Impacted Teeth

Fails to erupt into dental arch within the expected time Reasons: dense overlying bone excessive soft tissue adjacent teeth (inadequate dental arch length and space)

Most common: maxillary and mandibular third molars maxillary canines mandibular premolars Impacted teet should not be left in place until problems arise Removal becomes more difficult with advancing age

The average age of the eruption of third molar is age 20 Does not erupted after 20: covered with bone; mesioangular; cervical of second molar Late eruption: 20~25 soft tissue or slightly with bone; vertical position; superficially positioned with respect to the occlusal plane of the adjacent second molar

Early removal

Reduce postoperative morbidity Best healing The younger tolerate procedure better and recover quickly; periodontal healing is better in the younger patient, because of better regeneration of the periodontal tissue Ideal time: root formation 1/3~2/3 (age 17~20)

Indications: preventions of

Periodontal disease: upper distal furcation Dental caries: communications Pericoronitis: Streptococci; immune,food,trauma; H2O2; penicillin; fascial infection:38.4 C; 20mm trismus;dry socket and infection Root resorption: pressure; cemental repair Odontogenic cyst and tumors: dentigerous cyst, keratocyst; 3mm; ameloblastoma

Indications: preventions of

Fracture of the jaw: weaken mandible Impacted teeth under a dental prosthesis: edentulous area resorption; ext before denture making; late->tend to fracture Pain of unexplained origin: TMD,myofascial Facilitation of orthodontic treatment: molar retraction; prevent crowding Optimal periodontal healing: bone height and attachment level of 2nd molar; 25 y/o; >30,completely bony impacted=>left

Contraindication

Extremes of Age: bone calcified,less flexible, unlikely to bend;>40 y/o,bone>4mm=>left, f/u every 1~2 year with x-ray Compromised Medical Status: cardiovascular,respiratory function,host defense,coagulopathy + asymptommatic =>left Probable excessive damage to adjacent structures: nerves,teeth,bridges

Summary

At age 18~19, if the diagnosis for inadequate room can be made, the asymptomatic molar should be removed

Classification Systems

Accessbility is determined by the ease of: exposing the tooth preparing the pathway preparing a purchase point Determine the dicciculty of extraction

Classification Systems

Angulation of the long axis of 3rd molar and 2nd molar distoangular(6%)>horizontal(3%)>>vertical(38 %)>mesioangular(43%)

Anugulation

Angulation

Classification Systems

Amount of bone of the ramus covering (Pell and Gregory classification;classes 1,2,3) Mesiodistal diameter of the crown|ant border of ramus: classI=>normal position

1,2,3

Classification Systems

Depth 3rd molar and height of the 2nd molar (Pell and Gregory classification;classes A,B,C) Thickness of the overlying bone occlusal surface of impaction | occlusal surface,cervical line of 2nd molar

A,B,C