title: [Stress on class tunnel restorations of the first mandibular molar].
abstract: OBJECTIVE
  To study the effect on the stress and deformation of the first mandibular molar when the ridge thickness of Class tunnel restorations changes.
  
  
  METHODS
  Six kinds of Class tunnel restorations of the first mandibular molar were prepared,the ridge thickness were 1.5, 2.0 or 2.5 mm, the lateral cavity of the molar was oval or round in shape. The cavities were filled with composite resin. The stresses and deformations were imitated and analyzed by using three-dimensional finite element method with ANSYS 9.0, after vertical and lateral pressures were exerted.
  
  
  RESULTS
  Among the 6 restorations, when the ridge thickness of Class tunnel restorations was no less than 2 mm, the stresses were well-distributed, and the directions of stresses on the ridge were the same. There was no difference between round and oval-shaped cavities of Class tunnel in their stress and deformation.
  
  
  CONCLUSIONS
  The ridge thickness of Class tunnel restorations of the mandibular molar is effective and reliable when it's not less than 2 mm.
authors: Department of General Dentistry, Ninth People's Hospital, College of Stomatology, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China.
authors: Lan
authors: L
authors: Tao
authors: Xiao
authors: X
authors: Xu
authors: Fang
authors: F
authors: Ning
mesh_terms: D003188:Composite Resins; D003731:Dental Caries; D003737:Dental Cavity Preparation; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D008334:Mandible; D008963:Molar
chemical_list: D003188:Composite Resins