An 81-year-old man visited our hospital in 2016, complaining of difficulty in singing. He was a professional vocalist, and singing was his purpose. His medical history included hypertension since 2003 and diabetes mellitus since 2003, both of which were controlled with oral medications. His hemoglobin A1c level was 6.2% (The National Glycohemoglobin Standardization Program) at the time of initial visit. He was diagnosed with depression in 2009, Parkinson’s disease in 2011, and dementia in 2014. His Hoehn and Yahr Scale score was stage III. Bradykinesia and rigidity were also observed. He had already started treatment with L-dopa and a monoamine oxidase B inhibitor. His body mass index was 28.0 (kg/m2) at that time. He required nursing care of support level 2 according to the Long-Term Care Insurance Act in Japan [11] and received daytime care.

Intra-oral examination revealed that #24, #25, and #43 had residual root status, and root surface caries were observed at #11, #13, #15, #16, #21, #22, and #23. The intermaxillary relationship was crossbite; furthermore, tooth wear was observed in almost all teeth (Fig. 1). Panoramic radiographs showed periapical lesions in #24, #25, #43, and #44, and severe bone resorption in #26 and #27 (Fig. 2). The patient had undergone implant treatment approximately 20 years prior (#34: Brånemark MkII 3.3 × 13 mm, #36: Brånemark MkII 3.75 × 10 mm, #37: Brånemark Mk IV 5 × 7 mm, #38: Brånemark MK II 5 × 7 mm, #44: Brånemark MkII 3.75 × 13 mm, #45: Brånemark MkII 3.75 × 10 mm, #46: Brånemark MkII 3.75 × 13 mm, Nobel Biocare). Fixed implant-supported superstructures were installed in #44–#45 and #34–#36–#37 regions. However, fixture #46 fractured in 2011. Additionally, implant fixtures #46 and #38 were asleep submucosally (Fig. 2).

An intraoral photograph obtained at the patient’s first visit

A panoramic radiograph image obtained at the patient’s first visit

The patient’s oral problems included (1) tooth fractures at #24, #25, and #43; (2) chronic marginal periodontitis at #26 and #27; (3) apical periodontitis at #24, #25, and #42; and (4) root surface caries at #11, #13, #15, #16, #21, #22, and #23. Additionally, the patient’s crossbite and bruxism habits may have been related to a history of tooth fractures. Problems related to the patient’s systemic condition included dysfunction of the perioral muscles due to Parkinson’s disease and cognitive impairment due to dementia.

The following prosthetic treatment plans for the regions #24–#27 and #42–#43 were proposed to the patient: (1) application of implant-supported fixed prostheses with additional implant placement, (2) application of a conventional removable partial denture for the maxilla and an implant-supported fixed partial denture without additional implant placement (#42 cantilever), and (3) application of a conventional removable partial denture for the maxilla and IOD for the mandible after removing the implant superstructures #34–#37 and #44–#45.

A discussion was conducted with the patient and his wife, and they preferred to use a conventional removable partial denture for the maxilla and an IOD for the mandible. Informed consent has been obtained from the patient and his representative to publish the treatment process as a case report.