Evaluation of Occlusal Adjustment Material Removal on Monolithic Zirconia Blocks: An In Vitro Study
NCT ID: NCT07280130
Last Updated: 2025-12-30
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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NOT_YET_RECRUITING
120 participants
OBSERVATIONAL
2026-02-01
2027-12-31
Brief Summary
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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
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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.
Conditions
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Keywords
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Study Design
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CASE_CONTROL
PROSPECTIVE
Study Groups
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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.
perform material removal on monolithic zirconia
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
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.
perform material removal on monolithic zirconia
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
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.
perform material removal on monolithic zirconia
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
Interventions
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perform material removal on monolithic zirconia
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
Eligibility Criteria
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Inclusion Criteria
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.
Exclusion Criteria
* 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).
20 Years
40 Years
ALL
Yes
Sponsors
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National Taiwan University Hospital
OTHER
Responsible Party
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Principal Investigators
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Yihao Lan, DDS, MSD
Role: STUDY_DIRECTOR
National Taiwan University Hospital
Central Contacts
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Other Identifiers
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202510051RINA
Identifier Type: -
Identifier Source: org_study_id