Dental Education Lecture: Sealant

In Lecture: Brushing for Kids, we discuss that the developmental grooves in the biting, buccal and lingual surfaces are susceptible areas for dental cavities (caries).  To prevent the latter, we need to brush the biting surface in a 90 degree and the other two surfaces in a 45 degree.  Another way to prevent cavities is to place sealant when an adult molar is just coming in the mouth of your kids.  Fig.1 illustrates the biting surface of three molars.  Cross lines in these 3 molars indicate the developmental grooves we just talked about.  In Fig.2, the black spot represents a cavity in the middle of cross lines.  Fig.3 is a cross section of an adult molar.  If you are curious about how the cross section comes from, you need to return to Fig.1. The dashed red line is an imaginary line we cut through the tooth (teeth).  The arrow shows how we look at the cross section.  Anyway, let us look at a development groove in the cross section in Fig.3.  We blow up a gray box in Fig.3 into that of Fig.4.  As you may note, the groove is quite complicated, having a narrow opening and an enlarged bottom.  Tiny food particles and plaque (germ film, i.e., germ product) are easily trapped there (yellow, Fig.5).  The end result of accumulation of debris and germ in the groove is formation of a cavity (black, Fig.6).  

Scientists have developed a special material called sealant to seal the groove before cavity sets in.  Dentists or assistants dry up the tooth and deliver pretty runny sealant into the groove using a syringe (Fig.7).  Then they use a special light to make the sealant hard and set.  So that the latter stays in the groove to reduce the possibility of trapping bad stuffs.  Fig.9 is how the tooth look like when sealant procedure is finished.  However, correct ways of brushing should never be stopped, since sealant may come loose.

Xin Wei, DDS, PhD, MS 1st edition 01/27/2009, last revision 03/20/2010