Title: Evaluation of vertical measurements of molar teeth regions on panoramic radiographs obtained by dry skull by using different positions
Introduction: Panoramic radiography is used in dentistry for more than half a century. It is used for scanning the jaws and teeth before orthodontic treatment, maxillofacial surgery and also implants surgery. Having the ability to observe both jaws and adjacent structures at the same time, showing the large lesions and all the teeth in one image are some advantages of panoramic radiographs compared to intraoral radiographs. However, creating the magnification is the most important disadvantage. Magnification ratios ranging from 10% to 30% have been reported, depending on the positioning of the jaws.
In this study, we aimed to investigate the effect of panoramic x-ray on the alveolar bone for each molar tooth separately and the magnifications in different levels of this bone (three levels were used) with different head positions. In this respect, it is aimed to provide more efficient use of panoramic x-ray and reduce unnecessary tomography shots.
Methods and Materials: In the study, three spherical metal balls (diameter: 3.15mm) were placed in each of the 28 teeth regions of the human dry cranium model. The three metal balls were placed equal spacing, one of which was on occlusal, the other one was on middle triple, and the last one was on apical region. Being used different angles and positions 15 panoramic images were obtained. The positions were determined as horizontal (X: right +, left -), anteroposterior( Y: anterior +, posterior -) and right-left rotation (Z: right+, left -). The images were then be evaluated by an observer by using computer program (image J version 1.4). The obtained vertical dimension measurements were divided by the actual ball diameter to calculate the magnification factors and 312 measurements were subjected to statistical processing (Statistical Programme of Social Sciences SSPS).
Results: For the analysis of data Kolmogorov-Smirnov test for normality and Levene test for homogeneity of variance were performed. Then, One Way ANOVA test was performed for statistical analysis. For all molar teeth, differences of magnification factors between the three bone levels were not statistically significant (p>0,05). The differences between magnification factors are statistically significant in only maxillary molar regions on X=+5,Y=0,Z=0 and X=+5,Y= 0,Z=+5 positions.(p <0.05).
Conclusion: With the increase of implantation in the last years in dentistry, the number of cone beam computed tomography also increased. Although tomography has many advantages, patients are exposed to more radiation than intraoral and extra oral direct radiography techniques. We think that a patient with a complicated jaw and mouth structure or having multiple missing teeth may require a preoperative CBCT image before surgery, but panoramic radiographs is adequate in a patient with fewer missing teeth or a good bone level. If the magnification factor is known, even small positioning errors can be overcome and the vertical dimension can be calculated close to the real value.