Tissue Preservation in Immediate 1C Implants Using an Anatomical Prefabricated Healing Abutment

Immediate replacement of a severely damaged posterior tooth with a dental implant has demonstrated high long-term success rates while offering the advantages of shorter treatment time and fewer invasive procedures compared with delayed implant placement. Beyond successful osseointegration, preservation of healthy peri-implant soft tissue and development of an optimal emergence profile are critical determinants of long-term implant success, as they reduce food impaction and plaque accumulation, facilitate oral hygiene, and contribute to favorable esthetic and functional outcomes. Historically, conventional healing abutments have been used primarily during the uncovering phase to promote soft-tissue healing; however, their cylindrical design does not replicate the natural contour of the extracted tooth and provides limited support for peri-implant soft-tissue architecture. Consequently, clinicians often use temporary titanium abutments and composite resin to customize healing abutments, or fabricate provisional restorations to shape the soft tissues during healing.

Recent evidence suggests that customized healing abutments, which mimic the natural tooth morphology, particularly in the cervical third, may better preserve peri-implant soft tissue contours, maintain marginal bone height, reduce early loading of immediately placed implants, and facilitate the development of a natural prosthetic emergence profile. Conventional customization with composite resin on a temporary abutment is technique-sensitive, requires additional clinical time, and carries the risk of contamination of the extraction socket by excess composite material. Prefabricated scannable AHAs have been developed to overcome these limitations by conforming to the extraction socket anatomy, supporting the surrounding soft tissues to prevent collapse during healing, stabilizing the blood clot, preserving space for bone regeneration, and simultaneously functioning as scan bodies for digital impression workflows. In addition, AHAs accurately transfer the three-dimensional implant position, potentially reducing treatment time, minimizing complications associated with repeated component exchanges, improving patient comfort and satisfaction, and streamlining fabrication of the definitive implant-supported restoration.

Preliminary laboratory investigations, clinical case reports, and early prospective clinical studies support the feasibility of AHAs for soft tissue management and digital implant workflows. However, the current evidence remains limited, particularly regarding their effectiveness in preserving pre-extraction soft-tissue contours following immediate implant placement in posterior sites. Existing studies are characterized by relatively small sample sizes, heterogeneous methodologies, and limited longitudinal clinical data. Therefore, further clinical investigation is needed to determine whether scannable anatomical healing abutments provide measurable benefits over conventional approaches in preserving peri-implant soft-tissue architecture and optimizing the emergence profile prior to the fabrication of a definitive single-implant-supported crown. This study aims to compare the anatomical healing abutment's capacity to preserve preextraction soft tissue contours, with attention to the position of the mid-facial gingival margin, enabling the delivery of the final crown in a shorter treatment period without the need for further soft tissue conditioning. The findings of this study will address an important gap in the literature and contribute to evidence-based protocols for immediate implant therapy and digital restorative workflows.Despite these theoretical and practical advantages, the currently available scientific literature remains relatively limited. Existing investigations primarily consist of laboratory studies, technical reports, case series, retrospective analyses, and a limited number of prospective clinical investigations. Although preliminary findings suggest favorable soft tissue management, simplified digital workflows, and acceptable clinical outcomes, robust randomized controlled clinical trials directly comparing Anatomical Healing Abutments with conventional healing abutments remain scarce. The available literature is further limited by relatively small sample sizes, heterogeneous methodologies, short observation periods, and inconsistent outcome measures.

Additional randomized clinical investigations using standardized surgical protocols, digital outcome measurements, validated esthetic indices, radiographic analyses, patient-reported outcomes, and longitudinal follow-up are needed to establish evidence-based recommendations regarding their clinical effectiveness.

The present study has been designed to address this important knowledge gap. The primary purpose of this multicenter randomized controlled clinical trial is to determine whether a prefabricated scannable Anatomical Healing Abutment provides superior preservation of peri-implant soft tissue contours compared with a conventional titanium healing abutment following immediate implant placement in posterior extraction sites. Rather than focusing exclusively on implant survival, the investigation comprehensively evaluates biological, prosthetic, radiographic, esthetic, digital, patient-centered, and economic outcomes throughout one year of functional loading.

Specifically, the primary objective is to quantify three-dimensional peri-implant soft tissue volumetric changes by superimposing sequential intraoral digital scans obtained at predetermined clinical time points. Advanced metrology software will be used to calculate volumetric differences within predefined regions of interest, allowing highly precise longitudinal assessment of peri-implant soft tissue preservation. This methodology provides substantially greater sensitivity than conventional linear measurements alone and permits objective evaluation of subtle soft tissue changes occurring throughout healing.

In addition to the primary endpoint, numerous secondary outcome measures have been incorporated to provide a comprehensive assessment of treatment effectiveness. These include longitudinal evaluation of the mid-facial mucosal margin, keratinized mucosa width, Pink Esthetic Score, implant position accuracy, three-dimensional hard tissue remodeling, marginal bone level changes, implant survival, peri-implant tissue health, implant stability, biological complications, prosthetic complications, patient-reported oral health-related quality of life, patient satisfaction, and treatment cost-effectiveness. Collectively, these outcomes will provide a multidimensional assessment of clinical performance and permit evaluation of whether preservation of peri-implant anatomy translates into measurable improvements in esthetic, functional, and patient-centered outcomes.

The investigators hypothesize that participants receiving the Anatomical Healing Abutment will demonstrate superior preservation of peri-implant soft tissue volume throughout healing compared with participants treated using conventional healing abutments while maintaining comparable implant survival, safety, and peri-implant tissue health. If confirmed, these findings may support broader implementation of anatomically contoured healing abutments as part of contemporary immediate implant therapy and digital restorative workflows.

This investigation is designed as a prospective, multicenter, randomized, controlled, longitudinal clinical trial conducted at the University of Illinois Chicago College of Dentistry and the Indiana University School of Dentistry. Both institutions will follow an identical clinical protocol, standardized surgical procedures, calibrated examiner training, common eligibility criteria, and uniform methods for data collection and outcome assessment. Conducting the study at two academic institutions increases the generalizability of the findings while maintaining protocol standardization and high-quality clinical oversight. The study will be coordinated collaboratively by the Co-Principal Investigators at each institution, with centralized statistical analysis performed after completion of participant follow-up.

Thirty participants requiring immediate replacement of a hopeless posterior tooth will be enrolled. Eligible participants will be randomly assigned in a 1:1 allocation ratio to one of two treatment groups consisting of fifteen participants each. Randomization will occur immediately following implant placement using a computer-generated allocation sequence incorporated into the REDCap® randomization module. The allocation sequence will be prepared by the study statistician before initiation of enrollment, and no stratification factors will be applied. Participants will remain blinded to their treatment allocation throughout the study, whereas the treating clinicians cannot be blinded because of the visible differences between the healing abutment designs.

The intervention evaluated in the test group consists of the Straumann® Anatomical Healing Abutment, a commercially available, FDA-cleared, and CE-marked healing component manufactured from polyether ether ketone (PEEK). The device is specifically designed to reproduce the anatomical cervical contour of posterior teeth while simultaneously functioning as a digital scan body. Unlike conventional healing abutments, the Anatomical Healing Abutment is intended to support peri-implant soft tissue architecture immediately after implant placement, facilitate preservation of the emergence profile, and allow direct acquisition of digital implant impressions without removal of the healing abutment. Throughout the healing phase, the device remains connected to the implant until definitive prosthetic procedures are initiated.

Participants allocated to the control group will receive the Straumann® Conventional Titanium Healing Abutment. This commercially available healing component represents the current standard of care for transmucosal healing after implant placement. Although highly successful for protecting the implant platform during healing, the conventional healing abutment possesses a cylindrical emergence profile that does not reproduce natural tooth anatomy and therefore serves as the comparator intervention in this investigation. Aside from the healing abutment assigned by randomization, every other aspect of treatment will be identical between study groups.

Participant eligibility has been carefully defined to create a relatively homogeneous study population while minimizing factors known to influence implant healing and peri-implant tissue remodeling. Eligible participants will be adults between 20 and 75 years of age with American Society of Anesthesiologists (ASA) Physical Status Classification I or II who require immediate implant placement for a hopeless maxillary or mandibular posterior tooth. Subjects must be willing to provide written informed consent, comply with all study procedures, and attend every scheduled follow-up visit. Candidate teeth must present with intact or successfully restored adjacent teeth and satisfy both clinical and radiographic criteria for immediate implant placement.

To minimize potential confounding variables, participants with conditions known to adversely affect wound healing or implant success will be excluded. These exclusion criteria include poorly controlled diabetes mellitus, smoking, immunodeficiency, previous head and neck radiotherapy, use of antiresorptive medications, pregnancy, poor oral hygiene, active periodontal disease, acute endodontic infection, inadequate occlusal relationships, insufficient restorative space, unfavorable soft tissue phenotype, significant mucogingival recession, or inadequate alveolar bone morphology. Following preliminary clinical screening, all potential participants will undergo cone-beam computed tomography (CBCT) to confirm the presence of sufficient facial

• Mid-facial mucosal margin (MM) level [Срок оценки: From enrollment to the 12-months follow-up]
• Keratinized mucosa width (KMW) [Срок оценки: From enrollment to 12-months follow-up]
• Pink Esthetic Score (PES) [Срок оценки: From prosthesis delivery to 12-months follow-up]
• Implant position accuracy [Срок оценки: From implant planning to immediate post-implant placement]
• 3D hard tissue change (3DHT) [Срок оценки: From implant placement to 12-months follow-up]
• Marginal Bone Level (MBL) [Срок оценки: From implant placement to 12-months follow-up]
• Implant survival rate (SR) [Срок оценки: From implant placement to 12-months follow-up]
• Peri-implant Tissue Health Status [Срок оценки: From loading (prosthesis delivery) to the 12-months follow-up]
• Insertion Torque [Срок оценки: Perioperative (at T3 - Implant Placement)]
• Biological Complications [Срок оценки: From prosthesis delivery to the 12-months follow-up]
• Implant Stability [Срок оценки: Perioperative and at Day 90 (T4 - Implant Impression)]
• Prosthetic Complications [Срок оценки: From prosthesis delivery to the 12-months follow-up]