Experimental fractures of monkey mandibles

Forty vervet monkey half mandibles, 20 with unerupted third molars and 20 with erupted third molars, were partially embedded in acrylic and loaded in an Instron tensiometer. Mandibles with unerupted third molars fractured at 15.8 +/- 2.5 kg while those having erupted third molars fractured at 26.4 +/- 4.2 kg. Mandibles having unerupted third molars were shown to be significantly weaker than the mandibles with erupted third molar (t = 8.45, P less than 0.001).