Dental implants are widely used to replace missing teeth and restore oral function and aesthetics. One of the key factors affecting the long-term success of dental implants is the stability of the bone surrounding the implant, particularly the crestal bone around the implant neck. Implant insertion depth relative to the alveolar crest may influence peri-implant tissue health and marginal bone remodeling.

This randomized controlled clinical trial aims to evaluate the influence of implant placement depth on peri-implant health and radiographic bone changes around short dental implants placed using guided surgical protocol. All implants will be placed using the Bicon Implant System following computer-guided implant planning and surgical guide fabrication to ensure precise implant positioning.

Participants requiring implant therapy will be randomly allocated into two groups. In the test group, implants will be placed 2 mm below the crestal bone level (subcrestal placement). In the control group, implants will be placed at the crestal bone level (crestal placement). Implant placement will be performed using guided implant surgery to standardize surgical positioning and minimize variability in implant angulation and depth.

Clinical parameters related to peri-implant health, including Modified Plaque Index, Implant Mucosal Index, Peri-implant Mucosal Tissue Index and Probing Depth during follow-up visits at 3, 6 and 12 months. In addition, standardized radiographic examinations will be performed to measure peri-implant Crestal bone level changes at 12 months.

The primary objective of this study is to determine whether subcrestal implant placement (2 mm below the bone crest) results in improved preservation of peri-implant crestal bone compared with crestal implant placement. Secondary outcomes will include assessment of peri-implant soft tissue health and overall implant stability.

The findings of this study may help clarify the optimal implant insertion depth for short implants placed using guided surgery and may contribute to improving long-term implant success and peri-implant tissue stability.

Dental implants have become a predictable and widely accepted treatment modality for replacing missing teeth and restoring oral function, aesthetics, and patient quality of life. Long-term implant success is highly dependent on the preservation of peri-implant hard and soft tissues, particularly the stability of the crestal bone surrounding the implant neck. Early marginal bone remodeling following implant placement is considered a physiological process; however, excessive bone loss may compromise implant stability, prosthetic outcomes, and long-term implant survival.

Several factors have been suggested to influence peri-implant crestal bone remodeling, including implant design, implant-abutment connection, surgical technique, loading protocol, soft tissue thickness, and implant placement depth relative to the alveolar crest. Implant insertion depth has gained increasing interest because it may influence the establishment of peri-implant biologic width, soft tissue adaptation, and the position of the implant-abutment interface relative to the crestal bone. Subcrestal implant placement has been proposed as a potential strategy to improve marginal bone stability and optimize soft tissue emergence profile; however, evidence regarding its clinical benefits compared with crestal implant placement remains inconclusive.

Peri-implant health is typically assessed through a combination of clinical and radiographic parameters. Clinical parameters such as probing depth, plaque accumulation, bleeding on probing, and soft tissue condition provide important information regarding peri-implant tissue stability and inflammation. Radiographic evaluation remains essential for detecting marginal bone changes, which are considered a key diagnostic criterion for peri-implant disease progression and long-term implant success.

9. Periodontology 2000 - 2024 -…

The present randomized controlled clinical trial aims to evaluate the influence of implant placement depth on peri-implant health and radiographic crestal bone changes around short dental implants placed using a guided surgical protocol. The study will utilize the Bicon Implant System and a computer-guided implant placement workflow to ensure standardized implant positioning and minimize surgical variability. Digital implant planning will be performed using cone-beam computed tomography (CBCT) and virtual implant planning software. A surgical guide will be fabricated to allow accurate and reproducible implant placement according to the planned position.

Eligible participants requiring implant therapy will be randomly assigned to one of two treatment groups. In the test group, implants will be placed 2 mm below the crestal bone level (subcrestal placement). In the control group, implants will be placed at the crestal bone level (crestal placement). All implants will be placed using a guided implant surgery protocol to standardize implant angulation, position, and insertion depth.

Following implant placement, patients will undergo routine postoperative care and follow-up visits. Clinical parameters related to peri-implant health will be evaluated at 3, 6, and 12 months following implant placement. These clinical parameters will include:

Modified Plaque Index

Implant Mucosal Index

Peri-implant Mucosal Tissue Index

Probing Depth

These indices are commonly used to monitor peri-implant tissue conditions and detect early signs of inflammation or disease progression. Clinical probing and soft tissue evaluation provide essential diagnostic information regarding peri-implant mucosal health and tissue stability.

9. Periodontology 2000 - 2024 -…

Radiographic assessment will be performed using standardized periapical radiographs to evaluate peri-implant marginal bone levels. Radiographic measurements of crestal bone level changes will be performed at baseline and at 12 months after implant placement. The distance between the implant reference point and the first bone-to-implant contact will be measured to determine peri-implant marginal bone remodeling.

The primary outcome of the study is the evaluation of radiographic peri-implant crestal bone level changes after 12 months in implants placed at crestal and subcrestal levels.

Secondary outcomes include the assessment of peri-implant soft tissue health, including plaque accumulation, mucosal inflammation, and probing depth changes over the follow-up period.

This study aims to determine whether subcrestal implant placement (2 mm below the alveolar crest) provides improved preservation of peri-implant crestal bone and peri-implant tissue health compared with crestal implant placement when using a standardized guided implant surgery protocol.

The findings of this clinical trial may contribute to improving clinical decision-making regarding optimal implant insertion depth and may provide evidence-based guidance for implant placement protocols using short implants and guided surgical techniques.

Inclusion Criteria:

1. Adults aged 18 years or older requiring dental implant therapy for replacement of a missing tooth in the posterior maxilla or mandible.
2. Presence of sufficient bone volume to receive a short dental implant without the need for bone augmentation procedures.
3. Patients in good general health or with controlled systemic conditions that do not contraindicate implant surgery.
4. oral hygiene, defined as a plaque score ≤25%.
5. Presence of healthy or treated periodontal tissues prior to implant placement.
6. Patients willing and able to return for follow-up visits at 3, 6, and 12 months.
7. Patients who provide written informed consent to participate in the study.

Exclusion Criteria:

1. Patients with uncontrolled systemic diseases (e.g., uncontrolled diabetes mellitus, immunosuppressive disorders).
2. History of radiotherapy in the head and neck region.
3. Patients currently receiving bisphosphonate therapy or other medications affecting bone metabolism.
4. Active periodontal disease or untreated oral infections.
5. Heavy smokers (≥10 cigarettes per day).
6. Presence of parafunctional habits such as severe bruxism or clenching.
7. Patients requiring simultaneous bone grafting or sinus augmentation at the implant site.
8. Pregnant or lactating women.
9. Patients unable or unwilling to comply with the study protocol or follow-up schedule.