Photoelastic Stress Induced by Maxillary Denture on the Mandibular Denture and Overdentures Lined with Silicone-based Material

Objectives: This study evaluated the stress induced by maxillary denture over mandibular denture and overdentures lined with silicone-based material. Materials and Methods: Three maxillary dentures, a mandibular denture, an overdenture supported by a single implant, and other supported by two implants were made for the following groups: MCD—Mandibular complete denture lined with silicone-based material, OSI—Overdenture lined with silicone-based material supported by single implant, and OTI— Overdenture lined with silicone-based material supported by two implants. The mandibular photoelastic model was axially loaded by the maxillary denture with intensities of 10, 20, or 30 kgf. Photoelastic analysis took place with the maxillary denture in maximum intercuspation with the mandibular prostheses. Results: Photoelastic analysis showed that the 10 kgf load promoted in the mandibular denture greater stress along the photoelastic model mainly in the anterior region. Stress occurred around the single implant with higher intensity at the apex. Stress occurred between the two implants and no stress was shown along the implants and apices. For 20 kgf, stress occurred in the anterior region of the mandible denture; Higher stress is shown around the single implant and apex and smaller at the mandible left side. Stress occurred between the two implants, and few stress at the apex of the left implant. For 30 kgf, stress occurred in the anterior region of the mandible with more intensity on the left side. Stress is shown around and at the implant apex and both mandible frontal sides. Stress is shown between the two implants and little stress at the apex of the left implant. Conclusions: The lined overdentures supported by single or two implants exhibited stress concentration in the implant region compared to lined mandibular denture showing stress along the mandible body. The stress in the overdentures occurred mainly around the single implant or between the two implants. The increase in load intensity had little influence on the increase in stress for the prostheses with lined bases. Clinical Relevance: Intercuspation in the overdenture must have the same importance given to the vertical relationship to relieve the chewing effort in overdenture lined with silicone-based material.