| The air abrasion is one kind of minimally invasive dentistry. It was proposed by Black and cuts by dashing against the dental tissue with high kinetic energy, through a bunch of high-speed aluminum oxide particles. It has some advantages which traditional methods don't have, such as producing less heat, making less noise, no vibration, safety, without anesthesia, as well as to maximize the preservation of teeth, and so on. It's full of important clinical significance to treatment the children who have decayed tooth but with dental fear.Part 1 Investigation of children's dental fearObjective: To investigate the reason and related factors of children's dental fear(DF). Methods: A total of 209 children who came to see dentists were evaluated using clinical ratings of anxiety and comparative behavior evaluation system, and the data statistically analyzed. Results: The survey showed that no significant difference in the incidence of DF between children of different ages, but there was significant difference among children with different sex, different dental experiences. Conclusion: The children's DF was closely related to their ages, dental experiences,pain, turbine engine and so on.Part 2 Microleakage of composite resin restorations in primary molars after preparation with bur or air abrasion. Objective: The aim of this study was to assess microleakage in class I cavities prepared by air abrasion or high-speed dental bur in primary molars and restored with the composite resin.Methods: Thirty primary molars were equally divided into 3 groups. Group I (n=12,the control): preparation by high-speed; group II(n=12): preparation by air abrasion, using 27μm aluminum oxide particles; group III(n=12): preparation by air abrasion, using 50μm aluminum oxide particles. Two primary molars of each group,which one of them was etching,were observed by SEM. Preparations were placed with composite resin. All the primary molars in each group were thermocycled and dye penetration was evaluated in order scale. Results: 1. No significant differences existed between groups I and group II(p>0.05),but a statistical difference between groups I and groups III(p<0.05). 2. The tooth preparated by air abrasion with etching showed characteristic"honeycomb"pattern in SEM-micrograghs. Conclusion: Air abrasion preparation did influence microleakage in class I restorations with the composite resin.Part 3 Microleakage and microtensile bond stregth of different filling materials restorations in primary molars after preparation with air abrasion.Objective: The aim of this study was to assess microleakage and microtensile bond stregth in class I cavities prepared by air abrasion in primary molars and restored with different filling materials.Methods: 1. Group I - III: preparation by air abrasion, using 50μm aluminum oxide particles. Restorations filled with the composite resin, the flowable composites and the light-curing nano-lonomer restorative respectively. All primary molars in each group were thermocycled and dye penetration was evaluated in order scale. 2. GroupⅣ-Ⅴ: Superficial occlusal dentin were abrased with 50μm aluminum oxide particles, and a crown of different crued resin composite bonded . Microtensile testing was used to examine the microtensile bond strength.Results: 1. Statistcal analyses revealed a significant differences(p<0.001)in microleakage amomg three materials.The flowable composites showed the less microleakage compared to others(p<0.05). 2. No significant difference was found in the composite resin group and the flowable composites group(p>0.05). Conclusion: It can be conclued that flowable composites may be recommended to improve the marginal seal of a restoration. |
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