Reinforced Overdentures Using PREAT eFiber and Perma Mesh
Strengthen a prosthesis with this fabrication method
By James Davidge
When denture breakage problems arise due to faults in the original fabrication, it can be challenging to address them without needing to completely remake the prosthesis. However, there are ways to help reinforce and strengthen the existing denture in the laboratory in a time- and cost-effective manner. The following is a step-by-step guide to fabricate a fully internal framework in-lab in a fraction of the time it takes with conventional metal frames. As a technician and laboratory owner, the author has successfully used this method time and again for difficult cases.
A female patient in her mid-fifties presented for treatment. Her maxillary and mandibular ridges each had four Locator abutments with divergent angulation placement. The original dentures were not reinforced, had constant fractures, and needed repair often.
Master casts and record bases—with the final Locator housings in the baseplates for a stable occlusal plane record/gothic arch tracing and facebow mounting—were fabricated (Figure 1). Using this information, the author's laboratory was able to do an accurate analysis of the working dimensions and a try-in with teeth, verifying esthetics and function.
The overdentures were invested in the IvoBase flasks (Ivoclar Vivadent; ivoclarvivadent.com) with the permanent Locator housings engaged to the analogs using black processing caps. This is when fiber reinforcement could be added.
After the teeth were prepped by steam and sandblasted, a primer coat of the light-cure wetting agent was added to the basal surface of the denture teeth. They cured for 20 seconds with a UV light.
Next, PREAT's eFiber was added to the primed basal surface of the teeth (Figure 2). The eFiber has a very tacky consistency due to its BIS-GMA and PMMA-impregnated unidirectional composition. A hand instrument was used to tack the eFiber to the basal surface of the teeth and smooth out the remaining bit of the strand to the desired position (Figure 3). One advantage to using this material is that it can be cured in sections, making the trip around the flask more manageable (Figure 4).
Note that it is also possible to pre-grind a channel in the basal side of the teeth for even easier placement of the eFiber. Having gone through this process with and without a channel, the author has not determined if one is better than the other strength-wise as none of the dentures have broken. Grinding a channel is a personal preference.
Once the eFiber was tacked down and properly cured in place, then the regular denture processing was done. The dentures were re-articulated, ground down, and polished (pre-high-shine), then the second framework fiber reinforcement could be implemented. This author likes Perma Mesh by PREAT, a multidirectional, printed-glass dry mesh (Figure 5).
The denture was cut back 0.6 mm over the desired position-over the Locator housing sites on the lower and always over the incisive papilla and Locator housing sites on the upper (Figure 6).
Cut the Perma Mesh into multiple pieces. Lay one piece down (left to right) using the light-cure wetting agent, then another (right to left), overlapping each other where optimal strength is required. Once the mesh is in place, cure both wetting agent and mesh (Figure 7 and Figure 8). Next, mix an acrylic of choice and paint 0.75 mm of it to cover and seal the Perma Mesh (Figure 9). Conventionally cure the acrylic as indicated. Since the mesh is translucent, the fibers will not be visible or detected in any way on a denture polished to a high-shine (Figure 10). A laboratory can deliver a case like this with confidence (Figure 11 and Figure 12).
The goal is to add the right type of strengthener in the weakest location on a prosthesis using a simple, in-house technique that really works. Having used this process on over 20 cases (some even on over-bars with minimal clearance), the author can attest to the fact that none have ever broken or needed to be remade. This method, using eFiber and Perma Mesh, is an easy and effective solution to implement into a laboratory workflow.
Disclaimer: The statements and opinions contained in the preceding material are not of the editors, publisher, or the Editorial Board of Inside Dental Technology.
About the Author
James Davidge is a dental technician at Dental Works West in Arroyo Grande, California.
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