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Table of Contents   
ORIGINAL RESEARCH  
Year : 2019  |  Volume : 30  |  Issue : 2  |  Page : 238-242
Prevalence of impacted third molars among orthodontic patients in different malocclusions


1 Department of Orthodontics and Dentofacial Orthopedics, Government College of Dentistry, Indore, Madhya Pradesh, India
2 Indian Agricultural Research Institute, Indore, Madhya Pradesh, India

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Date of Web Publication29-May-2019
 

   Abstract 

Objectives: The aim of this retrospective study was to investigate the prevalence and pattern of third molar impaction and missing third molars in patients over 18 years in different anteroposterior skeletal patterns among central Indian populations. Materials and Methods: The study reviewed 357 orthopantomograms of patients attending the Government College of Dentistry, Indore, Madhya Pradesh. Patients were evaluated to determine the prevalence of third molar impaction, angulation, and level of eruption in Class I, Class II, and Class III patients using Winter's classification to determine angulation of third molars and Pell and Gregory classification for level of impaction. Results: Out of 357 patients, 187 (52.3%) were present with at least one impacted teeth. The third molar impaction was most commonly present in Class II malocclusion (60.65%). Overall, the most common angulation of impaction in both genders was the mesioangular (39%), and the most common level of impaction in both arches was Level B. In Class I, Class II and Class III malocclusion vertical angulation was the most common finding in the maxillary arch and mesioangular angulation in the mandibular arch. No significant association was observed between different types of malocclusion and third molar impaction (P > 0.4648). Conclusion: This study found that almost half of the adult patients above 18 years had at least one impacted third molar. The anteroposterior relationship does not have any significant role for the third molar impaction.

Keywords: Anteroposterior relationship, impacted teeth, missing third molars, prevalence, third molar

How to cite this article:
Jain S, Debbarma S, Prasad S V. Prevalence of impacted third molars among orthodontic patients in different malocclusions. Indian J Dent Res 2019;30:238-42

How to cite this URL:
Jain S, Debbarma S, Prasad S V. Prevalence of impacted third molars among orthodontic patients in different malocclusions. Indian J Dent Res [serial online] 2019 [cited 2019 Aug 22];30:238-42. Available from: http://www.ijdr.in/text.asp?2019/30/2/238/259231

   Introduction Top


Teeth become impacted when they fail to erupt or develop in their proper functional location; third molar is the most common impaction that accounts for 98% of all impactions.[1] The frequency of third molar impaction varies substantially among different populations and was reported to range from 18% to 70%. This can be attributed to racial variation in the pattern of facial growth, jaw, and tooth size, which are crucial determinants of the eruption pattern.[2],[3],[4],[5],[6] Among all teeth, mandibular third molars are the most frequently impacted teeth.[7] The cause of third molar impaction is due to inadequate space in the mandible, which may lead to pericoronitis, dental caries, and cystic lesions.[8] Panoramic radiograph orthopantomogram (OPG) is considered the technique of choice for evaluation of the status of third molar impaction with regards to the angulation of impaction, level of impaction, and amount of covering bone. In addition, OPG is used to evaluate the relationship between third molars with inferior alveolar canal.[9] During the correction of the malocclusion, it is the duty of the orthodontist to correct all malalignments. As most orthodontic patients are in the growing age group, early evaluation of the third molar eruption status will benefit the patients' treatment outcome. According to Castella et al., the third molar impaction in the mandible was a predictable event both in extraction and nonextraction patients.[10] Agenesis of the third molar is also a common occurrence, but its frequency varies in different studies.[11],[12] The frequency of the third molar agenesis in decreasing order of occurrence is two, followed by one, three, and all the four third molars,[13] and in another study, it is referred to as one missing third molar followed by two, three, and all the four third molars.[14] Consideration of the mandibular third molar is important from orthodontic perspective because of lower anterior arch crowding, relapse in the lower anterior region, interference with uprighting of mandibular first and second molars during anchorage preparation, molar distalization, caries, and pericoronitis.[15],[16] In previous studies, certain radiographic predictors for the evaluation of lower third molar eruption were not thoroughly investigated with regard to different skeletal patterns and patient age.[17],[18],[19] The aim of this study is to determine the prevalence of third molar impaction among orthodontic patients and to determine the relationship between total number of impacted teeth, their angulation and level of impaction in relation to different anteroposterior skeletal patterns.


   Materials and Methods Top


This retrospective study was undertaken on a group of patients, who attended Government College of Dentistry, Indore (Madhya Pradesh), for the purpose of treatment in Orthodontics Department. A total of 357 OPGs and lateral cephalograms were selected from the record for evaluation, and the age range of patients was above 18 years since third molars have been found to erupt between the ages of 18 and 21 years. Out of 357 patients, 172 were male and 185 were female.

Teeth with bone pathology that causes malalignment in the occlusal plane, absence of adjacent second molars, incomplete patient records or patients with poor quality OPGs were excluded from the study. The data required for each patient was collected from their records retrospectively from the department data. As the study was retrospective radiographic study, informed consent could not be obtained from the patients. All OPGs were assessed for the following criteria: number of impacted third molars; missing, angular position of impaction; and level of eruption in relation to different malocclusions.

For this study, the impaction, level of impaction, and angulation of third molars were defined as follows. The third molar was considered impacted when it was not fully erupted to the assumed normal functional position in the occlusal plane. The angulation of the impacted third molar was recorded using Winter's classification with reference to the angle formed between the intersected longitudinal axes of the second and third molars.[4] According to Winter's classification, third molar is classified as follows:

  • Mesioangular angulation: When the long axis of the third molar bisects the long axis of the second molar at or above the occlusal plane
  • Distoangular angulation: When the long axis of the third molar tilts away from the long axis of the second molar
  • Horizontal angulation: When the long axis of the third molar bisects the long axis of the second molar at right angle
  • Vertical angulation: When the long axis of the third molar runs parallel to the long axis of the second molar.


Maxillary third molars were recorded as impacted when the lowest portion of the crown of an impacted maxillary third molar was below the occlusal plane of the second molar.[20]

The level of impaction was determined using the Pell and Gregory classification as follows:

  • Position A: If the highest portion of the impacted third molar was on a level with or above the occlusal plane
  • Position B: If the highest portion of the impacted third molar was below the occlusal plane but above the cervical line of the second molar
  • Position C: If the highest portion of the impacted third molar was below the cervical line of the second molar.[9]



   Results Top


Out of 357 patients, 187 (52.3%) had at least one impacted third molar; among them, the distribution in male patients was 91 (48%) and in female patients was 96 (51%). Totally, 402 impacted teeth were found among 357 patients and 92 missing teeth.

[Table 1] shows the distribution of the patients having impacted teeth among the included patients in different malocclusions. Out of 357 patients, the third molar impaction was present in 187 (52.38%) patients. Among studied population, the finding of malocclusion was 218 Class I, 122 Class II, and 17 Class III. The third molar impaction was most commonly present in Class II malocclusion (n = 74, 60.65%) followed by Class III malocclusion (n = 10, 58.82%) and Class I malocclusion (n = 103, 47.24%). The impacted third molar distribution in the mandibular and maxillary arch was compared in all classes of malocclusion by applying Chi-square test, and the result showed significant difference only in the Class II malocclusion. Chi-square test was applied to compare the distribution of impaction in Class I, Class II, and Class III malocclusion, but the result was not significant.
Table 1: Distribution of the impacted teeth among the included patients in different malocclusion and total impacted teeth distribution

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[Table 2] shows the occurrence of third molar angulations of impacted teeth in the maxillary and mandibular arches. Overall, the most common angulation was the mesioangular (155/402, 38.5%), followed by vertical (127/402, 31.5%), horizontal (72/402, 17.9%), and distoangular (48/402, 11.9%). The most common form of impaction in both the genders was the mesioangular impaction (38%). In the maxilla, χ2 = 9.80 and P < 0.05, which suggest that the distribution of angulations in between males and females is highly significant in maxillary arch, whereas in the mandible, it is not significantly different (χ2 = 6.7, P ≥ 0.05).
Table 2: Distributions of the third molar angulations of impacted teeth in male and female (n=402)

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[Table 3] shows the distribution of the total number of impacted third molar angulations in different malocclusions. The total number of impacted teeth found among 357 patients was 402 teeth; in the maxillary arch, it was 169 and 233 in the mandibular arch. Overall, in all the malocclusions, mesioangular angulation was the most common finding. In the maxillary arch in all the malocclusions (Class I, Class II, and Class III), the most common finding was the vertical angulation and distribution as in Class I, 25%, Class II, 21%; and Class III, 22%, and in the mandibular arch, mesioangular angulation was the most common finding in Class I, 27%; Class II, 34%; and Class III, 37%. This showed that the angulation of the impacted teeth does not depend on the anteroposterior relationship or malocclusion.
Table 3: Distribution of the total number of impacted third molar angulations in Class I, Class II, and Class III

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[Table 4] shows the distributions of the different level of impaction in different malocclusion. The most commonly found level of impaction in all the malocclusions was the Position B (226/402, 56.2%), followed by Position C (118/402, 29.3%) and Position A (58/402, 14.4%). The Level A was common in Class III malocclusion 22.2%, Level B in Class II malocclusion 59.1%, and Level C in Class I malocclusion 30.4%.
Table 4: Distribution of level of third molar impaction in Class I, Class II, and Class III

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[Table 5] shows the distribution of the third molar impaction by gender and the arches (maxilla and mandible). The prevalence of third molar impaction in the mandible was 58.2% (234/402) and in the maxilla was 41% (168/402); Chi-square test showed no statistically significant difference in both male and female participants. In the maxilla, females (100/168, 59.5%) were having more third molar impaction than males (68/168, 40.4%). In the mandibular arch also, females (140/234, 59.8%) showed more third molar impactions than males (94/234, 40%).
Table 5: Distributions of the third molar impaction by gender and the arches (maxilla and mandibular arch, n=402)

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   Discussion Top


This is the first study on Indian population which determines the relationship between different malocclusions (Class I, Class II, and Class III) and prevalence of impacted third molars. As racial variation, nature of diet, degree of use of masticatory apparatus, and genetic inheritance can affect the jaw size and tooth size, studies of prevalence and incidence of impacted third molars have been carried out on different population groups by various authors.[2],[3],[4],[5],[6],[7],[8],[9],[10] This study will help determine whether this is an emerging problem or due to influences of the population's ethnic background. For this study, patients were randomly selected to ensure that the study sample will represent whole Indian population. In our study, the prevalence of third molar impaction found was 52.38%, which is in agreement with Nanda[14] and Sandhu and Kaur[12] who noted 40%–68.9% in South Indian population. However, the prevalence found for this study is lower than that observed by Obiechina et al.,[21] which is 72.09% of the Nigerian population, 65.5% in the USA population noticed by Morris and Jerman,[22] and Grover and Lorton[23] observed 96.5% of the third molar impaction but significantly more than that of Scherstén et al.[24] who observed 33%, Hattab et al.[4] observed 28.2%, and Ma'aita[8] observed in Saudi Arabians population 40.5% and among Jordanians students 47.4%.

In this study, the impacted third molars were most commonly found in Class II malocclusion (60.65%), which is in agreement with Richardson.[17] In contrary, Abu Alhaija et al.[18] found third molar impaction more in Class III malocclusions.

In the current study, the most common number of impacted third molars per patient was one (32%), which is similar to Hashemipour et al. study.[25] However, two-third molar impaction was the most common finding by Quek et al.[6] In contrast, Ma'aita[8] reported that 40% of Jordanian patients had all the four third molars impacted. The most common number of impacted third molars in the present study by order of frequency was one tooth in 60 (32.9%), two teeth in 52 (28.5%), four teeth in 49 (26.9%), and three teeth in 21 (11.53%) patients. Overall, the mesioangular impaction was the most common type of angulation found in this study. However, when the angulation was observed separately in different malocclusions, then the vertical angulation was the most common in maxillary arch and mesioangular angulation in the mandibular arch. This is in agreement with many other studies where the frequency of mesioangular impaction ranged from 33.4%–62%.[3],[7],[11],[12],[13],[14] However, the current study's result differs from studies published by Reddy and Prasad[26] who found that vertical impaction was the most common type of third molar impaction.

An analysis of the level of impaction showed that Level B was the most common level of impaction (56.2%). This finding is more than the finding of 39% by Sandhu and Kaur[12] and 45.8% by Padhye et al.[2] but less than the study done by Quek et al.[6] who found 80%. In contrast, Level A was the most common level observed in third molar impaction by Hattab et al.[4] (58%) and Gupta et al.[7] (61.8%).


   Conclusion Top


  • This is the first retrospective radiographic study investigating the prevalence of third molar impaction in different malocclusions among central Indian population in adult patients aged above 18 years
  • The study showed high prevalence, and almost half of the population were having at least one impacted third molars in different types of malocclusions
  • Comparison between Class I, Class II, and Class III malocclusion did not showed any significant difference
  • Overall, the most common angulation found in all the malocclusions was mesioangular angulation
  • The distribution of the total impacted teeth in male and female participants was equally distributed, but the angulation distribution showed a significant difference between males and females in the maxillary arch.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Correspondence Address:
Dr. Sharmila Debbarma
Room No. 11, Department of Orthodontics and Dentofacial Orthopedics, Government College of Dentistry, Indore - 452 001, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_62_17

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