BACKGROUND: Mixed dentition analyses are used to determine possible tooth-size and arch-length discrepancies during the transition from primary to permanent dentition. Prediction methods using a probability table or linear regression equation use the sum of the mesiodistal widths of mandibular permanent incisors to predict the mesiodistal width of unerupted permanent teeth. Racial and sexual variations and sexual dimorphism in tooth size have been reported. The objective of this study is to validate Moyer\'s and Tanaka Johnston\'s mixed dentition analyses in a contemporary South Indian population.

BACKGROUND: Contemporary imaging methods and quickly advancing technologies have increased the number of diagnostic tools available in medicine and orthodontics. The current study aimed to determine three-dimensional (3D) space changes that occurred after the extraction of either the maxillary or mandibular primary molars during the mixed dentition period.
METHODS: The present study was a longitudinal split-mouth study with a study group and a control group. The sample consisted of 20 children aged between 6 and 9 years. Clinical examination, radiological analysis, and 3D digital images of the plaster casts were used sequentially to gather all the data. The dental cast measurements recorded were arch width, arch length, hemi-perimeter, dental space at the extraction site, and angulation of the first permanent molar. The children were recalled for follow-up after 9 months, and all dental cast measurements were repeated using nondestructive 3D computed tomography software. For repeated measurements, the test applied was a paired t-test, and for independent samples, the test was a Student\'s t-test.
RESULTS: A significant decrease in arch width (P = 0.001), arch length (P < 0.001), hemi-perimeter (P < 0.001), D-space (P < 0.001), and E-space (P = 0.001) was observed following extraction. A significant increase in angulation measurements was observed (P = 0.001).
CONCLUSIONS: The study revealed a comparative reduction in mandibular arch width, a reduction in arch length in both the maxilla and the mandible, a reduced hemi-perimeter of dental arches, loss of dental extraction space, and a change in angulation of the erupted first permanent molars following premature loss of the primary molar.

OBJECTIVE: To compare vertical and transverse changes in mixed dentition patients treated with the Invisalign First System (IFS) to those treated with a banded hyrax expander with fixed appliances (Hyrax) and control groups, and to assess the efficiency rate of dental arch expansion with IFS.
METHODS: The study included 80 mixed dentition patients, with 40 in each group (IFS and Hyrax) and 40 controls from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection. Skeletal and dental vertical dimension changes and arch width changes between pretreatment (T1) and posttreatment (T2) were evaluated.
RESULTS: Age at T1, time interval (T1-T2), sex, and Angle class did not significantly differ among the groups. Mandibular plane angle changes showed a similar reduction for the control and IFS groups, with no changes in the Hyrax group. However, the differences among the three groups did not reach statistical significance (P = .06). The Hyrax group showed significantly greater expansion in maxillary intermolar width compared to the IFS group, 4.4 vs 2.5 mm, respectively. The efficiency of maxillary expansion using IFS ranged from 52.3% to 76.87%.
CONCLUSIONS: During the mixed dentition stage, no significant changes occurred in vertical dimensions among the control, Hyrax, and IFS groups. Although there was a trend suggesting a greater reduction in mandibular plane angle in the IFS group compared to the Hyrax group, this may not be clinically significant given the less than 1° difference. IFS can be a viable option for addressing mild arch width deficiencies, with a predictable increase in intermolar width of approximately 2.5 mm.

OBJECTIVE: To compare changes in upper arch dimension and molar inclination between Invisalign First (IF) and removable acrylic expander (RE) treatments during the mixed dentition period.
METHODS: Seventeen patients meeting inclusion criteria underwent IF treatment and were age matched with a group that received treatment with a removable acrylic expander (RE). Intercanine width (ICW), intermolar width, arch depth, buccolingual inclination of the first molars (MI), surface area (SA) and volume (VAP) of the anterior palate, and expansion were compared before and after treatment. The predictability of expansion was calculated for the IF group. Analysis of variance and Kruskal-Wallis tests were used to assess differences.
RESULTS: The ICW increased significantly by 2.14 mm in the IF group and 3.49 mm in the RE group, with no significant intergroup difference. Both groups exhibited significant increases in intermolar width (P < .05), except for intermolar distopalatal width in the IF group (P = .246). Mesiobuccal rotation of the first molar was observed with IF treatment. Although SA and VAP increased in both groups, the changes were not significant for the IF group (P > .05). The RE group exhibited significantly higher increases (P < .05), with an SA increase of 34.32 mm2 and VAP increase of 119.15 mm3. MI changes were in the opposite directions. The prediction accuracy of expansion was 70.28% for canines and 34.12% for first molars.
CONCLUSIONS: Both appliances effectively expanded the intercanine region in growing patients. Expansion predictability was lower in first molars than in canines for the IF group. Removable acrylic expanders could be a choice of preference for expansion targeted to the molar region.

OBJECTIVE: To compare the buccal and palatal bone changes of maxillary posterior teeth produced by hybrid hyrax (HH) and conventional hyrax (CH) expanders in growing patients.
METHODS: A sample of 32 patients with posterior crossbites in the late mixed dentition was recruited and randomly allocated into two groups. Group HH was composed of 18 individuals with a mean age of 10.7 years (six female, 12 male) treated with a hybrid expander with two anterior parasagittal miniscrews. Group CH was composed of 14 individuals with a mean age of 11.4 years (six female, eight male) treated with a conventional Hyrax expander. Cone-beam computed tomography (CBCT) exams were obtained before expansion (T1) and after 11 months when the expander was removed (T2). Buccal and palatal bone plate thickness and height of maxillary posterior teeth were measured. Intergroup comparisons were performed using t or Mann-Whitney tests (P < .05).
RESULTS: The CH group showed greater decreases of the buccal bone plate height (mean change: 1.27 mm) at the maxillary first premolars compared to the HH group (mean change: 0.11 mm, P = .001). No intergroup difference was found for changes in the buccal and palatal bone thickness.
CONCLUSIONS: Hybrid expanders showed a tendency to cause less negative impact on the buccal bone plate height of first premolars compared to conventional Hyrax expanders. However, the difference was not clinically significant. Both hybrid and conventional Hyrax expanders are safe for the alveolar bone morphology in the late mixed dentition.

This study had two aims. First, we aimed to investigate the prevalence of ACB, PCB, and oral habits among a group of Albanian children with ASD compared with a group of children without ASD. Second, we aimed to identify the associations of ASD with ACB, PCB, and oral habits. The sample inlcuded 125 children with ASD (91 males, 34 females) from 2 special schools for children with disabilities and 2 daily residential centers in Tirana. The control group included 125 children without ASD. The relationships between categorical variables were evaluated via the chi-square test. To identify the potential risk factors for ASD, we performed binary logistic regression. No statistically significant differences were found for CB or oral habits between the primary and adolescent dentition stages. A comparison of children with ASD with CB and oral habits revealed a significant difference in the prevalence of PCB. Binary logistic regression revealed that ACB, PCB and oral habits were not associated with ASD. CB was more prevalent among children with ASD in the primary and mixed dentition stages. Oral habits were more prevalent in the mixed and adolescent dentition stages. However, ASD is not a risk factor for CB or other oral habits.

Mid-root fractures are rare injuries in young permanent teeth and tend to have poor prognoses. This study presents a case of oblique root fracture of both maxillary immature central incisors in the middle third accompanied by delayed dental visit and severe caries of all primary teeth. After restoring all the primary and permanent teeth that needed stabilization, the coronal fragments were repositioned and stabilized with a flexible splint consisting of orthodontic wire and composite resin. A comprehensive and sequential dental treatment for other oral diseases and oral hygiene instructions were provided. A 16-month follow-up revealed that the two injured young permanent incisors were healed, surrounded by hard tissues and continued to grow both in length of the root and thickness of the root canal wall, with significant improvement in oral hygiene. Based on the outcome of this case, initial stabilization without endodontic therapy could be considered a successful treatment modality for young permanent teeth with oblique root fracture due to the growth of fractured teeth with vital pulp and the maintenance of natural dentition.

OBJECTIVE: In the interpretation of panoramic radiographs (PRs), the identification and numbering of teeth is an important part of the correct diagnosis. This study evaluates the effectiveness of YOLO-v5 in the automatic detection, segmentation, and numbering of deciduous and permanent teeth in mixed dentition pediatric patients based on PRs.
METHODS: A total of 3854 mixed pediatric patients PRs were labelled for deciduous and permanent teeth using the CranioCatch labeling program. The dataset was divided into three subsets: training (n = 3093, 80% of the total), validation (n = 387, 10% of the total) and test (n = 385, 10% of the total). An artificial intelligence (AI) algorithm using YOLO-v5 models were developed.
RESULTS: The sensitivity, precision, F-1 score, and mean average precision-0.5 (mAP-0.5) values were 0.99, 0.99, 0.99, and 0.98 respectively, to teeth detection. The sensitivity, precision, F-1 score, and mAP-0.5 values were 0.98, 0.98, 0.98, and 0.98, respectively, to teeth segmentation.
CONCLUSIONS: YOLO-v5 based models can have the potential to detect and enable the accurate segmentation of deciduous and permanent teeth using PRs of pediatric patients with mixed dentition.

In orthodontic treatment of patients during the mixed dentition period, arch expansion and opening deep overbite are one of the objectives to achieve proper alignment of the teeth and correction of sagittal and vertical discrepancies. However, the expected outcomes of most therapeutic regimens are not clear, making it impossible to standardize early treatment effects. Therefore, this study was designed to evaluate the impact of the Invisalign® First System on the dental arch circumference and incisor inclination in patients during the mixed dentition period. A total of 21 children during the mixed dentition period (10 females and 11 males, with an average age of 8.76 years) were included in this study. The patients received non-extraction treatment through Invisalign® First System clear aligners, and no other auxiliary devices were used except Invisalign® accessories. Subsequently, the cooperation degree of patients during treatment and the oral measurement parameters at the beginning (T1) and the end (T2) of treatment were collected. All patients showed moderate/good cooperation degree during treatment. Besides, horizontal width of the maxillary first molar increased significantly; the designed arch expansion was 4.1 mm (±1.4 mm), while the actual arch expansion was 3.0 mm (±1.7 mm). Furthermore, the torque expression rate of upper anterior teeth reached 56.53%. Invisalign® First System clear aligners can effectively correct the teeth of patients during the mixed dentition period, widen the circumference of dental arch, and control the torque of incisors.

OBJECTIVE: To investigate the relationship between oral muscle pressure and malocclusion in the mixed dentition.
METHODS: Maximum tongue, lip and cheek pressure was measured using the Iowa Oral Performance Instrument (IOPI) in 3 patient cohorts: patients with (1) posterior crossbite, (2) class II relationship and (3) a control group of patients without malocclusion. Linear models were used to compare the mean differences in muscle pressure between groups, with correction for age and gender. The imbalance between lips and tongue and between lips and cheeks was calculated by the Delta z-scores of each group.
RESULTS: A total of 146 participants were included, 46 (mean age 8.71±0.85), 41 (mean age 11.74±1.17) and 35 (mean age 10.71±1.92) in groups 1, 2 and 3 respectively. Patients with malocclusion showed significantly higher lip and lower cheek pressure and imbalance favouring the lips over the tongue compared to controls. Class II,1 patients showed significantly higher tongue pressure than Class II,2. No differences were found in muscle pressure or imbalance between crossbite and Class II nor between crossbite types.
CONCLUSIONS: These findings suggest that oral muscle pressure may be associated with malocclusion. This highlights the importance of functional diagnosis and its implications on the prevention and treatment of malocclusion, as well as on orthodontic stability.