Dental Journal of Iwate Medical University

The purpose of this study was to investigate the stress/strain distributions around the mandibular premolar teeth in patients with loss of molar support. Subjects included female patients with loss of bilateral mandibular molar teeth that were restored with removable dentures (n=7, age from 51 to 69) and controls with complete dentition (n=7, age from 50 to 68). Occlusal contacts and bite forces were recorded under the maximum clenching with and without denture wearing. Finite element model of the mandibular first and second premolar teeth, periodontal ligament and bone was constructed for each patient based on radiographs and study models. The bite forces were applied on corresponding locations in the models to calculate the stress/strain of the periodontium. The forces, the maximum strain and stress of the molar loss group ranged widely among subjects, but they were all significantly higher than those of control group (p<0.05), and they were not prevented by denture wearing. Three subjects demonstrated high compressive cortical bone strain exceeding the estimated threshold of micro-damage of bone. The results suggest that the periodontium of the most posteriorly-located occluding premolars may become sensitive to bilateral loss of molar support if patients exhibit higher maximum bite forces.

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We experienced intravenous sedation management of a patient who had the tricuspid atresia (TA, 1b) and also investigated the change in intracerebral oxygen environment during intravenous sedation using a near-infrared oxygen monitor (NIRO).
A 21-year-old male (height 160cm, weight 61kg) patient, diagnosed with horizontal eruption of wisdom teeth in lower jaw left-hand side, was scheduled for extraction under intravenous sedation. He was diagnosed with tricuspid atresia just after birth. Balloon atrioseptostomy (BAS) was done at 24 days, Blalock-Taussing shunt operation at 4 years old, and Gleen operation at 2 years old. He had cyanosis and clubbed fingers, SPO_2 by pulse oximetry showed 82 to 85% oxygen saturation with room air in everyday life.
The ampicillin natrium (2g) was administered 60 minutes before the start of anesthesia intravenously. Intravenous sedation was maintained with 41/min oxygen, midazolam (2.0mg) and propofol (0.6〜1.2μg/ml) to relieve anxiety and procedural stress leading to possible changes in his hemodynamic state. His hemodynamics were almost stable. The oxygenation index (TOI) by NIRO was changed 68.8 to 76.2% within normal range and may not have been a clinical problem.
Tricuspid atresia is a disease with a poor prognosis. So we have needed a grasp of sick reserve force and careful caution for the complications in anesthetization management. Moreover, it was suggested that NIRO is effective for safe perioperative management in intravenous sedation management.

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