Complex sentence: The condition is thought to be due to trauma during the period in which tooth is forming, with the result that the position of the calcified portion of the tooth is changed and the remainder of the tooth is formed at an angle.
Split into simpler sentences: The condition is thought to be due to trauma during the period in which tooth is forming. The result is that the position of the calcified portion of the tooth is changed and the remainder of the tooth is formed at an angle.