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The adhesion of zirconia and soft tissue is very important for the success of zirconia implants. The aim of this study was to characterize the effects of excimer laser treatment of zirconia on the adhesion of L929 fibroblasts. In this study, polished zirconia disks treated with an excimer laser were the experimental group and untreated zirconia disks were the control group. Surface roughness and contact angles of zirconia disks were measured. mRNA expression levels of integrin β1 and collagen type I α1 in L929 fibroblasts cultured on zirconia disks were measured using qRT-PCR. Cell morphology was evaluated using 3D laser microscopy and the expression of vinculin was characterized using confocal microscopy. There was no significant difference in the surface roughness of zirconia disks, but contact angles were significantly lower. mRNA expression of integrin β1 was significantly higher at 3, 6 and 24 h and of collagen type I α1 was significantly higher at 6 and 24 h. L929 fibroblasts tended to form elongated microspikes and vinculin colocalization in those microspikes. Furthermore, vinculin was strongly expressed in filopodia of L929 fibroblasts at 24 h. These results suggest that excimer laser treatment improves adhesion between zirconia disks and L929 fibroblasts.

Here, we describe the provision of an implant-supported prosthesis in a patient with impacted teeth in the maxilla, which complicated implant placement and necessitated utilization of the extraction sockets of previously impacted teeth and residual submerged roots. The patient was a 63-year-old man who visited our clinic with the chief complaint of difficulty in mastication. Numerous residual roots were observed in the maxilla, and radiographic imaging revealed that the residual roots of teeth #13 and #16 were fully impacted. The patient complained of a strong sensation of a foreign body in the area of a denture support overlying these residual roots. Therefore, the impacted teeth were extracted, 5 implants placed, and a temporary prosthesis provided. Given the necessity of placing the implant through the extraction socket of the impacted canine (#13), favorable initial stability was achieved using a long (>20 mm) implant. Moreover, autogenous bone obtained by osteotomy was grafted onto the extracted impacted tooth socket. The clinical condition was stable at approximately 1 year after implant placement and so the final prosthesis was delivered, with periodic check-ups being performed every 3 months thereafter. After 4 years, the patient has reported no symptoms. Clinically, there are no signs of inflammation, and the postoperative condition is deemed to be very favorable.

Although the risk of injuring the lingual nerve in the mandibular molar area during dental treatment is high, it can be repaired by nerve grafting. However, from the perspective of clinical dentistry, the pathway and histomorphometric characteristics of this nerve remain to be documented in detail. The purpose of the present study was to morphologically elucidate the pathway of the lingual nerve to clarify its significance in a clinical setting. A histomorphometric analysis was also performed in consideration of nerve grafting. The vertical distance between the occlusal plane and the superior margin of the lingual nerve showed a gradual decrease from the premolar toward the distal molar area. This suggests that the risk of injuring the lingual nerve increases gradually toward the distal area. The average total fascicular area of the lingual nerve was 1.90 mm2, which was larger than that of the sural nerve. It is the first-choice donor nerve for grafting. Therefore, even though the total fascicular area of the donor nerve is a little smaller than that of the recipient nerve, nerve grafting should be successful.

To provide safe dental care, it is important to minimize the pain associated with the initial injection of the local anesthetic. For this purpose, a topical anesthetic is preliminarily applied to the area where a needle will be inserted in a clinical setting. In this study, we prepared new topical anesthetic formulations with favorable intra-oral retentivity and an excellent anesthetic effect, and clinically evaluated their efficacy. We used 4% lidocaine solution as an anesthetic drug and gelatin, agar, and a food thickener as a base to prepare new topical anesthetic formulations. The subjects rested in a supine position on a chair for dental practice prior to the following experiments. Firstly, about 0.2 g of the sample was applied at a test site. One minute later, the sample was removed, and a 30 G dental injection needle was inserted into the test site. The agar/gelatin-based formulation containing gelatin of 2% and agar of 1% had a moderate solidity at 25°C and a moderate fluidity at 37°C. This formulation showed a significantly greater depth than any of the commercially available topical anesthetics. The results of the present study demonstrated that the agar/gelatin-based formulation showed an excellent analgesic effect against pain associated with needle insertion.

Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.

Statement of problem Although 1-piece implants are associated with positive clinical outcomes, including improved implant stability, overall survival rate, and marginal bone levels, a few studies have suggested that 1-piece implants have low success rates. Purpose This prospective multicenter study evaluated the efficacy of 1-piece implants placed in immediate function in private clinic-based and hospital-based settings with a focus on marginal bone level changes and esthetic outcomes over a 3-year follow-up period. Material and methods A total of 93 one-piece implants (29 maxillary, 64 mandibular) were placed in 63 participants (25 men and 38 women) at 1 university hospital and 3 private clinics. The implants were restored with interim crowns immediately after placement. Clinical and radiographic evaluations of marginal bone level, implant stability, periimplant mucosa, and plaque and papilla indices were performed at the time of implantation and after 6, 12, 24, and 36 months. Results The 3-year cumulative implant survival rate was 100%. After implant placement, mean bone levels changed from -0.16 ±1.41 mm at 24 months to 0.40 ±1.46 mm at 36 months. Clinical parameters, including implant stability, periimplant mucosa, and plaque index, remained stable from 3 to 36 months during follow-up. The papilla index score increased over time. Conclusions Within the limitations of this prospective study, marginal bone level was maintained, soft tissue integration was achieved, and a cumulative survival rate of 100% was obtained for 1-piece implants. The present findings indicate that 1-piece implants are an effective treatment option for immediate function situations.