Comparative Assessment of Marginal Bone Loss Around the Implant When Using PEEK With Composite Veneering Versus Monolithic Zirconia Restorations as Implant Restorations

Purpose of the Study

The primary purpose of this randomized controlled clinical trial is to compare two specific materials used for screw-retained dental implant restorations in the "esthetic zone" (the front of the upper jaw) to see which one better preserves the surrounding bone.

Core Research Objective

The study aims to evaluate whether PEEK (Polyetheretherketone) veneered with composite is superior to monolithic zirconia in decreasing marginal bone loss around dental implants.

The Scientific Rationale

Researchers are investigating these materials for several key reasons:

* Stress Distribution:** PEEK has an elastic modulus (flexibility) similar to human bone. It is believed this may help avoid high-stress transfer at the bone-implant interface and reduce "stress shielding," which can lead to bone loss.
* Improving on Current Standards:** While monolithic zirconia is popular due to its high esthetic potential and biocompatibility, it is very rigid, and common failures include the chipping of veneering porcelain.
* Establishing Gold Standards:** The study seeks to determine a "gold standard" for screw-retained restorations that can maximize implant survival rates and enhance the quality of life for partially edentulous patients.
* Clinical Guidance:** The findings are intended to provide clinicians with specific precautions and recommendations for implant planning in the esthetic zone to enhance overall treatment success.

Primary and Secondary Outcomes

To fulfill this purpose, the study measures two main factors:

1. Primary Outcome:** The amount of **marginal bone loss** (measured in millimeters) using digital X-rays at 6 and 12 months.
2. Secondary Outcome:The **survival rate** of the different types of restorations over the one-year follow-up period.

• PEEK (Polyetheretherketone) screw-retained implant restoration veneered with composite (Procedure), also known as PEEK: To distinguish the interventions in this specific study from those in other clinical trials, the following unique technical and procedural details should be noted: * Specific Material Combination:** The primary intervention uses PEEK (Polyetheretherketone) specifically veneered with **Visio-lign composite**, a combination chosen to mimic the elastic modulus of human bone and reduce stress shielding. * Targeted Anatomical Site:** The study is exclusively limited to the **maxillary esthetic zone** (upper front teeth), where both mechanical stress and esthetic demands are highest. * Fully Digital Workflow:** Unlike studies that may use conventional impressions, this protocol utilizes a **fully digital workflow**, including digital intraoral scans and CAD/CAM fabrication for both the PEEK and zirconia restorations. * Prosthetically Driven Surgical Guidance:** The placement of the two implants is "prosthetically driven," meaning the final tooth position dictates the surgey
• Monolithic zirconia screw-retained implant restoration (Procedure), also known as Zirconia: In this study, the **comparator group** (the control group) receives a **monolithic zirconia screw-retained restoration**. This group serves as the standard clinical benchmark against which the experimental PEEK-composite material is measured. The specific details that distinguish this intervention from others include: * Material Selection:** The restoration is made of **monolithic zirconia**, a high-strength ceramic known for its biocompatibility and esthetic potential, but which is significantly more rigid than the experimental PEEK material. * Fully Digital CAD/CAM Workflow:** Unlike traditional methods, the zirconia restoration is designed and fabricated using a **fully digital workflow**, including digital intraoral scans and computer-aided manufacturing. * Specific Anatomical Placement:** This intervention is applied specifically to **two dental implants** located in the maxillary esthetic zone

Primary outcomes

• Margina Bone Loss [the assessments are conducted at the following intervals: Baseline (T0): Immediately after the placement of the implants. 6 Months (T4): Six months after the initial implant placement. 12 Months (T5): One year after the initial implant placement]: Method: The marginal bone height level is radiographically assessed using Digital Subtraction Radiography with the DIGORA system. Technique: Researchers utilize a long paralleling technique to measure bone height in millimeters from the mesial and distal aspects of the implants. Standardization: To ensure consistency across different time points, a customized occlusal bite index (made of hard acrylic attached to a film holder) is used to standardize the film placement and the angle of the X-ray cone.

Sex: All, ages: 20 Years to 50 Years

Inclusion Criteria:

* Missing Teeth: Patients must be partially edentulous, specifically missing teeth in the upper (maxillary) aesthetic zone
* Age: between the ages of 20 and 50 years.
* Systemic Health: Individuals must be free from any systemic diseases
* Jaw Relationship: Participants must have an Angle's Class I skeletal relationship.
* Facial Structure: Patients must demonstrate normal facial symmetry

Exclusion Criteria:

* Jaw Joint Issues: Patients suffering from Temporomandibular Disorder (TMD) problems.
* Smoking Status: Heavy smokers are excluded from the study.
* Bone and Tissue Health: Patients with existing bone loss in the anterior (front) area, flabby tissues, or a sharp residual ridge.
* Neuromuscular Disorders: Any patient with a neuromuscular disorder is ineligible

• Moustafa Ali, R., Helmy, M. (2020). 'Poly ether-ether ketone veneered with composite Versus Porcelain fused to metal Full arch fixed screw retained prosthesis for atrophied mandibular ridges. One year randomized clinical and radiographic trial study', Egyptian Dental Journal, 66(Issue 4 - October (Fixed Prosthodontics, Removable Prosthodontics and Dental Materials)), pp. 2439-2449. doi: 10.21608/edj.2020.35663.1173
• Results publication: Reissmann DR, Dard M, Lamprecht R, Struppek J, Heydecke G. Oral health-related quality of life in subjects with implant-supported prostheses: A systematic review. J Dent. 2017 Oct;65:22-40. doi: 10.1016/j.jdent.2017.08.003. Epub 2017 Aug 5. PMID 28789860
• Results publication: Martins RG, Castro TS, Dib LL, Gehrke SA, Mesquita AMM. Influence of Restorative Material on the Distribution of Loads to the Bone in Hybrid Abutment Crowns-In Vitro Study. Medicina (Kaunas). 2023 Jun 22;59(7):1188. doi: 10.3390/medicina59071188. PMID 37512000
• Results publication: Yazigi C, Kern M, Chaar MS, Libecki W, Elsayed A. The influence of the restorative material on the mechanical behavior of screw-retained hybrid-abutment-crowns. J Mech Behav Biomed Mater. 2020 Nov;111:103988. doi: 10.1016/j.jmbbm.2020.103988. Epub 2020 Jul 26. PMID 32799134
• Results publication: Belser UC, Mericske-Stern R, Bernard JP, Taylor TD. Prosthetic management of the partially dentate patient with fixed implant restorations. Clin Oral Implants Res. 2000;11 Suppl 1:126-45. doi: 10.1034/j.1600-0501.2000.011s1126.x. PMID 11168262

• Study Protocol and Statistical Analysis Plan (PDF, 2024-12-02)
• Informed Consent Form (PDF, 2025-04-29)