Introduction
In thelate 1990’sWilcko brothers, developed the Accelerated OsteogenicOrthodontics (AOO) procedure and claimedthat the orthodontic treatment time could bereduced by 75% in the majority oforthodontic cases by accelerating orthodontic tooth movement.1 In 2009 Dibart2 et al. described a newminimally invasive procedurePiezocision,whichcombines micro-incisions limited to thebuccal gingiva that allow the use of apiezoelectric knife to give osseous cuts tothe buccal cortex and initiate the regionalacceleratory phenomenon (RAP).
Wilcko et al.3, claimed that accelerated tooth movement after corticotomy is a result of a physiological response of the bone, known as the regional acceleratory phenomenon, which is induced by bone damage. Sebaoun et al, suggested that alveolar decortication induces rapid and localized bone turnover and may be the main reason for accelerated tooth movement. Liou andHuang4 suggested that rapid canine retraction could be achieved by distractingthe periodontal ligament and undermining the interseptal bone by bending the interseptal bone distal to the canine and move the canine into the first-premolar extraction site.
This article describes a patient treated with custom-made, rigid, segmental tooth-borne distractiondevice used to retract thecanine by distraction of the periodontalligament into premolar extracted site with knife edge alveolar ridge after ridge expansion with piezocision.
Diagnosis and Treatment Planning
A 25-year-old male presented with the complaint of crowded upper front teeth. On extra oral examination he exhibited a convex profile with prognathic maxilla (Figure 1). Intra oral examination revealed a class I canine relation, crowded upper and lower anterior teeth. There were missing teeth in relation to 24,25,26 region with a history of extraction before 3 years due to which there was a knife edge alveolar ridge in that region (Figure 1). Cephalometric analysis indicated that patient had a skeletal class II relationship with maxillary prognathism, low mandibular plane angle and proclination of the lower incisors (Table 1).Treatment plan was to
First retraction of 23 into 24 region
After, 23 retraction, extraction of other sides first premolars and start fixed appliance therapy to correct crowding.
Finally, after fixed appliance therapy, replacement of 25 and 26 was planned
Taking into consideration the anchorage demands, long span knife edge edentulous space in the second quadrant, we proposed the use of a distraction device to rapidly retract the left upper canine to the first premolar region after ridge expansion.
Table 1
Cephalometric variables
Treatment progress
The tooth to be distracted was second quadrant canine and the second molar acts an anchor unit. The custom made distractor (Figure 3) was made according to design by Sukuricaet al.5 and modified by soldering a 11mm expansion screw to bands on 23 and 27 on the buccal side and lingual buttons were welded on the lingual side for attachment of elastic chain to prevent unwanted rotation of canine and molar during distraction. Before placement of the distractor device we planned for ridge expansion of 10 mm in first premolar region due to reduced thickness of alveolar ridge in first premolar region which could not accommodate the canine. The protocol according to Mete Ozerfor implant placement was followed for ridge expansion.6 Under Local Anaesthesia, crestal incision was performed from 23 to 26 region. Using piezoelectric device vertical osteotomy cuts were given 3mm distal to 23 to a planned height of 16mm grooving vertically along the buccal and lingual sides to facilitate distraction of canine. (Figure 4 a, b). Ridge split was carried out on the knife edge ridge for 4 mm and expansion was done for 10mm (Figure 4 c).
The expanded region was packed with osseomould bone graft to prevent approximation of expanded ridges. The graft was covered with a layer of plasma rich fibrin (PRF) 7 to increase the bone inductive and conductive activity. The custom-made distractor was fixed and left in place for 2 days (Figure 5). From third day the distractor device (Figure 6, Figure 7) was activated at the rate of 0.5mm per day (two quarter turns twice daily).4 The distraction was carried out till canine was bought into the first premolar region(Figure 8), a total of 8 mm canine retraction was achieved. Elastic chain was attached between the lingual side of canine and second molar to prevent unwanted rotation of anchor tooth.
Treatment outcome
The canine was distracted and brought in to first premolar position, there were no visible color changes in the distracted as well as anchor teeth. The canine has tipped slightly after distraction.Although there was no bodily molar movement, there was slight tipping was seen (Figure 8). After 6 months the appliance was removed (Figure 9) and patient advised for further treatment with fixed appliance therapy. In post-treatment OPG parallelism of roots was almost achieved. (Figure 10)
Discussion
In this case, we have achieved rapid canine distraction through distraction of periodontal ligament along with ridge expansion. The lack of ridge preservation after extraction will lead to significant ridge atrophy, as such in our case. In this clinical case, there was an absence of both left maxillary premolars and the first permanent molar, which was utilized by moving the upper left canine to the interdental region between lower premolars. We have used piezoelectric surgical method for decortication because they are minimally invasive surgical techniques that offer less patient pain and acceptance.2 This procedure is like intentional fracture which produces a regional acceleratory phenomenon that speeds up the bone remodelling process. 8 One animal study found that distraction of the periodontal ligament stimulated the expression of collagen I, collagen III, and matrix metalloproteinase-1 and thus promoted rebuilding of the ligament.9 In our patient, the upper canine’s periodontal ligaments were distracted by about 8mm in four weeksKharkar and colleagues preferred dentoalveolar distraction to periodontal distraction for rapid canine retraction because it avoided canine tipping.10 In our patient the canine and molar tipping was avoided by placement of powerchain on the lingual side between canines and first molars. The distracted canines showed grade 1 mobility indicating tearing of periodontal ligament as demonstrated by Feng et al.11
Conclusion
This method of combining ridge expansion with use of distraction done was effective in moving the canine through atrophic ridges. Though the custom-made distractor was initially unesthetic and causes short term problems such as discomfort and chewing difficulty, the canine movement was rapid and effective. Hence, this technique can be effectively used in patients with knife-edge alveolar ridge who were difficult to treat previously with orthodontic treatment alone.
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