RATES OF DENTIN MINERALIZATION IN PERMANENT HUMAN TEETH

Previous experimental studies have estimated linear rates of dentine f ormation in modern humans to be close to 4 mu m day(-1). In this study a method similar to that first adopted by Kawasaki, Tanaka and Ishika wa(5) was used to estimate linear rates of dentine mineralization over a period of 1200 days in both the cusps and cervical regions of sever al permanent tooth types. All teeth were from the same individual. Rat es in the cusps of teeth with the tallest crowns were estimated to be between 5 mu m day(-1) and 6 mu m day(-1). This is higher than previou s estimates in permanent tooth crowns, although rates in the cusp of a first permanent molar, where cusps were less tall and cuspal dentine therefore less thick, were close to previous estimates of 4 mu m day(- 1). Despite this variation in cuspal rates, mineralization rates were linear in all cusps studied over a long period of time. Rates in the c ervical region, either close to the enamel dentine junction or to the cement dentine junction, were estimated to be between 1.3 mu m day(-1) and 1.5 mu m day(11), much slower than reported previously. Rates in the mid-portion of the dentine, in both the lateral part of the crown and in the cervical one-third of the root, rose steadily to match rate s in the cuspal region, but then slowed towards the pulp chamber. Thes e data extend the findings of previous studies on permanent human dent ine. They demonstrate a wide range of mineralization rates in permanen t dentine and provide a more secure basis for judging different rates in different locations of different human tooth types.