When You Need a Filling… Pain in the tooth, including tooth aches, throbbing pains and sharp pains. Pain or sensitivity in the tooth when you touch it or put pressure on it (e.g. when eating, brushing) A visible hole in the tooth or mark that might indicate a hole exists. Why would you need a filling? Tooth fillings help dentists repair cavities, so they don't become bigger dental problems down the road. Fillings can fill small holes caused by tooth decay, but they can also repair cracks and fractures in teeth.