The purposes of this study are to compare the blood perfusion and early healing of horizontal mattress suture with vertical mattress sutures following open-flap implant surgery. Patients wanting single implant replacement in esthetic area will be recruited. This is a randomized, open-label, controlled clinical trial. Noninvasive procedures will be used to assess the primary and secondary outcomes.

Inclusion Criteria: With sufficient bone width (≥6mm), With mesial-distal distance over 8mm, age over 18, Willing to participate Exclusion Criteria: Patients want multiple adjacent implant replacements in esthetic area, Untreated periodontitis, Smokers, Diabetes mellitus

The overall aim of this study is to compare the microcirculation changes of peri-implant soft tissues following open-flap implant surgery using different suture techniques. Subjects fulfilling the inclusion and exclusion criteria will be invited to participate in the study and randomized to one of the two groups: vertical mattress suture (test group) and horizontal mattress suture (control group) on a 1:1 ratio. A laser Doppler flowmetry machine (LDF) (LW1111, LEA) will be used to measure the tissue perfusion. Assessment will be performed at different time, including: Baseline Assessments (presurgical measurements) - T0; Immediate after anesthesia - T1; Immediate after suture - T2; 1 hour after surgery - T3; 2 hours after surgery - T4; 6 hours after surgery - T5; 24 hours after surgery - T6; 72 hours after surgery - T7; 7 days after surgery - T8; 14 days after surgery - T9; 30 days after surgery - T10. The primary outcome is blood perfusion volume (PU) change during the observation period. And secondary outcomes include blood flow velocity change during the observation period, hemoglobin count change during the observation period, blood oxygen saturation change during the observation period; three-dimensional soft-tissue volumetric changes during the observation period, changes in clinical wound healing score during the observation period, PROMs (VAS).

Inclusion Criteria:

1. Aged 18 and above
2. Subjects want single implant treatment in esthetic area (premolar to premolar) in maxilla
3. With sufficient bone width (≥6mm)
4. With mesial-distal distance over 8mm
5. Evidence of subject ability to achieve good oral hygiene and control periodontitis in the whole of the dentition (FMPS<20% and FMBS<20%)
6. Ability to understand study procedures and to comply with them for the entire length of the study. Ability and willingness to give written informed consent.

Exclusion Criteria:

1. Subjects want multiple adjacent implant treatment
2. Patients with inadequate bone volume where major bone augmentation would be required at implant location.
3. Subjects with untreated periodontitis
4. Current smokers
5. Subjects with diabetes mellitus.
6. Pregnant females
7. Participation in another intervention trial
8. Inability or unwillingness of individual to give written informed consent.