Objective: The main purpose of this systematic review was to examine the extent to which caries may be managed by non-invasive methods. Methods: In order to find the best evidence the main electronic databases were searched for English-language papers published between 1966 and 2004. Inclusion criteria was randomised controlled trials or cohort studies of more than 12 months duration, having criteria for assessing lesions at baseline and end points, assessing posterior teeth, and lesions monitored by bitewing radiographs. The papers were grouped according primary and permanent teeth and to mode of results presentation. Results: 1)Primary teeth: More than 50% of lesions progressed but progression rates were significantly higher for control groups in some studies. Median survival times were 2 years or more except for deep dentinal lesions. 2)Permanent teeth: (a) Progression rates - In more recent studies, arrest rates ranged from 15 to 86% and were greater in treatment than control groups. Combinations of preventive agents gave higher arrest rates than single agents. (b) Progression score - Fluoride toothpaste and both fluoride and chlorhexidine varnishes were effective in retarding or reversing mean progression scores. (c) Survival analysis - Under varying conditions, median survival rates (MSR) for lesions in the outer and inner halves of enamel ranged from 23 to 76 and from 34 to 58 months respectively. MSR for early dentinal lesions was about 3 years. Conclusion: Rates of progression of lesions is higher in primary than in permanent teeth. In primary teeth, it appears that many lesions may not need restorative care prior to exfoliation. For permanent teeth, prospects are better for arresting caries and for retarding the progress of lesions. The overall slow progress rates observed allow for safe monitoring and further intensive fluoride therapy to increase arrest rates.