1. Dried fruits like dates, figs, and raisins, which are rich in concentrated sugars and get stuck to the teeth, have been found to have a similar effect to sticky sweets. The complex subject here is "Dried fruits like dates, figs, and raisins, which are rich in concentrated sugars and get stuck to the teeth." This subject includes the noun "dried fruits" and the subordinate clause "which are rich in concentrated sugars and get stuck to the teeth." 2. Periodontal disease, which results from inflammation of the gum that gradually causes destruction of the bone supporting the teeth, is known. The complex subject here is "Periodontal disease, which results from inflammation of the gum that gradually causes destruction of the bone supporting the teeth." This subject includes the noun "periodontal disease" and the subordinate clause "which results from inflammation of the gum that gradually causes destruction of the bone supporting the teeth." 3. Tooth loss appears to be a result of periodontal disease. The complex subject here is "Tooth loss," which is the result of periodontal disease. 4. Water fluoridation is believed to be the most effective public health strategy for caries prevention. The complex subject here is "Water fluoridation," which is believed to be the most effective public health strategy for caries prevention. 5. Starchy foods that stick to the teeth are likely to cause decay. The complex subject here is "Starchy foods that stick to the teeth," which are likely to cause decay. This subject includes the noun "starchy foods" and the subordinate clause "that stick to the teeth."