EFFECTS OF GROOVE PLACEMENT ON RETENTION RESISTANCE OF MAXILLARY ANTERIOR RESIN-BONDED RETAINERS

Debonding of resin-bonded fixed partial dentures has been partly resol ved with modification of tooth preparations, Tooth preparations for re sin bonded retainers were completed on a maxillary central incisor, a lateral incisor, and a canine. Fifteen metal replicas were constructed (five of each tooth morphotype). The three tooth morphotypes were the n modified with proximal grooves prepared parallel to the long axes, a nd another 15 metal replicas were prepared. Cast metal retainers were constructed and cemented to the replicas with a resin cement. Tensile shearing dislodging loads were applied at 20 degrees to the long axes of the teeth with a testing machine, The addition of proximal grooves made statistically significant differences in resistance to debonding forces for all three tooth morphotypes (p < 0.01). An increase of 76.7 % was seen in dislodging forces for lateral incisors with proximal gro oves compared with incisors without grooves.