Influence of the Crystallization Firing Process on Marginal and Internal Adaptation of Silicate-based Glass-ceramic Inlays Fabricated With a CAD/CAM Chairside System
Computer-aided design/computer-aided manufacturing (CAD/CAM) systems are widely used in dental treatment. Clinicians can use chairside CAD/CAM technology, which has the advantage of being able to fabricate inlays on the same day. We aimed to evaluate the effects of crystallization firing processes, fabrication methods (one-step and two-step), and materials on marginal and internal adaptations of silicate-based glass-ceramic all-ceramic inlays fabricated with CAD/CAM chairside systems. Ten artificial mandibular left first molars were prepared with standardized ceramic class II mesialocclusal (MO) inlay cavities. Optical impressions were obtained using CEREC Omnicam Ban. IPS e-max CAD (IE), (Ivoclar Vivadent, Schaan, Liechtenstein), Initial LiSi Block (LS) (Hongo, Bunkyoku, Tokyo, Japan), VITA Suprinity (SP), (Vita Zahnfabrick, Bad Säckingen, Germany), and Celtra Duo (CD) (Ivoclar Vivadent, Schaan, Liechtenstein) (n=10) were milled using CEREC MC XL (Bensheim, Germany). IE and SP were crystallization-fired using CEREC Speed Fire. The silicone replica technique was used for the measurement of internal (axial and pulpal walls) and marginal (cervical and occlusal edge) adaptations. The adaptations were measured using a thin layer of light-body polyvinyl siloxane impression material placed between the master tooth inlay preparation and restoration. Marginal and internal adaptations of IE, LS, SP, and CD were measured using a stereomicroscope (500×). For IE and SP, marginal and internal adaptations were measured before and after the crystallization firing process. Data analyses were conducted using one-way ANOVA and the Tukey test. For IE and SP, marginal and internal adaptations before and after the crystallization firing process were analyzed using the t-test. The significance level was set at α=0.05. One-way ANOVA revealed statistically significant differences in occlusal and cervical edge marginal adaptations among the material groups (p<0.001). The Tukey HSD test revealed a significant difference in marginal occlusal and cervical edge adaptations between LS and CD groups and IE and SP groups (p≤0.05). For IE and SP inlays, the t-test revealed a significant difference between occlusal and cervical edge adaptations before the crystallization firing process and those after the crystallization firing process, with the latter group showing a more significant discrepancy in adaptation than the former group (p≤0.05). Fabrication methods (one- and two-step) affected the marginal adaptation compatibility but not internal compatibility of MO inlays. The crystallization firing process affected the marginal adaptation of inlays using lithium silicate or lithium disilicate glass-ceramics. However, adaptation to the cavity was considered clinically acceptable for all materials.SUMMARY
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Prepared class II mesial-occlusal inlay. Mesial-occlusal inlay cavities with 2.0 mm deep occlusal box and an isthmus width of 3.0 mm. The gingival floor of each box had a mesiodistal width of 1 mm and an axial wall height of 1 mm.
Location of the points where the internal and marginal adaptations were measured. A: The cavity is divided into two halves, buccal and lingual B: Measurement points viewed from the buccal or lingual direction C: The cavity is divided into three parts, mesial and distal D: Measurement point viewed from the mesial or distal direction. The marks correspond as follows: ★ Pulpal wall ▲ Axial wall ● Occlusal edge ■ Cervical edge.
Internal and marginal adaptation measurements. A: Replica body. B: A guide is used to cut the center of the replica body mesial-distally C: A guide is used to cut the replica body buccal-lingually at two points D: Stereomicrograph of a section of the internal pulpal wall and marginal cervical edge E: Stereomicrograph of a section of the internal axial wall and marginal occlusal edge. The marks correspond as follows: ★ Pulpal wall ▲ Axial wall ● Occlusal edge ■ Cervical edge.
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