engleski

EVALUATION OF ANGULAR INTRAARCH PARAMETERS ON LONGTERM STABILITY

AIM: There are still a lot of uncertainties related to long term stability after orthodontic treatment. Mostly, linear measurements were investigated and predictors have not been identified. Aim of this research was to investigate how angular intraarch parameters influence long term stability. + MATERIALS AND METHODS: Sample was consisted of 103 patients (73 female and 30 male), with class I and class II malocclusions. 48 patients were treated nonextraction and 55 were treated with extractions, mostly of first permanent premolars. Their dental casts were obtained before treatment (T1), after treatment (T2) and at long term postretention period (T3). All patients were treated with fixed orthoodntic appliances by one experienced orthodontist. Retention protocol lasted 3 years ( upper Wraparound retainer and lower bonded retainer).. All dental casts of upper and lower dental arches were scanned with Ortho Insight 3D Scanner ( Motion View LLC, Hixon, USA) and transfered into STL format. Using custom software developed in Matlab programing environment, linear and angular intraarch parameters such as Little's irregularity indeks (II), intercanine width (IC), intermolar width (IM), contact angle (CA) and interdental angle (ID) were analysed. Contact angle was measured between two lines connecting mesial and distal contact points of adjacent teeth. RESULTS: Patients were out of retention for average of 17.2 (sd ± 6.45) years. Upper and lower arches showed significant stability in postretention period. In T3 in upper arch irregularity index was smaller than in lower arch, but it wasn't statistically significant. In T3 in upper arch Irregularity Index for extraction cases was 1.69mm and 1.10mm for nonextraction. In lower arch Irregularity Index for extraction cases was 2.05mm and for nonextraction 1.52mm. In upper arch strong positive correlation was detected between Irregularity index and CA 1121 and CA2221. In the lower arch Irregularity index positively correlated with CA 3332 (p<.05). CONCLUSION: Upper and lower arches showed clinically significant stable long term result of orthodontic extraction and nonextraction treatment, mostly under 2mm of Little's index. It seems that long term stability in upper arch is related to the position of incisors, while in the lower arch it is more related to position of canines.

stability, dental arch, intraarch parameter

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