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Scratch hardness of stone models--measuring conditions
Hisami Nakagawa1, Hisako Hiraguchi
1Dental Research Center, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. nakagawa@dent.nihon-u.ac.jp
Dental Materials Journal
|February 4, 2005
Summary
Scratch hardness of dental stone models increases with higher scratch load. Storage duration impacts Type 4 stone hardness, but scratch speed effects are inconsistent.
Area of Science:
- Materials Science
- Dental Materials
Background:
- Dental stone models are crucial for prosthodontic and orthodontic applications.
- Understanding material properties like scratch hardness is essential for model accuracy and longevity.
Purpose of the Study:
- To investigate the influence of scratch load, speed, and specimen storage duration on the scratch hardness of Type 4 and Type 5 dental stone.
- To determine how different impression materials (vinyl silicone rubber and alginate) affect stone model properties.
Main Methods:
- Type 4 and Type 5 stone specimens were fabricated using vinyl silicone rubber and alginate impressions, respectively.
- Specimens were stored for 24 hours or 1 week at room temperature.
- Scratch hardness was assessed by measuring scratch depths created under varying loads (1N, 2N, 3N) and speeds (50, 100 mm/min).
Main Results:
- Scratch depth significantly increased with higher applied scratch loads.
- Type 4 stone specimens exhibited reduced scratch depths after 1-week storage compared to 24-hour storage at a scratch speed of 100 mm/min.
- No consistent trend was observed regarding the effect of scratch speed on scratch depth.
Conclusions:
- Scratch load is a primary determinant of scratch hardness in dental stone models.
- Storage duration can influence the scratch resistance of specific stone types (e.g., Type 4).
- Further research may be needed to clarify the complex interactions between scratch speed and stone model properties.