Scripta Scientifica Medicinae Dentalis

5

Authors: Tihomir Vasilev, Tsanka Dikova, Dzhendo Dzhendov, Elisaveta Ivanova

The aim of the present paper is to evaluate and compare the strength properties and deformation characteristics of cast and Selective Laser Melted (SLM) Co-Cr dental alloys by using CAD/CAE software. The Solid Works Simulation software is used for simulation of chewing load of the virtual 3D model of a four-part dental bridge. Two Co-Cr dental alloys, cast and SLM were used in this study. During the simulation process by means of linear static analysis the displacements, strains, stresses, and reaction forces under the effect of the applied load were calculated. As a result, the equivalent von Mises stresses, Factor of Safety (FOS) and displacements were evaluated in this study. It was established that the highest values of the equivalent von Mises stresses of cast and SLM bridges are situated in the connectors between the teeth, i.e. the zones with the lowest areas of the cross sections. They are in the range 95-162 MPa, which is lower than the stress limits for the both materials. The minimum FOS of both materials is higher than 1. In the cast bridges it is 1.32-2.64 in the zones with the highest load, while in the SLM samples it is 2.61-5.68. As FOS shows the reserve strength of the material for the applied load, it is obvious that the SLM bridge possesses twice as high reserve strength. This allows optimization of the construction, economy of material and possibility for manufacturing of objects with porous structures.

5

Authors: Vassil Svechtarov, Savina Nencheva - Svechtarova

INTRODUCTION: The aim of this study is to evaluate the distribution of the most common comorbid conditions associated with chronic temporomandibular disorders, and the pharmacological agents which play an integral role in the overall management of temporomandibular joint disorders. MATERIALS AND METHODS: A total of 23 articles are included in this comprehensive review of the relevant studies on common comorbid conditions related to temporomandibular disorders. This review provides summarized clinical and online platform based analyses focused on the five most common comorbid conditions and their relevant pharmacological therapy. RESULTS AND CONCLUSION: The majority of the studies show that comorbid conditions may include fibromyalgia, systemic myofascial pain and chronic fatigue syndrome, chronic headaches, migraine, heart arrhythmias, endometriosis, interstitial cystitis, irritable bowel syndrome, lower back pain, sleep disorders - insomnia, autoimmune diseases, sleep apnea, noises and irritation in the ear, vulvodynia and mental disorders. The top comorbid conditions reported from people with TMJ syndrome, regardless of status are: anxiety, depression, insomnia, fatigue and pain.

7

Authors: Albena Gencheva, Tihomir Georgiev, Hristina Arnautska, Ivan Gonkov, Petyr Chankov, Kamen Nogalchev

AIM: The aim of this research is to demonstrate the necessity of CBCT – examination for evaluation of the surgical approach of high-risk impacted lower third molars. As “high-risk” we defined lower third molars which have signs of proximity to the mandibular canal seen on standard panoramic radiography. MATERIALS AND METHODS: All patients who had undergone a CT examination between September, 2015 and October, 2016 were reviewed. We included images from cone beam computed tomography made in the Department of Radiologic Diagnostics, University Medical and Dental Centre of the Medical University of Varna. The device used was Planmeca ProMax 3D Max with software for images Planmeca Romexis. We chose 100 images randomly. From these images we selected 39 images with high-risk lower third molars. We examined different signs with which we defined the exact position to the mandibular canal of 60 wisdom teeth and we managed to asses the risk of damaging the IAN during a classical odontectomy of these teeth. In the research we included the panoramic radiographs of 20 patients from these 39 cases. RESULTS: From the examination of the CBCT images we found: 28 lower third molars where the mandibular canal runs apical and has contact; 11 where the mandibular canal runs apical in contact with the tooth and penetration of the apices of the tooth is seen; 10 where the mandibular canal runs buccal with contact; 8 where the mandibular canal runs lingual with contact; 3 where the mandibular canal runs between the roots touching one/both of them. In three of the cases we found severe deviation of the root apices. From the examination of the panoramic radiographs we found: 5 cases with darkening of roots in the apical area; 8 with interruption of the white line (lamina dura) of the mandibular canal; 1 with diversion of the mandibular canal with/without narrowing of the mandibular canal; 6 without any of these three signs. CONCLUSION: The development and rapid commercialization of new technologies like CBCT allows us to have precise images and exact diagnosis of the diseases in the oral and maxillofacial area. Our study confirmed the high diagnostic value of CBCT regarding to precise the position of the lower third molars to the mandibular canal and IAN. This gives the clinician the opportunity to determine which lower third molars are “high-risk” teeth and to choose the best method for surgical treatment.