This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'In which of the following situations composites should be avoided: \nSelect and explain. \nA. Fissure sealant, B. Root surface lesion, C. Preventive resin restoration, D. Posterior teeth restorations', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Composites are usually contraindicated in root surface lesions as gap formation is seen as a result of the forces of polymerization shrinkage being higher than initial bond strength.\xa0\xa0\nComposites are effectively used for pit and fissure sealants, preventive resin restorations and core build ups.', 'role': 'assistant'}]