PurposeThis study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption.Materials and MethodsThe records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption.ResultsThe periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket.ConclusionThese results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

There was no significant difference between intraoral film, a high-resolution complementary metal oxide semiconductor digital imaging system and CBCT in detecting vertical root fractures in mandibular single-rooted teeth.

Cone-beam computed tomography (CBCT) has been developed as a new imaging modality for dentists to diagnose various diseases and to determine treatment plan options. It can display the images in axial, sagittal, and coronal planes, as well as permitting three-dimensional (3D) image reconstruction. Therefore, CBCT is widely used in several dental applications.1 Recently, there have been studies on the accuracy in detection of caries using CBCT. 2-9 However, the effectiveness of CBCT in caries detection has been still equivocal. Akdeniz et al 2 found that limited cone beam computed tomography (LCBCT) was better to assess the depth of proximal caries than intra-oral digital imaging systems using storage phosphor plate sensors and film. The 3DX Accuitomo system (Mortita, Kyoto, Japan), one of the CBCT systems, was reported to show significantly higher sensitivity than 2D images in detecting proximal dentin caries. 4,5 For proximal enamel caries, Young et al 5 found that the 3DX Accuitomo was a superior imaging modality to intra-oral digital imaging systems using charge coupled device (CCD) sensors. Kayipmaz et al 7 stated that CBCT images could detect occlusal caries better than conventional films and storage phosphor plates, whereas no signifcant difference was found for proximal caries. Kamburoglu et al 9 found that CBCT images improved the detection of occlusal caries in deep enamel, superficial dentin, and ABSTRACTPurpose : The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. Materials and Methods : One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n= =60) and composite resin (n= =60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (A z ) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value⁄0.05).Results : The mean A z values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p= =0.007). For CBCT systems, the axial plane showed the greatest A z value. Conclusion : Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries. (Imaging Sci Dent 2011; 41 : 143-50)

PurposeTo perform a comparative analysis of the palatal bone thickness in Thai patients exhibiting class I malocclusion according to whether they exhibited a normal or open vertical skeletal configuration using cone-beam computed tomography (CBCT).Materials and MethodsThirty CBCT images of Thai orthodontic patients (15–30 years of age) exhibiting class I malocclusion with a normal or open vertical skeletal configuration were selected. Palatal bone thickness was measured in a 3.0-mm grid pattern on both the right and left sides. The palatal bone thickness of the normal-bite and open-bite groups was compared using the independent t-test. The level of significance was established at P<.05.ResultsThe palatal bone thickness in the normal-bite group ranged from 2.2±1.0 mm to 12.6±4.1 mm. The palatal bone thickness in the open-bite group ranged from 1.9±1.1 mm to 13.2±2.3 mm. The palatal bone thickness was lower at almost all sites in patients with open bite than in those with normal bite. Significant differences were found at almost all anteroposterior sites along the 3 most medial sections (3.0, 6.0, and 9.0 mm lateral to the midsagittal plane) (P<.05).ConclusionClass I malocclusion with open vertical skeletal configuration may affect palatal bone thickness, so the placement of temporary anchorage devices or miniscrew implants in the palatal area in such patients should be performed with caution.

PurposeThis study determined and compared the distances from the maxillary root apices of posterior teeth to the floor of the maxillary sinus, or maxillary sinus distances (MSDs), and the distances from the mandibular root apices of the posterior teeth to the mandibular canal, or mandibular canal distances (MCDs), in Thai subjects with skeletal open bite and skeletal normal bite.Materials and MethodsPretreatment cone-beam computed tomography (CBCT) images were obtained from 30 Thai orthodontic patients (15 patients with skeletal normal bite and 15 with skeletal open bite) whose ages ranged from 14 to 28 years. The CBCT images of the patients were processed and measured using the Romexis Viewer program. The MSDs and MCDs from the root apices of the maxillary and mandibular second premolar, first molar, and second molar to the maxillary sinus floor or the mandibular canal were measured perpendicularly to the occlusal plane. The Student t test was used for comparisons between the 2 groups.ResultsThe greatest mean MSDs were from the root apex of the second premolars in both groups, whereas the least mean MSDs were from the mesiobuccal root apex of the second molars. The greatest mean MCDs were from the mesial root apex of the first molars, whereas the least mean MCDs were from the distal root apex of the second molars.ConclusionThere were no differences in the mean MSDs or the mean MCDs between the skeletal normal bite group and the skeletal open bite group.