|Year : 2015 | Volume
| Issue : 1 | Page : 35-41
Relationship between mandibular angle fracture and state of eruption of mandibular third molar: A digital radiographic study
Mahesh Kumar Talkad Subbaiah1, Indira Annamalai Ponnuswamy2, Maria Priscilla David2
1 Department of Oral Medicine and Radiology, Rajarajeswari Dental College and Hospital, Bangalore, Karnataka, India
2 Department of Oral Medicine and Radiology, MR Ambedkar Dental College and Hospital, Bangalore, Karnataka, India
|Date of Submission||12-Nov-2014|
|Date of Acceptance||14-Jul-2015|
|Date of Web Publication||12-Oct-2015|
Mahesh Kumar Talkad Subbaiah
Department of Oral Medicine and Radiology, Rajarajeswari Dental College and Hospital, #14, Ramohalli Cross, Kumbalagodu, Mysore Road, Bangalore - 560 060, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objectives: The purpose of this study was to assess the relationship between mandibular angle fracture and the status of eruption of the mandibular third molars. Materials and Methods: The sample consisted of 50 mandibular angle fracture cases with or without the presence of mandibular third molars, inclusive of both genders in the age group 18 years and above. The mandibular angle fractures were assessed by taking an orthopantomograph for each case following strict radiation protection protocol after an informed consent was obtained. The captured image was assessed and traced for the presence of mandibular angle fracture, angulation, and status of mandibular third molar by using Windows Trophy DICOM and Master View 3.0 software. Pell and Gregory's and Winter's classifications were followed. Results: We observed the following: Increased incidence of angle fractures in the presence of mandibular third molar, male predominance, the mean average age being 29 years, and the most common cause of angle fractures was road traffic accident; the fractures were observed more on the left side. In the total sample, mandibular third molar was present in 90% of the cases with angle fracture; of this, 73% of the teeth were impacted. Increased incidence of mandibular angle fracture was observed in position A, class II, and mesioangular impaction of third molar, which were statistically significant. Conclusion: The presence of mandibular third molar was in strong association with mandibular angle fracture and there was an increased incidence of position A, class II, and mesioangular impaction, when compared with other positions. This study concludes that there is a direct relationship between the presence and status of impacted third molars with increased risk of mandibular angle fracture.
Keywords: Mandibular angle fracture, mandibular third molar, status of eruption
|How to cite this article:|
Subbaiah MT, Ponnuswamy IA, David MP. Relationship between mandibular angle fracture and state of eruption of mandibular third molar: A digital radiographic study. J Indian Acad Oral Med Radiol 2015;27:35-41
|How to cite this URL:|
Subbaiah MT, Ponnuswamy IA, David MP. Relationship between mandibular angle fracture and state of eruption of mandibular third molar: A digital radiographic study. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2020 Sep 25];27:35-41. Available from: http://www.jiaomr.in/text.asp?2015/27/1/35/167074
| Introduction|| |
Maxillofacial injuries have remained serious clinical problems because of the specificity of this anatomical region.  Mandible in its vulnerable position and anatomic configuration is one of the most frequent facial bones to be involved in traumatic injuries with resultant fracture, even though it is considered the strongest and most rigid bone in the facial skeleton.  Weakest region of the mandible to fracture is the angle. Approximately 50% of fractures of the mandible involve areas with teeth and the presence of teeth are the most important factor in determining where the fracture occurs. 
The presence of third molar is associated with twofold to threefold increased risk of angle fractures compared with the absence of third molar, and the fractures are most likely to occur in teens and those in their twenties. This is of clinical interest because this age is most likely to have unerupted third molar. , Mandibular angle fractures follow a pattern common to many injuries and this depends on multiple factors including direction, amount of force, presence of soft tissue bulk, and biomechanical characteristics of the mandible such as bone density, mass, or anatomic structures creating weak areas. , The present study was designed with the following aims:
- To assess the relationship between the presence and position of mandibular third molars and mandibular angle fractures, and.
- To advocate prophylactic extraction of third molars as prevention against mandibular angle fracture.
| Materials and Methods|| |
For this radiographic study, the mandibular angle fracture cases reporting to the Department of Oral Medicine and Radiology were selected.
The sample size consisted of 50 mandibular angle fracture cases with or without the presence of mandibular third molar, inclusive of both the genders. After an informed consent was obtained, a detailed case history was recorded with complete clinical examination and orthopantomograph (OPG) was advised. The mandibular angle fracture was assessed by taking OPG following strict radiation protection protocol using the Kodak 8000C digital panoramic and cephalometric system with the following parameters: 73 kVp, 12 mA, and 13.9 s. Patients of both genders and age 18 years and above were included in this study with mandibular angle fractures associated with or without the presence of mandibular third molar. Those of age below 18 years and patients with active lesions like cyst and tumors, developmental disturbances, pathological fractures, iatrogenic fractures, or edentulous mandibular angle fractures were excluded from this study.
Determination of angle fracture
The angle fracture was considered when the radiolucent line appeared posterior to the second molar and was located at any point on the curve formed by the junction of the horizontal and the posterior border of the ascending ramus of the mandible (Kelly and Harrigan, 1975). The captured image was traced and assessed for the presence or absence of mandibular angle fracture and to find the position and angulation of the mandibular third molar by using Windows Trophy DICOM and Master View 3 software [Figure 1] and [Figure 2]. The Pell and Gregory classification  (Monaco et al., 2004) was followed to classify the ramus and occlusal position of the third molars, and Winter's classification  (Quek et al., 2003) was followed to classify the angulation of mandibular third molars. The obtained data was subjected to statistical analysis using Z-test for proportions.
| Results|| |
In the present study, we observed angle fracture in the age group ranging from 18 to 55 years and the mean age of the patients was 29.6 years. The study sample consisted of 38 (76%) males and 12 (24%) females. Mandibular angle fractures were observed more on the left side [28 (56%)] than on the right. The most likely cause of angle fracture [Table 1] was road traffic accident with 34 (68%) cases, followed by falls in 5 (10%) cases, assaults in 4 (8%) cases, sports in 2 (4%) cases, and others in 5 (10%) cases. In this study, we found 26 (52%) cases of isolated angle fracture and 24 (48%) cases were associated with other fracture sites of mandible, with 16 (32%) cases of parasymphysis fracture, 7 (14%) cases of symphysis fracture, 5 (10%) cases of condylar fracture, and 1 (2%) case of coronoid fracture [Table 1]. It was observed that mandibular third molars were involved in 45 (90%) cases of angle fracture and were absent in 5 (10%) cases [Table 2] and [Figure 3]. In the sample of 45 cases, we observed 33 (73%) cases of angle fractures associated with impacted mandibular third molar and were erupted in 12 (27%) cases [Table 2] and [Figure 3]. Following was the status of impacted mandibular third molar in relation to angle fracture:
|Table 1: Distribution of gender, cause of injury, side, and associated fracture in mandibular angle fracture cases|
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|Table 2: Distribution of mandibular third molar in mandibular angle fracture|
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|Figure 3: Presence or absence of mandibular third molar in angle fracture and distribution of mandibular third molar in angle fracture|
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- Distribution of sample according to the type of inclination (Winter's classification) [Table 2] and [Figure 4].
In the present study, mesioangular impactions were more with 13 (40%) cases, which was statistically significant (P < 0.05), followed by vertical impaction in 10 (30%) cases, horizontal impaction in 7 (21%) cases, and distoangular impaction in 3 (9%) cases.
- Distribution of sample according to the horizontal position of mandibular third molar (Pell and Gregory's classification) [Table 2] and [Figure 5].
- We found 14 (43%) cases of class II, 12 (36%) cases of class I, and 7 (21%) cases of class III impacted teeth, which were not statistically significant.
- Distribution of sample according to the vertical position of mandibular third molar (Pell and Gregory's classification) [Table 2] and [Figure 6].
- With respect to vertical position, position A was seen in 20 (61%) cases which was highly significant (P < 0.001), position B in 8 (24%) cases, and position C in 5 (15%) cases of angle fracture.
- Relationship between status of mandibular third molar in horizontal and vertical positions and angle fracture [Table 2] and [Figure 7].
|Figure 7: Pell and Gregory's classifi cation — both horizontal and vertical|
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- We observed Class IA in 11 (34%) cases, IIA in 8 (24%) cases, IIB in 5 (15%) cases, IIIC in 4 (12%) cases, IIIB in 2 (6%) cases, IIIA in 1 (3%) case, IB in 1 (3%) case, IIC in 1 (3%) case, and IC in 0 (0%) case of mandibular angle fracture.
| Discussion|| |
Fractures of the facial skeleton are one of the most common components of multiple trauma resulting from motor vehicle crashes, industrial accidents, sports, and assaults.  Fracture of the mandible occurs more frequently than any other fracture of the facial skeleton. This is due to its relatively prominent anatomical position and also their exposure to the external environment. Mandibular fracture patterns depend on multiple factors, including direction and amount of force, presence of soft tissue bulk, and biomechanical characteristics of the mandible such as bone density and mass or anatomic structures and presence or absence of tooth, thus creating weak areas. Thus, the angle of the mandible is an area of lowered resistance to fracture.  In mandible, the angle is the most frequent site when only one fracture is present. 
Teeth in mandible and maxilla are the most important anatomical factor which makes fractures involving these bones entirely different from other fractures elsewhere.  The mandibular third molars are the most frequently impacted teeth seen, which may be either complete or partial.  When the impacted third molar is present, by virtue of it occupying space, there is a reduced cross-sectional area of the angle of mandible. This results in an area of weakness facilitating the occurrence of fracture following minor trauma. When third molar is absent, the resistance of mandibular angle increases causing the force to be transmitted to a more fragile region, namely, the condyle. 
In the present study, the mandibular angle fracture was observed in the age group ranging from 19 to 55 years and the mean age was 29.6 years. The present study result was consistent with the results of the study conducted by Olikarinen et al. and Sakr et al. who reported that a peak incidence of angle fracture was observed at 20-29 years, , which probably is attributed to the presence of relatively high incidence of unerupted third molars, and also, this age group may probably have a tendency to be involved in violent conduct making them more susceptible to trauma.
In the present study, the study sample consisted of 38 males (76%) and 12 females (24%). This finding was consistent with the finding of the study conducted by Dongas et al. who observed increased incidence of angle fracture in males than females.  The greater predisposition of males is probably due to the fact that they are more exposed to the risk factors for facial trauma as they are involved in violent conduct, physical aggression, participate in contact sport, and drive recklessly, making them more prone to angle fracture.
Causes of injury
In our study, road traffic accidents seemed to be the most likely cause for angle fracture [34 (68%) cases] when compared to assaults [4 (8%)] and falls [6 (12%)]. This was in agreement with the study conducted by Ugboko et al. who observed that road traffic accidents were the main cause of mandibular angle fractures.  This is attributed to multiple reasons like inadequate road safety awareness, violation of the speed limit, use of alcohol or other intoxicating agents, participation in sports, behavioral disorders, and socio-cultural insufficiencies.
Relationship between the side and angle fracture
We found 28 (56%) cases of mandibular angle fracture on the left side as compared to 22 (44%) on the right side. This was in agreement with the study finding of Inaoka et al., where they proved left side had more angle fractures than the right side. However, the side did not present a significant relationship with angle fracture.  The site of impact is usually restricted to the side of fall. If the impact is of a high force or concentrated over a large area, then a direct fracture at the point of application will occur. If the impact is of a low force or distributed over a larger area, the stress-strain will transfer to the contralateral side, causing an indirect fracture.  In case of altercations, considering the predominance of the right-handed people in the society, when the victim is facing the opposite direction, the site of fracture is related to the side of impact.
Angle fracture associated with other fracture sites of mandible
In this study, 24 (48%) cases were associated with other fracture sites of the mandible, with 16 (32%) cases of parasymphysis fracture, 7 (14%) cases of symphysis fracture, 5 (10%) cases of condylar fracture, and 1 (2%) case of coronoid fracture. This was in agreement with the study conducted by Zhu et al. who proposed that location, site, direction, severity of force, and impact may influence the site of fracture.  Injury mechanism is also an important factor in determining other associated mandibular fractures. The severity of injury was the primary factor resulting in multiple fractures and was not influenced by the presence or absence of mandibular third molar. In this study, we found 5 (10%) condylar fractures along with angle fracture (3 cases of unerupted tooth and 2 cases with absence of tooth). This finding was consistent with the study conducted by Inaoka et al. When the third molar is erupted or absent, the resistance of the mandibular angle increases causing the force to be transmitted to a more fragile region, namely, the condyle. This could be due to intrinsic weakness of the condyle.
Isolated angle fracture
In this study, 26 (52%) cases had isolated mandibular angle fracture. The presence of third molar (erupted or impacted) increases the risk of angle fractures. The bone space occupied by the tooth makes the mandibular angle more fragile. As there is a change in the direction of grain pattern in the angle of mandible, release of stress secondary to a primary force elsewhere compounded by the presence of unerupted third molars makes it vulnerable for the fracture to occur in this region.
Presence/absence of mandibular third molar in angle fracture
In the total sample, mandibular third molars were involved in 45 (90%) cases, among which 33 (73%) cases had impacted third molar and in 12 (27%) cases, it was erupted. This finding was in concordance with Amaratunga et al. who implicated mandibular third molars as a risk factor and showed the higher risk of angle fractures with incompletely erupted mandibular third molars.  Lack of space in the arches is the common factor resulting in inadequate space to accommodate the erupting teeth due to decrease in jaw size, which is probably the result of both genetic and environmental factors. The reason for this increased incidence of fracture was that the impacted tooth within the angle region acts as a predisposing factor by virtue of occupying the bone space and lowering the resistance of mandible to fracture. The third molar was absent in 5 (10%) cases of mandibular angle fracture. The other reason could be that change in the direction of muscle pull by the pterygomasseteric sling and suprahyoid muscles causes strain at the angle region in case of sudden spasm of muscles as in case of trauma. This increase in strain at the angle during trauma would contribute to the risk of fracture at the angle.
Distribution of type of third molar impaction in the sample (Winter's classification)
We observed mesioangular impactions in 13 (40%) cases (P < 0.005), followed by vertical 10 (30%), horizontal 7 (21%), and distoangular impaction in 3 (9%) cases. This was in agreement with the study conducted by Fuselier et al. and Thangavelu et al. who proved that mesioangular impactions were the most commonly associated with angle fracture. , As the root of mesioangular impacted third molar is directed toward the angle of mandible, stress is concentrated around the root apex, which may act as a wedge splitting the mandibular angle, by which the injury forces are redirected toward the mandibular angle, and decreases the amount of bone by more than 20%, which increases the risk of angle fracture. Mandibular angle fractures observed along with other impaction positions of third molars in decreasing order were: Vertical, horizontal, and distoangular. However, some cases were observed in superficial position and some were positioned deep. This was in support with the hypothesis proposed by Meisami et al. who proved that the superficially positioned impacted third molar could increase the risk of angle fracture.  When the tooth is superficially impacted, it breaks the integrity of external oblique line, creating a fragile point in the mandible. This, in turn, weakens the mandible in the angle region, making it more prone to fracture. Amaratunga et al. observed impacted teeth to be positioned deep.  When the impacted tooth is deeply placed in the angle region, it acts as a predisposing factor for its weakness, thus lowering the resistance of mandible to fracture, by virtue of occupying bone space. The deeper localization would increase the risk by reducing the height of mandible at the angle region to less than 19 mm, which favors angle fracture.
Distribution of position of third molar impaction in the sample (Pell and Gregory's classification)
According to vertical position
In the present study, position A was seen in 20 (61%) cases (P < 0.001), position B in 8 (24%) cases, and position C in 5 (15%) cases. The findings of the present study were consistent with the findings of the study conducted by Elavenil et al. who confirmed that the most common type of impaction associated with angle fracture was class I, position A.  This may be explained by the fact that in mandibles with partially impacted/erupted teeth, the continuity of the external oblique ridge is disrupted, producing a point of weakness in the mandible, making it susceptible to fracture. In our study, the observed results were not significant in relation to positions B and C compared to position A. This was in agreement with the findings of Lee and Dodson, who showed that mandibles with the most deeply placed third molar had a 50% decrease in angle fracture risk compared with mandibular third molars in class IA, and there was no difference regarding the position in relation to the ramus.  The hypothesis states that deeper impacted mandibular third molar influences the risk of angle fractures by occupying osseous space and, thereby, weakening the angle region.
According to horizontal position
We found 14 (43%) cases of class II, 12 (36%) cases of class I, and 7 (21%) cases of class III impacted tooth in mandibular angle fracture cases. However, it was not statistically significant. These findings were consistent with the study conducted by Thangavelu et al. who observed that the largest percentage of angle fracture cases corresponded to class II position in angle fracture.  This could be due to the reduction in height of mandibular angle region by occupying the osseous space, making it susceptible to fracture.
Considering both the horizontal and vertical positions
We observed class IA in 11 (34%) cases, IIA in 8 (24%) cases, IIB in 5 (15%) cases, IIIB in 2 (6%) cases, IIIC in 4 (12%) cases, IIIA in 1 (3%) case, IB in 1 (3%) case, IIC in 1 (3%) case, and IC in 0 (0%) case of mandibular angle fracture. The present study showed increased risk of angle fracture with mandibular third molars in class I position A. This finding was consistent with the study of Lee and Dodson. 
| Conclusion|| |
In the total sample, mandibular third molar was present in 90% of cases with angle fracture; of these, 73% of the teeth were impacted. The increased incidence of mandibular angle fracture was observed in position A, class II, and mesioangular impaction of third molars. This study concludes that there is a direct relationship between the presence of mandibular third molar and the status of impacted third molars with increased risk of mandibular angle fracture. Knowledge of such a result could be helpful for the clinicians during clinical and radiographic evaluation and prophylactic removal of the third molar to prevent mandibular angle fracture. We suggest prophylactic removal of mandibular third molar to reduce the risk of mandibular angle fracture in high-risk groups and to prevent future complications. However, we recommend studies with a larger sample size using other recent imaging modalities. Biomechanical studies may be necessary in future to further clarify the risk of mandibular angle fracture depending on the various impact areas, direction and amount of the forces applied, in addition to the presence of impacted mandibular third molars.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
[Table 1], [Table 2]