The treatment of class III malocclusion in early mixed dentition: Two case reports

Abstract

Class III malocclusion is orthodontic anomaly where mandibular arch is in mesial position to maxillary arch. Reasons for Class III malocclusion can be found in mandibular prognathism, maxillar retrognathism or combination of these two. In most cases of mandibular prognathism, it is necessary to postpone the treatment until the growth ceases. However, if certain conditions are accomplished it is possible to start early treatment of class III malocclusion to improve occlusal relations and provide more favorable environment for future growth. The aim of this study was to present treatment of two patients with Class III maloclussion in early mixed dentition, using two different appliances: Delaire mask and Frankel functional regulator type 3. The treatment with Delaire mask resulted in rotation of maxilla downward and forward due to the angle of extraoral part of the mask to the occlusal plane that was modified to be almost 45°. At the end of the treatment facial esthetics was significantly improved. Moving maxilla forward resulted in straight profile, whereas moving maxilla downward lead to coordination of upper, middle and lower facial third. The result of the treatment in patient who used Frankel functional regulator was correction of anterior crossbite by premaxilla development and incisors protrusion. Significant differences in SNA, SNB and ANB angle values at the beginning and at the end of the treatment were not found suggesting that most changes were dental but not skeletal.

Skeletna malokluzija III klase je nesklad u međusobnom odnosu gornje i donje vilice, jer je donja vilica postavljena mezijalnije u odnosu na gornju. Uzrok nastanka skeletne malokluzije III klase može biti mandibularni prognatizam, maksilarni retrognatizam ili kombinacija ova dva uzroka. U slučaju isuviše razvijene donje vilice najčešće je potrebno sačekati završetak rasta, kako bi se primenilo konačno lečenje. Međutim, ako su ispunjeni određeni uslovi, moguće je primeniti ranu terapiju III klase, da bi se poboljšali okluzalni odnosi i obezbedila dobra osnova za dalji rast. Cilj ovog rada bio je da se prikaže terapijski efekat dva slučaja malokluzije III klase u ranom uzrastu pomoću različitih ortodontskih aparata: Delerove maske i Frenklovog regulatora funkcije tip 3. Kod pacijentkinje koja je tokom lečenja nosila Delerovu masku gornja vilica je zarotirana unapred i nadole, jer je ugao delovanja sile modifikovan da bude skoro 45 stepeni. Na kraju lečenja postignut je znatno bolji izgled lica. Pomeranjem gornje vilice unapred postignut je prav profil, dok je pomeranje nadole dovelo do usklađivanja visine srednje trećine lica sa gornjom i donjom. Kod pacijenta kod kojeg je tokom lečenja primenjena terapija Frenklovim regulatorom funkcije tip 3 do korekcije obrnutog preklopa sekutića došlo je kombinacijom razvijanja premaksile i protruzije sekutića. Značajne promene u vrednostima uglova SNA, SNB i ANB nisu zabeležene na kraju terapije u odnosu na početak, što bi ukazivalo na to da su postignute promene uglavnom dentalne, a ne skeletne.