Craniofacial growth and SITAR growth curve analysis.

BACKGROUND: SITAR (SuperImposition by Translation And Rotation) is a shape invariant growth curve model that effectively summarizes somatic growth in puberty. AIM: To apply the SITAR model to longitudinal mandibular growth data to clarify its suitability to facial growth analysis. SUBJECTS AND METHODS: 2D-cephalometric data on two mandibular measurements (AP: articulare-pogonion; CP: condylion-pogonion) were selected from the Denver Growth Study, consisting of longitudinal records (age range: 7.9-19.0 years) of females (sample size N: 21; number of radiographs n: 154) and males (N: 18; n: 137). The SITAR mixed effects model estimated, for each measurement and gender separately, a mean growth curve versus chronological age, along with mean age at peak velocity (APV) and peak velocity (PV), plus subject-specific random effects for PV and mean size. The models were also fitted versus Greulich-Pyle bone age. RESULTS: In males, mean APV occurred at 14.6 years (AP) and 14.4 years (CP), with mean PV 3.1 mm/year (AP) and 3.3 mm/year (CP). In females, APV occurred at 11.6 years (AP and CP), with mean PV 2.3 mm/year (AP) and 2.4 mm/year (CP). The models explained 95-96 per cent of the cross-sectional variance for males and 92-93 per cent for females. The random effects demonstrated standard deviations (SDs) in size of 5.6 mm for males and 3.9 mm for females, and SDs for PV between 0.3 and 0.5 mm/year. The bone age results were similar. CONCLUSION: The SITAR model is a useful tool to analyse epidemiological craniofacial growth based on cephalometric data and provides an array of information on pubertal mandibular growth and its variance in a concise manner.

Evidence of secular trend in mandibular pubertal growth.

BACKGROUND: During puberty, mandibular growth follows a growth curve comparable to somatic growth. This study aimed to review the relationship between mandibular pubertal peak height velocity (PHV) and skeletal age, and to investigate the possibility of a secular trend. METHODS: Retrospective analysis was performed of two historical craniofacial growth studies (Denver Growth Study; observational time: 1943-1965, and Zurich Growth Study; observational time: 1982-1984) of healthy untreated subjects. Two mandibular growth measures (Articulare-Pogonion [Ar-Pg], Condylion-Pogonion [Co-Pg]) were retrieved from cephalograms (n: 990) and corresponding skeletal age based on hand-wrist radiographs. Mandibular growth velocity was related to skeletal age, PHV was established by use of cubic smoothing splines and variability was calculated by bootstrap resampling for every growth study and gender separately. RESULTS: Sexual dimorphism in mandibular growth was apparent in both cohorts. In subjects of the Denver Growth Study, mandibular PHV occurred at a more advanced skeletal age than in subjects of the Zurich Growth Study. This trend was more pronounced in males, for whom PHV of Co-Pg shifted from 14.4 to 13.8 years and of Ar-Pg from 14.6 to 13.7 years. This tendency was more subtle in females: PHV of Co-Pg shifted from 12.7 to 12.4 years and of Ar-Pg from 12.6 to 11.8 years. CONCLUSIONS: Mandibular growth appears to be subject to a secular trend. When related to skeletal age, this secular trend seems to be more accentuated than the established secular trend for somatic pubertal growth.

Structural, morphological, compositional, and mechanical changes of palatal implants after use: a retrieval analysis.

PURPOSE: The aim of this study was to characterize the surface, elemental, and mechanical alterations of orthodontic palatal implants after intraoral aging. MATERIALS AND METHOD: Nineteen consecutively retrieved implants (RET) after orthodontic treatment and three unused implants used as control (CON) were included in this study. Both groups were characterized non-destructively by Stereomicroscopy, Optical Profilometry (Sa, Sq, Sz, Sc), and SEM/EDX analysis and then destructively after metallogaphic preparation employing instrumented indentation testing (HM, EIT, ηIT, and HV) and SEM/EDX at bone-implant interface. RESULTS: All retrieved implants showed a loss of gloss with the formation of bone-like formation on the majority of them. However, no differences in surface roughness parameters were identified between macroscopically intact and retrieved regions of implants. The elements precipitated on the surface were O, C, Ca, and P while traces of Na, K, Al, S, Cl, and Mg were also identified. The surface of control sample is characterized by small pits while only Ti and Al traces were identified by EDX analysis. The presence of all the aforementioned elements apart from Ti and Al on the retrieved implants' surface should be appended to the contact of implant with bone and biological fluids while Interfacial analysis revealed a well-formed bone-implant interface. However, no significant differences were found for all mechanical properties tested between RET and CON groups. CONCLUSIONS: The results of this study indicate that retrieved palatal implant surface has undergone morphological and elemental alterations probably associated with the osseointegration process during service. Insertion and functional loading did not affect the mechanical properties of implants tested.

Effect of different incisor movements on the soft tissue profile measured in reference to a rough-surfaced palatal implant.

INTRODUCTION: The aim of this study was to evaluate soft tissue profile changes after a wide range of incisor movements in the anterior and posterior directions in nongrowing patients. Identifying baseline values more prone to substantial soft tissue profile changes was of high interest. METHODS: For this retrospective study, 47 pairs of lateral cephalograms of nongrowing white patients were superimposed. The cephalograms were taken with the same palatal implant in situ before and after treatment. To increase the accuracy of the measurements, the palatal implants were used as stable reference structures in close relation to the incisors. RESULTS: Horizontal changes of the most anterior point of the maxillary incisor showed a significant correlation to horizontal changes of the upper and lower lips (P <0.001). For every millimeter of horizontal change of the most anterior point of the maxillary central incisor, a change of 0.59 mm at labrale superior can be expected. Also, the angulations of the upper and lower lips were significantly correlated to the most anterior point of the maxillary incisor. Lip retraction was less pronounced in patients with initially thicker lips than in those with thinner lips. CONCLUSIONS: The major contributing factors for predicting the soft tissue profile change during orthodontic treatment are the amount of horizontal movement of the most anterior point of the maxillary incisor, the amount of bite opening, and the initial lip thickness. Although there are significant correlations between dental movements and soft tissue changes in larger samples, predictions for individuals may be inconsistent.

New perspectives on the relationship between mandibular and statural growth.

BACKGROUND: Condylar and somatic growth have similar growth curves. The aim of this study was to compare both growth curves in untreated subjects at different ages and investigate if a correlation factor (CF) could be established. MATERIAL AND METHODS: Semi-longitudinal records (cephalograms and body height) of 418 untreated, healthy children (193 girls and 225 boys) from a craniofacial growth study were analyzed. Incremental changes of three mandibular measurements from articulare and three from condylion were compared to statural growth changes separately. Based on the assumption that mandibular and somatic growth both follow a parallel line, a CF was postulated and checked for validity and reliability. RESULTS: Mandibular growth spurt could be observed in all six different mandibular measurements, but distances from condylion were more informative. Gonial measurements were not as indicative as symphyseal distances. Mandibular growth did not coincide with somatic growth precisely, and condylar peak velocity preceded statural peak velocity in boys and was slightly delayed in girls. CF was close to the value of 0.4, and its validity could be ascertained when using the condylion-gnathion distance for all ages in girls and up to the age of 12 in boys. Reliability, however, proved to be poor owing to heterogeneity of the sample. CONCLUSIONS: Although the relationship between mandibular and statural growth increments can be expressed as a CF with some degree of adequacy, the variance rendered CF unreliable. When evaluating growth-related changes, condylion should be preferred as condylar reference, and symphyseal landmarks should be favoured over gonion.

Is early TMJ involvement in children with juvenile idiopathic arthritis clinically detectable? Clinical examination of the TMJ in comparison with contrast enhanced MRI in patients with juvenile idiopathic arthritis.

BACKGROUND: To test clinical findings associated with early temporomandibular joint (TMJ) arthritis in comparison to the current gold standard contrast enhanced magnetic resonance imaging (MRI) in children with juvenile idiopathic arthritis (JIA). METHODS: Seventy-six consecutive JIA patients were included in this study. Rheumatological and orthodontic examinations were performed blinded to MRI findings. Joint effusion and/or increased contrast enhancement of synovium or bone as well as TMJ deformity were assessed on MRI and compared to clinical findings. The maximal mouth opening capacity (MOC) of the JIA patients was compared to normative values obtained from a cohort of 20719 school children from Zürich, Switzerland. RESULTS: On MRI a total of 54/76 (71%) patients and 92/152 (61%) joints had signs of TMJ involvement. MRI showed enhancement in 85/152 (56%) and deformity in 39/152 (26%) joints. MOC, asymmetry and restriction in condylar translation showed significant correlation to TMJ enhancement and deformity, whereas antegonial notching was correlated with TMJ deformity only. When joints with deformity were excluded, enhancement alone did not show a significant correlation with any clinical factor. CONCLUSIONS: Clinical findings in affected TMJs are correlated with structural damage only. Therefore clinical assessment of TMJs does not allow to diagnose early arthritis accurately and will still depend on contrast enhanced MRI.

Method of visualisation influences accuracy of measurements in cone-beam computed tomography.

This study evaluated the potential impact of different visualisation methods of cone-beam computed tomography (CBCT) on the accuracy of linear measurements of calcified structures, and assessed their interchangeability. High resolution (0.125 mm voxel) CBCT scans were obtained from eight cadaveric heads. The distance between the alveolar bone ridge and the incisal edge was determined for all mandibular incisors and canines, both anatomically and with measurements based on the following five CBCT visualisation methods: isosurface, direct volume rendering, multiplanar reformatting (MPR), maximum intensity projection of the volume of interest (VOIMIP), and average intensity projection of the volume of interest (VOIAvIP). All radiological methods were tested for repeatability and compared with anatomical results for accuracy, and limits of agreement were established. Interchangeability was evaluated by reviewing disparities between the methods and disclosing deterministic differences. Fine intra- and inter-observer repeatability was asserted for all visualisation methods (intraclass correlation coefficient ≤0.81). Measurements were most accurate when performed on MPR images and performed most disappointingly on isosurface-based images. Direct volume rendering, VOIMIP and VOIAvIP achieved acceptable results. It can be concluded that visualisation methods influence the accuracy of CBCT measurements. The isosurface viewing method is not recommended, and multiplanar reformatted images should be favoured for linear measurements of calcified structures.

Assessing the length of the mandibular ramus and the condylar process: a comparison of OPG, CBCT, CT, MRI, and lateral cephalometric measurements.

BACKGROUND/OBJECTIVES: To compare different imaging procedures [cone beam computed tomography (CBCT), computed tomography (CT), magnetic resonance imaging (MRI), orthopantomography (OPG), and lateral cephalometry (LC)] for assessing the mandibular height [ramus height (RH)] and condylar process (CondProc) length as they reflect mandibular growth. MATERIALS/METHODS: The RH and CondProc of eight cadaver heads (each side separately) were measured using CBCT, CT, MRI, OPG, and LC. They were measured twice by two independent observers parallel to the posterior border of the mandibular ramus. An intraclass correlation coefficient (ICC) was used to assess the inter- and intraobserver reliability. The coefficient of variation was used to elucidate precision. Bland-Altman (BA) plots were used to assess the agreement between the procedures and the intra- and interobserver measurements. RESULTS: All procedures, with the exception of LC, showed good intra- and interobserver agreement (maximum range of agreement: 5.3mm) and excellent reliability (ICC > 0.9). The BA plot analysis for the CondProc and RH showed similar ranges of agreement between MRI, CT, and CBCT (maximum 6.4mm) but higher ranges for OPG and LC. The MRI and OPG values were generally smaller. CONCLUSIONS/IMPLICATIONS: All 3D imaging procedures yielded nearly equal results when used to measure the CondProc and RH. MRI is recommended because it avoids ionizing radiation and has higher sensitivity in the detection of inflammation. A 2-year threshold for detecting growth in the follow-up period should be taken into account for all 3D imaging methods. Measuring the RH is recommended for the follow-up of condylar growth because reference values for annual increments are published.

Temporary anchorage device usage: a survey among Swiss orthodontists.

BACKGROUND: The aim of the survey was to obtain information on the treatment plan preferences, mechanics and characteristics of temporary anchorage device (TAD) application using a single case presented to orthodontists in Switzerland. METHODS: A structured questionnaire to be completed by all study participants with case-specific (treatment plan including mechanics and TAD usage) and general questions (general fixed appliance and TAD usage as well as professional, educational and demographic questions) together with an orthodontic borderline case was utilised. The case was a female adult with dental Class II/2, deep bite and maxillary anterior crowing, who had been treated in childhood with extraction of four premolars and fixed appliance followed by wisdom tooth extraction. RESULTS: The response rate was 24.4% (108 out of 443). The majority (96.3%, 104) proposed comprehensive treatment, while 3.7% (4) planned only alignment of maxillary teeth. 8.3% (9) included a surgical approach in their treatment plan. An additional 0.9% (1) combined the surgical approach with Class II mechanics. 75.1% (81) decided on distalization on the maxilla using TADs, 7.4% (8) planned various types of Class II appliances and 3.7% (4) combined distalization using TADs or headgear with Class II appliances and surgery. Palatal implants were the most popular choice (70.6%, 60), followed by mini-screws (22.4%, 19) and mini-plates on the infrazygomatic crests (7.0%, 6). The preferred site of TAD insertion showed more variation in sagittal than in transversal dimension, and the median size of mini-screws used was 10.0-mm long (interquartile range (IQR) 2.3 mm) and 2.0-mm wide (IQR 0.3 mm). CONCLUSIONS: Distalization against palatal implants and then distalization against mini-screws were the most popular treatment plans. Preferred site for TAD insertion varied depending on type and size but varied more widely in the sagittal than in the transversal dimension.

The inclination of mandibular incisors revisited.

OBJECTIVE: To reassess the inclination of lower incisors and evaluate possible associations with gender, age, symphyseal parameters, and skeletal pattern. MATERIALS AND METHODS: Twelve hundred and seventy-two (605 females, 667 males) cephalograms of untreated subjects of a craniofacial growth study (age: 8-16 years) were evaluated. Correlations between the angulation of the lower incisors and age, symphyseal distances (height, width, and depth), symphyseal ratios (height-width, height-depth), and skeletal angles (divergence of the jaws and gonial angle) were investigated for all ages separately and for both sexes independently. RESULTS: The inclination of lower incisors increased over age (8 years: girls = 93.9° [95% CI, 92.3°-95.7°], boys = 93.3° [95% CI, 91.8°-94.9°]; 16 years: girls = 96.1° [95% CI, 94.1°-98.2°], boys = 97.1° [95% CI, 95.6°-98.6°]). Inclination of lower incisors correlated with the divergence of the jaws for all ages significantly or highly significantly, except for boys and girls 9 years of age and girls 11 and 12 years of age, for which only a tendency was observed. Similarly, a strong correlation to gonial angle could be observed. No correlation could be found between the inclination of lower incisors and any symphyseal parameters (absolute measurements and ratios), except for symphyseal depth. CONCLUSION: Lower incisor inclination is linked to the subject's sex, age, and skeletal pattern. It is not associated with symphyseal dimensions, except symphyseal depth. Factors related to natural inclination of lower incisors should be respected when establishing a treatment plan.

Dentofacial and upper airway characteristics of mild and severe class II division 1 subjects.

The aim of this retrospective, cross-sectional study was to assess whether mild and severe Class II division 1 subjects have craniofacial and upper airway characteristics, which relate to the severity of Class II as judged by overjet or ANB angle. The sample consisted of pre-treatment lateral cephalograms and dental casts of 131 males and 115 females (mean age 10.4 ± 1.6). Inclusion criteria were: healthy Caucasian subjects, at least ¾ Class II first molar relationship on both sides and overjet ≥ 4 mm. The cephalograms were traced and digitized. Distances and angular values were computed. Mild and severe Class II was defined by overjet (<10 mm/≥ 10 mm) or by ANB angle (<7 degrees/≥7 degrees). Statistics were performed with two-sample t-test and Pearson's correlation analysis. In the two overjet groups, significant differences were mainly found for incisor inclination while the two ANB groups differed significantly in SNA, WITS, Go-Pg, SpaSpp/MGo, SN/MGo, and Ar-Gn. The shortest airway distance between the soft palate and the posterior pharyngeal wall was significantly correlated to the NS/Ar angle. Statistical analysis revealed several significant correlations. Patients with a large overjet or ANB angle differed significantly from patients with a small overjet or ANB angle mainly in their incisor inclination. In the present sample, the overjet and to some extent also the ANB angle is determined by soft tissue or individual tooth position rather than by skeletal background. In retrognathic patients, a tendency towards smaller airway dimensions was found. However, statistical analysis did not reveal a strong connection between upper airway and dentoskeletal parameters, but a large interindividual variation.

Cervical vertebrae anomalies in subjects with Class II malocclusion assessed by lateral cephalogram and cone beam computed tomography.

A high prevalence of cervical vertebrae anomalies (CVA) has been recently associated with various malocclusions. Our aim was to study the prevalence of CVA on lateral cephalograms in Class II subjects and to compare the findings with those obtained from cone beam computed tomography (CBCT). Standardized cephalograms of 238 Class II patients were analysed for CVA. Cephalogram and CBCT were available for an additional 21 subjects. Cephalometric values were correlated with vertebrae morphology; logistic regressions and intraobserver agreement were evaluated. Inspection of lateral cephalograms could exclude CVA in 90.3 per cent of the subjects, while 9.7 per cent showed potential fusions. No correlations were found between the cephalometric values and potential vertebrae anomalies. In the 21 patients with a CBCT and a lateral cephalogram, the visual assessment of the cephalogram yielded a potential fusion in nine cases. None could be confirmed by CBCT. A low number of potentially fused cervical vertebrae could be detected on lateral cephalograms. The possible fusions did not correlate to any cephalometric values nor could they be confirmed by CBCT, the gold standard for assessing CVA. Visual examination of a cephalogram may result in a false-positive finding and does not allow reliable diagnosis of CVA.