This study investigated the reliability and accuracy of panoramic radiograph diagnoses of the periodontal state of mandibular molars, particularly regarding the diagnosis of furcation area periodontal defects, treatment planning, and prognosis prediction. This study examined a total of 110 teeth belonging to 33 subjects (19 male, 14 female) presenting with incipient to moderate periodontitis 4-7mm pocket depth. The alveolar bone level, length and width of the root trunk, and root separation angle were measured using the panoramic radiograph and compared to the results taken directly by retracting a full-thickness flap.

The results of the study are as follows:

1. Data regarding the alveolar bone level of the mandibular first molar showed that the directly taken surgical measurements resulted in 5.1±0.9mm that was slightly deeper than the corresponding panoramic measurement resulted in 4.8±0.8mm, but these differences were statistically insignificant (p>0.05).

2. The data of the directly taken surgical measurement of the mandibular second molar (5.1±1.1mm) was slightly deeper than the corresponding panoramic measurement (4.7±1.2mm), but these differences were statistically insignificant (p>0.05).

3. The measured values of the length and width of the mandibular first molar root trunks were determined to be 4.1±0.6mm and 7.3±0.9mm, respectively, while the values of the mandibular second molar root trunks were determined to be 4.6±1.3mm and 7.6±0.9mm respectively. The differences between these values were found to be statistically significant (p<0.01).

4. The measured values of the root separation angle showed that the mandibular first molars averaged 34.5±4.4°, while the mandibular second molars averaged 23.0±10.0°. The differences between these values were found to be statistically significant (p<0.01).

The results of the study show that when directly taken surgical measurements of periodontal defect depth are compared to depths indirectly measured using standard panoramic radiograph, the values are slightly deeper, but that these values are statistically insignificant. These results imply that panoramic radiograph is a reliable and effective means of making clinical diagnosis of incipient to moderate periodontitis.