Description
Abstract
Background: The aim of this study was to evaluate the effect of surgical guide design and type of blade, in relation to soft tissue thickness, on the accuracy of computer-assisted crown lengthening.
Methods: A set of fully dentate anatomic maxilla models was implemented, using 2 types of soft-tissue masks with a mean thickness of 1.5 and 3.5 mm, respectively, to simulate a clinical scenario of altered passive eruption. In total, 5 different gingivectomy techniques were assessed, implementing 3 different types of guidance and 2 different blades. The osteotomy was performed using 2 surgical guide designs. After each operation, the models were scanned and superimposed with the initial virtual design, to evaluate the accuracy of each evaluated approach through a set of linear measurements.
Results: For the gingivectomy as well as for the osteotomy, the mean discrepancy was increased in the presence of increased soft tissue thickness (p < 0.05). The integration of supporting planes led to a decrease in the discrepancy compared to the conventional double guide design for both of the investigated soft-tissue thicknesses (p < 0.05). For the models with the normal soft tissue thickness, a lower mean discrepancy was presented, when a mini blade was used instead of a conventional surgical blade, irrespective of the guide design (p < 0.05). Conclusion: Computer-assisted crown lengthening can be considered a feasible treatment option. Soft tissue thickness has to be taken into consideration during the design of the surgical template, in order additional support to be provided when it is needed. Surgical templates with integrated supporting planes can increase the accuracy of computer-assisted crown lengthening.
K E Y WO R D S
crown lengthening, digital workflow, guided surgery, smile esthetics, soft tissue
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