In this study, to investigate the effects of CO₂ laser irradiation distance and irradiation speed on sealability of dentinal tubules, the dentin permeability inhibition ratio was measured using a model of hypersensitive dentin. Bel Laser (BL, BP mode, 2W) and Panalas C05Σ (PA, Σ mode, 2W) were used as CO₂ laser. The irradiation distance was set to 0 mm or 2 mm. The irradiation speed was set to low-speed (1.0 mm/s) or hi-speed (2.3 mm/s) using a moving stage. The low-speed groups were BL0lo, BL2lo, PA0lo and PA2lo groups. The hi-speed groups were BL0hi, BL2hi, PA0hi and PA2hi groups. The dentin permeability inhibition ratio of the low-speed BL0lo group was significantly higher than that of the BL2lo and PA2lo groups. There was no significant difference in the dentin permeability inhibition ratio among the hi-speed BL0hi, BL2hi, PA0hi and PA2hi groups. From the above, it was found that irradiation distance and irradiation speed affect the energy density of the CO₂ laser during dentinal tubule sealing, and that irradiation mode with a high duty ratio has sufficient sealability of dentinal tubules. Shika Igaku (J Osaka Odontol Soc) 2025; Sep; 88(2): 73-81.

In recent years, social interest in young carers has increased, yet research in the dental field remains limited. Few studies have addressed the oral health of young carers or their care recipients. This study aims to clarify the actual conditions and challenges of oral care provided by young carers and to explore how dental professionals can support them to reduce their burden.

We surveyed 106 care and welfare workers in Osaka who had experience supporting young carers. Additionally, semi-structured interviews were conducted with 13 current and former young carers, and the data were qualitatively analyzed using the SCAT method.

The results revealed that some young carers, including children aged 7-9, were involved in tasks such as assisting with dental visits and oral cleaning. Interviews highlighted barriers such as lack of knowledge, absence of guidance, prioritization of other care tasks, and financial hardship.

Based on these findings, effective support may include expanding home-visit dental care, providing instructional videos, and collaborating with care workers, former dental professionals, and dental education institutions. It is also important for dental professionals to recognize young carers and connect them with appropriate support. Shika Igaku (J Osaka Odontol Soc) 2025; Sep; 88(2): 82-91.

Osteoma is a benign tumor consisting of mature bone tissue. The predilection sites include the skull and jaw bone. We report the case of a 37-year-old male diagnosed with peripheral osteoma of the mandibular angle. The osteoma enlarged by approximately three times during long-term follow-up. The patient visited a physician with the chief complaint of common cold symptoms at the beginning of August 2003. After palpation in the submandibular region, the patient was advised to visit a dentist. Since a radiograph showed radiopacity in the right mandibular angle region, he was referred to our department for further evaluation. Although the tumor was 13 x 10 x 15 mm and had a volume of 2.3 cm3 based on a CT taken in 2003, it had enlarged to 41 x 31 x 37 mm and a volume of 34.6 cm3 based on that in 2016. The osteoma was removed using an extraoral technique under general anesthesia. No relapse was noted over the following 13 months. Shika Igaku (J Osaka Odontol Soc) 2025; Sep; 88(2): 92-100.

Rina Ito, Masako Kishima, Mikiko Imai, Kumiko Kaji, Masataka Itoda. A study on the oral hygiene and oral function in patients with maxillary obturator prostheses. Shika Igaki, 2025, 88(2), p.101-102.

Kazuko Yamamoto, Kengo Iwasaki, Akiko Shimada, Masanori Hashimoto. Cytotoxic effect of ultrasmall platinum nanoparticles on RAW264 cells. Shika Igaku. 2025, 88(2), p.103-103.