Search

Objective: The purpose of this study was to assess the associations between the self‐reported oral health‐related quality of life (OHRQoL) of older Chinese people and their socio‐economic status and oral health using data collected in the 4th National Oral Health Survey. Methods: After multistage stratified cluster sampling, 4332 adults aged 65‐74 years participated in the study. After a clinical examination, the participants completed a structured questionnaire. A Mandarin version of the General Oral Health Assessment Index (GOHAI) was included in the questionnaire. Clinical examinations were carried out using the criteria recommended by the World Health Organization. Multivariate analysis was used to evaluate the associations of the clinical and socio‐demographic variables with the GOHAI scores of the participants. Results: The weighted mean (SE) GOHAI score was 51.6 (0.0). Female sex and having more than 10 missing teeth, unrestored tooth spaces, more than 10 decayed teeth and a periodontal pocket ≥6 mm were negatively associated with the GOHAI score, while having a higher education level and living in the Eastern region of China were positively associated with the GOHAI score. Conclusion: After adjustment for confounders, the OHRQoL of older Chinese individuals was mainly affected by untreated dental caries and the loss of teeth. Older Chinese individuals who were male, had a higher education level, were from the Eastern region, had no unrestored tooth spaces or deep periodontal pockets and had fewer decayed or missing teeth had higher GOHAI scores, indicating better OHRQoL. [ABSTRACT FROM AUTHOR]

The supersonic jet characteristics of the oxygen lance nozzle play an important role in converter melting. However, limited studies have investigated the different nozzle arrangements to improve the jet characteristics. This study uses FLUENT to establish a compressible nonisothermal computational fluid model with a 250 t converter as the object, and the model first validates and then discusses the effects of the center hole and postcombustion (PC) oxygen lance secondary hole on the aggregation behavior and impact area of the oxygen jet based on the conventional five‐hole oxygen lance. The study shows that, at the same distance, the influence of the peripheral jet offset degree from small to large is secondary hole–center hole–secondary hole with center hole. At the lance height of 1900 mm, compared to the traditional five‐hole oxygen lance offset theoretical axial centerline distance is 1.98, 2.31, and 3.20 times. The larger the jet migration degree of the peripheral hole, the smaller is the velocity of the peripheral jet. The presence of center hole, secondary hole, and center hole with secondary hole encloses 1.04, 1.09, and 1.47 times the area enclosed by the conventional five‐hole oxygen lance at 150 m s−1 isovelocity line, respectively. [ABSTRACT FROM AUTHOR]

The flow characteristics and postcombustion behavior of a single‐flow postcombustion (PC) oxygen lance are of paramount significance to optimal design and operation of the lance but not well understood, and there is also no well‐known design criterion for the optimization of the single‐flow PC lance. Herein, the design criteria of a single‐flow PC lance are first proposed. Then, a 3D fluid model is established combined with a 120 t top‐blown converter. The influences of the key parameters of secondary nozzles (i.e., inclination angle, diameter, and number) on the jet characteristics and PC behavior at the steelmaking temperature are studied. Finally, based on the design criteria, an optimal PC lance is designed and its smelting effect is compared with that of the conventional lance by industrial tests. The results indicate that the reasonably designed PC lance can effectively improve the PC zone of CO gas and simultaneously increase both the penetration depth and impact area of the main jet. Compared with conventional lance, the PC oxygen lance can raise the temperature of molten steel by ≈30 °C and reduce the total fe (T.Fe) content in the final slag by 0.86%. Moreover, it has almost no effect on the gas recovery. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-23-584/coif). The authors report that this work was supported by grant from the New Clinical Technology Project Foundation of the Southwest Hospital, Third Military Medical University (No. SWH2016JSTSYB-50). The authors have no other conflicts of interest to declare.

Objective: To evaluate the effects of powered and manual tooth brushing on gingival inflammation in a Chinese population with mild to moderate gingivitis., Methods: The present randomised, single-blind, parallel clinical trial was conducted in five cities in China. Generally healthy participants aged 18 to 65 years, who were non-smokers and had at least 20 sites of gingival bleeding, were included as eligible subjects. The subjects were randomly assigned to either the powered tooth brushing (PTB) group or standard manual tooth brushing (MTB) group. All subjects were supplied with a fluoride-containing toothpaste, Gingival Bleeding Index (GBI), Modified Gingival Index (MGI) and the Turesky modification of the Quigley-Hein Plaque Index (MPI) were used to evaluate the outcomes., Results: A total of 235 subjects completed the study, 118 in the PTB group and 117 in the MTB group. The mean age and sex distribution for the PTB and MTB groups were 34.40 ± 9.99 years, 89 women and 29 men, and 34.20 ± 10.14 years, 82 women and 35 men, respectively. After 6 months, the percentage decrease in MGI was 26.150% ± 26.897% for the PTB group and 14.768% ± 38.544% for the MTB group (P = 0.0092). Statistically significant differences between types of tooth brushing were also observed at 6 months for GBI, and at all time points for MPI., Conclusion: Tooth brushing with a powered toothbrush twice a day was shown to be more effective than use of a manual toothbrush in reducing gingival inflammation, gingival bleeding and surface plaque after a 6-month period. Both kinds of toothbrushes were safe for the oral tissues.