Dental arch monitoring by splines fitting error during orthodontic treatment using 3D digital models

Abstract

Backrgound/Aim. Researchers in the field of dentistry have been conducting research into modelling and defining dental arches equitations. Nowadays, when 3D digital modelling is commonly utilized in dentistry, the approach to modelling, analysis and synthesis has changed. Clinical researches are related to aesthetic and functional analysis. The aim of this study was to increase repeatability and accuracy of defining and determining the coordinate system of the jaw as well as to defining mathematical criteria for monitoring and evaluating orthodontic treatment. Methods. In this study, we used the plaster models of the jaw, optical scanner with structured light, 3D digital models, computer aided design (CAD) engineering tools adjusting the coordinate system, spline fitting of 3rd, 4th, 5th, 6th, 7th and 8th degrees. Results. Splines of 3rd, 4th, 5th, 6th, 7th and 8th degrees were fitted from the initial state (K0) in all 10 successive controls (K1, K2, K3,…, K10). All splines were fitted through 12 points, from the right to the left side of the jaw: 6-5-4-3-2-1-1-2-3-4-5-6. Tabular and graphic presentations of the maximum and average deviation of dental arch fitting curves in successive controls were given. Conclusion. The parameters of the maximum and average errors of fitting curves converge the dental arch values that are lower than the accuracy of the used optical scanners. The average error of fitting provides a general picture of the entire dental arch at each stage of treatment. Maximum error fitting points at a specified tooth where the largest deviation.

Uvod/Cilj. Istraživači u oblasti stomatologije, posebno kliničari, već dugo se bave istraživanjima koja se odnose na modeliranje i definisanje oblika i parametara zubnog luka. Danas, kada je 3D digitalno modeliranje postalo uobičajena praksa u stomatologiji, promenio se i prilaz modeliranju, analizi i sintezi u ortodonciji. Klinička istraživanja oblika zubnog luka direktno se odnose na estetsku i funkcionalnu analizu zubnog niza (nivelacija, okluzija, zagrižaj). Cilj rada bio je da se poveća ponovljivost i preciznost definisanja i određivanja koordinatnog sistema vilice i definišu matematički kriterijumi za praćenje i ocenjivanje ortodontske terapije. Metode. U radu su koršćeni gipsani modeli vilice, optički skener sa strukturisanom svetlošću, 3D digitalni modeli vilice i Computer Aided Design (CAD) i inženjerski alati. Sprovedeno je podešavanje koordinatnog sistema i fitovanje splajnova trećeg, četvrtog, petog, šestog, sedmog i osmog stepena. Rezultati. Splajnovi (trećeg, četvrtog, petog, šestog, sedmog i osmog stepena) fitovani su u odnosu na početno stanje (K0), za svih 10 uzastopnih kolona (K1, K2, K3,... K10). Svi splajnovi su fitovani u 12 tačaka, sa leve i desne strane vilice: 6-5-4-3-2-1-1-2-3-4-5-6. Dat je tabelarni i grafički prikaz maksimalnih i prosečnih odstupanja fitovanih krivih linija dentalnog luka u sukcesivnim kontrolama. Zaključak. Parametri maksimalne i prosečne greške fitovanja krivih linija dentalnog luka konvergiraju vrednostima koje su manje od tačnosti korišćenih optičkih skenera. Prosečna greška fitovanja daje opštu sliku celokupnog dentalnog luka u svakoj od faza terapije. Maksimalna greška fitovanja ukazuje na tačno određeni zub gde su odstupanja najveća.