Effect of First Premolar Retainer Design on Tensile Bond Strength in Three-unit Fixed Partial Dentures: An In Vitro Study
Year: 2025
Type: article
Abstract: Aim: To compare the tensile bond strength of 3-unit fixed dental bridges using four different first premolar retainer designs: Full coverage on a sound abutment, full coverage on a post and core build-up, endocrown, and Sharonlay (SL).Materials and methods: Forty human mandibular teeth (20 first premolars and 20 first molars) were used to fabricate 23-unit fixed dental bridges replacing the second premolar.Teeth were mounted in epoxy resin blocks, with each bridge supported by one premolar and one molar, resulting in a total of 20 specimens.These were evenly assigned to 4 main groups (n = 5 per group) according to first premolar retainer designs: Full coverage on a sound tooth (FC), full coverage on a fiber post and composite core build-up (PC), endocrown with 2.5 mm intraradicular extension (EC), and SL with 5 mm intraradicular extension.All teeth were scanned using the Medit i700 intraoral scanner, and zirconia bridges were digitally designed, milled, and cemented using dual-cure resin cement under a 5-kg load.Tensile bond strength was tested using a universal testing machine with a constant crosshead speed; then data were collected for appropriate statistical analysis.Results: The highest mean tensile bond strength was recorded in the FC group (431.82 ± 18.90), followed by the PC group (212.93 ± 5.84), endocrown (EC) group (181.97 ± 12.06), and SL group (156.92 ± 10.75).Statistical analysis showed a significant difference among the groups (p < 0.001).Conclusions: Within the limitations of this in vitro study, the full coverage retainer demonstrated the highest tensile bond strength among the evaluated designs, while the SL showed the lowest.Retainer design significantly affects the bonding performance of three-unit fixed dental bridges.Clinical significance: This study demonstrates that retainer design significantly impacts the tensile bond strength of three-unit fixed dental bridges.Full coverage retainers provide superior bond strength; therefore, it is recommended that clinicians prioritize full coverage designs to enhance the longevity and stability of dental prostheses.
Authors: Cherif Adel Mohsen, Nagia Fathy Abd-Elghany
Institutions: Nahda University, Minia University
Language: English
Subfield: Orthodontics
Field: Dentistry
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W4413374331