Influence of Alloy Composition and Fabrication Techniques on the Marginal and Internal Fit of Fixed Dental Prostheses: A Narrative Review.

For individuals who are partially edentulous, fixed dental prostheses (FDPs), such as single crowns and fixed partial dentures, are crucial for restoring function, aesthetics, and structural continuity. Accurate marginal and internal fit are crucial for the long-term success of these restorations because inconsistencies can lead to cement disintegration, plaque buildup, microleakage, secondary caries, periodontal breakdown, and pulpal irritation. These issues can eventually lead to restorative failure, which can include loss of retention or debonding of the restoration, fracture or chipping of the restoration or supporting tooth structure, recurrent infection necessitating restoration replacement, and, in extreme circumstances, the need for more involved procedures like endodontic therapy or tooth extraction. From a therapeutically relevant prosthodontic standpoint, this narrative review sought to assess how alloy composition and fabrication methods affected the marginal and internal fit of FDPs. Databases like PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), and EBSCOhost were used to search the literature for English-language research published between 1990 and 2025. Included were pertinent comparative studies, randomized and non-randomized trials, observational studies, validation studies, in vitro investigations, and review articles assessing titanium, nickel-chromium (Ni-Cr), and cobalt-chromium (Co-Cr) alloys made using direct metal laser sintering (DMLS) and conventional casting methods. According to the examined data, titanium alloys often exhibit less predictable marginal adaptation than Co-Cr and Ni-Cr alloys. Due to numerous technique-sensitive laboratory procedures, conventional lost-wax casting techniques demonstrated higher variability but produced clinically acceptable results. On the other hand, while internal fit varied based on workflow factors and post-processing procedures, available literature suggests that, especially DMLS and additive manufacturing techniques, may improve reproducibility and marginal accuracy in numerous tests. Clinically, better internal and marginal adaptation may eliminate chairside adjustments, increase the durability of restorations, and lessen biological problems. Overall, rather than being the product of a single material or fabrication method, restoration fit should be viewed as the consequence of an integrated interplay between alloy composition, fabrication workflow, and laboratory precision.