Restauração em resina composta semidireta em dente posterior: relato de caso / Semi-direct composite restoration in posterior toth: a case report

A escolha da técnica restauradora desempenha papel fundamental na eficácia e duração de um tratamento reabilitador. O objetivo deste relato de caso foi descrever a utilização da técnica semidireta para a confecção de uma restauração em resina composta em um primeiro molar inferior. A paciente apresentava uma restauração insatisfatória no dente 36, que necessitava ser substituída devido à infiltração por cárie. Optou-se pela técnica semidireta devido à amplitude da cavidade, que envolvia estruturas de suporte, e pela combinação das vantagens das abordagens direta e indireta. O procedimento envolveu a remoção de tecido cariado, a aplicação de hidróxido de cálcio pasta, seguida da aplicação de uma fina camada de ionômero de vidro e, posteriormente, resina fluída para realizar o selamento dentinário. O preparo foi realizado seguindo os princípios necessários. O elemento em questão foi moldado com silicone de adição e o arco antagonista, com alginato. Ambos modelos foram vertidos com silicone para modelos semirrígidos e montados em oclusor de peças de brinquedo. A restauração semidireta foi confeccionada em resina composta Filtek Z350 XT, respeitando a anatomia do dente 36. Pigmentos foram utilizados para aprimorar detalhes estéticos. Após acabamento e polimento, a peça foi condicionada e cimentada com cimento dual Relyx Ultimate. Pode-se concluir que a abordagem restauradora por meio da técnica semidireta construída em modelo semirrígido é uma opção terapêutica conservadora e vantajosa para dentes com extensa destruição coronária. Essa técnica possibilita a restauração de forma eficaz, garantindo tanto a estética quanto a função adequada do dente afetado(AU)

The choice of restorative technique plays a fundamental role in the effectiveness and duration of rehabilitation treatment. The objective of this case report was to describe the use of the semi-direct technique to create a composite resin restoration in a lower first molar. The patient had an unsatisfactory restoration on tooth 36, which needed to be replaced due to cavity infiltration. The semi-direct technique was chosen due to the amplitude of the cavity, which involved support structures, and the combination of advantages of the direct and indirect approaches. The procedure involved the removal of carious tissue, and the application of calcium hydroxide paste, followed by the application of a thin layer of glass ionomer and, subsequently, fluid resin to seal the dentin. The preparation was carried out following the necessary principles. The element in question was molded with addition silicone and the antagonist arch was molded with alginate. Both models were poured with silicone for semi-rigid models and mounted on toy parts occluders. The semi-direct restoration was made in Filtek Z350 XT composite resin, respecting the anatomy of tooth 36. Pigments were used to improve aesthetic details. After finishing and polishing, the piece was conditioned and cemented with Relyx Ultimate dual cement. It can be concluded that the restorative approach using the semi-direct technique built on a semi-rigid model is a conservative and advantageous therapeutic option for teeth with extensive coronal destruction. This technique allows for effective restoration, ensuring both the aesthetics and adequate function of the affected tooth(AU)

Bovine and Ovine Teeth as a Substitute for the Human Teeth: An Experimental Study.

Statement of the Problem: Although various kinds of research have been conducted to compare the physical and chemical properties of dentin and enamel in animal and human samples, proving the ability of animal dentin material as a good substitute for human specimens is always a challenge for experimental studies. Purpose: The aim of the present study is to investigate whether the changes in the dentin microhardness of animal samples are similar to those of human samples or not. Materials and Method: In this in vitro study, sixty single-rooted human, bovine, and ovine teeth (n=20 in each group) were decoronated at CEJ. The remaining roots were embedded in acrylic resin and a cross-section cut was made in the middle of the samples in order to achieve dentin disks. All of the 120 samples were randomly assigned to three control (n=20 for each group) and three experimental groups (n=20 for each group). In the experimental groups, calcium hydroxide with a creamy consistency was prepared and the disks were embedded in dishes containing calcium hydroxide. Control groups were embedded in physiological saline. The samples were incubated for seven days at the 37oC and Vickers microhardness test was performed immediately. The average of three yielded values was considered as the final value of microhardness. Data were analyzed using two-way ANOVA, one-way ANOVA, and Tukey's post hoc tests. Results: In the control group, the human samples showed the highest microhardness value, while the bovine teeth had the lowest microhardness value (p< 0.001). In the calcium hydroxide group, the human samples showed the highest microhardness value in comparison to bovine and ovine to teeth. However, no significant difference was observed between the bovine and ovine samples in microhardness value. Conclusion: Based on our research, substituting bovine and ovine samples with human samples in experimental studies is not recommended. Nevertheless, more studies are needed in this regard.

Clinical and radiographic success rate of the root canal filling materials used in primary teeth: A systematic review.

One of the most important factors that determine the success of pulpectomy in primary teeth is the root canal filling material used. This systematic review is an update on the success rates of various materials used for obturation in primary teeth. An electronic search was carried out in the PubMed, Scopus, Web of Science, and Cochrane Library databases with the preset inclusion and exclusion criteria. Only randomized or quasi-randomized clinical and controlled trials with a minimum follow-up of 12 months were included for analysis. Nine articles were considered potentially eligible for inclusion in this review. All the included trials had zinc oxide-eugenol (ZOE) cement as a control group. The time span of the included trials extended from 12 to 30 months. Only 2 trials were at low risk of bias. Evidence to support the success rates of obturating materials used in primary teeth is scarce, which necessitates further highquality randomized controlled clinical trials with regard to this issue.

Novel approach for characterizing clinical load application of superelastic orthodontic wires.

OBJECTIVE: Current standardized in vitro bending experiments for orthodontic archwires cannot capture friction conditions and load sequencing during multi-bracket treatment. This means that clinically relevant forces exerted by superelastic wires cannot be predicted. To address these limitations, this study explored a novel test protocol that estimates clinical load range. METHODS: The correction of a labially displaced maxillary incisor was simulated using an in vitro model with three lingual brackets. Deflection force levels derived from four different protocols were designed to explore the impact of friction and wire load history. These force levels were compared in nickel-titanium (NiTi) archwires with three commonly used diameters. The unloading path varied between protocols, with single or multiple sequences and different load orders and initial conditions. RESULTS: Deflection forces from the new protocol, employing multiple continuous load/unload cycles (CCincr), consistently exceeded those from the conventional protocol using a single continuous unloading path (CUdecr). Mean differences in plateau force ranged from 0.54 N (Ø 0.014" wire) to 1.19 N (Ø 0.016" wire). The CCinr protocol also provided average force range estimates of 0.47 N (Ø 0.012" wire), 0.89 N (Ø 0.014" wire), and 1.15 N (Ø 0.016" wire). SIGNIFICANCE: Clinical orientation towards CUdecr carries a high risk of excessive therapeutic forces because clinical loading situations caused by friction and load history are underestimated. Physiological tooth mobility using NiTi wires contributes decisively to the therapeutic load situation. Therefore, only short unloading sequences starting from the maximum deflection in the load history, as in CCincr, are clinically meaningful.

Spontaneous Eruption of Permanent Teeth That Had Eruption Disturbances After Extirpation of Odontomas: A Report of Two Cases.

Odontomas, often found adjacent to impacted teeth, are tumors of abnormal tissue morphology arising from the tooth germ and are usually asymptomatic. They are often found by accident on X-ray images, and the eruption of permanent teeth is often caused by odontomas. In most cases, the tooth is extracted with the permanent tooth or orthodontic treatment is performed after extraction. However, the criteria are not clear. We encountered two cases of dental eruption in which permanent teeth, which originally seemed to be suitable for orthodontic treatment, spontaneously erupted after odontoma removal. It is necessary to examine the indications and timing of tooth extraction.

Extracellular Matrix Remodelling of the Periodontium under Orthodontic Force.

As the biological mechanisms of orthodontic tooth movement have been explored further, scholars have gradually focused on the remodelling mechanism of the extracellular matrix (ECM) in the periodontal ligament (PDL). The ECM of the PDL consists of various types of collagens and other glycoproteins. The specific process and mechanism of ECM remodelling during orthodontic tooth movement remains unclear. Collagen I and III, which constitute major components of the PDL, are upregulated under orthodontic force. The changes in the contents of ECM proteins also depend on the expression of ECM-related enzymes, which organise new collagen fibre networks to adapt to changes in tooth position. The matrix metalloproteinase family is the main enzyme that participates in collagen hydrolysis and renewal and changes its expression under orthodontic force. Moreover, ECM adhesion molecules, such as integrins, are also regulated by orthodontic force and participate in the dynamic reaction of cell adhesion and separation with the ECM. This article reviews the changes in ECM components, related enzymes and adhesion molecules in the PDL under orthodontic force to lay the foundation for the exploration of the regulatory mechanism of ECM remodelling during orthodontic tooth movement.

Knowledge, attitudes, and practices among patients with combined dentition defect and non-functional impacted teeth toward tooth autotransplantation.

BACKGROUND: Tooth autotransplantation (TAT) is a surgical procedure involving the extraction of a tooth from one location and its subsequent transplantation into another alveolar socket within the same individual. This innovative treatment approach holds significant promise. Nonetheless, the potential recipients exhibit a limited level of awareness and understanding of this procedure. This study investigated the knowledge, attitudes, and practices (KAP) among patients with combined dentition defects and non-functional impacted teeth toward TAT. METHODS: This web-based cross-sectional study was conducted between December 2022 and February 2023 at one hospital. A self-designed questionnaire was developed to collect demographic information of the patients and assess their knowledge, attitudes, and practices toward TAT. RESULTS: A total of 533 valid questionnaires were collected. The mean knowledge, attitude, and practice scores were 5.55 ± 2.38 (possible range: 0-10), 26.82 ± 2.46 (possible range, 8-40), and 27.45 ± 7.40 (possible range, 9-45), respectively. CONCLUSION: The participants had insufficient knowledge, negative attitudes, and passive practices toward TAT. Targeted interventions should be implemented to improve the understanding and practice of TAT among patients with dentition defects.

Pain and root resorption due to surgical interventions to accelerate tooth movement in orthodontics: A systematic review and meta-analysis.

BACKGROUND: There are several publications that show the efficacy of surgical interventions in accelerating the rate of tooth movement in orthodontics. Consequently, possible adverse effects must also be evaluated. OBJECTIVES: The aim of the present study was to compare the perception of pain and root resorption between orthodontic treatment with a surgical acceleration intervention vs. conventional orthodontic treatment. MATERIAL AND METHODS: An electronic search was conducted in the MEDLINE, Scopus, Web of Science (WoS), ScienceDirect, Cochrane Library, and Virtual Health Library (VHL) databases up to September 12, 2022. Randomized or non-randomized, controlled, parallel-arm or split-mouth clinical trials were included. Fixed-and random-effects meta-analyses were performed with regard to heterogeneity. The risk of bias (RoB) was assessed using the RoB 2.0 and ROBINS-I tools. RESULTS: A total of 1,395 articles were initially retrieved, 40 studies were finally included in the review and 15 studies were eligible for quantitative analysis. The meta-analysis showed a significant difference in pain perception between acceleration surgery vs. conventional orthodontics at 24 h (p = 0.040); however, this difference was not significant at 7 days (p = 0.080). Overall, the patients who underwent any acceleration procedure presented significantly less resorption as compared to those who were applied conventional treatment (p < 0.001). A similar significant difference was found in retraction movements (p < 0.001) and alignment movements (p = 0.030). CONCLUSIONS: In the first 24 h, surgical interventions for the acceleration of tooth movement produce a greater perception of pain as compared to conventional orthodontic treatment, but the perception is similar after 7 days. Acceleration surgery results in less root resorption - in alignment movements, and especially in retraction movements.

Teeth and alveolar bones as tracers of metals and radionuclides in inhabitants of a uranium region.

Biodosimetry can define risks in inhabitants of areas with potential contaminants, ensuring environmental protection and living conditions due to toxic and radioactive effects. This study aimed to evaluate metals and radionuclides in dental structures and alveolar bones in residents of a uranium area in Paraíba and Pernambuco, Brazil. Eighty-nine specimens were pulverized, fractionated, and chemically prepared for analysis by EDXRF, FAAS, and ICP-MS. Levels of Ca, Cu, Fe, Si, Mn, Ni, Pb, Sr, Ti, V, Zn, K, Mn, Th, and U were investigated. Higher concentrations were measured for Ca, with an average of 272,986.4 mg kg-1. Ni presented in lower concentrations, with an average of 30.4 mg kg-1. For U, concentrations ranged from 1.5 to 145.0 mg kg-1, with more than 27% of the samples above the reference value of 8.1 µg kg-1. For Th, almost 38% of the results were above the limit of 3.5 µg kg-1. In the bone spicules, the contents of U and Th ranged from 45.1 to 1451.2 µg kg-1 and from 7.5 to 78.4 µg kg-1, in this order. The levels of radionuclides were more expressive for the teeth collected in São José do Sabugi, suggesting contamination through food and water consumption. In the bone spicules, the levels of U were up to 179 times higher than the safety limit. The results indicate a possible risk of contamination with probable induced radiobiological effects.

The association of composite dietary antioxidant index with periodontitis in NHANES 2009-2014.

Background: To date, evidence is rare regarding whether and how dietary antioxidants are associated with the risk of periodontitis. This study aimed to investigate the association of composite dietary antioxidant index (CDAI) with periodontitis and tooth loss, using data from the National Health and Nutrition Examination Survey (2009-2014). Methods: A cross-sectional analysis was conducted using data from 10,067 adults aged ≥30 years who underwent assessments of periodontal health and the 1st day dietary recall. Based on a crude model and three adjusted models, multivariate regressions were used to examine the relationship between CDAI and periodontitis-related measurements including probing pocket depth, clinical attachment loss and tooth loss. Subgroup analyses and the restricted cubic splines plots were applied to examine the association between CDAI ingredients and periodontitis. Results: For the subjects with high CDAI scores, increased CDAI was associated with significant (P < 0.05) reduction of severe periodontitis (odd ratio = 0.663, 95% confidence interval: 0.491-0.896) and increased number of remaining teeth (weighted ß[SE] = 1.167[0.211]). However, the protective effect of CDAI on periodontitis vanished (P > 0.05) in active smokers and former smokers. There were threshold levels for ß-carotene, Vitamin A, C and E intakes where the risk of periodontitis significantly decreased (P < 0.05) above these levels. Conclusion: Increased CDAI was associated with reduced risk of periodontitis and tooth loss for non-smokers. It was recommendable that proper dietary intakes of ß-carotene, Vitamin A, C and E would be of benefit for preventive dental care and adjuvant therapies for periodontitis.

Ten-year prognostic outcomes of molar survival using the Miller-Mcentire Periodontal Prognostic Index - A longitudinal prospective study.

Background: A 10-year survival analysis was performed to assess the predictive validity of the periodontal risk score (formerly known as Miller-McEntire Periodontal Prognostic Index [MMPPI]) to predict long-term survival of periodontally diseased molars in a longitudinally assessed cohort. Materials and Methods: The MMPPI scores were computed at baseline by summarizing scores allocated for individual factors. The cohort was treated, followed up, and placed under regular periodontal maintenance. Molar survival data collected up to 10 years of follow-up were analyzed. Cox proportional regression was performed, and hazards ratio (HR) were computed for each prognostic factor and the MMPPI score. To estimate the predictive value of MMPPI, a receiver operating curve (ROC) curve analysis was performed. Results: From 1032 molars, 155 molars were extracted over the 10-year follow-up duration. Cox proportional hazard analysis showed significant hazard ratios for tooth loss for the component variables significant HR was noted for age: 4.92 (3.34:7.27), smoking: 1.74 (1.38-2.22), diabetes: 1.66 (1.49-1.86), molar type: 1.39 (1.15-1.67), probing depth: 2.00 (1.63-2.46), furcation: 2.64 (2.30-3.03), mobility: 3.45 (2.98-4.01), and total MMPPI score: 1.98 (1.85-2.12). ROC curve analysis showed an area under the curve value of 0.94 for the MMPPI index as a predictor of molar loss at 8 years, and the Youden index was maximized at the optimal cutoff point score of 7. Conclusions: All component scores of MMPPI showed significant hazard ratios at 10 years. These findings support the previous results from the 5-year analysis of this university-based cohort and warrant validation in independent cohorts.

Management of a bulbous blunderbuss maxillary central incisor with one root and three canals in a patient with cleft lip and palate.

Unique anatomical deviations in canal structure are rare in anterior teeth, especially central incisors, and thus risk being overlooked. For successful intervention, a meticulous diagnostic procedure and treatment plan, significantly aided by cone-beam computed tomography (CBCT), are crucial. The case at hand explores the management of a maxillary left central incisor in a cleft palate patient, characterized by multiple developmental lobes, a bulbous crown, and an atypical root anatomy. The primary symptom was pain, accompanied by a history of trauma at age 8 years and ensuing tooth discoloration. Initial evaluations, augmented by CBCT, revealed pulpal necrosis in a single-rooted tooth with three distinct canals. Initial clinical examination was supplemented by electrical pulp testing, RadioVisioGraphy (RVG), and CBCT, after which the root canal therapy was initiated. Informed consent was obtained from the patient. The access cavity preparation resulted in a three-orifice cavity. Subsequently, the canals were enlarged and sufficiently debrided. Calcium-hydroxide was applied for 2 weeks before the commencement of apexification and obturation, followed by esthetic rehabilitation. This case highlights the importance of recognizing rare anatomical variations in anterior teeth and demonstrates the invaluable role of CBCT in both diagnosing and managing such complexities.

Modeling fracture in multilayered teeth using the finite volume-based phase field method.

The present work, utilizing the finite volume-based phase field method (FV-based PFM), aims to investigate the initiation and propagation of cracks in the second molar of the left mandible under occlusal loading. By reconstructing cone beam computed tomography scans of the patient, the true morphology and internal mesostructure of the entire tooth are implemented into numerical simulations, including both 2D slice models and a realistic 3D model. Weibull functions are introduced to represent the tooth's heterogeneity, enabling the stochastic distribution characteristics of mechanical parameters. The results indicate that stronger heterogeneity leads to greater crack tortuosity, uneven damage distribution, and lower fracture stress. Additionally, different cusp angles (50° and 70°) and pre-existing fissure morphologies (i.e., U-shape, V-shape, IK-shape, I-shape, and IY-shape) also significantly affect the mechanical performance of the tooth. The study reveals that different cusp angles affect the location of crack initiation. Overall, this work demonstrates the utility of the FV-based PFM framework in capturing the complex fracture behavior of teeth, which can contribute to improved clinical treatment and prevention of tooth fractures. The insights gained from this study can inform the design of dental crown restorations and the optimization of cusp inclination and contact during clinical occlusal adjustments.

Personalized 3D Printed Tooth-Supported Template as a Novel Strategy for Radiofrequency Thermocoagulation for Trigeminal Neuralgia After the Failure of CT-Guided Puncture.

Background: Trigeminal neuralgia (TN) is a common form of craniofacial pain, and Radiofrequency thermocoagulation (RFT) has become a commonly utilized treatment modality for TN. However, the complex anatomical configuration of the maxillofacial region and the difficulties inherent in positioning the neck in a hyperextended manner can present challenges for CT-guided punctures. Aim: The objective of this study is to assess the effectiveness and safety of 3D printed tooth-supported template(3D-PTST) guided RFT in patients who have previously undergone unsuccessful CT-guided puncture. Methods: Patients with TN undergoing RFT at the Department of Pain Medicine, PLA General Hospital, from January 2018 to January 2023, were assessed. 3D-PTST guided RFT was employed as an alternative when percutaneous puncture failed. Clinical, demographic, and follow-up data were collected. The duration of the procedure was determined by subtracting the time of anesthesia administration from the time of surgical drape removal. Pain intensity was assessed using the Numerical Rating Scale-11 scale. Treatment effects were evaluated utilizing the Barrow Neurological Institute scale. Incidences of complications related to RFA were documented. Results: Six TN patients underwent 3D-PTST guided RFT. With tooth-supported template guidance, five patients achieved therapeutic target puncture in one attempt with one CT scan. One patient required two attempts with two CT scans. Operation duration ranged from 18 to 46 mins (mean 30 mins). All completed 3D-PTST-guided RFT without difficulty, significantly improving pain symptoms. Four patients had no pain recurrence at 12, 18, 36 and 37 months follow-up, respectively. Recurrence occurred in two patients (at 1 and 13 months). No serious treatment-related complications were observed. Conclusion: 3D-PTST guided RFT is an effective, repeatable, safe, and minimally invasive treatment method for patients with TN who have failed due to difficulty in puncture.

Effects of different tooth movement patterns and aligner thicknesses on maxillary arch expansion with clear aligners: a three-dimensional finite element study.

Objectives: The objective of this study was to investigate the biomechanical effects of different tooth movement patterns and aligner thicknesses on teeth and periodontal tissues during maxillary arch expansion with clear aligners, to facilitate more precise and efficient clinical orthodontic treatments. Methods: Three-dimensional models including teeth, maxilla, periodontal ligament, and aligner were constructed and subjected to finite element analysis. Tooth displacement trends and periodontal ligament stresses were measured for seven tooth displacement patterns (divided into three categories including overall movement of premolars and molars with gradually increasing molar expansion in each step; distributed movement of premolars and molars; and alternating movement between premolars and molars at intervals) and two aligner thicknesses (0.5 mm and 0.75 mm) during maxillary arch expansion with clear aligners. Results: When expanding the maxillary arch with clear aligners, the effective expansion of the target teeth mainly showed a tilting movement trend. Increasing the amount of molar expansion increased the buccal displacement of the first molar but decreased the buccal displacement of the premolars. The mean buccal displacement of the target teeth was greater in the posterior teeth interval alternating movement group (0.026 mm) than in the premolar/molar distributed movement group (0.016 mm) and the overall movement group (0.015 mm). Increasing aligner thickness resulted in greater buccal displacement of the crowns and increased stress on the periodontal ligaments. Conclusion: Increasing the amount of molar expansion reduces the efficiency of premolar expansion. Alternating movement of premolars and molars at intervals achieves a higher arch expansion efficiency, but attention should be paid to the anchorage of adjacent teeth. Increasing the thickness of the aligner increases the expansion efficiency but may also increase the burden on the periodontal tissues.

Number of teeth and functional disability in community-dwelling older adults.

INTRODUCTION: This study determined whether tooth loss was associated with the development of functional disability and estimated the population attributable fraction (PAF) of functional disability due to tooth loss, along with risk factors for functional disability such as physical function and cognitive impairment. METHODS: The participants were 838 community-dwelling older adults aged ≥70 years living in the Tsurugaya district in Japan in 2003. The exposure variable was the number of remaining teeth (counted by trained dentists). Other variables were age, sex, depressive symptoms, cognitive impairment, educational attainment, physical function and social support. The Cox proportional hazards model was applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of the incidence of functional disability for each risk factor, such as tooth loss. The functional disability PAF due to tooth loss was estimated, and risk factors for functional disability were identified. RESULTS: In total, 619 (73.9%) participants developed functional disability during follow-up. A multivariable model showed that those with <20 teeth (HR, 1.28; 95% CI, 1.08-1.53) were more likely to develop functional disability than those with 20 teeth or more. PAF estimation for functional disability was shown to have decreasing values in the following order: age, female sex, tooth loss and reduced physical function. CONCLUSIONS: Tooth loss was associated with the development of functional disability in community-dwelling older Japanese adults. While retaining teeth may be a potential strategy for avoiding functional disability, clinical studies on the effect of dental treatment on preventing functional disability are warranted.

A nomogram-based predictive model for tooth survival in Chinese patients with periodontitis: An 11-year retrospective cohort study.

AIM: To develop a nomogram-based predictive model of tooth survival by comprehensively analysing clinical and radiographic risk factors of tooth loss (TL). MATERIALS AND METHODS: In this study, 3447 teeth of 131 subjects who underwent non-surgical periodontal treatment were examined retrospectively within a mean follow-up period of 11.6 years. The association of risk factors including clinical and radiographic parameters with TL was assessed using univariate and multivariate Cox regression analyses. A nomogram-based predictive model was developed, and its validation and discriminatory ability were analysed. RESULTS: In all, 313 teeth were lost in 94 patients in this study (overall tooth loss [OTL] 9.08%; 0.21 teeth/patient/year). Male, heavy smoking, molar teeth, probing depth (PD), attachment loss (AL), tooth mobility and radiographic bone loss were significantly associated with TL (p < .05). A gradient effect of tooth mobility on TL increased from degree I to III versus none (p < .0001). The area under the curve (AUC) of the model was 0.865. Calibration curve and decision curve analysis demonstrated good performance and high net benefit, respectively. CONCLUSIONS: Adopting a specific nomogram could facilitate the prediction of tooth survival and the development of tailored treatment plans in Chinese patients with advanced periodontitis.

Influence of remaining coronal tooth morphology with resin abutment and fiber post on static and dynamic fracture resistances.

This study aimed to clarify the fracture resistance of resin abutments built on endodontically treated roots with the remaining coronal teeth via static and cyclic loading tests. Endodontically treated bovine roots, which had a remaining coronal tooth covered with an occupied area for a quarter and half of the circumference at the tensile side or covered the circumference at both the tensile and compressive sides, were fabricated to build up to the resin abutment. Fracture resistance was evaluated via static and cyclic loading tests by applying a load of 30° to the tooth axis. Half of the circumference of the remaining coronal tooth showed a significantly higher static fracture load and survival rate. The remaining coronal tooth on the compressive side improved the dynamic fracture resistance associated with severe fractures. The occupied area and location of the remaining coronal tooth affected the static and dynamic fracture resistances.

Comprehensive analysis of transcription factors involved in odontoblast differentiation mechanism.

Primary cultured odontoblasts rapidly lose their tissue-specific phenotype. To identify transcription factors (TF) that are important for the maintenance of the odontoblast phenotype, primary cultures of C57BL/6 J mouse dental mesenchymal cells (DMC) were isolated, and expression of TF and odontoblast marker genes in cells immediately after isolation and 2 days after culture were comprehensively evaluated and compared using RNA-sequencing (RNA-seq). The expression of odontoblast markers in mouse dental mesenchymal cells decreased rapidly after isolation. In addition, the expression of Hedgehog-related, Notch-related, and immediate- early gene (IEG)-related transcription factors significantly decreased. Forced expression of these genes in lentiviral vectors, together with fibroblast growth factor 4 (FGF4), fibroblast growth factor 9 (FGF9), and the Wnt pathway activator CHIR99021, significantly induced the expression of odontogenic marker genes. These results indicate, for the first time, that Notch signaling and early genes may be important for maintaining odontoblast cultures. Furthermore, simultaneous stimulation of FGF, Wnt, Hedgehog, Notch pathways, and IEG transcription factors cooperatively promoted the maintenance of the odontoblast phenotype. These results suggest that the Hedgehog and Notch signaling pathways may play an important role in maintaining odontoblast phenotypes, in addition to FGF and Wnt signaling.

Association between masticatory function and depression in older adults: Results from NHANES 2009 to 2018.

AIM: Depression is prevalent among older adults. Although the number of missing teeth is considered to be associated with depression, the relationship between masticatory function, which is usually indicated by functional tooth units (FTUs), and depression in older adults remains unclear. MATERIALS AND METHODS: This study used data from the National Health and Nutrition Examination Survey (NHANES) 2009-2018. The number of FTUs was defined as pairs of opposing natural and artificial teeth. Depression was accessed using the Patient Health Questionnaire (PHQ-9), and participants who scored ≥10 on PHQ-9 were diagnosed with depression. Logistic regression analyses, propensity score matching (PSM) analyses and subgroup analyses were conducted to assess the association between FTU and depression. RESULTS: The analysis included 5764 individuals over 60 years. An association between FTU and the risk of depression among older adults was detected (odds ratio [OR] = 0.951, 95% confidence interval [CI] 0.915-0.989), suggesting protective roles of more FTUs. Significant increase in the risk of depression in 0 ≤ FTUs ≤ 3 was observed compared with 10 ≤ FTUs ≤ 12 (OR = 1.819, 95% CI 1.157-2.858). However, no significant increase in the risk of depression in 4 ≤ FTUs ≤ 9 was found. After PSM, significant increase in the risk of depression in 0 ≤ FTUs ≤ 3 was still detected compared with 4 ≤ FTUs ≤ 12 (OR = 1.484, 95% CI 1.030-2.136). Subgroup analyses demonstrated consistent results in all subgroups, except for individuals aged 76-80 and drinking regularly. CONCLUSIONS: The findings suggested the association between impaired masticatory function and the risk of depression among older adults. Longitudinal studies are needed to elucidate the role of masticatory function impairment in the development of depression further.