Abstract: PURPOSE: To study the effect of NITI cantilever arm in correcting lingually inclined mandibular molar. METHODS: Sixteen patients whose single mandibular second molar was lingually inclined were chosen. The intra-mandibular anchorage was achieved by means of cast frame which connected the bilateral mandibular posterior teeth. The splint disoccluded the lingually inclined second molar with the antagonist. The cantilever arm of 0.018 inch×0.025 inch or 0.019 inch×0.025 inch NITI wire was used to provide buccal rotation moment and intrusion force. Graphpad Prism 6.0 software was applied for data analysis. RESULTS: All the lingually inclined second molars were uprighted, the axial change relative to the sagittal plane was 24°±1.2°(P<0.01).The change of the distance from the mesial lingual cusp of the lingually inclined second molar to the sagittal plane was 3 mm±0.8 mm (P<0.05). The anterior overbite was almost unchanged and the periodontal condition was healthy. CONCLUSIONS: Combination of casting frame with NITI cantilever arm can provide effective mechanics to correct lingually inclined mandibular molars.

Key words: Lingually inclined, Mandibular molar, NITI cantilever arm, Casting frame