1. Research background NobelBiocare manufacture put forward a new abutment called on1. This concept is based on a two-stage abutment in which the on1 abutment is placed directly on the implant during surgery and will not be disconnected since then. At present, there are very a few clinical prospective studies about clinical effect of Nobelparallel CC implant combined with on1 abutment.
2. Research objective This study will evaluate the clinical efficacy of Nobel parallel with on1 abutment compared to traditional healing cap in posterior teeth in a short term(one year) and long trem (five year) follow-up.
3. Study design and methods:

Design type: prospective clinical study. Study duration: 5 years Start time: From the date of adoption of ethics. End time: 2026. Follow up examination: Panoramic images will be taken at all times to measure the marginal bone level of the implant. Clinical examination and questionnaire survey will be conducted to obtain the implant conditions and patients' satisfaction. Periodontal indexes such as keratinized gingival width, plaque index, gingival index, bleeding on probe, probing depth of peri-implant tissue will be evaluate.

1. Research background NobelBiocare manufacture put forward a new abutment called on1. This concept is based on a two-stage abutment in which the on1 abutment is placed directly on the implant during surgery and will not be disconnected since then. At present, there are very a few clinical prospective studies about clinical effect of Nobelparallel CC implant combined with on1 abutment.
2. Research objective This study will evaluate the clinical efficacy of Nobel parallel with on1 abutment compared to traditional healing cap in posterior teeth during a five-year follow-up.
3. Study design and methods:

Design type: prospective clinical study (Non randomized clinical trial) Study duration: 5 years Start time: From the date of adoption of ethics. End time: 2026. Follow up examination: Panoramic images will be taken at all times to measure the marginal bone level of the implant. Clinical examination and questionnaire survey will be conducted to obtain the implant conditions and patients' satisfaction. Periodontal indexes such as keratinized gingival width, plaque index, gingival index, bleeding on probe, probing depth of peri-implant tissue will be evaluate.

Introduction to the research scheme: Implants of Nobel Parallel CC will be implanted into the posterior teeth in the Affiliated Stomatology Hospital, Zhejiang University School of Medicine since the date of ethical adoption. Forty patients with on1 abutment will be placed with implant. Forty patients with common healing abutment will be selected with the same implants simultaneously. Panoramic images will be evaluated before surgery, immediately after surgery, immediately, 3 months, 1 year, 2 years, 3 years and 4 years after prosthesis loading. Clinical examination and questionnaire survey will be carried out 4 years after prosthesis loading to obtain periodontal indexes about peri-implant tissues. Through the evaluation of the above experimental data, on1 abutment with implant will be analyzed about the clinical efficacy.

The inclusion criteria were as follows:

1. At least eighteen years old without any medical contraindications, able to tolerate dental implant surgery;
2. Planned to implant with Nobel Parallel CC™ in the maxillary or mandible posterior tooth regions with single-implant-prosthesis design;
3. No requirement for further bone augmentation;
4. Sufficient space to place the abutment and future prosthesis;
5. Adhere to follow-up.

The exclusion criteria were as follows:

1. Uncontrolled systematic diseases (blood pressure >180/100 mmHg, fasting blood glucose >8.88 mmol/L, myocardial infarction in six months, cardiac function class III to IV, third- or second-degree II atrioventricular block, and double bundle branch block et al.);
2. Using drugs such as bisphosphonates within three months;
3. Heavy smoker (≥ 10 cigarettes per day), alcoholism, and drug abuse;
4. Uncontrolled periodontitis;
5. Implant site infection;
6. Pregnancy or lactation;
7. Severe malocclusion.