Background This study investigated the causes of dental implant removal due to complications, and examined whether patients who had dental implant removal desired re-implant prosthesis treatments. Material and Methods A retrospective case–control study was conducted on patients who had their dental implants removed. We investigated whether the removed dental implant was replaced with other implant prostheses. Age, sex, diabetes, smoking, implant site distribution, reason for implant removal, and blade and root-form implants were categorized as predictive variables. The outcome variable was desire for re-implantation or use of other prosthetic methods after implant removal. A logistic regression model was created to identify patient factors that could predict the re-implantation of dental prostheses after implant removal. Results A total of 215 dental implants were removed from 143 patients. The most common reason for implant removal was peri-implantitis that was identified in 165 implants. After implant removal, re-implantation was performed in 98 implants (45.6%). Bivariate analyses showed that age, diabetes, implant type, and reason for implant removal were associated with the desire for re-implanted prostheses. The multiple regression model revealed that age, implant type, and reason for implant removal were associated with an increased desire for re-implant prostheses after implant removal. Conclusions Re-implantation of prostheses after the removal of dental implants was desired by patients who were younger, had implants placed in the root form, and had implants removed due to prosthetic-related complications. Key words: Dental implant removal, complications, implant prosthesis, retrospective study, re-implantation.

To investigate the influence of occlusal support and the presence and position of mandibular third molars on the incidence of mandibular condylar fractures. Records of 222 patients who presented with mandibular fracture at the Department of Oral and Maxillofacial Surgery, Kagawa Prefectural Central Hospital, from 2006 to 2019 were retrospectively analyzed. The following variables were investigated: age, sex, cause of fracture, the presence and state (impaction and angulation) of mandibular third molars, the site of mandibular fracture, and the presence of occlusal support for molars. Various risk factors for mandibular condylar head and subcondylar fractures were investigated. The majority of fractures were caused by a fall. The risk of mandibular subcondylar fractures was significantly higher in patients with occlusal support and mandibular third molars. The risk of mandibular condylar head fractures was significantly higher in patients without occlusal support or mandibular third molars. The position and angulation of mandibular third molars did not show significant difference between occurrences of head or subcondylar fractures. This study demonstrated that occlusal support and the presence of mandibular third molars significantly increased the risk of subcondylar fractures. One the contrary, their absence increased the risk of condylar head fractures.

Purpose: This study aimed to examine the relationship between post-operative mandibular fractures and its predictable risk factors in patients with marginal mandibular resection. Additionally, the timing of post-operative mandibular fractures was assessed. Patients and methods: Records of 37 patients with mandibular gingival carcinoma who underwent marginal mandibular resection at the Department of Oral and Maxillofacial Surgery, Kagawa Prefectural Central Hospital, from April 2011 to March 2019 were retrospectively analyzed. The following variables were investigated: age, sex, location of carcinoma, tumor size, mandibular height on the surgical and healthy sides, surgical approach, number of residual teeth, post-operative radiotherapy, chemotherapy, and the presence or absence of diabetes and osteoporosis. Various risk factors for post-operative mandibular fractures were statistically investigated. Results: Post-operative mandibular fracture was observed in 5 (13.5%) of the 37 mandibular marginal resection cases. The average residual mandibular height in patients with post-operative mandibular fracture was 8.5 mm. A significant difference in residual mandibular height (P = 0.013) was observed between patients with post-operative mandibular fracture and those with no fracture. The average time to post-operative fracture of the mandible was 305.4 days, and it was found to be correlated to the remaining height of the mandibular body. Conclusions: A decrease in mandibular height below 9 mm results in post-operative mandibular fracture. Furthermore, a correlation between the height of the mandibular bone and the period until the post-operative mandibular fracture was noted in this study. These findings contribute to the prediction and management of mandibular fractures after mandibular margin resection.