Periodontal response to orthodontic tooth movement in diabetes-induced rats with or without periodontal disease

The onset of adenosine monophosphate-activated protein kinase activity on orthodontic tooth movement in rats with type 2 diabetes

Adenosine monophosphate-activated protein kinase (AMPK) plays pivotal roles in metabolic diseases including type 2 diabetes. However, the specific role of AMPK for orthodontic tooth movement in type 2 diabetes is unclear. In this study, a diabetic rat model was established through dietary manipulation and streptozocin injection. Examinations were conducted to select qualified type 2 diabetic rats. Then, an orthodontic device was applied to these rats for 0, 3, 7, or 14 days. The distance of orthodontic tooth movement and parameters of alveolar bone were analyzed by micro-computed tomography. Periodontal osteoclastic activity, inflammatory status, and AMPK activity were measured via histological analyses. Next, we repeated the establishment of diabetic rats to investigate whether change of AMPK activity was associated with orthodontic tooth movement under type 2 diabetes. The results showed that diabetic rats exhibited an exacerbated alveolar bone resorption, overactive inflammation, and decreased periodontal AMPK activity during orthodontic tooth movement. Injection of the AMPK agonist alleviated type 2 diabetes-induced periodontal inflammation and alveolar bone resorption, thus normalizing distance of orthodontic tooth movement. Our study indicates that type 2 diabetes decreases periodontal AMPK activity, leading to excessive inflammation elevating osteoclast formation and alveolar bone resorption, which could be reversed by AMPK activation.

Remodeling of the periodontal ligament and alveolar bone during axial tooth movement in mice with type 1 diabetes

OBJECTIVES

To observe the elongation of the axial tooth movement in the unopposed rodent molar model with type 1 diabetes mellitus and explore the pathological changes of periodontal ligament and alveolar bone, and their correlation with tooth axial movement.

METHODS

The 80 C57BL/6J mice were randomly divided into the streptozotocin(STZ)-injected group (n = 50) and the control group (n = 30). Mice in the streptozotocin(STZ)-injected group were injected intraperitoneal with streptozotocin (STZ), and mice in the control group were given intraperitoneal injection of equal doses of sodium citrate buffer. Thirty mice were randomly selected from the successful models as the T1DM group. The right maxillary molar teeth of mice were extracted under anesthesia, and allowed mandibular molars to super-erupt. Mice were sacrificed at 0, 3, 6,9, and 12 days. Tooth elongation and bone mineral density (BMD) were evaluated by micro-CT analysis(0,and 12 days mice). Conventional HE staining, Masson staining and TRAP staining were used to observe the changes in periodontal tissue(0, 3, 6, 9, and 12 days mice). The expression differences of SPARC, FGF9, BMP4, NOGGIN, and type I collagen were analyzed by RT-qPCR.

RESULTS

After 12 days of tooth extraction, our data showed significant super-eruption of mandibular mouse molars of the two groups. The amount of molar super-eruption in the T1DM group was 0.055mm( ± 0.014mm), and in the control group was 0.157( ± 0.017mm). The elongation of the T1DM mice was less than that of the control mice(P<0.001). It was observed that the osteoclasts and BMD increased gradually in both groups over time. Compared with the control group, the collagen arrangement was more disordered, the number of osteoclasts was higher (P<0.05), and the increase of bone mineral density was lower(2.180 ± 0.007g/cm³ vs. 2.204 ± 0.006g/cm³, P<0.001) in the T1DM group. The relative expression of SPARC, FGF9, BMP4, and type I collagen in the two groups increased with the extension of tooth extraction time while NOGGIN decreased. The relative expression of all of SPARC, FGF9, BMP4, and type I collagen in the T1DM group were significantly lower, and the expression of NOGGIN was higher than that in the control group (P<0.05).

CONCLUSION

The axial tooth movement was inhibited in type 1 diabetic mice. The result may be associated with the changes of periodontal ligament osteoclastogenic effects and alveolar bone remodeling regulated by the extracellular matrix and osteogenesis-related factors.

Morphologic Evaluation of Dentoalveolar Structures after Corticotomy-Assisted Orthodontic Treatment in Romanian Adult Patients

Background and Objectives: Corticotomy-facilitated orthodontics is an approach that can be useful in treating complex orthodontic cases and that could enhance the rate of tooth movement. The aim of this study was to evaluate the changes that occurred in the buccal cortical bone and at the root level after an orthodontic treatment when corticotomy was used, in Romanian patients. Materials and Methods: After dividing the subjects into two groups (maxillary and mandibular corticotomy), based on CBCT, measurements were made of the thickness of the cortical buccal bone at the cervical, median and apical level, and of the root length at T0 (before corticotomy) and T1 (6 months after surgery). Several tests were used for statistical analysis of the data. Results: In the maxillary arch, the bone thickness measured after corticotomy in males was 0.64 mm at the cervical level, 0.53 mm at the medial level and 0.30 mm in the apical area. In females, the values were 0.46 mm (cervical), 0.37 mm (medial) and 0.36 mm (apical). In the lower arch, the values obtained for these three regions were 0.37 mm, 0.30 mm and 0.37 mm for males and 0.58 mm, 0.32 mm and 0.43 mm for female subjects. All values were statistically significant. The root length for the lower teeth at T0 was 11.98 ± 2.24 mm at T0 and 11.97 ± 2.24 mm at T1. For the upper teeth, the root length at T0 was 13.83 ± 2.28 mm and 13.81 ± 2.28 mm. Conclusions: Comparing the measurements, it was observed that the biggest changes in the cortical bone were at the cervical level. In the maxillary arch, the most significant modifications were registered at the canines and the level of the first premolars, and in the lower arch at the incisors level. The measured root resorption of the teeth was considered to be statistically insignificant.

Pulpal outcomes in orthodontic tooth movement in diabetes mellitus

Diabetes mellitus impairs angiogenesis and tissue reorganization during orthodontic tooth movement (OTM). Thus, this study evaluated pulpal outcomes in orthodontic tooth movement through metabolic changes in diabetes. Male Wistar rats were used, and the in vivo study design consisted of four groups (n = 10/group): C-non-diabetic animals not subjected to orthodontic tooth movement; D-diabetic animals not subjected to orthodontic tooth movement; OTM-non-diabetic animals subjected to orthodontic tooth movement; and D + OTM-diabetic animals subjected to orthodontic tooth movement. In addition, the pulps of the distovestibular root (DV) and mesiovestibular root (MV) were assessed by histomorphometric analyses and immunoexpression of the RANKL/OPG system. Pulpal analysis of the MV root showed an increase in blood vessels in diabetic animals. Inflammatory infiltrate and fibroblastic cells were elevated in diabetic animals with tooth movement in the DV and MV roots. In the DV and MV roots, diabetic rats with OTM showed a reduction in birefringent collagen fibers. The immunostaining for RANKL was higher in the pulp tissue of OTM in diabetic and non-diabetic animals. It was concluded that the pulp tissue has less adaptive and repair capacity during OTM in diabetes. Orthodontic strength can alter the inflammatory processes in the pulp.

Bovine lactoferrin inhibits alveolar bone destruction in an orthodontic rat model with periodontitis

OBJECTIVE

We aimed to evaluate the effect of bovine lactoferrin (bLF) on alveolar bone destruction and remodelling under orthodontic force (OF) in periodontitis-affected rats.

MATERIAL AND METHODS

After establishing the periodontitis-affected rat model with lipopolysaccharides (LPS), the left maxillary first molars were moved orthodontically under a force of 0.2N. Based on saline or bLF gavage, 54 Sprague-Dawley (SD) rats were randomized into 5 groups: A (blank), P1 (LPS+OF+bLF), P2 (LPS+OF+saline), C1 (OF+bLF), and C2 (OF+saline). Animals were evaluated using micro-computed tomography (micro-CT) followed by haematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining, and the LF level was determined using ELISA in the gingival crevicular fluid (GCF) of the experimental teeth. Immunohistochemistry helped to detect expression changes in RANKL, OPG and COX-2.

RESULTS

Micro-CT results indicated that compared with group P2, trabecular number (Tb.N) and trabecular thickness (Tb.Th) in group P1 were higher and bone surface/bone volume (BS/BV) was lower on day 14, while trabecular separation (Tb.Sp) decreased significantly on Day 5 and Day 14 after bLF gavage (P<0.05). This was supported by changes in H&E and TRAP staining. bLF down-regulated RANKL level at both timepoints and up-regulated OPG level on Day 14 in periodontitis rats (P<0.05). The significant changes mentioned above were not observed between group C1 and C2 (P>0.05). No significant change in COX-2 levels were observed in any group (P>0.05). The lactoferrin level in GCF increased significantly after bLF gavage (P<0.05).

CONCLUSION

Bovine lactoferrin inhibited LPS-induced bone destruction, but the bone healing effect was independent of orthodontic aseptic inflammatory bone remodelling.

Influence of thyroxine supplementation on orthodontically induced tooth movement and/or inflammatory root resorption: A systematic review

The role of thyroxine administration on orthodontically induced tooth movement and/or inflammatory root resorption remains unclear. The aim was to assess the influence of thyroxine administration on orthodontically induced tooth movement and/or inflammatory root resorption. The study protocol was registered in PROSPERO (CRD42020164151). An electronic search of indexed databases was conducted without time or language restrictions up to and including May 2020. The following eligibility criteria were imposed: (a) original prospective controlled clinical studies and/or experimental studies on animal models; (b) subjects undergoing orthodontic therapy with fixed appliances; (c) presence of a control group [orthodontic tooth movement without thyroxine administration]; and (d) intervention: orthodontic tooth movement with thyroxine administration. Review articles, commentaries, letters to the editor, case reports/series, studies with no control group, cross-sectional studies, retrospective studies and studies where thyroxine was administered along with other interventions such as calcitonin and prostaglandins were excluded. Quality of available evidence and risk of bias within studies were assessed. Any disagreements were resolved via consensus discussions. Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 8 animal studies were included. Four studies reported that thyroxine administration increases the rate of orthodontic tooth movement; 3 studies did not show a significant difference. Three studies showed that thyroxine administration decreases orthodontically induced inflammatory root resorption; 2 studies found no significant difference. The risk of bias among studies was high. In conclusion, the influence of thyroxine administration on orthodontic tooth movement and/or orthodontically induced inflammatory root resorption in animal models remains unclear.

Effect of two corticotomy protocols on periodontal tissue and orthodontic movement

Objective

To compare two corticotomy surgical protocols in rats to verify whether they alter conventional orthodontic movement.

Methodology

Sixty Wistar rats were divided into three groups – orthodontic movement (CG), orthodontic movement and corticotomy (G1) and orthodontic movement with corticotomy and decortication (G2) – and euthanized after 7 and 14 days. Tooth movement (mm), bone volume fraction and bone volume ratio to total volume (BV/TV), and bone mineral density (BMD) were evaluated by micro-CT. The total amount of bone was measured in square millimeters and expressed as the percentage of bone area in the histomorphometry. The number of positive TRAP cells and RANK/RANKL/OPG interaction were also investigated.

Results

Day 14 showed a statistically significant difference in orthodontic tooth movement in CG compared with G1 (7.52 mm; p=0.009) and G2 (7.36 mm; p=0.016). A micro-CT analysis revealed a difference between CG, G1 and G2 regarding BV/TV, with G1 and G2 presenting a lower BV/TV ratio at 14 days (0.77 and 0.73 respectively); we found no statistically significant differences regarding BMD. There was a difference in the total amount of bone in the CG group between 7 and 14 days. At 14 days, CG presented a significantly higher bone percentage than G1 and G2. Regarding TRAP, G2 had more positive cells at 7 and 14 days compared with CG and G1.

Conclusion

Corticotomy accelerates orthodontic movement. Decortication does not improve corticotomy efficiency.

Microtomographic analysis of the effect of sodium alendronate on orthodontic movement in rats

OBJECTIVE

To evaluate the effect of sodium alendronate on orthodontic tooth movement in rats using microtomographic analysis.

SETTINGS AND SAMPLE POPULATION

Thirty male Wistar rats (Rattus norvegicus) were divided into three groups of 10 rats and administered saline (control), 1 mg/kg sodium alendronate or 6 mg/kg sodium alendronate, respectively.

MATERIALS AND METHODS

The drug was administered once per week for 5 weeks by gavage. Orthodontic movement was induced during the last 2 weeks of medication administration by inserting a closed nickel-titanium spring between the left upper first molar and central incisors. The opposite side served as the control. Tooth movement and bone trabeculation in the furcation region were evaluated by microtomographic analysis in the first (moved) and third (static) molars. The data were subjected to one-way or two-way ANOVA and Bonferroni test (P < .05).

RESULTS

The microtomographic images of the group that received 6 mg/kg sodium alendronate demonstrated significantly less tooth movement (P = .048), less space between the trabeculae (P = .031) and greater number of bone trabeculae (P = .033) compared to the other groups. There were no statistically significant differences in bone volume and mean trabecular thickness between the three groups. The static teeth did not show the same alterations (P > .05).

CONCLUSION

Sodium alendronate treatment reduced tooth movement in rats.

Evidence on the effect of uncontrolled diabetes mellitus on orthodontic tooth movement. A systematic review with meta-analyses in pre-clinical in- vivo research

OBJECTIVE

The aim of this review was to appraise the existing evidence from pre- clinical research on tooth movement under the condition of hyperglycemic status.

DESIGN

Electronic search was conducted in 8 databases in October 13, 2019, to identify related pre- clinical animal research with keywords being: "diabetes mellitus", "tooth movement". Eligibility criteria involved controlled animal studies, entailing tooth movement under diabetic status compared to control healthy animals. Primary endpoints involved all outcomes related to tooth movement. Risk of bias (RoB) was assessed through the SYstematic Review Centre for Laboratory animal Experimentation tool (SYRCLE), while quantitative synthesis was planned after exploration of heterogeneity, through random effects meta-analyses of standardized mean differences (SMDs) with 95 % confidence intervals (CIs).

RESULTS

Of an initial number of 290 articles retrieved, 14 papers were eligible for inclusion in the qualitative synthesis, while 9 contributed to meta-analyses. Heterogeneity of experimental conditions in individual studies was evident. The risk of bias overall was rated as unclear to high. There was no evidence of a significant effect of diabetes mellitus when tooth movement was assessed macroscopically (6 studies, SMD: 1.47; 95 % CI: -0.60, 3.53; p = 0.16). However, attenuation of osteoblastic differentiation within the periodontal ligament was detected, as there was evidence of reduction of osteopontin expression (2 studies, SMD: -3.77; 95 %CI: -4.89, -2.66; p < 0.001).

CONCLUSIONS

There is currently a paucity of solid evidence with regard to alterations of the equilibrium of the implicated structures under the status of diabetes mellitus, when mechanical stimulation of teeth is attempted, with sporadic inferences from animal research. Significant research insights in how the disease impacts on orthodontic tooth movement are invaluable, at present.

Diabetes mellitus and periodontitis: Inflammatory response in orthodontic tooth movement

OBJECTIVES

This study evaluated, in experimental model, the inflammatory alterations in gingival tissue and alveolar bone during the orthodontic tooth movement (OTM) in diabetes mellitus (D) and periodontitis (P).

SETTING AND SAMPLE POPULATION

Forty male Wistar rats, 90 days old and weighing 300 g.

MATERIALS AND METHODS

The sample was divided into four groups (n = 10). OTM: orthodontic movement (10 days, 0.4 N force); P + OTM: periodontitis (ligature-induced periodontitis, 3-0 silk suture thread) and orthodontic movement; D + OTM: diabetes (Alloxan-induced diabetes, 150 mg/kg) and orthodontic movement; and D + P + OTM: diabetes, periodontitis and orthodontic movement. Tooth displacement was measured; fibroblast, inflammatory cells, osteoclast and blood vessels were quantified by histomorphometric analysis. Inflammatory markers, interleukin-6 (IL-6) and tumour necrosis factor (TNF-α) were quantified by ELISA (Enzyme-Linked Immunosorbent Assay) in gingival tissue. The fibroblastic growth factor (bFGF), transforming growth factor (TGF-β1) and the vascular endothelial growth factor (VEGF) were measured via Western blotting in the alveolar bone. The results were analysed by ANOVA and Tukey's test at a 5% significance level.

RESULTS

The quantification of inflammatory cells and the expression of IL-6, TNF-α, TGF-β1 and bFGF were increased in diabetes and periodontitis. However, the number of fibroblasts and blood vessels and the percentage of birefringent collagen fibres were higher in healthy animals. There was greater tooth displacement in the OTM group.

CONCLUSION

Diabetes Mellitus modifies the inflammatory response. The increased expression of inflammatory markers IL-6, TNF-α and TGF-β1 in diabetic animals impairs neovasculogenesis and tissue reorganization during orthodontic tooth movement, which may be aggravated by periodontitis.

Macroscopic and radiographic aspects of orthodontic movement associated with corticotomy: animal study

INTRODUCTION

To quantify the rate of tooth movement in two corticotomy protocols in an experimental model in rats through macroscopic and radiographic analysis.

METHODS

The animals were divided into three groups: orthodontic movement (CO), orthodontic movement plus corticotomy surgery (G2), and orthodontic movement and corticotomy surgery with decorticalization (G3).The euthanasia occurred in 7 and 14 days. The data were statistically analyzed (p < 0.05).

RESULTS

The CO presented lower distance between the mesial surface of the first molar and the distal surface of the third molar when compared to the G2 (6.96 ± 0.24, p = 0.009) and G3 (6.93 ± 0.18, p = 0.016) in the macroscopic analysis. In the 7 days, there was no statistically significant radiographic difference between the three groups: CO(0.94 ± 0.21 mm²), G2(1.05 ± 0,27 mm²), and G3(1.08 ± 0.27 mm²).There was a statistically significant difference between CO (0.87 ± 0.12 mm²), G2 (1.00 ± 0.12 mm²), and G3 (1.11 ± 0.14 mm²) at 14 days. There was a statistically significant linear difference between the groups in all periods.

CONCLUSION

Tooth movement and the region of interest were influenced by corticotomy, regardless of the surgical technique in the 14 days.

Effect of orthodontic force associated with cigarette smoke inhalation in healthy and diseased periodontium. A histometric and immunohistochemistry analysis in rats

BACKGROUND

The aim of the present study is to evaluate the effect of orthodontic forces in healthy or diseased periodontium of rats submitted/not submitted to cigarette smoke inhalation.

MATERIAL AND METHODS

Fifty-six male Wistar rats were allocated into two groups of conditions: smoking and non-smoking. Each group was divided into the following subgroups: control (C), orthodontic tooth movement (OTM), ligature-induced periodontitis (P) and P+OTM (POTM), with n = 14 each. Periodontitis was induced in the lower first molar by cotton ligature, and a 4 mm closed stainless steel spring was used for orthodontic movement. Animals were exposed to the smoke of 10 cigarettes for 8 minutes, 3 times a day for 60 days before P induction and OTM. Evaluation parameters were macroscopic analysis of dental movement, bone loss and bone density. In addition, the receptor activator of nuclear factor-kappaB (RANK) immunostaining and RANK ligand/osteoprotegerin ratio in the furcation region were assessed.

RESULTS

There was no statistically significant difference between groups, ie, smoking and non-smoking conditions (P = .338). Bone loss intragroup analysis between the P and POTM groups was not significant in smoking (P = 1) and non-smoking (P = .5) conditions; both were different from OTM and C in each condition. Regarding bone density, POTM and P were significant to C (P < .05). The POTM group was significant to the P and C (P = .001) regarding dental movement. The RANK ligand/osteoprotegerin ratio in the non-smoking condition was higher in P and POTM compared to C and OTM and to P and POTM in the smoking condition. RANK immunostaining was significant in the smoking condition for the P and POTM groups (P < .05).

CONCLUSION

Within the limitations of the present study, it was concluded that cigarette smoke inhalation had no influence on the evaluated groups, even with the presence of low levels of nicotine, carbon monoxide and tar. The POTM groups did not present greater bone loss compared to P groups, thus periodontal disease is essential for bone loss.