Primary failure of eruption (PFE) is a rare disorder characterized by failure of teeth to erupt, which leads to severe lateral open bite. It is often caused by heterozygous mutations in the parathyroid hormone receptor (PTH1R) gene. Although a variety of PTH1R mutants has been shown to be associated with PFE, molecular disease-causing mechanism are rarely identified. We here describe a co-segregation study and the cell biological characterisation of the PTH1R variant H442D that hitherto has been classified as of uncertain clinical significance. In a cohort study, we show that the H442D variant segregates with PFE. Moreover, while it displays correct localization to cell membranes, it evokes only modest levels of the downstream second messenger cAMP upon stimulation with PTH. Our study provides a molecular mechanism for the co-segregation of the PTH1R variant H442D with PFE. The decreased PTH-dependent cAMP signal may be causative for the observed PFE phenotype in subjects carrying this heterozygous mutation.
Abstract Background Infraocclusion of a permanent first molar, frequently due to ankylosis, can disrupt occlusal development and generate asymmetries. This study aimed to evaluate dental developmental differences caused by infraoccluded permanent first molars. Methodology A retrospective, two-center, split-mouth cross-sectional study analyzed panoramic radiographs of 45 patients (9–25 years) with a single, unilateral, infraoccluded permanent first molar. The contralateral molar served as control. Measurements included infraocclusion severity, teeth position within the arch, adjacent-tooth tipping and spacing, root length, presence and degree of root dilaceration. Results Infraoccluded permanent first molars were positioned 5.6(3.3) mm (95% CI, 5 to 7; p < 0.001) lower than controls and were significantly more distal within the arch ( p < 0.001), with adjacent teeth also displaced distally. Adjacent teeth tipped toward the infraoccluded molar: second premolars were 8(12)° more distally angulated (95% CI, 5 to 12; p < 0.001) and second molars 6(19)° more mesially angulated (95% CI, 0.6 to 15; p = 0.003). Posterior spacing was more frequent on the affected side (OR = 15.5; 95% CI 4 to 133; p < 0.001). Infraoccluded molars had roots that were 2.8(5.4) mm shorter than controls (95% CI, 1.2 to 4.4; p < 0.001) and a markedly higher prevalence of root dilaceration (OR = 18.5; 95% CI 5 to 158; p < 0.001). Infraocclusion severity was linearly associated with dilaceration severity ( r = 0.69; p = 0.0001). Adjacent teeth showed a similar trend toward higher prevalence and severity of dilacerations on the affected side. Conclusions Unilateral infraoccluded permanent first molars are strongly associated with shortened roots, increased root dilaceration, and significant distal displacement of the affected and adjacent teeth. Other effects include tipping and spacing of the adjacent teeth.
Autologous platelet concentrates (APCs) have been increasingly used to accelerate orthodontic canine retraction; however, their effectiveness and associated clinical outcomes remain unclear. To evaluate the effectiveness of platelet-rich plasma (PRP), injectable platelet-rich fibrin (i-PRF), and leukocyte-platelet-rich fibrin (L-PRF) in accelerating canine retraction following premolar extraction and to summarize associated clinical outcomes including canine movement patterns, anchorage loss, and treatment-related adverse outcomes. A systematic review and meta-analysis was conducted by searching PubMed, Embase, Web of Science, Scopus, and the Cochrane Library up to April 24, 2026. Randomized and controlled clinical studies involving orthodontic patients undergoing canine retraction following premolar extraction and evaluating the effects of APCs were included. Random-effects meta-analyses and GRADE assessments were performed when appropriate. 28 articles representing 26 unique studies were included in the qualitative synthesis, of which 16 studies were included in the meta-analysis. PRP demonstrated the most consistent evidence of accelerated canine retraction during the first month of treatment. i-PRF showed statistically significant effects across multiple observation periods, whereas L-PRF exhibited an earlier response pattern, with effects observed from the first week through the third month. However, substantial heterogeneity was observed in the i-PRF and L-PRF analyses. No consistent effects were identified on canine movement pattern or anchorage loss. No consistent increase in serious adverse outcomes was observed, although transient post-procedural pain and discomfort were reported following PRP and i-PRF administration. Moderate-certainty evidence supported the first-month effect of PRP, whereas all remaining findings were supported by low- to very low-certainty evidence. APCs may accelerate orthodontic canine retraction following premolar extraction without clear evidence of increased adverse outcomes. The most reliable evidence currently supports a possible short-term benefit of PRP during the first month of treatment. Although i-PRF and L-PRF demonstrated potential effects over longer or earlier observation periods, the certainty of evidence remains low and substantial heterogeneity limits confidence in these findings. Further well-designed randomized controlled trials are required to determine the clinical relevance of these effects and to establish optimal application protocols. PROSPERO (CRD 420261377123).
Abstract Background Torque control of anterior teeth remains a major challenge in clear aligner therapy. Power ridges have been introduced to improve buccolingual root control; however, their biomechanical performance in directly printed aligners remains insufficiently investigated. The aim of this study was to compare the torque efficiency of power ridges in thermoformed and directly printed aligners. Methodology A controlled in-vitro study was conducted using a standardised maxillary model requiring incisor torque correction. Four aligner groups were evaluated: Zendura Flex thermoformed aligners (Bay Materials LLC, USA) with (ZF-PR) and without (ZF-C) power ridges, and two directly printed aligners with power ridges fabricated from TA-28 (Graphy Inc., Seoul, South Korea) and DCA (LuxCreo Inc., Bellevue, WA, USA) resin materials. Power ridges were digitally positioned on the labial gingival third of the maxillary central incisors. Biomechanical testing was performed using the Orthodontic Measurement and Simulation System (OMSS) to assess torque expression, root displacement, and force–moment systems under controlled temperatures (25 °C and 37 °C). Results Torque expression demonstrated a clear material-dependent pattern. ZF-C, used as the baseline, showed moderate and consistent torque expression (38–39% of the programmed torque) across temperatures, with no significant temperature-dependent differences. DCA exhibited the highest torque expression, reaching 62% at 25 °C and 47% at 37 °C. ZF-PR showed intermediate performance (32–42%) with moderate temperature-related variation. TA-28 demonstrated the lowest torque expression (10–17%) with no significant temperature effect. Secondary outcomes supported these findings, with moment generation and displacement patterns correlating with torque expression, whereas force magnitude did not. Conclusions Torque expression in clear aligner systems is primarily governed by material properties and thermomechanical behaviour. Design features alone cannot fully compensate for limitations in material performance. Effective torque delivery depends on the generation and transmission of an appropriate force–moment system rather than on force magnitude alone.
Laypeople can choose from a variety of orthodontic care pathways. It is in the clinician’s best interest to understand their preferences in order to tailor consumer engagement. This scoping review maps the evidence concerning laypeople’s preferences for orthodontic providers and appliances. The review follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. Two reviewers conducted a systematic search and an independent screening process across five electronic databases until December 2025. A total of 56 studies (48 cross-sectional questionnaires; seven qualitative; one mixed methods) comprising 16,271 laypeople across 17 countries were included. Forty-two studies examined perspectives for orthodontic appliances, and 20 studies investigated providers. Specialist orthodontists were consistently the most preferred treatment providers, primarily associated with perceived higher quality and expertise. Direct-to-consumer (DTC) treatment appealed to a minority and was associated with lower cost, self-perceived easier-to-treat malocclusion and convenience. Adults preferred and were willing to pay more for aesthetic appliances, whereas children and adolescents perceived metallic braces as more aesthetic. Pragmatic appliance features such as effectiveness, comfort, and treatment outcomes often outweighed appearance, especially among informed or experienced patients. Common public misperceptions included confusion between general dentists and orthodontists, and overestimation of DTC safety and effectiveness. While DTC and aligners appeal to the public demand for aesthetics and convenience, preference for orthodontists and fixed appliances remains strong, driven by perceived quality and the social acceptability of metal braces in children and adolescents. Better public and in-chair education is recommended to address misperceptions and guide better-informed decision-making.
