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The Prevalence of Impacted Third Molar, Impaction Angulation, and Impaction Depth in Patients Visiting Dental Clinics and Private Offices in Ghaemshahr, Iran, in 2016

Background & Aims : The present study aimed to determine the prevalence of impacted third molar as well as impaction angulation and depth. Materials & Methods : In this cross-sectional descriptive study, 261 panoramic radiographs belonging to patients visiting dental clinics and offices in Ghaemshahr, Iran, were evaluated and the presence of impacted wisdom teeth was examined. Moreover, the angulation of impacted teeth, impaction depth, and the relationship of the tooth to the mandibular ramus were recorded. The data were recorded, collected, and statistically analyzed in SPSS 22 using the non-parametric chi-square test. p <0.05 was considered significant. Results : Of the 261 patients entering the study, 52 (17.69%) had at least one impacted tooth. Of the total number of patients with impacted teeth, 31 were women (mean prevalence of 19.87% of the total population of women) and 21 were men (15.22% of the total population of men), showing no significant difference (p=0.29). In terms of impaction depth based on Pell and Gregory’ classification, Class C impaction depth was the most prevalent in the maxilla, while Class A was the most prevalent in the mandible. The most prevalent impaction in terms of angulation in relation to the second molar was vertical in the maxilla and vertical and mesioangular in the mandible. Conclusion : Based on results, the prevalence of impacted wisdom teeth in patients was 17.69%. This may not be a striking amount, but it is still of significance since the possible complications of impacted teeth are costly and problematic.


Introduction
An impacted tooth is one that has not erupted due to the presence of a physical barrier on its eruption path (1). All teeth can be impacted, but the most commonly involved teeth are mandibular third molars, maxillary canines, maxillary third molars, mandibular and maxillary second premolars, and maxillary central teeth (2). Tooth impaction is often diagnosed when a tooth has a long delay in eruption (3). The natural eruption of the third molar in terms of angulation is as follows: First, it grows from a horizontal position to a mesioangular one, then grows vertically, and eventually erupts (4).
Survival analysis for third molar eruption confirmed that severely angulated third molars have a significantly lower chance of eruption over time, compared to third molars with small angulations (5). A reason why molar teeth are impacted is failing to change from the mesioangular to the vertical position (6). Moreover, the presence of an impacted tooth part which is exposed to the oral cavity causes distal pockets in the second molar, followed by acute pericoronitis (8).
The term pericoronitis refers to the inflammation of gingiva around the crown of a partially erupted tooth which may be acute, sub-acute, or chronic. A partially erupted or impacted third molar is the most prevalent place for pericoronitis (9).
A relationship was observed between the presence of the unerupted third mandibular molar and mandibular fracture. The presence of the third molar reduces the bone's cross-section, leading to the further incidence of mandibular angle fracture. Therefore, the removal of the unerupted third molar reduces the risk of mandibular angle fracture (10)(11)(12)(13)(14)(15).
Due to its importance, tooth impaction is discussed in most branches of dentistry, including surgery, pediatrics, orthodontics, and prosthesis, so that an accurate and timely treatment plan would be adopted and correct therapeutic decisions would be made in order to prevent further complications such as periodontal problems, caries in the adjacent tooth, root resorption in the adjacent tooth, crowding, cysts, tumors (16)(17)(18), and idiopathic pains (19).
Considering the effects of an impacted tooth on treatment methods, complications, higher treatment costs which put a burden on patients as well as the healthcare system, and the lack of accurate statistics, the present study aimed to determine the prevalence of impacted third molar and impaction angulation and depth in patients visiting dental clinics and private offices in Ghaemshahr, 2016.

Materials & Methods:
In the present cross-sectional descriptive study, panoramic radiographs of patients visiting the dental clinics and private offices of Ghaemshahr in 2016 were utilized. An observer examined these panoramic radiographs and recorded the age and sex of patients.

Results
The total number of panoramic radiographs equaled 261, of which 156 belonged to women (53%) and 138 to men (47% The total number of impacted teeth was 86. Of this, 35 teeth belonged to the maxilla (40%) and 51 to the mandible (60%). Moreover, 47 teeth were on the left (55%) and 39 were on the right (45%) ( Table 2).

Conclusion
Based on results, the prevalence of impacted wisdom teeth in patients visiting dental clinics and private offices in Ghaemshahr in 2016 was 17.69%. This may not be of considerable value, but it is still of significance since the possible complications of impacted teeth are costly and problematic. Moreover, it must be kept in mind that the prevalence of impacted wisdom teeth was higher in the mandible. Therefore, this must be taken into consideration during treatments. Nevertheless, the difference between men and women was not significant, thus resolving concerns regarding the higher prevalence of impacted teeth in either sex.