Physical Properties and Antimicrobial Release Ability of Gentamicin-Loaded Apatite Cement/α-TCP Composites: An In Vitro Study.

Apatite cement (AC), which has excellent osteoconductive ability, and alpha-tricalcium phosphate (α-TCP), which can be used for bone replacement, are useful bone substitute materials. The objective of this study was to clarify the physical properties and antimicrobial release ability of antibiotic-loaded AC/α-TCP composites in vitro. Gentamicin-loaded, rapid setting AC/α-TCP composites were prepared in 2 mixing ratios (10:3 and 10:6). The cement paste of AC/α-TCP composites was prepared in a plastic mold and dried in a thermostatic chamber at 37 °C and 100% relative humidity for 24 h. A diametral tensile strength test, powder X-ray diffraction analysis, and gentamicin release test were performed. The diametral tensile strengths of the AC/α-TCP composites were significantly less than that of AC alone. Powder X-ray diffraction patterns exhibited the characteristic peaks of hydroxyapatite in the AC/α-TCP composites and gentamicin-loaded AC/α-TCP composites. The concentration of the released gentamicin was maintained above the minimum inhibitory concentration of Staphylococcus aureus until Day 30 in both the gentamicin-loaded AC/α-TCP composites (10:3 and 10:6). Our results suggest that a gentamicin-loaded AC/α-TCP composite has potential as a drug delivery system. Further study is essential to investigate the antimicrobial activity and safety of the gentamicin-loaded AC/α-TCP composites in animal models.

In vitro investigation of the cell compatibility and antibacterial properties of titanium treated with calcium and ozone.

The purpose of this study was to evaluate the surface modification of calcium ions on roughened titanium as a surface treatment of dental implants for cell attachment, growth, and initial bacterial adhesion. When a surface-roughened, pure titanium disk was immersed in a calcium chloride solution (100 mM) containing 20 ppm ozone for 24 h at 25ºC, calcium was detected on the surface by X-ray photoelectron spectroscopy. The calcium-modified, roughened titanium disk had a significantly greater concentration of the initially adhered cells as well as cells cultured over 7 days compared with titanium disks without surface modification. Furthermore, the initial bacterial adhesion on the calcium-ozone treated titanium disk was statistically less than on a pure titanium disk or titanium disk treated without ozone. Dissolved ozone was useful for modifying the surface of roughened titanium with calcium ions and the surface modification may be applicable for dental implants.

Morphological Evaluation of Bone by CT to Determine Primary Stability-Clinical Study.

BACKGROUND: Primary stability is an important prognostic factor for dental implant therapy. In the present study, we evaluate the relationship between implant stability evaluation findings by the use of an implant stability quotient (ISQ), an index for primary stability, and a morphological evaluation of bone by preoperative computed tomography (CT). SUBJECTS AND METHODS: We analyzed 98 patients who underwent implant placement surgery in this retrospective study. For all 247 implants, the correlations of the ISQ value with cortical bone thickness, cortical bone CT value, cancellous bone CT value, insertion torque value, implant diameter, and implant length were examined. RESULTS: 1. Factors affecting ISQ values in all cases: It was revealed that there were significant associations between the cortical bone thickness and cancellous bone CT values with ISQ by multiple regression analysis. 2. It was revealed that there was a significant correlation between cortical bone thickness and cancellous bone CT values with ISQ by multiple regression analysis in the upper jaw. 3. It was indicated that there was a significant association between cortical bone thickness and implant diameter with ISQ by multiple regression analysis in the lower jaw. CONCLUSION: We concluded that analysis of the correlation of the ISQ value with cortical bone thickness and values obtained in preoperative CT imaging were useful preoperative evaluations for obtaining implant stability.

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report.

Autogenous block bone grafting as treatment for alveolar ridge atrophy has various disadvantages, including a limited availability of sufficiently sized and shaped grafts, donor site morbidity and resorption of the grafted bone. As a result, interconnected porous hydroxyapatite ceramic (IP-CHA) materials with high porosity have been developed and used successfully in orthopedic cases. To the best of the author's knowledge, this is the first report of clinical application of an IP-CHA block for onlay grafting for implant treatment in a patient with horizontal alveolar atrophy. The present study performed onlay block grafting using an IP-CHA block to restore bone volume for implant placement in the alveolar ridge area without collecting autogenous bone. Dental X-ray findings revealed that the border of the IP-CHA block became increasingly vague over the 3-year period, whereas CT scanning revealed that the gap between the block and bone had a smooth transition, indicating that IP-CHA improved the process of integration with host bone. In follow-up examinations over a period of 5 years, the implants and superstructures had no problems. An IP-CHA block may be useful as a substitute for onlay block bone grafting in implant treatment.

Preoperative oral health care reduces postoperative inflammation and complications in oral cancer patients.

The records of 70 patients with oral cancer who were treated at a single institution between 2008 and 2014 were reviewed. The body temperature, white blood cell count, and C-reactive protein (CRP) levels were compared between those who had received preoperative oral care (oral care group) and those who had not received any (non-oral care group). When the patients were divided into those who underwent minimally invasive surgery and those who underwent severely invasive surgery, the mean CRP level in the early postoperative period was lower in the oral care group as compared with the non-oral care group in those who underwent minimally invasive surgery as well as those who underwent severely invasive surgery. However, the mean CRP level was most evidently reduced in the severely invasive group on days 1 and 3-5. However, no significant differences were observed with regard to the percentage of postoperative infectious complications (for example, surgical site infection, anastomotic leak and pneumonia) between the oral care (13.6%) and non-oral care (20.8%) groups, though a reduced prevalence of postoperative complications following preoperative oral care was noted. The results of the present study suggest that preoperative oral care can decrease inflammation during the early postoperative stage in patients with oral cancer who undergo severely invasive surgery.

Effects of Apatite Cement Containing Atelocollagen on Attachment to and Proliferation and Differentiation of MC3T3-E1 Osteoblastic Cells.

To improve the osteoconductivity of apatite cement (AC) for reconstruction of bone defects after oral maxillofacial surgery, we previously fabricated AC containing atelocollagen (AC(ate)). In the present study, we examined the initial attachment, proliferation and differentiation of mouse osteoblastic cells (MC3T3-E1 cells) on the surface of conventional AC (c-AC), AC(ate) and a plastic cell dish. The number of osteoblastic cells showing initial attachment to AC(ate) was greater than those attached to c-AC and similar to the number attached to the plastic cell wells. We also found that osteoblastic cells were well spread and increased their number on AC(ate) in comparison with c-AC and the wells without specimens, while the amount of procollagen type I carboxy-terminal peptide (PIPC) produced in osteoblastic cells after three days on AC(ate) was greater as compared to the others. There was no significant difference in regard to alkaline phosphatase (ALP) activity and osteocalcin production by osteoblastic cells among the three surface types after three and six days. However, after 12 days, ALP activity and the produced osteocalcin were greater with AC(ate). In conclusion, AC(ate) may be a useful material with high osteoconductivity for reconstruction of bone defects after oral maxillofacial surgery.

Bone formation and osseointegration with titanium implant using granular- and block-type porous hydroxyapatite ceramics (IP-CHA).

The aim of the present study was to examine whether interconnected porous hydroxyapatite ceramics (IP-CHA) could be used as bone substitute for implant treatment in reconstructive surgery. We firstly assessed if surround of the titanium surface placed into granular or block-type IP-CHA can observe new bone formation in a rabbit bone defect model. Subsequently, osseointegration and stability of titanium implant inserted into block-type IP-CHA was investigated in a rabbit onlay graft model. Direct contact between new bone and the surface of the titanium in granular- or block-type IP-CHA was found in a rabbit bone defect. Further, new bone formation was found in direct contact with the implant surface in the block-type IP-CHA in an onlay graft model, and the implant stability quotient (ISQ) values were significantly increased after surgery. Therefore, IP-CHA may be a useful material for implant treatment in reconstructive surgery strategies.

Risk of bacterial contamination of bone harvesting devices used for autogenous bone graft in implant surgery.

BACKGROUND: Various instruments have been developed for collecting bone debris during intraoral autogenous bone graft procedures in implant surgery. The aim of this study was to quantitatively determine the degree of contamination in bone debris collected by different devices. METHODS: Twelve patients underwent autogenous bone collection using a bone chisel, bone scraper, trephine drill, and bone filter during bone augmentation surgery as a part of implant therapy, and the total bacterial count in bone debris collected by each was determined. RESULTS: Following anaerobic incubation, bacterial colony formation was found in all of the samples. The mean colony forming units (CFU)/g in samples collected by the trephine drill was found to be significantly lower than that of samples obtained with the other devices, while those values for samples collected by the bone scraper and bone filter was significantly higher as compared to the bone chisel and trephine drill. CONCLUSION: The bacterial levels may still carry the infection risk. Thus prophylactic antibiotic therapy maybe indicated when using bone particles for intraoral augmentation procedures.

3-dimensional composite scaffolds consisting of apatite-PLGA-atelocollagen for bone tissue engineering.

We fabricated 3-dimensional scaffolds consisting of biodegradable poly(D, L-lactide-co-glycolic acid)(PLGA)(75/25) with hydroxyapatite particles containing atelocollagen (aAC). The aim of this study was to evaluate this new type of scaffold in regard to its basic properties and biocompatibility. Characterization of the obtained scaffolds was performed to know the porosity, shrinkage, diametral tensile strength, and biocompatibility. Composite scaffolds made of PLGA with hydroxyapatite particles containing atelocollagen (PL-aAC) showed a greater strength and stability than PLGA scaffolds. PL-aAC also exhibited superior performance in terms of cell attachment and proliferation as compared to PLGA, while histological findings showed that PL-aAC had an excellent response toward soft tissues. Our results strongly suggest that PL-aAC is more useful for cell transplantation as compared to PLGA for bone tissue engineering.

Increased expression of CENP-H gene in human oral squamous cell carcinomas harboring high-proliferative activity.

We examined the expression of Centromere protein H (CENP-H) mRNA in 38 oral squamous cell carcinomas (SCCs), 2 epithelial dysplasias and 5 normal gingivae using the real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). The mean expression level of CENP-H mRNA was higher in oral SCCs (0.11+/-0.08) than epithelial dysplasias (0.03+/-0.01) and normal gingivae (0.027+/-0.01). The expression level of CENP-H mRNA was significantly higher in oral SCCs than normal gingivae (Mann-Whitney U test, P=0.005). We also found a significant association between the level of CENP-H mRNA expression and clinical stage in oral SCCs (Mann-Whitney U test, P=0.04). We next studied the expression of CENP-H in 17 oral SCCs immunohistochemically. A significant correlation between the expression levels of CENP-H protein and the Ki-67 labeling index was found (Mann-Whitney U test, P=0.005). These results indicate that human CENP-H is closely linked to the increased or abnormal cell proliferation in malignant conditions.