Marginal and internal fit of zirconia copings obtained using different digital scanning methods

Abstract

The objective of this study was to evaluate the marginal and internal fit of zirconia copings obtained with different digital scanning methods. A human mandibular first molar was set in a typodont with its adjacent and antagonist teeth and prepared for an all-ceramic crown. Digital impressions were made using an intraoral scanner (3Shape). Polyvinyl siloxane impressions and Type IV gypsum models were also obtained and scanned with a benchtop laboratory scanner (3Shape D700). Ten zirconia copings were fabricated for each group using CAD-CAM technology. The marginal and internal fit of the zirconia copings was assessed by the silicone replica technique. Four sections of each replica were obtained, and each section was evaluated at four points: marginal gap (MG), axial wall (AW), axio-occlusal edge (AO) and centro-occlusal wall (CO), using an image analyzing software. The data were submitted to one-way ANOVA and Tukey's test (α = 0.05). They showed statistically significant differences for MG, AO and CO. Regarding MG, intraoral scanning showed lower gap values, whereas gypsum model scanning showed higher gap values. Regarding AO and CO, intraoral digital scanning showed lower gap values. Polyvinyl siloxane impression scanning and gypsum model scanning showed higher gap values and were statistically similar. It can be concluded that intraoral digital scanning provided a lower mean gap value, in comparison with conventional impressions and gypsum casts scanned with a standard benchtop laboratory scanner.

Marginal Adaptation of CAD/CAM All‐Ceramic Crowns Made by Different Impression Methods: A Literature Review

“…In the included studies, marginal gap from intra‐ and extraoral scanning was between 16 to 80 μm and 19 to 112 μm, respectively. In four studies marginal gap of the restorations made using different intraoral scanners was significantly less than marginal gap of restorations made using extraoral scanners . However, in one study, marginal gap of restorations in either group showed no significant difference …”

“…Three of the 13 chosen studies reported the marginal gap of restorations made by the impression scanning method. [52][53][54] The results showed that both methods of extraoral scanning will result in a clinically acceptable marginal gap.…”

“…Although several review articles have compared marginal gap of restorations made using digital impressions (intraoral scanners) and the conventional impression method, no review article was found comparing scanning the impressions and stone dies. Three of the 13 chosen studies reported the marginal gap of restorations made by the impression scanning method . The results showed that both methods of extraoral scanning will result in a clinically acceptable marginal gap.…”

“…Due to different methodologies of the included studies, for proper evaluation of the effect of different extraoral scanners on marginal gap of final restorations, only studies with similar restorative material, abutment position, and preparation design were compared. The marginal gap of the posterior zirconia restorations with a chamfer preparation has been measured using different scanners for stone die scanning . The mean marginal gaps reported in these studies were as follows: 30 μm, 64 μm for Lava scanner, 70 μm for Cercon scanner, 87 μm for 3Shape scanner, and 47 μm for DCS scanner…”

Marginal and Internal Adaptation of Zirconia Crowns: A Comparative Study of Assessment Methods

“…After milling, copings were sintered. Marginal and internal adaptation of each coping was measured using the silicone replica technique (18,23,24) and micro-CT imaging (19,(25)(26)(27).…”