In situ Compressive Loading and Correlative Noninvasive Imaging of the Bone-periodontal Ligament-tooth Fibrous Joint

The overall goal of this procedure is to measure the biomechanical response of the dental alveolar complex. This is accomplished by first dissecting the animal to remove an intact hemi mandible or maxilla. The second step of the procedure is to mount the specimen and prepare the tooth surface with a composite buildup for mechanical testing.

The final steps include measuring the biomechanical state of the sample using an in C two load cell, followed by scanning the specimen using an x-ray microscope. Ultimately, results can show changes in the biomechanical response of a fibrous joint, such as due to disease or hypofunction in conjunction with high resolution tommies at various loading states. The main advantages of this technique over existing methods are that the organ is kept intact and that the methods of scanning are non-invasive.

Thus, the natural strain field of the ligament is maintained and the biomechanical properties can accurately be measured. First, obtain a dissected maxilla or mandible as described in the protocol. Proceed by immobilizing the specimen on the steel stub using acrylic.

Remove any excess material from the edges of the stub. Next, using a straight edge align the occlusal surfaces of interest parallel to the A FM metal specimen disc in the mesial distal plane, and then in the buccal lingual plane. Using a blunt tool, create a trough surrounding the molars.

This functions as a reservoir for tissue hydration. During in C two loading to prepare the tooth surface, use 35%phosphoric acid to etch the occlusal surface of interest for 15 seconds. After 15 seconds of past, rinse the etched area thoroughly with deionized water and dry the surface by using compressed air to prevent unintended curing of the composites.

Perform the next few steps under minimal ambient light. Spread a drop of bonding agent into open cusps. Cure the bonding agent for 20 seconds.

Using a dental curing light, using a blade, scrape away any excess bonding agent. It is important to ensure that excess composite material does not overflow to adjacent teeth. This prevents misrepresentation of the tooth as it is compressed into the bony socket.

Now place a thin layer of flowable dental composite on the surface and spread it into the grooves between the molars. Once spread, expose this compound to curing light for 30 seconds. Next, build up three to four millimeters of dental composite on the occlusal plane of interest and cure it with 30 seconds of light exposure.

After turning the lights back up, use a straight edge and a high speed handpiece with a diamond burr to remove excess composite and level the top side of the composite buildup into a flat surface. This ensures that the load will be applied evenly when completed. Store the specimen in TBS with antibiotics until it is tested.

To mechanically test the specimen first, secure it between the anvils of the loading device. Next, place an articulating paper on the surface of the composite. Then apply a small load to check the uniformity of the loading.

Concentric loading is indicated by an even distribution of markings to keep the specimen hydrated during testing, soak a tissue and TBS and place it around the specimen. Also fill the reservoir carved into the specimen with TBS. Using the software, apply a peak load and displacement rate to compress the molar immobilized.

On the A FM stub, the soft tissue can be stained with PTA. To enhance the x-ray images, backfill 5%PTA into a 1.8 milliliter carpule. Using a syringe slowly over five minutes, inject the PTA into the PDL space adjacent to the region of interest.

Repeat the injection four more times for a total injected volume of nine milliliters. After completing the injections, the specimen can be soaked overnight. In PTA prior to x-ray analysis during the loading cycle, there is an expected period of backlash when the gears switch in their motion from closing to opening of the jaws.

This lasts about three seconds and is seen regardless of loading conditions. The response to this backlash is strongest during rigid body loading. By comparison, the magnitude of the backlash response is less.

With the bone PD L tooth specimens, it is also lower with polymethyl alane specimens, but not quite as low as with bone PD L tooth specimens compared to rigid bodies, the complex and poly dimethyl suboxane specimens are also significantly less.Stiff. XCT scans of a typical non-ST stain specimen clearly showed the relationship of the tooth within the alveolar bone socket. However, non mineralized tissue like the PDL cannot be distinguished without the use of a enhancing stain.

Using a contrast enhancer such as PTA, the soft tissue becomes visible in the XCT scan at a higher magnification. Fibers even become visible within the PDL space. Specimens could be loaded ally, such as in this tooth bone relationship at 15 newtons or specimens could be loaded.

Eccentrically resulting in increased displacement of the tooth and a different tooth socket configuration from concentric loading. Thermograms were used to compare the effect of the two loading schemes. Both schemes caused the tooth to displace vertically, but eccentric loading added an additional rotational path to the tooth movement.

After watching this video, you should have a good understanding of how to prepare and mechanically test a dental ovular complex using an init loading device coupled to a micro XT microscope.