Correlation between body mass index and orthodontic treatment outcome

Obesity affects the proteome profile of periodontal ligament submitted to mechanical forces induced by orthodontic tooth movement in rats

The prevalence of obesity has increased significantly worldwide. Therefore, this study aimed to evaluate the influence of obesity on the proteomic profile of periodontal ligament (PDL) tissues of rat first maxillary molars (1 M) submitted to orthodontic tooth movement (OTM). Ten Holtzman rats were distributed into two groups (n = 5): the M group (OTM), and the OM group (obesity induction plus OTM). Obesity was induced by a high-fat diet for the entire experimental periods After that period, the animals were euthanized and the hemimaxillae removed and processed for laser capture microdissection of the PDL tissues of the 1 M. Peptide extracts were obtained and analyzed by LC-MS/MS. Data are available via ProteomeXchange with identifier PXD033647. Out of the 109 proteins with differential abundance, 49 were identified in the OM group, including Vinculin, Cathepsin D, and Osteopontin, which were selected for in situ localization by immunohistochemistry analysis (IHC). Overall, Gene Ontology (GO) analysis indicated that enriched proteins were related to the GO component cellular category. IHC validated the trends for selected proteins. Our study highlights the differences in the PDL proteome profiling of healthy and obese subjects undergoing OTM. These findings may provide valuable information needed to better understand the mechanisms involved in tissue remodeling in obese patients submitted to orthodontic treatment. SIGNIFICANCE: The prevalence of obesity is increasing worldwide. Emerging findings in the field of dentistry suggest that obesity influences the tissues around the teeth, especially those in the periodontal ligament. Therefore, evaluation of the effect of obesity on periodontal tissues remodeling during orthodontic tooth movement is a relevant research topic. To our knowledge, this is the first study to evaluate proteomic changes in periodontal ligament tissue in response to the association between orthodontic tooth movement and obesity. Our study identified a novel protein profile associated with obesity by using laser microdissection and proteomic analysis, providing new information to increase understanding of the mechanisms involved in obese patients undergoing orthodontic treatment which can lead to a more personalized orthodontic treatment approach.

Hyperlipidemic Conditions Impact Force-Induced Inflammatory Response of Human Periodontal Ligament Fibroblasts Concomitantly Challenged with P. gingivalis-LPS

In obese patients, enhanced serum levels of free fatty acids (FFA), such as palmitate (PA) or oleate (OA), are associated with an increase in systemic inflammatory markers. Bacterial infection during periodontal disease also promotes local and systemic low-grade inflammation. How both conditions concomitantly impact tooth movement is largely unknown. Thus, the aim of this study was to address the changes in cytokine expression and the secretion of human periodontal ligament fibroblasts (HPdLF) due to hyperlipidemic conditions, when additionally stressed by bacterial and mechanical stimuli. To investigate the impact of obesity-related hyperlipidemic FFA levels on HPdLF, cells were treated with 200 µM PA or OA prior to the application of 2 g/cm² compressive force. To further determine the additive impact of bacterial infection, HPdLF were stimulated with lipopolysaccharides (LPS) obtained from Porphyromonas gingivalis. In mechanically compressed HPdLF, PA enhanced COX2 expression and PGE2 secretion. When mechanically stressed HPdLF were additionally stimulated with LPS, the PGE2 and IL6 secretion, as well as monocyte adhesion, were further increased in PA-treated cultures. Our data emphasize that a hyperlipidemic condition enhances the susceptibility of HPdLF to an excessive inflammatory response to compressive forces, when cells are concomitantly exposed to bacterial components.

Osteopenic effects of high-fat diet-induced obesity on mechanically induced alveolar bone remodeling

OBJECTIVES

The aim of the study was to investigate the effect of obesity on the tissue and molecular reactions of alveolar bone in response to orthodontic force and its underlying mechanisms.

METHODS

Sixty-four rats were randomly divided into normal diet (ND) and high-fat diet (HFD) groups for eight weeks of dietary treatment. OTM was induced using nickel-titanium springs between the upper left first molar and incisor. After 1, 3, 7, and 14 days of OTM, the maxillary alveolar bone and gingival tissues were harvested and analyzed.

RESULTS

Compared with the ND rats, the HFD rats had greater OTM distance, serum levels of tartrate-resistant acid phosphatase (TRAP), and tumor necrosis factor α (TNF-α), as well as significant alveolar bone loss and bone architecture deterioration on both the compression and tension sides (p < .05 for all). This response was linked to the increased osteoclast numbers and functional activity and decreased osteoblast activity in the periodontal ligament, gingival tissue, and alveolar bone.

CONCLUSIONS

HFD-induced obesity promoted mechanically induced alveolar bone remodeling and detrimental changes in alveolar bone microstructure by increasing osteoclastogenesis and regulating inflammatory cytokine expression. The increased alveolar bone remodeling in the obese rats lead to an accelerated OTM.

Distinguish fatty acids impact survival, differentiation and cellular function of periodontal ligament fibroblasts

Alveolar bone (AB) remodeling is necessary for the adaption to mechanical stimuli occurring during mastication and orthodontic tooth movement (OTM). Thereby, bone degradation and assembly are strongly regulated processes that can be altered in obese patients. Further, increased fatty acids (FA) serum levels affect bone remodeling cells and we, therefore, investigated whether they also influence the function of periodontal ligament fibroblast (PdLF). PdLF are a major cell type regulating the differentiation and function of osteoblasts and osteoclasts localized in the AB. We stimulated human PdLF (HPdLF) in vitro with palmitic (PA) or oleic acid (OA) and analyzed their metabolic activity, growth, survival and expression of osteogenic markers and calcium deposits. Our results emphasize that PA increased cell death of HPdLF, whereas OA induced their osteoblastic differentiation. Moreover, quantitative expression analysis of OPG and RANKL revealed altered levels in mechanically stimulated PA-treated HPdLF. Furthermore, osteoclasts stimulated with culture medium of mechanical stressed FA-treated HPdLF revealed significant changes in cell differentiation upon FA-treatment. For the first time, our results highlight a potential role of specific FA in the function of HPdLF-modulated AB remodeling and help to elucidate the complex interplay of bone metabolism, mechanical stimulation and obesity-induced alterations.

Effects of the multifunctional hormone leptin on orthodontic tooth movement in rats

This study aims to investigate the effects of leptin, which is a multifunctional hormone, on orthodontic tooth movement (OTM) and the underlying mechanism. Sprague-Dawley rat OTM models were established and divided into two groups with the administration of vehicle or leptin respectively. Stereomicroscope and microcomputed tomography were used to evaluate the amount of OTM. TRAP staining, immunohistochemical and immunofluorescence staining were used to detect osteoclasts and relative protein expressions. After treated with compression force, human periodontal ligament cells (hPDLCs) were co-cultured with human peripheral blood mononuclear cells (hPBMCs) with the presence or absence of leptin. Small interfering RNA (siRNA) was transfected to knock down the leptin receptor (LepR). The mRNA expressions of the targeted genes were evaluated by quantitative real-time polymerase chain reaction. We found that leptin receptors were expressed on both rat periodontal ligament cells and hPDLCs. OTM was significantly attenuated in the leptin-treated group comparing to the control group. The number of osteoclasts was reduced in the periodontal ligament tissues in vivo and in vitro co-cultured system when treated with leptin. The expression of RANKL was inhibited by leptin administration either in vivo and in vitro. Leptin administration also inhibited the force-induced up-regulation of RANKL expression in hPDLCs, which was rescued by LepR siRNA transfection. The osteoclastogenesis was attenuated by leptin administration which was reversed by the LepR siRNA transfection. Taken together, leptin was able to attenuate OTM by inhibiting osteoclastogenesis which can be attributed to the reduced expression of RANKL in the periodontal ligament. Leptin may possess the potential for reinforcing anchorage clinically.

Influence of increased body mass index on orthodontic tooth movement and related parameters in children and adolescents: A systematic review of longitudinal controlled clinical studies

Objectives:

To assess the impact of increased body mass index (BMI) on orthodontic tooth movement (OTM) and related parameters in children and adolescents.

Search sources:

A search of six electronic databases and manual searching were performed up to June 2019 without language and time restrictions.

Data selection:

Eligibility criteria were as follows: (1) longitudinal controlled clinical studies; (2) children and adolescents undergoing orthodontic therapy (OT); (3) no systemic diseases; (4) experimental group: patients with increased BMI; and (5) control group: patients with normal BMI.

Data extraction:

Screening, study selection and data extraction were performed; bias within studies was assessed using the Risk of Bias In Non-randomised Studies (ROBINS-I) tool.

Results:

Seven studies were included. One study showed that an increased BMI is associated with less wear-time of removable orthodontic appliances and one study found no significant association. One study showed that an increased BMI is associated with less cooperation during OT; however, not with the treatment results. One study reported higher pain experience during OT in adolescents with than without increased BMI. Two studies showed that increased BMI in adolescents is related to OTM, one with increased and one with decreased rates of OTM, respectively. One study reported an association between increased BMI and incidence of white spot lesions and gingivitis during OT. The ROBINS-I tool showed low to moderate risk of bias within studies.

Conclusions:

The influence of BMI on OTM and related parameters in children and adolescents remains debatable.

Evaluation of leptin concentration in Gingival Crevicular Fluid (GCF) during orthodontic tooth movement and its correlation to the rate of tooth movement

OBJECTIVES:

Leptin, a polypeptide which is related to body fat regulation, is also found to have a role in the inflammatory reaction. The aim of this study is to assess the concentration of leptin in Gingival Crevicular Fluid (GCF) during orthodontic force application and to correlate its concentration to rate of tooth movement.

METHODS:

Twenty orthodontic patients (10 males and 10 females) were selected for the study. Leptin concentration was measured at T0, before force application; T1, one hour after force application; T2, one day after force application; T3, one week after force application; T4, one month after force application. GCF was collected using filter paper strips from the distal aspect of gingival sulcus of the right maxillary canine distalized by an active lace-backs of tooth movement was measured on dental casts, before and one month after force application. One-way ANOVA with Bonferroni correction and Pearson's correlation test were used to analyze the data.

RESULTS:

The mean GCF leptin concentration increased from T0 to T1, rose to a peak at T2, then declined to a minimum value at T3 and then increased to a value at T4, closer to the base line value (T0), and it was statistically significant (P < 0.05). There was positive correlation of the overall mean leptin concentration to rate of tooth movement (correlation coefficient = 0.634).

CONCLUSION:

There was a biphasic change in GCF leptin concentration during one cycle of orthodontic force application. There was a positive correlation between the GCF leptin concentration and rate of tooth movement.

Obesity attenuates force-induced tooth movement in mice with the elevation of leptin level: a preliminary translational study

Increasing number of patients with high body-mass index (BMI) are encountered in the orthodontic clinic with the growing prevalence of obesity and overweight worldwide. Some clinical studies found that the rate of orthodontic tooth movement (OTM) in obese patients decreased. However, how obesity can impact OTM has not been determined yet. Here, we used the high-fat diet (HFD) induced obese mouse model to translate this clinical problem to the basic research, and back to exploring the potential clinical applications. C57BL/6J mice were fed with high-fat diet (HFD) for 5 weeks to induce obesity and orthodontic nickel-titanium springs were applied to the upper first molars to establish OTM model. The serum level of leptin was tested by ELISA. Mouse macrophage cell line RAW264.7 cells were used as osteoclast progenitor cells stimulated by sRANKL with the presence or absence of letpin in vitro. TRAP staining was used to detect osteoclasts. Leptin was administrated intraperitoneally in mice to determine whether it can affect OTM in vivo. In obese mice, we found that OTM was attenuated and the number of osteoclasts decreased with the elevated serum level of leptin. Mechanically, we confirmed that leptin inhibited osteoclastogenesis and osteoclast functional genes expression. To translate our findings back to potential applications, we then revealed the administration of leptin could decrease OTM in wild type mice along with the decreased number of TRAP-positive osteoclasts. Taken together, these results demonstrated that the elevated level of leptin in obese mice was able to inhibit osteoclastogenesis and decrease OTM. Administration of leptin could inhibit molar mesial movement and possessed the potential to be a clinical anchorage reinforcement method.

Salivary leptin levels in normal weight and overweight individuals and their correlation with orthodontic tooth movement

OBJECTIVES

To assess and compare the concentration of leptin in saliva between normal weight and overweight individuals and to evaluate the rate of orthodontic tooth movement.

MATERIALS AND METHODS

Thirty female subjects were divided into two groups: I (normal weight) and II (overweight group) based on their body mass index. All subjects underwent fixed appliance therapy requiring upper first premolar extraction and distal movement of the canine. Distal force was applied to the maxillary right canine using active lacebacks. Salivary samples were collected just before force application (T₀), 1 hour (T₁), and 1 month (T₂) after force application. The rate of tooth movement was evaluated over 3 months and was measured on study models.

RESULTS

At all three time intervals, mean leptin concentration was greater in overweight individuals than normal weight individuals. In both groups at T₁, the mean leptin concentration was found to increase significantly compared with the baseline value (T₀), but at T₂, the leptin concentration declined to values lesser than the baseline values (T₀).

CONCLUSIONS

Overweight individuals had greater salivary leptin concentration. There was a positive correlation between salivary leptin concentration and rate of tooth movement in both normal and overweight individuals. The rate of tooth movement is decreased in overweight individuals as compared with normal weight individuals.

Impact of body mass index on oral health during orthodontic treatment: an explorative pilot study

AIM

To answer the question: is there a correlation between body mass index (BMI), oral health, and patient cooperation during multibracket (MB) appliance therapy?

MATERIALS AND METHODS

All adolescent MB patients started and finished between 2007 and 2012 were analysed. According to their pre-treatment BMI, patients were divided into one of the following groups: normal weight, overweight, or obese. Using the patients' records, the cooperation during treatment was classified as good, bad, or poor and the treatment duration was calculated. Using pre- and post-treatment photographs, white spot lesion (WSL) formation and gingivitis before and after MB therapy were assessed.

RESULTS

Of the 175 subjects, 138 had a normal BMI (79 per cent), 22 were overweight (12.5 per cent), and 15 obese (8.5 per cent). Whereas 42.8 per cent of the normal weight patients showed a good cooperation, only 22.7 per cent of the overweight and 20.9 per cent of the obese patients cooperated sufficiently. On average, normal weight patients were treated for 22.2 months, overweight patients for 23.0 months, and obese patients for 27.7 months. Normal weight patients developed less WSL (41.3 per cent) during MB treatment than overweight (50 per cent) or obese (66.7 per cent) patients. Furthermore, patients with a normal weight or overweight had less gingival inflammation (79.5 per cent) after treatment than obese individuals (93.3 per cent).

CONCLUSION

An increased BMI appears to be a risk factor for less cooperation, a longer treatment duration, and more oral health-related problems during MB treatment, indicating that these patients require special attention during orthodontic therapy.

Quantification of wear-time adherence of removable appliances in young orthodontic patients in relation to their BMI: a preliminary study

PURPOSE

The relationship between unhealthy body mass index (BMI) and adherence to orthodontic treatment with removable appliances has not previously been evaluated.

OBJECTIVE

The aim of this study was to quantify the association between BMI and wear time of removable orthodontic appliances and to evaluate BMI changes during orthodontic treatment.

PATIENTS AND METHODS

Fifty-three normal-weight and 39 overweight/obese children and adolescents (7-15 years old) undergoing orthodontic treatment with removable appliances were enrolled into the study. BMI categories were determined using standardized age-specific and sex-specific BMI criteria, using data measured at the beginning of therapy and once during orthodontic treatment. Wear times of removable appliances were measured at 15-minute intervals over a period of 5 months using implanted microelectronic sensors. Median wear-time values were used in the analysis with the Mann-Whitney U-test used to test statistical differences between groups.

RESULTS

The median wear time of removable orthodontic appliances was 9.3 hours for normal-weight patients and 9.2 hours for overweight/obese patients. No statistically significant (P>0.05) or clinically relevant differences in usage or adherence were detected between normal-weight and overweight/obese patients. BMI did not influence wear time or behavior of removable orthodontic appliances by young patients. The majority of patients showed qualitative decreases in BMI during therapy.

CONCLUSION

The orthodontic treatment of young patients with removable devices does not require BMI-dependent changes in the treatment strategy. However, the use of removable appliances during meal times raises the possibility of reducing food intake, and in this way the orthodontist may have an active role to play in weight reduction.