Acceleration of Orthodontic Tooth Movement for Retraction Upper Canine by Alveolar Corticotomy

Dental News Volume XVIII, Number I, March, 2011

by Pr. Azzam AL-jundi and Dr. Fadi Al-Naoum

Introduction

One method used to accelerate orthodontic tooth movement is the corticotomy-facilitated (CF) technique. Tooth movement and alveolar bone reaction after corticotomies have not been thoroughly examined. In this study, the effects of corticotomies on orthodontic tooth movement were investigated in humans. The purposes of this study were to (1) identify the effect of the CF technique on orthodontic tooth movement compared with the standard technique. (2) evaluate pain and discomfort levels and the levels  of satisfaction of the patients about corticotomy, during the treatment. (3) compare between males and females regarding tooth movement velocity on the experimental side. 

Methods

30 patients, aged 15 to 24 years, with a mean age (20,04±3,63) years were used in this study. Extraction of the maxillary first premolars. On One side, the corticotomy was performed. The canines were distalized with nickel-titanium coil springs on both sides. Corticotomies were performed on the cortical bone of the maxillary first premolars region in 30 patients (10 male and 20 female). The canines on the experimental side and on the sham side were moved distally with a continuous force of 120g.

Results

Tooth movement velocities after the corticotomies were significantly faster on the experimental side than on the sham side.

Conclusions

Orthodontic tooth movement increased after the corticotomies. This might be brought about by rapid alveolar bone reaction in the bone marrow cavities, which leads to less hyalinization of the periodontal ligament on the alveolar wall. suggested that the acceleration of tooth movement associated with corticotomy is due to increased bone turnover and based on a regional acceleratory phenomenon.

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Canine Distalization for extraction cases usually takes 6 to 9 months, contributing to an overall treatment time of 1.5 to 2 years. The duration of orthodontic treatment is one of the issues patients complain about most, especially adult patients. That is why many patients refuse orthodontic treatment. The incidences of caries and periodontal disease also increase when treatment is prolonged.¹ To shorten the time for orthodontic tooth movement, various attempts have been made. These attempts fall into 3 categories. The first is local or systemic administration of medicines such as prostaglandins, interleukins, leukotrienes, cyclic adenosine monophosphate, and vitamin D.^2-5 The second category is mechanical or physical stimulation such as direct electrical current ⁶ or a samarium-cobalt magnet.⁷ The last category is oral surgery, including gingival fiberotomy,⁸ alveolar surgery, and distraction osteogenesis. distraction osteogenesis is a process of growing new bone by mechanical stretching of the pre-existing bone tissue. In 1998, Liou and Huang demonstrated the rapid canine retraction technique involving distraction of the PDL (PDLD) aided by alveolar surgery undermining the interseptal bone.  after extraction of the first premolars.⁹ Iseri et al and Kisnisci et al described and clinically used a new technique for rapid retraction of the canines, the DAD.¹⁰

In 2001, Wilcko et al¹¹ reported a revised corticotomy-facilitated (CF) technique that included periodontal alveolar augmentation, called accelerated osteogenic orthodontics; it demonstrated acceleration of treatment to one third of the usual time.¹²

A corticotomy on the alveolar bone makes orthodontic tooth movement faster than that in conventional orthodontic treatment; this leads to shorter orthodontic treatment times.^13-18 According to Hajji,¹² the active orthodontic treatment periods in patients with corticotomies were 3 to 4 times more rapid compared with patients without corticotomies. It was believed that a corticotomy makes tooth movement faster because the bone block moves with the tooth.^11-16

However, tooth movement after a corticotomy should be considered a combination of the classical orthodontic tooth movement and the movement of bone blocks containing a tooth, because the force applied on a tooth is transmitted into the osteotomy gap through the periodontal ligament (PDL).

Bone turnover is well known to be accelerated after bone fracture, osteotomy, or bone grafting.¹⁹ This could be explained by a regional acceleratory phenomenon (RAP); ie, osteoclasts and osteoblasts increase by local multicellular mediator mechanisms containing precursors, supporting cells, blood capillaries, and lymph. ²⁰

Similarly, bone turnover is increased by RAP after a corticotomy.

The velocity of orthodontic tooth movement is influenced by bone turnover,^21,22 bone density,²³ and hyalinization of the PDL.¹ Wilcko et al^11,15 mentioned, in cases of rapid orthodontics with corticotomies, those corticotomies could increase tooth movement by increasing bone turnover and decreasing bone density.

However, the increase of tooth movement after a corticotomy was not always examined in humans. In our study, we intended to elucidate the mechanism of the rapid tooth movement associated with corticotomies by investigating the amount of tooth movement and the alveolar bone reaction on the periodontal tissue of the compression side after corticotomies in humans.

Material and Methods

A clinical prospective study was performed to evaluate the effects of corticotomy in 30 patients (10 male and 20 female) with a mean age (20,04±3,63) years.

After conviction there is indication for retraction upper canine after extraction first upper premolars.

The patients were informed of the risks, advantages, and disadvantages of  the experiment and they decided to undergo   orthodontic  treatment after corticotomy and signed a consent  form.

All patients were treated with preadjusted Straight Wire fixed appliances, with a 0.0220 × 0.0280 slot brackets (Roth, American orthodontics) were used and TPA (transpalatal arch) was soldered to the first upper molars bands.

The maxillary left and right canines were chosen to be the experimental and sham sides with one of the random methods.

The maxillary first premolars were extracted on both sides to prepare the space for distal movement of the canines.

Healing, by the formation and mineralization of callus, usually requires 4 to 16 weeks after bone injury.¹⁹ Therefore, at 12 weeks after extraction, the alveolar bone on the experimental side was corticotomized as follows: the gingival mucoperiosteal flaps were raised to expose cortical bone on both the buccal and the lingual sides of the canine (Fig 1 and 2).

Fig 1. Schematic drawing of incision on palatal side.

 

Fig 2. Schematic drawing of incision on buccal side.

The horizontal cut line of the corticotomy was made above the apices of the canine 2-3 mm on the buccal side and at the level of palatal groove on the palatal side. The vertical cut lines were made 1-2 mm apical to the alveolar crests of the canine to the horizontal cut lines on the buccal and lingual sides. Small corticotomy perforations were drilled in the buccal and palatal cortical bone. There were about 20  perforations according to the alveolar process area in each patient.

These perforations were made to obtain additional bleeding points. (Fig 3 and 4). The corticotomy process was performed with a fissure bur (width 2 mm), The corticotomy cuts and perforations were made with a round bur (diameter 2 mm), under saline-solution irrigation. The width of bone cuts was approximately    2 mm, and the depth was carefully adjusted to reach the bone marrow by confirming bleeding through the cut lines. The mucoperiosteal flaps were sutured with absorbable surgical sutures.

Immediately after the corticotomies, the canines of the experimental and sham sides were moved distally along the orthodontic wire with a continuous force of 120 g by using nickel-titanium closed coil springs. The canines were retracted using closed Sentalloy coil springs (American orthodontics) on 0.0190 × 0.0250 stainless steel arch wires.

Fig 3. Vertical and horizontal corticotomy cuts and perforations on the buccal corticotomy side.

 

Fig 4. Vertical and horizontal corticotomy cuts and perforations on the palatal corticotomy side.

One end of the spring was fixed to the hook of the canine bracket with a ligature wire, and the other side was fixed to the hook of the band of the upper first molar. The length of each spring, which corresponded to a contractile force of 120g, was measured with a caliper and strain gauge, and the activation of the spring was set at that length. The force delivery was measured once a week. The distance between canine bracket and first molar hooks was recorded by using a Boley gauge at the following assessment times: after 1 week of corticotomy (T1), after 2 week of corticotomy (T2), after 4 week of corticotomy (T3), after 2 month of corticotomy (T4) and after 3 months of corticotomy (T5).

Fig 5. Measurement of the distance between canine bracket and first molar hooks with the Boley gauge.

To evaluate pain and discomfort levels and the levels  of satisfaction of the patients about corticotomy during the treatment two specific questionnaires were given to the treated patients. The first questionnaire was given to the treated patients at the following assessment times: after one day of corticotomy (T1), after 3 days of corticotomy (T2), after 5 days of corticotomy (T3), after 1 week of corticotomy (T4). The Second questionnaire was given to the treated patients at the following assessment times: after 1 month of corticotomy (T1), after 2 month of corticotomy (T2), after 3 months of corticotomy (T3).

Statistical Analysis

The error of the method was calculated for the distance of tooth movement based on double measurements on 10 randomly selected distances of tooth movement measurements and was estimated as       S = √∑(d)2/2n, where n = number of paired measurements and d = deviations between the 2 measurements.

The error of the method for measurement of tooth movement was 0.028  mm.

Comparison of tooth movement velocity between experimental and sham groups with Mann-Whitney U test.

Results

The movement velocity on the experimental side was also faster than that on the sham side throughout the experiment (Fig 6). There was a significant difference between the experimental and sham sides at T0-1 and T1-2; movement was approximately 4 times faster on the experimental side. There was a significant difference between the experimental and sham sides at T2-3 and T4-5; movement was approximately 3 times faster on the experimental side. at T3-4 There was a significant difference between the experimental and sham sides movement was approximately twice faster on the experimental side. The main significant findings of the treatment were: (1) There was a significant difference in tooth movement velocity, about 2-4 times  faster on the experimental compared with the sham side. (2) no significant differences were detected between males and females regarding tooth movement velocity on the experimental side. (3) no significant differences were detected between males and females regarding tooth movement velocity on the sham side.

The questionnaire showed: (1) the corticotomy has a high levels of pain, swelling and discomfort for the first week only. (2) no significant differences were detected between males and females with regarding pain and discomfort. (3) the degree of discomfort at activating the retracting spring was significantly greater on the sham side than that on the experimental side.

Discussion

This study was undertaken to investigate the influence of corticotomy on tooth movement between the CF and the Standard orthodontic techniques. Our results showed that the CF technique significantly accelerated tooth movement. The rate of tooth movement in the CF group was 2-4 times of that  in the S group.

tooth movement velocity on the experimental side was significantly faster than on the sham side at T0-1 and T1-2 approximately 4 times faster on the experimental side. Therefore, it is suggested that orthodontic tooth movement  increased especially in the early stage after the corticotomies.

These results agree with those of Iino et al,²⁴ who reported significant acceleration of tooth movement in their animal study. The findings corroborate the clinical observations of Wilcko et al^11,15 and Hajji,¹² who reported significant reductions in treatment time with CF orthodontics.

In this study, Tooth movement began immediately after corticotomy. On the other hand, Iino et al²⁴ used both labial and lingual corticotomy cuts near the moving premolar. The acceleration of tooth movement in this study was similar to that reported by Ren et al,²⁵ who used a surgical technique that depended on undermining the interseptal bone in a premolar-extraction canine experiment.

The anchorage loss was not measured in this study We focused on the influence of corticotomy on tooth movement.

after the corticotomies in our study, the alveolar bone reaction increased simultaneously with orthodontic tooth movement near the corticotomy possibly by RAP at an early stage.

Clinically, it is generally believed that a heavier orthodontic force is needed for the en-masse movement of the bone block with the tooth after a corticotomy. ^13,14,16,17 However, our results suggest that conventional orthodontic force would increase the velocity of orthodontic tooth movement, possibly by the acceleration of the bone turnover mechanism at an early stage after a corticotomy.

No significant differences were detected between males and females regarding pain and discomfort. This result agrees with this of  Ngan et al. ²⁶

Conclusion

This study shows that the alveolar corticotomy procedure increases orthodontic tooth movement with accepted degrees of pain and discomfort.

Fig 6. Comparison of tooth movement velocity between experimental and sham groups with Mann-Whitney U test.

 

Fig 7. Comparison of tooth movement velocity between males and females groups in experimental side.

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