ENAMEL—the   white,   compact,   and   very hard   substance   that   covers   and   protects   the dentin  of  the  crown  of  a  tooth EUGENOL—a  colorless  or  pale  yellow,  oily liquid,  obtained  from  oil  of  clove  and  other natural sources; used as a topical analgesic and antiseptic;  and  used  in  combination  with  zinc oxide  as  a  sedative  dressing  in  a  tooth GINGIVAE—the   gums:   the   mucous   mem- brane, with the supporting fibrous tissue, which overlies the alveolar bone and encircles the necks of the teeth GINGIVAL  SULCUS—a  furrow  surrounding a tooth, bounded internally by the tooth surface and externally by the epitheliums lining the free gingivae INTERDENTAL   PAPILLA—the   triangular pad of gingival tissue filling the space between the proximal  surfaces  of  two  adjacent  teeth MESIAL-nearer   the   center   line   of   the dental arch NECROTIZING   ULCERATIVE   GINGIVI- TIS—trench mouth; an acute or chronic gingival infection characterized by redness and swelling, by   necrosis   extending   from   their   interdental papillae along the gingival margins, and by pain, hemorrhage,  and  a  necrotic  ordor OCCLUSAL—a  term  applied  to  the  chewing surface  of  premolars  and  molars PERICORONITIS—inflammation   of   the gingiva   surrounding   the   crown   of   a   partially erupted  or  unerupted  molar PERIODONTAL   LIGAMENT—a   modified periosteum  consisting  of  collagenous  connective tissue  fibers  that  connect  the  tooth  to  the  alveolar bone PERIODONTOTIS—an    inflammatory    re- action  of  the  periodontium,  usually  resulting  from the  extension  of  gingival  inflammation  into  the periodontium PERIODONTIUM—the tissue that surrounds and supports the teeth SCALING—the removal of calculus from the exposed  tooth  surfaces VARNISH—a  solution  of  rosin,  of  resin,  or of several resins in a suitable solvent or solvents, applied  to  protect  the  pulp DENTAL   ANATOMY When you refer a patient to a dentist, it will help  if  you  can  describe  the  specific  location  of the problem. To do that you must use the proper terms   to   describe   the   location,   identification, and  surfaces  of  the  teeth.  Since  this  does not   occur   frequently,   we   will   not   take   space here  to  cover  it.  This  information  is  available in detail in Dental Assistant, Basic,  NAVEDTRA 10677. DENTAL   HISTOLOGY Dental anatomy deals with the external form and  appearance  of  the  teeth.  Dental  histology studies the tissues and internal structure of the teeth,  along  with  the  tissues  that  surround  and support  them.  A  knowledge  of  dental  histology will   be   helpful   when   you   provide   emergency dental treatment. Tissues of the Teeth Structurally,  the  teeth  are  composed  of  four different tissues: enamel, dentin, cementum, and pulp.   They   are   shown   in   figure   2-5   and   are discussed  below. Enamel   is   the   calcified   substance   that covers the entire crown of the tooth. It is thickest 267.24 Figure 2-5.—The periodontium. 2-41