Clinical Performance and Fit of 3D-Printed Versus Milled Endocrowns: An 18-Month Trial (Endocrowns)

July 12, 2026 updated by: Yara Ahmed Elgammal, October 6 University

Clinical Performance and Restoration Fit of 3D-Printed Versus Milled Biomimetic Resin Composite Endocrowns: 18-Month Randomized Clinical Trial.

The goal of this clinical trial is to learn whether 3D-printed resin composite endocrowns perform as well as milled resin composite endocrowns in restoring endodontically treated teeth. It will also learn how well the restorations fit over time.

The main questions it aims to answer are:

Do 3D-printed endocrowns and milled endocrowns show different clinical performance? Do 3D-printed endocrowns and milled endocrowns differ in restoration fit over 18 months?

Researchers will compare two fabrication methods:

Additive manufacturing: 3D-printed resin composite endocrowns. Subtractive manufacturing: milled resin composite endocrowns.

Participants will:

Be recruited from the Conservative Dentistry Department, Faculty of Dentistry, October 6 University.

Receive tooth preparation after confirmation of satisfactory root canal treatment.

Have their teeth prepared using standardized endocrown guidelines by one calibrated operator.

Have digital scans taken of the prepared tooth, opposing arch, and bite registration.

Have restorations designed digitally and then assigned randomly to one of the two groups.

Receive a temporary restoration until the final endocrown is ready.

Have the final restoration tried in for fit, contacts, and occlusion before cementation.

Have a baseline post-cementation scan taken for fit assessment.

Return for follow-up visits at baseline, 6 months, 12 months, and 18 months.

Be evaluated at each visit using Modified FDI criteria and 3D digital superimposition for fit analysis.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Eligible participants will be recruited from the Conservative Dentistry Department, Faculty of Dentistry, October 6 University.

Following confirmation of satisfactory root canal treatment. Tooth preparation will follow standardized endocrown guidelines. All preparations will be performed by a single calibrated operator (Y.A.E.).

Full-arch digital impressions will be captured using an intraoral scanner, including scans of the prepared tooth, opposing arch, and bite registration. Digital files (STL format) will be used to design definitive restorations in CAD software. Following digital design, participants will be randomly allocated (1:1 ratio) to one of two fabrication groups:

Group 1 (Intervention): Additive manufacturing (3D-printed resin composite) Group 2 (Comparator): Subtractive manufacturing (milled resin composite) Teeth will be temporized with intermediate restorative material, then temporary materials will be removed and preparations cleaned. Restorations will be tried to verify fit, contacts, and occlusion.

After cementation, scan the seated restoration with the same intraoral scanner to create baseline restoration STL file (T0) for longitudinal fit assessment. Participants will be recalled at baseline (T0), 6 months (T1), 12 months (T2) and18 months (T3). At each visit, restorations will be evaluated using Modified FDI criteria (clinical performance) and 3D digital superimposition (Restoration fit via Geomagic Control X)

Study Type

Interventional

Enrollment (Estimated)

52

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

- Patient-Related Criteria

  1. Age: Between 20 and 40 years.
  2. Oral Hygiene: Good oral hygiene, evidenced by low plaque and gingival index scores.

  3. Willingness to attend regular follow-up visits during the study period

    - Tooth-Related Criteria

  4. Endodontic Quality: High-quality root canal treatment with no clinical or radiographic signs of pathology.
  5. Tooth Type: A permanent molar tooth requiring an endocrown after successful root canal treatment.
  6. Located in functional occlusion and opposing natural teeth in stable occlusal contact with the restored tooth.
  7. Teeth free from cracks, fractures, or internal resorption; supporting tissues without structural defects that may compromise restoration success

Exclusion Criteria:

- Patient-Related Criteria

  1. Parafunctional Habits: Severe bruxism, clenching, or other parafunctional habits.
  2. Allergies: to any study materials (e.g., resin composites, bonding agents).

  3. Patients with systemic diseases contraindicate elective dental treatment (e.g., uncontrolled diabetes)

    - Tooth-Related Criteria

  4. Insufficient Tooth Structure: Less than 2mm of circumferential sound denting height or deep, unrestorable.
  5. Tooth opposes prosthetic restoration.
  6. Teeth with a history of fixed prosthetic restorations (previous crowns, inlays/onlays, or bridge restorations)
  7. Periodontal Issues: Active periodontal disease, excessive mobility (> Grade 1, or a hopeless long-term prognosis.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Milled resin composite restorations fabricated using subtractive manufacturing from CAD/CAM blocks.
Subtractive Manufacturing, the control group will utilize restorations fabricated via subtractive manufacturing, specifically by milling from industrially fabricated blocks of nanohybrid composite. This method is the established gold standard for producing CAD/CAM resin composite restorations. It is known for creating restorations with excellent mechanical properties, high density, and predictable clinical performance due to the optimized, industrial-grade polymerization of the blocks. These materials, which include polymer-infiltrated ceramic networks (PICNs) and resin nanoceramics, were developed to combine the favorable properties of both ceramics and resin composites, offering a biomimetic alternative to traditional glass-ceramics.
Other: Milled resin composite restorations fabricated using subtractive manufacturing from CAD/CAM blocks.
Subtractive Manufacturing, the control group will utilize restorations fabricated via subtractive manufacturing, specifically by milling from industrially fabricated blocks of nanohybrid composite. This method is the established gold standard for producing CAD/CAM resin composite restorations. It is known for creating restorations with excellent mechanical properties, high density, and predictable clinical performance due to the optimized, industrial-grade polymerization of the blocks. These materials, which include polymer-infiltrated ceramic networks (PICNs) and resin nanoceramics, were developed to combine the favorable properties of both ceramics and resin composites, offering a biomimetic alternative to traditional glass-ceramics.
Other: Three dimensionally (3D) printed resin composite restorations fabricated using additive manufacturing
Additive Manufacturing, the intervention group will feature restorations fabricated via 3D printing. This technology is more time and cost-efficient, more accurate, and could provide a considerable alternative to the currently applied CNC milling, reduced material waste, and the ability to create complex geometries with high precision. Recent studies have shown that 3D-printed restorations can achieve promising results in terms of marginal and internal fit, which are critical for clinical longevity. This has spurred the development of novel, ceramic-filled hybrid materials specifically engineered for permanent 3D-printed restorations. Manufacturers of these materials claim high dimensional stability, flexural strength, and a modulus suitable for definitive restorations (e.g., Bego; VarseoSmile Triniq technical product data sheet). However, there is a lack of clinical data to support these claims.
Other: Three dimensionally (3D) printed resin composite restorations fabricated using additive manufacturi
Additive Manufacturing, the intervention group will feature restorations fabricated via 3D printing. This technology is more time and cost-efficient, more accurate, and could provide a considerable alternative to the currently applied CNC milling, reduced material waste, and the ability to create complex geometries with high precision. Recent studies have shown that 3D-printed restorations can achieve promising results in terms of marginal and internal fit, which are critical for clinical longevity. This has spurred the development of novel, ceramic-filled hybrid materials specifically engineered for permanent 3D-printed restorations. Manufacturers of these materials claim high dimensional stability, flexural strength, and a modulus suitable for definitive restorations (e.g., Bego; VarseoSmile Triniq technical product data sheet). However, there is a lack of clinical data to support these claims.
Other: Milled resin composite restorations fabricated using subtractive manufacturing from CAD/CAM blocks.
Subtractive Manufacturing, the control group will utilize restorations fabricated via subtractive manufacturing, specifically by milling from industrially fabricated blocks of nanohybrid composite. This method is the established gold standard for producing CAD/CAM resin composite restorations. It is known for creating restorations with excellent mechanical properties, high density, and predictable clinical performance due to the optimized, industrial-grade polymerization of the blocks. These materials, which include polymer-infiltrated ceramic networks (PICNs) and resin nanoceramics, were developed to combine the favorable properties of both ceramics and resin composites, offering a biomimetic alternative to traditional glass-ceramics.
Other: Three dimensionally (3D) printed resin composite restorations fabricated using additive manufacturing
Additive Manufacturing, the intervention group will feature restorations fabricated via 3D printing. This technology is more time and cost-efficient, more accurate, and could provide a considerable alternative to the currently applied CNC milling, reduced material waste, and the ability to create complex geometries with high precision. Recent studies have shown that 3D-printed restorations can achieve promising results in terms of marginal and internal fit, which are critical for clinical longevity. This has spurred the development of novel, ceramic-filled hybrid materials specifically engineered for permanent 3D-printed restorations. Manufacturers of these materials claim high dimensional stability, flexural strength, and a modulus suitable for definitive restorations (e.g., Bego; VarseoSmile Triniq technical product data sheet). However, there is a lack of clinical data to support these claims.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Clinical performance
Time Frame: T0=baseline (1st week), T1=6 months, T2=12 months and T3=18 months follow-up.

World Dental Federation (FDI) criteria set to evaluate direct and indirect dental restorations: Hickel et al. (2023).

Aesthetic properties of Endocrown restorations (Domain A):

  1. Surface Luster
  2. Staining (surface, margin)
  3. color match and translucency

  4. Esthetic anatomical form

    Functional performance of Endocrown restorations (Domain F):

  5. Fracture of material and retention
  6. Marginal adaptation

  7. Approximal anatomical form

    Biological Properties of Endocrown restorations (Domain B):

  8. Recurrence of caries (CAR)
  9. Tooth integrity (enamel cracks, tooth fracture)
  10. Periodontal response
T0=baseline (1st week), T1=6 months, T2=12 months and T3=18 months follow-up.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Restoration Fit
Time Frame: T0=baseline (1st week), T1=6 months, T2=12 months and T3=18 months follow-up.
  1. Marginal Adaptation
  2. Internal Adaptation Triple-scan digital superimposition (Geomagic Control X 2022 software)
T0=baseline (1st week), T1=6 months, T2=12 months and T3=18 months follow-up.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

October 6 University

Investigators

  • Study Director: Mohsen Hussein Abielhassan, • Professor, Conservative Dent, October 6 University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

  • 7. Cal, I. K., Ozturk, F., Aydin, N., & Karaoglanoglu, S. (2024). 3D Printed Restorations Produced From Permanent Resin: Case Report. International Dental Journal, 74, S298. 10.1016/j.identj.2024.07.282 8. Doumit, M., Beuer, F., Böse, M. W. H., Unkovskiy, A., Hey, J., & Prause, E. (2025). Wear behavior of 3D printed, minimally invasive restorations: Clinical data after 24 months in function. The Journal of Prosthetic Dentistry, 134(3), 662-669. 10.1016/j.prosdent.2025.03.014 9. Güntekin, N., & Tunçdemir, A. R. (2024). Comparison of volumetric loss and surface roughness of composite dental restorations obtained by additive and subtractive manufacturing methods. Heliyon, 10(4). 10.1016/j.heliyon.2024.e26269 10. Hickel, R., Mesinger, S., Opdam, N., Loomans, B., Frankenberger, R., Cadenaro, M., . & Kühnisch, J. (2023). Revised FDI criteria for evaluating direct and indirect dental restorations-recommendations for its clinical use, interpretation, and reporting. Clinical oral investigations, 27(6), 2573-2592. 10.1007/s00784-022- 04814-1 11. Kader, İ. T., Özer, S., & Arıcan, B. (2025). The effect of different fit-indicating materials and preparation designs on the marginal and internal fit of 3D-printed permanent endocrowns. Meandros Medical And Dental Journal, 26(1), 108-116. 10.69601/meandrosmdj.1596545 12. Koyuturk, A. E., Ozmen, B., Tokay, U., Tuloglu, N., Sari, M. E., & Sonmez, T. T. (2013). Two-year follow-up of indirect posterior composite restorations of permanent teeth with excessive material loss in pediatric patients: a clinical study. Journal of Adhesive Dentistry, 15(6). 10.3290/j.jad.a30897 13. Mahran, G. A., El-Banna, A., & El-Korashy, D. I. (2025). Evaluation of a 3Dprinted nanohybrid resin composite versus a milled resin composite for flexural strength, wear and color stability. BMC Oral Health, 25(1), 572. https://doi.org/10.1186/s12903-025-05861-2
  • 1.Abad-Coronel, C., Durán Urdiales, D., Benalcázar Arias, M. V., Córdova, A. K., Medina, M. S., & Bravo Torres, W. (2025). Flexural strength, fatigue behavior, and microhardness of three-dimensional (3D)-printed resin material for indirect restorations: A systematic review. Materials, 18(3), 556. https://doi.org/10.3390/ma18030556 2. Abou-steit, S. S., Salem, M. A., Omar, S., & Mahmoud, N. (2024). Clinical evaluation of the biomimetic aspect in the restoration of endodontically treated teeth (Randomized clinical trial). Egyptian Dental Journal, 70(3), 2683-2693. 10.21608/EDJ.2024.291267.3045 3. Abuabboud, O., Marinescu, A. G., Paven, M., Kovacs, I. M., Nica, L. M., Faur, A. B., & Jivănescu, A. (2025). Influence of Cement Thickness, Dentine Thickness, and Intracoronal Depth on the Fracture Resistance of 3D-Printed Endocrowns: A Pilot In Vitro Study. Dentistry Journal, 13(6), 263. 10.3390/dj13060263 23 4. Albrecht, M., Schmidt, F., Menzel, F., Yassine, J., Beuer, F., & Unkovskiy, A. (2024). Comparative Analysis of Modern 3D-Printed Hybrid Resin-Ceramic Materials for Indirect Restorations: An In Vitro Study. Polymers,16(22), 3161. https://doi.org/10.3390/polym16223161 5. Alghauli, M. A., & Alqutaibi, A. Y. (2024). 3D-printed intracoronal restorations, occlusal and laminate veneers: Clinical relevance, properties, and behavior compared to milled restorations; a systematic review and meta-analysis. Journal of Esthetic and Restorative Dentistry, 36(8), 1153-1170. 10.1111/jerd.13228 6. Arslan, S., Karagön, M., Balkaya, H., & Köse, B. (2024). A randomized clinical study evaluating the 30-month clinical performance of class II indirect restorations in endodontically treated teeth using ceramic, hybrid, and composite computer-aided design/computer-aided production blocks. Journal of Conservative Dentistry and Endodontics, 27(1), 68-75. 10.4103/JCDE.JCDE_213_23

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

November 1, 2026

Primary Completion (Estimated)

November 1, 2028

Study Completion (Estimated)

December 1, 2028

Study Registration Dates

First Submitted

July 12, 2026

First Submitted That Met QC Criteria

July 12, 2026

First Posted (Actual)

July 16, 2026

Study Record Updates

Last Update Posted (Actual)

July 16, 2026

Last Update Submitted That Met QC Criteria

July 12, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • RECO6U/14-2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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