Effect of luxation type on pulpal blood flow measurements: a long-term follow-up of luxated permanent maxillary incisors.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental injury has been associated with significant PBF reduction. The purpose of this study was to assess whether (i) the type of luxation trauma may affect PBF measurements and (ii) whether luxation type-related measurements may show short- and long-term changes of PBF values. In 41 trauma patients, 69 maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units were recorded in four sessions, on the day of splint removal, and 12, 24 and 36 weeks after splint removal. Statistical analysis consisted of univariate analysis of variance for repeated measurements. For the LDF measurements, the main effect of the variable 'session' was not significant (P = 0.119). However, there was a significant 'session'/'luxation type' interaction (P = 0.000). Analysis of simple session-within-luxation type effects revealed intrusive luxations to be associated with a significant decrease in PBF values (P = 0.000), while subluxations (P = 0.568), lateral luxations (P = 0.980), extrusive luxations (P = 0.910), and avulsions (P = 0.996) showed no significant difference between session-related values. The PBF measurements did not change over time for the contralateral incisors (P = 0.996). The LDF may become useful in the detection of pulpal ischaemic episodes in luxated maxillary incisors after repositioning and splinting. Further studies are warranted to assess the validity of the diagnosis of post-traumatic 'ischaemic episodes' by comparing it with histological tooth pulp changes, and by determining how well it may predict course and response to treatments in clinical trials.