Dental Restoration Failures
Conditions
Keywords
Onlays, Endodontically treated molars, Adhesive resin cement, USPHS criteria, Clinical performance
Brief 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.
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.
Interventions
DEVICEMonolithic zirconia partial coverage onlays
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.
DEVICELithium disilicate partial coverage onlays
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).
DEVICEzirconia-reinforced lithium disilicate partial coverage onlays
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).
Sponsors
Yousef Mahmoud Salem
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Intervention 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."
Eligibility
Sex/Gender
ALL
Age
17 Years to 60 Years
Healthy volunteers
No
Inclusion criteria
1. Patients must have good general health. 2. Patients must be 17 to 60 years old. 3. Exclusively permanent molar teeth (first or second molars) needing restoration after endodontic therapy. 4. The tooth needs adequate residual structure to support an Onlay repair, with minimum of 50% of the coronal structure maintained. 5. Absence of Active Caries: The tooth and surrounding teeth ought to be free of illnesses or other agents compromising the restoration. 6. Endodontic Status: Radiographic evidence of adequate obturation and the lack of periapical pathology justify the excellent root canal treatment the tooth underwent. 7. 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). 8. The tooth must be in functional occlusion or have a specified occlusal contact with the opposite dentition. 9. Patients must have good dental hygiene (plaque index than 20% and gingival index less than 1). 10. 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. 11. Patients must provide written informed consent to be part in the study.
Exclusion criteria
1. The tooth had past treatment with a crown or onlay. 2. Patients have any known allergies to the components utilized in the Onlay restoration-that is, composite resin, ceramic, or adhesive compounds. 3. Pregnant female participants 4. Patients have active periodontal disease 5. Teeth with vital pulp therapy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Number and Proportion of Successful Onlay Restorations in Posterior Endodontically Treated Teeth Assessed by the Modified United States Public Health Service (USPHS) Criteria | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Frequency and Distribution of Individual Modified USPHS Parameter Ratings (Failure Mode Analysis) Stratified by Onlay Material | 6 months and 1 year post-cementation | 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. |
Countries
Jordan
Contacts
PRINCIPAL_INVESTIGATORYousef Salem
Jordan University of Science and Technology
Outcome results
None listed