THE ORAL CAVITY Good overall health starts with the oral cavity…

The mouth opens into the oral or buccal cavity Its functions include: – Analysis of material before swallowing – Mechanical processing by the teeth, tongue, and palatal surfaces – Lubrication – Limited digestion

ORAL CAVITY

LIPS Lips are muscular structures, formed mostly by the orbicularis muscle. The color from the underlying blood vessels can be seen through the thin, transparent epithelium, giving the lips a reddish-pink appearance.

Lips Lips are a visible body part at the mouth of humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. The lower lip is usually somewhat larger. The skin of the lip, with three to five cellular layers, is very thin compared to typical face skin, which has up to 16 layers. If the individual has a deficiency of riboflavin, vitamin B2, the corners of the lips will exhibit cracks and fissures. A disorder known as cheilosis.

TONGUE Is a large, muscular organ that occupies most of the oral cavity. Frenulum – A thin fold of tissue that is attached anteriorly to the floor of the mouth. The tongue moves food in the mouth and, in cooperation with the lips and cheeks, holds the food in place during mastication. It is a major sensory organ for taste, as well as being one of the major organs of speech.

The tongue primary functions include: – Mechanical processing – Assistance in chewing and swallowing – Sensory analysis by touch, temperature, and taste receptors

TONGUE

Figure 24.7 The Salivary Glands Figure 24.7a, b

SALIVARY GLANDS

Salivary glands Your salivary glands make saliva, or spit, and empty it into your mouth through openings called ducts. The 3 major salivary glands are the parotid, submandibular, and sublingual glands. Saliva helps to keep the mouth moist, softens the food as it is chewed, and by means of salivary amylase, the digestive enzyme, that aids in the breakdown of food. A viral infection that affects the parotid glands are the mumps. (Thanks to the mumps vaccine developed in the 1960s, this viral infection is rare).

TEETH Normal adult teeth: 32 teeth It is divided into quadrants: right upper, left upper, right lower and left lower. Each quadrant contains: one central and one lateral incisor, one canine, first and second premolars and first, second and third molars. The third molars are called wisdom teeth because they usually appear in a person’s late teens or early twenties.

Figure 24.9 Primary and Secondary Teeth Figure 24.9a, b

Permanent Eruption Chart Permanent Teeth Development Chart Maxillary tooth sheddingTooth eruption Central incisors 6-7 years 7-8 years Lateral incisors 7-8 years 8-9 years Canines (cuspid) years years 1st pre molars 9-11 years years 2nd pre molars years years Mandibular tooth sheddingTooth eruption 1st pre molars years years 2nd pre molars 9-11 years years Canines (cuspid) 9-12 years 9-10 years Lateral incisors 7-8 years 7-8 years Central incisors 6-7 years 6-7 years

Deciduous dentition Also called baby teeth, milk teeth, temporary teeth, and primary teeth. Deciduous teeth start to form during the embryo phase of pregnancy. The deciduous dentition has a set of 20 teeth, 5 in each quadrant. The deciduous dentition or baby teeth are very important as they help the permanent teeth erupt in their normal positions.

Permanent Dentition Also known as adult teeth, the second set of teeth in humans. The permanent dentition has a set of 32 teeth, 8 in each quadrant. At age 6-7 years, until the last primary tooth is lost, a person will have what is known as a ‘mixed dentition.’ A mouth with both primary teeth and permanent teeth. Most people do not realize that the first molars, erupting at as early as 5 years of age, are permanent teeth because of such early eruption and only erupting once. These first permanent molars are the most important teeth for the correct development of an adult dentition. We only get one set of first, second, and third molars. If we lose these teeth, they will not grow back. If the deciduous dentition was poorly cared for, then the permanent teeth will not come in properly.

Figure 24.8 Teeth Figure 24.8a, b

The teeth and their parts Each tooth has two main parts, the crown and the root. The crown and the root meet at the neck of the tooth, which is normally just below the gum margin. The crown is the part of the tooth that we see in the mouth. It is made up of the enamel, dentin and pulp. Enamel is the white hard covering over the crown of the tooth. The hardest substance in the body. Dentin is a cream colored hard material that makes up the bulk of the tooth. The tooth will appear yellow if the dentin is exposed and the tooth will be sensitive to hot or cold. The nerves and blood vessels of the tooth are called the pulp. The primary function of the pulp is to form dentin, other functions include nutritive, which means the pulp keeps the surrounding tissues filled with moisture and nutrients, sensory, which means that the pulp responds to hot or cold temperatures and trauma to the dentin or pulp, and protective, which means that the pulp protects the tooth by forming reparative dentin. The roots are embedded in the tooth socket in the jaw bone. They serve to anchor the tooth in position and keep the tooth alive by picking up nutrients from the body and carrying them to the tooth.

Healthy Gingiva The gingiva, or gums, consists of the mucosal tissue that lies over the alveolar bone. Healthy gingiva usually has a color that has been described as "coral pink." Healthy gingiva has a smooth arcuate or scalloped appearance around each tooth. Healthy gingiva fills and fits each interdental space. Healthy gingiva also has a firm texture that is resistant to movement, and the surface texture often exhibits surface stippling much like an orange.

Gingival Disease GingivitisPeriodontitis

Gingivitis The term ‘gingivitis,’ is used to describe non-destructive periodontal disease. Gingivitis describes the events that begin with bacterial growth in your mouth and may end, if not properly treated, with tooth loss due to destruction of the tissue that surrounds your teeth. Bacteria in plaque build up, causes the gums to become inflamed (red and swollen) and often easily bleed during tooth brushing. Although the gums may be irritated, the teeth are still firmly planted in their sockets. No irreversible bone or other tissue damage occurs in its early stages. That is why regular cleanings are so important because the dentist is able to spot gingivitis in its early stages and is able to treat the disease before more serious complications arise.

Periodontitis Gingivitis usually precedes periodontitis and, unlike gingivitis, periodontitis is irreversible. Periodontitis is a set of inflammatory diseases affecting the periodontium, the tissues that surround and support the teeth. Periodontitis can be site specific meaning that gingivitis and periodontitis can involve only the three molars in the back of the oral cavity, for example, or the two central incisors either maxillary or mandibular and so on. With periodontitis the gums recede, exposing the root surfaces and increasing sensitivity to hot and cold. Toxins, produced by the bacteria in plaque as well as the body's "good" enzymes involved in fighting infections, start to break down the bone and connective tissue that hold teeth in place. Gum disease is the leading cause of tooth loss in adults and has been linked to endocarditis, an infection of the inner lining of your heart.

Gingival Disease GingivitisPeriodontitis

General Oral Anatomy

Hard Palate The hard palate, or roof of the mouth, is a thin horizontal bony plate of the skull. The interaction between the tongue and the hard palate is essential in the formation of certain speech sounds, notably /t/, /d/, and /j/. If the hard palate of a fetus does not fuse properly during pregnancy, a cleft palate occurs. It is treated with surgery, and if left untreated it can lead to hearing, speech, and feeding problems.

Soft Palate The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone, Hence, soft palate. The soft palate is movable, consisting of muscle fibers sheathed in mucous membrane. It is responsible for closing off the nasal passages during the act of swallowing, and also for closing off the airway.

Palatine Tonsil Palatine tonsils are the tonsils that can be seen on the left and right sides at the back of the throat. The palatine tonsil is one of the mucosa-associated lymphoid tissue (MALT). The palatine tonsil is located at the entrance to the upper respiratory and gastrointestinal tracts to protect the body from the entry of exogenous material through mucosal sites In children, the tonsils are common sites of infections that may give rise to acute or chronic tonsillitis. In severe cases the tonsils may have to be removed which is known as a tonsillectomy.

Palatine Tonsil

Uvula The uvula is the small projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose, glands that branch out much like grapes, and some muscular fibers. The uvula plays a key role in the articulation of the sound of the human voice to form the sounds of speech. The uvula is responsible for the ‘gag reflex.’

Uvula

Figure The Swallowing Process Figure 24.11a-h

Figure The Swallowing Process Figure 24.11a-h

Final Thoughts In order to stay healthy, it is wise to think about the care of your oral health. It is important for smokers to start thinking about the effects it causes their oral health as well as their overall health. Quitting smoking is one of the best things that you can do for your body as well as the community. Brushing and flossing everyday is a great start in overall health. Tooth loss does not come with old age but with poor oral care. That’s why regular dental check ups can aid in saving teeth. Eating the right foods can make a total body impact on overall health. If you skip brushing and flossing more than once, smoke, and eat the wrong foods such as candy, sodas, and chips. You can expect to be an unhealthy individual and possibly have many tooth and gum infections that will ultimately lead to heart problems. Always remember, “You don’t have to brush and floss all your teeth, just the ones you want to keep!”