Accuracy and tracing time of cephalometric analyses on a tablet or desktop computer : A prospective study.

BACKGROUND: This prospective study aimed to evaluate the influence of the computer type (tablet or desktop) on accuracy and tracing time of cephalometric analyses. METHODS: Dental students used a web-based application specifically developed for this purpose to perform cephalometric analyses on tablet and desktop computers. Landmark locations and timestamps were exported to measure the accuracy, successful detection rate and tracing time. Reference landmarks were established by six experienced orthodontists. Statistical analysis included reliability assessment, descriptive statistics, and linear mixed effect models. RESULTS: Over a period of 8 semesters a total of 277 cephalometric analyses by 161 students were included. The interrater reliability of the orthodontists establishing the reference coordinates was excellent (ICC > 0.9). For the students, the mean landmark deviation was 2.05 mm and the successful detection rate for the clinically acceptable threshold of 2 mm suggested in the literature was 68.6%, with large variations among landmarks. No effect of the computer type on accuracy and tracing time of the cephalometric analyses could be found. CONCLUSION: The use of tablet computers for cephalometric analyses can be recommended.

A systematic review: facial, dental and orthodontic findings and orofacial diagnostics in patients with FASD.

Background: The fetal alcohol spectrum disorder is a group of developmental disorders caused by maternal alcohol consumption. Patients with fetal alcohol syndrome show abnormal orofacial features. This review presents an overview over the facial, oral, dental or orthodontic findings and diagnostic tools concerning these features. Methods: For this systematic review Cochrane, Medline and Embase databases were considered and the review was performed according to the PRISMA checklist. Two independent reviewers evaluated all studies and recorded results in a summary of findings table. Risk of bias was analyzed via Quadas-2 checklist. Results: 61 studies were eligible for inclusion. All included studies were clinical studies. Methods and results of the studies were not comparable, guidelines or methods for the detection of FASD varied across studies. Facial features most often measured or found as distinguishing parameter were: palpebral fissure length, interpupillary or innercanthal distance, philtrum, upper lip, midfacial hypoplasia or head circumference. Conclusions: This review shows that to date a multitude of heterogeneous guidelines exists for the diagnosis of FASD. Uniform, objective diagnostic criteria and parameters for the orofacial region in FASD diagnosis are needed. A bio database with values and parameters for different ethnicities and age groups should be made available for diagnosis.

The Position of the Virtual Hinge Axis in Relation to the Maxilla in Digital Orthognathic Surgery Planning-A k-Means Cluster Analysis.

The aim of this study was to investigate a possible relation between skeletal phenotypes and virtual mounting data in orthognathic surgery patients. A retrospective cohort study including 323 female (26.1 ± 8.7 years) and 191 male (27.9 ± 8.3 years) orthognathic surgery patients was conducted. A k-means cluster analysis was performed on the mounting parameters: the angle α between the upper occlusal plane (uOP) and the axis orbital plane (AOP); the perpendicular distance (AxV) from the uOP to the hinge axis; and the horizontal length (AxH) of the uOP from upper incisor edge to AxV, with subsequent statistical analysis of related cepalometric values. Three clusters of mounting data were identified, representing three skeletal phenotypes: (1) balanced face with marginal skeletal class II or III and α=8∘, AxV = 36 mm and AxH = 99 mm; (2) vertical face with skeletal class II and α=11∘, AxV = 27 mm and AxH = 88 mm; (3) horizontal face with class III and α=2∘, AxV = 36 mm and AxH = 86 mm. The obtained data on the position of the hinge axis can be applied to any digital planning in orthognathic surgery using CBCT or a virtual articulator, provided that the case can be clearly assigned to one of the calculated clusters.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-Tipping or Translation in Posterior Crossbite Correction?

The aim of this study was to investigate buccolingual tooth movements (tipping/translation) in surgical and nonsurgical posterior crossbite correction. A total of 43 patients (f/m 19/24; mean age 27.6 ± 9.5 years) treated with surgically assisted rapid palatal expansion (SARPE) and 38 patients (f/m 25/13; mean age 30.4 ± 12.9 years) treated with dentoalveolar compensation using completely customized lingual appliances (DC-CCLA) were retrospectively included. Inclination was measured on digital models at canines (C), second premolars (P2), first molars (M1), and second molars (M2) before (T0) and after (T1) crossbite correction. There was no statistically significant difference (p > 0.05) in absolute buccolingual inclination change between both groups, except for the upper C (p < 0.05), which were more tipped in the surgical group. Translation, i.e., bodily tooth movements that cannot be explained by pure uncontrolled tipping, could be observed with SARPE in the maxilla and with DC-CCLA in both jaws. Dentoalveolar transversal compensation with completely customized lingual appliances does not cause greater buccolingual tipping compared to SARPE.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-The Amount of Posterior Crossbite Correction.

The aim of this study was to compare the crossbite correction of a group (n = 43; f/m 19/24; mean age 27.6 ± 9.5 years) with surgically assisted rapid palatal expansion (SARPE) versus a non-surgical transversal dentoalveolar compensation (DC) group (n = 38; f/m 25/13; mean age 30.4 ± 12.9 years) with completely customized lingual appliances (CCLA). Arch width was measured on digital models at the canines (C), second premolars (P2), first molars (M1) and second molars (M2). Measurements were obtained before treatment (T0) and at the end of lingual treatment (T1) or after orthodontic alignment prior to a second surgical intervention for three-dimensional bite correction. There was no statistically significant difference (p > 0.05) in the amount of total crossbite correction between the SARPE and DC-CCLA group at C, P2, M1 and M2. Maxillary expansion was greater in the SARPE group and mandibular compression was greater in the DC-CCLA group. Crossbite correction in the DC-CCLA group was mainly a combination of maxillary expansion and mandibular compression. Dentoalveolar compensation with CCLAs as a combination of maxillary expansion and mandibular compression seems to be a clinically effective procedure to correct a transverse maxillo-mandibular discrepancy without the need for surgical assistance.

Conformity between Pacifier Design and Palate Shape in Preterm and Term Infants Considering Age-Specific Palate Size, Facial Profile and Lip Thickness.

This retrospective case-control study is the first to examine the spatial conformity between pacifiers and palates in 39 preterm infants (12 females, 27 males) and 34 term infants (19 females, 15 males), taking into account the facial-soft-tissue profile and thickness. The shape of 74 available pacifiers was spatially matched to the palate, and conformity was examined using width, height, and length measurements. In summary, the size concept of pacifiers is highly variable and does not follow a growth pattern, like infant palates do. Pacifiers are too undersized in width, length, and height to physiologically fit the palate structures from 0 to 14 months of age. There are two exceptions, but only for premature palates: the palatal depth index at 9−11 months of age, which has no clinical meaning, and the nipple length at <37 weeks of age, which bears a resemblance to the maternal nipple during non-nutritive sucking. It can be concluded that the age-size concept of the studied pacifiers does not correspond to any natural growth pattern. Physiologically aligned, pacifiers do not achieve the age-specific dimensions of the palate. The effects attributed to the products on oral health in term infants cannot be supposed.

Simplifying Diagnosis of Fetal Alcohol Syndrome Using Machine Learning Methods.

INTRODUCTION: The fetal alcohol spectrum disorder (FASD) is a complex and heterogeneous disorder, caused by gestational exposure to alcohol. Patients with fetal alcohol syndrome (FAS-most severe form of FASD) show abnormal facial features. The aim of our study was to use 3D- metric facial data of patients with FAS and identify machine learning methods, which could improve and objectify the diagnostic process. MATERIAL AND METHODS: Facial 3D scans of 30 children with FAS and 30 controls were analyzed. Skeletal, facial, dental and orthodontic parameters as collected in previous studies were used to evaluate their value for machine learning based diagnosis. Three machine learning methods, decision trees, support vector machine and k-nearest neighbors were tested with respect to their accuracy and clinical practicability. RESULTS: All three of the above machine learning methods showed a high accuracy of 89.5%. The three predictors with the highest scores were: Midfacial length, palpebral fissure length of the right eye and nose breadth at sulcus nasi. CONCLUSIONS: With the parameters right palpebral fissure length, midfacial length and nose breadth at sulcus nasi, machine learning was an efficient method for the objective and reliable detection of patients with FAS within our patient group. Of the three tested methods, decision trees would be the most helpful and easiest to apply method for everyday clinical and private practice.

Incorrect measurements and misleading conclusions in the article "Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study".

BACKGROUND/OBJECTIVE: To reproduce the methods and results of the study by Alobeid et al. (2018) in which the efficacy of tooth alignment using conventional labial and lingual orthodontic bracket systems was assessed. MATERIALS/METHODS: We used the identical experimental protocol and tested (i) regular twin bracket (GAC-Twin [Dentsply]) and lingual twin bracket systems (Incognito [3M]), (ii) together with NiTi 0.014" wires (RMO), and (iii) a simulated malocclusion with a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). RESULTS: The method described by Alobeid et al. (2018) is not reproducible, and cannot be used to assess the efficacy of tooth alignment in labial or lingual orthodontic treatment. Major flaws concern the anteroposterior return of the Thermaloy-NiTi wire ligated with stainless steel ligatures. The reproduced experimental setting showed that a deflected Thermaloy-NiTi wire DOES NOT move back at all to its initial stage (= 0 per cent correction) because of friction and binding (see supplemented video), neither with the tested labial nor with the lingual brackets. Furthermore, an overcorrection of up to 138 per cent, which the authors indicate for some labial bracket-wire combinations and which deserves the characterization "irreal", stresses the inappropriateness of the method of measurement.Further flaws include: a) incorrect interpretation of the measurement results, where a tooth tripping around (overcorrection) is interpreted as a better outcome than a perfect 100 per cent correction; b) using a statistical test in an inappropriate and misleading way; c) uncritical copying of text passages from older publications to describe the method, which do not correspond to this experimental protocol and lead to calculation errors; d) wrong citations; e)differences in table and bar graph values of the same variable; f) using a lingual mushroom shaped 0.013" Thermaloy-NiTi wire which does not exist; g) drawing uncritical conclusions of so called "clinical relevance" from a very limited in vitro testing. CONCLUSIONS: Clinical recommendations based on in vitro measurements using the Orthodontic Measurement and Simulation System (OMSS) should be read with caution.

Asymmetry-index and orthodontic facial analysis of children with foetal alcohol syndrome using 3D-facial scans.

BACKGROUND: The foetal alcohol spectrum disorder (FASD) is a complex and heterogenic disorder, caused by gestational exposure to alcohol. Patients with foetal alcohol syndrome (FAS-most severe form) show abnormal facial features. Our study aims at finding additional reliable and objective parameters for FAS diagnosis. METHODS: Facial three-dimensional scans of 30 children with FAS and 30 controls were analysed. Orthodontic profile analysis (concerning position of upper and lower jaw) was performed. Vertical facial proportions were taken and facial asymmetry index (right to left side) was calculated. RESULTS: Profile type was significantly different for children with FAS (p = 0.001) with lower jaws more frequently in a retral position. Profile angle was significantly larger in the group with FAS (p = 0.009). Children with FAS had shorter middle thirds and longer lower thirds of the face (p < 0.001). Stomion (point between upper and lower lip) was located significantly more caudally in the FAS group (p < 0.001). Facial asymmetry index was not significantly different. CONCLUSIONS: Children with FAS differ significantly from controls in vertical and sagittal facial measurements. Profile analysis and measurement of vertical proportions are easy to apply standard procedures in everyday orthodontic practice and could be time-saving and objective means for additional verification of FAS.

Children with Fetal Alcohol Syndrome (FAS): 3D-Analysis of Palatal Depth and 3D-Metric Facial Length.

Background: Drinking alcohol during pregnancy can result in severe developmental disorders in the child. Symptoms of the fetal alcohol spectrum disorder (FASD) comprise growth deficiencies, abnormal facial phenotype and damage or dysfunction of the central nervous system. Numerous diagnostic methods for facial phenotyping in FASD exist, but diagnoses are still difficult. Our aim was to find additional and objective methods for the verification of FAS(D). Methods: Three-dimensional dental models of 60 children (30 FAS and 30 controls) were used to metrically determine maximum palatal depths at the median palatine raphe. Three-dimensional facial scans were taken, and vertical distances of the face were measured at five defined facial landmarks (FP1-FP5) for each child. Results: Mean palatal height, total facial length (FP1-FP5) as well as FP4-FP5 did not significantly differ between the FAS group and the control group. Comparing vertical facial subdivisions, however, resulted in significant differences for distances FP1 to FP2 (p = 0.042, FAS > controls), FP2 to FP3 (p < 0.001, FAS < controls), FP3 to FP4 (p < 0.001, FAS > controls) and FP3 to FP5 (p = 0.007, FAS > controls). Conclusions: Metric vertical measurements of the face can be used as additional objective criteria for FAS diagnoses. However, no significant differences were reported for palatal depth evaluation in the specific age range tested in the present study.

Tooth Malformations, DMFT Index, Speech Impairment and Oral Habits in Patients with Fetal Alcohol Syndrome.

Background: Fetal alcohol spectrum disorder (FASD) is a developmental disorder with severe negative lifetime consequences. Although knowledge about the harmfulness of alcohol consumption during pregnancy has spread, the prevalence of fetal alcohol spectrum disorder is very high. Our study aims at identifying fetal alcohol syndrome (FAS)-associated dental anomalies or habits, which need early attention. Methods: Sixty children (30 FAS; 30 controls) were examined prospectively. Swallowing pattern, oral habits, breastfeeding, speech therapy, ergotherapy, physiotherapy, exfoliation of teeth, DMFT (decayed, missing, filled teeth) index, modified DDE (developmental defects of enamel) index and otitis media were recorded. Results: Swallowing pattern, exfoliation of teeth, and otitis media were not significantly different. Significant differences could be found concerning mouthbreathing (p = 0.007), oral habits (p = 0.047), age at termination of habits (p = 0.009), speech treatment (p = 0.002), ergotherapy, physiotherapy, and breastfeeding (p ≤ 0.001). DMFT (p ≤ 0.001) and modified DDE (p = 0.001) index showed significantly higher values for children with fetal alcohol syndrome. Conclusions: Children with fetal alcohol syndrome have a higher need for early developmental promotion such as speech treatment, ergotherapy, and physiotherapy. Mouthbreathing, habits, and lack of breastfeeding may result in orthodontic treatment needs. High DMFT and modified DDE indexes hint at a higher treatment and prevention need in dentistry.

3D-Analysis of Mouth, Nose and Eye Parameters in Children with Fetal Alcohol Syndrome (FAS).

Background: Fetal alcohol spectrum disorder (FASD) is a developmental disorder with severe negative lifetime consequences for the affected person. Numerous diagnostic methods for facial assessment in FAS exist, but most of them are based on subjective evaluations. Our aim was therefore to find objective methods for the verification of FAS(D). Methods: 58 children (28 FAS; 30 controls) were examined prospectively. 3D facial scans were performed for each child and facial parameters at the mouth, nose and eye regions were measured and compared between the groups. Results: Significant differences could be found for the distance between right and left sulcus nasi at the transition point to the philtrum (p < 0.001), for the inner canthal distance (p = 0.001) as well as for the right and left palpebral fissure length (p < 0.001). No significant difference between the FAS and control children could be found for the measurements of mouth breadth (p = 0.267) and breadth between the left and right alares nasi (p = 0.260). Conclusions: Measurements of mouth breadth and nose breadth for the alares nasi are not suitable for FAS diagnosis. In contrast, digital contactless measurements of the distance between the right and left sulcus nasi at the transition point to the philtrum, as well as the inner canthal distance and palpebral fissure length of the left and right eyes, showed significant differences when comparing children with FAS to healthy controls. These measurements could thus be additional objective means for the verification of FAS.

Correction to: The tablet computer's impact on learning and National Dental Examination scores in orthodontics - a mixed-method research.

Following publication of the original article [1], the editor-in-chief reported that the information regarding ethics approval was accidentally entered by the author under trial registration. A trial registration was not required for this study.

The tablet computer's impact on learning and National Dental Examination scores in orthodontics - a mixed-method research.

BACKGROUND: To assess the educational impact of a one-to-one tablet PC (TPC) program by analysing university students' learning skills and related scores of the National Dental Examination (NDE) in Germany. METHODS: The study design was a mixed-method approach consisting of a survey and a comparison of NDE scores. Students received a loaned non-preloaded and non-managed TPC during three consecutive orthodontic semesters. Usability and learning benefits in clinical and nonclinical settings were assessed by a survey. After the participating students had passed the NDE in a standard period of study, their grades were compared with those of students from the semester prior to TPC introduction. RESULTS: One hundred and eight students (36 females and 72 males) received an TPC and participated in the survey. Of these, 53 passed the NDE in a standard period of study. 64 students from the semester before TPC introduction, who passed in the regular period of study, were chosen as non-TPC control group. Survey: Students' expectations concerning TPC benefits increased significantly after TPC usage (P = 0.000). TPCs were rated more useful for learning at places outside the clinic setting than for inside (P = 0.000). PDFs and communication applications were used more in nonclinical settings (P = 0.008 and 0.000, respectively). NDE scores: Concerning the examination parts relating to theoretical knowledge and clinical knowledge, students with full TPC use achieved higher scores than did those without TPC use (P = 0.006 and 0.002, respectively). Scores for manual skills showed no differences, neither for students with and without TPC, nor within the semester after TPC introduction (P = 1.000). CONCLUSIONS: This is the first study to analyse a one-to-one TPC program in the orthodontic curriculum and measure the effect of TPC usage on NDE scores. Students' expectations concerning the TPC benefit in the orthodontic curriculum improved significantly after using the devices. We have shown that NDE scores in theoretical knowledge increased significantly after TPC deployment whereas scores in motor skills remained unchanged. The results suggest that the TPC has a positive learning effect on theoretical knowledge in orthodontics. TRIAL REGISTRATION: Permission to conduct this study was given by the Ethics Committee of the Department of Medicine of the University of Münster, Germany (2012-12-13).

3D Analysis of Philtrum Depth in Children with Fetal Alcohol Syndrome.

AIMS: Diagnosis of fetal alcohol spectrum disorder (FASD) is complex and difficult. The estimated number of unreported FASD is thus assumed to be substantial. In our cross-sectional study, we aimed to identify possible metric differences in philtrum depth in children with fetal alcohol syndrome (FAS) compared to healthy controls based on non-invasive 3D facial scanning in order to provide an objective, metrical tool improving FASD diagnosis. METHODS: Twenty-five children with confirmed FAS and 30 healthy school children without FAS, both in the mixed dentition, were prospectively recruited and 3D facial scans were performed after recording body length, weight and head circumference. Philtrum surface data were extracted and metric philtrum depth was determined at four geometrically defined measuring points (P1-P4) along the vertical length of the philtrum. RESULTS: Philtrum depths at P1 (P = 0.025), P2 (P = 0.001), P3 (P < 0.001) and P4 (P = 0.001) as well as mean philtrum depth P1-P4 (P < 0.001) differed significantly between patients with and without FAS. Compared to controls, the philtrum was shallower in patients with FAS by on average 0.4 mm at each of the respective points. Whereas no differences could be determined for body height and weight, head circumference was significantly smaller in patients with FAS (P = 0.001), particularly in girls (P = 0.008). CONCLUSIONS: Apart from head circumference, philtrum depth is significantly reduced in children with FAS and can thus be used as diagnostic indicator to aid and confirm FAS diagnosis. In contrast to visual assessments, 3D face scan methods allow a more objective quantification and can thus provide additional evidence in FAS diagnosis.

Malocclusion Can Give Additional Hints for Diagnosis of Fetal Alcohol Spectrum Disorder.

AIMS: Fetal alcohol spectrum disorder (FASD) is a developmental disorder caused by maternal alcohol intake (prevalence: 0.77%). Malocclusion has been described in case reports of patients with FASD, but reliable evidence for associations between FASD and malocclusion is not documented. Malocclusion is defined as tooth irregularity (prevalence: 14.6%) or incorrect relationship between the jaws such as lateral crossbites (prevalence: 3.1%). The purpose of this study was to investigate possible associations between malocclusion and FASD. SHORT SUMMARY: FASD prevalence is high and diagnosis is very difficult; Malocclusions can give additional hints for FASD diagnosis; Patients with FASD show growth deficits concerning the maxilla; Early and consistent orthodontic supervision and therapy can prevent facial asymmetries in FASD patients. METHODS: Thirty patients with FASD and 30 patients of a healthy control group were examined. Inclusion criteria were mixed dentition, verified FASD/absence of FASD (control group), exclusion criteria were orthodontic treatment and disorders other than FASD. The extent and type of malocclusion were quantified with the peer assessment rating (PAR) index based on an analysis of orthodontic plaster models. In addition, anthropometric data such as gestational age, body weight and height at birth as well as present body weight, height and head circumference at examination date were assessed. RESULTS: The PAR index showed a significant increase in malocclusions in FASD patients compared to the group that were not diagnosed with FASD (P = 0.002). FASD patients showed particular differences in the upper transversal dimension with a higher prevalence of crossbites (P = 0.018) and a lower head circumference (P < 0.001). Body weight (P < 0.001) and height (P < 0.001) were significantly lower for FASD patients at time of birth, but not at the present examination date (weight: P = 0.329; height: P = 0.496). When relating weight and height measures to age using percentile curves of physiological growth, clinically relevant discrepancies could be found for FASD patients. CONCLUSIONS: Our results show that malocclusion can provide additional evidence for FASD diagnosis. When FASD is diagnosed in a child, early referral to an orthodontist is advisable to stimulate maxillary growth and consequently prevent further malocclusions.

Correction: Growth of the hard palate in infants with Down syndrome compared with healthy infants-A retrospective case control study.

[This corrects the article DOI: 10.1371/journal.pone.0182728.].

Growth of the hard palate in infants with Down syndrome compared with healthy infants-A retrospective case control study.

OBJECTIVE: To investigate morphological differences of the hard palate in infants with Down syndrome (DS) compared with a volumetric-matched control group (CG). METHODS: Trial design: retrospective case control study. Based on inclusion and exclusion criteria, plaster casts of edentulous maxillae of 40 DS infants (20 females and 20 males, aged 221.3 ± 132.4 days) and 40 CG infants (20 females and 20 males, aged 53.9 ± 87.2 days) were digitized and converted into 3-dimensional stereolithography data. An automated landmark- and investigator-independent method for assessing two-dimensional measurements such as width, depth, and length of palate, as well as palatal index and the 3-dimensional volume, were used. RESULTS: Matching DS and healthy CG infants by age, we found reduced sizes in all linear and volumetric measurements in the DS group. Matching both groups by palatal volume, we found no differences between the groups according to palatal width (p = .93), palatal depth (p = .32), and palatal index (p = .31). Control infants with the same palatal volume compared with the DS infants were about 151 days younger, 95%-CI = [102, 200] (Hodges-Lehmann estimator). Except for palatal length and palatal volume, the growth pattern of DS palates decreased irregularly at age 6 to 9 months. CONCLUSIONS: The palate of DS infants in the first 6 to 9 month of life is of normal shape but considerably smaller compared with healthy normals. From 6 to 9 months onward, the growth pattern of the hard palate in DS infants decreases irregularly. High-arch-constricted palates could, therefore, be interpreted as secondarily acquired in later life. We therefore speculate that it could be advantageous to begin oral muscular stimulating therapy between 6 and 9 months of age which may prevent palatal shape alterations and enhance oral function which also contributes to maxillary development.

Orthodontic treatment of children/adolescents with special health care needs: an analysis of treatment length and clinical outcome.

BACKGROUND: The aim of this retrospective study was to analyse the treatment time and differences between the pre- and post-treatment peer assessment rating (PAR) index and aesthetic component (AC) of the index of orthodontic treatment need (IOTN) scores in children/adolescents with special health care needs (SHCNs), compared to non-special health care needs (NSHCNs) controls. METHODS: Based on certain inclusion and exclusion criteria, medical records of SHCNs and randomly selected NSHCNs controls at the Department of Orthodontics, University Hospital Muenster were analysed retrospectively for the treatment time, number of appointments, chair time ("moderate" or "considerable"), PAR scores, and AC scores. Sample size calculation, descriptive statistics, and explorative analyses were performed using the Mann-Whitney U Test. RESULTS: Twenty-nine children with SHCNs (21 boys, 9 girls; median age: 11 years, pre-treatment) and 29 children with NSHCNs (12 boys, 17 girls; median age: 12 years, pre-treatment) were enrolled in this study.The overall treatment time did not differ between the patient groups. However, more "considerable chair time" was needed for the SHCNs group compared to the control group (p < 0.05), whereas "moderate chair time" was more often needed in patients with NSHCNs (p = 0.001).The age of the patients at the first and last appointments showed significant statistical differences: children in the SHCNs group commenced orthodontic treatment earlier, by a median of 1 year, compared to children in the NSHCNs group.The SHCNs group had significantly higher pre- and post-treatment PAR scores (median 21/median 6) and AC scores (median 9/median 3) compared to NSHCNs patients (PAR: median 17/median 0; AC: median 5/median 1).However, the overall treatment time and the overall PAR and AC score reduction did not differ significantly between the SHCNs and NSHCNs groups. CONCLUSIONS: While the overall treatment time and number of appointments did not differ, the overall chair time was higher in the SHCNs group. The pre- and post-treatment PAR and AC scores were significantly higher in the SHCNs group.