Takahiko Morotomi

Background/Objectives: This study aimed to evaluate the bacterial invasion inhibitory ability of MetaSEAL Soft Paste, which is a root canal sealer that has good sealing properties in dye penetration tests, compared with conventional sealers, using a novel bacterial leakage test model. Methods: We compared MetaSEAL Soft Paste (methacrylate-based resin sealer) with Canals (zinc oxide-eugenol-based sealer), AH Plus Jet (epoxy-based resin sealer), and Dentalis NX (calcium hydroxide-based sealer). In the bacterial leakage tests, the center of the root of a bovine incisor was sliced horizontally. The area of the root canal prepared using a diamond point was filled with a sealer, and the specimen was placed on a brain heart infusion agar medium. Specimens with a filter paper disc containing Enterococcus faecalis were maintained until colonization was observed. The antibacterial properties of the sealers were evaluated using the agar diffusion test and the direct contact test. Results: AH Plus Jet tended to take the longest time to show colonies in the bacterial leakage test; however, this result was not significant compared with MetaSEAL Soft Paste. In the direct contact test, significantly fewer bacteria were detected in MetaSEAL Soft Paste and Canals than in AH Plus Jet or positive controls (p < 0.01). Conclusions: This study suggests that the novel bacterial leakage test model is effective for accurately evaluating the ability of sealers to prevent bacterial leakage, and further suggests that the sealing ability of MetaSEAL Soft Paste may not be superior to that of AH Plus Jet.

Background: Osteoporosis screening in dental practice is challenging because dual-energy X-ray absorptiometry is not easily applicable to jaw bones. Objective: This study aimed to evaluate the diagnostic performance of a logistic regression model combining intraoral bone mineral density (BMD) using DentalSCOPE with the panoramic mandibular cortical index (MCI) for osteoporosis screening. Methods: Among 104 patients included in the study, 83 who underwent both intraoral and panoramic radiography were retrospectively selected as a training cohort to develop a logistic regression model for osteoporosis prediction. The mean age was 52.4 years, and 65.1% were female. Intraoral radiographs were analyzed using DentalSCOPE^® (Media Co., Tokyo, Japan) to determine BMD in the alveolar region (al-BMD). On panoramic radiographs, experienced radiologists determined the MCI. An additional 21 patients (mean age 63.1 years; 81.0% female) were prospectively enrolled as an external validation cohort. The trained model was applied to both the training (internal) and external cohorts to evaluate its diagnostic performance, which was compared with that of intraoral or panoramic radiography, using receiver operating characteristic (ROC) analysis. Results: In the training cohort, areas under the ROC curve (AUCs) of al-BMD and MCI were 0.74 and 0.82, respectively, while the combined model showed improved performance with an AUC of 0.88. In the external validation cohort, the AUCs were 0.92 and 0.97 for al-BMD and MCI, respectively. The performance of the combined model improved with an area under the AUC of 1.00. Conclusions: DentalSCOPE-based al-BMD, particularly when combined with panoramic MCI, offers a reliable and practical approach for opportunistic osteoporosis screening in dental care.

The ideal retrograde filling material that is easy to handle, has good physicochemical properties, and is biocompatible has not yet been developed. The current study reports the development of a novel bioactive glass based powder for use as a retrograde filling material that is capable of altering the consistency and hardening rate of mixtures when mixed with existing bioactive glass based cement. Furthermore, its physicochemical properties, in vitro effects on human cementoblast-like cells, and in vivo effects on inflammatory responses were evaluated. The surface of the hardened cement showed the formation of hydroxyapatite-like precipitates and calcium and silicate ions were eluted from the cement when the pH level was stabilized at 10.5. Additionally, the cement was found to be insoluble and exhibited favorable handling properties. No adverse effects on viability, proliferation, and expression of differentiated markers were observed in the in vitro experiment, and the cement was capable of inducing calcium deposition in the cells. Moreover, the cement demonstrated a lower number of infiltrated inflammatory cells compared to the other materials used in the in vivo mouse subcutaneous implantation experiment. These findings suggest that the retrograde filling material composed of bioactive glass and the novel bioactive glass based powder exhibits favorable physicochemical properties, cytocompatibility, and biocompatibility.

This study aimed to examine the resin polymerization of a fiber post/core resin construction system and the interface between resin and root canal sealers, which are important for root canal sealing. We used the i-TFC Luminus fiber post and i-TFC Luminus LC flow (i-TFC-L), the GC fiber post and Unifil Core EM (GCF), and the FiberKor post and Build-It FR (FKP) as core construction systems, and Nishika Canal Sealer BG (CS-BG), Metaseal Soft (META), and Nishika Canal Sealer EN (CS-EN) as sealers. The light transmission of fiber posts (n = 5), the polymerization of core resin (n = 5), and the adhesion between the sealer and core resin (n = 10) were evaluated. The i-TFC Luminus fiber post light transmission was significantly higher than that of other posts. Without shielding, i-TFC-L showed a significantly greater amount of polymerized resin than the other systems. With shielding, although i-TFC-L showed a significantly greater amount of polymerized resin immediately after light irradiation, polymerized resin was significantly greater in GCF and FKP after 10 min. All systems adhered to CS-BG and META but not to CS-EN. These results indicate that resin polymerization in the cavity differs among fiber post/core resin construction systems and that the adhesion of the resin and sealer depends on the property of the sealer.

The purpose of this study is to evaluate the effect of a bioactive glass-based root canal sealer, Nishika Canal Sealer BG (CS-BG), on the incidence of postoperative pain (PP) after root canal obturation (RCO). Eleven dentists performed pulpectomy or infected root canal treatments for 555 teeth. During RCO, CS-BG was used. After RCO, the rate of PP and the factors affecting PP (pain during RCO and pain immediately after RCO) were analyzed. PP was observed in eight teeth (1.5%), and within 7 days after RCO, there were no teeth with pain. In these teeth with PP, there was a significant difference in the occurrence of pain during RCO, but not in the occurrence of pain immediately after RCO, when compared with pulpectomy and infected root canal treatment. These clinical results show that CS-BG has an excellent biocompatibility, and can suppress the distress of patients during RCO.

Endodontic treatment for a tooth with damaged dental pulp aims to both prevent and cure apical periodontitis. If the tooth is re-infected as a result of a poorly obturated root canal, periapical periodontitis may set-in due to invading bacteria. To both avoid any re-infection and improve the success rate of endodontic retreatment, a treated root canal should be three-dimensionally obturated with a biocompatible filling material. Recently, bioactive glass, one of the bioceramics, is focused on the research area of biocompatible biomaterials for endodontics. Root canal sealers derived from bioactive glass-based have been developed and applied in clinical endodontic treatments. However, at present, there is little evidence about the patient outcomes, sealing mechanism, sealing ability, and removability of the sealers. Herein, we have developed a bioactive glass-based root canal sealer and provided evidence concerning its physicochemical properties, biocompatibility, sealing ability, and removability. We also review the classification of bioceramics and characteristics of bioactive glass. Additionally, we describe the application of bioactive glass to facilitate the development of a new root canal sealer. Furthermore, this review shows the potential application of bioactive glass-based cement as a root canal filling material in the absence of semisolid core material.

近年の根管治療用器具・機材および薬剤・材料の発展は目覚ましいが、感染根管処置には可能な限り適切と思われ る処置を行っても難治化する症例が存在する。根管は側枝や根尖分岐、イスマス・フィンなど複雑な解剖学的形態を 有することが多く、根管形成用器具を用いた機械的な感染歯質除去が可能な範囲は限られる。また、化学的洗浄を併 用しても根管内の全ての細菌や汚染物質を除去することは困難である。さらに根尖孔外に形成されたバイオフィルム の存在も、難治化の原因となる。このような症例では歯根端切除術が適用される。 Endodontic microsurgeryは、マイクロスコープにより歯根切断端や周囲歯周組織を確認しながら外科的歯内治療を行うもので、同軸照明と拡大視野のもと歯根周囲の歯周組織や歯根切除断面を観察しながら処置ができる。骨窩洞 や歯根切除長を最小限に設定でき、歯根周囲の病変も確実に除去できるため迅速かつ低侵襲な処置が可能となり、従 来法に比較し高い成功率が報告されている。術前の歯科用コーンビームCTによる術前診査も併用することで、その 精度はさらに高まる。 Endodontic microsurgeryの導入により、歯根端切除術は従来の方法と比較し、高い成功率の期待できる歯内治療法の一分野として確立されつつある。本総説では歯根端切除術におけるEndodontic microsurgeryの基本的な概念と手技、使用器具・機材や薬剤・材料につき概説する。

Direct pulp capping is an important procedure for preserving pulp viability. The pulp capping agent must possess several properties, including usability, biocompatibility, and the ability to induce reparative dentin formation. In this study, a novel bioactive glass‐based cement was examined to determine whether the cement has the necessary properties to act as a direct pulp capping agent. Physicochemical properties of the bioactive glass‐based cement and in vitro effects of the cement on odontoblast‐like cells, as well as in vivo effects on the exposed dental pulp, were analyzed. The cement immersed in water stabilized at pH10, and hydroxyapatite‐like precipitation was induced on the surface of the cement in simulate body fluid. There were no cytotoxic effects on the viability, alkaline phosphatase activity, or calcium deposition ability of odontoblast‐like cells. In the in vivo rat study of an exposed dental pulp model, the cement induced a sufficient level of reparative dentin formation by odontoblast‐like cells expressing odontoblastic markers at the exposed area of the dental pulp. These results suggest that the newly developed bioactive glass‐based cement provides favorable biocompatibility with the dental pulp and may be useful as a direct pulp capping agent. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 161–168, 2019.