Current status of dental journals published by Japanese organization

The publication status of dental journals in Japan was examined, with a focus on metrics such as Journal Impact Factor (JIF), Eigenfactor, Article Influence Score, and percentage of open access. A total of 18 journals published by Japanese dental organizations were identified in the Journal Citation Reports (JCR), with JIF values ranging from 0.4 to 6.6. The highest JIF was observed in The Japanese Dental Science Review. Additionally, 16 journals were not listed on the JCR. The authors explored the implications of these findings on the visibility and impact of Japanese dental research, and discussed the potential benefits of embracing open-access publications for greater global dissemination. This study highlighted the opportunities for journals to enhance their international recognition by meeting the criteria for JIF inclusion and embracing open-access publications. By adopting effective publication strategies, the dental community in Japan will be able to contribute to the advancement of dentistry globally, ensuring broader accessibility and recognition of its research contributions.

Effect of low-temperature degradation and sintering protocols on the color of monolithic zirconia crowns with different yttria contents

This study investigated the effects of low-temperature degradation (LTD) on the L*, a*, and b* values of highly translucent zirconia crowns. Four types of zirconia disks with different yttria contents (IPS e.max ZirCAD LT, IPS e.max ZirCAD MT, IPS e.max ZirCAD MT Multi, IPS e.max ZirCAD Prime, Ivoclar) and two shades (A2 and BL) were used. A crown was manufactured using four types of zirconia and LTD treated. Color measurements were performed, and the color difference (ΔE00) before and after LTD was calculated. The microstructure was determined through X-ray fluorescence and X-ray diffractometry. Highly translucent zirconia crowns showed greater changes in the a* and b* values than in the L* value after LTD, regardless of the shade. The Multi2 crowns exhibited a discernible color change due to the LTD treatment. The X-ray fluorescence results did not reveal any apparent change in the microstructure between sintering programs for all zirconia specimens.

Surveillance study on the application of titanium and its alloys to removable dental prostheses

This review describes individual studies of removable dental prostheses, evaluated their performance and clinical applicability for the proposal to expand health insurance coverage of titanium and its alloys to removable dental prostheses. Titanium and its alloys have become clinically applicable as prosthetic materials by improving dental casting systems. They have high biosafety and good mechanical properties, are excellent substitutes for the silver-palladium-gold alloys for casting, and are highly useful for removable dental prostheses. Therefore, the introduction of health insurance coverage for removable dental prostheses made of titanium and its alloys is worthy of consideration.

Effects of methacryloyloxydecyl dihydrogen phosphate on bonding of tri-n-butylborane-initiated resin to human enamel

This study investigated the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) in methyl methacrylate (MMA) monomer on the adhesion of tri-n-butylborane (TBB)-initiated resins (MDP/MMA-TBB resins) to human enamel. Enamel surface conditions were either polished only or phosphatized surfaces. The 1.0, 1.7, and 2.0 mol% MDP/MMA-TBB resins, 4-methacryloxyethyl trimellitate anhydride (4-META)/MMA-TBB resin and MMA-TBB resin were prepared as luting materials. The shear bond strength was determined before and after thermocycles, and the results were compared using non-parametric statistical analyses (each, n=15). The MDP/MMA-TBB resins showed significantly better bond durability to enamel than other resins with or without etching. The 1.7 and 2.0 mol% MDP/MMA-TBB resins were suggested to be the optimum MDP concentrations from pre- and post-thermocycling results for the non-etched specimens. The TBB initiator resin including MDP was shown to be effective in bonding to human enamel, and this effect was enhanced in combination with phosphate treatment.

Effect of luting system with acidic primers on the durability of bonds with Ti-15Mo-5Zr-3Al titanium alloy and its component metals

This study evaluated the effect of luting system with acidic primers on the durability of bonds with Ti-15Mo-5Zr-3Al titanium alloy (Ti-15Mo-5Zr-3Al) and its component metals. Adherend metals were Ti-15Mo-5Zr-3Al, Ti, Mo, Zr, and Al. Four primers were evaluated as adhesion promoters: Alloy Primer (ALP), Estenia Opaque Primer (EOP), M. L. Primer (MLP), and Super Bond liquid (SBL). An acrylic resin was used as the luting material. Pre- and post-thermocycling shear bond strength was determined to evaluate the bonding durability, and the results were compared using non-parametric statistical analyses (n=11/group). The post-thermocycling bond strength in MPa (median) associated with ALP, EOP, MLP, and SBL were 18.8, 19.8, 4.1, and 0.8, respectively, for Ti-15Mo-5Zr-3Al. The results showed that two primers containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) were effective for the durability of bonding of Ti-15Mo-5Zr-3Al to the resin. MDP enhanced the bonding durability of the resin bonded to either Ti, Zr, or Al.

Effect of multi-purpose primer on bonding of acrylic resin to cast titanium and gold alloy after airborne-particle abrasion

PURPOSE

To clarify the effect of a multi-purpose primer combining several functional monomers on two prosthodontic materials (cast titanium and a gold alloy) after airborne-particle abrasion.

METHODS

Disk-shaped adherends were prepared from cast titanium (CP Titanium JIS2) and a gold alloy (Casting Gold M.C. Type IV). A silane-containing two-liquid primer (M&C primer (MC)) and two silane-free single-liquid primers (Alloy Primer (AP) and V-Primer (VP)) were used as surface-treatment agents. The shear bond strengths were determined before and after thermocycling to evaluate the adhesive durability, and the results were compared using a non-parametric statistical analysis. The effect of airborne-particle abrasion with alumina on the titanium surface was analyzed by X-ray photoelectron spectroscopy (XPS).

RESULTS

There was no significant difference in bond strength between the MC and AP before and after thermocycling, whereas VP showed significantly lower values. XPS revealed that the titanium acquired hydrophilic properties after the airborne-particle abrasion.

CONCLUSIONS

The novelty of this study is that it shows that the presence/absence of the silane had no effect on the bonding of cast titanium with an acrylic resin. The study also showed that the multi-purpose primer can be used without any problems with both cast titanium and gold alloy, in combination with airborne-particle abrasion with alumina.

Effect of speed sintering of monolithic zirconia with different yttria contents on color and crystal phase

This study evaluated the color and microstructure of monolithic zirconia crowns with different yttrium oxide (Y₂ O₃ ) contents treated by conventional or speed sintering. Four types of zirconia ceramics were assessed: two monolayer zirconia, and two multilayer zirconia. The monolithic zirconia crowns were fabricated using a dental computer-aided design/computer-aided manufacturing (CAD/CAM) system and in two shades (A2 and BL). After milling, the zirconia crowns were sintered using either speed sintering or conventional sintering. For each combination of zirconia (4), shade (2), and sintering condition (2), the color parameters were determined at three positions of each of nine crowns using a non-contact dental spectrophotometer. In addition, the zirconia phases in the specimens were quantified using X-ray diffractometry. Significant differences in the ΔE₀₀ values at different measurement positions were observed for the Multi2 crown of the BL shade group. The color difference resulting from conventional and speed sintering programs was not affected by the difference in yttria content of Mono1, Mono2, and Multi1. However, in Multi2, containing 3Y-TZP and 5Y-PSZ, a color change was caused by the use of speed sintering. Therefore, when performing speed sintering with Multi2, it is necessary to select the color in consideration of these results or take measures for staining.

Usage of English prosthodontic terms 2019 in Japan

The use of a uniform terminology is important to avoid misunderstanding of concepts or procedures in discussion. The usage of English prosthodontic terms in Japan was investigated in the current study. English prosthodontic terms listed in The Glossary of Prosthodontic Terms edited by the Japan Prosthodontic Society (GPTJ-5) were compared to those in The Glossary of Prosthodontic Terms ninth edition (GPT-9). A small number of terms labeled as objectionable in GPT-9 were listed in GPTJ-5. This might indicate that it takes a long time to replace terms that are used widely.

Education and licensure of dental technicians

The Japanese Health, Labour, and Welfare Ministry in 2020 identified the following issues for training and recruitment of dental technicians: early involvement of students in dental practice and dental laboratory work, a curriculum in line with the times, and an extension of the years of training. This paper investigates the education and qualifications of dental technicians in other countries to discuss these issues. The survey method was to use the database PubMed to search the literature since 2001 using the keywords "dental technician," "education," and license" to collect literature related to the pre-graduate education of dental technicians. Information on educational institutions was also included in the survey. The results showed that the countries that introduced joint education between dental technicians and dentists into their educational programs, and the examinations and years of training required for each certification varied from country to country. The curriculum for dental technicians in Japan changed from a time-based to a credit-based system on April 1, 2018. The credit system is characterized by the possibility of each training institution actively engaging in flexible curriculum organization. Dental technician education programs in other countries can provide a valuable reference for each training institute to demonstrate its uniqueness.

Bonding of resin luting materials to titanium and titanium alloy

Recently in Japan, due to the increased prices of palladium and gold, cast titanium restorations have been included in the Japanese national health insurance system. The purpose of this review was to survey the available literature on titanium bonding systems, focusing on the adhesive monomer in the luting agent in order to expand the application of resin-bonded fixed prostheses made of titanium or titanium alloys. It was found that adhesive monomers are effective for bonding to titanium, and provide results equal to the procedures of silanization and tribochemical silica coating. A primer or a luting agent, including 10-methacryloyloxydecyl dihydrogen phosphate (MDP), methacryloyloxyalkyl thiophosphate derivative (MEPS), 6-methacryloxyhexyl phosphonoacetate (6-MHPA), and 4-methacryloyloxyethl trimellitate anhydride (4-META) promotes bonding characteristics between titanium and the resin material.

Bonding performance of a thiohydantoin-methacrylate monomer on noble metal alloys

This study assessed the effect of a primer containing 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP) on the bonding of noble metal alloys to an acrylic resin. Three noble metal alloys were selected as adherends, and V-Primer containing 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithione was used as a comparative control. The disk specimens of each noble metal alloy were wet-ground and divided into three conditions: specimens primed with MDTHP primer or V-Primer, and specimens without priming. An acrylic resin was bonded to each specimen, and the specimens were performed the shear bond test. The MDTHP primer showed higher shear bond strength than the V-Primer for all specimens. X-ray photoelectron spectroscopic analysis showed that MDTHP was adsorbed on the Au-Pt-Pd alloy surface even after acetone cleaning. MDTHP binds not only with Cu but also with Au and Ag, promoting the bond strength of noble metal alloys. The effectiveness of MDTHP on dental noble metal alloys was suggested.

Gloss and surface roughness of pre-polymerized composite materials designed for posterior CAD/CAM crown restorations corroded with acidulated phosphate fluoride application

This study assessed the gloss and surface roughness of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites corroded with acidulated phosphate fluoride (APF) application. One ceramic block, ten CAD/CAM resin composites for premolars, and four CAD/CAM resin composites for molars were assessed. The surface topography of the materials before and after APF application was observed using an electron microscope. The results were analyzed by Wilcoxon signed-rank test and Dunnett's many to one test (p<0.05). Gloss after APF application was significantly lower for all CAD/CAM resin composites except Artesano. Ra after APF application was significantly higher for all CAD/CAM resin composites except Artesano, Dentcraft HR Block, and Estelite P Block, and Sa was significantly higher for all CAD/CAM resin composites. Irregular surface topography was observed after APF application and the surface features differed among the materials. Therefore, APF application may be detrimental to the surface properties of CAD/CAM resin composites.

Impact of Anterior Clinoidectomy on Visual Function After Paraclinoid Carotid Artery Aneurysm Surgery: Power-Drill Versus No-Drill Technique

BACKGROUND

Few studies have attempted to make a direct comparison of the risk of visual impairment following extradural anterior clinoidectomy (EAC) with and without the use of a power drill.

OBJECTIVE

To evaluate postoperative visual outcomes between groups of patients with paraclinoid carotid artery aneurysms (PCAAs) who underwent surgical clipping with and without the use of a power drill during EAC.

METHODS

Between January 2010 and November 2019, 90 patients, 7 with ruptured and 83 with unruptured PCAAs, underwent clipping surgery at our hospital. The authors retrospectively analyzed postoperative visual complications from the medical records of these patients.

RESULTS

Among the 85 patients (excluding 3 patients with disturbance of consciousness caused by subarachnoid hemorrhage and 2 patients with preoperative visual disturbance) evaluated, EAC was conducted using a power drill in 64 patients and using a microrongeur in 21 patients. Permanent postoperative visual impairment developed in 14 (21.9%) patients in the drill group: 9 patients had ipsilateral lower nasal quadrant hemianopsia (ILNQH) and 5 patients had ipsilateral visual acuity reduction. Transient ILNQH developed in only 1 patient in the no-drill group. The incidence of permanent postoperative visual impairments was significantly lower in the no-drill group than in the drill group (P = .020). Seventeen (26.6%) patients developed transient oculomotor nerve palsy in the drill group, while no patients developed oculomotor nerve palsy in the no-drill group.

CONCLUSION

EAC using a microrongeur versus a power drill significantly improved visual outcomes after clipping surgery for PCAAs.

Bonding of Fused Quartz with an Aromatic Silane Compound and Acidic Functional Monomers with a Tri-n-butylborane Initiated Resin

Purpose: This study evaluated the effect of an aromatic silane compound and acidic functional monomer on the bond strength of fused quartz. Materials and Methods: A total of 264 disk specimens were fabricated from fused quartz for shear bond testing. Two silane compounds were used: 3-(trimethoxysilyl)propyl methacrylate (3-TMSPMA) and 3-(4-methacryloyloxyphenyl) propyltrimethoxysilane (3-MPPTS). As acidic functional monomers, 4-methacryloyloxyethyl trimellitate (4-MET) and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) were used. The disks were primed with one of each silane compound with or without the acidic functional monomer of the same molarity. The specimens were bonded with a tri-n-butylborane (TBB) initiated luting material. The shear bond strength was determined before and after 10,000 thermocycles. Bond strength was statistically evaluated with Kruskal-Wallis, Mann-Whitney U-, and Steel- Dwass tests. To test dye penetration, the specimens were immersed in 0.5 wt% fuchsin solution for 24 h after priming with each condition, bonding, and 10,000 thermocycles. The dye penetration area was determined by observing the backside of the bonded specimen with an optical microscope. The relationship between the shear bond strength and dye penetration ratio was analyzed with Spearman’s rank correlation test. Results: The highest post-thermocycling bond strengths in the 1 mol% and 2 mol% groups were 3-TMSPMA + 10- MDP and 3-MPPTS + 10-MDP. Spearman’s rank correlation coefficient between shear bond strength and dye penetration area was γ = -0.7519, indicating a strong negative correlation. Conclusion: The surface treatments of 3-TMSPMA and 3-MPPTS combined with 10-MDP yielded higher bond strength after 10,000 thermocycles than those combined with 4-MET, despite the similarity in molarity. The shear bond strength was negatively correlated with the dye penetration area.

Fabrication of titanium restoration by means of calcium aluminate-bonded magnesia investment material and one-chamber arc casting apparatus

Cast titanium restoration for molars has high biocompatibility and is covered by the Japanese national health insurance. Titanium casting requires specific investment material and casting apparatus. A cast restoration for the mandibular left second molar was fabricated using titanium in this study. A wax pattern fabricated on a definitive cast was invested in calcium aluminate-bonded magnesia investment material. Titanium was cast using an argon gas pressure one-chamber casting apparatus. No defects were observed on the surface and the hole was clearly reproduced. A smooth surface on the restoration was obtained by polishing at low speed. Reproductivity and polishing properties of the titanium restoration fabricated in this study were comparable to those of conventional dental metal restorations.

Adhesive bonding of noble metals with a thiohydantoin primer

OBJECTIVE

The purpose of this study was to assess the effects of an experimental primer containing acetone solution and a sulfur-containing functional monomer, 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP), on the bonds between noble metals and acrylic resin.

METHODS

The experimental primer used as the control for comparison consisted of 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithione (VBATDT) in acetone. These primers were prepared as equimolar functional monomers (0.1 mol%). A self-polymerizing acrylic resin initiated with tri-n-butylborane (TBB) was used as the luting agent. Four elemental metal disks (silver, copper, palladium, and gold) were used as adherend specimens. All the disks were wet-ground with silicon carbide paper (#1500). Bonding reactions were performed on 12 combinations of the four metals, and the disks were either primed with MDTHP or VBATDT or were unprimed (control). Shear bond strengths were determined pre- and post-thermocycling (5-55 °C, dwell time 60 s, 20,000 cycles). The results were statistically analyzed via a non-parametric test (α = 0.05).

RESULTS

The post-thermocycling shear bond strengths of the MDTHP primer were as follows (median, n = 11): 13.2 MPa on silver, 25.9 MPa on copper, 4.1 MPa on palladium, and 11.3 MPa on gold. The MDTHP primer showed higher post-thermocycling shear bond strength on all the four metals. Additionally, on silver and copper, the MDTHP bond strengths were higher than on the other metals.

SIGNIFICANCE

Within the limitation of current of experimental setting, the MDTHP compound may be applicable as a functional monomer for bonding noble metal alloys.

Combined effect of two-liquid silane-phosphate primer and single-liquid sodium sulfite primer on bonding between self-polymerizing resins and feldspathic ceramics

The purpose of this study is to investigate the combined effect of two-liquid silane-phosphate primer and single-liquid sodium sulfite primer on bonding between self-polymerizing resins and feldspathic ceramics, and to promote the polymerization behavior of self-polymerizing resins at the bonding interface. The silane-phosphate primer (Super-Bond PZ Primer; PZ) and the sodium sulfite primer (Teeth Primer; TP) were used as the surface treatment agents for bonding the feldspathic ceramics and the self-polymerizing resins (MMA-TBB resin and 4-META/MMA-TBB resin). Combined PZ and TP showed high shear bond strengths. The peak of the differential scanning calorimetry curve was shown to occur early through the addition of TP. These results indicated that additional TP promoted the conversion in the initial polymerization of resin, and the firmly bond was obtained at the interface. PZ+TP treatment can be regarded as an effective treatment for a temporary splint used in teeth restoration.

A report on the clinical use of bonding systems for coronal restorations produced from CAD/CAM resin blocks

Computer-aided design and manufacturing (CAD/CAM) resin-produced restorations were approved by a health insurance system in Japan from the year 2014. In this study, we investigated the use of CAD/CAM resin blocks in Japan since 2014, and the clinical use of adhesive systems for CAD/CAM resin-produced restorations in dentistry. Our findings indicated a rise in the clinical application of these products; however, some studies have reported instances of debonding and fracture of the restorations. CAD/CAM resin blocks were implemented in the health insurance system in Japan as an alternative for alloys due to the continuous rise in the prices of gold and palladium. Thus, in order to reduce the number of failures in CAD/CAM resin-produced restorations due to debonding and fracture, the integration of these restorations with the tooth structures is of utmost importance.

Synthesis and characterization of a methacrylate monomer with a thiohydantoin structure

The purpose of the current study was to synthesize a methacrylate monomer with a thiohydantoin structure. In a flask, (2-thiohydantoin-4-yl) propionic acid, 10-hyroxydecyl methacrylate, 4-dimethylaminopyridine, and tetrahydrofuran (THF) were placed in a nitrogen atmosphere. A THF solution of N,N'-dicyclohexylcarbodiimide was added and stirred at room temperature. Ethyl acetate and n-hexane were then added to the reaction mixture. The reacted slurry was purified by chromatography with silica gel and hexane-ethyl acetate gradient elution solvent. The structure of the compound was assigned with proton nuclear magnetic resonance spectrum analysis, infrared spectroscopy, and high-resolution mass spectral analysis. The colorless viscous liquid obtained in yield of 49% was characterized as 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP) or 10-((3-(5-oxo-2-thioxysoimidazolidin-4-yl)propanoyl)oxy)decyl methacrylate (2-THPDM). The MDTHP was soluble to acetone, isopropanol, and methyl methacrylate up to 2.6% or more. This compound could be potentially applicable as a functional monomer for bonding metals and alloys.

Radiopacity of computer-aided design/computer-aided manufacturing composite resin blocks

This study aimed to clarify the degree of difference in radiopacity between sixteen CAD/CAM composite resin blocks, one ceramic block, and teeth of the same thickness on radiographs. The radiographic density of CAD/CAM composite resin blocks was measured and the results were compared with the corresponding values for enamel and dentin. Additionally, the study analyzed the constituent elements of each type of CAD/CAM composite resin block and conducted an examination to identify those elements exerting an influence on radiopacity. Compared to the enamel, there were five blocks with significantly higher radiopacity, two blocks with the same level in radiopacity, and ten blocks with notably lower radiopacity. Compared to the dentin, there were ten blocks with significantly higher radiopacity, one block with the same level in radiopacity, and six blocks with notably lower radiopacity. All of the CAD/CAM composite resin blocks for molars contained barium and strontium. This result suggests that the addition of heavy metals, for example, barium, strontium, and zirconium, would be effective in providing CAD/CAM composite resin blocks with radiopacity.

Prediction of the difficulty of proximal vascular control using 3D-CTA for the surgical clipping of internal carotid artery-posterior communicating artery aneurysms

OBJECTIVE

During surgical clipping of internal carotid artery (ICA)-posterior communicating artery (PCoA) aneurysms, proximal vascular control (PVC) is difficult to achieve in some cases because of variations in the anatomy of this type of aneurysm and its parent arteries. The authors investigated morphometric features that may be predictive for the necessity of anterior clinoidectomy (ACL) or cervical ICA exposure for PVC.

METHODS

The authors retrospectively reviewed 65 patients with an ICA-PCoA aneurysm treated with clipping during the previous 3 years. The factors considered for assessing the difficulty of attaining PVC included the following: the maximum diameter of the aneurysm; the distance between the tip of the anterior clinoid process (ACP) and the proximal aneurysmal neck; the presence of calcification at the ophthalmic segment of the ICA; and the angles between the communicating segment of the ICA and the ophthalmic segment of the ICA and a line perpendicular to the cranial base, which reflect the tortuosity of the ICA. These parameters were measured based on preoperative CTA results.

RESULTS

In a total of 21 patients (32.3%), PVC was difficult to perform with the usual pterional approach. In 6 patients, temporary artery occlusions (TAOs) were difficult to achieve because of severe atherosclerotic wall changes in the ophthalmic segment of the ICA. For 15 patients, the ACPs overhanging the ophthalmic segment of the ICA obstructed the ability to secure a space for TAO. In the 21 patients with PVC difficulty, ACL alone, cervical ICA exposure alone, and both ACL and cervical ICA exposure were conducted in 6, 8, and 7 patients, respectively. Multivariate analysis with binary logistic regression revealed that the maximum diameter of the aneurysm (p = 0.041), the distance between the proximal neck of the aneurysm and the ACP tip (p = 0.002), and calcification of the ICA ophthalmic segment (p = 0.001) were significant predictive factors for difficulties with PVC. A receiver operating characteristic curve analysis revealed that a distance between the proximal aneurysmal neck and the ACP tip of ≤ 5.4 mm was the best cutoff value for predicting the difficulty of attaining PVC (area under the curve 0.800, sensitivity 80.0%, specificity 80.0%).

CONCLUSIONS

A short distance between the proximal aneurysmal neck and the ACP tip and the presence of calcification at the ophthalmic segment of the ICA on preoperative CTA are helpful for predicting the difficulty of achieving PVC.

Sphenoparietal sinus transposition technique: optimization of the surgical corridor with preservation of prominent bridging veins between the brain and the cranial base during aneurysm clipping via the pterional approach

OBJECTIVE

The sylvian bridging veins between the brain and the dura on the inner surface of the sphenoid wing can restrict brain retraction for widening of the lateral retrocarotid space during clipping surgery for internal carotid artery (ICA)-posterior communicating artery (PCoA) and basilar apex (BX) aneurysms. In such cases, the authors perform extradural anterior clinoidectomy with peeling of the temporal dura propria from the periosteal dura and inner cavernous membrane around the superior orbital fissure, with the incision of the dura mater stretching from the base of the temporal side to just before the distal dural ring of the ICA (termed by the authors as the sphenoparietal sinus transposition [SPST] technique). This technique displaces the bridging segment of the sylvian vein posteriorly and enables widening of the surgical space without venous injury. In this study, the authors observed the operative nuances and investigated the usefulness of this technique.

METHODS

The authors retrospectively reviewed the medical charts of 66 consecutive patients with ICA-PCoA and BX aneurysms between January 2016 and July 2018. This technique was performed in 8 patients (5 patients with PCoA aneurysms and 3 with BX aneurysms) in whom the bridging segments of the sylvian veins between the brain and the skull base restricted brain retraction for widening of the surgical space. The surface areas of the lateral retrocarotid space and the aneurysm were measured at the most visible working angle before and after the SPST technique was performed.

RESULTS

With the use of the SPST technique, an adequate surgical space for aneurysm clipping was obtained with preservation of the bridging veins in all patients. The mean surface areas of the lateral retrocarotid space (p = 0.002) and aneurysm (p = 0.001) were significantly increased from 18.3 ± 18.8 and 2.8 ± 2.5 cm2 before to 64.2 ± 21.1 and 20.9 ± 20.6 cm2, respectively, after the SPST technique was performed.

CONCLUSIONS

The SPST technique enables displacement of the bridging segments of the sylvian veins without venous injury and enables widening of the surgical space around the lateral retrocarotid area.

Direct measurement of 1-mN-class thrust and 100-s-class specific impulse for a CubeSat propulsion system

This paper presents the development of a thrust stand to enable direct measurement of thrust and specific impulse for a CubeSat propulsion system during firing. The thrust stand is an inverted pendulum and incorporates a mass balance for direct in situ mass measurement. The proposed calibration procedure allows precise performance characterization and achieves a resolution of 80 μN thrust and 0.01 g mass loss, by taking into account the drift of the thrust-stand zero caused by propellant consumption. The performance of a water micro-resistojet propulsion system for CubeSats was directly characterized as a proof of concept of the thrust stand. Continuous profiles of thrust, specific impulse, and mass consumption were acquired under various conditions in a single firing test. A thrust from 1 mN to 10 mN and a specific impulse from 45 s to 100 s with a maximum measurement uncertainty of ±15.3% were measured for the throat Reynolds number in the range 100-400.

Effect of etching with potassium hydrogen difluoride and ammonium hydrogen difluoride on bonding of a tri-n-butylborane initiated resin to zirconia

The purpose of the current study was to evaluate the effect of etching with potassium hydrogen difluoride (KHF₂) and ammonium hydrogen difluoride (NH₄HF₂) on the bond strength of a self-polymerizing methyl methacrylate resin (MMA-TBB) bonded to zirconia. Zirconia disks were prepared using the following surface treatment: no treatment, alumina blasting, and etching with KHF₂ or NH₄HF₂. The specimens were bonded with the MMA-TBB. The shear bond (Ø=5 mm) strength was measured. The surface free energies of the specimens were determined by measuring contact angles. The KHF₂ and NH₄HF₂ groups exhibited higher shear bond strength and surface free energy than did the alumina blasting and no treatment groups. Compared with alumina blasting, etching with KHF₂ and NH₄HF₂ exhibited superior bonding ability of mechanical retention to zirconia.

Surface properties and gloss of CAD/CAM composites after toothbrush abrasion testing

The purpose of this study was to evaluate the surface properties and gloss of CAD/CAM composites after toothbrush abrasion testing. Four CAD/CAM composites for molars (Cerasmart 300, Estelite P block, Katana Avencia P block, and KZR-CAD HR3 Gammatheta), one CAD/CAM composite for premolars (Shofu Block HC Hard), and one feldspathic ceramics (Vitablocs Mark II) were assessed. Knoop hardness number, gloss, and surface roughness (Ra, Rz, and Sa) were measured before and after toothbrush abrasion testing. Knoop hardness number values were in the order Vitablocs Mark II > Katana Avencia P block > Estelite P Block > Shofu Block HC Hard > Cerasmart 300 > KZR-CAD HR3 Gammatheta. After testing, the gloss of Estelite P block and KZR-CAD HR3 Gammatheta was greatly decreased and surface roughness was greatly increased. Periodic recall and re-polishing may thus be necessary when these products are used clinically.

Properties of indirect composites polymerized with laboratory light-emitting diode units

This study evaluated the light intensity of light-emitting diode (LED) units and the effects of five laboratory polymerization units on hardness and flexural strength. Two indirect composite materials (Cesead N and Solidex Hardura) were polymerized with five units (α-Light II, Hyper LII, LED Cure Master, Twinkle LED, and α-Light V). The light intensity of the devices was measured with a spectroradiometer. After light exposure, Knoop hardness number, flexural strength, and elastic modulus were determined. Evaluation of light intensity, using a wavelength range of 400 to 500 nm, revealed that the α-Light V and Hyper LII units had the highest light intensity. For the top surface of the two composites, the Knoop hardness number was significantly higher for the α-Light V and Hyper LII. For the two composite materials, flexural strength did not differ among the five polymerizing units. The present results indicate that the Cesead N and Solidex Hardura composites can be adequately polymerized with laboratory LED units.

Effect of multi-purpose primers on the bond durability between tri-n-butylborane initiated resin and gold alloy

PURPOSE

This study investigated the influence of an interaction between sulfur-containing monomers and other monomers in multipurpose primers on the bond durability of a tri-n-butylborane (TBB)-initiated acrylic resin to a gold alloy.

METHODS

The disk-shaped adherend materials were prepared from a gold alloy (Casting Gold M.C. Type IV). Two multipurpose-primers (Universal Primer, Monobond Plus), four metal primers containing an organic sulfur compound (M.L. Primer, Alloy Primer, Metaltite, and V-Primer), and three acidic primers (Estenia Opaque Primer, Acryl Bond, and Super-Bond Liquid) were used. The shear bond strengths were determined pre- and post-thermocycling to evaluate the bond durability. A statistical analysis of the results was performed using a non-parametric procedure, and the cohesive failure ratios of the debonded surfaces were compared.

RESULTS

Among the pre-thermocycling groups, M.L. Primer, Metaltite, Monobond Plus, Universal Primer, and Alloy Primer showed the greatest bond strengths. Among the post-thermocycling groups, M.L. Primer, Metaltite, Monobond Plus, and Universal Primer showed the greatest bond strengths, whereas Acryl Bond, Super-Bond Liquid, Estenia Opaque Primer, and the unprimed control showed the lowest. Similarly, the primers that did not contain either a sulfur compound showed an obvious reduction in the cohesive failure ratio.

CONCLUSIONS

Multi-purpose primers containing a sulfur-containing monomer increased the bond strength of a TBB-initiated acrylic resin to a gold alloy. The proportion of the area of cohesive failure to the bonded area showed an interrelationship with the shear bond strength testing results.

Castability and mechanical properties of Ti-15Mo-5Zr-3Al alloy in dental casting

The castability, mechanical properties, and fracture characteristics of Ti-15Mo-5Zr-3Al alloy were compared with those of Ti-6Al-7Nb alloy and pure titanium (CP Ti) for application of this β-type titanium alloy in cast dental prostheses. Cast specimens were prepared with a centrifugal casting machine. A tensile test was performed according to ISO standard 22674. The castability index for Ti-15Mo-5Zr-3Al was lower than those for Ti-6Al-7Nb and CP Ti. The tensile strength of Ti-15Mo-5Zr-3Al was 852 MPa, which was lower than that of Ti-6Al-7Nb and higher than that of CP Ti. The proof strength of Ti-15Mo-5Zr-3Al was 799 MPa, which was comparable to that of Ti-6Al-7Nb and higher than that of CP Ti. The elastic modulus of Ti-15Mo-5Zr-3Al was 81.0 GPa, which was lower than the values for Ti-6Al-7Nb and CP Ti. Elongation of Ti-15Mo-5Zr-3Al was 5.1%, which was comparable to that of Ti-6Al-7Nb and less than that of CP Ti. The shape of the fractured segment was narrower for Ti-15Mo-5Zr-3Al than for Ti-6Al-7Nb and CP Ti. The deformation characteristics of Ti-15Mo-5Zr-3Al may result in decreased stress relative to increased strain during plastic deformation in the stress-strain diagram. In conclusion, Ti-15Mo-5Zr-3Al alloy has a low elastic modulus and exhibits limited ductile plastic deformation in cast dental prostheses.

Effect of silane compounds on bonding to fused quartz of tri-n-butylborane initiated resin

This study aimed to investigate how different compositions of experimental silane-based primers in a methyl methacrylate solution containing 3-(trimethoxysilyl)propyl methacrylate (3-TMSPMA) or 3-(4-methacryloyloxyphenyl)propyl trimethoxysilane (3-MPPTS) might act as silicon dioxide bonding agents. With or without post-silanization heat treatment, primer-treated quartz discs were bonded using the MMA-TBB resin and their bond strengths were evaluated. The disks were primed with one of the following materials: 1 mol% 3-TMSPMA, 2 mol% 3-TMSPMA, 1 mol% 3-MPPTS, and 2 mol% 3-MPPTS. Shear bond strength was determined both before and after thermocycling. Statistical analyses were performed with non-parametric procedure (Kruskal-Wallis, Mann-Whitney U, and Steel-Dwass tests). Both primers were effective with heat treatment to enhance bonding between quartz and the MMA-TBB, and the bonding durability of the 1 and 2 mol% 3-MPPTS (16.8 and 24.9 MPa) with heat groups was significantly higher than in the 1 and 2 mol% 3-TMSPMA (5.4 and 9.8 MPa) with heat groups.

Trace of organic sulfur compounds detected from debonded interface between transparent acrylic resin and gold alloy

The purpose of the current study was to evaluate the bonding performance of two single-liquid primers, which contained 6-(4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione (VTD) or 6-methacryloyloxyhexyl 2-thiouracil 5-carboxylate (MTU-6), used for bonding between metals and an acrylic resin. A gold alloy and high-purity titanium were used as adherend materials, and a transparent acrylic resin initiated with tri-n-butylborane derivative was selected as the luting material. Both adherends were treated with one of the primers and bonded with the luting material, after which shear bond strength was determined. Fourier transform infrared spectroscopy was used to analyze debonded resin specimens. Shear bond strength to gold alloy was significantly greater than that to titanium for both the VTD and MTU-6 primers. A trace of thiol structure, probably derived from VTD and MTU-6, was detected on resin surfaces debonded from gold alloy. These results indicate that the two organic sulfur compounds, which are stable in an atmospheric environment, are tautomerized into a thiol structure, thus allowing adsorption onto noble metals. In addition, the adsorbed thiol compounds contribute to chemical bonding between the acrylic resin and noble metal alloy, as polymerizable adhesive functional monomers.

Concept and clinical application of the resin-coating technique for indirect restorations

The resin-coating technique is one of the successful bonding techniques used for the indirect restorations. The dentin surfaces exposed after cavity preparation are coated with a thin film of a coating material or a dentin bonding system combined with a flowable composite resin. Resin coating can minimize pulp irritation and improve the bond strength between a resin cement and tooth structures. The technique can also be applied to endodontically treated teeth, resulting in prevention of coronal leakage of the restorations. Application of a resin coating to root surface provides the additional benefit of preventing root caries in elderly patients. Therefore, the coating materials have the potential to reinforce sound tooth ("Super Tooth" formation), leading to preservation of maximum tooth structures.

Surface roughness and gloss of current CAD/CAM resin composites before and after toothbrush abrasion

The purpose of this study was to evaluate the gloss and surface roughness behaviors of newly developed CAD/CAM composite blocks with different filler contents and characteristics. The gloss and surface roughness were quantified before and after a toothbrush dentifrice abrasion test; the results were compared to the gloss and surface roughness of a ceramic CAD/CAM block. Knoop hardness was determined before abrasion test. The results were analyzed by ANOVA, Tukey HSD, and Dunnett t test (p<0.05). The rank order of Knoop hardness was as follows: Vita Mark II>Vita Enamic>Gradia block>Shofu Block HC, Lava Ultimate≥Katana Avencia block≥Cerasmart. After toothbrush abrasion, a significant difference in the gloss unit was detected between the Shofu Block HC material and the ceramic block. The Ra and Rz of the Cerasmart and Shofu Block HC materials were significantly larger than those of the ceramic block after toothbrush abrasion.

Effect of mechanochemical surface preparation on bonding to zirconia of a tri-n-butylborane initiated resin

This study aimed to evaluate the effect of surface preparation on bond strength of a tri-n-butylborane initiated resin (MMA-TBB) bonded to zirconia. Zirconia disks were either airborne-particle abraded with alumina or silica-coated. The disks were thereafter primed with one of the following materials: phosphate-silane (Clearfil Ceramic Primer), phosphate (Alloy Primer), or silane (ESPE Sil). The specimens were bonded with the MMA-TBB. Shear bond strength was determined both before and after thermocycling. Bond strength of unprimed zirconia (control) was not affected by the surface roughness of each adherend. Priming with phosphate was effective for bonding alumina-blasted zirconia. Priming with silane was effective for bonding silica-coated zirconia. Priming effect of the phosphate-silane was superior to that of silane alone for bonding silica-coated zirconia. Bond strength to zirconia of the MMATBB is significantly influenced by a combination of the specific functional monomer and the surface modification performed rather than the material surface roughness.

Inhibition of Trigeminal Respiratory Activity by Suckling

The trigeminal motor system is involved in many rhythmic oral-motor behaviors, such as suckling, mastication, swallowing, and breathing. Despite the obvious importance of functional coordination among these rhythmic activities, the system is not well-understood. In the present study, we examined the hypothesis that an interaction between suckling and breathing exists in the brainstem, by studying the respiratory activity in trigeminal motoneurons (TMNs) during fictive suckling using a neonatal rat in vitro brainstem preparation. The results showed that fictive suckling, which was neurochemically induced by bath application of N-methyl-D,L-aspartate and bicuculline-methiodide, or by local micro-injection of the same drugs to the trigeminal motor nucleus, inhibited the inspiratory activities in both respiration TMNs and respiratory rhythm-generating neurons. Under patch-clamp recording, fictive suckling caused membrane potential hyperpolarization of respiration TMNs. We conclude that the brainstem preparation contains an inhibitory circuit for respiratory activity in the trigeminal motor system via the rhythm-generating network for suckling. Abbreviations: BIC, bicuculline methiodide; GABA, gamma aminobutyric acid; NMA, N-methyl-D,L-aspartate; NMDA, N-methyl-D-aspartate; and TMN, trigeminal motoneuron.

Effect of thione primers on adhesive bonding between an indirect composite material and Ag-Pd-Cu-Au alloy

The current study evaluated the effect of primers on the shear bond strength of an indirect composite material joined to a silverpalladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell). Disk specimens were cast from the alloy and were air-abraded with alumina. Eight metal primers were applied to the alloy surface. A light-polymerized indirect composite material (Solidex) was bonded to the alloy. Shear bond strength was determined both before and after the application of thermocycling. Two groups primed with Metaltite (thione) and M. L. Primer (sulfide) showed the greatest post-thermocycling bond strength (8.8 and 6.5 MPa). The results of the X-ray photoelectron spectroscopic (XPS) analysis suggested that the thione monomer (MTU-6) in the Metaltite primer was strongly adsorbed onto the Ag-Pd-Cu-Au alloy surface even after repeated cleaning with acetone. The application of either the thione (MTU-6) or sulfide primer is effective for enhancing the bonding between a composite material and Ag-Pd-Cu-Au alloy.

Expressions of isopeptide bonds and corneodesmosin in middle ear cholesteatoma

OBJECTIVE

Isopeptide bonds form cross-links between constituent proteins in the horny layer of the epidermis. Corneodesmosin (CDSN) is a major component of corneodesmosomes, which bind corneocytes together. Both play important roles in maintaining epidermal barrier functions. In the present study, we investigated the expressions of isopeptide bonds, CDSN, and related enzymes in middle ear cholesteatoma in comparison with the skin.

DESIGN

Prospective case series of patients with middle ear cholesteatoma.

SETTING

Tertiary medical institute.

PARTICIPANTS

Cholesteatoma and normal postauricular skin were collected from patients with acquired middle ear cholesteatoma during tympanomastoidectomy.

MAIN OUTCOME MEASURES

Expression of e-(g-glutamyl)lysine isopeptide bonds was examined by immunohistochemistry; Expressions of transglutaminase (TGase)1, TGase2, TGase3, and TGase5 by immunohistochemistry and quantitative RT-PCR (qRT-PCR); expression of CDSN by immunohistochemistry, qRT-PCR, and Western blot; and expressions of tissue kallikrein-related peptidase (KLK)5, KLK7, KLK14, and serine peptidase inhibitor Kazal type 5 (SPINK5) by qRT-PCR.

RESULTS

TGase2 was higher (P=0.0046) and TGase5 was lower (P=0.0008) in cholesteatoma than in the postauricular skin. Immunoreactivity for isopeptide bonds was localized in the granular and horny layers, and was not different between the two tissues. Immunoreactivity for CDSN was localized in the granular layer, and was lower in cholesteatoma than in the skin (P=0.0090). Western blot and qRT-PCR confirmed that the expression of CDSN was lower in cholesteatoma than in the skin. Expressions of KLK5, KLK7, KLK14, or SPINK5 were not different between the two tissues.

CONCLUSIONS

These results indicate that the production of CDSN is likely to be suppressed in cholesteatoma, which would account, at least in part, for the mechanical fragility and increased permeability of the cholesteatoma epithelium.

Studies on the validity of urinary enzyme assay in the diagnosis of drug-induced renal lesions in rats

The validity of urinary enzyme assays in the diagnosis of renal lesions was studied in rats for evaluation in comparison with other tests such as urinalysis and serum biochemical assay. Tubular damages of slight or severe degree were induced by daily intramuscular administration of 500 mg/kg or 1,000 mg/kg of kanamycin (KM) for 7 and 6 days respectively. Glomerular lesions were induced subcutaneous injection of 30 mg/kg of puromycin (PM) for 6 days. The enzymes, assayed daily before and after the onset of administration, were lactic dehydrogenase (LDH), aspartate aminotransferase (GOT), alkaline phosphatase (AI-P), acid phosphatase (Ac-P), leucin aminopeptidase (LAP) and γ-glutamyl transpeptidase (γ-GT). The distribution of these enzymic activities in the kidneys was histochemically examined. Assays of LDH and GOT on the kidney tissue homogenate were also conducted. Histological alterations of the kidneys were examined in the rats sacrificed after termination of administration.

Significant elevation of the LDH and GOT urine levels were observed within 24 hours in rats treated with 500 mg/kg of KM with the high enzyme levels being maintained throughout the administration period, while the other enzymes remained within pretreatment levels or were only slightly elevated. Serum urea nitrogen (BUN) and creatinine levels remained unchanged with no abnormality being found in the urinalysis of this group. In the group treated with 1,000 mg/ kg of KM, concomitant rising of all urine enzyme levels was observed, with elevation of the LDH and GOT levels being extreme while the BUN and serum creatinine levels rose only at the termination of the administration period. The BUN level rose earlier than did most of the urinary enzymes in puromycin-treated rats.

Depletion of LDH activity was histochemically demonstrated in the kidneys where no histological alteration was observable, while the activities of AI-P, γ-GT, and LAP showed no distinct changes until the tabular destruction became severe. Upon termination of both KM and PM administration, the depletion of LDH and GOT activities was noted in a kidney homogenate assay for the enzymes.

These results clearly showed that among the enzymes studied, the LDH and GOT urine levels are the most sensitive indicators for detecting proximal tubular lesions induced by KM. It was further demonstrated that the urinary enzyme assay in combination with serum BUN measurement is an effective examination for distinguishing tubular from glomerular lesions.

Increased permeability of the epithelium of middle ear cholesteatoma

OBJECTIVE

We investigated the electrical impedance of and the expressions of tight junction molecules in the cholesteatoma epithelium to provide supporting evidence for the acid lysis theory of bone resorption in middle ear cholesteatoma.

METHODS

Study subjects were patients with primary acquired middle ear cholesteatoma and those with non-cholesteatomatous chronic otitis media who underwent tympanomastoidectomy. The electrical impedance of the cholesteatoma epithelium was measured during tympanomastoidectomy by loading alternating currents of 320 Hz and 30.7 kHz. The expressions of tricellulin (MARVELD2), claudin-1 (CLDN1) and claudin-3 (CLDN3) were examined by fluorescence immunohistochemistry and quantitative reverse transcription-polymerase chain reaction.

RESULTS

The electrical impedance of the cholesteatoma epithelium was significantly lower than that of the post-auricular skin and external auditory canal skin at both 320 Hz and 30.7 kHz. Immunoreactivity for MARVELD2, CLDN1 and CLDN3 was localised mainly in the granular layer, and to lesser degree, in the horny and spinous layers in both the cholesteatoma tissue and post-auricular skin. Fluorescence intensity was moderate for MARVELD2, weak for CLDN1 and strong for CLDN3. The expressions of MARVELD2, CLDN1 and CLDN3 mRNA were significantly lower in the cholesteatoma tissue than in the post-auricular skin.

CONCLUSIONS

These results indicate the increased permeability of the cholesteatoma epithelium and suggest that this change is, at least partially, dependent on the decrease in the expressions of the tight junction molecules. This evidence supports the acid lysis hypothesis of bone resorption in cholesteatoma.

Unique Distribution of Benzodiazepine Receptors in the Brain during the First Two Years of Life

BACKGROUND

123I-iomazenil (IMZ) single-photon emission computed tomography (SPECT) is a tool for evaluating epileptic foci and brain damage. To apply the method to children, information regarding the age-specific expression of benzodiazepine receptors (BDZ-Rs) is required. Unfortunately, there is no information currently available for children <2 years of age.

METHODS

We used IMZ SPECT once in infants aged 3-8 months and again at 2 years of age in order to describe the maturational changes in BDZ-R distribution.

RESULTS

No neurological deficits were found in any of the infants at the first examination. The BDZ-Rs were more dominantly distributed in the occipital lobe than in the frontal lobe before the age of 2 years. The frontal-occipital gradients of the distribution were obvious in children <8 months of age. Magnetic resonance imaging showed a spreading of myelination toward the frontal lobes simultaneously with BDZ-R expression.

CONCLUSION

Information regarding the alteration in the BDZ-R distribution pattern is useful when assessing infantile epilepsy and brain injury. The age-related pattern of BDZ-R distribution could correspond with myelination, cerebral blood flow, metabolism and behavioral development.

Strategies and Pitfalls of Motor-Evoked Potential Monitoring during Supratentorial Aneurysm Surgery

BACKGROUND

The aims of this study were to reveal the strategies and pitfalls of motor-evoked potential (MEP) monitoring methods during supratentorial aneurysm surgery, and to discuss the drawbacks and advantages of each method by reviewing our experiences.

METHODS

Intraoperative MEP monitoring was performed in 250 patients. Results from 4 monitoring techniques using combinations of 2 stimulation sites and 2 recording sites were analyzed retrospectively.

RESULTS

MEP was recorded successfully in 243 patients (97.2%). Direct cortical stimulation (DCS)-spinal recorded MEP (sMEP) was used in 134 patients, DCS-muscle recorded MEP (mMEP) in 97, transcranial electrical stimulation (TES)-mMEP in 11 and TES-sMEP in 1. TES-mMEP during closure of the skull was used in 21 patients. DCS-mMEP was able to detect waveforms from upper and/or lower limb muscles. Alternatively, DCS-sMEP (direct [D]-wave) could accurately estimate amplitude changes. A novel "early warning sign" indicating ischemia was found in 21 patients, which started with a transiently increased amplitude of D-wave and then decreased after proximal interruption of major arteries. False-negative findings in MEP monitoring in 2 patients were caused by a blood insufficiency in the lenticulostriate artery and by a TES-sMEP recording, respectively.

CONCLUSIONS

The results of this study suggest that to perform accurate MEP monitoring, DCS-mMEP or DCS-sMEP recording should be used as the situation demands, with combined use of TES-mMEP recording during closure of the skull. DCS-sMEP is recommended for accurate analysis of waveforms. We also propose a novel "early warning sign" of blood insufficiency in the D-wave.