1. Department of Conservative DentistryNational Health Insurance Service Ilsan HospitalGoyangKyeonggi‐doSouth Korea
2. Department of Periodontics and Endodontics, School of Dental MedicineUniversity at BuffaloBuffaloNew YorkUSA
3. Department of Policy Research AffairsNational Health Insurance Service Ilsan HospitalGoyangKyeonggi‐doSouth Korea
4. Microscope Center, Department of Conservative Dentistry and Oral Science Research CenterCollege of Dentistry, Yonsei UniversitySeoulSouth Korea