[Quality Control of Medical Instruments and Cleaning Water].

PURPOSE: Herein we aimed to investigate the degradation of surgical instruments in our hospital and how water quality affects the rate of metal corrosion. MATERIALS AND METHODS: We observed 279 stainless steel instruments, and determined the presence of damage like metal corrosion or scale formation. We also measured the concentrations of chloride(Cl-)and silicate(SiO44-)ions in the water used for cleaning in our operating rooms, including tap water from the city water supply and reverse-osmosis(RO)filtered water. RESULT: Pitting corrosion was observed on 71% of the instruments we investigated. The concentration of Cl- was 0.7mg/L in tap water and 0.1mg/L in RO water, while the concentration of SiO44- was 0.3mg/L in both the tap and RO water. DISCUSSION: Of the dissolved ions Cl- and SiO44-, Cl- is more of a concern, as it causes pitting corrosion over time, while SiO44- causes scale formation. Considering the typical water quality in the operating-room environment, degradation must be monitored for the general maintenance of metal surgical instruments.

Periodontal tissue regeneration by recombinant human collagen peptide granules applied with ß-tricalcium phosphate fine particles.

OBJECTIVES: Recombinant human collagen peptide (RCP) is a recombinantly created xeno-free biomaterial enriched in arginine-glycine-aspartic acid sequences with good processability whose use for regenerative medicine applications is under investigation. The biocompatibility and osteogenic ability of RCP granules combined with ß-tricalcium phosphate (TCP) submicron particles (ß-TCP/RCP) were recently demonstrated. In the present study, ß-TCP/RCP was implanted into experimental periodontal tissue defects created in beagles to investigate its regenerative effects. METHODS: An RCP solution was lyophilized, granulated, and thermally cross-linked into particles approximately 1 mm in diameter. ß-TCP dispersion (1 wt%; 500 µL) was added to 100 mg of RCP granules to form ß-TCP/RCP. A three-walled intrabony defect (5 mm × 3 mm × 4 mm) was created on the mesial side of the mandibular first molar and filled with ß-TCP/RCP. RESULTS: A micro-computed tomography image analysis performed at 8 weeks postoperative showed a significantly greater amount of new bone after ß-TCP/RCP grafting (2.2-fold, P < 0.05) than after no grafting. Histological findings showed that the transplanted ß-TCP/RCP induced active bone-like tissue formation including tartaric acid-resistant acid phosphatase- and OCN-positive cells as well as bioabsorbability. Ankylosis did not occur, and periostin-positive periodontal ligament-like tissue formation was observed. Histological measurements performed at 8 weeks postoperative revealed that ß-TCP/RCP implantation formed 1.7-fold more bone-like tissue and 2.1-fold more periodontal ligament-like tissue than the control condition and significantly suppressed gingival recession and epithelial downgrowth (P < 0.05). CONCLUSIONS: ß-TCP/RCP implantation promoted bone-like and periodontal ligament-like tissue formation, suggesting its efficacy as a periodontal tissue regenerative material.

Ultrasonic irrigation of periodontal pocket with surface pre-reacted glass-ionomer (S-PRG) nanofiller dispersion improves periodontal parameters in beagle dogs.

OBJECTIVES: Surface pre-reacted glass-ionomer (S-PRG) nanofiller, an antibacterial ion-releasing bioactive glass, has been shown to adhere to tooth surfaces and reported to improve inflammatory parameters in experimental periodontitis. In this study, cementum substrate was irrigated ultrasonically with dispersion to examine in-vitro nanofiller adhesion and antibacterial activity. Moreover, periodontal pockets in a beagle dog were ultrasonically irrigated with dispersion to assess periodontal healing. METHODS: The morphology of human cementum irrigated with S-PRG nanofiller dispersion was examined by scanning electron microscopy and energy dispersive X-ray spectrometry. The antibacterial activity of the treated cementum was tested using Actinomyces naeslundii. In addition, experimentally formed periodontal pockets in beagle dog were ultrasonically irrigated with S-PRG nanofiller dispersion. Periodontal parameters (gingival index, bleeding on probing, probing pocket depth, and clinical attachment level) were measured from baseline (0 weeks) through 12 weeks. Moreover, the effects of irrigation with S-PRG nanofiller on changes in periodontal microflora and bone healing were analyzed. RESULTS: After ultrasonic irrigation, S-PRG nanofiller adhered to the cementum and exhibited antibacterial activity. The periodontal parameters were shown to improve following ultrasonic irrigation with S-PRG nanofiller dispersion. Analysis by next-generation sequencing revealed that the ratio of red-complex species decreased in the pockets irrigated with S-PRG nanofiller dispersion. In addition, the S-PRG nanofiller showed the potential to promote bone healing. CONCLUSIONS: Ultrasonic irrigation with S-PRG nanofiller dispersion using an ultrasonic scaler system permitted delivery of the S-PRG nanofiller to the root surface, providing improved parameters in experimental periodontitis and modifying the composition of subgingival periodontal microflora.

Sustained antibacterial coating with graphene oxide ultrathin film combined with cationic surface-active agents in a wet environment.

Antimicrobial surfactants contained in mouthrinse have excellent efficacy, but are not retained on the tooth surface (are rinsed away) due to their low water resistance and thus do not exhibit sustained antibacterial activity. We have developed a new coating method using graphene oxide (GO) that retains the surfactant on the tooth surface even after rinsing with water, thus providing a sustained antibacterial effect. Ultra-thin films of GO and an antimicrobial agent were prepared by (1) applying GO to the substrate surface, drying, and thoroughly rinsing with water to remove excess GO to form an ultrathin film (almost a monolayer, transparent) on the substrate surface, then (2) applying antimicrobial cationic surface active agents (CSAAs) on the GO film to form a composite coating film (GO/CSAA). GO/CSAA formation was verified by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ζ-potential and contact angle measurements. GO/CSAA was effective at inhibiting the growth of oral pathogens for up to 7 days of storage in water, and antibacterial activity was recovered by reapplication of the CSAA. Antibacterial GO/CSAA films were also formed on a tooth substrate. The results suggest that GO/CSAA coatings are effective in preventing oral infections.

Atmospheric impregnation behavior of calcium phosphate materials for antibiotic therapy in neurotrauma surgery.

As part of a verification model of antibiotic therapy in cranioplasty, we evaluated the impregnation efficiency of interporous calcium phosphate materials with saline under atmospheric pressure and compared it to the efficiency of using the decompression method established by the Japanese Industrial Standard, under which pressure is reduced by 10 kPa. Five types of material formed in 1 mL cubes were selected as test samples: two consisting of hydroxyapatite (HAp) with 85% and 55% porosity and three of ß-tricalcium phosphate (ß-TCP) with 75%, 67%, and 57% porosity. All test samples showed an impregnation ratio of more than 70%, except for the HAp sample with 55% porosity, which had a ratio of approximately 50%. These high ratios were achieved at only 15 min. The impregnation effects were likely dependent on porosity and were independent of base material, either HAp or ß-TCP. Obtaining sufficient impregnation and antimicrobial efficacy in materials with low porosity, which are commonly used in cranioplasty, would require an increased volume of antibiotics rather than increased duration of impregnation. Our findings will enable the simple preparation of drug-impregnated calcium phosphate materials, even in operating rooms not equipped with a large decompression device.

Suppression of root caries progression by application of Nanoseal®: A single-blind randomized clinical trial.

The aim of this single-blind, parallel and randomized controlled trial was to evaluate the effect of Nanoseal® application on root caries progression. Adult patients (n=129, mean age: 66.4±10.1 years) with root caries were randomly allocated into three groups: high-frequency (HF, n=43; intervention: Nanoseal application at baseline and 1-5 months), low-frequency (LF, n=43; intervention: Nanoseal application at baseline and 3 months), and control (n=43; intervention: no application of Nanoseal) groups. Measurements of fluorescence laser values of carious lesions using a DIAGNOdent™ Pen (D-value) were performed for each subject before intervention (baseline) and at 3 and 6 months. Significantly lower D-values for the HF (p=0.017) and LF (p=0.034) groups were observed compared with the control group at 6 months. Nanoseal application would be an effective procedure to suppress root caries progression.

Characterization and evaluation of graphene oxide scaffold for periodontal wound healing of class II furcation defects in dog.

INTRODUCTION: The 3-dimensional scaffold plays a key role in volume and quality of repair tissue in periodontal tissue engineering therapy. We fabricated a novel 3D collagen scaffold containing carbon-based 2-dimensional layered material, named graphene oxide (GO). The aim of this study was to characterize and assess GO scaffold for periodontal tissue healing of class II furcation defects in dog. MATERIALS AND METHODS: GO scaffolds were prepared by coating the surface of a 3D collagen sponge scaffold with GO dispersion. Scaffolds were characterized using cytotoxicity and tissue reactivity tests. In addition, GO scaffold was implanted into dog class II furcation defects and periodontal healing was investigated at 4 weeks postsurgery. RESULTS: GO scaffold exhibited low cytotoxicity and enhanced cellular ingrowth behavior and rat bone forming ability. In addition, GO scaffold stimulated healing of dog class II furcation defects. Periodontal attachment formation, including alveolar bone, periodontal ligament-like tissue, and cementum-like tissue, was significantly increased by GO scaffold implantation, compared with untreated scaffold. CONCLUSION: The results suggest that GO scaffold is biocompatible and possesses excellent bone and periodontal tissue formation ability. Therefore, GO scaffold would be beneficial for periodontal tissue engineering therapy.

Cerebral and Intra-ventricular Abscess Caused by Bisphosphonate-related Osteonecrosis of the Jaw (BRONJ).

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is one of the major complications caused by prolonged bisphosphonate administration. We treated a case of BRONJ-related cerebral and intraventricular abscess. An 80-year-old woman was referred to our hospital for osteonecrosis of the maxilla. Removal of a decayed tooth followed by several oral antimicrobial administrations was performed, but the inflammation spread gradually into the orbit. Twenty-seven months after the initial treatment, she was referred to our hospital. A computed tomography (CT) scan revealed formation of an intraventricular abscess secondary to destruction of the maxillary and sphenoid sinuses. Reports of BRONJ associated with intracranial infection are rare. With prolonged life expectancy, BRONJ cases will increase with many comorbid diseases. Co-operation among physicians, dentists, and pharmacologists will be needed to treat these conditions appropriately.

Graphene oxide scaffold accelerates cellular proliferative response and alveolar bone healing of tooth extraction socket.

Graphene oxide (GO) consisting of a carbon monolayer has been widely investigated for tissue engineering platforms because of its unique properties. For this study, we fabricated a GO-applied scaffold and assessed the cellular and tissue behaviors in the scaffold. A preclinical test was conducted to ascertain whether the GO scaffold promoted bone induction in dog tooth extraction sockets. For this study, GO scaffolds were prepared by coating the surface of a collagen sponge scaffold with 0.1 and 1 µg/mL GO dispersion. Scaffolds were characterized using scanning electron microscopy (SEM), physical testing, cell seeding, and rat subcutaneous implant testing. Then a GO scaffold was implanted into a dog tooth extraction socket. Histological observations were made at 2 weeks postsurgery. SEM observations show that GO attached to the surface of collagen scaffold struts. The GO scaffold exhibited an interconnected structure resembling that of control subjects. GO application improved the physical strength, enzyme resistance, and adsorption of calcium and proteins. Cytocompatibility tests showed that GO application significantly increased osteoblastic MC3T3-E1 cell proliferation. In addition, an assessment of rat subcutaneous tissue response revealed that implantation of 1 µg/mL GO scaffold stimulated cellular ingrowth behavior, suggesting that the GO scaffold exhibited good biocompatibility. The tissue ingrowth area and DNA contents of 1 µg/mL GO scaffold were, respectively, approximately 2.5-fold and 1.4-fold greater than those of the control. Particularly, the infiltration of ED2-positive (M2) macrophages and blood vessels were prominent in the GO scaffold. Dog bone-formation tests showed that 1 µg/mL GO scaffold implantation enhanced bone formation. New bone formation following GO scaffold implantation was enhanced fivefold compared to that in control subjects. These results suggest that GO was biocompatible and had high bone-formation capability for the scaffold. The GO scaffold is expected to be beneficial for bone tissue engineering therapy.