Yeek Herr

Marginal bone loss around three different implant systems: radiographic evaluation after 1 year

This study was designed to radiographically evaluate the effect of surface macro-and microstructures within the coronal portion of the external hex implant at the marginal bone change after loading. The fifty-four patients included in the study were randomly assigned to treatment groups with rough-surface implants (TiUnite, n = 45), a hybrid of smooth and rough surface implants (Restore, n = 45) or rough-surface with microthreads implants (Hexplant, n = 45). Clinical and radiographic examinations were conducted at the time of implant loading (baseline) and at 1-year post-loading. A three-level mixed-effect ancova was used to test the significance of the mean marginal bone change of the three implant groups from baseline to 1-year follow-up. At 1-year, significant differences were noted in marginal bone loss recorded for the three groups (P < 0.0001). The rough surface with microthread implants had a mean crestal bone loss of 0.42 +/- 0.27 mm; the rough surface implants, 0.81 +/- 0.27 mm; and the hybrid surface implants, 0.89 +/- 0.41 mm. Within the limitations of this study, a rough surface with microthreads at the coronal part of implant maintained the marginal bone level against functional loading better than implants without these two features.

Endoplasmic reticulum stress modulates nicotine-induced extracellular matrix degradation in human periodontal ligament cells.

BACKGROUND AND OBJECTIVE Tobacco smoking is considered to be one of the major risk factors for periodontitis. For example, about half the risk of periodontitis can be attributable to smoking in the USA. It is evident that smokers have greater bone loss, greater attachment loss and deeper periodontal pockets than nonsmoking patients. It has recently been reported that endoplasmic reticulum (ER) stress markers are upregulated in periodontitis patients; however, the direct effects of nicotine on ER stress in regard to extracellular matrix (ECM) degradation are unclear. The purpose of this study was to examine the effects of nicotine on cytotoxicity and expression of ER stress markers, selected ECM molecules and MMPs, and to identify the underlying mechanisms in human periodontal ligament cells. We also examined whether ER stress was responsible for the nicotine-induced cytotoxicity and ECM degradation. MATERIAL AND METHODS Cytotoxicity and cell death were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide assay and flow cytometric annexin V and propidium iodide staining. The mRNA and protein expressions of MMPs and ER markers were examined by RT-PCR and western blot analysis. RESULTS Treatment with nicotine reduced cell viability and increased the proportion of annexin V-negative, propidium iodide-positive cells, an indication of cell death. Nicotine induced ER stress, as evidenced by survival molecules, such as phosphorylated protein kinase-like ER-resident kinase, phosphorylated eukaryotic initiation factor-2α and glucose-regulated protein-78, and apoptotic molecules, such as CAAT/enhancer binding protein homologous protein (CHOP). Nicotine treatment led to the downregulation of ECM molecules, including collagen type I, elastin and fibronectin, and upregulation of MMPs (MMP-1, MMP-2, MMP-8 and MMP-9). Inhibition of ER stress by salubrinal and transfection of CHOP small interfering RNA attenuated the nicotine-induced cell death, ECM degradation and production of MMPs. Salubrinal and CHOP small interfering RNA inhibited the effects of nicotine on the activation of Akt, JNK and nuclear factor-κB. CONCLUSION These results indicate that nicotine-induced cell death is mediated by the ER stress pathway, involving ECM degradation by MMPs, in human periodontal ligament cells.

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.

Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E2 by hypoxia‐inducible factor‐1α up‐regulation in human periodontal ligament cells

BACKGROUND AND OBJECTIVE   Although hypoxia-inducible factor 1α (HIF-1α) is up-regulated in the periodontal pockets of periodontitis patients, the expression and precise molecular mechanisms of HIF-1α remain unknown in human periodontal ligament cells (PDLCs). The aim of this study was to explore the effects, as well as the signaling pathway, of nicotine and lipopolysaccharide (LPS) on the expression of HIF-1α and on the production of its target genes, including cyclooxygenase-2 (COX-2)-derived prostaglandin E(2) (PGE(2) ), MMP-2 and MMP-9 in PDLCs. MATERIAL AND METHODS   The expression of COX-2 and HIF-1α proteins was evaluated using western blotting. The production of PGE(2) and MMPs was evaluated using enzyme immunoassays and zymography, respectively. RESULTS   LPS and nicotine synergistically induced the production of PGE(2) , MMP-2 and MMP-9, and increased the expression of MMP-2, MMP-9, COX-2 and HIF-1α proteins. Inhibition of HIF-1α activity by chetomin or knockdown of HIF1α gene expression by small interfering RNA markedly attenuated the production of LPS- and nicotine-stimulated PGE(2) and MMPs, as well as the expression of COX-2 and HIF-1α. Furthermore, pretreatment with inhibitors of COX-2, p38, extracellular signal-regulated kinase, Jun N-terminal kinase, protein kinase C, phosphatidylinositol 3-kinase and nuclear factor-kappaB decreased the expression of nicotine- and LPS-induced HIF-1α and COX-2, as well as the activity of PGE(2) and MMPs. CONCLUSION   These data demonstrate novel mechanisms by which nicotine and LPS promote periodontal tissue destruction, and provide further evidence that HIF-1α is a potential target in periodontal disease associated with smoking and dental plaque.

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.

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.

Genotype analysis of Porphyromonas gingivalis fimA in Korean adults using new primers

Strains of Porphyromonas gingivalis, a periodontopathic bacterium, are classified into six genotypic variants based on nucleotide sequence differences in the fimA gene encoding FimA. A PCR assay using primer sets specific for each genotype has demonstrated that the most predominant fimA genotype in periodontitis patients is type II, which is now commonly referred to as the periodontitis-associated fimA genotype of P. gingivalis. However, the potential for false type II fimA positives caused by cross-hybridization of type II fimA-specific primers with type Ib fimA has complicated the genotyping. A previous study developed new primers that specifically amplified only the DNA fragment of type II fimA. The aim of the present study was to assess the prevalence of P. gingivalis fimA genotypes in Korean adults and to reconfirm the relationship between type II fimA and periodontitis using the new primers. Among 412 Korean adults, P. gingivalis was detected in 97.5 % of patients and 57.8 % of healthy subjects. Type II fimA was the most widely distributed type among healthy and periodontitis subjects. Organisms with types II, Ib and IV fimA had a significant frequency of occurrence in periodontitis subjects. Statistical analysis, however, revealed that a more significant correlation was found between periodontitis and the occurrence of type Ib fimA.

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.