• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.3
• /
• pp.453-458
• /
• 2004

Mandibular fracture is less common in children than in adults. However, children are more susceptible to ankylosis and developmental disorders, and don't respond as well to intermaxillary fixation compared to adults. On the other hand, bone fracture is healed more quickly in children and complications are scarce. Mandibular fracture in children is usually treated successfully with acrylic splint therapy with or without the use of eyelet wires and intermaxillary fixation. Severe complications that include ankylosis and developmental disorders may occur. The frequency and severity of such complications can be mitigated with a shorter duration of intermaxillary fixation and good post-operative care. Encouraging mandibular physical therapy by increasing patient motivation may be necessary in such cases where the patient's response is poor and the duration of intermaxillary fixation increases; when the patient is unable to undergo physical therapy, or when intermaxillary fixation is not necessary with the patient showing only minor symptoms such as trismus. In this case report, a 6 year-old girl with bilateral condylar fracture was treated with elastic in both the upper and lower jaws to allow mandibular physical therapy using a Benoist's appliance, which allows opening, lateral, and protrusive retrusive movements of the mandible. A 7-month follow-up showed beneficial therapeutic effects such as increased mandibular movement and prevention of condylar ankylosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.30 no.1
• /
• pp.49-55
• /
• 2004

The management of mandibular condylar fractures in children has long been a matter of controversy. The fracture, if not treated appropriately, may result in complications such as disturbance of mandibular growth and temporomandibular joint ankylosis. They are usually treated nonsurgically, which has been proved to be satisfactory in the long term results. Nineteen children with 25 condylar fractures experienced during their growth period (age at trauma from 10 months to 12 years, mean 7.0 years) were studied. All patients were treated by arch bars and intermaxillary fixation for $7{\sim}14$ days. They have been evaluated with clinical and radiographic examination. The maximum mouth opening and lateral movement of the mandible were within normal limits. There was no malocclusion or ankylosis. Beginning of remodelling was evident at postoperative $1{\sim}3$ months. Remodelling of the condyle was good in 21, while partial adjustment occured in the other 4 condyles. These results suggest that the conservative treatment of condylar fractures in growing children results in good functional results and good remodelling of the condyle.

• The korean journal of orthodontics
• /
• v.19 no.2
• /
• pp.37-55
• /
• 1989

The tissue reactions concerned in alveolar bone remodelling at the pressure zones of rat molar periodontium associated with the application of force (15 gm) to the maxillary first molar teeth of the albino rats were studied by the transmission electron microscopy. Osteoclasts referrable to bone resorption were observed thereafter 3 hour survival period and undermining resorption was generated thenceforth 2 day survival period. Bone resorption, reversal zone and new bone formation were simultaneously observed adjacent to the zone of undermining resorption in the 7 day survival period. Osteoclasts with well developed primary lysosome, ruffled border, clear zone, granules and Golgi apparatus were detected at the zone of the bone resorption, and dark and bright cells adjacent to the osteoclasts as well. Mononuclear cells and perpendicularly arranged collagenous fibers were observed in the reversal zone and, on the other hand, osteoblasts with well developed Golgi apparatus and rough endoplasmic reticulum were detected at the zone of bone formation.

• The korean journal of orthodontics
• /
• v.33 no.4 s.99
• /
• pp.279-291
• /
• 2003

Electric current is a highly probable way as a clinical tool for tooth movement. The purposes of this study were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to investigate the effects of electric-orthodontic treatment on the remodeling of the periodontal tissue histologically The study was performed with six male cats weighing around 3kg. The electric device wich is providing the direct electric current of $20{\mu}A$ was inserted to the removable appliance. The right and left maxillary canines were assigned as control and experimental sides respectively. The control canine was Provided with orthodontic force (75gm) oかy and the experimental side was given the same amount of force and electricity. The lingual buttons were bonded to the maxillary canines and both sides of canines were retracted with NiTi coil spring. The electric device was adjusted to provide 20uh direct current to the experimental canines S hours a day The amount of the canine movement was measured with electronic caliper every week. After 4 weeks of tooth movement, the animals were sacrificed and the histologic study was performed. The results of this study were as follows. 1. The application of a direct current to the experimental tooth significantly increased the final amount of orthodontic tooth movement. The amount of tooth movement after 28-day was 37% more in the experimental side. 2. The electrically stimulated tooth showed histologic evidence of significant increases in the amount of bones and matrix deposition in the area of tension. 3. In the compression side, the electric-orthodontic treatment stimulated bone resorption more extensively in the experimental canines. 4. After 28 days of electricity exposure and orthodontic force, the experimental side demonstrated significantly more osteoblasts, osteoclasts, capillaries and osteoid tissues, reflectinr an increase in the local tissue's cellular activity. 5. Intermittent electrical stimulation (five hours a day) had effects to enhance orthodontic tooth movement and tissue remodeling. These results suggested that the low-intensity exogenous electric current by the miniature electric device might accelerate orthodontic tooth movement and bone remodeling in vivo and have the possibility to reduce the orthodontic treatment duration.

• Journal of dental hygiene science
• /
• v.13 no.2
• /
• pp.158-164
• /
• 2013

The most frequently encountered problems at fixture-implantation sites are lack of adequate bone and proximity to anatomic structures. It is generally accepted that growth factors play an essential role in the healing process and tissue formation, and they have become the focus of grafting materials research. The granules in platelets contain high concentrations of various growth factors. In particular, platelet-rich fibrin (PRF) is a second-generation platelet concentrate that allows the production of fibrin membranes enriched with platelets and growth factors from an anticoagulant-free blood harvest. This study investigated the in vitro effects of PRF on osteoblasts, in terms of the key cellular functions, and especially the effects on two growth factors, the homodimer of platelet-derived growth factor subunit B (BPDGF-BB) and transforming growth factor (TGF)-${\beta}1$, which are associated with wound healing and regeneration (i.e., proliferation and differentiation). The following parameters were investigated: PDGF-BB and TGF-${\beta}1$ levels in PRF, cell viability, alkaline phosphatase (ALP) activity, type 1 collagen synthesis, and the expressions of osteoblast differentiation markers (ALP and runt-related transcription factor 2) and bone matrix proteins (type 1 collagen). The release of autologous growth factors from PRF was maintained for a reasonable period of time, and exerted positive effects on the proliferation and differentiation of osteoblasts. The use of PRF thus appears to be a promising method for enhancing bone healing and remodeling.

• The korean journal of orthodontics
• /
• v.23 no.2 s.41
• /
• pp.229-248
• /
• 1993

[ $Interferon-\gamma$ ] has been suggested as a cytokine of connective tissue stabilizer. In addition, it has also been demonstrated that this cytokine inhibited bone remodeling activities of the bone derived cells. In order to illuminate the effects of this cytokine in orthodontic force induced bone remodeling, it was administered to primary cultured periodontal ligament cells which have been known to have some osteoblast like characteristics. $Interferon-\gamma$ slightly decreased $[^3H]thymidine$ incorporation rate without a significant change in the total cellular DNA content up to 1000 U/ml, which meant these doses were not cytotoxic to the cell. Total protein synthesis was not influenced by various concentration of interferon-y whether it was determined by the $[^3H]proline$ incorporation rate or by the Lowry smethod. The effect of $interferon-\gamma$ on the individual protein was, however, differential, ie, it increased $[^3H]proline$ incorporation into the noncollagenous protein marginally, while it decreased $[^3H]proline$ incorporation into the collagen, so that it caused dose-dependent suppression of the relative collagen synthesis. On the contrary, the fibronectin synthesis determined by the ELISA was increased by 1000 U/ml of $interferon-\gamma$. The differential effects of the interferon-y on the collagen and fibronectin synthesis exhibited not only their protein level but also the steady state mRNA level. $Interferon-\gamma$ decreased steady state level of ${\alpha}1(I)$ procollagen mRNA significantly, while showing no significant changes in the fibronectin mRNA level. In addition to this, it was also found that indomethacin did not affect on the $interferon-\gamma$ induced collagen decrease in this cell, which meant prostaglandins were not involed in the process of $interferon-\gamma$ induced collagen decrease. So it can be concluded that the incubation of periodontal ligament cells with 1000 U/ml of $interferon-\gamma$ for 24 hr showed differential effects on the type I collagen and fibronectin gene expression. The decrease in relative collagen synthesis in the protein level was related with decrease in the steady state level of mRNA, while the increase in the fibronectin synthesis in the protein level was not correlated with the mRNA level.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.4
• /
• pp.619-624
• /
• 2009

Pyknodysostosis(PKND) is a rare sclerosing bone disorder that has an autosomal recessive trait, also known as Toulouse-Lautrec syndrome. Deficiency of the cathepsin enzyme K in the osteoclasts of PKND patients results in continuous endosteal bone deposits without osteoclastic resorption or remodeling. This causes a generalized increase in sclerosis and fragility of bones. Osteomyelitis in the mandible and recurrent fracture of the long bones are characteristic complicatons of PKND. The patients present typical features of PKND, such as short stature under 150 cm, open cranial suture and fontanelle, club-shaped phalanges, and underdevelopment of midface. This is a case of a 7-year-old girl with PKND, who visited our clinic with the chief complaint of anterior Open-bite and generalized crowding. The patient had been diagnosed as PKND by an orthopedist and manifested characteristic clinical and radiographic features, such as open cranial suture and fontanelle, obtuse madibular gonial angle, frontal and occipital bossing, grooved palate, club-shaped phalanges, and short stature. Orthodontic treatment was not considered because patients with PKND show abnormal bone resorption and remodeling. Instead, removal of deciduous teeth near exfoliation and TFA were performed, and periodic check-up is planned to maintain good oral hygiene.

• The korean journal of orthodontics
• /
• v.30 no.3 s.80
• /
• pp.317-333
• /
• 2000

The purpose of this study was to determine the proliferative activity of the osteoblasts and fibroblasts in the midpalatal area and to investigate the adjacent periodontal tissues of individual tooth following rapid expansion of the palate. Ten young adult dogs, aged approximately ten months, were used in the experiment. The experimental design was consisted of 1 week expansion group(Group E1, 3 dogs), 2 week expansion group(Group E2, 3 dogs), 2 week expansion and 2 week retention group(Group E3, 3 dogs), and control group(Group C, 1 dog). For each group, expansion screw was activated one time per day(1/4 turn;$90^{\circ}$) following Hyrax-screw application. The experimental animals in each group were sacrificed at 1, 2 and 4 weeks following palatal expansion. Maxillary tissue blocks were obtained and prepared ior the histomorphologic and immunohistochemical studies. Light mcroscope, polarizing microscope, and soft X-ray apparatus were used in this study, and following results were obtained. 1. In polarizing microscopic study, the expansion groups(E1 & E2) showed blue color representing bone resorption and new bone formation in midpalatal suture area. E3 groups skewed less blue color compared to the E1 and E2 group. But yellow color increased by calcification in the E3 groups. 2. Immunohistochemical study revealed that positive responses of the osteoblasts to PCNA and undifferentiated fibroblasts to EGF in E1 group were somewhat increased. Positive response to PCNA and EGF were increased in fibroblasts and the osteoblasts forming new bone in E2 group. In E3 group, the positive response cell concentrated the periphery of edge of palatal process in both PCNA and EGF. 3. Throughout the expansion period(E1 & E2), light microscopic study showed the edges of the extensive resorption and new palatal processes, indicating bone remodeling within the suture. E3 group exhibited less remodeling of midpalatal suture area. E2 group and E3 group showed cementum formation and resorption at the apex of 3rd premolar and 1st molar E3 group exhibited extensive hyalinized zone on the cervical portion of buccal side of 1st molar. 4. Soft X-ray analysis of E1 group showed hypomineralized defect and microfractures in various parts of the suture areas when compared with control animals. There was no significant difference in the degree of mineralization in the midpalatal suture region between the C and E3 groups. Tooth axis showed tipping of 3rd premolar and 1st molar in the E2 group and E3 group. Based upon these experimental results, it is concluded that the undifferentiated mesenchymal cells always presented in midpalatal suture area following RPE. Differentiated osteoblasts and fibroblasts possess proliferating cellular activity until the 2 week retention period. The posterior teeth are tend to tip buccally as RPE force applied. Retention group exhibited irreversible response with severe hyalinized zone on the buccal surface of the first molar.

• The korean journal of orthodontics
• /
• v.28 no.1 s.66
• /
• pp.85-97
• /
• 1998

The purpose of this study was to observe the effects of sodium fluoride on the bony repair and regeneration processes after the rapid palatal expansion in the growing dogs. Eighteen dogs were divided into experimental and control groups. They were in the late mixed dentition. The rapid Palatal expansion was undertaken in all the animals($180^{\circ}$ turn/day) for ten days. The animals were sacrificed on 0, 15 and 45 days after the finish of expansion. One mg NaF/kg of body weight/day were given orally to the experimental group. Blood samples were drawn before and after expansion and the se겨m calcium, phosphate and alkaline phosphatase level were measured. The undecalcified bone section of midpalatal suture area was made, and observed under the light microscopy The results were as follows ; 1. The day after expansion, the infiltration of inflammatory cells were prominent and the new bone formation started at the edges of the two palatal plates bodering the midpalatal suture in both groups. Especially, the newly formed osteoid were very extensive and the osteoblasts lining the osteoid were very active in the experimental group. 2. At fifteen days after expansion, the active osteoblasts lining the osteold at the surface of trabecular bony spicules and active new bone formation were observed in the both groups. However, the cellular activity and new bone formation were more prominent In the experimental group. 3. At forty five days after expansion, the continuous osteoid and new bone formation and active osteoblasts were observed in the experimental group. But these phenomena were not observed in the control group. In the control group, the numerous osteoclasts were adjacent midpalatal suture and the bony remodeling process was begun. The serum alkaline phosphatase level was maintained highly in the experimental group, but decreased in the control. According to the above results, the author reached the conclusion that sodium fluoride has the stimulation effects on the osteoid production of the osteoblasts during the healing process after the rapid Palatal expansion more continuously.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.2
• /
• pp.376-381
• /
• 2008

In mixed dentition there exists many empty spaces in the arch due to eruption of permanent teeth and exfoliation of primary teeth. The empty spaces makes it difficult to apply fixed orthodontic appliances. Horseshoe Appliance can be used effectively at this stage, holding the whole dentition in one piece. It covers every surface of erupted teeth and prevents extrusion and rotation of single tooth. By using intermaxillary elastic force, remodeling of the alveolar bone is opposite in each arch. In patients who were treated with horseshoe appliance, forward growth of maxilla, labioversion of maxillary incisors and linguoversion of mandibular incisors were obtained. Minimum downward and clockwise rotation of mandible was shown, so increasing anterior facial height was minimized.