Sinus Lift and Implant Insertion on 3D-Printed Polymeric Maxillary Models: Ex Vivo Training for In Vivo Surgical Procedures

Abstract

Background and objectives: The aim of this study is to demonstrate the increased efficiency achieved by dental practitioners when carrying out an ex vivo training process on 3D-printed maxillaries before performing in vivo surgery.

Materials and methods: This developed ex vivo procedure comprises the following phases: (i) scanning the area of interest for surgery; (ii) obtaining a 3D virtual model of this area using Cone Beam Computed Tomography (CBCT); (iii) obtaining a 3D-printed model (based on the virtual one), on which (iv) the dental practitioner simulates/rehearses ex vivo (most of) the surgery protocol; (v) assess with a new CBCT the 3D model after simulation. The technical steps of sinus augmentation and implant insertion could be performed on the corresponding 3D-printed hemi-maxillaries prior to the real in vivo surgery. Two study groups were considered, with forty patients divided as follows: Group 1 comprises twenty patients on which the developed simulation and rehearsal procedure was applied; Group 2 is a control one which comprises twenty patients on which similar surgery was performed without this procedure (considered in order to compare operative times without and with rehearsals).

Results: Following the ex vivo training/rehearsal, an optimal surgery protocol was developed for each considered case. The results of the surgery on patients were compared with the results obtained after rehearsals on 3D-printed models. The performed quantitative assessment proved that, using the proposed training procedure, the results of the in vivo surgery are not significantly different (p = 0.089) with regard to the ex vivo simulation for both the mezio-distal position of the implant and the distance from the ridge margin to sinus window. On the contrary, the operative time of Group 1 was reduced significantly (p = 0.001), with an average of 20% with regard to in vivo procedures performed without rehearsals (on the control Group 2).

Conclusions: The study demonstrated that the use of 3D-printed models can be beneficial to dental surgeon practitioners, as well as to students who must be trained before performing clinical treatments.

Keywords: 3D printing; CAD/CAM techniques; Cone Beam Computed Tomography (CBCT); dental implants; ex vivo training procedure; in vivo surgery procedure; maxillary models; polymers; sinus lift.

Figure 1

(a) Initial clinical assessment; (b) preoperative orthopantomogram (OPG) showing an insufficient height for implant insertion in the maxillary right first molar edentulous site.

Figure 2

Cross-sectional CBCT views corresponding to: (a) the 16 with a bone height of 5.02 mm; (b) the 17 with a bone height of 2.65 mm and insufficient crestal width.

Figure 3

The steps of the design and manufacturing of a hemi-maxillary: (a) CAD-initial and final design; (b) CAM-3D printing, with a Form2 system (Formlabs Inc., Somerville, MA, USA); (c) final two steps of the manufacturing process, i.e., washing and curing of the obtained polymer-based 3D-printed models.

Figure 4

(a) 3D-printed model, with (b) frontal and (c) lateral view.

Figure 5

(a) Flap design; (b) the bony window; (c) the bony window, almost completed saving the blood vessels; (d) the Schneiderian membrane was elevated; (e) inserted implant in the 16th position with simultaneous sinus augmentation; (f) sinus lift procedure 17 and lateral crest augmentation.

Figure 6

(a) Postoperative control of the patient using 3D imaging; (b) the augmented 17 site (cross-sections).

Figure 7

Measurement of the mezio-distal position of the implant (i.e., distance from the anterior tooth to the middle of the implant (D1)) on (a) the training CBCT model (D1-3D) and on (b) the postoperative CBCT (D1-P)—panoramic view.

Figure 8

Measurement of the distance between the top of the ridge and the lowest access cut at the buccal wall of the maxillary sinus (for patient number 6 in Table 1) on (a) the training CBCT model (D2-3D) and on (b) the postoperative CBCT (D2-P) cross-section.