Methods: Initial reference points were randomly marked on four molar teeth with similar dimensions. Digital images were taken in a stainless-steel model with 16 points whose three dimension coordinates were determined as control. Further digital images were taken under 150N loading at the beginning, after MOD cavity preparation, after access cavity preparation, after restoring the pulp chamber with a resin cement (SuperBond C&B, Parkell) and after the following restoration techniques:1) Direct composite restoration (Clearfil SE Bond and AP-X composite-resin, Kuraray, Japan); 2) A flowable resin (Panavia F, Kuraray, Japan) lined before direct composite resin restoration and a polyethylene fiber (Ribbond, Ribbond Inc. Seattle WA) was embedded into the bed of flowable resin before direct composite resin restoration; 3) Fiber was inserted from buccal to lingual direction on the occlusal surface of the finished composite resin restoration; 4) Fiber was inserted circumferentially before composite resin restoration. The images were analyzed using a three dimensional photogrammetric technique (TOPCON Image Surveying Station PI-3000). The final coordinates were compared with initial coordinates and the movement of cusps were recorded as micron.
Results: Inserting the fiber under the composite resin increased the inter-cuspal distance (47 micron). When the fiber was inserted from buccal to lingual direction, inter-cuspal distance was reduced 1 micron (16micron) when compared to direct composite restoration (17 micron). Using the fiber circumferentially showed a cuspal distance change of 20 micron.
Conclusion: Digital photogrammetric technique used in this pilot study is an appropriate method for the measurement of cusp movement. Fiber use did not give an advantage in terms of cuspal deflection. Further research is needed for the accuracy of these results.