The shape and size of the bevel-preparing burs which had been designed before by us were improved so that the placement of the round or straight bevel would be done more uniformly and better on the margin of the composite resin cavity. Extracted human primary anterior teeth were used as materials in this study because the condition of the experiment, such as the shape and size of the cavity and bevel, had to be as uniform as possible.
The cavities with round bevel, straight bevel and butt joint were prepared on the labial surface of the experimental teeth. Light cured posterior composite resin was used for composite restoration. And the collision test reproducing the stress of mastication and occlusion was carried out by using the collision-andabrasion test machine. Next, the relationship between marginal sealing effect and the marginal form of the cavity was examined using the dye penetration test.
Further, the replica models of the experimental teeth taken before and after the collision test were examined with the scanning electron microscope. Furthermore, especially the margin of composites was observed to examine the appearance of marginal fracture.
The following results were obtained.
1. The improved bevel-preparing burs showed better performability for occlusal cavities on primary posterior teeth, especially when used for preparing round bevels.
2. The marginal sealing effect was significantly different among the three types of marginal form. The round bevel showed the most exellent results, followed by the straight bevel. And the butt joint had the lowest marginal sealing ability.
3. No obvious marginal fracture or gap formation was observed at the interference between the composite resin and the tooth material.
4. It was indicated that micro-gap may be formed between the composite resin and the tooth material by the stress of mastication or occlusion before the marginal fracture causes.

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The aims of this study were to estimate the needs of guidance in regard to dietary habits (mainly in the case of an unbalance dietary habits), and now nutritional conditions and dietary habits are related to dental health care problems of autism and autistic children by comparing between the dietary status of autistic children and that of ordinary children.
As subjects of the study of autism and autistic children, there were sixty two autism and autistic children comprised of fifty four boys and eight girls.
The results obtained were as follows:
1. From the data of a taste trends, it was found that the favorite foods of autistic children were fish and flesh, and the food most disliked was vegetables. The 25favorite foods of autistic children for snacks were juice and milk products.
2. From an evaluation in regard to an unbalanced diet in the case of autistic children rated CLAC II, the foods with a statistically significant difference in an energy intake corresponding to the existence of an unbalance diet were milk, oils and fats. Also the law of causality between the existence of an unbalanced diet and the fixation of autistic children was not included.
3. There was no statistically significant difference between autistic children and ordinary children in the area of the total nutritionally sufficient a rate. According to a dietary classification, the nutritionally sufficient rate for autistic children was higher with a statestically significant difference in regard to fish and flesh compared with the rate of ordinary children, and was lower with a statistically significant difference in regard to vegetable and milk products.
4. An autistic children ingested very hard food compared with ordinary children with respect to food consistency.
5. There was no statistically significant difference between autistic children and ordinary children in regard to the total ingestive points and the ingestive points in the dietary classification of snacks. The dietary habits of ordinary children for snacks (the intake frequency, regularity, the amount of intake per time) improved from five years of age, while the habits of autistic children deteriorated.
6. There was a high correlation between the status of dental caries and sugar intake. There was also a statistically significance difference between autistic children and ordinary children in regard to the time of intake and the food consistency containing sugar (beverage and others), In the case of children with a high sugar intake along with beverages at meals, there were more autistic children compared with ordinary children, and in the case of snacks, there were more ordinary children compared with autistic children.
7. From the mass evaluation, a nutritional unbalance was found in the dietary habits of autistic child, but it was not found that the unbalance influenced the the systemic condition. Also the dietary habits in relation to dental health care were good.

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The purpose of this study was to investigate the influence of the ground depths of the enamel and etching times on the adhesion of the resin on the ground enamel.
Seventy-five extracted and frozen bovine mandibular young permanent incisors were used. The etchant used in this study was 37% phospholic acid gel and the etching times were 0,10,20,30 and 60 seconds. All of the specimens were washed with an air water spray after etching. The bonding agent and composite resin used in this study were Dual Cured Scotch Bond and Silux (3M Co. ). Shear bond strengths to the outer enamel layers and the inner enamel layers of the same teeth were measured. After the shear bond strength test, all the test surfaces of the enamel and resin specimens were observed using the SEM. The results of this study were compared with the previous results using Photo Bond and Photo Clearfil A (Kurary Co. ).
1) The etching time which showed the highest bond strength was 60 seconds on th outer and inner enamel layers(45.13±5.11 MPa,45.37±6.73 MPa).
2) For the same etching times, the bond strengths between the outer enamel layers and the inner enamel layers showed no significant differences.
3) When the enamel was etched, for all of the etching times, the bond strengths were significantly higher than those of the enamel without etching on the outer and inner enamel layers.
4) The bond strength with 60 seconds of etching time was significantly higher than those with 20 and 30 seconds of etching times on the outer and inner enamel layers.
5) Such a tendency toward a higher bond strength was observed in cases which showed resin widely adhered on the enamel surface.
6) The bond strengths of Silux were significantly higher than those of Photo Clearfil A with 10 and 60 seconds of etching times, and the bond strength of Photo Clearfil A was significantly higher than those of Silux without etching on the outer and inner enamel layers.

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The suspectibility of enamel to caries is greatest immediately after the eruption of teeth and decreases in later years. This well-known changes is widely attributed to the post-eruptive maturation of the teeth, but the mechanism of the maturation is yet to be clarified. This study, part of a study done to identify of the mechanism, examined the in vitro effects on inorganic parts of the enamel of repeated acid treatment during maturation. Experiments were conducted on powered synthetic hydroxyapatite containing carbonate and on blocks of human enamel.
1) With the powder, crystallinity was improved more when acid treatment was added to demineralization. The reaction proceeded mostly along the C-axis. Frequent repetition of short demineralization cycles minimized the decrease in crystal size and improved the crystallinity.
2) With the human enamel, the use of repeated 30-sec demineralization cycles during remineralization improved the crystallinity and the acid resistance. Repeated 30-min demineralization cycles caused substantial defects in the enamel.
The results suggested that the frequent repetition of slight demineralization improves the crystallinity and acid resistance and greatly influence the post-eruptive maturation of the inorganig part of the enamel.

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In humans the volume of saliva induced reflexly by taste stimulation varies markedly, depending on the nature of the stimulus. Of the four basic taste stimuli (acid, salt, sweet and bitter), acid is by far the most potent even when the subjective intensities of the four stimuli are equal. Most studies on the salivary flow rate in humans have been carried out using adult subjects but there is little information about salivary secretion in children. The purpose of the present study was to determine the unstimulated whole salivary flow rate and the optimum concentration of acid necessary to elicit the maximal whole salivary flow rate in children.
The subjects were 20 boys and 20 girls, aged 5 years, and the studies were carried out at about 1: 00 pm, at least 1 h. after the last meal.1% citric acid was infused into the mouth through a plastic tube, at a rate of exactly 5. Oml/min, by means of a peristaltic pump. The subjects spat out the acid and any saliva into a weighed container about every 10 sec. The volume accumulated in the 1 min. minus the 5. O ml of infused acid, was regarded as the stimulated flow rate of saliva. After a rest period of a few minutes, this was repeated with 3% and then 5% citric acid.
The salivary flow rates were expressed both as ml/min and as a percentage of that in response to 5% citric acid since, in all 40 subjects, the 5% citric acid elicited the highest flow rate(4.25±1.38ml/min). There were no differences in flow rate due to gender and the mean flow rate elicited 1% and 3% citric acid were 2.34±1.11ml/min,57.1±18.0% and 3.18±1.03ml/min,79.6±12.0%, respectively. The mean flow rates with the different concentrations of citric acid ranged between 50 and 60 percent when expressed as a percentage of those reported for adults.

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The Present study was made to clarify the effects of lactic acid and acetic acid and/or those of a mixture of both acids at different retios. For this purpose synthetic hydroxyapatite powder and blocks of human enamel were prepared and exposed to five types of solutions containing lactic acid alone, lactic acid and acetic acid mixed at the ratios of 3: 1,1: 1, and 1: 3, and acetic acid alone. These solutions were adjusted to five different levels of pH; 4.0,4.5,5.0,5.5, and 6.0, with potassium hydroxide. Final acid concentration of these solutions was adjusted to 500 mM. The dissociated ions were examined with an atomic absorption spectrophotometer [AA-670, Shimadzu] and characteristic demineralization was examined with microradiographs [Softex CMR, Nippon softex], SEM [ JFC-1100, TEOL], and polarizingmicroscope [POH, Nikon].
The following results were obtained:
1) With mixtures of lactic acid and acetic acid, the demineralization of the enamel block was deeper when the pH was lower as well as when the ratio of lactic acid became higher.
2) At the same pH level, the extent of enamel demineralization was more limited when the ratio of acetic acid was higher.
3) As far as the amount of dissolution of calcium with synthetic apatite powder is concerned, the mixtures of the two acids showed more enchanced dissolution than those of single acids.
4) Consequently, it may be suggested that the demineralization of enamel was affected and modified not merely by pH level of an acid, but also by the mixture of organic acids.

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A histopathological study was attempted in order to investigate the pulpal response to diammine silver fluoride.
Cavity preparation was performed on 103 healthy permanent teeth of mongrel dogs with an air turbine and a carbide-bar with water spray. The specimens were divided into 2 groups. In the experimental group,0.01 ml 38% diammine silver fluoride (Ag(NH3)2F) solution was applied on the dentin for 3 minutes after the cavity preparation. In the control group, nothing was applied on dentin. All the dentin cavities of these groups were left open to the oral environment without any restoration.
The specimens were processed for histopathological evaluation at 3,7 and 30 days. The teeth were fixed in 10% neutral buffered formalin, embedded in celloidin, serially sectioned through the pulp and stained with hematoxylin and eosin.
The following observations were obtained.
1. Various histopathological changes such as necrosis, suppurative inflammation, round cell infiltration, bleeding, hyperemia, atrophy and vacuolization of pulps, and atrophy, loss and separation on odontoblastic layers, and destruction of predentin were observed in the experimental group and the control group. Apposition of dentin on the pulp chamber wall was observed in 11 cases (61.1%) out of 18 cases in the experimental group and in 7 cases (63.6%) out of 11cases in the control group of 30 days specimens.
2. In the experimental group, there was a 75% success ratio, a 20% fairly success raito and a 5% failure ratio in 3 day specimens, and a 73.9% success ratio, a 26.1 % fairly success ratio and a no failure ratio in 7 day specimens, and a 66.7% success ratio, a 22.2% fairly success ratio and a 11.1 % failure ratio in 30 days specimens.
3. In the control group, there was a 60% success ratio, a 26.7% fairly success ratio and a 13.3% failure ratio in 3 day specimens, and a 75% success ratio, a 25% fairly success ratio and a no failure ratio in 7 day specimens, and a 72.7% success ratio, a 18.2 % fairly success ratio and a 9.1 % failure ratio in 30 days specimens.
4. The above histopathological evaluations showed no significant differences between the experimental group and the control group.
5. There was no relation between the depth of silver particles included in Ag-(NH3)2F into dentinal tubles and the histopathological observations and evaluations.
6. Application of 38% Ag(NH3)2F did not show any protective efficacy to dental pulp.

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The present study was made to investigate the acid resistance, fluoride uptake and crystallinity of the enamel fissure after sealing with glass ionomer cement (Fuji ionomer Type III, G-C, Co. ). Acquired acid resistance of the enamel was assessed either by calcium dissolution or by the depth of the artificial caries lesion formed on the enamel, which had been sealed with glass ionomer cement. Uptake of fluoride into the enamel was evaluated by using an X-ray microanalyzer and by using an X-ray microbeam diffraction system, the crystallinity was evaluated. The results showed that glass ionomer cement sealing was unexpectedly effective on the enamel peripheral area of the sealing as well as underneath the sealing. Uptake of fluoride was noticed to depth of 20-30μm both in the underneath and peripheral area of enamel. The crystallinity of the enamel underneath the sealing was improved in the direction of a-axis, but was less with the c-axis. While, at the peripheral enamel, the crystallinities were improved both in the direction of the a-axis and c-axis, these results suggested that sealing with glass ionomer cement improves the crystallinity of both the underneath and peripheral enamel substance. Hence it provides an acid resistance nature for the enamel.

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We had previously reported that mastication plays an important role in the development of salivary glands and that the insufficient growth of the submandibular gland have an effect on the proliferation of other tissue in male mice. Submandibular glands contains an epidermal growth factor (EGF) which has a marked biological action both in vivo and in vitro, influencing proliferation, differentiation of various types of cells.
In this study, we examined the effects of mastication on the activity of EGF in the submandibular glands.
The experiment was done with two groups of male mice, a control group fed a solid diet, and the experimental group fed a paste diet after 3 reaching weeks of age. The activity of the EGF was assayed by the increase of DNA synthesis of the cells derived from the root resorption tissue of human deciduous teeth. Also a histological examination of the submandibular glands was carried out.
In the group fed the paste diet, the activity of the EGF was lower and the number of acinar cells with the granules which produce the EGF were fewer than that in the control group.
These results suggested that mastication has an effect on the differentiation of the acinar cells with granules and the EGF content in the submandibular glands, and it is involved in the systemic development.

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The purpose of this study was to ascertain the changing of the mandibular movement according to the development in children and the factors governing the sliding movement.
The subjects consisted of 33 children with normal occlusion and were divided into 3 groups, the IIA, III A and IV A stage of Hellman's dental stage.
The incisal path of the mandibular movement and the inclination angle of the occlusal facets of the maxillary teeth guiding the sliding movement were examined.
The results obtained were as follows:
1) Based on the progress of Hellman's dental stage, the range of mandibular movement was enlarged towards the exterior, anterior, inferior and posterior while the deviations of the maximal opening position, maximal protruded occlusal position and maximal lateral occlusal positions decreased.
2) Based on the progress of Hellman's dental stage, the inclination angle of the paths of the protrusive and lateral sliding movements tended to be steep.
3) The tooth that guided the lateral sliding movement most frequently for the maxillary teeth on the working side was the milk canine in stage II A and III A, the canine in stage IV A, and on the balancing side that was the second milk molar in stage II A, the second milk molar and first molar in stage III A, the first molar in stage IV A. The tooth that guided the protrusive sliding movement most frequently for the maxillary teeth was the central milk incisor in stage II A, and the central incisor in stage III A and IV A.
4) Based on the progress of Hellman's dental stage, the inclination angle of the occlusal facets of the maxillary teeth guiding the sliding movements tended to be steep.
5) The difference between the right and left of the changing of the inclination angle of the paths of the lateral sliding movements corresponding to the progress of Hellman's dental stage was caused by the difference between the right and left of the changing of the inclination angle of the occlusal facets of the maxillary teeth guiding the lateral sliding movements.
6) In the 3 and 4 mm lateral positions of the mandible from the intercupsal position high positive correlations were found between the inclination angle of the paths of the lateral sliding movements and the inclination angle of the occlusal facets of the maxillary teeth guiding the lateral sliding movements.

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The purpose of this study was to investigate the relationship between the feeding behavior, the biting pressure, and the masticatory efficiency for 3,4 and 5year old children.
69 healthy 3,4 and 5 year old children who had normal occlusion and were caries free. They were the subject of this study.
A questionnaire directed to nursery attendant who took care of them and gave them luncheon daily was chosen for investigating the feeding behavior of these children.
The results obtained were as follows.
1) The biting pressure and masticatory efficiency of children whose feeding behavior involved keeping food in their mouth and having an unbalanced diet often were low.
2) Children having very low levels of biting pressure and masticatory efficiency were not able to eat some kinds of food which required a greater muscular activity.
3) Children whose feeding behavior did not involve biting food enough, wanting to eat only soft food and having unbalanced diet often were not able to eat some kinds of food which require a greater muscular activity.

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Histopathological examinations of deciduous teeth from patients with hypophophatemic vitamin D-resistant rickets (HVDRR) were performed by means of a transmitted light microscope and contact microradiography. Structural deformities of HVDRR teeth were recognized as follows;
1) The HVDRR enamel and mantle dentin showed apparently normal morphology.
2) Numerous microscopic abnormalities were found in the HVDRR dentin, such as multiple occurrence of interglobular dentin, a wide predentin zone and tubular defects from pulp to dentin-enamel junction. The degree of occurrence of interglobular dentin was more severe in the familial HVDRR male tooth than in the familial HVDRR female tooth.
3) The formation of reparative dentin was observed at the pulp horn of HVDRR teeth which had been subjected to attrition at the corresponing dentin side.
4) The wide “rachitic predentin” stained with Sudan black B was recognized at the pulp side of HVDRR tooth.

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Cerebral palsy (C. P. ) involves motor dysfunction in the central nervous system. This often leads to various oral malfunctions including problems with phonation and speech. It is also important for us to analyze the aspects of masticatory muscle movements with regard to the eating function in patients with cerebral palsy.
This study examined masticatory activity, the amounts of masticatory muscle electromyograph (EMG) activity showing the EMG integrated volume.
The subjects were 10 Spastic C. P. patients (average age,16 y 2m) and 10 normal controls (average age,18 y 4m). Using 4 materially different chewing substances. chewing rhythm and muscle EMG activity for the musculus masseter and musculus temporalis anterior, average means of related muscle activities per stroke were examined.
Results:
1) As for the chewing rhythm, the duration and cycle of Spastic C. P. lasted significantly longer than in the normal controls for all of the foods.
2) As for the chewing rhythm, the coefficient of variation of apples showed the smallest values in each subject group.
3) As for muscle EMG activity, Spastic C. P. was significantly higher than in the normal controls for all of the foods.
4) As for muscle EMG activity, there were significant differences for each food in each subject group.

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The developmental change in the occlusal contacts is one of the very important aspects, involved in clarifying the development of occlusal functions in children.
The purpose of this study was to improve the procedure for measuring the number of the occlusal contacts, the occlusal contact area, and the extent of occlusal force in growing children.
Pressure detecting sheets called “Occlusal Prescale” are produced by Fuji Photo Film Co.. The device to measure this consisted of light source, stereomicroscope, T. V. camera, image analyzer with 256 grades of density, and main computer.
To improve the accuracy for measuring the several variables related to the occlusal contacts, the following results were found to be important:
1. Measurement should be started at least 60 minutes after the devices were switched on.
2. The transmitted light, cross type, was the best way of illuminating the specimen.
3. The occlusal prescale should be laid at the center of the measuring field.
4. The third degree polynominal regression equation was the most useful califor estimating the pressure from the color density of occlusal prescales.
5. An attention was paid to the conditions at collection, preservation, and measurement of occlusal prescales. The coefficients of variation for the multiple measurements on the identical specimens under the above conditions were not more than 0.002 for the occlusal contact area and the degree of occlusal force. The occlusal contact area and the degree of the occlusal force were repeatedly measured on the samples consisting of three adults and three children to estimate the reproducibility. The coefficients of variation for both variables were not more than 0.08 in both the adult and child subjects. It could be stated that the measuring system of the occlusal contacts developed in this study might be useful enough to be applied in children.

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A gross salivary calculus was removed non-surgically from the orifice of the duct of a submandibular gland of a severely handicapped woman, and was investigated histologically as well as morphologically.
The surface observation of the calculus was carried out using stereo-microscopy and scanning electron microscopy (SEM).
The calculus was then cut longitudinaly, and the cut surface was observed using stereo-microscopy, radiographs, and SEM. Also, the chemical components of the calculus were analyzed using an X-ray micro analyzer (XMA).
The results obtained were as follows:
1. The form of the calculus was club-shaped, and the size was 22mm×7mm. The dry weight was 0.627 g.
2. SEM observation of the calculus surface revealed a porous structure with numerous protrusions, and its regional specific structure was not observed.
3. Stereo-microscopic observation of the cut surface revealed a centric core located in one third from the distal end of the calculus. Also the centric core was surrounded by a relatively homogenous stratiform structure. The superficial layer of the calculus showed a rather spherical structure.
4. Based on the radiographic observation of the cut surface, it was found that the structure consists of a centric core, a stratiform structure and a superficial layer, corresponded to the stereo-microscopic findings.
5. SEM observation of the cut surface revealed that the stratiform structure was crystalitic and with a relatively regular arrangement similar to the annual ring of a tree, while the superficial layer was squamous with an irregular arrangement. However, under a high magnification, ultrastructural difference was not observed, suggesting the difference in the structures might be due to the difference in growing process of the calculus.
6. XMA analysis of the chemical component of the calculus showed predominant peaks of P and Ca, and line profile analysis indicated that the general component might be calcium phosphate salt.

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The out-patient surgery unit system, with which children can be treated under general anesthesia and go home on the same day without being admitted, started at Kobe Children's Hospital in April 1985. In our Clinic of Pedodontics,99children were treated under this system from April 1985 through March 1989, and no severe complications have arisen far.
The treatments performed during this period included caries treatment (77cases), impacted tooth extraction (10 cases), mucocele extripation (7 cases), lingua frenumectomy (3 cases) and labium maxillare frenumectomy (2 cases). The reasons for using this out-patient surgery unit system were mental retardation (58cases), minor oral surgery (22 cases) and difficult young children (19 cases). Their ages encompased the primary dental stage (53 cases), the mixed dental stage (39cases) and the permanent dental stage (7 cases). This system provide advantages such as reduction of the stress that may otherwise be caused to the patient and his family, and elimination of intro-hospital infection, etc.
This out-patient surgery unit system should not be used just for the provider's convenience, and it must be used only to performed the dental treatment smoothly and safety taking into consideration both, the mental procedure, the cooperation from other departments such as Anesthesiology & Pediatrics, Clinical Laboratories etc., is essential.

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Craniometaphyseal dysplasia is a rare disorder of the bone charactarized by widening of the metaphysis of the long bone, and thickening of the cranial vault and base, facial bones and mandible. Craniometaphyseal dysplasia is distinguished from the familial metaphyseal dysplasia (Pyle's disease) by the severity of the skull involvement. We are reporting here on the case of a 7 year and 2 month old girl and are including a detailed description of the oral findings. The chief complaint by the patient was abnormal tenacity of the deciduous teeth and delayed eruption of the permanent teeth.
The oral findings of this case are summarized as follows:
1) Hypertelorism was evident as well as a broad flat nose.
2) Increased opacity of the skull, especially in the mastoid, maxilla and some parts of the mandible, as well as lack of pneumatization of maxillary sinus and mastoid air space were noted.
3) Based on the cephalometric analysis, the height of maxilla, and madible, and depth of cranial base, and maxilla were larger than normal.
4) Delayed resorption of the deciduous teeth and delayed development of the permanent tooth germs were significant.
5) The occlusion was with a deep overbite and a buccal cross bite.
6) The impaction of the permanent teeth such as lateral incisors, canines, bicuspids in lower jaws, and upper 2nd bicuspids was suspected.

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Crouzon's syndorome is a disease which presents the three symptoms of (1)craniostosis, (2) hypoplasia of the middle face, and (3) exopthalmus. This report presents the systemic and dental findings concerning a 5-year-6-month-old girl with Crouzon's syndorome whom we encountered in our practice.
1) The patient was the first child of a 26-year-old woman and weighed 2,080 g when born during the 34th week of pregnancy.
2) The family included the parents and a younger sister, all of whom where healthy and had no notable abnormalities.
3) The following findings were noted in the patient:
(1) The child was deaf.
(2) No abnormalities were observed in the hair or skin, and, the eyes were slightly protruded, altough otherwise normal.
(3) The middle region of the face was not fully developed, and the patient had a "parrot's beak" nose and short upper lip.
(4) Clinical tests showed a high level of serum phosphorus and alkaline phosphatase, indicating the possibility of osteopathosis. No particular abnormalities were noted in the other blood, urine, and chromosomal tests.
(5) The cephalometoric radiograph showed conical and several fingerlike indentations in the bone. Underdevelopment of the maxilla and anterioinferior development of the mandible were observed. The patient had poor facial development, presenting a long lower face. Deformation of the mandible was also observed.
(6) The patient had 20 primary teeth. Examination of the occlusion showed an anterior open bite, mesial deviation of the mandible in the molar region, and a narrow mandibular arch. The patient had a high palate.
(7) All of the permanent tooth buds up to the second molars were observed in panoramic and dental radiographs, and the calcification age was judged to be 5 years and 4 months.

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We investigated the effects of flunitrazepam in intravenous sedation in pedodontics.
Twenty three children who were extremery uncooperative during treatment of dental caries, and seven children having major invasine surgical treatment, paticipated in this study.
We observed the relationship between the cooperation of the patients and this method of sedation with respect to the body movementand the details of dental treatment, and also studied the situation of complaints during and after surgery.
1) In order to obtain a better sedative situation, the average dose of flunitrazepam required for children was 2-4 times higher than the dose for adults.
2) The higher average dose was for children in the lower age group who received caries treatment. The higher mean age group received surgical treatment and a sufficient sedative effect was obtained with a relatively smaller dose than in the group receiving caries treatment.
3) It was suggested that both their cooperation and understanding of dental treatment were related to the dose administered.
4) No findings on the disturbances in circulatory kinetics or in respiration were obtained during the surgery, and when postoperative control was sufficient questionable complaints were not observed.
5) Memories of discomfort during and after the surgery did not remain, so that this method is suggested as being useful for the behavior control of cooperative children.

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The patient had been having dental check ups periodically since she was three years old, and at twelve years of age she complained of pain in TMJ of right side and the restriction of mouth opening (ca.29.5 mm). A bite plane splint was placed to relieve the masticatory muscles and TMJ as a first measure. After the pain was relieved occlusal adjustment and reconstruction were performed.
By refering to three cast models which were obtained four years before TMJ problems occured, it was thought conceivable that the causes of the TMJ dysfunction in this case could be related to the changes of occlusion, due to the eruption of the second molar of the left side and resultant premature contact between upper and lower first molars of the left side.

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To find out the cause of TMJ arthrosis commencing at an early age, the difference between 8 adult subjects who had TMJ arthrosis commencing in their lower teens (group A) and 13 adult subjects who had TMJ arthrosis occuring after 20years of age (group B) was analysed by means of oral examination with their plaster models of dentition and theircephalograms.
Also the cases of a 27 year old patient who had TMJ arthrosis commencing in her lowteens and of an 11 year old patient who had TMJ clicking were shown.
1. In both group A and B, their occlusion showed less than 40% of Angle class I.
2. The ratio of subjects who had all eight teeth with centric stops at 7,654 4,567was only 50.0% in group A and 38.5% in group B.
3. The ratio of subjects who had a suitable guide in lateral jaw movement was 0% in group A and only 15.4% in group B.
4. In group A, the ramus height of the man dible was apparently inferior to those of group B and the gonial angle was apparently larger than group B.5. There was no significant difference between group AB in the basal archlength and in the basal arch width.
5. There was no significant difference between group A and B in the basal archlength and in the basal arch width.
6. There was no significantldy difference between group A and B in the arch length discrepancy. Based on these results, it was shown that the subjects who had TMJ arthrosis commencing at an early age clearly had a smaller ramus height and a larger gonial angle than the subjects who had TMJ arthrosis occuring after 20 years of age, and had very probably malocculusion and an unsuitable guide in lateral jaw movement.
Through the treatment of the two cases, the effects of the splint and the occlusal reconstruction were evident.

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