The primary aim of this randomized clinical trial is to evaluate the influence of subcrestal implant placement depth (-2 mm vs -4 mm) on peri-implant marginal bone level changes, including marginal bone loss and bone remodeling. Secondary outcomes include implant success, peri-implant probing depth (PPD), and bleeding on probing (BoP). Partially edentulous patients requiring fixed implant-supported prosthetic rehabilitation with two implants in posterior maxillary or mandibular regions will be included. Implants will be placed subcrestally at either -2 mm or -4 mm from the bone crest, following a submerged healing protocol. Allocation to insertion depth will be randomized. Marginal bone level changes will be assessed using standardized periapical radiographs at second-stage surgery, prosthesis placement, and at 1, 3, 6, and 12 months after functional loading. PPD and BoP will be recorded at the same time points.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
80
Participants will receive bone-level dental implants placed subcrestally at either -2 mm or -4 mm below the bone crest in healed posterior sites of the maxilla or mandible, according to randomization. Implant placement will follow the manufacturer's drilling protocol, achieving a final insertion torque of at least 35 Ncm. A transmucosal abutment will be connected at the time of surgery, with height selected based on implant placement depth (2-3 mm for -2 mm placement and 4-5 mm for -4 mm placement). The abutment will be tightened to a final torque of at least 30 Ncm following a one abutment-one time protocol.
University of Valencia
Valencia, Valencia, Spain
Changes in peri-implant marginal bone level (mm)
Parallelized periapical radiographs will be obtained and a calibrated digital tool will be used to determine the vertical distance from the implant-abutment junction to the most coronal bone-to-implant contact on the mesial and distal sides. Unit of measure: Milimeters (mm)
Time frame: From abutment placement (baseline time [TB]), 1 month post (T1), and at 3 (T3) (prosthetic loading) , 6 (T6), and 12 (T12) months after definitive prosthesis placement.
Peri-implant probing depth (mm)
Peri-implant soft tissue condition will be assessed by recording PPD using a periodontal probe at six surfaces per implant (mesiobuccal, midbuccal, distobuccal, and the corresponding lingual/palatal sites) to calculate the mean of every implant. Unit of measure: Milimeters (mm)
Time frame: 1 month post-op (T1), and at months 3 (T3) (prosthetic loading) , 6 (T6), and 12 (T12) after definitive prosthesis placement.
Bleeding on probing (presence/absence)
Bleeding on probing will be measured by gently passing a periodontal probe (using \~20-25g of force) to the base of the sulcus/pocket of the prosthesis at six surfaces per implant (mesiobuccal, midbuccal, distobuccal, and the corresponding lingual/palatal sites), then waiting 30 seconds to observe bleeding. It will be recorded as a dichotomous score (yes/no). Unit of measure: Percentage of sites showing bleeding per implant.
Time frame: 1 month post-op (T1), and at months 3 (T3) (prosthetic loading) , 6 (T6), and 12 (T12) after definitive prosthesis placement.
Implant success
Assessment of the implants will be performed by categorizing them into: success (optimal health), satisfactory survival, compromised survival, or failure.
Time frame: From the time of surgery through the end of the 12-month follow-up period after definitive prosthesis placement.
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