The effect of metal artifacts on the identification of vertical root fractures using different fields of view in cone-beam computed tomography

PURPOSE: The aim of this study was to investigate the effects of metal artifacts on the accurate diagnosis of root fractures using cone-beam computed tomography (CBCT) images with large and small/limited fields of view (FOVs). MATERIALS AND METHODS: Forty extracted molar and premolar teeth were collected. Access canals were made in all teeth using a rotary system. In half of the teeth, fractures were created by the application of mild pressure with a hammer. The teeth were then randomly put into a wax rim on an acryl base designed in the shape of a mandible. CBCT scans were obtained using a Newtom 5G system with FOVs of 18 cmx16 cm and 6 cmx6 cm. A metal pin was then placed into each tooth, and CBCT imaging was again performed using the same fields of view. All scans were evaluated by two oral and maxillofacial radiologists. The specificity, sensitivity, positive predictive value, negative predictive value, and likelihood ratios (positive and negative) were calculated. RESULTS: The maximum levels of sensitivity and specificity (100% and 100%, respectively) were observed in smallvolume CBCT scans of teeth without pins. The highest negative predictive value was found in the small-volume group without pins, whereas the positive predictive value was 100% in all groups except the large-volume group with pins. CONCLUSION: The specificity of CBCT decreased with the presence of a pin in the large-volume group, but not in the small-volume group.

A comparative study of cone-beam computed tomography and digital periapical radiography in detecting mandibular molars root perforations

PURPOSE: The aim of this in vitro study was to determine the sensitivity and specificity of cone-beam computed tomography (CBCT) and digital periapical radiography in the detection of mesial root perforations of mandibular molars. MATERIALS AND METHODS: In this in vitro study, 48 mandibular molars were divided into 4 groups. First, the mesial canals of all the 48 teeth were endodontically prepared. In 2 groups (24 teeth each), the roots were axially perforated in the mesiolingual canal 1-3 mm below the furcation region, penetrating the root surface ("root perforation"). Then, in one of these 2 groups, the mesial canals were filled with gutta-percha and AH26 sealer. Mesial canals in one of the other 2 groups without perforation (control groups) were filled with the same materials. The CBCT and periapical radiographs with 3 different angulations were evaluated by 2 oral and maxillofacial radiologists. The specificity and sensitivity of the two methods were calculated, and P<0.05 was considered significant. RESULTS: The sensitivity and specificity of CBCT scans in the detection of obturated root canal perforations were 79% and 96%, respectively, and in the case of three-angled periapical radiographs, they were 92% and 100%, respectively. In non-obturated root canals, the sensitivity and specificity of CBCT scans in perforation detection were 92% and 100%, respectively, and for three-angled periapical radiographs, they were 50% and 96%, respectively. CONCLUSION: For perforation detection in filled-root canals, periapical radiography with three different horizontal angulations would be trustworthy, but it is recommended that CBCT be used for perforation detection before obturating root canals.

Assessment of vertical root fracture using cone-beam computed tomography

PURPOSE: The aim of this study was to investigate the accuracy of cone-beam computed tomography (CBCT) in the diagnosis of vertical root fractures in a tooth with gutta-percha and prefabricated posts. MATERIALS AND METHODS: This study selected 96 extracted molar and premolar teeth of the mandible. These teeth were divided into six groups as follows: Groups A, B, and C consisted of teeth with vertical root fractures, and groups D, E, and F had teeth without vertical root fractures; groups A and D had teeth with gutta-percha and prefabricated posts; groups B and E had teeth with gutta-percha but without prefabricated posts, and groups C and F had teeth without gutta-percha or prefabricated posts. Then, the CBCT scans were obtained and examined by three oral and maxillofacial radiologists in order to determine the presence of vertical root fractures. The data were analyzed using IBM SPSS 20.0 (IBM Corp., Armonk, NY, USA). RESULTS: The kappa coefficient was 0.875+/-0.049. Groups A and D showed a sensitivity of 81% and a specificity of 100%; groups E and B, a sensitivity of 94% and a specificity of 100%; and groups C and F, a sensitivity of 88% and a specificity of 100%. CONCLUSION: The CBCT scans revealed a high accuracy in the diagnosis of vertical root fractures; the accuracy did not decrease in the presence of gutta-percha. The presence of prefabricated posts also had little effect on the accuracy of the system, which was, of course, not statistically significant.

Evaluation of panoramic radiography at showing width of the dental follicle

Considering probable incidence of pathological changes in the follicles of impacted teeth, this study is conducted to evaluate pericoronal radiolucency of impacted third molars. In this cross-sectional study, widths of follicular spaces of 201 impacted third molars were measured on panoramic radiographs. Under local anesthesia, the teeth along with the dental follicles were surgically removed. After routine procedure, they histopathological were examined. After evaluating 201 dental follicles it was observed that, 50.7% of cases [102 cases] showed pathological changes and all of them were dentigerous cysts. Incidence of cystic changes in the follicles of third molars of patients aged 21 years and above, is 1.465 times more than patients who were under 21 years old. Also in dental follicles of lower third molars, the incidence of pathological changes was 1.957 times more than maxilla. Cystic changes in the evaluation of follicular widths up to 1.5 mm, was observed in 48% of cases, up to 2 mm, in 73.5% of cases, up to 2.5 mm, in 87.2% of cases and up to 3 mm, in 92.1% of cases. It seems that occurrence of cystic changes in dental follicles increases with increase in age and width of follicular space. However, considering the high incidence of cystic changes in pericoronal radiolucency around the impacted third molars, this study supports the prophylactic removal of impacted third molars

Root-crown ratio in permanent dentition using panoramic radiography in a selected Iranian population

Statement of the Problem: Determining the crown-root ratio is crucial in many dental clinical decisions. There are no reliable data presented for Iranian population

Purpose: The aim of this study was to assess the root-crown ratio of permanent teeth with regards to the relationship of gender and jaw type using panoramic radiographs. The reliability of method was also assessed

Materials and Method: The crown and root lengths of teeth were measured by a digital caliper on panoramic radiographs of 185 individuals except for the third molars. A total of 1994 teeth was studied and 50.8% of the teeth belonged to males and 49.2% belonged to females. The modified Lind method was applied

Results: The highest mean root-crown ratios in both arches of both genders were obtained in the second premolars, followed by the first premolars and canines. In both genders, the lowest root-crown ratios were found in the maxillary central incisors. In male patients, the mean root-crown ratio was higher [p= 0.003] than that of females. Using Bland-Altman analysis, a non-significant difference of 0.006 [95% CI: -0.012-0.024] and 0.0002 [95% CI: -0.011-0.011] were found for intra-observer and inter-observer agreement, respectively

Conclusion: Assessment of the root-crown ratio in permanent dentition could be performed on panoramic radiographs with acceptable reproducibility in an Iranian Population. Considering observed differences, our findings suggest that for the accurate assessment, this ratio must be calculated for male and female patients and also for the upper and lower jaws, separately

Can the follicle-crown ratio of the impacted third molars be a reliable indicator of pathologic problem?

Statement of the Problem: The presence of impacted third molars in the jaws is a common finding in the routine dental examination of patients. Concerning the odontogenic components of the dental follicle, it can be the origin of different types of odontogenic cysts and tumors

Purpose: The aim of this study was to find feasible radiographic criteria to help differentiate between normal and pathological dental follicles

Materials and Method: 134 asymptomatic impacted third molars were recruited in this study. Then, based on the radiographic measurements, the ratio between the diameter of the dental follicle and the mesiodistal width of the tooth crown was calculated. After surgical removal of impacted third molars, the related dental follicles were evaluated histopathologically. Statistical analyses were performed by adopting chi-square test, t-test, receiver oprating characteristic [ROC] curve, and logistic regression using SPSS-19 software

Results: The mean ratio of the dental follicle's diameter to the mesiodistal width, in the normal and cystic follicle group was 1.18 +/- 0.07 and 1.18 +/- 0.08, respectively. There was no statistically significant difference between this ratio and the histopathological evaluation. Based on the logistic regression analysis, only the age >20 years and inflammation had predictive value in identifying cystic changes in dental follicle

Conclusion: According to the findings of the current study, the ratio of dental follicle diameter to the mesiodistal width of the teeth cannot not be employed as a diagnostic index to differentiate between normal and pathological dental follicle

[Radiographic evaluation of apical root resorption following fixed orthodontic treatment]

Apical root resorption is an adverse side effect of fixed orthodontic treatment which cannot be repaired. The aim of this study was to use panoramic radiographs to compare the root resorption before and after the orthodontic treatment with standard edgewise .018 appliance. The before and after treatment panoramic views of sixty-three patients needed fixed orthodontic treatment included 1520 teeth were categorized into 3 Grades [G0: without resorption, G1: mild resorption with blunt roots or 1/4 to 1/2 of root length. Relationship between root resorption and sex and treatment duration was analyzed with Mann-whitney and Spearman's correlation coefficient, respectively. The findings showed that 345 teeth were categorized as Grade 1. Grade 2 of root resorption was not found in this study. The highest amount of root resorption was recorded for the mandibular lateral incisor. In both gender, the root resorption of the mandible was more than that of the maxilla. The males showed significantly higher rate of resorption than the females [P<0.05]. Root resorption was not significantly related to the treatment duration and the side of the jaws [P>0.05]. The mandible and male patients showed higher amount of root resorption. In addition, root resorption was not related to the treatment duration and the side of the jaws

[Histopathologic evaluation of normal radiolucent space around impacted third molar]

The follicular tissue around impacted third molar has a potential to develop to different lesions. However, it is generally accepted that the absence of abnormal radiolucency indicates the presence of a normal follicle. The aim of this study was to histopathologically evaluate the normal pericoronal radiolucencies associated with impacted third molars. The follicular space of 104 third molars with normal follicular space [<2.5mm] in panoramic radiographs was measured. Under local anesthesia, tooth and its follicle were taken out by surgical procedure and after necessary steps, were histopathologically evaluated. Data were analyzed by fisher's exact test, chi-square and logestic regression [alpha=0.05]. Thirty eight cases [36.5%] of all follicles had been collected from male, and 63.5% [66 cases] from female patients. 92 follicles [88.5%] had been taken out of mandible and 12 follicles [11.5%] from maxilla. Of the specimens submitted, 41.3% [43 cases] showed cystic changes equivalent to that in dentigerous cysts. Cystic changes in dental follicles were significantly higher in patients over 20 years of age [P<0.0001]. No significant difference was detected between sex of patients and cystic changes in follicles [P>0.05]. Impacted third molars with normal pericoronal radiolucency more than 1.5 mm showed cystic changes in 63.3% of the cases. This study confirms the idea that the risk of cystic changes increases with age. Considering the high incidence of cystic changes in pericoronal radiolucencies associated with impacted third molars, this study suggests prophylactic removal of impacted third molar