Effectiveness of Using Silver Diammine Fluoride Solution and Combination of Povidone Iodine and Sodium Fluoride Varnish in Preventing Dental Root Caries in Elders: a Randomized, Double-blind, Non-inferiority Trial

The study population of this proposed clinical trial is adults aged 60 years and above living in residential care homes or attending long-term care facilities in Hong Kong. Totally, 10 residential care homes or long-term care institutions served by NGO dental outreach teams in various districts with different background were selected by the PI in consultation with the NGOs. All elders living in the selected residential homes were invited to attend a free dental examination. Elders fulfilling the inclusion criteria were invited to participate in this study and informed written consent will be obtained before commencement of the study. Dental treatments other than the study interventions were provided by dentists from the NGOs which serve the residential homes.

Totally, 353 elder adults enrolled in the trial. The baseline examination was carried out in the residential home by two calibrated examiners, and so will be as follow-up examinations after 12 and 24 months. A portable dental chair, an intra-oral LED light, disposable dental mirrors and CPI probes were used in the examination.

For each tooth that was not indicated for extraction, status of its crown and its root were assessed and recorded separately. Caries diagnosis was based on visual and tactile inspection. No radiograph was taken. Plaque and food debris that obscures visual inspection of the tooth surfaces were removed. Four surfaces (mesial, distal, buccal and lingual) per tooth were examined and the status were recorded using the following codes which basically follow the criteria recommended by the International Caries Detection and Assessment System (ICDAS II) Coordinating Committee (2009).

The oral hygiene status of the subject was assessed and recorded by using the Visible Plaque Index (Ainamo & Bay, 1975). The presence or absence of visible plaque were recorded on four surfaces (mesial, distal, buccal and lingual) per tooth.

The gingival status of the subject was assessed and recorded using the Gingival Bleeding Index (Ainamo & Bay, 1975). The presence or absence of bleeding within 10 seconds after running a probe across the gingival margin was recorded on four surfaces (mesial, distal, buccal and lingual) per tooth.