Accuracy of 3D Printed Maxillary Complete Dentures Compared With Conventional Complete Dentures: Non-Randomized Control Trial

Conventional complete dentures have been used as a clinically accepted prosthetic treatment for completely edentulous patients for almost a century. [1] One of its advantages is ability to customize teeth arrangement and to check each step of the preceding steps before the delivery stage.

Conventional complete dentures fabrication consist of several steps of recording, transferring, evaluating, and creating artificial substitutes for patient's teeth and gingiva which must be in harmony with patient's mouth and face. All this steps demand high experience, artistic, and skillful operator and technician.

However denture processing results in polymerization shrinkage of the resin (due to flask cooling), and distortion of the denture base (due to stress release after denture base removal from the stone cast), and decreasing the accuracy and denture adaptation. [2] These dimensional changes increase the gap between the denture base and underlying mucosa, resulting in an ill-fitting denture.[3] Denture adaptation and fitting plays a crucial role in complete denture retention (by physical means), stability, and patient comfort. [4]

Also, flask closure must be done under considerable pressure to ensure metal-to-metal contact between the halves of the flask to confine the resin inside the mold with no excess.[5] In addition to the inherent processing shrinkage and/or expansion properties of the acrylic resin.[6] Researchers tried to overcome these disadvantages by changing the technique of polymerization of the resin, by using of microwave energy, dry heat, and visible light.[7] But unfortunately researchers found that, Discrepancies in the base adaptation shown by several techniques are not easily corrected after complete denture processing.[8] Denture base adaptation to the stone cast is usually not satisfactory, especially in the midline section of the central portion of the posterior border.[9] To overcome the previous disadvantages computer aided manufacturing technology was applied to complete dentures. Some advantages of digitally fabricated complete dentures are 1) reduced number of patient visits; 2) superior strength and fit of dentures; 3) omitting multiple error-introducing steps such as impression, waxing, and casting.[10] 4) reduced cost for patient and clinician; 5) easy denture duplication (due to stored digital data); 6) standardization of clinical research on complete dentures and implant-retained overdentures.

To fabricate physical prototype (model) there are two different approaches: subtractive and additive manufacturing.