A wisdom tooth is the most commonly impacted teeth.Definition of impaction:Prevention of complete eruption of a tooth into its normal functional position.

What factors that may lead to such a thing???Inadequate (lack) of space or another tooth preventing this tooth from erupting into its normal functional position.Some times may go to an erupting path which is not where supposed to be. i.e:Canine is going to erupt in the area of central incisor or in the area of 2nd premolar .and this is called Ectopic eruption .

Is there a difference between the terms impacted and unerupted tooth???Unerupted tooth : they r uneruptd because its not the time to erupt,there is chronological eruption sequence.For example at the age of 6-7 years, which tooth supposed to be in the process of eruption or erupted???Ans: 1st molar , so we don’t say they r impacted because of chronological sequence.

What r

commonly impacted teeth???Ans:3rd molars ,Max canines and Mand. premolars.

Is there something common between 3rd molars, Max canines and Mand. premolars???Ans: they r late erupting teeth , by the time they r going to erupt, their space may be occupied by another teeth and blocked from eruption.

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The age at 3rd molars erupt is variable but average chronological age for their eruption is 18-24, however about 25% of 3rd molars r congenitally absent or failed to develop . so at least 25% of individuals one or more of 3rd molars fails to develop.

Why we removed 3rd molars???First of all u should know that there is no doubt that 3rd molars with recurrent problems r indicated for extraction, and no disagreement about this, but 3rd molar not associated with any pathology there is still controversy about their extraction, so 3rd

molar which is asymptomatic ( not causing to the patient any problem clinically ).Removal of this tooth is not a standard procedure, it is controversial, some people may suggest its better to remove it, other suggest not to remove it.

The indications for extractions :

Dental caries:It’s a leading cause for a dental extraction. Dental caries may be in the 3rd or 2nd molars. usually the 3rd molar covered by soft tissue. This soft tissue lead to accumulation and impaction of food , this will cause dental caries in the 3rd molar or distal aspect of 2nd molar and if u want to restore the 2nd

molar u cant do that properly without removing 3rd molar.

Pericoronitis:Pericoronitis: inflammation of the soft tissue covering a

partially erupted tooth, such as 3rd molars. Because these soft tissue will lead to food trap which is difficult to keep clean , and bacteria will come to colonize in this area and produce its toxins and lead to inflammation, may be acute ,subacute , chronic and these soft tissue called operculum.Usually its result when host defenses decrease , trauma from opposing 3rd molars.

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In case of acute infection , most of time its contraindicated to do Surgery, because surgical intervention will lead to spread of infection into other areas so in acute infection we delay surgery until we control the infection ,and most commonly we do surgical intervention in chronic state .

periodontal diseasethe food impact or trap to periodontal ligament, the collection of food in an area difficult to keep clean will lead to periodontal disease and these disease more pronounced in the maxillary area .

in the picture

we can see bone loss and deep pocket distal to the 7 .

Q: why the periodontal disease more pronounced in the maxilla ?Because the bone is different from mandible and the furcation area of maxillary 2nd molar is closer.

prosthetic reason (indication or contraindication) patients may be seeking complete denture but when we take OPG you find that they have impacted 3rd molar ,usually its better to remove it because it in due time become superficial and interfere with the fitting of the denture BUT if the tooth is deeply impacted surgical removal may lead to prosthetic problem such as scar and loss of depth in the buccal sulcus so we leave it, and some times we leave it to retain the bone Because when we extract a tooth we will have bone resorption , so we keep it unless it interfere with fitness or construction of prostheses .

facilitation of orthodontic treatment

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sometimes orthodontists recommend removal of 3rd molar, Because impacted 3rd molar particularly lower 3rd molar are responsible for late anterior crowding but this issue is controversial, some people believe it is , others don’t believe and say that 3rd molar removal is no guarantee to improve the crowding .

prevention of root resorption of 2nd molar.In the picture we can see radiolucent

lesion it may

be a cyst, tumor, infection this radiolucent pathological lesion most likely its going to be a cyst (dentigerous cyst) and we can say it is cyst by taking sample, examine it histologically and from histological examination we can said it is a cyst. Another picture it is odontome.

3rd molar located in line of fracture this may be consider as indication or contraindication.Indication: if removal of this tooth will affect the treatment of fracture adversely we remove it .i.e.: this tooth was proper guide of occlusion , : if you remove this tooth you will lose your guide so in this case we keep it, but if this tooth (indication) will prevent fracture segments to heal we remove it .

unexplained facial painoccasionally, patient come to the dentist complaining of facial pain for no obvious reasons, after exclusion of facial pain disorders, and if the patient has an unerupted tooth ,removal of the tooth sometimes results in resolution of the pain. But in most of cases removal of wisdom teeth no guarantee to relief the pain so 3rd molar can be a cause of facial pain ,but it is not the commonest cause.

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-Some patient prefer to remove their wisdom teeth when they are

young why ?usually with advancing age you will get more of chronic disease such as diabetes , heart disease , hypertension and these disease , may make removal of this teeth difficult .

8- Social or economic factors which can be an indication for extraction of third molar .you may remove them if you will go to an area of little medical services .9- Previous attempts to extraction .

-If we decide that this wisdom tooth need removal , to be able to remove it safely with the least amount of complication and be convenience to the patient we should be able to plan our procedure .First----- we asses the tooth ,then we perform the surgery .-Usually assessment starts with , medical history , chief complaint , -------Local factors that we can see during examination as mouth opening , if it limited then it is difficult to do extraction .If it is good , it will be easy extraction , also small mandible .One of the most important assessment is radiographic by PA radiograph or OPG ( panorama) .X-Ray should show the crown and root and any anatomical structure .ID canal , Maxillary Sinus . (picture)You should carefully interpret the X-Ray .Types of X-Ray to see third molar .

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1- PA mandible 2- OPG . Extraoral 3- Periapical , Intraoral 4- Lateral skull .---------- External oblique ridge If this ridge is horizontal , then the access is excellent but if it is vertical , the access is poor because we need to remove a lot of bone to remove the impacted tooth .- Lines to determine the inclination and depth of

impaction (Winter lines)1- white line .2- Amber line .3- Red line .White line drawn along the occlusal surfaces of first, second and third molar .

This white line will give you an indication about axial inclination of tooth and how deep the wisdom tooth . (picture)

So we can classify the teeth as vertically impacted or mesiolingual impacted or horizontal , or distolingual impacted according to the long axis of wisdom tooth .

Vertical impaction :- the long axis of wisdom tooth is vertical and runs in the same direction of that M2-It is second most common impaction (38%)and second

on difficulty of removal .

- Mesioangular impaction :- the long axis is mesially tipped and the most common type of impaction (43%), but the least difficult to remove .

-Horizontal :- percentage is low(3%), and third in difficulty of removal .-The most difficult to remove is the disto angular that need a lot of bone to be removed to be able to remove it .

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Pell and Gregory classification :- A,B,C relationship of occlusal surface of the wisdom tooth to the other molar teeth .Class A:- if occlusal surface of third molar at the same level of second molar .(picture)Class B:- if occlusal surface of third molar between occlusal surface and cervical line of second molar .Class C :- if it is below the cervical margin .(picture)All of these tell how deep is the third molar .(PICTURE)

Class A Class C

Plz see the pictures in the book.Done by: Rania Al-Bsoul.Amal Abu Omar.Duaa Odat.Aysar TaSHtoush.

Good luck in the midterm exams.

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