Clinical and Radiographic Comparison of Two Implant-Abutment Connections

This study aims to compare the effect of the N1 implant system, featuring a new macro design with a TiUltra surface and a trioval implant-abutment connection placed in the posterior region as a splitmouth in single-unit implants, with that of Xeal abutments on Nobel Active conical connection implants, also featuring a TiUltra surface, on peri-implant marginal bone loss.

The stability of both soft and hard tissues is crucial for maintaining long-term peri-implant tissue health. In this context, various surface modifications have been studied to enhance osseointegration. Developed in recent years to optimize tissue integration at all levels of the implant, TiUltra™ surface features an ultra-hydrophilic, multi-zone, and anodized surface architecture. The TiUltra™ surface topography gradually changes from the implant neck to the apex, providing a biocompatible and stable surface at the soft tissue level while supporting osseointegration with a moderately rough and porous structure at the apex. A healthy soft tissue barrier, defined as peri-implant soft tissue integration (mucointegration), plays a critical role in protecting peri-implant bone by preventing bacterial colonization and related inflammatory processes. Therefore, in recent years, focus has been placed on implant and abutment connection design, surface topography, and surface chemistry. Various strategies have been used to maintain peri-implant tissue stability, including platform switching, transmucosal abutments, two-piece abutments, and modifications to the implant collar and implant-abutment interface, such as one-abutment one-time concepts. A new biology-driven implant concept has also been developed to improve osseointegration and mucointegration: the Nobel Biocare N1™ system. The system: It is based on a biological concept that combines the OsseoShaper™ cutting tool, which protects vital bone with low speed, irrigation-free operation, the OsseoDirector™, which guides implant positioning, the Xeal surfaced On1 abutment, and the TiUltra-surfaced N1 implant.

All implants will be placed using standard surgical protocols by the same brand. The implants will be placed in both groups during the same session. Local anesthesia will be achieved in surgical areas using the bilateral vestibular infiltration technique. A crestal incision will be made using a size 15 scalpel, and the mucoperiosteal flap will be elevated. In the test group, following the manufacturer's protocol, the implant site. The Nobel Biocare N1™ Implant will insert subcrestally at 25 rpm with an insertion torque of 35 Ncm. In the control group, osteotomy preparations are performed at 600-800 rpm, after which the Nobel TiUltra Active implants are placed subcrestally with an insertion torque of 35 Ncm. Following primary stabilization, the heights of the definitive two-piece abutments will be determined at the time of implant placement surgery based on the supracrestal tissue height, with heights of 1.75 mm and 2.5 mm recorded in both groups. The On1/N1 healing abutment will then be fitted on N1/On1 Base, and the surgical field will be sutured. The dental implant sites will primarily be closed with 4-0 resorbable Vicryl sutures. On1/N1 Temporary abutments will be placed, and temporary crowns will be delivered at the same day with operation day. After implant placement, a temporary abutment designed explicitly for temporary prosthesis application and a temporary prosthesis with approximately 1 mm infraocclusion will be fabricated. Following the dental implant treatment after 3 months, On1/N1 universal abutments will be torqued and screwed-retained porcelain fused to metal prosthetic final restorations will be delivered.

Clinical and Intraoperative Measurements Before the operation, keratinized mucosal width (KMW) and mucosal thickness (MT) will be measured at baseline (Tb).

Peri-implant clinical measurements: modified plaque index (mPI), modified gingival index (mGI), periodontal pocket depth (PD), bleeding on probing % (BOP%), KMW, and MT will be recorded at permanent prosthetic functional loading (T0), 1 month (T1), 3 month (T2), 6 months (T3), and 12 months (T4) following prosthetic functional loading. Mesial and distal adjacent to single-unit dental implants will be recorded as tooth or edentulous. Intraoperatively, implant placement depth at mesial, distal, buccal, and lingual aspects will be recorded. And also, supracrestal tissue height will be measured.

Digital aesthetic assessment in the study will be performed by superimposing intraoral scans and radiological images on a digital platform.

Marginal bone level will be measured in standardized periapical digital radiographs. Periapical radiographs will be obtained with the parallel long-cone technique with O-ring film-holder after immediately implant placement, at prosthesis functional loading (following 4 months of implant placement) (T0), 1 month (T1), 3 month (T2), 6 months (T3), and 12 months (T4) after prosthesis loading.