Dental educations in China and USA have different histories and systems even if they are similar in some respects.In this paper,by taking school of dental medicine in Harvard university as an example,dental educations in China and USA were compared with each other concerning the enrollment requirement,school system,course arrangement,teaching methods,clinical practice,elc.Based on the comparison,advices on how to improve and reform our dental education system were provided by learning from the advantages of dental education in USA.

Objective: To evaluate the effect of pure titanium modified by bioadhesive RGD peptide on the early attachment, growth and proliferation of osteoblasts. Methods: The titanium samples were hydroxylated by alkali/hot water aging and sol-gel layer-by-layer deposition technique. Afterwards, the terminal -NH_2 group was introduced to the titanium surface by organosilane APTMS self-assembled monolayers and the functional group -NH_2 was further reacted with EDC/NHS by which RGD peptides was covalently immobilized to titanium. The efficiency of this bioreactive surface in promoting cell attachment and the competitive inhibition effect of RGD peptide with different concentrations were observed by calculating the amount of osteoblasts attached on the modified titanium. The growth and proliferation were observed by MTT method and scanning electronic microscopy. Results: The cell adhesion percentage of the RGD modified titanium group was much higher than that of the other groups. The RGD peptide solutions with higher concentration had stronger inhibitory impact on the cell adhesion onto the titanium surface. The cell growth, morphology and proliferation on the RGD peptide modified titanium were better than other groups. Conclusion: Bioadhesive peptide can be chemically grafted onto the titanium surface by means of self-assembled monolayers technique. The cells′ biological behaviors on the surface of RGD immobilized titanium are greatly improved in vitro.

Continuing advances in dentin bonding technology and adhesives revolutionized bonding of resin-based composite restorations. However, hybrid layers created by contemporary dentin adhesives present imperfect durability, and degradation of collagen matrix by endogenous enzymes is a significant factor causing destruction of hybrid layers. Bond durability can be improved by using enzyme inhibitors to prevent collagen degradation and to preserve integrity of collagen matrix. This review summarizes progress on matrix metalloproteinase inhibitors (including chlorhexidine, ethylenediaminetetraacetic acid, quaternary ammonium salt, tetracycline and its derivatives, hydroxamic acid inhibitors, bisphosphonate derivative, and cross-linking agents) and suggests prospects for these compounds.
Acid Etching, Dental ; Bisphenol A-Glycidyl Methacrylate ; Collagen ; Dental Bonding ; Dentin ; Dentin-Bonding Agents ; Humans ; Matrix Metalloproteinase 2 ; Matrix Metalloproteinase Inhibitors

BACKGROUND:Bone is a remarkable natural material possessing piezoelectric properties.By harnessing the biomimetic piezoelectric effect,tissue engineering materials can be employed to effectively address bone tissue defects and facilitate their repair. OBJECTIVE:Using a solid-phase force chemistry technique,a piezoelectric scaffold with inherent osteogenic properties was meticulously fabricated.This unique scaffold was then assessed for its impact on osteoblast adhesion,proliferation,and osteogenic differentiation. METHODS:Polyvinylidene fluoride(PVDF)powders,along with commercially available NaCl(mass ratios are 60:40,50:50,40:60,and 30:70,respectively),were subjected to solid-phase shear milling technology,resulting in a homogenous mixture.Through a melting process,a substantial material was formed,and subsequent treatment with a pure water solution effectively eliminated the NaCl.Consequently,PVDF piezoelectric foam scaffolds with varying pore sizes were successfully prepared.These materials were categorized as PVDF-40,PVDF-50,PVDF-60,and PVDF-70,denoting the respective mass percentages of NaCl during preparation.The surface morphology,crystal phase composition,thermodynamic behavior,mechanical properties,and piezoelectric properties of each group were meticulously characterized.The four kinds of piezoelectric foam scaffolds were co-cultured with the MG63 osteoblast cell line to evaluate its biocompatibility and potential to promote bone differentiation. RESULTS AND CONCLUSION:(1)The scanning electron microscopy,four groups of scaffolds had multi-level pores.As the NaCl mass fraction in the mixed powder increased,the porosity of the scaffolds increased.X-ray energy dispersion spectrum,X-ray diffraction,Fourier transform infrared spectroscopy,and thermogravimetric analysis collectively revealed the scaffold predominantly comprised the α phase,which inherently lacked piezoelectric properties.However,the application of solid-phase force chemistry successfully stimulated the formation of the β phase,thereby enhancing the scaffold's piezoelectric properties.Notably,the PVDF-60 group exhibited the highest proportion of the β phase among all the tested groups.The results of cyclic compression testing and piezoelectric performance assessment demonstrated that the PVDF-60 group exhibited superior compressive strength and piezoelectric performance compared to the other groups.(2)The findings from scanning electron microscopy and laser confocal microscopy exhibited that MG63 cells adhered well to the surface of the four groups of scaffolds,with good morphology,extended more pseudopods,and secreted a large amount of extracellular matrix.CCK-8 assay revealed that the proliferative absorbance of PVDF-60 cells cultured for 4 days was higher than that of the other three groups(P<0.000 1).Alkaline phosphatase staining and alizarin red staining showed that the expression of alkaline phosphatase and the number of calcified nodules in the PVDF-60 group were higher than those in the other three groups(P<0.01,P<0.000 1).(3)The piezoelectric PVDF foam-based scaffolds demonstrated favorable cytocompatibility.Notably,the PVDF-60 group showed superior mechanical properties,piezoelectric performance,and bone-inducing capabilities.

The problems caused by proximal contact loss (PCL) of dental implants have been a mainstream research topic in recent years, and scholars are unanimously committed to analyzing their causes and related factors, aiming to identify solutions to the problems related to PCL. The effects of the anterior component of force (ACF), the lifelong remolding of the adult craniofacial jaw and alveolar socket, and the osseointegration characteristics of dental implants are the main causes of PCL. On the one hand, the closing movement of the mandible causes the ACF of the tooth to move through the posterior molar cusp. Moreover, drifting between the upper and lower posterior teeth and mandibular anterior teeth can cause the anterior teeth of the upper and lower jaws to be displaced labially. On the other hand, reconstruction of the jaw, alveolar socket and tooth root, the forward horizontal force of the masticatory muscles, the dynamic component of the jaw and the forward force generated by the oblique plane of the tooth cusp can cause the natural tooth to experience near-middle drift. Additionally, natural teeth can shift horizontally and vertically and rotate to accommodate remodeling of the stomatognathic system and maintain oral function. Nevertheless, the lack of a natural periodontal membrane during implant osseointegration, the lack of a physiological basis for near-medium drift, the small average degree of vertical motion and the integrated silence of dental implants without the overall drift characteristics of natural teeth increases the probability of PCL. The high incidence of PCL is clearly associated with the duration of prosthesis delivery and the mesial position; but it is also affected by the magnitude of the bite force, occlusion, the adjacent teeth, restoration design, implant location, jaw, and patient age and sex. PCL has shown a significant correlation with food impaction, but not a one-to-one correspondence, and did not meet the necessary and sufficient conditions. PCL is also associated with peri-implant lesions as well as dental caries. PCL prevention included informed consent, regular examinations, selection of retention options, point of contact enhancement, occlusal splints, and the application of multipurpose digital crowns. Management of the PCL includes adjacent contact point additions, orthodontic traction, and occlusal adjustment. Existing methods can solve the problem of food impaction in the short term with comprehensive intervention to seek stable, long-term effects. Symmetric and balanced considerations will expand the treatment of issues caused by PCL.