User:Globalorthodontist/Extraction in orthodontics

Extractions in orthodontics can place due to several reasons such as crowding or surgical patterns.

Lower Incisor
Lower incisor extraction can be used as a treatment modality.

Indications

 * Non-surgical treatment of a mild-moderate Class III malocclusion to achieve positive overjet and overbite
 * Incisal crowding in adults due to relapse
 * Bolton discrepancy which is excess in bottom arch, and deficient in maxillary arch
 * Periodontally compromised lower incisor
 * Severally crowded or malpositioned lower anterior incisor

Contraindications

 * Deep bite cases
 * Minimal crowding in lower arch (<4mm)

Advantages

 * Maintains or reduces intercanine width
 * Crowding is resolved quickly due to space near crowding
 * Likeliness of relapse is reduced

Second Premolars
Extraction of second premolars is often done in orthodontics due to following reasons stated below. In 1964, Hayes Nance advocated for second premolar extraction at the Angle Society meeting and considered this technique to be a hidden facet in the field.
 * Mild/moderate degree of crowding in a patient where an excellent profile must be maintained
 * 2nd premolars with previous restorative in comparison to a healthy first premolar indicated for extraction
 * Upper 1st premolars more esthetic than 2nd premolars
 * Allows good marginal relationship between the contact point of mandibular first molar
 * Minimum anchorage considerations of the posterior teeth

Molars
The idea of extractions of molars, although uncommon, has been around since early 1900s when Chapin proposed the extractions of molars instead of premolars. Several other authors have proposed extraction of molars in patients with Class 2 malocclusion, normal facial profile, excessive flaring of frontal incisors. Extractions of molars are considered to be more challenging than extractions of other teeth due to following reasons : Third molars (wisdom tooth) are most often extracted for the primary reason of impaction. Second molars are often extracted for reasons such as for distalization of first molars in a Class II malocclusion or creating space for eruption of third molars. However, Lin et al. performed a study where they extracted second molars in the lower arch of 13 Class III malocclusion patients and found it to be an effective way of correction Class III malocclusions.
 * Due to its larger size, it takes extra time to close a molar space than a premolar
 * Often these extracted molars are periodontally involved, thus increased focus on oral hygiene and shortened treatment time for orthodontic treatment can become a challenge
 * A non-compliant patient and increased treatment time in braces may make treatment worse

Extraction of first molars maybe done on teeth that have excessive restorations, endodontically treated with poor prognosis or posterior crowding.

En-Masse vs. Two-step canine retraction
En masse retraction stands for when after extraction of 1st premolars, the front six teeth (Central incisors, lateral incisors and canines) are all brought back together to close the space. Two-step canine retraction stands for when during the first step, the canine is brought back separately followed by a second step where the lateral and central incisors are brought back together. In a study done by Heo et al., 30 female adults were enrolled with Class 1 malocclusion where they were divided into two groups of en-masse retraction vs. two step canine retraction. They found that no signficant differences exists when comparing the amount of movement upper front teeth had vs the amount of anchorage loss the posterior molar teeth have.

Huang et al. published a study in 2010 where they looked at 52 patients who went through space closure with both of these techniques. The authors evaluated differences in the root shortening between these two procedures and found no significant differences.