Dental OcclusionNCT07280130
Evaluation of Occlusal Adjustment Material Removal on Monolithic Zirconia Blocks: An In Vitro Study
An observational study of Dental Occlusion and Occlusal Wear of Teeth, run by National Taiwan University Hospital.
Trial summary
This study aims to improve understanding of the amount of tooth-replacement material removed during a single grinding "stroke" performed in the adjustment of a zirconia crown. Zirconia is a highly durable ceramic material commonly used for dental restorations, and accurate adjustment is essential for achieving proper… Read more about this study
- Who is it for?
- Ages 20 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Dental Occlusion, Occlusal Wear of Teeth, Fixed Dental Prosthesis
- What is being tested?
- perform material removal on monolithic zirconia
- Type of treatment
- Surgery or procedure
- How many people
- 120 participants
- Where
- No sites listed yet
- Study dates
- 1 Feb 2026to 31 Dec 2027
- Phase
- Observational
- 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 20 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: The study population consists of 120 participants from three levels of dental training and early clinical practice, recruited from a dental school and affiliated clinical institutions. The sample includes: 1. Fourth-year dental students 2. Sixth-year dental interns 3. Clinicians with 0-5 years of post-graduation experience Participants are generally healthy adults capable of performing fine motor tasks required for dental procedures. Exclusion criteria include acute hand/upper-limb injuries, neuromuscular disorders, uncorrected poor vision, and inability to follow a metronome rhythm.
Who may be able to join
- Group A: Forty fourth-year dental students who have completed preclinical courses in operative dentistry, complete denture prosthodontics, and fixed prosthodontics (Part I). They have little to no experience in adjusting zirconia.
- Group B: Forty sixth-year dental interns. Each participant will be tested twice-once before and once near the end of their clinical training. A questionnaire will also record their prosthodontic clinical experience within the past year.
- Group C: Forty licensed clinicians with 0-5 years of post-graduation experience (with practical experience in zirconia adjustment). A questionnaire will also document their clinical experience in prosthodontics.
Who cannot join
- Acute upper-limb/hand injuries or postoperative recovery within the past 3 months that may affect grip strength or fine motor control.
- Neuromuscular disorders or tremor/postural control impairments (e.g., essential tremor, peripheral neuropathy, moderate to severe carpal tunnel syndrome) that prevent stable operation.
- Uncorrected or inadequately corrected vision that does not meet the requirements for close-range tasks (e.g., inability to clearly see fine markings at a distance of 30-40 cm even with correction).
- Inability to follow the metronome rhythm (100 beats per minute).
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
This study aims to improve understanding of the amount of tooth-replacement material removed during a single grinding "stroke" performed in the adjustment of a zirconia crown. Zirconia is a highly durable ceramic material commonly used for dental restorations, and accurate adjustment is essential for achieving proper occlusion. However, existing literature does not provide quantitative data regarding material removal per stroke during chairside adjustment, resulting in reliance on individual clinical experience.
In this study, standardized zirconia specimens will be prepared and assigned to three operator groups: dental students, dental interns, and experienced clinicians. Each participant will perform a controlled number of grinding strokes on the specimens using a commonly used dental grinding stone. Specimens will be scanned before and after grinding using a three-dimensional scanner to precisely quantify material removal.
Read more
Hypothesis
The hypotheses of this study are:
Each grinding stroke results in a measurable and relatively consistent amount of zirconia material removal.
Experienced clinicians demonstrate more controlled and predictable material removal per stroke compared with students and interns.
Read the detailed description
Clinical occlusal adjustment requires precision within tens of micrometers; however, current literature lacks objective data regarding per-stroke material removal during chairside adjustment of monolithic zirconia. As a result, clinical decision-making largely depends on subjective judgment.
Objective
The objective of this study is to quantify material removal per single reciprocating grinding stroke on monolithic zirconia blocks using a silicon carbide grinding stone and to compare performance among operators with different levels of clinical experience.
Methods
Monolithic zirconia specimens (VITA YZ ST; dimensions: 8 × 2 × 15 mm) will be milled, sintered, and embedded into standardized holders. Operators will include 40 fourth-year dental students, 40 sixth-year dental interns, and 40 experienced clinicians. Each participant will perform 100 grinding strokes along an 8-mm linear path at a frequency of 100 strokes per minute, guided by a metronome.
Grinding will be performed using a silicon carbide stone (Dura-Green Stone HP 0031/PC2, SHOFU, Japan) operated at 20,000 rpm. Pre- and post-grinding scans will be obtained using a 3Shape F8 scanner. Scan datasets will be superimposed using feature-based alignment to calculate volumetric loss and thickness reduction, expressed as mm³ per stroke and µm per stroke, respectively.
Statistical Analysis
Mixed-effects models will be applied to evaluate group-by-stroke interactions. Reference intervals for material removal will be established, and results will be translated into a clinically applicable occlusal adjustment guide.
Expected Results
The study is expected to define the magnitude and variability of zirconia material removal per grinding stroke, identify differences in performance between operator experience levels, and highlight areas requiring targeted educational training.
Conclusion
This in vitro investigation will provide the first stroke-level quantitative evidence for monolithic zirconia occlusal adjustment. The findings are expected to enhance the accuracy of clinical decision-making, improve training assessment, and support evidence-based guidelines for zirconia crown adjustment.
- Being tested
- perform material removal on monolithic zirconia
- Keywords
- occlusal adjustment, Monolithic zirconia, Material removal, Silicon carbide stone, 3D scan registration
- Medical subject headings
- Bites and Stings
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
perform material removal on monolithic zirconiaProcedure or surgery
Each participant will perform 100 strokes along an 8-mm path at a rate of 100 strokes per minute, guided by a metronome on the monolithic zirconia
| Study group | Role | What they receive |
|---|---|---|
| A.fourth-year dental students | Forty fourth-year dental students who have completed preclinical courses in operative dentistry, complete denture prosthodontics, and fixed prosthodontics (Part I). They have little to no experience in adjusting zirconia. Receives: Procedure: perform material removal on monolithic zirconia | |
| B.sixth-year interns | Forty sixth-year dental interns. Each participant will be tested twice-once before and once near the end of their clinical training. A questionnaire will also record their prosthodontic clinical experience within the past year. Receives: Procedure: perform material removal on monolithic zirconia | |
| C.clinicians | Forty licensed clinicians with 0-5 years of post-graduation experience (with practical experience in zirconia adjustment). A questionnaire will also document their clinical experience in prosthodontics. Receives: Procedure: perform material removal on monolithic zirconia |
What is being measured
The primary outcome is the main question the study is designed to answer.
The amount of material removal per stroke
Amount of Zirconia Material Removed per Grinding Stroke(um/stroke)
- Mean thickness of material removed per stroke
- Median thickness of material removed per stroke
Measured: about 12 months
Secondary outcomes (2)
Change in Material Removal Rate Between Grinding Phases
Difference in mean zirconia material removal per stroke between early grinding phase (strokes 1-50) and late grinding phase (strokes 51-100)
Unit of Measure: μm/stroke (difference between phases)
Measured: approximately 12 months
Percentile Distribution of Zirconia Material Removal by Operator Experience Level
Percentile distribution (e.g., 25th, 50th, 75th percentiles) of zirconia material removal per grinding stroke within each operator experience group
Unit of Measure: percentile values
Measured: approximately 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Dec 2025
- Study start1 Feb 2026 (estimated)
- Primary completion1 Jun 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Dental OcclusionStudies of the same condition, open and under way.
- More trials run by National Taiwan University HospitalThe sponsor's other registered studies.
- 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 120 participants (estimated)
Sponsor and investigators
- Lead sponsor
- National Taiwan University Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Yihao Lan, DDS, MSD, Study director, National Taiwan University Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07280130
- Sponsor's protocol ID
- 202510051RINA
- Status last verified
- Dec 2025
- First submitted
- 1 Dec 2025
- Last updated
- 30 Dec 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: If other research teams conduct similar experiments, we may consider releasing the relevant study data in a de-identified format.
Study at a glance
From the registry record, last updated by the sponsor on 30 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of Occlusal Adjustment Material Removal on Monolithic Zirconia Blocks: An In Vitro Study
- ClinicalTrials.gov ID
- NCT07280130
- Acronym / sponsor ID
- 202510051RINA
- Keywords
- occlusal adjustment, Monolithic zirconia, Material removal, Silicon carbide stone, 3D scan registration
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 120 participants (estimated)
- Lead sponsor
- National Taiwan University HospitalUniversity, hospital or other
- Study start
- 1 Feb 2026 (estimated)
- Primary completion
- 1 Jun 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 12 Dec 2025 (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 improve understanding of the amount of tooth-replacement material removed during a single grinding "stroke" performed in the adjustment of a zirconia crown. Zirconia is a highly durable ceramic material commonly used for dental restorations, and accurate adjustment is essential for achieving proper occlusion. However, existing literature does not provide quantitative data regarding material removal per stroke during chairside adjustment, resulting in reliance on individual clinical experience.
In this study, standardized zirconia specimens will be prepared and assigned to three operator groups: dental students, dental interns, and experienced clinicians. Each participant will perform a controlled number of grinding strokes on the specimens using a commonly used dental grinding stone. Specimens will be scanned before and after grinding using a three-dimensional scanner to precisely quantify material removal.
Hypothesis
The hypotheses of this study are:
Each grinding stroke results in a measurable and relatively consistent amount of zirconia material removal.
Experienced clinicians demonstrate more controlled and predictable material removal per stroke compared with students and interns.
Detailed description
Clinical occlusal adjustment requires precision within tens of micrometers; however, current literature lacks objective data regarding per-stroke material removal during chairside adjustment of monolithic zirconia. As a result, clinical decision-making largely depends on subjective judgment.
Objective
The objective of this study is to quantify material removal per single reciprocating grinding stroke on monolithic zirconia blocks using a silicon carbide grinding stone and to compare performance among operators with different levels of clinical experience.
Methods
Monolithic zirconia specimens (VITA YZ ST; dimensions: 8 × 2 × 15 mm) will be milled, sintered, and embedded into standardized holders. Operators will include 40 fourth-year dental students, 40 sixth-year dental interns, and 40 experienced clinicians. Each participant will perform 100 grinding strokes along an 8-mm linear path at a frequency of 100 strokes per minute, guided by a metronome.
Grinding will be performed using a silicon carbide stone (Dura-Green Stone HP 0031/PC2, SHOFU, Japan) operated at 20,000 rpm. Pre- and post-grinding scans will be obtained using a 3Shape F8 scanner. Scan datasets will be superimposed using feature-based alignment to calculate volumetric loss and thickness reduction, expressed as mm³ per stroke and µm per stroke, respectively.
Statistical Analysis
Mixed-effects models will be applied to evaluate group-by-stroke interactions. Reference intervals for material removal will be established, and results will be translated into a clinically applicable occlusal adjustment guide.
Expected Results
The study is expected to define the magnitude and variability of zirconia material removal per grinding stroke, identify differences in performance between operator experience levels, and highlight areas requiring targeted educational training.
Conclusion
This in vitro investigation will provide the first stroke-level quantitative evidence for monolithic zirconia occlusal adjustment. The findings are expected to enhance the accuracy of clinical decision-making, improve training assessment, and support evidence-based guidelines for zirconia crown adjustment.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| A.fourth-year dental students | – | Procedure: perform material removal on monolithic zirconiaForty fourth-year dental students who have completed preclinical courses in operative dentistry, complete denture prosthodontics, and fixed prosthodontics (Part I). They have little to no experience in adjusting zirconia. |
| B.sixth-year interns | – | Procedure: perform material removal on monolithic zirconiaForty sixth-year dental interns. Each participant will be tested twice-once before and once near the end of their clinical training. A questionnaire will also record their prosthodontic clinical experience within the past year. |
| C.clinicians | – | Procedure: perform material removal on monolithic zirconiaForty licensed clinicians with 0-5 years of post-graduation experience (with practical experience in zirconia adjustment). A questionnaire will also document their clinical experience in prosthodontics. |
Who may qualify
- Ages
- 20 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- The study population consists of 120 participants from three levels of dental training and early clinical practice, recruited from a dental school and affiliated clinical institutions. The sample includes: 1. Fourth-year dental students 2. Sixth-year dental interns 3. Clinicians with 0-5 years of post-graduation experience Participants are generally healthy adults capable of performing fine motor tasks required for dental procedures. Exclusion criteria include acute hand/upper-limb injuries, neuromuscular disorders, uncorrected poor vision, and inability to follow a metronome rhythm.
Key inclusion criteria (3 listed)
- Group A: Forty fourth-year dental students who have completed preclinical courses in operative dentistry, complete denture prosthodontics, and fixed prosthodontics (Part I). They have little to no experience in adjusting zirconia.
- Group B: Forty sixth-year dental interns. Each participant will be tested twice-once before and once near the end of their clinical training. A questionnaire will also record their prosthodontic clinical experience within the past year.
- Group C: Forty licensed clinicians with 0-5 years of post-graduation experience (with practical experience in zirconia adjustment). A questionnaire will also document their clinical experience in prosthodontics.
Key exclusion criteria (4 listed)
- Acute upper-limb/hand injuries or postoperative recovery within the past 3 months that may affect grip strength or fine motor control.
- Neuromuscular disorders or tremor/postural control impairments (e.g., essential tremor, peripheral neuropathy, moderate to severe carpal tunnel syndrome) that prevent stable operation.
- Uncorrected or inadequately corrected vision that does not meet the requirements for close-range tasks (e.g., inability to clearly see fine markings at a distance of 30-40 cm even with correction).
- Inability to follow the metronome rhythm (100 beats per minute).
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 |
|---|---|---|
| perform material removal on monolithic zirconiaEach participant will perform 100 strokes along an 8-mm path at a rate of 100 strokes per minute, guided by a metronome on the monolithic zirconia | Procedure or surgery | A.fourth-year dental students, B.sixth-year interns, C.clinicians |
Primary outcome
The amount of material removal per stroke
Time frame: about 12 months
Amount of Zirconia Material Removed per Grinding Stroke(um/stroke) * Mean thickness of material removed per stroke * Median thickness of material removed per stroke
2 secondary outcomes
Change in Material Removal Rate Between Grinding Phases
Time frame: approximately 12 months
Percentile Distribution of Zirconia Material Removal by Operator Experience Level
Time frame: approximately 12 months
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 30 Dec 2025.
- Individual participant dataSharing planned: Undecided. If other research teams conduct similar experiments, we may consider releasing the relevant study data in a de-identified format.
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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.
Yihao Lan, DDS, MSD study director
National Taiwan University Hospital
Questions about this trial
What is this clinical trial studying?
An observational study of Dental Occlusion and Occlusal Wear of Teeth, run by National Taiwan University Hospital.
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 3 inclusion and 4 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: opening soon, as of the sponsor's last update on 30 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
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 Yihao Lan, DDS, MSD (0922901103, blue-mac@hotmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The amount of material removal per stroke (time frame: about 12 months). 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 30 Dec 2025.