The main aim of the present study is to investigate implant success rate after 5 years of function of immediate (Test group; within 7 days of implant placement) versus delayed (Control group; 8 weeks after implant placement) loading of two-pieces zirconia implant, placed in pristine bone without bone regeneration. Implant success rate will be defined according to Buser's criteria. Secondary endpoints: Marginal bone level (MBL) evaluation by means of standardized radiographs; Clinical evaluation of biological (e.g. Plaque Index, PI; Probing Pocket Depth, PPD, Bleeding on Probing, BOP; suppuration upon probing/palpation) and prosthetic/technical complications; Clinical evaluation of soft tissue width, keratinized tissue, marginal and interproximal soft tissue recession; Patient reported outcome measures (PROMs) by questionnaire administration:

Inclusion Criteria:

• Sistemically healthy patients
• partial edentulism
• premolar position
• molar position
• Bone width and height at least 6 and 10mm, respectively.
• Keratinized tissue, at least 1 mm at implant site
• Full understanding of the proposed surgical treatments and the protocol schedule
• Full comprehension and availability to sign the informed consent form

Exclusion Criteria:

• Heavy smokers (>10 cigarettes a day)
• Serious kidney or liver diseases
• Uncontrolled diabetes
• Bisphosphonates intake
• History of radiotherapy of the head and neck
• Current antiblastic chemotherapy
• Congenital (primary) or acquired (secondary) immunodeficiency
• Pregnant women
• Connective tissue disorders

Local exclusion criteria:

• untreated stage III/IV periodontitis
• Autoimmune diseases
• oral parafunctions

Primary and secondary endpoints; indicators of central tendency; evidence summary; tables; figures.