Benefits and Risks of Fluoridation

Determination of the benefits and effectiveness of community water fluoridation should consider what the oral health of the population was like before fluoridation. It may be difficult to imagine that, during the 1940s in the United States, extractions of first molars in young children were routine; exodontia (extraction of the teeth) and complete dentures were the norm for older adults; 10% of recruits into World War II were rejected because of poor oral health, which meant those recruits did not have six opposing teeth and 40% needed immediate treatment for relief of pain.

Over the past 60+ years, numerous studies have been conducted on the effectiveness of fluoridation and fluorides in preventing dental caries and decreasing caries rates.

Water fluoridation has continued to play a dominant role in the decline in caries. During the early years of fluoridation, the primary source of fluoride was the drinking water, because there were no other discretionary sources of fluoride available, such as fluoride toothpaste.

Consequently, the reductions in dental caries rates attributed to water fluoridation were easily measurable and significant. By 1980, 98% of the available dentifrices contained fluoride. As more professional and consumer products containing fluoride came on the market, it was increasingly difficult to measure what portion of the caries reduction was attributable solely to water fluoridation. However, the impact of fluoridation remains evident.

Fluoridation has risks as well as benefits. Fluoride in water can cause a dental condition known as enamel fluorosis. Although the mild and very mild forms of fluorosis may be so minimally apparent that individuals may not even realize their teeth are effected, moderate and severe forms of fluorosis result in stained and pitted teeth that are cosmetically objectionable.

Enamel fluorosis results from hypomineralization in enamel surfaces of teeth that have been exposed to fluoride ingested during enamel formation. Enamel fluorosis occurs in children who consume fluoride when their teeth are developing; fluorosis cannot occur once enamel formation is complete and the teeth have erupted, regardless of intake; therefore older children and adults are not at risk for enamel fluorosis.

Excessive levels of exposure can occur in various ways, such as in drinking water that contains higher-than-optimal fluoride levels, as can happen with private wells or community water systems with high levels of naturally occurring fluoride.

The Safe Drinking Water Act, enacted by Congress in 1986, established primary and secondary standards for natural fluoride levels in public drinking water in the United States.

Fluoride ingestion should be reduced during the ages of tooth development, particularly under the age of 2 years. Parents need to assist in attainment of this goal by supervising young children during toothbrushing to ensure that they use only a small amount of toothpaste and do not swallow the toothpaste.

Complete and translate the sentences.

1. Determination of the benefits and effectiveness of community …

2. Water fluoridation has continued …

3. As more professional and consumer …

4. Fluoride in the water can cause…

5. Moderate and severe form of fluorosis result in …

6. Enamel fluorosis results from hypomineralization …

7. Parents need to assist …

Speaking

Uuse the information given in this Unit to explain the role of water fluoridation and the impact of multiple sources of fluoride on the decline of dental caries.

EXIT TEST

1. Write in English:

Ротовая полость, пищеварительный тракт, твёрдое нёбо,

частички пищи, пищеварительная cистема,

значительная роль, сосательный рефлекс, полости тела, дыхательная система, зубная боль,

челюсть,

разрушение, болезненный,

зуб,

десна.

2. Choose the correct variant:

1. The oral cavity is the first portion of the alimentary/ respiratory tract.

2. The mouth is normally moist/ dry.

3. The mouth is lined with a mucous membrane/ skin.

4. Infants are born with a sucking/ masticatory reflex.

5. The oral mucosa can be divided into five/ three categories.

3. Write sentences using Passive.

1) Many different bacteria … (find) in the mouth.

2) The inside of the mouth … (line) with a mucus membrane.

3) The tongue, lips and jaw … (need) to produce the sounds.

4) The mucous membrane …(involve) in the process of absorption and secretion.

5) Intense blood pressure … (produce) by increased blood flow in the case of infection.

6) Severe pain inside …(cause) by the increased blood flow.

7) Specialised cells …(deliver) by the increased blood flow to the place of infection.

4. Complete sentences with the correct form of the verb in Passive.

1. Food particles …… (break up) into smaller pieces in the mouth.

2. The inside of the mouth … (line) with the mucus membrane.

3. The tongue, lips and jaw …(need) to produce sounds.

4. Most of the body …(cover) with the skin.

5. The oral mucosa … (can/ divided) into three categories.

6. The mucus membrane … (involve) in absorption and secretion.

7. Infants … (bore) with a sucking reflex.

5. Transform into Passive.

1) We find many different bacteria in the mouth.

2) The blood flow can deliver specialized cells that can fight the infection.

3) The increase blood flow of the teeth produces intense pressure inside.

4) The increase blood flow causes severe pain inside.

5) They usually treat abscess by some combination of antibiotic therapy, endodontic treatment of root canal or removal of the tooth.

6. Can/ be able to:

1. ______ (you/can) see well enough to get around the house after an operation?

2. ______ (your husband/ can) come and pick you up if you phone him?

3. ______ (you/ can) speak to the dentist yesterday?

4. For how long _________ (you/ not/ can) eat the hard food?

5. _______ (he/ can/ ever) smile widely?

7. Give advice. Fill in should/ shouldn’t.

1. You ____ eat a lot of fruit and vegetables.

2. You _____ talk with your mouth full.

3. Peter _____ eat so much junk food.

4. A: Tim’s got an awful toothache.

B: He ____ go to the dentist.

5. You ____ brush your teeth twice a day.

8. What are the rules for nurses in your country? Tick (√) the correct column next to each prompt, then use the information in the table to talk about nurses in your country.

Nurses	must	mustn’t	don’t have to
Wear a uniform
Be polite to the patients
Assist doctors when necessary
Be rude to the patients
Cry loudly in the hospital

9. A) Read the text. Fill in the gaps.

Eruption in humans is a process in tooth development in which the teeth enter the mouth and become visible. Current research indicates that the periodontal ligaments play an important role in tooth eruption. Primary teeth erupt into the mouth … (1). These teeth are the only ones in the mouth until a person is about six years old. At that time, the first permanent tooth erupts. This stage, during which a person has a combination of primary and permanent teeth, … (2). The mixed stage lasts until the last primary tooth is lost and the remaining permanent teeth erupt into the mouth.

The onset of primary tooth loss has been found to correlate strongly with somatic and psychological criteria of school readiness.

The periodontium is the supporting structure of a tooth, helping to attach the tooth to surrounding tissues and to allow sensations of touch and pressure. It consists of the cementum, periodontal ligaments, alveolar bone, and gingiva. Of these, cementum is the only one that is a part of a tooth. Periodontal ligaments connect the alveolar bone to the cementum. Alveolar bone surrounds the roots of teeth to provide support and creates what is commonly called an alveolus, or "socket". Lying over the bone is the gingiva or gum, … (3).

The periodontal ligament is a specialized connective tissue that attaches the cementum of a tooth to the alveolar bone. This tissue covers the root of the tooth within the bone. Each ligament has a width of 0.15 - 0.38 mm, … (4).The functions of the periodontal ligaments include attachment of the tooth to the bone, support for the tooth, formation and resorption of bone during tooth movement, sensation, and eruption.

The alveolar bone is the bone of the jaw which forms the alveolus around teeth. Like any other bone in the human body, alveolar bone is modified throughout life. The gingiva ("gums") is the mucosal tissue that overlays the jaws. There are three different types of epithelium associated with the gingiva: gingival, junctional, and sulcular epithelium. The gingival epithelium is not associated directly with tooth attachment and is visible in the mouth. The junctional epithelium, … (5). The sulcular epithelium is nonkeratinized stratified squamous tissue on the gingiva which touches but is not attached to the tooth. This leaves a small potential space between the gingiva and tooth which can collect bacteria, plaque, and calculus.

A - from around six months until two years of age.

B - composed of the basal lamina and hemidesmosomes, forms an attachment to the tooth.

C - but this size decreases over time.

D - which is readily visible in the mouth.

E - is known as the mixed stage.

9. B) Explain the words in bold.

9. C) Make up phrases with the words: important, surrounding, alveolar, become, provide, tooth, periodontal.

_____ support

_____ tissue

____ development

____ visible

____ bone

____ ligament

____ role

ORAL CAVITY

10. Read the text and do the tasks.

1. The mouth, buccal cavity, or oral cavity is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.

2. In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in human language. Another non-digestive function of the mouth is its role in secondary social and/or sexual activity, such as kissing.

3. The mouth is normally moist, and is lined with a mucous membrane. The lips mark the transition from mucous membrane to skin, which covers most of the body. The first space of the mouth is the mouth cavity, bounded laterally and in front by the alveolar arches (containing the teeth), and posteriorily by the isthmus of the fauces. The oral cavity is also known as the mouth which swallows food and drinks that then go down the esophagus and into the stomach.

4. The mouth plays an important role in speech (it is part of the vocal apparatus), facial expression, eating, drinking and breathing. Infants are born with a sucking reflex, by which they instinctively know to suck for nourishment using their lips and jaw. The oral mucosa is the mucous membrane epithelium of the mouth. It can be divided into three categories.

• Masticatory mucosa - keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate and attached gingiva.

• Lining mucosa - non-keratinized stratified squamous epithelium, found almost everywhere else in the oral cavity.

• Specialized mucosa - specifically in the regions of the taste buds on the dorsum of the tongue.

5. The mucous membranes (or mucosae; singular mucosa) are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line various body cavities that are exposed to the external environment and internal organs. It is at several places continuous with skin: at the nostrils, the lips, the ears, the genital area, and the anus. The sticky, thick fluid secreted by the mucous membranes and gland is termed mucus. The term mucous membrane refers to where they are found in the body and not every mucous membrane secretes mucus. Body cavities featuring mucous membrane include most of the respiratory system.

10 A) True or false.

1. The mouth is the first portion of the digestive tract. __

2. The mouth in humans also plays an important role in communication. __

3. The lips mark the transition from the tongue to skin. __

4. The oral mucosa can be divided into masticatory, lining and specialized mucosa. __

5. The mucous membranes line various body cavities. __

10 B) In which part of the text is said about:

6. not every mucous membrane secretes mucus __

7. mouth is the beginning of the digestive system __

8. mouth plays an important role in communicating __

9. skin covers most of the body __

10. oral cavity begins digestion __

10 C) Make up phrases with the words: alimentary, food, human, mucous, body, respiratory, significant, sucking, digestive, hard.

_____ canal

_____ membranes

_____ cavities

_____ system

_____ reflex

_____ system

_____ role

_____ language

_____ particles

______ palate