The response rate for the survey in this study was 36.5%, which is slightly lower than the typical response rate for postal surveys . This was a fact-finding survey pertaining to implant patients requiring domiciliary dental care. Accordingly, if we assume the presence of bias due to factors such as the lack of survey completion because of no implant patients or no experience or interest in implant treatment, the actual implant status of patients requiring nursing and domiciliary dental care could be worse than that suggested by the results of this survey.
Domiciliary dental care
This survey found that approximately 62% of patients who received domiciliary dental treatment/care resided in their homes. Various types of nursing facilities are visited for providing domiciliary dental care. SNHs are permanent residential facilities for individuals who require constant care, cannot be cared for at home, and/or have relatively severe systemic conditions, such as immobility or dementia. LCHFs are temporary residential facilities for elderly individuals requiring medical care or rehabilitation that are primarily centered on rehabilitation measures to enable the individual to return home. PNHs are residential facilities that mainly provide services of daily life, including care services (bathing, toileting, feeding), household assistance (washing, cleaning), and health and medical care. Generally, patients cover all the expenses for using PNHs. DCSs are day care facilities for patients with dementia wherein lifestyle care and functional training are provided on an outpatient basis during the day.
Actual implant status of patients requiring domiciliary dental care
In this study, 2% of the total number of individuals receiving domiciliary dental care were implant patients. This proportion is slightly lower than the proportion of implant treatment in those aged 65 years and more (3.8%), according to the Survey of Dental Diseases conducted in Japan in 2016 . With regard to the distribution of implant patients according to the type of facility, we found the highest percentage in PNHs (5.3%), followed by DCSs and homes. Elderly individuals of a relatively higher socioeconomic group reside in PNHs; consequently, the proportion of implant patients in these facilities was high. The significant number of patients showing evidence of poor hygiene maintenance around the implant, resulting in peri-implantitis, as well as the presence of serious complications such as implant body fracture or implant loss indicated that the patient or caregiver did not perform oral care in an appropriate manner. We also found that a passive approach was employed for the management of biological complications. This could be attributed to the unfamiliarity of dentists involved in domiciliary dental care with implants. Aggressive interventions and invasive treatments are difficult because of limitations in the treatment environment. Thus, difficulties in providing appropriate dental treatment via domiciliary dental care result in improperly maintained superstructures and inadequately repaired prostheses. In this study, regarding the implant superstructure (crowns and bridges), a detailed analysis of the prosthetic retention options (screw, cement) and the type of facing material was not possible. However, many mechanical complications were answered, including veneering material chipping/fracture, screw loosening/fracture, loss of retention (crown detachment), and implant body fracture associated with these types of superstructures. In addition, because of economic limitations associated with aging, the patients may not be able to afford expensive dental treatments.
Furthermore, we found that oral care around the implant primarily involved the use of toothbrushes, interdental brushes, and dental floss, accompanied by cleaning strategies, such as wiping with gauze and moisturizing. This indicates that the maintenance of cleanliness around implants was prioritized, even if aggressive treatment for peri-implantitis could not be performed. However, the patient’s family or caregiver barely received instructions regarding oral hygiene maintenance, resulting in inadequate routine oral care. As many elderly individuals depend on their families or caregivers for oral care, educational activities that will enable the caregivers to provide a certain level of oral care to dependent individuals with oral implants are necessary.
Relationship between an aging society and implant treatment
In this study, 73% of dentists responded that implants were not necessary for patients requiring nursing care, with reasons including difficulty in providing oral care, need for invasive treatment, and difficulty in managing the prosthetic aspects of the implants. This opinion was generalized not only among dentists, but also among family members and caregivers of the patients. The participants of this study were randomly selected, and the respondents were not grouped according to their age or clinical experience, although there was a tendency for relatively experienced dentists to provide domiciliary dental care. Additionally, there was no disagreement regarding the problem of implants in an aging society and the importance/difficulty of domiciliary dental care depending on the clinical experience (age) of dentists. The long-term success of implants is dependent on regular checkups at dental clinics and routine oral hygiene maintenance. This is based on the premise that the patient is healthy and able to visit dental clinics in the long term. Accordingly, measures for the management of implant patients in the current super-aging society are essential. Müller and Schimmel  used the term “back-off” to advocate a shift from fixed prosthesis to a more simplified and easy-to-manage oral environment toward the end of life. This not only simplifies the provision of oral care but also prevents the build-up of biofilm and reduces the risk of aspiration pneumonia. Many respondents opined that measures such as implant-supported overdentures, implant removal, or sleeping (submerged) implants should be employed before patients reach the stage of requiring nursing and domiciliary dental care. However, if we consider the mental and financial conditions of patients, obtaining consent for changing the implant prosthesis, removing the implant, or converting the implant to a sleeping one (while the patients are still healthy) would be difficult. Furthermore, many implant patients have natural teeth as well as implant prostheses; hence, oral care for both the natural teeth and implant prostheses is required. The following factors were issues faced by domiciliary dentists/dental hygienists and caregivers: (1) little knowledge about dental implants, (2) difficulty in identifying implant-supported fixed prostheses, and (3) not familiar with special oral hygiene procedures for implants.