Analisis Distribusi Tegangan dan Persepsi Rasa Sakit pada Linggir Tajam dengan Ketebalan Silicone Soft Denture Liner Gigi Tiruan Lengkap dan Arah Beban Pengunyahan yang Berbeda Menggunakan Finite Element Analysis

Abstract

Decreasing masticatory performance is due to the inability to tolerate the masticatory load caused by tooth loss followed by ridge resorption. Fabrication of complete dentures (CD) is still one of the treatment choices. However, as resorption progresses, the residual ridge becomes narrow and sharp, referred to as knife-edge ridge. This causes the CD to destabilize and cause unequal stress distribution (SD) leading to mucosal pain that exceeds the pressure-pain threshold (PPT). Prosthodontic treatment that can be done is by adding Soft Denture Liner (SDL) to the CD. Silicone SDL (SSDL) is still the main choice due to its long-lasting elasticity compared to acrylic (ASDL), and easier to obtain. Application of SSDL can provide a “cushion effect” on the mucosa when CD is functioning, so that the SD is more even. To function optimally, SSDL should not be applied more than 4 mm or less than 2 mm thick. Choosing the ideal thickness of SSDL for knife-edge ridge can be tested in-silico using finite element analysis (FEA). In order to achieve a realistic result, CBCT was done on the mandible with knife edge ridge to obtain the anatomical model, intraoral scanning of knife-edge mucosa, and fabrication of the CD which will then be analysed for SD and pain perception of the CD with SSDL on knife-edge ridge with axial and oblique masticatory load of 100 N. From the results, it was found that the use of SSDL on CD can distribute stress more evenly than CD without SSDL. In Axial direction, CD with SSDL showed the maximum stress value less than PPT. In Oblique direction, SSDL with 3 and 4 mm on CD showed the value greater than PPT. In this study, there was a difference in the location of the maximum stress value on the mucosa under CD. In the axial load, the maximum stress value occurred in anterior mucosal area. While in the oblique load occurred in posterior area. This is because axial load is the main load during mastication with the direction of load falling along the tooth axis once the tips of the cups on the teeth are in contact with the fossa, so the drop point can be anterior or posterior. Meanwhile, the direction of the masticatory load in oblique is adjusted to the slope of the cusp on the posterior teeth of CD, therefore this load occurs mostly in the posterior. From the test results, it was found that the ideal thickness of SSDL on CD is 2 mm, because the maximum stress value obtained is still below PPT value in both axial and oblique loads. Therefore, the results of this study strengthened the previous studies and also provided clinical implications related to the ideal thickness of SSDL in CD with knife-edge ridge.