Extraction or Nonextraction in Orthodontic Cases: A Review

Abstract

Orthodontic treatment helps bring teeth in alignment. There is always debate whether tooth should be extracted or not for treating crowding. The present article highlights various advantages and disadvantages of extraction.

INTRODUCTION

Orthodontic treatment helps bring teeth in alignment. There are numerous conditions which require orthodontic treatment. These are spacing, crowding, tipping, transportation, increased overjet, overbite, etc., The management of orthodontic cases has been performed since ages. Crowding is the condition when there is minimum space for teeth to be in alignment; hence, teeth are crowded.[1] The management of such condition can be with extraction of few teeth or nonextraction with movement of teeth. In the 1960s, the therapeutic extraction became common with an aim to treat crowding. Till the 1990s, the trend declined; then again, there was a rise in the extraction cases.[2]

HISTORY

Deciduous teeth have been extracted since many years to create space for permanent teeth to erupt in right place. However, few dentists started extracting permanent teeth also as there was requirement of more space. Hunter[3] in 1771 was in disagreement and gave the clarification that with the extraction of permanent teeth; there is a chance of growth inhibition.

In the 18^th century, extraction of maxillary first premolars was considered to be the best treatment option in cases of class II, division I malocclusion. Delabarre suggested that first, one should plan whether extraction is really helpful or not. Davenport[4] in his speech in New York suggested loss of teeth as loss of an important organ. Angle,[5] the father of modern orthodontics, was in favor of extraction of teeth for bringing out better results. Multiple case series and research data are available in his book entitled, “Treatment of Malocclusion of the Teeth and Fractures of the Maxillae-Angle System.”

Rousseau, a philosopher, was again in opposition who declined the concept of extraction. He pointed out that an ideal occlusion may not necessarily be accomplished by extraction. Later on, Julius Wolff introduced the Wolff's law of bone in which he revealed that stress can lead to alteration of trabeculae. He postulated that when force is applied to teeth, bony trabeculae show changes in response to stress produced by forces.

Angle suggested that orthodontic forces may lead to growth of bone if teeth were placed in a proper occlusion. He mentioned his edgewise appliance as a “bone growing appliance.” He proposed the idea that there is an interrelation of dentition with facial profile. There is an alteration in facial esthetics with the movement of teeth, and esthetics is the best when all teeth are aligned in occlusion. He tried to preserve all natural teeth of patients by expanding the dental arches.

CONTROVERSY

Facial profile

One of the factors which plays an important role in deciding whether extraction should be performed or not, is the facial profile. Those who oppose extraction suggested that there is dish in of the face with extraction whereas those in favor thought that there will be fullness of facial profile.[6] A study of Rushing et al.[7] on effects of orthodontic extraction on facial profile suggested that most of the dental surgeons and orthodontists cannot judge whether extraction has been performed or not without seeing the patient clinically. This was supported by the work of Stephens et al. and Erdinc et al.[8]

Solem et al.[9] conducted a study (2013) in which they assessed the effect of bimaxillary protrusion on soft and hard tissues of the face. The authors found that there was subsequently retraction of upper lip post extraction. They suggested that extraction may be helpful in patients having fuller profiles and hence there are less chances of “dish-in” of the face; therefore, extraction is the best option in these patients. There is a need to study the case extensively as facial profile may show alteration due to overretraction of the maxillary anterior segment.

Konstantonis et al.[10] evaluated the effect of extraction on the soft tissue profile of patients. This was a meta-analysis performed on 9 databases. They assessed 24 studies which comprised 1456 patients and found that there was a mean difference of 1.96 mm between upper and lower lips. Extraction of teeth resulted in increased lower lip retraction. They studied 1149 patients in 21 studies and found a mean difference of 1.26 mm between upper and lower lips and suggested an association of extraction with upper lip retraction. Twenty-one studies comprised 109 patients which revealed association of extraction with nasolabial angle with a mean difference of 4.21°. Six studies were on profile convexity on 408 patients, in which the mean difference of 1.24° was found. Three studies showed a standardized mean difference of 0.41 in 249 patients. They suggested that patient profile may be affected with extraction; hence, no specific profile outcome may be proposed.

BUCCAL CORRIDORS

It is a belief of few researchers that extraction of maxillary premolars bring narrowing of the maxilla, leading to broader buccal corridors. Ioi et al.[11] in their study assessed the effect of smile esthetic on buccal corridor. In this study, a patient picture showing the maxillary right first molar to left first molar (16–26) was displayed; buccal corridors were modified digitally in 5% increments, from 0% to 25% buccal corridor compared with the inner commissural width and distributed among 32 Japanese orthodontists and 55 Japanese dental students to rate the six smiles. The authors found no significant difference in deciding the effects of buccal corridors on the smile attractiveness between both gender raters for both groups of dental surgeons. Both groups of dentists showed significant differences in the median esthetic scores. The median esthetic score decreased to become clinically significant from 10% to 25% buccal corridor for both groups. The result of this study was supported by the results obtained by Meyer et al.[12] who also suggested that broader buccal corridors may be attractive and extraction of maxillary premolar does not necessarily lead to narrow maxillary ridges.

TEMPOROMANDIBULAR JOINT DISORDERS

It is usually misconcept that extraction of teeth in orthodontic patients leads to temporomandibular joint disorders (TMDs). Hardly, there is any correlation of TMDs and orthodontic tooth extractions.[13] Gianelly et al.[14] in their study recruited 111 patients, out of this 79 patients underwent orthodontic treatment without extraction, 32 underwent extraction, 27 with 1 or more premolar extraction, and 5 with anterior tooth extraction. In all patients, assessment of condylar position was done before and after treatment. The results revealed nonsignificant difference in pretreatment and posttreatment condylar positions in all cases. The authors suggested that there is no movement of condyle during orthodontic treatment.

STABILITY LOSS

Bowman et al.[15] suggested that nonextraction of teeth in every patient may not always be helpful since there is variation in oral conditions in reference to positioning, tipping, and crowding in different patients. Thus, extraction may be planned in some cases to obtain better results. Erdinc et al.[16] in their study revealed that the extraction of premolars for orthodontic treatment to improve crowding may not augment stability.

RISK OF IMPACTION

Saysel et al.[17] suggested that with the extraction of premolars in orthodontic patients, there is more space for the third molar to erupt, hence the chances of impaction decreases. Turkuz et al.[18] found that approximately 81% of cases of third molar impaction in those patients who did not go for extraction of premolars, whereas only 63% of third molar impaction cases were found in extraction cases. Cassetta et al.[19] conducted a study, which comprised 40 patients with mandibular second molar impactions and 200 patients without second molar impactions. The study group exhibited significant presence of crowding, a smaller distance between the anterior margin of mandibular ramus and mandibular first molar, and higher angle of mandibular second molar inclination.

EXPANSION

It is suggested that expansion of maxillary arch may be useful in resolving crowding. Rapid maxillary expansion (RME) can be fruitful in borderline crowding (3–6 mm) in the mandible in patients with narrow transpalatal widths. It is evident that there is reciprocal mandibular expansion in reference to RME.[20]

Housley et al.[21] in their study found that 8% of patients had significant intercanine widths for more than 6 years who underwent mandibular expansion. Risk such as regression of labial or buccal cortical plate is seen in maxillary expansion cases.

PRESERVATION OF LEEWAY SPACE

It is evident that leeway space may be utilized for the treatment of mild-to-moderate crowding in patients with Class I and II malocclusion. Sonis et al.[22] found that the use of a lingual arch in the mixed dentition may be used for resolving mild-to-moderate crowding. However, in moderate-to-severe crowding, extraction of premolars is the best option. According to the contemporary extraction guidelines, extraction is rarely indicated in <4 mm of arch length discrepancy, posterior extraction may be required with 5–9 mm of arch length discrepancy and with >10 mm arch length discrepancy extraction is always required.[23]

AIR-ROTOR STRIPPING

It is suggested that approximately 6–8 mm of the space can be achieved to resolve protrusion, crowding, or a combination of both.[24]

CONCLUSION

The authors suggested that extraction and nonextraction of teeth in the treatment of crowding is solely an orthodontist decision. The consideration of advantages and disadvantages of extraction is essential before planning treatment.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.