Collarless porcelain veneer crown has excellent esthetic properties in the area of the lavial margin. It can eliminate the underlying metal collar and minimize the plaque retention. Several techniques such as platinum foil, refractory die, and direct lift techniques, have evolved an attempt to simplify the making procedure of this restoration. The present paper deals with the improved direct lift technique. The conventional direct lift technique has a problem of poor marginal integrity. Recentry "margin porcelain", high temperature fusing dentin powder, and "corrective powder of margin (C.P.M)" were developed, and the use of these materials could easily improved the adaptability of the porcelain margin. After cementation of the porcelain crown, cement thickness was between 5 to 18 μm at the margin. It is found that the margin of the porcelain crown has a tendency to be rounded off during final baking. Such a rounded shape of the margin will result in allowing the minimal extention into gingival sulcus and it may be favorable for the periodontal health. This technique does not require as much skill for the dentist and technician as the other techniques do. Although some problems still remain in the die material or others, this technique was confirmed to be effective.
In order to investigate the cause of pigmentation occurring in the gingival tissues after setting metal core (silver alloy), three healthy dogs with pinkish gingivae were used. Experimental conditions which may be supposed clinically for building up metal core were given as the following four types. Type I : Post crown type reproducing original tooth form. Type II : Jacket crown type with shoulder of 1.0mm in width. Type III : Re-preparation type of metal core without inflicting a wound to the gingival sulcular epithelium after setting Type I. Type IV : Re-preparation type of metal core inflicting a wound to the gingival sulcular epithelium after setting Type I. From 4th weeks after the setting metal core, changes in the gingival tissues were observed macroscopically, histopathologically and electron microscopically (TEM). Additionally, some of the samples were given electron-probe microanalysis. The main results obtained were as follows ; 1. Macroscopic findings Inflammatory changes, such as redness and swelling, were observed in each type on gingival tissue, but no significant gingival discolorations were found. 2. Light microscopic findings A few black depositions (metal fragment) were observed only in the gingival lamina propria mucosae of Type IV. These depositions had been surrounded by histiocyte-like cells. In other experimental types, severe inflammatory changes were observed, but no depositions were found in the gingival tissues. 3. Electron microscopic findings These depositions were found to consisted of fragmentary dense mass surrounded by a halo of material of lower electron density composed of fine particles and filaments. Around these depositions, dense fine particles had been taken into the histiocyte-like cells, and had been associated with lamina densa on the basal lamina of gingival basal epithelium. 4. Result of electron-probe microanalysis Analysis of the spot showed that these depositions were composed of high peak silver and sulphur, which were considered to be in the form of silver sulfide.
Because of the need to make dental records from the standpoint of patients, we tried to make a problem oriented dental records (PODR) for the patients with temporomandibular disorders according to the thought of problem oriented system (POS). This PODR is based on the TMD patients protocol made by TMD Team Approach, Kyushu Dental College and referred to the PODR of UCLA Pain Management Center and the PODR of Kyushu Dental College Hospital. This PODR consists of five parts such as data base, problem list, initial plan, progressive note and discharge summary. The data base consisits of seven different sheets such as patient profile, history 1 and 2, examination 1, 2 and 3 and X-ray. Examination sheets include nine items of examination such as posture and facial symmetry, palpation, range of motion, TMJ noise, bite maneuvers, joint play, occlusion, guidance and soft tissue. The X-ray sheet includes four items of findings such as pantomogram, transcranial, orbit-ramus and MR images. The problem list sheet is the record of patients problem list, current medications, concomitant treatment and allergies. The initial plan sheet is the record of assessment (A), diagnostic information required (DxI), plan (P) and patient education (PtEd). The progressive notes sheet is recorded in accordance with the SOAP, and a medication log sheet is added with this sheet. The discharge summary sheet is the record of data base, initial problem list, treatment, current problem list, treatment outcome and summary. We would appreciate readers comments and complete this PODR.
With increasing precision applied in casting crown prosthodontics in recent years, precision in micrometric degrees has become a requirement for fitness. A crown, a connective crown and a bridge of the anterior faced crown, all of which were prepared and set by one and the same clinician, were obtained without damage together with the teeth. Examination of the clinical fitness of these specimens were therefore made. Examinations were made of the fitness at the restorative crown margin, labio-lingual and mesio-distal sectional surface. Film thickness of cement layer was also measured with the reader scale after enlarging the layer a 100 times by a profile projector. The marginal fit of the cemented crown were far better than the values Murakami, et al obtained from autopsy cases, but fell rather short of the experimental values obtained by Yoshida, et al. The cement thickness of the specimens A, B and C were 284μ, 188μ, and 117μ, respectively, at the marginal portion of crown, and 87μ, 170μ, and 56μ, respectively, at the portion beneath incisal edge. The cause of lowering the fitness of the specimens examined may be attributed to the matters of tooth preparation, impression taking, preparation of die and temporary crown and the fundamental cares to be taken in each stage. The present examination reconfirmed the need and importance of giving due considerations to (1) the method of trimming, (2) deformations at the time of making and extracting wax patterns, imbedding, and casting, and (3) probable inclination at the time of cementation.
By reference to the patient chart concerning 140 patients of the temporomandibular joint disorders (TMJD) in Department of Prosthetic Dentistry of the Kyushu Dental College Hospital for five years from January 1979 to December 1983, the records about their sex, age, chief complaint, side of symptoms, treatment method, and treatment frequency were statistically pursued. The results obtained were as follows : 1. The number of patients of TMJD increased every year and the ration of man to woman for five years was about one-three. 2. The number of patients was highest in the 20 to 39 year age range. 3. Pain was the most frequent chief complaint of patients by an overwhelming majority compared with other complaints. 4. On the side of TMJ symptoms, unilateral was more numerous than bilateral. 5. In the investigation of treatment methods, splint therapy increased, but physical therapy decreased for the five year period. 6. Fixed prosthodontics were more numerous than removable prosthodontics in prosthetic treatment. 7. The treatment frequency of patients of TMJD decreased every year with progress in examination, diagnosis, and treatment methods.
From the viewpoint of dental prosthodontic purpose, it is important to restore function and esthetics. Harmony in color is one of the important factors in dental esthetic requirement. Dental porcelain have been widely used as a restorative material because of its ability to maintain its surface texture and color for an extended period without losing its naturalness and esthetic qualities in matching the adjacenting tooth structure in translucence, color and intensity. In the past, however, it was rather difficult to effect porcelain restoration which harmonized in color with the adjacent natural teeth. There are many factors which affect color stability during porcelain firing. With a realization that the number of firing affects color, an experiment was conducted to determine the relations of the number of firing and of the materials to color. For the experiment, vacuum fired porcelain test pieces, containing either opaque, body, or enamel, were subjected to repeated firing in vacuum for a different number of times and to natural glazing after firing. The color and color difference were then determined with a color meter. The integrating sphere system of JIS Z8722-II was used for measuring the color and color was represented by Y.X.Z. of tristimulus values of CIE system. A computer program with the numerical value of Hunter's and CIE color systems was prepared to obtain Hunter's numerical representation (L.a.b) of color. Representation of color and color difference were calculated with L.a.b. numerical values for every test piece in each group, which had been subjected to repeated firings and natural glazing. From the value of Hunter's and Munsell's color systems, the color and its variations were described with popularly used 'Hue, Chroma, and Value'. The ⊿E of color difference in repeated firings and glazing was compared with that of the first firng for each test piece. The results were as follows : 1. The ⊿E of color difference in repeated firings of the opaque test pieces was almost below 1.5 NBS, which varied from 'trace' to 'slight' macroscopically. The changes were caused by an increase in chroma or in value. 2. The ⊿E of color difference in repated firings of the body test pieces was between 0.5 and 1.5 NBS. The change in the range of 'slight' were observed from the 3rd to 6th firings. The changes ranged from 'noticeable' to 'much' after the 7th to 10th firings (After the 2nd to 6th firings in the enamel test pieces). 3. Over 1.5 NBS were detected macroscopically following the 7th or 8th firing of the body test pieces (After the 4th to 7th firings in the enamel test pieces). 4. The degree of color difference increased in proportion to the number of firing in both the body and the enamel test pieces. The changes were caused in most cases by an increase in value and particularly by an increase in chroma. 5. Better surface glossiness was seen following the 1st to 3rd firings but the glossiness decreased thereafter in proportion to the number of firing. 6. Glossiness was lost in natural glazing following the 8th firing in the body test pieces (After the 5th to 7th firings in the enamel test pieces). 7. The test pieces with glossiness after glazing decreased in value.
It is practically difficult to seat the full cast crown satisfactorily on the prepared tooth during cementation. Two clinical technics have been adopted so far to aid better seating of the crown restoration : (1) internal surface relief and (2) perforation of the crown to provide a vent for the cement to escape. The present article describes a newly designed crown restoration to minimize the elevation of the crown at the margin. It consists of an internal crown covering the axial surface up to the finishing line and an ordinary, external crown over the internal one. On cementation of the internal crown, the cement can easily escape toward the open occlusal plane, and the resultant average cement thickness between the internal crown and the tooth becomes as thin as 4.8μm at the margin. It indicates that the adequate application of such an internal crown would allow the cast crown restoration to seat more completely and reduce the influence on the marginal gingiva.
It is practically difficult to properly seat the full cast crown on the prepared tooth by means of a luting cement. We have devised the double-crown system consisting of an inner crown and an outer crown to aid better seating of the crown restoration. It can minimize the elevation of the inner crown at the margin, because its open occlusal plane allows the cement slurry to easily overflow. Although the inner crown should be very thin, it is not easy to fabricate it precisely by casting. In this study, therefore, the application of the sintering procedure by powder metallurgy to the formation of the inner crown was evaluated in terms of marginal fit before and after cementation and surface aspect. The results obtained were as follows : 1. There were no significant differences in the try-in marginal fit between the full cast crown, cast inner crown and sintered inner crown. 2. Both the cast and sintered inner crowns showed a small elevation at their margins by cementation, while significantly larger elevation was found in the cast full crown. 3. The surface roughness test and SEM observation revealed no obvious differences in the metal surface aspect between the sintering and casting method procedures. It was suggested from the foregoing results that the powder metallurgy could be effectively available for easily making the inner crown in the double-crown system.
