Influence of the Operator`s Experience, Working Time, and Working Position on the Quality of the Margin Width - In Vitro Study

At a Glance

Metadata	Details
Publication Date	2023-01-27
Journal	Medicina
Authors	Kinga Mária Jánosi, Diana Cerghizan, Zsigmond Rétyi, Alpár Kovács, Andrea Szász
Institutions	Universitatea de Medicină, Farmacie, Științe și Tehnologie „George Emil Palade” din Târgu Mureș
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Analysis: CVD Diamond for High-Precision Rotary Instruments

Executive Summary

This analysis connects the stringent material requirements for high-precision dental preparation tools, as detailed in the study on heavy chamfer finish lines, to 6CCVD’s advanced CVD diamond capabilities.

Precision Requirement: The study targeted a critical finish line width of 0.5 mm, emphasizing the need for ultra-precise, dimensionally stable rotary cutting instruments (diamond burs).
Material Degradation: The research highlighted that repeated use significantly decreases the cutting efficiency of diamond burs, necessitating single-use protocols to maintain preparation quality.
CVD Diamond Solution: 6CCVD’s Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) offer superior hardness, wear resistance, and thermal stability, making them the ideal base materials for manufacturing next-generation, high-consistency dental and micro-machining tools.
Dimensional Consistency: The study’s results showed significant variation in chamfer width (0.450 mm to 0.840 mm mean values), underscoring the need for diamond material with exceptional uniformity and edge retention to minimize operator variability.
Custom Tooling Support: 6CCVD provides custom SCD and PCD plates/wafers up to 125 mm, along with specialized polishing (Ra < 1 nm for SCD) and metalization services, enabling manufacturers to create highly durable, geometrically perfect diamond cutting edges.
Application Focus: This research validates the demand for consistent, high-performance diamond materials in critical medical and prosthodontic applications where marginal fit (target < 120 µm gap) is paramount to restoration success.

Technical Specifications

The following data points extracted from the research highlight the critical dimensional and performance requirements for the diamond cutting tools used in this study.

Parameter	Value	Unit	Context
Target Chamfer Width	0.5	mm	Desired width of the heavy chamfer finish line.
Diamond Bur Diameter	1.1	mm	Active end diameter of the round-end tapered diamond bur (016).
Diamond Bur Taper	Standard 3	°	Taper angle used for preparation.
Clinically Acceptable Marginal Gap	< 120	µm	Maximum acceptable gap for fixed restorations (0.12 mm).
Minimum Ceramic Thickness	0.5	mm	Required thickness for ceramic restorations (e.g., zirconia) to prevent fracture.
Overall Mean Chamfer Width (t1)	0.450	mm	Closest mean value achieved by a participant to the 0.5 mm target.
Overall Mean Chamfer Width (t2)	0.840	mm	Widest mean value achieved by a participant (inexperienced).
Total Preparations	160	teeth	Total sample size for the in vitro study.

Key Methodologies

The experiment relied on precise, standardized preparation techniques using specialized diamond rotary instruments.

Material Preparation: Forty left upper-second molars were prepared in vitro using Planmeca simulators.
Tool Selection: A new round-end tapered 016 diamond bur (1.1 mm active diameter, 3° taper) was used for each preparation (160 total burs), acknowledging the rapid decrease in cutting efficiency with repeated use.
Target Geometry: The goal was to achieve an equigingival heavy chamfer finish line with a 0.5 mm width, requiring the use of only half the diamond bur diameter.
Ergonomic Control: Preparations were performed by experienced (T1, T2) and inexperienced (t1, t2) operators in standardized sitting and supine patient positions, following ISO Standard 11226.
Measurement: Prepared teeth were photographed using a Canon D5300 camera with a macro lens. Digital measurements were calibrated using a ruler placed parallel to the survey table.
Data Analysis: Chamfer width was measured at eight reference points using Image-Pro Insight software. Statistical analysis (ANOVA, Tukey-Kramer) was used to determine the influence of operator experience and position.

6CCVD Solutions & Capabilities

The findings of this study—specifically the high variability in preparation width and the necessity of using a new diamond bur for every single preparation—underscore the critical need for ultra-consistent, high-wear-resistance diamond materials. 6CCVD is uniquely positioned to supply the foundational material for manufacturing superior dental and micro-machining tools.

Applicable Materials

To replicate or extend this research by developing more durable and precise rotary instruments, 6CCVD recommends the following materials:

6CCVD Material	Recommendation Context	Key Benefit for Tooling
Optical Grade Single Crystal Diamond (SCD)	Ideal for ultra-high precision micro-tools, guide pins, or cutting inserts where atomic-level edge sharpness and minimal wear are required.	Highest purity, extreme hardness, Ra < 1 nm polish capability for perfect cutting edges.
Polycrystalline Diamond (PCD)	Suitable for robust, larger-scale rotary instruments or substrates requiring high thermal stability and uniform hardness across larger areas.	Excellent wear resistance and thermal dissipation for high-speed applications. Available up to 125 mm diameter.
Boron-Doped Diamond (BDD)	Relevant for electrochemical sensing or specialized coating applications within the dental/medical field, though less common for pure cutting tools.	Electrical conductivity, chemical inertness.

Customization Potential

6CCVD’s advanced manufacturing capabilities directly address the dimensional and finishing requirements necessary for producing the highest quality diamond burs and micro-tools:

Custom Dimensions: We supply SCD and PCD plates/wafers up to 125 mm in diameter, allowing tool manufacturers to optimize material yield for small rotary instruments.
Thickness Control: SCD and PCD layers can be grown from 0.1 µm up to 500 µm, providing precise control over the diamond coating thickness on tool blanks.
Ultra-Low Roughness Polishing: We offer polishing services achieving Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This ultra-smooth finish is crucial for minimizing friction, reducing debris accumulation (as noted in the paper), and ensuring a consistently sharp cutting edge.
Metalization Services: 6CCVD offers in-house metalization (Au, Pt, Pd, Ti, W, Cu) for bonding diamond material to tool shanks or creating electrical contacts for advanced monitoring systems.

Engineering Support

The study concluded that preparation depth is conditioned by the methodology of instruction and the instructor’s work style, highlighting the variability introduced by tool inconsistency. 6CCVD’s in-house PhD team specializes in material science and can assist tool manufacturers in selecting the optimal CVD diamond grade and geometry for similar High-Precision Prosthodontic Tooling projects. We ensure the diamond material itself contributes zero variability to the final instrument performance.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Background and Objectives: Appropriate tooth preparation is mandatory to obtain a perfect marginal fit of fixed restorations. The heavy chamfer is the most commonly used finish line, especially for minimally invasive tooth preparation. The aim of the study was to compare the width of the finish line obtained during tooth preparation performed by experienced (university lecturers) and inexperienced persons (dental students) in different working times and positions. Materials and Methods: Forty left upper-second molars were prepared on the simulator by each participant, totalizing 160 prepared teeth. A new round-end tapered diamond was used to obtain the 0.5 mm width of the heavy chamfer. The prepared teeth were photographed using a Canon D5300 camera with a macro lens attached to a tripod. The measurements were made with the Image-Pro Insight software selecting the same eight reference points. From these points, perpendicular lines were drawn above the finish line to the axial walls and the distance between the chamfer’s outer edge and the axial wall’s inner edge was measured. GraphPad Instat and NCSS Dowson Edition software were used. The statistical significance was set at p < 0.05. The mean (M) and standard deviation (SD) were calculated. The used tests: one sample t-test, ANOVA test, and Tukey-Kramer Multiple Comparisons Test. Results: Statistically significant differences were obtained according to the experience of the participant, preparation time, patient’s position, and the chamfer width on the prepared tooth different surfaces. Conclusions: Daytime or weeklong tiredness and patient position do not affect the width of the heavy chamfer prepared by experienced and inexperienced persons. The experience and the operator’s working position influence the width of the prepared finish line.

Tech Support

Original Source

DOI: https://doi.org/10.3390/medicina59020244

References

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2015 - Iatrogenic damage to periodontium by restorative treatment procedures: An overview [Crossref]
2021 - Influence of manufacturing technique on marginal fit of cobalt chromium restorations: An in-vitro study [Crossref]
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