Analysis of the dentin-pulp complex in teeth submitted to orthodontic movement in rats

Abstract

In order to microscopically analyze the pulpal effects of orthodontic movement, 49 maxillary first molars of rats were submitted to orthodontic appliance composed of a closed coil spring anchored to the maxillary incisors, placed for the achievement of mesial movement. Material and Methods: Ten animals were used as the control group and were not submitted to orthodontic force; the other animals were divided into groups according to the study period of tooth movement, namely 1, 2, 3, 4, 5, 6 and 7 days. The investigation of pulp and periodontal changes included hyalinization, fibrosis, reactive dentin and vascular congestion. Statistical evaluation was performed between control and experimental groups and between periods of observation using non-parametric chi-square, Kruskal-Wallis and Dunn tests. Results: There was no statistically significant difference concerning pulpal changes between control and experimental groups nor between periods of observation. The control group, at 3 and 5 days, revealed greater hyalinization of the periodontal ligament (p<0.05), whereas root resorption was significantly greater at 5 and 7 days (p<0.05). Conclusion: No morphological change from the effect of induced tooth movement could be found in the dentin-pulp complex. In addition, no inflammatory or pulp degeneration, detectable in optical microscopy, was found in experimental groups.

Pulp analysis of teeth submitted to different types of forces: a histological study in rats

“…These authors found higher root resorptions associated with CF, corroborating data that duration plays an important role in the biological mechanism, promoting different tissue reactions. 1 Massaro, et al 19 (2009) observed higher radicular resorption at day 7 of ITM with continuous force; however, without greater pulp damage. Further studies are needed to investigate whether radicular resorption can be associated with pulp alterations in later periods after tooth movement.…”

“…Histological images were captured using an optical light microscope (Carl Zeiss, Göttingen, Germany), coupled to a digital camera (Axio Cam MRc5, Carl Zeiss, Göttingen, Germany). The radicular pulp of five roots of the right first molar ( Figure 3 ) was evaluated following an adaptation of the method proposed by Massaro, et al 19 (2009). The following histological characteristics were evaluated: presence or absence of inflammatory infiltrate, reduced cellularity, increased fibrosis, pulp hyalinization, pulp nodules, diffuse calcification, necrosis, vascular congestion, hemorrhage, thrombosis, reactional dentin, tubules with nuclei.…”

“…While some studies showed no pulp alterations resulting from orthodontic tooth movement, 19 , 20 other studies found several events, such as invasion of macrophages, cellular proliferation, vascular alterations and disorganization of the odontoblast layer. 3 - 12 A few cases of tooth vitality loss during the orthodontic treatment were reported; however, when present, they were associated with previous traumas and/or poor control of the orthodontic force.…”

Human Dental Pulp Tissue during Orthodontic Tooth Movement: An Immunofluorescence Study

“…The literature shows conflicting results about the correlations of pulp changes incident to orthodontic force. Some reports suggested permanent damage to pulpal tissue from orthodontic force as tissue calcification and vascular alteration with vascular stasis and pulp necrosis [ 12 ] but others supported no significant long-lasting effects of dental pulp [ 13 , 14 ]. The clinical impact of these studies was to determine whether any alterations in pulpal tissues could affect the long-term vitality of the teeth.…”

There is no pulp necrosis or calcific metamorphosis of pulp induced by orthodontic treatment: biological basis

“…In 2005, Consolaro 8 described the tooth movement in 39 rats, with periods of 1 to 7 days, using the model initially developed by Heller and Nanda, 9 recognized worldwide as the most employed in studies on this subject. The study analyzed pulp tissues, 8 , 10 compared to those of teeth of other 9 animals not submitted to tooth movement. It was concluded that induced tooth movement did not promote morphological alterations in the dental pulp detectable by light microscopy, either degenerative or inflammatory.…”