Effect of different tooth preparation designs on the marginal and internal fit discrepancies of cobalt-chromium crowns produced by computer-aided designing and selective laser melting processes

PURPOSE@#To evaluate the impact of five different tooth preparation designs on the marginal and internal fit discrepancies of cobalt-chromium (CoCr) crowns produced by computer-aided designing (CAD) and selective laser melting (SLM) processes. @*MATERIALS AND METHODS@#Five preparation data were constructed, after which design crowns were obtained. Actual crowns were fabricated using an SLM process. After the data of actual crowns were obtained with structural light scanning, intaglio surfaces of the design crown and actual crown were virtually superimposed on the preparation. The fit-discrepancies were displayed with colors, while the root means square was calculated and analyzed with one-way analysis of variance (ANOVA), Tukey’s test or Kruskal-Wallis test (α =.05). @*RESULTS@#The marginal or internal color-coded images in the five design groups were not identical. The shoulder-lip and sharp line angle groups in the CAD or SLM process had larger marginal or internal fit discrepancies compared to other groups (P < .05). In the CAD process, the mean marginal and internal fit discrepancies were 10.0 to 24.2 µm and 29.6 to 31.4 µm, respectively. After the CAD and SLM processes, the mean marginal and internal fit discrepancies were 18.4 to 40.9 µm and 39.1 to 47.1 µm, respectively. The SLM process itself resulted in a positive increase of the marginal (6.0 – 16.7 µm) and internal (9.0 – 15.7 µm) fit discrepancies. @*CONCLUSION@#The CAD and SLM processes affected the fit of CoCr crowns and varied based on the preparation designs. Typically, the shoulder-lip and sharp line angle designs had a more significant effect on crown fit. However, the differences between the design groups were relatively small, especially when compared to fit discrepancies observed clinically.

Effect of sclerostin on the functions and related mechanisms of cementoblasts under mechanical stress / 华西口腔医学杂志

OBJECTIVE@#The purpose of this study is to investigate the potential effects of sclerostin (SOST) on the biological funtions and related mechanisms of cementoblasts under mechanical stress.@*METHODS@#OCCM-30 cells were treated with varying doses of SOST (0, 25, 50, and 100 ng·mL⁻¹) and were loaded with uniaxial compressive stress (2 000 μ strain with a frequency of 0.5 Hz) for six hours. Western blot was utilized to detect the expressions of β-catenin, p-smad1/5/8, and smad1/5/8 proteins. Alkaline phosphatase (ALP) activity was determined, and reverse transcription polymerase chain reaction was used to measure the expressions of runt-related transcription factor 2 (Runx-2), osteocalcin (OCN), bone sialoproteins (BSP), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) mRNA.@*RESULTS@#The expression of p-smad
1/5/8 was significantly downregulated with increasing SOST. β-catenin and smad1/5/8 exhibited no difference. ALP activity decreased under mechanical compressive stress with increasing SOST concentrations. Runx-2 expression was reduced with increasing SOST concentrations, and a similar trend was observed for the BSP and OCN expressions. When the SOST concentration was enhanced, RANKL expression gradually increased, whereas the expression of OPG decreased.@*CONCLUSIONS@#Under mechanical comprehensive stress, SOST can adjust the bone morphogenetic protein (BMP) /smad signal pathway. Osteosclerosis inhibits the mineralization of cementoblasts under mechanical compressive stress, which may be achieved by inhibiting the expressions of osteogenesis factors (Runx2, OCN, BSP, and others) and by promoting the ratio of cementoclast-related factors (RANKL/OPG) through BMP signal pathways.

Effect of Quercetin on the Cell Cycle and Adhesion Molecules of NOD/SCID Mice with Acute B Lymphocytic Leukemia / 中国实验血液学杂志

OBJECTIVE@#To investigate the effect of Quercetin on cell cycle and adhesive molecules of NOD.SCID mice with acule B lymphocytic leuaemia(B-ALL).@*METHODS@#5×10 Nalm-6(B-ALL cell line) cells were injected into the tail vein of 48 NOD/SCID mice to establish the NOD/SCID mice with B-ALL. After 15 day, the NOD/SCID mice with B-ALL were randomly divided into 3 groups: salive group as control (injection with saline of 0.2 ml/mouse), cyclophos-phamid group (injection with cyclophosphamide of 100µg/kg) and quercetin group(injection with quercetin of 3 mg/kg). After treatment for 21 d, the perecntage of Nalm-6 cells in G1, G2, M and S phases was detected by flow cytonetry; the B lymphocytes Nalm-6 cells, neutrophils and WBC in while blood were counted before and after treatment; the expression of intercellalar. Adhesion molecole-1(FCAIU-1), vascular cell adhesion molecule-1(VCAM-1) and P-selectin was detected by double autibody soundwich method.@*RESULTS@#Compared with level before treatment, the expression of ICAM-1, VCAM-1 and P-selectin decreased after treatment with guercetin, The hemogram showed that the peripheral blood nentrophil level obviously increased, while the levels of B lymphocytes, Nalm-6 cells and WBC count decreased obviously after treatment with guercetin. The cell proliferatim rario in G0/G1 phase decreased, yet the cell proliferation ratio in S and G2/M phases increased after treatment with guercetin.@*CONCLUSION@#The guercetin can decrease the intercellular adhesion through inhibition of ICAM-1 expression, and arrests Nalm-6 cells in S and G2/M phases. The guercetin has obviously inhibitory effect on B-ALL cells.

Accuracy and reproducibility of 3D digital tooth preparations made by gypsum materials of various colors

PURPOSE: The study aimed to identify the accuracy and reproducibility of preparations made by gypsum materials of various colors using quantitative and semi-quantitative three-dimensional (3D) approach. MATERIALS AND METHODS: A titanium maxillary first molar preparation was created as reference dataset (REF). Silicone impressions were duplicated from REF and randomized into 6 groups (n=8). Gypsum preparations were formed and grouped according to the color of gypsum materials, and light-scanned to obtain prepared datasets (PRE). Then, in terms of accuracy, PRE were superimposed on REF using the best-fit-algorithm and PRE underwent intragroup pairwise best-fit alignment for assessing reproducibility. Root mean square deviation (RMSD) and degrees of similarity (DS) were computed and analyzed with SPSS 20.0 statistical software (α=.05). RESULTS: In terms of accuracy, PREs in 3D directions were increased in the 6 color groups (from 19.38 to 20.88 µm), of which the marginal and internal variations ranged 51.36 – 58.26 µm and 18.33 – 20.04 µm, respectively. On the other hand, RMSD value and DS-scores did not show significant differences among groups. Regarding reproducibility, both RMSD and DS-scores showed statistically significant differences among groups, while RMSD values of the 6 color groups were less than 5 µm, of which blue color group was the smallest (3.27 ± 0.24 µm) and white color group was the largest (4.24 ± 0.36 µm). These results were consistent with the DS data. CONCLUSION: The 3D volume of the PREs was predisposed towards an increase during digitalization, which was unaffected by gypsum color. Furthermore, the reproducibility of digitalizing scanning differed negligibly among different gypsum colors, especially in comparison to clinically observed discrepancies.

Mandibular condensability and length contraction: an animal experimental study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the condensability of mandibular length.</p><p><b>METHODS</b>In six goats were used in the study. Corticotomy at right mandibular angles was performed via extral-oral accession. Special devices were applied to shorten the mandible by 0.5 mm per three days respectively.</p><p><b>RESULTS</b>1. Mandibular angles of the six goats were shorten by 0.8 cm to 1.3 cm respectively in 48 days to 78 days; 2. In spite of the lower ascending ramus moving forward and angles being blunt, the occlusion scarcely varied because of contralateral bite-lock; 3. X-ray demonstrated that, at first, bone density in contracted areas declined, and then increased gradually to almost normal density; 4. Under microscope there were three tissues layers from central to lateral within the bone gap: fiber layer, cartilage layer and bone layer, and fiber layer gradually transform into cartilage layer with the fixed time. At the end of fixation they all transform into bone tissue.</p><p><b>CONCLUSION</b>Contraction osteogenesis is actually a process of compression, absorption and rebuilding. It is feasible that using contraction osteogenesis to shorten the mandible via cortcotomy.</p>