Objective: To examine the stability of mini-screws that invade a dental root by measuring the retention period/failure rate, and to illustrate their effects on paradental tissues. Materials and Methods: Three adult male beagle dogs received 48 orthodontic mini-screws. Half of the mini-screws were implanted to invade the roots, and the rest were placed in the middle of the alveolar bone. Half of the mini-screws were loaded immediately. The retention period of the mini-screws was documented. The dogs were euthanized after 8 weeks, and tissue samples were examined histologically.
Results:The failure rate of the mini-screws that invaded the roots was 79.2%, and that of the mini-screws in the middle of the alveolar bone was 8.3%. The application of force had little effect on the failed mini-screws. Moderately injured roots were repaired with osteoid and/or cementoid tissues with normal periodontal ligaments, followed by recovery of the original configuration.
In our previous studies, we confirmed that low-level laser therapy (LLLT) with a 980-nm gallium-aluminum-arsenide diode laser was beneficial for the healing of the alveolar bone in rats with systemic disease. However, many factors can affect the biostimulatory effects of LLLT. Thus, we attempted to investigate the effects of irradiation time on the healing of extraction sockets by evaluating the expressions of genes and proteins related to bone healing. The left and right first maxillary molars of 24 rats were extracted. Rats were randomly divided into four groups in which extraction sockets were irradiated for 0, 1, 2, or 5 min each day for 3 or 7 days. Specimens containing the sockets were examined using quantitative real-time reverse transcription polymerase chain reaction and western blotting. LLLT increased the expressions of all tested genes, Runx2, collagen type 1, osteocalcin, platelet-derived growth factor-B, and vascular endothelial growth factor, in a time-dependent manner. The highest levels of gene expressions were in the 5-min group after 7 days. Five minutes of irradiation caused prominent increases of the expression of all tested proteins after both 3 and 7 days. The expression level of each protein in group 4 was higher by almost twofold compared with group 1 after 7 days. Laser irradiation for 5 min caused the highest expressions of genes and proteins related to bone healing. In conclusion, LLLT had positive effects on the early stages of bone healing of extraction sockets in rats, which were irradiation time-dependent.
Although many attempts have been made to predict the occurrence of lymph node metastases from papillary thyroid carcinoma, there are currently no reliable means to accurately predict cervical nodal metastasis. In this study, we present a novel prediction system for the lymph node metastasis based on the histological and cyclin D1 staining features. The frequency of lymph node metastases from a series of 210 papillary thyroid carcinomas was analyzed according to the clinicopathological variables, cyclin D1 staining patterns and BRAF V600E mutation in tumor tissue. A total of 113 (54%) patients had lymph node metastasis. Cyclin D1 was constantly expressed at the invasive tumor front and revealed well-defined isolated glands of tumor cells in the extratumoral region (isolated glands) and laterally spreading tubular growth along the fibrous septa around the invasive front of the tumor (lateral tubular growth). Upon univariate analysis, an age of less than 45 years (Po0.001), tumor size of 10 mm or more (Po0.001), non-follicular variant (P ¼ 0.005), invasive growth pattern (P ¼ 0.007), extrathyroid extension (P ¼ 0.006), isolated glands (Po0.001), lateral tubular growth (Po0.001) and tumor multiplicity (P ¼ 0.005) predicted lymph node metastasis, whereas BRAF V600E mutation did not. Upon multivariate analysis, age (P ¼ 0.001, odds ratio (OR) ¼ 5.146), tumor size (P ¼ 0.034, OR ¼ 3.119), isolated glands (Po0.001, OR ¼ 21.042) and lateral tubular growth (Po0.001, OR ¼ 24.652) were found to be strong independent predictors of lymph node metastasis. Cyclin D1 staining of papillary thyroid carcinoma is very useful for identifying the intrathyroidal spreading or multifocality of the tumors. Tumor growth patterns verified by cyclin D1 staining can be used for the identification of papillary thyroid carcinomas with metastatic potential.
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