Reducing polymerization stress by controlled segmental curing

A method of curing a photo-polymerizable composite dental material to form a dental restoration of a tooth, using light energy from a light source, wherein prior to polymerization the composite dental material is placed in physical contact with a tooth to be restored, such that a composite-to-tooth interface is established, comprising the steps of:

• exposing at least one selected segment of the material to the light energy while selectively limiting exposure of at least one substantially adjacent segment of the material to the light energy;
• wherein said step of exposing a selected segment of the material to light energy while selectively limiting exposure of a least one substantially adjacent segment of the material to the light energy includes the steps of fitting the light source with a mask;
• wherein said mask has at least one first portion that is substantially transmissive of the spectrum of light required for curing the material, and at least one second portion which is non-transmissive of at least a portion of the spectrum of light required for curing the material;
• such that the stress occurring over the entire composite-to-tooth interface is effectively divided into a series of incremental stresses over composite-to-composite sub-interfaces, thereby substantially preventing the overall polymerization stress from being transmitted to the composite-to-tooth interface or being passed through the interface into the tooth structure.