[Prediction, analysis and application of learning curve of tooth preparation for all ceramic crowns of maxillary central incisors].

OBJECTIVE: To predict the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training based on the modified Wright learning curve model, then to analyze and applicate the learning curve. METHODS: Twelve graduate students participating in standardized dental resident training were selected to prepare the resin maxillary central incisors on phantom head simulators for all ceramic crowns 4 times. The results of preparation were evaluated by 3 prosthetic experts with at least 10 years' experience focusing on the reduction, contour, taper, shoulder, finish line, margin placement, adjacent tooth injury, and preparation time for tooth preparation. The learning rate of tooth preparation was calculated by scores of tooth preparation of 4 times. The learning curve of tooth preparation was predicted based on the modified Wright learning curve model. According to the criteria of standardized training skill examinations for dental residents in Beijing, 80 was taken as the qualified standard score. The minimum training times for tooth preparation to satisfy the qualified standard score (80) was calculated, to analyze the characteristics of learning curve and evaluate the effectiveness of tooth preparation. RESULTS: The scores of 4 tooth preparation were 64.03±7.80, 71.40±6.13, 74.33±5.96, and 75.98±4.52, respectively. The learning rate was (106±4)%, which showed the learning curve an upward trend. There were no significant differences between the qualified standard score and the predicted scores of tooth preparation from the 5th preparation to the 13th preparation (P > 0.05). The predicted score of the 14th preparation was higher than the qualified standard score (P < 0.05). CONCLUSION: The trend of the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training is upward, which predicts the minimum training times higher than the qualified standard score is 14 times.

[Clinical applicational comparison of digital impression and silicon rubber impression technique in posterior implant-supported single crown restoration].

Objective: To investigate the clinical effect and satisfaction of partially edentulous patients restored with posterior implant-supported single crown by digital impression technique and traditional silicon rubber impression, in order to provide clinical reference. Methods: Sixty-four partially edentulous patients who visited the Department of Prosthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University between March 2018 and January 2021 were enrolled. There were 31 male and 33 female, and the age of the group of patients was (49.3±13.3) years. The 113 implants placed in this group of patients were divided into digital impression group (n=70) and silicone rubber impression group (n=43) according to different impression techniques, and were restored with screw-retained full zirconia single crown, and the patients were followed up for 3-36 months after treatment. The implant survival rate, upper prosthesis, peri-implant soft tissue status, marginal bone loss and patients satisfaction were recorded to evaluate the clinical effects of two impression techniques in posterior implant-supported single crown. Results: In sixty-four patients, digital impression accounted for 62% (40/64), and silicon rubber impression accounted for 38% (24/64), the survival rate of 113 implants was 100% (113/113). The prevalence of interproximal contact loss, food impaction and mechanical complication of the upper full zirconia single crown restorations were 22.7% (41/181), 8.0% (9/113) and 2.7% (3/113) separately. All the mechanical complications were abutment screw loosening. All patients maintained good oral hygiene status, the incidences of peri-implantitis and peri-implant mucositis were 0.9% (1/113) and 4.4% (5/113) respectively. The marginal bone loss was (0.24±0.11) mm. The median of satisfaction visual analogue scale score in patients was 9-10, but no statistically significant differences of all the above results were observed between the two impression techniques (P>0.05). Conclusions: The clinical effect of partially edentulous patients restored with posterior implant-supported single crown using two different impression techniques is good and the satisfaction of patients is high, but the long-term clinical effect remains to be further observed.

[Authorization, translation, back translation and language modification of the Chinese version of the obturator functioning scale].

Objective: To cross-cultural adapt the English version of obturator functioning scale (OFS) to form a simplified Chinese version, to preliminarily verify its reliability and validity in clinic, and to provide an effective tool for evaluating the oral function and quality of life of patients with palatal defect and restored with obturators in China. Methods: The English version of the OFS was taken for forward translation, synthesis, back-translation, and reviewed by expert committee to develop a pre-testing simplified Chinese version. This scale contained demographic data, basic information of diseases, eating problems dimensions (3 items), speech problems dimensions (5 items), and other problems dimensions (7 items). From December, 2016 to December, 2018, forty-two patients who were treated in the Department of Prosthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University with palatal defect and restored with obturators were evaluated with OFS. Among them, there were 26 males, and 21-84 years old, and 16 females, who were 24-80 years old.The reliability and validity of the data were examined and analyzed. Results: The results showed that Cronbach's α coefficients of the overall scale and the three dimensions (eating problems, speech problems, and other problems) were 0.926, 0.938, 0.930, and 0.935, respectively. The internal consistency of the questionnaire was very good. The Spearman coefficients between each single dimension and the total score were 0.677, 0.792, and 0.860, respectively, suggesting that the scale convergence was good. The content validity index of 15 items was 0.905, indicating that the content validity was very good. Conclusions: The Chinese version of the OFS is exhibiting high reliability and validity, providing an effective evaluation tool of oral function and quality of life for Chinese patients with obturator prostheses to restore palate defects.

Association between Anxiety and Pain in Dental Treatment: A Systematic Review and Meta-analysis.

Accumulating evidence has revealed that dental anxiety (DA), as a dispositional factor toward the dental situation, is associated with the state anxiety (SA) and pain related to dental procedures. However, conclusions from individual studies may be limited by the treatment procedures that patients received, the tools used to assess DA, or the treatment stages when anxiety or pain was assessed. It is unclear whether DA, at the study level, accounts for the variance in pretreatment SA. The impact of DA and SA on pain at different treatment stages has not been systematically investigated. To address these questions, we present novel meta-analytical evidence from 35 articles (encompassing 47 clinical groups) that investigated DA in a clinical group. Subgroup analyses revealed that the studies of surgical and nonsurgical procedures did not significantly differ in either DA or pretreatment SA. Furthermore, metaregressions revealed DA as a significant predictor that explained the variance in SA assessed before and during treatment but not after treatment. The findings suggest that patient DA has a significant impact on patient SA. Metaregressions revealed DA as a significant predictor that explained the variance in expected pain, pain during treatment and posttreatment pain. In contrast, pretreatment SA was a significant predictor that explained the variance in expected pain. The findings reveal that DA has a consistent impact on pain through the entire period of dental treatment. Altogether, the findings highlight the role of DA as an overall indicator for anxiety and pain, across different types of dental procedures or treatment stages. We conclude that anxiety should be assessed as a critical step not only in anxiety management for high-DA patients, but also in pain control for all dental patients.

Hypoxia-upregulated microRNA-630 targets Dicer, leading to increased tumor progression.

MicroRNAs (miRNAs) are small RNA molecules that affect cellular processes by controlling gene expression. Recent studies have shown that hypoxia downregulates Drosha and Dicer, key enzymes in miRNA biogenesis, causing a decreased pool of miRNAs in cancer and resulting in increased tumor growth and metastasis. Here we demonstrate a previously unrecognized mechanism by which hypoxia downregulates Dicer. We found that miR-630, which is upregulated under hypoxic conditions, targets and downregulates Dicer expression. In an orthotopic mouse model of ovarian cancer, delivery of miR-630 using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nanoliposomes resulted in increased tumor growth and metastasis, and decreased Dicer expression. Treatment with the combination of anti-miR-630 and anti-vascular endothelial growth factor antibody in mice resulted in rescue of Dicer expression and significantly decreased tumor growth and metastasis. These results indicate that targeting miR-630 is a promising approach to overcome Dicer deregulation in cancer. As demonstrated in the study, use of DOPC nanoliposomes for anti-miR delivery serves as a better alternative approach to cell line-based overexpression of sense or antisense miRNAs, while avoiding potential in vitro selection effects. Findings from this study provide a new understanding of miRNA biogenesis downregulation observed under hypoxia and suggest therapeutic avenues to target this dysregulation in cancer.

Accelerated healing by composites containing herb epimedium for osteoinductive regeneration.

Porous composites composed of hydroxyapatite (HA), herb epimedium (EP), and chitosan (CS) were used to improve the repair of rabbit bone defects. The in vivo implantation of the HA/CS-EP showed that homogeneous bone formation occurred after 12 weeks' implantation and possessed good osteogenesis. The osteogenic process of the HA/CS-EP group was different from that of the HA/CS group. Direct bone formation of osteoblasts with HA/CS-EP as the matrix could be observed. Compared with the group filled with HA/CS, the group filled with HA/CS-EP showed significant increases in the number of osteoblasts and the bone formation area, and the areas of new bone formation in the HA/CS-EP group after 4 or 12 weeks' implantation reached 33% and 87%, respectively. The novel repair system of HA/CS-EP can induce bone formation, increase osteoblast quantity and improve osteogenesis, for EP can significantly promote the proliferation and activity of osteoblasts in the early stage and accelerate bone remodeling in the later stage. Composites containing EP could be a promising material with multifunctions of osteoinduction, osteoconduction and medication for bone repair, and herb medicine EP could be used as an osteoinduction material for bone tissue engineering.

Two-dimensional biosensor arrays based on surface plasmon resonance phase imaging.

We present a biosensor design based on capturing the two-dimensional (2D) phase image of surface plasmon resonance (SPR). This 2D SPR imaging technique may enable parallel label-free detection of multiple analytes and is compatible with the microarray chip platform. This system uses our previously reported differential phase measurement approach, in which 2D phase maps obtained from the signal (P) and reference (S) polarizations are compared pixel by pixel. This technique greatly improves detection resolution as the subtraction step can eliminate measurement fluctuations caused by external disturbances as they essentially appear in both channels. Unlike conventional angular SPR systems, in which illumination from a range of angles must be used, phase measurement requires illumination from only one angle, thus making it well suited for 2D measurement. Also, phase-stepping introduced from a moving mirror provides the necessary modulation for accurate detection of the phase. In light of the rapidly increasing need for fast real-time detection, quantification, and identification of a range of proteins for various biomedical applications, our 2D SPR phase imaging technique should hold a promising future in the medical device market.