a 10-year Follow-up Study of a Randomized Clinical Trial

Study design A 10-year follow-up study of a randomized controlled clinical trial (RCT) carried out from 2001 to 2003, including assessment of patient satisfaction, denture repair/replacement and OHRQoL. Data will be gathered through telephone interviews. Since the contacts were last used a decade ago, the phone number may have been changed, but we will make every effort to find new numbers for any participant those contact information is no longer valid .

Subjects Patients who participated and completed 6-month follow-ups in the RCT (T group: 50, and S group: 54; total 104 subjects) will be contacted by telephone.

Interviews and blinding Potential subjects will be told that we are investigating conditions of their dentures 10-years after the delivery and that we will ask general questions, as well as for their ratings of satisfaction and OHRQoL regarding their dentures. After this, the subjects will be asked whether they are willing to respond to the interviews. If they agree, the interviewer will ask the questions according to a flow chart (Appendix 1a, b). The subjects will not be told to which group they had been assigned, and a blinded research assistant will carry out the interviews and data gathering. The research assistant worked with these participants during the active study 10 years before. Patients will be excluded if they cannot respond properly to the questions.

Questionnaires Data will be gathered by four questionnaires: socio-demographic (Q1: Appendix 2), denture history/oral health (Q2: Appendix 3), general and related satisfaction outcomes by answering VAS (visual analog scale) scores out of 100 (Q3: Appendix 4), and OHQOL measures (OHIP-EDENT) 12, 13 (Q4: Appendix 5).

Analysis Denture history The difference in number of people who keep and use the dentures at 10 years will be calculated in percentages. A Chi-squared test will be employed for the statistical analyses. Finally, the prevalence of problems associated with the dentures will be calculated.

Satisfaction The differences between the treatment groups in their general satisfaction ratings on 100mm VAS after the prostheses are worn for 10 years. A two-sample independent t-test will be employed. VAS items of comfort, stability, esthetics, retention, function and ease of cleaning are also included. These will be compared between the groups using t-tests.

OHRQoL OHIP-EDENT consists of 19 statements and responses varying from 0 to 4 on a Likert scale. The possible range between 0 and 76 will be derived individually and compared between the two groups. A two-sample independent t-test will be employed.

Inclusion criteria

• Who can be contact with telephone call and accept the interview

Exclusion criteria

• The line is closed, no response, who have deceased.
• Refused to answer