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Unerupted lower third molars and their influence on fractures of the mandibular angle and condyle
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British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
Unerupted lower third molars and their influence on fractures of the mandibular angle and condyle Pavan M. Patil ∗ School of Dental Sciences, Plot 32 & 34, Knowledge Park 3, Sharda University, Greater Noida 201308, Uttar Pradesh, India Accepted 22 June 2011 Available online 20 July 2011
Abstract Our aim was to assess the influence of the presence and state of impaction of mandibular third molars on the incidence of fractures of the mandibular angle and condyle. We designed a retrospective study of patients who presented for the treatment of mandibular fractures from January 2006 to April 2011. The independent variables were the presence and degree of impaction of lower third molars, and the outcome variables were the incidence of fractures of the mandibular angle and condyle. The information was acquired from hospital records and panoramic radiographs. Personal data included age, sex, mechanism of injuries, and number of fractures of the mandibular angle and condyle. We studied 110 fractures of the mandibular condyle and 80 of the angle. The incidence of fractures of the mandibular angle was higher in the group with incompletely erupted third molars (37/80, p < 0.001) and that of condylar fractures was higher in the group without (67/110, p < 0.001). An incompletely erupted third molar reduces the risk of condylar fractures and increases the risk of fractures of the mandibular angle. © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Impacted third molars; Condylar fracture; Angle fracture
Introduction The mandible is fractured more often than the other facial bones, even though it is considered to be the strongest and most rigid bone in the facial skeleton. Many authors have reported that patients with unerupted mandibular third molars were more likely to have an angle fracture than those without, because the region of the mandibular angle that contains the unerupted third molars has a reduced cross-sectional bony area.1–5 Based on this evidence, some investigators have advocated the removal of unerupted mandibular third molars to prevent fractures of the mandibular angle.2,3,6 However, other authors have reported more condylar fractures in patients who do not have impacted lower third molars.7,8 The purpose of this study was to examine the influence of the presence and state of impaction of unerupted mandibular
∗
Tel.: +91 9999970260/9891812068; fax: +91 120 2323613. E-mail address: [email protected]
third molars on the incidence of fractures of the mandibular angle and condyle.
Patients and methods We did a retrospective review of all unilateral fractures of the mandibular angle and condyle that were treated at the School of Dental Sciences, Sharda University, Greater Noida, Uttar Pradesh, India, from June 2006 to April 2011. The study was approved by the Ethics Committee. During the study period 190 patients had unilateral fractures of the mandibular angle or condyle. Data were collected from the patients’ hospital records and panoramic radiographs for the following information: age, sex, cause of fractures, the presence and state of the lower third molars, and the number and sites of the mandibular fractures. The causes of fractures were grouped into: assault, fall, motor vehicle crash, and other (sports accident, or occupational). Patients with mandibular
0266-4356/$ – see front matter © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.bjoms.2011.06.002
444
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
Table 1 Details of patients. Data are expressed as number (%) of patients except where otherwise stated. Fractures Angle (n = 80) Sex Male Female Mean (SD) age (years) Causes Fall Motor vehicle crash Assault Other
Table 2 Position of the third molar according to the side of the angle and condylar fractures. Data are expressed as number (%). Side of fracture
Condyle (n = 110)
72 (90) 8 (10) 24 (5)
92 (84) 18 (16) 33 (4)
24 (30) 38 (48) 15 (19) 3 (4)
37 (34) 50 (45) 21 (19) 2 (2)
There were no significant differences between the groups.
fractures caused by gunshot wounds, pathological fractures, and those whose data were incomplete, were excluded. We used the definition of a fracture of the mandibular angle that was given by Kelly and Harrigan:9 a fracture located posterior to the second molar that extended from any point on the curve formed by the junction of the body and ramus in the retromolar area to any point on the curve formed by the inferior border of the body and posterior border of the ramus of the mandible. A condylar fracture was defined as a fracture in which the fracture line extended over the sigmoid notch. The variables studied were the characteristics of the mandibular fractures (whether or not it was associated with another mandibular fracture) and those of the third molars according to Pell and Gregory’s classification10 in the vertical and horizontal plane, and to Shiller’s classification11 of the angulation. From the information obtained we divided the patients into three groups for fractures of the mandibular angle and condyle according to whether or not there were unerupted third molar teeth. Any third molar partially or completely covered by bone tissue was regarded as unerupted. We calculated the mean (SD), and the significances of differences were assessed with the help of the chi square test and Student’s t test, as appropriate. Probabilities of less than 0.05 were accepted as significant.
Results Mandibular angle fracture The age and sex of the patients and the causes of the fractures are given in Table 1. Most (46%) were in the 21–30 years age group. The side involved and position of the third molar are shown in Table 2, and the condition of the third molar depending on the type of fracture in Table 3. In 46 cases the angle fracture was associated with another mandibular fracture (Table 4). If we use the classification of Pell and Gregory,10 for the 37 impacted third molars, the largest
Position of third molar Erupted
Impacted
16 (50) 23 (48)
13 (41) 21 (44)
3(9)* 4 (8)
Total (n = 80) Condyle Right (n = 53) Left (n = 57)
39 (49)
34 (43)
7 (9)
27 (51) 28 (49)
22 (42) 23 (40)
4 (8)** 6(11)
Total (n = 110)
55 (50)
45 (41)
10 (9)
Angle Right (n = 32) Left (n = 48)
∗ ∗∗
Absent
p = 0.33. p = 0.83.
numbers corresponded to Class I (20, 53%) and Class II (16, 42%). Most of the teeth were classified as Class A (n = 22, 60%), followed by Class B (n = 14, 37%). According to Shiller’s classification,11 n = 17 (46%) of the teeth had vertical angulation, followed by 13 (35%) with mesioangular angulation, 5 (13%) in the horizontal position, and 2 (6%) with distoangular angulation. Condylar fracture The mean age of the 110 patients was 33 (16–74) years. Ninety-two patients (84%) were men and 18 women (16%, Table 1). The condylar fracture was associated with a fracture in another region of the mandible in 48 cases (Table 4). Of the 110 condylar fractures, the third molar had erupted in the largest group (n = 67, 61%), followed by 23 (21%) with an impacted tooth, and 20 (18%) with a missing tooth (Table 3). There was no significant difference between the side of the fracture and the condition of the tooth (absent, erupted, or impacted) (p = 0.8). Of the 101 teeth present, 72 (71%) were classified as Class I, and 26 (26%) as Class II. If the Pell and Gregory classification is used, the largest numbers corresponded to Class A (n = 66, 65%) and Class B (n = 32, 32%). According to Shiller’s classification, 65 of the teeth (65%) had vertical angulation, followed by 21 (21%) with mesioangular angulation, 9 (9%) with horizontal angulation, and 4 (4%) with distoangular angulation. The number of impacted third molars was 23/110 (21%), the difference being significant (p = 0.001) when compared with the corresponding Table 3 Evaluation of the condition of the third molar according to the type of fracture. Data are expressed as number (%) of patients. Condition of third molar
Type of fracture Angle (n = 80)
Impacted Erupted Absent ∗ ∗∗
p = 0.001. p = 0.001.
37 (46) 41 (51) 2 (3)
Condyle (n = 110) 23 (21)* 67 (61) 20 (18)**
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
445
Table 4 Sites and numbers of multiple fractures in patients with and without unerupted third molars. Data are expressed as number (%). Fracture
Third molar unerupted (n = 49)
Third molar erupted (n = 43)
Symphysis and angle Symphysis and condyle Symphysis, angle, and condyle Angle and condyle
35 (71) 12 (24) 1 (2) 1 (2)
9 (21)* 34 (79)** 0 0
∗ ∗∗
p = 0.001. p = 0.001.
values among those with angle fractures (37/80 (46%), Table 3). Third molars were significantly more likely to be absent among the cases with condylar fractures (18%) than among those with angle fractures (3%), (n = 3, p = 0.001; Table 3).
Discussion We have aimed to evaluate the relation between third molars and fractures of the angle and condyle. Bilateral condylar fractures were excluded from the study as the mechanism in such fractures is more likely to be injury to the chin, which is less likely to fracture the angle than the condyle, while unilateral fractures of the angle or condyle could both result from lateral forces. As far as the effect of an unerupted mandibular third molar is concerned on the risk of an angle fracture, we agree with the findings of other published reports.1,2,4,5 The incidence of angle fractures is significantly higher in patients with unerupted third molars than in those without. The region of the mandibular angle with an unerupted third molar is an area of lowered resistance to external forces,12 and this observation has been confirmed by experimental studies on mandibles in monkeys.13 Reitzik et al.13 showed that a mandible with unerupted third molars required 40% less force to fracture it than one with fully erupted third molars, and they suggested that the unerupted third molars could weaken the mandible because the tooth occupied more of the osseous space. According to this theory, if the tooth was buried deeper this would increase this risk. However, the results of our study are at odds with this, though they do confirm a biomechanical study by Meisami et al.,14 which suggested that mandibular resistance is maintained by the integrity of the cortical bone, not the medullary bone; this means that the superficial position of the third molar breaks the integrity of the external oblique line to create a fragile point in the mandible. We also confirm the results of Halmos et al.15 that there is a greater risk of angle fractures when the third molar is present, and a variable risk depending on the position of the third molar, the risk being greater in Pell and Gregory’s classes I and II and A and B.10 According to Shiller’s classification, the vertical angulation was more common, followed by mesioangular angulation, which confirms the results of Ma’aita et al.16 However, Iida et al.8 found no significant difference between the position of the third molar and the risk of angle fractures.
The number of condylar fractures was larger among the patients who did not have an impacted third molar (absent or erupted 79%), which is in agreement with recent studies by Duan and Zhang,17 Zhu et al.,7 and Iida et al.8 Our findings could be explained by the reduction of the absorption capacity of the mandibular angle. According to Kober et al.18 the resistance of the mandibular angle increases when the third molar is erupted or absent, which causes the force to be transmitted to a more fragile region, namely the condyle. The results of this study agree with those of Duan and Zhang17 in relation to the prevalence in an older population, and the predominant sex (male). The greater predisposition of men could be explained by the fact that they are more exposed to the risk factors for facial trauma, such as motor vehicle crashes and physical aggression. The results of this study suggest that if the mandibular angle is made more resistant to fracture under a traumatic force, such trauma would create a fracture elsewhere, particularly the mandibular condyle. Difficulties are often encountered in repositioning the condylar fragments,19 as well as with accurate placement of the plates and screws through poor visibility in the operative field and difficult haemostasis. In addition, there is the possibility of injuring the facial nerve.20,21 However, excellent reduction and stable fixation in angle fractures are easy because the access and visibility for plating is much better, although Ellis has reported that the rate of postoperative complications is higher.22 It might not be appropriate therefore to strengthen the mandibular angle and to make the mandible more vulnerable to condylar fractures by means of removing the unerupted third molars, because the treatment of condylar fractures is more challenging than that of angle fractures. Prophylactic removal of symptom-free unerupted third molars may not be beneficial as a means of reducing the chances of angle fracture in those patients at risk of maxillofacial trauma. In conclusion, fractures of the condylar region were significantly more common among patients with erupted or absent third molars, while there were significantly more angle fractures among those with incompletely erupted third molars.
References 1. Hanson BP, Cummings P, Rivara FP, John MT. The association of third molars with mandibular angle fractures: a meta-analysis. J Can Dent Assoc 2004;70:39–43.
446
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
2. Lee JT, Dodson TB. The effect of mandibular third molar presence and position on the risk of an angle fracture. J Oral Maxillofac Surg 2000;58:394–8. 3. Peterson LJ. Principles of management of impacted teeth. In: Peterson LJ, Ellis III E, Hupp JR, Tucker MR, editors. Contemporary oral and maxillofacial surgery. 3rd ed. St. Louis: Mosby; 1993. p. 215–48. 4. Safdar N, Meechan JG. Relationship between fractures of the mandibular angle and the presence and state of eruption of the lower third molar. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79: 680–4. 5. Tevepaugh DB, Dodson TB. Are mandibular third molars a risk factor for angle fractures? A retrospective cohort study. J Oral Maxillofac Surg 1995;53:646–50. 6. Schwimmer A, Stern R, Kritchman D. Impacted third molars: a contributing factor in mandibular fractures in contact sports. Am J Sports Med 1983;11:262–6. 7. Zhu SJ, Choi BH, Kim HJ. Relationship between the presence of unerupted mandibular third molars and fractures of the mandibular condyle. Int J Oral Maxillofac Surg 2005;34:382–5. 8. Iida S, Nomura K, Okura M, Kogo M. Influence of the incompletely erupted lower third molar on mandibular angle and condylar fractures. J Trauma 2004;57:613–7. 9. Kelly DE, Harrigan WF. A survey of facial fractures: Belle Vue Hospital, 1948–1974. J Oral Surg 1975;33:146–9. 10. Pell GJ, Gregory GT. Impacted mandibular third molars: classification and modified technique for removal. Dent Dig 1933;39: 330–8. 11. Shiller W. Positional changes in mesio-angular impacted mandibular third molars during a year. J Am Dent Assoc 1979;99:460–4.
12. Krimmel M, Reinert S. Mandibular fracture after third molar removal. J Oral Maxillofac Surg 2000;58:1110–2. 13. Reitzik M, Lownie JF, Cleaton JP, Austin J. Experimental fractures of monkey mandibles. Int J Oral Surg 1978;7:100–3. 14. Meisami T, Sojat A, Sàndor GK, Lawrence HP, Clokie CM. Impacted third molars and risk of angle fracture. Int J Oral Maxillofac Surg 2002;31:140–4. 15. Halmos DR, Ellis III E, Dodson TB. Mandibular third molars and angle fractures. J Oral Maxillofac Surg 2004;62:1076–81. 16. Ma’aita J, Alwrikat A. Is the mandibular third molar a risk factor for mandibular angle fracture? Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:143–6. 17. Duan DH, Zhang Y. Does the presence of mandibular third molars increase the risk of angle fracture and simultaneously decrease the risk of condylar fracture? Int J Oral Maxillofac Surg 2008;37:25–8. 18. Kober C, Sader R, Thiele H. Stress analysis of the human mandible in standard trauma situations with numerical simulation (in German). Mund Kiefer Gesichtschir 2001;5:114–9. 19. Hendrix JH, Sanders SG, Green B. Open reduction of mandibular condyle: a clinical and experimental study. Plast Reconstr Surg Transplant Bull 1959;23:283–7. 20. Brown AE, Obeid G. A simplified method for the internal fixation of fractures of the mandibular condyle. Br J Oral Maxillofac Surg 1984;22:145–50. 21. Peters RA, Caldwell JB, Olsen TW. A technique for open reduction of subcondylar fractures. Oral Surg Oral Med Oral Pathol 1976;41:273–80. 22. Ellis III E. Complications of mandibular condyle fractures. Int J Oral Maxillofac Surg 1998;27:255–7.
British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
Unerupted lower third molars and their influence on fractures of the mandibular angle and condyle Pavan M. Patil ∗ School of Dental Sciences, Plot 32 & 34, Knowledge Park 3, Sharda University, Greater Noida 201308, Uttar Pradesh, India Accepted 22 June 2011 Available online 20 July 2011
Abstract Our aim was to assess the influence of the presence and state of impaction of mandibular third molars on the incidence of fractures of the mandibular angle and condyle. We designed a retrospective study of patients who presented for the treatment of mandibular fractures from January 2006 to April 2011. The independent variables were the presence and degree of impaction of lower third molars, and the outcome variables were the incidence of fractures of the mandibular angle and condyle. The information was acquired from hospital records and panoramic radiographs. Personal data included age, sex, mechanism of injuries, and number of fractures of the mandibular angle and condyle. We studied 110 fractures of the mandibular condyle and 80 of the angle. The incidence of fractures of the mandibular angle was higher in the group with incompletely erupted third molars (37/80, p < 0.001) and that of condylar fractures was higher in the group without (67/110, p < 0.001). An incompletely erupted third molar reduces the risk of condylar fractures and increases the risk of fractures of the mandibular angle. © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Impacted third molars; Condylar fracture; Angle fracture
Introduction The mandible is fractured more often than the other facial bones, even though it is considered to be the strongest and most rigid bone in the facial skeleton. Many authors have reported that patients with unerupted mandibular third molars were more likely to have an angle fracture than those without, because the region of the mandibular angle that contains the unerupted third molars has a reduced cross-sectional bony area.1–5 Based on this evidence, some investigators have advocated the removal of unerupted mandibular third molars to prevent fractures of the mandibular angle.2,3,6 However, other authors have reported more condylar fractures in patients who do not have impacted lower third molars.7,8 The purpose of this study was to examine the influence of the presence and state of impaction of unerupted mandibular
∗
Tel.: +91 9999970260/9891812068; fax: +91 120 2323613. E-mail address: [email protected]
third molars on the incidence of fractures of the mandibular angle and condyle.
Patients and methods We did a retrospective review of all unilateral fractures of the mandibular angle and condyle that were treated at the School of Dental Sciences, Sharda University, Greater Noida, Uttar Pradesh, India, from June 2006 to April 2011. The study was approved by the Ethics Committee. During the study period 190 patients had unilateral fractures of the mandibular angle or condyle. Data were collected from the patients’ hospital records and panoramic radiographs for the following information: age, sex, cause of fractures, the presence and state of the lower third molars, and the number and sites of the mandibular fractures. The causes of fractures were grouped into: assault, fall, motor vehicle crash, and other (sports accident, or occupational). Patients with mandibular
0266-4356/$ – see front matter © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.bjoms.2011.06.002
444
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
Table 1 Details of patients. Data are expressed as number (%) of patients except where otherwise stated. Fractures Angle (n = 80) Sex Male Female Mean (SD) age (years) Causes Fall Motor vehicle crash Assault Other
Table 2 Position of the third molar according to the side of the angle and condylar fractures. Data are expressed as number (%). Side of fracture
Condyle (n = 110)
72 (90) 8 (10) 24 (5)
92 (84) 18 (16) 33 (4)
24 (30) 38 (48) 15 (19) 3 (4)
37 (34) 50 (45) 21 (19) 2 (2)
There were no significant differences between the groups.
fractures caused by gunshot wounds, pathological fractures, and those whose data were incomplete, were excluded. We used the definition of a fracture of the mandibular angle that was given by Kelly and Harrigan:9 a fracture located posterior to the second molar that extended from any point on the curve formed by the junction of the body and ramus in the retromolar area to any point on the curve formed by the inferior border of the body and posterior border of the ramus of the mandible. A condylar fracture was defined as a fracture in which the fracture line extended over the sigmoid notch. The variables studied were the characteristics of the mandibular fractures (whether or not it was associated with another mandibular fracture) and those of the third molars according to Pell and Gregory’s classification10 in the vertical and horizontal plane, and to Shiller’s classification11 of the angulation. From the information obtained we divided the patients into three groups for fractures of the mandibular angle and condyle according to whether or not there were unerupted third molar teeth. Any third molar partially or completely covered by bone tissue was regarded as unerupted. We calculated the mean (SD), and the significances of differences were assessed with the help of the chi square test and Student’s t test, as appropriate. Probabilities of less than 0.05 were accepted as significant.
Results Mandibular angle fracture The age and sex of the patients and the causes of the fractures are given in Table 1. Most (46%) were in the 21–30 years age group. The side involved and position of the third molar are shown in Table 2, and the condition of the third molar depending on the type of fracture in Table 3. In 46 cases the angle fracture was associated with another mandibular fracture (Table 4). If we use the classification of Pell and Gregory,10 for the 37 impacted third molars, the largest
Position of third molar Erupted
Impacted
16 (50) 23 (48)
13 (41) 21 (44)
3(9)* 4 (8)
Total (n = 80) Condyle Right (n = 53) Left (n = 57)
39 (49)
34 (43)
7 (9)
27 (51) 28 (49)
22 (42) 23 (40)
4 (8)** 6(11)
Total (n = 110)
55 (50)
45 (41)
10 (9)
Angle Right (n = 32) Left (n = 48)
∗ ∗∗
Absent
p = 0.33. p = 0.83.
numbers corresponded to Class I (20, 53%) and Class II (16, 42%). Most of the teeth were classified as Class A (n = 22, 60%), followed by Class B (n = 14, 37%). According to Shiller’s classification,11 n = 17 (46%) of the teeth had vertical angulation, followed by 13 (35%) with mesioangular angulation, 5 (13%) in the horizontal position, and 2 (6%) with distoangular angulation. Condylar fracture The mean age of the 110 patients was 33 (16–74) years. Ninety-two patients (84%) were men and 18 women (16%, Table 1). The condylar fracture was associated with a fracture in another region of the mandible in 48 cases (Table 4). Of the 110 condylar fractures, the third molar had erupted in the largest group (n = 67, 61%), followed by 23 (21%) with an impacted tooth, and 20 (18%) with a missing tooth (Table 3). There was no significant difference between the side of the fracture and the condition of the tooth (absent, erupted, or impacted) (p = 0.8). Of the 101 teeth present, 72 (71%) were classified as Class I, and 26 (26%) as Class II. If the Pell and Gregory classification is used, the largest numbers corresponded to Class A (n = 66, 65%) and Class B (n = 32, 32%). According to Shiller’s classification, 65 of the teeth (65%) had vertical angulation, followed by 21 (21%) with mesioangular angulation, 9 (9%) with horizontal angulation, and 4 (4%) with distoangular angulation. The number of impacted third molars was 23/110 (21%), the difference being significant (p = 0.001) when compared with the corresponding Table 3 Evaluation of the condition of the third molar according to the type of fracture. Data are expressed as number (%) of patients. Condition of third molar
Type of fracture Angle (n = 80)
Impacted Erupted Absent ∗ ∗∗
p = 0.001. p = 0.001.
37 (46) 41 (51) 2 (3)
Condyle (n = 110) 23 (21)* 67 (61) 20 (18)**
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
445
Table 4 Sites and numbers of multiple fractures in patients with and without unerupted third molars. Data are expressed as number (%). Fracture
Third molar unerupted (n = 49)
Third molar erupted (n = 43)
Symphysis and angle Symphysis and condyle Symphysis, angle, and condyle Angle and condyle
35 (71) 12 (24) 1 (2) 1 (2)
9 (21)* 34 (79)** 0 0
∗ ∗∗
p = 0.001. p = 0.001.
values among those with angle fractures (37/80 (46%), Table 3). Third molars were significantly more likely to be absent among the cases with condylar fractures (18%) than among those with angle fractures (3%), (n = 3, p = 0.001; Table 3).
Discussion We have aimed to evaluate the relation between third molars and fractures of the angle and condyle. Bilateral condylar fractures were excluded from the study as the mechanism in such fractures is more likely to be injury to the chin, which is less likely to fracture the angle than the condyle, while unilateral fractures of the angle or condyle could both result from lateral forces. As far as the effect of an unerupted mandibular third molar is concerned on the risk of an angle fracture, we agree with the findings of other published reports.1,2,4,5 The incidence of angle fractures is significantly higher in patients with unerupted third molars than in those without. The region of the mandibular angle with an unerupted third molar is an area of lowered resistance to external forces,12 and this observation has been confirmed by experimental studies on mandibles in monkeys.13 Reitzik et al.13 showed that a mandible with unerupted third molars required 40% less force to fracture it than one with fully erupted third molars, and they suggested that the unerupted third molars could weaken the mandible because the tooth occupied more of the osseous space. According to this theory, if the tooth was buried deeper this would increase this risk. However, the results of our study are at odds with this, though they do confirm a biomechanical study by Meisami et al.,14 which suggested that mandibular resistance is maintained by the integrity of the cortical bone, not the medullary bone; this means that the superficial position of the third molar breaks the integrity of the external oblique line to create a fragile point in the mandible. We also confirm the results of Halmos et al.15 that there is a greater risk of angle fractures when the third molar is present, and a variable risk depending on the position of the third molar, the risk being greater in Pell and Gregory’s classes I and II and A and B.10 According to Shiller’s classification, the vertical angulation was more common, followed by mesioangular angulation, which confirms the results of Ma’aita et al.16 However, Iida et al.8 found no significant difference between the position of the third molar and the risk of angle fractures.
The number of condylar fractures was larger among the patients who did not have an impacted third molar (absent or erupted 79%), which is in agreement with recent studies by Duan and Zhang,17 Zhu et al.,7 and Iida et al.8 Our findings could be explained by the reduction of the absorption capacity of the mandibular angle. According to Kober et al.18 the resistance of the mandibular angle increases when the third molar is erupted or absent, which causes the force to be transmitted to a more fragile region, namely the condyle. The results of this study agree with those of Duan and Zhang17 in relation to the prevalence in an older population, and the predominant sex (male). The greater predisposition of men could be explained by the fact that they are more exposed to the risk factors for facial trauma, such as motor vehicle crashes and physical aggression. The results of this study suggest that if the mandibular angle is made more resistant to fracture under a traumatic force, such trauma would create a fracture elsewhere, particularly the mandibular condyle. Difficulties are often encountered in repositioning the condylar fragments,19 as well as with accurate placement of the plates and screws through poor visibility in the operative field and difficult haemostasis. In addition, there is the possibility of injuring the facial nerve.20,21 However, excellent reduction and stable fixation in angle fractures are easy because the access and visibility for plating is much better, although Ellis has reported that the rate of postoperative complications is higher.22 It might not be appropriate therefore to strengthen the mandibular angle and to make the mandible more vulnerable to condylar fractures by means of removing the unerupted third molars, because the treatment of condylar fractures is more challenging than that of angle fractures. Prophylactic removal of symptom-free unerupted third molars may not be beneficial as a means of reducing the chances of angle fracture in those patients at risk of maxillofacial trauma. In conclusion, fractures of the condylar region were significantly more common among patients with erupted or absent third molars, while there were significantly more angle fractures among those with incompletely erupted third molars.
References 1. Hanson BP, Cummings P, Rivara FP, John MT. The association of third molars with mandibular angle fractures: a meta-analysis. J Can Dent Assoc 2004;70:39–43.
446
P.M. Patil / British Journal of Oral and Maxillofacial Surgery 50 (2012) 443–446
2. Lee JT, Dodson TB. The effect of mandibular third molar presence and position on the risk of an angle fracture. J Oral Maxillofac Surg 2000;58:394–8. 3. Peterson LJ. Principles of management of impacted teeth. In: Peterson LJ, Ellis III E, Hupp JR, Tucker MR, editors. Contemporary oral and maxillofacial surgery. 3rd ed. St. Louis: Mosby; 1993. p. 215–48. 4. Safdar N, Meechan JG. Relationship between fractures of the mandibular angle and the presence and state of eruption of the lower third molar. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79: 680–4. 5. Tevepaugh DB, Dodson TB. Are mandibular third molars a risk factor for angle fractures? A retrospective cohort study. J Oral Maxillofac Surg 1995;53:646–50. 6. Schwimmer A, Stern R, Kritchman D. Impacted third molars: a contributing factor in mandibular fractures in contact sports. Am J Sports Med 1983;11:262–6. 7. Zhu SJ, Choi BH, Kim HJ. Relationship between the presence of unerupted mandibular third molars and fractures of the mandibular condyle. Int J Oral Maxillofac Surg 2005;34:382–5. 8. Iida S, Nomura K, Okura M, Kogo M. Influence of the incompletely erupted lower third molar on mandibular angle and condylar fractures. J Trauma 2004;57:613–7. 9. Kelly DE, Harrigan WF. A survey of facial fractures: Belle Vue Hospital, 1948–1974. J Oral Surg 1975;33:146–9. 10. Pell GJ, Gregory GT. Impacted mandibular third molars: classification and modified technique for removal. Dent Dig 1933;39: 330–8. 11. Shiller W. Positional changes in mesio-angular impacted mandibular third molars during a year. J Am Dent Assoc 1979;99:460–4.
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