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.
With the growing demand for orthodontic treatment among adults, a clear understanding of the age-related dentoalveolar changes has become increasingly important for accurate diagnosis, treatment planning, and long-term retention strategies. This study aims to characterize dentoalveolar changes in individuals with normal occlusion from early adolescence (13 years) to late adulthood (62 years) across four time points, using digitally derived measurements and strict inclusion and exclusion criteria. Thirty orthodontically untreated subjects (11 males, 19 females) recruited through the Public Dental Health Care system in, were examined at mean ages of 13 (T1), 16 (T2), 31 (T3), and 62 years (T4). Stone casts of the maxillary and mandibular arches were digitized using a high-resolution 3D scanner. Eleven variables were digitally assessed: overjet, overbite, intercanine width, intermolar width, arch depth, palatal height, curve of Spee, clinical crown height, arch length, space deficiency, and irregularity index. Changes across time points were analyzed using the Wilcoxon signed-rank test. Sagittally, overjet remained stable, whereas arch depth decreased significantly in both arches. Vertically, overbite decreased significantly, while clinical crown height increased significantly in both arches. Palatal height increased significantly up to age 31, and the curve of Spee decreased significantly by age 16. Transversely, maxillary and mandibular intermolar widths, as well as maxillary intercanine width, showed no significant changes, whereas mandibular intercanine width decreased significantly. In terms of space, maxillary and mandibular arch lengths decreased significantly at all time points, accompanied by significant increases in space deficiency and in the irregularity of the mandibular incisors throughout the observation period. Age-related dentoalveolar changes continue from adolescence into late adulthood, supporting the concept that occlusion remains dynamic throughout life. These longitudinal findings provide clinically relevant reference data for orthodontic diagnosis, treatment planning, and the development of effective long-term retention strategies.
Clear aligner (CA) therapy has experienced rapid use over the past two decades to treat orthodontic malocclusions. However, evidence on CA material degradation in the oral environment remains limited and often focuses on single brands or isolated material properties. To investigate CA ageing characteristics across different materials and brands and evaluate the chemical, physical, mechanical, and morphological changes following simulated or intraoral ageing. Five databases (PubMed, Web of Science, MEDLINE [Ovid], ProQuest, and Scopus) were searched to 18 March 2026, with no restrictions. Studies assessing CA properties after intraoral use or simulated ageing (thermocycling, cyclic loading, or liquid immersion) were included. Study selection followed PRISMA 2020. RoB was assessed using QUIN for purely in vitro studies, JBI for cohort in vivo studies, and Cochrane RoB 2 for RCTs. Results were synthesised narratively and organised by property domain, as substantial methodological heterogeneity precluded formal meta-analysis. Where protocols were comparable, a simple pooled weighted mean was calculated and presented graphically. Ninety-five studies were included. RoB was low in eight studies, moderate in sixty-two, and high in twenty-five. Chemical composition remained largely stable during ageing, though some brands showed trace elemental release. Physical, mechanical, and morphological properties showed material-dependent deterioration. Pooled discolouration was greatest with coffee (weighted mean ΔE = 70.9), versus tea (ΔE = 18.4) and red wine (ΔE = 11.5), with Invisalign® consistently exceeding the clinically perceptible threshold. Force decay of 40–90
