Investigation of Biofilm Formation on Temporary push-on Rings of Implant Crowns

July 21, 2025 updated by: University Hospital, Basel, Switzerland

Temporary push-on Rings of Antimicrobial Alloys for Transmucosal Implant Abutment Systems: a Randomized Clinical Study on Early and Mature Biofilm Formation

This in-vivo study investigates early (48h), mature (2 weeks) and long-term (3 months) biofilm formation and composition on temporary push-on cones (exchangeable conical rings) made of noble-alloy-based materials (Pagalinor, PA) in comparison to Titanium-6Aluminum-7Niobium alloy (TAN) presently used in the transmucosal portion of dental implant abutments.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Oral biofilm (dental plaque) consists of bacteria and their metabolic products as well as saliva components and food residues. It is recognizable as a tough and structured coating on teeth and artificial surfaces within the oral cavity. Plaque development is a physiological process that begins immediately after cleaning of the oral surface. If the biofilm is not removed by daily oral hygiene, it continues to mature while changing the structure and its microbial composition.

Implant restorations comprise the osseous implant portion predominantly manufactured from titanium alloys, the transmucosal implant portion (in most implant systems as a separate abutment), and the clinical crown, which is in most systems extraorally cemented on an abutment and screw-retained onto the implant. According to current knowledge, microbial colonization of the implant abutment surface plays a significant role in the aetiology of peri-implantitis.

This study investigates the antibacterial potential of a temporary push-on cone (conical ring) that could reduce the risk of bacterial related peri-implant diseases due to decreased biofilm susceptibility, compared to current available transmucosal materials, in the short- and long-run. The test material Pagalinor®2 (PA) is an established material in dental medicine and has proven to accumulate least biofilm in an in-vivo biofilm sampling model using removable splints. The control material consists of the current transmucosal implant abutment material Titanium-6Aluminum- 7Niobium alloy (TAN). The push-on rings are designed for repeated application along the transmucosal implant abutment portion with high precision fit and will allow biofilm sampling in the natural implant environment. Profound insight into the native homeostasis of biofilm formation will be obtained and therefore enhance the knowledge about long-term tissue response.

Study Type

Interventional

Enrollment (Estimated)

33

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 Contact Backup

Study Locations

  • Switzerland
      • Basel, Switzerland, 4058
        • Recruiting
        • UZB (University Center for Dental Medicine Basel)
        • Contact:
        • Contact:
        • Principal Investigator:
          • Nicola U. Zitzmann, Prof. Dr.
        • Principal Investigator:
          • Lucia K. Zaugg, Dr. med. dent.

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

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Informed Consent signed by the subject
  • Presence of one or more bone level titanium implant prior to insertion of the final restoration
  • No systemic illness
  • No heavy smoking (smoking <10 cigarettes/day)
  • No pregnancy
  • No active periodontitis (probing pocket depth ≤4 mm)
  • No pharmacological treatment or antibiotic therapy during or up to three months before the study

Exclusion Criteria:

  • Systemic illness (e.g. Diabetes)
  • Heavy smoking (smoking >10 cigarettes/day)
  • Known or suspected non-compliance, drug or alcohol abuse
  • Pregnancy
  • Active periodontitis (probing pocket depth >4 mm)
  • Pharmacological treatment or antibiotic therapy during or up to three months before the study

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: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Pagalinor®2 (PA) test arm
All patients will wear both the test and control ring material for a within-subject comparison. Ideally, biofilm sampling can be performed in a split mouth design (randomly allocated materials within subjects) with one patient having two implants for placing the test and the control material at the same time. In addition, patients providing one implant, will receive test and control push-on rings in a randomly assigned order, so that both materials are assessed in a consecutive manner.
Device: Rings made of PA (test)
Rings made of PA (test) 0.2mm in thickness are pushed on the conical titanium base (abutment) of implant crowns and are removed and replaced after 48h, 2 weeks and 3 months for quantification of the bacterial biofilm. Test rings are applied in a split-mouth design provided that 2 implants are present (total of 4 months study period), or one after the other when only 1 implant is present (total of 8 months study period).
Active Comparator: Titanium-6Aluminum- 7Niobium alloy (TAN) control arm
All patients will wear both the test and control ring material for a within-subject comparison. Ideally, biofilm sampling can be performed in a split mouth design (randomly allocated materials within subjects) with one patient having two implants for placing the test and the control material at the same time. In addition, patients providing one implant, will receive test and control push-on rings in a randomly assigned order, so that both materials are assessed in a consecutive manner.
Device: Rings made of TAN (control)
Rings made of TAN (control) 0.2mm in thickness are pushed on the conical titanium base (abutment) of implant crowns and are removed and replaced after 48h, 2 weeks and 3 months for quantification of the bacterial biofilm. Control rings are applied in a split-mouth design provided that 2 implants are present (total of 4 months study period), or one after the other when only 1 implant is present (total of 8 months study period).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in total bacterial load formed on the removable rings of each material
Time Frame: at 48 hours after ring placement, 2 weeks after ring placement and 3 months after ring placement
Quantification of the bacterial load formed on the removable rings of each material by quantitative real-time PCR (qPCR) using primers specific to highly conserved regions of bacterial 16S rRNA genes.
at 48 hours after ring placement, 2 weeks after ring placement and 3 months after ring placement

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in bacterial composition (taxonomic diversity) between different materials at various time points by using metagenomic sequencing analysis
Time Frame: at baseline, 2 weeks after ring placement and 10 weeks after ring placement
To assess differences in bacterial composition (taxonomic diversity) between different materials at various time points by Illumina MiSeq sequencing. The taxonomy of each 16S rRNA gene sequence will be analyzed by Ribosomal Database Project (RDP) Classifier (http://rdp.cme.msu.edu/) against the SILVA (SSU123) 16S rRNA database using a confidence threshold of 70%.
at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in probing pocket depth (PPD) in mm
Time Frame: at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in probing pocket depth (PPD) to investigate the inflammatory tissue response
at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in bleeding on probing (BoP)
Time Frame: at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Recording bleeding on probing (BoP) to investigate the inflammatory tissue response
at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in noninvasive laser doppler flowmetry
Time Frame: at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in noninvasive laser doppler flowmetry to to measure the blood flow of mucosa next to the ring
at baseline, 2 weeks after ring placement and 10 weeks after ring placement
Change in the cells of the peri-implant soft tissue
Time Frame: at 2 weeks after ring placement
To investigate the attachment of peri-implant soft tissues to implant materials, fibroblasts and junctional epithelial cells markers will be analysed using real-time quantitative PCR (RT-qPCR).
at 2 weeks after ring placement

Collaborators and Investigators

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

Sponsor

University Hospital, Basel, Switzerland

Collaborators

ITI International Team for Implantology, Switzerland

Investigators

  • Principal Investigator: Nicola U. Zitzmann, Prof. Dr., University Center for Dental Medicine Basel

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 (Actual)

January 11, 2022

Primary Completion (Estimated)

February 1, 2026

Study Completion (Estimated)

February 1, 2026

Study Registration Dates

First Submitted

November 3, 2021

First Submitted That Met QC Criteria

November 16, 2021

First Posted (Actual)

November 17, 2021

Study Record Updates

Last Update Posted (Actual)

July 25, 2025

Last Update Submitted That Met QC Criteria

July 21, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2021-D0061; ex21Zitzmann

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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