Prevalence of Impacted Third Molars in AZ-Zulfi Region of Saudi Arabia: A Cross-sectional Study

INTRODUCTION:

The functional and topographical position of the third molar had made the prevalence of these teeth more variable and significant when compared to other teeth. Various theories had been put forward to explain the nature of eruption and prevalence of impacted third molar, but none of the theories hold good with all kind of impaction. Third molars were more commonly associated with the development of pathological cyst, TMJ disorders, cheek bite, etc. and hence the prevalence studies on the third molar in the specific region suggest the need for the specific dental care and needs of that region. The erupting pathway and position of the third molar can be related not only to the ethnicity of the population but also to the masticatory efficiency, and hereditary influences(1).

Impacted teeth had been defined as a tooth that doesn’t reach the anatomical position because of insufficient space, bony interference, or any trauma leading to deviation in the path of the eruption(2). In Saudi Arabia, recently more studies have been done on the impacted third molar prevalence, because of its clinical and functional significance. However, there are no such studies found in the literature specific to the Az Zulfi region of Saudi Arabia. The primary objective of this study was to assess the prevalence of impacted third molars and also to evaluate any associated pathology with the impacted third molar among the patients attending the dental clinic, College of Dentistry, Majmaah University in Al-Zulfi region, Kingdom of Saudi Arabia,

MATERIALS AND METHODS:

This cross-sectional retrospective radiographic study was done in the clinics of the College of Dentistry, Majmaah University after getting approval from the Deanship of Scientific Research with project number HA-01-R-088. A total of around 1695 orthopantomograms (OPG) of the patients who were reported to the Maxillofacial Department of College of dentistry, Majmaah University from December 2018 and December 2019 were evaluated based on the classifications of Pell & Gregory and Winter. Only those records with panoramic radiographs were selected by simple random sampling method. The medical records of patients who did not have panoramic radiographs and those who did not exhibit complete root formation of the third molars were considered not eligible for the study. The two experts in dental radiology with more than fifteen years of experience were given the third molar characteristics evaluation form (TMCEF) to evaluate all the records included in the study. (Appendix 1)

The evaluation criteria for typing the impaction in the present study were Pell and Gregory classification (3) and Winter’s Classification (4),(5). The earlier classification was based on the occlusal plane level as A, B, C, where the third molar occlusal plane was at the same level or between the occlusal surface and the cementoenamel junction of the second molar or the occlusal surface of the third molar was apical to the cementoenamel junction of the second molar respectively. Based on the space available between the posterior part of the second molar and the anterior border of the ramus, the impaction can be typed as Class I (third molar tooth present in front of the ramus), Class II (ramus have partially embedded teeth) & Class III (fully embedded in the ramus).

Winter’s classification of impaction is based on the angle formed by the longitudinal axis of the impacted third molar with the second molar. They are classified as vertical impaction (10° to -10°), Mesioangular impaction (11° to 79°), Horizontal impaction (80° to 100°), Distoangular impaction (-11° to -79°), other categories (111° to -80°), Buccolingual impaction ( if in buccolingual direction).

For this study, the proposed null hypothesis was that there exists no difference in the third molar impactions types and the related features (age group, vertical position to the second molar, mandibular canal, and maxillary sinus) in Al Zulfi in comparison to other studies from different locations of the world. The collected data were statistically analyzed using SPSS version 21(SPSS Inc; Chicago, IL, USA). The prevalence of the third molar impactions and its type, age predilection, and root abnormalities, and its relation to inferior alveolar nerve canal was assessed by percentage and frequency.

RESULTS:

One thousand six hundred and ninety-five (1695) Orthopantomograms (OPG) of patients ranging in age from 18 to 83 years were evaluated to determine the prevalence of impacted third molars in their population.

Among 1695 OPG studied 240 OPGs showed a minimum of one impacted third molar impacted. Among the gender, males(15.6%) showed more impacted teeth prevalence than females(3.1%) (Table 1.A). The impacted mandibular molar prevalence (780, 23%) was more when compared to that of the maxilla (486, 14.3%). The mandible shows more prevalence of mesioangular impaction (50.44%) and in the maxilla, it was vertical impaction (49.39%). The left side of the mandible (23.9%) showed more impaction than the right side (22.1%). But in the maxilla, there is no great difference between the right (14.5%) and left side (14.2%) (Table 1.B).

There was no significant difference in the status of the molar impaction according to the age of the group (upper left P<0.08, lower right P<0.65, lower left P<0.36) except the upper right side status of molar (P<0.02)(Table: 2.A,2.B,2.C,2.D) and hence the null hypothesis was rejected as there was a difference in the prevalence of impacted teeth in upper right side impacted teeth. The status of the right side molar influences the status of the left side molar (P<0.00) (Table 3.A, 3.B).

The prevalence of impacted third molars according to level of eruption shows that Position B (45.95%) in the mandible and Position C (59.83%)in the maxilla were more common

(Table 1.C).

The order of occurrence of the level of impaction A, B, C types was analyzed and was found to be C>B>A in the maxilla, and in mandible, it was B>A>C. The Class II (51.09%) pattern is found to be more common than the other two classes(Table 1.D). The less common type of impaction found in the maxilla were horizontal and buccolingual types, whereas in mandible the less commonly found impaction was the buccolingual type (Table 1.B). More than 66% of maxillary impactions had close approximation to the floor of the maxillary sinus on both sides (Table 1.E). Of the impactions, 187 had some pathology associated with the impacted tooth (Table 4) and dental caries were found to more common among all the other pathologies.

DISCUSSION:

A large number of patients visit dentists seeking treatment for tooth impaction as it is a more common clinical finding in day-to-day practice. The early detection of the impaction and necessary intervention plays an important role to prevent the various harmful consequences of the impacted teeth. Among the radiographic methods available, OPG is commonly preferred to assess the impacted tooth in detail including their angulations, amount of bone covered, and their depth of impaction within the bone, their association with the adjacent normal anatomic structures like maxillary sinus and the mandibular canal and the presence of pathologies associated with them.

In the AZ-Zulfi Region of Saudi Arabia, mesioangular impacted mandibular molar and vertically impacted maxillary molar were found to be the most common among all the other angulations (Table 2). This result was similar to the study conducted by Syed KB (6), Hassan AH (7), Hashemipour MA et al (4). A study conducted by Kumar Pillai A (8) showed vertical impaction most common in both maxilla and mandible in contrary to this study which had found that the mesioangular type was more common in mandible whereas the vertical type more common in maxilla signifying the region-specific nature of the type of impacted teeth. The maxillary third molar tooth bud normally develops and erupts in the maxillary tuberosity region in the vertical pattern favoring the vertical type of impaction. If the maxillary growth is inadequate, the maxillary third molar gets impacted against the second upper molar (9). The proximity of 66% impacted maxillary third molar to the floor of maxillary sinus had suggested taking proper surgical care and precaution on attempting the removal of those teeth.

In the Al-Zulfi Region of Saudi Arabia, the prevalence of the impacted teeth was more in mandible which was similar to the results of the study conducted by Hassan AH (7), Hashemipour MA et al (4), Kumar Pillai A (8), and Kamran Bokhari Syed (6).

Among our study group, the most common pathology that was seen in association with the impacted tooth was dental caries (75.94%). This result was like the results of the study by Al-Khateeb TH (10). The second commonly encountered problem was the close association with the inferior alveolar canal. Injury to the Inferior alveolar nerve during impacted third molar removal had been more prevalent (11),(12). So, all possible care should be taken to prevent any damage to the nerve in all such cases (8.56%). The other problems encountered are caries involving the pulp with or without periapical pathology and pericoronitis like problems. The study results had rejected the proposed null hypothesis as there was a statistically significant difference in the type of impacted teeth and the associated features like age, vertical position to the second molar, mandibular canal, and maxillary sinus position.

CONCLUSION:

Until now there is no prevalence study done in the region of Az Zulfi, Riyadh Province, Kingdom of Saudi Arabia regarding the third molar impaction status. Understanding the prevalence of impaction among our population helps in the deeper understanding of the incidence of different types of impaction based on different classifications and their association with the pathologies. Methodical and systematic evaluation of each case in the right way using the radiograph helps in providing the necessary proper intervention when required on a case-by-case basis in the specific region.

References

1. Alling C, Alling R. Indications for management of impacted teeth. Impacted teeth. 1993:46-64.

2. Archer WH. Oral surgery; a step-by-step atlas of operative techniques. Philadelphia: Saunders; 1961.

3. Pell GJ. Impacted mandibular third molars: classification and modified techniques for removal. Dent Digest. 1933;39:330-8.

4. Hashemipour MA, Tahmasbi-Arashlow M, Fahimi-Hanzaei F. Incidence of impacted mandibular and maxillary third molars: a radiographic study in a Southeast Iran population. Med Oral Patol Oral Cir Bucal. 2013;18(1):e140-5.

5. Alfergani SM, Latif K, Alanazi YM. A pattern of impacted mandibular third molars in a Saudi population. Pakistan Oral & Dental Journal. 2017;37(3):407-10.

6. Syed KB, Zaheer KB, Ibrahim M, Bagi MA, Assiri MA. Prevalence of impacted molar teeth among the Saudi population in the Asir region, Saudi Arabia–a retrospective study of 3 years. Journal of international oral health: JIOH. 2013;5(1):43.

7. Hassan AH. The pattern of third molar impaction in a Saudi population. Clin Cosmet Investig Dent. 2010;2:109-13.

8. Pillai AK, Thomas S, Paul G, Singh SK, Moghe S. Incidence of impacted third molars: A radiographic study in People's Hospital, Bhopal, India. Journal of oral biology and craniofacial research. 2014;4(2):76-81.

9. Olasoji HO, Odusanya SA. Comparative study of third molar impaction in rural and urban areas of South-Western Nigeria. Odontostomatol Trop. 2000;23(90):25-8.

10. Al-Khateeb TH, Bataineh AB. Pathology associated with impacted mandibular third molars in a group of Jordanians. J Oral Maxillofac Surg. 2006;64(11):1598-602.

11. Rood JP, Nooraldeen Shehab BAA. The radiological prediction of inferior alveolar nerve injury during third molar surgery. British Journal of Oral and Maxillofacial Surgery. 1990;28(1):20-5.

12. Hillerup S. Iatrogenic injury to oral branches of the trigeminal nerve: records of 449 cases. Clin Oral Investig. 2007;11(2):133-42.