• Journal of dental hygiene science
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• v.15 no.2
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• pp.98-105
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• 2015

We investigated the effects of a mutan (water-insoluble ${\alpha}$-glucans) isolated from Streptococcus mutans on the healing of bone defect in rat. Sprague-Dawley rats were divided into control (saline-treated), lipopolysaccharide (LPS)-treated, and mutan-treated groups (n=6 per group). Experimental bone defects were surgically created with round fissure bur at the buccal surface of the left mandibular. The control groups was administered with saline solution (0.1 ml/100 g), while the LPS and mutan group was given LPS and mutan (1 mg/kg body weight) three times weekly. After 4 weeks the rats were sacrificed, the healing of bone defect was assessed by bone mineral density (BMD) and micro-computed tomography (${\mu}CT$) examination. Percent bone volume (bone volume/tissue volume [BV/TV]), trabecular thickness (Tb.Th), and trabecular number (Tb.N) parameters of ${\mu}CT$ showed higher values in control group than LPS and mutan group. Bone surface/volume ratio (BS/BV), trabecular bone pattern factor (Tb.Pf), and structure model index parameters of ${\mu}CT$ showed higher values in LPS group than mutan group. BMD values of mutan treated-alveolar bones were significantly lower for than that of the LPS group. Therefore, we suggest that mutan, water-insoluble ${\alpha}$-glucans from S. mutans may be induce the induction of periodontal diseases.

• Journal of Periodontal and Implant Science
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• v.53 no.4
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• pp.306-317
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• 2023

Purpose: Biphasic calcium phosphate (BCP), a widely used biomaterial for bone regeneration, contains synthetic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), the ratio of which can be adjusted to modulate the rate of degradation. The aim of this study was to evaluate the clinical and radiographic benefits of reconstructing peri-implant bone defects with a newly developed BCP consisting of 60% β-TCP and 40% HA compared to demineralized bovine bone mineral (DBBM). Methods: This prospective, multicenter, parallel, single-blind randomized controlled trial was conducted at the periodontology departments of 3 different dental hospitals. Changes in clinical (defect width and height) and radiographic (augmented horizontal bone thickness) parameters were measured between implant surgery with guided bone regeneration (GBR) and re-entry surgery. Postoperative discomfort (severity and duration of pain and swelling) and early soft-tissue wound healing (dehiscence and inflammation) were also assessed. Data were compared between the BCP (test) and DBBM (control) groups using the independent t-test and the χ² test. Results: Of the 53 cases included, 27 were in the test group and 26 were in the control group. After a healing period of 18 weeks, the full and mean resolution of buccal dehiscence defects were 59.3% (n=16) and 71.3% in the test group and 42.3% (n=11) and 57.9% in the control group, respectively. There were no significant differences between the groups in terms of the change in mean horizontal bone augmentation (test group: -0.50±0.66 mm vs. control groups: -0.66±0.83 mm, P=0.133), postoperative discomfort, or early wound healing. No adverse or fatal complications occurred in either group. Conclusions: The GBR procedure with the newly developed BCP showed favorable clinical, radiographic, postoperative discomfort-related, and early wound healing outcomes for peri-implant dehiscence defects that were similar to those for DBBM.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.313-326
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• 2007

With rising prevalency of mouth breathing children caused by developing civilization and increasing pollution, there are many maxillary transverse discrepancy patients with undergrowth of maxilla. For improving this, maxillary mid-palatal suture splitting was often performed. The purpose of this study was to analyse the stress distribution on the craniofacial suture and cranium after rapid maxillary expansion by finite element model. The boy(13Y6M) was chosen for taking computed-tomography for finite element model. Three-dimensional model of maxilla, first premolar, first molar, buccal and lingual part of rapid maxillary expansion were constructed. 1. The alveolar bone adjacent to the first molar and the first premolar that was affected directly by rapid maxillary expansion was displaced laterally approximately 4.04mm at maximum. The force decreased toward anterior region and frontal alveolar bone displaced laterally about 3.18mm. 2. A forward maximum displacement was exhibited at zygomatic process middle region. 3. At maximum, maxillary median part experienced 0.973mm downward repositioning and 0.65mm upward repositioning at lateral alveolar bone. 4. Von mises stress was observed the largest stress distribution around teeth and zygomatic buttress. 5. The largest tensile force was observed around alveolar bone of teeth, while compression force was observed at zygomatic buttress.

• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.35.1-35.9
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• 2022

Although the success rates of microsurgery and micro-resurgery are very high, the influence of a recurrent perforation combined with radicular cyst remains unclear. A 21-year-old white female patient had a history of root perforation in a previously treated right maxillary lateral incisor. Analysis using cone-beam computed tomography (CBCT) revealed an extensive and well-defined periapical radiolucency, involving the buccal and palatal bone plate. The perforation was sealed with bioceramic material (Biodentine) in the pre-surgical phase. In the surgical phase, guided tissue regeneration (GTR) was performed by combining xenograft (lyophilized bovine bone) and autologous platelet-rich fibrin applied to the bone defect. The root-end preparation was done using an ultrasonic tip. The retrograde filling was performed using a bioceramic material (Biodentine). Histopathological analysis confirmed a radicular cyst. The patient returned to her referring practitioner to continue the restorative procedures. CBCT analysis after 1-year recall revealed another perforation in the same place as the first intervention, ultimately treated by micro-resurgery using the same protocol with GTR, and a bioceramic material (MTA Angelus). The 2-year recall showed healing and bone neoformation. In conclusion, endodontic micro-resurgery with GTR showed long-term favorable results when a radicular cyst and a recurrent perforation compromised the success.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.6
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• pp.498-510
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• 2001

Distraction osteogenesis refers to the biological process responsible for new bone formation between bone segments by gradual distraction after osteotomy. For the past several years, various inconveniences including a protracted consolidation period that requires patients to wear a distractor frame longer, as well as higher medical costs, have not been remedied by improvements in osteotomy, distraction rate and monitoring system. Furthermore, side effects such as pin tract infections and soft tissue swelling may arise due to the long treatment period. These drawbacks form the rationale of this study which purports to seek a method by which the consolidation period can be reduced. This paper examines how platelet-rich plasma(PRP), known to facilitate osteogenesis, influences bone formation when applied in distracted area. Ten mongrel dogs, which were made to wear external distractor frames after osteotomy in both sides of the mandible, were used as subjects. After a 7day period of latency, distraction was carried out at a rate of 1mm/day for 14 consecutive days. After the onset of distraction, 2ml of PRP and a mixture of calcium gluconate and thrombine were injected into the center of the distracted callus on the left side of the mandible. The left was injected with PRP while the right side was set as the control site without PRP treatment. Execution at the onset of distraction and in 2 weeks, 4 weeks and 8 weeks after the consolidation period, clinical and radiographic tests, bone mineral density examination, histological examination and histomorphometric analysis were conducted to compare both sides. The results are summarized as follows: 1. Based on the clinical examination at two weeks, more remarkable cortical bone formation was found on the buccal and lingual side of the distracted area in the PRP treatment site than in the control site. No visual difference was found between the PRP treatment site and the control site at four eight weeks. 2. Based on the radiological examination, a distinct increase in the radiopaque appearance of the PRP treatment site was revealed at two weeks, but this increase appeared to slow down at four and eight weeks. 3. Examination of bone mineral density revealed a significant difference at two weeks with the PRP treatment site yielding density two times higher than the control site. This difference lessened after four weeks, and disappeared at eight weeks. 4. The histomorphometric examination revealed that about 20% more bony trabeculae area(20%, higher) was formed in the PRP treatment site than in the control site. In conclusion, it can be said that PRPs effect on stimulating bone formation in the PRP treatment site manifest as early as two weeks. Trabeculae formation likewise increased throughout the whole period. If this result can be applied to humans, the consolidation period can be reduced by injecting PRP into the distracted area.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.167-175
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• 2010

Objective: The aim of this study was to validate the Periotest values for the prediction of orthodontic mini-implants' stability. Methods: Sixty orthodontic mini-implants (7.0 mm $\times$ $\emptyset1.45$ mm; ACR, Biomaterials Korea, Seoul, Korea) were inserted into the buccal alveolar bone of 5 twelve month-old beagle dogs. Insertion torque (IT) and Periotest values (PTV) were measured at the installation procedure, and removal torque (RT) and PTV were recorded after 12 weeks of orthodontic loading. To correlate PTV with variables, the cortical bone thickness (mm) and bone mineral density (BMD) within the cortical bone and total bone area were calculated with the help of CT scanning. Results: The BMD and cortical bone thickness in mandibular alveolus were significantly higher than those of the maxilla (p < 0.05). The PTV values ranged from -3.2 to 4.8 for 12 weeks of loading showing clinically stable mini-implants. PTV at insertion was significantly correlated with IT (-0.51), bone density (-0.48), cortical bone thickness (-0.42) (p < 0.05) in the mandible, but showed no correlation in the maxilla. PTV before removal was significantly correlated with RT (-0.66) (p < 0.01) in the mandible. Conclusions: These results show that the periotest is a useful method for the evaluation of mini-implant stability, but it can only be applied to limited areas with thick cortical and high density bone such as the mandible.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.277-288
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• 2002

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the premolar superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional finite element analysis and the maximum von Mises stress in each reference area was compared. Under lateral loading, the stress was larger at the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. Around the fixture having wider platform, less stress was produced at the abutment/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In conclusion, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.32.1-32.7
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• 2019

Background: Tooth extraction commonly leads to loss of residual alveolar ridge, thus compromising the room available for the implant placement. To combat the post-extraction alveolar loss, alveolar ridge preservation is practiced, with the advent of the biomaterial available. The purpose of this study was to assess the efficiency of calcium phosphosilicate biomaterial in alveolar ridge preservation. Twenty patients indicated for extraction were selected followed by socket grafting using calcium phosphosilicate. Implant placement was done 6 months postoperatively during which a core was harvested from the preserved sockets. Clinico-radiographic measurements of hard and soft tissues were taken at baseline and 6 months post-grafting. Results: There were no significant changes in the radiographic and soft tissue parameters while significant changes in hard tissue parameters with 1.9 mm (p = 0.013) gain in mid-buccal aspect and 1.1 mm (p = 0.019) loss in horizontal bone width were observed. The histomorphometric evaluation depicted the vital bone volume of 54.5 ± 16.76%, non-mineralized tissue 43.50 ± 15.80%, and residual material 2.00 ± 3.37%. Conclusion: The implants placed in these preserved ridges presented 100% success rate with acceptable stability after a 1-year follow-up, concluding calcium phosphosilicate is a predictable biomaterial in alveolar ridge preservation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.7-21
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• 1994

Fifty-two cases of traumatic bone cysts in 50 patients were analysed clinically and radiologically. The obtained results were as follows; 1. Women showed a slightly higher incidence than did men (56% of patients) and the average age proved to be 18.6 years. 2. The majority of the cases were asymptomatic. being detected incidentally. and over the half of the cases occurred in the mandibular symphyseal region. 3. All cases were unilocular and the largest diameter of the lesions varied from 1 to 10㎝, mean 3㎝. 4. Some degree of marginal condensation was present in 28 cases and 23 cases presented pencil-sketch appearance. 5. Many anatomical cortical plates (especially, mandibular inferior cortex and lamina durae) consisted of the margin of the lesions partly. 6. Erosive change of the mandibular inferior cortex was caused by 12 cysts, but cortical expansion only by 3 cysts including 2 cases of buccal expansion. 7. The lesion enveloped the roots of the adjacent teeth in 27 cases and scalloping was present between roots in 17 cases. 8. Lamina dura of the teeth was destroyed by only 1 cyst, and in 1 case root resorption was noticed. But there was no divergence of the roots of teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.59-72
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• 2000

This study was performed to investigate the effects of tooth mobility and design of the direct retainer on the stress of supporting tissues in distal extension removable partial denture. Tooth mobility was simulated and four different types of direct retainer such as Alters clasp, I-bar clasp, wrought wire clasp, and Dalbo attachment were designed and stress on the support-ing tissues were measured and analyzed with straingauge method. The following conclusions were drawn from this study. 1. The stress revealed at the lingual side of alveolar bone of the abutment tooth in edentulous area was the largest. 2. The stress at the lingual side of alveolar bone of the abutment tooth in edentulous area was increased according to the increase of tooth mobility in I-bar clasp and Dalbo attachment. 3. The stress at the residual ridge crest was the great in Dalbo attachment on mobility 0, in I-bar clasp on mobility 1, and in wrought wire clasp on mobility 2. 4. There was little changes of stress according to the increase of tooth mobility at buccal and lingual side of the residual ridge crest and around the abutment teeth in dentulous area.