CATEGORY AUSTRALASIAN DENTIST 57 LINICAL least effective attachment because of its small size and lack of a defined active surface. All other attachments are variations of the initial rectangular attachment design. This design was the primary attachment for any tooth movement that was considered moderate or difficult, without difference to the actual forces and moments generated by its placement. The patient has difficulty inserting and removing the aligners, which is an inherent problem with rectangular attachments. Initially attachments were only ellipsoidal in shape: horizontal for active intrusion movements and vertical for retentive purposes. Horizontal rectangular attachments: as conventional ones but are applied along the vertical axis of the tooth in the so-called “active surface area” to avoid the sliding effect during placement. Teardrop attachments Always customized according to the shape, length and width of the teeth. Used in cases of multiple rotations, to guide the derotation of the canines and when the correction exceeds 2 degrees. Altered aligner geometries include: Power ridges: Used to improve the correction of the torque (>3º) and the vertical control of the axis of the incisors. Bite ramps: These are horizontal attachments that are applied to the lingual surface of the upper teeth to correct deep bites and are applied buccally only in cases of cross bite. Use of bite ramps in deep bite cases with aligners creates proper space for lateral sector extrusion and supporting lower anterior intrusion and controlled proclination. To facilitate greater easeof insertionand removal, as well as to eliminate the issue, the beveled attachment was developed by rotating a portion of the rectangular attachment virtually into the tooth surface. The beveled attachment can be used in multiple orientations by simply rotating the attachment in a different manner. Attachments for various tooth movements The ability of an aligner to move teeth is given by the pressure exerted by the material on the tooth. Traditionally, the displacement is guided by the presence of composite resin buttons which are applied to the buccal or palatal surface of one or more teeth, and whose shape and position depend on the function they must perform. The attachments are placed according to the aligner software attachment protocol such as ellipsoid attachment, horizontal/ vertical attachment, gingival/ occlusal bevelled attachment, optimized attachment automatically placed by the software. u used for intrusions and extrusions on premolars and incisors, u on premolars to increase aligner stability when using class II or III elastics, fu or retention in subjects with short dental crowns or hypodivergent patterns (to control the Spee curve and deep bite), u on restored teeth because the attachment’s bonding area is smaller. Vertical rectangular attachments: u used to derotate the canines and premolars (in particular, on the mandibular ones to close the extraction spaces), u for the axial control of the anterior teeth, u for the uprighting of the posterior teeth. Bevelled rectangular attachments Bevelled rectangular attachments are used in cases of deep bite particularly, they are indicated class II malocclusions which requires to intrude canines and incisors. These attachments have then evolved into customized and smaller bevelled attachments that have the same function Divots: These are small depressions programmed and pre-inserted on the invisible aligners that are able to replace the attachments to guide many movements (rotations, minor tipping movements, buccal-oral movements) and/or guarantee the retention of the aligner. Also called pressure points within the aligner to deliver forces instead of bonded resin attachments. In all cases, the effectiveness of the aligner–attachment–tooth interaction depends a lot on the precision with which the operative protocol used for bonding the attachment itself is performed and on the composite material used.
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