Virtual versus jaw simulation in Oral implant education: a randomized controlled trial.

BACKGROUND: This research aims to investigate the evaluation methods of teaching oral implant clinical courses and estimate the effectiveness of a virtual simulation platform. METHODS: Eighty second- and third-year undergraduates in Lanzhou University were recruited and randomized to either three experimental groups or one control group. The subjects undertook theoretical examinations to test their basic level of knowledge after training in similarly unified knowledge courses. Each student group then participated in an eight-hour operating training session. An operation test on pig mandible was conducted, followed by a second theoretical examination. The assessment consists of three distinct parts: a subjective operating score by a clinical senior teacher, an implant accuracy analysis in cone-beam computed tomography (angular, apical, and entrance deviation), and comparison of the two theoretical examinations. Finally, students completed a questionnaire gauging their understanding of the virtual simulation. RESULTS: There was no significant difference between the four groups in first theoretical examination (P > 0.05); the second theoretical scores of the V-J and J-V group (62.90 ± 3.70, 60.05 ± 2.73) were significantly higher than the first time (57.05 ± 3.92, P < 0.05), while no difference between the V (57.10 ± 3.66) and J (56.89 ± 2.67) groups was found. Thus, the combination of V-J was effective in improving students' theoretical scores. The V-J and J-V groups had higher scores on operation (73.98 ± 4.58, 71.85 ± 4.67) and showed better implant precision. CONCLUSION: Virtual simulation education, especially with a jaw simulation model, could improve students' implantology achievements and training. Currently study found that the V-J group may performed better than the J-V group in oral implant teaching.

A review of microplastic transport in coastal zones.

Transport of microplastics (MPs) in coastal zones is influenced not only by their own characteristics, but also by the hydrodynamic conditions and coastal environment. In this article, we first summarized the source, distribution and abundance of MPs in coastal zones around the world through the induction of in-situ observation literature, and then comprehensively reviewed the different transports of MPs in coastal zones, including sedimentation, vertical mixing, resuspension, drift and biofouling. Afterwards, we conducted a comparative analysis of relevant experimental literature, and found that the current experimental research on microplastic transport mainly focused on the settling velocity under static water and the transport distribution under dynamic water. Based on the relevant literature on numerical simulation of microplastic transport in coastal zones, it was also found that the Euler-Lagrange method is the most widely used. The main influencing factor in the Euler method is hydrodynamic, while the Lagrange method and Euler-Lagrange method is hydrodynamic and microplastic particle characteristics. Tides in hydrodynamics are mentioned the most frequently, and the role of turbulence in almost all the literature. The density of MPs is the most influencing factor on transport results, followed by size, while shape is only studied in small-scale models. Some literature has also found that the influence of biofilms is mainly reflected in the changes in the density and size of MPs.

Clinical and radiographic performance of one-piece and two-piece implant:a systematic review and meta-analysis.

PURPOSE: The aim of this system review was to evaluate clinical and radiographic performance of one-piece implant (OPI) and two-piece implant (TPI). METHODS: Electronic database searches were performed in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and OpenGrey databases up to May 2019. Two authors individually screened the related literatures according to the inclusion and exclusion criteria. Main clinical outcomes included failure and complication rates. Radiographic outcomes were peri-implant bone loss between baseline and last available follow-up. RESULTS: Finally, 11 articles reporting 10 different studies were included in this review. No statistically significant difference (P = 0.22) in risk of failure was found between the two types of implants (RR: 0.49, 95% CI: 0.16-1.53). Peri-implantitis accounted for most failures and complications and there was no statistically significant difference in risk of peri-implantitis no matter after 1 year follow-up (RR: 1.15, 95% CI: 0.37-3.53, P = 0.81) or at 2-3 years (RR: 1.95, 95% CI: 0.23-16.63, P = 0.54). With regard to the marginal bone loss (MBL) around implants, subgroup meta-analysis by platform switching versus platform matching showed a significant MBL-reducing effect for TPI when compared to OPI (WMD: 0.21mm, 95% CI: 0.07-0.36mm, P = 0.004) in the platform-switching subgroup, while no significant difference in MBL was observed between the two groups in the platform-matching subgroup (P = 0.67). CONCLUSIONS: The results of this review suggested that OPI and TPI showed similar short-term survival rates and incidences of complications. Nevertheless, TPI with platform switching may be a better option to reduce peri-implant bone loss.

[Effect of orthodontic traction on the microstructure of dental enamel].

OBJECTIVE: To investigate the effect of orthodontic traction on the microstructure of dental enamel. METHODS: Forty-eight isolated premolars were randomly divided into 6 groups (n=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome. RESULTS: Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2. CONCLUSIONS: Orthodontic traction can cause changes in the microstructure of normal dental enamel.