Reconstruction of rabbit mandibular bone defects using carbonate apatite honeycomb blocks with an interconnected porous structure.

Carbonate apatite (CO3Ap) granules are useful as a bone substitute because they can be remodeled to new natural bone in a manner that conforms to the bone remodeling process. However, reconstructing large bone defects using CO3Ap granules is difficult because of their granular shape. Therefore, we fabricated CO3Ap honeycomb blocks (HCBs) with continuous unidirectional pores. We aimed to elucidate the tissue response and availability of CO3Ap HCBs in the reconstruction of rabbit mandibular bone defects after marginal mandibulectomy. The percentages of the remaining CO3Ap area and calcified bone area (newly formed bone) were estimated from the histological images. CO3Ap area was 49.1 ± 4.9%, 30.3 ± 3.5%, and 25.5 ± 8.8%, whereas newly formed bone area was 3.0 ± 0.6%, 24.3 ± 3.3%, and 34.7 ± 4.8% at 4, 8, and 12 weeks, respectively, after implantation. Thus, CO3Ap HCBs were gradually resorbed and replaced by new bone. The newly formed bone penetrated most of the pores in the CO3Ap HCBs at 12 weeks after implantation. By contrast, the granulation tissue scarcely invaded the CO3Ap HCBs. Some osteoclasts invaded the wall of CO3Ap HCBs, making resorption pits. Furthermore, many osteoblasts were found on the newly formed bone, indicating ongoing bone remodeling. Blood vessels were also formed inside most of the pores in the CO3Ap HCBs. These findings suggest that CO3Ap HCBs have good osteoconductivity and can be used for the reconstruction of large mandibular bone defects. The CO3Ap HCB were gradually resorbed and replaced by newly formed bone.

Association of PD-L1 and ZEB-1 expression patterns with clinicopathological characteristics and prognosis in oral squamous cell carcinoma.

Programmed cell death-1 (PD-1) and its ligand programmed cell death 1 ligand 1 (PD-L1) are immune checkpoint inhibitors that play an important role in the host immune avoidance mechanism of tumors. The relationship between PD-L1 expression and malignancy has been reported in various types of cancer, such as lung and gastric cancer. In addition, epithelial-mesenchymal transition (EMT) of cancer cells is deeply involved in the invasion and metastasis of cancer. It has been reported that zinc finger E-box binding homeobox 1 (ZEB-1), an EMT inducer, contributes to metastasis in pancreatic and colon cancer. The present study aimed to investigate the relationship between the expression patterns of two markers, PD-L1 and ZEB-1, and clinicopathological characteristics and prognosis of oral squamous cell carcinoma (OSCC). Biopsy or surgical excision specimens from 169 patients with OSCC were used in the present study. Immunohistochemical staining with monoclonal anti-PD-L1 antibody and anti-ZEB-1 antibody was conducted. Cases with >1% tumor cells positive for PD-L1 and those with >10% tumor cells positive for ZEB-1 were considered positive, respectively. The findings revealed that individual expression of PD-L1 and ZEB-1 in OSCC was not associated with tumor size, degree of differentiation or Yamamoto-Kohama invasion pattern classification. However, co-expression of PD-L1 and ZEB-1 was associated with higher cervical lymph node metastasis and a lower survival rate. In conclusion, the results of the present study indicated that co-expression of PD-L1 and ZEB-1 could serve as a potential marker for the prognosis of patients with OSCC.

Effects of acidic calcium phosphate concentration on setting reaction and tissue response to ß-tricalcium phosphate granular cement.

Beta-tricalcium phosphate granular cement (ß-TCP GC), consisting of ß-TCP granules and an acidic calcium phosphate (Ca-P) solution, shows promise in the reconstruction of bone defects as it sets to form interconnected porous structures, that is, ß-TCP granules are bridged with dicalcium phosphate dihydrate (DCPD) crystals. In this study, the effects of acidic Ca-P solution concentration (0-600 mmol/L) on the setting reaction and tissue response to ß-TCP GC were investigated. The ß-TCP GC set upon mixing with its liquid phase, based on the formation of DCPD crystals, which bridged ß-TCP granules to one another. Diametral tensile strength of the set ß-TCP GC was relatively the same, at ∼0.6 MPa, when the Ca-P concentration was 20-600 mmol/L. Due to the setting ability, reconstruction of the rat's calvarial bone defect using ß-TCP GC with 20, 200, and 600 mmol/L Ca-P solution was much easier compared to that with ß-TCP granules without setting ability. Four weeks after the reconstruction, the amount of new bone was the same, ∼17% in both ß-TCP GC and ß-TCP granules groups. Cellular response to ß-TCP granules and ß-TCP GC using the 20 mmol/L acidic Ca-P solution was almost the same. However, ß-TCP GC using the 200 and 600 mmol/L acidic Ca-P solution showed a more severe inflammatory reaction. It is concluded, therefore, that ß-TCP GC, using the 20 mmol/L acidic Ca-P solution, is recommended as this concentration allows surgical techniques to be performed easily and provides good mechanical strength, and the similar cellular response to ß-TCP granules. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:22-29, 2020.

Histological comparison of three apatitic bone substitutes with different carbonate contents in alveolar bone defects in a beagle mandible with simultaneous implant installation.

Since bone apatite is a carbonate apatite containing carbonate in an apatitic structure, carbonate content may be one of the factors governing the osteoconductivity of apatitic bone substitutes. The aim of this study was to evaluate the effects of carbonate content on the osteoconductivity of apatitic bone substitutes using three commercially available bone substitutes for the reconstruction of alveolar bone defects of a beagle mandible with simultaneous dental implant installation. NEOBONE, Bio-Oss, and Cytrans that contain 0.1, 5.5, and 12.0 mass% of carbonate, respectively, were used in this study. The amount of newly formed bone in the upper portion of the alveolar bone defect of the beagle's mandible was 0.7, 6.6, and 39.4% at 4 weeks after surgery and 4.7, 39.5, and 75.2% at 12 weeks after surgery for NEOBONE, Bio-Oss, and Cytrans, respectively. The results indicate that bone-to-implant contact ratio was the largest for Cytrans. Additionally, the continuity of the alveolar ridge was restored in the case of Cytrans, whereas the continuity of the alveolar ridge was not sufficient when using NEOBONE and Bio-Oss. Both Cytrans and Bio-Oss that have a relatively larger carbonate content in their apatitic structure was resorbed with time. We concluded that carbonate content is one of important factors governing the osteoconductivity of apatitic bone substitutes.

Fabrication of porous carbonate apatite granules using microfiber and its histological evaluations in rabbit calvarial bone defects.

Carbonate apatite (CO3 Ap) granules are known to show good osteoconductivity and replaced to new bone. On the other hand, it is well known that a porous structure allows bone tissue to penetrate its pores, and the optimal pore size for bone ingrowth is dependent on the composition and structure of the scaffold material. Therefore, the aim of this study was to fabricate various porous CO3 Ap granules through a two-step dissolution-precipitation reaction using CaSO4 as a precursor and 30-, 50-, 120-, and 205-µm diameter microfibers as porogen and to find the optimal pore size of CO3 Ap. Porous CO3 Ap granules were successfully fabricated with pore size 8.2-18.7% smaller than the size of the original fiber porogen. Two weeks after the reconstruction of rabbit calvarial bone defects using porous CO3 Ap granules, the largest amount of mature bone was seen to be formed inside the pores of CO3 Ap (120) [porous CO3 Ap granules made using 120-µm microfiber] followed by CO3 Ap (50) and CO3 Ap (30). At 4 and 8 weeks, no statistically significant difference was observed based on the pore size, even though largest amount of mature bone was formed in case of CO3 Ap (120). It is concluded, therefore, that the optimal pore size of the CO3 Ap is that of CO3 Ap (120), which is 85 µm.

Expression of CD44, CD44v9, ABCG2, CD24, Bmi-1 and ALDH1 in stage I and II oral squamous cell carcinoma and their association with clinicopathological factors.

Cancer stem cells (CSCs) exhibit self-replication, self-differentiation, drug resistance and immune evasion activities. In recent years CSCs have become increasingly important for the treatment of malignant tumors. CSCs express specific markers, including cluster of differentiation (CD)44, CD44 variant 9 (CD44v9), ATP-binding cassette sub-family G member 2 (ABCG2), CD24, B lymphoma Mo-MLV insertion region 1 homolog (BMI-1) and aldehyde dehydrogenase 1 (ALDH1). However, the prognostic value of their expression in patients with oral squamous cell carcinoma (OSCC) are not well known. The present study evaluated these markers in stage I and II patients with OSCC and examined the association between T classification, histological differentiation, classification of invasion mode, lymph node metastasis and disease-free survival rate. Tissue specimens were obtained from 70 patients with stage I or II OSCC following either surgery or biopsy. Immunohistochemistry was performed and positive staining was defiend as 10% positive cells. CD44 and CD44v9 expressions were strongly detected in all OSCC tissues compared with normal epithelial cells. A total of 22 (31.4%) cases expressed ABCG2 and there was a significant association between ABCG2 expression and invasion. A total of 41 cases (59.0%) expressed CD24 and there was a significant association between CD24 expression and invasion. A total of 33 cases (47.1%) expressed BMI-1 and there was a significant association between BMI-1 expression and the disease-free survival rate. A total of 18 cases (25.7%) expressed ALDH1. Although there was no association between ALDH1 expression and T classification, there were significant associations between ALDH1 expression and histological differentiation, invasion mode, metastasis and the disease-free survival rate. Multivariate analysis revealed that ALDH1 expression was the only prognostic factor for disease-free survival rate. The results of the present study suggest that the positivity of ALDH1 detected in patients with OSCC correlates with the number of cells undergoing epithelial mesenchymal transition and metastasis. These findings indicated that the expression of ALDH1 may be an effective prognostic marker indicating the survival of patients with stage I and II OSCC.

Compositional and histological comparison of carbonate apatite fabricated by dissolution-precipitation reaction and Bio-Oss®.

Carbonate apatite (CO3Ap) is an inorganic component of bone. This study aimed to compare the composition and tissue response to of CO3Ap (CO3Ap-DP) fabricated by the dissolution-precipitation reaction using calcite as a precursor and Bio-Oss®, which is widely used in orthopedic and dental fields as a synthetic bone substitute. X-ray diffraction and Fourier transform infrared results showed that CO3Ap-DP and Bio-Oss® were both B-type carbonate apatite with low crystallinity. The average sizes of CO3Ap-DP and Bio-Oss® granules were 450 ± 58 and 667 ± 168µ m, respectively, and their carbonate contents were 12.1 ± 0.6 and 5.6 ± 0.1 wt%, respectively. CO3Ap-DP had a larger amount of CO3 than Bio-Oss® but higher crystallinity than Bio-Oss®. When a bone defect made at the femur of rabbits was reconstructed with CO3Ap-DP and Bio-Oss®, CO3Ap-DP granules were partially replaced with bone, whereas Bio-Oss® remained at 8 weeks after implantation. CO3Ap-DP granules elicited a significantly larger amount of new bone formation at the cortical bone portion than Bio-Oss® at 4 weeks after the implantation. The results obtained in the present study demonstrated that CO3Ap-DP and Bio-Oss® showed different behavior even though they were both classified as CO3Ap. The CO3 content in CO3Ap played a more important role than the crystallinity of CO3Ap for replacement to bone and high osteoconductivity.

Prevalence and imaging characteristics of nasopharyngeal and eustachian tube tonsilloliths in 2244 patients determined using computed tomography.

OBJECTIVES:: Nasopharyngeal tonsilloliths (NT) and eustachian tube tonsilloliths (ET) are not as well-known to radiologists as palatine and lingual tonsilloliths. The aim of this investigation was to determine the prevalence and imaging characteristics of NT and ET using CT and panoramic radiographs. METHODS:: We retrospectively assessed the scans of 2244 patients who underwent consecutive CT and panoramic radiographs of the maxillofacial region. The prevalence, size, number, and position of NT and ET were analysed. RESULTS:: NT and ET were detected in 14 (0.6%) and 6 (0.3%) of 2244 patients on CT, respectively, but they were undetectable on panoramic radiographs. No significant difference was found in the prevalence with respect to sex. Although there was also no significant difference in the prevalence among age groups, tonsilloliths were most commonly noted in patients over 40 years old; they appeared as small and round calcified bodies, ranging from 1 to  3 mm in diameter. All NT were found 0 to 3 mm beneath the nasopharyngeal mucosal surface. CONCLUSIONS:: The prevalence of NT and ET on CT was lower than that of palatine and lingual tonsilloliths. However, since they are encountered more frequently than clinically significant calcifying diseases such as retropharyngeal calcific tendinitis, clinicians should be able to correctly diagnose NT and ET based on their anatomical features.