Background/Aims: To compare the change in the angulation of developing mandibular third molar in both first premolar extraction and non-extraction cases and to determine whether premolar extraction results in a more mesial movement of the mandibular buccal segment and causes favorable rotational changes in the mandibular third molar tilt, which can enhance later eruption of the third molars.

No abstract

Assoc iate Pro fesso r, Dept. of O rth odo nti cs a nd De ntofac ia l O rth o pedi cs, SDM De nt a l In stitut e, Dh a rwad, Ka rn ata ka, In di a. K. M. Ke luskar MDS, Professor, He ad, De pt. of Orth odo nti cs a nd De ntofac ial O rthopedi cs, KLE De nta l Institute, Be lga um , Ka rn a tak a, In dia.

Objective: To find out if it is possible to control maxillary anterior teeth in sagittal and vertical plane during retraction by altering the vertical levels of force application in the posterior region, i.e. identifying the type of movement of the maxillary anterior teeth which occurs when force would be applied from four different levels i.e. High, Medium, and Low pull Implants and from a conventional Molar hook and also to quantify the retraction and intrusion components of force thus setting a guideline for the implant height placement. Materials and Methods:A Finite Element Model of maxillary dentition along with alveolar bone, brackets and wire was developed with defined material properties. The model was analysed to calculate the displacement when force was applied from different levels.Results: From all points of force application, anterior teeth tipped lingually in the sagittal plane, whereas in the vertical plane extrusion was seen when retracted from molar hook and intrusion was seen when retracted from implants. For every mm of apical displacement of implant, the retraction component of force reduces approximately by around 1% and intrusion component of force increases approximately by around 0.3%. Conclusion:Based on the results of this study we can reckon that by changing the position of implant in vertical plane one will have very little effect on the type of tooth movement. As the point of force application moves apically, type of tooth movement in the sagittal plane remained almost constant and in vertical plane intrusion is slightly increased.

Decreased Adenoids, restricted airway, small, retruded maxilla, smaller velum length and larger need ratio larger were seen in the cleft group as compared to the non-cleft group, which was suggestive of VPI.