Abstract: The relationship between cavity preparation extension and restoration longevity is examined through a systemic review of the available evidence on specific conservative, operative caries-management strategies. Evidence tables are provided for three specific techniques in the permanent dentition: 1) the proximal “tunnel ” restoration, 2) the proximal “box-only ” restoration, and 3) the preventive resin restoration. In the primary dentition, the clinical trials involving the proximal box-only restoration, most of which involved glass-ionomer materials, are reviewed. In the permanent dentition, the evidence reveals low effectiveness for “tunnel ” restorations, limited but supportive results for proximal-only restorations, and general...