Entire Dental Arch Mesial Movement after Extraction of Maxillary Right Central Incisor due to Root Fracture Treated with Temporary Anchorage Devices

This case report describes a 19-year-old woman with skeletal Class I crowding and an unsalvageable maxillary right central incisor. She visited our clinic with the chief complaint of mobility of the maxillary right central incisor due to a traffic accident. After extraction of the maxillary right central incisor, the space was closed orthodontically. All the maxillary right teeth were moved mesially with an elastic chain attached to a palatal lever arm which was connected to palatal temporary anchorage devices (TADs). After orthodontic treatment had been completed, the maxillary right lateral incisor and peg-shaped left lateral incisor were restored with a porcelain laminate veneer. The maxillary right canine was morphologically reshaped and built up with composite resin. Consequently, esthetically ideal occlusion and functional lateral guidance with uncontacted molars were obtained. These results show that mesial movement of the entire dental arch with TADs is a useful orthodontic treatment option in patients in whom the maxillary central incisor has been extracted.

Effect of laser engraving on shear bond strength of polyetheretherketone to indirect composite and denture-base resins

Background/purpose

Polyetheretherketone (PEEK) is a highly sought-after thermoplastic due to its exceptional mechanical properties and biocompatibility. However, bonding PEEK to indirect composite resin (ICR) or denture-based resin (DBR) can be challenging. Laser engraving technology has shown potential to improve bonding for other materials; thus, this study aims to evaluate its effectiveness for PEEK.

Materials and methods

The experiment involved preparing ingot-shaped PEEK samples, which were then categorized into four groups based on the treatment method employed: without treatment, air abrasion, sulfuric acid etching, and laser engraving (LS). Subsequently, the samples were bonded to ICR or DBR, and their shear bond strength (SBS) was tested with or without thermocycling using a universal testing machine. Furthermore, the failure mode was observed, with statistical analyses conducted to compare the results.

Results

The grid-like microslit structure of LS group displayed the highest SBS for bonding PEEK to ICR or DBR (P < 0.05). During the bonding of PEEK to ICR, resin residue and penetration into the microslits were frequently observed in the LS group, indicating cohesive failure. However, when PEEK was bonded to DBR, mixture failure was frequently observed without thermocycling. After thermocycling, only the LS group showed cohesive failure, while the majority of specimens exhibited mixture failure.

Conclusion

Laser engraving significantly improves the SBS between PEEK and both ICR and DBR. Furthermore, it was observed that resin had penetrated the microslits, indicating that laser engraving has great potential as a surface treatment method.

The Physiological Function of Deglutition and Swallowing in Patients With Maxillary Protrusion After Mandibular Advancement

The objective of this study was to determine the tongue-palatal contact changes in patients with skeletal maxillary protrusion after sagittal split ramus osteotomy (SSRO) during swallowing. In this study, 15 patients with maxillary protrusion and 10 normal subjects participated. Before and 3 months after surgery, tongue-palatal contact patterns during swallowing of patients with maxillary protrusion as well as controls were evaluated by electropalatography. The electrode contact number in the alveolar, palatal, and velar parts was examined. The swallowing duration of each phase was also evaluated. In the lateral area of the velar part, incomplete electrode contact was shown at 0.3 seconds in patients with maxillary protrusion. The electrode contact number in the velar part at 0.3 seconds before tongue-palatal complete contact was significantly less in the preoperative patients compared with the controls ( P < 0.05). A small increase in the electrode contact number of the velar part was shown in the postoperative patients at 0.3 and 0.2 seconds before tongue-palatal complete contact ( P < 0.05). The pharyngeal phase duration was significantly larger in the patients with maxillary protrusion before SSRO compared with the controls ( P < 0.05). After SSRO, the pharyngeal phase duration was significantly shortened. It was shown that the tongue-palatal contact pattern during swallowing in patients with maxillary protrusion improved after orthognathic surgery, and the pharyngeal phase duration was also shortened. It is suggested that the changes in the mesiodistal mandibular position by orthognathic surgery can improve tongue posture and movement during swallowing.

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.

Influence of dental abrasives on surface roughness, gloss, and color of titanium

PURPOSE

The influence of three dental abrasives on the surface roughness, glossiness, and color of titanium (Ti) after mechanical polishing was investigated.

METHODS

The specimens were divided into groups, referred to as SM, SR, and TP, to distinguish the different polishing processes. SM: rubber polishing using a rubber point containing SiC abrasive particles at 20,000 rpm, followed by gloss polishing; SR: rubber polishing using a rubber point containing Al₂O₃ abrasive particles at 20,000 rpm, followed by gloss polishing; TP: rubber polishing using a rubber point containing TiO₂ abrasive particles at 6,000 rpm, followed by gloss polishing. Gloss polishing was carried out at 10,000 rpm using a leather buffing wheel. Measurements to evaluate the surface conditions of Ti were performed after each polishing process.

RESULTS

There were no significant differences in the Ra and glossiness values between the SM and TP groups; these specimens were not as smooth and glossy as the SR group. The SM group showed relatively high values of lightness and chroma after gloss polishing.

CONCLUSION

Rubber polishing with abrasives containing SiC or TiO₂ particles before gloss polishing did not achieve appropriate surface conditions on Ti.

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.

Functional regulation of osteoblastic MC3T3E-1 cells by hyperbaric oxygen treatment

OBJECTIVES

The purpose of the present study was to examine the influence of hyperbaric oxygen (HBO) on the function of osteoblastic MC3T3-E1 cells.

DESIGN

Murine MC3T3-E1 cells were exposed to HBO treatment (at 2.5 absolute atmospheric pressure with 100% oxygen, 90 min per day) for 28 days. Alkaline phosphatase (ALP) staining, activity, and calcium (Ca) content were measured. Gene expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), hypoxia-inducible factor-1α (HIF-1α), type 1 collagen (COL1), and osteocalcin (OCN) was assessed using real-time quantitative polymerase chain reaction after a single HBO exposure for 1.5, 6, and 12 h. Furthermore, adenosine triphosphate (ATP) levels were measured using a luminescent cell viability assay.

RESULTS

ALP activity and Ca content were higher in the HBO group compared to those in the control group. Gene expression of bFGF, COL1, and OCN was upregulated in the HBO group; however, that of VEGF and HIF-1α significantly decreased in the HBO group in comparison with that in the control group. ATP levels were significantly higher in the HBO group compared to those in the control group.

CONCLUSIONS

These findings suggest that HBO accelerates bone formation by increasing the ATP levels of osteoblasts, and bFGF can act as a substitute for VEGF in vascularization by HBO application.

Effects of dimensions of laser-milled grid-like microslits on shear bond strength between porcelain or indirect composite resin and zirconia

PURPOSE

Zirconia cores and frameworks are widely used in restorative dentistry. Although these structures are veneered with porcelain for esthetic reasons, the use of indirect composite resins (ICRs) is expected to increase in the future. The purpose of this study was to investigate the effects of microslits of different dimensions formed by Nd:YVO 4 laser machining on the bond strength between two types of zirconia (3 mol% yttria-partially stabilized zirconia (Y-TZP) and ceria-partially stabilized zirconia/alumina nanocomposite (Ce-TZP/A)) and porcelain or an ICR.

METHODS

The zirconia disks were assigned as follows: 1) blasted with alumina particles (AB) and 2-4) surface machined with gridded microslits with a width, pitch, and depth of 50, 75, or 100 µm (MS50, MS75, and MS100, respectively). After the bonding of the veneering materials to the disks, half of the specimens veneered with the ICR were subjected to thermocycling (4-60°C, 20000 cycles). All the specimens were subsequently shear tested (n = 10/group).

RESULTS

There was no significant difference between the groups of the disks bonded to porcelain. On the other hand, for the disks bonded to the ICR, the bond strengths of the MS groups after thermocycling were statistically higher than that of the AB group. However, there was no significant difference in the bond strengths of the disks with different microslits.

CONCLUSIONS

Within the study limitations, it can be concluded that, for porcelain, the design of the mechanical retentive structure must be modified. However, for the investigated ICR, a simple gridded pattern can improve the bond strength with zirconia.

Generalized periodontitis treated with periodontal, orthodontic, and prosthodontic therapy: A case report

BACKGROUND

Generalized periodontitis is a severe periodontal disease characterized by rapid periodontal destruction in healthy persons. This case report describes the treatment of a severe crowding, large overjet, and occlusal collapse due to the loss of anterior guidance with generalized periodontitis.

CASE SUMMARY

A 35-year-old female patient with a chief complaint of crowding and maxillary protrusion was diagnosed with generalized periodontitis by clinical and radiographic examinations. To improve crowding and overjet, orthodontic treatment was performed after basic periodontal therapy. Severely damaged upper right lateral incisor and left canine were extracted, and lower right first premolar and left second premolar were also removed to treat severe crowding. After orthodontic treatment, periodontal flap surgery for upper left molars and guided tissue regeneration for the lower left second molar was performed. Then, a dental implant was inserted in the upper left canine legion. The esthetics of the maxillary anterior tooth was improved by prosthetic restorations. The treatment result showed a well-improved occlusion with proper anterior guidance and healthy periodontal tissue after a retention period of 10 years.

CONCLUSION

Periodontal, orthodontic, and prosthodontic treatments are extremely useful to improve function and stable periodontal tissue for generalized periodontitis.

Color accuracy of different types of monolithic multilayer precolored zirconia ceramics

STATEMENT OF PROBLEM

The use of monolithic multilayer precolored zirconia facilitates the production of esthetic restorations in a convenient and straightforward manner. However, the accuracy of the final color is not clear.

PURPOSE

The purpose of this in vitro study was to determine the color accuracy of different types of monolithic multilayer precolored zirconia ceramics of varying thicknesses.

MATERIAL AND METHODS

Eighty cubical A2-shade monolithic multilayer precolored zirconia ceramic specimens (15×15 mm) of 2 different thicknesses (1.0 mm and 1.5 mm) and 4 zirconia brands (UPCERA EXPLORE [UPEX], KATANA Zirconia STML [STML], Enamel ZR Multi-5 [EZM5], and Aidite 3D Pro Zir [A3DM]) were fabricated and divided into 8 groups (n=10). The Commission Internationale de l'Eclairage (CIELab) values were measured against 3 different backing substrates (gray, transparent, and A2) by using a spectrophotometer. The color difference (ΔE) between the backing substrates of each group and the Vita A2 Shade Guide, translucency parameter (TP), and chroma (C) values were calculated to evaluate the accuracy of the final color. Statistical analysis was performed by using ANOVA and the post hoc Tukey HSD tests (α=.05).

RESULTS

The ΔE values for UPEX and STML exceeded the clinically acceptable thresholds for gray and transparent backing substrates (ΔE>3.7) and were higher than those for the A2 backing substrate. A3DM showed less ΔE from the shade guide for all the backing substrates (P<.05), and the corresponding ΔE values were within the clinically acceptable threshold (ΔE<3.7). The TP value was inversely proportional, and the C value was proportional to thickness. For the zirconia ceramics with identical thicknesses, UPEX and STML exhibited the highest TP values, and A3DM showed the lowest C value (P<.05).

CONCLUSIONS

At a specific thickness, color accuracy was mainly affected by the type of monolithic multilayer precolored zirconia ceramic, and the high transparency of ceramics will cause color differences.

Finite-element analysis and optimization of the mechanical properties of polyetheretherketone (PEEK) clasps for removable partial dentures

PURPOSE

Polyetheretherketone (PEEK), a high-strength, aesthetic, and non-allergic thermoplastic polymer, recently became a candidate for replacing metallic components in dental prosthesis. However, as PEEK is flexible, the need for retention presents a key challenge in terms of its clinical application. In this study, clasps prepared using PEEK were optimized and evaluated to provide the mechanical properties required by dentures.

METHODS

Seventy-two three-dimensional rod-shape models, based on four thickness/width ratios, three base widths, and six taper ratios were created. These models were analyzed using finite-element methods to determine which modified clasp arm shape provided the most appropriate mechanical properties. Three shape-optimized PEEK specimens and one standard-shape Co-Cr alloy specimen were then fabricated. Constant-displacement fatigue testing was performed to calculate load values and deformations after ten years of clinical use.

RESULTS

Shape optimization indicated a maximum stress concentration that was consistently located at the base of the specimen, a correlation between mean load values and thickness that was greater than that with the width, and a correlation between taper ratio and mean load values. Fatigue testing showed that although PEEK exhibited significantly lower average load values than the Co-Cr alloy, these were sufficient for clinical use. All specimens exhibited significant deformation during the first period of cycling; however, there was no significant difference in the deformation between the two materials after fatigue testing.

CONCLUSIONS

PEEK exerts fewer stresses on abutments compared to standard-alloy clasps, provides adequate retention, and satisfy aesthetic demands, indicating that PEEK presents a promising alternative to conventional metal clasps.

Fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal clasps for removable partial dentures

With the rapid development of computer-aided design/computer-aided manufacturing (CAD/CAM) systems, the application of zirconia in removable partial dentures is expected to expand. Clasps composed of zirconia should improve esthetics without inducing the risk of metal allergy. The aim of this study was to examine the fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) clasps for removable partial dentures. Yttria-stabilized tetragonal zirconia polycrystal and cobalt-chromium (Co-Cr) alloy were prepared using CAD/CAM systems. Specimens were either of the semicircular type or of the flat type, with cross-sectional areas of taper ratios of 0.50, 0.75, and 1.00. All specimens were tested using the cantilever test and the constant displacement fatigue test, and data were analyzed using ANOVA. During the cantilever test, the maximum displacement prior to fracture was greater than the required undercut, and the semicircular-type specimen exhibited a higher fracture load than the flat type. None of the specimens displayed permanent deformation and showed almost the same degree of deformation after fatigue testing. A lower taper ratio was associated with lower average load values and greater displacement. Within the limitations of this study, it was possible to conclude that Y-TZP provides the required undercut and adequate retentive force for removable partial denture clasps. Additionally, Y-TZP and Co-Cr alloy had almost the same degree of deformation even after the simulated lifespan of removable partial dentures.

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.

Influence of air-abrasion and subsequent heat treatment on bonding between zirconia framework material and indirect composites

The purpose of this study was to evaluate the influence of air-abrasion and subsequent heat treatment on the shear bond strength of the bond between indirect composites and a zirconia material. Four surface preparations were employed; ground flat, then heated to regenerate the crystal phase (C); air-abraded with alumina for 10 s (S10), for 20 s (S20), and air-abraded for 10 s and heated (H). Disks were primed with Alloy Primer and bonded either with Estenia or with Gradia composite. XRD analysis suggested that the monoclinic zirconia content was increased by air-abrasion, and decreased by heating. The surface roughness of S10, S20 and H disks was similar. Nevertheless, H groups showed lower bond strengths than the S10 and S20 groups both before and after thermal cycling. Although alumina air-abrasion considerably enhanced bonding between zirconia and indirect composites, subsequent heat treatment had a negative effect on the durability of bond strength.

[Functional model of the middle ear ossicles]

In students' dissection practice, it is very difficult to teach students the structures and functions of the middle ear ossicles. The middle ear ossicles are too small to explain their structures and functions. Models are useful in explaining these points, but there have been no models that accurately explain the movements of the middle ear ossicles and the functions of the muscles in the middle ear. This time, we have made a model of middle ear ossicles. Our ear ossicles are made of paper-mache with metal in it. The incudomalleolar and incudostapedial articulations are made of rubber. The tensor tympani and the stapedius muscles are made of wire and the two wires can be fixed by cord stoppers. Our model explains clearly the following mechanisms of the middle ear ossicles. 1. The mechanism of sound conduction system. When the sound vibrates the tympanic membrane, malleus and incus rotate together. The long process of the incus pushes the head of the stapes. The sound is amplified by leverage. 2. Attenuation of sound by contractions of tensor tympani and stapedius muscles. When a loud sound is transmitted through the ossicular system, the tensor tympani muscle pulls the malleus inward while the stapedius muscle pulls the stapes outward. These two forces oppose each other and increase rigidity of the ossicular system, thus reducing the ossicular conduction. 3. The mechanism of how paralysis of stapedius muscle, caused by an injury to the facial nerve, results in hyperacusis. 4. This model also suggests a possible reason why the pars lucida of the tympanic membrane exists.

[Model for the functional instruction of swallowing]

It is difficult to teach students about the mechanism of swallowing. There are three phases of swallowing; oral phase, pharyngeal phase and esophageal phase. The bolus of food is propelled to back of mouth by the tongue and the swallowing reflex happens. After nasopharynx and mouth closure, the glottal closure occurs, then hyoid and larynx are lifted by the contractions of suprahyoid and thyrohyoid muscles. As for the epiglottis, it is compressed by the tongue and inclines downward. As the larynx is lifted upward and anteriorly, slight vacuum is caused in the lower pharynx and upper esophagus at the same time, and pharyngeal constrictor compress bolus, therefore, the bolus passes the piriform fossa, and is inhaled into the esophagus. This time, we made a model in order to explain this complicated mechanism. The mandible is made of paper clay by using a metallic plate in it. The tongue, the soft palate, and the epiglottis are made by using the EVA (Ethylene Vinyl Acetate) sheet. Styloglossus, suprahyoid, thyrohyoid muscles are made with the wire. Moreover, a movable wooden chip represents the contraction of the pharyngeal constrictor muscles. The spring is put in the trachea in order to lift the larynx. The upper part of esophageal constrictor is made with spring plates.

International telephone code used for citizenship identification in a denture

This case report describes a simple method for identifying the citizenship of a denture wearer by marking the telephone country code number inside the denture base. A wax pattern for the denture framework was prepared on the refractory cast. A piece of embossing tape, containing the country code (81, Japan), Japanese prefectural code, and abbreviation of the dental clinic where the denture was fabricated, was placed on the metal framework. A titanium-aluminum-niobium (Ti-6Al-7Nb) alloy was cast in the mold, and the denture was then fabricated by the conventional method. The casting satisfactorily reproduced the embossed letters, and the plate was identifiable through the gingiva-colored acrylic denture base resin. Since an embossed metal plate integrated with the skeleton is embedded in the denture base resin material, the current denture marking technique serves as a simple procedure for insertion of an undegradable denture identification mark which makes it possible to identify the nationality of the denture wearer.

Application of a preliminary light-curing unit for enhanced bonding between a gold alloy and veneering materials

PURPOSE

To evaluate the effectiveness of a preliminary light-curing unit when it was used in a procedure to bond veneering material to metal.

METHODS

Two light-activated composite materials (Artglass and Cesead II) were separately placed onto gold alloy disks (Pontol LFC), and polymerized using one of the following three methods: (1) exposure with a high-intensity laboratory light-curing unit (Hyper LII) for 90 seconds; (2) exposure with a preliminary light-curing unit (Targis Quick) for 20 seconds, followed by exposure with the high-intensity unit for 90 seconds; and (3) exposure with the preliminary unit for 90 seconds, followed by exposure with the high-intensity unit for 90 seconds. Shear bond strengths were determined and compared by analysis of variance and post-hoc multiple comparison intervals. The curing depths of the two materials polymerized with the two curing units were determined using a scraping technique described by the International Organization for Standardization (ISO) 4049 with the aim of evaluating the difference in curing performance between the two units.

RESULTS

The group polymerized using the preliminary unit for 90 seconds showed statistically improved bond strengths over the group polymerized without the preliminary unit (P < 0.05) regardless of the materials. Regarding the Cesead II material, both groups polymerized using the preliminary unit also indicated significantly improved bond strength compared with the group polymerized with high-intensity only. Also, curing depth results revealed that the high-intensity unit demonstrated greater curing performance than the preliminary unit for both types of materials examined.

Immobilization of Octadecyl Ammonium Chloride on the Surface of Titanium and Its Effect on Microbial Colonization In Vitro

The aim of our study was twofold: to immobilize an organosilicon quaternary ammonium salt (3-(trimethoxysilyl)-propyldimethyl-octadecyl ammonium chloride, Si-QAC) on the surface of pure titanium and to investigate the antimicrobial activity of Si-QAC-immobilized titanium against microbial adherence and biofilm formation. The results of ToF-SIMS analysis of Si-QAC-titanium suggested the possibility of immobilizing Si-QAC on titanium surface through Ti-O-Si coupling, and that Si-QAC treatment significantly reduced both the adherence and colonization of Candida albicans and Streptococcus mutans isolates. The antimicrobial activity was achieved through at least two mechanisms: the first was attributed to the octadecyl alkyl chain which inhibited initial adherence, and the second was attributed to the quaternary ammonium salt which killed initial adherent cells as well as retarded or inhibited subsequent microbial growth. Further, thermocycling did not significantly reduce the antimicrobial activity of Si-QAC-titanium, and no significant cytotoxicity of Si-QAC-titanium was observed in either cell viability test or proinflammatory cytokine production test using human gingival fibroblasts. These results, taken together, favorably suggested that Si-QAC treatment would be a helpful means to inhibit dental plaque or denture plaque formation.

Comparative strength of metal-ceramic and metal-composite bonds after extended thermocycling

The relative strengths of ceramic-to-metal and composite-to-metal bonds were compared after prolonged thermocycling. A total of 104 cast discs were produced from a gold alloy (Pontor LFC). A ceramic material (Duceragold) was fused to 24 discs to assess the strength of the metal-ceramic bond. An indirect composite material (New Metacolor Infis) was bonded to the remaining discs after surface preparation by Rocatec tribochemical coating, tin plating and priming with a phosphate conditioner [10-methacryloyloxydecyl dihydrogen phosphate (MDP), Cesead II], priming with a thione conditioner (V-Primer) or no treatment (unprimed control). Shear bond strengths were determined before and after thermocycling at 20,000 and 100,000 cycles. Pre-thermocycling bond strengths were ranked in the order: metal-ceramic (40.5 MPa); Rocatec treatment (33.1 MPa) and tin plating-MDP (31.0 MPa); V-Primer (20.9 MPa); and control (11.9 MPa). The bond strengths of the first three groups were not significantly different after 20,000 thermocycles, whereas those of the V-Primer and control groups were significantly reduced. After extended thermocycling (100,000 cycles) the metal-ceramic group had the highest mean shear bond strength (28.5 MPa; P < 0.05), followed by the Rocatec (23.9 MPa) and tin plating-MDP (22.1 MPa) groups. The metal-ceramic bond was the most durable, although its strength was reduced by 29.6% after extended thermocycling. On the basis of these results, we recommend the Rocatec and tin plating-MDP systems for composite-to-metal bonding. Metal-ceramic bonding, however, is superior to metal-composite bonding within the limitation of the current experiment.

Adhesive bonding of titanium-aluminum-niobium alloy with nine surface preparations and three self-curing resins

The purpose of the current study was to evaluate the adhesive performance of metal conditioners when used for bonding between auto-polymerizing methacrylic resins and a titanium alloy. Disk specimens were cast from a titanium-aluminum-niobium (Ti-6Al-7Nb) alloy, air-abraded with alumina, and bonded with 24 combinations of eight metal conditioners (Acryl Bond, ACB; All-Bond 2 Primer B, ABB; Alloy Primer, ALP; Cesead II Opaque Primer, COP; Metafast Bonding Liner, MBL; Metal Primer II, MPII; MR Bond, MRB; Super-Bond liquid, SBL) and three autopolymerizing methacrylic resins (Repairsin, RE; Super-Bond C & B, SB; Tokuso Rebase; TR). Unprimed specimens were used as controls. Shear bond strengths were determined both before and after thermocycling (4-60 degrees C, 20, 000 cycles). The ALP-SB group recorded the greatest post-thermocycling bond strength (21.8 MPa) followed by the COP-SB group (17.8 MPa) and the MPII-SB group. The post-thermocycling bond strengths of the unprimed-SB group and the ALP-RE group were statistically comparable. No significant differences were found among the nine TR resin groups, and these groups showed the lowest bond strength. In conclusion, the use of one of the three conditioners (ALP, COP, and MPII) in combination with the SB resin is recommended for bonding the Ti-6Al-7Nb alloy.

Veneering technique for a Ti-6Al-7Nb framework used in a resin-bonded fixed partial denture with a highly filled indirect composite

This article presents a veneering technique for fixed partial denture frameworks made from a Ti-6Al-7Nb alloy. The fixed partial denture framework was prepared with a magnesia-based mold material and a centrifugal casting machine. An esthetic veneer was fabricated with a highly filled dual-polymerized composite material and a metal-conditioning agent. This technique can be applied as a standardized veneering procedure for the titanium alloy, for which porcelain fusing is currently difficult.

Incorporation of a cast, embossed identification plate into a partial denture framework

This article presents a technique for the fabrication and incorporation of a stable and fireproof identification plate into a cast partial denture framework. Embossing tape is embedded in the wax pattern of the major connector. The resulting casting reproduces the embossed lettering, which is identifiable through the tissue-colored acrylic denture base resin.

Adhesive bonding of composite material to cast titanium with varying surface preparations

The purpose of the present study was to evaluate the surface preparation effects of eight metal conditioners and an adhesive system on bonding between a prosthodontic composite material and cast titanium. Eight primers designed for conditioning base metal alloys (Acryl Bond, All-Bond 2 Primer B, Alloy Primer, Cesead II Opaque Primer, Eye Sight Opaque Primer, Metafast Bonding Liner, Metal Primer II, and MR Bond) as well as a surface modification technique (Siloc) were assessed. Disk specimens cast from titanium (T-Alloy H) were either primed with one of the eight primers or treated with the Siloc system, and then bonded with a light-activated composite material (Artglass). Bond durability was evaluated by thermocycling (4 and 60 degrees C, 1 min each, 20, 000 cycles). After thermocycling, two groups either primed with the Cesead II Opaque Primer material or treated with the Siloc system exhibited significantly greater bond strength (20.0 and 19.0 MPa) than the other groups (0.2-12.6 MPa, P < 0.05). These two systems are considered to be useful for improving bonding between the titanium and the composite material tested.

Shear bond strength of resin composite veneering material to gold alloy with varying metal surface preparations

STATEMENT OF PROBLEM

Although adequate surface preparation is indispensable to achieve a consistent and durable bond between resin composite materials and the metal substructures of veneered restorations, information on the bonding performance of current metal adhesive systems is limited.

PURPOSE

The purpose of this study was to evaluate the surface preparation effects of 4 metal conditioners and 1 adhesive system on bonding between a prosthetic resin composite veneering material and a gold casting alloy.

MATERIAL AND METHODS

Four primers containing sulfur derivative monomer and designed for conditioning noble metal alloys (Alloy Primer, Infis Opaque Primer, Metal Primer II, and Metaltite) and a surface modification technique (Siloc) were assessed. Cast disk specimens made of gold alloy (Pontor LFC) were either primed with 1 of the 4 primers or treated with the Siloc system and bonded with a light-activated prosthetic resin composite material (New Metacolor Infis). Control specimens were also prepared without the use of a bonding agent. Shear bond strengths were determined before and after thermocycling (20,000 cycles) for evaluation of bond durability.

RESULTS

All of the primed and Siloc-treated groups showed improved 24-hour shear bond strengths compared with the control group. After thermocycling, the groups either primed with the Metaltite conditioner or treated with the Siloc system exhibited the highest mean shear bond strengths.

CONCLUSION

The Metaltite conditioner and Siloc system each represent a useful method for improving the bond between the gold alloy and resin composite material tested.

Effect of noble metal conditioners on bonding between prosthetic composite material and silver-palladium-copper-gold alloy

STATEMENT OF PROBLEM

Mechanical retentive devices and the application of complicated surface preparation have been indispensable for bonding composite material to the metal substructure of restorations.

PURPOSE

This study evaluated the priming effects of 4 metal conditioners on bonding between a prosthetic veneering material and a silver-palladium-based casting alloy.

MATERIAL AND METHODS

Four primers designed for conditioning noble metal alloys (Alloy Primer, Metaltite, Metal Primer II, and V-Primer) were assessed (all materials contain organic sulfur compounds). Cast disk specimens made of silver-palladium-copper-gold alloy (Castwell M.C.12) were primed with 1 of the 4 primers, and bonded with a light-activated prosthetic composite material (Axis). Shear testing was performed before and after thermocycling for evaluation of bond durability.

RESULTS

All primed groups showed improved 24-hour bond strengths compared with the unprimed group. After thermocycling, 3 groups primed with the Metal Primer II, Alloy Primer, and Metaltite agents exhibited the highest bond strength.

CONCLUSION

Use of 1-liquid metal conditioners containing sulfur compounds was a simple and useful method for improving bonding between the alloy and the composite material tested.

Primary malignant melanoma of the male urethra

We report a case of primary malignant melanoma of the male urethra, increasing the total number of reported cases to 31. The experience with our case suggests that urinary cytology is a diagnostic method for malignant melanoma and essential in the preoperative diagnosis of this disease.

[A case of bilateral testicular germ cell tumors of different cell types with maturation in the metastatic region]

A case of bilateral testicular germ cell tumors of different cell types and maturation in the metastatic region is described. A 42-year-old man with bilateral testicular swelling visited our clinic. Bilateral high orchiectomy was performed. Subsequent histological examination revealed seminoma and embryonal carcinoma in the right testis and seminoma and mature teratoma in the left. Then bilateral retroperitoneal lymphadenectomy was performed and 7 metastatic regions were found in the para-aortic lymph nodes. One of these revealed histopathologically a mature teratoma containing cartilage constituents. After the operation, multiple drug treatment with Cis-DDP, vinblastine and pepleomycin was started. The patient has been in complete remission for about 1.5 year. In addition, we reviewed the literature about bilateral testicular germ cell tumors and maturation in the metastatic region.

Spontaneous maturation in the metastatic region of a bilateral testicular germ cell tumor

A case of bilateral testicular germ cell tumor of different cell types was found to have a mature teratoma in the metastatic region. Histology of the right testis revealed seminoma and embryonal carcinoma while the left testis revealed seminoma and mature teratoma. A mature teratoma, containing cartilage components, was also found in the right para-aortic lymph node. The findings of the case are described and the literature on cases with maturation in the metastatic region are reviewed.

[Compared studies of antimicrobial agents against E. coli, Klebsiella, Citrobacter and Proteus isolated from urinary tract infections]

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients urinary tract infections at 8 hospitals in Japan, were investigated by agar dilution method from July to October in 1979. The summarized results are as follows. 1. Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. Among parenteral antibiotics, CTM was the most active against E. coli and Klebsiella. However, ABPC-resistant E. coli and Klebsiella have appeared to occupy about 40% and 96% of bacteria isolated from urinary tract infections, respectively. 2. In vitro activities of antibacterial agents against Proteus and Citrobacter showed not so potent. 3. Causative organisms in female patients with simple urinary tract infections were mainly E. coli and Klebsiella. 4. Among oral antibacterial agents, PPA have shown similar antimicrobial activities against E. coli isolated from simple and complicated urinary tract infections. ABPC and MPC have been influenced in some degree by these factors. However, parenteral antibiotics are not influenced by these factors. On the other hand, in vitro activities of antibacterial agents against Klebsiella isolated from simple and complicated urinary tract infections were similar.