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doimost common surgical events.1 This is why, inite of the diversified demands of practice, manyntal surgeons will still need to face the problem ofoval of impacted mandibular third molars.2 Bothpatient and dentist must therefore have scientific

idence-based information concerning the estimatedel of surgical difficulty of every case.There are a number of previous studies to evaluatergical difficulty in the extraction of impacted man-ular third molars.1-6 However, most of these stud-were based only on dental factors evaluated byiologic assessment.2-5 Opinions vary on these ra-logic factors, but most authors agree that they play

believe it is difficult to estimate actual difficulty byradiologic methods only, and that it is only intraoper-atively that actual difficulty can be estimated.7 Someauthors also believe that clinical variables such as age,gender, and weight of the patient are also very impor-tant.1,6 Few authors have proposed indexes for mea-suring intraoperative/surgical difficulty.5 Pedersonproposed such an index, but it is seldom used be-cause it has been reported that it does not matchactual surgical difficulty.5

This study aims to use both clinical and radiologicvariables in estimating intraoperative difficulty. Wealso propose a preoperative index based on bothclinical and radiologic variables.

Patients and Methods

Patients who were referred for extraction of im-pacted mandibular third molars between October2003 and April 2004 at the Oral and MaxillofacialClinic of the Lagos University Teaching Hospital (La-gos, Nigeria) were included in the study. Approval forthe study was obtained from the local ethics commit-tee and informed consent was obtained from all par-ticipating patients.

eived from the Department of Oral and Maxillofacial Surgery,

llege of Medicine, University of Lagos, Lagos, Nigeria.

Lecturer.

Associate Professor and Consultant.

Senior Lecturer and Consultant.

Address correspondence and reprint requests to Dr Gbotolo-

: Department of Oral and Maxillofacial Surgery, College of

dicine, University of Lagos, P.M.B 12003, Lagos, Nigeria;

ail: lekangbotol@yahoo.co.uk

007 American Association of Oral and Maxillofacial Surgeons

8-2391/07/6510-0012$32.00/0

:10.1016/j.joms.2006.11.030

1977Assessment of FactoSurgical Difficu

Mandibular ThirdOlalekan Micah Gbot

Godwin Toyin Arotiba, BDS, FM

Akinola Ladipo Ladeind

Purpose: The aim of this prospective study was towith increased difficulty in the removal of impactedindex to measure the difficulty of removal of the im

Patients and Methods: A total of 87 patientsmandibular third molars from November 2003 to Mclinical data were taken preoperatively. All extractiooperator. Surgical difficulty was measured by the to

Results: Increased surgical difficulty was associatealso associated with the curvature of roots of the im(P .05).

Conclusion: Both clinical and radiologic variableimpacted mandibular third molar extractions. 2007 American Association of Oral and MaxilloJ Oral Maxillofac Surg 65:1977-1983, 2007Associated Within Impactedolar Extraction

n, BDS, FMCDS,*

, FWACS, FDS RCSEd, and

S, FMCDS, FWACS

tigate radiologic and clinical factors associateddibular third molars. We also aimed to form aned molars preoperatively.

required 90 surgical extractions of impacted04 were involved in the study. Radiologic andre performed under local anesthesia by a singletervention time.

th increasing age and body mass index. It wasd tooth and the depth from point of elevation

important in predicting surgical difficulty in

l Surgeons

Table 1. CLASSIFICATION OF PREOPERATIVE VARIABLES

Variable/Definition ClassificationGe

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1978 SURGICAL DIFFICULTY IN THIRD MOLAR EXTRACTIONnder 1: male2: female

e: age at last birthday 1: 16242: 25353: above 35

I (body mass index): weight in kg divided byeight in meters squared

1: below 182: 18 to below 253: 25 to below 304: above 30

clusal level: the level of the occlusal plane ofhe third molar compared with the secondolar

1: highwhen the highest part of the crown of the thirdmolar is above or at the same level as that of the secondmolar

2: mediumwhen the highest part is lower than that ofthe second molar but higher than the amelocementaljunction

3: lowwhen the highest point is lower than theamelocemental junction of the second molar

tromolar space available: the ratio of theistance between the most distal point on therown of the second molar to the mostnterior point on the ascending ramus and theesiodistal width of the impacted tooth

1: Sufficient space when the ratio 12: reduced when the ratio was 1 but 0.53: no/very little space 0.5

gulation of impaction: the angle (measured byprotractor) measured in degrees formedetween the intersected long axes of theecond and third molars

1: vertical 10102: mesioangular 11793: horizontal 801004: distoangular 11795: others 11180

mber of roots 1: 1 fused root2: 2 roots3: 3 or more roots

rvature of roots: the long axis of the root inelationship to the root of the second molar

1: incomplete roots2: straight roots3: favorable roots when roots are curved in the directionand towards path of elevation

4: when roots were either curved in opposite direction oragainst path of elevation

ot inferior dental canal relationship 1: no contact when the root at its closest point is morethan 2 mm from the canal

2: approximation: when the closest point is 2 mm fromcanal but there is no contact

3: contact when there is any relationship between rootand canal (eg, contact, impinging, overlap)

ntact with second molar 1: no contact2: contact with crown only3: contact with crown and root4: contact with root only5: overlap

lbosity of roots: the ratio of the mesiodistalistance at the cervix and the widest pointlong the root of the impacted tooth

1: bulbous when ratio 12: when ratio 1

dth of crown: the ratio of the mesiodistalidth of the crown of the third and secondolars

1: bulbous when the ratio was 12: not bulbous when ratio is 1

ot periodontal space interface 1: clear when the periodontal space is clear all around thetooth

2: some clear when the periodontal space around thetooth is clear in some places

3: sclerosed when the periodontal space is not clear allround the tooth

otolorun et al. Surgical Difficulty in Third Molar Extraction. J Oral Maxillofac Surg 2007.

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GBOTOLORUN ET AL 1979Exclusion criteria were patients with only soft tis-e impaction and those with missing second molarjacent to the impacted tooth. Preoperative clinicald radiologic data were collected as shown in TableBased on the preoperative data, estimated level officulty of all extractions was done prior to surgerying the Pederson scale (Table 2) before the extrac-ns. The extractions were classified as easy, moder-ly difficult, and very difficult preoperatively.The surgical extractions were carried out underal anesthesia by a single operator. All proceduresre standardized, a buccal flap was raised and boneoval was performed using a fast hand piece,000150,000 rms) under continuous cool waterspray throughout the surgery. In all procedures theal intervention time (TII) was measured in minutesing a stopwatch. Extractions were also classifiedraoperatively as easy, moderately difficult, and veryficult based on the TII as shown in Table 3. Statis-al analysis was conducted using SPSS Inc version.5 (Chicago, IL). Univariate analysis of the preoper-ve variables in association with intraoperative diffi-

able 1. (CONTINUED)

pth from point of elevation: the length of aerpendicular line drawn from the distalmelocemental junction of the second molaristally and the point of application oflevator. The point of elevator for theesioangular and horizontal impactions was

he mesial amelocemental junction of thehird molar while for the vertical andistoangular was at the bifurcation

otolorun et al. Surgical Difficulty in Third Molar Extraction. J O

able 2. THE PEDERSON INDEX8

Classification Value

atial Relationshipesioangular 1orizontal/transverse 2ertical 3istoangular 4

pthevel A: high occlusal level 1evel B: medium occlusal level 2evel C: low occlusal level 3mus relationship/space availablelass 1: sufficient space 1lass 2: reduced space 2lass 3: no space 3ficulty indexery difficult 710oderately difficult 56lightly difficult 34

otolorun et al. Surgical Difficulty in Third Molar Extraction.ral Maxillofac Surg 2007.lty, as measured by the TII, was performed. Allriables with P values less than .1 were used inltiple linear regressions to identify the most impor-t variables in determining intraoperative difficultyextractions (Table 4). P values less than .05 wereen as statistically significant (Table 4).The relationship of these significant variables to TIIgs 1-4) was used to form a preoperative index officulty (Table 4). The sensitivity and specificity ofs new index in determining actual intraoperativeficulty (as measured by the TII) was compared witht of the Pederson index.8

sults

A total of 90 teeth from 87 patients were extractedring the period of the study. The male to femaleio was 1:1.1. The mean (SD) age of the patients was.6 6.2 years. The mean (SD) TII was 9.2 3.0nutes. The surgeries based on the TII were classi-d into easy, moderately difficult, and very difficult.

3 mm6 mm6 mm

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able 3. SIGNIFICANT LEVEL OF EACH VARIABLE INELATION TO TII AS THE INDEPENDENT VARIABLE

Variable

UnivariateAnalysis(P Value)

MultipleLinear

Regression(P Values)

nder .096 .478e* .0007 .048I* .0003 .047clusal level .0007 .088gulation of impaction .001 .265rvature of roots* .0002 .001ot/inferior dental canalelationship .0008 .063riodontal space/rootone interface .001 .365pth from point oflevation* .0001 .005

Statistically significant variables after multiple linear regressions.

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1980 SURGICAL DIFFICULTY IN THIRD MOLAR EXTRACTIONSixty extractions (66.7%) were classified as easy, 25.6%) as moderately difficult, and 5 (5.6%) werery difficult. Univariate analysis showed 9 variablesclinical, 6 radiologic variables) which had P lessn .1 in association with TII. However, after theltiple regressions only 4 variables had P values lessn .05 (P values are as shown in Table 4). The mostportant variable resulting in increased TII in thisdy was depth from point of extraction greater thanm. In the 3 cases where depth was greater than 6, 2 were classified as very difficult and 1 as mod-tely difficult (Fig 4). The extraction with the long-TII was also the one at the lowest depth (depthm point of elevation was 8 mm).The relationship of these significant variables to TIIgs 1-4) was used to form a preoperative index officulty (Table 3). The sensitivity and specificity ofnew index to determine actual intraoperative dif-

ulty as determined by the TII compared with thederson index was as follows: in determining easytraction, the new index had 74% and 79% sensitiv-and specificity, respectively (accuracy 76%),ile those of the Pederson8 index were 43% and%, respectively (accuracy 49%). In determiningderately difficult extractions, the sensitivity andecificity of the new index were 70% and 75%,pectively (accuracy 73%), while those of thederson8 index were 52% and 48%, respectively (ac-racy 49%). For difficult cases the new index was% sensitive and 97% specific (accuracy 98%), whilePederson8 was 20% sensitive and 89% specific

curacy 86%).

able 4. NEW INDEX SCORE

Variable Value Range

e 1 242 25343 34

I 1 242 25303 30

pth from point of elevation 1 03 mm2 46 mm3 6 mm

rvature of roots 1 Incomplete

2Straight/favorablycurved

3Unfavorablycurved

tal 12

w Index Score:asy, 46oderately difficult, 79ery difficult, 1012.

otolorun et al. Surgical Difficulty in Third Molar Extraction.ral Maxillofac Surg 2007.scussion

Preoperative assessment of surgical difficulty is fun-mental to the planning of extraction of impactedrd molars. The assessment is not only important todental surgeon who needs it to be able to decideether or nor to refer patients for specialist care,2

t it is also important in predicting the possiblemplications so that the patient can be informed.6

e percentage of extractions in each group of theraoperative score in this study (68.9%, 25.6%, and% for easy, moderately difficult, and very difficulttractions, respectively) is comparable to those ofinwande2 (65.3%, 30.6%, and 4.1%, respectively)o divided his score into similar groups. However,present study contrasts those of Renton et al1 andasa et al,5 although these studies used differentdes of classification of intraoperative difficulty.wever, most researchers agree that postoperativemplications are more commonly associated withre difficult extractions. With the range of difficulttractions from the studies between 4.1% and 44.5%,s imperative that patients are, to the highest level ofentific certainty, informed of the possibility of com-cations after removal of their impacted mandibularrd molars, based on a preoperative estimation officulty.Previous assessment models are based on dentaltors recorded on preoperative x-rays.1-6 Threeaginary lines to determine the depth of the man-ular third molars in bone have been describedrlier.9 This method is taught to most undergraduatedents, but is reported to be used little in practice.1

ll and Gregory11 described an alternative method,t it also has recently been found to be an unreliablethod of determining surgical difficulty.4 Edwards etcorroborated this by reporting that it is difficult toimate actual surgical difficulty by radiologic assess-nt alone.Both clinical and radiologic variables were used inr model in the present study. This was a modifica-n of the model used by Santamaria and Arteagatia.3

wever, another variable (ie, depth from the pointelevation) was added to the protocol used in thisdel. The point used in this model was based on thees described by Ward.10 Depth from the point ofvation has been described as the single most im-rtant indicator for prediction of the difficulty in thetraction of impacted mandibular third molars.2,9,10

is variable was also very important in determiningficulty in the present study.The clinical variables that were statistically signifi-nt in this study were age and body mass indexMI) of the patients. It was observed that with in-asing age and BMI the total time for extractionreased. Renton et al1 and Benediktsdottir et al6 also

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GBOTOLORUN ET AL 1981orted the same findings in their study. However,e of patients was not considered as a risk factor bysurgeons who answered questionnaires in the

eliminary survey by Yuasa et al.5 There was a sig-cant increase in TII in impacted third molar ex-ontias in relation to age of patients in this study,th more patients older than 34 years in the moder-

57.7

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otolorun et al. Surgical Difficulty in Third Molar Extraction. J O

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1982 SURGICAL DIFFICULTY IN THIRD MOLAR EXTRACTIONpth from the point of elevation. All these factorsve also been found to be related to increased diffi-lty in other studies.1-6 After multiple linear regres-n, however, only 4 of these variables (age, BMI,rvature of roots, and depth from point of elevation)re still in significant relationship with TII. Theltiple linear regressions were performed to deter-

100

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otolorun et al. Surgical Difficulty in Third Molar Extraction. J O

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otolorun et al. Surgical Difficulty in Third Molar Extraction. J One which of the variables were most important intermining the TII and thereby enabling a more userendly index to be formed with the most importantriables.The new index formed in this study uses all theiables that were found to be statistically significant.ch variable was put in a scale in the degree that it

47.442.1

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Easy

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Very difficult

CURVATURE OF ROOTS

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affected surgical difficulty. All variables used in the in-dex are easily identifiable in either periapical x-rays (asused in this study) or with orthopanthomographs. Thenew model was found to be more sensitive and specificin determining the degree of difficulty in almost allextraction groups than the Pederson index.8 It was alsoobserved in this study that the sensitivity of the Peder-son index8 in identifying very difficult cases was 20%,which was also reported by Yuasa et al5 (who claimedthat the Pederson index8 incorrectly identifies very dif-ficult extractions as moderately difficult).

This new index uses 4 variables (both clinical andradiologic). The authors of this study believe the majordifference of this index and the Pederson index8 is theincorporation of the clinical variables (namely age andBMI) that were important in determining surgical diffi-culty rather than radiologic variables alone, which wereused by the Pederson index.8

The new index formed from both clinical and radio-logic variables seems to be superior to that of the Ped-erson index, which used only radiologic variables. How-ever, more research has to be performed using thismodel to prove its superiority and remove bias.

References1. Renton T, Smeeton N, McGurk M: Factors predictive of difficulty

of mandibular third molar surgery. Br Den J 190:607, 20012. Akinwande JA: Mandibular third molar impactionA comparison

of two methods for predicting surgical difficulty. Nig Dent J 10:3,1991

3. Santamaria J, Arteagatia MD: Radiologic variables of clinical signif-icance in the extraction of impactedmandibular thirdmolars. OralSurg Oral Med Oral Pathol Oral Radiol Endod 84:469, 1997

4. Garcia AG, Sampedro FG, Rey JG, et al: Pell-Gregory is unre-liable as a predictor of difficulty in extracting impactedlower third molars. Br J Oral Maxillofac Surg 83:585, 2000

5. Yuasa H, Kawai T, Suguira M: Classification of surgical difficulty inextracting impacted third molars. Br J Oral Maxillofac 40:26, 2002

6. Benediktsdottir IS, Wenzel A, Petersen JK, et al: Mandibularthird molar removal: Risk for extended operation time, post-operative pain, and complication. Oral Surg Oral Med OralPathol Oral Radiol Endod 97:438, 2004

7. Edwards DJ, Brickley MR, Horton J, et al: Choice of anaestheticand healthcare facility for third molar surgery. Br J Oral Maxil-lofac Surg 36:333, 1998

8. Koerner KR: The removal of impacted third molars: Principlesand procedures. Dent Clin North Am 38:255, 1994

9. Howe GL: Minor Oral Surgery. Ed 2. Bristol, John Wright andSons, 1971

10. Ward TG: The radiographic assessment of the impacted lowerwisdom tooth. Dent Delineator 6:3, 1953

11. Pell GJ, Gregory BT: Impacted mandibular third molars; classi-fication and modified techniques for removal. Dent Digest39:330, 1933

GBOTOLORUN ET AL 1983

Assessment of Factors Associated With Surgical Difficulty in Impacted Mandibular Third Molar ExtractionPatients and MethodsResultsDiscussionReferences