Koma Sanda

In the intraoral scanner (IOS) impression technique for dental implants, a scanbody (SB) is connected to the implant and scanned. Poly(ether-ether-ketone) (PEEK) is a widely used material for SBs and it is recommended for single use. However, from the perspective of the Sustainable Development Goals, it is desirable to use these products multiple times. As SBs are used in patients’ mouths, proper sterilization is necessary for multiple uses. In the present study, the effect of autoclave treatment and connection/disconnection on SB deformation was investigated. The SB was connected to the implant and stereolithography (STL) data were obtained. Then, the SB was disconnected and underwent autoclave treatment, or was connected and disconnected multiple times, or underwent a combination of both processes. The results showed that there were significant differences in the distance and angle when comparing SBs before and after the autoclave treatment, but repeated connections with or without autoclave treatment had no significant impact on the measured values. The surface texture, observed with scanning electron microscopy, showed that a groove was observed on the surface of the SB, but the groove did not show major changes after 10 connection/autoclave processes. These results indicate that autoclave sterilization has some impact on SB deformation but connection/disconnection itself may not have a huge impact on SB deformation.

Medication-related osteonecrosis of the jaw (MRONJ) is an intractable disease that is typically observed in patients with osteoporosis or tumors that have been treated with either bisphosphonate (BP) or antiangiogenic medicine. The mechanism of MRONJ pathogenesis remains unclear, and no effective definitive treatment modalities have been reported to date. Previous reports have indicated that a single injection of benidipine, an antihypertensive calcium channel blocker, in the vicinity of a tooth extraction socket promotes wound healing in healthy rats. The present study was conducted to elucidate the possibility of using benidipine to promote the healing of MRONJ-like lesions. In this study, benidipine was administered near the site of MRONJ symptom onset in a model rat, which was then sacrificed two weeks after benidipine injection, and analyzed using histological sections and CT images. The analysis showed that in the benidipine groups, necrotic bone was reduced, and soft tissue continuity was recovered. Furthermore, the distance between epithelial edges, length of necrotic bone exposed in the oral cavity, necrotic bone area, and necrotic bone ratio were significantly smaller in the benidipine group. These results suggest that a single injection of benidipine in the vicinity of MRONJ-like lesions can promote osteonecrotic extraction socket healing.

When taking the final impression for a three-unit fixed partial denture (FPD), the intaglio surface of the pontic of provisional restoration cannot be transferred accurately to that of definitive restoration. The intra- and extra-oral scanning (IEOS) technique, a method for accurately reproducing the submucosal morphology of the superstructure of an implant, has been reported using an intraoral scanner. In the present study, we evaluated the difference between the conventional impression method using impression material and the IEOS technique in reproducing the morphology of the surface of the pontic of a definitive FPD. There was a significant difference in the trueness of the intaglio surface morphology of the pontic between the conventional method and the IEOS technique; however, no significant difference in precision was observed. As a result, the intaglio surface of the pontic of the three-unit FPD could be transferred to definitive restorations more accurately with the IEOS technique than with the conventional method. These results suggest that the IEOS technique can duplicate the intaglio surface of the pontic more reproducibly to the definitive restorations compared with the conventional method.

Background: Refractory jaw osteonecrosis that occurs in osteoporotic or cancer patients treated with bisphosphonates is called medication‐related osteonecrosis of the jaw but its underlying mechanism is unclear. Statins, therapeutic agents for dyslipidemia, lower blood low‐density lipoprotein cholesterol. Fluvastatin promotes the healing of tooth extraction sockets and reduces the risk of developing medication‐related osteonecrosis of the jaw‐like lesions. We used a rat model to investigate whether injecting fluvastatin at extraction sites promoted the healing of medication‐related osteonecrosis of the jaw‐like lesions.Methods: Upper first molars of rats administered zoledronate and dexamethasone for 2 weeks were extracted. Two weeks after tooth extraction, rats with medication‐related osteonecrosis of the jaw‐like lesions (bone exposure) were included in this study. A single injection of fluvastatin was administered in the vicinity of the medication‐related osteonecrosis of the jaw‐like onset site in rats.Results: The distance between the edges of the epithelia, the length of the necrotic bone exposed toward the oral cavity, the area of the necrotic bone, and the necrotic bone ratio were significantly smaller in the fluvastatin‐administered group compared with the saline group. A single application of fluvastatin near the site of medication‐related osteonecrosis of the jaw onset showed a tendency to close the epithelium, reduce necrotic bone, and form new bone, even when symptoms had already developed.Conclusion: This study suggests that a single topical administration of fluvastatin may be a novel treatment for medication‐related osteonecrosis of the jaw.