The follicular dental cyst (FDC) was defined as “a cyst arising by separation of the follicle from around the crown of an unerupted tooth within the jaws”. But, what causes the development of follicular dental cysts around some unerupted teeth is unknown. A few works reported that it occurred most frequently in mandibular second premolars and mentioned the possibility of injury to the permanent tooth dental germ by endodontic treatment of deciduous teeth in childhood.
To elucidate the pathogenesis of FDC, the authors investigated 11 cases of FDC in children with special regard to the clinical and radiographic findings and to the inflammatory changes of cyst fluids by biochemical analysis, including the studies on the generation of superoxide (O₂^-), SOD activity, free radicals and leukotorienes in cyst fluids.
Clinical and radiographic findings revealed that the root apex of pulp-treated deciduous teeth contacted with cyst walls in 8 cases. Anaerobic bacteria were identified in 8 cases. Neutrophils separated from cyst fluid showed the same O₂^-production ability as those separated from peripheral blood of patients. SOD activity and free radical intensity of cyst fluid varied with the clinical findings of inflammation. Leukotorienes, migration mediator of leukocytes, were detected by HPLC in cyst fluid. Therefore, it was useful for improving inflammatory symptoms to treat FDC with the solvent of radical scavengers replacing the cyst fluid.
These results suggested that the periapical lesion of a deciduous tooth mainly caused the pathogenesis and enlargement of the follicular dental cyst in children.

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We have previously reported that sensitivity to various antitumor drugs on squamous carcinoma cells is different from that on adenocarcinoma cells.Furthermore, the difference is well correlated with the ability of the cells to incorporate drugs by passive transport. These results suggest the possibility that the accumulation of the drug was closely associated with lipid composition and/or conformation which is thought to be an important factor to determine hydrophobicity of the cell membrane.
Generally, serum-contained medium was used to study lipid metabolism in cultured cells. Since lipid metabolism is dependent upon the presence of external lipoproteins, we have studied lipid metabolism of normal epithelial and cancer cells in serum-free culture to evaluate intrinsic lipid metabolism in the cells.
[2-¹⁴C] acetate was incorporated almost exclusively into phospholipids in oral epithelial cells cultured in a low calcium medium. However when the concentration of calcium was changed from 0.03 mM to 1.12mM to induce terminal differentiation of the cell, a definite amount of radioactive acetate was incorporated into free cholesterol and incorporation into phospholipids was decreased. The extent of the incorporation into free cholesterol was increased at least until 48 hrs after inducing differentiation and the ratio of free cholesterol over phospholipids were constantly increased in this period, indicating that accumulation of free cholesterol is concomitant with the differentiation of the cell.Furthermore, it may be suggested that the ratio of free cholesterol over phospholipid could be an indicator for terminal differentiation of epithelial cells.Squamous cell carcinoma cells which showed a decreased capacity to differentiate exhibited increased incorporation into phospholipids and decreased incorporation into neutral lipids. On the other hand, adenocarcinoma cells showed marked differences in lipid metabolism compared to squamous carcinoma cells, i.e., increased incorporation into neutral lipids and decreased incorporation into phospholipids.
From the results obtained, it is clear that a close relationship exists between lipid metabolism and the ability of cells to differentiate. Furthermore, it may be suggested that hydrophobicity of the cell membrane in squamous carcinoma cells might be higher than that in adenocarcinoma cells.

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Natural Killer (NK) and lymphokine-activated killer (LAK) activity as well as surface markers of peripheral blood lymphocytes (PBL) in head and neck cancer patients are investigated with regard to the prognosis of patients.Patients (n=31) were grouped as follows:(1) untreated (UT) group (n=29), (2) treated, disease-free (TDF) group (n=21), and (3) group with recurrent disease (RD;n=6).NK and LAK activities were assayed by ⁵¹ Cr release method using K-562 cells in NK assay or Daudi cells in LAK assay as targets. Also LAK induction rate from PBL by interleukin-2 (IL-2) was measured.Analysis of surface markers of PBL (Leu 2, Leu 3, Leu 4, Leu 7, Leu 11, HLA-DR, and M1) including two color analysis (Leu 4×HLA-DR, Leu 2×Leu 15, Leu 3×Leu 8, and Leu 7×Leu 11) were performed using flow cytometry system.
NK activity (P<0.01) or LAK induction rate (P<0.01) in the TDF group was significantly increased as compared with the UT group.LAK activity in PBL without IL-2 treatment were not statistically different among TDF, RD, and UT groups.In the study of surface markers of PBL, a significant decrease in the percentage of Leu3⁺ (P<0.01) or Leu 3⁺8⁺ (P<0.01) cells, and significant increase in the percentage of HLA-DR⁺ (P<0.01), Leu 4⁺HLA-DR⁺ (P<0.05), or Leu 3⁺8^- (P<0.05) cells in TDF group were observed as compared with each corresponding immunologial parameter in the UT group.In the RD group, the percentage of Leu 3⁺ (P<0.001) or Leu 4⁺ (P<0.05) cells was significantly decreased and the percentage of HLA-DR⁺ (P<0.01), Leu 7⁺ (P<0.05), Leu 11⁺ (P<0.05), or Leu 2⁺15⁺ (P<0.05) cells was significantly increased, when compared with the UT group.However, the difference between each pair of UT, TDF and RD groups with regard to the percentage of M1⁺, Leu 7⁺11^-, Leu 7⁺11⁺, or Leu 7^-11⁺cells in PBL was not significant.

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The surgical correction of secondary dentofacial deformities associated with cleft palate, in some cases, encounter problems such as difficulty in positioning of osteotomized maxillary bony segments, postoperative relapse with unstable maxillary segments especially in the case of palatal expansion.Alleviation of tension in palatal soft tissue and bone grafting into the cleft alveolus and palate are believed to be essential in solving these problems.
Experimental models with cleft alveolus and palate were produced surgically in adult Macaca fuscata monkeys, and these defects were repaired with mucoperiosteal flap.Repeated elevations of mucoperiosteum were performed in creating the cleft alveolus and palate, repairing them, and grafting of autologous cortico-cancellous bone block into the bony clefts.Bone healing was studied for up to 6 months using contactmicroangiography, fluorescence microscopic and histologic examination.
Results of these clinically analogous studies indicate that the remodeling procedure of grafted cortico-cancellous bone block is obviously delayed in surgically damaged palatal side. In addition, differences in bone healing were recognized by the recipient site and depending on the grafting fashion.

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Predominant bacteria isolated from 21 cases of odontogenic infection were identified and examined for β-lactanlase, DNase, hyaluronidase, chondroitin sulfatase, lipase, lecithinase, collagenase, trypsin, chymotrypsin and plasmin activities.Pus was aspirated, immediately inserted into RTF under a stream of anaerobic gas, sealed tightly with a butyl gum stopper and transferred to the laboratory. The sample was serially diluted and smeared on blood agar plates in duplicate. One plate was incubated anaerobically for 7 days and another aerobically for 4-7 days.Bacteria were isolated in all cases and the standard number of isolates was 9.2×10⁸ CFU/ml.Anaerobic bacteria predominated in 20 of the 21 cases yielding positive culture.In anaerobic bacteria, gram negative rods were predominant, especially species of Bacteroides (45.6%) were isolated from 20 of the 21 cases, followed by species of Peptostreptococcus (23.8%) and Streptococcus (9.0%).B.intermedius (18.8%), Ps.productus (7.6%), Ps.micros (5.3%), S.mitior (4.4%) and B.gingivalis (4.3%) were identified as major constituents.
All cases contained various bacteria producing different enzymes at high percentages. Enzymes most often detected included β-lactamase (100%), DNase (87.5%), hyalurcnidase and chondroitin sulfatase (81.3%), lipase (81.0%), lecithinase (71.4%) and collagenase (68.8%).B.iltermedius was predominant as β-lactamase, DNase, hyaluronidase, chondroitin sulfatase, lipase, and lecithinase producer.While, B.gingivalis was predominant as collagenase, trypsin chymotrypsin and plasmin producer.
These results indicate that hydrolyticenzyme-active B.interrrtedius and B.gingitalis may exert important influences upon the exacerbation of odontogenic infection.

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Hydroxyapatite cement (HAP cement) and fibrin glue were evaluated as a delivery system of bone morphogenetic protein (BMP) in terms of roentogenographic and histological method.Semipurrified BMP was prepared from bovine bones according to Urist's method, and the BMP showing bioassay was provided as a material.
5 mg of BMP mixed with 20 mg of HAP cement or 0.2 ml of fibrin glue was implanted into ICR mouse thigh muscle, and post-survival rates were 3, 5, 7, 14, 21 and 28 days.
Chondroid matrix existed in the HAP-BMP implanted area on day 14 post operation, osteoid tissue on day 21, and endochondral ossification on day 28.In the newly formed chondro-osseous tissue, the particles of HAP cement still remained.On the contrary, mixture of BMP-fibrin glue resulted in the formation of connective tissue without finding any evidence of bone tissue formation.
From the results of the present study, the author evaluated that HAP cement is a useful material as a BMP delivery system.

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We have developed a pure titanium mandibular head cap and applied it to the orthopedic site of the mandibular head in condyloplasty and arthroplasty.It is shaped to cover the mandibular head so that natural head form and structure can be restored when the cap is worn and stabilized.In addition, this mandibular head cap has tiny holes in its margin to accomodate the expected bone infiltration and has holes for screws at the parietolateral part so that it can be secured with bone-marrow screws that match the mandibular head and neck.The titanium cap comes in three sizes-large, medium, and small-that can be chosen according to the size of the mandibular head.
The surgical procedure involving this titanium mandibular head cap follows condyloplasty. The coarse surfaces and bony lumps of the mandibular head are ground and eliminated with a surgical bur.Next, the cap is placed on the mandibular head to be stabilized diagnally or vertically with screws.In some cases, the articular tubercle is removed to facilitate forward movement of the mandibular head.
In our practice, this procedure was indicated for temporomandibular arthrosis that was unresponsive to longterm conservative therapy (disc displacement without reduction), temporomandibular arthrosis deformans, and ankylosis of the temporomandibular joint.This paper primarily addresses, in summary, the procedures and application methods.

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The etiology was investigated on 141 patients with temporomandibular dysfunction under 19 years old who visited our clinic for 3 years from January 1987 to December 1989 in order to investigate the etiology.The results were as follows:
1.The patients less than 20 years old occupied 21.3% of the total patients.
2.The incidence remarkably increased on the patients over 15 who amounted to 76.6% of the subjects.
3.Type III accompanied with the displaced disc was seen most frequently (86.6%) in the classification of the TMJ dysfunction and this percentage was greater than that of all type III patients in our clinic.Furthermore, all patients, of 33 the cases, under 15 years old were type III.
4.The frequency of the intermittent closed lock was dominant in comparison to that seen in the total patients of or clinic.
5.There was the tendency that younger patients with the displaced disc, especially with intermittent closed lock didn't have pain in the TMJ or masticatory muscles.
6.Remarkable bone changes in the condylar head were observed in 4 cases.

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Ultrasonography (US), computed tomography (CT), sialography and CT-sialography were performed on 25 patients with parotid gland tumor.Diagnostic images were compared to assess their respective roles in the investigation of parotid masses to determine the most appropriate diagnostic approach.
Twenty-five patients with a total of 26 lesions were included in the study and ranged in age from 28 to 75 years (mean, 51.5 years).US was performed in 25 of the patients, CT in 22, sialography in 23, and CT sialography in 13 patients.US examinations were obtained with real-time scanning using 5-MHz, 7.5-MHz and 10-MHz transducers (Toshiba SAL-30 A and Aloka SSD-125).CT was obtained using a Toshiba TCT-60A.All tumors were surgically explored and histological diagnosis was obtained for 26 lesions (23 benign, three malignant). US and CT proved equally effective in demonstrating parotid masses and predicating malignancy.These proved to be especially superior to sialography for demonstration of the tumor in most cases.As to the border, margin and shape of the tumor, examination by US and CT showed mostly similar appearances, but the internal findings of the tumor delineated by US were more coincidental with the surgical specimen than were those by CT.CT helped in establishing the relationship of the tumor mass to the facial nerve (81%).
CT is most useful in assessing the position of the tumor in the deep lobe, medial side of the ramus on the mandible and the extraglandular spread of the tumor.Indication for CTsialography was limited to those cases in which the tumor was unclear on plain CT.Sialography was inferior to US and CT in the detection of parotid tumor.US was a reliable diagnostic method for detection of mass lesions in the parotid gland.The author therefore recommends US as the initial investigatory method for evaluating parotid masses.

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