Edentulism continues to be a significant public health concern, particularly among the elderly population¹. Despite improvements in preventive dentistry, complete dentures remain a primary modality for rehabilitation of edentulous patients. Polymethyl methacrylate (PMMA) has long been considered the material of choice for denture bases due to its favorable esthetics, ease of processing, dimensional stability, and cost-effectiveness². However, PMMA exhibits inherent brittleness and relatively low fatigue resistance³. Denture fracture remains one of the most common complications in removable prosthodontics⁴. Epidemiological studies indicate that maxillary denture fractures occur approximately twice as frequently as mandibular fractures⁵. Failures may occur extraorally due to impact forces or intraorally due to cyclic flexural fatigue under masticatory stresses⁶. Flexural strength is one of the most clinically relevant mechanical properties of denture base materials, as it reflects resistance to deformation under functional loads⁷. Various modifications such as fiber reinforcement, rubber modification, cross-linking, and metal incorporation have been proposed to improve fracture resistance⁸-¹⁰. Metal reinforcement in the form of mesh or frameworks has been used to enhance structural stability of dentures¹¹. By redistributing stresses and limiting crack propagation, metallic reinforcement may significantly improve mechanical performance¹²-¹⁴. The present in vitro study was undertaken to evaluate whether incorporation of mesh reinforcement significantly improves flexural strength compared to conventional non-reinforced heat-cure denture base resins. OBJECTIVE To comparatively evaluate the flexural strength of conventional heat-cure denture base resins fabricated with and without mesh reinforcement.

Study Design: An in vitro experimental study conducted in 2016 at the Department of Prosthodontics, Jaipur Dental College, in collaboration with Central Institute of Plastic Engineering & Technology. Materials Used • Lucitone 199 (Dentsply) • Acralyn-H (Asian Acrylates) • Pyrax (Pyrax Polymers) • DPI Heat Cure (Dental Products of India) • Gold-plated mesh (0.4 mm thickness) Specimen Fabrication A metal die was fabricated to standardize specimen dimensions (40 × 40 × 3 mm) for flexural strength. Eighty wax patterns were prepared and invested using conventional flasking technique. Specimens were divided into two groups. A total of 80 wax patterns were fabricated with different denture base materials. Specimens were divided into 2 groups. In group A, 40 samples were made different denture base materials reinforced with mesh and in group B, 40 samples were made without mesh reinforcement. All specimens were processed using a short curing cycle: • 73°C for 90 minutes • Terminal boil at 100°C for 30 minutes Specimens were bench cooled, finished, polished, and measured using a digital vernier caliper. Flexural Strength Testing: Flexural strength was evaluated using a three-point bending test on a SHIMADZU-AGS universal testing machine. Parameters: • Crosshead speed: 1 mm/min • Span length: 20 mm • Central loading until fracture Flexural strength was calculated using: Flexural strength = 3pl / 2bd2 Where p - is the peak load l -is the span length b - is the sample width and d - is the sample thickness Statistical Analysis: Data were analyzed using SPSS 17.0 software. Student’s t-test was applied. Statistical significance was set at p < 0.05. A B C D E A) Metal Die; B) Packing with Mesh; C) Finished Samples; D) Load Applied on the Specimen; E) Fractured Specimen

Table 1: Comparison Between Reinforced and Non-Reinforced Groups GROUP N MEAN (MPA) STD. DEVIATION P-VALUE Mesh Reinforced 40 80.4792 34.20231 0.000 Without Mesh 40 57.3083 18.44891 The reinforced specimens demonstrated a mean flexural strength of 80.4792 MPa compared to 57.3083 MPa in non-reinforced specimens. This represents a 40.43% increase in flexural strength following mesh reinforcement. The difference was statistically highly significant (p=0.000).

Fracture of polymethyl methacrylate (PMMA) denture base resin continues to be a persistent clinical complication in removable prosthodontics despite decades of material modifications. The majority of denture fractures occur either due to impact forces outside the oral cavity or due to cyclic flexural fatigue intraorally under functional masticatory stresses⁵,⁶. Flexural fatigue, particularly in maxillary dentures, is considered one of the primary etiological factors contributing to midline fractures⁵. Hence, evaluation and enhancement of flexural strength remains of paramount importance in improving the longevity of complete dentures. The present in vitro study demonstrated that incorporation of mesh significantly increased the mean flexural strength of denture base resins by 40.43%, with the reinforced group showing 80.4792 ± 34.20231 MPa compared to 57.3083 ± 18.44891 MPa in the non-reinforced group (p=0.000). This statistically highly significant difference confirms that metal mesh reinforcement substantially improves resistance to bending forces. Flexural strength is a collective representation of tensile, compressive, and shear stresses acting simultaneously on a material⁷. During mastication, dentures are subjected to complex stress distributions. PMMA, being relatively brittle with low fatigue resistance³, is prone to crack initiation and propagation under repetitive stress. Metal reinforcement modifies this stress distribution pattern. The embedded mesh functions as a stress-absorbing and load-bearing scaffold, redistributing tensile stresses away from the acrylic matrix¹¹. This biomechanical mechanism likely explains the significant enhancement observed. Zeynep D et al. reported significantly higher fracture resistance in reinforced acrylic denture bases¹². Bassi T et al. demonstrated that metal reinforcement significantly improved transverse and impact strength¹³. Dandekeri S et al. observed higher flexural strength in reinforced resins compared to conventional materials¹⁴. Although high-impact resins improve impact resistance, literature shows inconsistent superiority in flexural performance³,⁵. In contrast, metal mesh provides structural reinforcement without altering polymer chemistry. Clinically, reinforcement is particularly indicated in patients with heavy occlusal loads, parafunctional habits, or history of repeated fracture⁵. Varghese K et al. emphasized that metal scaffolding enhances fracture resistance by withstanding stress concentration¹¹. Despite its benefits, mesh reinforcement may increase cost and fabrication complexity¹⁵. However, in high-risk cases, mechanical advantages outweigh these limitations. The statistically highly significant difference (p=0.000) and 40.43% increase in flexural strength indicate strong clinical relevance. Limitations include in vitro design and absence of fatigue cycling. Future long-term clinical studies are recommended.

Mesh reinforcement significantly increases flexural strength of heat-cure denture base resins. Reinforced specimens demonstrated a 40.43% higher mean flexural strength compared to conventional non-reinforced resins. Mesh reinforcement may be recommended in patients with high occlusal stress or repeated denture fracture. ACKNOWLEDGEMENT The authors acknowledge Jaipur Dental College and the Central Institute of Plastic Engineering & Technology for laboratory and testing support. The authors also thank The VAssist Research team (www.thevassist.com) for its contribution in manuscript editing and submission process. Conflict of Interest: None declared. Source of Funding: No external funding received.

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