Potential effects of allyl isothiocyanate on inhibiting cellular proliferation and inducing apoptotic pathway in human cisplatin-resistant oral cancer cells.

BACKGROUND/PURPOSE: Cisplatin-resistant oral cancer is clinically difficult to manage and the dose-dependent toxicities of cisplatin has been widely concerned. Allyl isothiocyanate (AITC), known as mustard oil, is a plant-derived compound abundant in cruciferous vegetables. It is reported to have anti-cancer potential as a natural dietary chemopreventive compound against a variety of cancers, but the effect of AITC on cisplatin-resistant cancer cells is still little-known. METHODS: Human CAL27-cisplatin-resistant oral cancer cells (CAR cells) were examined to investigate the antitumor properties of AITC. 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay, IncuCyte™ S3 cell proliferation assay, 4',6-diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining as well as Western blot analysis were deployed. RESULTS: AITC decreased CAR cell viability, induced cell death of CAR cells and inhibited the confluences of cultured CAR cells. When CAR cells were treated with AITC, activation of caspase-3 and caspase-9 by AITC was observed and could be reversed by Z-VAD-fmk (pan-caspase inhibitor). Furthermore, the protein expressions of phosphorylated protein kinase B (p-AKT) and phosphorylated mammalian target of rapamycin (p-mTOR) were suppressed in AITC-treated CAR cells, whereas protein expressions of Bax, cytochrome c, Apaf-1, cleaved caspase-3, and cleaved caspase-9 were upregulated in AITC-treated CAR cells. CONCLUSION: AITC can inhibit Akt/mTOR proliferation signaling and promote mitochondria-dependent apoptotic pathway through AITC-enhanced activities of caspase-3 and caspase-9 in CAR cells.

Improving the prediction of the trabecular bone microarchitectural parameters using dental cone-beam computed tomography.

BACKGROUND: In this study, we explored how various preprocessing approaches can be employed to enhance the capability of dental CBCT to accurately estimate trabecular bone microarchitectural parameters. METHODS: In total, 30 bovine vertebrae cancellous bone specimens were used for in study. Voxel resolution 18-µm micro-computed tomography (micro-CT) and 100-µm dental CBCT were used to scan each specimen. Micro-CT images were used to calculate trabecular bone microarchitectural parameters; the results were set as the gold standard. Subsequently, before the dental CBCT images were converted into binary images to calculate trabecular bone microarchitectural parameters, three preprocessing approaches were used to process the dental CBCT images. For Group 1, no preprocessing approach was applied. For Group 2, images were sharpened and despeckable noises were removed. For Group 3, the function of local thresholding was added to Group 2 to form Group 3. For Group 4, the air pixels was removed from Group 3 to form Group 4. Subsequently, all images were imported into a software package to estimate trabecular bone microarchitectural parameters (bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN), and trabecular separation (TbSp)). Finally, a paired t-test and a Pearson correlation test were performed to compare the capability of micro-CT with the capability of dental CBCT for estimating trabecular bone microarchitectural parameters. RESULTS: Regardless of whether dental CBCT images underwent image preprocessing (Groups 1 to 4), the four trabecular bone microarchitectural parameters measured using dental CBCT images were significantly different from those measured using micro-CT images. However, after three image preprocessing approaches were applied to the dental CBCT images (Group 4), the BV/TV obtained using dental CBCT was highly positively correlated with that obtained using micro-CT (r = 0.87, p < 0.001); the correlation coefficient was greater than that of Group 1 (r = -0.15, p = 0.412), Group 2 (r = 0.16, p = 0.386), and Group 3 (r = 0.47, p = 0.006). After dental CBCT images underwent image preprocessing, the efficacy of using dental CBCT for estimating TbN and TbSp was enhanced. CONCLUSIONS: Image preprocessing approaches can be used to enhance the efficacy of using dental CBCT for predicting trabecular bone microarchitectural parameters.

Effects of mineral trioxide aggregate and bioceramics on macrophage differentiation and polarization in vitro.

BACKGROUND/PURPOSE: Mineral trioxide aggregate (Pro-Root MTA, PR-MTA) and bioceramics (iRoot® SP Injectable Root Canal Sealer, iR-BC) are used for making apical plugs used in apexification, repairing root perforations during root canal therapy, and treating internal root resorption. The purpose of the present in vitro study was to compare the biological effects of PR-MTA- and iR-BC-based dental sealers in the mouse macrophage cell line RAW 264.7. METHODS: Cytotoxicity and cell proliferation were analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell hemocytometer, respectively. Protein expression of biomarkers of cell proliferation, autophagy, and osteoclast differentiation was determined by western blotting. Pro-inflammatory gene expression was examined using quantitative reverse transcription-PCR. RESULTS: PR-MTA induced cytotoxicity in RAW 264.7 cells in a dose-dependent manner, and iR-BC was more cytotoxic than PR-MTA. Low-dose and short-term treatments of both PR-MTA and iR-BC induced RAW 264.7 cell proliferation. PR-MTA induced autophagy, whereas iR-BC did not. Neither PR-MTA nor iR-BC induced osteoclastogenesis. Pro-inflammatory genes were activated by both materials. However, the expression of inducible nitric oxide synthase (iNOS) mRNA was upregulated by iR-BC treatment, but not by PR-MTA treatment. CONCLUSION: Overall, dental PR-MTA and iR-BC induced pro-inflammatory genes but did not induce osteoclastogenesis in macrophages. PR-MTA and iR-BC induced M2 and M1 polarization, respectively, of RAW 264.7 cells.

The survey of tinea capitis and scalp dermatophyte carriage in nursing home residents.

Tinea capitis is a contagious dermatophyte infection of scalp and associated hairs. On the other hand, asymptomatic carriage is a status of positive dermatophyte scalp culture, but without signs or symptoms of tinea capitis, and no evidence of hair shaft invasion confirmed by direct microscopy. Tinea capitis and asymptomatic carriage mostly occur in children, but adult females are becoming another population in recent decades. In this study, we focused on the prevalence and related fungi of tinea capitis and asymptomatic carriage in elderly by the shampoo brush method, as well as the source of transmission, in 10 nursing home residents. Two hundred and thirteen residents were screened, and 186 isolates were identified, of which only three were dermatophytes (1.4%). The scalp dermatophyte isolates were identified as Trichophyton rubrum by morphological characters and sequences comparisons in all three cases. After revisiting, these cases were proved to be asymptomatic carriers by negative microscopic and culture examination; however, two cases were found to have concurrent tinea pedis and onychomycosis, which were identified as T. rubrum and Trichophyton interdigitale. The source of the T. rubrum scalp carriage may come from tinea elsewhere on the body of the same subject or from other people in the same institute. Finding and treating the source of carriage, as well as treating scalp carriage patients according to the colony counts, may help prevent disease spreading.

Prevalence of primate and interdental spaces for primary dentition in 3- to 6-year-old children in Taiwan.

BACKGROUND/PURPOSE: Spaced primary dentition plays a critical role in the eruption of permanent teeth and the establishment of ideal occlusion. A lack of these spaces in deciduous dentition may result in disproportionate jaw and tooth sizes. Additionally, spaced primary dentition is significantly affected by ethnic factors. However, few of these studies have been conducted in Asia. The purpose of this study was to investigate the prevalence of spaced primary dentition in Taiwan. METHODS: One hundred and forty-seven 3- to 6-year-old Taiwanese children (58 girls and 89 boys) were recruited for a cross-sectional study. Primate and interdental spaces were recorded by intraoral photos. The prevalence of spaced dentition was evaluated. The interpersonal agreement of spaced dentition between the upper and lower arches was also assessed. RESULTS: Most of the subjects had spaced primary dentition. The prevalence of primate space was 83.7% in the upper arch and 61.2% in the lower arch, whereas the prevalence of interdental space was 44.2% in the upper arch and 53.1% in the lower arch. The prevalence rates of interdental space and upper primate space were significantly higher in boys than in girls. Interdental spaces of the lower arch increased with age. CONCLUSION: Ethnic factors can affect the ratio of spaced dentition. Most of the 3- to 6-year-old Taiwanese children have spaced dentition. The boys have higher incidence of spaced dentition than the girls. Furthermore, primate space is more frequently found in the upper arch than in the lower arch, whereas interdental space is reversed.

Bite-force difference among obese adolescents in central Taiwan.

BACKGROUND/PURPOSE: Maximal bite force of the jaw can cause thorough food chewing and result in good digestion. Bite force is related to the health of the masticatory muscles. Muscle force is frequently affected by obesity in adolescence, however, little is known about how obesity influences the maximum bite force and the difference between genders. METHODS: Five hundred and seventy-seven adolescent students (292 girls and 285 boys), aged 13-16 years, from central Taiwan were recruited for a cross-sectional study in 2009. The maximum bite force, hand strength, triceps skin-fold fat thickness, serum level of testosterone, and body mass index (BMI) were measured. Dental health was evaluated based on malocclusion and dental caries. RESULTS: Bite force in girls was highest in the obese group (32.49 ± 19.13 kg, mean ± standard deviation), whereas in boys it was higher in the overweight group (41.89 ± 19.3 kg) than in the obese group (33.21 ± 17.12 kg). The prevalence of obesity was twofold higher in boys (14.39%) than in girls (7.88%). The mean serum level of testosterone increased with BMI in girls (p = 0.0172), whereas it decreased with BMI in boys (p = 0.0014). The relationships of serum testosterone level and bite force with BMI were similar in the two gender groups. CONCLUSION: The maximum bite force decreased in obese boys but increased in obese girls, which may be due to the sensitivity to testosterone being modulated by the fat level.

Macrophage-mediated osteogenesis activation in co-culture with osteoblast on calcium silicate cement.

The use of calcium silicate (CS) cement holds great promise for bone substitute biomaterials. However, the effects of CS on osteoblast and macrophage cells are not fully understood. This study examines cell proliferation and differentiation of mono- or co-cultured MC3T3-E1 and Raw 264.7 cells on CS cement. Very few studies to date have looked at the effects of osteoblast and macrophages on biomaterial-regulated osteogenesis. In this study the proliferation and differentiation of MC3T3-E1, Raw 264.7 and co-cultured MC3T3-E1/Raw 264.7 on CS cements have been analyzed using a PrestoBlue kit and ELISA. In addition, the effect of macrophages on CS-coordinated osteogenesis of MC3T3-E1 has been investigated. Results show that MC3T3-E1, Raw 264.7 and co-cultured MC3T3-E1/Raw 264.7 adhere to and proliferate well on the CS cement. In a co-culture, the CS cements inhibit receptor activator of nuclear factor kappa B ligand expression of both genes and proteins in Raw 264.7 cells when compared to those grown in mono-cultured system. Ca deposition of MC3T3-E1 in the co-culture is higher than that of cells in a mono-culture. Bone morphogenetic protein 2 (BMP2) is also significantly up-regulated by the CS cement stimulation, indicating that macrophages may participate in the CS stimulated osteogenesis. Interestingly, when macrophage are cultured with BMP2 receptor-blocking MC3T3-E1 on the CS cements, the osteogenesis differentiation of the cells is significantly inhibited, indicating the important role of macrophages in biomaterial-induced osteogenesis via BMP2 receptors. It is assumed that it is an increase in the secretion of the BMP2 from the Raw 264.7 cell that is primarily involved in the promotion of the osteogenesis of the MC3T3-E1. These results provide valuable insights into both the mechanism of CS-stimulated osteogenesis, and strategies to optimize the evaluation system for the in vitro osteogenesis capacity of bone substitute biomaterials.

Analysis of mandibular molar anatomy in Taiwanese individuals using cone beam computed tomography.

Background/purpose: Before periapical surgery in the mandibular posterior teeth is performed, the thicknesses of the buccal alveolar bone wall and buccolingual root might be a critical issue. This study aimed to assess the anatomical structure of the posterior region of the mandible in Taiwanese individuals using cone-beam computed tomography (CBCT). Materials and methods: The CBCT images of 96 Taiwanese individuals (51 male and 45 female), which included 192 mandibular first molars and 192 mandibular second molars, were imported into medical imaging software to measure the buccal alveolar bone thickness and buccolingual root thickness at 3 mm above the root apex. Statistical analysis was conducted to examine the impact of tooth position, gender, and age on the anatomical position of mandibular molars. Results: The buccal alveolar bone thickness at 3 mm above the root apex of the mandibular second molar demonstrates a significantly higher value when compared to that of the first molar. Nonetheless, concerning the buccolingual root thickness, no significant differences were observed between these two teeth. In addition, the buccal alveolar bone thickness and buccolingual root thickness at 3 mm above the root apex may not be influenced by gender and age. Conclusion: The anatomical structures of the posterior region of the mandible in Taiwanese individuals exhibited variations between the mandibular first and second molars. However, these differences were not influenced by gender or age.

Comparison sealing ability in three bioceramic sealers applied in hydraulic condensation technique by using micro-computed tomography.

Background/purpose: Sealing ability in root canal obturation has always been a key concern for endodontic success. The purpose of this study was to analyze the percentage of voids in root canal space obturated by using single cone hydraulic condensation with different root canal sealers and to compare those with AH Plus sealer. Materials and methods: Experiments were conducted using twenty 3D-printed upper first premolars. After the buccal root canals were prepared using Ni-Ti rotary instruments, the teeth were divided into four groups: the AH Plus, BC sealer, BC sealer HiFlow, and Endoseal MTA groups. All buccal canals were obturated by single-cone hydraulic condensation. All specimens were scanned using micro-computed tomography and the percentage volume of the voids inside and outside the filled materials (Vin and Vout) at three different canal depth intervals were calculated by a Bruker micro-CT software. Differences according to root canal sealers were evaluated statistically using the Kruskal-Wallis test and the Wilcoxon Rank Sum test at a significance level of 0.05. Results: The results indicated that most of the voids were presented near the interface (Vout), the Vin is very small and not significant different between groups. The Vout decreased in the following order: AH Plus(1.837% ± 1.226%)≅BC sealer (1.225% ± 0.836%)>BC sealer Hiflow(0.349% ± 0.071%)>Endoseal MTA(0.203% ± 0.049%). Conclusion: For the percentage volume of voids between the root canal filling material and root canal surface, though the BC sealer Hiflow is slightly larger than Endoseal MTA, which is still much less than BC sealer and AH Plus.

Distribution of Yeast Species and Risk Factors of Oral Colonization after Oral-Care Education among the Residents of Nursing Homes.

Most yeasts causing infections in humans are part of commensal microflora and etiological agents of different infections when hosts become susceptible, usually due to becoming immunocompromised. The colonization of potentially pathogenic microbes in the oral cavity is increased by poor oral hygiene. This follow-up survey was conducted approximately two months after providing information on proper oral care at 10 nursing homes in Taiwan. Among the 117 of 165 residents colonized by yeasts, 67 were colonized by more than one yeast species. A total of 231 isolates comprising eight fungal genera and 25 species were identified. Candida albicans (44.6%) was the dominant species, followed by Candida glabrata (17.7%), Candida parapsilosis (8.7%), Candida tropicalis (7.8%), and Candida pararugosa (7.3%). Residents having a yeast colony-forming unit >10 (OR, 8.897; 95% CI 2.972−26.634; p < 0.001) or using a wheelchair (OR, 4.682; 95% CI 1.599−13.705; p = 0.005) were more likely to be colonized by multiple species. By comparing before and after oral-care education, dry mouth (OR, 3.199; 95% CI 1.448−7.068; p = 0.011) and having heart disease (OR, 2.681; 95% CI 1.068−6.732; p = 0.036) emerged as two independent risk factors for increased density of colonizing yeast.

Effect of screw fixation on temporomandibular joint condylar prosthesis.

PURPOSE: The objective of the present study was to evaluate the effect of the number of screws on the stress and stability of the temporomandibular joint (TMJ) condylar prosthesis and on the strain distribution in the bone. MATERIALS AND METHODS: Three-dimensional, finite element models of the mandible and a TMJ condylar prosthesis with fixations involving different numbers of screws in 8 configurations were established to investigate the effect of the number of fixed screws on the stress and stability of the implant and strain in cortical and cancellous bone. RESULTS: The simulations showed that increasing the number of screws beyond 3 only slightly enhanced the implant stability and reduced the implant stress. The position of the inserted screws significantly affected the strain distributions in cortical and cancellous bone tissues. CONCLUSIONS: The results of our study have shown that 3 staggered screws can provide optimal implant stability and bone stress and strain distributions in a TMJ condylar prosthesis.

Bone density changes around teeth during orthodontic treatment.

The objective of this study was to evaluate bone density changes around the teeth during orthodontic treatment by using cone beam computed tomography (CBCT). CBCT was used to measure the bone densities around six teeth (both maxilla central incisors, lateral incisors, and canines) before and after 7 months of orthodontic treatment in eight patients. In addition, each root was divided into three portions (cervical, intermediate, and apical) to determine whether the bone density change varied with tooth level. The mean reduction in bone density around the measured teeth was 24% after orthodontic treatment. The bone density reduction around teeth was largest for the upper-right and upper-left central incisor (29% and 26%, respectively) and ranged from 20% to 23% for the other four teeth. The mean bone density reduction did not differ significantly between the cervical, portion, and apical portions of the teeth (26%, 22%, and 24%, respectively). CBCT is useful for evaluating bone density changes around teeth during orthodontic treatment. The bone density around the teeth reduced significantly after the application of orthodontic forces for 7 months.

The relationship of the occurrence between three-rooted deciduous mandibular second molars and three-rooted permanent mandibular first molars in children.

BACKGROUND/PURPOSE: This study aimed to determine the correlation between the occurrence of three-rooted deciduous mandibular second molars and three-rooted permanent mandibular first molars in children. MATERIALS AND METHODS: Orthopantograms (n = 977) obtained from August 2008 to December 2010 were retrospectively screened and examined. Among the 977 orthopantograms, those of 591 participants (314 boys and 277 girls; mean age, 8.7 years) with bilateral deciduous mandibular second molars and permanent mandibular first molars were studied. The gender predilection and prevalence of three-rooted mandibular molars were assessed, and the pattern of concurrence was investigated. RESULTS: The prevalence of three roots were 28.4% and 27.6% in the deciduous mandibular second molars and permanent mandibular first molars, respectively. Bilateral occurrence of three-rooted mandibular molars was almost 60% for both deciduous and permanent molars. There was a significantly greater prevalence of three-rooted mandibular molars on the right side of the mandible than that on the left side. CONCLUSION: Deciduous and permanent molars show a similar prevalence of three roots. The presence of three-rooted deciduous mandibular second molar can strongly predict the possibility of three roots in permanent mandibular first molar.

Effects of cortical bone thickness and implant length on bone strain and interfacial micromotion in an immediately loaded implant.

PURPOSE: The aim of this study was to evaluate the effects of cortical bone thickness and implant length on strain in the surrounding bone and micromotion at the bone-implant interface in single immediately loaded implants. MATERIALS AND METHODS: Experiments with rapid prototyping technique and finite element simulations were performed to evaluate bone strain and micromotion at the bone-implant interface. Implants (13-mm long) were embedded into models with three thicknesses of cortical bone (0.5, 1.7, and 3.4 mm), and implants with different lengths (11.5 and 15.0 mm) were inserted into models with 1.7 mm of thickness of cortical bone. Vertical and lateral loads of 130 N were applied to the models. RESULTS: On lateral loading, the strains were highly concentrated on one side of the mandible in both experimental and finite element models. Sliding and gap distances were reduced when the cortical bone was thicker and when the implant was longer. CONCLUSION: Placement of a longer implant into thicker cortical bone will result in reduced sliding and gap distances. However, bone strain is influenced more by the cortical bone thickness than by the implant length for single immediately loaded implants.

Prevalence of three-rooted primary mandibular first molars in Taiwan.

BACKGROUND/PURPOSE: Knowledge of root canal anatomy is important for dental practice and for identifying features of anthropological significance. Three-rooted permanent mandibular molars are considered an anatomical variant of the Mongoloid race. This study aimed to determine the prevalence of three-rooted primary mandibular first molars in Taiwanese subjects. METHODS: Vertical bite-wing radiographs of 227 subjects, which had been obtained previously in the Department of Pediatric Dentistry, Taichung Veterans General Hospital, Taichung, Taiwan, from January 2004 to December 2007, were screened retrospectively. Images of 121 subjects [54 boys and 67 girls; mean age (range), 5.8 (2.4-10.4) years] who had bilateral primary mandibular first molars were studied. The sex, symmetry and frequency of occurrence of three-rooted primary mandibular first molars were recorded and statistically analyzed. RESULTS: The overall prevalence of subjects with three-rooted primary mandibular first molars was 5.0% (6/121), and 83.0% of the molars were unilateral. The prevalence of teeth that showed an extra root among all teeth examined was 2.9% (7/242). Such prevalence did not differ significantly between the right and left sides of the mandible, bilateral and unilateral, or with sex. CONCLUSION: The data presented here indicate that approximately 5% of Taiwanese subjects had a threerooted mandibular primary first molar and 80% of such teeth occurred unilaterally. Dentists should take into account the prevalence of these three-rooted variants in primary mandibular first molars among Taiwanese patients during their daily endodontic and exodontic procedures.

Prevalence of 3-rooted primary mandibular second molars among chinese patients.

PURPOSE: The purpose of this study was to determine the prevalence of 3-rooted primary mandibular second molar teeth in Chinese patients via vertical bitewing radiography. METHODS: Vertical bitewing radiographs of 227 patients previously obtained from the Department of Pediatric Dentistry, Taichung Veterans General Hospital, Taichung City, Taiwan, from June 2004 to July 2007 were retrospectively screened and examined. Images of 185 patients (92 boys and 93 girls; mean age=5.6 [range=2.5-11.9] years old) with bilateral primary mandibular second molars were studied. The gender, symmetry, and frequencies of occurrence of 3-rooted primary mandibular second molars were compared. RESULTS: Eighteen (9%) 3-rooted primary mandibular second molars were found in the 185 patients, with a bilateral incidence of a symmetrical distribution of 28% (5/18). The prevalence of 3-rooted primary second molars did not differ significantly between the mandible's right and left sides (P<.41), or with gender (P<.31). CONCLUSIONS: The data presented here indicate that approximately one tenth of Chinese individuals have a 3-rooted primary mandibular second molar and that this condition is bilaterally symmetric in approximately one third of such individuals in a Taiwan hospital.

Effect of Scanning Resolution on the Prediction of Trabecular Bone Microarchitectures Using Dental Cone Beam Computed Tomography.

Assessing bone quality and quantity at the location of dental implants before dental implantation is crucial. In recent years, dental cone-beam computed tomography (dental CBCT) has often been used to assess bone quality and quantity prior to dental implant. However, the effect of scanning resolution on the prediction of trabecular bone microarchitectural parameters (TBMPs) remains unclear. The objective of this study was to examine how dental CBCT with various scanning resolution differs with regard to predicting TBMPs. This study used micro-computed tomography (micro-CT) with 18 µm resolution and dental CBCT with 100 µm and 150 µm resolutions on 28 fresh bovine vertebrae cancellous bone specimens. Subsequently, all images were input into the ImageJ software to measure four TBMPs: bone volume total volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp). One-way analysis of variance and Tukey's test were subsequently used to assess the differences between three scanning modes for the four TBMPs. In addition, correlations between measurement results obtained from micro-CT and dental CBCT with two resolutions were measured. The experimental results indicated that significant differences in four TBMPs were observed between micro-CT and dental CBCT (p < 0.05). The correlation coefficients between BV/TV, Tb.N, and Tb.Sp obtained from micro-CT and from dental CBCT with 100 µm resolution (0.840, 0.739, and 0.820, respectively) were greater than the correlation coefficients between BV/TV, Tb.N, and Tb.Sp obtained from micro-CT and from dental CBCT with 150 µm resolution (0.758, 0.367, and 0.724, respectively). The experimental results revealed that the TBMPs measured with dental CBCT with two resolutions differed from ideal values, but a higher resolution could provide more accurate prediction results, particularly for BV/TV, Tb.N, and Tb.Sp.

Caffeic Acid-coated Nanolayer on Mineral Trioxide Aggregate Potentiates the Host Immune Responses, Angiogenesis, and Odontogenesis.

INTRODUCTION: The aim of this study was to investigate whether mineral trioxide aggregate (MTA) can be modified with caffeic acid (CA) to form caffeic acid/mineral trioxide aggregate (CAMTA) cement and to evaluate its physicochemical and biological properties as well as its capability in immune suppression and angiogenesis. METHODS: MTA was immersed in trishydroxymethyl aminomethane buffer with CA to allow coating onto MTA powders. X-ray diffractometry and tensile stress-strain tests were conducted to assess for physical characteristics of CAMTA and to evaluate for successful modification of MTA. Then, the CAMTA cement was immersed in simulated body fluid to evaluate its hydroxyapatite formation capabilities and Si release profiles. In addition, RAW 264.7 cells and human dental pulp stem cells were used to evaluate CAMTA's immunosuppressive capabilities and cell responses, respectively. hDPSCs were also used to assess CAMTA's angiogenic capabilities. RESULTS: The X-ray diffractometry results showed that CA can be successfully coated onto MTA without disrupting or losing MTA's original structural properties, thus allowing us to retain the initial advantages of MTA. CAMTA was shown to have higher mechanical properties compared with MTA and had rougher pitted surfaces, which were hypothesized to lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. In addition, it was found that CAMTA was able to enhance hydroxyapatite formation and immunosuppressive capabilities compared with MTA. CONCLUSIONS: CAMTA cements were found to have improved physicochemical and biological characteristics compared with their counterpart. In addition, CAMTA cements had enhanced odontogenic, angiogenic, and immunosuppressive properties compared with MTA. All of the results of this study proved that CAMTA cements could be a biomaterial for future clinical applications and tissue engineering use.

Bone stress and interfacial sliding analysis of implant designs on an immediately loaded maxillary implant: a non-linear finite element study.

OBJECTIVES: This study investigated the surrounding bone stress and the implant-bone interfacial sliding of implant designs and implant sizes of immediately loaded implant with maxillary sinus augmentation by using three-dimensional (3D) non-linear finite element (FE) analysis. METHODS: Twenty-four FE models including four implant designs (cylindrical, threaded, stepped and step-thread implants) and three implant dimensions (standard, long and wide threaded implants) with a bonded and three levels of frictional contact of implant-bone interfaces were analyzed. The maxillary model was constructed from computer tomography (CT) images of a human skull and all 3D implant models were created via the computer-aided design (CAD) software. RESULTS: The use of threaded implants decreased the bone stress and sliding distance obviously about 30% as compared with non-threaded (cylindrical and stepped) implants. Increasing the implant's length or diameter reduced the bone stress by 13-26%. Employing a immediately loaded implant with smooth machine surface (mu=0.3, mu represents frictional coefficient) increased the bone stress by 28-63% as compared with the osseointegrated (bonded interfaces) implants. Roughening the implant surface (mu>0.3) did not reduced the bone stress, however it did decrease the interfacial sliding between implant and bone. CONCLUSIONS: For an immediately loaded implant placed with sinus augmentation, using threaded implant could decrease both the bone stress and implant-bone sliding distance which may improve the implant initial stability and long-term survival. Rough surface of implants shows no benefit to reduce the bone stress but they could lower the interfacial sliding. On the contrary, employing long or wide implants decrease the bone stress but they cannot diminish the interfacial sliding.

Endodontic shaping performance using nickel-titanium hand and motor ProTaper systems by novice dental students.

BACKGROUND/PURPOSE: Preparing a continuous tapering conical shape and maintaining the original shape of a canal are obligatory in root canal preparation. The purpose of this study was to compare the shaping performance in simulated curved canal resin blocks of the same novice dental students using hand-prepared and engine-driven nickel-titanium (NiTi) rotary ProTaper instruments in an endodontic laboratory class. METHODS: Twenty-three fourth-year dental students attending China Medical University Dental School prepared 46 simulated curved canals in resin blocks with two types of NiTi rotary systems: hand and motor ProTaper files. Composite images were prepared for estimation. Material removed, canal width and canal deviation were measured at five levels in the apical 4 mm of the simulated curved canals using AutoCAD 2004 software. Data were analyzed using Wilcoxon's rank-sum test. RESULTS: The hand ProTaper group cut significantly wider than the motor rotary ProTaper group in the outer wall, except for the apical 0 mm point. The total canal width was cut significantly larger in the hand group than in the motor group. There was no significant difference between the two groups in centering canal shape, except at the 3 mm level. CONCLUSION: These findings show that the novice students prepared the simulated curved canal that deviated more outwardly from apical 1 mm to 4 mm using the hand ProTaper. The ability to maintain the original curvature was better in the motor rotary ProTaper group than in the hand ProTaper group. Undergraduate students, if following the preparation sequence carefully, could successfully perform canal shaping by motor ProTaper files and achieve better root canal geometry than by using hand ProTaper files within the same teaching and practicing sessions.