The Effect of Different Wax Pattern Fabrication Techniques on the Marginal Fit of Customized Lithium Disilicate Implant Abutments

Abstract

Purpose: To evaluate the effect of different wax pattern fabrication techniques on the fit of customized pressed lithium disilicate implant abutments on titanium inserts before and after pressing. The marginal fit results of pressed lithium disilicate implant abutments were then compared with those of milled lithium disilicate abutments. Materials and Methods: After scanning the titanium inserts and designing an implant abutment, wax patterns were fabricated with three techniques (n = 15 each): computeraided design/computer-aided manufacturing (CAD/CAM) milling, 3D printing and conventional layering. The marginal fit (µm) was measured using a stereomicroscope for all the wax patterns before pressing them into the lithium disilicate abutments. The pressed implant abutments were measured again for marginal fit, and the results were compared to those of the milled lithium disilicate abutments. One-way analysis of variance (ANOVA) was used to assess different wax pattern fabrication techniques in each stage before and after pressing. One-way ANOVA was also used to compare the groups of pressed and milled lithium disilicate abutments. Multiple pairwise comparisons were performed using the Tukey post hoc test in each stage. Results: There were statistically significant differences between the marginal fit of the three wax patterns groups (p < 0.001; f = 123.33), wherein the mean marginal fit was the highest for conventionally layered wax patterns (30 ± 13.09) µm. Furthermore, after pressing, there were statistically significant differences between the marginal fit of the three pressed abutments groups (p < 0.001; f = 518.62), wherein the mean marginal fit was the highest for pressed e.max abutments fabricated from conventionally layered wax patterns (25.26 ± 3.9) µm. There was no statistically significant difference between the mean marginal fit of the pressed abutments fabricated from conventional layered wax patterns and that of the milled CAD/CAM abutments. However, the mean marginal fit of the milled CAD/CAM abutments was higher than that of the pressed abutments fabricated from both CAD/CAM wax and 3D printed wax. Conclusion: All the tested fabrication methods provided degrees of accuracy that lie well within accepted limits. The use of pressed lithium disilicate abutments fabricated from conventional layering wax pattern technique should provide a more consistent better marginal fit between the titanium insert and the abutment and may therefore be the preferable fabrication method.

Comparison of Intaglio Surface Trueness of Interim Dental Crowns Fabricated with SLA 3D Printing, DLP 3D Printing, and Milling Technologies

“…The CAD/CAM process manufactures dental prostheses in the order of scanning, CAD, and CAM processes [7,8]. The steps of CAD/CAM workflow are as follows: acquire a virtual work model using a 3-dimensional (3D) scanner and produce a working cast using a 3D printer, milling machine, or design a prosthesis in CAD software without a model and then use 3D printing and milling technologies to fabricate dental prostheses [9,10].…”

Effect of different fabrication materials and techniques on the retention of implant meso-structures to Ti-base abutments

“…The paradigm shift in recently introduced digital workflow of oral implantology and CAD/ CAM technology has reached an advanced level of development. 24 The overlap between these two advanced categories in dentistry in addition to the innovative enhancement in all-ceramic materials and polymer-based materials led to the introduction of novel treatment strategies and concepts for replacement of missing single tooth through implant-supported restorations. 45 The selection of implant abutments which represent the link between osseo-integrated implant fixtures and implant superstructure is crucial in gaining functional and esthetic rehabilitation.…”

“…Moreover, within the pressing technique itself, the step of the wax pattern construction could be designed with different technologies such as manual conventional technique, subtractive CAD/CAM technique as well as the additive 3D manufacturing technique. 24 In this study, the two techniques for construction of lithium disilicate E.max ceramic were selected: the CAD/CAM technique and the pressing technique using the 3D printing for wax pattern fabrication. The E.max Press abutments showed higher pullout retention values than E.max CAD abutments and the difference was statistically significant.…”

“…The abutments were designed with a standardized dimension according to the dimensions of prepared upper second premolar as follows: 12 mm occlusogingival height, 6.5mm bucco-lingual width, 5.5 mm mesio-distal width, 0.5 mm chamfer finish line and 2.5mm screw channel. 24 (Fig. 2).…”

“…17 CAD/ CAM technology is not only restricted to subtractive manufacturing where the crown or abutment can be milled or grinded from a block or a disc, but also additive manufacturing can be used to fabricate a wax pattern, which in turn, can be used either by heat-pressing or compression moulding techniques to fabricate the superstructure. 24 Due to the huge advancement in technologies and materials, the use of Ti-base nowadays ranges from single tooth replacement to full-arch prostheses with a plethora of dental materials available for each purpose. 25 When used as abutments on Ti-base, zirconia has shown good results and high fracture resistance 26 .…”