Cephalometric assesement of the cranio-facial pattern skeletal class III in the period of mixed dentition

Abstract

The essence of the class III malocclusions is a decreased value of the angle which defines sagittal jaw relationships. This is a skeletal disharmony which develops slowly, during the specific process of the development, under the influence of genetic and non - genetic etiological factors. The AIM of this research is to examine cranial, facial and dental parameters with children with skeletal class III in the period of mixed dentition. Furthermore, to compare them to the parameters of children at the same age, with I class skeletal class and adults with skeletal class III. That is how we can determine relevant parameters for early diagnostic of this malocclusion, define their dominate model in Serbian children population and accordingly, suggest the best early therapeutic treatment protocol. Sample was made by random selection. All the examinees had their parents’ written consent and had been fully informed about the purpose of this research in both aural and written form. Lateral cephalometric images were done in central occlusion using standard procedure for all the patients. Each image was drawn on the tracing paper. First, the relevant cephalometric marks, lines and planes were specified and then the angular and linear measurements from cephalometric analysis were performed: Bjork, Wits, Chang, Downs, Steiner, Swartz, Tweed. The examinees were divided into three groups. Each group consisted of 50 examinees, male and female, with no previous orthodontic treatment. The first group consisted of children with mixed dentition (aged 6 - 12) and skeletal class III (ANB ˂ 2°). The second group consisted of children with mixed dentition (aged 6 - 12 years) and skeletal class I ( ANB = 2° - 4°, SNA = 80° - 82°, SNB = 78° - 80°). The third group consisted of adults (aged 18 - 26) with skeletal class III (ANB ˂ 2 ° ). The examinees from the first and the second group were divided in to two subgroups by their age: a) subgroup aged 6 - 7 and 11 months, b) aged 8 - 9 and 11 months and c) aged 10 - 12. The examinees from the first and the third group were divided by the type of skeletal class III malocclusion determined by the maxillas and mandibles position in comparison with cranial base: I type - maxilla r is orthognat h is m and mandibles prognat his m, II type - maxillas retrognat h ism an d mandibles orthognat h is m , III type - bimaxillar retrognat h is m, IV type - bimaxillar prognat h is m, V type - maxillas retrognat h is m and mandibles prognat h is m and VI type – bimaxillar orth ognat h is m, which was defined only in the first group...

Suštinu malokluzije III skeletne klase čini smanjena vrednost ugla koji definiše skeletni sagitalni MVO. Malokluzija III skeletne klase je skeletna disharmonija koja se razvija postepeno, u toku specifičnog razvojnog procesa, pod uticajem genetskih i negenetskih etioloških faktora. Cilj ovog istraživanja je da se ispitaju kranijalni, facijalni i dentalni parametri kod dece sa III skeletnom klasom u doba mešovite denticije. Zatim, da se uporede sa istim parametrima kod dece sa I skeletnom klasom istog uzrasta i odraslih sa III skeletnom klasom. Tako bi se utvrdili relevantni parametri za što raniju dijagnozu ove malokluzije, definisao njen dominantni model u populaciji srpske dece i u skladu sa tim, sačinio predlog ranog terapijskog protokola. ISPITANICI I METOD RADA: Uzorak je formiran metodom slučajnog izbora. Svi ispitanici su imali pisanu saglasnost roditelja, uz predhodno potpuno informisanje, usmeno i u pisanoj formi o ciljevima istraživanja. Svakom ispitaniku načinjen je lateralni kefalometrijski snimak u centralnoj okluziji, standardnom procedurom. Svaki snimak je iscrtan preko paus papira. Najpre su određene relevantne kefalometrijske tačke, prave i ravni, a zatim su sprovedena angularna i linearna merenja iz kefalometrijskih analiza: Bjork, Wits, Chang, Downs, Steiner, Swarz, Tweed. Ispitanici su podeljeni u tri grupe, pri čemu je u svakoj po 50 ispitanika oba pola, koji ranije nisu bili ortodontski lečeni. Prvu grupu čine deca sa mešovitom denticijom (uzrast 6 – 12 godina života) i III skeletnom klasom (ugao ANB lt 2°). Drugu grupu čine deca sa mešovitom denticijom (uzrast 6 – 12 godina života) i I skeletnom klasom (ugao ANB = 2° - 4°, ugao SNA = 80° – 82°, ugao SNB = 78° – 80°). Treću grupu čine odrasli ispitanici (uzrast 18 – 26 godina života) sa III skeletnom klasom (ugao ANB lt 2°). Ispitanici iz 1. i 2. grupe podeljeni su u podgrupe prema godinama starosti na: a - podgrupa uzrasta od 6 godina – 7 godina i 11 meseci, b - podgrupa uzrasta od 8 godina – 9 godina i 11 meseci i c - podgrupa uzrasta od 10 godina –12 godina. Ispitanici iz 1. i 3. grupe podeljeni su po tipovima malokluzije III skeletne klase, određenim prema poziciji maksile i mandibule u odnosu na kranijalnu bazu na: I tip - maksilarni ortognatizam i mandibularni prognatizam, II tip - maksilarni retrognatizam i mandibularni ortognatizam, III tip - bimaksilarni retrognatizam, IV tip - bimaksilarni prognatizam, V - maksilarni retrognatizam i mandibularni prognatizam i VI tip - bimaksilarni ortognatizam, koji je definisan samo u 1. grupi...