Long-Term Periodontal Tissue Changes Associated With Metal-Ceramic Crowns: An 8-Year Split-Mouth Study

March 30, 2026 updated by: Elīna Bluma, Riga Stradins University

Long-Term Assessment of Periodontal Tissue Health Following Metal-Ceramic Crown Use: Complication Rates and Prevention Strategies

The goal of this clinical trial is to to evaluate the periodontal condition around metal-ceramic crown. The main question to be answered is: whether the metal-ceramic crown is the cause of gum changes? The study offers to involve patients who receive single metal-ceramic crown and have kept the same tooth intact on the other side of the mouth.

The condition of the gums around the crown will be compared with the corresponding natural teeth on the oposite side of the mouth. Clinical parameters such as plaque accumulation, bleeding on probing, periodontal pocket depth and gingival recession will be evaluated. All procedures are part of routine dental examination.

Participants:

will be invited for gingival examination 3 months after receiving the metal-ceramic crown, will receive a routine hygiene instruction, will be invited for gingival re-examination after 8 years.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The aim of this study is to evaluate the effects of metal-ceramic (MC) crowns on periodontal tissues over 8-year period, using a split-mouth design by comparing treated teeth with contralateral teeth within the same oral cavity.

The preparation and manufacturing of the MC crown is performed following a standardized clinical and laboratory protocol. Tooth preparation follow routine requirements, including creation of a chamfer preparation line and placing the crown margin equigingivally.

An initial follow-up examination is performed three months after the placement of the MC crown. The examination is performed by a prosthodontist under a dental operating light, using a flat-surfaced intra-oral mirror and a dental/periodontal probe. Both the restored tooth (test) and the contralateral natural tooth (control) are examined.

Attention is paid to examin the gingival tissue determining the degree of gum inflammation, the amount of plaque around the crown. The depth of the gum pockets are measured and the amount of recession is determined.

Inspection records are made twice, 3 months and 8 years after the placement of MC crowns.

All data are confidential and are used only within the framework of the study. Participation is voluntary. Patient have the option to withdraw their participation in the study at any time. This will not affect further treatment at institution.

If patients have any questions about the study they are invited to contact: call or visit the Clinic of Prosthetic Dentistry/ RSU Institute of Stomatology.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
32

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Patients with a tooth-based metal-ceramic crown intended.
  • Patients with a good general state of health, i.e. do not suffer from chronic uncontrolled general illnesses (diabetes, cardiovascular diseases, oncological diseases).
  • Patients who have corresponding natural tooth on opposite side without a fixed dental prosthesis (crown, bridge).

Exclusion Criteria:

  • Pregnancy.
  • With local inflammation and diseases of the oral mucosa.
  • With removable prostheses in both jaws.
  • Smokers (>20 cigarettes per day).
  • With an extraction wound next to an exposed tooth.
  • With neurological or psychiatric problems that affect hygiene.

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Participant with 1 metal-ceramic crown (test)and nonrestored natural tooth in oral cavity (control)
A patient (who visits the department's clinic) with a clinical necessity and his own choice to make a metal-ceramic crown (test group) for incisors, canines, premolars, and molars, but has a non-restored corresponding natural tooth on the opposite side of the mouth (control group).
Device: Metal-ceramic crown

The preparation and manufacturing of the MC crown was performed following a standardized clinical and laboratory protocol. Final impression was taken with a one-step technique in a standard tray. All crowns were manufactured in the same dental laboratory. The metal frameworks were fabricated in cobalt-chromium using the lost-wax technique and then veneered with ceramic using a layering technique. All restorations were cemented with zinc phosphate cement.

The examination was performed under a dental operating light, using a flat-surfaced intra-oral mirror and a dental/periodontal probe. Both the restored tooth (test) and the contralateral natural tooth (control) were examined. Records were made for the gingival condition using the Silness & Loe gingival index. Gingival pocket depth measured in millimeters, gingival recession was measured as distance in millimeters (mm) from the cementoenamel junction to the gingival margin.

Other Names:
  • Gingival index
  • Gingival pocket depth
  • Gingival recession

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Clinical parameters
Time Frame: 8 years

Records were made for the gingival condition of test and control using the Silness & Loe gingival index, scoring four sites (M, D, B, L) for each tooth. The mean value for each tooth was then calculated.

Gingival index (GI) according to Silness & Loe. Scores Description 0-Normal gingiva,

  1. Mild inflammation: slight change in color, slight edema, no bleeding on probing,
  2. Moderate inflammation: redness, edema, and glazing, or bleeding on probing,
  3. Severe inflammation: marked redness and edema, tendency toward spontaneous bleeding.

Gingival pocket depth measured in millimeters was assessed at 6 surfaces per tooth by inserting a dental probe between teeth and gumline and recording the distance from the gingival margin to the base of the pocket, with the deepest measurement considered. Gingival recession was measured as distance in millimeters (mm) from the cementoenamel junction to the gingival margin, with the greatest value recorded.
8 years

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Riga Stradins University

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 1, 2015

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2016

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 23, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 23, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 30, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 3, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 30, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • E-9 (2)

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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