User:Globalorthodontist/Extraction in orthodontics

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

Indications for different teeth

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

Premolars

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:

• 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

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.

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

Patterns

Surgical Extraction Pattern

Problem	Treatment Type	Extraction Pattern	Comments
Mandibular Hyperplasia and/or Maxillary Hypoplasia	BSSO mandibular setback with or w/o LeFort advancement	Upper 1st premolars (U4s) only	Upper first premolar extraction will lead to increased reverse overjet, which will maximize the mandibular setback
Mandibular Hypoplasia	BSSO mandibular advancement	Lower 1st premolars (L4s) only	Lower premolars extraction will lead to increased overjet, which will maximize the mandibular advancement movement

Non-Surgical Extraction Pattern

Problem	Treatment Type	Extraction Pattern	Comments	Final Molar Relationship	Canine Relationship
Mandibular Hyperplasia and/or Maxillary hypoplasia	Class 3 Camouflage	Lower 1st premolars only	Lower 1st premolars are extracted to maximize the retraction of the lower incisors to achieve a positive overjet	Class 3	Class 1
Class 2 Malocclusion with Mandibular Hypoplasia	Class 2 Camouflage	Upper 1st premolars only	Upper 1st premolars are extracted to maximize the retraction of the upper incisors to achieve a reduction in the amount of overjet	Class 2	Class 1
Bi-dentoalveolar Protrusion or "Bi-max Protrusion"		Upper and lower 1st premolars	All 1st premolars are extracted to correct the inclination of the upper and lower incisors compared to the palatal plane and mandibular plane respectively.	Class 1	Class 1

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.