An anatomical study on locations of the mandibular foramen and the accessory mandibular foramen in the mandible and their clinical implication in a Thai population / 대한해부학회지

Mandibular foramen (MF) is a structure that inferior alveolar nerve and artery pass through itself which is found on the mandible. The objective of this research aims to locate MF among the Thai population including other MF characteristics. The sampling is conducted in the Thai population of the total number of 220 samples from the Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University. The MF anteroposterior and superoinferior localizations are similar in both sex which at Q3 of right anteroposterior, Q2 of left anteroposterior and Q2 of left and right superoinferior axis. Otherwise, the prevalence of accessory MF has in 68 samples which are 30.89%. The prevalence of unilateral single accessory MF is 20.45%, bilateral single accessory MF is 6.36%, unilateral double accessory MF is 2.27% and bilateral double accessory MF is 0.45%. This present research results that the Thai population has a difference in MF location while comparing to other populations. Moreover, Thai MF and accessory MF location and localization will be helpful to clinical implications.

An anatomical study on locations of the mandibular foramen and the accessory mandibular foramen in the mandible and their clinical implication in a Thai population / 대한해부학회지

Mandibular foramen (MF) is a structure that inferior alveolar nerve and artery pass through itself which is found on the mandible. The objective of this research aims to locate MF among the Thai population including other MF characteristics. The sampling is conducted in the Thai population of the total number of 220 samples from the Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University. The MF anteroposterior and superoinferior localizations are similar in both sex which at Q3 of right anteroposterior, Q2 of left anteroposterior and Q2 of left and right superoinferior axis. Otherwise, the prevalence of accessory MF has in 68 samples which are 30.89%. The prevalence of unilateral single accessory MF is 20.45%, bilateral single accessory MF is 6.36%, unilateral double accessory MF is 2.27% and bilateral double accessory MF is 0.45%. This present research results that the Thai population has a difference in MF location while comparing to other populations. Moreover, Thai MF and accessory MF location and localization will be helpful to clinical implications.

Quantitative evaluation of palatal bone thickness in patients with normal and open vertical skeletal configurations using cone-beam computed tomography

PURPOSE: To 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 METHODS: Thirty 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. RESULTS: The 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). CONCLUSION: Class 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.

Distances from the root apices of posterior teeth to the maxillary sinus and mandibular canal in patients with skeletal open bite: A cone-beam computed tomography study

PURPOSE: This 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 METHODS: Pretreatment 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. RESULTS: The 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. CONCLUSION: There were no differences in the mean MSDs or the mean MCDs between the skeletal normal bite group and the skeletal open bite group.

Comparison of interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns using cone-beam computed tomography

PURPOSE: This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. RESULTS: Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. CONCLUSION: In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

PURPOSE: This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. MATERIALS AND METHODS: The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. RESULTS: Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. CONCLUSION: The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

PURPOSE: This 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 METHODS: The 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. RESULTS: The 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. CONCLUSION: These 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.

Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

PURPOSE: 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 (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). RESULTS: The mean Az 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 Az value. CONCLUSION: Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

Evaluation of the depth of non-cavitated carious lesions by radiographs

Aims: To evaluate and compare the depths of white and brown spot, non-cavitated, carious lesions by radiographs.Methods: Thirty white spot and 25 brown spot, non-cavitated carious lesions from proximal surfaces of extracted premolar and molar teeth were selected. The bucco-lingual dimension (size) of all lesions was measured using a vernier caliper. The teeth were radiographed. Three observers scored the lesions’ depths from the radiographs.  The lesions’ depths in ground sections were used as the gold standard. The depths of the white and brown spot lesions were compared. The relationship between the depth and the sizes of both types of lesion were evaluated. The depths measured on the radiographs were compared to those of the gold standard. Results: The white lesions were significantly deeper than the brown lesions. Radiographically, most of the brown lesions (72%) showed no radiolucency. Of the white lesions, 50% had lesion depths limited to enamel and 36.7% showed no radiolucency.  The remainder had lesions reaching at least to the DEJ. However, the ground sections showed that 60% of the white lesions reached at least to the DEJ. There was a significant correlation between the radiographic depth and the lesions’ sizes in only the white lesions. Compared to the gold standard, the radiographic measurement underestimated the lesions’ depths, equally for both white and brown spot lesions.Conclusions: For both radiographic and ground section examinations, white spot lesions were deeper than brown spot lesions. Therefore, they should be given more attention in disease prevention and treatment. Radiographs should be used as one of the aids for treatment planning of non-cavitated, carious, especially white, lesions. Key Words: non-cavitated carious lesion, depth, radiograph