This paper examines the thermomechanical effects of Er :YAG irradiation of a tooth from a theoretical standpoint. Neglecting heat conduction and light scattering in tissue, analytical solutions for heat and stress distribution were used to estimate the radial and circumferential stresses developed as a result of temperature rise on the surface of a tooth. Radial stresses were always found to be compressive. Circumferential stresses, however, were compressive within a range inside the beam radius, and tensile outside the beam radius. Locations of the maximum tensile stress and maximum displacement were found to be outside and inside the beam radius (l/e2), respectively. Maximum stresses and displacements decreased monotonically with increasing beam radius. Our results also revealed that ablation and thermal stresses beyond enamel strength could be reached within a single laser pulse.