RESUMO
Aim: To evaluate the spatial distribution of MIH opacities in first permanent molars (FPM). Materials and methods: an analysis of intraoral photographs of FPM with demarcated MIH opacities was conducted. The presence of opacity was computed in a digital matrix, discriminating the anatomical regions of the FPM surfaces. The frequencies of distribution of the opacities were descriptively analyzed through 227 FPM digital images of 89 children built in GIMP and Python and by Spearman correlation (= 0,05). Results: the occlusal surface was the most affected one (94% to 100%). In the upper FPM, the palatine surface was the second most affected one (84%-91%). In the lower FPM, the vestibular surface was the second most affected one (85%-80%). A similar pattern of opacity distribution was observed in the contralateral teeth. On smooth surfaces, opacities were more frequent in the regions closer to the occlusal surface than to the cervical one. Conclusion: MIH opacities were mostly present on occlusal, vestibular, and lingual/palatine surfaces, respectively. There is a possibility that the occurrences are in accordance with the chronology of dental formation.