Volume 30 Issue 4 Article 7

2020

Decision Making on Tooth Extraction in Orthodontics Decision Making on Tooth Extraction in Orthodontics

Yu-Ting Sun Chung Shan Medical University Hospital, Taichung, Taiwan; College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Chia-Tze Kao Chung Shan Medical University Hospital, Taichung, Taiwan; College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan, ctk@csmu.edu.tw

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Recommended Citation Recommended Citation Sun, Yu-Ting and Kao, Chia-Tze (2020) "Decision Making on Tooth Extraction in Orthodontics," Taiwanese Journal of Orthodontics: Vol. 30 : Iss. 4 , Article 7. DOI: 10.30036/TJO.201812_30(4).0007 Available at: https://www.tjo.org.tw/tjo/vol30/iss4/7

This Case Report is brought to you for free and open access by Taiwanese Journal of Orthodontics. It has been accepted for inclusion in Taiwanese Journal of Orthodontics by an authorized editor of Taiwanese Journal of Orthodontics.

247Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

INTRODUCTION

The options of extraction versus nonextraction

therapy in orthodontics has remained as a controversial

topic for a long time. In the early 20th century, Angle

favored non-extraction orthodontic treatment and be-

lieved that an intact dentition was essential to achieve

an ideal esthetics and stability. However, Tweed, one of

Angle’s student, noted that many of his cases relapsed

especially those with proclined lower incisors. He had to

retreat the patients by tooth extraction of four premolars

to achieve better functional and aesthetic outcome. Since

then, premolar extraction was adopted as treatment

strategy to correct the malocclusion in the late 20th

century.1 Currently, with the development of miniscrews

and the changes in concept of facial attractiveness, the

rate of tooth extraction for orthodontics has declined. It is

necessary to completely evalu-ate the individual patient’s

dental, facial and skeletal patterns to offer a correct

diagnosis and proper treat-ment plan.

Case Report

Extraction or non-extraction is an issue that we face in our daily orthodontic practice. Before deciding the

treatment plan, we have to examine the case carefully. Orthodontic tooth extraction involves more than just the

need to create space in the arches but also the concerns of facial esthetics and treatment stability. The report

presented a case of teenage boy with severe external root resorption of tooth 27, 37, 46, 47 which caused

by impaction of third molars and a supernumerary premolar. Patient already had orthodontic treat-ment

before and did not favor a comprehensive orthodontic treatment again. Tooth extraction of 27, 37, 47 and the

supernumerary premolar were conducted. The lingual holding arch with hook was used to upright the mesially

erupted third molar. The opinion and philosophy of the tooth extraction decision making was discussed.

(Taiwanese Journal of Orthodontics. 30(4): 247-255, 2018)

Keywords: tooth extraction in orthodontics; third molar uprighting; external root resorption caused by impacted tooth.

decision making on TooTh exTracTionin orThodonTics

Yu-Ting Sun, Chia-Tze KaoChung Shan Medical University Hospital, Taichung, Taiwan

College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Received: July 24, 2018 Revised: August 9, 2018 Accepted: December 18, 2018Reprints and correspondence to: Dr. Chia-Tze Kao, Department of Dentistry, Chung Shan Medical University, Taichung, Taiwan No.110, Sec. 1, Jianguo N. Rd., South Dist., Taichung City 402, Taiwan Tel: +886-4-24718668 Fax: +886-4-24759065 E-mail: ctk@csmu.edu.tw

248 Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

with the distal root of the tooth 27. Surgical removal of

28 was suggested; but the pa-tient preferred to follow

the tooth instead (Figure 4). Until 2014, he came to our

clinic again for periodic observation. The panoramic film

demonstrated impaction of tooth 18, 28, 38, 48 and severe

root resorption of tooth 27, 37, 46 and 47. Moreover,

drift of the supernumerary tooth and causing the 46

severe mesial root resorptions (Figure 5). The cone-beam

computed tomography (CBCT) scan revealed that 46

mesiobuccal and mesiolingual root resorption to the level

of furcation, more than half length of 47 and 37 distal

roots were resorbed, palatal root of 27 was completely

resorbed and the distobuccal root was reduced in half

length (Figure 6).

CASE REPORT

This boy who was referred for orthodontic

consultation due to bilateral posterior cross-bite and

dental crowding in the upper arch when he was 13 years

old (Figure 1). Our treatment plan was conducted by non-

extraction with Hyrax expander to expand maxilla at that

time. Then alignment the teeth was achieved in the first

orthodontic treatment. In the post-treatment panoramic

X-ray, we noticed there is supernumerary tooth under

tooth 45 and the presence of the tooth germs of all four

third molars (Figure 2, 3). After 2-year fol-low-up, the

root development of the supernumerary tooth was evident.

Also tooth 28 was more mesially erupted, overlapped

Sun YT, Kao CT

Figure 1. Initial intraoral photograph.

249Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

Decision Making on Tooth Extraction

Figure 2. Completion of the first orthodontic treatment.

Figure 3. Panoramic film at the completion of the first orthodontic treatment.

250 Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

Sun YT, Kao CTSun YT, Kao CT

Figure 4. Follow-up panoramic film, 2 year after completion of the first orthodontic treatment.

Figure 5. Follow-up panoramic film, 5 year after completion of the first orthodontic treatment.

Figure 6. The CBCT indicated the external root resorption of 27, 38, 46 and 48.

251Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

Treatment progress and resultsBefore the surgical removal of 18, 27, 37,4

7 and the supernumerary tooth, the patient had 46

root canal treatment. After the surgical removal of

the aforementioned teeth, 6 months was waited for

spontaneous eruption of the third molar. The mesial

inclination of tooth 38 48 was noted. Lingual holding

arch was fabri-cated with a 0.032-inch stainless steel

wire, protraction hooks was soldered to the bands on

bilateral man-dibular first molars. Lower third molars

were bonded with brackets and lingual buttons on the

exposed cusps. Elastomeric chains were used to protract

and extrude 38,48 (Figure 7). Sectional wires with 0.018-

inch stainless steel L-loop were inserted in both sides of

lower arch (Figure 8). The 0.017x0.025-inch TMA wires

were used to upright molars sequentially. 38 48 were well

uprighted after ten months. After finishing and detailing

was completed, the removable wraparound retainer

was delivered to patient at debond. The total treatment

duration was 14 months (Figure 9, 10).

Treatment objectivesBecause the patient didn’t have the problem of

space discrepancy in the anterior region nor protrusive lip

profile. Functionally, the posterior cross-bite did not cause

his difficulties in chewing. Additionally, he had finished

the first orthodontic treatment few years ago. He only

wanted to have optimal orthodontic treat-ment. Thus, the

treatment objective was only to upright the lower third

molars and close the space.

Treatment planAfter discussing with the patient and his parents, the

treatment plan was as followings:

(1) Endodontic treatment of 46

(2) Tooth extraction of 18, 27, 37, 47 and the supernumerary

premolar

(3) Lingual holding arch with traction hook to protract

and upright third molars

(4) Wrap-around retainers

Decision Making on Tooth ExtractionDecision Making on Tooth Extraction

Figure 7. Initiation of second orthodontic treatment.

252 Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

Sun YT, Kao CT

Figure 10. Photographs at the completion of the orthodontic treatment.

Figure 8. Sectional 0.018-inch stainless steel archwires with L-loop in both sides.

Figure 9. Panoramic film at the completion of the orthodontic treatment.

253Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

4. Growth and anteroposterior relationships: Pubertal

growth spurt usually starts between the age of 10 to

12 in girls, and 12 to 14 in boys, subject to individual

variations.4 The cervical vertebral mmaturation

method5,6

or hand-wrist radiograph7-9

could be used to

predict the growth stage. If a patient still has growth

potential, we may correct the skeletal discrepancy

without extraction. While in adult patients, dental

extraction plans would be considered for camouflage

the skeletal discrepancy, or orthognathic surgery for

correction of the jaw relation.

5. Dental asymmetry: Lewis listed 5 common causes of

midline deviations.10

With proper diagnosis, some cases

can be treated with asymmetric mechanics to correct

the deviation. Patients with severe dental midline

deviation relative to the face may require asymmetric

extractions. Small asymmetries can be corrected with

intermaxillary elastics, miniscrews or interdental

stripping.11-13

6. Facial pattern: Patients with different facial patterns

response to orthodontic treatment differently. For

dolichofacial patients, distal tooth movement should be

planned with cautious by not to wedge the man-dible

and open the bite. On the other hand, for brachyfacial

patients, tooth extractions tend to deepen the bite

during the space closure. Although patients with

hyperdivergent facial pattern usually show greater

anchorage loss than those with hypodivergent pattern;

this is not always true. In general, we like to treat high

angle cases with extraction of posterior teeth, followed

by loss of anchorage to correct the increas-ed lower

facial height with resultant counterclockwise rotation

of the mandible. However, Kim et al has questioned

the effect of wedge effect concept.14

The biomechanics

of space closure with different facial pattern should be

considered in treatment.

7. Pathologies: Some pathologies play a key role in

determine orthodontic treatment plan. The advanced

periodontal problems, ectopic eruption, deep caries

DISCUSSION

Extraction or non-extraction is the most common

dilemma that we encounter in our practice, especially for

the borderline case. It is essential to examine the case

thoroughly to establish an effective treatment plan. To

discuss the extraction or not, there are many factors to be

considered. Ruellas et al listed seven factors to evaluate

the proper decision of tooth extraction as followings.2

1. Compliance: Sometimes we need addi t ional

compliance to achieve treatment success. For example,

the treatment options in growing patient with skeletal

Class II may include headgears and functional appli-

ances. Nowadays, with the aid of miniscrews, similar

treatment outcomes can be achieved whether con-

ducted with or without tooth extractions in some

borderline cases. Otherwise, lack of compliance can

lead to revise the plan to extractions.

2. Tooth-arch discrepancy: Proffit and Fields reported

that in less than 4 mm arch length discrepancy,

tooth extraction is rarely indicated, except in cases

with incisor protrusion or vertical discrepancy.3

Small negative discrepancies can be treated without

extractions by interproximal dental stripping, up-

righting the lower posterior teeth and arch expansions.

Arch length discrepancy of 5 to 9 mm allow treatment

to be performed with or without extractions, depending

on the hard and soft tissue characteris-tics of the

patient and how the final position of the incisors will be

moved. For arch length discrepancy of 10 mm or more,

extraction is commonly required.

3. Cephalometric discrepancy and facial profile: In

situations of pronounced proclination of the incisors

and convex profile, extractions are often required to

improve the patient’s lip profile by tooth extraction.

Currently, we put more emphasis on soft tissue profile

rather cephalometric measurements. Therefore, we

should bear in mind not worsen the soft tissue profile

in order to retract the teeth to match the cepha-lometric

norm values.

Decision Making on Tooth Extraction

254 Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

that he had mesioden removal when he was 8 years of

age. Solares and Romero reported that patients with a

previous history of supernumerary teeth in the anterior

region may have a 24% possibility of developing su-

pernumerary premolars at a later stage.16

Therefore, it

is important to have panoramic radiograph taken peri-

odically follow up in long term to detect the formation of

other supernumerary tooth later in dental devel-opment. If

the supernumerary tooth does not cause any complications

to adjacent tooth or structure, yearly monitor with

radiographic examination is required. The patient should

be informed of possible complica-tions of cystic change

and migration to damage the nearby roots.17

Nemcovsky et al observed the effect of nonerupted

third molars on distal roots and supporting structures and

reported that the apical position and mesial inclination

of 60° or more of the impacted third molars may

be the factors associated with root resorption in the

proximal second molars.18

However, using the orthopan-

tomography or periapical film to locate the tooth position

would be misled by overlap of the objects. With the use

of CBCT, the external root resorption could be explored

more accurately. It is advised to take 3D image when there

is a close relation of impacted tooth with normal tooth

root seeing in 2D image.

CONCLUSION

1. Decision of orthodontic tooth extraction should not

only rely on space discrepancy but also for other

aspects, such as facial aesthetics and stability.

2. External root resorption of the second molar caused

by impacted molar could be avoided with preven-tive

extraction. With the use of CBCT, better evaluation

makes the correct decision. Treatment varies according

to the severity of resorption. When a permanent molar

demonstrates severe root resorption, an impacted third

molar can effectively substitute the tooth by mesially

movement with an appropriate orthodontic approach.

or endodontic lesions may indicate for tooth extrac-

tion. When extraction is planned, the tooth with

pathology could be a viable extraction alternative for

the premolar.

In this case report we may observe the treatment

outcome is not satisfy to all. The extraction of first molar

rather than the supernumerary premolar could also be

an option for extraction. In the light of seven extrac-

tion diagnostic elements mentioned above, pathology

is the key element in deciding which teeth to extract in

our case. If tooth extraction of 27, 37, 46 and 47 were

planned for the root resorption, the patient would have

no occlusion at right side for a period of time since

46, 47 were missing. We might need to tract the super-

numerary premolar prior to upright the bilateral lower

third molars. After discussing with the parents of the

patient, minimal intervention of current occlusion was

decided. Thus, extraction supernumerary premolar rather

than 46 was finally decided. Despite the fact that we chose

to keep 46, the periodontal findings were normal without

tooth mobility after completion of treatment. Whether a

complete functioning dentition will persist with age is

unknown.19

With precaution, the patient was encouraged

to keep good oral hygiene. Kalkwarf et al pointed out that

the prognosis of apical resorption of the root would be

better than the perio-dontal destruction with the loss of

alveolar bone support.20

We didn't aware of the supernumerary premolar

until 2-year follow-up; the root development of the su-

pernumerary tooth was evident. Although we suggested

to remove the supernumerary premolar, but the pa-tient

favored to monitor the progress instead. He lost follow-up

and came back to the clinic three years later. Significant

root resorption of 27, 37, 46, 47 were noted.

Rubenstein and Lindauer et al reported that the

supernumerary premolars may not become radiograph-

ically visible until well after the patient’s normal

premolars have erupted.15

In addition, the patient recalled

Sun YT, Kao CT

255Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 410.30036/TJO.201812_30(4).0007

9. Houston, W. Relationships between skeletal maturity

estimated from hand-wrist radiographs and the timing

of the adolescent growth spurt. European J Orthod

1980;2:81-93.

10.

11.

Lewis P. The deviated midline. Am J Orthod.

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Narmada S, Kumar KPS, Raja S. Management of mid-

line discrepancies: a review. J Indian Acad Dent Spec

Res 2015;2:45-8.

12. Jerrold L, Lowenstein J. The midline: diagnosis

and treatment. Am J Orthod Dentofacial Or-thop

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13. Rebellato J. Asymmetric extractions used in the

treatment of patients with asymmetries. Semin Orthod

1998;4:180-188.

14. Kim TK, Kim JT, Mah J, Yang WS, Baek SH. First or

second premolar extraction effects on facial ver-tical

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15. Rubenstein LK, Lindauer SJ, Isaacson RJ, Germane

N. Development of supernumerary premolars in an

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3. When a supernumerary premolar develops at a later

stage, periodic panoramic radiograph should be

monitored for any pathological change. If the patient

had previous history of supernumerary tooth in the

anterior region, there would be a 24% possibility to

develop another supernumerary premolar at later stage.

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Decision Making on Tooth Extraction