Soft Tissue Response and IL-1β Levels Around CAD/CAM-Milled vs 3D-Printed PMMA Healing Abutments

Clinical and Biochemical Assessment of the Soft Tissue Response to Printed Versus Milled Polymethyl Methacrylate Custom Healing Abutments

This study looked at how the gums and tissues around dental implants heal when using two different types of temporary healing caps made of PMMA (a common dental material). These healing caps help shape the gums before placing the final crown.

There are two ways to make these caps:

1. CAD/CAM-milled (carved from a solid block)

2. 3D-printed (built layer by layer using resin) The goal was to find out which type leads to healthier gum tissue. What the Researchers Did

   • 22 dental implants in 22 patients were included.
   • Each implant received one healing cap-either milled or 3D-printed.
   • Patients were checked after 1 week, 2 weeks, and 4 weeks.

   • The team measured:

     • Gum inflammation
     • Bleeding around the implant
     • Plaque buildup
     • Pocket depth around the implant
     • Levels of an inflammatory marker called Interleukin-1β (IL-1β) in the gum fluid (higher levels mean more inflammation).
     • Surface smoothness and material quality of each type of healing cap. What the Study Found
   • Gum inflammation and bleeding were higher with 3D-printed caps, especially at week 4.
   • IL-1β levels were much higher around 3D-printed caps-showing more inflammation.
   • Both types had some increase in plaque and probing depth over time, but there was no major difference between groups.
   • The milled caps had smoother surfaces and better material quality, which may have helped reduce irritation and inflammation.
   • 3D-printed caps were rougher and had lower polymerization (more leftover monomers), which may trigger soft-tissue irritation.

What This Means

• CAD/CAM-milled PMMA healing caps appear to be safer and healthier for gum healing around dental implants.
• They may help reduce early inflammation, support better tissue health, and more predictably shape the gums during healing.

Why This Matters for Patients

• Using a smoother, better-finished healing cap may lower the risk of early gum inflammation.
• Healthier soft tissue around an implant leads to better long-term implant stability.
• This information can help dentists choose the best healing cap for optimal healing.

Study Timeframe

• The follow-up was 4 weeks, so results focus on early healing. More research is needed to know long-term differences.

Study Overview

• Status: Active, not recruiting
• Conditions: Peri-implant Soft Tissue Healing
• Intervention / Treatment: Device: CAD/CAM-Milled PMMA Healing Abutment; Device: 3D-Printed PMMA Healing Abutment

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Alexandria, Egypt, 21526
    • Faculty of Dentistry, Alexandria University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adults aged 25 to 65 years
• Presence of one osseointegrated dental implant placed at least 8 weeks prior to second-stage surgery
• Adequate zone of attached keratinized gingiva (> 1 mm) around the implant site
• Good general health and able to provide informed consent
• Willing and able to attend all follow-up visits (1, 2, and 4 weeks)

Exclusion Criteria:

• Smoking more than 20 cigarettes per day
• Presence of systemic diseases that may affect healing (e.g., autoimmune conditions, uncontrolled diabetes, immunosuppressive disorders)
• Oral inflammatory conditions or active oral infections
• History of head and neck radiation therapy or chemotherapy
• Use of corticosteroids or antibiotics within the last 3 months
• Parafunctional habits (e.g., bruxism)
• Pregnant or breastfeeding individuals
• Implants with insufficient attached gingiva or poor oral hygiene maintenance

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: CAD/CAM-Milled PMMA Healing Abutment; Participants receive a customized PMMA healing abutment manufactured using CAD/CAM milling from a pre-polymerized PMMA block. The abutment is attached to the implant at second-stage surgery to guide soft-tissue healing.	Device: CAD/CAM-Milled PMMA Healing Abutment; A customized healing abutment fabricated by subtractive CAD/CAM milling from a pre-polymerized PMMA block. Milling produces a highly polished, low-porosity surface with a high degree of polymerization. The abutment is connected to a Ti-base and placed at second-stage surgery to shape peri-implant soft tissues.
Experimental: 3D-Printed PMMA Healing Abutment; Participants receive a customized PMMA healing abutment manufactured using 3D printing from a light-cured PMMA resin, followed by post-processing and UV curing. The abutment is attached to the implant at second-stage surgery.	Device: 3D-Printed PMMA Healing Abutment; A customized healing abutment produced by additive manufacturing (3D printing) using a light-cured PMMA resin. The abutment is printed layer-by-layer, washed in isopropyl alcohol, UV-cured, finished, and polished. This manufacturing technique results in a different surface texture and polymerization level compared to milled PMMA. The abutment is attached to a Ti-base and placed at second-stage surgery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Interleukin-1β (IL-1β) Level in Peri-Implant Crevicular Fluid	Concentration of IL-1β in peri-implant crevicular fluid collected using sterile paper points. Samples are stored at -80°C and analyzed using ELISA kits. Higher IL-1β levels indicate greater inflammatory response. Mean IL-1β values are compared between CAD/CAM-milled and 3D-printed PMMA healing abutment groups at each time point.	up to 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Modified Gingival Index (MGI)	Soft-tissue inflammation around the healing abutment assessed using the Modified Gingival Index (0-3 scale) at four peri-implant sites (mesial, distal, buccal, palatal). Higher scores indicate more severe inflammation. Group differences and changes over time are evaluated.	up to 4 weeks
Plaque Index (PI)	Plaque accumulation measured at four implant surfaces using a 0-3 scale (0 = no plaque; 3 = heavy soft deposits). Mean PI values are compared between study groups and across time points.	up to 4 weeks
Bleeding on Probing (BOP)	Presence or absence of bleeding upon gentle probing around the healing abutment. BOP is recorded as a binary variable and expressed as the percentage of implants with bleeding in each group.	up to 4 weeks
Probing Pocket Depth (PPD)	Probing depth in millimeters measured at four peri-implant sites using a plastic periodontal probe. Mean pocket depths and changes over time are compared between groups.	up to 4 weeks
Surface Roughness of PMMA Healing Abutments	Surface roughness parameters (Ra, Rz, Rp, Rv) measured via profilometry for CAD/CAM-milled and 3D-printed PMMA abutments. Higher values indicate rougher surfaces. Group means are compared.	Immediately after fabrication
Degree of Conversion (%) of PMMA Material	Degree of polymerization of PMMA material measured using spectroscopic methods. Higher percentages indicate more complete polymerization and lower residual monomer content. Compared between milled and 3D-printed groups.	Immediately after fabrication

Collaborators and Investigators

• Sponsor: Ali Hassan Eid Toto

Study record dates

Study Major Dates

• Study Start (Actual): November 23, 2025
• Primary Completion (Estimated): December 23, 2025
• Study Completion (Estimated): December 23, 2025

Study Registration Dates

• First Submitted: November 23, 2025
• First Submitted That Met QC Criteria: December 3, 2025
• First Posted (Actual): December 17, 2025

Study Record Updates

• Last Update Posted (Actual): December 17, 2025
• Last Update Submitted That Met QC Criteria: December 3, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Dental implants; Biocompatibility; PMMA; Soft tissue healing; Digital dentistry; Peri-implant crevicular fluid; Peri-implant soft tissue; Peri-implant inflammation; Surface roughness; Healing abutments; CAD/CAM milled abutments; 3D-printed abutments; Interleukin-1 beta (IL-1β); Degree of conversion
• Other Study ID Numbers: AlexandriaUali

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No