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DILEMMA OF IMPACTED MANDIBULAR THIRD MOLAREXTRACTIONS: REVIEW OF A CASE

Malik Salman Aziz1 BDS, FCPS, MFDS RCPSG, MFGDP(UK)Anser Maxood2 BDS, MSc, FRACDS

Risks involved in removal of impacted mandibular third molars are, by far, much higher than the perceived risk ofdevelopment of any condition compelling their prophylactic removal. Mandibular third molars, lying in closeproximity to the most important sensory nerves especially the mandibular nerve, pose a considerable threat ofpossible neurological injury. Removal of impacted mandibular third molars especially if asymptomatic, is notdesirable and has detrimental consequences affecting the patient's quality of life. Damage to the inferior alveolarnerve may result in paraesthesias or abnormal sensations, hypoaesthesias, dysaesthesias and even anesthesia withor without taste disturbances. This paper reviews a case involving prophylactic bilateral extractions of impactedmandibular third molars in a male patient 26 years of age, the aftereffects that occurred and some directives toimproved management and avoidance of such problems.KEY WORDS: Third Molar, Mandibular nerve, Paresthesia, Anesthesia.HOW TO CITE: Aziz MS, Maxood A, Hassan A. Dilemma of Impacted Mandibular Third Molar Extractions:Review of A Case. J Pak Dent Assoc 2013; 22: 237-240.

INTRODUCTION

andibular third molars being the most frequentlyimpacted teeth have always been the oral surgeon'sprime targets for extraction. This school of thought

is backed by myths of association of these teeth, with a highincidence of pathological lesions, anterior crowding, less traumain cases of early extraction, and with the little risk of harm inremoval. Although true to a certain extent, the above mentionedreasons do not justify the prophylactic removal of these teeth.The risks involved in prophylactic extractions of such teeth, whenweighed against conservation, are far greater than the risks ofdevelopment of any of the aforementioned conditions. Apart fromthe usual post surgical complications including pain, swelling,hemorrhage, trismus and malaise, mandibular third molar removalis associated with more serious conditions affecting the qualityof life including, paraesthesias, hypoaesthesias, dysaesthesias(temporary or permanent), fractures of adjacent teeth or mandible,development of periodontal defects and even anesthesia.The most common pathology associated with impacted mandibularthird molars is pericoronitis which if recurrent and/or unresponsive

to treatment, necessitates removal.A risk of development of cystic lesions around impacted

teeth should be born in mind and weighed against the odds ofdevelopment of physical and/or sensory disability which may beencountered after surgery. Patients with asymptomatic andimpacted mandibular third molars should be recalled for continuedfollow up, but should not be encouraged to undergo a procedureinvolving considerable risk, affecting their quality of life unlessthere is a good evidence of patient's benefit.Presence and position of mandibular impacted third molars hasbeen identified as one of the potential etiological factors of bothanterior crowding and late lower arch crowding post orthodontictreatment. This hypothesis has been nullified by research work.1Prevention of mandibular incisor crowding by the prophylacticremoval of third molars is therefore not justified.

Highest risks of complication of mandibular impacted thirdmolar removal have been shown to be between 25 to 34 years ofage as compared to higher age groups.2

This case report signifies and enlightens how impactedmandibular third molar extractions can affect the quality of lifeand also explains how to avoid such events and manage theconsequences.

CASE

A male patient 26 years of age, reported at the Department

M

1. Consultant in Restorative Dentistry University Medical & Dental College Faisalabad. 2. Professor, Head of Department of Dentistry Pakistan Institute of MedicalSciences, Islamabad.3. Associate Professor, Department of Prosthodontics Margalla College of Dentistry,Rawalpindi.Correspondence to:“Dr. Malik Salman Aziz” <drsalmanaziz@gmail.com >

Ayub Hassan3 BDS, MCPS

CASE REPORT

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Aziz MS / Maxood A / Hassan A Dilemma of impacted mandibular third molarextractions: Review of a case

of Dentistry, Pakistan Institute of Medical Sciences with thecomplaint of numbness and occasional tingling on the entire rightside of his lower jaw including the lower lip and chin, and onthe left half of his tongue which also had no taste sensation. Onhistory taking it was revealed that he had undergone surgery forthe removal of both his mandibular third molars under generalanesthesia, at a dental hospital abroad (location undisclosed). Onexamination of his presurgical panoramic tomograph andperiapicals, it was revealed that both the mandibular molars wereimpacted, # 38 (FDI) being horizontal, while #48 (FDI) wasmesioangular. Additionally both these teeth were in close proximityof the inferior dental canal as shown in fig.1. This finding wasindicative of probability of trauma to the mandibular and lingual

nerves during removal of the impacted teeth. On furtherquestioning, the patient also disclosed that, he being a flyingofficer at an international airline, was suffering from frequentand excruciating episodes of pain, in his posterior mandibularregion during flights only, which became the main reason forhim opting to undergo removal of both his wisdom teeth. Therewas no history of episodes of pain with infection and swelling,i.e. pericoronitis in the mandibular third molar regions.

On examination, the patient was afebrile but had trismus,and ulceration at the angle of the mouth (fig 2). The socket healing

was normal. Thorough neurosensory examination was carriedout in the form of pin prick and light touch sensation test, whichconfirmed the anesthesia in the areas innervated by right

mandibular inferior dental nerve both intraorally as well asextraorally. Provocation taste test was conducted, which includesthe placement of sugar salt and mustard on the patient’s tongue,to confirm the ageusia on the left anterior half of the tongue. Itwas concluded that the patient had anesthesia on the entiremandibular right side and diminished taste sensation on the leftanterior part of tongue. Rest of the oral cavity had a normalpresentation. There was however a crown in upper central incisorand a root treated maxillary right first molar which at the timeof examination did not show any abnormality. The patient wasotherwise fit and healthy.

The patient was reassured and was advised to have regularfollow up with a prescription of Methylcobalamin 500µg thricedaily. He was also advised not to have hot and spicy food stuff,keep a check on his intra oral environment daily so as to detectany trauma to the mucosa which may be in the form of ulceration,and not to chew his lip in order to check for the presence of anysensation.

On first follow up appointment after 15 days the patientreported minute alleviation in symptoms, in the form ofimprovement in taste sensation, however paresthesia of gumsand lip on the right side was the same. Neurosensory examinationwas again inconclusive. Patient was advised to continue treatmentfor 15 more days. On subsequent visit, patient reported someform of sensations at night on the left side but over all thecondition remained the same. He was then referred to an oral andmaxillofacial surgeon and neurologist for opinion and furthermanagement.

DISCUSSION

Mandibular third molars lie in close proximity to four mostimportant nerves, namely inferior dental, lingual and mylohyoidand long buccal nerves. These nerves are at constant risk ofdamage during surgical removal of impacted mandibular thirdmolars.

Conditions which necessitate impacted mandibular thirdmolar removal include acute or chronic pericoronitis, presenceof caries on the second molar or third molar itself, presence ofcysts, periodontal disease of second molar, resorption of adjacenttooth caused by the impacted third molar, pre or post orthodontictreatment or pre orthognathic surgery.3

The incidence of third molar removal has always been highall over the world with prophylactic extractions topping thelist.4-6 However since the newly published recommendations ofBritish National Institute of Clinical Excellence (NICE), the trendfor prophylactic removal of mandibular third molars has changedin the UK and has started to flip towards a more conservative

Fig 1: Pre operative panoramic view

Fig: 2a Fig: 2bPost operative Clinical Pictures

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approach in the US. The guidelines given by NICE specificallyoppose prophylactic removal of impacted third molars.6

Removal of impacted mandibular third molars usuallyinvolves surgery under general anesthetic. Assessment of thefactors such as depth of impaction, angulation of tooth, rootcurvature, ramus relationship, root divergence, number of roots,relative horizontal position, periodontal membrane space, andproximity to the inferior alveolar nerve must be kept underconsideration during treatment planning, as they not only governthe difficulty of the procedure but also influence the post surgicalmanagement, outcomes and needs of the patient.7 Adverse eventsand complications of impacted third molar removal include effectsfrom hemorrhage to numbness.

Barodontalgia is defined as dental pain elicited by changesin barometric pressure in an asymptomatic tooth. Dental caries,pulpitis, defective restorations, periodontal pockets, pulp necrosis,apical periodontitis, impacted teeth and mucous retention cystshave been identified as possible causes of the condition.8

Sometimes air crew patients and air passengers challenge thedental surgeon in treating several flight related conditions as wasthe case with current patient, who ended up having removal ofboth his asymptomatic impacted mandibular molars making flightdiscomfort the main reason. According to the patient, the sideeffects were conveyed to him but his profession led him intodeciding for extraction. Last decision always remains with thepatient, but dentists should always perform his /her duty inconveying the risks, benefits and prognosis of the treatment tothe patient, taking written informed consent to avoid any unwantedsituations in the form of law suits. Moreover ethical bindingshould always be remembered, as patient’s wants may sometimesdisagree with it. In such situations, the patient should be referredfor opinion to a specialist.

If removal of a mandibular impacted third molar in closeproximity of inferior dental nerve is deemed necessary, apartfrom the conventional surgical techniques, a new approach hasbeen developed, in the form of coronectomy of the third molarwithout removal of the entire tooth.9 This technique, first describedin 1989, 10 has the advantage of avoiding a longer and moreinvasive surgery along with sparing the mandibular nerve, whichexempts the patients from unnecessary trauma. This procedureinvolves the removal of the crown of the third molar thuspromoting and facilitating the eruption and movement of retainedroots away from the inferior dental canal. Once the root portionof the tooth has erupted to a safe level above the inferior dentalcanal, it can be removed whenever required by a secondsurgery 11.The apparent undesirability of this procedure woulddefinitely be, that of patient undergoing two surgeries includingadministration of local anesthetic; however it has the advantage

of avoiding extreme effects on quality of patient’s life, alongwith refraining from probable general anesthesia .

Here a debate also arises, igniting an argument, as to whatwould be the fate of the pulp tissue and the remaining roots whichhave been left inside the bone? Well the answer has been providedby research on retention of retained vital roots,12-14 which statesthat retained roots remain vital and may in time get coveredby osteocementum and bone. 12-14 Therefore it is advised inliterature, not to treat or medicate the retained root pulp aftercoronectomy.11, 15

Methylcobalamin is a neurologically active form of vitaminB12, which has provided promising results in treatment of patientswith various nerve injuries; however its effectiveness in all casescannot be guaranteed. Besides it has disturbing side effects andtherefore should be discontinued if patient reports any symptomslike hypersensitivity reactions, gastrointestinal problems in theform of nausea and vomiting or anorexia and diarrhea16- 17.

Although the incidence of mandibular third molars in extremeproximity of inferior dental nerve is less, the clinician must keepin mind its possibility, especially if pre operative radiographsindicate a close relation. All cases of impacted mandibular thirdmolars in close relation to the mandibular nerve must be referredfor specialist management by oral and maxillofacial surgeon.

In general practice cases of nerve injury, if report to theclinician, must be considered for a referral to a neurologist andspecialist oral and maxillofacial surgeon for management.The reparative role of vitamin B12/methylcobalamin in nerveinjuries should be further investigated.

REFERENCES

1. Harradine NW, Pearson MH, Toth B. The effect of extractionof third molars on late lower incisor crowding: a randomizedcontrolled trial. Br J Orthod. 1998. 25(2): 117-122.2. Osborn TP, Frederickson G, Small IA, Torgerson TS. Aprospective study of complications related to mandibular thirdmolar surgery. J Oral Maxifac Surg. 1985: 43: 767-769.3. Bolondeau F, Daniel NG. Extraction of mandibular thirdmolars: Postoperative complications and their risk factors. J CanDent Assoc. 2007; 73(4): 325.4. Landes DP. The relationship between dental health andvariations in the level of third molar removals experienced bypopulations. Community Dental Health. 1998; 15: 67-71.5. Shepherd JP, Brickley M. Surgical removal of third molars.Br Med J. 1994; 309: 620-621.6. Friedman JW. The prophylactic extraction of third molars:A public health hazard. Am J Public Health. 2007; 97(9): 1554-1559.

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Dilemma of impacted mandibular third molarextractions: Review of a case

7. Akadiri OA, Obiechina AE, Arotiba JT, Fasola AO. Relativeimpact of patient characteristics and radiographic variables onthe difficulty of removing impacted mandibular third molars.J Contemp Dent Pract. 2008; 9(4):51-58.8. Zadik Y. Aviation dentistry: current concepts and practice.Br Dent J. 2009; 206(1):11-16.9. Renton T, Hankins M, Sproate C, McGurk M. A randomizedcontrolled trial to compare the incidence of injury to inferioralveolar nerve as a result of coronectomy and removal of mandibularthird molars. Br J Oral Maxfac Surg. 2005; 43(1): 7-12.10. O'Riordan BC. Uneasy lies the head that wears the crown.Br J Oral Maxillofac Surg 1997; 35:209.11. Pogrel MA, Lee JS, Muff DF. Coronectomy: A techniqueto protect the inferior alveolar nerve. J Oral Maxillofac Surg.2004; 62: 1447-1452.

12. Johnson DL, Kelly JF, Flinton RJ, Cornell MT. Histologicevaluation of vital root retention. J Oral Surg 32:829, 1974.13. Whitaker DD, Shankle RJ. A study of the histologic reactionof submerged root segments. Oral Surg Oral Med Oral Pathol1974;37:919-last page, 1974.14. Plata RL, Kelln EE, Linda L. Intentional retention ofvital submerged roots in dogs. Oral Surg Oral Med Oral Pathol1976 42:100-last page, 1976.15. Frafjord R, Renton T. A review of coronectomy. J OralSurg 2010; 3: 1-7.16. Jalaludin MA. Methylcobalamin treatment of Bell's palsy.Methods Find Exp Clin Pharmacol. 1995;17:539-544.17. Yaqub BA, Siddique A, Sulimani R. Effects ofmethylcobalamin on diabetic neuropathy. Clin NeurolNeurosurg. 1992;94:105-111.

Aziz MS / Maxood A / Hassan A