Practice-based preclinical instruction for gingival displacement with animal models.

STATEMENT OF PROBLEM: Gingival displacement is recognized as a substantive and difficult procedure in fixed prosthodontics. However, a realistic simulation of gingival displacement is unavailable for preclinical dental students. PURPOSE: The purpose of this study was to evaluate whether practice-based preclinical instruction of gingival displacement with animal models could improve students' skill in patient care. MATERIAL AND METHODS: Isolated bovine mandibles (calves were younger than 6 months of age) and isolated porcine hemimandibles were prepared for this study. Twenty-two general dental practitioners with at least 5 years of experience were randomly selected and assigned to perform gingival displacement on both bovine and porcine jaws. Those practitioners were then asked to assess the clinical similarity of gingival displacement between human teeth and animal teeth. The data were analyzed with the paired t test (α=.05). Upon confirmation that the animal jaw provided a similar gingival displacement environment to that of human teeth, 80 predoctoral dental students were enrolled and randomized into 2 groups. Half of them underwent the new practice-based instruction, while the others underwent traditional preclinical teaching only (lectures, online video, or live demonstration). After preclinical learning, clinical performance in gingival displacement was evaluated for all students in terms of the effect of gingival displacement and quality of impression. The data were analyzed with the chi-square test (α=.05). RESULTS: The dentogingival environments of porcine and bovine jaws were similar to those of human jaws, and no significant difference was detected between these 2 animal models (P=.178). A significant increase occurred in the acceptable rate of the effect of gingival displacement (P<.001) and the quality of impression (P<.001) among students who received the practice-based instruction compared with those who received traditional teaching. CONCLUSIONS: These findings suggest that this practice-based instruction of gingival displacement with animal models is an effective method of promoting dental students' learning of gingival displacement.

Application of Graphene Based Nanotechnology in Stem Cells Research.

The past several years have witnessed significant advances in stem cell therapy, tissue engineering and regenerative medicine. Graphene, with its unique properties such as high electrical conductivity, elasticity and good molecule absorption, have potential for creating the next generation of biomaterials. This review summarizes the interrelationship between graphene and stem cells. The analysis of graphene when applied on mesenchymal stem cells, neural stem cells, induced pluripotent stem cells, embryonic stem cells, periodontal ligament stem cells, human adipose-derived stem cells and cancer stem cells, and how graphene influences cell behavior and differentiation are discussed in details.

Role of sagittal and oblique smiling profiles in evaluating facial esthetics.

INTRODUCTION: Surgeons and orthodontists used to use a conventional set of facial photographs, composed of front, front smiling, and profile images to evaluate facial esthetics, whereas sagittal and oblique smiling profile images have been largely neglected in practice. The aim of this study was to explore the importance of sagittal and oblique smiling profiles in evaluating facial esthetics. METHODS: Photographs from 80 patients, of whom 40 underwent orthognathic surgery and 40 underwent orthodontic treatment, including front, front smiling, profile, sagittal profile smiling, and oblique profile smiling images before and after treatment, were collected and synthesized into 6 categories. Thirty judges gave scores to these photographs based on their own esthetic conception with a 1-week interval for each category. RESULTS: The results demonstrated that the mean score change of evaluating facial attractiveness of patients who underwent orthognathic surgery was lower when adding sagittal or oblique smiling profiles before the treatment, whereas it was higher after the treatment, which were opposite to the orthodontic treatment group with a higher score before the treatment and a lower score after the treatment when sagittal or oblique smiling profiles were added. The changes have a significant difference in adding both sagittal smiling profiles (P < 0.05) and oblique smiling profiles (P < 0.05) before and after treatment. CONCLUSIONS: Along with oblique smiling profile, sagittal smiling profile is crucial in evaluating facial esthetics for orthodontic treatment and orthognathic surgery. Both of them suggested to be integrated in routine photographic assessment of facial attractiveness evaluation before and after treatment, especially in orthognathic surgery for facial esthetic evaluation.

Effect of mesiodistal angulation of the maxillary central incisors on esthetic perceptions of the smile in the frontal view.

INTRODUCTION: The purpose of this study was to analyze the effect of mesiodistal angulation of the maxillary central incisors on the smiling esthetics in young adults. METHODS: Frontal smile photographs of a young man and a young woman were digitally modified to produce 28 smile images that were grouped into 4 series. These images were judged using visual analog scales by 52 orthodontists and 61 laypeople. The effects of the judges' professions, subjects' sexes, and photograph framings on the appreciation of smile esthetics with different mesiodistal angulations of the maxillary central incisors were evaluated. The data were analyzed with paired t tests, Dunnett t tests, and independent samples t tests; statistical significance was set at P <0.05. RESULTS: The images were ranked less attractive as the mesiodistal angulation of the maxillary central incisors increased during smiling. No relationship was found between the judges' professions and the esthetic evaluations of incisal angulation, but the statistical analysis showed that both the subject's sex and the photograph framing were significant variables (P <0.05). CONCLUSIONS: The mesiodistal angulation of the maxillary central incisors plays an essential role in smile esthetics in the frontal view. When formulating treatment plans, orthodontists should never underestimate the influence of mesiodistal angulation on smile attractiveness.

Efficacy and safety of bupivacaine versus lidocaine in dental treatments: a meta-analysis of randomised controlled trials.

The objective of this study was to assess the efficacy and safety of bupivacaine compared with lidocaine in local anaesthesia in dental treatment. Medline, Cochrane Central Register of Controlled Trials, EMBASE, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and the World Health Organisation (WHO) International Clinical Trials Registry Platform were searched electronically. Relevant journals and references of studies included were hand-searched for randomised controlled trials comparing bupivacaine with lidocaine in terms of efficacy and safety. Sixteen studies were included, of which nine had low, six had moderate and one had high risk of bias. In comparison with 2% lidocaine plus 1:100,000 adrenaline, 0.5% bupivacaine plus 1:200,000 adrenaline showed a higher success rate in inflamed pulp (P = 0.03) but a lower success rate in vital pulp (P < 0.00001), a lower percentage of patients using postoperative analgesics (P < 0.00001), a longer onset times of pulpal anaesthesia and a longer duration of pulpal anaesthesia (P < 0.00001). In comparison with 2% lidocaine plus 1:80,000 adrenaline, 0.75% bupivacaine plus 1:200,000 adrenaline had same level of success rate (P = 0.29), and was better in postoperative pain control (P = 0.001) while 0.75% levobupivacaine had same level of postoperative pain control (P = 0.16); 0.5% levobupivacaine had higher success rate (P = 0.04) and was better in postoperative pain control (P = 0.001) than 2% lidocaine. There was no statistically significance in adverse events between two groups. Given the efficacy and safety, the bupivacaine group is better than the lidocaine group in dental operations that take a relatively long time, especially in endodontic treatments or where there is a need for postoperative pain management.

An In Vitro Study of Fluid Contaminations Influences on Reverse Torque Values of Implant-Abutment Connections.

Purpose: To examine the effects of fluid contamination on the reverse torque value (RTV) of abutment screws. 484 titanium fixtures were mounted into the stainless-steel holders. Methods: 11 groups (44 specimens in each group) of implants were mounted in acrylic resin. Ten groups of fixture screw holes were contaminated with chlorhexidine, saliva, blood, fluoride, or combination groups, and one group served as a control without contamination. To simulate the oral environment, samples were subjected to thermal cycling and cyclic loading. Results: The RTV means were less than the initial torque in both control and contamination groups. The maximum RTV mean was observed in the fluoride group (26.00 ± 1.02 Ncm). In other groups, this rate for control, blood, saliva, and chlorhexidine groups were 18.00 ± 1.78 Ncm, 22.12 ± 1.56 Ncm, 21.56 ± 1.43 Ncm, and 21.89 ± 1.02 Ncm, respectively. In combination groups, the maximum RTV mean was observed in the saliva+CHX group (23.89 ± 1.92 Ncm). In other combination groups, this rate for the blood+CHX, blood+saliva, saliva+fluoride, fluoride+CHX, and fluoride+blood groups were 22.56 ± 1.73 Ncm, 22.00 ± 1.54 Ncm, 20.11 ± 1.58 Ncm, 23.51 ± 1.19 Ncm, 21.02 ± 1.38 Ncm, and 20.11 ± 1.58 Ncm, respectively. The RTV was statistically significant (p < 0.05) for the contamination groups (except saliva) and combination groups compared to the control group. There is no statistically significant difference (p > 0.05) between the reverse torque value mean of the blood and saliva groups and between that of the fluoride and chlorhexidine groups. Conclusion: Implant-abutment specimens are suggested to be placed in a saliva environment and should be subjected to cyclic loading.

Regulation of LL-37 in Bone and Periodontium Regeneration.

The goal of regenerative therapy is to restore the structure and function of the lost tissues in the fields of medicine and dentistry. However, there are some challenges in regeneration therapy such as the delivery of oxygen and nutrition, and the risk of infection in conditions such as periodontitis, osteomyelitis, etc. Leucine leucine-37 (LL-37) is a 37-residue, amphipathic, and helical peptide found only in humans and is expressed throughout the body. It has been shown to induce neovascularization and vascular endothelial growth factor (VEGF) expression. LL-37 also stimulates the migration and differentiation of mesenchymal stem cells (MSCs). Recent studies have shown that LL-37 plays an important role in the innate defense system through the elimination of pathogenic microbes and the modulation of the host immune response. LL-37 also manifests other functions such as promoting wound healing, angiogenesis, cell differentiation, and modulating apoptosis. This review summarizes the current studies on the structure, expression, and function of LL-37 and highlights the contributions of LL-37 to oral cavity, periodontium, and bone regeneration.

The Effect of IFT80 Deficiency in Osteocytes on Orthodontic Loading-Induced and Physiologic Bone Remodeling: In Vivo Study.

Osteocytes are the main mechanosensory cells during orthodontic and physiologic bone remodeling. However, the question of how osteocytes transmit mechanical stimuli to biological responses remains largely unanswered. Intraflagellar transport (IFT) proteins are important for the formation and function of cilia, which are proposed to be mechanical sensors in osteocytes. In particular, IFT80 is highly expressed in mouse skulls and essential for ciliogenesis. This study aims to investigate the short- and long-term effects of IFT80 deletion in osteocytes on orthodontic bone remodeling and physiological bone remodeling in response to masticatory force. We examined 10-week-old experimental DMP1 CRE+.IFT80f/f and littermate control DMP1 CRE-.IFT80f/f mice. After 5 and 12 days of orthodontic force loading, the orthodontic tooth movement distance and bone parameters were evaluated using microCT. Osteoclast formation was assessed using TRAP-stained paraffin sections. The expression of sclerostin and RANKL was examined using immunofluorescence stain. We found that the deletion of IFT80 in osteocytes did not significantly impact either orthodontic or physiologic bone remodeling, as demonstrated by similar OTM distances, osteoclast numbers, bone volume fractions (bone volume/total volume), bone mineral densities, and the expressions of sclerostin and RANKL. Our findings suggest that there are other possible mechanosensory systems in osteocytes and anatomic limitations to cilia deflection in osteocytes in vivo.

Control of Cell Geometry through Infrared Laser Assisted Micropatterning.

Micropatterning is an established technique in the cell biology community used to study connections between the morphology and function of cellular compartments while circumventing complications arising from natural cell-to-cell variations. To standardize cell shape, cells are either confined in 3D molds or controlled for adhesive geometry through adhesive islands. However, traditional micropatterning techniques based on photolithography and deep UV etching heavily depend on clean rooms or specialized equipment. Here we present an infrared laser assisted micropatterning technique (microphotopatterning) modified from Doyle et al. that can be conveniently set up with commercially available imaging systems. In this protocol, we use a Nikon A1R MP+ imaging system to generate micropatterns with micron precision through an infrared (IR) laser that ablates preset regions on poly-vinyl alcohol coated coverslips. We employ a custom script to enable automated pattern fabrication with high efficiency and accuracy in systems not equipped with a hardware autofocus. We show that this IR laser assisted micropatterning (microphotopatterning) protocol results in defined patterns to which cells attach exclusively and take on the desired shape. Furthermore, data from a large number of cells can be averaged due to the standardization of cell shape. Patterns generated with this protocol, combined with high resolution imaging and quantitative analysis, can be used for relatively high throughput screens to identify molecular players mediating the link between form and function.

Quantitative Analysis of Myofibroblast Contraction by Traction Force Microscopy.

Myofibroblasts play important roles in physiological processes such as wound healing and tissue repair. While high contractile forces generated by the actomyosin network enable myofibroblasts to physically contract the wound and bring together injured tissue, prolonged and elevated levels of contraction also drive the progression of fibrosis and cancer. However, quantitative mapping of these forces has been difficult due to their extremely low magnitude ranging from 100 pN/µm2 to 2 nN/µm2. Here, we provide a protocol to measure cellular forces exerted on two-dimensional compliant elastic hydrogels. We describe the fabrication of polyacrylamide hydrogels labeled with fluorescent fiducial markers, functionalization of substrates with ECM proteins, setting up the experiment, and imaging procedures. We demonstrate the application of this technique for quantitative analysis of traction forces exerted by myofibroblasts.

The Role of the Immune Response in the Development of Medication-Related Osteonecrosis of the Jaw.

Medication-related osteonecrosis of the jaw (MRONJ) is a rare but serious adverse drug effect. There are multiple hypotheses to explain the development of MRONJ. Reduced bone remodeling and infection or inflammation are considered central to the pathogenesis of MRONJ. In recent years, increasing evidence has shown that bisphosphonates (BPs)-mediated immunity dysfunction is associated with the pathophysiology of MRONJ. In a healthy state, mucosal immunity provides the first line of protection against pathogens and oral mucosal immune cells defense against potentially invading pathogens by mediating the generation of protective immunoinflammatory responses. In addition, the immune system takes part in the process of bone remodeling and tissue repair. However, the treatment of BPs disturbs the mucosal and osteo immune homeostasis and thus impairs the body's ability to resist infection and repair from injury, thereby adding to the development of MRONJ. Here, we present the current knowledge about immunity dysfunction to shed light on the role of local immune disorder in the development of MRONJ.

Effect of Ferrule Thickness on Fracture Resistance of Endodontically Treated Incisors Restored with Fiber Post and Metal Crown.

PURPOSE: To assess the influence of ferrule thickness on the fracture resistance and failure mode of endodontically treated bovine incisors and to predict the long-term prognosis, as well as choose the most suitable clinical treatment, for teeth with different ferrule thicknesses. MATERIALS AND METHODS: A total of 50 endodontically treated bovine incisors were restored with quartz fiber posts and metal crowns and separated into five groups (n = 10 each): no ferrule (group A); 0.5-mm-thick ferrule (group B); 1.0-mm-thick ferrule (group C); 1.5-mm-thick ferrule (group D); and 2.0-mm-thick ferrule (group E). All specimens were subjected to a fatigue loading test (2.33 Hz, 50 N, 300,000 cycles). Survived specimens were loaded until fracture on a universal testing machine at an angle of 135 degrees and a crosshead speed of 0.5 mm/minute. Failure modes and fracture resistance were recorded. Data were analyzed using one-way ANOVA and least significant difference tests. RESULTS: A significant increase (P < .05) was detected in fracture resistance with increase in ferrule thickness. Group D (1.5 mm) and group E (2.0 mm) showed significantly higher fracture resistance than the other three groups. All failures belonged to restorable fracture patterns. CONCLUSION: Ferrule thickness contributed significantly to the fracture resistance of endodontically treated bovine incisors restored with quartz fiber posts and metal crowns. Teeth with ferrule thickness of ≥ 1.5 mm can achieve higher fracture resistance and have a better long-term prognosis.

IFT80 is required for stem cell proliferation, differentiation, and odontoblast polarization during tooth development.

Primary cilia and intraflagellar transport (IFT) proteins control a wide variety of processes during tissue development and homeostasis. However, their role in regulation of stem cell properties during tooth development remains elusive. Here, we revealed that dental pulp stem cells (DPSCs) express IFT80, which is required for maintaining DPSC properties. Mice with deletion of IFT80 in odontoblast lineage show impaired molar root development and delayed incisor eruption through reduced DPSC proliferation and differentiation, and disrupted odontoblast polarization. Impaired odontoblast differentiation resulted from disrupted hedgehog (Hh) signaling pathways. Decreased DPSC proliferation is associated with impaired fibroblast growth factor 2 (FGF2) signaling caused by loss of IFT80, leading to the disruption of FGF2-FGFR1-PI3K-AKT signaling in IFT80-deficient DPSCs. The results provide the first evidence that IFT80 controls tooth development through influencing cell proliferation, differentiation, and polarization, and Hh and FGF/AKT signaling pathways, demonstrating that IFT proteins are likely to be the new therapeutic targets for tooth and other tissue repair and regeneration.

Ciliary IFT80 regulates dental pulp stem cells differentiation by FGF/FGFR1 and Hh/BMP2 signaling.

Primary cilia and intraflagellar transport (IFT) proteins control a wide variety of processes during development and tissue homeostasis. However, their potential roles in the regulation of stem cell differentiation and tooth development remain elusive. Here, we uncovered the critical roles of ciliary IFT80 in cilia formation and differentiation of dental pulp stem cells (DPSCs). IFT80-deficient DPSCs showed reduced fibroblast growth factor receptor 1 (FGFR1) expression, leading to the disruption of FGF2-FGFR1 signaling. We found, during DPSC differentiation, FGF2-FGFR1 signaling induces stress fiber rearrangement to promote cilia elongation, meanwhile stimulates PI3K-AKT signaling to aid Hh/bone morphogenetic protein 2 (BMP2) signaling activation. These signaling pathways and their coupling were disrupted in IFT80-deficient DPSCs, causing impaired differentiation. Our findings revealed a novel mechanism that ciliary protein regulates the odontogenic differentiation of DPSCs through FGF/FGFR1 and Hh/BMP2 signaling.

[Application of animal models in gingival retraction experimental curriculum].

PURPOSE: To introduce a teaching method for gingival retraction, and evaluate its efficacy for implementation into experimental curricula. METHODS: First, two kinds of animal models using pigs and cows (below 6 months of age) were established. Twenty-two experienced prosthodontists were then asked to apply gingival retraction on each animal model and evaluate the biofidelity of the 2 models' dento-gingival environment. The data was analyzed with SPSS19.0 software package for paired t test.Then, eighty pre-internship students were randomly divided into 2 groups. Besides the traditional teaching (lecture-based teaching), the experimental group (group A) also had access to skill training (using animal models to practice gingival retraction), while the control group (group B) only used the traditional teaching modality. All students' performance in gingival retraction and impression taking were evaluated in their internship. The data was analyzed with SPSS19.0 software package for Chi-square test. RESULTS: Both pig and cow's dento-gingival environment were similar to that of human being, and there was no significant difference between the two models'biofidelities (P>0.05). In addition, both the effect of gingival retraction and the quality of impression in group A were significantly better than those in group B (P<0.05). CONCLUSIONS: Compared with the traditional strategy,practising gingival retraction on animal models can offer greater opportunities for skill development,and be implemented for a wider range of applications.

Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm(2) , Rout = 140 Ω/cm(2) ) compared to 21 days (Rin = 3.60 e4 Ω/cm(2) , Rout = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm(2) , Rout = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm(2) , Rout = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91.

Hydrophilic polyurethane matrix promotes chondrogenesis of mesenchymal stem cells.

Segmental polyurethanes exhibit biphasic morphology and can control cell fate by providing distinct matrix guided signals to increase the chondrogenic potential of mesenchymal stem cells (MSCs). Polyethylene glycol (PEG) based hydrophilic polyurethanes can deliver differential signals to MSCs through their matrix phases where hard segments are cell-interactive domains and PEG based soft segments are minimally interactive with cells. These coordinated communications can modulate cell-matrix interactions to control cell shape and size for chondrogenesis. Biphasic character and hydrophilicity of polyurethanes with gel like architecture provide a synthetic matrix conducive for chondrogenesis of MSCs, as evidenced by deposition of cartilage-associated extracellular matrix. Compared to monophasic hydrogels, presence of cell interactive domains in hydrophilic polyurethanes gels can balance cell-cell and cell-matrix interactions. These results demonstrate the correlation between lineage commitment and the changes in cell shape, cell-matrix interaction, and cell-cell adhesion during chondrogenic differentiation which is regulated by polyurethane phase morphology, and thus, represent hydrophilic polyurethanes as promising synthetic matrices for cartilage regeneration.

Intervention of selenium on apoptosis and Fas/FasL expressions in the liver of fluoride-exposed rats.

Fluorosis is a major public health problem in numerous areas around the world, including China. To alleviate this problem, selenium has been used. In this study, we aimed to investigate the influence of selenium on apoptosis in fluorosis-affected rat livers and determine the optimal selenium concentration in drinking water to fight fluorosis. The protein levels of Fas in NaF and NaF+Se (0.375 and 0.75 mg/L) groups as well as FasL in NaF, Se (0.75 and 1.5 mg/L), and NaF+Se (0.375 mg/L) groups were significantly increased compared with those in the control group. The mRNA levels of Fas in NaF and Se (1.5 mg/L) groups as well as FasL in NaF and NaF+Se (0.375 mg/L) groups were significantly increased. The protein levels of Fas in NaF+Se (1.5 mg/L) group and FasL in three NaF+Se groups were significantly decreased compared with those in the NaF group. The mRNA levels of Fas in the three NaF+Se groups and FasL in NaF+Se (0.75 and 1.5 mg/L) groups were significantly decreased. Compared with the control group, activity of GSH-Px, and SOD in the NaF group decreased obviously and MDA content increased obviously; activity of SOD in 1.5 mg/L Se group decreased obviously. Compared with the NaF group, activity of GSH-Px in NaF+Se (1.5 mg/L) group significantly increased, and MDA content decreased obviously. Thus, fluoride induced apoptosis in the liver, thereby causing liver damage in the rats. Selenium could alleviate fluorosis-induced liver injury. In particular, selenium at 1.5 mg/L is considered the optimum concentration against fluorosis.

Cell-material interactions on biphasic polyurethane matrix.

Cell-matrix interaction is a key regulator for controlling stem cell fate in regenerative tissue engineering. These interactions are induced and controlled by the nanoscale features of extracellular matrix and are mimicked on synthetic matrices to control cell structure and functions. Recent studies have shown that nanostructured matrices can modulate stem cell behavior and exert specific role in tissue regeneration. In this study, we have demonstrated that nanostructured phase morphology of synthetic matrix can control adhesion, proliferation, organization and migration of human mesenchymal stem cells (MSCs). Nanostructured biodegradable polyurethanes (PU) with segmental composition exhibit biphasic morphology at nanoscale dimensions and can control cellular features of MSCs. Biodegradable PU with polyester soft segment and hard segment composed of aliphatic diisocyanates and dipeptide chain extender were designed to examine the effect polyurethane phase morphology. By altering the polyurethane composition, morphological architecture of PU was modulated and its effect was examined on MSC. Results show that MSCs can sense the nanoscale morphology of biphasic polyurethane matrix to exhibit distinct cellular features and, thus, signifies the relevance of matrix phase morphology. The role of nanostructured phases of a synthetic matrix in controlling cell-matrix interaction provides important insights for regulation of cell behavior on synthetic matrix and, therefore, is an important tool for engineering tissue regeneration.

Effects of selenium intervention on chronic fluorosis-induced renal cell apoptosis in rats.

This study aims to explore the effect of selenium in fluoride-induced renal cell apoptosis in rats and determine the optimal level of selenium in drinking water to prevent fluorosis. Experimental animals were divided into a control group, a sodium fluoride-treated group (NaF, 50 mg/L), three sodium selenite-treated groups (Na2SeO3, 0.375, 0.75, and 1.5 mg/L), and three selenium + NaF-treated groups (Na2SeO3, 0.375, 0.75, and 1.5 mg/L; NaF, 50 mg/L). Ultrastructural changes in the kidney tissues of each group were observed by transmission electron microscopy. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and the expressions of Bcl-2 and Bax proteins were detected by immunohistochemical methods. The expressions of Bcl-2 and Bax mRNA were detected by reverse transcription-polymerase chain reaction. The results showed that Bcl-2, Bax, and Bax/Bcl-2 protein expressions in the fluoride and high selenium groups were highly elevated compared with the control group (P < 0.01). Bax expression in the low selenium group and Bcl-2, Bax, and Bax/Bcl-2 protein expressions in the moderate selenium groups were observably elevated (P < 0.05). Bax and Bax/Bcl-2 expressions in the fluoride group and Bax mRNA expression in the high selenium group were highly elevated (P < 0.01). Bax/Bcl-2 mRNA expression in the high selenium group was also highly elevated (P < 0.05). Compared with the fluoride group, the group treated with low selenium has Bax protein expression that was observably reduced (P < 0.05); the group treated with moderate selenium has Bcl-2 protein expression that was observably elevated (P < 0.05), Bax protein expression that was highly reduced (P < 0.01), and Bax/Bcl-2 protein expression that was observably reduced (P < 0.05); the group treated with high selenium has Bcl-2 protein expression that was highly elevated (P < 0.01), Bax protein expression that was highly elevated (P < 0.01), and Bax/Bcl-2 protein expression that was highly reduced (P < 0.01); the groups treated with moderate selenium and high selenium have Bax mRNA expression that was highly reduced (P < 0.01), and the groups treated with high selenium have Bax/Bcl-2 mRNA expression that was observably reduced (P < 0.05). Selenium may inhibit the apoptosis of renal cells in fluorosis rats by regulating the expressions of Bcl-2 and Bax. The optimal dose of Na2SeO3 to protect against fluoride-induced renal cell apoptosis was determined to be 1.5 mg/L.