The Prevalence of Root Resorption after Orthodontic Treatment in Patients Attending a University Hospital Dental Clinic

Abstract

Introduction:

After orthodontic treatment, some teeth undergo external root resorption due to different factors, such as the root shape, oral habits, biological and genetic factor, gender, and age. Furthermore, extraction cases, long treatment duration, and the amount of force applied during the treatment might be related to root resorption.

Materials and Methods:

Panoramic radiographs for 226 patients treated in the orthodontic department were screened. The lower first permanent molars, lower second premolars, and lower first premolars were measured in centimeters on a ruler using ImageJ System. Teeth were measured from the cusp tip to the cementoenamel junction (CEJ) and from the CEJ to the root apex, and then, the tooth was measured as a whole before and after the treatment.

Results:

Multiple analysis of variance showed that there were no interactions between the root lengths of all teeth tested and either gender, treatment type, or treatment duration (P > 0.05).

Conclusion:

Based on the results of this study, no statistically significance relationship between external apical root resorption and gender, type of treatment, and treatment duration was found.

INTRODUCTION

Root resorption is defined by Ne et al. “as a condition associated with either physiologic or pathologic process resulting in the loss of dentine, cementum, or bone.”[1] Some teeth undergo external root resorption after the orthodontic treatment due to many factors, such as the root shape, oral habits, biological, genetic factors, gender, and age.[2,3,4,5,6] Further, root resorption has been linked to orthodontic cases with extraction, long treatment duration, and the amount of force applied during the orthodontic treatment.[7,8] Root resorption is considered the prominent hidden scars of orthodontic treatment. It constitutes a nightmare for almost all orthodontists.[9]

Brezniak and Wasserstein formulated the term “orthodontically induced inflammatory root resorption” to denote this kind of root resorption and differentiate it from others such as those caused by periodontal lesions or trauma.[10] Abbas and Hartsfield found an incidence of about one in every 20 orthodontically treated subjects having at least 5 mm of root resorption. This information considers root resorption as the second most common unfavorable consequence of orthodontic treatment after white spot lesions of the enamel.[11] The focus of this research is to study the prevalence of external apical root resorption (EARR) after orthodontic treatment in patients treated at the Department of Orthodontics by postgraduate residents in King Abdulaziz University Faculty of Dentistry and to evaluate the association of EARR with gender, type of treatment, and duration of the treatment.

MATERIALS AND METHODS

This was a cross-sectional study done in patients attending Dental Clinic of King Abdul Aziz University Hospital for fixed orthodontic treatment. Panoramic radiographs for 226 patients treated in the orthodontic department were screened. The inclusion criteria were (1) adult patients, (2) roots with closed apices, (3) no evidence of root reposition before the treatment, (4) healthy patients, and (5) complete records/data and proper panoramic radiographs before and after the treatment. The exclusion criteria were (1) patients who did not complete the treatment.

Fifty-four cases satisfied our inclusion criteria; among the included cases, 31 were females and 23 were males with a mean age of 18 years and the mean treatment duration is 41.5 months. The lower first permanent molars, lower second premolars, and lower first premolars were measured in centimeters on a ruler using ImageJ software version 1.44; (National Institutes of Health, Bethesda, MD, USA). Teeth were measured from the cusp tip to the cementoenamel junction CEJ and from the CEJ to the root apex, and then, the tooth was measured as a whole before and after the treatment. To compensate for any magnification in the panoramic radiographs, the following equation was used on an excel sheet 100 − (X × 100/Y) where X is referred to the mesiodistal width of a magnified permanent tooth in the panoramic radiograph before the treatment and Y is referred to the mesiodistal width of the same tooth in the panoramic radiograph after the treatment.

EARR was classified using four-grade ordinal scale proposed by Scott McNab: grade 0 means no apical root resorption is found, grade 1 blunt root apex, grade 2 moderate resorption of root apex beyond blunting and up to one-third of the root length, and grade 3 severe resorption of root apex beyond one-third of the root length.

Statistical analysis

Data were tabulated and analyzed using the Statistical Package for the Social Sciences (IBM SPSS Statistics for Mac, Version 20.0. Armonk, NY: IBM Corp, USA). The Shapiro–Wilk test showed that the data were not normally distributed, so nonparametric tests were used throughout the study. Mann–Whitney tests were used for bivariate comparisons between treatment type and EARR and gender and EARR. Spearman's rank correlation coefficient (rho) was used to establish a correaltion between treatment time and root resorption. A statistical significance was considered at P < 0.05.

RESULTS

The case summaries of all the teeth are given in Table 1. Nonparametric tests were used to compare the treatment type whether extraction or not and also between genders. Mann–Whitney tests showed that there were no significant differences in the lengths of the roots for all teeth studied between extraction and nonextraction cases [Table 2] and also between genders [Table 3], P > 0.05.

Table 1.

Case summaries of resorption measurement (cm)

Gender	Treatment	Premolar				Molars
		Premolar 45	Premolar 44	Premolar 35	Premolar 34	Molar 46 distal root	Molar 46 mesial root	Molar 36 distal root	Molar 36 mesial root
Male	Nonextraction
	n	16	16	16	16	16	16	16	16
	Mean (SD)	0.0625 (0.2500)	0.2500 (0.5773)	0.1875 (0.4031)	0.000 (0.000)	0.063 (0.250)	0.063 (0.250)	0.063 (0.250)	0.000 (0.000)
	Extraction
	n	7	2	7	2	5	5	6	6
	Mean (SD)	0.2857 (0.4879)	0.500 (0.7071)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)
	Total
	n	23	18	23	18	21	21	22	22
	Mean (SD)	0.1304 (0.34435)	0.2778 (0.5745)	0.1304 (0.3443)	0.000 (0.000)	0.048 (0.218)	0.048 (0.218)	0.046 (0.213)	0.000 (0.000)
Female	Nonextraction
	n	24	24	24	23	22	22	22	22
	Mean (SD)	0.0417 (0.2041)	0.0417 (0.2041)	0.125 (0.3378)	0.1304 (0.3443)	0.000 (0.000)	0.000 (0.000)	0.046 (0.213)	0.000 (0.000)
	Extraction
	n	7	1	7	1	7	7	7	7
	Mean (SD)	0.000 (0.000)	0.000 (-)	0.000 (-)	0.000 (-)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)
	Total
	n	31	25	31	24	29	29	29	29
	Mean (SD)	0.0323 (0.180)	0.04 (0.200)	0.0968 (0.301)	0.125 (0.338)	0.000 (0.000)	0.000 (0.000)	0.035 (0.186)	0.000 (0.000)
Total	Nonextraction
	n	40	40	40	39	38	38	38	38
	Mean (SD)	0.05 (0.221)	0.125 (0.404)	0.150 (0.362)	0.0769 (0.270)	0.026 (0.162)	0.026 (0.162)	0.053 (0.162)	0.026 (0.226)
	Extraction
	n	14	3	14	3	12	12	13	13
	Mean (SD)	0.1429 (0.363)	0.333 (0.577)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)	0.000 (0.000)
	Total
	n	54	43	54	42	50	50	51	51
	Mean (SD)	0.0741 (0.2644)	0.1395 (0.4130)	0.111 (0.317)	0.0714 (0.261)	0.020 (0.141)	0.020 (0.141)	0.039 (0.196)	0.000 (0.000)

SD: Standard deviation

Table 2.

Bivariate comparisons=Grouping variable: Treatment (extraction vs. nonextraction)

P*
Molar 46 distal root	Molar 46 mesial root	Bicuspid 45	Bicuspid 44	Molar 36 distal root	Molar 36 mesial root	Bicuspid 35	Bicuspid 34
0.574	0.574	0.258	0.247	0.403	1.000	0.128	0.622

*P>0.05 is considered statistically significant

Table 3.

Bivariate comparisons=Grouping variable: Gender

P*
Molar 46 distal root	Molar 46 mesial root	Bicuspid 45	Bicuspid 44	Molar 36 distal root	Molar 36 mesial root	Bicuspid 35	Bicuspid 34
0.240	0.240	0.177	0.066	0.843	1.000	0.0700	0.124

*P>0.05 is considered statistically significant

Bivariate correlation was performed between the amount of root resorption and treatment time. The Spearman rho showed no significant correlation between treatment time and the amount of root resorption for the teeth studied (P > 0.05).

DISCUSSION

This retrospective study investigated the prevalence of root resorption after orthodontic treatment in relation to age, gender, duration of the treatment, and extraction cases through panoramic radiographs. Although panoramic radiographs have limitations in the evaluation of the root shape and apical area, they were used because periapical radiographs were not available for all patients and because panoramic radiographs are taken by any orthodontist before and after orthodontic treatment.

To compensate for any magnification in panoramic radiographs, a specific equation was used. To discriminate any possibilities of changing in the crown instead of having apical root resorption, teeth were measured from the cusp tip to the CEJ and from the CEJ to the root apex, and then, the tooth was measured as a whole using ImageJ System.

Out of 54 cases, only 11 cases had EARR. These results showed no statistically significant relationship between EARR and gender as in previous studies of Pandis et al.,[12] Krieger et al.,[13] and Sunku et al.[14]

Further, there was no statistically significant relationship between EARR and the type of the treatment whether extraction or not; this is similar to a study done by Pandis et al.[12] Another study done by Sunku et al. reported that there is an association between EARR and cases treated with extraction.[14]

In addition, the current study showed no statistical significance between EARR and duration of the treatment; this is contrary to the study of Pandis et al., which concluded that there is statistical significance between the duration of the treatment and EARR.[12]

As regards the management of root resorption during orthodontic treatment, many researchers tried to introduce means to control this root resorption other than postponement of treatment. A group of researches tried medical agents such as echistatin,[15] bisphosphonates,[16] and lithium chloride,[17,18] while others tried the use of physical means such as low-intensity pulsed ultrasound.[19,20,21]

Limitations

One of the limitations in the study was the small sample size because some of the patients records had incomplete data; in addition, most of the panoramic radiographs were not clear. Furthermore, periapical radiographs and cone-beam computed tomography would be more useful to evaluate EARR than panoramic.

CONCLUSION

Within the limitation of the current study, no statistically significance relationship between EARR and gender, type of treatment, and treatment duration was found. Individual susceptibility could be one the main risk factors for root resorption in adults.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.