A comparative evaluation of the clinical performance of bulk-fill and preheated bulk-fill composite resin in class I compound restorations by using custom shield technique A randomized controlled trial.

The massive introduction of various fluoridated agents appears to have altered the morphological factor in the development of dental caries. This led to hidden carious lesions which have an intact occlusal surface and hence are occult. Nowadays for restoring such carious lesions the earlier concept of prophylactic  extension is being displaced by minimally invasive dentistry, which focuses on preserving the sound dental structure. The posterior composite resin restorations are the standard in modern dentistry, which is moving towards Biomimetic dentistry   aiming to restore the natural contour & function of the original tooth & it is also important to achieve a harmonious occlusal & cusp fossa relationship in posterior tooth cavity restoration. The direct restorations are time-consuming, technically sensitive, and may not result in correct replication of the form and occlusion. Frequently, along with occlusal surfaces, the buccal and lingual surfaces can be affected by hidden caries and be lost during caries excavation. To resolve all these problems in the class I compound lesions, Gaetano Paolone and Salvatore Scolavino and the style Italiano team introduced the custom shield technique.  This  technique utilizes putty index for recording the height and anatomy of the buccal/palatal cusp before its reduction. Restoration of natural contours using bulk-fill composite resin becomes difficult because of more viscous nature.  it does not get adapted properly to putty index. To improve the adaptation of viscous bulk-fill composite resin, preheating of bulk-fill composite resin is done. Pre-heating of bulk-fill and conventional restorative composites prior to photoactivation decreases polymerization-induced shrinkage forces without compromising the degree of conversion & improves marginal adaption.