Clinical examination

• All third molar areas should be examined by the dentist during a routine dental examination.
• When a patient seeks care for third molar problems, all four third molars should be examined even if the patient only complains of pain in a single molar.
• Extra-oral examination includes the detection of facial swelling, evaluating the patient's capacity to open the mouth, and palpation of the submandibular nodes.
• Intra-oral examination includes detection of sublingual swelling or local swelling at the gingiva around the third molar and pus discharge.
• The state of eruption of the third molar is examined (unerupted, partially erupted or fully erupted). Caries of the third molar is examined. Attention is paid to whether the distal gingiva of the third molar is loose alveolar mucosa or attached gingiva.
• The depth of the periodontal pocket between the second and third molar is examined with a probe. The connection between a clinically invisible third molar and the oral cavity is examined (figure «The status of the gingiva and the pocket depth between the second and third molars are examined with a probe»5).
• Caries in neighbouring tooth is examined.
• The patient is asked to bite the posterior teeth together to determine whether the third molar is below the occlusal plane, in occlusion or elongated. The dentist must also determine whether the third molar is traumatising the buccal mucosa or the gingiva of an opposing tooth.

Prediction of eruption

• Eruption of the third molar does not occur after the age of 26 years «Ventä I, Ylipaavalniemi P, Turtola L. Clinical out...»2.
• The prediction of eruption is relevant only for a short time, between 17 and 25 years of age.
• The most important predictor for the eruption of a partially erupted and vertically situated mandibular third molar is the space available for eruption.
  • There must be a space between the second molar and the mandibular ascending ramus that is at least equal to the width of the crown of the third molar for eruption to proceed «Begtrup A, Grønastøð HÁ, Christensen IJ ym. Predic...»21, «Ganss C, Hochban W, Kielbassa AM ym. Prognosis of ...»22, «Ventä I, Murtomaa H, Ylipaavalniemi P. A device to...»17.
• Eruption of a mandibular third molar in a 20-year-old is probable in the near future if the following criteria are met «Ventä I, Murtomaa H, Turtola L ym. Assessing the e...»23:
  • The tooth is in a vertical position
  • The tooth is located on the same occlusal level as the neighbouring tooth
  • The tooth is impacted only in soft tissue
  • The tooth is completely developed with a root end
  • There is sufficient space between the second molar and the ramus.

Differential diagnostics

• Diagnosis of infection of the third molar and differentiation from other possible diagnoses is generally not difficult because the infection is typically observed in young adults:
  • Pericoronitis of the third molar is common among 20- to 25-year-old patients «Perikoroniitille altistavia tekijöitä ovat 20–25 vuoden ikä ja alaviisaudenhammas, joka on pystysuora tai taaksepäin kallistunut, osittain puhjennut ja sijaitsee lähellä purentatasoa.»A.
  • Chronic pericoronitis is observed in adults at any age.
• An unerupted third molar may cause nonspecific facial pain. The diagnosis of a third molar problem may be confused with facial pain if the third molar area is clinically normal.
• Pain from a third molar may be described as pain in the ear.
• If the third molar is located close to the mandibular canal, there may be symptoms in that half of the jaw.
• Other diseases and findings resembling symptoms from a third molar include the following:
  • Parotitis
  • Abscess of the throat
  • Caries in the neighbouring tooth
  • A cyst or a tumour
  • Temporomandibular disorders.

Microbiology of the third molar

• The predominantly anaerobic bacteria found in pericoronitis resemble those found in gingivitis and periodontitis «Leung WK, Theilade E, Comfort MB ym. Microbiology ...»24.
• The most common bacteria are streptococci, Actinomyces species and Propionibacterium, as well as beta lactamase-producing species of Prevotella, Bacteroides, Fusobacterium, Capnocytophaga, and staphylococci «Sixou JL, Magaud C, Jolivet-Gougeon A ym. Evaluati...»25, «Gutiérrez-Pérez JL. Third molar infections. Med Or...»26.
• Parodontopathogens, such as Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Tannerella forsythia, have been isolated from pericoronitis sites «Leung WK, Theilade E, Comfort MB ym. Microbiology ...»24, «Rajasuo A, Jousimies-Somer H, Savolainen S ym. Bac...»27, «Rajasuo A, Sihvonen OJ, Peltola M ym. Periodontal ...»28, «Peltroche-Llacsahuanga H, Reichhart E, Schmitt W y...»29. Through the use of PCR, Treponema denticola «Rajasuo A, Laine V, Kari K, Pyhäjärvi A, Meurman J...»30 has also been reported to exist in pericoronitis sites.
• Elevated numbers of T. forsythia, P. gingivalis, T. denticola, Prevotella intermedia, and Campylobacter rectus species in the gingival sulcus of the second molar may lead to deepening of the gingival pocket (≥ 4–5 mm) around the second and third molars within two years in relatively young patients «White RP Jr, Madianos PN, Offenbacher S ym. Microb...»31, «White RP Jr, Offenbacher S, Blakey GH ym. Chronic ...»32.

Imaging

Orthodontic considerations

• Changes in the occlusion and the position of teeth during one's lifetime, which manifest as the crowding of teeth, especially of mandibular incisors «Björk A, Jensen E, Palling M. Mandibular growth an...»15:
  • Crowding takes place in both orthodontically treated patients and other patients.
  • There are many reasons for crowding, including slow growth of the jaw in adulthood accompanied by twisting of the jaw and crowding of the mandibular incisors.
  • The straightening of the upper incisors accompanied by diminished space for the lower incisors may cause crowding of the lower incisors.
• The relationship between the third molar and the crowding of the lower front teeth:
  • Crowding of the lower incisors begins at approximately the same time as the third molars erupt.
  • In the general population, possible crowding of the lower incisors after orthodontic treatment is not associated with third molars and their eruption «Ades AG, Joondeph DR, Little RM ym. A long-term st...»35.
  • The removal of third molars is not indicated solely to prevent crowding of the lower incisors among orthodontically treated patients or other patients «Viisaudenhampailla ei ole yhteyttä oikomishoidon jälkeen mahdollisesti tapahtuvaan alaetuhampaiden ahtautumiseen.»A, «Rupp RP. Orthodontic relapse and the mandibular th...»36.
• The effects of the removal of other teeth on the eruption of the third molar:
  • The removal of premolars during orthodontic treatment does not have any considerable effect on the inclination of third molars to erupt «Välihampaiden poistot kiinteillä kojeilla tehdyn oikomishoidon yhteydessä eivät merkittävästi vaikuta ylä- tai alaleuan viisaudenhampaiden puhkeamissuuntaan, mutta saattavat joissain tapauksissa vähentää viisaudenhampaiden impaktoitumista.»A, «Haavikko K, Altonen M, Mattila K. Predicting angul...»37.
  • The removal of premolars significantly decreases third molar impaction only if the first molars are allowed to move forward as part of the orthodontic treatment «Välihampaiden poistot kiinteillä kojeilla tehdyn oikomishoidon yhteydessä eivät merkittävästi vaikuta ylä- tai alaleuan viisaudenhampaiden puhkeamissuuntaan, mutta saattavat joissain tapauksissa vähentää viisaudenhampaiden impaktoitumista.»A.
  • The removal of teeth in the course of orthodontic treatment does not affect the eruption of third molars «Välihampaiden poistot kiinteillä kojeilla tehdyn oikomishoidon yhteydessä eivät merkittävästi vaikuta ylä- tai alaleuan viisaudenhampaiden puhkeamissuuntaan, mutta saattavat joissain tapauksissa vähentää viisaudenhampaiden impaktoitumista.»A.
  • If the third molar prevents the eruption of the second molar, the treatment decision should be made in conjunction with the orthodontist. Removal of the third molar instead of the second molar is often recommended «Magnusson C, Kjellberg H. Impaction and retention ...»38.
• The eruption of the third molar into the place of the second molar:
  • If the second molar is removed because of cariologic or periodontologic indications, an improved position of the third molar in place of this removed tooth is more likely the earlier the third molar is removed.
  • The prognosis of eruption of the third molar into the place of the second molar is better for the opening type of growth of the jaws than for the closing type, and it is also better for the upper jaw than for the lower jaw «De-la-Rosa-Gay C, Valmaseda-Castellón E, Gay-Escod...»39.
• Removal of the third molar with respect to orthognathic surgery:
  • Mandibular third molars are typically removed on a case-by-case basis at least 6 months before ramus osteotomy and orthognathic surgery «Reyneke JP, Tsakiris P, Becker P. Age as a factor ...»40, «Schwartz HC. Simultaneous removal of third molars ...»41, «Colella G, Giudice A. The timing of third molar re...»42.
  • If the removal is performed intraoperatively during the ramus osteotomy, it does not necessarily increase the risk of improper splitting of the mandible and may even alleviate the operation of the mandibular canal «Mehra P, Castro V, Freitas RZ ym. Complications of...»43, «Tucker MR, Wolford LM. Sagittal ramus osteotomy wi...»44, «Doucet JC, Morrison AD, Davis BR ym. The presence ...»45. This method may also decrease the incidence of nerve damage and accelerate recovery from the impairment of sensation in the lower lip «Doucet JC, Morrison AD, Davis BR ym. Concomitant r...»46.
  • Upper third molars are removed if needed during the LeFort I osteotomy.
• The surgical orthodontics of third molars (autotransplantation):
  • It is possible to transplant the third molar into the place of premolars or molars. The prognosis is best if the development of the root is at 1/2-3/4 phase.
  • It is possible to orthodontically move an autotransplanted third molar to a more appropriate place and position.
  • Orthodontic treatment does not affect the root development of a transplanted tooth.
  • Transplantation prognosis is good, but rotation of the transplanted tooth with fixed appliances often causes devitalisation of the tooth «Bauss O, Schwestka-Polly R, Kiliaridis S. Influenc...»47, «Bauss O, Zonios I, Rahman A. Root development of i...»48, «Denys D, Shahbazian M, Jacobs R ym. Importance of ...»49.

Periodontal considerations

• If there is no attached gingiva behind the second molar, it is very important to save the bone and the soft tissue at the extraction site.
• Although the patient may feel symptomless, periodontal infection (pocket depths ≥ 5 mm) may arise from the third molar area and spread throughout the dentition «Blakey GH, Marciani RD, Haug RH ym. Periodontal pa...»50, «Blakey GH, Jacks MT, Offenbacher S ym. Progression...»51, «Offenbacher S, Beck JD, Moss KL ym. What are the l...»52.
• Partially erupted third molars increase the risk of periodontal problems of the second molar, especially under the following conditions:
  • The patient is 25 years of age or older
  • The patient smokes
  • The patient's education level is low
  • The patient visits the dentist only when necessary «Offenbacher S, Beck JD, Moss KL ym. What are the l...»52, «Nunn ME, Fish MD, Garcia RI ym. Retained asymptoma...»53.
• Deep gingival pockets are observed more often in the mandibular third molar area than in the maxilla «Blakey GH, Marciani RD, Haug RH ym. Periodontal pa...»50, «Offenbacher S, Beck JD, Moss KL ym. What are the l...»52.
• The removal of an impacted mandibular third molar before the patient reaches the age of 25 significantly decreases the formation of postoperative residual pockets «Impaktoituneen alaviisaudenhampaan poisto potilaan ollessa 25-vuotias tai nuorempi vähentää jäännöstaskun muodostumista toisen alaposkihampaan takapinnalle.»A.
• Predisposing factors for postoperative bone defects behind the second molar are as follows:
  • Patient age greater than 25 years
  • An existing bone defect behind the second molar
  • A large contact area between the second and third molars: the third molar is inclined forward or in a horizontal position
  • Resorption of the root surface of the second molar
  • A deep gingival pocket postoperatively behind the first molar
  • An enlarged follicle of the third molar «Kugelberg CF, Ahlström U, Ericson S ym. The influe...»54.
• Diminishment or complete healing of bone defects can be expected up to four years after extraction if the patient is younger than 25 years of age «Kugelberg CF. Periodontal healing two and four yea...»55. Healing of periodontal tissue can be detected clinically much more easily than from radiographs «Karapataki S, Hugoson A, Falk H ym. Healing follow...»56.

Prevention of pericoronitis

• The development of pericoronitis can be prevented by improving oral hygiene, especially by brushing the teeth twice a day and cleaning the third molar area.
• Acute pericoronitis among 20- to 25-year-old patients can be prevented if mandibular third molars in the following states are removed early:
  • A partially erupted third molar with an enlarged follicle «Perikoroniitin ehkäisemiseksi kannattaa alle 25-vuotiailta poistaa ennakoivasti sellaiset pystysuorat tai taaksepäin kallistuneet alaviisaudenhampaat, jotka ovat osittain puhjenneita eivätkä mahdu kokonaan puhkeamaan ja joilla on laajentunut kruunufollikkeli.»A
  • A vertical or distoangular third molar close to the occlusal surface «Perikoroniitin ehkäisemiseksi kannattaa alle 25-vuotiailta poistaa ennakoivasti sellaiset pystysuorat tai taaksepäin kallistuneet alaviisaudenhampaat, jotka ovat osittain puhjenneita eivätkä mahdu kokonaan puhkeamaan ja joilla on laajentunut kruunufollikkeli.»A.

Prevention of periodontal infection

• Postoperative bone defects of partially erupted mandibular third molars that are in a horizontal position or that are deeply inclined forward can be prevented by removal before the age of 25 years «Impaktoituneen alaviisaudenhampaan poisto potilaan ollessa 25-vuotias tai nuorempi vähentää jäännöstaskun muodostumista toisen alaposkihampaan takapinnalle.»A.
• Removal of a partially erupted mandibular third molar significantly decreases visible plaque in the entire dentition as well as the amount of bacteria causing periodontal infection in the periodontal pockets of the neighbouring teeth «Giglio JA, Gunsolley JC, Laskin DM ym. Effect of r...»57, «Rajasuo A, Meurman JH, Murtomaa H. Periodontopathi...»58, «Blakey GH, White RP Jr, Offenbacher S ym. Clinical...»59.
• The removal of a mandibular third molar improves the periodontal status of the dentition, particularly the attachment level of the neighbouring second molar «Giglio JA, Gunsolley JC, Laskin DM ym. Effect of r...»57, «Montero J, Mazzaglia G. Effect of removing an impa...»60, «Nunn ME, Fish MD, Garcia RI ym. Retained asymptoma...»53.
• A visible third molar diagnosed during the first two thirds of pregnancy, especially with a periodontal pocket of more than 4 mm, is a significant predictor of periodontal infection during pregnancy, particularly in the molar area «Moss KL, Ruvo AT, Offenbacher S ym. Third molars a...»61. A high level of oral hygiene during pregnancy is necessary and it is further emphasized if the third molars are not removed before pregnancy.

Prevention of nerve injuries

• If the mandibular third molar is developing in a position in which the root of the tooth and the mandibular canal are visibly superimposed on the radiograph, and if there is not enough space for the tooth to erupt or if the direction of eruption is unfavourable, removal of the tooth is recommended before the growth of the root end is complete to prevent injury to the inferior alveolar nerve «Jos alaviisaudenhammas on kehittymässä siten, että hampaan juuri ja hermokanava kuvautuvat päällekkäin röntgenkuvasta arvioituna, hampaan poisto ennakoivasti ennen juuren kehityksen päättymistä vähentää N. alveolaris inferiorin vauriota.»A.
• An assessment of the lack of space for eruption must consider the following:
  • The space between the second molar and the ascending ramus of mandible
  • An estimation of the final size of the tooth and the space above the mandibular canal
  • The amount of bone below the third molar.

Prevention of caries

• Third molars are prone to developing caries soon after eruption. Caries in neighbouring teeth increases the likelihood of caries in the third molars «Fisher EL, Moss KL, Offenbacher S ym. Third molar ...»9, «Divaris K, Fisher EL, Shugars DA ym. Risk factors ...»62, «Shugars DA, Elter JR, Jacks MT ym. Incidence of oc...»63.
• Because partially erupted mandibular third molars increase the amount of salivary bacteria that cause caries as well as visible plaque in neighbouring teeth, the removal of partially erupted third molars from the mandible significantly decreases the following «Meurman JH, Rytömaa I, Murtomaa H ym. Erupting thi...»64, «Ylipaavalniemi P, Turtola L, Rytömaa I ym. Effect ...»65:
  • Visible plaque throughout the dentition «Giglio JA, Gunsolley JC, Laskin DM ym. Effect of r...»57
  • The amount of bacteria causing periodontal infection in neighbouring teeth
  • The amount of salivary bacteria causing caries «Rajasuo A, Meurman JH, Murtomaa H. Periodontopathi...»58, «Rajasuo A, Meurman JH, Metteri J ym. Effect of ext...»66, «Meurman JH, Rytömaa I, Murtomaa H ym. Erupting thi...»64.
• Caries on the distal surface of mandibular second molars is more common if there is a partially erupted or completely erupted third molar in a forward-inclined position behind the molar «Kokonaan tai osittain puhjennut ja eteenpäin kallistunut alaviisaudenhammas ilmeisesti edesauttaa viereisen toisen alaposkihampaan takapinnan reikiintymistä.»B, «Falci SG, de Castro CR, Santos RC ym. Association ...»67, «McArdle LW, Renton TF. Distal cervical caries in t...»68, «Nunn ME, Fish MD, Garcia RI ym. Retained asymptoma...»53.

Cost-effectiveness studies of preventive removals

• No cost-effectiveness studies on preventive third molar removals have been performed in Finland.
• There are no randomised controlled studies recommending or contradicting the systematic removal of symptomless unerupted third molars «Mettes TD, Ghaeminia H, Nienhuijs ME ym. Surgical ...»69.
• In a Swedish study, indirect costs related to the surgery (for example sick leave and travel costs) were found to be greater than the costs of the operation «Liedholm R, Knutsson K, Norlund A. Economic aspect...»70.
• All of the following cost-effectiveness studies were published in the 1990s:
  • According to a study from Great Britain, it is more cost-effective to retain symptomless mandibular third molars than to systematically remove such teeth preventively «Edwards MJ, Brickley MR, Goodey RD ym. The cost, e...»71.
• However, preventive removal of a mandibular third molar is cost-effective if the following criteria are met «Edwards MJ, Brickley MR, Goodey RD ym. The cost, e...»71:
  • Probability of pericoronitis is greater than 40%
  • Probability of periodontal disease is greater than 17%
  • Probablity of untreatable caries of the neighbouring tooth is greater than 22%.
• According to a decision analysis performed in the USA, it is most advantageous to remove only impacted third molars with pathology «Tulloch JF, Antczak-Bouckoms AA, Ung N. Evaluation...»72.
• According to a study from Norway, it is most cost-effective if an oral surgeon preventively removes symptomless and partially erupted third molars from patients around the age of 20 to 25 years. The most expensive alternative is the removal of a third molar by a dentist when the patient is more than 44 years old «Berge TI. The impacted third molar. Assessments an...»73.
• According to a Canadian decision analysis, the most beneficial strategy is removal of some symptomless and unerupted mandibular third molars before the age of 14 years and removal of most third molars before the age of 22 years, provided that the patient has good oral hygiene «Mercier P, Precious D. Risks and benefits of remov...»74.
• Since the publication of the NICE and SIGN guidelines, the mean age of patients at the time of third molar removal has increased from 29 years to 36 years, which has already affected the occurrence of complications «NICE, National Institute for Health and Care Excel...»75, «SIGN, Scottish Intercollediate Guidelines Network...»76, «Petrosyan V, Ameerally P. Changes in demographics ...»77.

Acute care

• Acute care for pericoronitis includes the following:
  • The removal of an upper third molar that causes trauma to the soft tissue.
  • Occasionally proper grinding of an opposing tooth.
  • An overall improvement of oral hygiene, particularly brushing the teeth twice a day and cleaning the third molar area.
  • Local rinses with chlorhexidine.
  • Systemic antimicrobials for acute pericoronitis (see Current Care Guideline on Antimicrobials in acute dentistry «Hammasperäiset äkilliset infektiot ja mikrobilääkkeet»1).
    • When a systemic antimicrobial is indicated, phenoxymethylpenicillin together with metronidazole is recommended in healthy patients.
    • Cephalexin together with metronidazole or clindamycin is recommended for patients allergic to penicillin.
    • Bacteria producing betalactamase (prevalence in Finland 2.0-4.6% «Gunell M, Hakanen A, Aittoniemi J ym. Mikrobilääke...»78) may inhibit the effectiveness of antimicrobials. Therefore, one choice is to use a combination of amoxicillin and clavulanic acid «Sixou JL, Magaud C, Jolivet-Gougeon A ym. Evaluati...»25, «Gutiérrez-Pérez JL. Third molar infections. Med Or...»26, «Sixou JL, Magaud C, Jolivet-Gougeon A ym. Microbio...»79.
  • Incision and drainage of an abscess if needed.
  • Removal of the infected tooth if possible.
  • Chronic pericoronitis seldom requires treatment before the removal of the tooth «Kay LW. Investigations into the nature of pericoro...»11.
• Acute care for caries of the third molar includes pulp capping and temporary filling.

Technique of tooth removal

• Third molars are typically removed under local anaesthesia.
• The demands of the operation and adequate instrumentation should be evaluated before the operation.
• The operation should be performed as atraumatically as possible, saving the surrounding tissues.
• If the third molar must be removed surgically, the incision should be made such that good visibility of the field is achieved.
  • The opening incision for a mandibular third molar is made on the buccal gingiva.
• The incision may be made as a triangular flap (figure «A triangular flap accelerates the initial healing phase»7), an envelope flap (figure «Envelope flap»8), or a trapezoidal flap (figures «Trapezoid flap»9 and «Extended trapezoid flap»10), depending on the location and status of the tooth.
• The shape of the opening incision may have an effect on the primary healing period, but the difference does not persist for more than a year after the operation «Impaktoituneen alaviisaudenhampaan poistossa leikkausviillon muoto saattaa vaikuttaa edullisesti ensimmäisten viikkojen paranemiseen ja ientaskujen madaltumiseen toisen alaposkihampaan takapinnalla.»C.
  • A triangular flap (figure «A triangular flap accelerates the initial healing phase»7) enhances the wound healing in mandibular third molar surgery during the first two weeks compared with an envelope flap (figure «Envelope flap»8) «Jakse N, Bankaoglu V, Wimmer G ym. Primary wound h...»80.
• Bone is removed with a surgical burr or a micromotor using saline.
• According to pilot studies, advantages of piezoelectric removal of bone include less swelling and pain, but a longer operation time is required compared with a conventional burr. A conventional burr is, however, required for splitting the tooth «Sortino F, Pedullà E, Masoli V. The piezoelectric ...»81, «Barone A, Marconcini S, Giacomelli L ym. A randomi...»82, «Goyal M, Marya K, Jhamb A ym. Comparative evaluati...»83.
• While removing a partially erupted third molar, the flap should be replaced for suturing such that the attached gingiva is preserved behind the second molar.
• When suturing a mandibular third molar wound, the anatomy of the lingual nerve must be kept in mind.

Medication for third molar surgery

• It is usually necessary to use painkillers for third molar surgery.
  • Regular painkillers, such as ibuprofen and diclofenac, in normal dosages adequately relieve postoperative pain «Normaaliannoksilla käytetyt anti-inflammatoriset analgeetit (tulehdusta ehkäisevät kipulääkkeet) ja koksibit takaavat parhaimman kivun lievityksen ja vähäisimmät haittavaikutukset viisaudenhampaiden leikkauksissa.»A.
  • In addition, these painkillers are cheaper than COX-2 inhibitors, which are also effective for pain relief «Normaaliannoksilla käytetyt anti-inflammatoriset analgeetit (tulehdusta ehkäisevät kipulääkkeet) ja koksibit takaavat parhaimman kivun lievityksen ja vähäisimmät haittavaikutukset viisaudenhampaiden leikkauksissa.»A. Possible adverse effects of diclofenac and COX-2 inhibitors, especially among patients with risk factors for heart and vascular diseases, should be considered.
  • Paracetamol in sufficiently large amounts is also effective and safe for postoperative pain in third molar surgery «Weil K, Hooper L, Afzal Z ym. Paracetamol for pain...»99.
• The use of antibiotics in third molar surgery has proven useful to prevent alveolitis and late infection «Viisaudenhammasleikkausta ennen aloitettu ja sen jälkeen 2–7 vuorokautta käytetty bakteerilääkehoito vähentää leikkausalueen jälki-infektion ja hammaskuopan tulehduksen riskiä sekä leikkauksen jälkeistä kipua.»A, «Lodi G, Figini L, Sardella A ym. Antibiotics to pr...»142, «Ren YF, Malmstrom HS. Effectiveness of antibiotic ...»143.
  • Medication should always begin before operation (30–90 minutes) to be effective and should be continued for 2–7 days postoperatively.
  • Possible adverse effects of the medicines should be noted (for example, allergy).
  • No antibiotic is given higher priority, but the selected antibiotic should be as effective as possible against most oral microbes.
  • There are several predisposing factors for postoperative alveolitis and late infection, such as increased patient age, female gender, smoking, poor oral hygiene, decreased general health, and the amount of tissue damage incurred during the operation. In addition to these issues, antibiotics should always be considered in cases of severe tooth infection and in demanding operations «Viisaudenhammasleikkausta ennen aloitettu ja sen jälkeen 2–7 vuorokautta käytetty bakteerilääkehoito vähentää leikkausalueen jälki-infektion ja hammaskuopan tulehduksen riskiä sekä leikkauksen jälkeistä kipua.»A.
  • Local risk factors for infective complications are as follows:
    • Third molar impacted totally or partially in bone is a significant factor
    • Impaction in soft tissue is a moderate factor
    • Infection diagnosed preoperatively
    • Any other pathology related to the third molar «Chuang SK, Perrott DH, Susarla SM ym. Risk factors...»100.
• Rinsing with chlorhexidine before the operation and for several days postoperatively decreases the prevalence of alveolitis after third molar surgery «Klooriheksidiinihuuhtelu leikkauspäivänä ennen leikkausta ja usean päivän ajan leikkauksen jälkeen alentaa viisaudenhammasleikkauksen jälkeisen hammaskuopan tulehduksen (alveoliitti) esiintyvyyttä.»A.
• The use of systemic corticosteroids in third molar surgery decreases swelling, trismus and pain during the first postoperative day «Esen E, Tasar F, Akhan O. Determination of the ant...»101, «Schmelzeisen R, Frölich JC. Prevention of postoper...»102.
  • The use of corticosteroids should be considered in most difficult operations and particularly when removing several third molar teeth at the same time.
  • Routine use of corticosteroids may not be necessary in regular operations.

Alveolitis (ICD10 code K10.3)

• Alveolitis follows conventional extraction with forceps in 0.5–5% of cases, but it may occur following operative extraction of mandibular third molars in 37.5% of cases.
• Predisposing factors for alveolitis include female gender, smoking, poor oral hygiene, and traumatic operation «Daly B, Sharif MO, Newton T ym. Local intervention...»110.
• According to a Cochrane review, there is insufficient evidence to recommend the best treatment method «Daly B, Sharif MO, Newton T ym. Local intervention...»110.
• It is common practice to irrigate the socket with saline and to insert an appropriate medicated dressing. The dressing is changed every few days depending on the pain. The dressing is soaked in medicines such as iodoform as an antiseptic, benzocaine as a topical anaesthetic, and eugenol for pain «Hupp JR. Prevention and management of surgical com...»111. In Finland, it is common practice to use a dressing soaked in iodoform. Chlumsky solution is no more recommended because of adverse effects (NIH) «National Institutes of Health. U.S. National Libra...»141.
• Local anaesthesia and curettage of the socket are usually not necessary.
• If it is known that the mandibular nerve is exposed on the bottom of the socket, no medicine should be used because of the risk of nerve injury. In such cases, a grease dressing is sufficient as a tampon «Loescher AR, Robinson PP. The effect of surgical m...»112.
• Alveolitis can be prevented with the use of systemic antibiotics «Viisaudenhammasleikkausta ennen aloitettu ja sen jälkeen 2–7 vuorokautta käytetty bakteerilääkehoito vähentää leikkausalueen jälki-infektion ja hammaskuopan tulehduksen riskiä sekä leikkauksen jälkeistä kipua.»A and rinsing with chlorhexidine before the operation and for several days postoperatively «Klooriheksidiinihuuhtelu leikkauspäivänä ennen leikkausta ja usean päivän ajan leikkauksen jälkeen alentaa viisaudenhammasleikkauksen jälkeisen hammaskuopan tulehduksen (alveoliitti) esiintyvyyttä.»A, «Daly B, Sharif MO, Newton T ym. Local intervention...»110.

Nerve injury from mandibular nerve block (ICD10 code T80.8)

• The estimated incidence of permanent injury of the lingual nerve or the inferior alveolar nerve or both is 1:26,000–800,000 «Pogrel MA, Thamby S. Permanent nerve involvement r...»113, «Haas DA, Lennon D. A 21 year retrospective study o...»114.
• According to a German study, an alveolar nerve block per 12,104 patients caused a permanent lingual nerve injury «Krafft TC, Hickel R. Clinical investigation into t...»115.
• During mandibular nerve block, a nerve trunk with only one fasciculus may be damaged more easily than a trunk with several fascicles. The lingual nerve in the mandibular nerve block area was unifascicular in 33% of cases, but the inferior alveolar nerve always had more fascicles. This fact may explain why the lingual nerve is injured in 70% of cases, whereas the inferior alveolar nerve is injured in only 30% of cases «Pogrel MA, Schmidt BL, Sambajon V ym. Lingual nerv...»116.
• To prevent injury, an adequate nerve block technique, the integrity of the needle tip, and goal-oriented entry of the needle are emphasised «Norton N. Intraoral injections. Kirjassa: Norton N...»117.

Injury of the inferior alveolar nerve related to mandibular third molar removal (ICD10 code T81.2)

• The incidence of permanent nerve injury is 1% «Schultze-Mosgau S, Reich RH. Assessment of inferio...»118, and the incidence of temporary injury is 1–8% «Rood JP. Permanent damage to inferior alveolar and...»119.
• Among Danish patients (N=449) with injury of the trigeminal nerve, the method of injury was third molar surgery in 71% of cases and mandibular nerve block in 17% of cases «Hillerup S. Iatrogenic injury to oral branches of ...»120.
• The most common sign of nerve injury is hypoanaesthesia (69%), and the second most common sign is total anaesthesia (27%) «Hillerup S. Iatrogenic injury to the inferior alve...»121.
• When the root and mandibular canal are completely superimposed on the panoramic tomograph, the most important findings that predict nerve injury are narrowing of the canal and contact between the canal and the root «Eyrich G, Seifert B, Matthews F ym. 3-Dimensional ...»122.
• If the mandibular nerve is exposed and intact in the socket during the operation, and if the radiographs demonstrate close contact, impairment of nerve function is observed in 20–22% of cases after a week, in 6% of cases after a year, and in 2% of cases two years after the operation. If the mandibular canal was not exposed in the socket, impairment of nerve function after a week is observed in only 3% of cases «Tantanapornkul W, Okouchi K, Fujiwara Y ym. A comp...»34, «Tay AB, Go WS. Effect of exposed inferior alveolar...»123.
• To prevent nerve injury,
  • The difficulty of the operation and the course of the mandibular canal should be assessed preoperatively, and accordingly an appropriate place for the treatment chosen.
  • The tooth should be split if necessary.
  • Excessive force should be avoided.
  • Coronectomy should be considered.

Injury of the lingual nerve related to mandibular third molar removal (ICD10 code T81.2)

• The most common malpractice claim submitted to the Finnish Patient Insurance Centre related to tooth extractions is lingual nerve injury «Ventä I, Lindqvist C. Viisaudenhampaiden poistoihi...»124.
• The incidence of permanent impairment of the lingual nerve is 0.1–0.6%, and the incidence of temporary impairment is 0.6–9.6% «Pichler JW, Beirne OR. Lingual flap retraction and...»125.
• Complete healing of nerve injury is unlikely if impairment persists for more than 6 months «Zunica JR. Normal responses to nerve injury: histo...»126.
• The lingual nerve passes the mandibular third molar in the soft tissue on the lingual side and may even be located above the bone crest and above a partially erupted third molar crown.
• The location of the nerve in the lingual soft tissue varies horizontally between 0 and 3 mm from the bone surface and vertically from 2 mm above the bone crest to 7 mm below the bone crest «Kiesselbach JE, Chamberlain JG. Clinical and anato...»127, (figure «Course of the lingual nerve in the lingual soft tissue of the mandibular third molar»11), «Ventä I, Lindqvist C. Viisaudenhampaiden poistoihi...»124.
  • In 17.6% of cases, the nerve is located at or above the bone crest.
  • In 62% of cases, the nerve is located at the lingual bone surface.
• To prevent injury to the lingual nerve, it is important to note possible mechanisms of damage. In addition to a mandibular nerve block, the nerve may be damaged by the following:
  • An opening incision placed too far on the lingual side behind the tooth
  • Operating on the lingual side
  • Slippage of the elevator to the lingual side
  • Drilling of the bone behind the tooth or on the lingual side
  • Perforation of the lingual bone with the burr
  • Extraction forceps clamping the lingual gingiva
  • Exhaustive removal of the follicle
  • Needle perforation of the lingual gingiva during suturing.

Mandibular fracture related to mandibular third molar removal (ICD10 code T81.8)

• The incidence of fractures is 1 per 22,000 operations «Perry PA, Goldberg MH. Late mandibular fracture af...»128.
• The mandibular bone may also break during the operation due to the application of excessive force.
• Fractures occur on average 12–14 days after the operation (range 1–60 days).
• Predisposing factors for fractures include male gender, older age (mean age of fracture patients is 45 years), complete dentition, and a deeply located mandibular third molar «Krimmel M, Reinert S. Mandibular fracture after th...»129, «Wagner KW, Otten JE, Schoen R ym. Pathological man...»130.
• To prevent fractures among patients at risk, it is important to note the scarcity of bone below the root end, to inform the patient about this risk, and to recommend a soft diet and the avoidance of extreme physical stress and contact sports for 4–6 weeks postoperatively.

Sinus perforation related to upper third molar removal (ICD10 code T81.8)

• The incidence of acute perforation of the sinus is 5% in an ordinary extraction, 10% in an operative removal of a partially erupted tooth, and 24% in an operative removal of an unerupted third molar «Rothamel D, Wahl G, d'Hoedt B ym. Incidence and pr...»131.
  • Perforation is most likely to occur when the root fractures during extraction, when the tooth is unerupted, and among elderly persons.
• Depending upon the size of the perforation, the treatment may be the formation of a stable blood clot, sutures or the raising of the buccal flap, in addition to adequate medication, postoperative instructions for self-care, and a follow-up assessment of healing «Hupp JR. Prevention and management of surgical com...»111.
• The proximity of the sinus should be determined preoperatively from the radiograph, and the operation should be planned considering the proximity.