Posterior minimally invasive full‐veneers: Effect of ceramic thicknesses, bonding substrate, and preparation designs on failure‐load and ‐mode after fatigue

Abstract

Objective To evaluate the effect of ceramic thicknesses, bonding surface (enamel vs. dentin), and preparation design (box vs. no box) on the fatigue survival and failure load of minimally invasive full‐veneer restorations. Materials and Methods Human‐premolars (n = 60) were divided into five test groups (n = 12). All teeth received full‐veneer preparation with the following occlusal/labial thicknesses: standard: 1.5/0.8 mm; thin: 1.0/0.6 mm; ultrathin 0.5/0.4 mm. Preparations for each ceramic thickness were refined in enamel (E‐1.0 and E‐0.5) or dentin (D‐1.5, D‐1.0, and D‐0.5). Control groups DB‐1.5, EB‐1.0, and EB‐0.5 received box preparations. Monolithic lithium disilicate restorations (IPS‐e.max‐Press, Ivoclar Vivadent) were adhesively cemented (Syntac‐Classic/Variolink‐II, Ivoclar Vivadent) and subjected to cyclic mechanical loading (F = 49 N, 1.2 million cycles) with simultaneous thermocycling (5–55°C). All specimens were exposed to single load‐to‐failure. Pair‐wise differences were calculated by using a linear regression model and Student–Newman–Keuls method (p < 0.05). Results All full‐veneers of group D‐1.5, E‐1.0, E‐0.5, DB‐1.5, EB‐1.0, and EB‐0.5 survived fatigue. Two full‐veneers (D‐1.0 and D‐0.5) revealed cracks during fatigue, resulting in an overall fatigue survival rate of 98.1%. Mean load‐to‐failure values (N) were as followed: 1005 (D‐1.5); 866 (D‐1.0); 816 (D‐0.5); 1495 (E‐1.0); 1279 (E‐0.5); 1129 (DB‐1.5); 1087 (EB‐1.0); and 833 (EB‐0.5). Irrespective of ceramic thicknesses, enamel‐based full‐veneers resulted in higher failure loads than dentin‐based restorations. Box preparation reduced the failure loads of thin and ultrathin enamel‐based restorations. Conclusion All tested monolithic lithium disilicate full‐veneer restorations exceeded physiological masticatory forces. Minimally invasive full‐veneer restorations with enamel as a bonding surface and a non‐retentive preparation design showed superior performance. Clinical Significance Enamel‐based non‐retentive full‐veneers made of monolithic lithium disilicate may serve as a reliable and esthetical minimally invasive treatment option for premolars.

Load-bearing capacity of pressable lithium disilicates applied as ultra-thin occlusal veneers on molars

“…Static loading of the specimens led to all type of failures from no visible damage of the restoration to complete fracture of the restoration-cement-tooth complex. Most of the specimens showed a cohesive fracture of the restoration and of the cement layer (score 2) which was also found to be the predominant failure mode in comparable studies (Gierthmuehlen et al, 2022;Ioannidis et al, 2020). In the present investigation, static loading forces went up to 2'500 N. Clinically, maximum masticatory forces in the posterior region range from 200 to 540 N and reach up to 800 N in patients suffering from bruxism (Bates et al, 1975).…”

Minimally invasive CAD/CAM lithium disilicate partial‐coverage restorations show superior in‐vitro fatigue performance than single crowns

“…If the restoration needs to be renewed, this could be beneficial, since tooth substance will be preserved. Other in‐vitro studies with minimally invasive LDS restorations on human premolars and molars confirmed the observed failure modes with mainly cohesive ceramic fractures without involvement of the tooth for thin restorations 24,49 …”

Retentive Strength of CAD/CAM-Fabricated All-Ceramic Crowns Luted on Titanium Implant Abutments Using Different Ceramic Materials and Luting Agents: An In Vitro Study

“…It is well known that in addition to marginal adaption, high fracture strengths, and sufficient aesthetics, one of the most important aspects for long-term survival of luted fixed partial dentures (i.e., crowns) is the fixation of the restoration achieved as a quality factor for long-term success [ 17 ]. Thus, in several studies the bond strength was used as a prognostic factor to evaluate clinical suitability, i.e., for veneer restorations on natural teeth [ 18 ]. However, the question arises as to how it behaves with ceramic restorations on titanium abutments.…”