The aim of this study is to determine the method of maintenance care for support the functional condition during long period. The present paper reports on the result of osseointegrated titanium fixture in four complete denture patients. The marginal soft tissue reactions were investigated at the 1st, 3rd, 6th, 12th and 18th month after prothetic restrations by clinical examination and microbiological observations. All abutments were surrounded by clinically in healthy gingiva, however most individuals with the implant fixture had used as a complete denture for many years, without oral hygiene. For a favorable prognosis of the implant-recipients, self plaque control should be acquired for the patients shortly after prothetic restration. Before the healing phase, it is necessary to recall frequently for maintenance marginal soft tissue and prothetic restoration. After healing and remodeling phase, the interval of maintenance care was decided on each 3rd months. The interval seemed practically reasonable because the 18th month later the prognosis was satisfactory. This report presents two cases of complications during the maintenance phase of osseointegrated implants. Case I: A 72-year-old female patient presented gingival hyperplasia formation around the abutment after 19th months on abutment setting. We performed excision of the hyperplastic gingiva and apically positioned flap. Probing depth (PD) could not be determined because of gingival hyperplasia formation before operation, but there was marking reduction of probing depth after operation. The gingival bleeding index (GBI) was improved and the amount of gingival crevicular fluid (GCF) was reduced after operation. In pre-operative anaerobic culture, the proportions of Capnocytophaga species and Haemophilus actinomycetemcomitans were found. Post-operatively, Capnocytophaga sp. was not found, but H. actinomycetemcomitans was unchanged. Case II: A 47-year-old male patient presented gingivitis around the abutment after 13th months on abutment setting. We performed cleaning of the abutment surface with the flap procedure. Furthermore, a joint screw between the fixture and abutment was adapted due to loosening after operation, PD was unchanged, GBI was improved and GCF was slightly reduced. In pre-operative anaerobic culture, Bacteroides intermedius was rich. Post-operatively, B. intermedius was not found. In conclusion, we advocate that maintenance care of osseointegrated implants is the most important factor in the procedure.