YOLO-V5 based deep learning approach for tooth detection and segmentation on pediatric panoramic radiographs in mixed dentition.

OBJECTIVES: 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.

Long-term stability of posterior crossbite correction, treated in the mixed or permanent dentition of growing children: A systematic review and meta-analysis.

When treating posterior crossbite, the primary goal is to achieve long-term crossbite correction. The majority of studies however focus on relapse of the increase in the transverse dimension, but not relapse of the crossbite itself, which is an essential outcome. The aim of the present study was to determine long-term stability (2 years minimum post-treatment) of posterior crossbite correction, treated in mixed or early permanent dentitions of growing children. Following registration in PROSPERO (CRD42022348858), an electronic literature search including PubMed, Embase, Web of Science, the Cochrane Library, and a manual search were conducted up to January 2023, to identify longitudinal studies looking into the long-term stability of crossbite correction in growing children. Data extraction and risk of bias assessment were carried out, and subsequently, a random-effects meta-analyses models were used to calculate estimates for relapse of the crossbite and relapse at the transverse level. Twenty-two studies were included, of varying designs and quality, representing 1076 treated patients, with different expansion appliances and protocols. Meta-analysis results showed that 19.5% (95% CI: 15%; 25%) of patients present with relapse of posterior crossbite at long-term follow-up. At the transverse level, 19.3% of the total expansion (including overexpansion) relapsed (95% CI: 13%; 27%) regardless of whether there a was relapse of the crossbite itself. Data from existing studies, with a moderate level of evidence, indicate that the long-term stability of posterior crossbite correction in growing children is unfavourable in roughly 1 in 5 growing children, with crossbite relapse long-term. On average, 19% of the maxillary expansion performed (including overexpansion) relapses long-term, which may occur in cases with or without relapse of the crossbite.

Correlation between oral muscle pressure and malocclusion in mixed dentition: a cross-sectional study.

OBJECTIVE: To investigate the relationship between oral muscle pressure and malocclusion in the mixed dentition. MATERIALS AND 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. CONCLUSION AND CLINICAL RELEVANCE: 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.

Changes in the swallowing pattern and tongue posture during the transition from deciduous to mixed dentition-a longitudinal ultrasonography study.

BACKGROUND: Given the importance that swallowing pattern and tongue posture might have in the aetiology of malocclusion, it appears important to be aware of the physiological changes of tongue function and its posture. OBJECTIVES: The study aimed to assess changes of the swallowing pattern and tongue posture during the transition from the deciduous to mixed dentition and the association between them. MATERIALS AND METHODS: The study included 57 subjects aged 5.87 ±â€…0.5 with normal occlusion, orofacial functions, no history of trauma, or orthodontic treatment. Ultrasonography was used for the assessment of tongue posture and swallowing pattern, where the spontaneous act of swallowing was recorded. To evaluate the possible effect of incisors' eruption, the swallowing pattern and tongue posture ultrasonograms were compared at the deciduous (DD), early mixed (EMD), and intermediate mixed (IMD) timepoints. RESULTS: A significant association between the swallowing pattern and tongue posture at the DD and IMD timepoint was found. Moreover, the visceral swallowing pattern decreases with age (odds ratio [OR] = 0.777), as well as with a prolonged phase IIa (OR = 0.071), while it increases when the tongue is postured on the mouth floor (OR = 5.020). LIMITATIONS: The young age of the investigated subjects, direct contact of the probe, and the determination of the rest phase of the tongue were considered limitations. CONCLUSIONS: No statistically significant changes in swallowing pattern and tongue posture occurred during the transition period; however, a significant association between the swallowing pattern and tongue posture among subjects with normal occlusion, regardless of the dentition phase was detected.

Posterior crossbite corrections in the early mixed dentition with quad helix or rapid maxillary expander: a cost-effectiveness analysis of a randomized controlled trial.

BACKGROUND: Unilateral posterior crossbite is a common malocclusion, and early treatment is recommended to enable normal growth. There are several possibilities regarding choice of appliances used for correcting this malocclusion; however, when treatment is financed by public funds the decision needs to be based not only on the effects but also on the effect in relation to the costs. OBJECTIVES: The aim was to perform a cost-effectiveness analysis comparing quad helix (QH) and rapid maxillary expanders (RME; hyrax-type) in children in the early mixed dentition. MATERIAL AND METHODS: Seventy-two patients were randomized to treatment with either QH or RME, at two different centres. Data were collected from the patient's medical records regarding success rate, number of visits, total treatment time, emergency visits, and so forth, together with answers from patient questionnaires concerning absence from school and use of analgesics. A cost-effectiveness analysis with both an intention-to-treat (ITT) and a per-protocol approach was performed, as well as a deterministic sensitivity analysis. RESULTS: The success rate, one year after the completion of the expansion, was equal between groups according to the ITT approach. From a healthcare perspective, the mean cost difference between RME and QH was €32.05 in favour of QH (P = 0.583; NS). From a societal perspective, the mean cost difference was €32.61 in favour of QH (P = 0.742; NS). The total appliance cost alone was higher in the RME group €202.67 resp. €155.58 in the QH group (P = 0.001). The probability of RME having a higher cost was 71% from a healthcare perspective and 62.7% from a societal perspective. The total treatment time was 97 days longer in the QH group. In the deterministic sensitivity analysis, when using a higher valuation of the children's educational loss, the QH becomes €58 more costly than the RME. There was a statistically significant difference in chair time and visits between centres (P < 0.001). CONCLUSION: The difference in costs between RME and QH is not statistically significant, however, there is a slightly higher probability that RME is more expensive than QH with a mean cost of an additional €32 per patient from a healthcare perspective. Different work procedures at different centres indicate that logistics around the patient's treatment is a more important aspect than appliance used to decrease the number of visits and save chair time and thereby also costs.

Comparison of the different methods of width estimation in unerupted canine and premolars.

BACKGROUND: There are different methods for determining the required space for unerupted teeth. However, the accuracy of these techniques varies depending on ethnic differences. Therefore, the current study was performed to compare the accuracy of four methods for estimating the mesiodistal width of unerupted canines and premolars in a population of northern Iran. METHODS: The present cross-sectional study was conducted on 50 pairs of dental casts of patients aged 12-24 years old. The mesiodistal width of the teeth was measured with a digital caliper by two observers (ICC < 0.9), and the mean value was recorded. The space required for eruption of canines and premolars was obtained by the Tanaka-Johnson formula and the Moyers tables and compared with the actual value by paired t test. RESULTS: The Tanaka-Johnson formula had overestimation in the maxilla and mandible, which was statistically significant (p < 0.001). The values obtained from the Moyers tables in different confidence levels were not accurate. However, the 65% level for the mandible had almost no difference from the actual value (P = 0.996 and r2 = 0.503). Furthermore, linear regression was obtained based on the total mesiodistal width of the maxillary first molar and mandibular central incisor (maxilla: Yx= 0.613X + 2.23 and mandible: Ym= 0.618X + 1.6) and the total mesiodistal width of the mandibular first molar and maxillary central incisor in each jaw (maxilla: Yx = 0.424X + 5.021 and mandible: Ym = 0.447X + 3.631). CONCLUSION: The Tanaka-Johnson method was overestimated in the population of northern Iran. The 85% and 75% confidence levels of the Moyers table have the best clinical results for the maxilla and mandible, respectively. Regression based on maxillary first molars and mandibular central incisors has better results.

Predictability of expansion movements performed by clear aligners in mixed dentition in both arches: a retrospective study on digital casts.

BACKGROUND: to evaluate the predictability of expansion achieved in patients in early mixed dentition treated with Clear Aligners (CA), analyzing the efficiency of the expansion at the end of the first set of aligners and at the end of the therapy in the upper and lower arch. METHODS: 36 patients (20 F, 16 M; mean age 8.3 ± 1.5 years) were selected retrospectively from the Department of Orthodontics of the Hospital of Rome "Tor Vergata". All subjects were treated with CA with no other auxiliaries than attachments. For each patient a standardized sequential expansion protocol was planned for both arches. Digital dental casts were created at three observation periods from an intraoral scanner: prior to treatment (T0), at the end of the first set of aligners (T1), at the end of treatment (T2). The 3D models in planned position determined by the first Clincheck (CC) were obtained for comparison with T1 and T2. Six linear transversal measurements were used to evaluate the dimensional changes and the predictability of expansion movements, comparing T1-CC and T2-CC. RESULTS: a statistically significant increase within the pre-treatment and the final outcomes for all the variables examined was found. In the upper arch, the greatest level of predictability was detected at the level of the first (46.44%) and second deciduous molar width (44.95%) at T1. The analysis of T2-CC changes showed a significant increase in the percentage of predictability of expansion at the level of the first permanent molars, at mesial (54.86%) and distal (58.92%) width. In the lower arch, a higher percentage of predictability than the upper arch was reported at T1-CC and T2-CC, with the greatest values at the level of second (T1-CC: 48.70%; T2-CC: 75.32%) and first deciduous molar width (T1-CC: 45.71%; T2-CC: 72.75%). CONCLUSIONS: CA can induce significant transversal increments. The predictability of expansion is variable, but it did not exceed the 50% during the first set of aligners. It was necessary to apply refinement set to achieve a good predictability for expansion of about 70%. The expansion in the lower arch was observed to be more predictable than in the upper arch.

The predictability of arch expansion with the Invisalign First system in children with mixed dentition: a retrospective study.

This study aimed to quantify the predictability of arch expansion in children with early mixed dentition treated with the Invisalign First® system and evaluate the clinical factors for the predictability of arch expansion. Pretreatment, predicted and posttreatment digital models from Invisalign's ClinCheck® software were obtained for 90 children with mean (standard deviation) age of 8.42 (0.93) who planned arch expansion. Arch width measurements were collected using Invisalign's arch width table. The predictability of expansion was calculated by comparing the amount of expansion achieved with the predicted expansion. Linear regression analysis was used to evaluate clinical factors associated with predictability of expansion. The predictability of the expansion of the maxillary teeth was as follows: 71.1% primary canines (n = 55), 67.5% first primary molars (n = 46), 65.2% second primary molars (n = 79), and 53.4% first permanent molars (n = 90); the predictability of the expansion of the mandibular teeth was 81.1% primary canines (n = 31), 81.2% first primary molars (n = 51), 77.8% second primary molars (n = 80), and 69.4% first permanent molars (n = 90). The predictability of arch expansion was significantly higher in the mandibular arch compared to the maxillary arch and significantly lower in the permanent first molar than in the other primary teeth. Predictability decreased significantly as the amount of predicted expansion per aligner increased in the upper and lower permanent first molars, primary second molars, and upper primary canines. Predictability significantly increased when buccal or palatal attachments were placed on the bilateral side compared to cases without attachment at the upper permanent first and primary second molars. The predictability of arch expansion using the Invisalign First® system varies according to arch and tooth type. The amount of predicted expansion per aligner and the number of attachments to the maxillary teeth are potential clinical factors that can affect the predictability of expansion.

Influence of the practice of sports, sleep disorders, and habits on probable sleep bruxism in children with mixed dentition.

OBJECTIVE: Investigate the association between sleep disorders and probable sleep bruxism (SB) in children eight to ten years of age. METHODS: A cross-sectional study was conducted with 739 schoolchildren in Brazil. Parents/guardians answered a sociodemographic questionnaire, the sleep disturbance scale for children, and the Circadian Energy Scale. Parafunctional habits were evaluated using the Nordic Orofacial Test-Screening. Multivariate logistic regression was performed (α = 5%), and a directed acyclic graph was used in the statistical model. RESULTS: The prevalence of probable SB was 9.1% and 58.6% of the children had sleep disorders. In the final model, having unmarried parents/guardians (OR = 1.98; 95% CI: 1.07-3.65), exhibiting parafunctional habits (OR = 2.02; CI: 1.01-4.06), not practicing sports (OR = 1.92; CI: 1.04-3.54), sleep-wake transition disorders (SWTD) (OR = 2.01; 95%CI: 1.12-3.62), and excessive daytime sleepiness (EDS) (OR = 2.17; 95%CI: 1.11-4.29) were significant associated with probable SB. CONCLUSION: The occurrence of probable sleep bruxism was influenced by the marital status of the parents/guardians, parafunctional habits, the non-practice of sports, and sleep disturbance (SWTD and EDS). This research contributes to the planning of public policies that include educational regimens at school to prevent sleep disorders and favor the reduction in sleep bruxism prevalence.

Should midline diastema in mixed dentition be an aesthetic concern?

BACKGROUND: Mixed dentition determines an important period of occlusion development in childhood. OBJECTIVE: This study aimed to evaluate the aesthetic impact of the midline diastema cut-off point in mixed dentition. DESIGN: A cross-sectional study was performed with 257 children aged 8-10 years in late mixed dentition, with midline diastema of 1-5 mm and normal maxillary overjet. Orthodontic Aesthetic Subjective Impact Score determined the aesthetic impact of the midline diastema. Four quartiles of diastema measurements and impact scores were considered as cut-off points. Receiver Operating Characteristic curves were constructed, and the distances representing the distances to the ideal point were calculated. The Yuden index determined the efficiency of measuring the diastema to assess the aesthetic impact. The Kruskal-Wallis test compared the groups of participants classified according to the diastema cut-off by the sample quartile regarding the impact score. The analyses were performed with a significance level of 5%. RESULTS: There was no significant difference between the four groups of measurement quartiles of the diastema regarding the aesthetic impact (P > .05). CONCLUSIONS: The perception of dental aesthetics in mixed dentition children was not affected by the midline diastema, regardless of the cut-off point.

What is the Effectiveness of Premaxilla Surgical Repositioning and its Stabilization Methods in Mixed Dentition Patients With Bilateral Cleft Lip and Palate?

OBJECTIVE: Verify the effectiveness of surgical repositioning of the premaxilla and its stabilization methods in patients with bilateral cleft lip and palate during mixed dentition. DESIGN: Systematic review. MATERIAL AND METHODS: The search was conducted in 7 databases (eg, Medline via PubMed; Scopus; Central Cochrane; LILACS; Embase, Web of Science; and Sigle via OpenGrey until August 2021), using the descriptors "premaxilla", "cleft Palate", and "bone transplantation". INCLUSION CRITERIA: Clinical trials and observational studies that have patients with bilateral cleft who had a need for superior/posterior repositioning of the premaxilla on mixed dentition; Studies in any language was evaluted whitout time restriction of publication. RESULTS: From 5572 records, 6 studies were included in the review with a total sample of 212 patients. Regarding the type of stabilization used in the premaxilla, the hybrid method (rigid and complementary semi-rigid stabilization) predominated, being observed in 184 patients (86.8%). A total of 17 failures were identified related to the surgical repositioning of the premaxilla, corresponding to 8% of the total number of surgeries. A meta-analysis of prevalence was performed, only with the retrospective studies. It was observed that the effectiveness rate of premaxilla repositioning was 92%, with a CI between 0.04 and 0.13, with all included studies showing a similar failure rate (0.08-0.09). The included studies also showed great homogeneity in this analysis (I2 = 0%; P = .75). CONCLUSION: Although there are several alternatives and techniques for repositioning and stabilizing the premaxilla, the statistical result did not differ between the different techniques.

Clear aligner therapy in the mixed dentition: Indications and practitioner perspectives.

INTRODUCTION: This study evaluated current trends and perspectives among orthodontists regarding clear aligner therapy in the mixed dentition (CAMD), including insights into perceived indications, compliance, oral hygiene, and other factors. METHODS: An original, 22-item survey was mailed to a randomized, nationally representative sample of practicing orthodontists (n = 800) and a specific, randomized subsample of high-aligner-prescribing orthodontists (n = 200). Questions assessed respondents' demographic information, experience with clear aligner therapy, and perceived advantages and disadvantages of CAMD compared with fixed appliances (FAs). Responses were compared using McNemar's chi-square and paired t tests to assess CAMD vs FAs. RESULTS: One thousand orthodontists were surveyed, and 181 (18.1%) responded over 12 weeks. CAMD use was less common than mixed dentition FAs, but most respondents predicted an increase in their future CAMD use (57.9%). Among respondents using CAMD, the number of patients with mixed dentition treated with clear aligners was significantly lower than the number of total patients with clear aligners (23.7% vs 43.8%; P <0.0001). Fewer respondents considered skeletal expansion, growth modification, sagittal correction, and habit cessation feasible indications for CAMD compared with FAs (P <0.0001). Perceived compliance was similar for CAMD and FAs (P = 0.5841), but perceived oral hygiene was significantly better with CAMD (P <0.0001). CONCLUSIONS: CAMD is an increasingly common treatment modality for children. Most surveyed orthodontists reported limited indications for CAMD compared with FAs but perceived noticeable benefits for oral hygiene with CAMD.

Dentoskeletal effects of rapid maxillary expander therapy in early mixed dentition patients with different vertical growing patterns without posterior crossbite: A retrospective study.

INTRODUCTION: This study aimed to analyze the variation of dentoskeletal effects after rapid maxillary expander therapy in subjects with different vertical growth patterns. METHODS: The study sample consisted of 94 patients (32 males, 62 females; mean age 8.9 ± 1.5 years) treated with rapid maxillary expander (RME) anchored on first permanent molars. For each subject, lateral cephalograms and maxillary digital dental casts were available before RME, immediately after appliance removal, and 1 year after appliance removal. All the subjects were divided into 3 groups according to their vertical facial patterns (low-angle, normal-angle, and high-angle). Cephalometric analysis was conducted on lateral cephalograms. The virtual 3-dimensional models were used to analyze the torque of the first permanent molars and intercanine and intermolar width. The differences between the vertical facial subgroups were contrasted by analysis of variance multicomparison test (P <0.05). RESULTS: In the short-term (from before to immediately after RME removal), high-angle subjects showed a mandibular clockwise rotation compared with other groups. No significant long-term vertical and sagittal skeletal changes (from before to 1 year after RME removal) were found between the groups. A greater increase in maxillary molar torque was observed in high-angle subjects than in the other groups. The low-angle patients showed a greater increase in the intercanine diameter. CONCLUSIONS: Hyperdivergent subjects showed increased buccal tipping of the anchor molars after the expansion. Hypodivergent and normodivergent subjects showed lower buccal tipping after the expansion and an increased expansion effect in the anterior region.

Three-dimensional analysis of root changes after orthodontic treatment for patients at different stages of root development.

INTRODUCTION: We investigated changes in the roots of maxillary incisors at different stages of root development after fixed-appliance treatment using cone-beam computed tomography. METHODS: Data from 52 subjects receiving fixed-appliance treatment were collected retrospectively. The subjects were divided into 3 groups: mixed dentition group (aged 7-10 years; root development stage: Nolla eighth-10th; n = 16), early permanent dentition group (aged 12-18 years; root development stage: Nolla 10th; n = 20), and adult group (aged 18-35 years; root development stage: Nolla 10th; n = 16). Changes in root lengths and volume of the maxillary central incisors were measured using pretreatment and posttreatment cone-beam computed tomography. RESULTS: The root lengths and volumes of maxillary central incisors in the mixed dentition group significantly increased after orthodontic treatment (P >0.05). No significant differences were found when comparing the final root length and volume of the mixed dentition group with the pretreatment maxillary incisor values of the early permanent dentition group (P >0.05). The early permanent dentition group showed a significant decrease in root length (P <0.05), and both the root length and volume of the adult group significantly decreased after treatment (P <0.05). The differences in root length and volume reduction between the 2 groups were not significant (P >0.05). CONCLUSIONS: Orthodontic treatment had no significant negative impact on the continued root development of incomplete roots with two-thirds root formation. Both the early permanent dentition and adult groups exhibited root resorption after orthodontic treatment. It seemed age was not a factor that resulted in significant root resorption during routine orthodontic leveling and alignment treatment once the roots were fully developed.

Spontaneous correction and new development of posterior crossbite from the deciduous to the mixed dentition.

AIM: To determine (a) the prevalence of spontaneous correction of posterior crossbites from the deciduous to the mixed dentition and (b) the development of new posterior crossbite cases during the eruption of the first permanent molars, in orthodontically untreated children. MATERIALS AND METHODS: A cohort of pupils aged 4-12 years participated in annual dental screenings, from 2001 to 2019. Data were collected prospectively but examined retrospectively. Children were selected who had been initially screened in their deciduous dentition and on at least one consecutive year, presenting with a posterior crossbite in the deciduous or mixed dentition. Those with a posterior crossbite in the deciduous dentition were evaluated to see whether the crossbite persisted in the mixed dentition, and vice versa. RESULTS: Of the 2571 children participating in the annual dental screenings, 1076 children were in the deciduous dentition at their first screening appointment, with 693 having attended at least two screening appointments. Of these 693 children, 70 had a posterior crossbite in the deciduous dentition (10.1%). The crossbite persisted in the mixed dentition in only 16 out of these 70 children. Twenty-six out of the 623 children who did not have a posterior crossbite in the deciduous dentition developed one in the mixed dentition. LIMITATIONS: The retrospective data collection, multiple examiners carrying out the dental screenings, and the absence of data on para-functions and oral habits were some of the limitations of the present study. CONCLUSIONS: In the present sample, 1 in 10 children have a posterior crossbite in the deciduous dentition, which is however autocorrected in about three-quarters of cases. On the other hand, 4% of children developed a new crossbite in the mixed dentition. It may thus be reasonable in cases with posterior crossbite in the deciduous dentition to wait for the first permanent molars to erupt before initiating treatment.

Self-correction of posterior crossbite in childhood: a systematic review of long-term follow-up studies.

BACKGROUND: The concept that posterior crossbite is not self-correcting has been controversial in the literature. OBJECTIVE: To evaluate the incidence of self-correction of crossbite in different stages of dentition in childhood. SEARCH METHODS AND SELECTION CRITERIA: A bibliographic search using the acronym PECOS was performed in five databases and in partial grey literature. Studies evaluating children with posterior crossbite in the deciduous or mixed dentition at initial examination and followed for at least 3 years were included. DATA COLLECTION AND ANALYSIS: The data extraction of the studies included presents information on authorship, clinical characteristics, main results, and conclusions. The risk of bias in the studies was evaluated through the Joanna Briggs Institute tool. The certainty of the evidence was assessed using the GRADE tool. RESULTS: Among the 3045 references identified, seven cohort studies met the eligibility criteria. The studies evaluated patients in transition from deciduous to mixed, mixed to permanent, and deciduous to mixed dentition. Two studies had a low risk of bias, three had a moderate risk, and two had a high risk of bias. The results showed posterior crossbite self-correction frequencies ranging from 12.2 to 77.1% during the transition from primary to mixed dentition, approximately 16% from mixed to permanent dentition, and a range from 20 to 82.8% from deciduous to permanent dentition. The level of certainty of the evidence generated ranged from very low to moderate. LIMITATIONS: The observational design of the studies, without adequate control for confounding factors, and non-classification of the samples considering the types or the severity of the posterior crossbite. CONCLUSION: The self-correction of posterior crossbite in childhood is possible. However, the results of this research do not allow to affirm how often the self-correction of posterior crossbite can occur. New studies that assess factors associated with the occurrence of self-correction of this malocclusion, including oral habits, may increase the certainty of the evidence. REGISTRATION: PROSPERO CRD42022311935.

Mandibular second premolar distoangulation: a longitudinal follow-up from the mixed to the permanent dentition.

OBJECTIVE: The aim of this study was to assess the frequency of mandibular second premolar (MnP2) distoangulation among orthodontic patients and the angular changes after a longitudinal follow-up. METHODS: The sample was collected from the orthodontic records of 865 patients. The distoangulation group was composed of 42 patients (mean age 9.29 ±â€…1.24 years, 16 male, 26 female) with distoangulation of MnP2. The control group was composed of 32 patients (mean age 9.38 ±â€…1.10 years, 15 male, and 17 female) without distoangulation of MnP2. Panoramic radiographs taken in the mixed (T1) and the early permanent dentition (T2) were analyzed in both groups. Longitudinal angular changes (distal angle θ and premolar-molar angle γ), degree of root formation, second premolar depth, and prevalence of associated dental anomalies were analyzed. Intergroup comparison was performed with Mann-Whitney, t-tests, and chi-square tests (P < 0.05). RESULTS: The prevalence of MnP2 distoangulation in the mixed dentition was 4.85%. The distoangulation group showed a smaller initial distal angle (59.34o ±â€…8.41) when compared to control group (79.88o ±â€…7.60). The spontaneous eruption of the MnP2 with distoangulation was observed in 76.57% of the sample. MnP2 distoangulation was significantly associated with agenesis of its antimere, small maxillary lateral incisors, and deciduous molar infraocclusion. LIMITATIONS: Severe cases of MnP2 distoangulation were absent in this study. CONCLUSIONS: The frequency of MnP2 distoangulation among orthodontic patients was 4.85%. Mild to moderate distoangulated Mnp2 spontaneously uprighted from the mixed to the permanent dentition. Small lateral incisors, second premolar agenesis, and infraocclusion of deciduous molar were frequently found in cases with MnP2 distoangulation.

Treatment effects after maxillary expansion using invisalign first system vs. acrylic splint expander in mixed dentition: a prospective cohort study.

BACKGROUND: Invisalign First System (First) is a new type of orthodontic appliance for maxillary arch expansion in mixed dentition children. Till now, few studies have evaluated the expansion effects of First versus other appliances. What's more, most studies of arch expansion did not include a natural group to rule out growth effects. This prospective cohort study aimed to evaluate the dental and dentoalveolar effects using First or acrylic splint rapid maxillary expander (RME) in adolescents excluding growth factors. MATERIALS AND METHODS: After screening by strict inclusion criteria and propensity score matching (PSM), fifty-one patients were included: First group (n = 17), RME group (n = 17), and natural growth (NG) group (n = 17). Nine indicators including dental arch width, dentoalveolar arch width, and inclination of the molars were measured on digital dental casts at baseline (T0) and six-month follow-up (T1). Paired t-tests were used for intra-group results, and two-sample independent t-tests were used for inter-group comparisons. RESULTS: There was no significant increase in all indicators within six months in the NG group (p > 0.05). In the First group and RME group, all width indicators were significantly increased after treatment (p < 0.05). The RME group exhibited greater expansion than the First group in intercanine width, first interpremolar width, second interdeciduous molar width, first intermolar width, arch perimeter, intercanine dentoalveolar width, intermolar dentoalveolar width, and inclination of the molars (p < 0.05). Whereas, there was no significant difference in arch depth between the two treated groups. CONCLUSIONS: Both First and RME can expand the maxillary arch in mixed dentition. In case of mild to moderate maxillary transverse deficiency (MTD), Invisalign First System could be a reasonable option. RME shows significant better efficiency of dental arch expansion than First, recommended for patients with severe MTD. TRIAL REGISTRATION: This prospective study was registered on ClinicalTrials.gov (01/02/2022, registration number: ChiCTR2200056220). The trial was approved by the Ethical Committee of the Hunan Xiangya Stomatological Hospital Central South University (20,200,088), and informed consent was obtained from all subjects and their legal guardian(s).

Management Of Ectopic Eruption Of Bilateral Mandibular First Permanent Molars: A Case Report And Literature Review.

Ectopic eruption of the first permanent molars is a local eruption disturbance. The frequency of ectopically erupted first permanent molars is predominant in boys and primarily affects the maxilla. Interceptive treatment for irreversible ectopic eruptions should be initiated early to prevent space loss and the impaction of the second premolars. Herein, we report the case of a six-year-old girl with irreversible ectopic eruption of the bilateral mandibular first permanent molarstreated with a modified lingual arch. The mandibular first permanent molars were successfully distalised after six months of treatment, and one year of follow-up showed a satisfactory outcome. The modified lingual arch satisfies not only the clinical aspects of treatment but also the patient's well-being. However, the lingual arch may disturb tooth eruption in the mixed dentition stage.

Assessment of dental arch forms in a sample of children.

In this study, we investigated dental arch forms in a representative sample of children with mixed dentition. Twenty-four pairs of study models, belonging to twenty-four youngsters (twelve boys and twelve girls aged 8 to 9 years) with acceptable occlusion, were scanned and assessed by Ortho analyzer software. Three transversal and three vertical measurements were acquired to evaluate the lengths and widths of dental arches, and the ratios between these measurements were standardized. Next, the mean standardized parameters were used to define the dental arch form. Unpaired t-tests were used to analyze gender differences for all measures. Subsequently, frequencies and percentages were determined for each arch shape in both jaws and genders, and Pearson's Chi-squared test was used to evaluate differences between genders. Males exhibited higher mean values for all measurements, but without statistical significance. The most prevalent dental arch was the mid form (83.3%) for both jaws and genders.