Despite progress in the decrease of caries by means of many preventive dental programs, children's teeth of poor socio-economic groups are still strongly affected. The well known role of children's teeth in oro-facial growth and harmony, as well as in the development of functions as chewing, speaking or phonation and swallowing, has justified their preservation during all their functional periods. Several conservative therapies allow to reach this purpose. However, extensive dental caries, difficulty to get child tooth infection under control, injuries on permanent tooth germs and child's general health deficiency, can limit preservation of infected teeth, leading to their extraction.