• Journal of Periodontal and Implant Science
• /
• v.24 no.3
• /
• pp.633-648
• /
• 1994

Synthetic bone graft materials have been used for the regeneration of periodontal tissue lost due to periodontal disease, but the limitations of these materials had prompted the use of composite grafts. Among those, a composite graft of calcium carbonate(CC) and calcium sulfate(CS) is one of those materials that has not been studied extensively. CC, which is extracted from a natural coral, is known to possess osteoconductive property. SC can play an adjunctive role in the regeneration of bone tissue, and has shown good resorbability and biocompatibility. This study was conducted in order to investigate the effects of CC and CS composite graft to the regeneration of bone in the intrabony defects of dogs. 3-wall intrabony defects ub size of $4mm{\times}4mm{\times}4mm$ were created in the alveolar bone in the premolar areas. Then those defects that were treated with root planning only were designated as control, while the experimental group 1 and 2 each received the CC and CS composite grafts in the ratio of 8 : 2 and 5 : 5 the animals were sacrificed after 8weeks and the specimens were histologically analyzed. The results were as follows ; 1. No inflammation or foreign body reaction were observed in all subjects. CS has not been seen due to complete resorption, and resorption pattern of CC was observed. 2. Significant differences(p<0.05) in new cementum formation were observed between control($1.42{\pm}0.64mm$) and experimental groups(group 1 ; $2.53{\pm}0.94mm$, group 2 ; $2.23{\pm}0.96mm$) but the difference between the two experimental groups was not significant. 3. Significant differences(p<0.01) in new bone formation were observed between control($0.59{\pm}0.55mm$) and experimental groups(group 1 ; $2.27{\pm}0.61mm$, group 2 ; $2.05{\pm}0.56mm$) but the difference between the two experimental groups was not significant. 4. The extent of apical epithelial migration has shown no significant difference between control($1.18{\pm}1.24mm$) and experimental groups(group 1 ; $0.51{\pm}0.54mm$, group 2 ; $0.73{\pm}0.70mm$). 5. The extent of bone formation was generally limited to the extent of cementum formation for all groups, and significant correlation was found in the amount of bone formation and cementum formation in experimental group 1.(Co.=0.86, p<0.01) These results suggest that the composite graft of CC and CS is biocomplatible and effective in the new bone and new cementum formations. In the case of 3-wall intrabony defects of dogs, the composite ratio of 8 : 2 and 5 : 5 had shown no significant differences in the healing.

• Journal of Periodontal and Implant Science
• /
• v.32 no.4
• /
• pp.733-744
• /
• 2002

The fibroblasts are the principal cells in the periodontal ligament of peridontium. As the periodontal ligament fibroblasts (PDLF) show similar phenotype with osteoblasts, the PDLF are thought to play an important role in alveolar bone remodeling. Cell-to-cell contacted signaling is crucial for osteoclast formation. Recently it has been reported that PDLJ enhance the bone resorbing activity of osteoclasts differentiated from hematopoietic preosteoclasts. The aims of this study were to $clarify\;^{1)}$ the mechanism of PDLF-induced osteoclastogenesis $and\;^{2)}$ whether we can use preosteoclast cell line instead of primary hematopoietic preosteoclast cells for studying the mechanism of PDLF-induced osteoclastogenesis. Osteoclastic differentiation of mouse macrophage cell line RAW264.7 was compared with that of mouse bone marrow-derived M-CSF dependent cell (MDBM), a well-known hematopoietic preosteoclast model, by examining, 1) osteoclast-specific gene expression such as calcitonin receptor, M-CSF receptor (c-fms), cathepsin K, receptoractivator nuclear factor kappa B (RANK) ,2) generation of TRAP(+) multinucleated cells (MNCs), and 3) generation of resorption pit on the $OAAS^{TM}$ plate. RAW264.7 cultured in the medium containing of soluble osteoclast differentiation Factor (sODF) showed similar phenotype with MDBM-derived osteoclasts, those are mRNA expression pattern of osteoclast-specific genes, TRAP(+) MNCs generation, and bone resorbing abivity. Formation of resorption pits by osteoclastic MNCs differentiated from sODF-treated RAW264.7, was completely blocked by the addition of osteoprotegerin (OPG), a soluble decoy receptor for ODF, to the sODF-containing culture me야um. The effects of PDLF on differentiation of RAW264.7 into　the TRAP(+) multinucleated osteoclast-like cells were examined using coculture system. PDLF were fxed with paraformaldehyde, followed by coculture with RAW264.7, which induced formation of TRAP(+) MNCs in the absence of additional treatment of sODF. When compared with untreated and fixed PDLF (fPDLF), IL-1 ${\beta}$-treated, or lipopolysaccha-ride-treated and then fixed PDLF showed two-folld increase in the supporting activity of osteoclastogenesis from RAW264.7 coculture system. There were no TRAP(+) MNCs formation in coculture system of RAW264.7 with PDLF of no fixation. These findigs suggested that we can replace the primary hematopoietic preosteoclasts for RAW264. 7 cell line for studying the mechanism of PDLF-induced osteoclastogenesis, and we hypothesize that PDLF control osteoclastogenesis through ODF expression which might be enhanced by inflammatory signals.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.3
• /
• pp.368-373
• /
• 2010

The incisors function as instruments for biting and cutting food during mastication. They also support the lips and face and maintain vertical dimension. In addition, they contribute to overall normal arch appearance. They play important role during the articulation of speech and assist in guiding jaw closure. Extraction and space maintenance are the most common treatment for a tooth with poor prognosis. However, in the mixed dentition, extraction of the upper permanent incisors results in many complications, such as resorption of alveolar bone, poor esthetics, pronunciation, and mastication. Considering these various roles of incisors in oral cavity, approach for traumatized incisors, even the ones with poor prognosis, should be considered first prior to simple extraction. The dentist must take into account the age of the patient, growth potential, occlusion, oral hygiene status, economic status and motivation towards dental health in addition to patient compliance. In this case, although the prognosis was predicted to be unfavorable due to short root and mobility, we could save the central incisor using conservative treatment, reposition by orthodontic appliance instead of extraction.

• The Journal of Korean Academy of Prosthodontics
• /
• v.60 no.2
• /
• pp.160-167
• /
• 2022

One of the treatment options for edentulous state patients with residual ridge resorption is implant overdenture using milled bar and attachment. It not only provides improved retention and stability but can also reduce the coverage of palatal surface. In addition, when a small number of implants are used, milled bar has the effect of being splinted between implant fixtures, which makes it mechanically advantageous under functions such as mastication. The patient in this case was a maxillary edentulous state patient with a considerable amount of residual alveolar bone resorption after removing the existing failed implants. Three implants were planted on both sides and an implant overdenture was fabricated using milled bar and ADD-TOC attachment.

• The Journal of Korean Academy of Prosthodontics
• /
• v.60 no.4
• /
• pp.412-419
• /
• 2022

For treatment of partially edentulous patients, a treatment using implant is widely used. Treatment method using implant are implant fixed prostheses and removable partial dentures, and for patients with severe bone resorption, removable implant overdenture with the effects of aesthetic and reducing cost can be used as treatment options. Specially, prosthesis with milled-bar and attachment has the effect of being splinted between implant fixtures, higher retention and stability than conventional removable partial denture. And it has the effect of improvement of aesthetic through lip support by denture base. In this case, the patient with severe alveolar bone resorption and partial edentulous maxilla and mandible was treated by implant-assisted removable partial denture using Milled-bar and ADD-TOC attachment. The esthetic was improved by removing the clasp because of effects of additional retention by using the attachment, and reducing palatal coverage of implant-assisted removable partial denture. The clinical results were satisfactory on the aspect of aesthetic and masticatory function.

• Journal of Periodontal and Implant Science
• /
• v.39 no.3
• /
• pp.367-373
• /
• 2009

Purpose: Following tooth extraction caused by severe periodontitis, alveolar ridge dimension lose their original volume. To reduce the alveolar ridge dimension, the ridge preservation technique has been introduced and tested in many clinical studies with membrane alone or membrane plus graft, achieving reduced ridge loss compared to extraction only. The aim of the present clinical study was to compare the post-extraction dimensional changes in the membrane exposure group to non-exposure group during healing period following ridge preservation technique. Methods: Ridge preservation was performed in 44 extraction sites. After extraction, deproteinized bovine bone mineral coated with synthetic oligopeptide (Ossgen-$X15^{(R)}$) or deproteinized bovine bone mineral (Bio-$Oss^{(R)}$) was implanted into the socket. A collagen membrane (Bio-$Gide^{(R)}$) was trimmed to cover the socket completely and applied to the entrance of the socket. Four clinical parameters were compared between baseline and 6 months. Results: During healing period, membrane exposure was observed at 19 sites. At the re-entry, hard newly formed tissue were observed at the ridge preservation site. The grafted socket sites were well preserved in their volume dimension. In both groups, horizontal ridge width was reduced and vertical height was increased. There were not statistically significant differences in horizontal (-1.32 mm vs -1.00 mm) and vertical ridge change (2.24 mm vs 2.37 mm at buccal crest, 1.36 mm vs. 1.53 mm at lingual crest) between two groups. Conclusions: The ridge preservation approach after tooth extraction effectively prevented resorption of hard tissue ridge in spite of membrane exposure during healing period.

• The korean journal of orthodontics
• /
• v.37 no.5
• /
• pp.351-363
• /
• 2007

The aim of this study was to evaluate pulp and periodontal changes following rapid tooth retraction by periodontal distraction after bone undermining surgery in young adult dogs. Methods: Alter extraction of second premolars, the interseptal bone mesial to the upper 3rd premolar was undermined. After activating the distraction appliance at 0.5 mm/day for six days, the dogs were sacrificed at 0, 1, 3, 5, 7, and 9 weeks during the consolidation period. Tissue changes of periodontium and pulp were evaluated radiologically, histologically, and immunohistochemically. Results: Digital subtraction radiography showed active bone formation in the stretched periodontal ligament from 0 - 4 weeks. Resorption of the alveolar bone, appearance of osteoclasts, and infiltration of inflammatory cells were observed just after the activation period at the pressure side, and distinctive bone formation was seen in the tension side of the periodontal ligament from 1 week. New bone formation was active at 1 - 3 weeks. The expression of calcitonin gene-related peptide in the experimental group was increased at the alveolar bone and pulp, and periodontal ligament at the pressure side from 0 - 1 week, and it decreased after 5 weeks to become similar to that of the control group. Conclusions: The results showed that rapid tooth movement using periodontal distraction can be new form of orthodontic tooth movement for accelerating normal bone formation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.38 no.6
• /
• pp.337-342
• /
• 2012

Objectives: Implants connect the internal body to its external structure, and is mainly supported by alveolar bone. Stable osseointegration is therefore required when implants are inserted into bone to retain structural integrity. In this paper, we present an implant with a "wing" design on its area. This type of implant improved stress distribution patterns and promoted changes in bone remodeling. Materials and Methods: Finite element analysis was performed on two types of implants. One implant was designed to have wings on its cervical area, and the other was a general root form type. On each implant, tensile and compressive forces ($30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$) were loaded in the vertical direction. Stress distribution and displacement were subsequently measured. Results: The maximum stresses measured for the compressive forces of the wing-type implant were $21.5979N/m^2$, $25.1974N/m^2$, $29.7971N/m^2$, and $32.3967N/m^2$ when $30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$ were loaded, respectively. The maximum stresses measured for the root form type were $23.0442N/m^2$, $26.9950N/m^2$, $30.7257N/m^2$, and $34.5584N/m^2$ when $30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$ were loaded, respectively. Thus, the maximum stresses measured for the tensile force of the root form implant were significantly higher (about three times greater) than the wing-type implant. The displacement of each implant showed no significant difference. Modifying the design of cervical implants improves the strength of bone structure surrounding these implants. In this study, we used the wing-type cervical design to reduce both compressive and tensile distribution forces loaded onto the surrounding structures. In future studies, we will optimize implant length and placement to improve results. Conclusion: 1. Changing the cervical design of implants improves stress distribution to the surrounding bone. 2. The wing-type implant yielded better results, in terms of stress distribution, than the former root-type implant.

• Journal of Periodontal and Implant Science
• /
• v.48 no.3
• /
• pp.152-163
• /
• 2018

Purpose: To determine whether the swelling and mechanical properties of osmotic self-inflating expanders allow or not the induction of intraoral soft tissue expansion in dogs. Methods: Three different volumes (0.15, 0.25, and 0.42 mL; referred to respectively as the S, M, and L groups) of soft tissue expanders (STEs) consisting of a hydrogel core coated with a silicone-perforated membrane were investigated in vitro to assess their swelling behavior (volume swelling ratio) and mechanical properties (tensile strength, tensile strain). For in vivo investigations, the STEs were subperiosteally inserted for 4 weeks in dogs (n=5). Soft tissue expansion was clinically monitored. Histological analyses included the examination of alveolar bone underneath the expanders and thickness measurements of the surrounding fibrous capsule. Results: The volume swelling ratio of all STEs did not exceed 5.2. In tensile mode, the highest mean strain was registered for the L group ($98.03{\pm}0.3g/cm$), whereas the lowest mean value was obtained in the S group ($81.3{\pm}0.1g/cm$), which was a statistically significant difference (P<0.05). In addition, the S and L groups were significantly different in terms of tensile strength ($1.5{\pm}0.1g/cm$ for the S group and $2.2{\pm}0.1g/cm$ for the L group, P<0.05). Clinical monitoring showed successful dilatation of the soft tissues without signs of inflammation up to 28 days. The STEs remained volumetrically stable, with a mean diameter in vivo of 6.98 mm, close to the in vitro post-expansion findings (6.69 mm). Significant histological effects included highly vascularized collagen-rich fibrous encapsulation of the STEs, with a mean thickness of $0.67{\pm}0.12mm$. The bone reaction consisted of resorption underneath the STEs, while apposition was observed at their edges. Conclusions: The swelling and mechanical properties of the STEs enabled clinically successful soft tissue expansion. A tissue reaction consisting of fibrous capsule formation and bone loss were the main histological events.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.1
• /
• pp.34-40
• /
• 2004

Unerupted maxillary anterior teeth is not a common case, However it may present practitioners with management problem. The cause of impaction is considered to be multifactorial, and local cause is the most common. These impacted teeth require surgical intervention, removal, transplantation, or surgical exposure, with or without orthodontic traction to align the malpositioned tooth. The preferred option is surgical exposure and orthodontic correction. Surgical intervention and orthodontic correction should not be delayed to avoid unnecessary difficulties in aligning the tooth in the arch. Surgical exposure should be performed with the intent of providing sufficient attached gingiva rather than simply uncovering the crown, which results in only alveolar mucosal attachment. Attached gingiva is essential to secure the gingival tissues to the adjacent teeth at the dentogingival junction. Thus preventing loss of periodontal tissues as a result of the pull of the surrounding soft tissues and facial muscles. Labially impacted maxillary anterior teeth uncovered with an apically positioned flap technique have more un- esthetic sequelae than those uncovered with a closed-eruption technique. In the case of severly displaced impacted teeth, autotransplantation ensures preservation of the alveolar bone and will facilitate future placement of an osseointegrated implant once growth has ceased or if ankylosis/resorption of the transplant occurs.