Search

Background The present review aimed to investigate the feasibility and clinical effectiveness of a direct bonded fixed partial denture (DBFPD) based on available literature. The efficiency of a DBFPD is mainly affected by the type of artificial denture tooth, the type of luting agent, and the adhesive preparation. Methods The parameters were reviewed based on the in vitro and in vivo studies conducted. An acrylic resin tooth or a composite resin tooth for removable dentures should be used as the artificial tooth for the pontic. Results Considering the luting agent, a methyl methacrylate-based resin luting agent, which has low mechanical strength but is capable of plastic deformation and could sustain for a long time, should be used. Appropriate pre-adhesive treatment should be performed on both the artificial and abutment teeth. The cases in which a DBFPD can be applied are limited to one missing anterior tooth, as long as it is not overstressed. Patient cooperation in cases of occlusion seems to be another prerequisite. Conclusion Knowledge and selection of the material and case indications are essential, and patient cooperation is pertinent in studying the long-term prognosis of a DBFPD.

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.

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.

Purpose In recent years, the application of restorations and fixed dental prostheses to molars by computer-aided design-computer-aided manufacturing (CAD/CAM) with composite resin has been increasing. Titanium and titanium alloy having a high tissue affinity and good biocompatibility are suitable for cases where CAD/CAM fabrications are inadequate, such as allergic reaction to metal. Many studies have reported methods of production with titanium and titanium alloys. The purpose of this review is to survey the clinical application of titanium and titanium alloy restorations and fixed dental prostheses with various fabrication systems. Study selection A literature search in PubMed was performed for various fabrication systems of titanium and titanium alloy from 2010 through 2019. The search keywords were “titanium”, “titanium alloy”, “CAD/CAM”, “cast”, “fabrication system”, “marginal gap”, “internal gap”, and “clinical performance”. Only relevant studies are summarized and discussed in this review. Results With any fabrication system, titanium and titanium alloy restorations and fixed dental prostheses fabricated with various systems were within the clinically acceptable ranges of marginal gap and internal fit. Additionally, these restorations were considered to have less effect on the periodontal issues. Although metal–ceramic restoration has clinical performance problems, such as ceramic fracture, fabrications with only titanium and titanium alloy were reported to have good clinical performance. Conclusions Regardless of the fabrication system, titanium and titanium alloy restorations and fixed dental prostheses can be applied clinically. Titanium and titanium alloys are thought to be a promising alternative to the dental metals currently used.

Purpose To evaluate the influence of polymerization methods and a metal priming agent on the bond strength between gold alloy for metal ceramic restorations and dual-cure-type resin luting agents, and on the strength and hardness of the luting agents. Methods A total of 154 disks cast by a gold alloy were treated with or without a metal priming agent. One of the three luting agents was applied on the disk. The luting agent was either chemically or dual-polymerized. The shear bond strength was measured both before and after thermocycling. In addition, scanning electron microscope (SEM) observation, flexural strength test, and Knoop hardness test were performed. Results Significant differences among the luting agents were observed in terms of bond strength and flexural strength. Significant differences between chemically and dual-polymerized luting agents were observed regarding shear bond strength, flexural strength, and Knoop hardness before thermocycling. The application of the priming agent was effective only for a luting agent. Conclusion Both bond strength and flexural strength differed among three luting agents. The effect of the priming agent on bond strength differed among the luting agents. Both the bond and flexural strength of a chemically polymerized luting agent differed before or after thermocycling.

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.

Accurate impressions are essential in fabri-cating dental restorations and fixed dental prostheses. During the last decade, digital impression systems have improved substantially. This review discusses the accuracy of digital impression systems for fabrication of dental restorations and fixed dental prostheses. A literature search in PubMed was performed for the period from July 2010 through June 2017. The search keywords were Cerec, digital impression, direct digitalization, indirect digitalization, and intraoral scanner. Only relevant studies are summarized and discussed in this review. In general, the latest systems have considerably reduced the time required for impression making, and the accuracy and marginal fit of digital impression systems have recently improved. Restorations and fixed dental prostheses fabricated with currently available digital impression systems and intraoral scanners exhibit clinically acceptable ranges of marginal gap in both direct and indirect procedures.

The outbreak of novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. Nasopharyngeal swabs are widely used in polymerase chain reaction (PCR) test to detect SARS-CoV-2. However, the collection of nasopharyngeal swabs has a series of drawbacks concerning exposure of healthcare staff, difficulty in collection, and discomfort of patients. Therefore, an alternative noninvasive sample for diagnostic of emerging viral diseases is required. The usefulness of saliva screening tests is compared to conventional swab tests in this report. The results suggest that saliva could be a reliable sample for detecting SARS-CoV-2.

This study aimed to evaluate the bonding behavior of two acrylic resin adhesives joined to titanium-aluminum-niobium (Ti-6Al-7Nb) alloy primed with two metal conditioners. Cast Ti-6Al-7Nb alloy disks were air-abraded with alumina and bonded with six combinations of two resin adhesives (Super-Bond C&B and Multi Bond) and three surface conditions (Alloy Primer, M.L. Primer, and unprimed control). Shear bond strengths were determined both before and after 20,000 thermal cycles. The tri-n-butylborane initiated Super-Bond C and B resin exhibited greater bond strength than the BPO-amine initiated Multi-Bond resin. Both the Alloy Primer with a hydrophobic phosphate and the M.L. Primer with a phosphonoacetate effectively improved the 24-hour bond strength of Multi-Bond resin as well as the post-thermocycling bond strength of Super-Bond C and B resin.

This study aimed to evaluate the effect of adhesive systems based on a thiouracil monomer on bonding to silver-palladium-copper-gold (Ag-Pd-Cu- Au) alloy (Castwell M.C.12). Disk specimens were cast from the alloy and then air-abraded with alumina. The disks were bonded using six bonding systems selected from four primers and three luting materials. Shear bond strengths were determined both before and after thermocycling. Bond strength varied from 2.7 MPa to 32.0 MPa. Three systems based on a thiouracil monomer (MTU-6) showed durable bonding to the alloy, with post-thermocycling bond strengths of 22.4 MPa for the Metaltite (MTU-6) primer and Super- Bond, a tri-n-butylborane (TBB) initiated resin, 9.0 MPa for the Multi-Bond II resin, and 8.1 MPa for the Metaltite and Bistite II system. It can be concluded that a combination of thiouracil-based primer and TBB initiated resin is effective for bonding Ag-Pd-Cu-Au alloy. (J Oral Sci 52, 405-410, 2010)

This study evaluated the effect of preliminary irradiation on the depth of cure and Knoop hardness of a veneering composite. The composite was filled into a mold, and irradiated with different irradiation duration or irradiance. After removing the mold, the depth of cure was measured, and the Knoop hardness number at each depth was determined and statistically analyzed using Mann-Whitney U test. Depth of cure of the composite polymerized by the Sublite S unit with a distance of 15 cm for 30 or 60 s was less than 2.0 mm. The Knoop hardness number of the group polymerized by the Hyper LII unit without preliminary irradiation and the group polymerized by the Sublite S unit with a distance of 3 cm was higher than that of the group polymerized by the Sublite S unit for 90 s or the group polymerized by the Solidilite unit, respectively, even though the depth of cure for these four groups was higher than 2 mm. Preliminary irradiation with long duration and low irradiance caused a low degree of polymerization, which is probably effective in enhancing the bond strength between veneering composite and cast framework. (J Oral Sci 52, 71-75, 2010)

The aim of this study was to evaluate in vitro the shear bond strength to a gold alloy of RMGICs combined with three metal priming agents. Gold alloy was primed with one of the following materials: Alloy Primer, Metal Primer II, or Metaltite. Non-treated group was considered as the control. Specimens were bonded with one of the following luting agents: Super-Bond C&B, Vitremer Luting Cement, Fuji Lute, or Xeno Cem Plus. Shear bond strength was then determined. The bond strengths of resin-modified glass ionomer cements primed with the metal priming agents were greater than that of non-treated group, except for the Vitremer Luting Cement-Alloy Primer combination. It was thus concluded that the priming agents employed in this study were substantially effective in improving the bonding of resin-modified glass ionomer cements to gold alloy.

The purpose of this study was to evaluate the influence of heating, cast bonding, and subsequent polishing procedures on attractive force of magnetic attachments. Two magnetic attachment systems with keepers of different chemical compositions (Hicorexslim 3013, 447J1; Magfit EX400, AUM20) were employed. Keepers examined were: (1) untreated; (2) heated; (3) cast-bonded with Ag-Pd alloy; (4) cast-bonded with Ag-Pd alloy and polished; (5) cast-bonded with gold alloy; and (6) cast-bonded with gold alloy and polished. Attractive force was determined with a force gauge, and surface structure was evaluated with scanning laser and electron microscopes. Attractive force of the Hicorex system was reduced by cast bonding, whereas that of the Magfit system was reduced by both heating and cast bonding. However, attractive force of both systems was somewhat recovered through the polishing process. Based on the findings of this study, it was suggested that careful polishing after cast bonding was indispensable to the recovery of attractive force for both attachment systems.

The purpose of the current study was to evaluate the effect of a metal priming agent on wear resistance of gold alloy-composite joint. Four types of plate specimen were prepared: composite (Estenia CB or Epricord) alone, type 4 gold alloy alone, alloy-composite joint without priming agent, and alloy-composite joint bonded with a priming agent (Alloy Primer). Three-body wear test was performed using the plate specimens, gold alloy antagonist, and polymer slurry. Joined specimens with priming exhibited less wear depth (in microm; 21.0 for Estenia and 24.9 for Epricord) than the joined specimens without priming (57.8 for Estenia and 46.7 for Epricord). Wear depth of the single plate specimens when abraded with the gold alloy antagonist was ranked as follows: Estenia (9.6), gold alloy (12.8), and Epricord (19.1). It was concluded that the use of a metal priming agent at the alloy-composite interface effectively enhanced the wear resistance of the joined area when under cycled loading.

The purpose of the current study was to evaluate the effect of functional monomers contained in the primers on adhesive bonding of a steel alloy. SUS XM27 steel was primed with one of the following materials; Alloy Primer, Estenia Opaque Primer, and V-Primer. The functional monomers in the primers were a phosphate (10-methacryloyloxydecyl dihydrogen phosphate; MDP) and a thione (6-(4-vinylbenzyl-n- propyl) amino-1,3,5-triazine-2,4-dithione, -dithiol tautomer; VTD) for Alloy Primer, MDP alone for Estenia, and VTD alone for V-Primer. The steel disks were bonded with an acrylic resin (Unifast Trad), and bond strength was determined. Of the three primers, both the Alloy Primer (33.3 MPa) and Estenia Opaque Primer (33.9 MPa) materials exhibited far better post- thermocycling bond strength than V-Primer (0 MPa). It can be concluded that the phosphate MDP is effective, whereas the thione VTD is ineffective for bonding SUS XM27 steel. (J. Oral Sci. 48, 215-218, 2006)