Advanced Full-Arch Implant Surgery by Drs. Cory Glenn and Danny Domingue

by Daniel Domingue, DDS and Cory Glenn, DDS

Abstract
Digital technology has advanced to provide lower cost of entry and faster results, making 3D-printed surgical guides a more reasonable option for practitioners. Historically, the high cost and the complexity of planning kept many from utilizing this technology. Now, with the development of affordable 3D printers and free software such as Blue Sky Plan and Meshmixer, clinicians can now perform the planning and fabrication entirely in-house in a time-efficient manner. However, the surgical results can be no more accurate than the merging of the various data sets, so it is incredibly important to properly acquire, merge and 3D print the data.

We will compare two cases and provide examples of which method would be the best overall therapy in a private practice model. It is well known in the literature that guided surgery is more predictable than non-guided/“free-handed” surgery.1 It’s also well studied that pilot drill-guided surgery is within the same standard deviation range as compared to fully-guided surgery.2,3 In essence, if you are using a surgical guide, either fully or partially guided, it is more accurate for implant placement than not using one at all.

Literature also states that using surgical guides shows comparable long-term success rates compared to not using guides4 for implant placement. A more accurate, inexpensive, easy-to-use, surgical guide for bone reduction and implant placement is not only better for the patient, but also for the practitioner, and should be more routinely utilized.

Purpose
Surgical guide fabrication takes extra effort in the planning phase by adding costs (significantly lower than previously) and time to get trained and work up each case as compared to free-handing implant placement.

While this topic remains hotly debated, it has been our experience after performing many cases in a free-hand and guided approach that the time invested on the front end in planning makes the surgery far easier and more predictable. In this article we’ll show a simple comparison of two similar cases for mandibular implant placement performed by the same surgeon and treatment-planned for the same restorative phase. The one key difference was the obvious use of a surgical guide to reduce bone and direct implant placement. The comparable retrospective study draws a conclusion to warrant guides for all similar cases and less invasive procedures.

Methods

Case I:
A preoperative CT scan was taken (i-CAT) and obvious anterior mandibular atrophy was noted for the first 13mm (roughly midsymphysis) going coronally apically from mental foramen to foramen (Fig.?1). Reduction of mandible was indicated over grafting this site to provide room for prosthetics and level the horizontal plane of occlusion. Measurements for prosthetics were not taken into consideration on CT as this was not available when using i-CAT’s treatment plan studio.

Fig. 1

Case II:
A preoperative CT scan was taken and reviewed (PreXion) (Fig. 2). Similarly, an obvious unlevel plane of occlusion was noted for the anterior mandible. Reducing the mandible was again indicated; however, this time we used BlueSkyBio software in advanced segmentation mode to turn the mandible into an STL file. This was exported from BSB and imported into Meshmixer software, where we used the Plane Cut tool (Fig. 3) at the proper horizontal restorative plane to remove the atrophic excess of bone. We then imported it back into BSB to design a surgical bone reduction guide and a pilot drill guide (Fig. 4). Finally, the prosthetic plane was planned in the software to ensure enough room for fixed prosthetics (Fig. 5).

Fig. 2

Fig. 3

Fig. 4

 

Fig. 5

Results

Case I:
Full flap reflection was placed from a retromolar pad to the contralateral side (Fig. 6). Measurements from the CT scan were then transferred directly on the flapped mandibular bone before making perforations for the desired bone removal location. Each perforation was connected, and the ridge was smoothed down before making pilot drills (Fig. 7). Atrophic bone was removed in one section (Fig. 8) then implant placement was completed without a surgical guide (Fig. 9).

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Case II:
A full thickness flap was placed from the retromolar pad to the contralateral side. A bone reduction guide was placed inside the flap, resting on bone (Fig. 10). A surgical Lindemann bur was used to remove bone and teeth simultaneously (Fig. 11), leaving the remaining ridge perfectly flat (Fig. 12). After the root tips were removed, the pilot drill guide was used (Fig. 13) to place the implants in their preplanned positions (Fig. 14).

Fig. 10

Fig. 11

Fig. 12

Fig. 13

Fig. 14

Conclusion
The postoperative CT images reveal the accuracy and precision of the procedure following the surgical bone-reduction guide (Fig. 15), especially when compared to the results of the nonguided reduction surgery (Fig. 16). The postoperative panorex of guided implant placement, showing parallelism of the osseointegrated implants (Fig.?17), further accentuates the accuracy of placement for guided surgery versus nonguided (Fig. 18).

After placing a full thickness flap, it is often difficult to find hard landmarks on an edentulated ridge. Using a bone reduction guide ensures a faster more predictable reduction without over- or under-reducing the bone. Following up with a pilot drill bone guide provides proper alignment for implant placement. To ensure the guide is fully seated on bone passively, the flap has to be adequate enough to incorporate the thickness of the material under the tissues without pressure from the tissues to disrupt the guide seating. This may require a larger flap or deeper elevation to enable fully seating the guide into place.

Ultimately, using the digital software showed a predetermined ridge reduction, avoiding unnecessary excessive hacking away of bone or not removing enough bone. It provided the ideal location and spacing of osteotomies while also using depth control to prevent nerve injury or cortical perforation. This shortened the surgical procedure and allowed for better healing and less postoperative pain.

No complications were seen in either surgery, all implants integrated, and pain and postoperative swelling, although anecdotal, seemed to be within normal limits. Implants in both phases were not immediate-loaded. A conventional denture was delivered the day of surgery with a modified intaglio surface to not put pressure on the sutures/ridges.

With the advent of free surgical guide design software and the lower cost of CBCT scans and 3D printers, clinicians can 3D print their guides in the office and ensure more predictable and accurate results. The time that it takes to provide the service to your patients, given the accuracy, warrants the use in private practice. In the future this will help eliminate surgical complications such as off angulation, too close to adjacent teeth, nerve impingement, depth control, and bone dehiscence or fenestration, and improve the predictability of the restorative phase of treatment.

Even within the most experienced practicing clinicians, citing all above, there should no longer be an argument against using surgical guides in implant dentistry. Proper planning prosthetics in printed guides prevents poorly placed implants, ensuring predictable precision for patients and practitioners.

Fig. 15

Fig. 16

Fig. 17

Fig. 18

References
1. Scherer U1, Stoetzer M, Ruecker M, Gellrich NC, von See C. Templateguided vs. non-guided drilling in site preparation of dental implants. Clin Oral Investig. 2015 Jul;19(6):1339-46.
2. Kühl S1, Zürcher S, Mahid T, Müller-Gerbl M, Filippi A, Cattin P. Accuracy of full guided vs. half-guided implant surgery. Clin Oral Implants Res. 2013 Jul;24(7):763-9
3. Beretta M1, Poli PP1, Maiorana C1. Accuracy of computer-aided templateguided oral implant placement: a prospective clinical study. J Periodontal Implant Sci. 2014 Aug;44(4):184-93.
4. Laleman I, Bernard L, Vercruyssen M, Jacobs R, Bornstein MM, Quirynen M. Guided Implant Surgery in the Edentulous Maxilla: A Systematic Review. Int J Oral Maxillofac Implants. 2016;31