Abstract
Evaluation of the Effect of Zirconia and Titanium Abutments on Microleakage of Implant-Abutment Interface Under Oblique Cyclic Loading In Vitro
Highlights
It was generally reported that titanium abutments show smaller microgaps compared to zirconia abutments but tightening zirconia abutments from 20 N.cm to 35 N.cm reduces the size of the microgap.(23) Abdelhamed and colleagues compared the microleakage of the implant-abutment interface (IAI) in two types of abutments, zirconia and titanium, in non-loading conditions.(31) They stated that time, type of abutment, and amount of torque play a key role for leakage from the internal chamber of the implant to the external milieu while for leakage from the external milieu to the internal chamber, only two factors of time and type of abutment are effective.(31) Several studies
Figure 4b: Fuchsine penetration in samples of zirconia abutment group at ×75 magnification of electron microscope Based on the results of t-test (Table 2), it was found that the amount of microleakage following oblique cyclic loading in the group of zirconia abutments was significantly higher compared to the titanium abutment group (P=0.002)
When the abutment is placed on the implant, it creates a microspace called the IAI.(2) Studies have shown that oral microbiota can proliferate in this space and cause inflammation in the peri-implant tissues and adjacent bone.(2,33) Bacterial colonization in the IAI depends on several factors, including the precise adjustment between the implant components, the torque between these components, and the force exerted on the implants when placed in the oral cavity and function.(11) In the present study, to simulate the clinical conditions of occlusal force transfer in the oral environment on the abutments, the oblique force was used as cyclic loading
Summary
Microleakage through the gap at the implantabutment interface (IAI) is still one of the challenges of two-piece implant treatment.(1-8) In an in-vitro study, the prevalence of microleakage in Morse taper implants was reported to be 20%.(9) All two-piece implant systems include two main parts of endosteal fixture and prosthesis-supporting abutment.(10-12) Inevitably, in all two-piece implants, the gap size increases or decreases during the application of force to the assembly, which leads to a pumping effect.(13-15) The pumping effect is the passage of fluids when the implant is subjected to functional forces, which increases the concentration of bacterial metabolites in the peri-implant area.(16) Factors that affect the microleakage include the implant system used, the geometry of the IAI, the precision of fit, micromovements, the applied torque, and occlusal forces.(16-20)SH Naser mostofy,et alIn the event of microleakage, deep pockets containing anaerobic bacteria form around the implant within 3-6 months.(21) Following the pocket formation, bacterial adhesion, increased bacterial byproducts, and pre-implant boneloss will occur, which are the primary cause of long-term failures in the implant.(21-23)Various techniques have been proposed to reduce microleakage, including the use of different types of implant-abutment connection, the use of silicone gel sheets, application of different torques to connect implants and abutments, and the use of different types of abutment.(23-25) The material of the abutment has a definite effect on the aesthetic appearance and function of an implant restoration.(26) Titanium abutments are considered as the gold standard in implant reconstructions due to their good stability and acceptable biocompatibility.(26) Recently, the aesthetic needs of patients to reconstruct a single-tooth space by implant-based restoration, especially in anterior areas, have challenged clinicians.(27,28) The introduction of modern high-strength ceramic abutments has provided a new opportunity for the restoration of missing teeth in the esthetic zone. (26) So far, various bacteria or dyes such as fuchsine, rhodamine B, and toluidine blue, have been used to measure microleakage in crowns, composite restorations, and IAIs.(3,29,30) Smith and Turkyilmaz evaluated the sealing capability of titanium and zirconia abutments with two different screw torque values against Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum.(23) They showed that in titanium abutments, changing the amount of torque from 20 N.cm to 35 N.cm would not have a significant effect on microleakage. It was generally reported that titanium abutments show smaller microgaps compared to zirconia abutments but tightening zirconia abutments from 20 N.cm to 35 N.cm reduces the size of the microgap.(23) Abdelhamed and colleagues compared the microleakage of the IAI in two types of abutments, zirconia and titanium, in non-loading conditions.(31) They stated that time, type of abutment, and amount of torque play a key role for leakage from the internal chamber of the implant to the external milieu while for leakage from the external milieu to the internal chamber, only two factors of time and type of abutment are effective.(31) Several studies. (4,24) this study evaluated the effect of two types of abutments, zirconia and titanium, on the microleakage of the IAI under oblique cyclic loading in vitro. This study aimed to assess the effect of zirconia and titanium abutments on the microleakage of the IAI under oblique cyclic loading conditions.
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