Missing IncisorsNCT04693949
Effect of Nano-structured Alumina Coating on the Bond Strength of Zirconia Resin-bonded Fixed Dental Prostheses
A study testing NAC and APA in people with Missing Incisors and Zirconia Surface Pretreatment, run by University of Ljubljana, Faculty of Medicine at 1 site in Slovenia.
Trial summary
The purpose of this study is to evaluate the clinical outcome of resin-bonded fixed dental prostheses (RBFDPs) pretreated with nanostructured alumina coating (NAC). The study adopts a prospective, randomized, controlled, double-blind design contrasting the use of NAC to air-borne particle abrasion (APA) (control) as a… Read more about this study
- Who is it for?
- Any ageHealthy volunteers can take part
- Conditions the study is for
- Missing Incisors, Zirconia Surface Pretreatment, Children
- What is being tested?
- NAC and APA
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 80 participants
- Where
- 1 siteSlovenia
- Study dates
- 3 Jan 2018to 1 Jan 2030
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- 1. Patients with missing central or lateral incisor
Who cannot join
- inadequate edentulous space for the pontic
- signs of bruxism
- abutment tooth with active periodontal or periapical disease
- inadequate enamel bonding surface of the abutment tooth
- inadequate interocclusal space for a retainer wing and a proximal connector
- pontic guidance
- physical or psychological disease likely to interfere with normal conduct of the study
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Slovenia1 site, 1 recruiting
- Recruiting
Medical Faculty - University of Ljubljana Ljubljana
Ljubljana, 1000
Tine Malgaj, DMD, +386 31 410140, tine.malgaj@mf.uni-lj.si
About this study
The purpose of this study is to evaluate the clinical outcome of resin-bonded fixed dental prostheses (RBFDPs) pretreated with nanostructured alumina coating (NAC).
The study adopts a prospective, randomized, controlled, double-blind design contrasting the use of NAC to air-borne particle abrasion (APA) (control) as a surface pretreatment method of zirconia RBFDPs used for replacing missing central or lateral incisors. The primary outcome evaluated is the retention/survival of the zirconia RBFDPs pretreated with APA and NAC.
Read the detailed description
Zirconia resin-bonded fixed dental prostheses (RBFDPs) have been regarded as a promising minimally invasive alternative for the replacement of missing central and lateral incisors, offering several advantages to orthodontic space closure or tooth replacement with implant-supported restorations. Debonding of the zirconia RBFDPs represents the main technical complication since clinically established airborne particle abrasion (APA) of an inert zirconia surface does not always provide sufficient resin-bond strength. Further, APA can also impair the mechanical properties of zirconia restoration affecting its long-term success. Nano-structured alumina coating (NAC) presents an alternative non-invasive zirconia surface pretreatment. The aim of this randomized controlled clinical trial is to study the effect of NAC coated bonding surface of zirconia RBFDPs affecting its debonding and clinical survival rate.
The study adopts a prospective, randomized, controlled, double-blind design contrasting the use of NAC to air-borne particle abrasion (APA) as a surface pretreatment method of zirconia RBFDPs. Healthy patients in need of a missing central or lateral incisor replacement are screened and rated to be eligible by two calibrated dentists. RBFDPs are randomly allocated into two groups and inserted by the same operator. The first group, where the bonding surface is pretreated with APA serves a control group. In the second group the restorations are pretreated with NAC. The participants and the operator are blinded to the group assignment in a double-blinded trial design. The primary outcome evaluated is the retention/survival of the RBFDP. Non-parametric tests and Kaplan-Meyer analysis will be used to determine differences between both study groups.
- Conditions
- Missing Incisors, Zirconia Surface Pretreatment, Children, Adults, Debonding
- Being tested
- NAC, APA
- Keywords
- Airborne particle abrasion, Nanostructured alumina coating, Resin-bonded fixed dental prostheses
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
NACOther
Pretreatment of zirconia RBFDP with nanostructured alumina coating after milling of RBFDP's framework
APAOther
Air-borne particle abrasion of zirconia RBFDPs prior to bonding
| Study group | Role | What they receive |
|---|---|---|
| APA | Active comparator | Air-borne particle abrasion of zirconia RBFDPs prior to bonding Receives: Other: APA |
| NAC | Experimental | Pretreatment of zirconia RBFDP with nanostructured alumina coating after milling of RBFDP's framework Receives: Other: NAC |
What is being measured
The primary outcome is the main question the study is designed to answer.
Survival rate of zirconia RBFDPs
Survival rate is defined by debonding or restoration loss
Measured: From baseline through study completion, an average of 1 year
Secondary outcomes (6)
Porcelain chipping
Porcelain chipping
Measured: From baseline through study completion, an average of 1 year
Zirconia framework fracture
Zirconia framework fracture
Measured: From baseline through study completion, an average of 1 year
Gingivitis
Visual and tactile inspection of gingiva
Measured: From baseline through study completion, an average of 1 year
Parodontitis
Gingival sulcus depth measurement
Measured: From baseline through study completion, an average of 1 year
Marginal leakage
Discoloration of a restoration margin
Measured: From baseline through study completion, an average of 1 year
Secondary caries
Caries between the tooth and restoration margin
Measured: From baseline through study completion, an average of 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Jan 2021
- Study start3 Jan 2018
- Primary completion1 Jan 2027 (estimated)
- Study completion1 Jan 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Missing IncisorsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This is a single-centre, prospective, randomized, controlled, double-blind clinical trial.
- Masking
- Double blind
- Who is masked
- Participant, Care provider
- Enrolment
- 80 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Ljubljana, Faculty of Medicine
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04693949
- Sponsor's protocol ID
- Adhesion of RBFDPs
- Status last verified
- Oct 2025
- First submitted
- 29 Dec 2020
- Last updated
- 23 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 23 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Nano-structured Alumina Coating on the Bond Strength of Zirconia Resin-bonded Fixed Dental Prostheses
- ClinicalTrials.gov ID
- NCT04693949
- Acronym / sponsor ID
- Adhesion of RBFDPs
- Conditions
- Missing Incisors, Zirconia Surface Pretreatment, Children, Adults, Debonding
- Keywords
- Airborne particle abrasion, Nanostructured alumina coating, Resin-bonded fixed dental prostheses
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 80 participants (estimated)
- Lead sponsor
- University of Ljubljana, Faculty of MedicineUniversity, hospital or other
- Study start
- 3 Jan 2018 (actual)
- Primary completion
- 1 Jan 2027 (estimated)
- Study completion
- 1 Jan 2030 (estimated)
- First posted
- 5 Jan 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to evaluate the clinical outcome of resin-bonded fixed dental prostheses (RBFDPs) pretreated with nanostructured alumina coating (NAC).
The study adopts a prospective, randomized, controlled, double-blind design contrasting the use of NAC to air-borne particle abrasion (APA) (control) as a surface pretreatment method of zirconia RBFDPs used for replacing missing central or lateral incisors. The primary outcome evaluated is the retention/survival of the zirconia RBFDPs pretreated with APA and NAC.
Detailed description
Zirconia resin-bonded fixed dental prostheses (RBFDPs) have been regarded as a promising minimally invasive alternative for the replacement of missing central and lateral incisors, offering several advantages to orthodontic space closure or tooth replacement with implant-supported restorations. Debonding of the zirconia RBFDPs represents the main technical complication since clinically established airborne particle abrasion (APA) of an inert zirconia surface does not always provide sufficient resin-bond strength. Further, APA can also impair the mechanical properties of zirconia restoration affecting its long-term success. Nano-structured alumina coating (NAC) presents an alternative non-invasive zirconia surface pretreatment. The aim of this randomized controlled clinical trial is to study the effect of NAC coated bonding surface of zirconia RBFDPs affecting its debonding and clinical survival rate.
The study adopts a prospective, randomized, controlled, double-blind design contrasting the use of NAC to air-borne particle abrasion (APA) as a surface pretreatment method of zirconia RBFDPs. Healthy patients in need of a missing central or lateral incisor replacement are screened and rated to be eligible by two calibrated dentists. RBFDPs are randomly allocated into two groups and inserted by the same operator. The first group, where the bonding surface is pretreated with APA serves a control group. In the second group the restorations are pretreated with NAC. The participants and the operator are blinded to the group assignment in a double-blinded trial design. The primary outcome evaluated is the retention/survival of the RBFDP. Non-parametric tests and Kaplan-Meyer analysis will be used to determine differences between both study groups.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, care provider)
- Number of arms
- 2
- Model description
- This is a single-centre, prospective, randomized, controlled, double-blind clinical trial.
| Arm | Type | Receives |
|---|---|---|
| APA | Active comparator | Other: APAAir-borne particle abrasion of zirconia RBFDPs prior to bonding |
| NAC | Experimental | Other: NACPretreatment of zirconia RBFDP with nanostructured alumina coating after milling of RBFDP's framework |
Who may qualify
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (1 listed)
- 1. Patients with missing central or lateral incisor
Key exclusion criteria (7 listed)
- inadequate edentulous space for the pontic
- signs of bruxism
- abutment tooth with active periodontal or periapical disease
- inadequate enamel bonding surface of the abutment tooth
- inadequate interocclusal space for a retainer wing and a proximal connector
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| NACPretreatment of zirconia RBFDP with nanostructured alumina coating after milling of RBFDP's framework | Other | NAC |
| APAAir-borne particle abrasion of zirconia RBFDPs prior to bonding | Other | APA |
Primary outcome
Survival rate of zirconia RBFDPs
Time frame: From baseline through study completion, an average of 1 year
Survival rate is defined by debonding or restoration loss
6 secondary outcomes
Porcelain chipping
Time frame: From baseline through study completion, an average of 1 year
Zirconia framework fracture
Time frame: From baseline through study completion, an average of 1 year
Gingivitis
Time frame: From baseline through study completion, an average of 1 year
Parodontitis
Time frame: From baseline through study completion, an average of 1 year
Marginal leakage
Time frame: From baseline through study completion, an average of 1 year
Secondary caries
Time frame: From baseline through study completion, an average of 1 year
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing NAC and APA in people with Missing Incisors and Zirconia Surface Pretreatment, run by University of Ljubljana, Faculty of Medicine at 1 site in Slovenia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 23 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Slovenia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Tine Malgaj, DMD (+386 31 410140, tine.malgaj@mf.uni-lj.si), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Survival rate of zirconia RBFDPs (time frame: From baseline through study completion, an average of 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jun 2026.