Classification of Maxillofacial Morphology by Artificial Intelligence Using Cephalometric Analysis Measurements.

The characteristics of maxillofacial morphology play a major role in orthodontic diagnosis and treatment planning. While Sassouni's classification scheme outlines different categories of maxillofacial morphology, there is no standardized approach to assigning these classifications to patients. This study aimed to create an artificial intelligence (AI) model that uses cephalometric analysis measurements to accurately classify maxillofacial morphology, allowing for the standardization of maxillofacial morphology classification. This study used the initial cephalograms of 220 patients aged 18 years or older. Three orthodontists classified the maxillofacial morphologies of 220 patients using eight measurements as the accurate classification. Using these eight cephalometric measurement points and the subject's gender as input features, a random forest classifier from the Python sci-kit learning package was trained and tested with a k-fold split of five to determine orthodontic classification; distinct models were created for horizontal-only, vertical-only, and combined maxillofacial morphology classification. The accuracy of the combined facial classification was 0.823 ± 0.060; for anteroposterior-only classification, the accuracy was 0.986 ± 0.011; and for the vertical-only classification, the accuracy was 0.850 ± 0.037. ANB angle had the greatest feature importance at 0.3519. The AI model created in this study accurately classified maxillofacial morphology, but it can be further improved with more learning data input.

Tensile and shear bond strengths of a stainless steel used in orthodontic brackets bonded to bovine enamel using two types of resin cement.

The purpose of this study was to examine the relationship between the bond strength of stainless steel with two types of resin cements (MMA- and composite-based) on bovine enamel depending on the directionality of the applied force. The specimens were either placed in water or subjected to thermal cycles (TC), and the shear or tensile bond strengths (SBS or TBS) were determined. The SBS showed significantly greater than the TBS for both types of cement, and the SBS and TBS for composite-based cement had larger than MMA-based one. No significant difference in SBS was observed in the cements even after being subjected to TC. Cohesive failures of the cement and bovine enamel in the composite-based group, while adhesive failures were observed in MMA-based one. Consequently, the direction of the force at both cements affected the retention of stainless steel, and MMA-based cement was preferred when prioritizing less enamel damages.

Goltz Syndrome Combined with Triple X Syndrome, a Case Report.

Goltz syndrome is a rare X-linked dominant multisystem disorder that presents with ectoderm and mesoderm-derived symptoms. Skin manifestations including congenital patchy skin aplasia, congenital nodular fat herniation, congenital hypo- or hyperpigmentation along Blaschko's lines, telangiectasia, and congenital ridged dysplastic nails are typical in this disorder. Almost all cases of Goltz syndrome correspond to female newborns and that hemizygosis makes the syndrome fetal in males. Triple X syndrome is a relatively common congenital disorder that presents with mild to no symptoms in the developmental and psychiatric realm. The patient reported here was born with multisystem anomaly affecting the eyes, craniofacial region, cardiovascular system, skin, and limbs. A G-banding chromosomal study revealed 47, XXX. She was diagnosed with Goltz syndrome owing to her distinctive skin manifestations. The congenital cervical skin defect healed with conservative treatment. The facial cleft, cleft lip-palate, and syndactyly were successfully treated with multiple surgical treatments. The combination of triple X syndrome and Goltz syndrome is very rare. We describe the expression of presenting with both syndromes simultaneously.

Diagnosis of Tooth Prognosis Using Artificial Intelligence.

The accurate diagnosis of individual tooth prognosis has to be determined comprehensively in consideration of the broader treatment plan. The objective of this study was to establish an effective artificial intelligence (AI)-based module for an accurate tooth prognosis decision based on the Harvard School of Dental Medicine (HSDM) comprehensive treatment planning curriculum (CTPC). The tooth prognosis of 2359 teeth from 94 cases was evaluated with 1 to 5 levels (1-Hopeless, 5-Good condition for long term) by two groups (Model-A with 16, and Model-B with 13 examiners) based on 17 clinical determining factors selected from the HSDM-CTPC. Three AI machine-learning methods including gradient boosting classifier, decision tree classifier, and random forest classifier were used to create an algorithm. These three methods were evaluated against the gold standard data determined by consensus of three experienced prosthodontists, and their accuracy was analyzed. The decision tree classifier indicated the highest accuracy at 0.8413 (Model-A) and 0.7523 (Model-B). Accuracy with the gradient boosting classifier and the random forest classifier was 0.6896, 0.6687, and 0.8413, 0.7523, respectively. Overall, the decision tree classifier had the best accuracy among the three methods. The study contributes to the implementation of AI in the decision-making process of tooth prognosis in consideration of the treatment plan.

Current Implementation of Digital Dentistry for Removable Prosthodontics in US Dental Schools.

Objectives: Although digital technology has been widely integrated into dental education, there is limited literature investigating the extent of the integration of computer-aided design and computer-aided manufacturing (CAD-CAM) for removable systems in the dental curriculum. The purpose of this study was to assess the current implementation of CAD-CAM complete and partial dentures in predoctoral (PP) and advanced graduate prosthodontic (AGP) education in US dental schools. The study also aimed to identify potential barriers to its implementation in the dental curriculum. Methods: An online survey with 15 questions was created using online survey software. The survey was distributed to the directors of predoctoral prosthodontics in 56 schools and advanced graduate programs of prosthodontics in 52 schools listed in the 2018-19 American Dental Education Association (ADEA) Directory. Results: The percentage of programs (PP and AGP) implementing CAD-CAM complete dentures (CAD-CAM CDs) and CAD-CAM removable partial dentures (CAD-CAM RPDs) in their didactic, preclinical, and clinical curricula was recorded. CAD-CAM CDs are taught in didactic courses in 54.2% of PP and 65.2% of AGP. However, CAD-CAM RPDs are only taught in 37.5% of PP and 47.8% of AGP. Programs are largely limited by a lack of funds, resources, time, and faculty members. Conclusion: While digital technologies have indeed become more prevalent in dental education, many institutions face barriers to implementation. More research must be conducted in order to support the continued incorporation of digital technologies into dental education.

Importance of bitewing radiographs for the early detection of interproximal carious lesions and the impact on healthcare expenditure in Japan.

BACKGROUND: Globally, the direct cost of dental caries is approximately $298B yearly, consuming 5-10% of national healthcare budgets. Bitewing radiographs (BWR) are the standard method of diagnosing interproximal dental caries. In Japan, bitewing radiographs are rarely used. This retrospective observational study was conducted to measure the potential economic impact of carious lesions left undiagnosed and untreated due to this omission of bitewing radiographs. METHODS: The total number of existing carious lesions, the number of undiagnosed lesions, and costs of treating these lesions were calculated from the national database of Ministry of Health, Labor and Wellness in Japan between June 2013 and 2017. The number of affected teeth was estimated using prevalence data and undiagnosed lesions were estimated. The expense associated with treating progressed lesions was calculated using the standard Japanese fee structure. BWR trends were assessed, and analyses were performed to understand the differences between states and populations over time. RESULTS: The average number of BWR taken monthly per office was 48.3±1.1 (average ± SD). It was calculated that an average of 6,429,155 lesions went undiagnosed per month, 93.5 teeth per practice, and 1.6 teeth per patient. The cost of treating lesions that went undiagnosed and then progressed into more invasive restorations was estimated to be between $57M-$218M more (difference between NaF varnish and class II restorations), and $150M-$443M more (difference between Class II restoration and crown or crown with RCT). CONCLUSIONS: BWRs are crucial in diagnosing a significant number of carious lesions. There is considerable impact on health and cost to the national health system due to undiagnosed lesions. Practitioners need to be educated on reading and understanding BWR, and policy should be changed to cover BWR.

Accuracy of a Method to Monitor Root Position Using a 3D Digital Crown/Root Model during Orthodontic Treatments.

This study aimed to assess the accuracy of a method of predicting post-movement root position during orthodontic treatment using a 3D digital crown/root model (3DCRM) created with pre-movement records of both cone-beam computed tomography (CBCT) and dental arch digital scans. Pre- and post-movement CBCT scans and dental arch digital scans of five patients who had completed orthodontic treatments were used in this study. The 3DCRM was superimposed onto the post-movement scanned dental arch to identify the post-movement root position (test method). Post-movement CBCT (referenced as the current method) served as the control to identify the actual post-movement root position. 3D-coordinate analysis revealed no significant differences between the test and current methods along the X and Y axes. However, the discrepancy on the Z axis (especially in cases of intrusion) was greater than that in all other directions for all three tooth types examined (p < 0.05). A strong positive correlation between the degree of discrepancy and the distance of tooth movement was observed on the Z axis (r = 0.71). The 3DCRM method showed promising potential to accurately predict root position during orthodontic treatments without the need for a second CBCT. However, root resorption, which affected the Z axis prediction, needs to be closely monitored using periapical radiographs to complement this method.

3D digital analysis of tooth movement with magnets and elastics in vitro.

OBJECTIVES: Magnets have many advantages in orthodontics, and our previous studies confirmed their therapeutic potential through 3D-data analysis. The aim of this study was to compare tooth movements, including rotation, obtained via magnetic and elastic forces in crowded cases in vitro. METHODS: Typodont models mimicking a crowded case were prepared. In the magnetic force-driven orthodontics (MG) group, Nd-Fe-B magnets were attached to the labial surfaces from UR4 to UL4 for attracting force, and to UR6 and UL6 for repulsing force. For the elastic force-driven orthodontic (EL) group, brackets were placed on labial surfaces from UR2 to UL2 with power-chain elastics. A NiTi archwire was used in both groups. The models were 3D scanned before and after tooth movement and exported as STL files. The pre- and post-movement STL files were superimposed. The 3D coordinates of the measurement points of the crown and root apex were obtained, and tooth displacement, 3D movements (X, Y, and Z-axis), and rotation (yaw, pitch, and roll) were calculated. Two-tailed Student's t-test was performed for comparison of the results between MG and EL groups (n = 3). RESULTS: Overall, both groups indicated similar movement and rotation to achieve the planned arch form. In the crown movement and rotation, no significant differences were observed between MG and EL groups. However, in the root movement, there was a significant difference between MG and EL groups in X and Z axis for the canines. CONCLUSIONS: Magnetic force-driven orthodontics demonstrated comparable results to elastics with less tipping movement, suggesting a potential future orthodontic modality. CLINICAL SIGNIFICANCE: This in vitro study showed the potential of magnetic force for orthodontic application. The magnetic force-driven orthodontics might provide less tipping tooth movement compared to conventional methods, such as power chains, and could be a future technique for comprehensive orthodontic treatment.

Association between cognitive health and masticatory conditions: a descriptive study of the national database of the universal healthcare system in Japan.

Cognitive health is subject to decline with increasing numbers of lost teeth which impacts mastication. This study is a descriptive data analysis of the association between masticatory and cognitive conditions using a large database. We obtained the dental and medical records from Japan's universal healthcare system (UHCS) from the national database in 2017. The data from 94% of the Japanese population aged 65 and over is included. It is inclusive of diagnostic codes for various types of cognitive impairment, as well as dental treatment records from 2012 to 2017. The cognitive impairment group was compared to those without a diagnosis of cognitive impairment. Crude odds ratio between loss of mastication with natural teeth (exposure) and cognitive impairments (outcome) were compared. Patients who have lost masticatory function are likely to have cognitive impairment with an odds ratio of 1.89 (p<0.0001) for early elderly (aged 65-75) and 1.33 (p<0.0001) for advanced elderly (over 75). Patients who are edentulous and function with complete dentures are likely to have cognitive impairment with an odds ratio of 2.38 (p<0.0001) and 1.38 (p<0.0001), respectively. The data shows a convincing and significant result of an association between cognitive health and oral health, related to masticatory conditions.

Effects of healthcare policy and education on reading accuracy of bitewing radiographs for interproximal caries.

OBJECTIVES: The aim of this study is to assess the accuracy of bitewing radiograph interpretation of predoctoral students, residents and general dentists who work under different core curriculum of dental education and healthcare policy. METHODS: A total of 118 examiners including predoctoral dental students, residents and general dentists from USA and Japan were tasked with evaluating a series of bitewing radiographs and diagnosing interproximal carious lesions. This study was approved by the Harvard Medical School Institutional Review Board (IRB). Participants graded interproximal aspects of those images and categorized the following criteria; "intact", "enamel caries <1/2 width", "enamel caries >1/2 width" or "caries into dentin". The gold-standard was determined by the consensus of two HSDM full-time faculty. RESULTS: There was significant difference in the sensitivity for all three caries levels between the two groups but there was no significant difference on specificity. The positive-predictive and negative-predictive values of the USA group for the enamel caries (<1/2 of enamel) were significantly higher than the Japanese group. The average of AUC (ROC) was significantly higher in the USA group (0.885 ± 0.04) than the Japanese group (0.785 ± 0.08, p<0.01). CONCLUSION: Teaching and adopting BW radiographs for diagnosis of interproximal caries is integral for dental providers to accurately and efficiently use them in their practices. It is critical that all dental educators approach policymakers to explain the importance of BW radiographs and promote their efficacy for prevention and early diagnosis of interproximal caries.

Effect of Magnet Position on Tipping and Bodily Tooth Movement in Magnetic Force-Driven Orthodontics.

The goal of our study is to launch magnetic force-driven orthodontics. This continuous study investigated the influence of magnet position on tipping and bodily tooth movement, using 3D printing technology and digital analysis. Orthodontic typodont models (TMs) for space-closure were 3D printed to mimic maxillary central incisors. Nd-Fe-B magnets were placed in the middle third (Model-M), and the cervical third (Model-C), of the tooth. TMs, before and after movement, were digitally scanned and superimposed. The 3D digital coordinates (X, Y, and Z axes), and rotations (yaw, pitch, and roll) of the tooth crown and root, were calculated and compared between the two magnet position settings. Model-M showed higher rates of movement, but more rotation than Model-C (p < 0.01). The root apex of Model-M moved in the opposite direction of the crown (R = -0.29), indicating tipping movement. In contrast, the crown and root apex moved in the same direction (R = 0.56) in Model-C, indicating bodily movement. These patterns were confirmed in a typodont model of a moderate crowding case. The results validated that modifying the magnet position increased the amount of bodily tooth movement, and decreased rotation/tipping in an ex vivo setting.

Trans-trigeminal transport of masseter-derived neprilysin to hippocampus.

OBJECTIVE: To show the possible occurrence of exosomal transport of neprilysin from masseter muscle to hippocampus via trigeminal nerve in the living mouse. DESIGN: Mouse C2C12 myotube-derived exosomes were labeled with near-infrared (NIR) dye and injected into the masseter muscle to track their fluorescence from masseter muscle to hippocampus via trigeminal nerve. A plasmid vector encoding green fluorescent protein (GFP)-tagged neprilysin (GFP-neprilysin) was transfected into masseter muscle of C57BL/6 J mice. Expression of mRNA and encoded protein of the transgene was identified in masseter muscle, trigeminal nerve and hippocampus by RT-PCR and Western blot, respectively. RESULTS: Peak of exosomal NIR in masseter muscle at time 0 rapidly reduced at 3 h and 6 h along with the subsequent increases in trigeminal nerve and hippocampus. Expression of GFP-neprilysin mRNA was detected in masseter muscle, but not trigeminal nerve and hippocampus. On the other hand, the corresponding protein of GFP-neprilysin was identified in the three tissues on day 3 after transfection into masseter muscle as a single band on Western blots with anti-GFP and anti-neprilysin antibodies. CONCLUSION: The appearance of GFP-neprilysin protein in trigeminal nerve and hippocampus without a corresponding mRNA expression indicated the protein's origin from the masseter muscle. Concomitant migration of NIR-exosomes from masseter muscle to hippocampus via trigeminal nerve suggested the possible occurrence of exosomal transport of neprilysin.

3D digital analysis of magnetic force-driven orthodontic tooth movement.

With the introduction of rare earth magnets like neodymium-iron-boron (NdFeB), it has become possible to produce small magnets with high forces, necessary for its usage in the field of dentistry, such as for orthodontic tooth movement. The ultimate goal of this project is to establish magnetic force-driven orthodontic treatment as a future treatment modality for comprehensive orthodontic treatment. In order to utilize magnets for orthodontic treatment, we must first understand the characteristics of tooth movement created by magnetic forces. In this study, we aimed to digitally assess the efficacy of magnetic attraction and repulsion forces by means of a 3D digital analysis of movement (distance, direction, angulation and duration) and rotation (yaw, pitch and roll) of the crown and root of teeth in an ex vivo typodont model. We performed space closure and space gain treatment of maxillary central incisors (n = 30) and analyzed the movement and rotation of the teeth and root apex with 3D digital analysis. The results of the typodont model indicated significant differences on amount, speed and rotation of tooth and root movement created by magnetic attraction and repulsion forces. We also mimicked a moderate crowding typodont case and successfully treated it with a combination of attraction and repulsion magnetic forces. The moderate crowding case utilized magnets and a titanium archwire to guide the planned tooth movements and prevent undesired or unexpected movement. Further ex vivo experiments and considerations for biosafety will be necessary to investigate magnet force-driven orthodontics as a future modality of orthodontic treatment.

Cephalometric Measurements Of Non-Syndromic Oligodontia In Early Dental Age In A Japanese Population.

PURPOSE: Oligodontia significantly affects oral function and esthetics. Recognition of skeletal and dental patterns may aid in proper diagnosis and development of appropriate interventions. The aim of this study was to analyze skeletal and dental patterns for pre-adolescent patients with a diagnosis of oligodontia. PATIENTS AND METHODS: This study included 19 oligodontia patients (age: 9.5±1.3, Hellman's developmental stage IIIA~IIIB) along with a control group that comprised of 19 participants (age: 9.9±1.6) without any skeletal disharmony or congenitally missing teeth, with an Angle class I relationship and general crowding. Average cephalometric measurements among the oligodontia group were compared to the control group. The correlation between number of congenitally missing teeth (CMT) and each measurement was investigated. Skeletal measurements for both male and female patients in the oligodontia group and the control group were also compared. RESULTS: No significant difference between the experimental and the control group was observed with respect to skeletal angular and linear measurements, except the gonial angle. Differences in dental pattern measurements were observed. The oligodontia group had significantly smaller Mo-Ms and Is-Mo than the control group (p<0.01). No correlation was detected between severity of oligodontia (number of CMT) and skeletal measurement except for SNB (R=-0.4). For females with oligodontia, Mo-Ms (eruption of maxillary first molar) and Is-Mo (mesial location of maxillary first molar) significantly differed from females in the control group (p<0.01). In contrast, no differences in Mo-Ms or Is-Mo were detected for male patients when oligodontia and control group were compared. CONCLUSION: Among pre-adolescent Japanese patients with oligodontia in Hellman's developmental age IIIA~IIIB, no significant differences in skeletal characteristics were established when compared to the control group. However, tooth position of maxillary first molars indicated smaller vertical descent and mesial shift, which may suggest weak maxillary vertical development.

Retrograde transport of masseter muscle-derived neprilysin to hippocampus.

Although the effects of neprilysin (NEP), also called CD10, on the clearance of Alzheimer's disease (AD)-associated amyloid-ß (Aß) have been reported, NEP is not made in the brain, and the mechanism for the transport of NEP to the brain has not been investigated. Our hypothesis is that muscle packages NEP in exosomes in response to a neuromuscular signal and sends it to the brain via retrograde axonal transport. The masseter muscle (MM) and the trigeminal nerve (TGN) are good candidates for this mechanism by virtue of their proximity to the brain. The aim of this study was to trace the NEP protein from the MM, through the TGN, and to the hippocampus (HPC) in muscle contraction models in vitro and in vivo. NEP expression in mouse tissue lysates was analyzed by RT-PCR and Western blot. Four-week-old mice were perfused to remove blood NEP contamination. The MM expressed substantial levels of NEP protein and mRNA. On the other hand, a remarkably high level of NEP protein was measured in the TGN in the absence of mRNA. NEP protein, without the corresponding mRNA, was also detected in the HPC. These results suggested that the MM derived NEP was taken up by the TGN, which in turn permitted NEP access to the central nervous system and within it the HPC. When the MM was induced to contract by electric stimulation in freshly euthanized mice, NEP protein decreased in the MM in a stimulus time-dependent manner, while that in the TGN and the HPC increased sequentially. Furthermore, NIR-labeled exosomes tracked along the same route. Finally, carbachol induced secretion of exosomal NEP in C2C12-derived myotube cells. These results support our hypothesis that MM-derived NEP is transported along the TGN to reach the HPC following electrical or cholinergic stimulation.

Establishment of immortalized mesenchymal stem cells derived from the submandibular glands of tdTomato transgenic mice.

Transgenic mice that overexpress the red fluorescent protein tdTomato (tdTomato mice) are well suited for use in regenerative medicine studies. Cultured cells from this murine model exhibit strong red fluorescence, enabling real-time in vivo imaging through the body surface of grafted animals. Mesenchymal stem cells (MSCs) have marked potential for use in cell therapy and regenerative medicine; however, the mechanisms that regulate their dynamics in vivo are poorly understood. In the present study, an MSC line was derived from the submandibular gland fibroblasts of tdTomato mice. The fluorescent signal from this cell line was observed in organs throughout the body, as well as in salivary glands. Primary culture cells derived from the submandibular gland were immortalized with SV40 large T antigen (GManSV cells); these cells exhibited increased migratory ability, as compared with those isolated from the sublingual gland. GManSV cells were tdTomato-positive and exhibited spindle-shaped fibroblastic morphology; they also robustly expressed mouse MSC markers: Stem cell antigen-1 (Sca-1), CD44, and CD90. This cell line retained multipotent stem cell characteristics, as evidenced by its ability to differentiate into both osteogenic and adipogenic lineages. These results indicate that Sca-1+/CD44+/CD90+-GManSV cells may be useful for kinetic studies of submandibular gland-derived MSCs in the context of in vitro co-culture with other types of salivary gland-derived cells. These cells may also be used for in vivo imaging studies, in order to identify novel cell therapy and regenerative medicine for the treatment of salivary gland diseases.