Three-dimensional video recordings: Accuracy, reliability, clinical and research guidelines - Reliability assessment of a 4D camera.

OBJECTIVES: In addition to studying facial anatomy, stereophotogrammetry is an efficient diagnostic tool for assessing facial expressions through 3D video recordings. Current technology produces high-quality recordings but also generates extremely excessive data. Here, we compare various recording speeds for three standardized movements using the 3dMDface camera system, to assess its accuracy and reliability. MATERIALS AND METHODS: A linear and two circular movements were performed using a 3D-printed cube mounted on a robotic arm. All movements were recorded initially at 60 fps (frames/second) and then at 30 and 15 fps. Recording accuracy was tested with best-fit superimpositions of consecutive frames of the 3D cube and calculation of the Mean Absolute Distance (MAD). The reliability of the recordings were tested with evaluation of the inter- and intra-examiner error. RESULTS: The accuracy of movement recordings was excellent at all speeds (60, 30 and 15 fps), with variability in MAD values consistently being less than 1 mm. The reliability of the camera recordings was excellent at all recording speeds. CONCLUSIONS: This study demonstrated that 3D recordings of facial expressions can be performed at 30 or even at 15 fps without significant loss of information. This considerably reduces the amount of produced data facilitating further processing and analyses.

Third molar agenesis in individuals with supernumerary teeth.

OBJECTIVES: To explore the association between third molar agenesis and supernumerary tooth formation in a white-European population. MATERIALS AND METHODS: A record review in various orthodontic clinics identified 380 eligible white-European individuals, half of whom had non-syndromic permanent supernumerary teeth (122 males and 68 females, totalling 244 supernumerary teeth; median age: 13.1, iqr: 1.5 years), and the other half were age- and sex-matched controls with full dentition, excluding the third molars. Tooth sequences were identified in panoramic radiographs. RESULTS: In the supernumerary group, approximately 80% of the individuals had a single supernumerary tooth, followed by those having two additional teeth. In both groups, there was no sexual dimorphism in third molar agenesis severity. The prevalence of third molar agenesis in the supernumerary group was similar to that of the control group (28/190 = 14.7% in both groups; p = 1.0). In total, 53 third molars were missing in the supernumerary group (n = 190) compared to 67 in the control group (n = 190; p = .862). The ratio of bilateral to unilateral third molar agenesis was significantly lower in the supernumerary group than in the control group (1.0 vs. 3.7, respectively; p = .026). CONCLUSION: The presence of supernumerary teeth did not significantly alter the likelihood of third molar agenesis or its severity. Bilateral third molar agenesis was considerably less prevalent in individuals with supernumerary teeth compared to controls. The present novel findings have important clinical and developmental implications.

Third molar agenesis relates to human craniofacial form.

OBJECTIVE: To investigate the association between the number of third molars and craniofacial shape. SUBJECTS AND METHODS: The study sample comprised 470 individuals (194 males and 276 females), out of whom 310 (124 males, mean age: 14.6 years and 186 females, mean age: 14.1 years) had a full permanent dentition including third molars and 160 (70 males, mean age: 13.7 years and 90 females, mean age: 13.9 years) had at least one missing third molar. Pre-orthodontic treatment cephalometric images were digitized using 127 landmarks to describe the shape of the entire craniofacial configuration, the cranial base, the maxilla, and the mandible. The shapes of the various configurations were described by principal components (PCs) of shape. The effect of third molar agenesis on craniofacial shape was evaluated with multivariate regression models, considering shape PCs as the dependent variables, and age and sex as predictors. RESULTS: There was a strong association between third molar agenesis and the shape of all craniofacial configurations in both sexes. Individuals with missing third molars presented a less convex craniofacial configuration, a shorter anterior facial height and a more retrusive maxilla and mandible. In cases with third molar agenesis only in one jaw, shape differences were also evident in the opposing jaw. LIMITATIONS: Interpretation of study outcomes should take into consideration the two-dimensional data and the analysis of only white-European subjects. CONCLUSIONS: There is a strong association between third molar formation and craniofacial shape. The effect is rather generalized than local and is potentially linked to an ongoing evolutionary mechanism that leads to smaller and fewer teeth, as well as smaller craniofacial configurations, in modern humans.

Profile shape variation and sexual dimorphism amongst middle-aged Northern Europeans.

AIM: To explore profile shape variation in a large population of middle-aged individuals and investigate features of sexual dimorphism. MATERIALS AND METHODS: Facial profile photographs of 1776 individuals (964 females and 812 males; 46 years old), members of the Northern Finland Birth Cohort 1966 (NFBC1966), were uploaded and digitized with Viewbox software. Profile shape was defined with 47 landmarks (4 fixed and 43 sliding semi-landmarks). Digitized images were reoriented and scaled with Procrustes Superimposition, and shape variation was determined with a Principal Component Analysis. RESULTS: More than 90 per cent of profile shape variation was explained by Principal Components (PC) 1-9. PC1, explaining the largest amount of variation (33.1 per cent) described changes in facial convexity, slope of the forehead, lip, and chin protuberance. PC2 (23.1 per cent variation) was more related to vertical changes of the lower facial third and PC3 (11 per cent variation) primarily described changes in lip protrusion and nasal projection. Shape analysis showed a significant difference between the average female and the average male profile shape (P < 0.001); however, this was not evident upon visual observation. The shape variable most associated with sex was PC3 (η 2 = 0.245; P < 0.001), which described changes in lip prominence and in projection of the dorsal nasal surface. An additional discriminant analysis showed that profile shape predicted sex in 76 per cent of males and 79.6 per cent of females. CONCLUSIONS: There is significant sexual dimorphism in facial profile among middle-aged adults. Profile shape variation was associated to changes in lip protrusion, nasal protuberance, and chin projection.

The effect of orthodontic treatment on facial attractiveness: a systematic review and meta-analysis.

BACKGROUND: Facial and smile attractiveness are significant motivating factor for patients to seek orthodontic treatment. Although there is a general belief that orthodontic treatment improves facial appearance, this has yet not been systematically evaluated. OBJECTIVE: The objective of this study was to assess the current evidence on the effect of orthodontic treatment on facial attractiveness. SEARCH METHODS: Systematic and unrestricted search of nine databases were performed up to January 2022. SELECTION CRITERIA: Studies evaluating facial attractiveness before and after orthodontic treatment. DATA COLLECTION AND ANALYSIS: Extracted data included study design and setting, sample size and demographics, malocclusion type, treatment modality, and method for outcome assessment. Risk of bias was assessed with the ROBINS-I tool for non-randomized studies and with RoB-2 for randomized controlled trials (RCTs). Random-effects meta-analyses of mean differences and their 95% confidence intervals (CIs) were performed. RESULTS: Twenty studies were included in data synthesis; three randomized controlled clinical trials and 17 non-randomized clinical studies of retrospective or prospective design. One of the RCTs was found to have low risk of bias, one presented some concerns and the third showed a high risk of bias. All non-randomized studies showed either unclear or high risk of bias. Data syntheses showed that orthodontic treatment improved facial attractiveness ratings by 9% when compared with untreated controls (MD: 9.05/95% CI: 4.71; 13.39). A combination of orthodontics and orthognathic surgery also showed a positive effect of 5.5% (MD: 5.51/95% CI: 1.55; 9.47) when compared with orthodontic treatment alone. There was no difference in effect between extraction and non-extraction treatments (MD: -0.89/ 95% CI: -8.72; 6.94) or between different types of Class II correctors (MD: 2.21/95% CI: -16.51; 20.93). LIMITATIONS: With the exception of two RCTs, included studies were of unclear or low quality. CONCLUSIONS: Orthodontic treatment has a clinically weak effect on facial attractiveness when compared to no treatment. The same is true when a combined orthodontic/surgical treatment is compared to orthodontics alone. REGISTRATION: PROSPERO #: CRD42020169904.

Voxel-based superimposition of serial craniofacial cone-beam computed tomographies for facial soft tissue assessment: Reproducibility and segmentation effects.

INTRODUCTION: The aim of this investigation was to evaluate the reproducibility of a voxel-based 3-dimensional superimposition method and the effect of segmentation error on determining soft tissue surface changes. METHODS: A total of 15 pairs of serial cone-beam computed tomography images (interval: 1.69 ± 0.37 years) from growing subjects (initial age: 11.75 ± 0.59 years) were selected from an existing digital database. Each pair was superimposed on the anterior cranial base, in 3 dimensions with Dolphin 3D software (version 2.1.6079.17633; Dolphin Imaging & Management Solutions, Chatsworth, Calif). The reproducibility of superimposition outcomes and surface segmentation were tested with intra- and interoperator comparisons. RESULTS: Median differences in inter- and intrarater measurements at various areas presented a range of 0.08-0.21 mm. In few instances, the differences were larger than 0.5 mm. In areas where T0-T1 changes were increased, the error did not appear to increase. However, the method error increased the farther the measurement area was from the superimposition reference structure. For individual images, the median soft tissue segmentation error ranged from 0.05 to 0.06 at various areas and in no subject exceeded 0.13 mm. CONCLUSIONS: The presented voxel-based superimposition method was efficient and well reproducible. The segmentation process was a minimal source of error; however, there were a few cases in which the total error was more than 0.5 mm and could be considered clinically significant. Therefore, this method can be used clinically to assess 3-dimensional soft tissue changes during orthodontic treatment in growing patients.

Voxel-based superimposition of serial craniofacial CBCTs: Reliability, reproducibility and segmentation effect on hard-tissue outcomes.

OBJECTIVES: To test the reliability and reproducibility of a fast and user-friendly voxel-based 3D superimposition method and the effect of bone segmentation on its outcomes. SETTING AND SAMPLE POPULATION: This prospective methodological study assessed 15 pairs of pre-existing serial CBCT images (interval: 1.69 ± 0.37 years) obtained from growing patients (initial age: 11.75 ± 0.59 years). MATERIALS AND METHODS: Volumes were superimposed on the anterior cranial base using Dolphin 3D software. Reliability was assessed visually, by inspecting the overlap of the superimposition reference structures. Reproducibility was tested with intra- and inter-operator comparisons of superimposition outcomes. RESULTS: The method presented good reliability in all cases. The median differences between intra- and inter-operator comparisons at various tested areas ranged from 0.06 to 0.16 mm and from 0.15 to 0.24 mm, respectively. In few individual cases, differences exceeded 0.5 mm. There was no evidence that the error increased upon increase in the magnitude of the detected T0-T1 changes. However, the superimposition error increased when the distance between the measurement area and the superimposition reference also increased. For a single image, the median error of bone surface segmentation ranged in different areas between 0.05 and 0.12 mm, with few exceptions where it slightly exceeded 0.25 mm. CONCLUSIONS: The tested voxel-based superimposition method presented good efficiency, cranial base matching and reproducibility in a growing patient sample. Segmentation error was considered minimal. The total error reached clinically relevant levels in very few cases. Thus, this technique is considered appropriate for clinical use, when 3D assessment of craniofacial changes is required.

The role of lip thickness in upper lip response to sagittal change of incisor position.

OBJECTIVES: To investigate the association between upper lip thickness and the amount of upper lip repositioning upon retraction of maxillary incisors. SETTING AND SAMPLE POPULATION: Pre- and post-treatment lateral cephalograms of 101 patients were reviewed. All subjects were treated with fixed orthodontic appliances including extraction of two maxillary premolars. Only subjects without change in lip thickness between pre- and post-treatment cephalograms were included. MATERIAL AND METHODS: Digital software measurements for lip thickness, pre- and post-treatment upper lip position were performed. Appropriate regression models were developed to explore the correlation between maxillary incisor retraction and lip retraction when controlling for lip thickness and other confounding factors. The level of statistical significance was set at 0.05 for all analyses. RESULTS: A significant correlation was found between change in maxillary incisor position following premolars extraction and change in upper lip position (r = 0.95, P < 0.001). The average ratio between maxillary incisor retraction and upper lip repositioning was 1.43:1. Upper lip thickness was not significantly associated with this ratio (r = 0.003, P > 0.05). CONCLUSION: Although there is a highly significant correlation between maxillary incisor retraction and upper lip repositioning, lip thickness is not significantly associated with the amount of repositioning.

Influence of overjet and overbite on soft tissue profile in mature adults: A cross-sectional population study.

INTRODUCTION: The aim of this study was to explore the association of soft tissue profile and severity of overbite and overjet in a large adult population. METHODS: The study population consisted of 1630 adults (age, 46 years; 712 men, 919 women), all part of the Northern Finland Birth Cohort 1966. A clinical examination was performed on all subjects, including recording of overjet and overbite, and digital facial (frontal and profile) photographs were obtained. A multivariate regression model was developed to study the correlation of soft tissue measurements with overjet and overbite, considering the effect of sex. RESULTS: The regression model explained approximately 30% of the variability in overjet in our sample and approximately 22% of the variability in overbite. Overjet was related more significantly to upper and lower anteroposterior lip position, and upper and lower facial height (P <0.05). Overbite showed a stronger association with anteroposterior position of the lower lip, pogonion, and soft tissue B-point (P <0.05). CONCLUSIONS: Soft tissue profile was weakly to moderately correlated with severity of overjet and overbite in the entire sample. However, in subjects with negative overjet (mandibular prognathism), this association was highly significant.

Association of facial sagittal and vertical characteristics with facial aesthetics in the Northern Finland Birth Cohort 1966.

OBJECTIVE: To explore the association of facial sagittal and vertical dimensions with aesthetic assessment by three panel groups. MATERIALS AND METHODS: The study population comprised adult individuals from the Northern Finland Birth Cohort 1966 (NFBC1966). A clinical oral examination including digital facial photographs was performed. The study population was divided into subjects with the lowest and highest values in soft tissue measurements in lower anterior facial height percentage (LAFH%) (60 subjects) and antero-posterior jaw relationship [soft tissue A-point, nasion, and B-point (ANB) angle; 60 subjects] and a control group (30 subjects). Frontal and profile facial photographs were presented to three panel groups: five orthodontists, five dentists, and five laypersons, who evaluated the photographs using the visual analogue scale (VAS). RESULTS: This study showed significant differences in VAS mean scores between the panel groups. Curve estimation revealed a significant quadratic association between aesthetic VAS evaluation and ANB angle for all panel groups. The association between ANB angle and perceived facial attractiveness was highest among orthodontists (R2 = 0.276, P = 0.001 for males; R2 = 0.285, P = 0.001 for females). However, no statistically significant association was found between facial attractiveness and LAFH%. CONCLUSION: Facial sagittal dimensions appeared to influence facial aesthetics more than vertical dimensions in middle-aged adults. In their perception of facial aesthetics, orthodontists were more influenced by antero-posterior jaw relationships than dentists and laypersons. The overall perception of facial attractiveness related to facial dimensions appeared to differ between the panel groups in female and male faces.

Authorship characteristics of orthodontic randomized controlled trials, systematic reviews, and meta-analyses in non-orthodontic journals with impact factor.

Background/Objective: This study was conducted to explore authorship characteristics and publication trends of all orthodontic randomized controlled trials (RCTs), systematic reviews (SRs), and meta-analyses (MAs) published in non-orthodontic journals with impact factor (IF). Materials and methods: Appropriate research strategies were developed to search for all articles published until December 2015, without restrictions regarding language or publication status. The initial search generated 4524 results, but after application of the inclusion criteria, the final number of articles was reduced to 274 (SRs: 152; MAs: 36; and RCTs: 86). Various authorship characteristics were recorded for each article. Frequency distributions for all parameters were explored with Pearson chi-square for independence at the 0.05 level of significance. Results: More than half of the included publications were SRs (55.5 per cent), followed by RCTs (31.4 per cent) and MAs (13.1 per cent); one hundred seventy-eight (65 per cent) appeared in dental journals and 96 (35 per cent) were published in non-dental journals. The last decade was significantly more productive than the period before 2006, with 236 (86.1 per cent) articles published between 2006 and 2015. European countries produced 51.5 per cent of the total number of publications, followed by Asia (18.6 per cent) and North America (USA and Canada; 16.8 per cent). Limitations: Studies published in journals without IF were not included. Conclusions/Implications: Level-1 evidence orthodontic literature published in non-orthodontic journals has significantly increased during 2006-15. This indicates a larger interest of other specialty journals in orthodontic related studies and a trend for orthodontic authors to publish their work in journals with impact in broader fields of dentistry and medicine.

Prevalence of malocclusion traits and orthodontic treatment in a Finnish adult population.

Objective The aim of the study was to examine the prevalence of malocclusion traits and the extent of orthodontic treatment in a Finnish adult population. Materials and methods The study population comprised subjects (n = 1964) from the Northern Finland Birth Cohort 1966 living in the city of Oulu and within 100 km of it. A clinical oral and dental examination with registration of occlusion was carried out in 2012 in connection with a 46-year follow-up survey. Data on previous orthodontic treatment were collected based on a questionnaire. Results In the clinical examination, 39.5% of the subjects had at least one malocclusion trait. The most common malocclusion traits were lateral crossbite (17.9%), overbite ≥ 6 mm (11.7%) and overjet ≥ 6 mm (9.7%). Crossbite on the left premolars, negative overjet and increased overbite were found more frequently in men. The prevalence of malocclusion traits was at the same level in treated and untreated groups. Overall, 18.6% of the subjects had undergone orthodontic treatment. Women showed a significantly higher prevalence of orthodontic treatment. Conclusions The most common malocclusion trait in the present study was lateral crossbite. Significant male dominance in the prevalence of malocclusion was observed, which has not been reported earlier in Finland. Orthodontic treatment of malocclusion traits was more common among females in Northern Finland. This study indicates that orthodontic treatment provided in childhood was, on average, adequate in reducing malocclusion traits to the level observed in the general population.

Demographic characteristics of systematic reviews, meta-analyses, and randomized controlled trials in orthodontic journals with impact factor.

INTRODUCTION: The aim of this study was to explore demographic characteristics of systematic reviews (SRs), meta-analyses (MAs), and randomized controlled trials (RCTs) published in orthodontic journals with an impact factor (IF). MATERIALS AND METHODS: An electronic search was developed and implemented to identify all the SRs, MAs, and RCTs published in the seven orthodontic journals with an IF. No restrictions were applied regarding language, publication date, or publication status. The initial search generated 1147 articles, which were reviewed by three authors in order to determine if they met the inclusion criteria. Five hundred and fifty-seven articles were included in the final analysis. Type of article, name of journal, year of publication, number of authors, country of origin, and primary affiliation were recorded. Associations between those parameters were tested with the Pearson chi-square test for independence at the 0.05 level of significance. RESULTS: The majority (72%) of this kind of articles published in the orthodontic literature were RCTs, followed by SRs (20.1%) and MAs (7.9%). Approximately 77.2% of all RCTs, SRs, and MAs were published between 2004 and 2013, and 72.9% came from orthodontic departments. More than 80% of all articles were collaborative efforts between three or more authors. Contributions from Asia, South and Central America significantly increased during last decade, while contributions from North America decreased by almost 30%. CONCLUSIONS: Most RCTs, MAs, and SRs have been published between 2004 and 2013, indicating a significant improvement of the orthodontic literature during the last decade. Asia, South and Central America have significantly increased their contributions to the high evidence orthodontic literature since 2004.

The most distal palatal ruga for placement of orthodontic mini-implants.

OBJECTIVE: To evaluate the stability and bone availability of the most distal (third) palatal ruga, as an anatomical region for safe insertion of orthodontic mini-implants (OMIs) in the anterior palate. STUDY DESIGN: Orthodontic records of 35 patients were analysed. Initial (T1) and final (T2) study models were bisected and the outline of the palatal contour was marked on the surface. Models were scanned and the palatal contours were superimposed on the palatal structures on the respective initial and final cephalometric images. Cephalometric measurements were used to assess vertical (3rdRug-PP, 2ndRug-PP, and 1stRug-PP), and oblique bone levels (3rdRug-U1, 2ndRug-U1, 1stRug-U1, and 3rdRug-U1(o)). Paired Student's t-test was used to compare measurements between T1 and T2. RESULTS: The position of the third palatal ruga remained stable during orthodontic treatment (Δ2ndRug-3rdRug P = 0.1mm; P = 0.61 and Δ1stRug-3rdRug P = 0.2mm; P = 0.39). Bone availability also remained adequate (3rdRug-U1T2 (o) = 9.9mm). CONCLUSION: The third palatal ruga is a reliable clinical landmark to evaluate bone availability for the placement of OMIs in the anterior palate.

Three dimensional anatomical exploration of the anterior hard palate at the level of the third ruga for the placement of mini-implants--a cone-beam CT study.

AIM: The aim of this retrospective investigation was to measure vertical bone thickness on the hard palate, determine areas with adequate bone for the insertion of orthodontic mini-implants (MIs), and provide clinical guidelines for identification of those areas. MATERIALS AND METHODS: Pre-treatment records of 1007 patients were reviewed by a single examiner. A total of 125 records fulfilled the inclusion criteria and were further investigated. Bone measurements were performed on cone-beam computed tomography scans, at a 90° angle to the bone surface, on 28 predetermined and standardized points on the hard palate. Bone thickness at various areas was associated to clinically identifiable areas on the hard palate by means of pre-treatment plaster models. RESULTS: Bone thickness ranged between 1.51 and 13.86 mm (total thickness) and 0.33 and 1.65 mm (cortical bone thickness), respectively. Bone thickness was highest in the anterior palate and decreased significantly towards more posterior areas. Plaster model analysis revealed that bone thickness was highest at the level of the third palatal ruga. CONCLUSIONS: The areas on the anterior palate with adequate bone thickness for successful insertion of orthodontic MI correspond to the region of the third palatal ruga. These results provide stable and clinically identifiable landmarks for the insertion of palatal MIs.

Interlot variations of transition temperature range and force delivery in copper-nickel-titanium orthodontic wires.

INTRODUCTION: The manufacturing process for copper-nickel-titanium archwires is technique sensitive. The primary aim of this investigation was to examine the interlot consistency of the mechanical properties of copper-nickel-titanium wires from 2 manufacturers. METHODS: Wires of 2 sizes (0.016 and 0.016 × 0.022 in) and 3 advertised austenite finish temperatures (27°C, 35°C, and 40°C) from 2 manufacturers were tested for transition temperature ranges and force delivery using differential scanning calorimetry and the 3-point bend test, respectively. Variations of these properties were analyzed for statistical significance by calculating the F statistic for equality of variances for transition temperature and force delivery in each group of wires. All statistical analyses were performed at the 0.05 level of significance. RESULTS: Statistically significant interlot variations in austenite finish were found for the 0.016 in/27°C (P = 0.041) and 0.016 × 0.022 in/35°C (P = 0.048) wire categories, and in austenite start for the 0.016 × 0.022 in/35°C wire category (P = 0.01). In addition, significant variations in force delivery were found between the 2 manufacturers for the 0.016 in/27°C (P = 0.002), 0.016 in/35.0°C (P = 0.049), and 0.016 × 0.022 in/35°C (P = 0.031) wires. CONCLUSIONS: Orthodontic wires of the same material, dimension, and manufacturer but from different production lots do not always have similar mechanical properties. Clinicians should be aware that copper-nickel-titanium wires might not always deliver the expected force, even when they come from the same manufacturer, because of interlot variations in the performance of the material.

An active, skeletally anchored transpalatal appliance for derotation, distalization and vertical control of maxillary first molars.

OBJECTIVE: The objective of this investigation was to evaluate treatment outcomes of the skeletally anchored 'Frog' appliance. DESIGN: A single-centre, retrospective study was performed. SETTING: Private orthodontic practice. PARTICIPANTS: Patients who had undergone comprehensive orthodontic treatment with the skeletally anchored 'Frog' appliance. METHODS: 43 participants (20 males and 23 females) who had received treatment with the skeletally anchored 'Frog' appliance where included. In order to explore dentoalveolar and skeletal treatment outcomes, pre- (T1) and post- (T2) treatment measurements were performed on patients' plaster models and cephalometric images. Comparisons between T1 and T2 were made by means of a Student's t-test. All statistical analyses were conducted at the 0·05 level of statistical significance. RESULTS: Study model analysis revealed a statistically significant derotation of maxillary molars (µΔT2-T1=9·5°, P<0·001) as well as an increase in transverse arch dimensions at the end of treatment (µΔT2-T1=2·2 mm, P<0·001). Cephalometric changes included bodily distalization of maxillary molars (µΔ(T2-T1)=-1·9 mm, P<0·001), as well as noticeable angular displacement (µΔT2-T1=4·1°, P=0·004). No significant anchorage loss was observed, as displayed by the limited change in maxillary incisor position (µΔ(T1-T2)=0·2 mm, P=0·45). In addition, excellent vertical control of the maxillary molars was achieved, with no change in the mandibular plane (ML/NSL) angle (µΔT2-T1=0·3°, P=0·38). CONCLUSIONS: The skeletal 'Frog' is effective in derotating and distalizing maxillary molars without anchorage loss and with excellent vertical control.

Clinical outcomes of cases with missing lateral incisors treated with the 'T'-Mesialslider.

The objective of this article is to review the fabrication and activation procedures of the 'T'-Mesialslider and to present the clinical outcomes in cases where canine substitution is the treatment of choice for missing maxillary lateral incisors. The 'T'-Mesialslider allows for effective mesial translation of the canines and the posterior dentition, without significant loss of anterior anchorage and with good vertical control. Possible adverse effects of the appliance and clinical recommendations for their management are also discussed. In canine substitution cases with high anchorage demands, the 'T'-Mesialslider provides an effective treatment option.

Occlusal characteristics in modern humans with tooth agenesis.

Non-syndromic permanent tooth agenesis affects a significant proportion of the population, especially if third molars are considered. Although tooth agenesis has been linked to a smaller craniofacial size, reduced facial convexity and a shorter skeletal face, the occlusal characteristics of individuals with tooth agenesis remain largely unexplored. Therefore, this study investigated potential associations between tooth agenesis and metric occlusal traits in 806 individuals (491 with 4.1 missing teeth per subject, including third molars, and 315 without any tooth agenesis). Dentoskeletal morphology was defined through anatomical landmarks on pre-treatment cephalometric radiographs. Multivariate regression models, adjusted for sex and age, showed that tooth agenesis was significantly associated with a reduced overjet, an increased interincisal angle, and shorter upper and lower dental arch lengths, but not with overbite. Moreover, apart from reduced tooth length and dentoalveolar effects, as the number of missing teeth increased the upper front teeth were progressively retruded according to the craniofacial complex and to the face. Thus, tooth agenesis has a substantial influence on dental and occlusal characteristics, as well as on the sagittal position and inclination of anterior teeth. These findings emphasize the necessity for personalized, multidisciplinary approaches in individuals with multiple agenesis to successfully meet treatment goals.

The use of CBCT in orthodontics with special focus on upper airway analysis in patients with sleep-disordered breathing.

Applications of cone-beam CT (CBCT) in orthodontics have been increasingly discussed and evaluated in science and practice over the last two decades. The present work provides a comprehensive summary of current consolidated practice guidelines, cutting-edge innovative applications, and future outlooks about potential use of CBCT in orthodontics with a special focus on upper airway analysis in patients with sleep-disordered breathing. The present scoping review reveals that clinical applications of CBCT in orthodontics are broadly supported by evidence for the diagnosis of dental anomalies, temporomandibular joint disorders, and craniofacial malformations. On the other hand, CBCT imaging for upper airway analysis-including soft tissue diagnosis and airway morphology-needs further validation in order to provide better understanding regarding which diagnostic questions it can be expected to answer. Internationally recognized guidelines for CBCT use in orthodontics are existent, and similar ones should be developed to provide clear indications about the appropriate use of CBCT for upper airway assessment, including a list of specific clinical questions justifying its prescription.