Assessment of sagittal root position, alveolar bone concavity, and labial bone perforation in the mandibular anterior tooth region for immediate implant placement.

Background/purpose: Immediate implant placement in the mandibular anterior tooth region requires a thorough understanding of the alveolar bone anatomy for determining the ideal implant position and preventing labial bone perforation. The anatomical characteristics of the jaws are closely related to the sagittal root position (SRP) and labial concavity of the alveolar bone. This study evaluated SRP, labial concavity, and labial bone perforation in the mandibular anterior tooth region. Materials and methods: Cone-beam computed tomography images of 116 participants (696 teeth) were uploaded to medical imaging software. SRP classification, labial concavity of the alveolar bone, and labial bone perforation were analyzed. A t-test was performed to compare measurements between the central and lateral incisors, central incisors and canines, and lateral incisors and canines. Results: The results revealed that the frequency of SRP Class I (88.20%) was the highest, and that of SRP Class III was the lowest (0.53%). Central incisors had the highest mean labial concavity (144.5°), followed by the canines (143.9°) and lateral incisors (143.3°), and the differences were significant between any two of the tooth groups (all P < 0.05). The frequency distribution of labial bone perforation was the highest in central incisors (69.9%), followed by the canines (40.5%) and lateral incisors (10.8%). Conclusion: The majority of mandibular anterior teeth had SRP Class I, with Class III being the least prevalent. Central incisors had the highest mean alveolar bone concavity angle and the most frequent labial bone perforations.

Outpatient Dental Treatment Expenditure for Patients with Oromaxillofacial Cancer: A Cohort Study in Taiwan.

The information on the outpatient expenditure of patients with oromaxillofacial cancer is minimal. This study aimed to compare the average annual expenditure on dental treatment for these patients 5 years before and 5 years after oromaxillofacial cancer diagnosis. In this study, 7731 patients who received oromaxillofacial cancer diagnosis in 2005 were selected from the Registry of Catastrophic Illness Database as the case-cohort. In the control cohort, 38,655 people without cancer were selected from the National Health Insurance Research Database, with the case-control ratio being 1:5. All participants were observed for 5 years before diagnosis and 5 years after diagnosis. The conditional logistic regression model was used to determine the odds ratios of annual expenditures incurred by participants in the case-cohort. The measurement results indicated that in the oromaxillofacial cancer cohort, the average annual dental expenditure levels at 1, 2, 3, 4, and 5 years after diagnosis were US $97.34, US $77.23, US $109.65, US $128.43, and US $128.03 and those at these years before diagnosis were US $37.52, US $32.10, US $31.86, US $29.14, and US $29.35, respectively. In conclusion, the average annual expenditure on the dental treatment of oromaxillofacial cancer patients after five years of diagnosis was increased compared to five years before diagnosis.

Assessment of the Retromolar Canal in Taiwan Subpopulation: A Cross-Sectional Cone-Beam Computed Tomography Study in a Medical Center.

The retromolar canal is an anatomical variation that occurs in the mandibular bone. The retromolar canal typically originates in the mandibular canal on the distal side of the third molar and extends forward and upward to the retromolar foramen (RMF), which contains the neurovascular bundle. Accidentally damaging the neurovascular bundle in the retromolar canal during the extraction of the third molar, dental implant surgery, or maxillofacial orthognathic surgery may lead to subsequent complications such as incomplete local anesthesia, paresthesia, and bleeding during operation. The objective of this study was to investigate the prevalence of the RMF in the Taiwanese population in a medical center by using dental cone-beam computed tomography (CBCT) and to identify the position of the RMF in the mandibular bone. The dental CBCT images for the mandibular bone of 68 hemi-mandible were uploaded to the medical imaging software Mimics 15.1 to determine the prevalence of the RMF in the Taiwanese population and the three positional parameters of the RMF in the mandibular bone: (1) The diameter of the RMF, (2) the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the second molar, and (3) the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal. Seven RMFs were observed in the 68 hemi-mandibles. Thus, the RMF prevalence was 10.3%. In addition, the diameter of the RMF was 1.41 ± 0.30 mm (mean ± standard deviation), the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the the second molar was 12.93 ± 2.87 mm, and the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal below second molar was 13.62 ± 1.3487 mm. This study determined the prevalence of the RMF in the Taiwanese population in a medical center and its relative position in the mandibular bone. This information can provide clinicians with a reference for posterior mandible anesthesia and surgery to ensure medical safety.

Clinical assessment of the palatal alveolar bone thickness and its correlation with the buccolingual angulation of maxillary incisors for immediate implant placement.

BACKGROUND: Clinicians needed to be aware of the thinness of the palatal bone plate when identifying severe protrusion of maxillary incisors, as this could result in perforation of the palatal bone plate during surgical procedures associated with immediate maxillary implant placement. PURPOSE: This study evaluated the thickness of the palatal bone plate, the buccolingual angulation of maxillary incisors, and the correlation between these two parameters in relation to immediate implant placement. MATERIALS AND METHODS: Cone-beam computed tomography images of 37 Asian patients (20-60 years old) with no evidence of dental treatment in the maxillary incisor area were collected and classified into groups based on sex and incisor locations. Sagittal slices were used to measure the palatal bone plate thickness at the cervical, middle, and apical levels, and the buccolingual angulation of each tooth was also measured. The intraclass correlation, Shapiro-Wilk test, descriptive analysis, Student's t-test, and Pearson correlation were used for statistical and correlation analyses, with P < .05 applied as the criterion for statistical significance. RESULTS: At the apical level of all inspected teeth and the middle level of lateral incisors, the palatal bone was significantly thicker in males than in females. The inclination of the maxillary lateral incisor showed a moderate negative linear correlation with the palatal bone thickness at the apical level (R = -0.517 and R = -0.579 for males and females, respectively). CONCLUSIONS: In an Asian population, an increased buccolingual angulation of the maxillary lateral incisors was correlated with a thinner palatal bone plate at the apical level.