Background/Objectives Orthodontic tooth movement (OTM) relies on mechanobiological interactions between osteoblasts and human periodontal ligament stem cells (hPDLSCs). While mechanical compression alters osteoblast behavior-upregulating RANKL/OPG and inflammatory mediators-its paracrine effects on hPDLSCs remain poorly understood. This study investigated how osteoblast-derived secretomes, conditioned by compressive forces, modulate hPDLSC differentiation.Materials/Methods hPDLSCs were isolated from third molars and characterized via immunophenotyping (CD105, CD73, CD90), clonogenicity assays, and multipotent differentiation (osteogenic/adipogenic). Osteoblastic spheroids (hFOB 1.19) were subjected to 0, 1, or 4 g/cm2 compression for 24/72 hours, generating conditioned media. hPDLSCs were exposed to these media for 48 hours, and viability, gene expression (RT-qPCR), and mineralization (Alizarin Red) were assessed.Results Compressive stress attenuated osteoblast secretome-induced osteogenic marker expression in hPDLSCs (RunX2, ALP, Col1, OPN), with no effect on osteocalcin. Sox9 (chondrogenic) was downregulated, while adipogenic markers (PPAR gamma, Adipsin) remained unchanged. No mineralization occurred under any condition. Viability assays confirmed no adverse effects on proliferation.Limitations The in vitro monoculture model used here does not fully recapitulate the spatial and temporal complexity of cell-cell interactions in vivo, including bidirectional signaling and the influence of the extracellular matrix.Conclusions/Implications These findings suggest that mechanical compression disrupts osteoblast-secretome-mediated osteogenic priming of hPDLSCs, potentially explaining resorption-site dynamics during OTM. Future studies should isolate extracellular vesicles (EVs) from stressed osteoblasts to identify cargo (e.g. miRNAs) driving MSC fate. Understanding this paracrine axis may optimize orthodontic treatments and regenerative therapies.
Background Over the past 40 years, randomized trials have become the mainstay of evidence-based orthodontics.Materials and Methods This paper represents the content of the Sheldon Friel lecture presented in 2026 at the Congress of the European Orthodontic Society. I outline the value of randomized trials and revisit the findings of some of the main studies I have completed. We must also consider the development of patient-relevant outcomes and core outcome sets. While we recognize the value of trials, we must also recognize that evidence-based care is undermined by claims from the orthodontic fringe.Conclusions Tension currently exists between the evidence-based orthodontic approach and the low-quality evidence provided by the orthodontic fringe. This paper provides an overview of these two views. The solution to this dilemma lies in carrying out high-level research and making the findings relevant and understandable to our patients.
Background Poor adherence in orthodontic care is a complex issue involving both children and their parents. The study aimed to expand the theory of planned behavior (TPB) by integrating sense of coherence (SOC) to predict appointment attendance in adolescent orthodontic patients. Materials and methods This prospective cohort study recruited adolescents from the University of Alberta Graduate Orthodontic Clinic. Baseline questionnaires captured sociodemographic data, TPB constructs, and SOC. Appointment attendance and oral hygiene were monitored over 1 year. Structural equation modeling (SEM) was used to examine relationships between TPB constructs and appointment adherence, with model fit assessed using chi(2), chi-square/degrees of freedom ratio (CMIN/DF), root mean square error of approximation (RMSEA), and comparative fit index (CFI). Results A total of 168 adolescent-parent pairs participated, and 57% of participants missed at least one appointment during the first year of treatment. SEM demonstrated moderate model fit (CMIN/DF = 1.74; RMSEA = 0.06; CFI = 0.84). Within the TPB constructs, only perceived behavioral control (PBC) significantly predicted intention (P < 0.05), whereas attitude and subjective norm were not significant predictors. SOC did not significantly predict intention, TPB constructs, or appointment adherence in either the adolescent or parent models. Intention also failed to significantly predict actual attendance. Conclusion Within the expanded TPB-SOC framework, PBC was the sole psychosocial predictor of orthodontic appointment-adherence intention. However, neither intention nor SOC translates into actual clinical attendance. The moderate model fit indicates that psychosocial constructs alone are insufficient to fully explain orthodontic appointment adherence. To build more effective adherence models, future research and clinical strategies must look beyond psychology and account for structural, logistical, and environmental barriers.
Objectives To compare the effectiveness and efficiency of clear aligners (CA) with fixed appliances (FA) during presurgical orthodontics for combined orthodontic-orthognathic treatment of skeletal Class III malocclusion. Materials and methods In this single-centre retrospective cohort, 95 patients (16-36 years) treated between 2019 and 2021 were stratified by appliance and extraction status: FA nonextraction (n = 24), FA extraction (n = 28), CA nonextraction (n = 24), and CA extraction (n = 19). The prespecified primary effectiveness outcome was maxillary incisor decompensation (Delta U1-SN); the key efficiency outcome was recorded presurgical duration. Adjusted within-stratum CA-FA contrasts used HC3 robust linear models with Benjamini-Hochberg correction across the secondary-outcome family. Results CA were associated with shorter recorded duration in both strata (nonextraction -143.6 days, P = .020; extraction -263.0 days, P = .0005) and fewer follow-up visits (-8.41 and -13.52; both P < .001). A prespecified sensitivity analysis adding each CA patient's aligner delivery wait left the extraction association intact (-231.7 days, P = .0023) but rendered the nonextraction association marginal (-117.6 days, P = .055). CA showed greater maxillary incisor decompensation in both strata (primary outcome, raw P: nonextraction +4.63 degrees, P = .027; extraction +4.37 degrees, P = .044, marginal). No secondary effectiveness outcome survived correction, and a simulated surgical readiness index showed no difference. Conclusions In this retrospective cohort, CA were associated with shorter recorded presurgical treatment, fewer visits and greater maxillary incisor decompensation than FA. The nonextraction duration association became marginal once the delivery wait was incorporated, whereas the extraction-stratum association was largely preserved. Prospective controlled studies are needed to confirm these findings.
