# Acceleration Techniques for Teeth Movements in Extractive Orthodontic Therapy
## 4 Discussion
### Corticotomies  
First introduced in 1892, corticotomy is a surgical technique involving a cortical bone cut, perforated or mechanically altered, with minimal involvement of the bone marrow [33]. It differs from osteotomy, where the cut involves bone and marrow. Regional Accleratory Phenomena (RAP) is based following corticotomy surgery on the principle that rapid bone remodelling and increased cell turnover occur following any trauma to bone tissue. There is a 4-5-month window during which the bone physiology changes, where the trabecular bone loses density and selectively offers less resistance to OTM. In AOO (Accelerated Osteogenic Orthodontics), non-activated teeth provide a relative anchorage for activated teeth that move faster (Figure 3) [33; 65; 66]. Several studies have been conducted to investigate the efficacy of this strategy. [PERSON] et al. (2014) evaluated the impact of corticotomy on a sample of 20 patients [33]. In the group of ten patients who underwent surgery, after lifting a full-thickness flap, a 2 mm round bur was used to make incisions between the inter radicular spaces from premolar to premolar, starting 2 mm apical from the bone crest and ending more than 2 mm from the root apex. The cuts for horizontal corticotomy involved both labial and palatal sides, and demineralised freeze-dried bone was applied before flap closure and suturing. Once compared to the CGr, the ExGr TT was significantly shorter(131 \(\pm\) 7.5 days vs. 234 \(\pm\) 9) [33]. [PERSON] et al. (2018) compared corticotomy versus the control in a split-mouth study [34]. Two vertical incisions were made, one on the canine distal line angle and the other on the second premolar mesial line angle, and full-thickness mucoperiosteal flaps were reflected. Selective decorification was performed on the buccal and lingual cortical plates using a fissure bur (#556) in a high-speed handpiece. To standardise all corticotomy operations, decoritation was conducted at three sites: the buccal plate, the crest of the alveolar ridge, and the palatal plate (Figure 1). The study concludes that corticotomy accelerates OTM by 40% [34; 67]. [PERSON] et al. (2014), which analysed bur decoritation via 701 slit burs and number 2 round burs attached on a micromotor handpiece, reached a similar conclusion,  
Figure 3: Corticotomies technique, as shows the red dashes. as it measures the average space closure velocity in the maxilla as 1.8 mm/month, and in the lower jaw, as 1.57 mm/month, compared to 1.02 mm/month in the maxilla and 0.87 mm/month in the CGr [54]. [PERSON] et al. (2017) inserted an additional variable in the split mouth RCT study, as it compared bur corticotomy performed only on the buccal side with corticotomy performed on both the buccal and palatal side and came to the conclusion that there are no statistically notable differences within the two populations [24]. [PERSON] pioneered piezovision as a minimally invasive approach for accelerating OTM. Piezoision is a potentially minimally invasive tooth acceleration procedure because of its numerous periodontal, cosmetic, and orthodontic benefits [57]. Incisions are made in the buccal mucosa under local anaesthetic 2-3 mm below the interproximal papilla's base. To decoricate the alveolar bone, the tip of the piezotome is placed at a depth of 3 mm. [PERSON]'s study (2020) states that piezocision accelerates canine retraction movement by 1.5 times [57]. In an RCT study, [PERSON] et al. (2021) compared traditional corticotomy with bur using piezocision. Buccal 1 cm transmucosal incisions were made distal to the canine and mesial to the second premolar area in both groups [55]. The incisions were made 5 mm apical to the papillae, and the vertical guideline bur holes were drilled and joined on the buccal cortex using a No.8 tungsten carbide round bur mounted on a straight handpiece and rotated at 30,000 rpm. At a depth of 2 mm, the groove went through the cortical bone, barely entering the spongiosa.