Comparison of the Efficiency and Treatment Outcome of Patients Treated with Corticotomy-Assisted En masse Orthodontic Retraction with the En masse Retraction without Corticotomy.

BACKGROUND: Corticotomy in fixed orthodontic treatment gives a potential approach to reduce the treatment duration. Typically, this duration of rapid tooth movement lasts 4-6 months. AIM: The aim of this study was to compare the treatment outcome and effectiveness in en masse retraction with and without corticotomy.
MATERIALS AND METHODS: Thirty-two patients (male 16 and female 16) who opted to undergo surgery to reduce the orthodontic treatment time were chosen for the research, and the group consisted of 26 patients (male 13 and female 13) who did not opt for the corticotomy procedure were selected as the control. There was no blindness of the party distribution. It was focused on the patient's ability to opt for an additional minor surgical procedure that may affect orthodontic treatment length. The operation was conducted under local anesthesia (Lignox 2%). The same maxillofacial surgeon performed all the surgical operations.
RESULTS: The space present in the maxillary and mandibular arch at the time of retraction had no statistically significant difference in both the control and study groups (P > 0.05). In comparison, the mean amount of retraction space in the maxillary arch and maxillary arch was significant in the control and study groups at 1 month, 2 months, 3 months, and 4 months of the time interval.
CONCLUSION: It can be concluded that corticotomy-assisted retraction significantly decreases the total length of orthodontic care. Effectively stationary anchorage segment was made, thereby removing the need for other anchorage boosters, instrumental in maximum anchorage cases using corticotomy technique. Copyright:

INTRODUCTION

In patients with a maxillary-mandibular protrusion, orthodontic care is obtained to minimize lip procumbency. The most common way to straighten the profile is to extract the four first premolars and retract the anteriors with optimum anchorage. Incisor apices' level is an anatomical limit set by the alveolus' cortical plates, which serve as an obstacle to incisor retraction. Bone loss, root resorption, gingival recession, root dehiscence, and fenestration are few side effects of orthodontic retraction. Adult patients requiring orthodontic care also want their treatment to be done within the shortest possible time.[12]

Köle introduced selective alveolar decortication in 1959, where the entire bone segment's movement was possible. However, in 2001, Wilcko et al. came up with a new technique called periodontally accelerated osteogenic orthodontics, where they combined corticotomy with alveolar augmentation and orthodontic therapy. In this, regional acceleratory phenomenon (RAP) is observed, where there is increased bone turnover rate and decreased bone density, thereby accelerating the orthodontic tooth movement.[34]

One potential approach for shortening the orthodontic treatment time is by combining it with corticotomy. Typically, this duration of rapid tooth movement lasts 4–6 months.[56] Because of the restricted corticotomy-facilitated orthodontics studies in bimaxillary cases, this study aimed to assess the effectiveness and treatment outcome in en-masse retraction with and without corticotomy.

MATERIALS AND METHODS

Thirty-two patients (male 16 and female 16) who opted to undergo surgery to reduce the orthodontic treatment time were chosen for the research, and the group consisted of 26 patients (male 13 and female 13) who did not opt for the coticotomy procedure were selected as the control. There was no blindness of the party distribution. It was focused on the patient's ability to opt for an additional minor surgical procedure that may affect orthodontic treatment length. The operation was conducted under local anesthesia (Lignox 2%). The same maxillofacial surgeon performed all the surgical operations.

For the upper arch before flap elevation, premolars were removed at the time of corticotomy, and 0.019 × 0.025 in stainless steel wire with hooks was placed in the experimental group. From the distal aspect of the right canine to the left canine, a sulcular incision was placed, and up to 3 mm beyond that teeth apices full-thickness flap was raised. Selective alveolar decortication was performed. Number 2 round bur was used for surface punch holes, and 701 fissure bur was used for interdental scoring. At 2 mm beyond the teeth root apices, vertical cuts were connected by horizontal decortication. For palatal decortication, the palatal flap was raised, and decortication was performed accordingly. Demineralized freeze-dried allograft was mixed with normal saline was placed on the buccal and palatal region. A full-thickness flap was placed back and sutured using 4–0 silk suture, and archwire was placed again.

After 5–7 days, with a closed coil, nickeltitanium springs from the soldered hook to the first molar for en-masse retraction with 250 gf. Every month, that extraction space was measured using a digital vernier caliper on the study models. The distance between the pterygoid vertical to the first molar was measured on the lateral cephalogram. The jig's distance on the incisor and molar bracket to the sella vertical was measured to determine anchor loss and retraction. The space closure was contrasted before the beginning of retraction in both categories. The time taken in the corticotomy community for space closure was contrasted with space closure in the control group.

Statistical analysis

Data analyses were done using the Statistical package for the social sciences (SPSS) version 21 (IBM Corp., Chicago, Illinois, USA). The mean and the standard deviation were determined for any linear distance measured on the lateral cephalogram. To assess the statistical significance of the difference between left and right side variables within the maxilla and mandible, the paired t-test was used.

Independent t-tests were used to evaluate the statistical significance for retraction rate, anchor loss at T1 (before retraction), and T2 (during retraction period) between the sample and control groups. One-way ANOVA was used to check the anchor loss and rate of space closure every month, and Tukey's HSD was used for intergroup comparison. A (P < 0.05) was considered statistically substantial. The intensity of the sample is 0.95.

RESULTS

Maxillary arch and mandibular arch's mean retraction space difference at the time of retraction was not significant. In comparison, the mean amount of retraction space in the test and control group's maxillary arch was significantly different at T0, 1 month, 2 months, 3 months, and 4-month of the time interval [Table 1].

Table 1

Comparison of rate of retraction in the mandible and the maxilla during monthly intervals in the control group and study group

Arch involved	Monthly interval	Group	n	Mean (retraction space in mm)	SD	P
Maxillary arch	T0 (before retraction)	Study group	32	9.83	0.06	0.08
		Control group	26	8.72	0.07
	1	Study group	32	6.64	0.03	0.04
		Control group	26	7.65	0.04
	2	Study group	32	5.42	0.08	0.02
		Control group	26	6.62	0.07
	3	Study group	32	4.12	0.56	0.01
		Control group	26	5.24	0.12
	4	Study group	32	3.12	0.12	0.04
		Control group	26	4.18	0.67
Mandibular arch	T0 (before retraction)	Study group	32	8.83	0.12	0.07
		Control group	26	7.72	0.09
	1	Study group	32	5.64	0.12	0.04
		Control group	26	6.65	0.16
	2	Study group	32	4.42	0.09	0.03
		Control group	26	5.62	0.19
	3	Study group	32	3.12	0.07	0.04
		Control group	26	4.24	0.08
	4	Study group	32	2.12	0.05	0.01
		Control group	26	3.18	0.06

SD: Standard deviation

The mean anchor loss was significantly different in the maxillary arch at the monthly interval of 0–2 months, 2–4 months, while it was not significantly different in more than 4 months. The mean anchor loss was significantly different in the mandibular arch at the monthly interval of 0–2 months, 2–4 months, and more than 4 months [Table 2].

Table 2

Comparison of anchor loss rate in the mandible and the maxilla during monthly intervals in the control and study groups

Arch involved	Monthly interval	Group	n	Mean (anchor loss in mm)	SD	P
Maxillary arch	T02	Study group	32	0.02	0.03	0.04
		Control group	26	0.72	0.04
	24	Study group	32	0.27	0.08	0.02
		Control group	26	0.91	0.07
	>4 months	Study group	32	0.67	0.56	0.08
		Control group	26	0.71	0.12
Mandibular arch	T02	Study group	32	0.01	0.03	0.02
		Control group	26	0.68	0.04
	24	Study group	32	0.17	0.08	0.03
		Control group	26	0.81	0.07
	>4 months	Study group	32	0.37	0.56	0.02
		Control group	26	0.61	0.12

SD: Standard deviation

DISCUSSION

Two critical considerations in the treatment of maxillomandibular protrusion are the achievement of stable dental relations and esthetic rehabilitation. Several patients with protrusive jaws seek treatment to reduce the dental and lips' protrusion.[78] Typically, the treatment strategy includes retracting the anterior segment with maximum anchorage after extracting the four first premolars. During orthodontic treatment, time is an essential factor. In systematic analysis, Mavreas suggested that the treatment period for the four cases of premolar extraction was approximately 18.6 months.[910]

Long assessed the efficacy of orthodontic tooth movement acceleration interventions, corticotomy to be an efficient and secure treatment for accelerating orthodontic tooth movement. The protocol used in the current study may therefore be considered to be an efficient form of intervention.[1112] In the literature, there is enough evidence indicating corticotomy to be a practical choice for accelerated orthodontics.[1314]

Thus, delayed extraction of the first bicuspid would help accelerate tooth movement to take advantage of the maximum RAP response for 4 months. Furthermore, during the time of retraction, the undecorticated molar segment functions as an anchorage module.[15] Compared to traditional en mass retraction in maxillary-mandibular protrusion patients, this technique is used efficiently for better the anterior section's en masse retraction. During retraction, for reducing torque loss and for bodily or controlled tipping tooth movements, stainless steel archwire (0.019” × 0.025”) is placed to stabilize dentition.[16]

To serve as a stabilizing unit, the posterior section of the arch was not decorticated. Corticotomy was performed before aligning in Wilcko et al. protocol, and a supplementary procedure in which in the extraction space osteotomy is done, as would be inconvenient to the patient and costly. Thus, instead of extracting a large quantity of cortical bone around the first bicuspid, delayed extraction without removing the first bicuspid's cortical bone, more selected cases were conducted with very minimal crowding and delayed extraction did not prolong care.[1718]

Nevertheless, during the treatment, the mild inconvenience was seen as a result of temporary inflammation. In the corticotomy-assisted retraction, literature has not credibly reported molar anchor failure. Therefore, our analysis was designed to determine the retraction rate and molar anchor loss's degree throughout the retraction period. With lateral cephalogram aid, anchor loss was evaluated similarly to the method suggested by Badri Thiruvengadachari, where in order to distinguish between right and left molar, modified jigs were mounted on the upper and lower the first molar of both sides.[19]

Closure of extraction space, successful retraction, and anchor loss were evaluated for approximately 4–5 months in the test and control groups. The test and control groups were comparable as the extraction space did not differ significantly though extraction was done early in the control group. The mean for maxilla was 7.63 mm and 6.77 mm in the mandible.

The study results are in conjunction with the study done by Aboul-Ela et al., in which they found that after 2 months, the amount of space closure peaked and decreased eventually at the end of the 4th month. As Frost stated, the above phenomenon may be purely linked to the RAP phase for a brief period of our months. Therefore, the retraction was fastest during the first 4 months. There was a loss of space for 4–6 months due to anchor loss of 0.6 mm in an average in the maxilla and mandible.[1820]

As most of the studies used temporary anchorage devices, there is no substantial literature on anchor loss in corticotomy-assisted orthodontics. This research will possibly be the first to link, to the best of our knowledge, loss of anchor value and the nondecorticated posterior arch section as the stabilizing unit. Likewise, in a previous analysis of WookHeo's traditional en-masse retraction, approximately 1 mm of anchor loss results from 4 mm of incisor retraction.[1920] As the current study did not assess the entire retraction period; therefore anchor loss during the later retraction stages cannot be commented on.

CONCLUSION

It can be concluded that corticotomy-assisted retraction significantly decreases the total length of orthodontic care. The need for anchorage boosters can be eliminated by making the anchorage segment stationary in maximum anchorage cases by selective decortication.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.