Dental Restoration FailuresNCT07753941
An In-vivo Survival Rate of Different Onlay Materials Placed Over Endodontically Treated Molar Teeth
A study testing Monolithic zirconia partial coverage onlays, Lithium disilicate partial coverage onlays and zirconia-reinforced lithium disilicate partial coverage onlays in people with Dental Restoration Failures, run by Yousef Mahmoud Salem at 1 site in Jordan.
Trial summary
This study aims to evaluate the survival rates of onlays placed over posterior endodontically treated teeth restored with zirconia, lithium disilicate and lithium disilicate reinforced with zirconia. Additionally, it seeks to identify and assess the failure modes associated with these types of restorations. Read more about this study
- Who is it for?
- Ages 17 to 60 years
- Conditions the study is for
- Dental Restoration Failures
- What is being tested?
- Monolithic zirconia partial coverage onlays, Lithium disilicate partial coverage onlays and zirconia-reinforced lithium disilicate partial coverage onlays
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 39 participants
- Where
- 1 siteJordan
- Study dates
- 1 Sep 2025to 1 Jun 2027
- 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 17 to 60 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Patients must have good general health.
- Patients must be 17 to 60 years old.
- Exclusively permanent molar teeth (first or second molars) needing restoration after endodontic therapy.
- The tooth needs adequate residual structure to support an Onlay repair, with minimum of 50% of the coronal structure maintained.
- Absence of Active Caries: The tooth and surrounding teeth ought to be free of illnesses or other agents compromising the restoration.
- Endodontic Status: Radiographic evidence of adequate obturation and the lack of periapical pathology justify the excellent root canal treatment the tooth underwent.
Show all 11Show fewer
- The tooth and surrounding tissues must show periodontal stability free of evidence of active periodontal disease (probing depth < 4 mm, lack of movement, and no bleeding following probing).
- The tooth must be in functional occlusion or have a specified occlusal contact with the opposite dentition.
- Patients must have good dental hygiene (plaque index than 20% and gingival index less than 1).
- Participants must show that they are ready to follow the study plan, which calls for maintaining oral hygiene standards and showing attendance to follow-up visits.
- Patients must provide written informed consent to be part in the study.
Who cannot join
- The tooth had past treatment with a crown or onlay.
- Patients have any known allergies to the components utilized in the Onlay restoration-that is, composite resin, ceramic, or adhesive compounds.
- Pregnant female participants
- Patients have active periodontal disease
- Teeth with vital pulp therapy
Trial locations and contacts
1 site in 1 country.
Jordan1 site
Dental Teaching Clinics at Jordan University of Science and Technology
Irbid, 22110
About this study
Official title: An In-vivo Survival Rate of Different Onlay Materials Placed Over Endodontically Treated Molar Teeth.
This study aims to evaluate the survival rates of onlays placed over posterior endodontically treated teeth restored with zirconia, lithium disilicate and lithium disilicate reinforced with zirconia. Additionally, it seeks to identify and assess the failure modes associated with these types of restorations.
Read the detailed description
A total of 39 root canal-treated molars were restored with partial coverage onlays. Teeth were divided randomly into three groups: 13 with zirconia, 13 with lithium disilicate and 13 with lithium disilicate reinforced with zirconia. Informed consent was obtained from all patients prior to their participation.
A silicon index was used for precise tooth preparation and temporary fabrication.
Preparation: Monolithic Zirconia Onlays preparation included a rounded shoulder with the finish line located supragingivally, with a minimum of 1 mm axial reduction and 1.5 to 2 mm occlusal reduction, performed with diamond burs (Komet Dental, Germany). For Lithium Disilicate or Zirconia Reinforced Onlays, teeth were prepared with a rounded shoulder finish line located above the CEJ with axial reductions of 1.5 mm, and occlusal reductions of 2 mm using diamond burs (Komet Dental, Germany) the internal line angles were rounded, and the cavosurface angles achieved to be 90°. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology.
Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany).
Isolation and Cementation: Teeth were isolated using rubber dam, bleeding was controlled.
For ceramic-based onlays, the intaglio surface was treated with 9% hydrofluoric acid, washed and dried followed by application of Ceramic Primer Plus (Clearfil™) and Panavia V5 resin cement (Kuraray Dental-Kurashiki, Okayama, Japan) respectively. Tooth Primer was applied to ensure optimal adhesion. The restorations were seated, excess cement were removed using a tack-curing method, isolation were maintained for 3 minutes or light-cure for translucent onlays.
After Isolation were removed, occlusal adjustments were made.
For zirconia onlays, the intaglio surface was treated with tribochemical silica-coating using a chairside air-abrasion device. Alumina-coated silica particles 30µm (CoJet Sand, 3M ESPE) were applied to the intaglio surface of the zirconia onlays at a pressure of 2.5 bar, with the nozzle at a 45-degree angle and 10 mm from the surface. The application time for coating was 20 seconds. Afterward, the specimens were air-dried to remove loosely adhered particles. The above procedure has been designed based on the optimized parameters set by Özcan et al. (2013) for the highest silica content and lowest surface damage. Onlays were then treated using Z-Prime Plus, BISCO followed by Ceramic Primer Plus and Panavia V5 resin cement (Kuraray Dental-Kurashiki, Okayama, Japan). Procedures were performed by the same prosthodontist and evaluated by two operators. Restorations were assessed according to modified United States Public Health Service (USPHS) criteria, focusing on: (a) marginal discoloration, (b) secondary caries, (c) marginal integrity, (d) surface texture, (e) restoration fracture, (f) occlusal wear, (g) Color match and (h) Aesthetic anatomic form. Success will be determined based on Alpha and Bravo ratings at 6 months and 1 year intervals.
- Conditions
- Dental Restoration Failures
- Being tested
- Monolithic zirconia partial coverage onlays, Lithium disilicate partial coverage onlays, zirconia-reinforced lithium disilicate partial coverage onlays
- Keywords
- Onlays, Endodontically treated molars, Adhesive resin cement, USPHS criteria, Clinical performance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Monolithic zirconia partial coverage onlaysDevice
Also called Adhesive resin cement; USPHS criteria; Clinical performance.
Endodontically treated molars restored with adhesive onlays. For the monolithic zirconia, material-specific intaglio surface treatments are applied prior to cementation: zirconia onlays receive tribochemical silica-coating with 30µm alumina-coated silica particles (CoJet Sand) at 2.5 bar for 20 seconds, followed by Z-Prime Plus and Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel.
All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes.
Lithium disilicate partial coverage onlaysDevice
Also called Adhesive resin cement; USPHS criteria; Clinical performance.
Endodontically treated molars restored with adhesive onlays. For the Lithium disilicate (IPS e.max Press), material-specific intaglio surface treatments are applied prior to cementation: Onlays receive 9% hydrofluoric acid etching, washing, drying, and application of Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel.
All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes (or light-cured for translucent onlays).
zirconia-reinforced lithium disilicate partial coverage onlaysDevice
Also called Adhesive resin cement; USPHS criteria; Clinical performance.
Endodontically treated molars restored with adhesive onlays. For the zirconia-reinforced lithium disilicate onlays (Vita Ambria), material-specific intaglio surface treatments are applied prior to cementation: Onlays receive 9% hydrofluoric acid etching, washing, drying, and application of Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel.
All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes (or light-cured for translucent onlays).
| Study group | Role | What they receive |
|---|---|---|
| Monolithic Zirconia Onlays | Experimental | 13 endodontically treated molars restored with monolithic zirconia partial-coverage onlays (Zolid Bion Multilayer). Tooth preparation: rounded shoulder finish line located supragingivally, minimum 1 mm axial reduction, 1.5-2 mm occlusal reduction.Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology.
Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). Receives: Device: Monolithic zirconia partial coverage onlays |
| Lithium Disilicate Onlays | Active comparator | 13 endodontically treated molars restored with lithium disilicate glass-ceramic onlays (IPS e.max Press). Tooth preparation: rounded shoulder finish line located above the cemento-enamel junction (CEJ), 1.5 mm axial reduction, 2 mm occlusal reduction, rounded internal line angles, 90° cavosurface angles. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology.
Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). Receives: Device: Lithium disilicate partial coverage onlays |
| Zirconia-Reinforced Lithium disilicate Onlays | Experimental | 13 endodontically treated molars restored with zirconia-reinforced lithium disilicate glass-ceramic onlays (Vita Ambria). Tooth preparation: identical to lithium disilicate group: rounded shoulder finish line above the CEJ, 1.5 mm axial reduction, 2 mm occlusal reduction, rounded internal line angles, 90° cavosurface angles. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology.
Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). Receives: Device: zirconia-reinforced lithium disilicate partial coverage onlays |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number and Proportion of Successful Onlay Restorations in Posterior Endodontically Treated Teeth Assessed by the Modified United States Public Health Service (USPHS) Criteria
Posterior endodontically treated teeth restored with zirconia, lithium disilicate, or zirconia-reinforced lithium disilicate onlays are evaluated by two independent examiners using modified USPHS criteria across 8 parameters: marginal discoloration, secondary caries, marginal integrity, surface texture, restoration fracture, occlusal wear, color match, and aesthetic anatomic form. Each parameter rated Alpha (clinically ideal), Bravo (minor complication, clinically acceptable), or Charlie (major complication requiring renewal). Failure if Charlie on any single parameter. Data will be analyzed using Kaplan-Meier survival estimation. Outcome reported as absolute count and percentage (%) of successful restorations, stratified by material group. Higher percentage indicates better outcome.
Measured: 6 months and 12 months post-cementation
Secondary outcomes (1)
Frequency and Distribution of Individual Modified USPHS Parameter Ratings (Failure Mode Analysis) Stratified by Onlay Material
To provide a granular failure-mode analysis to onlays' placed over posterior endodontically treated teeth. This analysis will be stratified by the three onlay material groups (zirconia, lithium disilicate, and zirconia-reinforced lithium disilicate) to identify the most prevalent types of minor complications (Bravo ratings) and failures (Charlie ratings, defined as major complications requiring restoration renewal) associated with each specific material. In this failure-mode analysis, Charlie (C) ratings are explicitly considered failures. Since the USPHS criteria represent an ordinal categorical scale. Data will be aggregated as count distributions and relative frequencies (%) for each rating per parameter, per material group, providing a comprehensive descriptive assessment of failure modes.
Measured: 6 months and 1 year post-cementation
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Aug 2026
- Study start1 Sep 2025
- Primary completion1 Jun 2026
- Study completion1 Jun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Dental Restoration FailuresStudies 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 was a three-arm, parallel-group, randomized controlled trial. The individual molar tooth served as the unit of randomization. The two evaluating examiners were blinded to the material assignment and were not present during cementation or occlusal adjustments; only the treating prosthodontist was unblinded to the intervention. Clinical outcomes were assessed prospectively at 6 months and 1 year using modified USPHS criteria."
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 39 participants (actual)
Sponsor and investigators
- Lead sponsor
- Yousef Mahmoud Salem
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Yousef Mahmoud Salem, Jordan University of Science and Technology
- Investigators
- Yousef Salem, Principal investigator, Jordan University of Science and Technology
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07753941
- Sponsor's protocol ID
- 154-2025
- Other IDs
- 20250217
- Status last verified
- Jul 2026
- First submitted
- 31 Jul 2026
- Last updated
- 10 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Demographic data: Participant age and gender Tooth identification: Anonymized tooth number and arch location Group allocation: Assigned material group (zirconia, lithium disilicate, or zirconia-reinforced lithium disilicate). Primary outcome: Overall USPHS success rating (Alpha, Bravo, Charlie, Delta) at 6 months and 1 year. Supporting documents to be shared: Study protocol and statistical analysis plan
Study at a glance
From the registry record, last updated by the sponsor on 10 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An In-vivo Survival Rate of Different Onlay Materials Placed Over Endodontically Treated Molar Teeth.
- ClinicalTrials.gov ID
- NCT07753941
- Acronym / sponsor ID
- 154-2025
- Conditions
- Dental Restoration Failures
- Keywords
- Onlays, Endodontically treated molars, Adhesive resin cement, USPHS criteria, Clinical performance
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 39 participants (actual)
- Lead sponsor
- Yousef Mahmoud SalemUniversity, hospital or other
- Study start
- 1 Sep 2025 (actual)
- Primary completion
- 1 Jun 2026 (actual)
- Study completion
- 1 Jun 2027 (estimated)
- First posted
- 10 Aug 2026 (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.
This study aims to evaluate the survival rates of onlays placed over posterior endodontically treated teeth restored with zirconia, lithium disilicate and lithium disilicate reinforced with zirconia. Additionally, it seeks to identify and assess the failure modes associated with these types of restorations.
Detailed description
A total of 39 root canal-treated molars were restored with partial coverage onlays. Teeth were divided randomly into three groups: 13 with zirconia, 13 with lithium disilicate and 13 with lithium disilicate reinforced with zirconia. Informed consent was obtained from all patients prior to their participation.
A silicon index was used for precise tooth preparation and temporary fabrication.
Preparation: Monolithic Zirconia Onlays preparation included a rounded shoulder with the finish line located supragingivally, with a minimum of 1 mm axial reduction and 1.5 to 2 mm occlusal reduction, performed with diamond burs (Komet Dental, Germany). For Lithium Disilicate or Zirconia Reinforced Onlays, teeth were prepared with a rounded shoulder finish line located above the CEJ with axial reductions of 1.5 mm, and occlusal reductions of 2 mm using diamond burs (Komet Dental, Germany) the internal line angles were rounded, and the cavosurface angles achieved to be 90°. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology.
Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany).
Isolation and Cementation: Teeth were isolated using rubber dam, bleeding was controlled.
For ceramic-based onlays, the intaglio surface was treated with 9% hydrofluoric acid, washed and dried followed by application of Ceramic Primer Plus (Clearfil™) and Panavia V5 resin cement (Kuraray Dental-Kurashiki, Okayama, Japan) respectively. Tooth Primer was applied to ensure optimal adhesion. The restorations were seated, excess cement were removed using a tack-curing method, isolation were maintained for 3 minutes or light-cure for translucent onlays.
After Isolation were removed, occlusal adjustments were made.
For zirconia onlays, the intaglio surface was treated with tribochemical silica-coating using a chairside air-abrasion device. Alumina-coated silica particles 30µm (CoJet Sand, 3M ESPE) were applied to the intaglio surface of the zirconia onlays at a pressure of 2.5 bar, with the nozzle at a 45-degree angle and 10 mm from the surface. The application time for coating was 20 seconds. Afterward, the specimens were air-dried to remove loosely adhered particles. The above procedure has been designed based on the optimized parameters set by Özcan et al. (2013) for the highest silica content and lowest surface damage. Onlays were then treated using Z-Prime Plus, BISCO followed by Ceramic Primer Plus and Panavia V5 resin cement (Kuraray Dental-Kurashiki, Okayama, Japan). Procedures were performed by the same prosthodontist and evaluated by two operators. Restorations were assessed according to modified United States Public Health Service (USPHS) criteria, focusing on: (a) marginal discoloration, (b) secondary caries, (c) marginal integrity, (d) surface texture, (e) restoration fracture, (f) occlusal wear, (g) Color match and (h) Aesthetic anatomic form. Success will be determined based on Alpha and Bravo ratings at 6 months and 1 year intervals.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 3
- Model description
- This was a three-arm, parallel-group, randomized controlled trial. The individual molar tooth served as the unit of randomization. The two evaluating examiners were blinded to the material assignment and were not present during cementation or occlusal adjustments; only the treating prosthodontist was unblinded to the intervention. Clinical outcomes were assessed prospectively at 6 months and 1 year using modified USPHS criteria."
| Arm | Type | Receives |
|---|---|---|
| Monolithic Zirconia Onlays | Experimental | Device: Monolithic zirconia partial coverage onlays13 endodontically treated molars restored with monolithic zirconia partial-coverage onlays (Zolid Bion Multilayer). Tooth preparation: rounded shoulder finish line located supragingivally, minimum 1 mm axial reduction, 1.5-2 mm occlusal reduction.Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology. Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). |
| Lithium Disilicate Onlays | Active comparator | Device: Lithium disilicate partial coverage onlays13 endodontically treated molars restored with lithium disilicate glass-ceramic onlays (IPS e.max Press). Tooth preparation: rounded shoulder finish line located above the cemento-enamel junction (CEJ), 1.5 mm axial reduction, 2 mm occlusal reduction, rounded internal line angles, 90° cavosurface angles. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology. Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). |
| Zirconia-Reinforced Lithium disilicate Onlays | Experimental | Device: zirconia-reinforced lithium disilicate partial coverage onlays13 endodontically treated molars restored with zirconia-reinforced lithium disilicate glass-ceramic onlays (Vita Ambria). Tooth preparation: identical to lithium disilicate group: rounded shoulder finish line above the CEJ, 1.5 mm axial reduction, 2 mm occlusal reduction, rounded internal line angles, 90° cavosurface angles. Finishing was completed with Al2O3 stones or rubber cups. Impressions were taken using digital scanning technology. Temporary fabrication: The abutment teeth were temporarily restored using Acrytemp (Zhermack, Italy) and temporarily cemented with 3MTM RelyXTM Temp NE Zinc Oxide Non-Eugenol Temporary Cement (3M, Germany). |
Who may qualify
- Ages
- 17 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (11 listed)
- Patients must have good general health.
- Patients must be 17 to 60 years old.
- Exclusively permanent molar teeth (first or second molars) needing restoration after endodontic therapy.
- The tooth needs adequate residual structure to support an Onlay repair, with minimum of 50% of the coronal structure maintained.
- Absence of Active Caries: The tooth and surrounding teeth ought to be free of illnesses or other agents compromising the restoration.
Key exclusion criteria (5 listed)
- The tooth had past treatment with a crown or onlay.
- Patients have any known allergies to the components utilized in the Onlay restoration-that is, composite resin, ceramic, or adhesive compounds.
- Pregnant female participants
- Patients have active periodontal disease
- Teeth with vital pulp therapy
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 |
|---|---|---|
| Monolithic zirconia partial coverage onlaysAlso: Adhesive resin cement; USPHS criteria; Clinical performance.Endodontically treated molars restored with adhesive onlays. For the monolithic zirconia, material-specific intaglio surface treatments are applied prior to cementation: zirconia onlays receive tribochemical silica-coating with 30µm alumina-coated silica particles (CoJet Sand) at 2.5 bar for 20 seconds, followed by Z-Prime Plus and Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel. All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes. | Device | Monolithic Zirconia Onlays |
| Lithium disilicate partial coverage onlaysAlso: Adhesive resin cement; USPHS criteria; Clinical performance.Endodontically treated molars restored with adhesive onlays. For the Lithium disilicate (IPS e.max Press), material-specific intaglio surface treatments are applied prior to cementation: Onlays receive 9% hydrofluoric acid etching, washing, drying, and application of Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel. All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes (or light-cured for translucent onlays). | Device | Lithium Disilicate Onlays |
| zirconia-reinforced lithium disilicate partial coverage onlaysAlso: Adhesive resin cement; USPHS criteria; Clinical performance.Endodontically treated molars restored with adhesive onlays. For the zirconia-reinforced lithium disilicate onlays (Vita Ambria), material-specific intaglio surface treatments are applied prior to cementation: Onlays receive 9% hydrofluoric acid etching, washing, drying, and application of Ceramic Primer Plus (Clearfil™). Teeth were isolated using rubber dam and Tooth Primer were applied for dentin/enamel. All restorations are definitively cemented with MDP-based dual-cure resin cement (Panavia V5, Kuraray Dental). Restorations are seated, tack-cured, and isolated for 3 minutes (or light-cured for translucent onlays). | Device | Zirconia-Reinforced Lithium disilicate Onlays |
Primary outcome
Number and Proportion of Successful Onlay Restorations in Posterior Endodontically Treated Teeth Assessed by the Modified United States Public Health Service (USPHS) Criteria
Time frame: 6 months and 12 months post-cementation
Posterior endodontically treated teeth restored with zirconia, lithium disilicate, or zirconia-reinforced lithium disilicate onlays are evaluated by two independent examiners using modified USPHS criteria across 8 parameters: marginal discoloration, secondary caries, marginal integrity, surface texture, restoration fracture, occlusal wear, color match, and aesthetic anatomic form. Each parameter rated Alpha (clinically ideal), Bravo (minor complication, clinically acceptable), or Charlie (major complication requiring renewal). Failure if Charlie on any single parameter. Data will be analyzed using Kaplan-Meier survival estimation. Outcome reported as absolute count and percentage (%) of successful restorations, stratified by material group. Higher percentage indicates better outcome.
1 secondary outcome
Frequency and Distribution of Individual Modified USPHS Parameter Ratings (Failure Mode Analysis) Stratified by Onlay Material
Time frame: 6 months and 1 year post-cementation
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 10 Aug 2026.
- Individual participant dataSharing planned: Yes. Demographic data: Participant age and gender Tooth identification: Anonymized tooth number and arch location Group allocation: Assigned material group (zirconia, lithium disilicate, or zirconia-reinforced lithium disilicate). Primary outcome: Overall USPHS success rating (Alpha, Bravo, Charlie, Delta) at 6 months and 1 year. Supporting documents to be shared: Study protocol and statistical analysis plan
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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. This study is not recruiting at the moment.
Yousef Salem principal investigator
Jordan University of Science and Technology
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Monolithic zirconia partial coverage onlays, Lithium disilicate partial coverage onlays and zirconia-reinforced lithium disilicate partial coverage onlays in people with Dental Restoration Failures, run by Yousef Mahmoud Salem at 1 site in Jordan.
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 11 inclusion and 5 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: under way, not looking for participants, as of the sponsor's last update on 10 Aug 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 Jordan. 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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number and Proportion of Successful Onlay Restorations in Posterior Endodontically Treated Teeth Assessed by the Modified United States Public Health Service (USPHS) Criteria (time frame: 6 months and 12 months post-cementation). 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 10 Aug 2026; AzTrials last refreshed its copy on 8 Nov 2026.