PURPOSE: To investigate the biomechanical effect of marginal bone resorption (MBR) on the mandibular mini implant (MI)-retained overdenture (MI-OD) on the edentulous model. MATERIALS AND METHODS: The experimental mandibular edentulous model was modified from a commercial model with 2 mm thick artificial soft tissue under denture base. Two MIs (Φ2.6 mm x 10 mm) were bilaterally placed between the lateral incisor and the canine area and attached with magnetic attachments. Three groups were set up as follows: 1) alveolar bone around the MI without MBR (normal group), 2) with MBR to 1/2 the length of the implant (resorption group), and 3) complete denture (CD) without MI (CD group). Strain around the MI, pressure near the first molar area, and displacement of denture were simultaneously measured, loading up to 50 N under bilateral/ unilateral loading. Statistical analysis was performed using independent-samples t test and one-way ANOVA (α=.05). RESULTS: The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure in CD was higher than in MI-ODs (P <.05), while there was no statistical difference between the normal and resorption group (P >.05). Similarly, the CD demonstrated a greater displacement of the denture base than did the MI-ODs during bilateral and unilateral loadings (P <.05). CONCLUSION The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure on posterior alveolar ridge and denture displacement of MI-ODs significantly decreased compared to CDs, even when MBR occurs. Bilateral balanced occlusion was recommended for MI-ODs, especially when MBR occurred.

An 84-year-old man electively underwent abdominal aortic open repair for an abdominal aortic aneurysm. During the operation, the ureter was not confirmed when manipulating the iliac arteries. Subsequently, intestinal paralysis occurred on the fifth day after surgery and a drainage tube of the intestinal tract was inserted. Liquid retention around the left iliopsoas muscle, and left renal nephropathy were recognized on performing enhanced computed tomography (CT) on postoperative day 11. An initial diagnosis of an iliopsoas abscess was considered. Simple CT imaging was performed on the 13th day after surgery without symptomatic improvement. This scan revealed that the contrast agent had remained in the cavity since the previous CT scan, which had been misdiagnosed as an abscess. Ureteral injury was now suspected. Retrograde ureterography revealed an urinoma caused by left ureter injury. We diagnosed paralytic ileus due to urinoma. For drainage of the urine, a percutaneous renal fistula was constructed. He was discharged from the hospital on the 56th postoperative day, and by six months after the operation, the urinary tract problem had disappeared. In conclusion, we report a case of delayed ureteral injury that occurred after abdominal aortic open repair surgery.