Four-year clinical performance and marginal analysis of pressed glass ceramic inlays luted with ormocer restorative vs. conventional luting composite
Introduction
All-ceramic inlays are a well-accepted treatment option for decayed teeth.1, 2, 3 The leucite-reinforced glass ceramic IPS Empress (Ivoclar Vivadent, Schaan, Principality of Liechtenstein) is one of the most successful ceramic types for inlays and onlays.4 In general, prospective clinical studies report promising long-term performances of different inlay systems,1, 2, 3, 4, 5 especially for CAD/CAM ceramic inlays.6, 7, 8, 9, 10, 11 However, a recent study demonstrated that technique sensitivity is still a major problem and operator skills are fundamentally affecting clinical outcome.10 Clinical aspects of adhesive luting ceramic exhibit two predominant problems: (1) the brittleness of ceramics leads to bulk fractures as main failure reason,1, 3, 4, 11, 12, 13 but meticulous luting and polishing guarantee for acceptable fracture rates14, 15, 16, 17 and (2) postoperative hypersensitivities are still reported to be between 3 and 5% in recent clinical studies observing tooth-colored inlays.3, 10 Nevertheless, annual failure rates of 1–1.5% are acceptably low.12, 3, 7, 8
From both preclinical and clinical investigations it is known that adhesive luting is still technique sensitive.10, 15, 18 Therefore, simplified luting cements such as self-adhesive cements have been suggested for adhesive luting, however, it is proven that recent self-adhesive cements cannot compete with conventional etch-and-rinse-systems.15, 19, 20 On the other hand, also restorative composites have been proposed to be suitable for adhesive luting when the ultrasonic insertion technique is used for placement of the inlays.17 This aspect was one focus of the present clinical trial, to investigate the restorative ormocer material Definite acting as luting resin composite.
For both adhesive luting and direct restorative therapy, it is still not fully understood whether selective enamel etching combined with the self-etch approach or the etch-and-rinse technique for both enamel and dentin are more appropriate for long-term success of bonded restorations.21, 22, 23, 24 Therefore it was a side aspect of the present study to elucidate that particular question.
The aim of the present prospective clinical two-center study was to investigate the clinical behaviour of adhesively luted pressed glass ceramic inlays and to investigate marginal adaptation of selected samples under a SEM. Two different adhesive/luting composite combinations were used by four different dentists in a private practice and a dental school. The null hypothesis was that there would be no difference between materials used for luting.
Section snippets
Materials and methods
All patients were required to give written informed consent. The study was conducted according to EN 540 (Clinical investigation of medical devices for human subjects, European Committee for Standardization), and inspected and approved by an ethics committee (University of Erlangen-Nuremberg). The patients agreed to a recall programme of 4 years consisting of five appointments. Patients selected for this study met the following criteria: (1) absence of pain concerning the tooth to be restored;
Results
One patient with three restorations/two Definite, one Variolink) missed the final recall. After 48 months of clinical service, four restorations in four patients (three luted with Definite, one with Variolink) failed due to inlay fracture (n = 3) and tooth fracture (n = 1). 50 inlays were in good condition (survival rate 94.1%, median survival time 4.73 years (95% confidence interval ± 0.103; survival analysis by Kaplan–Meier algorithm) (Fig. 1). Survival rate after 4 years was 93.3% for Definite vs.
Discussion
The present two-center clinical study aimed to investigate clinical performance of pressed glass ceramic inlays with respect to luting materials’ influence. Therefore, the study was carried out with the same ceramic (Cergogold) and different materials being used for bonding and adhesive luting (Definite + Definite Multibond/Syntac + Variolink Ultra). Due to the high viscosity of the luting resin composites, ultrasonic activation of the thixotropic materials was necessary in accordance to the
Acknowledgement
The present study was supported by Degudent, Hanau, Germany.
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