LIKE CREEDMOOR MARKS, HARD TO HIT. 209 



About the ninth year a mark, which is sometimes 

 mistaken for the infundibiihim, appears on tlie central 

 incisors. Girard named it the dentinal'''' 

 sta7\ but it is also called the fang-hole 

 and secondary mark. Dentinal star is 

 perhaps the most proper name, for the 

 mark is " due to the i)resence of second- 

 ary dentine, into which the remains of 

 the pulp has been converted." The con- 

 version of the pulp into dentine prevents 

 the cavity from becoming a reservoir for food, for 

 otherwise it would become such as soon as reached by 

 wear ; and it preserves tlie tooth from decay, afford- 

 ing a good illustration of Nature barricading disease. 

 The pulp cavity is lined with dentine ; the dentine 

 into which the pulp is converted is sometimes called 

 osteodentine, and may be distinguished from the for- 

 mer by its yellow tint. The star may not afford reli- 

 able data by which to judge of the age, but its pres- 

 ence is prima facie evidence that the tooth has been 

 worn to the original pulp cavity, f It becomes plainer 

 as it approaches the cavity's center, but the bottom 

 of the cavity is ultimately reached, which of course is 

 hollow. It is visible 8 or 10 years, the depth of the 

 cavities varying from about | to 1 inch. 



The marks of some teeth are disproportionately 

 composed of cement, a fact Prof, A. Chauveau says he 

 is not aware has ever been taken into account in ^^ cal- 



* See note, pag^ viii. 



f Nature fills the cavity in proportion as the crown is worn. 

 Take two teeth of tlie same kind, one just full-grown, the 

 other worn almost to its neck. In the latter the spot is visible, 

 and if as much material is cut from the former as has been woru 

 from the latter, its cavity will be cat through,— JcA?i Hunter. 



