**6. Alignment/ Leveling/Torque/Angulation (ALTA) corrections**

incisor, an apically positioned flap is the appropriate surgical uncovering technique. Exposure of the crown facilitates attachment of an elastomeric chain directed toward the center of the edentulous alveolar ridge to gradually guide the canine crown into the dental arch. [16] A "Vertical spring" bent into 0.14 inch stainless steel wire that faces downward before activation is another alternative. It can be activated by pushing the vertical legs toward the impacted canine. This kind of round wire has the benefit of increased length and springiness but needs some kind of anti-rotation bent for avoiding rotation of round wire inside bracket slot that neutralizes the activity of the spring. Another alternative is an "Overlaid Auxiliary NiTi wire" on the rectangular stabilizing arch. These auxiliary arch wires are very efficient to bring an impacted tooth into dental arch. "Cantilever springs" can be used, either soldered to a heavy base arch or from auxiliary tube on the first molar. Some have used headgear tube plus an antirotation bend on wire and a helix around main arch wire for forced eruption of impacted teeth.

Dental arch with aligned teeth and heavy main archwire can serve as an anchorage unit to be used for uprighting posterior second or third molar teeth by a NiTi or sectional Stainless Steel wire incorporating loops e.g. T-loop. Absolute anchorages i.e. miniscrews or titanium miniplates are other alternatives for distalizing or uprighting impacted molar teeth (Figure 15). Molar uprighting is generally associated with extrusion of antagonist teeth, reduction in edentulous space, bone dehiscence in the mesial surface of tipped molars, gingival recession of tipped molars, early contact in centric relation and occlusal interference on excursion of the mandible. With regard to integrated planning, clinicians must decide whether the tooth subject to uprighting will undergo movement for space closure, opening of space for prosthetic rehabilitation or implant placement. Mesial movement of molars may be rendered difficult due to the following: alveolar bone resorption resulting from tooth loss, which causes the molar mesial bone to become too thin; unfavorable root morphology for movement of lower molars; greater mandibular bone density in relation to the maxilla; and thin buccolingual bone thickness from distal to mesial in the mandibular arch. Using straight wires to upright tipped molars is considered unfeasible, given that, in these cases, there is a strong tendency towards extrusion of molars, especially due to the short distance between brackets. Additionally, incorporating a T-loop spring into the arch will lead to extrusion of premolars. A cantilever, extended up to the anterior region, may be used to reduce the effects of extrusion on molars. Researches have proved a moment of 1200 gf.mm to be appropriate for molar uprighting. Should a 30-mm cantilever be used, an activation of 40 gf is enough for molar uprighting, in which case 40 gf corresponds to intrusive forces in the anterior region and extrusive forces in the region of molar teeth. Mesocephalic or brachycephalic patients are able to eliminate or reduce this effect

tooth lingually. At the first molar, if the center of resistance is 5 mm lingual to the tube, a 30 g intrusive force can create 150 g.mm moment to rotate it buccally. If the center of resistance of the impacted canine is, presumably, 10 mm palatal to the buccal surface of the first molar, activation of spring to tie to the canine, can twist it and create 300 g.mm (30x10=300g.mm) moment to rotate molar crown palatally. The result at the molar is a net 150 g.mm (300 g.mm palatal – 150 g.mm buccal =150 g.mm palatal) palatal crown torque. (Bracket type and existence of continuous archwire of the model are not related to the biomechanical

The orthodontist should avoid mechanics that draw the tooth labially, which could produce a bony dehiscence and accelerated migration of the labial gingival margin, resulting in labial recession. A "Ballista" loop is a simple, convenient, unobtrusive method of applying a vertical vector of force to a labially impacted tooth to erupt the crown into the center of the alveolus. When the canine crown is displaced mesially and lies over the root of the permanent lateral incisor, an apically positioned flap is the appropriate surgical uncovering technique. Exposure of the crown facilitates attachment of an elastomeric chain directed toward the center of the edentulous alveolar ridge to gradually guide the canine crown into the dental arch.(16) A "Vertical spring" bent into 0.14 inch stainless steel wire that faces downward before activation is another alternative. It can be activated by pushing the vertical legs toward the impacted canine. This kind of round wires have the benefit of increased length and springiness but they need some kind of anti-rotation bent for avoiding rotation of round wire inside bracket slot that neutralizes the activity of the spring. Another alternative is an "Overlaid Auxiliary NiTi wire" on the rectangular stabilizing arch. These auxiliary arch wires are very efficient method to bring an impacted tooth into dental arch. "Cantilever springs" can be used, either soldered to a heavy base arch or from auxiliary tube on the first molar. Some clinician have used headgear tube plus an anti-rotation bend on wire and

‐Biomechanical alternatives for tooth forced eruption

A dental arch with aligned teeth and heavy main archwire can serve as an anchorage unit to be used for uprighting posterior second or third molar teeth by a NiTi or sectional Stainless Steel wire incorporating loops e.g. T-loop. Absolute anchorages i.e. miniscrews or titanium miniplates are other alternatives for distalizing or uprighting impacted molar teeth (Figure 15).

**Figure 15.** T-loops have efficient control on angulation and torque of an inclined tooth (left). An alternative to absolute anchorage can help in uprighting the tilted impacted second or third molars without endangering other teeth as an‐

Molar uprighting is generally associated with extrusion of antagonist teeth, reduction in edentulous space, bone dehiscence in the mesial surface of tipped molars, gingival recession of tipped molars, early contact in centric relation and occlusal interference on excursion of the mandible. With regard to integrated planning, clinicians must decide whether the tooth subject to uprighting will undergo movement for space closure, opening of space for prosthetic rehabilitation or implant placement. Mesial movement of molars may be rendered difficult due to the following: alveolar bone resorption resulting from tooth loss, which causes the molar mesial bone to become too thin; unfavorable root morphology for movement of lower molars; greater mandibular bone density in relation to the maxilla; and thin buccolingual bone thickness from distal to mesial in the mandibular arch. Using straight wires to upright tipped

chorage units that may be affected with orthodontic force and tooth movement or root resorption.

**5.2. Molar uprighting in impacted cases**

of extrusion by their own muscular pattern. (15,17)

a helix around main arch wire for forced eruption of impacted teeth.

84 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

‐Molar uprighting in impacted cases

explanations.)

The root apices are located in the apical portion of the jaws and malposition almost always develops as the eruption paths of teeth are deflected; for impacted teeth the problem is more complicated and both apex and crown are usually misplaced. ALTA corrections have been considered for the time that impacted tooth has been brought near to the dental arch. Light and continuous force is recommended for the beginning of the treatment i.e. "Alignment", through tipping movement for impacted teeth in facio-lingual direction. As a general rule, heavy wires should be avoided at this stage. A minimum of 0.004 inch clearance is needed for sliding mechanics, in other words, in 0.018 slot an archwire with 0.014 inch stainless steel can be accepted for sliding but for severe crowding or malposition situation, more length of wire in the form of loop or helices should be incorporated. Although resilient wire with rectangular shape like A-NiTi or CuNiTi (Damon system) could be used, but because they produce unwanted root movement, possible root resorption, and possible delay in alignment progres‐ sion, rectangular resilient wires are not advisable. Wires should have excellent strength and springiness, long range of action and low load deflection rate. NiTi wires are springier and stronger (in small section) than beta-titanium (TMA), for these reasons, A-NiTi and CuNiTi wires are recommended for initial stages of aligning.

In addition to alignment, impacted teeth should be "Leveled" in occluso-gingival direction. Leveling can be obtained by absolute intrusion or by relative intrusion and sometimes by differential elongation or extrusion of teeth. Utility arches e.g. 2x4 appliance, reverse curve for lower arch, intrusion arch and combination of sectional wires, segmented arches and titanium miniscrews are used for leveling the dental arch.

After establishment of proper alignment and leveling, two other crown position characteristics should be achieved i.e. "Torque" and "Angulation". Torque is in facio-lingual direction and usually involves root movement and moment (increased M/F ratio) is needed for its correction. Angulation is related to mesio-distal characteristics of crown positioning and like the amount of torque degree, is considered in bracket prescription in straight wire appliances (SWA). Wire bending like what is performed in "Standard Edgewise" for finishing and establishment of correct torque and angulation, is needed for severe impacted cases for obtaining the proper ALTA correction and accepted occlusion (according to ABO scores).
