The third deciduous molars of young dogs about 3 months old were extracted, and daily changes in the extraction wounds and the surrounding tissue were investigated radiologically, optically, and pathohistologically from the 3rd to the 30th day after extraction. The results were as follows : 1. On the 3rd postoperative day, radiograms showed about the same radiolucency for the extarction wounds of the medial and distal roots. In microphotograms, however, the lower portion of the extraction wound of the distal root showed low density curves. Pathohistologically, new bone formation was seen in the distal side of the bottom of the extraction wound of the distal root. 2. In the radiograms on the 7th day, healing of the distal side in the middle portion of the extraction wound of the distal root was remarkable. Healing of the medial side in the middle and lower portions of the extraction wound of the distal root was active. Pathohistologically, epithelium extended to half of the surface of the extraction wound of the medial root. In the extraction wound of the distal root, epithelium covered nearly all of the surface. Where bone healing was markedly seen, many osteoblasts were observed. 3. On the 14th day, epithelium tissue completely covered the surface of the extraction wound of the medial root. Healing of the medial and distal sides was faster than that of other sites and tissue fusion of new trabeculae and the surrounding alveolar bone was observed. Osteoblasts were found up to the upper portion of the extraction wound of the distal root. New trabeculae were seen in all parts of the extraction wound. 4. On the 21st day, gingival epithelium of stratified rquamous epithelium widened its stratum corneum and corvered the surface layer of the extraction wound. Although the extraction wounds of the medial and distal roots were markedly radioopaque, healing of the middle portion of the extraction wound of the medial root continued and that of the central and distal sides especially was remarkable. In the extraction wound of the distal root, healing of the distal side in the upper portion was remarkable. 5. On the 30th day, the gingival epithelium covering the extraction wound widened its stratum corneum and formation of secondary papillae was remarkable. The proper layer of the connective tissue immediately below was continuous with the surrounding healthy tissue. Although healing of the central and distal sides was still in progress, new formation of trabeculae was seen in the medial and distal sides in the upper portion of the extraction wound. Appearance of osteoclasts in the distal side of the alveolar bone was remarkable because of growth of the succeeding permanent tooth in the extraction wound of the distal root. 6. Observation of changes in density in radiograms showed that the postoperative duration from the 7th to 14th days was the period when new bone formation was very active in healing process of the extraction wounds of deciduous teeth. The process mainly consisted of bone healing in the medial side of the middle portion of the extraction wound of the medial root and in the distal side of the middle portion of the extraction wound of the distal root. 7. In the subjects on the 3rd and the 7th day after extraction of deciduous teeth, slight inflammatory round cell infiltration and sparseness were observed in connective tissue of the dental sac surrounding the succeeding permanent tooth. However, extraction of deciduous teeth had almost no effect on formation and eruption of germs of permanent teeth.

View full abstract

Porcelain teeth have various advantages for their use clinically. However, the designs currently used for most porcelain teeth provide mechanical locking with the use of metal pins or undercut wells (diatoric form). These designs weaken the teeth and do not prevent the leakage of fluids along the tooth-resin interface, which has created poor oral hygiene and esthetics. Therefore, if porcelain teeth are bonded chemically to the denture base of acrylic resin without the use of pins, failure in porcelain teeth will decrease significantly in clinical use. So an attempt of creating such chemical bonding between porcelain teeth and acrylic resin was undertaken utilizing a kind of silane coupling agents, gamma-methacryloxypropyltrimethoxysilane. The results were as follows : 1. The chemical bonding of porcelain teeth to the denture base of heat-curing acrylic resin was accomplished by the addition of gamma-methacryloxypropyltrimethoxysilane in the methyl methacrylate monomer for the heat-curing resin. 2. More than 4 wt% concentration solution of the silane in the methyl methacrylate monomer for the heat-curing acrylic resin produced a stable bonding strength, and also a sufficient anchorage was observed after breakage on the surface of test pieces. 3. Inclusions of gamma-methacryloxypropyltrimethoxysilane in the methyl methacrylate monomer for the heat-curing acrylic resin did not create any change in the physical properties of the heat-curing resin. However, a slightly increased sorption of water in the cured acrylic resin was observed by inceasing the concentration of the silane in the methyl methacrylate monomer. 4. By evaluating the effect of the silane bond on porcelain anchorage strength, it was concluded that a 6 wt% concentration solution of the silane in the methyl methacrylate monomer for the heat-curing acryic resin was sufficient. 5. Data indicated that a large difference in the thermal expansion existing between the bonding surfaces can cause a lowering of bonding strength when the bonded specimen was alternately dipped in the cold and the hot water baths and subjected to thermocycles from 5, 000 to 10, 000 times. 6. The bonding strength of the adhesive acrylic resin to the porcelain teeth was not affected by the total immersion in water (36℃) for 90 days. 7. A dye penetration test showed that the firm bonding of the adhesive acrylic resin to the porcelain teeth prevented dye penetration far more effectively than in the case of bonding of non-adhesive ones with the porcelain teeth. On the base of the above results, it was concluded that the porcelain could be bonded stably to the denture base of heat-curing acrylic resin by using the silane added monomer for acrylic resin. This silane added adhesive acrylic resin is much more reliable for clinical use than non-adhesive ones.

View full abstract

With 20 skulls of Japanese cats as the material, the mandibula, upper and lower dental arch palate, and teeth were examined morphologically. Although they belong to carnivorous order, cats are said to have masticatory organs better suited for carnivorous diet than the members of the dog family. Therefore, the cats were examined in comparison with other mammals, particularly with carnivorous animals. The results were summarized as follows : 1. The cephalic length-width index for the cats was 70.72. The cats were brachycephalic whereas most of the animals in the dog family were mesocephalic. 2. Thomson's mandibula index for the cats was 97.09, which was lower than the index for bobcats and those for the members of the dog family. This finding indicated that the inter-mandibular head width was greater, although slightly, than the mandibular length in the mandibula of the cats. 3. In the palatal form of the cats, the width was relatively wider in proportion to the length and the height was markedly low as compared with those of other mammals. 4. The number of the transverse palatine folds was 8 in 71% and 7 in 29%. The folds got longer successively from the front to the back. However, the eighth fold was small and rudimental. 5. The dental arch index at M_1 was 114.88 for the maxilla and 98.60 for the mandibula. These values were markedly greater than those of other mammals and indicated that the width of the dental arch was relatively wide in proportion to the length of the dental arch. 6. Diastema was 3.47mm between I_3 and C, 2.83mm between C and P_2, and 2.00mm between P_2 and P_3 in the maxilla, and 7.03mm between C and P_3 in the mandibula. Unlike the members of the dog family, diastema was found between C and P_2 and between P_2 and P_3 in the maxilla in the cats. 7. The measurements of the crown height indicated that the paracone, 5.10mm at P_4 and 5.11mm at P_3, was the highest. The mesiodistal diameter was 10.13mm at P_4 6.54mm at P_3, and 3.31mm at M_1. The buccolingual diameter was 5.45mm at P_4, and 3.44mm at P_3, and 1.86mm at M_1. P_4 was the largest follwed by P_3 and M_1. 8. In the measurement of mandibular molars, the paraconid at M_1 and the protoconid at P_4 and P_3, 5.45mm, 5.11mm, and 4.41mm, respectively, were the highest. The mesiodistal diameter was 7.89mm at M_1, 6.97mm at P_4, and 5.42mm at P_3. The buccolingual diameter was 3.52mm at M_1, 3.06mm at P_4, and 2.59mm at P_3. The tooth size became successively smaller toward the front from M_1 to P_4 and P_3. 9. In the proportion of other molars to the carnassial tooth, P_3 was about 64% in the mesiodistal diameter and about 63% in the buccolingual diameter, and M_1 was about 32% in the mesiodistal diameter and about 34% in the buccolingual diameter, in the maxilla. Diminution percentage of M_1 was noticeable. In the mandibula, P_3 was about 69% in the mesiodistal diameter and about 74% in the buccolingual diameter, and P_4 was 88% in the mesiodistal diameter and about 87% in the buccolingual diameter. As compared with those in the maxilla, diminution percentage was small. 10. The coronal width-thickness index was 185.75 for P_4 in the maxilla and 224.47 for M_1 in the mandibula indicating that the mesiodistal diameter was markedly large in proportion to the buccolingual diameter.

View full abstract

In order to clarify initial figure of the mandibular symphysis, which was closely associated with the development of the bone (=the submaxilla), a histological study was done based on serial sections from 12 human fetuses (ranging from 2.5 up to 10 cm CF length). The results were as follows. The development of the mandible : 1. The first formation of the osteoid tissue was observed, showing the contact with Meckel's cartilage in the undifferentiated mesenchymal connective tissue around cartilage of the 2.5cm case. 2. The osteoid tissue was differentiated into the bone tissue in the 5.5cm case. 3. The bone tissues, which had been formed at the upper and lower sides of Meckel's cartilage, extended above and below with the growth of the fetuses. Furthermore, the upper end of the bone tissue extended inside and outside, while the lower end extended outside and inside, and the center extended outside continuously. Thus, the anlage of the mandible was formed. The initial figure of the mandibular symphysis : 1. The initial figure of the mandibular symphysis was confirmed in the 8.0cm case. 2. The bone trabeculae inside the lower end of the bone tissue played an important role in the development of the mandibular symphysis. 3. The extension of the trabecular bone was differentiated, grown, and increased by a chain of structure including connective tissue layer, transitional layer, osteoblastic layer and homogenous layer.

View full abstract

Solid media and culture conditions for mycelial (M) growth were investigated for the purpose of defining the mechanism of the yeast (Y)-M transition in Candida albicans (C. albicans) ATCC 1002 strain. Germ tube (GT) formation media were prepared based on results obtained by using solid media. The effect of thiazolidine-4-carboxylic acid (thioproline) (selected as one of the growth media components) on germination in C. albicans was studied. The results obtained were as follows. 1. When each amino acid was added to agar media composed of 10^<-2>% MgCl_2 and 10^<-2>% NaH_2PO_4, L-proline was the only amino acid to stimulate good M growth. 2. A gaseous phase containing CO_2 over 1% was necessary to stimulate M growth on agar media composed of 10^<-2>% L-proline, 10^<-2>% MgCl_2 and 10^<-2>% NaH_2PO_4. 3. When the organism was cultivated using the candle jar method on the media containing 10^<-2>% L-proline and one of the following : 10^<-2>% thioproline, 10^<-2>% L-cysteine, 10^<-1>% L-methionine or 10^<-1>% MgCl_2, good M growth was observed. The best M growth was obtained on the plate containing thioproline and L-proline. 4. Based on the results of the experiments using solid media, a TPC medium composed of 10^<-2>% thioproline (T), 10^<-2>% L-proline (P) and 10^<-2>% NaHCO_3 (C) was devised for GT formation. 74% of the cells in TPC medium developed GTs and 2% of those in PC medium (TPC medium minus thioproline) developed GTs. 5. The effective inoculum sizes for GT formation in TPC medium were under 10^5 CFU/ml. When organisms in excess of 10^6 CFU/ml were inoculated in the medium, only 20% of the organism formed GTs. 6. The following additives put on the TPC medium inoculated with 10^6 CFU/ml caused over 90% of the cells to develope GTs : 10^<-2>% sodium linoleic acid, 10^<-2>% sodium oleic acid, 10^<-2>% linolenic acid, or 1% tween 80. About 90% of the cells formed GTs in TPC medium supplemented with 10^<-2>% sodium linoleic acid (L) ; in LPC medium 2% of the cells formed GTs. 7. Substitutes for thioproline in LTPC medium were investigated. Sulfur containing amino acids (L-methionine, L-cysteine, L-cystine), metabolic intermediates, taurine, and some inorganic sulfur compounds (except Cu, Zn, Mn compounds) were effective. 8. Thioproline concentrations that accelerated GT formation in the LTPC medium ranged from 3×10^<-5>% to 3×10^<-2>%. The best GT formation was obtained in concentrations of 3×10^<-3>% to 10^<-2>%. About 90% of the cells formed GTs. However GT formation was inhibited by thioproline at 10^<-1>%. 9. The inhibition by 10^<-1>% thioproline was bacteriostatic. 10. The cells' uptake of L-proline in the LTPC medium was accelerated by 10^<-3>% thioproline. The uptake reached a maximum at 10^<-2>%, and was inhibited at 10^<-1>%.

View full abstract

Periodontitis results from the extension of the inflammatory process initiated in the gingiva to the supporting periodontal tissues, which is characterized by alveolar bone loss. To understand this bone status is needed to examine the bone dynamics of the alveolar bone involved in periodontitis. Experimental periodontitis in dogs activates remodeling in the cortex and on the surface of alveolar bone, although the bone loss occurred in periodontitis. This bone loss results from bone remodeling alteration between resorption and the succeeding formation, that is, the volume newly formed is not equal to the volume resorbed. The volume formed will depend on three variables, namely 1) the area, 2) the speed, and 3) the period of formation. The area of formation, that is, the length of osteoid surface on the alveolar bone and the number of formative osteons in the alveolar cortex, increases with inflammation. Therefore the cause of the decreased volume of newly formed bone is suggested for the dynamics of the latter two variables. This study was designed to determine the effect of experimental periodontitis on the speed of formation (the appositional rate) following resorption of the alveolar bone remodeling sequence with histomorphometry. Periodontitis was induced around the second, third and fourth premolars on the left side of the mandible in 6 male dogs by ligating a nylon floss around the teeth and into the gingival sulcus for 22 days. The right side on which ligature was not applied served as the control. Evaluation of the dynamics of appositional bone growth was facilitated by subcutaneous administration of Calcein and oxytetracycline. Administration began on Day 0 of the start of the study with the use of a schedule of 2 days on (Calcein), 8 days off, 2 days on (Calcein), 8 days off, and 2 days on (oxytetracycline). The dosage was about 10 mg/kg/day for Calcein and 20 mg/kg/day for oxytetracycline. After killing the dogs, the specimens were prepared for bone histomorphometry. Morphometric measurement was taken at the alveolar bone with the microcomputer-based system. The following measurements for alveolar cortex were made : 1) the osteoid seam thickness (OST), 2) the osteoid seam volume (OSV), 3) the circumference of osteoid seam (Sf), 4) the mineral appositional rate in microns per day in 1st half and 2nd half of the experimental period per triple labeled osteon (Mo1 and Mo2 respectively), and 5) the circumference of label per triple labeled osteon (Sl). For evalluation, several scatter diagrams were illustrated. The results were as follows : 1. OST and OSV showed significantly positive correlationship with Sf both in the inflamed and in the control side in all six dogs. 2. Mo showed significantly positive correlationship with Sl respectively in 1st half and in 2nd half of the experimental period in the inflamed side of all six dogs and in the control side except one dog whose data was insufficient. 3. In alveolar bone, the matrix appositional rate (Mf) was shown to equal Mo as in long bones, and the following relationship was found between the appositional rate (M) and the circumference of Haversian canal or osteon (S) : M=α・log S-β (α, β : constant). 4. OST and Mo2 were higher in values in the inflamed side than in the control side, and so both appositional rates, that is, Mf and Mo, were shown to increase with inflammation. 5. This increase of both appositional rates with inflammation was higher in the larger osteon, large in size earlier in the formation phase of the remodeling sequence, and was shown possibly to be the highest on the alveolar bone surface. These results suggest that the bone formation is not depressed but activated at the cellular level and the tissue level, and the activated remodeling sequence may be accelerated in the cortex and on the surface of alveolar bone in periodontitis. Alveolar bone loss would be caused by considerably shorter period of

(View PDF for the rest of the abstract.)

View full abstract

The behavior of osteomyelitis in the maxilla differs from that in the mandible radiologically and clinically. The mandibular osteomyelitis tends to be more diffuse and wide-spread lesion, but in the maxillary osteomyelitis the lesion is usually localized. In this study, the difference in radiographic findings of osteomyelitis between in the maxilla and the mandible is demonstrated by using dogs experimentally. The difference between jaw bones and the tibia is also clarified. The experimental osteomyelitis was caused by an injection of 4-Nitroquinoline-N-oxide (4NQO) into the bone marrow of the individual bones. The results obtained are as follows : 1. An experimental osteomyelitis in the individual bones was successfully caused by the application of 4NQO. 2. There were no radiographic changes in the jaw bones and the tibia one week after the injection of 4NQO. Two weeks after the injection of 4NQO, radiographic findings appeared in the maxilla, mandible, and tibia. 3. The severity of the maxillary bone destruction due to the osteomyelitis was less than that in the mandible and the tibia. The bone destruction of the maxilla did not progress with time but was localized around the 4NQO injected area. The bone destruction of the mandible and the tibia was accelerated with time, and its severity increased. 4. Osteosclerosis in the tibial osteomyelitis was more severe than in the mandible. No osteosclerosis was seen in the maxillary osteomyelitis. 5. The sequestrum formation was seen to be almost the same in the maxilla, and tibia. 6. The periosteal new bone formation occurred more frequently in the tibial osteomyelitis than in the mandibular osteomyelitis, but there was no statistical significance. The periosteal new bone formation did not develope in the maxillary osteomyelitis. 7. As the first bony changes of osteomyelitis, the bone destruction and the periosteal new bone formation occurred two weeks after 4NQO injection. Osteosclerosis and the sequestrum formation were mostly seen three or four weeks after 4NQO injection. 8. In the mandibular and tibial osteomyelitis, the lesion spread more widely with time, but in the maxillary osteomyelitis the lesion was still localized. 9. The mandibular and tibial osteomyelitis revealed more radiographic findings than the maxillary osteomyelitis.

View full abstract

Ag-Pd-Au alloy is commonly used for the cast crown and bridge. The occurrence of inner porosities, however, has often been pointed out as one of the disadvantages of this alloy. Although some reports have been issued concerning the porosities in the casting of this alloy, almost all of them have dealt with some simple shaped experimental castings such as rods or plates. However, the shape of the casting might be a primarily important factor affecting the occurrence of porosities. And the shape commonly encountered in the clinical use should be adopted as the shape of test specimens. In the present study, therefore, a frequently found clinical shape (premolar crown) was selected as the test specimen shape. Then the effects of several casting machines and conditions on the size, number and distribution of inner porosities were investigated for the premolar crown cast by usual spruing. There were significant differences in size, number and distribution of the porosities among the four casting methods employed, namely, (1) melted by gas-air flame and cast by centrifugal casting machine, (2) melted by electric furnace in carbon crucible and cast by centrifugal casting machine, (3) melted by electric furnane in carbon crucible and cast by vacuum-pressure casting machine, and (4) melted by induction heating in argon atmosphere and cast by vacuum-pressure casting machine. Large, localized porosities were found near the occlusal surface in the crown cast by centrifugal casting machine. When vacuum-pressure casting machine was used, the porosities were significantly decreased in size and number, and they distributed throughout the whole crown body. Particularly, vacuum-pressure casting combined with induction heating in argon atmosphere brought a marked reduction of porosities. In the case of centrifugal casting combined with gas-air flame melting, the inner porosities were minimized in size and number at the mold temperature of 600℃. No increasing effects of overheating the alloy up to 1, 100℃ were recognized on the porosities as long as the mold temperature was kept at 600℃. When the mold was prepared with phosphate bonded investment instead of gypsum bonded investment, the inner porosities were significantly decreased. It is suggested from this fact that the molten alloy may react with the mold wall of gypsum bonded investment more vigorously than with that of phosphate bonded one to cause more porosities at the elevated temperature. The use of flux was not so effective as ever expected to reduce the porosities in the cast crown of this alloy.

View full abstract

Untreated root canals of extracted human permanent maxillary anterior teeth were enlarged with use of reamers, K-type files, and H-type files, and the inner wall surface after instrumentation was observed with a scanning electron microscope. The results were as follows : 1. No marked differences were observed among the three uses of instruments : reamers alone, K-type files alone, and reamers, K-type files, and H-type files combined. 2. Mechanical enlarging does not result in thorough cleaning of root canals and chemical enlarging (cleaning) is required.

View full abstract

Defective speech due to velopharyngeal insufficiency occurs from various causes such as cleft palate. In determining treatment for such defects and evaluating the outcome, diagnosis of velopharyngeal insufficiency is important. Though various diagnostic methods have been reported, none seems to be objective and accurate. We have performed audiometry and hydrodynamic examination as well as electroacoustic examination. Recently, nasopharyngeal fiberscope added for comprehensive evaluation. In this study, comparison was made between the findings obtained by hydrodynamic examination and those with a nasopharyngeal fiberscope in patients with velopharyngeal insufficiency following cleft palate repair and controls, and the following results were obtained. 1. A correlation was suggested between the amount of velopharyngeal insufficiency (open area) and that of intranasal breath exhalation. These factors affected the intraoal pressure and the degree of asaphia. 2. This comprehensive method may be useful in detemining the applicability of speech aid or pharyngeal flap operation as well as evaluating outcome.

View full abstract

The widely used dental Ag-Pd-Au alloy is frequently melted with a gas-air blowtorch, and cast by a centrifugal casting machine. In this case, the timing of casting the molten alloy is generally determined by means of the observation of its appearance at melting. There are few reports on the temperature of the molten alloy at casting. Therefore, the casting temperature of Ag-Pd-Au alloy melted with a gas-air blowtorch was measured, as well as the heating time until the start of castig. This study was scheduled to examine the effects of remelting, flux addition, and operator's experience in casting. Six operators, three well and three poorly experienced, were selected. The casting temperatures adopted by the three well experienced operators tended to rise gradually as the repetition times of melting increased. The difference between the casting temperatures at the first and the 10th melting without flux ranged from 10 to 15℃. On the other hand, the casting temperatures adopted by two poorly experienced operators of the three tended to fluctuate sharply, and no rising tendencies were observed in the casting temperatures. Flux addition in due course of heating the alloy reduced the difference between the maximum and the minimum casting temperature. The rise in casting temperature was suppressed by flux addition in the repeated melting by the well experienced operator group, resulting in about only 5℃ rise from the first to the 10th melting. The time required for heating the alloy from the liquidus to the casting temperature was nearly constant in the case of the well experienced operator group, but in the case of the poorly experienced one it fluctuated sharply, irrespective of flux utilization. Consequently, it may be said that the operator's experience and/or skill are inevitably necessary for casting Ag-Pd-Au alloy by judging the casting temperature from the appearance of the molten alloy.

View full abstract

Cancer chemotherapy used in the management of neoplastic lesions is important method along with surgical therapy and radiation therapy. Anatomical functional and cosmetic considerations make chemotherapy for oral cancer more important. However, the cytocidal effect of anti-cancer agents works not only on the tumor cells but also on the normal cells and tissues, and involves rather extensive specific sideeffects because of their toxicity. For this reason attempts have been made to minimize the systemic toxicity of anti-cancer agents on normal tissues and to uptake the maximum concentration in tumor areas. Based on these ideas, Klopp et al (1950) first introduced the intra-arterial infusion of anti-cancer agents. In treating oral cancers in our department since 1964, we have been treating the therapeutic plan as a first choice, in which regional intra-arterial infusion of various anti-cancer agents through the superfacial temporal artery. Accordingly, we belive that regional intra-arterial infusion therapy is beneficial to adjuvant chemotherapy for oral cancer.

View full abstract