Reading and developing speaking skills

Ex. 8. Read VOCABULARY and memorize new words.

Ex. 9. Insert the missing letters:

D_ntist; d_ring; de_ay; rem_val; pro_ess; dete_mine; rem_ve_; prep_re; space; fil_ing; cle_ning; cav_ty; bacte_ia; debri_.

Ex. 10. Read the following words:

First; dentist; numb; around; tooth; local anesthetic; drill; air abrasion; instrument; laser; remove; decayed; area.

Ex. 11. Read and translate the following text:

Fillings

To treat a cavity your dentist will remove the decayed portion of the tooth and then "fill" the area on the tooth where the decayed material once lived.

Fillings are also used to repair cracked or broken teeth and teeth that have been worn down from misuse (such as from nail-biting or tooth grinding).

First, the dentist will numb the area around the tooth to be worked on with a local anesthetic. Next, a drill, air abrasion instrument or laser will be used to remove the decayed area. The choice of instrument depends on the individual dentist's comfort level, training, and investment in the particular piece of equipment as well as location and extent of the decay. Next, your dentist will probe or test the area during the decay removal process to determine if all the decay has been removed.

Once the decay has been removed, your dentist will prepare the space for the filling by cleaning the cavity of bacteria and debris. If the decay is near the root, your dentist may first put in a liner made of glass ionomer, composite resin, or other material to protect the nerve. Generally, after the filling is in, your dentist will finish and polish it.

Today, several dental filling materials are available. Teeth can be filled with gold; porcelain; silver amalgam (which consists of mercury mixed with silver, tin, zinc, and copper); or tooth-colored, plastic and glass materials called composite resin fillings. The location and extent of the decay, cost of filling material, patients' insurance coverage and your dentist's recommendation assist in determining the type of filling that will best address your needs.

Cast gold

Advantages:

1. Durability - lasts at least 10 to 15 years, usually longer; doesn't corrode:

2. Strength - can withstand chewing forces;

3. Aesthetics - some patients find gold more pleasing to the eye than silver, amalgam fillings;

Disadvantages:

1. Expense - more than other materials; up to 10 times higher than cost of amalgam filings;

2. Additional office visits - requires at least two office visits to place;

3. Galvanic shock - a gold filling placed immediately next to a silver, amalgam filling can cause a sharp pain (galvanic shock) to occur. The interaction between the metals and saliva causes an electric current to occur - it's a rare occurrence;

4. Aesthetics - most patients don't find any "colored" fillings to be an "eye-pleasing" advantage;

Silver-fillings (Amalgams)

Advantages:

1. Durability - lasts at least 10 to 15 years and usually outlasts composite fillings;

2. Strength - can withstand chewing forces;

3. Expense - is less expensive than composite fillings;

Disadvantages:

1. Poor aesthetics - fillings don't match the color of your natural teeth;

2. Destruction of more tooth structure - healthy parts of the tooth must often be removed to make a space large enough to hold the amalgam filling;

3. Discoloration - amalgam fillings can create a grayish hue to the surrounding tooth structure;

4. Cracks and fractures - although all teeth expand and contract in the presence of hot and cold liquids, which ultimately can cause the tooth to crack or fracture, amalgam material - in comparison with other filling materials-may experience a wider degree of expansion and contraction and lead to a higher incidence of cracks and fractures;

5. Allergic reactions - a small percentage of people, approximately 1%, are allergic to the mercury present in amalgam restorations;

Tooth-colored composite fillings

Advantages:

1. Aesthetics - the shade/color of the composites can be closely matched to the color of existing teeth; is particularly well suited for use in front teeth or visible parts of teeth;

2. Bonding to tooth structure - composite fillings actually chemically bond to tooth structure, providing further support to the tooth;

3. Versatility in uses - in addition to use as a filling material for decay, composite fillings can also be used to repair chipped, broken or worn teeth;

4. Tooth-sparing preparation - sometimes less tooth structure needs to be removed compared with amalgams when removing decay and preparing for the filling;

Disadvantages:

1. Lack of durability - composite fillings wear out sooner than amalgams (lasting at least 5 years compared with at least 10 to 15 for amalgams); in addition, they may not last as long as amalgams under the pressure of chewing and particularly if used as the filling material for large cavities;

2. Increased time - because of the process to apply the composite material, these fillings can take up to 20 minutes longer than amalgams to place;

3. Additional visits - if composites are used for inlays or onlays, more than one office visit may be required;

4. Chipping - depending on location, composite materials can chip off the tooth;

5. Expense - composite fillings can cost up to twice the cost of amalgams;

Ceramics, which are made most often of porcelain, are more resistant to staining than composite resin material but are also more abrasive. This material generally lasts more than 15 years and can cost as much as gold.

Glass ionomer is made of acrylic and a specific type of glass material. This material is most commonly used for fillings below the gum line and for fillings in young children (drilling is still required). Glass ionomers release fluoride, which can help protect the tooth from further decay. However, this material is weaker than composite resin and is more susceptible to wear and prone to fracture. Glass ionomer generally lasts 5 years or less with costs comparable to composite resin.

Ex.12. Translate into English:

Видаляти, пломби, наліт, бактерія, стійкий до, захищати, переваги і недоліки, відновити, місце розташування, карієс; гниття зуба, визначати, чищення, подрібнення; здрібнювання, іономер, тривалість, вартість; ціна, змінність, жування, неправильно використовувати; зловживати; невідповідне призначення.

Ex.13. Answer the following questions:

1.Why are fillings inserted in teeth? 2. What are the most important steps of dentist to fill in the cavity? 3. What types of fillings do you know? 4. What are disadvantages of silver fillings? 5. What are advantages of tooth-colored composite fillings? 6. What is durability of silver fillings? 7. What are advantages of cast gold fillings?

Ex.14. Match the following words logically:

1. Vital, destroy, front, soft, entrance, pack in, heat

2. Back, cold, come out, hard, dead, preserve, exit

Ex. 15. Read the following text and comment upon it. Try to retell the text.