Nanophotosensitizers Composed of Phenyl Boronic Acid Pinacol Ester-Conjugated Chitosan Oligosaccharide via Thioketal Linker for Reactive Oxygen Species-Sensitive Delivery of Chlorin e6 against Oral Cancer Cells

Chlorin E6 (Ce6)-incorporated nanophotosensitizers were fabricated for application in photodynamic therapy (PDT) of oral cancer cells. For this purpose, chitosan oligosaccharide (COS) was conjugated with hydrophobic and reactive oxygen species (ROS)-sensitive moieties, such as phenyl boronic acid pinacol ester (PBAP) via a thioketal linker (COSthPBAP). ThdCOOH was conjugated with PBAP to produce ThdCOOH-PBAP conjugates and then attached to amine groups of COS to produce a COSthPBAP copolymer. Ce6-incorporated nanophotosensitizers using the COSthPBAP copolymer were fabricated through the nanoprecipitation and dialysis methods. The Ce6-incorporated COSthPBAP nanophotosensitizers had a small diameter of less than 200 nm with a mono-modal distribution pattern. However, it became a multimodal and/or irregular distribution pattern when H₂O₂ was added. In a morphological observation using TEM, the nanophotosensitizers were disintegrated by the addition of H₂O₂, indicating that the COSthPBAP nanophotosensitizers had ROS sensitivity. In addition, the Ce6 release rate from the COSthPBAP nanophotosensitizers accelerated in the presence of H₂O₂. The SO generation was also higher in the nanophotosensitizers than in the free Ce6. Furthermore, the COSthPBAP nanophotosensitizers showed a higher intracellular Ce6 uptake ratio and ROS generation in all types of oral cancer cells. They efficiently inhibited the viability of oral cancer cells under light irradiation, but they did not significantly affect the viability of either normal cells or cancer cells in the absence of light irradiation. The COSthPBAP nanophotosensitizers showed a tumor-specific delivery capacity and fluorescence imaging of KB tumors in an in vivo animal tumor imaging study. We suggest that COSthPBAP nanophotosensitizers are promising candidates for the imaging and treatment of oral cancers.

A large invasive chondroblastoma on the temporomandibular joint and external auditory canal: a case report and literature review

BACKGROUND

Chondroblastomas, which account for approximately 1% of all bone tumors, typically occur in long bones, such as the femur, humerus, and tibia. However, in extremely rare cases, they may also occur in the craniofacial region where the tumor is often found in the squamous portion of the temporomandibular joint (TMJ) and in the temporal bone.

CASE PRESENTATION

This case report describes a large chondroblastoma (diameter, approximately 37 mm) that occurred in the TMJ. The tumor was sufficiently aggressive to destroy the TMJ, mandibular condyle neck, external auditory canal (EAC), mandibular fossa of the temporal bone, and facial nerve. The tumor was completely excised using a pre-auricular approach. The EAC and surgical defect were successfully reconstructed using a temporoparietal fascia flap (TPFF) and an inguinal free fat graft. There was no local tumor recurrence at the 18-month follow-up visits. However, the patient developed sensory neural hearing loss, and his eyebrow paralysis worsened, eventually requiring plastic surgery.

CONCLUSION

Large, invasive chondroblastomas of the TMJ can be completely removed through a pre-auricular approach, and the resulting surgical defect can be reconstructed using TPFF and free fat grafts. However, preoperative evaluation of the facial nerve and auditory function is necessary. Therefore, a multidisciplinary approach is essential.

Upper airway stimulation as an alternative to maxillomandibular advancement for obstructive sleep apnoea in a patient with dentofacial deformity: case report with literature review

Obstructive sleep apnoea (OSA) is characterized by repeated upper airway collapse leading to oxygen desaturation resulting in cardiovascular and neurocognitive sequelae. Upper airway surgeries such as palatopharyngoplasty, tongue base surgery, and maxillomandibular advancement can improve patient tolerance of continuous positive airway pressure, quality of life, and the severity of OSA. Upper airway stimulation (UAS) of the hypoglossal nerve is a contemporary US Food and Drug Administration-approved treatment modality for OSA with a fundamentally different mechanism. We report the case of a 65-year-old male with a high body mass index, hypertension, diabetes, dentofacial deformity, and severe OSA. He presented with a respiratory distress index (RDI) of 89.1 events per hour, apnoea-hypopnoea index (AHI) of 82.7 events per hour, and minimum oxygen saturation of 75%. He chose to undergo UAS. Initially, complete concentric collapse of the velum was found during drug-induced sedation endoscopy, which was converted by palatopharyngoplasty to meet inclusion criteria for UAS. The patient achieved surgical cure with postoperative RDI and AHI of 2 events per hour with minimum oxygen saturation of 83%, and resolution of daytime somnolence. UAS is an effective surgical option to broaden the surgeon's ability to treat OSA, especially if facial skeletal surgery is contraindicated or declined by the patient with dentofacial deformity.

Healing outcomes of root canal treatment for C-shaped mandibular second molars: a retrospective analysis

Objectives

This study aimed to evaluate the healing rate of non-surgical endodontic treatment between C-shaped and non-C-shaped mandibular second molars.

Materials and Methods

Clinical records and radiological images of patients who had undergone endodontic treatment on mandibular second molars between 2007 and 2014 were screened. The periapical index scoring system was applied to compare healing outcomes. Information about preoperative and postoperative factors as well as the demographic data of the patients was acquired and evaluated using chi-square and multinomial logistic regression tests.

Results

The total healing rate was 68.4%. Healing rates for the mandibular second molar were 70.9% in C-shaped canals (n = 79) and 66.6% in non-C-shaped ones (n = 117). The difference was not statistically significant.

Conclusions

The presence of a C-shaped canal in the mandibular second molar did not have a significantly negative effect on healing after treatment. Instead, proper pulpal diagnosis and final restoration were indicated as having significantly greater influence on the healing outcomes of C-shaped and non-C-shaped canals, respectively.

Finite element analysis on stress distribution of maxillary implant-retained overdentures depending on the Bar attachment design and palatal coverage

PURPOSE

The purpose of this study was to determine the effect of anchorage systems and palatal coverage of denture base on load transfer in maxillary implant-retained overdenture.

MATERIALS AND METHODS

Maxillary implant-retained overdentures with 4 implants placed in the anterior region of edentulous maxilla were converted into a 3-D numerical model, and stress distribution patterns in implant supporting bone in the case of unilateral vertical loading on maxillary right first molar were compared with each other depending on various types of anchorage system and palatal coverage extent of denture base using three-dimensional finite element analysis.

RESULTS

In all experimental models, the highest stress was concentrated on the most distal implant and implant supporting bone on loaded side. The stress at the most distal implant-supporting bone was concentrated on the cortical bone. In all anchorage system without palatal coverage of denture base, higher stresses were concentrated on the most distal implant and implant supporting bone on loaded side.

CONCLUSION

It could be suggested that when making maxillary implant retained overdenture, using Hader bar instead of milled bar and full palatal coverage rather than partial palatal coverage are more beneficial in distributing the stress that is applied on implant supporting bone.

Magnesium vs. machined surfaced titanium - osteoblast and osteoclast differentiation

PURPOSE

This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source.

MATERIALS AND METHODS

40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs).

RESULTS

MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM.

CONCLUSION

Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.

Effects of layering technique on the shade of resin overlays and the microhardness of dual cure resin cement

The purpose of this study was to assess the color of layered resin overlays and to test the early microhardness of dual cure resin cement (DCRC) light cured through the layered resin overlays. Resin overlays of 1.5 mm thickness were fabricated with the A3 shade of Z350 (Group 1L), the A3B and A3E shades of Supreme XT (Group 2L), and the A3, E3, and T1 shades of Sinfony (Group 3L) using one, two, and three layers, respectively (n=7). Each layer of the resin overlays was set in equal thickness. The color of the resin overlays was measured with a colorimeter and compared with an A3 shade resin denture tooth. DCRC was light cured through the resin overlays, and the early microhardness of the DCRC was measured. The ΔE value between the denture tooth and the resin overlays and the Vickers hardness number (VHN) of the DCRC were analyzed with one-way ANOVA and Tukey's HSD test. The color differences were 8.9±0.5, 5.3±1.0, and 7.3±0.5 and the VHNs were 19.4±1.1, 21.1±0.9, and 29.3±0.6 for Groups 1L, 2L, and 3L, respectively. Therefore, to match the designated tooth color of resin inlays and to increase the early microhardness of DCRC, layered resin inlays are more appropriate than single-dentin-layer resin inlays. However, the translucent layer should be used cautiously because the color difference of resin inlays with a translucent layer was affected more than those without a translucent layer.

Healing after horizontal root fractures: 3 cases with 2-year follow-up

Among dental traumas, horizontal root fractures are relatively uncommon injuries. Proper initial management and periodical evaluation is essential for the successful treatment of a root-fractured tooth. If pulpal necrosis develops, endodontic treatment is indicated, exclusively for the coronal fragment. Fragment diastases exert a great influence on healing at the fracture line and on pulpal necrosis. An adequately treated root-fractured tooth has a good prognosis. This case report describes the treatment and 2-yr follow up of 3 maxillary central incisors, first with horizontal root fracture, second with horizontal root fracture and avulsion, and third with horizontal root fracture and lateral luxation. All three cases were treated with mineral trioxide aggregate (ProRoot, Dentsply). During 2 yr of follow-up evaluation, the root-fractured teeth of the present patients were well retained in the arch, showing periodontal healing, even after endodontic treatment.

Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin

Objective

The aim of this study was to evaluate the effect of multiple layers of an infection control barrier on the micro-hardness of a composite resin.

Material and Methods

One, two, four, and eight layers of an infection control barrier were used to cover the light guides of a high-power light emitting diode (LED) light curing unit (LCU) and a low-power halogen LCU. The composite specimens were photopolymerized with the LCUs and the barriers, and the micro-hardness of the upper and lower surfaces was measured (n=10). The hardness ratio was calculated by dividing the bottom surface hardness of the experimental groups by the irradiated surface hardness of the control groups. The data was analyzed by two-way ANOVA and Tukey's HSD test.

Results

The micro-hardness of the composite specimens photopolymerized with the LED LCU decreased significantly in the four- and eight-layer groups of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. The hardness ratio of the composite specimens was <80% in the eight-layer group. The micro-hardness of the composite specimens photopolymerized with the halogen LCU decreased significantly in the eight-layer group of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. However, the hardness ratios of all the composite specimens photopolymerized with barriers were <80%.

Conclusions

The two-layer infection control barrier could be used on high-power LCUs without decreasing the surface hardness of the composite resin. However, when using an infection control barrier on the low-power LCUs, attention should be paid so as not to sacrifice the polymerization efficiency.

Power density of various light curing units through resin inlays with modified layer thickness

OBJECTIVES

The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers.

MATERIALS AND METHODS

To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured.

RESULTS

Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05). Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units.

CONCLUSIONS

To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

Endodontic management of a C-shaped maxillary first molar with three independent buccal root canals by using cone-beam computed tomography

The aim of this study was to present a method for endodontic management of a maxillary first molar with unusual C-shaped morphology of the buccal root verified by cone-beam computed tomography (CBCT) images. This rare anatomical variation was confirmed using CBCT, and nonsurgical endodontic treatment was performed by meticulous evaluation of the pulpal floor. Posttreatment image revealed 3 independent canals in the buccal root obturated efficiently to the accepted lengths in all 3 canals. Our study describes a unique C-shaped variation of the root canal system in a maxillary first molar, involving the 3 buccal canals. In addition, our study highlights the usefulness of CBCT imaging for accurate diagnosis and management of this unusual canal morphology.

Machine learning methods applied to pharmacokinetic modelling of remifentanil in healthy volunteers: a multi-method comparison

This study compared the blood concentrations of remifentanil obtained in a previous clinical investigation with the predicted remifentanil concentrations produced by different pharmacokinetic models: a non-linear mixed effects model created by the software NONMEM; an artificial neural network (ANN) model; a support vector machine (SVM) model; and multi-method ensembles. The ensemble created from the mean of the ANN and the non-linear mixed effects model predictions achieved the smallest error and the highest correlation coefficient. The SVM model produced the highest error and the lowest correlation coefficient. Paired t-tests indicated that there was insufficient evidence that the predicted values of the ANN, SVM and two multi-method ensembles differed from the actual measured values at alpha = 0.05. The ensemble method combining the ANN and non-linear mixed effects model predictions outperformed either method alone. These results indicated a potential advantage of ensembles in improving the accuracy and reducing the variance of pharmacokinetic models.

Simvastatin promotes odontoblastic differentiation and expression of angiogenic factors via heme oxygenase-1 in primary cultured human dental pulp cells

INTRODUCTION

Although simvastatin has multiple demonstrable effects, its function in dentinogenesis remains unclear. In this study, we tested the hypothesis that the addition of simvastatin to human dental pulp cells (HDPCs) stimulates odontogenesis both by promoting odontoblastic differentiation and by favoring the release of angiogenic factors. In addition, the role of heme oxygenase-1 (HO-1) in these effects was investigated.

METHODS

The expression of markers for odontoblastic differentiation and angiogenesis was analyzed by means of alkaline phosphatase (ALP) activity, alizarin red staining, and Western blotting.

RESULTS

Simvastatin enhanced the differentiation of HDPCs by up-regulating mineralization nodules and odontogenic markers as well as angiogenic markers. These phenomena were then correlated with the induction of HO-1 protein levels. The inducing effect of simvastatin on odontoblastic differentiation and angiogenesis was nullified by an HO-1 inhibitor and a carbon monoxide (CO) scavenger.

CONCLUSIONS

These results suggested that simvastatin exerts its odontoblastic differentiation and angiogenesis-inducing effects in HDPCs through a mechanism that involves the action of HO-1 and its product CO.

Tissue-specific expression of the subunits of chick 20S proteasomes

The subunit patterns of the proteasomes, that were purified from muscle, liver and brain, were found to be significantly different from one another. Furthermore, the proteasomes from adult and embryonic tissues of the same types also differed from each other in their subunit patterns. In addition, the specific activities of the purified proteasomes for peptide-cleavage, but not for casein-hydrolysis, appeared to be varied among the enzymes isolated from the different tissues. Thus, expression of a large number of proteasome subunits appears to be tissue-specific and under developmental control, although its relation with the multicatalytic activities of the proteasomes remains unclear.

Developmental regulation of proteolytic activities and subunit pattern of 20 S proteasome in chick embryonic muscle

The proteolytic activities of the 20 S proteasome were found to change in their levels during the development of chick embryonic muscle. The peptide-cleaving activities against N-succinyl-Leu-Leu-Val-Tyr-7-amido-4-methylcoumarin and N-benzyloxycarbonyl-Ala-Arg-Arg-4-methoxy-beta-naphthylamide gradually decreased with the time of development. On the other hand, the casein-degrading activity in the presence of poly-L-lysine markedly increased from embryonic day 11 and reached a maximal level by day 17. These changes appeared to be tissue-specific because little or no change in any of the proteolytic activities was observed with developing embryonic brain, while dramatic alterations occurred in the extents of the peptide hydrolyses in liver. Furthermore, a number, but not all, of the proteasome subunits in embryonic muscle were changed in their amounts during the development. These results suggest that the alterations in the proteasome activities and subunit pattern are developmentally regulated and may be correlated.

Effects of leucine on in vitro protein synthesis and degradation in rat skeletal muscles

Weanling rats were used to examine the role of leucine in in vitro protein turnover in skeletal muscles. In three experiments, rats were subjected to 24 or 72 hours of food deprivation or 5 days of consuming a protein-free diet or injection of streptozotocin. The soleus and extensor digitorum longus muscles were removed and utilized for measures of protein synthesis or degradation by using the isolated, incubated muscle technique of Li et al. These experiments demonstrate that supplementation of the incubation media with 0.5 mM leucine stimulates protein synthesis in these catabolic muscles and that during total starvation the stimulation decreases as the severity of the condition increases. Leucine supplementation failed to affect protein degradation in these skeletal muscles. This study demonstrates that the branched-chain amino acid leucine has the potential to stimulate protein synthesis in skeletal muscles, at least under specific catabolic conditions, but does not affect protein degradation in skeletal muscles under the conditions studied.