366 



HOW FOOD IS PREPARED FOR BODY USE 



and form a center or focus of infection from which poison gets 

 into the blood. As a result of this, very serious diseases may 



occur, of which the most com- 





exiamzA 



dentine 



pulp 



mon are rheumatism of the 

 joints and neuritis or inflam- 

 mation of the nerves. Infected 

 teeth should be extracted, as 

 this usually removes the cause 

 of the trouble. 



."blood, , 

 vessel 



.cement* 



Practical Exercise 1. Using a 

 small mirror, count your teeth, 

 giving the number under each of 

 the following heads : 



(a) Incisors, broad cutting teeth 

 in front. 



(&) Canines, pointed sharp teeth 

 next to the incisors. 



(c) Premolars, grinders with two 

 points on the biting surface. 



(d) Molars, teeth with more than 

 two points, in the back of the 

 mouth. 



Practical Exercise 2. Examine 



carefully with a flash light each of 



A section through a tooth. Why is a cavity your teeth and answer the following 



painful? Why is a tooth sometimes so hard questions. Mark the points asked 



t0 pul1 ? for on the chart copied from the 



diagram. 

 With a bracket, label each group of teeth. With a cross, mark all the 

 teeth you have lost or that have not grown. Mark all cavities not filled in 

 your teeth by a spot where the cavity exists. If teeth have been filled, 

 mark with appropriate title. 



Care of the teeth. Too much emphasis cannot be placed on 

 the proper care of the teeth. They should be carefully brushed 

 each morning and evening. Use a medium stiff brush and work 

 the bristles in a vertical direction away from the gum so as to get 

 between the teeth. After that, a rotating movement over the sur- 

 face and between the teeth will dislodge any remaining particles 

 of food. Above all, massage the gums with your brush and polish 

 the surface of the teeth both in back and in front, for this helps 

 remove the bacterial film. Dental silk should be used after meals. 



It has been found that fruit acids are very beneficial to the teeth. 

 Vinegar diluted to about half strength with water makes an 



