Immediate Implants in Front Teeth With Bone Loss: Regeneration and Temporary Crown in a Randomized Clinical Study

Introduction The standard treatment for buccal bone dehiscence (BBD) around dental implants is the use of a bone graft combined with a collagen membrane. However, there is continuing debate regarding whether the addition of a collagen membrane is essential for optimal regenerative outcomes. In the context of immediate implant placement (IIP) at sites with BBD, it has been proposed that replacing the collagen membrane with an autogenous soft tissue graft may improve peri-implant tissue volume and enhance aesthetic results. This clinical trial is designed to evaluate the biological and clinical performance of a connective tissue graft compared with a collagen membrane when used together with deproteinized bovine bone mineral with collagen (DBBM-C) for simultaneous regeneration in aesthetic areas.

Objectives The main objective of this randomized clinical trial is to evaluate the non-inferiority of buccal bone defect resolution after immediate implant placement in aesthetic regions, comparing two regenerative approaches: (1) autogenous connective tissue graft combined with DBBM-C and (2) collagen membrane combined with DBBM-C. The study aims to determine whether a connective tissue graft can achieve comparable regenerative and aesthetic results to the conventional collagen membrane technique.

Materials and Methods This controlled, randomized clinical trial will be conducted at the Department of Periodontology within the research line of surgical techniques, morbidity, and biomaterials. The study protocol is version 1.0, dated March 18, 2025. A total of twenty-four patients will be included and randomly assigned into two equal groups of twelve participants each (test and control). The study duration will be twelve months, and each participant will attend eight scheduled visits.

Sample Size Calculation The calculation was based on the main outcome variable-vertical buccal bone gain after twelve months. Assuming no real difference between treatment groups, twenty-four patients will provide 90% power for the lower bound of the one-sided 95% confidence interval to remain above the non-inferiority margin of 1.5 mm.

Inclusion and Exclusion Criteria Patients indicated for immediate implant placement in aesthetic areas presenting with buccal bone dehiscence will be eligible. All participants must be in general good health and suitable for oral surgery. Specific inclusion and exclusion criteria will follow standard clinical and ethical guidelines for implant therapy.

Surgical Procedure Atraumatic tooth extraction will be performed without flap elevation, and the socket will be carefully curetted to remove granulation tissue. Buccal bone dehiscence will be confirmed intraoperatively.

Implants (BLC, Straumann®, Basel, Switzerland) will be placed following the manufacturer's instructions and prosthetically guided planning. The buccal defect's width and depth will be measured with a periodontal probe (PCP UNC-15, HuFriedy®, Chicago, IL). A partial-thickness tunnel flap will be extended beyond the defect to allow regeneration and soft tissue adaptation.

All defects will be filled with DBBM-C (Bio-Oss® Collagen, Geistlich Pharma AG, Switzerland). After graft placement, participants will be randomly assigned to one of two groups:

• Control group: DBBM-C covered with a collagen membrane (Bio-Gide®, Geistlich Pharma AG, Switzerland) stabilized using horizontal mattress sutures (6/0 monofilament).
• Test group: DBBM-C covered with an autogenous connective tissue graft harvested from the palatal mucosa (approximately 1.5 mm thick) and stabilized similarly.

When primary stability ≥35 N/cm is achieved, an immediate screw-retained provisional restoration will be delivered without occlusal or eccentric contacts. If torque <35 N/cm, a customized healing abutment and a Maryland-type provisional will be fabricated.

Postoperative Care and Prosthetic Phase Patients will follow a soft diet and maintain oral hygiene while avoiding brushing at the surgical site for one week. After three months, digital impressions will be taken using an intraoral scanner (TRIOS 3, 3Shape, Copenhagen, Denmark), and a definitive screw-retained zirconia restoration will be fabricated and placed. All prosthetic work will be performed by experienced clinicians and dental technicians to ensure standardization.

Benefits and Risks Potential benefits include both direct and indirect effects. Clinically, patients will receive implant-supported rehabilitation that enhances masticatory function, occlusion, and aesthetics. Scientifically, participants will contribute to expanding knowledge on predictable management of buccal bone dehiscence in immediate implant placement.

Risks are minimal and limited to standard surgical complications, such as pain, swelling, bleeding, or minor infection, all of which will be managed according to established clinical protocols.

Alternative Treatments Patients who decline participation will be offered the standard implant procedure as in the control group. If implant therapy is not accepted, fixed or removable prostheses will be proposed to ensure functional and aesthetic rehabilitation.

Management of Complications Any postoperative complications will be treated according to clinical guidelines using pharmacological or surgical interventions as needed. All adverse events will be documented and managed to ensure patient safety and ethical compliance.

Materials and Equipment Materials include BLC implants (Straumann®, Basel, Switzerland), Bio-Oss® Collagen (DBBM-C), Bio-Gide® collagen membranes, and suture materials (polyvinylidene fluoride 6/0, Seralene®, and polyamide 5/0, Seralon®). Adhesive PeryAcril® 90HV (Glustitch Inc., Canada) will be used as needed. Standard surgical instruments such as periodontal probes, scalpels, Orban knives, Allen elevators, and tunneling instruments (HuFriedy®, Chicago, IL) will be used. The TRIOS 3 intraoral scanner (3Shape, Copenhagen, Denmark) will support the digital workflow.

Statistical Analysis Descriptive and inferential analyses will be performed. Descriptive statistics will include mean, standard deviation, median, range, and interquartile range for continuous variables, and frequency and percentage for categorical variables. Data normality will be tested using the Kolmogorov-Smirnov test. The primary outcome will be analyzed using repeated-measures mixed ANOVA to assess intergroup and intragroup differences over time. ANCOVA will be applied when covariate adjustment is necessary. Reliability will be measured using the intraclass correlation coefficient (ICC) for intra- and inter-examiner agreement. The significance level is set at α = 0.05.

Ethical Considerations All procedures comply with the Declaration of Helsinki and current national standards for human clinical research. Each participant will receive detailed verbal and written information and must provide signed informed consent before inclusion. Data confidentiality will be maintained at all stages.

Expected Outcomes and Clinical Significance This study aims to determine whether an autogenous connective tissue graft offers non-inferior bone regeneration compared to the conventional collagen membrane approach while improving soft tissue thickness and aesthetics. Demonstrating non-inferiority would validate the use of soft tissue grafts as a biologically sound, clinically effective alternative for simultaneous hard and soft tissue management during immediate implant placement in aesthetic regions affected by buccal dehiscence.

Inclusion criteria

• • Adult patients with ⩾ 25 years of age.

• Ability to understand all the study procedures and to comply with them along the entire study period. Ability and willingness to give written informed consent.
• Periodontal health in an intact or reduced periodontium (2017 World Workshop in Periodontal and Peri-implant Diseases and Conditions) (G. Caton et al., 2018).
• Good level of oral hygiene (Plaque Index < 20%) (Löe, 1967).
• Failing tooth in the anterior area of the maxillary arch (incisors, canines and premolars).
• Bone availability for a prosthetically driven single-unit immediate implant.
• A peri-implant BBD with a minimum vertical dimension height (VDH) of 3mm, detected by means of a CT imaging.
• Presence of adjacent teeth.
• Presence of antagonist teeth.
• Keratinized mucosa of at least 2mm on the buccal aspect of the tooth to be extracted.

Exclusion criteria

• Smokers ⩾ 10 cigarettes per day.

• Pregnant women or lactating females.
• Acute periapical infection.
• Presence of buccal/palatal and/or interproximal gingival recession in the target tooth.
• Any systemic disease or medication that contraindicates implant treatment or could influence the outcome of the therapy (i.e., non-controlled diabetes mellitus, osteoporosis, radiotherapy, bisphosphonate medication, ...).
• Long-term non-steroidal anti-inflammatory drug therapy (⩾ 3 months).
• Lack of primary manual stability of the implant during installation.