Mechanical Behaviors of a New Polymer-Based Restorative Material for Immediate Loading: An In Vitro Comparative Study  
[PERSON]  
1 Department of Medicine, Surgery, and Pharmacy, University of Sassari, 07100 Sassari, Italy; [EMAIL_ADDRESS] (M.P. ); [EMAIL_ADDRESS] (A.D.M. ); [EMAIL_ADDRESS] (I.K. ); [PERSON]ADDRESS] (S.M.M. ); [PERSON]ADDRESS] (A.L.L.) The intricate landscape of dental materials and techniques continually evolves to address the challenges in maintaining oral health. Dental professionals navigate a spectrum of options, from testing materials like adhesives, metals, porcelains, polymers, and ceramics to the burgeoning advancements in dental implants. While implants represent a gold standard for rehabilitating compromised teeth, preserving viable teeth remains a priority. Modern approaches, such as guided surgery, harness digital technologies to meticulously plan implant placements, showcasing promising long-term success rates. However, challenges persist in achieving immediate function, prompting ongoing research into enhanced implant surfaces. The prevalent use of polymers, particularly poly(methyl methacrylate) or PMMA, underscores the quest for durable interim restorations, albeit with concerns regarding fractures under masticatory forces. Efforts to innovate involve exploring novel composite polymers, seeking alternatives to reinforce PMMA interim restorations. This dynamic landscape calls for rigorous comparative studies to ascertain the efficacy and resilience of emerging materials in dental applications. In recent years, the use of dental implants has become the gold standard to rehabilitate hopeless or missing teeth; however, attempts should be made first to save maintainable teeth [6]. Industries are focusing their effort to improve the protocols for immediate function. Within these, enhancement of implant surfaces allows better and faster osseointegration, even in compromised scenarios. However, immediate function remains a challenge in dentistry [6; 7; 8]. Computer-assisted, template-based surgery, also known as guided surgery, takes advantage of modern digital technologies to guide implants in the optimal, virtually planned, prosthetically driven position. It has been demonstrated to have high long-term success and a low incidence of peri-implantitis, over a period of 10 years, with the lower value of bone remodeling compared to a free-hand approach [9; 10; 11]. Guided surgery is performed at the basis of the three-dimensional view of the bone, anatomical structures, and final prosthetic visualization during the thorough virtual planning process. This allows the surgeon to plan the implant position and to prepare a fixed interim restoration, making implant placement and immediate function safer and quicker. Several materials have been proposed to fabricate implant fixed interim restorations. Among these, polymeric materials are commonly used as temporary materials on the basis of their enhanced clinical performance in comparison with alternative options [12; 13]. Poly(methyl methacrylate) or PMMA represents the most used polymeric material, which has been used for some time in dentistry. In the last year, milled PMMA has replaced conventional processed PMMA in order to overcome its drawbacks. However, although interim restorations milled from high-density PMMA demonstrated 35% higher flexural strength, metal reinforcement is still recommended [14]. Fractures are the main complication associated with PMMA, which gradually develop during the first period of function and typically result from exposure to high mastication forces [14; 15; 16]. An option to strengthen the PMMA fixed interim restorations is to include a metallic bar, enhancing the mechanical properties of PMMA temporary restorations [17]. With the aim of simplifying the workflow for immediate loading in complete dedulous or failing dentition cases, several materials and techniques have been proposed [18; 19]. However, there has yet to be a consensus on the best material.