Completely Digital Two-Visit Immediately Loaded Implants: Proof of Concept

Implant dentistry has become a common treatment alternative, yet only a small percentage of patients missing teeth are receiving its benefits.

A 2012 National Health and Nutrition Examination Survey (NHANES)¹  reported more than one-half of the adult population were missing 1 or several teeth, and 23% of those above age 65 are missing all teeth. Yet in 2014, only approximately 2.3 million implants were placed in the United States.² 

The usual reason cited for the limited use of implants is expense. However, more significant limitations are the small percent of practitioners placing implants and the time commitment on the part of the patient. A 2008 ADA survey³  showed only 15.9% of dentists practicing in the United States are placing implants. Some reasons cited for this are the long learning curve and the complex, expensive delivery systems. Thus, practitioners prescribe the less time consuming and less complex conventional treatment alternatives that they are comfortable providing. This report introduces a proof of concept that promises to overcome these limitations. It demonstrates that a restoratively driven implant and restoration—directly from digital input technology—can be performed in 2 patient visits without requiring years of manual skill development on the part of the surgeon, restorative dentist, and technician.

A 32-year-old male patient presented with a high smile line and missing maxillary left lateral and canine as a result of a bicycle accident that occurred approximately 2 years prior to presentation (Figure 1). At the first visit a CBCT scan (i-CAT, Imaging Sciences International LLC, Hatfield, Pa) of the maxillary arch with an intraorally placed prefabricated appliance containing fiduciary markers (Keybite, ProPrecision Guides, Keystone Heights, Fla) confirmed, at the edentulous site, adequate bone volume and density and acquired a digital image of the bone, remaining teeth, and fiduciary markers. At this same visit, an optical scan of the teeth, soft tissue, and opposing arch, as well as the teeth in occlusion was completed with a digital impression device (Itero, Align Technology Inc, San Jose, Calif) (Figure 2). Following digital data capture, the patient was provided preoperative instruction, medication, and informed consent and was appointed for implant and restoration.

Digitization of the information was undertaken and shown in Figure 3. From the digital data captured by the CBCT, a 3-D reconstruction was produced. Digital images of the 3-D reconstruction of the hard tissue from the CT scan, with fiduciary markers in yellow, are shown in Figure 3a and b. The surface scan (digital impression) is shown in green, and marked in red are the teeth from the CT scan. Four red spheres can be seen at the cusp tips on both of these images; these are used to register and merge the digital CT images with surface scans in the software (Figure 3c and d). The merged images are shown in Figure 3e and f. The surface scan of the opposing arch, which is digitally articulated from the digital interocclusal record captured at the initial surface scan, is shown in Figure 3g and h.

Now all the elements required to plan implant position and create emergence profile and occlusion for immediate restoration are available in digital form. The merged digital information containing the fiduciary markers was exported into the implant planning software (Dental Wings Inc, Montreal, Canada). Fiduciary markers were necessary for the software to export the correct implant coordinates for final file assembly in production of the surgical guide. Using CAD software (Geomagic Freeform, 3D Systems, Rock Hill, SC), a digital cuspid and lateral incisor from the contralateral teeth were created and positioned within the edentulous space relative to each other, adjacent teeth, soft tissue, and opposing dentition (Figure 4a and b).

Next, using Codiagnostix implant planning software (Dental Wings), a digital implant 10 × 4.1 mm bone level (Straumann, Andover, Mass) was positioned within the cervical envelope formed by the cervix of the tooth, incisal edge, and the crest of residual bone (Figure 5).

With the implant in the optimum position within the digitally positioned teeth, the emergence profile for the provisional restoration was formed between the implant platform and the cervix of the tooth (Figure 6).

Once the planning was complete, the digital information was transmitted to a production facility for digital printing of surgical template for guided implant placement and pre-implant printed models containing a repository for the implant analogue (ProPrecision Guides, Keystones Heights, Fla). Figure 7 shows the digital surgical template on the left (a), the printed template on the right (b), the digital implant on the left (c), and the digitally printed pre-implant model with the implant analog on the right (d).

Next, the digital file of the restoration was transmitted for milling (North Shore Dental Labs Inc, Lynn, Mass) in Telio CAD resin (Ivoclar Vivadent, Amherst, NY). The restoration was then positioned on the printed maxillary model with analogue (Figure 8), and a silicone matrix (Zhermack Inc, River Edge, NJ) was formed to capture the restoration position relative to the adjacent teeth for positioning the restoration at surgery.

At the second visit, the patient presented for implantation. He was premedicated with Penn VK 2000 mg 1 hour prior to the procedure and administered 2 cc local infiltration anesthetic (xylocaine 1:100 000) palatally and labially shortly before beginning the incision. A marginal and midline incision was made to elevate a conservative flap in the area of the guide sleeve of the template to position it on the adjacent teeth without soft tissue interference (Figure 9).

The template was seated and correct position confirmed by the inspection windows shown with the arrows (Figure 10). Following the manufacturer's protocol, the implant site was prepared. The 4.1 × 10 mm bone level implant (Straumann USA LLC, Andover, Mass) was placed, fully guided with the insertion torque of 35 Ncm (Figure 11).

To account for reported discrepancies between planned and final position^4,5  when using guided implant placement, the provisional restoration was joined to the temporary abutment at implant placement. To accomplish this, the provisional restoration was milled hollow so it could be passively and precisely positioned over the temporary abutment once the implant had reached its final position. Immediately upon placement of the implant in its final position, a prefabricated temporary abutment (Straumann) was placed on the implant, and the pre-implant provisional crown was positioned over the abutment using the silicon indexing matrix. The crown was then luted to the abutment with autopolymerizing PMMA resin (Caulk Temporary Bridge Resin, Dentsply Caulk, Milford, Del). Once cured, the crown was removed from the implant and the emergence area between the implant platform and crown, and the crown was contoured with the same autopolymerizing PMMA resin (Dentsply), finished and polished (Figure 12). The immediately loaded provisional restoration was inserted and adjusted completely out of occlusion. Tissue closure was with 4-0 Vicryl Rapide (Ethicon, Somerville, NJ) (Figure 13). The initial patient presentation is shown in Figure 14a; the final restoration at 4 months, demonstrating soft tissue apposition, is shown in Figure 14b.

This proof of concept demonstrates that, today, a digitally planned implant and restoration can be produced, placed, and restored in 2 visits without the need for conventional impressions, laboratory procedures, and advanced manual skills.

There are significant future benefits to this approach. First, there are reduced patient visits. Second, there are improved methods of pretreatment electronic communication, resulting in all implant planning accomplished digitally among the surgical specialist, restorative dentist, and laboratory technician. Third, preplanning can be accomplished by support staff, reducing practitioners' and senior technicians' learning curve and, ultimately, cost.

Furthermore, time-consuming, and expensive laboratory procedures are unnecessary prior to CT scans. Thus, the current workflow is reversed so that CT scans can be performed as a first step to identify the straightforward implant patient prior to laboratory fabrication of a surgical guide, which can later be merged with the CAT scan for treatment to proceed.

There are, however, several obstacles to overcome if this concept is to become reality. In this report, multiple individual, nonintegrated digital technologies were used to accomplish this delivery model. While the combination of CBCT data with surface scan data is becoming more routine and has been shown to be clinically acceptable,⁶  the process today is cumbersome. For implant planning procedures used in this report, we exported a digitally contralateral tooth to both plan and produce the restoration using a separate software (Geomagic Freeform, 3D Systems, Rock Hill, SC). In the future, teeth from digital libraries within planning software will be available for both implant planning and restoration production. At the present time, available library software does not allow for the planned restoration to be digitally produced without cumbersome exporting and importing among different software formats during the planning and, later, in the production phase.

Moreover, intrinsic inaccuracies of hardware must be addressed to minimize inaccuracies resulting from instrumentation fit through the surgical template and fit of the template to the dentition.^7–11  Thus, improved precision of planned vs actual implant position is critical to producing restorations that can be precisely attached to the implant at insertion without time-consuming chairside fitting. It should be noted that the techniques demonstrated in this report are not applicable to the completely edentulous patient due to instability of the surgical template resting on mucosa.¹²  Additional research into production methods of bone-anchored prostheses promises to address this.

Currently available systems include Anatomage (San Jose, Calif), Gallaleos (Sirona Dental Inc USA, Charlotte, NC), NobelClinician (NobelBiocare USA, Yorba Linda, Calif), Cares (Straumann), Simplant (Dentsply Implants, Waltham, Mass), and 3Shape Implant Studio (3Shape A/S, Warren, NJ). They emulate various aspects of this concept, but none are fully able to proceed digitally from initial data capture to restoration insertion immediately upon implant placement. As the digitization of implant dentistry progresses, competition among manufacturers promises to make digital implant treatment readily available at a reasonable cost and reduced learning curve.

This proof of concept demonstrates clinical implant treatment heretofore requiring years of manual skill development on the part of the surgeon, restorative dentist, and technician can be accomplished fully digitally, resulting in a significant reduction in learning curve and manual skill level. As digital procedures are refined, many more dental professionals will become involved in providing implant therapy earlier in their careers. This promises to result in reduced cost, making implants available to millions more patients who could benefit from them.