Gyu-Tae Kim

Effect of heparin and alendronate coating on titanium surfaces on inhibition of osteoclast and enhancement of osteoblast function

The failure of orthopedic and dental implants has been attributed mainly to loosening of the implant from host bone, which may be due to weak bonding of the implant material to bone tissue. Titanium (Ti) is used in the field of orthopedic and dental implants because of its excellent biocompatibility and outstanding mechanical properties. Therefore, in the field of materials science and tissue engineering, there has been extensive research to immobilize bioactive molecules on the surface of implant materials in order to provide the implants with improved adhesion to the host bone tissue. In this study, chemically active functional groups were introduced on the surface of Ti by a grafting reaction with heparin and then the Ti was functionalized by immobilizing alendronate onto the heparin-grafted surface. In the MC3T3-E1 cell osteogenic differentiation study, the alendronate-immobilized Ti substrates significantly enhanced alkaline phosphatase activity (ALP) and calcium content. Additionally, nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation of RAW264.7 cells was inhibited with the alendronate-immobilized Ti as confirmed by TRAP analysis. Real time PCR analysis showed that mRNA expressions of osteocalcin and osteopontin, which are markers for osteogenesis, were upregulated in MC3T3-E1 cells cultured on alendronate-immobilized Ti. The mRNA expressions of TRAP and Cathepsin K, markers for osteoclastogenesis, in RAW264.7 cells cultured on alendronate-immobilized Ti were down-regulated. Our study suggests that alendronate-immobilized Ti may be a bioactive implant with dual functions to enhance osteoblast differentiation and to inhibit osteoclast differentiation simultaneously.

Anatomical structures in the maxillary sinus related to lateral sinus elevation: a cone beam computed tomographic analysis

OBJECTIVES The objective of this study is to evaluate the anatomical structures in the maxillary sinus with relation to lateral approach sinus elevation utilizing cone beam computed tomography (CT) scans taken prior to sinus elevation surgery. MATERIALS AND METHODS A total of 150 CT images were acquired from 150 patients (90 men and 60 women; mean age, 49.4 years, range 23-86 years) who were being treated with implant-supported restorations in the posterior edentulous maxilla. Of the 150 CT scans, 65 were of the right sinus and 85 of the left sinus. Measurements of the anatomical structures in the maxillary sinus were conducted on the CT images. RESULTS In the mean width of the lateral wall, there were statistically significant values among the measurement points (P < 0.05). The anterior area of the sinus lateral wall was thicker than the posterior lateral wall. There was a statistically significant difference between the vessel diameter and lateral wall width (P < 0.05). As sinus lateral wall width increased, so did the vessel diameter. The mean distance to the inferior border of the vessel from the sinus floor and from the alveolar crest was 8.25 and 17.03 mm, respectively. The intraosseous group among the vessel position was 64.3%, so the intraosseous vessel could be visualized in CT scans at 64.3%. In angle A, the group of less than 30° was 4.8%. Schneiderian membrane perforation by narrow angle had a low risk. The prevalence of the septa related to Schneiderian membrane perforation was 44%. The distance to the inferior border of the vessel from the alveolar crest being less than 15 mm was 31%. The vessel diameter greater than 1 mm was 37.8%. CONCLUSIONS Based on present research about utilizing cone beam CT scans for sinus elevation, the alteration of the lateral approach sinus elevation technique is highly recommended if complications such as membrane perforation or bleeding are expected.

The incidence and configuration of the bifid mandibular canal in Koreans by using cone-beam computed tomography

Purpose This study was performed to investigate the incidence and configuration of the bifid mandibular canal in a Korean population by using cone-beam computed tomography (CBCT) imaging. Materials and Methods CBCT images of 1933 patients (884 male and 1049 female) were evaluated using PSR-9000N and Alphard-Vega 3030 Dental CT units (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan). Image analysis was performed by using OnDemand3D software (CyberMed Inc., Seoul, Korea). The bifid mandibular canal was identified and classified into four types, namely, the forward canal, buccolingual canal, dental canal, and retromolar canal. Statistical analysis was performed by using the chi-squared test and one-way analysis of variance (ANOVA). Results Bifid mandibular canals were observed in 198 (10.2%) of 1933 patients. The most frequently observed type of bifid mandibular canal was the retromolar canal (n=104, rate: 52.5%) without any significant difference among the incidence of each age and gender. The mean diameter of the accessory canal was 1.27 mm (range: 0.27-3.29 mm) without any significant difference among the mean diameter of each type of the bifid mandibular canal. The mean length of the bifid mandibular canals was 14.97mm(range: 2.17-38.8 mm) with only a significant difference between the dental canal and the other types. Conclusion The bifid mandibular canal is not uncommon in Koreans and has a prevalence of 10.2% as indicated in the present study. It is suggested that a CBCT examination be recommended for detecting a bifid canal.

Cone-beam computed tomography evaluation of orthodontic miniplate anchoring screws in the posterior maxilla

INTRODUCTION The purposes of this study were to evaluate the actual postplacement positions of orthodontic miniplate anchoring screws (MPAS) and to determine the risk factors for their failure and iatrogenic effects on the intraoral structures. METHODS Three-dimensional cone-beam computed tomography images were generated to examine 31 orthodontic miniplates and their MPAS (diameter, 1.5 mm; length, 4 mm), which showed good clinical stability 6 months after placement in the posterior maxilla of 18 patients. The cone-beam computed tomography data were analyzed with analysis of variance (ANOVA) statistics to evaluate the difference of placement depth and vertical distance of the MPAS from the cementoenamel junction to the center of the screw. The Fisher exact test was used to determine differences in MPAS position, root proximity, and sinus penetration. RESULTS The mean placement depth of the MPAS was 2.48 mm with no significant difference relative to their position. Twenty-six (of 74) MPAS were placed in the dentition area. Of these 26, 14 were placed in interdental spaces, and the other 12 followed the direction of the roots. Nine MPAS showed root proximity, and 7 MPAS had root penetration, all of which were placed in the central position of the miniplate. Thirty-nine MPAS penetrated the sinus, indicating a low interrelationship between placement depth and cortical bone thickness of the sinus. CONCLUSIONS Miniplates were successfully retained by MPAS even with less-than-ideal placement. Root contact and proximity of MPAS seem to have minimal effects on the successful stabilization of miniplates. Pertinent guidelines should, however, be followed during MPAS placement to minimize the risk of damage to adjacent roots.

Sublingual traumatic ulceration (a Riga‐Fede disease): report of two cases

Sublingual traumatic ulceration is rare and a benign, ulcerative and granulomatous process that occurs as a result of repetitive trauma of the oral mucosal surfaces by the teeth. Treatment should begin conservatively and should focus on eliminating the source of the trauma. In our cases, we chose the conservative treatment by grinding the teeth and placing composite resin over the offending teeth and applied orabase. At the follow-up, we confirmed that the lesion was resolved and infant was feeding normally.

Endodontic Treatment of an Anomalous Anterior Tooth with the Aid of a 3-dimensional Printed Physical Tooth Model

Endodontic treatment of tooth formation anomalies is a challenge to clinicians and as such requires a complete understanding of the aberrant root canal anatomy followed by careful root canal disinfection and obturation. Here, we report the use of a 3-dimensional (3D) printed physical tooth model including internal root canal structures for the endodontic treatment of a challenging tooth anomaly. A 12-year-old boy was referred for endodontic treatment of tooth #8. The tooth showed class II mobility with swelling and a sinus tract in the buccal mucosa and periapical radiolucency. The tooth presented a very narrow structure between the crown and root by distal concavity and a severely dilacerated root. Moreover, a perforation site with bleeding and another ditching site were identified around the cervical area in the access cavity. A translucent physical tooth model carrying the information on internal root canal structures was built through a 3-step process: data acquisition by cone-beam computed tomographic scanning, virtual modeling by image processing, and manufacturing by 3D printing. A custom-made guide jig was then fabricated to achieve a safe and precise working path to the root canal. Endodontic procedures including access cavity preparation were performed using the physical tooth model and the guide jig. At the 7-month follow-up, the endodontically treated tooth showed complete periapical healing with no clinical signs and symptoms. This case report describes a novel method of endodontic treatment of an anomalous maxillary central incisor with the aid of a physical tooth model and a custom-made guide jig via 3D printing technique.

NOD2 Mediates Odontoblast Differentiation and RANKL Expression

The precise regulation of odontoblast differentiation and osteoclastogenic cytokine expression in human dental pulp cells (HDPCs) is crucial for the pathology of bacteria-related pulpitis. Although the up-regulation of nucleotide-binding oligomerization domain-containing protein 2 (NOD2) has been reported in inflamed human dental pulps, the role of NOD2 in the differentiation of HDPCs remains unclear. Here, we show the involvement of NOD2 in odontoblast differentiation together with osteoclastogenic cytokine expression in HDPCs. Treatment with muramyl dipeptide (MDP), a known NOD2-agonist, significantly inhibited odontoblast differentiation of HDPCs, as revealed by reduced ALP activity, osteoblast/odontoblast marker expression, and mineralized nodule formation. Importantly, the forced down-regulation of NOD2 by small interfering RNA (siRNA) recovered MDP-down-regulated odontoblast differentiation. MDP-elicited suppression of odontoblast differentiation resulted from the increased expression of MKP-1 protein and the subsequent decline of MAPKs phosphorylation, which is a prerequisite for odontoblast differentiation. Furthermore, we found that MDP treatment elevated the expression of osteoclastogenic cytokines in HDPCs, which was also reversed by NOD2 silencing. Analysis of these data, taken together, suggests that the regulation of NOD2 expression upon MDP challenge might serve as an intrinsic mechanism that underlies the hindered dentin formation and accelerated dentin resorption in bacterial infection-mediated pulpitis. Abbreviations: HDPCs, human dental pulp cells; NOD2, nucleotide-binding oligomerization domain-containing protein 2; MDP, muramyl dipeptide; siRNA, small interfering RNA; MAPKs, mitogen-activated protein kinases; MKP-1, MAPK phosphatase-1; BMMs, bone-marrow-derived macrophages; and CM, conditioned medium.

Accuracy of a cone beam computed tomography-guided surgical stent for orthodontic mini-implant placement.

OBJECTIVE To validate the accuracy of a cone-beam computed tomography (CBCT)-guided surgical stent for orthodontic mini-implant (OMI) placement by quantitatively evaluating the difference between CBCT-prescribed and actual position of mini-implants in preoperative and postoperative CBCT images. MATERIALS AND METHODS A surgical stent was fabricated using Teflon-Perfluoroalkoxy, which has appropriate biological x-ray attenuation properties. Polyvinylsiloxane impression material was used to secure the custom-made surgical stent onto swine mandibles. CBCT scanning was done with the stent in place to virtually plan mini-implants using a three-dimensional (3D) software program. An appropriate insertion point was determined using 3D reconstruction data, and the vertical and horizontal angulations were determined using four prescribed angles. A custom-designed surveyor was used to drill a guide hole within the surgical stent as prescribed on the CBCT images for insertion of 32 OMIs. The mandibles with a surgical stent in place were rescanned with CBCT to measure the deviations between the virtual planning data and surgical results. RESULTS The difference between the prescribed and actual vertical angle was 1.01 ± 7.25, and the horizontal difference was 1.16 ± 6.08. The correlation coefficient confirms that there was no intrarater variability in either the horizontal (R  =  .97) or vertical (R  =  .74) vectors. CONCLUSIONS The surgical stent in this study guides mini-implants to the prescribed position as planned in CBCT. Since the statistical difference was not significant, the surgical stent can be considered to be an accurate guide tool for mini-implant placement in clinical use.

Malignant transformation of monostotic fibrous dysplasia in the mandible.

Malignant transformation of fibrous dysplasia (FD), which was first introduced by Coley and Steward is very rare. We present a case of malignant transformation of monostotic mandibular FD after 2 surgical excisions, 20 and 15 years ago, respectively. The treatment choice of FD is usually conservative. With the advanced surgical techniques, radical excisions followed by immediate reconstruction have been reported. However, the decision criteria are still controversial and we might think that radical treatment is a good method for recurrent lesions based on the recent literatures. The case discussed here is of sarcomatous transformation of a recurrent FD.

Primary intraosseous squamous cell carcinoma mimicking periapical disease: a case report

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare carcinoma, which arises within the jaws without connection to the oral mucosa and presumably develops from a remnant of odontogenic epithelium. We present a case of solid type PIOSCC in a 52-year-old male patient complaining of dull pain on his left lower molar. In this case, early stage PIOSCC mimicking a periapical lesion might lead to a one-year delay in treatment due to the misdiagnosis of osteomyelitis after extraction of the third molar. The clinical, radiological, and histologic features are described. In this case, there was initial radiographic evidence for PIOSCC mimicking a periapical lesion. Incautious radiographic interpretation and treatment procedures had delayed the correct diagnosis and resulted in extensive bony destruction during the patients disease progression.