34 research outputs found
Induced Ankylosis of a Primary Molar for Skeletal Anchorage in the Mandible as Alternative to Mini-Implants
Background Mesial protraction of mandibular posterior teeth requires increased anchorage to avoid undesired tooth movements. Orthodontic mini-implants have become a popular and successful way to increase skeletal anchorage in such cases. However, mini-implants may cause injury to adjacent teeth or anatomical structures and may lead to tissue inflammation. Induced ankylosed primary teeth have been used in the past as abutments for the protraction of the maxilla in cases of maxillary retrognathism. However, this technique has not been described in the literature for the protraction of mandibular molars. The aim of this paper is to present, through a case report, an alternative to mini-implant devices to maximize anchorage in the mandible by inducing ankylosis on a primary molar. Findings A 13-year-old female with class II right malocclusion, deep bite, and congenitally missing right second premolars was referred for orthodontic treatment. Treatment plan involved removal of the primary teeth and mesial protraction of the posterior. In the mandible, ankylosis was induced on the retained primary second molar by extraction, bisection, replantation of the mesial part after endodontic treatment, and bonding of a rigid splint. Ankylosis was diagnosed after 10 weeks and a closing T-loop sectional wire was inserted to move the permanent first molar mesially. At 6 months, the remaining space was closed using elastic chain on a rectangular stainless steel wire with tip-back bends, supported by class II elastics. Conclusions Induced ankylosis of primary teeth can be an alternative to orthodontic mini-implants in selected cases, with minimal risks and maximum biocompatibility
Covariance patterns between ramus morphology and the rest of the face: A geometric morphometric study
OBJECTIVE
The growth and development of the mandible strongly depend on modeling changes occurring at its ramus. Here, we investigated covariance patterns between the morphology of the ramus and the rest of the face.
METHODS
Lateral cephalograms of 159 adults (55 males and 104 females) with no history of orthodontic treatment were collected. Geometric morphometrics with sliding semi-landmarks was used. The covariance between the ramus and face was investigated using a two-block partial least squares analysis (PLS). Sexual dimorphism and allometry were also assessed.
RESULTS
Differences in the divergence of the face and anteroposterior relationship of the jaws accounted for 24.1% and 21.6% of shape variation in the sample, respectively. Shape variation was greater in the sagittal plane for males than for females (30.7% vs. 17.4%), whereas variation in the vertical plane was similar for both sexes (23.7% for males and 25.4% for females). Size-related allometric differences between the sexes accounted for the shape variation to a maximum of 6% regarding the face. Regarding the covariation between the shapes of the ramus and the rest of the face, wider and shorter rami were associated with a decreased lower anterior facial height as well as a prognathic mandible and maxilla (PLS 1, 45.5% of the covariance). Additionally, a more posteriorly inclined ramus in the lower region was correlated with a Class II pattern and flat mandibular plane.
CONCLUSIONS
The width, height, and inclination of the ramus were correlated with facial shape changes in the vertical and sagittal planes
Applications of 3D printing on craniofacial bone repair: A systematic review
Objectives
Three-dimensional (3D) bioprinting, a method derived from additive manufacturing technology, is a recent and ongoing trend for the construction of 3D volumetric structures. The purpose of this systematic review is to summarize evidence from existing human and animal studies assessing the application of 3D printing on bone repair and regeneration in the craniofacial region. Data & sources
A rigorous search of all relevant clinical trials and case series was performed, based on specific inclusion and exclusion criteria. The search was conducted in all available electronic databases and sources, supplemented by a manual search, in December 2017. Study selection
43 articles (6 human and 37 animal studies) fulfilled the criteria. The human studies included totally 81 patients with craniofacial bone defects. Titanium or hydroxylapatite scaffolds were most commonly implanted. The follow-up period ranged between 6 and 24 months. Bone repair was reported successful in nearly every case, with minimal complications. Also, animal intervention studies used biomaterials and cells in various combination, offering insights into the techniques, through histological, biochemical, histomorphometric and microcomputed tomographic findings. The results in both humans and animals, though promising, are yet to be verified for clinical impact. Conclusions
Future research should be focused on well-designed clinical trials to confirm the short- and long- term efficacy of 3D printing strategies for craniofacial bone repair. Clinical significance
Emerging 3D printing technology opens a new era for tissue engineering. Humans and animals on application of 3D printing for craniofacial bone repair showed promising results which will lead clinicians to investigate more thoroughly alternative therapeutic methods for craniofacial bone defects
Anterior teeth root inclination prediction derived from digital models : a comparative study of plaster study casts and CBCT images
To assess the accuracy of digital models generated using commercially available software to predict anterior teeth root inclination characteristics and compare the results to relevant data obtained from CBCT images. Following sample size calculation and after application of inclusion and exclusion criteria, pre-treatment maxillary and mandibular plaster models and the corresponding CBCT scans of 31 patients attending a private orthodontic clinic were selected. The subjects were 10 males and 21 females with age range 12 to 40 years. Plaster models were scanned using the high resolution mode of an Ortho Insight 3D scanner and CBCT scans were taken using a Kodak 9500 Cone Beam 3D System machine. The teeth on the digital scans were segmented and virtual roots were predicted and constructed by the Ortho Insight 3D software. The long axes of the predicted roots and the actual roots, as segmented from the CBCT images, were computed using best-fit lines. The inter-axis angle was used to assess error in root inclination prediction by the software. Mann-Whitney and Kruskal-Wallis tests were used. Intra-examiner error was evaluated using the Bland-Altman method. The maximum disparity in angle between images derived from digital models and CBCT data was almost 40 degrees (upper left canine). The upper and lower canines produced the worst results, followed by the lower lateral incisors. The upper central incisors showed the best results, although the maximum angle of difference exceeded 20 degrees (with the median around 8 degrees). Root morphology imaging prediction is not a primary function of this software and this study confirmed its limitation as a sole tool in routine clinical applications. At present these predictions cannot be considered accurate or reliable unless correlated clinically with a radiographic image
Number of Teeth Is Related to Craniofacial Morphology in Humans.
One of the most common dental anomalies in humans is the congenital absence of teeth, referred to as tooth agenesis. The association of tooth agenesis to craniofacial morphology has been previously investigated but remains unclear. We investigated this association by applying geometric morphometric methods in a large sample of modern humans. In line with previous studies, we report here that a reduced teeth number is linked to a less convex profile, as well as to a shorter face. The effects were similar for males and females; they increased as the severity of the tooth agenesis increased and remained unaltered by the inclusion of third molars and of allometry in the analysis. Furthermore, in cases with tooth agenesis only in the maxilla, there was no detectable effect in mandibular shape, whereas maxillary shape was affected independently of the location of missing teeth. The robustness of the present sample along with the shape analysis and the statistical approach applied, allowed for thorough testing of various contributing factors regarding the presence but also the magnitude of effects. The present findings suggest a relationship between number of teeth and overall craniofacial development and have evolutionary implications
Morphometric covariation between palatal shape and skeletal pattern in Class II growing subjects
Objectives
To evaluate the patterns of covariation between palatal and craniofacial morphology in Class II subjects in the early mixed dentition by means of geometric morphometrics.
Methods
A cross-sectional sample of 85 Class II subjects (44 females, 41 males; mean age 8.7 years ± 0.8) was collected retrospectively according to the following inclusion criteria: European ancestry (white), Class II skeletal relationship, Class II division 1 dental relationship, early mixed dentition, and prepubertal skeletal maturation. Pre-treatment digital 3D maxillary dental casts and lateral cephalograms were available. Landmarks and semilandmarks were digitized (239 on the palate and 121 on the cephalogram) and geometric morphometric methods (GMM) were applied. Procrustes analysis and principal component analysis (PCA) were performed to reveal the main patterns of palatal shape and craniofacial skeletal shape variation. Two-block partial least squares analysis (PLS) assessed patterns of covariation between palatal morphology and craniofacial morphology.
Results
For the morphology of the palate, the first principal component (PC1) described variation in all three dimensions. For the morphology of the craniofacial complex, PC1 showed shape variation mainly in the vertical direction. Palatal shape and craniofacial shape covaried significantly (RV coefficient: 0.199). PLS1 accounted for more than 64 per cent of total covariation and related divergence of the craniofacial complex to palatal height and width. The more a Class II subject tended towards high-angle divergence, the narrower and higher was the palate.
Conclusions
Class II high-angle patients tended to have narrower and higher palates, while Class II low-angle patients were related to wider and more shallow palates
Microcollimator for Micrometer-Wide Stripe Irradiation of Cells Using 20–30 keV X Rays
The exposure of subnuclear compartments of cells to ionizing radiation is currently not trivial. We describe here a collimator for micrometer-wide stripe irradiation designed to work with conventional high-voltage X-ray tubes and cells cultured on standard glass cover slips. The microcollimator was fabricated by high-precision silicon micromachining and consists of X-ray absorbing chips with grooves of highly controlled depths, between 0.5-10 mum, along their surfaces. These grooves form X-ray collimating slits when the chips are stacked against each other. The use of this device for radiation biology was examined by irradiating human cells with X rays having energies between 20-30 keV. After irradiation, p53 binding protein 1 (53BP1), a nuclear protein that is recruited at sites of DNA double-strand breaks, clustered in lines corresponding to the irradiated stripes
Morphometric evaluation of soft-tissue profile shape
Introduction: Soft-tissue facial outline has been studied by
conventional cephalometric methods, and differences between the 2 sexes
have been identified, mainly related to size and timing of growth.
However, shape per se was not sufficiently evaluated, especially
regarding variability, age-related changes, and sexual dimorphism. The
purpose of this study was to evaluate shape variability and sexual
dimorphism of the soft-tissue outline by using morphometric methods.
Methods: Pretreatment lateral cephalograms from 170 consecutive patients
(82 male, 88 female) aged 7 to 17 years were used. Fifteen skeletal and
22 soft-tissue landmarks were digitized and processed with Procrustes
superimposition and principal component analysis. The principal
components (PCs) of the soft-tissue shape were analyzed in relation to
age and sex. Results: The first 8 PCs explained approximately 90% of
the total shape variability. The first coefficient (PC1) related to lip,
nose, and chin prominence and included 36% of total shape variability.
It was significantly correlated to age, but with a low coefficient of
determination (r(2) = 13%). The second coefficient (PC2) related to
facial convexity and explained 18% of shape variability. The next 2
coefficients were mainly related to lower lip shape. Statistically
significant sexual dimorphism was detected, but the overall shape
differences between the average profiles of boys and girls were minor
and barely detectable visually. Shape dimorphism was present both before
and after the age of 12 years. Conclusions: Shape variability related
mainly to relative lip protrusion, convexity of the face, and lower lip
shape. Shape differences between the sexes seemed to exist even before
the pubertal growth spurt, but they were small. Age changes in shape
appeared more significant
Morphometric correlation between facial soft-tissue profile shape and skeletal pattern in children and adolescents
Introduction: Prediction of soft-tissue outline shape from skeletal
remains is useful in forensics and archaeology. The inverse problem, the
assessment of underlying skeletal relationships from the external
appearance, is pertinent in orthodontics. The purposes of this study
were to assess the correlation between craniofacial shape and shape of
the soft-tissue profile outline and to determine the extent to which it
might be possible to predict the latter from the former. Methods:
Lateral cephalograms from 170 consecutive orthodontic patients were
used, and 17 skeletal, 2 dental, and 22 soft-tissue landmarks were
digitized and processed by using Procrustes superimposition and
principal component analysis. The principal components of the skeletal
and soft-tissue shapes were entered into the correlation analysis.
Results: Significant correlations were found between the skeletal and
the soft-tissue components. The use of 7 anterior skeletal landmarks
(not including the nasal bone) resulted in a predictive power
(coefficient of determination) of 38% of the variability of soft-tissue
shape. This increased to almost 50% by adding nasal and incisor points
but showed only a slight further improvement by incorporating posterior
skeletal landmarks. Conclusions: Anterior skeletal and dental landmarks
can be used to predict soft-tissue profile shape with a 50% power in
children and adolescents
Morphological integration between the cranial base and the face in children and adults
The primary aim of the present study was to assess morphological covariation between the face and the basicranium (midline and lateral), and to evaluate patterns of integration at two specific developmental stages. A group of 71 children (6-10 years) was compared with a group of 71 adults (20-35 years). Lateral cephalometric radiographs were digitized and a total of 28 landmarks were placed on three areas; the midline cranial base, the lateral cranial base and the face. Geometric morphometric methods were applied and partial least squares analysis was used to evaluate correlation between the three shape blocks. Morphological integration was tested both with and without removing the effect of allometry. In children, mainly the midline and, to a lesser extent, the lateral cranial base were moderately correlated to the face. In adults, the correlation between the face and the midline cranial base, which ceases development earlier than the lateral base, was reduced. However, the lateral cranial base retained and even strengthened its correlation to the face. This suggests that the duration of common developmental timing is an important factor that influences integration between craniofacial structures. However, despite the apparent switch of primary roles between the cranial bases during development, the patterns of integration remained stable, thereby supporting the role of genetics over function in the establishment and development of craniofacial shape