To quantitatively compare nickel and chromium ion release and corrosion resistance of copper–nickel–titanium (Cu–NiTi), stainless steel (SS), and beta-titanium (β-Ti) archwires following immersion in povidone-iodine (Betadine), chlorhexidine, amine fluoride (Amflor) mouthwashes, and distilled water. An in vitro study was performed using 60 rectangular archwire specimens (20 each of Cu–NiTi, SS, and β‑Ti), divided into four subgroups according to the immersion medium (chlorhexidine, Betadine, Amflor, distilled water; n = 5 per subgroup). Wires were immersed in each solution at 37 °C for 1.5 h to simulate approximately 3 months of daily mouthwash exposure. Metal ion release was analyzed by atomic absorption spectrophotometer (AAS), while corrosion behavior was assessed using potentiodynamic polarization via a Zive SP1 potentiostat. Two-way analysis of variance (ANOVA) with Tukey’s post hoc test was used to determine statistically significant effects of wire and solution type (p < 0.05). Significant differences were observed among wire and solution types (p < 0.001). β‑Ti wires showed no detectable metal ion release and the lowest corrosion rates. Cu–NiTi and SS wires exhibited measurable nickel release, highest in chlorhexidine (46.91 ppm for Cu–NiTi, 42.93 ppm for SS). Chromium release was exclusive to SS (maximum 23.62 ppm). The corrosion hierarchy was chlorhexidine > Betadine > Amflor > distilled water, with β‑Ti demonstrating superior resistance. Both material composition and mouthwash formulation critically affect corrosion and ion release. β‑Ti exhibits optimal biocompatibility, whereas chlorhexidine significantly accelerates corrosion.
To compare the acceleration effect of piezocision and modified piezocision (a combination of piezocision and piezopuncture) on canine retraction. In this two-arm parallel, split-mouth randomized clinical trial, 30 participants (15–25 years) undergoing fixed orthodontic treatment with the extraction of first upper premolars and canine retraction were randomly assigned to piezocision or modified piezocision groups. Thirty surgical procedures were performed using a split-mouth design, with 15 in each interventional arm, and the contralateral sides were treated in a conventional way (control). Outcomes assessed included the amount of canine retraction (primary outcome variable), rotation, inclination changes, root resorption, and molar anchorage loss. Data analysis included paired t‑tests, Wilcoxon signed-rank tests (between experimental and control sides), independent t‑tests, and Mann–Whitney U tests (between experimental sides). The level of significance was set at P < 0.05. Canine retraction on the experimental side in the piezocision group was 1.5 times greater than on the control side (3.83 ± 0.17 mm vs. 2.46 ± 0.31 mm, P < 0.001). In the modified piezocision group, retraction was nearly twice as great on the experimental side compared to the control (5.13 ± 0.14 mm vs. 2.50 ± 0.32 mm, p = 0.001). The modified piezocision technique showed significantly higher (p-value < 0.001) canine retraction than the original piezocision technique. Secondary outcomes showed nonsignificant differences. No harm was observed other than mild postsurgical pain and swelling, which were controlled with appropriate medications. Both modified and traditional piezocision techniques effectively accelerated canine retraction. However, the modified technique demonstrated superior results, offering a promising avenue for future orthodontic practice.
Artificial intelligence (AI) is rapidly transforming orthodontics, yet a comprehensive and up-to-date bibliometric analysis is lacking. This study systematically maps key research areas, influential contributors, and collaborative networks driving AI innovation. A comprehensive search was conducted in the Web of Science (Clarivate, London, UK) for AI and orthodontics articles up to January 10, 2026. CiteSpace (version 6.2.R6, Drexel University, Philadelphia, PA, USA) and VOSviewer (version 1.6.20, Centre for Science and Technology Studies, Leiden University, Leiden, The Netherlands) were used to extract and visualize the data, including publications, journals, institutions, countries, highly cited articles, authors, and keywords. A total of 454 articles were included, authored by 2150 authors affiliated with 674 institutions across 64 countries. The research landscape has expanded exponentially since 2019, with the USA, China, and South Korea emerging as primary global collaboration hubs. Keyword burst analysis highlighted the rapid clinical integration of AI applications in image recognition, diagnosis, and evaluation. This study maps AI integration trends, showing how AI enhances diagnostic precision and treatment evaluation. These insights might be able to guide researchers toward cutting-edge frontiers. Future research should prioritize multimodal data integration, personalized treatment workflows, and patient privacy protection.
To investigate how age-related changes in midpalatal suture morphology influence skeletal response to varying force magnitudes in nonsurgical rapid palatal expansion (RPE) using a rat model. Nine rats were allocated to an age-based analysis (2, 4, and 8 months; n = 3 per group) to evaluate physiologic age-related development in midpalatal suture morphology. Thirty-five mature rats (8 months) were further assigned to light force (50 g), heavy force (200 g), or control groups. Forces were applied via custom-fabricated expansion devices for 3, 7, and 14 days. Micro-computed tomography (micro-CT), histological analysis, and immunohistochemistry were performed. Histological analysis included qualitative and quantitative assessments. Micro-CT was used for evaluating suture separation, bone volume fraction (BV/TV), and bone mineral density (BMD). Immunohistochemistry assessed the expression of bone remodeling markers. Increased age correlated with reduced midpalatal suture separation and bone formation. Heavy forces resulted in significantly greater suture separation at early time points but also induced more bone resorption, as indicated by lower BV/TV and BMD values. Immunohistochemistry confirmed increased RANKL expression in heavy force groups, indicating enhanced bone remodeling activity. Midpalatal suture response is significantly influenced by both age and the magnitude of applied force. While heavy force promotes faster suture separation, it leads to increased bone resorption and reduced bone quality. In contrast, light force results in a more gradual separation but supports earlier osteoclastic activity, greater vascularization, and better preservation of bone structure. These findings underscore the importance of age-appropriate force selection in nonsurgical RPE protocols.
To examine associations between vertical craniofacial growth pattern, self-reported daytime sleepiness, sleep-related complaints, and lip posture in adolescents. This cross-sectional study included 157 adolescents aged 12–14 years classified as hyperdivergent (n = 121) or normodivergent (n = 36). Daytime sleepiness and sleep-related complaints were assessed using an Epworth sleepiness scale (ESS)-based questionnaire and Berlin questionnaire (BQ)-derived items. Lip posture was measured cephalometrically. Independent t‑tests, chi-square/Fisher exact tests, Pearson correlations, and multiple linear regression were used. Hyperdivergent adolescents had higher ESS and BQ scores (p < 0.001; ESS d = 0.70), more frequent sleep-disordered breathing (SDB)-related symptoms (p < 0.05), and a significant Frankfort mandibular plane angle (FMA)–ESS association after adjustment for age, body mass index, and sex (β =0.354, p < 0.001). Lip posture showed no group differences or associations with BQ, with only weak correlations with ESS or sleep duration. Hyperdivergence, but not lip posture, was associated with greater questionnaire-derived sleepiness and SDB symptoms.
Successful orthognathic therapies are characterised by a physiologically configured occlusion whose long-term clinical stability is mainly assessed through occlusal parameters. In the present study, long-term treatment outcomes were assessed based on occlusal changes after 5 years using digital occlusion and masticatory efficiency analysis. This study examined 33 adult patients after treatment of skeletal class II (n = 18; 12 women, median age 28.15 years; interquartile range [IQR] = 15.10) and class III malformations (n = 15; 7 women, median age 23.90 years; IQR = 4.80) 9 months (T1) and 5 years (T2) postorthognathic therapy. A total of 20 patients with neutral skeletal relation (10 women; median age 30.50 years; IQR = 7.50) served as a control group. Skeletal classification was based on sagittal jaw configuration (Wits) and habitual intercuspation was recorded using the T‑Scan Novus® (Tekscan Inc., South Boston, MA, USA) for digital occlusion analysis with the following variables: total tooth contact (TTC), occlusion time (TOC), occlusion asymmetry (OAS), anterior and posterior antagonism (ATC and PTC). In addition, masticatory performance was assessed using a standardized two-colour chewing gum bolus analysis. Five years after surgery (T2), none of the occlusal parameters differed significantly between the groups, indicating functional approximation to the control group. Longitudinal analysis revealed significant improvements within both surgical groups (T1 to T2). In class II patients, TTC, ATC and PTC increased, while TOC decreased significantly. Class III patients also showed significant increases in TTC, ATC and PTC with TOC and OAS remaining unchanged. Overall, both treatment groups demonstrated substantial recovery and long-term stabilization of occlusal function. Bolus homogeneity analysis showed no significant difference between control and treatment patients 5 years after surgery. The 5‑year observation of orthognathic treatment for sagittal jaw malformations showed significant improvements in occlusal parameters. Both masticatory efficiency and occlusal parameters measured at 5 years postoperatively did not differ significantly from the control group, indicating that the functional improvements achieved by the therapy were stable in the long term.
Surgically facilitated anterior maxillary distraction (AMD) is used for the treatment of maxillary hypoplasia secondary to cleft lip and palate (CLP). In this study, the soft and hard tissue changes following AMD in growing patients with CLP were evaluated to determine the extent of changes that occurred. Cephalometric records of 8 growing patients with maxillary hypoplasia secondary to CLP were obtained. They were treated with AMD using a modified hyrax appliance. The preoperative (T1) and postoperative records (T2: after 1 year of consolidation and growing period) were analyzed using Dolphin software (version 11.95; Dolphin Imaging, Chatsworth, CA USA) and subjected to statistical analyses. Cephalometric analysis was performed by the same operator. The values of SNA, U1-NA, U1-PP, U1-SN, L1-NB, AO-BO, OCC-SN angle, Sn-St increased significantly after the AMD procedure (p < 0.05). However, the soft tissue parameters nasolabial angle (Cm-Sn-Ls), facial height ([Gla]–Sn), and mentolabial sulcus depth (LiPo-Sm) did not show statistically significant changes (p < 0.05). These results concur that AMD produced midfacial profile changes in patients with CLP. After AMD, the negative overjet decreased and proclination of the upper incisors was observed. Soft tissue parameters did not show statistically significant changes during the study period. The study proved that changes to correct the class III malocclusion occur primarily in the hard tissue and the results were significant.
This prospective randomized clinical study aimed to evaluate the effectiveness of maxillary protraction with differently located miniplates combined with intermaxillary elastic applications after corticotomy in patients with skeletal class III malocclusion. Twenty patients aged 13–15 years were randomly assigned to one of three groups using a computer-generated random sequence. In the AS and MS groups, an acrylic splint (AS) with hooks in the upper molar region was cemented; the MS group additionally received two palatal miniscrews (MS) for anchorage. In all patients, incomplete Le Fort I osteotomy was performed. Miniplates were placed vertically between the mandibular canine and first premolar in all groups, and horizontally under the osteotomy line in the MP group. Class III elastics were applied 5 days postsurgery and continued until a positive overjet was achieved. Cephalometric radiographs were taken at the beginning of treatment (T0) and at the end of the protraction period (T1). The MP group exhibited the greatest maxillary advancement (3.2 ± 2.2 mm, p < 0.05). Significant B‑point changes occurred in the MP (−1.2 ± 1 mm, p < 0.05) and AS (−0.9 ± 0.9 mm, p < 0.05) groups. The AS group had the largest increase in upper incisor angulation (U1-SN: 5.5° ± 2.5; U1-PP: 4.7° ± 3.3, p < 0.05). All groups showed favorable soft tissue changes; in the MS group the best control of mandibular clockwise rotation was achieved. The duration of protraction period was 5.52 ± 0.9 months for the MP group, 4.84 ± 1.3 months for the AS group, and 4.74 ± 1.18 months for the MS group. Although significant improvement was observed in maxillomandibular relations in all groups, the greatest change was observed in the MP group (p < 0.01). The use of skeletal anchorage helped reduce dentoalveolar changes. The MS group was most successful in controlling clockwise rotation of the mandible.
To compare the incidence, severity, and regional distribution of white spot lesions (WSLs) between clear aligner therapy (CAT) and fixed appliance therapy (FAT) using standardized intraoral photographs supported by digital scans. This retrospective comparative study included pre- (T0) and posttreatment (T1) records of 100 patients treated with CAT or FAT. Enamel demineralization was assessed using the Enamel Decalcification Index (EDI; 0–3). All evaluations were performed by two calibrated, blinded examiners. Statistical analyses were conducted using SPSS (p < 0.05; version 21.0, IBM, Armonk, NY, USA). Posttreatment WSL counts were significantly lower in the maxillary and mandibular anterior regions in the CAT group, with no significant differences in the posterior regions. Although WSLs increased in both groups, the increase was lower after CAT. Total WSL counts were also significantly lower after CAT. In the FAT group, lesion development was more pronounced in the mandibular anterior region. CAT was associated with lower WSL burden and fewer newly developed lesions than FAT, particularly in the anterior regions. However, given the observational design, findings should be interpreted as associations rather than causal effects.
To analyze and compare the differences in orthodontic pain-related behavior between adolescent and adult rats. Twenty 6‑week-old male Sprague–Dawley rats were used to represent adolescent animals, and twenty 8‑month-old male Sprague–Dawley rats were used as adult animals. Ten animals of each group were randomly selected as the control group, and ten as the experimental group. In the experimental groups, each rat was subjected to an orthodontic force. Body weight, food intake weight, and face-grooming activity were recorded, and the open-field and light/dark box tests were conducted on days 1, 3, 7, and 10 after force loading. In adolescent rats, body weight and food intake weight of the experimental group were lower than those of the control group at some time points. The frequency and duration of face grooming in the adolescent rats in the experimental group were greater than those in the control group. On day 1, the distance and frequency that the rats travelled in the center in the open-field test and the frequency that they entered the light box in the light/dark box test in the experimental group were less than in the control group. There was no obvious difference in the indices above between the control and experimental groups of the adult rats. Adolescent and adult rats demonstrated different patterns of orthodontic pain-related behaviors. Compared with adult rats, adolescent rats exhibited more intense and earlier responses to orthodontic pain.
Oral health-related quality of life (OHRQoL) is a patient-reported outcome measure (PROM) that assesses patients’ subjective perception of their oral health status. Previous studies assessing the influence of malocclusions on OHRQoL revealed inconsistent results. This cross-sectional multicenter cohort study aimed to investigate the impact of general orthodontic treatment need (OTN) and of specific anterior malocclusions on OHRQoL and its subdomains in children and adolescents with class II malocclusion. This study included 321 patients with class II malocclusion who required an initial orthodontic diagnosis. OHRQoL was assessed using the German version of the Child Oral Health Impact Profile (COHIP-G19). OTN was evaluated using the Dental Aesthetic Index (DAI) and the Index of Orthodontic Treatment Need (IOTN). To determine specific anterior malocclusions, overjet, overbite, anterior crowding, and anterior spacing were analyzed. Multiple linear regression analysis was performed to examine the effects of OTN and of the anterior malocclusions on OHRQoL and its subdomains, adjusted for demographic confounders (age, gender, and socioeconomic status). High values for OTN were significantly associated with poorer OHRQoL in patients with class II malocclusion. Multiple regression showed a significant effect of overjet and anterior crowding in the upper jaw on OHRQoL. No statistically significant associations were found between OHRQoL and anterior open bite, deep bite, or anterior spacing. High general OTN as well as specific anterior malocclusions such as increased overjet and anterior crowding showed significant associations with OHRQoL in children and adolescents with class II malocclusion. In addition, other unmeasured factors likely play a distinctive role in determining OHRQoL.
This study aimed to evaluate the reliability and agreement of a semi-automated evaluation of the electronic cast–radiograph evaluation (E-CRE) model score, as developed by the American Board of Orthodontics (ABO), compared to manual measurements. A total of 67 study models of patients who had completed orthodontic treatment were available, both as digital scans and as plaster models. Manual and digital evaluations followed the E‑CRE guidelines, assessing six criteria: alignment, marginal ridges, buccolingual inclination, occlusal relationships, overjet and root angulation, which was assessed visually on panoramic radiographs. The digital models were graded using a semi-automated software tool in OnyxCeph3™ Lab (version 3.5, Image Instruments GmbH, Chemnitz, Germany), while the plaster models were scored manually using the ABO measurement gauge. In addition, 20 models were scored manually and digitally by a second observer to assess interobserver reliability. The interobserver reliability was excellent for digital measurements (intraclass correlation coefficient [ICC] 0.94–1.00) and higher compared to those for manual measurements (ICC 0.90–0.97). The reliability between digital and manual measurements was very high, with correlation coefficients ranging from 0.95 to 0.99. However, the digital evaluation produced slightly higher scores for alignment than the manual measurement (mean difference: +0.93). Semi-automated evaluation of ABO E‑CRE scores using OnyxCeph3™ is highly reliable and involves less interpersonal variance than manual grading. However, scores measured digitally were on average 0.79 point higher than those measured manually (scores below 30 are considered as acceptable treatment outcome).
Rehabilitation of compromised masticatory function is a primary goal in orthodontics. Therefore, its assessment is essential for monitoring and validating treatment. However, current methods typically focus on a single feature, such as color homogeneity or texture of the test bolus, thereby, limiting their applicability. This study introduces a new open-source software that facilitates easier comparison of mixing ability metrics and evaluates the feasibility of two novel methods that combine color homogeneity, saturation, brightness, and texture. Bicolor gum samples were chewed 10, 20, and 30 times by 15 participants with class I normocclusion. The boluses were processed using a standardized protocol and photographed under controlled conditions. The state-of-the-art standard deviation of Hue (SDHue) was compared with two new metrics: the Hue–Saturation–Value (HSV) metric, which combines hue, saturation, and brightness, and the Patch Expected Value (PEV) metric, which associates hue and texture. Their ability to discriminate between chewing trials and their intercorrelations were assessed. All three metrics significantly discriminated between the three chewing conditions. The three metrics were correlated with one another across the entire dataset, with the lowest correlation between SDHue and HSV (r = 0.70). SDHue and PEV showed good to strong correlations across the 10×, 20×, and 30× cycle conditions (r = 0.62, 0.92, and 0.76, respectively). This study presents a reproducible methodology and the corresponding software for the objective assessment of masticatory performance. The combination of texture and color homogeneity appears feasible and promising, though further testing with finer mixing resolutions is needed.
The aim of this study is to assess tongue volume (TV), oral cavity proper volume (OCPV), oral cavity volume (OCV), the TV/OCV ratio, pharyngeal airway volume (PAV), nasopharyngeal airway volume (NPAV), and oropharyngeal airway volume (OPAV) in individuals with different sagittal skeletal patterns using cone-beam computed tomography (CBCT), and to explore the interrelationships among these parameters. In addition, this study aimed to enhance the understanding of functional craniofacial anatomy and to support comprehensive planning in both orthodontic and orthognathic treatments. In all, CBCT images of 165 individuals (88 females, 77 males) were retrospectively selected. The mean age was 21.6 ± 4.5 years (range 17–36 years). The individuals were classified into class I, II, and III based on the sagittal skeletal pattern using the ANB angle. The SNA and SNB angles were also measured. To ensure measurement standardization, all CBCT images were reoriented and resampled to a uniform voxel size of 0.32 mm3 using the “Resample scalar volume” module. Measurements of TV, OCPV, OCV, PAV, NPAV, and OPAV were determined using a semi-automatic segmentation method in the 3D Slicer 5.2.2 software (Surgical Planning Lab, Harvard Medical School, Boston, MA, USA), with different thresholds for air (−1000 to −500) and tongue (−500 to +250). Manual corrections and Gaussian smoothing (1 mm) were applied for tongue segmentation. Group comparisons were made with the Kruskal–Wallis test, followed by post hoc pairwise analysis for significant differences. Spearman’s correlation analysis was used to examine relationships between parameters, and the Mann–Whitney U test assessed gender differences (p < 0.05). SNA, SNB, TV, OCV, and NPAV values were significantly higher in males than in the females (p < 0.05). SNB, TV, and OCV were higher in the class III group compared to class II and I (p < 0.05). A strong positive correlation was identified between TV and OCV (r: 0.907; p < 0.001; p < 0.05), while a negative correlation was found between TV and OCPV (r: −0.435; p < 0.001; p < 0.05). In class II patients, the TV and TV/OCV ratio correlated positively with NPAV, while in class III patients, the TV/OCV ratio correlated negatively with PAV and OPAV (p < 0.05). The SNB value showed a positive correlation with TV, OCV, PAV, and OPAV (p < 0.05). Additionally, the SNA value exhibited a positive correlation with TV and a negative correlation with OCPV (p < 0.05). The relationships between the tongue, oral cavity, and upper airway differed by gender, skeletal patterns, and the relative positions of the mandible and maxilla.
The aim of this study was to investigate whether the severity of incisor irregularity is associated with the buccal, palatal/lingual, or normal positions of fully erupted upper or lower permanent canines in three dimensional (3D) digital models. This cross-sectional study included 288 individuals aged 13.2–15.3 years with skeletal class I malocclusion. Incisor irregularity was assessed using Little’s irregularity index (LII), which quantifies the linear displacement of anterior contact points. Canine eruption positions in the upper and lower jaw were classified as normal, buccal or palatal/lingual. All measurements were performed digitally on calibrated 3D intraoral scans. Associations between canine position, irregularity severity, and gender were analyzed using χ2 tests. A priori power analysis was conducted (effect size w = 0.51, α = 0.05, power = 0.95). In the maxilla, normally positioned canines were most frequently associated with 0–3 mm of incisor irregularity (59.6
This study aimed to compare the distorotation of the upper first molars (U6) and the expansion of the upper dental arch achieved using clear aligners (CA), Leaf Expander® (LE; Leone, Sesto Fiorentino, Italy), and rapid maxillary expander (RME), all anchored to the second primary molars. The research was structured as a superiority randomized controlled trial conducted in two academic medical centers in Italy. Participants included children in growth phase presenting transverse maxillary deficiency with intermolar width less than 30 mm, early mixed dentition with fully erupted upper first molars, and a cervical vertebral maturation stage (CVMS) 1 or 2, without systemic diseases or syndromes. Subjects were randomly assigned to one of the three treatment groups: CA, LE, or RME. The main variable measured was the distorotation of U6, with secondary variables including the width between canines, first molars, and second primary molars. In all, 60 subjects were randomized equally into the three groups. Average treatment time was 8 ± 3 months for the LE group and 9 ± 1 months for the RME group (p = 0.089). Mean treatment time for the CA group was 15 months with a standard deviation of 2 months. A significant difference was observed in the number of clinical visits: 6 ± 2 for LE and 8 ± 1 for RME (p < 0.001). The RME group completed the active treatment phase in 10 ± 2 days, which was notably shorter than the 3.5 ± 0.71 months required for the LE group (p < 0.001). Analysis of variance (ANOVA) revealed statistically significant differences among the groups in terms of U6 distorotation (p < 0.05), whereas no significant differences were found for the expansion of the upper arch. Overall molar distorotation was highest in the LE group (11.73°), surpassing the RME group (6.22°), and was similar to the result observed in the CA group (11.89°). Both CA and maxillary expanders fixed to upper primary molars produced comparable levels of dentoalveolar expansion. The spontaneous distorotation of the U6 obtained with LE was similar to the planned distorotation achieved with CA and significantly higher than that observed with RME.
To assess the effects of attachment design and location on derotation of mandibular second premolars through the finite element method. A mandibular model consisting of teeth, periodontal ligament (PDL), trabecular/compact bones, attachment, and clear aligner was created. Tooth 35 was positioned with 30° mesial rotation. Seven treatment scenarios were planned to analyze the derotation movement, i.e., Model 1: no attachment; Model 2: buccal vertical rectangular attachment (VRA); Model 3: buccal beveled VRA (bVRA); Model 4: lingual VRA: Model 5: lingual bVRA; Model 6: buccal and lingual VRAs; and Model 7: buccal and lingual bVRAs. Derotation activation was 1.2° for each aligner. Tooth displacement, aligner deformation, and stresses produced in the PDL and the aligner were analyzed. The highest value for tooth displacement (0.087 mm, 0.51°) was detected in Model 7, while Model 1 exhibited the lowest value (0.067 mm, 0.39°). Model 7 created the least deformation of the clear aligner (0.469 mm) and the highest stresses in the PDL (6.780 MPa) and the clear aligner (101.258 MPa), whereas Model 1 induced the highest deformation of the clear aligner (0.523 mm) and the lowest stresses in the PDL (6.253 MPa) and the clear aligner (62.667 MPa). Greater derotations were observed in models with bVRA than in those with VRA in the same placement and in models with attachments on both surfaces than in those with attachment on one surface. bVRAs placed on both the buccal and lingual surfaces provided the most controlled and predictable derotation movement. Aligner deformation and stresses produced in the PDL and the clear aligner showed biomechanical harmony with the movement.
We explored the association between the 6‑n-propylthiouracil (PROP) taste phenotypes and the incidence and severity of initial caries lesions (ICL) during fixed orthodontic treatment. The participants were a prospective cohort of 44 fixed orthodontic patients (16 males, 28 females, 18.7 ± 5.5 years) classified as non-tasters (n = 19) and tasters (n = 25) based on their bitter taste perception of PROP. The primary outcome was the cumulative incidence (Cin) of ICL at the facial surfaces of the anterior teeth and premolars at 1, 3, 6, 9 and 12 months in treatment. The severity of ICL (Enamel Decalcification Index, EDI) was the secondary outcome. Baseline age, sex, caries status, dietary habits, oral hygiene practice, type of treatment (non-extraction/extraction), oral hygiene, and salivary flow during treatment were the confounders/covariates explored. Non-tasters had a higher relative risk (RR) of a tooth developing ICL than tasters at 9 months (Cin = 8.6 vs 0.6
