This review describes a fundamental adhesive technique for seating ceramic restorations, surface preparations for mechanical interlocking, adhesive functional compounds, requirements for luting agents, and clinical performance of resin-bonded ceramic restorations. A number of reports demonstrate effectiveness of hydrofluoric acid etching for sintered porcelain as well as the use of acidic functional monomers as catalysts for silane coupling. Clinical reports suggest that care must be taken to avoid fracture of restorations in service.

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Purpose: The purpose of this study was to examine the influence of anteroposterior inclination of the distal-extension edentulous ridge on the abutment tooth movement under loading on the unilateral free-end saddle with an Aker's clasp and the alteration of the influence by inclining the rest seat anteroposteriorly and splinting the abutment to the adjacent tooth.
Methods: A simulation model with a unilateral distal-extension ridge was used. The movements of the abutment tooth were measured with the Mandibular Kinegiograph under the vertical loading at the point of occlusal surface of the removable partial denture such as an occlusion rim. The experimental conditions were as follows:(1) three types of the anteroposterior inclination of the residual ridge, (2) splinting or non splinting the abutment tooth to adjacent tooth, (3) three types of the anteroposterior inclination of rest seat.
Results: The abutment tooth moved mesially in every experimental condition. Anteroposteriorly inclined rest seats tended to increase the displacement of the abutment tooth. Splinting the abutment tooth with the neighboring tooth tended to reduce the displacement of the abutment tooth.
Conclusion: It was suggested that the anteroposterior inclination of the residual ridge affected the movement of the abutment tooth, but the horizontal rest seat and splinting the abutment tooth were effective for reducing the movement of the abutment tooth.

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Purpose: The purpose of this study was to evaluate the influence of canine guidance inclination through periodontal pulsation.
Materials and Methods: The measurement was completed using a tooth displacement transducer consisting of a photo sensor. Two healthy adult dentate subjects volunteered for this study. Subject A was a non-bruxer while subject B had a history of bruxism. The periodontal pulsation of both subjects before and after clenching tasks were measured. To evaluate the effect of canine inclination on the periodontal pulsation, the lingual surface of subject A's left canine was modified by attaching two metal guidances, consecutively. Metal guidances inclined up to 10 and 20 degrees were prepared, set on the patient's canine and remained in the mouth overnight. The periodontal pulsation before and after clenching tasks were measured the next day.
Results: 1. No difference was found in the periodontal pulsation at rest of subjects A and B. The periodontal pulsation observed in Subject A was similar before and after clenching tasks. However, in subject B, the periodontal pulsation was different before and after clenching. 2. In subject A, the periodontal pulsation did not change by modifying the canine guidance inclination to 10 degrees. Conversely, a change was observed when the inclination was increased to 20 degrees. The periodontal pulsation curve observed was similar to that found in subject B (without canine modification).
Conclusions: From the results, the following conclusions were drawn: 1. Data indicates that it is possible to measure the periodontal pulsation of canine tooth. 2. Tooth guidance inclined up to 10 degrees is acceptable to the periodontal pulsation. 3. Tooth guidance inclined up to 20 degrees is inappropriate and not acceptable to the periodontal pulsation. This means that this inclination is detrimental to the integrity of the periodontal pulsation.

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Purpose: The purpose of this study was to compare two methods of artificially induced loss of occlusal support, tooth grinding and tooth extraction, in determining the behavioral and pharmacological effects of each on the central nervous system in rats.
Method: 5-week-old male Wistar rats were divided into three groups for this study. In Group A, maxillary molar teeth were extracted. In Group B, maxillary molar teeth were ground down. Teeth were left intact in the Control group. A series of spatial memory tasks were performed in an 8-arm radial maze at 1, 3, and 7 weeks for all three groups. Following completion of this task period, levels of neurotransmitters in each group were measured in the cortex, striatum and hippocampus regions.
Results: The results showed that both experimental groups A and B exhibited significant behavioral dysfunction, compared to the Control group; yet behavioral dysfunction was most remarkable in Group A. Pharmacological investigation in Group B revealed that dopamine levels in the hippocampus had dropped. However, in Group A, dopamine levels had dropped in both the hippocampus and the striatum. A correlation between behavior and pharmacological levels is suggested, as spatial memory task results lowered as levels of acetylcholine and dopamine in the striatum dropped.
Conclusions: In conclusion, the effects of experimental tooth extraction on the central nervous system differ from those of tooth grinding.

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Purpose: Mandibular deviation was determined to clarify the effects of strain in facial muscles on the muscular position used as the mandibular position when registering interocclusal relation and occlusal adjustment, if the angle of the mouth was brought sharply back by facial muscles.
Method: Thirteen subjects with no dysfunction of the stomatognathic system kept natural head positions in sitting positions, and had an anterior jig placed to exclude the effects of contact with teeth. Each mandibular deviation when bringing the angle of the mouth sharply back while closing the mouth at the muscular position, and further, when tapping with the angle of the mouth brought sharply back, was determined with a Gnathohexagraph®. The mandibular position for the angle of mouth when tapping after bringing the angle of the mouth to the muscular position was compared.
Results: Compared to the muscular position, average deviations of 0.18 mm backward at the incisal point, 0.00 mm at the left condylar point and 0.04 mm at the right condylar point were found for the angle of the mouth, and anteroposterior variation was greater. Compared to the muscular position, average deviations of 0.50 mm backward at the incisal point, 0.25 mm at the left condylar point back and 0.36 mm at the right condylar point backward were found when tapping after bringing the angle of the mouth back.
Conclusions: The mandibular deviation from the muscular position was found when the angle of the mouth was brought back by straining facial muscles, and anteroposterior variation was greater.
Further tapping after bringing the angle of the mouth back showed that the lower jaw was displaced further back than the muscular position.

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Purpose: The purpose of this research was to develop the standard morphology of the ideal dental occlusion. In this study, the kinetic role of each occlusal facet on upper and lower molars was evaluated by analysis of occlusal contacts during the end phase of jaw closing stroke.
Methods: Masticatory movements of fourteen adult volunteers with chewing gum were measured by a six-degree-of-freedom jaw tracking device. Cast stone models of these subjects were scanned with 3-D digitizer to obtain three-dimensional shape of occlusal surface. These configuration data were linked with jaw movement data to analyze relative position of upper and lower dentition during mastication. Occlusal facets on main occlusing area were classified into six different types (AM, AD, BM, BD, CM, CD) according to the direction of its normal vector and its position. A, B and C represents medio-lateral position of each facet and direction of the normal vector there of, and M and D represents antero-posterior direction of the normal vector. Transition pattern of occlusal contacts during the end phase of closing stroke was studied.
Results: When jaw closing, occlusal contacts was begun with AM or CM type occlusal facet. This finding suggests that AM and CM type occlusal facets work as the functional guidance of masticatory movement. This property was clearer with the occlusal facets on the functional cusp. Incident angle of the terminal jaw closing movement was 30° to BD type occlusal facet, and 40° to BM type facet.
These data suggest that BD type facet meets at a right angle to the occlusal surface, and works for the compression of food during mastication.
Conclusion: Occlusal facets of molar surface were classified into six different types, and the kinetic role of each occlusal facet was revealed.

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Purpose: It is desirable to apply a multi-purpose alloy with good biocompatibility. A recently introduced gold-titanium alloy is reported to show good corrosion resistance and good biocompatibility. The purpose of this study was to evaluate the mechanical properties and the metal-fused-to-porcelain bond strengths of this alloy.
Methods: A commercial gold-titanium alloy was selected. Cast specimens were prepared according to the manufacturer's instructions. The tensile test, the Vickers hardness test and the thermal expansion test were performed. The bond strengths of the gold-titanium alloy to a conventional porcelain and an ultra low-fusing porcelain for metal veneering were evaluated according to DIN 13 927. The bond strength of a conventional gold alloy to the conventional porcelain was also measured as a control. The sectioned specimen of the conventional porcelain fused to the goldtitanium alloy was analyzed with X-ray micro probe analysis.
Results: Mechanical properties, such as Vickers hardness, tensile strength, yield strength and elastic modulus, were modified with heat treatment; the value of the mechanical properties after softening were significantly smaller than those after hardening and those of “as cast”; the properties after hardening nearly reached the classification of the ISO type 4 gold alloy. The coefficient of thermal expansion of this alloy was larger than that of the conventional gold alloy for porcelain. There were statistically no significant differences among bond strengths of three metal-porcelain combinations, all of which were above 40MPa. Elements of the porcelain and titanium were observed on the detached metal surface and the detached porcelain surface respectively. Particles of titanium oxide were observed at the interfacial layer on the sectioned specimens.
Conclusions: This gold-titanium alloy could be applied to various restorations because of its sufficient mechanical properties and bond strengths with porcelain.

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Purpose: The purpose of this in vitro study was to investigate the oral conditions that cause discoloration of 12 mass%Au-Ag-Pd alloy, and to investigate the relation between discoloration and the amounts of volatile sulfur compounds (CH₃SH, H₂S) and oral microorganisms (Fusobacterium nucleatum, Streptococcus mutans) produced.
Materials and Methods: Casts (5×5×0.46mm) of Au-Ag-Pd, titanium, Co-Cr and Au-Pt alloy were incubated in THB broth for four weeks at 37°C. Oral microorganisms such as Fusobacterium nucleatum or Streptococcus mutans incubated in the THB broth. After incubation, the luminance of thecasts were evaluated and color differences (ΔE^*ab) between before and after incubation were calculated according to the CIELab color system. The cast surface was observed using an electron probe X-ray microanalyzer.
Results: 1. Luminance and ΔE^*ab of Au-Ag-Pd alloy incubated with Fusobacterium nucleatum showed a marked amount of accretion, and Fusobacterium nucleatum was related to the production of CH₃SH, H₂S. 2. The casts of Au-Ag-Pd alloy incubated with control and Streptococcus mutans were discolored and discoloration tended to be more marked in THB broth including L-cysteine. 3. The reduced luminance found in the casts of titanium, Co-Cr and Au-Pt alloy was less than that found in Au-Ag-Pd alloy. 4. Qualitative analysis showed that sulfide was produced after four weeks of incubation in Au-Ag-Pd alloy.
Conclusions: The findings indicated in vitro that the production of CH3SH, H2S was related to the discoloration of Au-Ag-Pd alloy. The discoloration of Au-Ag-Pd alloy may also be related to the total oral conditions such as periodontics, halitosis and oral care.

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Purpose: The purpose of this study was to establish the proper usage of an autopolymerizing resin which is the optimum application requirement in early hardening pursued at the initial stage of the autopolymerizing resin using barbituric acid derivatives.
Methods: The shear bond strength of specimens was measured by the change of various polymerization conditions of exposure time, the dipping time and warm water temperature after the autopolymerizing resin identical to that of the autopolymerizing resin block was put on the brush. The plane of the broken surface was observed in the scanning electron microscopic image, and in addition, the rupture condition was classified by visual observation. The classification of the failure patterns was interface failure, cohesion failure and mixing failure.
Results and Conclusion: The shear bond strength increased according to the rise in water temperature in dipping time of 30 seconds, 45 seconds and 60 seconds. It was confirmed that the optimum technical service condition was 60-second dipping time in warm water (temperature of 50°C) and that shear bond strength is about 10 MPa. It proved advantageous to stiffen the autopolymerizing resin using a barbituric acid derivative. It was also confirmed that sufficient stiffening occurred in warm water to decrease the residual monomer.

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Purpose: An in vitro study on the durability of dental adhesion systems was conducted by the immersion test in distilled water. However, the pH of oral environment changes from 2.3 to 8.0. In this study, the immersion tests in solution of pH 2.3 and 8.0 were conducted and adhesive bond strengths were measured after immersion. The results were compared with those attained in distilled water.
Methods: Three dental alloys and a porcelain were used as adherends for fabrication of adhesion specimens. These were immersed in two solutions, one was lactic acid solution maintained at pH 2.3 and the other was sodium hydrogencarbonate solution at pH 8.0. Distilled water at pH 6.0 was also used for comparison. After 36 months of the longest period, shear bond strengths were measured.
Results: Au-Ag-Cu-Pd alloy and Co-Cr alloy specimens bonded with Super-Bond C & B showed abrupt decrease of bond strength in distilled water. Panavia Fluoro Cement specimens showed different characteristics and the bond strengths decreased in lactic acid solution. Porcelain specimen showed cohesive failure in porcelain adherent in every measurement, and adhesion durability could not be studied.
Conclusions: Adhesion durability evaluated by long-term immersion test was affected by the kind of adhesive resin and pH value of immersion solution. However, the differences in dental alloys and their surface treatment did not affect the adhesion durability.

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Purpose: Resin facing crowns are frequently used clinically as aesthetic restorations. Improvement of the adhesion between prosthetic composite resin and the dental alloy decreased the debonding of the resin from the metal frame. However, shade or luster of the resin surface change gradually over a long time, resulting in poor appearance. Although it is easily expected that thermo-cycle testing should affect the surface texture of prosthetic composite resin, details have never been clarified. The purpose of this investigatixon was to clarify the effects of thermo-cycle testing on surface texture of prosthetic composite resin.
Methods: Square (8×8×1.5mm) specimens were fabricated by 4 photo-curing prosthetic composite resin. The measuring surface was polished according to the clinical procedure. Surface textures before and after thermo-cycle testing (4°C60°C) were investigated by macroscopic observation, pigment penetration test, measurement of surface roughness and scanning electron microscopic (SEM) observation of the microstructure.
Results: Macroscopic observation revealed a rough mat surface, and the pigment penetrations were increased on the thermo-cycled specimens. Surface roughness of the thermo-cycled specimens was increased as compared with that of the non-thermo-cycled specimens. Furthermore, SEM observation demonstrated cracking and partial peeling of the thermo-cycled resin surface.
Conclusions: Since thermo-cycle stress causes various changes to the surface texture of the prosthetic composite resin, it is an important factor, which deteriorates the aesthetic quality.

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Purpose: In daily clinical treatment, the crown restoration was dislodged from root dentin with the cast post. With regard to the cause of this dislodgment, morphology of the post or stress distribution have been evaluated. However, adhesion to the tooth was evaluated only a little, and furthermore, the evaluation of the adhesion is only to the crown dentin. In this study, to elucidate the cause of the dislodgment of post cores from the tooth, differences between the adhesion of resin cements to the crown dentin and that to the root dentin were evaluated.
Method: Human teeth were extracted and frozen. The human teeth were allowed to thaw before use, and the crown dentin and tooth root dentin were polished with #1000 water-resistant paper. In the adhesion test, 4 types of commercially available resin cements were used. Furthermore, the conditions of resin after treatment by preliminary treatment materials and resin tags after adhesion by resin cements were observed with a scanning electron microscope.
Results: Tooth crown dentin showed greater adhesion than tooth root dentin in all 4 types of resin cements. Removal of smeared layers by preliminary treatment materials was marked in tooth crown dentin. Furthermore, the presence of longer resin tags in tooth crown dentin was confirmed.
Conclusion: It was suggested that to improve the adhesion of resin cement to tooth root dentin, it was necessary to perform the treatment of smeared layers in tooth root dentin on the same level as in tooth crown dentin.

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Purpose: This study was performed to examine whether different torques to fasten a superstructure with a screw affected mechanical mobility of IMZ implants with intramobile connector (IMC) or titanium element.
Methods: Eight IMZ implants in five patients were used for this study. The same superstructure was fastened with occlusal screw to each implant with IMC or titanium element at 85, 145 and 180 Nmm torque values using a torque wrench. The horizontal mechanical mobility of each implant was measured three times by the automatic diagnostic system for tooth mobility.
Results: The larger the torque values were, the smaller mechanical mobility of IMZ implants with IMC was. Friedman test indicated that mechanical mobility of IMZ implants with IMC significantly changed according to torque values (p<0.01). However, changes in mechanical mobility of the implants with titanium element were not statistically significant. At the fastening torque of 85 and 145 Nmm, a difference in mechanical mobility between implants with IMC and titanium element was statistically significant (p<0.05). However, fastening torque of 180Nmm did not show significant difference.
Conclusions: A superstructure fastened with occlusal screw at torque values of 85 and 145Nmm had little influence on the stress absorption effect of IMC under horizontal load.

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