Ten years post-treatment, periodontal conditions remain improved, and good functional recovery has been maintained.

These findings suggest that in implant therapy for patients with severe periodontitis, it is essential to focus not only on clinical factors such as periodontal treatment but also on maintaining the patient’s long-term motivation for oral hygiene management. Furthermore, these results imply that implant therapy should not be viewed merely as a prosthetic replacement for missing teeth, but rather positioned as an extension of periodontal therapy.

In this report, two implants with diameters of <3.0 mm were used to rehabilitate mesiodistally narrow anterior edentulous sites, and a favorable outcome has been maintained for 4 years and 6 months.

The patient was a 25-year-old man who visited our clinic seeking implant rehabilitation of post-orthodontic spaces. Congenitally missing teeth were noted in the left and right mandibular anterior regions, and the spaces corresponding to teeth 33 and 43 had been maintained with a retainer after orthodontic treatment. Preoperative computed tomography was used to evaluate the mesiodistal space and buccolingual bone width at each site. Because a sufficient distance from the adjacent teeth could not be obtained with regular-diameter implants, implants <3.0 mm in diameter were planned for both sites. In August 2020, the implants were placed according to the standard protocol without bone augmentation. After the healing period, definitive impressions were made, and zirconia crowns were delivered.

At 4 years and 6 months after delivery of the definitive superstructures, no peri-implant inflammation or radiographic bone loss was observed around the implants placed at the sites corresponding to teeth 33 and 43. This case suggests that implants <3.0 mm in diameter may represent a treatment option for anterior edentulous sites with limited mesiodistal space.

For horizontal bone deficiency, GBR with a bone substitute and barrier membrane is applied. However, problems such as operability of the barrier membrane and infection due to wound dehiscence have been reported.

In this case series, good bone formation was achieved without a barrier membrane by covering and fixing carbonate apatite and autogenous bone with the periosteum.

During implant placement, the full-thickness flap was carefully elevated to avoid disruption, forming an envelope without tension-relieving incisions. Following the simulation, implant placement surgery was performed. After perforating the cortical bone to ensure blood supply, the buccal space was filled with bone graft material. This consisted of calcium phosphate mixed with autogenous bone harvested during implant socket preparation and moistened with saline solution. The mixture was packed buccally to cover the implant body as a bone graft material to augment bone.

CBCT images taken more than three years after completion of implant treatment showed hard tissue-like radiopaque areas, indicating an increase in horizontal hard tissue volume.

By covering the horizontally resorbed alveolar ridge with a mixture of carbonate apatite bone substitute material and autogenous bone using the periosteum, favorable bone regeneration was achieved without the use of a barrier membrane.

Objective: To report the mid- to long-term clinical outcomes of implant therapy combined with guided bone regeneration (GBR) in an anterior maxillary defect with buccal bone deficiency, in which the membrane was fixed using resorbable bone tacks.

Patient overview: A 33-year-old man presented with a missing maxillary right central incisor. Following initial periodontal therapy, an implant was placed, and GBR was performed using deproteinized bovine bone mineral and a collagen membrane, which was stabilized with resorbable bone tacks. Healing after implant placement was uneventful, with no signs of infection or wound dehiscence. At 3 years after prosthesis delivery, computed tomography suggested that the bone tacks had been resorbed. Although a slight concave appearance was observed at the former fixation sites, no radiolucency or inflammatory findings were detected, and both hard and soft peri-implant tissues remained stable.

Conclusion: Membrane fixation using resorbable bone tacks may be a useful option for GBR in the esthetic zone; however, continued long-term follow-up is necessary to fully evaluate its biological and clinical impact.

Purpose: Intraoral scanners (IOS), which enable the digital acquisition of intraoral information, have become widely adopted worldwide and constitute a core component of digital workflows. In implant dentistry, IOS are utilized not only for the fabrication of implant-supported prostheses but also for diagnostic simulation and surgical procedures. However, there is a paucity of evidence regarding the extent of IOS utilization and the challenges associated with their use in implant therapy in Japan. The present study aimed to investigate the current status of IOS utilization among dentists performing implant treatment and to examine associated issues and future perspectives.

Materials and Methods: A questionnaire survey entitled “Survey on the prevalence and utilization of intraoral scanners” was conducted among 260 dentists who are members of the Japanese Society of Oral Implantology and affiliated with the Institute of Hokkaido Plastic Dentistry.

Results: The rate of IOS utilization was 70.7％, and 90.9％ of respondents reported a satisfaction level of "generally satisfied" or higher. The proportion of respondents indicating an intention to continue using IOS was 100％. Regarding accuracy, 87.5％ of respondents considered IOS to be reliable, whereas 62.1％ expressed expectations for further improvements in accuracy. Notably, in cases involving multiple missing teeth, 66.7％ of respondents indicated that verification of accuracy is necessary.

Conclusion: The level of satisfaction with IOS was remarkably high, and its use provides significant benefits, including a reduction in the burden on both clinicians and patients. However, at present, it remains difficult to apply IOS to all clinical scenarios. Further refinement and validation are considered necessary, particularly for cases involving multiple missing teeth.