Facially-guided fast and fixed reha- bilitation of an edentulous maxilla
MORVARID KESHVARI, PORTUGAL

Implant dentistry has recently witnessed a paradigm shift to a complete digital workflow encompassing
advanced dental diagnostic and planning software, Digital Smile Design, intraoral digital impressions and scans with Computer-Assisted Designing (CAD) and Computer-Assisted Manufacturing (CAM) of provisional and definitive prostheses. A digital workflow enables the patient to visualize the expected rehabilitation before the start of procedure, hence facilitating communication and management of patient’s expectation. A clinician can achieve successful and reproducible reconstruction with minimal treatment and short turnaround time by complete digitization of the process.

There are various 3D smile design soft-wares available. The evolution of dental designing software over the past few years has made possible the rehabilitation of a patient by combining the files from a CBCT along with STL files of an intraoral scan and images. This threedimensional data acquisition allows a dentist to create virtual models of the face, bone and dental profile. This data is imported into a CAD software and superimposed upon each other in order to obtain the virtual patient. The dentist and the dental technician using the CAD software plan the surgical template and prosthetic restoration. Finally, these devices are processed by CAM software, milled or 3D printed and made available for clinical use.

The literature on immediate loading with fixed full-arch prosthesis in the maxilla shows that a successful outcome can be expected if adequate criteria are used to evaluate the patient, choose the right implant with high primary stability and perform the surgical and prosthetic treatment. High implant and prosthetic survival rate, low marginal bone loss and few complications are reported by studies on immediate loading.

The SKY fast and fixed treatment concept presents the possibility for immediate loading of a full arch with a reduced number of implants spread out according to the biomechanical principles of load transfer on the condition that the implants achieve primary stability of more than 30 Ncm. Cross-arch splinting with temporary bridge is recommended to minimize forces exerted and implant micromobility controlled (< 150 μm) for osseointegration of immediately loaded implants. Hence the patient gets a fixed set of teeth on the day of surgery. The following case report highlights the meticulously planned and esthetically executed case of a female edentulous patient with the SKY fast and fixed treatment concept using a novel digital workflow.

Case report

A middle-aged female patient presented with a removable complete upper denture seeking treatment for fixed replacement of her missing teeth. Following the radiological and clinical examination, a full-arch implant supported rehabilitation with six implants in the maxilla in accordance with the fast & fixed concept using digital workflow and Digital Smile Design (DSD) was planned.

Preoperative procedures

Full-mouth intraoral scans were taken with the existing denture in place and subsequently without the denture to obtain STL files (Figs. 1 and 2).

DICOM data was obtained by taking the CBCT of the patient with the old denture in place along with opaque points and without the denture (Fig. 3). A CBCT was also taken of the denture alone with the opaque points. A series of facial images were taken of the patients at rest and in motion (Figs. 4 and 5). The digital smile design, implant placement planning for fabrication of surgical guides and prosthesis was done using Nemotec and exocad (exocad GmbH, Germany) software.

The STL files, CBCTs and images were imported to the software. Superimposition of the same was done for virtual manipulation to enable the fabrication of guides and digitally design the smile of the patient. The Digital Smile Design was done considering esthetics, lip support and occlusal scheme (Figs. 6 to 10) for procuring an ideal immediate hybrid provisional prosthesis in Polymethylmethacrylate (PMMA).

Based on the prosthetic planning and the anatomy of the maxilla, the path of implant placement was planned (Fig. 11) for fabrication of the surgical guide and prosthesis. Hence a facially guided approach was used. Since bone reduction was required, stackable guides were fabricated on the base guide (Fig. 12). A bite splint was also fabricated for orientation and position of the first guide (base guide) before fixing it with pins (Fig. 13). The ability of implants to achieve a high primary stability is an important factor in immediate restoration. Hence a back tapered, self-cutting double-threaded implant with a unique surface topography osseo-connect surface (OCS) which enhances osseointegration and soft tissue adhesion at the neck was chosen (copaSKY, bredent medical GmbH & Co. KG, Germany). The SKY planX guide drills and sleeves were intended to be used for the guided implant surgery for precise implant placement.

Surgical phase

The procedure was performed under local anaesthesia (Fig. 14) and a full thickness mucoperiosteal flap was elevated. The base guide was positioned with the customized prefabricated immediate implant prosthesis along with the bite splint to correctly orientate the base guide before fixing it with pins (Fig. 15).

The anchor pins were put into place after using the twist drills (Figs. 16 and 17). Bone reduction and flattening of the ridge was done with rongeurs and crestotomy round burs for the final implant head position (Fig. 18). Following the bone reduction, the surgical guide (Pilot System) for the osteotomy preparation was attached to the base guide and osteotomy was completed (Figs. 19 and 20).

The SKY planX drills were used for osteotomy site preparation for the subsequent placement of six copaSKY implants (Fig. 21). Resonance Frequency Analysis (RFA) was done (Penguin, bredent medical GmbH & Co. KG, Germany) and an average reading of 70 Implant Stability Quotient (ISQ) was achieved on all implants making immediate loading predictable. The copaSKY unicone abutments were attached to the implants followed by engaging the titanium copings of the immediate provisional prosthesis (Fig. 22). The immediate provisional PMMA prosthesis was activated extraorally with Qu connector at the luting areas (bredent GmbH & Co. KG, Germany) and puttied intraorally with Qu resin (bredent GmbH & Co. KG, Germany) (Fig. 23).

Only centric contacts were given on the provisional prosthesis. The provisional bridge did not have any cantilevers hence preventing high leverage forces which might be a risk for the osseointegration of the implants (Fig. 24). The patient was extremely satisfied with the facially designed immediate provisional prosthesis (Figs. 25 and 26) and the healing was satisfactory (Fig. 27). She immediately got back her lost confidence.

Discussion

The main advantage of planning a fullarch implant reconstruction with the SKY fast & fixed treatment concept is the possibility of getting an immediate fixed interim prosthesis on the day of surgery. This provides esthetics and functional rehabilitation without delay thereby enhancing the patient’s quality of life. Splinting of implants seems to be important in immediate loading, especially when bone density is low. The reduced number of stable implants is cross-arch splinted for occlusal load distribution as a treatment protocol. Hence immediate loading with interim fixed prostheses in the edentulous maxilla is a viable treatment alternative. Studies have shown that the SKY fast and fixed treatment protocol is successful in restoring edentulous ridges due to the perfectly matched combination of implants, abutments and dental laboratory materials, which make immediate loading with immediate implants feasible and predictable. A study evaluated the clinical efficacy of the SKY fast and fixed system and reported a 100 % success rate of prosthetic restoration. Patients were satisfied with the esthetics of the prosthesis and with the phonetics and chewing function. Prosthetic-driven implant dentistry is the optimal way to treat patients using dental implants. In the current case, DSD was done to ensure a prosthetic- driven facial approach for planning and designing of the provisional and definitive prosthesis. The same applies for the path of implant placement using a guided approach. DSD is a tool which provides detailed information to the clinician, the technician and the patient. Due to its interoperability with different digital file formats, software and modern dental equipment, the DSD is optimal for planning and leads to predictable restorative outcomes. A guided approach using stackable stents was used for the osteotomy site. Static guidance systems are defined as systems which communicate the predetermined virtual implant position to the surgical operating area, using a rigid surgical implant template or guide. A systematic review concluded that the accuracy of static computer aided implant surgery is within the clinically acceptable range in most clinical situations. However, a safety margin of at least 2 mm should be respected. The outcome of implants placed with a static guide and of the prosthetic reconstruction seems similar to that expected from conventional techniques. The number of surgical complications with the guided approach is negligible . The copaSKY implant system was selected based on the reliable attainment of high primary stability and the fast osseointegration due to the implant surface and design, in addition to prosthetic benefits of the conical implant-abutment connection. The copaSKY implant has a unique osseo-connect surface, the neck of the implant supports soft tissue at- tachment for the prevention of bacterial infiltration thereby protecting the implant. The sandblasted and etched sur- face enhances rapid osseointegration. It has a back-taper design and double, self-cutting compression threads which is important for the primary stability because only half the amount of the trabecular bone is traumatized during the insertion of the implant. The back taper should always be covered with bone chips to ensure that the implant is completely covered from all sides. The self-tapping double thread also achieves faster in- sertion of the implant with lower heat generation and bone condensation. Sandblasted and etched implants with a self-cutting thread in a cylindrical and conical mixed design show statistically higher insertion and removal torque val- ues compared with machined implants along with enhanced primary stability. All reviewed studies agreed in regarding primary implant stability as the key requirement for success of immediate loading. The short conical and parallel walled implant-abutment connection makes abutments easily retrievable, there is no morse taper effect even after loading. The copaSKY uni.cone abutments are soft tissue friendly with no sharp and rough edges. Due to the formfit between the co- paSKY uni.cone abutments and copings, there is a high stability of occlusal screw- retained bridge. A systematic review by Papaspyridakos et al reported that the most frequent implant-related technical complication with fixed implant rehabili- tation for edentulous patients was screw fracture, yielding a 5-year complication rate of 10.4 % and a 10-year rate of 20.8 %. This formfit technology minimizes complications such as screw-loosening and fractures often witnessed with full-arch implant-supported bridges.The material of choice for the provisional prosthesis was PMMA due to the high fracture rate reported in interim acrylic prosthesis by several studies. PMMA can be easily milled and fabricated with digital workflows. It ensures softer loading without compromise on esthetics.

Conclusion

The current increase in patient demands for esthetics and dentists’ quest for precision in implant dentistry require excellent techniques and materials. The trend toward digital workflows makes this possible, with the patient’s well-being at the forefront at every stage. The described workflow showcased a reduction in the surgical time due to the digitalized comprehensive planning and pre-operative laboratory procedures for immediate restoration of function and esthetics. Hence attention to detail and a holistic approach culminate into functional and visually appealing masterpiece aided with new-age biomaterials. Summarized, the digital workflow with SKY fast & fixed is a win-win situation for the patient and the practice. However, long-term clinical studies are needed to evaluate the clinical superiority of guided implant procedures as compared to conventional methods for the rehabilitation of edentulous jaws.