Hemophilia is a hereditary condition in which one of the normal blood clotting factors is absent. This sex-linked, recessive disease, transmitted by the female and expressed in some of her male offspring, is characterized by significantly delayed coagulation times and by the tendency to hemorrhage. On the dental treatment especially, surgical procedure, appropriate methods of hemorrhage control are required. These methods are replacement therapy, antifibrinolytic agents, and local hemostatic methods. In this case, we successfully extract residual roots of hemophiliac patient without eccessive post operative bleeding using replacement therapy and surgical splint.

본 실험은 삼차신경 자극으로 발생되는 체성 감각 유발 전위에 대한 국소마취제의 효과를 관찰하였다. 나트륨 통로차단을 통하여 약리작용을 나타내는 것으로 알려져 있는 리도카인를 뇌 피질에 국소 투여한 후 삼차신경의 체성 감각유발 전위의 강도및 지연시간을 측정하였다. 케타민으로 마취된 흰쥐의 대측성 구레나룻 자극후 뇌의 체성 감각영역으로부터 기록되는 유발전위를 분석한 결과, 리도카인을 뇌 피질에 국소 투여시 유발전위의 강도 및 지연시간의 감소가 나타났으며, 필드 전위의 형태는 이상성 (양극성 및 음극성) 혹은 삼상성 (양극성, 음극성 및 양극성) 의 파형으로 나타났다. 필드 전위의 발생 부위는 뇌 피질의 중대뇌동맥의 상행지 상방영역이었다. 본 실험에서 나타난 초기 전위변동은 피질판 상층에 존재하는 신경세포의 탈분극 과청에 의하여 생성되고 후기의 전위 변동은 동일 영역의 하층 신경세포에서 과분극 혹은 재분극이 발생한 결과라고 유추된다. 따라서 삼차신경계의 체성 감각 영역에서는 피질 상층및 하층의 과립성 피라미드 세포의 순차적인 활성화에 의하여 기본적인 신경 회로망이 형성되어 있으며 생리적 자극으로 유발되는 필드 전위는 이러한 신경망를 통하여 발생될 것으로 사료된다.

본 증례의 혈우병 및 자폐증 환아의 치료를 통해 다음과 같은 결론을 얻었다. 1. 혈우병 환자의 내원시 내과의사나 소아과의사 및 혈액학자에게 의뢰를하여 출혈찬도 및 부족인자 보충 퉁에 관한 자문을 얻어야 한다. 2. 매우심한중증의 혈우병 환자이거나 외과적 수술등으로 인해 많은 출혈이 예상될 경우에는 포괄적인 환자 관리를위해 입원 치료를 해주어야 한다. 3. 자폐중으로인한 행동조절이 어렵거나 그외 다른 요인에 의해 행동조절이 불가능한 혈우병 환자의 경우 입원치료가 필요하다. 4. 치과 시술을 행할때에는 최소의 관혈적인 치과치료 행하도록 노력해야 하며, 응급 상황을 대비해서 국소적인 지혈방법을 습득해야 한다. 5. 치과 시술시 환자의 동통 완화 및 소염작용을 위한 약물 처치시에도 주의를 요한다. Non-steroidal anti-inflammatory drugs는 혈소판응집을 방해하기 때문에 동통완화를 위해서는 aspirin 대신에 acetaminophen을 사용하며, 소염효과를 위해서는 steroid 계통의 약물을 사용하며 ibuprofen, indomethacin, phenylbutazone 등의 약제 사용은 금한다. 6. 혈우병 환자라고해서 두려워하거나 치과 치료의 질을 변경해서는 안된다.

저자는 전반적인 치아우식증을 주소로 개인 의원에서 경희대학교병원 소아치과에 의뢰된 10세 여아에서 Robinow syndrome 의 드문 증례의 치료를 시행하고 문헌을 고찰하여 다 음과 같은 결론을 얻었다. 1. 전신소견으로 전두부 돌출, 양안격리, 넓은 안검렬, 들창코 등을 보이는 태아모습의 특정적 안모와 작은키, 짧은 팔, 굽은 손가락, 생식기의 미발육 등이 관찰되었고 전반적인 발육지연이 있었다. 2. 구내소견으로 치아우식, 치아총생, 구개수의 미발육, 수술받은 구개열, 구호흡이 관찰되었다. 3. 이 증후군에서 드물게 보여지는 정신지체, 청각장애, 삼출성 중이염을 동반하였다. 4. 가족력은 발견할수 없었다. 5. 전신마취하에 전반척인 치과치료와 이비인후과치료를 함께 시행하였다. 6. Robinow 증후군은 여러 합병증을 수반할 수 있으므로 타과와의 협력하에 전반적인 검사를 시행하고 포괄적인 협력진료가 요구된다.

Laser is getting more attention from increasing numbers of dental clinicians by its own several unique characteristics : precision, hemostasis, and bactericidal capacity. It also provides patients with several advantages of minimal tissue damage. faster healing with less postoperative pain and minimal use of local anesthetics. Labial or lingual frenectomies were performed successfully in three pediatric patients using Nd-YAG laser. When compared to the conventional scalpel method, less local anesthetics were needed and the bleeding control was so excellent that any suture was not necessary. The operation sites were completely healed without any infection or complication and discomfort from swelling or pain was not noted in all cases throughout the healing process.

Face mask is an extraoral appliance which used to protract maxilla, and can help in the correction of moderately severe class IlI malocclusions by the anterior displacement of the maxilla and maxillary dentition, and possibly restricting or changing the direction of the growth of the mandible. In three cases the results were followed. 1. Anterior crossbite was corrected 2. Maxilla & maxillary dentition were displaced forwardly. 3. Lingual tipping of the mandibular incisors, and backward & downward rotation of mandible were performed. 4. Acceptable improvement in the class III profile was performed.

Anterior openbite is defined as the lack of contacts between the functional occluding teeth on vertical line at centric occlusion and classified into functional and skeletal anterior openbite based on its causes and characteristics. Anterior openbite causes masticatory, speech, and esthetic problems in the growing children and difficulties in diagnosis, treatment, and the prediction of its prognosis. We are reporting on the treatment of anterior openbite in the growing children and the results follow as : 1. In the growing children with anterior openbite, the overbite could be increased by the treatment according to its causes and characteristics. 2. The prognosis is not determined by the presence or severity of oral habit but the skeletal tendency of the patient.

Electrosurgical technique have been used in dentistry as an aid to soft tissue management for nearly 60 years. However, it was not until the late 1960s that the principles of electrosurgery were understood and improved equipment became available. Electrosurgery is a surgical procedure performed on soft tissue utilizing controlled high frequency electricaI(radio-frequency) currents in the range of 1,500,000 to 7,500,000 cyclesper second. The radio-frequency energy used in electrosurgery is able to cut and coagulate tissue because it focuses the energy at the small, active electrode. Advantages of electrosurgery for soft-tissue management during dental procedures include improved hemostasis, ease of tissue modification, improved visibility and so on, but adverse healing responses-including necrosis of soft tissue and sequestration of alveolar bone-have been reported. The present report provides examples of treatment of soft tissue and pulp tissue of primary teeth by electrosurgery. The results are as follows; 1. Electrosurgical techniques can be used for various procedures in pedodontics. 2. Electrosurgical procedures provide improved hemostasis and visibility in the operating field, which enable to remove, reshape, and contour soft tissues easily. 3. In pulpotomy technique, it was difficult to expect the variable pulpal response based on the degree of heat accumulation and the conditions of pulp tissues. Therefore, electrosurgical pulpotomy could not be considered as a method superior to formocresol pulpotomy. 4. A greater degree of dexterity and experiences in manipulation of the electrode is required compared with the conventional scalpel surgery.

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

The treatment of complete avulsed teeth due to traumatic injuries is replantation procedure. The major complication of replantation are pulp necrosis, ankylosis, and root resorption. It is important to maintain the vitality of periodontal ligament to minimize the complications. The purpose of this case report is to consider the facts that affect the success rate and the prognosis of complete avulsed teeth after replantation. All of these cases had different conditions and transport media. The following results were observed: 1. The successive treatment of complete ayulsed teeth requires the maintainance of vitality of periodontal ligament. 2. The complication of replantation are inflammatory root resorption and ankylosis and in such case, proper endodontic treatment using calcium hydroxide medications and periodic observations are needed. 3. In case of delayed replantation, the use of fluoride and root planning procedure can help to achieve better result. 4. It is more esthetic and functional to maintain the avulsed tooth in mouth.

The prevalence of class III malocclusion is approximately 5$\sim$9%, and about one fourth of this malocclusion is due to underdeveloped maxilla. Maxillary protraction appliance is an orthopedic device which promote the growth of a deficient maxilla by applying extraoral force to actively growing patients. The object of using maxillary protraction appliance is to guide a normal growth of maxilla and mandible and improve the occlusal relationship and also improve the facial profile. The author treated three patients whom were diagnosed as a class III malocclusion due to deficient maxilla using maxillary protraction appliance and the followings are the conclusions : 1. In these cases, anterior crossbite was corrected by anterior movement of maxilla and downward backward rotation of mandible and simultaneously, anterior facial height was increased. 2. The amount of dental change compare to skeletal change was greater as the patients got older. 3. When 500gm of force to each side was applied, the treatment period has been decreased. 4. As a result of applying the force between maxillary first primary molar and canine, there was a small degree of changes in palatal plane. So, it can be concluded that the maxillary protraction appliance is effective in treating growing patients with a deficient maxilla.

The peripheral odontogenic fibroma (WHO type) is a relatively rare and characteristically benign and unencapsulated, exophytic gingival mass of fibrous connective. Odontogenic epithelium is found within the gingival mass, but usually appears to playa minor role when compared to the fibrous component. The connective tissue is ranged from markedly cellular to relatively acellular and well collagenized. but the connective tissue in this case report appears less cellular. Peripheral odontogenic fibroma must be differentiated histologically from peripheral ossifying fibroma, Peripheral cemental epithelial odontogenic tumor and Peripheral ameloblastoma. The author reports the following conclusions after clinical and radiological examination, excisional biopsy and reviewing literatures. 1. Peripheral odontogenic fibroma is rare lesion and frequently occurs in interdental papila as a form of fibroblastic connective tissue including odontogenic epithelium within the lesion. 2. Peripheral odontogenic fibroma must be differentially diagnosed with Peripheral ossifying fibroma by including less cellular connective tissue, odontogenic epithelium and dysplastic dentin 3. Treatment consists of surgical excision including removal of alveolar bone which is eroded under the lesion

Surgical removal of impacted mesiodens can be performed easily when exact position of mesiodens is identified. This case report is argued about methodological approach of exact antero-posterior postioning of mesiodens using conventional cross-sectional occlusal film and periapical film. The author concludes, 1. Among various methods of positioning mesiodens, exact position of mesiodens can be determined with occlusal film and periapical film. 2. On operation, exact antero-posterior position of mesiodens can be determined with comparing occlusal images of adjacent teeth and anatomic structure to real ones. 3. It is important that exact removal course of mesiodens has to be determined in addition to exact determination of one's position, and that it has to be determined in regard to position, morphological basis, direction of impacted pattern of mesiodens and adjacent anatomic structure. 4. In 2 cases presented, both are mesiodens of inverted conical type, and impacted direction are class I and III respectively according to classification author suggested, and surgery can be perfomed with ease by different approach directions.

Garre's osteomyelitis is a unique form of osteomyelitis characterized rediographically by localized thickening of the periosteum and deposition of laminated subperiosteal bone. The most common inciting factor is a mandibular infection in permanent first molar with necrotic pulp. This disease occurs primarily in children and to date in all instances it has occured only in mandible. It usually results in hard swelling over the jaws, producing facial asymmetry with little or no pain. The overlying skin is normal but can occasionally be inflammed mostly when pain is present. Palpation reveals a usually smooth, bone-hard lesion which feel like an inherent part of the mandible. Unlike other forms of osteomyelitis, there is no marked increase in fever, white bloods cell count, sedimentation rate or alkaline phosphatase value. The treatment of Garre's osteomyelitis usually consist of elimination of the sourses of infection, i.e., either extration of an offending infected teeth or root canal therapy. This treatment almost always results in resolution of the Garre's osteomyelitis. Resistant cases have involved secondary surgery, i.e., decortication and sequestrectomy. This report presents three cases of Garre's osteomyelitis resolved by endodontic treatment. Cliniqtl examination revealed swelling on the face with no tenderness. Periapical radiograph showed deep caries lesion extending into pulp chamber and periapical radiolucency. Occlusal radiograph showed an enlargement of bone and stretching the periosteum. A clinical diagnosis of the Garre's osteomyelitis was made. Endodontic treatment was accomplished with conventional method and restored facial symmetry. Long-term check-ups are necessary to evaluate the results of endodontic treatment.

Ankyloglossia, or tongue-tie, is a congenital condition which occurs as a result of fusion between the tongue and the floor of the mouth. Ankyloglossia often results in malocclusion with an anterior "open bite" deformity, early prognathism, swallowing problem, speech disorder, and periodontal problem. Generally lingual frenectomy is used for treatment of ankyloglossia, but incomplete operation and simple frenectomy may produce a scar contracture resulting in a more deformed ankyloglossia than was present initially. The Z-plasty is used for the correction of scar contractures and the replacement of missing tissue and this procedure is ideally suited for the treatment of an ankylosed frenum. Most authors advise postponement of any decision for surgical correction of tongue-tie until the age of 4 years, unless the child is having much difficulty with sucking or swallowing. We treated 4 patients with ankyloglossia using Z-plasty technique. As a result, we found out that it was effective for correction of movement limitation of tongue, prevention of relapse. Further, periodic check ups are needed for evaluation of relapse, improvement of speech, and other functions of the tongue.

The purpose of this study was to investigate. the effects of the lactation of human or bovine milk and the method of using nursing bottles on the salivary invertase test scores and deciduous caries experience of children. 328 preschool children (boys 178, girls 150) in Iksan city were selected for this study. The parents of the children were asked to answer the questionnaire about the lactation of human or bovine milk and the time of using nursing bottles. The data were obtained from the salvary invertase activity score,(Resazurin Disc Test) deciduous caries experience and the questionnaire. The result were as follows. The invertase activity and caries experience of the human milk higher than that of the bovine milk group(P<0.05). There were significant positive relationships between the lactation period and the invertase activity and between the lactation period and the caries experience(P<0.05). Caries experience had a tendency to increase as the time of using nursing bottles increase (P>0.05).

The effects of electro-acupuncture on the pain threshold and the amplitude of dEMG(di-gastric EMG) evoked by the noxious electric stimulation on teeth and gingiva in dogs were studied. Experiments were carried out with 10 dogs weighing 5-8kg. Each animal was anestheticed with Entobar given intraperitoneally in an initial dose of 30mg/kg. Maintenance dose of 5mg/kg/hr was given through a cannula, in the femoral vein, as required to keep up light anesthesia. Bipolar stimulating wire electrodes, 0.1mm in diameter, insulated except for tips, were inserted into the upper canine and palatal gingiva. Rectangular aluminium plate electrodes (15$\times$5mm) were placed on acupuncture points, called Yin-Hsiang, located at both sides of the upper jaw. Rectangular biphasic current pulses of 2Hz, with a $250{\mu}sec$ duration, were delivered for 15 minutes. The dEMG activities were recorded from the anterior belly of the digastric muscle(one of the jaw opening muscles) using bipolar wire electrodes. The magnitude of the jaw opening reflex at different intensties of electro-acupuncture(1volt 4volt and 10volt) was estimated by averaging the 30 superimposed dEMGs recorded on an oscilloscope and audiomonitor. Data were analysed statistically with ANOV A and paired t-test. The obtained results were as follows: 1. Pain thresholds were increased 7.7 %, 15.4 %, 17.3 % in the teeth and 11.1 %, 19.0 %, 25.4 % in the gingiva as the intensities of electro-acupuncture increased incrementally. 2. Amplitudes of dEMG were decreaed 8.3%, 22.4%, 27.4% in the teeth and 9.8%, 36.5%, 42.2 % in the gingiva as the intensities of electro-acupuncture increased incrementally. 3. Inhibition of pain responses by the electroacupuncture was more effective in the gingiva than in the teeth.

Cleft lip and palate is the most common malformation in the craniofacial region. The patients with cleft lip and palate have functional problem such as, speech, feeding and respiratory as well as esthetic problem. So, treatment should be done by multidiciplinary team approach. The role of pediatric dentist in the team is advicement for feeding method, guidance of normal growth, caries control and preventive orthodontics. In cleft lip and palate patients, maxillary arch after cheiloplasty is usually collapsed by excessive tension of the scar. This collapse increase the difficulty of later orthodontic treatment. Therefore, the maxillary arch segments should be moved and retaind to normal position as soon as cheiloplasty is done to reduce the need and difficulty of orthodontic treatment. This concept is called by the early orthopedic treatment in cleft lip and palate. Also, this orthopedic appliance works as feeding applince to normal feeding and weight gain We reported two cases of early orthopedic treatment with favorable result in complete bilateral cleft lip and palate patients after cheiloplasty. Patients showed normal weight and their maxillary arch widths were increased.

The conventional treatment of skeletal Class III malocclusion has been focused on application of orthopedic force primarily to the mandible. However, In Class III malocclusion with retrograde position or underdevelopment of Maxilla, this approach is not suitable treatment. These patients need an application of orthopedic forces via face-mask to the Maxilla to stimulate its growth and to change the direction of growth. In skeletal Class III patients who were treated by Face-Mask, the following results were obtained. 1. Forward growth of Maxilla was enhanced. 2. Labioversion of upper incisors and linguoversion of lower incisors were observed. 3. Mandible was rotated to clockwise direction and remodeling of B point was observed. 4. Anterior crossbite was corrected by combining of the above results.

An alternative design to conventional class II cavity preparation for proximal carious lesions is the tunnel preparation. It preserves the marginal ridge intact, thus making it possible to maintain the natural contact relationship with the adjacent tooth and minimize tooth reduction. This in vitro study was purposed to evaluate the effect of the materials' elastic constants and shear-bond strength on the marginal ridge fracture resistance of teeth restored by the tunnel technique, and to find the materials of choice for tunnel restorations. $Resinomer^{(R)}$, $Ketac-silver^{(R)}$, $Miracle-Mix^{(R)}$, and Tytin were used as restorative material. The elastic constants of each restorative material were evaluated by ultrasonic pulse measurement. Young's modulus and bulk modulus of the restorative materials were evaluated in three specimens for each material type. The shear-bond strength of the restorative materials to the dentin surface was measured after thermocycling 400 times between 6 and $60^{\circ}C$, using ten specimens for each material type. For measuring marginal ridge strength, 60 sound extracted molar teeth were distributed into six groups by size. Sound molar teeth were used as a Control group and unfilled prepared teeth were grouped as Unrestored. Another four groups were named Resinomer group, Ketac-Silver group, Miracle Mix group, and Tytin group by type of restorative material. Tunnel cavity preparation was done with ' 1/2, 2, and 4 round burs in sequence. Initial access to proximal surface was made through an occlusal access preparation started at least 2mm from the marginal ridge, and the proximal opening was formed about 2.5mm below the marginal ridge. After restoration and thermocycling, marginal ridge strength was measured using a universal testing machine. The results were as follows: 1. The Young's modulus of $Tytin^{(R)}$ was 63.95 GPa, followed by $Ketac-Silver^{(R)}$ 27.60 GPa, $Miracle-mix^{(R)}$ 18.48 GPa, and $Resinomer^{(R)}$ 10.74 GPa showing significant differences between the groups(P<0.05). The bulk modulus of the materials showed the same order as Young's modulus. The value of $Tytin^{(R)}$ showed 59.57 GPa indicating that it will deform less than other materials under the same stress. It was followed by $Ketac-Silver^{(R)}$ 23.57 GPa, Miracle $Mix^{(R)}$ 12.50 GPa, and $Resinomer^{(R)}$ 11.60 GPa. 2. The Resinomer group had a shear-bond strength of 7.41 MPa which was significantly higher than those of the Ketac-Silver group (1.80 MPa) and the Miracle Mix group (2.84 MPa) (P<0.01). All the specimens of Tytin group detatched from the dentin surface during thermocycling. 3. The mean marginal ridge strength of the Unrestored group(46.14 kgf) was significantly lower than that of the Control group (84.24 kgf) (P<0.01). The marginal ridge strength of teeth restored by the tunnel technique was, in order, Ketac-Silver group 74.06 kgf, Miracle Mix group 73.36 kgf, Resinomer group 63.47 kgf, and Tytin group 58.76 kgf. The Ketac-Silver, Miracle Mix, and Resinomer groups showed no significant difference with the Control group (P>0.05), but the Tytin group showed significantly lower strength compared to the Control group(P<0.05). The results showed that the marginal ridge strength of the teeth restored by the tunnel technique was not significantly lower than that of sound teeth. They also demonstrated that the bonding strength of the restorative material to the tooth surface should be high and the modulus of elasticity should not be lower than that of the tooth in order to restore the marginal ridge strength to its natural condition.

The mutan containing $\alpha$-1,3 bond is an insoluble portion of glucan which is the main component of dental plaque. The secretion of mutanase was assessed with mutan-digesting Streptomyces isolated from soil, and the factors affecting its activity was studied, obtaining the following result. Mutan-digesting Streptomyces was identified as Streptomyces exfoliatus by its characteristics. The effect of dextranase was identified on the media containing blue dextran. A clear zone was produced by Streptomyces exfoliatus on the media containing blue mutan, so showing the secretion of mutanase. A clear zone was significantly produced on the media overlayed with agar containing blue mutan. A clear zone was produced at 2 days after the inoculation of Streptomyces exfoliatus on the media containing below a concentration of 0.025% glucose, at 3 days on the media containing 0.05 % glucose, and at 4 days on the media containing 0.1 % glucose. Mutan-digestion wasn't appeared early by adding other carbohydrates. The higher concentration of peptone, the later appearance of clear zone was on the media containing below a concentration of 0.1 % peptone. These results indicated that the secretion of mutanase was identified from mutan-digesting Streptomyces on the media containing blue mutan, and a clear zone was appeared lately on the media containing higher amount of glucose.