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.

Long-term occlusal tooth wear at the onset of permanent dentition.

OBJECTIVES: This study quantified the long-term occlusal wear in the natural posterior teeth and the associations per tooth type within the dentition. METHODS: The sample included 70 orthodontically treated subjects (52 females and 18 males; median age, 14.3 years), followed for a 12.7-year period. They were consecutively selected with no tooth wear-related criteria. Post-treatment (T1) and follow-up dental casts (T2) were scanned and superimposed through three-dimensional methods. Occlusal wear volume of posterior teeth and tooth wear patterns were investigated through non-parametric statistics and analysis of covariance. RESULTS: There were no significant differences between contralateral teeth. The average occlusal wear per posterior tooth was 2.3 mm3, with 65.2% of teeth showing values greater than 1 mm3. Males, mandibular teeth, and first molars exhibited slightly greater wear levels than females (median, 2.57 and 2.21 mm3, respectively; p = 0.005), maxillary teeth, and first or second premolars, respectively. In all first premolars and in the mandibular second premolars, the buccal cusps were primarily affected with no other distinct patterns. There were weak to moderate correlations between tooth types, apart from certain strong correlations detected in males. CONCLUSIONS: Posterior tooth wear was highly prevalent after a 13-year period starting at the onset of permanent dentition. The detected patterns are in accordance with the concept of canine guidance occlusion that is transforming into group synergy through function. CLINICAL RELEVANCE: The widespread tooth wear occurrence and the high intra- and inter-individual variability underline the need for individual patient monitoring to identify high-risk patients at early stages.

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.

Palatal canine impaction is associated with craniofacial shape in humans.

BACKGROUND/OBJECTIVES: It is unclear whether palatal canine impaction is related to genetic or local/environmental factors. If a genetic origin is assumed, then it could be expected that palatal canine impaction is associated with overall craniofacial development. Within this context, the aim of this study was to evaluate the craniofacial morphology of individuals with palatal canine impaction and compare it to a matched group of normal controls. MATERIALS/METHODS: The sample for this investigation comprised 404 individuals (232 females and 172 males). Half of these individuals presented with unilateral or bilateral palatal canine impaction confirmed clinically and radiographically. The other half were matched for sex and age with the first half and comprised individuals without tooth impaction, apart from third molars. The shape of the craniofacial structures was outlined on calibrated cephalometric images through 15 curves and 127 landmarks (11 fixed and 116 semi-landmarks). Shape configurations were superimposed using Procrustes Superimposition and the resulting shape coordinates were reduced into principal components for all subsequent analyses. The effect of palatal canine impaction on craniofacial shape was assessed with regression models, separately in females and males. All statistical tests were performed assuming a type-1 error of 5%. RESULTS: Individuals with palatally impacted canines appear to have a less convex face, a more brachyfacial skeletal pattern, and a sagittally extended premaxilla. In females effect sizes ranged between η2 = 0.136-0.397 (P < 0.05) and in males between η2 = 0.125-0.396 (P < 0.05, apart from the entire craniofacial configuration: P = 0.259). LIMITATIONS: Palatal canine impaction was not confirmed through cone beam computer tomography images in all patients, however, in those cases, the treatment history confirmed the diagnosis. CONCLUSIONS/IMPLICATIONS: Palatal canine impaction is related to a distinct craniofacial shape in females and males. These findings allow for speculation that palatal canine impaction is affected by genetic pathways involved in overall craniofacial development.

Accurate gingival recession quantification using 3D digital dental models.

OBJECTIVES: To develop and validate a method for accurate quantitative assessment of gingival recessions based on superimposition of serial 3D digital models. MATERIALS AND METHODS: Gingival recessions of mild (0.5-2 mm) and increased (3-7 mm) severity were simulated on stone casts and surface models were created. The outlines of the gingival margins of the mild (A) and severe recessions (B) were compared to the original gingival margins following 3D best fit superimposition through a gold standard technique (GS), which used intact adjacent structures, and the tested method (CC), which used single tooth crowns at the position of recessions, as superimposition reference. The primary outcome was the distance between the most apical point of each corresponding gingival margin along the respective tooth long axis. RESULTS: For mild recessions, the median difference of the test methods (CC_A) from the reference method (GS_A) was 0.008 mm (IQR: 0.093; range: - 0.143, 0.147). For severe recessions, the median difference of the test method (CC_B) from the reference method (GS_B) was 0.009 mm (IQR: 0.091; range: - 0.170, 0.198). The proposed method (CC) showed very high intra- and inter-operator reproducibility (median: 0.025 and 0.033 mm, respectively). CONCLUSIONS: The suggested method offers highly accurate monitoring of gingival margin changes and diagnosis of gingival recessions using 3D digital dental models. The method is applicable irrespective of changes in tooth position or form, allowing for assessments over any time span. CLINICAL RELEVANCE: The accurate detection and visualization of gingival margin changes in 3D will enhance diagnosis and patient-doctor communication.

Superimposition of serial 3-dimensional facial photographs to assess changes over time: A systematic review.

INTRODUCTION: Superimpositions of 3-dimensional photographs enable a thorough and risk-free assessment of facial changes over time. However, the available methods and the evidence supporting them have not been assessed systematically. The paper summarizes and assesses the current evidence on superimposition methods of serial 3-dimensional facial photographs available in the literature. METHODS: The following databases were searched without time restriction (last updated December 2020): MEDLINE via PubMed, EMBASE, Cochrane Library, and Google Scholar. Unpublished literature was searched on Open Grey and Grey Literature Report. Authors were contacted if necessary, and reference lists of relevant papers were screened. All studies with sample size ≥6 that tested the accuracy or precision of a superimposition technique, or agreement between different techniques regarding facial surface changes, were considered. The 2 authors performed data extraction independently using predefined forms. The risk of bias was assessed through the Quality Assessment and Diagnostic Accuracy Tool 2 tool. RESULTS: Eight studies fulfilled the inclusion criteria. The total risk of bias of 7 studies was high and of 1 low. Seven studies had high total applicability concerns, and 1 was unclear. There was high heterogeneity among studies, which tested constructed planes through manually selected landmarks, a configuration of 9 landmarks, various surface areas, and the entire facial surface as superimposition references. A small rectangular area on the forehead combined with one on the middle part of the nose and the lower wall of the orbital foramen showed promising results. CONCLUSIONS: The limited available evidence suggests that surface-based registration is superior to landmark-based registration. Further research in the field is mandatory.

Reliability of cephalometric superimposition for the assessment of craniofacial changes: a systematic review.

BACKGROUND: Superimposition of serial cephalometric radiographs enables the assessment of craniofacial changes over time, and therefore, several methods have been suggested in the literature. OBJECTIVE: The aim of the present study is to summarize and critically evaluate the available evidence on the reliability of methods used to superimpose serial cephalometric radiographs. SEARCH METHODS: Electronic searches were performed in MEDLINE, EMBASE, Google Scholar, and Cochrane Databases, without time limit (last update: 1 November 2020). Unpublished literature was searched on the Open Grey and Grey Literature Report databases. SELECTION CRITERIA: Studies that tested the accuracy, precision, or agreement between different cephalometric superimposition techniques, used to evaluate the craniofacial changes due treatment or growth. DATA COLLECTION AND ANALYSIS: Reference lists of relevant articles were screened and authors were contacted, if needed. All study selection steps, data extraction, and risk of bias (QUADAS-2 tool) assessments were performed independently by two authors on predefined forms. RESULTS: There were 27 eligible studies. From these, 17 tested superimpositions methods on the anterior cranial base, 10 on the maxilla and 12 on the mandible. There were three studies that compared superimpositions on the cranial base with those on the maxilla and one that compared the cranial base with the mandibular superimposition. There was high heterogeneity among studies in terms of sample size, growth, radiographic machines, selection criteria, superimposition methods, references, and outcomes measured. Furthermore, almost all studies presented important methodological limitations, with only two studies having unclear risk of bias and the rest 25 presenting high risk. CONCLUSIONS: Currently, there is no cephalometric superimposition method that has been proved to deliver accurate results. There is an urgent need for further research in this topic, since this is a primary assessment method to assess craniofacial changes over time for several relevant disciplines. REGISTRATION: PROSPERO (CRD42020200349).

Effect of the timing of second molar bonding on the duration of the mandibular arch levelling: a randomized clinical trial.

INTRODUCTION: This study investigated the effect of the timing of second molar bonding on the time required for the levelling of the mandibular dental arch. TRIAL DESIGN: Single-centre two-arm parallel randomized clinical trial using random permuted blocks. Allocation concealment was achieved through sealed envelopes. There was blinding in outcome assessment, but not of patient or operator. METHODS: Thirty-six patients (12-18 years old) with mild to moderate crowding and fully erupted mandibular second molars were assigned randomly (1:1 ratio) in two groups. Group A started fixed orthodontic treatment by bracket bonding in both jaws. Initial wire was 0.014" NiTi. Lower second molar tubes were bonded at the time of 0.016" x 0.022" NiTi wire placement. Group B was same as Group A, but second lower molars were bonded at the first appointment. Placement of the 0.017" x 0.025" stainless steel wire in the mandibular arch was considered the primary endpoint of the trial, indicating the completion of the levelling phase. The days required from bonding to the endpoint comprised the main outcome. Non-parametric statistics were applied. RESULTS: There were two dropouts in each group. The compared groups had similar baseline characteristics regarding age, sex, overjet, overbite, space in the dental arch, average Curve of Spee (CoS), and maximum CoS. Group A tended to require more days for levelling (median: 203 days) than Group B (median: 168 days). However, this difference was not statistically significant (P = 0.128). From the tested occlusal factors, only initial overjet was found to be moderately associated with the days required to complete levelling of the mandibular arch (r = 0.45, P = 0.009). CONCLUSIONS: In the frame of the current study, the duration of the levelling phase of orthodontic treatment with fixed appliances was not affected by the timing of second molar inclusion in the appliance. Future research could aim in cases with deep CoS to generalize the present findings and in larger sample sizes.

Palatal rugae positional changes during orthodontic treatment of growing patients.

OBJECTIVES: To investigate the anteroposterior and vertical changes of the median rugae area, which is commonly used as dental model superimposition reference, relevant to its underlying skeletal structures. SETTINGS AND SAMPLE POPULATION: Retrospectively collected pre- and post-treatment cephalometric radiographs and 3D digital dental models of 24 orthodontic patients (age at treatment start: 12.26 ± 0.83 years; assessment period: 2.13 ± 0.68 years) were analysed. All had mild to moderate malocclusions that were treated non-extraction with full fixed appliances. MATERIAL AND METHODS: The incisive papilla and rugae points were placed on the dental models that were then registered to the cephalometric radiographs. Afterwards, the radiographs were superimposed on Sella, ANS-PNS, and through a maxillary structural method. The vertical and horizontal movements of the papilla and the rugae points, as well as of a central incisor, were measured (Viewbox 4 software). RESULTS: The incisive papilla and the three rugae points remained stable anteroposteriorly, but moved downwards in the vertical dimension (approximately 1-2 mm), in a similar manner (P > .05). However, the anteroposterior position of the papilla and the first rugae points were affected by changes in anterior tooth position and inclination (P < .05). CONCLUSION: Both the second and third rugae can be used as superimposition references for tooth movement assessment. The use of the papilla and the first rugae area is not recommended, because they are affected by tooth movement. The outcomes of a palatal superimposition are comparable to those of a maxillary skeletal superimposition in the anteroposterior, but not in the vertical dimension.

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.

Assessment of techniques used for superimposition of maxillary and mandibular 3D surface models to evaluate tooth movement: a systematic review.

BACKGROUND: Superimposition of three-dimensional (3D) digital models offers great opportunities to assess tooth movement during time. In the literature, several superimposition techniques are described. OBJECTIVES: To summarize and critically assess the available evidence from studies on serial digital 3D dental model superimposition. SEARCH METHODS: MEDLINE via Ovid and PubMed, EMBASE via Ovid, Cochrane Register of Diagnostic Test Accuracy Studies, and Google Scholar were searched with no time limit (last update: December 2018). Hand and unpublished literature searches were also performed. SELECTION CRITERIA: Studies of any design that had a sample size ≥5 and tested superimposition of serial 3D digital dental models to assess tooth movement were included. DATA COLLECTION AND ANALYSIS: Study selection, data extraction, and risk of bias assessment were performed independently by the authors. RESULTS: Twelve studies met the eligibility criteria. The total risk of bias (QUADAS-2 tool) of 10 studies was high, whereas only 2 studies had unclear bias. Ten studies had high and two studies low overall applicability concerns. From these, one study tested the mandibular alveolar bone area, three studies the rugae area, nine studies a larger palatal area, and two studies the incisive papilla area. The high heterogeneity in samples, outcomes, and methods did not allow for synthesis of a considerable amount of studies in any case. LIMITATIONS: The high heterogeneity among studies and the limited evidence did not allow for solid conclusions. CONCLUSIONS AND IMPLICATIONS: The following areas of the maxilla could provide reliable outcomes: (1) the medial two-thirds of the third rugae and the area 5 mm dorsal to them and (2) an area including all rugae, with the lateral margins located at least 5 mm from the gingival margins and a distal margin that does not extend beyond the first molars. No recommendation is possible for other regions of the mouth. There is an urgent need for further research in the field. REGISTRATION: PROSPERO (CRD42019124365).

Success of palatal implants or mini-screws placed median or paramedian for the reinforcement of anchorage during orthodontic treatment: a systematic review.

Objectives: To assess the failure rates of palatal implants and palatal mini-screws, independently and comparatively, used for supplementing anchorage during orthodontic treatment. Protocol and registration: The protocol was not registered prior to the study. This study was not registered in any publicly assessable database. Materials and methods: Screening for inclusion eligibility, quality assessment of studies, and data extraction was performed independently by two authors. The electronic databases MEDLINE, EMBASE, and CENTRAL, as well as unpublished literature, were searched with no restrictions on publication date or language using detailed strategies. The main outcome assessed was palatal implant or mini-screw failure. Randomized controlled trials were evaluated according to the Cochrane risk of bias tool. Prospective and retrospective studies were graded employing the adjusted predetermined criteria of Bondemark. Results: Twenty-seven studies satisfied the inclusion criteria. Four were RCTs of low risk of bias, 12 were prospective (2 low, 7 unclear, 3 high risk of bias) and 11 were retrospective studies (6 unclear, 5 high risk of bias). Only one retrospective study assessed both palatal implants and mini-screws. Seventeen studies, including the four RCTs, assessed solely palatal implants and nine studies palatal mini-screws. The median failure risk of palatal implants was 6.0 per cent (range: 0.0-26.1%) and of mini-screws 6.1 per cent (range: 0.0-33.3%). The median follow-up period was 17.9 months for palatal implants and 6 months for mini-screws. Limitations: Significant clinical and methodological heterogeneity among studies and highly variable outcomes. Conclusions: Both palatal implants and mini-screws have quite low failure rates that are also comparable, though the median follow-up period of palatal implants was quite larger. Therefore, in regular orthodontic cases, the choice between anchoring devices may rely on other factors, such as costs, patient comfort, personal preferences, familiarity with the device, and insertion procedures.

Effect of orthodontic treatment with 4 premolar extractions compared with nonextraction treatment on the vertical dimension of the face: A systematic review.

INTRODUCTION: Our aim was to assess the available evidence for the effects of orthodontic treatment with 4 premolar extractions on the skeletal vertical dimension of the face compared with nonextraction treatment. METHODS: Electronic database searches (MEDLINE, EMBASE, Cochrane Oral Health Group's Trials Register, and CENTRAL) of published and unpublished literature and hand searches of eligible studies were performed, with no language or publication date restrictions. Two authors performed data extraction independently and in duplicate. Risk of bias was assessed. RESULTS: After application of the eligibility criteria, 14 studies were included in this systematic review. All were retrospective. Risk of bias ranged from moderate to critical. Ten studies investigated patients with various skeletal vertical patterns and classes of malocclusion and found no difference between extraction (Ex) and nonextraction (Nonex) treatment in regard to the vertical dimension. Only 2 studies found statistically significant increases in the nonextraction groups, one in N-Me (Ex: +1.5 mm; Nonex: +5.5 mm; P <0.05) and one in SN-GoGn (Ex: -0.9°; Nonex: +0.8°; P <0.05), but without a concurrent significant change in other vertical measurements such as FMA. Two other studies showed opposite findings regarding N-Me (Ex: +2.3 mm; Nonex: +0.9 mm; P <0.05) and FMA (Ex: +0.3°; Nonex: -2.0°; P <0.05). CONCLUSIONS: Although the quality of evidence ranged from moderate to low, there was considerable agreement among these studies, suggesting that orthodontic treatment with 4 premolar extractions has no specific effect on the skeletal vertical dimension. Thus, an extraction treatment protocol aiming to reduce or control the vertical dimension does not seem to be an evidence-based clinical approach.

Early anterior crossbite correction through posterior bite opening: a 3D superimposition prospective cohort study.

Objectives: To assess the effectiveness, clinical performance, and potential adverse effects of early anterior crossbite correction through opening of the bite. Subjects and methods: The sample consisted of 16 consecutive patients (8.0 ± 0.9, range: 6.2-9.3 years) with dental anterior crossbite in the mixed dentition who were treated through posterior bite opening. Patients were prospectively followed until a minimum of 6 months post-treatment and there were no drop-outs. Results: In 14 patients (87.5 per cent), the anterior crossbite was corrected. Results remained stable without any retention regime. Active treatment of the successfully treated cases lasted 2.5 months (range: 0.6-8.9). Crossbite correction of central incisors was achieved by a 2.05 mm (range: 0.97-5.45) forward movement and 9.25° (range: 2.32-14.52°) buccal inclination of the crowns (P < 0.05). The antagonists showed spontaneous adaptation of their position in the opposite direction (P < 0.05). No important adverse effects were recorded. Limitations: This was a non-comparative controlled study, on a limited sample. Conclusions: Bite opening is a promising, simple, and non-compliance approach for early dental anterior crossbite correction. The technique of 3D superimposition and analysis of digital models used here, allowed precise evaluation of single tooth movement in all three planes of space.

Apical root resorption due to mandibular first molar mesialization: A split-mouth study.

INTRODUCTION: Our aim was to evaluate the risk of external apical root resorption (EARR) in mesialized mandibular molars due to space closure in patients with unilateral second premolar agenesis. The contralateral side served as the control. METHODS: After application of eligibility criteria, 25 retrospectively selected subjects (median age, 14.9 years; range, 12.0-31.9 years) were analyzed. Space closure (approximately 10 mm) was performed using skeletal anchorage. EARR was measured at the mandibular permanent canines, first premolars, and first molars in the pretreatment and posttreatment orthopantomograms. Measurements were performed by 2 examiners independently and were corrected for distortion and magnification of radiographs, which were assessed in a pilot study. Multivariate analysis of covariance and pairwise comparisons were performed. RESULTS: The mean enlargement factor of the panoramic machine was 29% ± 0.3%. Distortion exceeded 5% only in cases of large positioning errors (>20°). Intraclass correlation coefficients showed strong to almost perfect agreement (mean, 0.80 mm; 95% CI, 0.75-0.85) of the two examiners. Multivariate analysis of covariance resulted in no difference in EARR between the canines and premolars of the space closure and control sides. On the contrary, there was a statistically significant difference between mesialized and nonmezialized molars (0.73 mm; 95% confidence interval, 0.19-1.27). The mean total EARR in each tooth type did not exceed 1 mm. CONCLUSIONS: Space closure through extensive tooth movement in the mandible was identified as a risk factor for EARR. However, the amount of EARR attributed to space closure and the total EARR were not considered clinically significant.

Perceived facial changes of Class II Division 1 patients with convex profiles after functional orthopedic treatment followed by fixed orthodontic appliances.

INTRODUCTION: The aim of this research was to investigate the perceived facial changes in Class II Division 1 patients with convex profiles after functional orthopedic treatment followed by fixed orthodontic appliances. METHODS: Pretreatment and posttreatment profile photographs of 12 Class II Division 1 patients treated with activators, 12 Class II Division 1 patients treated with Twin-block appliances, and 12 controls with normal profiles treated without functional appliances were presented in pairs to 10 orthodontists, 10 patients, 10 parents, and 10 laypersons. The raters assessed changes in facial appearance on a visual analog scale. Two-way multivariate analysis of variance was used to evaluate differences among group ratings. RESULTS: Intrarater reliability was strong in most cases (intraclass correlation coefficients, >0.7). The internal consistency of the assessments was high (alpha, >0.87), both within and between groups. The raters consistently perceived more positive changes in the Class II Division 1 groups compared with the control group. However, this difference hardly exceeded 1/10th of the total visual analog scale length in its highest value and was mostly evident in the lower face and chin. No significant differences were found between the activator and the Twin-block groups. CONCLUSIONS: Although the raters perceived improvements of the facial profiles after functional orthopedic treatment followed by fixed orthodontic appliances, these were quite limited. Thus, orthodontists should be tentative when predicting significant improvement of a patient's profile with this treatment option.

Clinical outcomes of lingual orthodontic treatment: a systematic review.

OBJECTIVES: To assess the available evidence on the effectiveness of lingual orthodontic treatment and related clinical parameters through a systematic review of relevant studies. MATERIALS AND METHODS: Eligible clinical studies published from January 2000 to March 2015 were identified through electronic (five major databases) and hand searches. Risk of bias was assessed using the Cochrane risk of bias tool for prospective studies and a specially designed tool for retrospective studies. RESULTS: From the 3734 articles identified by the search, after application of specific inclusion and exclusion criteria, 16 papers were included in the study. Eleven studies were retrospective, four were prospective, and only one was a RCT. In detail, six studies evaluated differences of the treatment outcome from the pre-treatment set-up prediction, two studies evaluated the effect of treatment on periodontal and microbial parameters, and 10 studies assessed various clinical treatment related parameters. Despite several promising findings, the quality of evidence supporting them was found to be low in most cases. CONCLUSIONS: This systematic review showed encouraging results on the clinical outcome of lingual orthodontic treatment, especially in regards to the achievement of individualized treatment goals and the reduction of decalcifications on the bonded surfaces of the teeth. However, additional well-designed prospective clinical trials with larger samples are needed to confirm those findings. Several aspects of lingual orthodontic treatment were difficult to be conclusively evaluated due to the study design, the heterogeneity, the small samples sizes, and the high risk of bias seen in the majority of the included studies.