Sayyiduna Ali (may Allah be pleased with him) said: If part of a tooth is broken, the diyah will be given to its owner in proportion to what was broken, and then it will be left for one year. If it turns completely black, there will be the full diyah; otherwise there will be nothing more.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16271