Your definitions and explanations here!
Enamel crack- enamel cracks are actually extensions of enamel lamellae which are developed 
                       in planes of tensions. But if the disturbance is more severe, a full crack may develop. 
 


Cervical portion- the portion of the tooth crown closest to the gums. 
 
 
 


Hypocalcification- this isn seen in the form of chalky white surfaces of the tooth. This is  
                   a common defect which is the inability of the enamel matrix to mature or even formed. 
                   One very common cause of this is ingestion of excessive water-borne flouride  
                   (in excess of 1.5 parts per million). The ideal flouride concentration in water is 
                   1 part per million which is optimal for protection against dental caries. 


Dental caries-  
 
 


Dentinal tubules- they are found throughout normal dentin. They are only visible though,  
                through electon microscope. To give you an idea of how minute these tubules are, 
                For every 1 square mm. of cavity exposes 30,000 tubules.                 
 
Odontoblastic processes- these are extensions of odontoblasts, the dentin forming cell. 
               Thet are contained inside the dentinal tubules. The inportance of these processes 
                is that they give vitality to the dentin, which is important for its capacity to react 
                to physiologic and pathologic stimuli. Since dentin is just right above the pulp,  
                 it is the function of dentin to undergo protective changes for the pulp.  

There are three Theories of Pain Transmission: 
               1. Direct innervation- in which stimuli directly effect the nrve endings in the tubule. 
                   But the manner in which stimuli reach nerve endings is yet unknown. 
               2. Hydrodynamic theory- the most popular theory staes that stimuli causes fluid 
                   movement within the tubules and disturbs the nerve endings, illiciting pain. 
               3.Transduction theory- states that it is the odontoblastic processes that are  
                  excited and the impulses are transmitted towards nerve endings. This is not  
                  popular because no neurotransmitter can be found in odontoblastic processes. 


The following receptors are not found in the tooth pulp: 
 
Receptor
Stimulus

Root Canal Treatment-  go through the pages on Oral Anatomy. Watch for it soon on 
                The "Molar Truth" is...