This patient had multiple dental implants placed in the mouth (full-mouth fixed rehabilitation). The patient donated one implant as part of a clinical study. The patient received the full-mouth treatment in compensation for all the inconveniences.
After 3 months of surgery, we trephined the implant out of the mouth and analyzed it under the microscope. The histologies show a considerable amount of Bone To Implant Contact (BIC), (BIC = process to measure the amount of bone that grows in direct contact with the implant)
The soft tissue is also adhered to the surface of the CeraRoot zirconia implant. This is very rare (or almost impossible) to see in two-piece titanium implants because the connection of the implant is at bone level, and there are higher levels of bacteria present at the implant connection, and this creates chronic inflammation and peri-implantitis.
Soft and hard tissue attachment around zirconia implants: a human histologies clinical study
High strength ceramics such as zirconium oxide (Y-TZP) is rapidly overtaking the metal-ceramic restorations due to its more esthetic and biocompatible properties. Zirconia is a ceramic with better soft tissue response due to its non-conductive and non-corrosive surface. Bacteria accumulates more easy and rapidly to Titanium surfaces to Zirconia.
The purpose of this study was to evaluate thru histological analysis the type and quality of bone and soft tissue attachment on the surface of a zirconia implant in healthy patients 3 months after implantation.
Materials and methods:
Two patients that underwent full-mouth oral rehabilitation and were part of a clinical study donated two of their implants for histological analysis. The two patients were male, over 60 years old, healthy , fully edentulous and had to have alveolar bone dimensions at the second molar region of about 12 x 12 x 12mm. The implants used were one-piece with a 4.1mm diameter cylindrical shape. One patient had the abutment healing in the mouth without any type of covering. The other patient had a zirconia crown permanently cemented on the day of surgery. After three months of healing, the implants were trephined out of the mouth using 10mm drill. The socket was grafted with xenograft and PRF. The healing of the implant extraction site was uneventful. Both patients were restored with fixed zirconia full contour bridges at 4 months and a half after implant placement.
After the specimens were processed at the University of Minnesota (USA) it was possible to observe on both implants a healthy soft tissue attached on the surface of the acid etched CeraRoot one-piece zirconia implant. The location where the implants were placed in the mouth (between the first and second upper molar) showed a highly spongy (cancellous) bone and therefore the bone to implant contact (histomorphometric) analysis did not bring any relevant information. The histological specimens showed new bone formation in direct contact with the threaded and non-threaded area (transgingival portion) at three months post surgery. Both implants improved the Periotest values (from +5 to -2) from day of surgery to day of retrieval. These results demonstrate that the acid etched surface of the one-piece zirconia implants seems to be appropriate to achieve soft tissue attachment and osseointegration at three months after surgery and almost eliminates the inflammatory infiltrate commonly seen in the bone level prosthetic connections of two-piece titanium implants.
One-piece implants with acid etched surface have been available in the market since 2004 and the clinical studies show less tendency to bone loss and better soft tissue health due to its reduction of bacteria colonization in the prosthetic connection. The restoration and cementation of these kind of implants is being done at gum level and therefore the depth of the gingival pockets around these implants is very similar to a natural tooth, and very different when comparing it to a two-piece titanium bone level implant. These histological analysis also indicate that Y-TZP ceramics with roughened surface has the same amount of osseointegration capabilities as the titanium dental implants. Patients with metal-free / holistic lifestyle and patients that have high sensitivities to some of the chemical elements found in titanium alloys could benefit from these type of implant materials since the material seems to perform with no biological or mechanical failures after more than 10 years of use in the mouth.