Beyond osseointegration: the long-term biological vision in implant prosthodontics

Looking back to move forward 

We often celebrate early success. But time is the true test. What appears successful at the beginning may not remain so after ten, fifteen, or twenty years. In my experience, long-term success is about the stability of the entire peri-implant complex, especially the soft tissue barrier. And this is where prosthetic design becomes not just important, but essential.

The barrier question

We’ve all seen cases where the implant is wellintegrated, the volume is sufficient, and the esthetics are acceptable. Yet over time, marginal bone loss or soft tissue recession occurs. These aren’t outright failures, but they are signs of biological instability. They occur not only in regenerated bone but also in immediate implant placements, even with adjacent teeth present. Slight papilla collapse, some recession, and bone loss all point toward a vulnerable or unstable soft tissue seal.

Understanding the soft tissue interface 

Research now shows that the soft tissue barrier around implants is fundamentally different from that around natural teeth. A study from Stanford University compared the junctional epithelium in both scenarios.¹ Around teeth, the barrier is stronger, supported by a rich population of stem cells. Around implants, this biological support is missing. The result is a weaker and more vulnerable interface.

To look deeper into this, we should study the adhesion, e.g. the concentration of the hemidesmosomes, which are key adhesion structures, in the tissues. One of our recent studies shows that the highest concentration of hemidesmosomes is located at the border between the connective tissue and the junctional epithelium.² This makes this area the premium zone, where we must focus our efforts if we want to improve soft tissue integration.

However, this interface takes time to mature. A recent animal study suggests that the complete soft tissue maturation takes longer than that of the bone. This was unexpected because we as clinicians have always thought that soft tissue heals faster than bone, and it is related to how fast the epithelialization happens after an injury. By contrast, these recent data demonstrate that even if the epithelialization happens fast there are still changes happening at a deeper level, influencing hemidesmosomal attachment, cell proliferation and immune response.² Complete maturation requires patience. And this is why our clinical protocols must respect biological timing.

The emergence profile: two rooms, two roles 

To manage this complexity, we can divide the emergence profile into two distinct compartments: the biological room and the restorative room.³

The biological room is the deeper zone. It includes the connective tissue and the base of the junctional epithelium. This is where we need adhesion and stability. The materials used here must be biocompatible, sterile, and optimized for soft tissue adherence. Titanium and zirconia are the best options.

The restorative room is more coronal. This is the zone of esthetics and hygiene. Here, we need materials that are cleanable and esthetically pleasing. Always, (i) the morphology, (ii) the material, and (iii) the clinical approach must all be adapted to the specific biological and functional needs of each compartment.

Morphology 

In the biological room, the emergence profile should be straight or slightly concave. This leaves space for the soft tissue and avoids pressure on the bone peaks. It respects biology.⁴

In the restorative room, the profile should be anatomical. It must support the soft tissue and recreate the natural contours. However, it must also be cleanable, because this is the maintenance zone. If we go too fast or too deep with the emergence profile in the biological zone, we risk bone resorption. Studies confirm this. The ideal configuration is a biological room of at least 2 mm and a restorative room of no more than 3 mm in the esthetic zone. In posterior areas, the restorative room can be slightly shorter, around 1.5 mm, because esthetic demands are lower. And the restorative room should never exceed 3 mm. Deeper restorations are harder to clean and maintain.

“I place posterior implants at a depth of 4 mm, and anterior implants at 4 to 6 mm apical to the buccal free gingival margin.”

Material selection  

Material choice is not just about esthetics. It is about biology.

In the restorative room, we need materials that are cleanable and esthetically pleasing. Polished zirconia, glass ceramics, and PMMA are all acceptable, but only in this zone. This is where the dental technician works, not deeper.

In the biological room, we need materials that promote soft tissue adherence. They must be sterile, biocompatible, and have the right surface chemistry. Anodized titanium and zirconia are ideal. Our recent study compared anodized abutments to machined ones.⁵ The Xeal™ surface showed faster soft tissue adherence and better integration. This points to surface chemistry as the next frontier in prosthetic design, in order to promote faster and stronger cell adherence and healthier immune response.

Clinical approach  

Another key principle is to avoid disconnections. Every time we remove and reconnect an abutment, we disrupt the soft tissue seal. We introduce contamination and compromise healing. This is why the “one abutment, one time” approach works best for esthetics. I place the final abutment at the time of surgery and never remove it. All the prosthetic work is then done at the tissue level. The temporary can be disconnected multiple times if needed, but the implant-abutment interface and hemidesmosome band remain untouched.

In a study, we investigated this approach, not only in the context of bone preservation but also the soft tissue health thanks to STL analysis.⁶ We observed not only better bone stability but also bone gain in most cases. The soft tissue outcomes were significantly improved.

Timing is everything  

Time is a critical factor, especially when working with GBR or connective tissue grafts. We cannot expect a new papilla to form in two weeks. We must wait and allow the tissue to mature.

In some cases, we shape the soft tissue with a temporary restoration before placing the implant. We create the papilla and define the emergence profile. Only then do we place the implant, using a flapless approach. The result is a stable and esthetic outcome with minimal disruption to the soft tissue.

This is the prosthetics-first mindset. We (re)create and design the tissue first, then we place the implant. This sequence respects biology and improves predictability.

Clinical execution  

In this clinical case, Nobel Biocare N1™ implants were used. The treatment began with GBR and CT graft recreating the tissue necessary and planned for an ideal esthetic outcome. Then the treatment proceeded by shaping the soft tissue using a temporary restoration to define the papilla and emergence profile. Once the desired contours were achieved, implants were placed using a flapless technique, preserving tissue integrity and minimizing trauma. A key advantage of the Nobel Biocare N1 system is its compatibility with the “one abutment, one time” protocol and the Xeal surface present on the abutment base. The final abutment base was placed at surgery and left undisturbed, maintaining the soft tissue seal and reducing bacterial contamination. A temporary crown was connected to support the tissue during healing. The emergence profile was designed with a concave shape in the biological zone for tissue stability and an anatomical form in the restorative zone for esthetics and hygiene. After full tissue maturation, the final restoration was placed. At the 5-year follow-up, outcomes remained stable: preserved papillae, healthy mucosa, and no bone loss or soft tissue recession.

Vision for long-term success  

Achieving success in implant dentistry requires a harmonious integration of prosthetic and surgical components. The wrong prosthetic design can compromise even the best bone graft. This is why the two disciplines must work together. Digital workflows help us plan and execute with precision, but the key is understanding and respecting biology.

Each patient is different. Each case is unique. Periodontal history, systemic conditions, and immune response all influence outcomes. We now know that even the surface of the abutment could change the cytokine levels in the sulcus.

We are entering a new era. An era where prosthetic design is not just mechanical but biological. Where surface chemistry, emergence profile, and clinical timing come together to create long-lasting and predictable results.

This is the path for the future. And it begins with understanding the soft tissue barrier.