Publications by authors named "Konstantinia Almpani"

8 Publications

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Malocclusion Classification on 3D Cone-Beam CT Craniofacial Images Using Multi-Channel Deep Learning Models

Annu Int Conf IEEE Eng Med Biol Soc 2020 07;2020:1294-1298

Analyzing and interpreting cone-beam computed tomography (CBCT) images is a complicated and often time-consuming process. In this study, we present two different architectures of multi-channel deep learning (DL) models: "Ensemble" and "Synchronized multi-channel", to automatically identify and classify skeletal malocclusions from 3D CBCT craniofacial images. These multi-channel models combine three individual single-channel base models using a voting scheme and a two-step learning process, respectively, to simultaneously extract and learn a visual representation from three different directional views of 2D images generated from a single 3D CBCT image. We also employ a visualization method called "Class-selective Relevance Mapping" (CRM) to explain the learned behavior of our DL models by localizing and highlighting a discriminative area within an input image. Our multi-channel models achieve significantly better performance overall (accuracy exceeding 93%), compared to single-channel DL models that only take one specific directional view of 2D projected image as an input. In addition, CRM visually demonstrates that a DL model based on the sagittal-left view of 2D images outperforms those based on other directional 2D images.Clinical Relevance- the proposed method aims at assisting orthodontist to determine the best treatment path for the patient be it orthodontic or surgical treatment or a combination of both.
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http://dx.doi.org/10.1109/EMBC44109.2020.9176672DOI Listing
July 2020

Severity of oro-dental anomalies in Loeys-Dietz syndrome segregates by gene mutation.

J Med Genet 2020 10 8;57(10):699-707. Epub 2020 Mar 8.

Craniofacial Anomalies and Regeneration Section, National Institute of Dental and Craniofacial Research, Bethesda, Maryland, USA

Loeys-Dietz syndrome (LDS), an autosomal dominant rare connective tissue disorder, has multisystemic manifestations, characterised by vascular tortuosity, aneurysms and craniofacial manifestations. Based on the associated gene mutations along the transforming growth factor-beta (TGF-β) pathway, LDS is presently classified into six subtypes. We present the oro-dental features of a cohort of 40 patients with LDS from five subtypes. The most common oro-dental manifestations were the presence of a high-arched and narrow palate, and enamel defects. Other common characteristics included bifid uvula, submucous cleft palate, malocclusion, dental crowding and delayed eruption of permanent teeth. Both deciduous and permanent teeth had enamel defects in some individuals. We established a grading system to measure the severity of enamel defects, and we determined that the severity of the enamel anomalies in LDS is subtype-dependent. In specific, patients with TGF-β receptor II mutations (LDS2) presented with the most severe enamel defects, followed by patients with TGF-β receptor I mutations (LDS1). LDS2 patients had higher frequency of oro-dental deformities in general. Across all five subtypes, as well as within each subtype, enamel defects exhibited incomplete penetrance and variable expression, which is not associated with the location of the gene mutations. This study describes, in detail, the oro-dental manifestations in a cohort of LDS, and we conclude that LDS2 has the most severely affected phenotype. This extensive characterisation, as well as some identified distinguishing features can significantly aid dental and medical care providers in the diagnosis and clinical management of patients with this rare connective tissue disorder.
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http://dx.doi.org/10.1136/jmedgenet-2019-106678DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7525783PMC
October 2020

Insight Into the Ontogeny of GnRH Neurons From Patients Born Without a Nose.

J Clin Endocrinol Metab 2020 05;105(5)

Clinical Research Branch, National Institute of Environmental Health Sciences, Durham, North Carolina.

Context: The reproductive axis is controlled by a network of gonadotropin-releasing hormone (GnRH) neurons born in the primitive nose that migrate to the hypothalamus alongside axons of the olfactory system. The observation that congenital anosmia (inability to smell) is often associated with GnRH deficiency in humans led to the prevailing view that GnRH neurons depend on olfactory structures to reach the brain, but this hypothesis has not been confirmed.

Objective: The objective of this work is to determine the potential for normal reproductive function in the setting of completely absent internal and external olfactory structures.

Methods: We conducted comprehensive phenotyping studies in 11 patients with congenital arhinia. These studies were augmented by review of medical records and study questionnaires in another 40 international patients.

Results: All male patients demonstrated clinical and/or biochemical signs of GnRH deficiency, and the 5 men studied in person had no luteinizing hormone (LH) pulses, suggesting absent GnRH activity. The 6 women studied in person also had apulsatile LH profiles, yet 3 had spontaneous breast development and 2 women (studied from afar) had normal breast development and menstrual cycles, suggesting a fully intact reproductive axis. Administration of pulsatile GnRH to 2 GnRH-deficient patients revealed normal pituitary responsiveness but gonadal failure in the male patient.

Conclusions: Patients with arhinia teach us that the GnRH neuron, a key gatekeeper of the reproductive axis, is associated with but may not depend on olfactory structures for normal migration and function, and more broadly, illustrate the power of extreme human phenotypes in answering fundamental questions about human embryology.
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http://dx.doi.org/10.1210/clinem/dgaa065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7108682PMC
May 2020

Craniofacial Analysis May Indicate Co-Occurrence of Skeletal Malocclusions and Associated Risks in Development of Cleft Lip and Palate.

J Dev Biol 2020 Jan 28;8(1). Epub 2020 Jan 28.

Craniofacial Anomalies and Regeneration Section, NIDCR, NIH, Bethesda, MD 20892-1470, USA.

Non-syndromic orofacial clefts encompass a range of morphological changes affecting the oral cavity and the craniofacial skeleton, of which the genetic and epigenetic etiologic factors remain largely unknown. The objective of this study is to explore the contribution of underlying dentofacial deformities (also known as skeletal malocclusions) in the craniofacial morphology of non-syndromic cleft lip and palate patients (nsCLP). For that purpose, geometric morphometric analysis was performed using full skull cone beam computed tomography (CBCT) images of patients with nsCLP ( = 30), normocephalic controls ( = 60), as well as to sex- and ethnicity- matched patients with an equivalent dentofacial deformity ( = 30). Our outcome measures were shape differences among the groups quantified via principal component analysis and associated principal component loadings, as well as mean shape differences quantified via a Procrustes distance among groups. According to our results, despite the shape differences among all three groups, the nsCLP group shares many morphological similarities in the maxilla and mandible with the dentofacial deformity group. Therefore, the dentoskeletal phenotype in nsCLP could be the result of the cleft and the coexisting dentofacial deformity and not simply the impact of the cleft.
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http://dx.doi.org/10.3390/jdb8010002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151201PMC
January 2020

Surgical Methods for the Acceleration of the Orthodontic Tooth Movement.

Front Oral Biol 2016 24;18:92-101. Epub 2015 Nov 24.

Surgical techniques for the acceleration of the orthodontic tooth movement have been tested for more than 100 years in clinical practice. Since original methods have been extremely invasive and have been associated with increased tooth morbidity and various other gaps, the research in this field has always followed an episodic trend. Modern approaches represent a well-refined strategy where the concept of the bony block has been abandoned and only a cortical plate around the orthodontic tooth movement has been desired. Selective alveolar decortication has been a reproducible gold standard to this end. Its proposed mechanism has been the induction of rapid orthodontic tooth movement through the involvement of the periodontal ligament. More recent techniques included further refinement of this procedure through less invasive techniques such as the use of piezoelectricity and corticision. This chapter focuses on the evolution of the surgical approaches and the mechanistic concepts underlying the biological process during the surgically accelerated orthodontic tooth movement.
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http://dx.doi.org/10.1159/000382051DOI Listing
March 2016

Nonsurgical Methods for the Acceleration of the Orthodontic Tooth Movement.

Front Oral Biol 2016 24;18:80-91. Epub 2015 Nov 24.

While acceleration of the orthodontic tooth movement by surgical techniques has been shown to be effective for decades, noninvasive and nonsurgical methods have always been preferred by both the clinicians and the patients. These techniques have ranged from application of biological molecules to innovative technologies such as resonance vibration, cyclic forces, light electrical currents, magnetic field forces, low-intensity laser irradiation and low-level light therapy. Endogenously produced biologicals have been tested based on their roles in the turnover of alveolar bone in response to orthodontic tooth movement as well as during wound healing. The premise behind this approach is that these exogenously applied compounds will mimic their counterparts produced in vivo. Meanwhile, technologies tested so far target these pathways for the acceleration of the orthodontic tooth movement. All these approaches have shown favorable outcomes with varying success. This chapter presents the current knowledge and a discussion over their limitations with an emphasis on the mechanism of action for each technique.
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http://dx.doi.org/10.1159/000382048DOI Listing
March 2016

Autotransplantation of teeth in humans: a systematic review and meta-analysis.

Clin Oral Investig 2015 Jul 24;19(6):1157-79. Epub 2015 Apr 24.

Aristotle University of Thessaloniki, Thessaloniki, Greece.

Objectives: The aim of this investigation was to assess the currently available evidence concerning the complications and risk factors influencing the outcome of autotransplantation of teeth in humans.

Materials And Methods: Electronic searches were conducted to identify randomized controlled and prospective clinical trials. Risk of bias within studies was assessed with the Downs and Black tool. Random-effects meta-analyses were conducted to pool the adverse event rates and relative risks with their 95% confidence intervals. Risk of bias across studies was assessed with the GRADE framework followed by sensitivity analyses.

Results: Thirty-eight studies were included in the analysis. Reported complications included the need for extraction, failure, hypermobility, pulp necrosis, pulp obliteration, and root resorption. Pooled complication event rates varied considerably, with small studies (<100 teeth) reporting greater complication rates. The analysis of risk factors was associated with both the primary outcome (extraction need) and secondary outcomes (failure, hypermobility, pulp necrosis, pulp obliteration, root resorption). The stage of root development seems to influence both the future survival, as well as the success of the transplanted teeth. Teeth with open apex were less likely to be extracted in comparison to teeth with closed apex (3 studies; 413 teeth; relative risk 0.3; 95% confidence interval 0.2-0.6).

Conclusions: Due to the small number of the contributing studies, their methodological limitations, and the heterogeneous results reported, no firm conclusions can be drawn.

Clinical Relevance: Root development of the donor teeth has been established as one the most important factor related to the success of tooth autotransplantation.
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http://dx.doi.org/10.1007/s00784-015-1473-9DOI Listing
July 2015

Role of third molars in orthodontics.

World J Clin Cases 2015 Feb;3(2):132-40

Konstantinia Almpani, Forsyth Institute, Boston, MA 02115, United States.

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too.
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http://dx.doi.org/10.12998/wjcc.v3.i2.132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4317606PMC
February 2015