如果中国在人均二氧化碳排放量上向美国看齐的话，世界将遭受难以修补的损害。
If China were to follow the American model in terms of per capita carbon emissions, the world would be damaged beyond repair.
目的观察采用三氧化矿物凝聚体（MTA）修补根管穿孔的短期临床效果。
Objective To observe short-term clinical effect of root perforation repair using mineral trioxide aggregate(MTA).
目的探讨DMG光固化氢氧化钙修补前牙陈旧性根管穿孔的临床效果及可行性。
Objective To discuss the clinical effects and feasibility of repairing old root canal perforation of front teeth using DMG calcium hydroxide.
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