Although both extra-radicular bone screws (IZC, BS) and micro-implants are classified under temporary anchorage devices – micro-implants are placed in between the roots of teeth (mostly) – intra-radicular, while bone screws are placed away from the roots in the infra-zygomatic areas of the maxilla and the buccal shelf areas of the mandible – extra-radicular. Both of them however are used for the purpose of skeletal anchorage.

While the regular size of a micro-implant ranges between 6 and 11 mm in length and 1.3–2 mm in diameter depending on the clinical situation, it needs to be used for; bones screws are comparatively larger in size ranging from 10 to 14 mm in length and a minimum diameter of 2 mm. Just like a micro-implant may be available as a short or a long head one, bone screws are also available as a short or a long collar depending on the anatomic site and the clinical situation it needs to be used for. Their head shapes may also vary just as micro-implants, the common being mushroom shaped.

Almost every micro-implant available in the market is made with an alloy of – titanium, aluminum and vanadium (Ti6Al4Va) and bone screws are also available with similar compositions but the choice of material is pure stainless steel. Bone screws are generally placed in areas of DI (>1250 HU) quality bone (IZC and BS areas) and therefore requires greater fracture resistance. Stainless steel provides greater fracture resistance than Ti alloy and is therefore the preferred material of choice 4.

The treatment objectives were to create a satisfactory occlusion maintaining a Class I molar relationship and anddecrowding in maxillary and mandibular anteriors. Correction of axial inclination of maxillary and mandibular anteriors with distalisation of the maxillary and mandibular teeth were indicated.

Orthodontic treatment lasted for 23 months. Preadjusted edgewise aplliance 0.022 MBT brackets were bonded to all teeth. With sequential nickel‐titanium archwires, alignment and leveling were achieved in 4 months. Then, after decrowding in upper and lower anterior teeth a posted archwire of 0.019‐0.025 SS wire place in maxillary and mandibular arche.

After 4 months of distalisation of the maxilla, the first molars were maintained in Class I relationship, facial profile and smile is improved. Posttreatment intra‐oral and extra‐oral photographs are shown in Figure 3. Posttreatment lateral cephalogram and orthopantomogram (OPG) is shown in Figure 4.

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Orthodontic treatment with mini‐screw anchorage is more comfortable for the patient than traditional reinforced anchorage such as multi‐brackets combined with intraoral or extraoral anchorage, because there is no requirement for the patient’s cooperation. Nevertheless, the success rate was approximately 80‐95%, and minimum invasion for placement surgery was necessary; the patients complained of little pain and discomfort after placement of the mini‐screws 5.

The center of resistance (Cres) of the maxillary dentition has been shown to be located around the middle area of the premolar roots. The more interproximal alveolar bone is available between the maxillary second premolar and first molar roots and between the maxillary first and second molar roots than in other locations 1.

The driving of the IZC screws into the bone begins 14-16mm above the maxillary occlusal plane at an angle of 90° to the occlusal plane. After a couple of turns, the mini-screws handle is turned to an angle of 55° to 70° to avoid damage to the roots of the molar teeth. The angle less than 55° technically is said to be easier but biting depth is reduced hence lacks stability and there is a higher failure rate with the above-mentioned angle. There is also a chance of alveolar or buccal mucosa irritation. An angle greater than 75° faces technical difficulty in placement, there might be slippage of IZC screws, bone stripping and also there is a greater chance of damage to the mesiobuccal root of the molar. Hence, the angulation between 55°-70° is chosen 9.

As anchorage is the prime goal of many treatment of malocclusion and skeletal anchorage play a absolute role we must know the importance of every type of skeletal anchorage system with their pros and cons 10.

There are hardly any complications associated with the use of implants. Ideally, fully erupted third molars are to be removed to create a space and aid in distalization process. For unerupted third molars placed below the cemento-enamel junction of the second molars in young individuals, distalization is possible without their extraction 11.

Through this case report we can conclude that mini‐screws placed in the maxillary buccal interradicular space between the second premolar and the first molar at an oblique angle were useful for moving molars distally in patients.