Evaluation of the appropriate angles for periapical intraoral radiographic images using the bisecting angle technique based on different age groups in Iranian population

Abstract

Abstract Background/Aim: Intraoral periapical radiography is an important tool in dentistry. There are two techniques for obtaining intraoral periapical images: parallel method and bisecting angle. The parallel method is a better method in terms of repeatability and lack of distortion, but many evidences show that the most widely used method is the bisecting angle technique. There is evidence that dentists often have difficulty taking periapical radiographs. The most common problem reported is related to incorrect angulation and positioning of the X-ray cone, which leads to changes in the length of the image of the teeth and loss of apical areas in the radiograph. Studies have been conducted in different regions such as North America, India and Brazil to review and provide angulation guidelines for periapical bisector images. In addition, very specific studies have also investigated the effect of age and jaw growth rate on the angulation of periapical images. However, no study has been done so far in Iran and West Asian countries to provide guidelines for angulation. Also, the mentioned studies have limited sample size, different studied race and sometimes controversial methodologies. According to the previous explanations, the widespread use of this technique requires the existence of specific recipes for different races and ages. The present study will be done to solve this problem and provide imaging guide. Methods: In this cross-sectional study, 240 periapical radiographs will be collected using bisecting angle technique from patients referred to Tabriz dental faculty. Patients will be divided into 6 to 12, 13 to 18 and over 18 age groups. The radiographs of each age group will be divided specifically for the existing dental areas. (incisors, canines, premolars, molars). In this way, for each of the age groups of 6 to 12, 13 to 18 and over 18 years, the areas of incisors, canines, premolars, and molars will be examined. Radiographs will be taken by an experienced and trained radiology technician. Two maxillofacial radiologists will supervise the compliance of the operation with the established standards, such as the parallelism of the occlusal plane with the horizontal axis and the accuracy of the horizontal and vertical angles of the X-ray tube. For each imaging, the angle used and the tooth area will be recorded in the attached checklist. In the next step, two oral radiologists will separately check the images for correctness and the absence of radiographic errors. Disputed items will be deleted. SPSS software version 27 will be used to analyze the effect of the age factor on the appropriate angles of periapical images and compare the results with the declared data of other populations. Results: In the total of two jaws, the angular results of Iran compared to the three countries of North America, Brazil and India, were the closest to North America and the farthest from Brazil. India had a moderate level of dissimilarity compared to Iran. In the upper jaw, there is a significant difference in the average angle in the incisor, canine and molar teeth in age groups. Premolar teeth did not show a significant difference between the average angle in age groups. In the lower jaw, the incisor teeth showed a significant difference in the average angle in age groups. But in canine, premolar and molar teeth, there was no significant difference between the average angle in age groups. In statistically significant data, the amount of angle in the age group of 6-12 years is significantly higher than other age groups. Other age groups do not have a significant difference in the average angle. Conclusion: The angular results of Iran are most similar to those of North America compared to the three countries mentioned. The angle in the 6-12 year age group is significantly higher than other age groups. Also, in younger patients, an average increase of 5 to 10 degrees is required in the absolute value of the X-ray tube angle in the incisor and canine and molar regions of the maxilla and the incisor region of the mandible.