Fracture strength and three-dimensional marginal evaluation of biocompatible high-performance polymer versus pressed lithium disilicate crowns.

STATEMENT OF PROBLEM: Despite the acceptable physical properties of biocompatible high-performance polymer (BioHPP), little is known about the marginal accuracy and fracture strength of restorations made from this material. PURPOSE: This in vitro study assessed the marginal and internal adaptation and fracture strength of teeth restored with lithium disilicate (LD) ceramics and BioHPP monolithic crowns. MATERIAL AND METHODS: Twenty-four extracted premolars were prepared for complete coverage crowns and divided into 2 groups to receive pressed IPS e.max LD, or computer-aided design and computer-aided manufacturing (CAD-CAM) BioHPP monolithic crowns. After adhesive cementation, the marginal and internal adaptations of the restorations were evaluated by microcomputed tomography at 18 points for each crown. Specimens were subjected to 6000 thermal cycles at 5 °C and 55 °C and 200 000 load cycles of 100 N at a frequency of 1.2 Hz. The fracture strength of the restorations was then measured in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed via an independent-sample t-test (α=.05). RESULTS: The mean ±standard deviation of marginal gap was 138.8 ±43.6 µm for LD and 242.1 ±70.7 µm for BioHPP groups (P=.001). The mean ±standard deviation value of absolute marginal discrepancy was 193.8 ±60.8 µm for LD and 263.5 ±97.6 µm for BioHPP groups (P=.06). The internal occlusal and axial gap measurements were 547.5 ±253.1 µm and 197.3 ±54.8 µm for LD (P=.03) and 360 ±62.9 µm and 152.8 ±44.8 µm for BioHPP (P=.04). The mean ±standard deviation of internal space volume was 15.3 ±11.8 µm³ for LD and 24.1 ±10.7 µm³ for BioHPP (P=.08). The mean ±standard deviation of fracture strength was 2509.8 ±680 N for BioHPP and 1090.4 ±454.2 MPa for LD groups (P<.05). CONCLUSIONS: The marginal adaptation of pressed lithium disilicate crowns was better, while BioHPP crowns displayed greater fracture strength. Marginal gap width was not correlated with fracture strength in either group.

Recent Approaches to Enhance Osteogenesis of Dental Pulp Stem Cells on Electrospun Scaffolds.

Critical-sized bone defects are a challenging issue during bone regeneration. Bone tissue engineering is aimed to repair such defects using biomimicking scaffolds and stem cells. Electrospinning allows the fabrication of biocompatible, biodegradable, and strengthened scaffolds for bone regeneration. Natural and synthetic polymers, alone or in combination, have been employed to fabricate scaffolds with appropriate properties for the osteogenic differentiation of stem cells. Dental pulps are rich in stem cells, and dental pulp stem cells (DPSCs) have a high capacity for proliferation, differentiation, immunomodulation, and trophic factor expression. Researchers have tried to enhance osteogenesis through scaffold modification approaches, including incorporation or coating with mineral, inorganic materials, and herbal extract components. Among them, the incorporation of nanofibers with hyaluronic acid (HA) has been widely used to promote osteogenesis. In this review, the electrospun scaffolds and their modifications used in combination with DPSCs for bone regeneration are discussed.