Effects of the secondhand smoking exposure in the early stages of the bone development

Abstract ObjectiveThe objective of this study was to evaluate the effects of the secondhand smoking in the trabecular bone micro-architecture of the mandible of rats, offsprings of passive smoking matrices. Materials and MethodsFifty-five rats, Rattus norvegicus albinus, offsprings of passive smoking and non-passive smoking matrices, were divided into three groups: continuous smoking offsprings (CSO), interrupted smoking offsprings (ISO) and non-smoking offsprings (NSO/control). After the 21st, 42nd, 63rd and 128th days, the mandibles were analyzed by micro-computer tomography(micro-CT). Images of inter-radicular alveolar bone of the mandibular first molars underwent three-dimensional reconstruction and were analyzed. The bone volume fraction (BV/TV, bone volume/total volume), the trabecular thickness (Tb.Th), the trabecular spacing (Tb.Sp), the trabecular number (Tb.N) and the structure model index (SMI) were analyzed. ResultsThe BV/TV analysis revealed increase of the average values in the CSO group, at 21st and 42nd days (p=0,0124), tending to decrease related to the mean from the 42nd day. The animals of ISO group did not show significant difference in BV/TV, about the control group (p=0,9751). The results of Tb.Th were different and significant during all the experimental period among the three groups: CSO and control (p<0,0001), ISO and control (p=0,0030) and CSO / ISO (p=0,0020). About Tb.Sp, the differences were not significant among the three groups. About Tb.N, the difference was significant into each group, with increasing values (p<0.0001). The SMI showed significant difference between the CSOs and control, CSO and ISO, both with (p<0,0001). The difference between control and ISO group was not significant (p=0,1253). ConclusionThe passive inhalation of cigarette smoke by the offsprings of smoking matrices had a harmful effect in the micro-archicteture of the trabecular bone of the rats’ mandible in developing. About the ISO groups, the recovery of the micro-archicteture occurred partially.