Marginal adaptation of zirconia‐reinforced lithium silicate overlays with different preparation designs

Abstract

Objective: Following the advent of strong adhesive bonding, the conservative tooth preparation designs without a retentive form gained increasing popularity. This study aimed to evaluate the marginal adaptation of zirconia-reinforced lithium silicate (ZLS) overlays with different preparation designs. Materials and methods: Forty sound human maxillary first molars were collected and divided into four groups (n = 10) according to their preparation design for the fabrication of ZLS overlays: (O) anatomical occlusal reduction, (OS) anatomical occlusal reduction with rounded shoulder, (OG) anatomical occlusal reduction with a central groove, and (OSG) anatomical occlusal reduction with rounded shoulder and central groove. A video measuring machine (VMM) was used to measure the marginal gap. Statistical analysis was carried out using one-way ANOVA followed by paired t test and Tukey's test (α = .05). Results: The gap size was significantly different between the groups both before (P = .004) and after (P = .008) cementation, and it was significantly smaller in group O than group OSG (P = .002 before and P = .004 after cementation). Marginal gap increased in all groups following cementation (P < .001). Conclusions: Group O showed comparable marginal adaptation with groups OS and OG while group OSG with the most complex design showed the lowest marginal adaptation for ZLS overlays. Clinical Significance: According to the results of this in vitro study, it may be stated that for defect-free teeth requiring occlusal restoration, the occlusal surface preparation alone would suffice to achieve optimal marginal adaptation, and retentive and more invasive preparation designs are not required.

Marginal adaptation of three-unit interim restorations fabricated by the CAD-CA systems and the direct method before and after thermocycling

“…This technique has drawbacks such as difficult differentiation between the tooth structure and the most inferior part of the finish line margin, and advantages such as being faster, and having lower cost since it does not require procedures such as sectioning of specimens. Also, this technique has lower risk of cumulative errors that occur in multi-step procedures ( 24 , 25 ).…”

Mechanical Behavior of Different Restorative Materials and Onlay Preparation Designs in Endodontically Treated Molars

“…When comparing different preparation geometries, the teeth that presented both the least invasive and retentive preparations proved to be more resistant to fracture [39]; in addition, both lithium-disilicate and leucite-reinforced glass ceramic restorations appear to be promising for clinical application in preparations without retention forms [40]. For marginal adaptation, teeth with the most complex preparation design showed inferior marginal adaptation when compared to those with more simplified and less retentive geometries [41]. Clinically, the studies that evaluated the execution of restorative treatments with preparations without emphasis on the retention method were promising, recommending more and more the importance of the conservation of the remaining healthy dental structure [28], both for resin and ceramic restorations [10,11].…”

Differences in Supragingival Microbiome in Patients with and without Full-Crown Prostheses

“…Full-crown restoration is the main treatment for tooth or dentition defects [ 26 , 27 ]. Porcelain crowns are low cost and easy to clean, and all-ceramic crowns have good biocompatibility and aesthetic appearance; both are still commonly used in dental prostheses.…”