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Tensile strength of prosthodontic treatments

March 11, 2016

One of the most amazing features of the mouth is the tensile strength of human teeth. Human teeth have a unique micro and nanostructure. The crystalline structure in human teeth have a special arrangement and they are effectively glued together by proteins. These proteins keep teeth intact even when damaged. Due to this structure, a crack or chip in the tooth is isolated and doesn’t run the length of the entire tooth.

The human tooth has dentin inside (or dental pulp), with a relatively soft enamel on the outside made of the mineral hydroxyapatite. Hydroxyapatite is also present in human bone. Even with our softer enamel, however, human teeth are remarkably strong in terms of tensile strength.

For prosthodontists, we often engage patients who have damaged their natural teeth despite that strength. Whether it was due to accident, injury, or decay, damaged teeth can be repaired or replaced by prosthodontists with a variety of measures. From veneers to fixed partial dentures or dental implants, there’s a solution for every patient’s need. Of course, nothing replaces the form and function of an original human tooth. Oftentimes, this means that replacing lost teeth isn’t so much about restoring a missing function, but preserving the natural teeth that remain and preventing them from shifting and loosening.

Published research in the Journal of Prosthodontic Research recently focused on this issue of tensile strength in human tooth prosthodontics. The researchers sought to verify the finite element analysis model of a three-unit fixed partial denture with in vitro electronic strain analysis and then analyze a clinical situation with the verified model. Essentially, researchers wanted to verify a model for analyzing tensile strength in fixed partial dentures and then use that model in a clinical setting.

The researchers applied strain gauges to critical areas of a three-unit fixed partial denture. Strain values were measured under a 300 N load perpendicular to the occlusal plane. In addition, a three dimensional finite element model was constructed from the scanning data. The researchers compared the strain analysis of the strain gauges versus the 3D model to determine whether the electronic data was as accurate as the strain gauge testing. Once the tensile strength of the three-unit fixed partial denture was determined, the clinical destruction of the fixed partial denture was evaluated with the verified finite element analysis model.

Both the strain gauge and 3D models found that tensile strength failure will occur in the veneer layer on buccal surface of the connector under occlusal force of 570N. While a force of 570N isn’t normal everyday wear on teeth, the researchers did find that the veneer layer on buccal surface of the connector is the weakest area in the fixed partial denture. The inner structure was able to withstand stronger forces, but veneer would chip and crack before those limits were discovered.

What this means in practice is that it’s essential to preserve natural teeth as best one can. This can be done with the standards of regular oral health care:

  • Brush twice daily. Brush gently. If gum recession has been an issue, switch to a softer bristled brush or to an electric toothbrush. Brushing too vigorously can lead to gum recession and complications with teeth.
  • Use fluoridated toothpaste. Fluoride has a long history in the United States, and what we know is that there is a level of fluoride exposure that provides the maximum benefit with minimal risk to the teeth. Modern U.S. water fluoridation efforts and fluoridated toothpastes are a response to this ongoing research.
  • Floss daily. Flossing removes food debris brushing can’t access in tight spaces between teeth or at the gumline. Flossing is essential for your healthiest teeth and gums.
  • Have an annual evaluation with your general dentist. Your dentists will screen you for oral cancers, investigate any abnormalities in your teeth, gums, or jaw, and will monitor your mouth over time using X-rays and other tools.
  • Have your twice-yearly prophylaxis or dental cleanings.
  • And visit your prosthodontist! If you have any missing or damaged teeth, resolving those issues is imperative. Fixing missing or broken teeth doesn’t just restore that tooth’s function; it preserves all surrounding teeth.

If you have questions about your oral health, contact the team at Tindal Smiles for your prosthodontic evaluation today!



Wan et. al. “Verification of finite element analysis of fixed partial denture with in vitro electronic strain measurement.” Journal of Prosthodontic Research. 60:1. 2016. 29-35.


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