Jong-Hyuk Chung

Sclerostin antibody stimulates bone regeneration after experimental periodontitis

The reconstruction of large osseous defects due to periodontitis is a challenge in regenerative therapy. Sclerostin, secreted by osteocytes, is a key physiological inhibitor of osteogenesis. Pharmacologic inhibition of sclerostin using sclerostin‐neutralizing monoclonal antibody (Scl‐Ab) thus increases bone formation, bone mass and bone strength in models of osteopenia and fracture repair. This study assessed the therapeutic potential of Scl‐Ab to stimulate alveolar bone regeneration following experimental periodontitis (EP). Ligature‐induced EP was induced in rats to generate localized alveolar bone defects. Following 4 weeks of disease induction, Scl‐Ab (+EP) or vehicle (+/− EP) were systemically delivered, twice weekly for up to 6 wks to determine the ability of Scl‐Ab to regenerate bone around tooth‐supporting osseous defects. 3 and 6 wks after the initiation of Scl‐Ab or vehicle treatment, femur and maxillary jawbones were harvested for histology, histomorphometry, and micro‐computed tomography (micro‐CT) of linear alveolar bone loss (ABL) and volumetric measures of bone support, including bone volume fraction (BVF) and tissue mineral density (TMD). Serum was analyzed to examine bone turnover markers during disease and regenerative therapy. Vehicle + EP animals exhibited maxillary bone loss (BVF, TMD and ABL) at ligature removal and thereafter. 6 weeks of Scl‐Ab significantly improved maxillary bone healing, as measured by BVF, TMD and ABL, when compared to vehicle + EP. After 6 weeks of treatment, BVF and TMD values in the Scl‐Ab + EP group were similar to those of healthy controls. Serum analysis demonstrated higher levels of bone formation markers osteocalcin and PINP in Scl‐Ab treatment groups. Scl‐Ab restored alveolar bone mass following experimental periodontitis. These findings warrant further exploration of Scl‐Ab therapy in this and other oral bone defect disease scenarios.

Sodium hydrogen sulfide inhibits nicotine and lipopolysaccharide‐induced osteoclastic differentiation and reversed osteoblastic differentiation in human periodontal ligament cells

Although previous studies have demonstrated that hydrogen sulfide (H2S) stimulated or inhibited osteoclastic differentiation, little is known about the effects of H2S on the differentiation of osteoblasts and osteoclasts. To determine the possible bioactivities of H2S on bone metabolism, we investigated the in vitro effects of H2S on cytotoxicity, osteoblastic, and osteoclastic differentiation as well as the underlying mechanism in lipopolysaccharide (LPS) and nicotine‐stimulated human periodontal ligament cells (hPDLCs). The H2S donor, NaHS, protected hPDLCs from nicotine and LPS‐induced cytotoxicity and recovered nicotine‐ and LPS‐downregulated osteoblastic differentiation, such as alkaline phosphatase (ALP) activity, mRNA expression of osteoblasts, including ALP, osteopontin (OPN), and osteocalcin (OCN), and mineralized nodule formation. Concomitantly, NaHS inhibited the differentiation of tartrate‐resistant acid phosphatase (TRAP)‐positive osteoclasts in mouse bone marrow cells and blocked nicotine‐ and LPS‐induced osteoclastogenesis regulatory molecules, such as RANKL, OPG, M‐CSF, MMP‐9, TRAP, and cathepsin K mRNA. NaHS blocked nicotine and LPS‐induced activation of p38, ERK, MKP‐1, PI3K, PKC, and PKC isoenzymes, and NF‐κB. The effects of H2S on nicotine‐ and LPS‐induced osteoblastic and osteoclastic differentiation were remarkably reversed by MKP‐1 enzyme inhibitor (vanadate) and expression inhibitor (triptolide). Taken together, we report for the first time that H2S inhibited cytotoxicity and osteoclastic differentiation and recovered osteoblastic differentiation in a nicotine‐ and periodontopathogen‐stimulated hPDLCs model, which has potential therapeutic value for treatment of periodontal and inflammatory bone diseases. J. Cell. Biochem. 114: 1183–1193, 2013.

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 effects of bone grafting material and a collagen membrane in the ridge splitting technique: an experimental study in dogs

OBJECTIVES This study was designed to evaluate the effect of bone graft materials and collagen membranes in ridge splitting procedures with immediate implant placement using a dog model. MATERIALS AND METHODS Mandibular premolars were extracted in five beagle dogs. After 3 months, ridge splitting and placement of three OsseoSpeed implants were performed bilaterally. The gaps between the implants were allocated according to the following eight treatment modalities; Group 1(no graft), Group 2 (autogenous bone), Group 3 (Bio-Oss Collagen), Group 4 (Bio-Oss), Group 5 (no graft+BioGide), Group 6 (autogenous bone+BioGide), Group 7 (Bio-Oss Collagen+BioGide), and Group 8 (Bio-Oss +BioGide). The dogs were sacrificed after 8 or 12 weeks and the specimens were analyzed histologically and histometrically. RESULTS The gaps between the implants were filled with the newly formed bone, irrespective of which of the eight grafting techniques was used. Group 1 revealed a significantly lower percentage of bone-to-implant contact (BIC) than Group 5 at 8 and 12 weeks (P<0.05). Group 1 showed the most prominent marginal bone loss (MBL) at 12 weeks (P<0.05). Regarding the use of membranes, Groups 1 and 2 showed significantly more MBL than Groups 5 and 6 at 12 weeks (P<0.05). CONCLUSIONS After ridge splitting, if the gaps between implants were grafted or covered with collagen membranes, a higher percentage of BIC was obtained. Based on our results, we suggest that the use of bone graft materials and/or collagen membranes is better for the prevention of MBL after ridge splitting procedures.

The effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of double acid-etched implants

Purpose One of the most frequent complications related to dental implants is peri-implantitis, and the characteristics of implant surfaces are closely related to the progression and resolution of inflammation. Therefore, a technical modality that can effectively detoxify the implant surface without modification to the surface is needed. The purpose of this study was to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on the microstructural changes in double acid-etched implant surfaces according to the laser energy and the application duration. Methods The implant surface was irradiated using an Er:YAG laser with different application energy levels (100 mJ/pulse, 140 mJ/pulse, and 180 mJ/pulse) and time periods (1 minute, 1.5 minutes, and 2 minutes). We then examined the change in surface roughness value and microstructure. Results In a scanning electron microscopy evaluation, the double acid-etched implant surface was not altered by Er:YAG laser irradiation under the condition of 100 mJ/pulse at 10 Hz for any of the irradiation times. However, we investigated the reduced sharpness of the specific ridge microstructure that resulted under the 140 mJ/pulse and 180 mJ/pulse conditions. The reduction in sharpness became more severe as laser energy and application duration increased. In the roughness measurement, the double acid-etched implants showed a low roughness value on the valley area before the laser irradiation. Under all experimental conditions, Er:YAG laser irradiation led to a minor decrease in surface roughness, which was not statistically significant. Conclusions The recommended application settings for Er:YAG laser irradiation on double acid-etched implant surface is less than a 100 mJ/pulse at 10 Hz, and for less than two minutes in order to detoxify the implant surface without causing surface modification.

Development and evaluation of new primers for PCR‐based identification of type II fimA of Porphyromonas gingivalis

For more accurate PCR-based identification of Porphyromonas gingivalis harboring genotype II fimA, the most prevalent type in periodontitis patients, a new primer set was developed and evaluated. The previous type II primers hybridized to the DNA of P gingivalis strains harboring type Ib as well as type II fimA, while the new primers specifically amplified only the DNA fragment of type II fimA. In the investigation using mixed bacterial culture and 155 clinical samples from peri-implantitis patients, the new primers increased the accuracy of PCR-based detection of type II fimA by excluding false-negatives as well as false-positives.

A comparison of different gingival depigmentation techniques: ablation by erbium:yttrium-aluminum-garnet laser and abrasion by rotary instruments

Purpose The aim of this study is to compare two different gingival depigmentation techniques using an erbium:yttrium-aluminum-garnet (Er:YAG) laser and rotary instruments. Methods Two patients with melanin pigmentation of gingiva were treated with different gingival depigmentation techniques. Ablation of the gingiva by Er:YAG laser was performed on the right side, and abrasion with a rotary round bur on the opposite side. Results The patients were satisfied with the esthetically significant improvement with each method. However, some pigment still remained on the marginal gingival and papilla. The visual analog scale did not yield much difference between the two methods, with slightly more pain on the Er:YAG laser treated site. Conclusions The results of these cases suggest that ablation of the gingiva by an Er:YAG laser and abrasion with a rotary round bur is good enough to achieve esthetic satisfaction and fair wound healing without infection or severe pain. Prudent care about the gingival condition, such as the gingival thickness and degree of pigmentation along with appropriate assessment is needed in ablation by the Er:YAG laser procedure.

Implant failure associated with oral bisphosphonate-related osteonecrosis of the jaw

Purpose The aim of this study is to report a case of oral bisphosphonate-related osteonecrosis of the jaw (BRONJ) resulting in implant failure. Methods A patient suspected of having BRONJ was referred to the Department of Periodontology, Kyung Hee University School of Dentistry for the evaluation and treatment of exposed bone around implants. Results The patient, who had been taking oral bisphosphonates (BPs) for about a year, was successfully treated with systemic antibiotics, chlorhexidine mouth rinse, explantation, and surgical debridement of necrotic bone. Conclusions The results of this case suggest that a patient taking BPs orally should be treated cautiously. Appropriate management including cessation of BPs and respective dental treatment may reduce the development of BRONJ.

Effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of sand-blasted, large grit, acid-etched implants

Purpose The present study was performed to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on sand-blasted, large grit, acid-etched (SLA) implant surface microstructure according to varying energy levels and application times of the laser. Methods The implant surface was irradiated by the Er:YAG laser under combined conditions of 100, 140, or 180 mJ/pulse and an application time of 1 minute, 1.5 minutes, or 2 minutes. Scanning electron microscopy (SEM) was used to examine the surface roughness of the specimens. Results All experimental conditions of Er:YAG laser irradiation, except the power setting of 100 mJ/pulse for 1 minute and 1.5 minutes, led to an alteration in the implant surface. SEM evaluation showed a decrease in the surface roughness of the implants. However, the difference was not statistically significant. Alterations of implant surfaces included meltdown and flattening. More extensive alterations were present with increasing laser energy and application time. Conclusions To ensure no damage to their surfaces, it is recommended that SLA implants be irradiated with an Er:YAG laser below 100 mJ/pulse and 1.5 minutes for detoxifying the implant surfaces.

I-shaped incisions for papilla reconstruction in second stage implant surgery

Purpose Pink gingival esthetic especially on the anterior teeth has been an important success criterion in implant-supported restoration. Inter-implant papillae are a critical factor for implant esthetics, and various techniques for inter-implant papilla reconstruction have been introduced. The aim of this study is to suggest and evaluate a surgical technique for reconstructing inter-implant papillae. Methods A 28-year-old man had an implant placed on the #13 and #14 area. Four months after implant placement, a second stage surgery was planned for inter-implant papilla reconstruction. At the time of the abutment connection, I-type incisions were performed on the #13i & #14i area followed by full-thickness flap elevation and connection of a healing abutment on underlying fixtures without suture. Results Two weeks after the second stage implant surgery, soft tissue augmentation between the two implants was achieved. Conclusions I-shaped incisions for papilla reconstruction performed during the second stage implant surgery were useful for inter-implant papilla reconstruction and showed a good esthetic result.