3D modeling is a new technology applied in orthodontics. In this research, this technique was used to evaluate teeth nivelation. In order to do this, with the application of standard geometric modelers (CAD systems), for these investigations, reference geometric entities (RGEs) have been developed, as basic, derivative and anatomical. In this way, orthodontic parameters are defined, and in a new way they perform orthodontic analysis, in the case of a tooth nivelation. A set of 54 orthodontic parameters is defined, 28 for the lower jaw and 26 for the upper jaw. They are monitored in the space, in all three orthodontic levels, through the anatomical points of the teeth. The concept of e personal practice is defined, the developed model for monitoring the position of teeth in the space, the concept of modeling the dental arch using the spline in the occlusal plane was set up and the accuracy of the two scanners was explored. All this has been tested on a case of tooth nivelation. MATERIAL AND METHODS: In these studies, the basic sample covered 155 patients, Clinics for orthodontics, Faculty of Dentistry in Belgrade. The population that made this sample was between the ages from 15 to 26, both sexes. In all of them from the orthodontic point of view, the following problems have been reported: incorrect position of teeth, disturbances, different types of malooclusions, irregular shape of the dental arch. The leveling of the teeth (their position in the area, as well as in the occlusal plane) was observed, which belongs to the first phase of therapy with fixed devices. It includes the following: (i) Leveling of brackets, ie regulation of vertical deviations of individual teeth, (ii) Correction of rotated teeth, (iii) Correction of labio (bucco) lingual tooth deviations, and (iv) Tooth decay (upright). The scan was performed at: Next Engine (Faculty of Dentistry, Belgrade), Atos (Topomatika, Zagreb) and LazakSkan (Faculty of Mechanical Engineering, Ljubljana). The obtained 3D models were processed in the GOM Inspect V8 (V8 Hotfix 6, Rev. 81431) and the orthodontic analysis and synthesis were performed on Solid Works and Siemens PLM NX10 software. As an approach, the approach of generating a 3D digital model was used, and on it, through a concrete example, the definition, measurement and monitoring of RGE, used for orthodontic analysis and synthesis. These studies are based on the application of the following methods: analysis (orthodontic cases, states, parameters, trends, ...), synthesis (therapeutic methods, procedures and procedures, ...), induction (prediction of orthodontic trends for a set versus sample) and deduction (drawing conclusions about the orthodontic condition for each patient separately). Of course, as a basic process for these research, 3D modeling, as a scientific discipline that was first developed in engineering, and here will be applied in orthodontics..., 3D modeliranje je nova tehnologija primenjena u ortodonciji. U ovim istraţivanjima ova tehhnologija je primenjena za praćenje nivelacije zuba. Da bi se to ostvarilo, uz primenu standardnih geometrijskih modelera (CAD sistemi), za ova istraţivanja, su razvijeni referentni geometrijski entiteti (RGE), kao osnovni, izvedeni i anatomski. Na ovaj naĉin se definišu ortodontski parametri, a na novi naĉin vrše ortodontske analize, na primeru nivelacije zuba. Definisan je skup od 54 ortodontska parametra, 28 za donju vilicu i 26 za gornju vilicu. Oni se prate u prostoru, u sve tri ortodontske ravni, preko anatomskih taĉaka zuba. Definisan je konept e personalne ordinacije, razvijen model praćenja poloţaja zuba u prostoru, postavljen koncept modeliranja zubnog luka pomoću splajna u okluzalnoj ravni i istraţena taĉnost dva skenera. Sve ovo testirano je na primeru nivelacije zuba. MATERIJAL I METOD: U ovim istraţivanjima osnovni uzorak je obuhvatio 155 pacijenata, Klinike za ortopediju vilica Stomatološkog fakulteta u Beogradu. Populacija koja je saĉinjavla ovaj uzorak bila je starosti od 15 do 26. godina, oba pola. Kod svih njih sa ortodontske taĉke gledišta, javljali su se sledeći problemi: nepravilan poloţaj zuba, teskoba, malokluzija razliĉitog tipa, nepravilan oblik zubnog luka. Pratila se nivelacija zuba (njihov poloţaj u prostoru, kao i u okluzalnoj ravni), koja spada u prvu fazu terapije fiksnim aparatima. Ona obuhvata sledeće: (i) Nivelaciju bravica, odnosno regulisanje vertikalnih odstupanja pojedinih zuba, (ii) Korekcija rotiranih zuba, (iii) Korekcija labio(buko) lingvalnih odstupanja zuba, i (iv) Uspravljanje zuba. Skeniranje je vršeno na: Next Engine (Stomatološki fakultet, Beograd), Atos (Topomatika, Zagreb) i LazakSkan (Fakultet za strojništvo, Ljubljana). Dobijeni 3D modeli su obraĊeni u programu GOM Inspect V8 (V8 Hotfix 6, Rev. 81431), a ortodontske analize i sinteze su vršene na Solid Works i Siemens PLM NX10 softveru. Kao metod korišćen je prilaz generisanja 3D digitalnog modela, a na njemu, kroz konkretni primer, definisanje, merenje i praćenje RGE, koji su korišćeni za ortodontske analize i sinteze. Ova istraţivanja su zasnovana na primeni sledećih metoda: analiza (ortodontskih sluĉajeva, stanja, parametara, trendova, ...), sinteza (terapijskih metoda, procedura i postupaka, ...), indukcija (predviĊanje ortodontskih trendova za skup u odnosu na uzorak) i dedukcija (izvlaĉenje zakljuĉaka o ortodontskom stanju za svakog pacijenta posebno). Naravno, kao bazni postupak za ova istraţivanja korišćeno je 3D modeliranje, kao nauĉna disciplina koja je prvo razvijena u inţenjerstvu, a ovde će se primenjivati u ortodonciji...