[MUSIC] Hello, in this section we are going to discuss several dental diseases that affect the teeth. Let's start with dental caries, which is a term foreknown as cavities. Dental caries is the most common of the dental diseases. Worldwide, approximately 2.4 billion people, or 36% of the population, have dental caries in their permanent teeth. In the US, dental caries is the most common disease of childhood. It is five times more common than asthma. In addition to caries, we're also going to discuss erosion, abrasion, and pulpal conditions. Caries is basically the localized destruction of tissues of the teeth by bacterial fermentation of dietary carbohydrates. It is a chronic androgynous infection that is caused by members of the neural oral flora. The result of the caries process, the caries lesion is a manifestation of the mineralization of enamel, dentin, and cementum. The development of caries is a multifactorial diseases that is dependent on four aspects. The most important one is the development of the bacterial plaque which sets the caries in motion. The second one is the quality and quantity of the salivary flow. The third aspect is the presence of minerals such as fluoride and the fourth aspect that you need to consider is the quality of nutritions. Caries is definitely associated with diet which is rich in refined carbohydrates and is associated with foods which are sticky to the tooth structure. Caries can affect both the baby teeth or the deciduous teeth as well as permanent teeth. And caries can also develop in different locations on the tooth. There are caries that develop in the pit and fissure caries, sometimes referred to as occlusal caries. They can also develop on the smooth surfaces on the teeth, either in between the teeth, known as interproximal, and also on the root surfaces of the teeth. Those caries on the root surfaces generally develop more in older age. Pit and fissure caries can start developing actually within days of tooth eruption providing that the diet is rich in suitable carbohydrates and begin shortly thereafter. Compare to coronal smooth surface caries, proximal caries progresses much quicker because it can pass through enamel much more rapidly. As mentioned, root surface caries develop in a later age. Caries can effect both the enamel, the dentin, and the cementum. And caries with effect the cementum of the root are particularly difficult to manage because cementum has the least calcium, it's the softest of the mineral structures in the tooth. There are caries which are associated with radiation. Radiation in certain cancers, head and neck cancers, destroys salivary glands. Those patients suffer from lack of saliva, which has a protective function, and they tend to develop caries at a high rate. And there also something which we refer to as rampant caries. Which occur in people with bad diets and with very poor oral hygiene. There are also the secondary, recurrent caries which can develop under poor fitting restorations. In those restorations which are not well adapted or do not form a perfect seal, they form an area where a patient has a difficulty in plaque control. The baby bottle caries are the caries which occur in very young children. They usually occur there's a really poor oral hygiene and where the diet is very rich in fermentable carbohydrates. Such caries usually develop within months of tooth eruption and they do so when the diet is rich in sucrose, glucose, and sticky foods. Bacteria metabolizes sugar which produces acid. This acid then stands to soften and break down the tooth structure. Therefore, a high sugar diet is a risk factor for dental caries. Dental caries is more common in the developed world due to the high sugar content of the diet. The frequency that bacteria are exposed to sugars definitely affect the likelihood of caries development. This is why snacking between meals promotes caries. The saliva plays a very important role in control of caries. It is a fluid secreted by the salivary glands namely the parotid, the submaxillary, sublingual, and outer minor glands. It contains a pH buffering capacity, cleansing effect, antibacterial action, and remineralization by salivary calcium. Individuals with dry mouth, known as xerostomia, due to radiation therapy, certain drugs, or other diseases, exhibit increased rate of caries. In humans, some of the more important bacteria that have been associated with different caries are the actinomyces viscosus, actinomyces naeslundii, the lactobacilli, enterococci, and the mutans streptococcus bacteria. Mutans streptococci bacteria actually are important for the caries to develop. Its virulence of the strep mutans is actually due to the adhesion, acidogenesis, and adhesion colonization, i.e., formation of biofilms. The host factors which can influence the development of caries are the tooth location, the presence of sugars and sticky foods, frequent snacking, inadequate oral hygiene, such as brushing and flossing, lack of fluoride, either in the diet or in the water, or in the toothpaste, lack of saliva, and various type of eating disorders. The best way to treat caries is actually prevention. Oral hygiene is extremely important. This includes daily brushing and flossing to inhibit the development of the bacterial biofilm. Regular visits with a dental hygienist are needed to clear away any remaining plaque and calculus. Fluoride plays incredibly important role in caries prevention. It both strengthens the teeth and inhibits bacterial ability to ferment sugars. Fluoride tooth pastes, fluoride rinses, and water fluoridation are all measures to ensure that teeth have enough exposure to fluoride. According to Center for Disease Control, water fluoridation is one of the top ten greater public health achievements of the twentieth century. Once caries develop, the way to treat them is to remove the decayed material and placing filling materials or crowns. This includes excavation of all caries tooth structure and placement of filling material to restore the tooth to proper form and function. Other types of conditions affecting the teeth are erosion, abrasion, occlusal trauma, and palpal conditions. Erosion is the loss of tooth structure due to chemical acidic breakdown from a non-bacteria source. That happens frequently in people who have acid reflux and have very acidic saliva. Erosion is many times associated with bulimia. Dental abrasion is the loss of the tooth structure due to mechanical work and incorrect brushing techniques. This picture which shows you the example of toothbrush abrasion due to incorrect brushing. Attrition is a loss of tooth structure from opposing teeth. This condition is found in patients who have excessive tooth grinding. This condition occurs frequently in patients who are emotionally stressed and they tend to grind the teeth either during the day or at night. Abfraction are lesions at the gumline thought to be caused by flexile forces that degrade the tooth structure. Occlusal trauma is a damage incurred by teeth or surrounding structures due to traumatic occlusion. Traumatic occlusion happens when the forces acting on the teeth exceed the capacity of the periodontal ligament to withstand such forces. There are two types of occlusal trauma. The first type, the more common type, happens when there are excessive forces acting on healthy periodontium. Example of such forces would be excessive grinding, clenching, chewing on nails, pencils, etc. These conditions, occlusal trauma, can be treated by occlusal adjustment, realignment of the teeth, and also, by appliances, such as night guard. Secondary occlusal trauma happens when there are normal occlusal forces, but the periodontal support is compromised and weakened by periodontal disease. The treatment for this condition, of course, requires, if possible, regeneration of the supporting structures and also splinting of the teeth to distribute the forces more equally. Caries, when it becomes severe, can actually penetrate the nerve of the tooth. When that happens, a palpable condition happens. The nerve becomes infected and becomes slowly, but surely, destroyed. The toxins and the byproducts from this infection can then spill into the surrounding bone. Even if a filling is placed, the immune system cannot clear the infection in the pulp chamber, and therefore the pulp tissue needs to be removed. This treatment is known as the endodontic therapy.