This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Who gave the concept of well adapted crown? 
Select and explain. 
A. Winkler, B. Spedding, C. Webber, D. Wilkinson
B: Spedding
Answer: B: Spedding 
Explanation: - The smallest crown that completely covers the preparation should be chosen.
- Spedding has advocated adhering to two important principles that will help consistently to produce well-adapted stainless steel crowns.
a. The operator must establish the correct occluso-gingival crown length; and
b. The crown margins should be shaped circumferentially to follow the natural contours of the tooth’s marginal gingivae.