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Caries repair is the most common and the most basic treatment, but caries repair is also a very fine treatment, considering the status of dental (occlusal) force status, hole design, repair material choice and more kinds of factors. Due to various reasons, the caries restorative treatment failure not uncommon. How to improve the success rate of caries reparative therapy, dental caries research hotspot. The experimental composite resin restoration mandibular first molars with class Ⅰ study, through the establishment of a three-dimensional model, using the finite element method quantitative study (occlusal) force, hole-type base, and other factors of tooth structure and fix the size and distribution of body stress, and to analyze the possible damage caused by the tooth structure and restorations. According to research different factors, the experiment is divided into three parts: ① (occlusal) surface of the same model vertical load or lateral 30 ° loading (by the tongue to cheek) 50N, 100N, 150N load, compare different load cases enamel, dentin, prosthesis maximum Von Mises stress and maximum principal stress distribution (2) in six different sizes with class Ⅰ same load is applied, more enamel restoration maximum Von Mises stress and maximum tensile stress distribution. ③ same load is applied to the four different types of base material thickness bottom class Ⅰ more enamel restoration maximum Von Mises stress and the maximum tensile stress distribution. The results showed that: ① vertical load or lateral load conditions, enamel, dentin, prosthesis maximum Von Mises stress and maximum principal stress values ??increase with increasing (occlusal) force. The enamel and the maximum stress value of the prosthesis significantly greater than the maximum stress value of the dentin. Vertical load conditions, enamel, smaller prosthesis stress, compressive stress and uniform distribution of lateral loading (from tongue to cheek) conditions, enamel, uneven distribution of stress prosthesis significantly higher tensile stress in the side of the tongue at the junction of the enamel and restorations. In the repair in vivo, the maximum stress value is located in the prosthesis surface, the more down to smaller stress values. ② In the case of a constant width of the hole type, hole type is the deeper, the greater the enamel, the restoration of the maximum Von Mises stress and the maximum tensile stress value. Similarly, in the case of constant depth of the hole-type, the width of the hole-type increase enamel prosthesis Zhejiang University master's degree thesis maximum Von MiseS stress and maximum tensile stress increased. Hole pattern width, depth, two factors compared to the increase in the width of the hole type of enamel restoration of maximum stress increase greater impact. ③ from the base material, zinc-phosphate cement as a base, enamel, restoration maximum Von Mises stress and maximum tensile stress than glass ionomer cement as a base is smaller and more uniform stress distribution. Substrate thickness, enamel, fix maximum Von Mises stress and the maximum tensile stress decreases with increasing substrate thickness.
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