ABSTRACT
Objective To compare the bonding strength of different adhesives to the enamel of mild, moderate and severe dental fluorosis with tensile bonding strength, and to provide the experimental foundation for choosing different adhesives for different degrees of dental fluorosis in clinical practice. Methods At the Affiliated Hospital of Inner Mongolia Medical University, according to the Dean classification standards, one hundred-eighty extracted caries-free and whole human premolars of dental fluorosis were divided into three groups with mild, moderate and severe degree,60 teeth in each group.Each group was divided into two subgroups by random number table method,30 teeth in each subgroup.The emery was used to remove enamel surface 0.5 mm,and then two kinds of bonding adhesives(all-etching adhesive prime&bond NT,self-etching adhesive SE-BOND) were used to bond, pressurized layered composite resin Z350 curing, kept in 37 ℃ distilled water for 24 h. The bonding strength was tested at universal material testing machine, and fracture interface was observated using scanning electron microscope. Results All-etching adhesive had statistical significant influence on the tensile strength of mild, moderate and severe dental fluorosis[(7.82 ± 4.20),(4.79 ± 2.69),(5.04 ± 2.81)MPa,F=4.610,P<0.05], and the tensile strength of mild dental fluorosis was the largest (P < 0.05), the tensile strength between moderate and severe dental fluorosis was not significantly different (P > 0.05). The effect of self-etching adhesive on the tensile strength of mild, moderate and severe dental fluorosis was not statistically significant (F = 0.393, P >0.05). The effect of all-etching adhesive on the tensile strength of mild dental fluorosis was stronger than that of self-etching adhesive(t = 2.197, P < 0.05). Under the scanning electron microscope,the enamel bonding surface of mild dental fluorosis was relatively uniform and compact,with a small amount of crystal disorder,crystal gap slightly widened; the enamel bonding surface of severe dental fluorosis lost seriously enamel, even some of the dentinal tubules exposed, with enamel relatively loose and non uniform, crystal disordered and crystal gap widened significantly, less number of enamel rod. Moderate dental fluorosis was similar to severe dental fluorosis; enamel stripping also occurred under the action of the pulling force but was slighter than severe dental fluorosis enamel. Conclusions ①The effect of all-etching adhesive on the tensile strength of mild dental fluorosis is stronger than that of self-etching adhesive. ②The effect of all-etching adhesive on the tensile strength of mild dental fluorosis is the biggest,there is no statistical significant difference between moderate and severe dental fluorosis.
ABSTRACT
Mitochondria regulate numerous crucial cell processes, including energy production, apoptotic cell death, oxidative stress, calcium homeostasis and lipid metabolism. Here, we applied an efficient mitochondria-based centrifugal ultrafiltration/liquid chromatography/mass spectrometry (LC/MS) method,also known as screening method for mitochondria-targeted bioactive constituents (SM-MBC). This method allowed searching natural mitochondria-targeting compounds from traditional Chinese medicines(TCMs), including Puerariae Radix (PR) and Chuanxiong Radix (CR). A total of 23 active compounds were successfully discovered from the two TCMs extracts. Among these 23 hit compounds, 17 were identified by LC/MS, 12 of which were novel mitochondria-targeting compounds. Among these, 6 active compounds were analyzed in vitro for pharmacological tests and found able to affect mitochondrial functions. We also investigated the effects of the hit compounds on HepG2 cell proliferation and on loss of cardiomyocyte viability induced by hypoxia/reoxygenation injury. The results obtained are useful for in-depth understanding of mechanisms underlying TCMs therapeutic effects at mitochondria level and for developing novel potential drugs using TCMs as lead compounds. Finally, we showed that SM-MBC was an efficient protocol for the rapid screening of mitochondria-targeting constituents from complex samples such as PR and CR extracts.