Effects of different energy density low-level laser therapies for temporomandibular joint disorders patients: a systematic review and network meta-analysis of parallel randomized controlled trials.

PURPOSE: To compare the effects of different energy density LLLT on TMD patients' pain reduction. METHODS: Reviewers searched RCTs published in Embase, PubMed and The Cochrane Library before 1 April 2020. Reviewers included parallelRCTs that compared the effects of LLLT with placebo or different energy density LLLT for TMD patients' pain reduction. Reviewers did network meta-analysis and evaluated the quality of evidence using the GRADE process. RESULTS: From 352 studies, reviewers included 16 RCTs. Immediately after treatment, the d1 laser therapy (energy density ranging from 0 to 10 J/cm2) ranked first. The d1 laser therapy showed more pain reduction than placebo ( MD = 2.49, 95% CI ranging from 1.28 to 3.71). The quality of "d1 vs p" comparison was assessed as "moderate" quality. A month after treatment, the d1 laser therapy also performed better than placebo (MD = 1.69, 95%CI = [-0.78, 4.16]). The quality of secondary outcome was assessed as "low" quality. CONCLUSIONS: For clinical application, d1 laser therapy (energy density ranging from 0 to 10 J/cm2) is recommended for short-term pain management of TMD patients (moderate quality evidence). A month after treatment, the d1 laser therapy also performed better than placebo and other laser groups but the result didn't reach the point of statistical significance (low quality evidence). TRIAL REGISTRATION: PROSPERO-CRD42018118313.

Effect of Fiber Mass Fraction on Microstructure and Properties of 2D CF-GO/EP Composite Prepared by VIHPS.

Graphene is often used to improve interlaminar fracture toughness of carbon fiber/epoxy resin (CF/EP) composites. It is still a challenge to improve the toughness while maintaining the in-layer properties. In this study, 2D graphene oxide carbon fiber reinforced epoxy resin matrix (2D CF-GO/EP) composites were prepared by a vacuum infiltration hot-press forming experimental system (VIHPS), and three-point flexural and end notch flexural (ENF) tests were carried out. With the increase of the fiber mass fraction in the composites, the mode II interlaminar fracture toughness (GIIC) layers decrease gradually, and the bond property between the fiber and matrix interface layer becomes worse, because the accumulation of dense fiber bundles reduces the matrix penetration ability of cracks. However, the flexural properties increased first and then decreased, and reached the best flexural properties at 64.9%. When the fiber mass fraction is too high, the interlamellar bonding properties will decrease, and the fiber bundles will compress and affect each other. The delamination phenomenon will occur between the layers of the composites, which affects the overall bearing strength and stress limit of the composites. The results of the study show that the composites prepared by VIHPS have excellent mechanical properties, and the content of carbon fiber plays an important role in the influencing factors of the interlaminar and in-layer properties of composites.

Effectiveness of modifications to preadjusted appliance prescriptions based on racial dental characteristics assessed by the ABO Cast-Radiograph Evaluation: A propensity score matching study.

BACKGROUND: Because racial discrepancies in dental characteristics are known to exist, designing preadjusted appliances according to racial normal occlusion data would be expected to improve treatment results. However, whether modifications based on racial characteristics can improve treatment outcomes in the clinic remains to be investigated. METHODS: To study the influence of prescription type on treatment outcomes, 91 patients treated with Chinese or Roth prescription appliances were selected as an initial sample. Two groups of patients were selected by propensity score matching (1:1) to limit the effects of confounding factors, including age, sex, case complexity, and extraction plan. Discrepancy Index and cervical vertebral maturation values were used to quantify case complexity and patient age, respectively. After matching, the final sample of 60 patients consisted of two groups of 30 patients each: group 1 had been treated with a Chinese prescription appliance and group 2 had been treated with a Roth prescription appliance. ABO casts and radiograph evaluation (CR-Eval) and lateral cephalograms were utilized to compare the treatment outcomes of the two groups. RESULTS: The total ABO scores of groups 1 and 2 were 22.03 and 23.87, respectively. There were no significant differences between the two groups in total ABO score or in seven other sub-scores; however, there was a significant difference between the two groups in mandibular canine alignment score. CONCLUSIONS: There are no significant differences in overall treatment outcomes between the Chinese and Roth prescription appliances. The Chinese prescription yielded better alignment results in the mandibular canine for Chinese patients.

A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite.

In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 ℃, vacuum heating curing at -0.05 MPa + 30 min + 80 ℃, and hot-press curing at 0.7 MPa + 5 min + 50 ℃, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.

IMCs Microstructure Evolution Dependence of Mechanical Properties for Ni/Sn/Ni Micro Solder-Joints.

The current miniaturization trend of microelectronic devices drives the size of solder joints to continually scale down. The miniaturized joints considerably increase intermetallic compounds (IMCs) volume fraction to trigger mechanical reliability issues. This study investigated precise relationships between varying IMC volumes and mechanical properties of Ni/Sn(20µm)/Ni micro-joints. A designed method that followed the IMC volume as the only variable was used to prepare micro-joint samples with different IMC volumes. The continuously thickened Ni3Sn4 IMCs exhibited a noticeable morphology evolution from rod-like to chunky shape. The subsequent tensile tests showed unexpected tensile strength responses as increasing Ni3Sn4 volume, which was strongly associated with the Ni3Sn4 morphological evolutions. Fractographic analysis displayed that the ductile fracture dominates the 20%-40% IMC micro-joints, whereas the brittle fracture governs the 40%-80% IMC micro-joints. For the ductile fracture-dominated joints, an abnormal reduction in strength occurred as increasing IMCs volume from 20% to 40%. This is primarily due to severe stress concentrations caused by the transformed long rod-typed morphology of the Ni3Sn4. For the brittle fracture-dominated joints, the strength appeared a monotonous increase as the Ni3Sn4 volume increased. This may be attributed to the increased crack resistance resulting from continuous coarsening of the chunky Ni3Sn4 without any voids. Moreover, the finite element analysis was provided to further understand the joint failure mechanisms.

Influence of Infiltration Pressure on the Microstructure and Properties of 2D-CFRP Prepared by the Vacuum Infiltration Hot Pressing Molding Process.

The critical infiltration pressures of the matrix in a two-dimensional (2D) carbon fiber preform were calculated theoretically, and the calculated values of the static and dynamic models were 0.115 and 0.478 MPa, respectively. Compared with the dynamic model, there is no viscous resistance or infiltration front gas pressure in the static model, so the static value is obviously lower than the dynamic value. To verify the rationality of theoretical calculation, 2D carbon fiber reinforced plastics (2D-CFRP) with infiltration pressures of 0.5, 0.6, 0.7, 0.8, and 0.9 MPa were prepared by the vacuum infiltration hot pressing molding process. The microstructure of the composite was observed and the bending strength was tested by three-point bending test. The results show that the infiltration pressure has an important influence on the infiltration effect and the bending fracture morphology. When the infiltration pressure is 0.7 MPa, the composite has an excellent infiltration effect. The fibers distribute reasonable in the fracture. Stress can be effectively transferred when the composite material is loaded. And the bending strength of the composite material reaches 627 MPa at this time.