Tooth mobility changes subsequent to root fractures: a longitudinal clinical study of 44 permanent teeth

The purpose of this study was to analyze tooth mobility changes in root-fractured permanent teeth and relate this to type of interfragment healing (hard tissue healing (HT), interfragment healing with periodontal ligament (PDL) and nonhealing with interposition of granulation tissue (GT) because of pulp necrosis in the coronal fragment. Furthermore, the effect of age, location of the fracture on the root, and observation period on mobility values was analyzed. Mobility values were measured for 44 of 95 previous reported root-fractured permanent incisors. Mobility changes were measured with a Mühlemanns periodontometer and noninjured incisors served as controls. The mobility values represented the labial-lingual excursion of the root measured in μm when the tooth received a frontal and a palatal impact of 100 g force. In 18 cases of hard tissue healing (HT), a slightly increased mobility was seen after 3 months and 1 year, and a normalization of mobility value was usually found after 5 and 10 years. In 17 cases of PDL healing, generally a higher mobility was found in comparison with root fractures healing with hard tissue, and a consistent decrease in mobility value was found in the course of the 10 year observation period. A tendency for reduced mobility over time was found, a relation that could possibly be explained by the known general decrease in tooth mobility with increasing age. Finally, nine cases of nonhealing with initial interposition of granulation tissue (GT) because of pulp necrosis in the coronal fragment resulted in increasing mobility values possibly related to a lateral breakdown of the PDL in relation to the fracture line. In control teeth, a lowering of mobility was found over the course of a 10-year observation period. In conclusion, mobility changes appeared to reflect the radiographic healing stages and known age effects upon tooth mobility.