Aesthetics in Implantology

Osseointegration in the anterior maxilla is currently not sufficient to result in successful implantation. As soft tissue stability is closely linked to bone stability, any delayed bone resorption will affect all tissues comprising the surface and will inevitably have aesthetic repercussions. Many factors can cause advanced osteolytic lesions. Despite contradictions between authors, exposure of the roughened surface at the soft tissues could cause inflammation leading to peri-implant bone loss. The implant must therefore be designed to promote formation of as permanent as possible tissue environment.

Subcrestal implant positioning is also a surgical option for managing the risks of excessive mechanical constraints at the cortical bone⁽¹⁾ and to reduce the risk of implant exposure, in contrast to equicrestal positioning⁽²⁾. Regarding prosthetics, this subcortical positioning of the implant enables subsequent fitting of a morse cone with a gradual emergence profile. It also enables better management of reduced occlusal spaces⁽²⁾.

Friction cone type connection

In “bone level” implantology, internal cone type connections seem unanimously recognised today for their superiority for peri-implant tissue remodelling, essential in implantology for aesthetic reasons. This superiority is due to their performance with respect to antibacterial and hermetic properties and their ability to prevent micromovements of prosthetics⁽³⁾. The risk of bacterial leakage at the interface is significantly reduced and the integrity of the peri-implant biologic width better preserved⁽⁴⁾.

Surface condition SA² is obtained by sandblasting followed by etching, certified ultraclean by international academy Clean Implant Foundation based in Berlin, Germany.

3 weeks after placement of the implant in dogs, bone healing showed contact osteogenesis. The points of the implant threads were sited in the bone of the bone ridge of the implant site and new cancellous bone was visible in the thread spaces. The thread was not completely filled but the presence of many osteoblasts and osteoid tissue indicated that bone formation was underway.

After 12 weeks, the thread spaces were filled with newly formed bone. The remodelling was started: The primary bone was replaced by secondary osteons which was evidence of an advanced change process.

^{Dr C. Bolle. Soft-tissue and marginal bone-adaptation on platform switched implants.with a morse cone connection: a histomorphometric study in dogs. The Intern. J. of Peiod. & Rest. Dent. (2015)}

” Concave” profiles

For aesthetic permanence, it is essential to preserve the bone plates which support the peri-implant mucosa. Conversely, to reduce negative effects on the bone, optimising mucosa thickness with adapted prosthetic components is recommended⁽⁵⁾.

Healing screw and biological signature

The architecture of the prosthetic housing for implant-supported restorations has a direct influence on the bone remodelling. Using narrow profiles seems better for stabilising the underlying bone⁽⁶⁾.  The supraosseous region of the final prosthesis should ideally have the same prosthetic profile as the healing screw, to ensure no damaging tension can affect the tissues, to preserve thickness and respect the biologic width⁽⁷⁾.

Implantation surgery in the anterior region requires the least invasive route possible. Therefore, when conditions allow, placement of an implant in an alveolar extraction socket is a useful technique which meets this requirement effectively⁽⁸⁾:

• Reduced number of surgical procedures
• Preservation of bony tissue and gingival architecture⁽⁹⁾
• Improvement of osseointegration by benefiting from the alveolar healing potential
• Minimising drilling steps and help with implant position
• Ease of integration of future prostheses during immediate aesthetic loading
• Positive psychological results for the patient for all the above reasons

However, for thin or average biotypes, experience has shown that preserving the soft tissues alone is not enough, and it may be necessary to create a biologically stable anatomic and aesthetic environment at the same time as the grafts.

It has been shown that zirconia implant abutments with a titanium base lead to a favourable response both for periodontal integration and aesthetically⁽¹⁰⁾. This prosthetic option has become essential for thin and transparent biotypes. Machining by CFAO of a ceramic component, then attached by gluing onto a titanium base, enables the laboratory to customise the implant abutment emergence profile while preserving the integrity of the prosthetic interface designed by the manufacturer. The titanium base machined by the manufacturer of the implant ensures the transfer of occlusal loading onto the implantation connection in conformance with the industrial design and protects the assembly against the effects of erosion by friction.

Good three-dimensional implant positioning on the anterior region is a key element in obtaining an aesthetically pleasing result. Bone anatomy and surrounding structure (smile line, etiology, biotype, adjacent teeth, antagonistic teeth, prosthetic plan, mechanical constraints, etc.) criteria vary between patients. IT planning followed by a 3D impression for a surgical guide can be a well thought out choice for the treatment plan. Planning enables adjustment of the 3D positioning of the implant so that it conforms with the prosthetic plan and so that the implant is the most efficient in terms of mechanical, bone and periodontal integration.