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.

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.

Infection control and patient discomfort with an alternative plastic barrier in intraoral digital radiography.

OBJECTIVES: (1) To compare the efficacy of a commercially available hygienic sheath and an alternative plastic bag in preventing contamination of the imaging plate during intraoral radiography and (2) to compare patient discomfort when using the hygienic sheath and the plastic bag. METHODS: 60 sterilized Size 2 imaging plates covered with either the hygienic sheath (n = 30) or the plastic bag (n = 30) were used to simulate digital periapical radiographic examination in 30 volunteer patients. After disinfection, each plate was swabbed. The swabbed medium was then plated on trypticase soy agar and incubated. Bacterial colonies were counted. Patient discomfort was assessed using a visual analogue scale (VAS) score. The comparison of the number of bacterial colonies and VAS scores between the two groups was tested by paired t-test at p < 0.05. RESULTS: There was no significant difference in the number of bacterial colonies between the two groups (p = 0.745). Of all the plates, 10% plates yielded bacterial colonies. The mean count of bacterial colonies for both groups was 10-20 CFU ml-1. However, there was a significant difference between VAS scores for the two systems (p = 0.000). The mean VAS scores (range 0-10) for patient discomfort for the hygienic sheath group and the plastic bag group were 3.03 and 5.33, respectively. CONCLUSIONS: Based on the design of this study, the alternative barrier provided similar results to those commercially available. Regarding the type of barrier envelope, the hygienic sheath induced less discomfort than the plastic bag.

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.

New prediction models for dental age estimation in Thai children and adolescents.

UNLABELLED: The aims of this study were to develop new prediction models for dental age estimation and to test the accuracy of the resulting models in comparison with the Demirjian et al. and the Willems et al. methods in Thai children and adolescents. Digital panoramic radiographs of 1,134 Thai individuals (487 males and 647 females) aged from 6 to 15 years were selected and evaluated for dental age estimation. Quadratic regression was used to generate new models. The results showed that the new prediction models indicated a strong correlation coefficient between the dental maturity score and the chronological age in both sexes (r=0.951 for males, r=0.945 for females). The new age prediction models were: y=0.006297x(2) - 0.804930x+32.591843 for males and y=0.010677x(2) - 1.538823x+61.955056 for females, where y is the dental age, x is the dental maturity score according to Demirjian et al. METHOD: Moreover, these new models were tested showing the greatest accuracy for estimating the age in Thai samples using the mean difference values between the dental and the chronological ages (-0.04 years for males, 0.02 years for females) when compared with the Demirjian et al. and the Willems et al. METHODS: In addition, the new models revealed a high percentage of accuracy in the absolute difference values between the dental and the chronological ages within 1 year (76.26% and 74.49% for males and females, respectively). Furthermore, our results in mean difference values indicated that the Demirjian et al. method (0.11 and 0.10 years for males and females, respectively) was more accurate than the Willems et al. method (-0.37 and -0.39 years for males and females, respectively) in Thai samples. In conclusion, the new age prediction models in this study provide accurate age estimation in both sexes, suggesting that these models be applied for forensic age estimation, especially in Thai children and adolescents.

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 (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.