Cone-beam computed tomography-based investigation of pre-eruptive intracoronal resorption prevalence.

This retrospective study aimed to investigate the prevalence of pre-eruptive intracoronal resorption (PEIR) using cone-beam computed tomography (CBCT) and to explore the mechanism and characteristics of PEIR development. CBCT images of patients aged ≤ 20 years with unerupted teeth at Hiroshima University Hospital were collected. We examined 1530 patients with 10,576 unerupted teeth. Teeth with PEIR were identified for the detailed location and size of the PEIR in the crown using multiplanar reconstruction. The subject and tooth prevalence rates of PEIR were 1.96% and 0.31%, respectively. The teeth that were the most commonly affected by PEIR were mandibular third molars (3.09%). The prevalence of PEIR was significantly higher in females than in males, and higher in the mandible than in the maxilla. No significant difference between in the position of PEIR within the crown was observed. Moreover, CBCT imaging revealed the onset of PEIR in one case. This study demonstrated the prevalence of PEIR and identified statistically significant sex- and location-based differences. Furthermore, one case of CBCT imaging supports the hypothesis that the onset of PEIR was due to resorption after completion of the crown.

Prospective Observational Study for the Comparison of Screening Methods Including Tongue Pressure and Repetitive Saliva Swallowing With Detailed Videofluoroscopic Swallowing Study Findings in Patients With Acute Stroke.

BACKGROUND: Simple, noninvasive, and repeatable screening methods are essential for assessing swallowing disorders. We focused on patients with acute stroke and aimed to assess the characteristics of swallowing screening tests, including the modified Mann Assessment of Swallowing Ability score, tongue pressure, and repetitive saliva swallowing test (RSST), compared with detailed videofluoroscopic swallowing study (VFSS) findings to contribute as a helpful resource for their comprehensive and complementary use. METHODS AND RESULTS: We enrolled first-ever patients with acute stroke conducting simultaneous assessments, including VFSS, modified Mann Assessment of Swallowing Ability score, tongue pressure measurement, and RSST. VFSS assessed aspiration, laryngeal penetration, oral cavity residue, vallecular residue, pharyngeal residue, and swallowing reflex delay. Screening tests were compared with VFSS findings, and multiple logistic analysis determined variable importance. Cutoff values for each abnormal VFSS finding were assessed using receiver operating characteristic analyses. We evaluated 346 patients (70.5±12.6 years of age, 143 women). The modified Mann Assessment of Swallowing Ability score was significantly associated with all findings except aspiration. Tongue pressure was significantly associated with oral cavity and pharyngeal residue. The RSST was significantly associated with all findings except oral cavity residue. Receiver operating characteristic analyses revealed that the minimum cutoff value for all VFSS abnormal findings was RSST ≤2. CONCLUSIONS: The modified Mann Assessment of Swallowing Ability is useful for broadly detecting swallowing disorders but may miss mild issues and aspiration. The RSST, with a score of ≤2, is valuable for indicating abnormal VFSS findings. Tongue pressure, especially in oral and pharyngeal residues, is useful. Combining these tests might enhance accuracy of the swallowing evaluation.

Image preprocessing with contrast-limited adaptive histogram equalization improves the segmentation performance of deep learning for the articular disk of the temporomandibular joint on magnetic resonance images.

OBJECTIVES: The objective was to evaluate the robustness of deep learning (DL)-based encoder-decoder convolutional neural networks (ED-CNNs) for segmenting temporomandibular joint (TMJ) articular disks using data sets acquired from 2 different 3.0-T magnetic resonance imaging (MRI) scanners using original images and images subjected to contrast-limited adaptive histogram equalization (CLAHE). STUDY DESIGN: In total, 536 MR images from 49 individuals were examined. An expert orthodontist identified and manually segmented the disks in all images, which were then reviewed by another expert orthodontist and 2 expert oral and maxillofacial radiologists. These images were used to evaluate a DL-based semantic segmentation approach using an ED-CNN. Original and preprocessed CLAHE images were used to train and validate the models whose performances were compared. RESULTS: Original and CLAHE images acquired on 1 scanner had pixel values that were significantly darker and with lower contrast. The values of 3 metrics-the Dice similarity coefficient, sensitivity, and positive predictive value-were low when the original MR images were used for model training and validation. However, these metrics significantly improved when images were preprocessed with CLAHE. CONCLUSIONS: The robustness of the ED-CNN model trained on a dataset obtained from a single device is low but can be improved with CLAHE preprocessing. The proposed system provides promising results for a DL-based, fully automated segmentation method for TMJ articular disks on MRI.

Construction of orthodontic setup models on a computer.

INTRODUCTION: Orthodontic setup models are usually limited to the display of teeth, with no information about the roots. The purpose of this article is to present a method for visualizing the tooth roots in setup models by integrating information from cone-beam computed tomography and a laser scanner. The reproducibility of the integration was evaluated. METHODS: The records of 5 patients were used in this study. Three-dimensional digital models were generated from the dental casts. Tooth models were generated from the cone-beam computed tomography slices. The 3-dimensional models were superimposed on the crowns of the teeth in the tooth models and integrated. The integrated 3-dimensional tooth model and 3-dimensional setup model were registered. The reproducibility of the integration was evaluated for each tooth. Unpaired Student t tests were performed on the data between the anterior and posterior teeth, and between the right and left teeth. RESULTS: The discrepancy among the integrated 3-dimensional models at the final positions after we used this technique was 0.025 ± 0.007 mm. There was a significant difference in the distance between the anterior and posterior teeth (P <0.05). However, the average distances between the anterior and posterior teeth were small: 0.023 ± 0.007 and 0.028 ± 0.007 mm, respectively. No significant difference was found between the right and left teeth (P = 0.831). CONCLUSIONS: The methods presented in this study provide a reproducible visualization of tooth roots in virtual setup models by registering accurate crown models to cone-beam computed tomography scans.

Do various imaging modalities provide potential early detection and diagnosis of medication-related osteonecrosis of the jaw? A review.

OBJECTIVE: Patients with medication-related osteonecrosis of the jaw (MRONJ) often visit their dentists at advanced stages and subsequently require treatments that greatly affect quality of life. Currently, no clear diagnostic criteria exist to assess MRONJ, and the definitive diagnosis solely relies on clinical bone exposure. This ambiguity leads to a diagnostic delay, complications, and unnecessary burden. This article aims to identify imaging modalities' usage and findings of MRONJ to provide possible approaches for early detection. METHODS: Literature searches were conducted using PubMed, Web of Science, Scopus, and Cochrane Library to review all diagnostic imaging modalities for MRONJ. RESULTS: Panoramic radiography offers a fundamental understanding of the lesions. Imaging findings were comparable between non-exposed and exposed MRONJ, showing osteolysis, osteosclerosis, and thickened lamina dura. Mandibular cortex index Class II could be a potential early MRONJ indicator. While three-dimensional modalities, CT and CBCT, were able to show more features unique to MRONJ such as a solid type periosteal reaction, buccal predominance of cortical perforation, and bone-within-bone appearance. MRI signal intensities of vital bones are hypointense on T1WI and hyperintense on T2WI and STIR when necrotic bone shows hypointensity on all T1WI, T2WI, and STIR. Functional imaging is the most sensitive method but is usually performed in metastasis detection rather than being a diagnostic tool for early MRONJ. CONCLUSION: Currently, MRONJ-specific imaging features cannot be firmly established. However, the current data are valuable as it may lead to a more efficient diagnostic procedure along with a more suitable selection of imaging modalities.

Multislice Computed Tomography Assessment of Airway Patency Changes Associated with Mandibular Advancement Appliance Therapy in Supine Patients with Obstructive Sleep Apnea.

The purpose of the present study was to measure the regional effects of the mandibular advancement appliance (MAA) on the upper airway of supine subjects with obstructive sleep apnea (OSA) using multislice computed tomography (MSCT). The subjects included 8 males and 5 females who were diagnosed with mild to moderate OSA and were referred to the Orthodontic Clinic of Hiroshima University Hospital, where they underwent MAA therapy. Using a CT scanner, baseline MSCT images were obtained from the subjects without the MAA for morphological analysis, and then the experimental images were obtained while wearing the MAA. To measure the anteroposterior diameter, width, and cross-sectional area of the oropharynx region of interest (ROI), five distance variables were first defined on each multiplanar reconstruction (MPR) image using OsiriX. Additionally, the volumes of the upper airway, bony hard tissue, and soft tissue (soft palate and tongue) in the oro-hypopharyngeal region were measured. In most of the assessed airway size variables, significant increases in the anteroposterior diameter and width were observed after MAA therapy. Regarding the upper airway cross-sectional area, all the upper airway size variables exhibited significant increases. In the volumetric analysis, a significant increase was observed in airway volume, whereas the soft tissue volume in the oro-hypopharyngeal region did not show the significant decrease after MMA therapy. However, from a different point of view, the volumes of the upper airway and soft tissue significantly increased and decreased, respectively, as demonstrated by the calculated ratio for the oro-hypopharyngeal region. We demonstrated that the proportional size of the soft tissue volume, i.e., the soft palate and tongue in the oro-hypopharyngeal region, significantly decreased during use of an MAA. This forward displacement of the soft tissue thereby increases the retroglossal airway space (except the nasopharynx) three-dimensionally.

Influence of aging and denture use on liquid swallowing in healthy dentulous and edentulous older people.

OBJECTIVES: To clarify the influence of aging and denture use on swallowing in healthy edentulous people aged 75 and older. DESIGN: A cross-sectional research design was used with participants from Hiroshima University Hospital, Hiroshima University, and Hiroshima City. SETTING: Participants were examined in Hiroshima University Hospital, Hiroshima, Japan. PARTICIPANTS: Thirteen edentulous elderly volunteers (7 male, 6 female; aged 75-86, mean age 81.2) and 19 dentulous elderly volunteers (12 male, 7 female; aged 80-87, mean age 81.2) as a control group participated in this study. Participants reported no clinical symptoms relating to dysphagia, neurological impairments, or degenerative diseases. MEASUREMENTS: Participants were asked to swallow a 10-mL barium sulfate solution three times. Edentulous older people were asked to swallow the solution while wearing dentures and with dentures removed. Functional swallowing was recorded on cine-film with a digital subtraction angiography system. Lateral cinefluorography images were obtained from seated subjects. Using a cine-projector, visual images were evaluated qualitatively and quantitatively. RESULTS: No participants exhibited aspiration. The occurrence of laryngeal penetration in the edentulous older people not wearing dentures was the only significant difference (P<.05). CONCLUSION: Only laryngeal penetration differed significantly between edentulous older people not wearing their dentures and dentulous older people.

Aspects of swallowing in healthy dentate elderly persons older than 80 years.

BACKGROUND: Although age-related changes resulting in slowing of the swallowing reflex and a decline in the neuromuscular control system have been reported, there have been few reports on swallowing function in dentate elderly persons. The purpose of this study was to clarify the primary influence of aging on swallowing in healthy dentate elderly persons older than 80 years who have more than 20 teeth. METHODS: Dentate elderly persons (12 male, 7 female; mean age: 81.2 years) and dentate young participants (9 male, 5 female; mean age: 26.8 years) as a control group participated voluntarily. Participants reported no clinical symptoms relating to dysphagia, neurologic impairments, or degenerative diseases, and were asked to swallow 10 ml of barium sulfate solution (10% w/v) three times. Functional swallowing was recorded on 35 mm cinefilm at 30 frames per second with a digital subtraction angiography system. Lateral images of cinefluorography of seated participants' mouth, pharynx, and larynx were obtained. Visual image analysis for qualitative and quantitative evaluation was made with a cine projector. RESULTS: No participants exhibited aspiration during three trials. Occurrence and frequencies of piecemeal deglutition, premature loss of liquid, oral and pharyngeal residues, and laryngeal penetration were significantly greater in dentate elderly persons (p <.05) than in the dentate young participants. Oral transit time, pharyngeal delay time, and pharyngeal transit time in dentate elderly persons were prolonged significantly compared with those in dentate young participants (p <.01). CONCLUSION: Physiological swallowing functions deteriorate even in healthy dentate elderly persons. This deterioration may be explained primarily by the influence of aging on swallowing.

Deglutitive tongue movement after correction of mandibular protrusion.

OBJECTIVE: To investigate any change in deglutitive tongue movement following the correction of malocclusion by orthognathic surgery. MATERIALS AND METHODS: The subjects were nine patients with mandibular protrusion. A control group consisted of 10 individuals with a similar age range and normal occlusion. Swallowing events before and after mandibular setback via sagittal split ramus osteotomy were recorded by cineradiography, and the tongue movement was analyzed. Time and linear measurements were compared before and after surgical treatment by the Wilcoxon signed rank test; control and test subjects were compared with the Mann-Whitney U-test. RESULTS: Tongue-palate contact and the tongue-tip position changed after orthognathic surgery and became similar to those of the controls. Movements of the anterior and middorsal regions of the tongue did not change after orthognathic surgery and remained different from those of the controls. CONCLUSION: Our findings suggest that tongue-palate contact and tongue-tip position during deglutition adapted to the corrected oral and maxillofacial morphology, but the anterior and middorsal regions of the tongue during deglutition may have been affected by pharyngeal constrictors rather than by the oral and maxillofacial morphology.

Radiographic evaluation of the fate of developing tooth buds on the fracture line of mandibular fractures.

PURPOSE: The goal was to suggest guidelines for the treatment of developing tooth buds located on the fracture line of mandibular fractures. PATIENTS AND METHODS: The long-term radiographic follow-up records of 28 patients with mandibular fractures involving 66 tooth buds were examined for the occurrence of abnormalities in development or eruption. The fates of the involved teeth were compared according to the fracture conditions and other factors, and the cause of the abnormalities was surveyed. RESULTS: Abnormal findings were observed in 30 of 66 developing teeth (45%); these included deficient root formation, abnormal bend of the root, nodule formation on the root, partial obliteration of the pulp cavity, impaction, growth arrest, and external resorption. No relationship was found between the presence of abnormalities and the condition of the fracture or the developmental stage of the tooth buds. However, infection, rotation of the tooth bud, and a surgical wire passing through the follicular space were associated with arrested growth and impaction. CONCLUSIONS: The tooth buds present on the fracture line should be preserved except in cases of infection, and careful attention should be paid to avoiding further injury to the tooth bud and the soft tissues of the follicle at the time of surgery.

Relationship between maxillofacial morphology and deglutitive tongue movement in patients with anterior open bite.

We reported previously that patients with anterior open bite had tongue tip protrusion, slower movement of the rear part of the dorsal tongue, and earlier closure of the nasopharynx during deglutition. In the present study, the relationship between this characteristic tongue movement and maxillofacial morphology in patients with anterior open bite was investigated. The subjects were 10 female patients with anterior open bites and 10 women with normal overbites as controls. Maxillofacial morphology was measured by cephalometric radiography, and tongue movement during deglutition was analyzed by cineradiography. The relationship between each value obtained by cephalometric radiography and cineradiography was evaluated by simple correlation analysis. In the patients with anterior open bite, there were significant correlations between mandibular plane angle, ramus height of the mandible, or anteroposterior dimension of the maxilla and movement of the front part of the dorsal tongue during deglutition. Furthermore, there were also significant correlations in these patients between mandibular plane angle, gonial angle, or ramus height of the mandible and the change in the contact between tongue and palate during deglutition. The controls did not have the correlations like these. Our study suggests that characteristic tongue movements during deglutition in patients with anterior open bites are closely related to their morphological features.