Does preparing a tooth for a crown weaken a tooth?

Molar teeth that have extensive tooth structure missing usually are strengthened by crowning them. Molars experience a great deal of vertical loading during a patient’s lifetime and crowns often strengthen these teeth and make them less likely to experience a fracture.

Premolars and anterior teeth present a different set of problems for a dentist. Preparing a tooth for a crown may make a tooth more vulnerable to horizontal loading (although it usually strengthens a tooth’s ability to with stand vertical forces). This fact has different significance depending on whether an anterior or posterior tooth is involved.

Teeth in general experience both vertical and horizontal loading forces, but the anterior teeth ( the canines, laterals and centrals)and even premolar teeth can experience a greater proportion of horizontal force vectors. Overtime crowned anterior teeth do seem to have a higher propensity to sustain a fracture of the tooth holding a crown, as compared to crowned posterior molars. Another factor involved maybe the fact that anterior and premolar teeth have less tooth structure in the first place as compared to molar teeth.

Consequently, when preparing either anterior or premolar teeth, care must be taken to conserve tooth structure so that the resulting restored tooth will be able to withstand the horizontal forces that will be placed on it. This can be a challenge for some teeth that have had large fillings in them prior to their being crowned.

One of the reasons that veneers or bonding are good for restoring anterior teeth is that they do not involve removing as much tooth structure as the preparation required for a traditional crown.