The subgingival finish line in indirect restorations plays a critical role in achieving both esthetic integration and functional stability. This article reviews the clinical indications and placement techniques of subgingival finish lines, and examines the associated challenges and their potential solutions. Particular emphasis is placed on the influence of convex subgingival contours on periodontal tissues and the biological limitations of finish line placement in relation to supracrestal tissue attachment. Furthermore, the indications for deep subgingival margin placement are delineated, accompanied by specific technical recommendations. This paper aims to provide a framework for treatment planning that harmonizes esthetic excellence with the preservation of periodontal health.

This invited review aimed to understand bone quality and bone response to mechanical stimuli based on scientific information from research. Our previous research using several types of animals were selected in this review. Repetitive mechanical loads via the implant significantly changed degree of osseointegration, bone volume, bone mineral density and bone quality around the implant. The specific design controlling bone quality was identified under mechanical loaded-conditions. Bone quality is completely different from bone mineral density. The specific neck design significantly changes bone quality around the implant under mechanical loaded-conditions.

Physical stimuli (mechanical stress) are involved in the biological functions such as cell proliferation, differentiation, and morphogenesis, and have been developed as mechanobiology to elucidate their mechanisms. In the field of regenerative medicine, many researchers investigate the biological effects of mechanical stress and mechanical environments. In recent years, novel regenerative technologies have been developed to regulate the morphogenesis of bioengineered organs and to activate the maturation of regenerated tissues without the use of differentiation-inducing factors. This paper describes the effects and applications of mechanical stresses, such as external pressure and occlusal stimulation, on tooth organogenesis and maturation of periodontal tissues.

In Europe and the US, there are departments specializing in periodontal prosthetic treatment of patients with severe periodontitis, and integrate knowledge of periodontology and prosthodontics to maintain long-term oral health and recover the oral function for the patients. In contrast, periodontology and prosthodontics are divided into separate department in Japan. This journal has previously discussed fixed prosthodontic treatment for patients with periodontal disease from the standpoint of Japanese prosthodontist, classifying it into “US type” and “Scandinavian type.” From the perspective of extending healthy life expectancy and quality of life, the common goals of both periodontal and prosthodontic treatment are to protect remaining teeth and to enable patients to “eat anything delicious.’’ Ante’s law is not applicable to oral rehabilitation of patients with severe periodontitis, and periodontal prosthesis using cross-arch bridges, implant treatment and telescopic crowns are applied.

In orthodontics, achieving a final jaw position where Centric Occlusion (CO) approximates Centric Relation (CR) is often considered ideal. However, there is no conclusive evidence that fully aligning CO and CR guarantees optimal outcomes. Aligner-based orthodontic devices, unlike traditional braces, allow teeth to be repositioned without direct occlusion, enabling easier detection of premature contacts. Despite this advantage, inadequate treatment planning can lead to significant CO-CR discrepancies upon treatment completion, resulting in unstable occlusion. This article examines cases from our clinic to illustrate treatment planning methods and explores the objectives of aligner therapy, emphasizing the need to reconsider its treatment goals for better clinical outcomes.

Implant surgery is a procedure that requires the use of many instruments and implant-related materials in a small oral surgical field, and therefore various complications occur than conventional minor oral surgery. Surgical complications include those that are difficult to completely recover from, such as nerve damage or damage to the roots of adjacent teeth, and those that are recoverable, such as bleeding and emphysema. Surgical site infection (SSI) is recoverable in most cases if appropriate procedure was performed early. However, if the infection progresses to implant loss or jaw osteomyelitis, it can lead to a delay in treatment period and increased human resources and medical costs, so it is a complication that should be prevented as much as possible. In this article, we report on SSIs related to implant surgery and subsequent our management including previous literature.

Patient: The patient was a 76-year-old male whose main complaint was an ill-fitting immediate denture. He exhibited a non-vertical stop occlusion and had a systemic disease causing a tendency to bleed. Teeth that were difficult to extract were preserved with copings. The maxilla was rehabilitated with a full denture-supported overdenture, while the mandible was treated with a partial denture-supported overdenture. After fitting the dentures, the patient’s masticatory function improved, and a favorable long-term prognosis was achieved.

Discussion: Considering the patient’s systemic condition, we provided only support functions for coping with the condition and performed appropriate occlusal adjustments, which minimized the risk of denture subsidence or rotation. As a result, we were able to achieve favorable outcomes.

Conclusion: Due to a bleeding tendency caused by systemic conditions, invasive interventions were avoided. Functional recovery was achieved using an overdenture with copings that provided only support functions, resulting in a favorable clinical course.

Patient: A 65-year-old female with a chief complaint of masticatory disturbance and discomfort while talking caused by mobilization of the maxillary anterior bridge. The hopeless teeth were extracted; this was followed up with an immediate maxillary denture, an old mandibular denture, and provisional restorations. Subsequently, the final prosthetic devices were fitted.

Discussion: By establishing an appropriate occlusal plane through pre-prosthetic procedures and utilizing a highly rigid metal framework, it was possible to effectively distribute occlusal forces during function.

Conclusion: In this case, exhibiting occlusal plane disruption due to the loss of occlusal support in the molar region, hopeless teeth were extracted, resulting in the non-vertical stop occlusion. However, correcting the occlusal plane and full-maxillary prosthodontic treatment resulted in good treatment results.

Patient: A 61-year-old female patient complained of difficulty in mastication due to missing molars and poor esthetics. There was insufficient crown length due to severe attrition of the mandibular anterior teeth, and insufficient prosthetic space due to protrusion of the maxillary right molar, but occlusal vertical dimension was not reduced. Therefore, surgical preprosthetic treatment was performed, and function and esthetics were restored without occlusal elevation.

Discussion: Surgical crown lengthening was performed on the mandibular anterior teeth, to ensure sufficient crown length for esthetics and retention of the partial denture. In addition, the result of the maxilla being edentulous simplified the prosthetic design and made management easier.

Conclusion: Due to severe attrition and a non-vertical stop occlusion in the molars, restorative and prosthetic treatment was performed after appropriate prosthetic treatment to correct the occlusal plane and achieve the retention of the definitive prosthesis.