We are learning many things from the new coronavirus. The cumulative actions of many people will overcome this infectious disease and the whole of society will finally change, bringing an end to the coronavirus crisis. A similar social phenomenon to this crisis occurred regarding implant treatment about ten years ago, which caused the greatest crisis for the Japanese Society of Oral Implantology. In that “implant crisis,” our Society made many accomplishments to solve the problem. We succeeded in regaining social trust by spreading standard treatment methods, improving education at undergraduate and postgraduate levels, and conveying proper information to patients and society. This experience suggests that the key aim of our Society in future is “to improve the presence of implant treatment.”

Based on the discovery of osseointegration, the JSOI has successfully developed and been committed to more sophisticated treatment methodologies and education thereon. Going forward, to gain further trust of patients, we need to acquire clinical evidence on the advantages and burden of oral implant treatment, which may lead to valid informed consent. In the near future, autologous bone transplantation may be minimized due to the availability of mesenchymal stem cells, biomaterials, and growth factors in a clinical setting. Peri-implantitis should be prevented and treated well. Problems in home care such as alveolar bone osteopenia and sclerosis as well as drug-related osteonecrosis of the jaw should be solved. It is possible that a biohybrid tooth root with periodontal tissue and tooth regeneration may be achieved. All of such innovations would support minimally invasive and maximally effective modalities in the future. It is hoped that these innovations will be produced within the JSOI.

Implant dentistry is regarded as a successful dental treatment that restores superior functions and esthetics to the previous oral condition. On the other hand, implant occlusion needs careful consideration because of fundamental differences in placement status and surrounding tissue structure between natural teeth and implants. However, there has never been an optimal solution since “Implant-Protected Occlusion” proposed by Dr. CE MISCH. This article explores the transition of ideas about implant occlusion and the consensus at present.

Implant prostheses are basically one of the elements that constitute the stomatognathic system. In that sense, there is no difference in the goal of occlusion between dentition with or without implant prostheses. However, when there are large differences of displaceability and sensory acceptability on both sides, the occlusal contact relationship should be taken into careful consideration. The procedures described in “Implant-Protected Occlusion” take care to avoid stress concentration on implants. Subsequent clinical evidence has revealed the unexpectedly excellent load-bearing ability of implants. Such evidence suggests that overprotection of implants should be avoided except in cases of bruxism. Moreover, occlusal adjustment tailored to antagonist teeth was proposed in a position paper by the Japan Prosthodontic Society. A comprehensive consideration of implant occlusion should be kept in mind.

Recent developments in digital dentistry have been remarkable. While CAD/CAM technology for manufacturing prosthetic devices based on a model has reached the stage of maturity, intraoral scanners with high versatility and excellent precision in impression-taking have been developed and attracted attention. The author has already used an intraoral scanner for nearly all cases of treatments that are not covered by insurance. This article reports on the various advantages and numerous clinical applications of intraoral scanners in implant treatments, which have achieved the following favorable results:

1.Elimination of distortion in impression material and plaster, which had been unavoidable, and mitigation of discomfort

2.Examination and application that are possible only with virtual methods that utilize software programs

3.Reduction in material cost, prevention of infection, and reduction in transport time

4.Ability to take impressions even on teeth with large mobility; useful for immediate loading after tooth extraction

5.Faithful reproduction of provisional restoration

6.Application for implant overdentures and in home care

7.Use of the “IOS denture copying method” and “IOS copy denture method”

As listed above, intraoral scanners offer various advantages and are expected to become widely popular; the era of intraoral scanners has arrived.

Purpose : This study aimed to clarify the influence of the thickness of the implant collar part on the maximum bending load, amount of deformation, and strain.

Materials and Methods : The collar-part thickness was changed to 0.7 (T07), 0.8 (T08), and 0.9 (T09) mm, and the titanium abutment was processed to the same size among the three groups. The maximum bending load, amount of deformation, and strain (loading from 100 to 800 N) were measured and the inner region was observed using CT. In each measurement, superstructures with an inclination angle of 20° and 30° and superstructure length of 10 mm were set.

Results and Discussion : The maximum bending load at an inclination of 20° increased with an increase in thickness. On the other hand, the maximum bending load at an inclination of 30° was the smallest in T07 and no difference was noted between T08 and T09. The amount of deformation was the largest in T07 at both inclination angles, whereas no difference was noted between T08 and T09. At an inclination of 20°, 0.1% or greater strain was caused by loading 500 N in the T07 preparation and by loading 600 N in T08 and T09. At an inclination of 30°, 0.1% or greater strain was caused by loading 400 N in T07 and T08 and by loading 500 N in T09. Strain by loading 800 N at an inclination of 20° was 0.3% or smaller in all three types of preparation and that at an inclination of 30° was 0.3% or greater in the preparations other than T09. No difference in strain of T09 was noted between the two inclination angles from loading 300 N. On internal observation, a gap was present at the tips of the abutment and collar part, and the upper part of the screw showed plastic deformation and entered the grinding swarf discharge hole.

Conclusion : For T07, technical complications should be considered because the maximum bending load is small and the deformation is large. As for T07 and T08, it is necessary to consider biologic complications because there is a large strain at an inclination of 30°.