Abutment Macro Design and Peri-implant Tissues

Implant placement and abutment design will be planned with a computer software for guided implant treatment (SIMPLANT). The surgical implant placement will be performed under manufacturer's protocol by placing the implant platform 1mm below the buccal aspect of the osteotomy (Koutouzis et al 2013). Virtually designed, permanent CAD-CAM fabricated abutments (ATLANTIS, DENTSPLY) with different configuration of the subcritical contour (emergence shape) will be connected to the implants and temporary crowns will be delivered.

Implants of the Group 1 will have permanent abutments with a concave configuration of the subcritical contour (emergence shape).

Implants of the Group 2 will have permanent abutments with a convex configuration of the subcritical contour (emergence shape).

The patients will be restored with single crowns 3 months following implant installation.

A randomization protocol will be produced from a computer-generated list for the distribution of subjects in the two treatment groups.

General Inclusion criteria:

• - Age more than 21 years
• Absence of relevant medical conditions
• Availability for 12 month follow-up

Specific Inclusion criteria:

• One missing tooth in the maxillary premolar region
• Presence of two adjacent teeth at the implant site
• Absence of periodontal disease
• Healed osseous architecture enough to receive an implant with a diameter of at least 3.5 mm and a sufficient amount of bone for placing implants with a length of at least 9 mm

General Exclusion Criteria:

• - Pregnancy at the screening visit.
• Smoking more than 10 cig/day

Specific Exclusion criteria:

• Adjacent implants
• Presence of periapical radiolucency at the adjacent teeth
• Missing adjacent teeth