Evaluation of fracture resistance and color stability of innovative esthetic crowns for primary posterior molars

Abstract

Purpose: To evaluate color stability and fracture resistance of CAD/CAM and manually fabricated tooth colored materials as crowns on primary molars. Methodology : Eighty epoxy replicas (Vertex-Dental B.V., The Netherlands) of minimally prepared primary molar were constructed to receive a tooth colored crown. Replicas were assigned into 4 groups (n=20) according to crown material used: CAD/CAM PMMA blocks (Telio Cad, Ivoclar Vivadent AG, Liechtenstein) [CC], self-polymerizing temporary resin material [SP] (Snap, Parkell, NY 11717 USA), auto-mix temporary resin material [AT] (Telio CS C&B Ivoclar Vivadent AG, Liechtenstein), and thermoplastic resin material [TP] (DurAcetal, Myerson LLC, Chicago, IL, USA). After cementation using glass ionomer cement (Vivaglass CEM, Ivoclar Vivadent AG, Liechtenstein), all specimens were thermo-cycled for 1000 cycles. Tooth shade was recorded using spectrophotometer , after storing in: orange juice, and carbonated beverage. Fracture resistance was assessed by axially loading the crowns using a universal testing machine . Data were analyzed using one-way analysis of variance and post hoc tests (α=0.05).Results: Spectrophotometric analysis revealed unacceptable color change of manually fabricated crowns; SP (∆E =5.4 ± 1.6), AM (∆E =6.7 ± 1.2) and TP (∆E =4.4 ± 2.5). On the other hand, CC crowns demonstrated high color stability (∆E=1.7 ± 0.2). CAD/CAM crowns demonstrated significantly higher fracture resistance (1417.9 ± 62 N) compared to manually fabricated crowns (SP=1096 ± 50, AM=989 ± 41 and TP=1297 ± 45).Conclusions: CAD/CAM PMMA crowns revealed superior fracture resistance and color stability properties suitable for long-term clinical performance within the primary molars.

The effect of thermo-cycling on fracture strength of 3D printing and PMMA interim prostheses

“…All of those materials also have the benefit of being quickly and easily mended intra-orally. Because they are made to order, they are more suited to the prepared tooth than prefabricated equivalents (15) . Self-polymerizing PMMA materials don't need any special instrument and can be easily fabricated and have low-cost.…”

The Effect of Thermo Cycling on Fracture Resistance Of Temporary Prosthesis Fabricated By CAD/CAM With Composite- Based Material

“…There are certain limitations to chair-side fabrication of interim restorations, including the possibility that the mixing processes and filling the external mold may introduce voids that could impair the restoration's mechanical strength, surface texture, and accurate fit. (6) .Bis-Acryl and Bis-GMA based materials are superior in their color stability, mechanical properties and have less polymerization shrinkage compared to acrylic resin based materials (7). The use of CAD/CAM systems in dentistry has increased significantly over the past ten years as a result of developments in the acquisition of intraoral images, the creation of design and production technologies, and the accessibility of cutting-edge materials for dental restorations.…”