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': 'Radiographic finding of tooth shows radiolucency reaching the middle 1/3rd of dentin. Based on radiographic finding, this tooth will be categorised as _____ according to latest ICCMS guidelines. \nSelect and explain. \nA. RA2, B. RA3, C. RC5, D. RB4', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The ICCMSTM classifies tooth surfaces radiographically as follows: (modified from Agustdottir et al ; Ekstrand et al (22]).\n0 = No radiolucency.\nRA: Initial stages\n1 = radiolucency in the outer ½ of the enamel\xa0\n2 = radiolucency in the inner ½ of the enamel ± EDJ (enamel-dentin junction) (this stage is recommended for restorative care in the US, if the radiolucency touches the EDJ)\n3 = radiolucency limited to the outer 1/3 of dentin (in some countries, especially the US, this stage is classified as moderate).\nRB: Moderate stages\n4 = radiolucency reaching the middle 1/3 of dentin.\nRC: Extensive stages\n5 = radiolucency reaching the inner 1/3 of dentin, clinically cavitated\n6 = radiolucency into the pulp, clinically cavitated.\nICCMSTM Caries Risk Likelihood Matrix', 'role': 'assistant'}]