CAUSES OF TEETH DECAY 113 



II. By means of a small mirror, observe the front surfaces of your upper 

 teeth, the inner surfaces of the lower front teeth, and the inner surfaces of the 

 back teeth. Use the tongue to explore the surfaces of the teeth for tartar. 



A. Describe the appearance and location of any tartar. 



B. Discuss the origin of tartar. 



III. Look carefully at the gum line of the teeth. Describe the appearance 

 of any tooth from which the gum has receded, exposing the neck. 



A. Why will such teeth decay quickly? 



B. What effect will the removal of tartar and proper massaging of 

 the gums probably have on such teeth ? 



IV. By comparing your teeth with the diagram on page 109, name and 

 describe the condition of any tooth showing a cavity. In each case describe 

 the apparent extent of the cavity. Explain why your examination is not as 

 complete as a dentist's ? 



V. If you have any roots of broken teeth left in your gums, give, briefly, the 

 history of each. By referring to the diagram determine the name of each. 



A. Discuss whether the loss of the tooth could have been prevented. 



B. Discuss dangers from the presence of roots left to decay in the mouth. 



VI. If you have any spaces left by extracted teeth, what are your plans in 

 regard to these spaces ? Again refer to the diagram to name the missing tooth. 



VII. When did you last visit a dentist? When will you again visit one? 



VIII. If you are unable to detect any defects in your teeth, tell why you 

 cannot conclude that your teeth are in good condition ? 



IX. By means of red and blue litmus, test whether the reaction of your 

 mouth is acid or alkaline. NOTE. When blue litmus turns pink, an acid is 

 present. When pink litmus turns blue, an alkali is present. 



A. State one possible source of acid-formation. What effect has acids 

 on enamel ? 



X. What advice can you give your parents in regard to the care of the 

 teeth of your small brothers and sisters ? 



XI. Discuss the value of X-rays in dentistry. 



QUESTIONS 



1 . Describe the arrangement, number, and kinds of temporary teeth. 



2. Describe the arrangement, number, kinds, and structure of per- 

 manent teeth. 



3. Explain the hygienic methods of cleaning teeth. 



4. What is the relation of proper diets to good teeth ? 



5. What are some of the causes of bad teeth? 



