Immediate Loading in Single Tooth Implants

The planned study is designed to provide evidence for the application of early implant placement with partial bone-healing and either an immediate or an early restoration/ loading protocol.

Materials and methods

The study will be conducted according to the recommendations published as the CONSORT statement and respecting the intention to treat principle. Participants will be enrolled if they present with a mandibular first molar that has to be extracted, and require implant treatment for replacement of the molar. Ridge preservation using a well-documented xenogeneic bone substitute will be done following the extraction. After 12 weeks of healing, a cone-beam computed tomography (CBCT) and a digital intraoral scan will be taken, followed by digital planning of the implant position and the additive construction of a surgical drill guide by means of rapid prototyping using a 3-D printer. Afterwards, the participants will be randomized into the two study groups:

Group A (immediate loading): A screw-retained PMMA implant provisional bonded to a titanium base will be fabricated subtractively by computer aided design/ computer aided manufacturing (CAD/CAM), based on the data of the digitally planned implant position.

Group B (early loading): No further preparation has to be done.

Before finishing 16 weeks post-extraction, implants (Straumann Standard Implant RN, TiZr, minimum length: 10mm, minimum diameter 4.1mm) will be placed in both study groups using sCAIS. During surgery, the surgeon will not know if the participant was allocated to Group A or Group B. Directly after surgery, digital intraoral scans will be obtained, to record the final implant position. Afterwards, either the prepared implant provisional (Group A; immediate loading) or a healing cap (Group B, early loading) will be inserted into the implant.

4 weeks after implant placement the participants in Group B will receive a loaded, screw-retained implant provisional, based on the data of the post-surgery scan. 6-months after implant placement participants will receive final screw-retained single implant crowns. The study end will be a final follow-up visit after 12 months. Participants will be invited for further follow-up visits up to 5 years. (not part of the present proposal) Implant survival/ success will be evaluated according to the criteria described by Buser et al. All seconda

Inclusion criteria

• Age ≥ 20 years
• Willingness to sign informed consent and to participate in the study
• Plaque index according to Silness and Loe of < 35% [26]

At site level:

• Presence of a mandibular first molar that has to be extracted
• Sufficient vertical interocclusal space for the placement of an implant crown (7 mm)
• Presence of an opposing natural or artificial tooth
• Ridge height sufficient for the placement of a ≥ 10 mm-long implant
• Sufficient ridge width for the placement of a 4.1mm diameter implant

Exclusion criteria

At patient level:

• Any physical or mental disorder that would interfere with the ability to perform adequate oral hygiene or the capability of providing written informed consent and compliance to the protocol
• Any disorder that would interfere with wound healing or represent a contraindication for implant surgery such as, but not limited to, uncontrolled diabetes or conditions resulting in or requiring immunosuppression, radiation, chemotherapy, frequent use of antibiotics or antiresorptive medication such as bisphosphonates
• Pregnancy or lactation
• Heavy smoking habit with ≥ 10 cig/d
• Severe bruxism or clenching habits, present oro-facial pain at site level
• Insufficient ridge width/height for the study implant