Clinical Comparison of On1 Two-stage Abutment With One-stage Abutment on Different Implant Neck Design

In clinical implant treatment, the healing abutment or temporary abutment needs to be removed or replaced multiple times after implant insertion and before prosthesis restoration. During this process, the friction between connective tissue around the implant cannot be avoided. Different from natural periodontal tissue, soft tissue around the implant lacks the periodontal ligament barrier and periodontal ligament blood supply, and is more likely to be damaged during repeated wearing. The integrity, health and stability of the peri-implant connective tissue is crucial to the implant osseointegratio. Through randomized controlled trials and meta-analysis, Marco Tallarico et al found that repeated removal of one-stage abutments can significantly increase bone resorption. Based on this situation, the design of implant neck and abutment, especially the design concept of smooth collar, has attracted widespread attention. The design of smooth collars with different heights can isolate the mechanical damage of the abutment to the connective tissue around the implant to different degrees. Among them, the On1 two-stage abutment has a smooth collar with a height of 1.75-2.5mm, and the Nobel implants have a smooth neck design ranging from 0-0.75mm to protect the connective tissue around the implant. Through a systematic review and meta-analysis, Qing-qing Wang et al concludes that direct mechanical stimulation from the abutment has long-term adverse effects on peri-implant connective tissue and bone tissue. However, whether the On1 two-stage abutment has a positive effect on the stabilization of the peri-implant soft tissue and bone tissue remains to be studied. At the same time, the relative height of the smooth collar increased by the On1 abutment in the implants with different neck designs varies to some extent, and further research is still needed to provide evidence about the effect of the On1 abutment on the tissue surrounding the implants with different neck designs. In