Brighter smiles, stronger fillings: how heating and high-power light improve dental restorations
| ISRCTN | ISRCTN82059518 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN82059518 |
| Sponsor | University of Diyala |
| Funder | Investigator initiated and funded |
- Submission date
- 16/06/2026
- Registration date
- 17/06/2026
- Last edited
- 17/06/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Oral Health
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data
Record updated in last year
Plain English summary of protocol
Not provided at time of registration
Contact information
Dr Rabeia Khalil
Scientific, Public, Principal investigator
Scientific, Public, Principal investigator
College of Dentistry, University of Diyala
Baquba P.O. Box 78
Diyala Governorate
32001
Iraq
 ORCID ID |
0009-0001-9484-5391 |
|---|---|
| Phone | +964 07705888527 |
| d.rabea779@Uodiyala.edu.iq |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Randomized controlled trial |
| Masking | Blinded (masking used) |
| Control | Active |
| Assignment | Single |
| Purpose | Treatment |
| Participant information sheet | 49728_PIS.pdf |
| Scientific title | A combined high-power light-curing and preheating protocol for class I posterior composite restorations: a 12-month randomized controlled clinical trial |
| Study objectives | This 12-month randomized controlled clinical trial aimed to assess whether Class I posterior composite restorations subjected to preheating and high-power curing would demonstrate superior clinical performance based on USPHS criteria. |
| Ethics approval(s) |
Approved 22/11/2025, Scientific and Ethical Committee in University of Diyala, College of Medicine (College of Dentistry, University of Diyala, Baquba P.O. Box 78, Diyala Governorate, 32001, Iraq; +964 07721863978; info.med@uodiyala.edu.iq), ref: 2025RJK965 |
| Health condition(s) or problem(s) studied | Clinical performance of a specific dental restorative protocol in Class I posterior composite restorations. From a WHO perspective, the primary conditions being addressed are: 1. Dental Caries (Tooth Decay). 2. Defective Dental Restorations (Failed or failing fillings) |
| Intervention | Method of Randomization: Randomization was performed using computer-generated block randomization sequences created using Random Allocation Software (version 1.0, by Dr. Mahmoud Saghaei). The block size was fixed at four, with each block containing an equal number of participants allocated to each of the four treatment groups (1:1:1:1 ratio). Allocation Concealment: Allocation was concealed using sequentially numbered, opaque, sealed envelopes. The envelopes were prepared by an independent researcher who was not involved in the clinical procedures. Each envelope contained the group assignment for a specific cavity (tooth). The envelopes were opened by the operator immediately after cavity preparation and before adhesive application, ensuring that the allocation sequence remained concealed until the intervention was assigned. Study Design: The study employed a split-mouth design, where each patient received four Class I composite restorations in different posterior teeth. Each restoration was randomly allocated to one of four intervention groups: • G1 (Control): Conventional incremental curing (Bluephase G2, 1200 mW/cm², 20 seconds per 2 mm increment). • G2 (HP): High-power bulk curing (Flashmax P3, 4000 mW/cm², 3 seconds per 3 mm bulk). • G3 (PH): Preheated composite (57°C) with conventional curing. • G4 (PH+HP): Preheated composite (57°C) with high-power curing (Flashmax P3, 3 seconds). Randomization Sequence Generation: The randomisation sequence was generated using a computerized random number generator with a fixed block size of four. The sequence was exported to SPSS version 28.0 for verification of randomness using a runs test. Restorations were evaluated for seven parameters at 30 minutes, 24 hours, 6 months, and 12 months using the Modified United States Public Health Service (USPHS) criteria (marginal adaptation, fracture resistance, post-operative sensitivity, color match, surface texture, anatomical form, and secondary caries). Each parameter was rated Alpha (optimal), Bravo (acceptable), or Charlie (unacceptable). Statistical comparisons between groups employed Chi-square and Fisher Exact tests, while intra-group temporal changes were analyzed using the Friedman test at 1. T₀ Baseline (30 minutes), 2. T₁ 24 hours (1 day), 3. T₂ 6 months (180 days) and 4. T₃ 12 months (365 days) (Primary endpoint). |
| Intervention type | Procedure/Surgery |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) | |
| Completion date | 30/04/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Upper age limit | 50 Years |
| Sex | All |
| Target sample size at registration | 60 |
| Total final enrolment | 47 |
| Key inclusion criteria | 1. Patients aged 18–50 years 2. With at least four molars requiring Class I restorations or presenting primary occlusal caries (ICDAS codes 4 or 5) 3. Occlusal contact with the antagonist tooth 4. A minimum prepared cavity depth of 3 mm 5. Vital or endodontically treated teeth with a positive prognosis 6. Good overall health (ASA I or II) |
| Key exclusion criteria | 1. Systemic illness 2. Pregnancy 3. Breastfeeding 4. Untreated periodontal disease with mobility 5. Severe bruxism 6. Caries extending beyond the occlusal surface 7. Pulp exposure or imminent risk thereof 8. Spontaneous pain or tenderness to percussion, severe occlusal wear 9. Refusal to participate 10. Prior use of unapproved foundation materials beneath the composite |
| Date of first enrolment | 20/02/2025 |
| Date of final enrolment | 30/04/2025 |
Locations
Countries of recruitment
- Iraq
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Other files | 17/06/2026 | No | No | ||
| Participant information sheet | 17/06/2026 | No | Yes | ||
| Protocol file | version 1.0 | 22/10/2025 | 17/06/2026 | No | No |
| Statistical Analysis Plan | version 1.0 | 22/04/2026 | 17/06/2026 | No | No |
Additional files
- 49728_SAP_v1.0_22April2026.pdf
- Statistical Analysis Plan
- 49728_Informed Consent.pdf
- Other files
- 49728_PIS.pdf
- Participant information sheet
- 49728_Protocol_v1.0_22Oct2025.pdf
- Protocol file
Editorial Notes
17/06/2026: Study’s existence confirmed by the Scientific and Ethical Committee at the University of Diyala, College of Medicine, Iraq.
