Three-dimensional visualization of the alveolar bone and posterior superior alveolar foramen in gender.

The present study applied a three-dimensional (3D) program to measure the distances from the maxillary sinus floor (MSF) to the lingual and buccal alveolar bone and also to the posterior superior alveolar foramen (PSAF), with the aim of determining differences according to gender. The study also attempted to verify the accuracy of measurements obtained from 3D images by performing comparisons with the results obtained in a preliminary study. The results showed that the alveolar bone length and the MAF-PSAF were generally larger in males than in females. It is also predicted that the accuracy of data obtained from a 3D program will be higher than that of data derived from conventional two-dimensional (2D) images. The accurate measurements obtained in this study are anticipated to prove useful in assessments related to dental implantation and anatomical structures. The fundamental data obtained in this study may also assist in setting the goals of future studies utilizing 3D programs.

Dental optical coherence tomography: new potential diagnostic system for cracked-tooth syndrome.

PURPOSE: The aim of the present study was to determine the reliability of optical coherence tomography (OCT) in detecting cracked teeth and its relative clinical effectiveness by comparing it with other diagnostic methods including conventional visual inspection, trans-illumination, and micro-computed tomography (micro-CT). METHODS: The reliability of swept source OCT (SS-OCT) was verified by comparing the number of detected crack lines on 109 surfaces of 61 teeth with those detected with other conventional methods. RESULTS: One to one comparison revealed that crack lines that were invisible with naked eyes could be found in SS-OCT images. The detection ability of SS-OCT was superior or similar to those of micro-CT (100.0 %) and trans-illumination. CONCLUSIONS: Crack lines shown in the SS-OCT images had distinct characteristics, and structural crack lines and craze lines could be distinguished in SS-OCT images. Thus, the detection ability of SS-OCT renders it an acceptable diagnostic device for cracked-tooth syndrome.

Quantitative anatomical analysis of facial expression using a 3D motion capture system: Application to cosmetic surgery and facial recognition technology.

The topography of the facial muscles differs between males and females and among individuals of the same gender. To explain the unique expressions that people can make, it is important to define the shapes of the muscle, their associations with the skin, and their relative functions. Three-dimensional (3D) motion-capture analysis, often used to study facial expression, was used in this study to identify characteristic skin movements in males and females when they made six representative basic expressions. The movements of 44 reflective markers (RMs) positioned on anatomical landmarks were measured. Their mean displacement was large in males [ranging from 14.31 mm (fear) to 41.15 mm (anger)], and 3.35-4.76 mm smaller in females [ranging from 9.55 mm (fear) to 37.80 mm (anger)]. The percentages of RMs involved in the ten highest mean maximum displacement values in making at least one expression were 47.6% in males and 61.9% in females. The movements of the RMs were larger in males than females but were more limited. Expanding our understanding of facial expression requires morphological studies of facial muscles and studies of related complex functionality. Conducting these together with quantitative analyses, as in the present study, will yield data valuable for medicine, dentistry, and engineering, for example, for surgical operations on facial regions, software for predicting changes in facial features and expressions after corrective surgery, and the development of face-mimicking robots.

Perioral soft tissue evaluation of skeletal Class II Division 1: A lateral cephalometric study.

INTRODUCTION: To obtain the balance and harmony of the soft tissue facial profile in orthodontic treatment, it is necessary to identify the characteristics of overlying soft tissues according to the horizontal and vertical skeletal patterns. The aim of this study was to evaluate the perioral soft tissue characteristics of skeletal Class II Division 1 subjects (group II) with various vertical patterns compared with skeletal Class I subjects (group I). METHODS: Lateral cephalograms of 99 Korean adults (44 women, 45 men; mean age, 23.4 years) were divided into 4 groups based on horizontal and vertical skeletal pattern (SN-MP angle): group I, 22 subjects; group II-low angle (<27°), 14 subjects; group II-normal angle (27°-36°), 33 subjects; and group II-high angle (>37°), 30 subjects. The correlations and multiple linear regression tests were used to determine the skeletal and dental variables influencing soft tissue characteristics. RESULTS: Group II-high angle showed significantly greater values than did group II-low angle for basic lower lip thickness and lower lip length. The perioral soft tissue measurements of group II were correlated with the inclination and anteroposterior position of the maxillary and mandibular incisors along with facial depth (N-Go) and facial length (S-Gn). Upper lip strain of group II was not influenced by any skeletal variables but only by the inclination and anteroposterior position of the maxillary incisors. CONCLUSIONS: Clinicians need to evaluate lip strain and lip thickness based on the skeletal pattern as well as dental inclination to obtain balance in the perioral muscle activity.

Comparison of Nasal Dimensions According to the Facial and Nasal Indices Using Cone-Beam Computed Tomography.

The nasal cavity constitutes the foremost portion of the respiratory system, composed of the anterior nasal aperture, nostrils, and choanae. It has an intricate anatomical structure since it has various functions, such as heat exchange, humidification, and filtration. Accordingly, clinical symptoms related to the nose, such as nasal congestion, snoring, and nasal septal deviation, are closely linked to the complex anatomical structure of the nasal cavity. Thus, the nasal cavity stands as a paramount structure in both forensic and clinical contexts. The majority of relevant studies have performed comparisons between sexes, with studies making comparisons according to the FI and NI only and examining relative percentages. Furthermore, the nasal cavity was measured in 2D, and not 3D, in most cases. In this study, we conducted a 3D modeling and anthropometric assessment of the nasal cavity using a 3D analysis software. Furthermore, we aimed to investigate whether the size of the nasal cavity differs according to sex, facial index (FI), and nasal index (NI). We retrospectively reviewed the cone-beam computed tomography (CBCT) data of 100 participants (50 males, 50 females) aged 20-29 years who visited the dental hospital of Dankook University (IRB approval no. DKUDH IRB 2020-01-007). Our findings showed that nasal cavity sizes generally differed according to sex, FI, and NI. These findings provide implications for performing patient-tailored surgeries in clinical practice and conducting further research on the nasal cavity. Therefore, we believe that our study makes a significant contribution to the literature.

Evaluation of stability changes in magnesium-incorporated titanium implants in the early healing period.

The aim of the present study was to determine the bone response to magnesium (Mg) ion-incorporated titanium (Ti) implants during the early healing period. A total of 114 patients (69 men and 45 women aged between 29 and 71 years) participated in the study. Overall, one hundred thirty-three 10-mm-long fixtures were installed, composed of 65 Mg ion-incorporated fixtures in the test group (55 participants; 30 males and 25 females) and 68 resorbable blast media (RBM) surface fixtures in the control group (59 participants; 39 males and 20 females). The bone responses were evaluated by resonance frequency analysis (RFA) at the following time points after implant insertion (ie, the healing period): 0, 2, 4, 8, and 12 weeks. Each time an RFA measurement was taken, the stability changes relating to both bone quality and implant arch location (maxilla or mandible) were recorded for further analysis. The mean stabilities were lowest at week 4 of healing for both the test and control groups. Significant differences in RFA values between the 2 groups were found at week 12 of healing. The mean percentage change in implant stability quotient (ISQ) from the baseline revealed that the implant stability of the Mg ion-incorporated test group had increased (4.55%) more than the RBM surface group (2.23%) by week 12 of healing. With respect to bone quality, the mean ISQ of Mg-incorporated Ti implants only changed significantly during the 12-week period for type 4 bone. Furthermore, at weeks 4 and 12 of healing, significant differences were found between the 2 groups for type 2 and type 4 bone. A comparison of the stability patterns of mandibular and maxillary implants revealed that the overall stability was higher in the mandible; however, no significant difference was found for Mg-incorporated Ti implants. The Mg-incorporated Ti implants exhibited a slightly better bone response with respect to ISQ than did the RBM surface implants, and the percentage change in mean ISQ from the baseline was greater for the Mg-incorporated group than for the RBM surface group at the end point of this study.

Realization of masticatory movement by 3-dimensional simulation of the temporomandibular joint and the masticatory muscles.

Masticatory muscles are closely involved in mastication, pronunciation, and swallowing, and it is therefore important to study the specific functions and dynamics of the mandibular and masticatory muscles. However, the shortness of muscle fibers and the diversity of movement directions make it difficult to study and simplify the dynamics of mastication. The purpose of this study was to use 3-dimensional (3D) simulation to observe the functions and movements of each of the masticatory muscles and the mandible while chewing. To simulate the masticatory movement, computed tomographic images were taken from a single Korean volunteer (30-year-old man), and skull image data were reconstructed in 3D (Mimics; Materialise, Leuven, Belgium). The 3D-reconstructed masticatory muscles were then attached to the 3D skull model. The masticatory movements were animated using Maya (Autodesk, San Rafael, CA) based on the mandibular motion path. During unilateral chewing, the mandible was found to move laterally toward the functional side by contracting the contralateral lateral pterygoid and ipsilateral temporalis muscles. During the initial mouth opening, only hinge movement was observed at the temporomandibular joint. During this period, the entire mandible rotated approximately 13 degrees toward the bicondylar horizontal plane. Continued movement of the mandible to full mouth opening occurred simultaneously with sliding and hinge movements, and the mandible rotated approximately 17 degrees toward the center of the mandibular ramus. The described approach can yield data for use in face animation and other simulation systems and for elucidating the functional components related to contraction and relaxation of muscles during mastication.

Accuracy of miniscrew surgical guides assessed from cone-beam computed tomography and digital models.

INTRODUCTION: Several methods are available to enhance the precision of miniscrew placement. The use of surgical guides based on cone-beam computed tomography is indicated especially in patients with risky or difficult anatomic situations. The purpose of this study was to evaluate the accuracy of miniscrew placement by using surgical guides developed with computer-aided design and manufacturing techniques. METHODS: Miniscrews were placed in cadaver maxillae using stereolithographic computer-aided design and manufacturing techniques with assistance from surgical guides (surgical guide group, n = 25) or periapical x-rays (control group, n = 20). Insertion sites were selected using a 3-dimensional surgical planning program by fusing maxillary digital model images and cone-beam computed tomography images. Deviations between actual and planned placements were measured as 3-dimensional angular deviations and distance (coronal and apical) deviations. RESULTS: In the surgical guide group, the angular deviation was a median of 3.14° (range, 1.02°-10.9°), and the mesiodistal deviations in the coronal and apical areas were medians of 0.29 mm (range, 0.03-0.73 mm) and 0.21 mm (range, 0.03-0.97 mm), respectively. The deviations differed significantly between operators in the control group, but not in the surgical guide group. In the surgical guide group, there was no root damage from miniscrew placement, and 84% of the miniscrews were placed without contacting adjacent anatomic structures. In the control group, 50% of the miniscrews were placed between the roots (P <0.05). CONCLUSIONS: Surgical guide accuracy was improved when digital model imaging was used. Miniscrews were placed more accurately when using surgical guides than when using a direct method.

Biosynthesis of artificial starch and microbial protein from agricultural residue.

Growing populations and climate change pose great challenges to food security. Humankind is confronting a serious question: how will we feed the world in the near future? This study presents an out-of-the-box solution involving the highly efficient biosynthesis of artificial starch and microbial proteins from available and abundant agricultural residue as new feed and food sources. A one-pot biotransformation using an in vitro coenzyme-free synthetic enzymatic pathway and baker's yeast can simultaneously convert dilute sulfuric acid-pretreated corn stover to artificial starch and microbial protein under aerobic conditions. The ß-glucosidase-free commercial cellulase mixture plus an ex vivo two-enzyme complex containing cellobiose phosphorylase and potato α-glucan phosphorylase displayed on the surface of Saccharomyces cerevisiae, showed better cellulose hydrolysis rates than a commercial ß-glucosidase-rich cellulase mixture. This is because the channeling of the hydrolytic product from the solid cellulosic feedstock to the yeast mitigated the inhibition of the cellulase cocktail. Animal tests have shown that the digestion of artificial amylose results in slow and relatively small changes in blood sugar levels, suggesting that it could be a new health food component that prevents obesity and diabetes. A combination of the utilization of available agricultural residue and the biosynthesis of starch and microbial protein from non-food biomass could address the looming food crisis in the food-energy-water nexus.

Odontogenic ameloblasts-associated protein (ODAM), via phosphorylation by bone morphogenetic protein receptor type IB (BMPR-IB), is implicated in ameloblast differentiation.

To elucidate the function of the odontogenic ameloblast-associated protein (ODAM) in ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in ameloblasts during ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

Three-Dimensional CBCT Based Evaluation of the Maxillary Sinus by Facial Index.

The maxillary sinus growth is initiated 3 months after birth, and it grows lateral and inferior until the pneumatization of the alveolar bone occurs. The facial skeleton has recently been determined as affecting the maxillary sinus, prompting additional studies on changes in the size of the maxillary sinus. This study aimed to determine the size of the maxillary sinus using a 3D program after categorizing South Korean adults according to their facial index (FI) classification. The participants of this study were 60 patients in their 20s, who visited the orthodontic department of Dankook University Dental Hospital (approval no. DUDH IRB 2015-12-022). The CBCT of the patients were extracted and measured as 3D images using Mimics (version 22.0, Materialise, Leuven, Belgium). Upon categorizing the subjects based on their FI classification, they were grouped into the mesoprosopic, leptoprosopic, and hyperleptoprosopic types. A one-way ANOVA was performed to evaluate the mean differences of the maxillary sinus, depending on the FI classification. In this study, the maxillary sinus tended to be wider in those with mesoprosopic type, and tended to be higher in the hyperleptoprosopic type, suggesting a need for clinicians to focus to the shape of the face during clinical treatments.

Factors Related to the Intention to Use Dental Care by Industrial Workers Due to COVID-19: Application of Anderson Model and Planned Behavior Theory.

The COVID-19 pandemic has affected medical and dental care in Korea. This study aimed to investigate the factors influencing the intention to use dental care in industrial workers, an economically active population. An online questionnaire survey was completed by 301 industrial workers. Stress and anxiety to viral epidemics-6 (SAVE-6), attitude, subjective norm, perceived behavior control, and intention to use dental care, based on the theory of planned behavior (TPB), were measured. Predisposing, enabling, and need factors based on the Andersen model were measured as control variables for influencing factors. In the final hierarchical multiple regression analysis, the most significant relevant factors affecting intention to use dental care were attitude (ß = 0.598, p < 0.001), followed by experience of dental clinic visits (ß = 0.237, p < 0.001), subjective norm (ß = 0.125, p < 0.001), perceived behavior control (ß = 0.114, p = 0.004), SAVE-6 (ß = -0.073, p = 0.025), and gingival bleeding (ß = 0.062, p = 0.029). Dental care use decreased to 58.5%, and socio-psychological factors based on TPB were closely associated with the intention to use dental care. Therefore, awareness must be raised regarding oral health practices to increase the use of dental care among industrial workers.

Association of Number of Teeth with ADL/IADL in Korean Middle-Aged and Older Adults: An Analysis of the 7th Korean Longitudinal Study of Aging.

We determined the association between the number of natural and implant teeth with activities of daily living (ADL) and instrumental ADL (IADL) levels in middle-aged and older adults aged ≥ 55 years. We included 6,925 participants, who underwent a computer-assisted personal interview in the 7th Korean Longitudinal Study of Aging. After controlling for general characteristics, the associations between the number of natural and implant teeth with ADL and IADL levels were examined using multiple regression analysis. The participants had 21.2 natural teeth and 1.08 implant teeth on average. The ADL and IADL levels were 0.61 and 1.56, 0.40 and 1.16, and 1.10 and 0.31 in participants with ≤ 9, 10-19, and ≥ 20 teeth, respectively. There was no significant association between ADL and the number of natural and implant teeth (p > 0.05). However, a one-unit increase in IADL score was associated with a reduced number of natural (ß = -0.031, p < 0.001) and implant (ß = -0.194, p = 0.006) teeth. Difficulties regarding IADL were associated with fewer natural and implant teeth, suggesting that maintaining and managing the number of teeth is critical to promoting the health of middle-aged and older adults.

Premixed Calcium Silicate-Based Root Canal Sealer Reinforced with Bioactive Glass Nanoparticles to Improve Biological Properties.

Recently, bioactive glass nanoparticles (BGns) have been acknowledged for their ability to promote interactions with the periapical tissue and enhance tissue regeneration by releasing therapeutic ions. However, there have been no studies on calcium silicate sealers with bioactive glass nanoparticle (BGn) additives. In the present study, a premixed calcium silicate root canal sealer reinforced with BGn (pre-mixed-RCS@BGn) was developed and its physicochemical features and biological effects were analyzed. Three specimens were in the trial: 0%, 0.5%, and 1% bioactive glass nanoparticles (BGns) were gradually added to the premixed type of calcium silicate-based sealer (pre-mixed-RCS). To elucidate the surface properties, scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy were used and flowability, setting time, solubility, and radiopacity were analyzed to evaluate the physical properties. Chemical properties were investigated by water contact angle, pH change, and ion release measurements. The antibacterial effects of the bioactive set sealers were tested with Enterococcus faecalis and the viability of human bone marrow-derived mesenchymal stem cells (hMSCs) with this biomaterial was examined. In addition, osteogenic differentiation was highly stimulated, which was confirmed by ALP (Alkaline phosphatase) activity and the ARS (Alizarin red S) staining of hMSCs. The pre-mixed-RCS@BGn satisfied the ISO standards for root canal sealers and maintained antimicrobial activity. Moreover, pre-mixed-RCS@BGn with more BGns turned out to have less cytotoxicity than pre-mixed-RCS without BGns while promoting osteogenic differentiation, mainly due to calcium and silicon ion release. Our results suggest that BGns enhance the biological properties of this calcium silicate-based sealer and that the newly introduced pre-mixed-RCS@BGn has the capability to be applied in dental procedures as a root canal sealer. Further studies focusing more on the biocompatibility of pre-mixed-RCS@BGn should be performed to investigate in vivo systems, including pulp tissue.

FAM83H mutations in families with autosomal-dominant hypocalcified amelogenesis imperfecta.

Amelogenesis imperfecta (AI) is a collection of diverse inherited disorders featuring dental-enamel defects in the absence of significant nondental symptoms. AI phenotypes vary and are categorized as hypoplastic, hypocalcified, and hypomaturation types. Phenotypic specificity to enamel has focused research on genes encoding enamel-matrix proteins. We studied two families with autosomal-dominant hypocalcified AI and have identified nonsense mutations (R325X and Q398X) in the FAM83H gene on chromosome 8q24.3. The mutations perfectly cosegregate with the disease phenotype and demonstrate that FAM83H is required for proper dental-enamel calcification.

Development of distraction osteogenesis model of the inferior mandibular border and alveolar bone.

The aims of this study were to establish an experimental rat model for distraction osteogenesis of the mandible and alveolar bone for the investigation of histologic and radiographic analysis and to develop the device for various distraction models. For osteotomy location and distraction device design, micro-computed tomographic analysis of the structure of rat mandible was performed. Twenty mandibles of Sprawl-Dawley rats were osteotomized based on the analysis, and newly developed custom-made devices were applied with bone screws. After a 5-day latency period, a distraction of 0.2 mm at a single session, and a 4-week consolidation period, animals were killed for histologic samples. The rat distraction osteogenesis model for the inferior mandibular border and alveolar bone was successfully established based on the protocols used in this study. New bone formation occurred at both body and alveolar bones of the mandible by the combination of 2 modes: intramembranous ossification was predominant at the end of distraction period, whereas endochondral ossification was observed at the center of the distraction gap at the end of the 4-week consolidation period. This model can be applied to various conditions related to distraction osteogenesis and provide information for the development of improvements in clinical treatments using distraction osteogenesis.

Malaris muscle, the lateral muscular band of orbicularis oculi muscle.

Little is currently known about the variations in the muscular band around the orbicularis oculi muscle (OOc) region, and so the aim of the current study was to describe in anatomic terms the morphologic patterns of the lateral muscular bands of the OOc. Sixty-one hemifaces from embalmed Korean adult cadavers (34 males, 27 females; age range, 45-85 years; mean age, 62.6 years; 28 bilateral and 5 unilateral) were dissected to reveal the anatomic features of the region around the OOc. The lateral muscular band originating from the superficial temporal fascia lateral to the OOc was observed in 54.1% of cases. It terminated at the zygomatic arch region in 17 cases (type A, 27.9%), at the cheek region in 11 cases (type B, 18%), and at the angle of the mouth in 5 cases (type C, 8.2%). When the linear length from the lateral canthus to the tragion was set as 100, the length from the lateral canthus to the lateral edge of OOc was 34.0 (male, 34.1; female, 33.7), and the length between the lateral edge of OOc and the lateral muscular bands of OOc was 6.4 (male, 6.5; female, 6.2). The results of this study suggest that the lateral muscular bands of the OOc may play a significant role in facial animation and dimple formation. In addition, these data provide an index of suggested regions to be injected in patients with periorbital rhytides.

Morphometric analysis of the Korean mandibular ramus for distraction osteogenesis using micro-computed tomography.

When performing distraction osteogenesis, the osteotomy is normally applied to the cortical bone posterior to the mandibular second molar. We measured the topographic thickness of the cortical and trabecular bone of the mandibular ramus and at the mandibular canal (MC) to provide crucial anatomic data aimed at minimizing complications and elucidating the most appropriate site for placing the distractor. Forty sides of the mandibles were prepared from 20 Korean cadavers (10 men and 10 women with a mean age of 68 years). The specimens were scanned and reconstructed into three-dimensional images using a micro-computed tomography system. Coronal and horizontal sectional images of the mandibular ramus were taken at thickness intervals of 2 mm from the reconstructed three-dimensional images. Image analysis software was used to measure the thicknesses of the cortical and trabecular bone and to identify the locations of the MC within the body and the mandibular ramus on each section. The mean thicknesses of the buccal cortical plate, trabecular bone, and lingual cortical plate were 2.9 mm (men, 3.0 mm; women, 2.8 mm), 9.1 mm (men, 9.8 mm; women, 8.5 mm), and 2.2 mm (men, 2.3 mm; women, 2.1 mm), respectively. The distance from the buccal surface of the mandible to the MC increased from 5.3 to 10.0 mm (men, 5.3-10.0 mm; women, 5.3-9.1 mm) when moving progressively anterosuperior from the mandibular angle region. Morphometric analyses of the mandibular ramus can provide crucial data when performing mandibular osteotomy and locating an appropriate placement site for a distractor device during the distraction-osteogenesis procedure.

A piezoelectric motor-based microactuator-generated distractor for continuous jaw bone distraction.

Distraction osteogenesis is widely applied to correct oral and maxillofacial deformities, and intermittent distraction protocols have been used in various clinical applications. There are many challenges for continuous distraction of the jaw bone such as when using hydraulic motors and motor-driven plates. The size of the motor is critical to the ability to miniaturize the complete distractor system, and the importance of size makes it difficult to extrapolate the results of animal models to the clinical situation. This study developed a microactuator-generated distractor (MAGD) for continuous jaw bone distraction. The MAGD system consists of control software based on Microsoft Windows and a Squiggle piezoelectric motor. The system allows various intermittent and continuous distraction protocols to be simply selected using the control software. The maximum force of the laboratory-scale MAGD is 3 N, and the device is ready for adoption in small-animal distraction models such as the rat and mouse. The MAGD needs further refinement before it can be applied to humans, but a fully implanted MAGD system will reduce soft-tissue complications resulting from exposure of the extraoral component. Moreover, the MAGD will support the patient's social activities and require only minimal cooperation from the patient.

Nuclear factor I-C is essential for odontogenic cell proliferation and odontoblast differentiation during tooth root development.

Our previous studies have demonstrated that nuclear factor I-C (NFI-C) null mice developed short molar roots that contain aberrant odontoblasts and abnormal dentin formation. Based on these findings, we performed studies to elucidate the function of NFI-C in odontoblasts. Initial studies demonstrated that aberrant odontoblasts become dissociated and trapped in an osteodentin-like mineralized tissue. Abnormal odontoblasts exhibit strong bone sialoprotein expression but a decreased level of dentin sialophosphoprotein expression when compared with wild type odontoblasts. Loss of Nfic results in an increase in p-Smad2/3 expression in aberrant odontoblasts and pulp cells in the subodontoblastic layer in vivo and primary pulp cells from Nfic-deficient mice in vitro. Cell proliferation analysis of both cervical loop and ectomesenchymal cells of the Nfic-deficient mice revealed significantly decreased proliferative activity compared with wild type mice. In addition, Nfic-deficient primary pulp cells showed increased expression of p21 and p16 but decreased expression of cyclin D1 and cyclin B1, strongly suggesting cell growth arrest caused by a lack of Nfic activity. Analysis of the pulp and abnormal dentin in Nfic-deficient mice revealed an increase in apoptotic activity. Further, Nfic-deficient primary pulp cells exhibited an increase in caspase-8 and -3 activation, whereas the cleaved form of Bid was hardly detected. These results indicate that the loss of Nfic leads to the suppression of odontogenic cell proliferation and differentiation and induces apoptosis of aberrant odontoblasts during root formation, thereby contributing to the formation of short roots.