Digital Planning for a Maxillary All-on-X Surgery: Considerations for a High Smile Line
A 68-year-old female presented upon referral from her physician to evaluate her dentition as a potential contributing factor to her elevated white blood cell counts. Her medical history included controlled Type II diabetes and thyroid removal following cancer. After many years since her last dental visit, she presented for a dental evaluation. The oral examination noted numerous abscesses, failing restorations, and missing teeth. The following treatment options were discussed for her maxillary arch: (1) endodontic treatment on multiple teeth, restoring caries, and replacing the missing teeth with long-span bridgework; (2) a full-arch extraction, followed by a locator implant overdenture; or (3) a full-arch, implant-supported, fixed option using a teeth-in-a-day protocol. Upon discussion of the risks and benefits of the 3 treatment options, the patient and her husband elected for the teeth-in-a-day approach for her maxillary arch. The patient’s mandibular teeth would be restored with fillings and crowns.
Upon acceptance of the treatment plan, a full diagnostic workup was completed. This included a full photographic series (Nikon [PhotoMed]), an intraoral scan for study models (CEREC [Dentsply Sirona]), and a CBCT scan (RayScan [Genicore]). Those records were imported into surgical planning software (Blue Sky Plan [Blue Sky Bio]) and were sent to the dental laboratory team for denture fabrication (Artifex Lab, Alexandria, Va).
The patient’s upper lip was extremely mobile, ranging from no tooth display at rest to showing several millimeters of gingiva on full smile. This presented a serious challenge for our surgical planning because we needed to predictably plan the correct amount of bone reduction on the day of surgery, but we did not have a method to measure the height that her lip reached. This measurement needs to be extremely accurate because the height of the lip-line determines a significant portion of the prosthetic and surgical planning. The lip-line determines the final height of the patient’s gingiva, which determines the amount of bone reduction needed, which, in turn, impacts the final implant positions. Too little bone reduction would cause a visible transition between the patient’s gingiva and the prosthetic gingiva, but too much bone reduction would compromise the height of bone available to engage our implants; therefore, a more accurate measurement was needed of the patient’s lip-line.
Following the recommendations of Dr. Elias Rivera (University of Maryland Prosthodontics) and Dr. Paul Bylis (Innovative Dental Design, Glen Burnie, Md), the patient was brought back to take one additional record. This new record would objectively determine her lip-line when she displayed the fullest smile. This would form an accurate and repeatable landmark of where the lip extends on full smile rather than have our full surgical plan relying on an estimate from a photo. The premise of this record was the following: create a putty matrix in the patient’s mouth that represents the exact level of her lip on full smile, and then transfer that lip-line record into the digital planning software. To accomplish this, we created a putty matrix (Panasil Putty Soft [Kettenbach LP]) on her study model in preparation for the appointment. At the appointment, we seated the matrix in her mouth, had her make her “biggest smile ever,” and then used a pen to mark her lip-line on the putty. The stent was cut along that line and placed back into her mouth, and then small modifications were made to the stent based on observing her talk and smile. Photos of the patient wearing this stent were then taken.
After this appointment, the matrix was placed onto her study model, and a No. 8 round bur (Brasseler USA) was utilized to indent the flange of the matrix (representing the patient’s lip-line) onto her cast. This cast was digitally scanned, imported into the implant planning software, and then aligned with her other models/CT scans (Figure 3b). The digital plan now had a defined plane of the patient’s exact lip-line, aligned with her CT scans/other models, which represents the maximum height that her lip extends and, therefore, the coronal-most position of the gingiva.
This was a critical piece of information, which allowed for the virtual design and planning of the other aspects of the case. The bone level was digitally cut to 3.0 mm apical to the height of the gingiva. Then the implants were placed to the height of the bone, and the prosthetic clearance was made to be 15.0 mm from the platform of the implants to the occlusal surface of the prosthetic. All implants and surgical guide stabilization pins were digitally placed based on the prosthetic plan and anatomical boundaries.
The surgical plan called for the fabrication of 3 guides: a pin guide, a bone reduction guide, and an implant guide. All 3 guides’ placements were triangulated based on 3 stabilization pinholes. This is unlike a typical single-tooth implant, which uses a tooth-borne guide and seats on the adjacent teeth for orientation.
The first guide is the pin guide, which is used to determine the 3 pinholes. The purpose of these pinholes is to orient the subsequent 2 guides, which are fixated and stabilized by 3 pins. For this case, the pin guide was made to be placed following extraction of the teeth and to be seated over the patient’s edentulated arch. Since there was not an actual model of how the patient’s bone would present after the teeth were extracted, a model was generated by modifying the segmented maxillary model to virtually extract the teeth (Meshmixer [Autodesk]). Next, this edentulous bone model was imported into the planning software, and a vacuum-formed guide was fabricated with 3 pinholes. Surgically, the pin guide is placed following the extractions, the 3 holes are drilled, and then the guide is set aside.
The next guide is the bone reduction guide: a thin guide in which the coronal portion represents the new level of the bone; all bone coronal to the bone guide should be reduced to that level. The final guide is the implant guide, which also engages the 3 pinholes and was used with our fully guided implant kit (TAG Dental [Genicore]) to predictably place all 8 planned implants. All 3 guides were 3-D printed (Digi3DWorks) in preparation for the day of surgery.
On the day of surgery, local anesthetic was administered, and a full-thickness mucoperiosteal flap was laid. Then the patient was atraumatically and fully edentulated on the maxillary arch, and all infected tissue was curetted until solid bone was reached. Due to the large amount of bone reduction required for this procedure, a large flap had to be laid to allow the guides to seat apically enough. Following edentulation, the pin guide was seated on the bone, and the 3 pinholes were created. Next, the bone reduction guide was placed, engaging the 3 pin holes and showing exactly how much bone needed to be reduced . A large bone-cutting bur (Global Dental Products) was used with copious irrigation to reduce the bone to the level of the bone reduction guide . The bone reduction guide was then removed, and the implant guide was placed, engaging the same 3 pinholes. Implants (TAG Dental implants [Genicore]) were placed using fully guided protocols, bone (MinerOss [BioHorizons]) and MIS Implants Technologies’ collagen membranes (Genicore) were placed, the flap was approximated using simple interrupted sutures, and a final CBCT scan was taken to confirm the placement of the implants.
Upon confirmation of successful implant placement, multi-unit abutments and cylinders (TAG Dental products [Genicore]) were placed on the implants, the maxillary denture was seated over the cylinders and was picked up with acrylic (Lang Dental), the prosthetic was adjusted/polished, and the palate of the denture was removed. The finalized temporary was inserted, engaging 7 of the 8 implants, and occlusion was checked. The eighth implant was not engaged due to insufficient insertion torque and, instead, was buried with a bone healing cap. The screw access holes were sealed with light-body putty (Kettenbach LP). Photos at the one-day follow-up revealed that the patient was healing well.