OBJECTIVETo study the influence of three kinds of retainers on the abutment movement of removable partial dentures (RPDs) for restoring the dentition with unilateral distal-extended tooth missing.

METHODSThe combined clasp, the extension clasp and the telescopic crown were designed to retain RPDs. When food chip was masticated between dentitions, the displacement of abutments was measured by a high-sensitive-laser-transferring-detector, and then the data was statistically analyzed.

RESULTSAll of abutments showed the inclination, torsion and vertical translocation. Of them, abutments with telescopic crowns had the lowest horizontal torsion (P < 0.01) and the highest vertical translocation (P < 0.01).

CONCLUSIONSCompared with the combined clasp and the extension clasp, the telescopic crowns enable abutments to bear the load more axial and the stress to be distributed more even, so the design of the telescopic crown may be considered more favourable for the health of abutments.

Crowns ; Dental Abutments ; Dental Clasps ; Dental Stress Analysis ; methods ; Denture Retention ; instrumentation ; methods ; Denture, Partial, Removable ; Humans ; Tooth Movement Techniques

Objective:To investigate mucosal injury after high-dose methotrexate (HD-MTX) chemotherapy in treatment of children with acute lymphoblastic leukemia (ALL), and to analyze the association with methotrexate blood concentration, risk stratification and clinical efficacy.Methods:The data of 95 children with ALL who received 539 times of HD-MTX chemotherapy in the First Hospital of Harbin from November 2015 to October 2018 were retrospectively analyzed, and the association of mucosal injury with methotrexate blood concentration, disease risk degree and clinical efficacy was also analyzed.Results:Among 95 children who received 539 times of HD-MTX chemotherapy, the total incidence of mucosal injury was 8.4% (45/539); the incidence of mucosal injury was 4.6% (11/239), 7.6% (8/105), 13.3% (26/195), respectively in the low-risk group, middle-risk group and high-risk group. With the elevation of disease risk, the incidence of mucosal injury was increased ( χ2 = 10.787, P < 0.05). There was no correlation of the degree of mucosal injury with methotrexate blood concentration and disease risk degree (all P > 0.05), and the mucosal injury was not related with the clinical efficacy ( P > 0.05). Conclusion:After the application of HD-MTX in children with ALL, adjustment of the dose of rescue drug by monitoring of methotrexate blood concentration can improve the safety of therapeutic drugs.

Objective:To explore the therapeutic effect of low-dose arsenous acid/tretinoin with or without low-dose cytarabine induction regimen on myelodysplastic syndromes (MDS) with TET2 gene mutation in children.Methods:Nine children with MDS who were hospitalized at the First Hospital of Harbin from March 2009 to April 2018 were collected, including 3 cases of refractory cytopenia of childhood (RCC), 4 cases of MDS with excess of blasts type Ⅰ (MDS-EBⅠ) and 2 cases of MDS with excess of blasts type Ⅱ (MDS-EBⅡ). The next-generation gene sequencing method (NGS) was applied to detect the TET2 gene mutation in bone marrow cells of children with MDS. The low-dose arsenous acid/tretinoin with or without low-dose cytarabine induction regimen was adopted to conduct tiered therapy on children with MDS. The clinical efficacy was assessed in line with the MDS response evaluation criteria adopted by the MDS International Working Group (IWG) in 2006.Results:Among the 9 patients, the short-term clinical efficacy was observed in 8 cases. Two patients with TET2 gene mutation achieved the short-term clinical efficacy of bone marrow complete remission (mCR) and hematological improvement (HI). Among 7 patients without TET2 gene mutation, 4 patients obtained CR, 1 patients obtained mCR and HI, and 1 patients obtained stable disease (SD) in terms of the short-term clinical efficacy.Conclusion:The low-dose arsenous acid/tretinoin with or without low-dose cytarabine regimen may be beneficial to MDS children with TET2 gene mutation.