Preface to the 9th Biennial COAST Conference: Harnessing Technology and Biomedicine for Personalized Orthodontics.

OBJECTIVE: The Consortium on Orthodontic Advances in Science and Technology (COAST) convened for its 9th biennial conference titled 'Harnessing Technology and Biomedicine for Personalized Orthodontics' to explore cutting-edge craniofacial research towards building the foundations for precision care in orthodontics. SETTING AND SAMPLE POPULATION: Seventy-five faculty, scholars, private practitioners, industry, residents and students met at the UCLA Arrowhead Lodge on 6-9 November 2022 for networking, scientific presentations and facilitated discussions. Thirty-three speakers provided state-of-the-art, evidence-based scientific and perspective updates in craniofacial and orthodontic-related fields. The overall format included an Education Innovation Award Faculty Development Career Enrichment (FaCE) workshop focused on faculty career development, three lunch and learns, keynote or short talks and poster presentations. MATERIAL AND METHODS: The 2022 COAST Conference was organized thematically to include (a) genes, cells and environment in craniofacial development and abnormalities; (b) precision modulation of tooth movement, retention and facial growth; (c) applications of artificial intelligence in craniofacial health; (d) precision approaches to Sleep Medicine, OSA and TMJ therapies; and (e) precision technologies and appliances. RESULTS: The collective advances in orthodontics and science represented in the manuscripts of this issue fulfil our goal of laying solid foundations for personalized orthodontics. Participants elevated the need for stronger industry-academic research partnerships to leverage knowledge gained from large datasets with treatment approaches and outcomes; systematizing the potential of big data including through multi-omics and artificial intelligence approaches; refining the genotype: phenotype correlation to create biotechnology that will rescue inherited dental and craniofacial defects; evolving studies of tooth movement, sleep apnoea and TMD treatment to accurately measure dysfunction and treatment successes; and maximizing the integration of newer orthodontic devices and digital workflows. CONCLUSIONS: Technological advances combined with those in biomedicine and machine learning are rapidly changing the delivery of health care including that in orthodontics. These advances promise to lead to enhanced customization, efficiencies and outcomes of patient care in routine orthodontic problems and in severe craniofacial problems, OSA and TMD.

Management of Lateral Epicondylitis: A Prospective Comparative Study Comparing the Local Infiltrations of Leucocyte Enriched Platelet-Rich Plasma (L-aPRP), Glucocorticoid and Normal Saline.

Introduction: Lateral epicondylitis is a painful condition of the elbow, characterised by pain and tenderness with resisted wrist extension. This study was carried out to evaluate the comparative efficacy of the local infiltration of L-PRP, methylprednisolone and normal saline in patients with lateral epicondylitis. Materials and methods: Sixty adult patients, between the ages 30 to 50 years, diagnosed with lateral epicondylitis of more than 12 weeks, were enrolled in the prospective randomised study. Their medical history and previous conservative treatment were recorded; the clinical evaluation of the tendinitis was made with the visual analogue scale (VAS), the disabilities of the arm, shoulder, and hand (DASH) outcome scores, the modified elbow performance index (MEPS), the functional assessment by patient-rated tennis elbow evaluation (PRTEE), together with the laboratory investigations. The patients were randomised using the computer-generated alphabets into three groups of 20: group A received saline, group B received PRP, and group C received corticosteroids. Results: Patients were seen at 4, 8 and 12 weeks to evaluate the post-injection status. VAS, DASH, and PRTEE scores were significantly reduced, and MEPS was significantly improved in group B compared to group A and group C. Moreover, the reductions in VAS and PRTEE were significantly different in group C compared to group A. Conclusion: PRP leads to superior healing with long-term therapeutic advantages compared to corticosteroids though it takes a little longer to have its effect.

Lactobacillus fermentum (MTCC-5898) alleviates Escherichia coli-induced inflammatory responses in intestinal epithelial cells by modulating immune genes and NF-κB signalling.

AIM: Dietary intervention using probiotic bacteria has emerged as a promising preventive strategy in addressing foodborne infections or gastrointestinal disorders. This study investigated the immunomodulatory effects of Lactobacillus fermentum (MTCC-5898) on Escherichia coli-induced inflammatory responses in intestinal epithelial cells. METHODS AND RESULTS: The immune response of intestinal cells (Caco-2) in the presence of probiotic Lact. fermentum was determined during exclusion, competition and displacement of E. coli as the inflammatory agent. To achieve this objective, transcriptional modulation of key immune-related genes (cytokines, pattern recognition receptors and NF-κB), release of cytokines and nuclear translocation of the NF-κB subunit p-65 were studied. Expression of pro-inflammatory cytokines IL-8, TNF-α, IFN-ϒ and IL-23 was high in E. coli-exposed intestinal cells. However, overexpression of these E. coli-induced pro-inflammatory cytokines was prevented by Lact. fermentum during exclusion and competition assays. It also modulated the transcriptional expression of regulatory cytokines (IL-10 and TGF-ß), pattern recognition receptors (TLR-2 and TLR-4) and genes associated with master inflammatory regulators (NF-κB and SIGIRR) to reduce E. coli-induced inflammation. The protective effect of Lact. fermentum was further confirmed by suppression of nuclear translocation of cytoplasmic NF-κB subunit (p-65). CONCLUSION: Lactobacillus fermentum alleviated E. coli-induced inflammatory responses by modulating the NF-κB signalling besides pro-inflammatory and regulatory cytokines expression. SIGNIFICANCE AND IMPACT OF THE STUDY: Lactobacillus fermentum holds significant promise as a potent nutraceutical that prevents and manages inflammatory gut-associated dysfunctions.

Progressive Device Failure at Long Term Follow Up of the Nellix EndoVascular Aneurysm Sealing (EVAS) System.

OBJECTIVE: High rates of midterm failure of the Nellix EndoVascular Aneurysm Sealing (EVAS) System resulted in device withdrawal from the UK market. The study aim was to report long term Nellix EVAS outcomes and management of a failing device. METHODS: A retrospective review of EVAS procedures at a tertiary unit was performed. Device failure was defined as a triad of stent migration, stent separation, and secondary sac expansion, or any intervention for type 1 endoleak, device rupture, or explant. RESULTS: 161 (male n = 140, female n = 21) patients with a median follow up of 6.0 (IQR 5.0-6.6) years were included. Freedom from all cause mortality estimate at six years was 41.5%. There were 70 (43.5%) device failures with a freedom from device failure estimate at six years of 32.3%. Failure was the result of sac expansion (n = 41), caudal stent migration (n = 36), stent separation (n = 26), and secondary AAA rupture (n = 15). A substantial number of type 1 endoleaks was present (1a n = 33, 1b n = 11), but the type 2 endoleak rate was low at 3.7%. Some 36 (22.4%) patients required re-intervention. Twenty-one patients underwent explant with no 30 day deaths. Six patients underwent Nellix-in-Nellix application (NINA) with one early death from bowel ischaemia and one patient who died later from non-aneurysm related cause. Two NINA patients have ongoing sac expansion and two have had thrombosis of a Nellix limb or visceral stent. Proximal embolisation was only successful in one of six cases. CONCLUSION: The long term failure rate of Nellix EVAS is high. All patients with a device must be informed and be enrolled in enhanced surveillance. EVAS explant is an acceptable technique with favourable outcomes. Management by open explant, if the patient is fit, should be considered early and offered to those with device failure.

Erectile Dysfunction in Peripheral Vascular Disease: Endovascular Revascularization as a Potential Therapeutic Target.

INTRODUCTION: Erectile dysfunction (ED) affects more than 150 million men worldwide, with deleterious effects on quality of life. ED is known to be associated with ischemic heart disease but the impact of ED in patients with peripheral arterial disease (PAD) is unknown. We assessed the prevalence and severity of ED in patients with PVD. METHODS: Following ethical approval, sequential male patients diagnosed with PAD over a 1-year period following diagnosis of intermittent claudication. The patient demographics and comorbidities were recorded, with the International Index of Erectile Function (IIEF-5) questionnaire used to grade severity of ED. Computed tomographic angiography and severity of stenosis in the proximal vessels and internal pudendal arteries were correlated using a modified Bollinger Matrix scoring system. RESULTS: 60 patients were recruited, most (77.2%) reported erectile dysfunction (52.5% severe, 22.5% moderate). Patients with severe ED were more likely to have 2 or more comorbidities (P = .009). 86.7% with severe ED had bilateral internal pudendal artery stenosis with a mean modified Bollinger score of 17.6. 35.5% of moderate ED patients had bilateral internal pudendal stenosis with a mean Bollinger score of 11.75. There was significant difference in overall scores between moderate and severe erectile dysfunction (p< 0.05), thus indicating a potential link between ED severity and extent of vessel stenosis. CONCLUSION: There is a substantial burden of clinically significant ED among patients with PAD. This study suggests ED should be discussed with all PAD patients and ED may precede a PAD diagnosis. There is scope for endovascular revascularization as a treatment option for ED secondary to arterial insufficiency.

Estrogen Selectively Enhances TMJ Disc but Not Knee Meniscus Matrix Loss.

The preponderance of temporomandibular joint (TMJ) degenerative disorders in women and their early onset during reproductive years have implicated female sex hormones, particularly 17-ß estradiol (E2), in the pathogenesis of these disorders. Nevertheless, the mechanisms by which E2 contributes to TMJ degenerative disorders and the reasons for its targeted effects on the TMJ but not other joints remain poorly understood. Here, we developed an ovariectomized mouse model in which systemic E2 concentrations mimicked those in cycling women, and we determined the effect of E2 on the targeted turnover of TMJ fibrocartilage matrix via E2-induced matrix metalloproteinases MMP9 and MMP13. Infusion of E2 and progesterone (P4; hormone control) over 7 d resulted in 5- and 8-fold greater serum E2 and P4 levels relative to controls, respectively, achieving systemic hormone levels similar to high baseline levels in cycling women. Administration of E2 but not P4 caused a significant loss of TMJ collagen and glycosaminoglycans, which was accompanied by amplification of ERα and specific increases in MMP9 and MMP13 expression. This dose of E2 had no effect on knee meniscus fibrocartilage, demonstrating the specificity of the degradative effect of E2. Dose-response experiments showed a greater sensitivity and a higher peak induction of MMP9 and MMP13 in TMJ fibrocartilaginous cells than knee meniscus cells to E2, providing an explanation for the differential responses of these tissues to E2. Using MMP9- and MMP13-null mice, we observed no discernible effects of each proteinase individually to E2-mediated TMJ matrix loss but noted a significant compensatory reciprocal induction of each MMP by E2 in the absence of the other. The redundancy in E2's induction of MMP9 and MMP13 suggests that the proteinases may together contribute to E2-mediated TMJ fibrocartilage loss. These results advance our understanding of E2-mediated upregulation of MMP9 and MMP13 on fibrocartilage matrix turnover targeted to the TMJ.

Antibiotic resistance and virulence genes in nisin-resistant Enterococcus faecalis isolated from raw buffalo milk modulate the innate functions of rat macrophages.

AIMS: To elucidate the antibiotic resistance and virulence genes of nisin-resistant Enterococcus faecalis isolated from raw buffalo milk and to study the effect of nisin-sensitive and -resistant E. faecalis on the innate immunity of rats. METHODS AND RESULTS: Slanetz-Bartley agar plates containing nisin were used to isolate nisin-resistant E. faecalis. The virulence factors were ascertained using quantitative real-time polymerase chain reaction. Cell viability, phagocytosis, intracellular survival and enzyme assays were performed to investigate the interaction of E. faecalis with rat macrophages. Nisin-resistant E. faecalis was less prone to phagocytosis and survived longer inside the macrophages, due to reduced production of reactive oxygen species and nitric oxide. The viability and activation of macrophages was also reduced in the presence of resistant E. faecalis, as observed by enhanced lactate dehydrogenase production and reduced ß-galactosidase. CONCLUSIONS: Nisin-resistant E. faecalis and its virulence factors were reported in raw buffalo milk. This study shows that nisin-resistant variants exhibited cross resistance to antibiotics and suppressed the innate immune responses of rats by directly affecting macrophage activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study elucidated the contamination of raw buffalo milk by nisin-resistant E. faecalis, which may pose food safety risk.

17ß-estradiol Induces MMP-9 and MMP-13 in TMJ Fibrochondrocytes via Estrogen Receptor α.

Temporomandibular joint (TMJ) disorders, including degenerative TMJ disease, occur primarily in women of reproductive age. Previous studies showed elevated estrogen levels in subjects with TMJ disorders relative to controls and the presence of estrogen receptors α and ß (ERα and ERß) in TMJ fibrocartilage. Additionally, estrogen-induced overexpression of specific matrix metalloproteinases (MMPs), including MMP-9 and MMP-13, in TMJ fibrocartilage is accompanied by loss of extracellular matrices. However, the contribution of ERα and ERß in estrogen-mediated induction of MMP-9 and MMP-13 and the signaling cascade leading to the upregulation of these MMPs have not been elucidated. Here, we show that specific siRNAs and selective ER antagonists effectively block ERα or ERß expression in primary mouse TMJ fibrochondrocytes, but that only blockage of ERα suppresses MMP-9 and MMP-13 levels induced by 17ß-estradiol (E2). Overexpression of ERα but not ERß enhances E2-induced MMP-9. Using the same loss-of-function and gain-of-function approaches, we demonstrate that E2 stimulates ERK activation through ERα and that inhibition of ERK phosphorylation reduces E2-induced MMP-9. Furthermore, we reveal that E2 promotes NF-κB and ELK-1 activation through ERα/ERK signaling and that knockdown of either one decreases the respective activity of these signaling mediators and MMP-9 expression induced by E2, indicating that both contribute to E2/ERα/ERK-mediated MMP-9 upregulation. This is supported by findings in which mutated binding sites of either NF-κB or ELK-1 in the MMP-9 promoter lead to a significant reduction of E2-stimulated promoter activity. Our findings provide novel molecular mechanisms for the understanding of E2-mediated upregulation of MMPs, having implications to pathophysiologic TMJ cartilage matrix turnover that may yield therapeutic intervention targets for TMJ disorders.

Post-operative arterio-venous fistula blood flow influences primary and secondary patency following access surgery.

PURPOSE: Primary arteriovenous fistula arterio venous fistula (AVF) formation has proven to be the best and optimal vascular access for the majority of haemodialysis patients. At present there are limited data to suggest which haemodynamic parameters most correlate with the likelihood of early failure. The aim of this study is to identify the haemodynamic predictors of early failure, hence identify which fistulae may benefit from timely pre-emptive intervention. MATERIAL AND METHODS: Retrospective analysis of data was performed of 201 patients undergoing native AVF creation over a one year period. Demographic details, co-morbidity, preoperative vessel calibre were collected. Flow was measured by duplex ultrasound post operatively. RESULTS: Preoperative vein calibre (p = 0.01) and fistula flow (p < 0.001) positively affected primary patency. Age, gender, ethnicity, type of fistula, hypertension and preoperative arterial calibre did not influence outcome. Regression analysis showed that the strength of correlation between early postoperative fistula flow and patency decreased progressively with time. Six week flow predicts early, but not late, failure. ROC analysis identified 300 ml/min flow as the best predictor of patency. Fistulae with flow above 300 ml/min were more likely to remain patent over the next 12 months (p < 0.001, HR = 7.4). CONCLUSION: Postoperative fistula flow of less than 300 ml/min identifies AVFs at high risk of early failure. These may be candidates for early intervention with balloon assisted maturation. The findings of this retrospective cohort study strongly support the need for a more robust prospectively designed trial identifying haemodynamic factors that can predict mid and long-term AVF patency.

Selective Role of Discoidin Domain Receptor 2 in Murine Temporomandibular Joint Development and Aging.

Temporomandibular joint (TMJ) disorders are often associated with development of osteoarthritis-like changes in the mandibular condyle. Discoidin domain receptor 2 (DDR2), a collagen receptor preferentially activated by type I and III collagen found in the TMJ and other fibrocartilages, has been associated with TMJ degeneration, but its role in normal joint development has not been previously examined. Using Ddr2 LacZ-tagged mice and immunohistochemistry, we found that DDR2 is preferentially expressed and activated in the articular zone of TMJs but not knee joints. To assess the requirement for Ddr2 in TMJ development, studies were undertaken to compare wild-type and smallie ( slie) mice, which contain a spontaneous deletion in Ddr2 to produce an effective null allele. Analysis of TMJs from newborn Ddr2slie/slie mice revealed a developmental delay in condyle mineralization, as measured by micro-computed tomography and histologic analysis. In marked contrast, knee joints of Ddr2slie/slie mice were normal. Analysis of older Ddr2slie/slie mice (3 and 10 mo) revealed that the early developmental delay led to a dramatic and progressive loss of TMJ articular integrity and osteoarthritis-like changes. Mutant condyles had a rough and flattened bone surface, accompanied by a dramatic loss of bone mineral density. Mankin scores showed significantly greater degenerative changes in the TMJs of 3- and 10-mo-old Ddr2slie/slie mice as compared with wild-type controls. No DDR2-dependent degenerative changes were seen in knees. Analysis of primary cultures of TMJ articular chondrocytes from wild-type and Ddr2slie/slie mice showed defects in chondrocyte maturation and mineralization in the absence of Ddr2. These studies demonstrate that DDR2 is necessary for normal TMJ condyle development and homeostasis and that these DDR2 functions are restricted to TMJ fibrocartilage and not seen in the hyaline cartilage of the knee.

Preface to COAST 2016 innovators' workshop on personalized and precision orthodontic therapy.

OBJECTIVE: A second focused workshop explored how to transfer novel findings into clinical orthodontic practice. SETTING AND SAMPLE POPULATION: Participants met in West Palm Beach (Florida, USA), on 9-11 September 2016 for the Consortium for Orthodontic Advances in Science and Technology 2016 Innovators' Workshop (COAST). Approximately 65 registered attendees considered and discussed information from 27 to 34 speakers, 8 to 15 poster presenters and four lunch-hour focus group leaders. MATERIAL AND METHODS: The innovators' workshops were organized according to five themed sessions. The aims of the discussion sessions were to identify the following: i) the strength and impact of the evidenced-based discoveries, ii) required steps to enable further development and iii) required steps to translate these new discoveries into orthodontic practice. RESULTS: The role of gene-environment interactions that underlie complex craniofacial traits was the focus of several sessions. It was agreed that diverse approaches are called for, such as (i) large-scale collaborative efforts for future genetic studies of complex traits; (ii) deep genome sequencing to address the issues of isolated mutations; (iii) quantifying epigenetic-environmental variables in diverse areas myofascial pain, alveolar remodelling and mandibular growth. Common needs identified from the themed sessions were multiscale/multispecies modelling and experimentation using controlled and quantified mechanics and translation of the findings in bone biology between species. Panel discussions led to the consensus that a consortium approach to establish standards for intra-oral scanning and 3D imaging should be initiated. CONCLUSIONS: Current and emerging technologies still require supported research to translate new findings from the laboratory to orthodontic practice.

Moving towards precision orthodontics: An evolving paradigm shift in the planning and delivery of customized orthodontic therapy.

Advances in precision medicine portend similar progress in orthodontics and will be increasingly harnessed to achieve customized treatment approaches and enhance treatment efficiencies. Our goal is to provide a background on emerging advances in computer technologies and biomedicine and highlight their current and likely future applications to precision orthodontics. A review of orthodontically relevant technologies and advances in pertinent biological research was undertaken. Innovations in computer hardware and software, and 3D imaging technologies offer the ability for customized treatment and biomechanical planning that will be more fully realized within the next few decades. These technologies combined with 3D printing are already being applied to customized appliance fabrication such as aligners and retainers. The future prospects for custom fabrication of orthodontic brackets of appropriate material properties and smart devices are highly desirable and compelling goals. Within biomedicine, the fundamental understanding of cartilage growth and bone biology is currently being tested in animal models to modify mandibular growth and modulate tooth movement, respectively. Some of these discoveries will ultimately have clinical applications in orthodontics including for growth modification, accelerating orthodontic tooth movement, and enhancing anchorage or retention of teeth. Additional genomic and proteomic information will add to further customization of orthodontic diagnosis and treatments. Over the coming decades, precision orthodontics will continue to benefit from advances in many fields and will require the integration of advances in technology, and biomedical and clinical research to deliver optimal, efficient, safe, and reproducible personalized orthodontic treatment.

Protective effects of casein-derived peptide VLPVPQK against hydrogen peroxide-induced dysfunction and cellular oxidative damage in rat osteoblastic cells.

Oxidative stress inhibits osteoblast differentiation and function that lead to the development of osteoporosis. Casein-derived peptide VLPVPQK (PEP), a potent antioxidant, was isolated from ß-casein of buffalo milk. We used an in vitro oxidative stress model induced by hydrogen peroxide (H2O2) in rat osteoblastic cells to investigate the protective effects of PEP against H2O2-induced dysfunction and oxidative damage. Cells were pretreated with PEP (50-200 ng/mL) for 2, 7 or 21 days followed by 0.3 mM H2O2 treatment for 24 h and then markers of osteogenic development, oxidative damage and apoptosis were examined. PEP significantly increased the viability and differentiation markers of osteoblast cells such as alkaline phosphatase and calcium mineralization. Moreover, PEP suppressed the production of reactive oxygen species (ROS), lipid peroxidation and ameliorated H2O2-induced reduction in glutathione, superoxide dismutase and catalase activities. In addition, PEP partially inhibited caspase-9 and-3 activities and reduced propidium iodide-positive cells. Altogether, our results demonstrated that PEP could protect rat osteoblast against H2O2-induced dysfunction and oxidative damage by reduction of ROS production, lipid peroxidation and increased antioxidant enzyme activities. Thus, our data suggest that PEP might be a valuable protective agent against oxidative stress-related diseases such as osteoporosis.

Glutathione biosynthesis and activity of dependent enzymes in food-grade lactic acid bacteria harbouring multidomain bifunctional fusion gene (gshF).

AIMS: To assess glutathione (GSH) biosynthesis ability and activity of dependent enzymes in food-grade lactic acid bacteria (LAB) and correlating with genomic information on GSH system in LAB. METHODS AND RESULTS: Whole-genome sequences of 26 food-grade LAB were screened for the presence/absence of a set of genes involved in de novo GSH system. Multiple strains of Streptococcus thermophilus (37), Lactobacillus casei (37), Lactobacillus rhamnosus (4), Lactobacillus paracasei (8) Lactobacillus plantarum (23) and Lactobacillus fermentum (22) were screened for biochemical evidence of the GSH system. Multiple sequence analysis of GshF sequences was carried out for comparing the genomic signatures between GSH-producing and nonproducing species. CONCLUSIONS: Streptococcus thermophilus was found to have de novo GSH biosynthesis as well as import ability. Lactobacillus sp. were negative for GSH synthesis but could import it from the medium. All the species exhibited prolific GSH reductase and peroxidase activity. Sequence analysis revealed the absence of key amino acid residues as well as a truncated N-terminal region in lactobacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides a comprehensive view on the status of an important antioxidative system (the GSH system) in LAB and is expected to serve as a primer for future work on the mechanistic role of GSH in the group.

Effects of a sensory branch to the posterior external ear canal: coughing, pain, Ramsay Hunt's syndrome and Hitselberger's sign.

BACKGROUND: A distinct nerve innervating the external auditory canal can often be identified in close relation to the facial nerve when gradually thinning the posterior canal wall. This nerve has been attributed to coughing during cerumen removal, neuralgic pain, Hitselberger's sign and vesicular eruptions described in Ramsay Hunt's syndrome. This study aimed to demonstrate the origin and clinical impact of this nerve. METHODS AND RESULTS: In patients with intractable otalgia or severe coughing whilst inserting a hearing aid, who responded temporarily to local anaesthesia, the symptoms could be resolved by sectioning a sensory branch to the posterior canal. In a temporal bone specimen, it was revealed that this nerve is predominantly a continuation of Arnold's nerve, also receiving fibres from the glossopharyngeal nerve and facial nerve. Histologically, the communicating branch from the facial nerve was confirmed. CONCLUSION: Surgeons should be aware of the posterior auricular sensory branch and its clinical implications.

Personalized and precision orthodontic therapy.

OBJECTIVE: To bring together orthodontic stakeholders from academics, industry, and private practice for a series of thematically focused workshops to explore and develop the transfer of novel approaches into clinical orthodontic practice. SETTING AND SAMPLE POPULATION: Twenty-seven invited speakers, eight poster presenters, and participants of the Consortium for Orthodontic Advances in Science and Technology (COAST) 2014 Innovators' Workshop at the Eaglewood Resort and Spa, Itasca, Illinois, September 11-14, 2014. MATERIAL AND METHODS: Five themed sessions involving between 4-7 presentations followed by panel discussions were organized. The aims of the discussion sessions were to highlight important findings and consider the strength of evidence for these, indicate next steps and needed research or technological developments to move forward, and to weigh the expected benefits from these findings and steps to implement in clinical practice. RESULTS: Among important areas for attention identified were need for multiscale and multispecies modeling and experimentation for interspecies translation of results; large-scale collaborative efforts within the profession to address the need for adequate sample sizes for future genetic studies of complex traits such as malocclusion; a consortium approach to improve new technologies such as intra-oral scanning and 3D imaging by establishing standards; and harnessing the growing body of knowledge about bone biology for application in orthodontics. CONCLUSIONS: With increased awareness of the potential of current and emerging technologies, translation of personalized and precision approaches in the field of orthodontics holds ever-increasing promise.

3D superimposition and understanding temporomandibular joint arthritis.

OBJECTIVES: To investigate the 3D morphological variations in 169 temporomandibular ioint (TMJ) condyles, using novel imaging statistical modeling approaches. SETTING AND SAMPLE POPULATION: The Department of Orthodontics and Pediatric Dentistry at the University of Michigan. Cone beam CT scans were acquired from 69 subjects with long-term TMJ osteoarthritis (OA, mean age 39.1±15.7 years), 15 subjects at initial consult diagnosis of OA (mean age 44.9±14.8 years), and seven healthy controls (mean age 43±12.4 years). MATERIALS AND METHODS: 3D surface models of the condyles were constructed, and homologous correspondent points on each model were established. The statistical framework included Direction-Projection-Permutation (DiProPerm) for testing statistical significance of the differences between healthy controls and the OA groups determined by clinical and radiographic diagnoses. RESULTS: Condylar morphology in OA and healthy subjects varied widely with categorization from mild to severe bone degeneration or overgrowth. DiProPerm statistics supported a significant difference between the healthy control group and the initial diagnosis of OA group (t=6.6, empirical p-value=0.006) and between healthy and long-term diagnosis of OA group (t=7.2, empirical p-value=0). Compared with healthy controls, the average condyle in OA subjects was significantly smaller in all dimensions, except its anterior surface, even in subjects with initial diagnosis of OA. CONCLUSION: This new statistical modeling of condylar morphology allows the development of more targeted classifications of this condition than previously possible.

Locally limited inhibition of bone resorption and orthodontic relapse by recombinant osteoprotegerin protein.

OBJECTIVES: To determine minimal dose levels required for local inhibition of orthodontic relapse by recombinant OPG protein (OPG-Fc), while also determining effects of injected OPG-Fc on alveolar bone and long bone. SETTING AND SAMPLE POPULATION: The Department of Orthodontics and Pediatric Dentistry at the University of Michigan. Eighteen male Sprague Dawley rats. MATERIALS & METHODS: Maxillary molars were moved with nickel-titanium springs and then allowed to relapse in Sprague Dawley rats. Upon appliance removal, animals were injected with a single dose of 1.0 mg/kg OPG-Fc, 0.1 mg/kg OPG-Fc, or phosphate-buffered saline (vehicle) just distal to the molar teeth. Tooth movement measurements were made from stone casts, which were scanned and digitally measured. Alveolar tissues were examined by histology. Micro-computed tomography was used to quantify changes in alveolar and femur bone. RESULTS: Local injection of OPG-Fc inhibited molar but not incisor relapse, when compared to vehicle-injected animals. No significant differences in alveolar or femur bone were seen between the three treatment groups after 24 days of relapse. CONCLUSIONS: Our results demonstrate that a single local injection of OPG-Fc effectively inhibits orthodontic relapse, with minimal systemic bone metabolic effects. Our results also show that a single injection of OPG-Fc will influence tooth movement only in teeth close to the injection site. These findings indicate that OPG-Fc has potential as a safe and effective pharmacological means to locally control osteoclasts, for uses such as maintaining anchorage during orthodontic tooth movement and preventing orthodontic relapse in humans.

Immortalization and characterization of mouse temporomandibular joint disc cell clones with capacity for multi-lineage differentiation.

OBJECTIVE: Despite the importance of temporomandibular joint (TMJ) disc in normal function and disease, studying the responses of its cells has been complicated by the lack of adequate characterization of the cell subtypes. The purpose of our investigation was to immortalize, clone, characterize and determine the multi-lineage potential of mouse TMJ disc cells. DESIGN: Cells from 12-week-old female mice were cultured and immortalized by stable transfection with human telomerase reverse transcriptase (hTERT). The immortalized cell clones were phenotyped for fibroblast- or chondrocyte-like characteristics and ability to undergo adipocytic, osteoblastic and chondrocytic differentiation. RESULTS: Of 36 isolated clones, four demonstrated successful immortalization and maintenance of stable protein expression for up to 50 passages. Two clones each were initially characterized as fibroblast-like and chondrocyte-like on the basis of cell morphology and growth rate. Further the chondrocyte-like clones had higher mRNA expression levels of cartilage oligomeric matrix protein (COMP) (>3.5-fold), collagen X (>11-fold), collagen II expression (2-fold) and collagen II:I ratio than the fibroblast-like clones. In contrast, the fibroblast-like clones had higher mRNA expression level of vimentin (>1.5-fold), and fibroblastic specific protein 1 (>2.5-fold) than the chondrocyte-like clones. Both cell types retained multi-lineage potential as demonstrated by their capacity to undergo robust adipogenic, osteogenic and chondrogenic differentiation. CONCLUSIONS: These studies are the first to immortalize TMJ disc cells and characterize chondrocyte-like and fibroblast-like clones with retained multi-differentiation potential that would be a valuable resource in studies to dissect the behavior of specific cell types in health and disease and for tissue engineering.