Digital workflow for implant-supported restorations in the mandible including reverse scan bodies: a feasibility study
TL;DR
Within the limitations of this single-patient evaluation and the favorable two-implant mandibular configuration, intraoral scanning provided sufficient accuracy for fabricating passively fitting restorations on two implants in the edentulous mandible.
Abstract
Completely edentulous mandibles present a challenge for accurate intraoral scanning, which can compromise the passive fit of implant-supported restorations. Reverse scan bodies may improve the accuracy of implant position transfer and support a fully digital workflow. However, clinical evidence for their use in the edentulous mandible remains limited. In this single-patient prospective clinical evaluation, one fully edentulous mandible restored with two interforaminal implants was scanned ten times using an intraoral scanner (IOS). Based on each scan, titanium verification bars (VBs) were fabricated, and their passive fit was assessed clinically. After sectioning and intraoral re-splinting, splinted verification bars (SVBs) were digitized using reverse scan bodies and a laboratory scanner to fabricate new verification bars (NVBs). Linear and angular deviations between datasets (IOS, VB, SVB, NVB) were analyzed using metrology software and statistically evaluated with Welch’s ANOVA and post hoc tests (α = 0.05). All VBs and NVBs demonstrated passive fit clinically. Mean linear deviations were 12 μm between IOS and VB, 50 μm between VB and SVB (p = 0.001), and 26 μm between SVB and NVB (p = 0.20). Mean angular deviations were 0.18° between IOS and VB, with six measurements > 0.4°; 0.79° between VB and SVB (p = 0.01), with seven measurements > 0.4°; and 0.06° between SVB and NVB, with four measurements > 0.4°. Within the limitations of this single-patient evaluation and the favorable two-implant mandibular configuration, intraoral scanning provided sufficient accuracy for fabricating passively fitting restorations on two implants in the edentulous mandible. Measurable linear and angular deviations did not compromise clinical fit in this case. The use of reverse scan bodies may be effective in cases of misfit after intraoral re-splinting, especially in more complex full-arch workflows, as only minor linear and angular deviations were observed in the NVBs with integrated abutments.