Just like other fields of dentistry, implant dentistry continues to advance and evolve with each decade. New materials, techniques and technology offer ways to make dental implants more successful than ever before. Developments include innovations within each component of a dental implant, which include the implant itself, the abutment and the prosthetic restoration (crown, bridge or denture).
One of the most notable advancements in implant dentistry involves the abutment piece. The abutment serves a key purpose of attaching the prosthetic tooth above the gum line to the implant that has been surgically placed in the bone underneath the gum line. Implant abutments must deliver long-term strength, high stability, excellent biocompatibility and be resistant to corrosion. Without an abutment, a dental implant would not be able to function.
What Are the Advantages of Custom Milled Abutments?
Custom milled abutments have many advantages:
- They help achieve a passive fit
- The final restorations are manufactured to the patient’s exact gingival architecture, achieving an optimal emergence profile and a more esthetically pleasing outcome
- It is easier to correct the angulation of the implants
- Fewer chair-side adjustments are required, and appointments can be smoother and faster, helping to increase the efficiency of a dental office
Custom abutments may be milled from titanium or from zirconia.
Designing and Manufacturing Custom Milled Titanium
Custom abutments are manufactured in several different ways. One of the most common ways utilizes CADCAM manufacturing technology.
Virtual design allows the technician to create an abutment specifically for each patient. Using design technology, it is even possible to create virtual crown shapes to guide the design of the abutment, allowing the technician and clinician to visualize all anatomic aspects of the final restoration. Once the design is complete, the files are transferred to a milling machine, where a titanium blank or rod is milled into the custom-designed abutment. Virtual files allow multiple abutments to be created, so the patient can wear a nice provisional crown while the technician still has a duplicate to create the final restoration. But, this treatment approach will incur higher costs for the clinician, and ultimately for the patient.
After a titanium abutment is milled, it is hand finished if required. The extent of finishing depends on whether the abutment has been produced with its retentive grooves and surface anatomy or whether these will be contoured before polishing. Often CADCAM technology provides superior surface finishes compared to hand polishing.
Manufacturing Custom Milled Zirconia Abutments
Custom milled abutments can also be manufactured from zirconium rods. The demand for zirconia abutments is increasing and they can be a good option for cases where esthetics are particularly important and where the patient has thin gingival tissues. Crowns and bridges can be fabricated using higher translucency materials when tooth colored abutments are chosen.
The zirconia used to manufacture custom abutments is stabilized with yttrium trioxide. This stabilized form of zirconia has excellent mechanical properties and is highly suitable for use in the mouth. The behavior of the stabilized zirconia is very similar to stainless steel and it has a flexural strength of approximately 1200 to 1300 MPA. For comparison, the flexural strength of PFMs is approximately 1400 MPA. Stabilized zirconia can resist cyclical loading stresses and its white color can be modified to mimic the natural shades of teeth. Zirconia abutments can be kinder to the peri-implant issues compared with titanium and the risk of an inflammatory reaction is decreased.