Publications by authors named "Young Woo Song"

19 Publications

  • Page 1 of 1

Scanning Electron Microscopic Evaluation of the Internal Fit Accuracy of 3D-Printed Biphasic Calcium Phosphate Block: An Ex Vivo Pilot Study.

Materials (Basel) 2021 Mar 22;14(6). Epub 2021 Mar 22.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul 03722, Korea.

The aim of this study was to assess the internal fit accuracy of a three-dimensional (3D)-printed biphasic calcium phosphate (BCP) block compared with a 3D-milled poly methyl methacrylate (PMMA) block by scanning electron microscope (SEM) analysis. In a total of 20 porcine rib bones, two different types of defects having two adjacent walls and a floor were produced: a defect with a flat floor (flat defect; = 10) and a defect with a concave floor (curved defect; = 10). Each defect was grafted with either the 3D-printed BCP block or the 3D-milled PMMA block fabricated following the computer aided design. The defects were then cut cross-sectionally and evaluated under the SEM. The extents of internal contact and gap were measured and statistically analyzed ( < 0.05). All blocks in both BCP and PMMA groups were successfully fit to the flat and curved defects. The internal contact ratio was significantly higher in the BCP group (flat defect: 0.47 ± 0.10; curved defect: 0.29 ± 0.05) compared with the PMMA group (flat defect: 0.21 ± 0.13; curved defect: 0.17 ± 0.04; < 0.05). The internal gap area was similar between the two groups regardless of the defect types ( > 0.05). The internal fit accuracy of the 3D-printed BCP block was reliable in both the flat and curved defects when compared with the accuracy of the 3D-milled PMMA block.
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http://dx.doi.org/10.3390/ma14061557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8004813PMC
March 2021

Diverse patterns of bone regeneration in rabbit calvarial defects depending on the type of collagen membrane.

J Periodontal Implant Sci 2021 Feb;51(1):40-52

Department of Periodontology, Research Institute of Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Korea.

Purpose: Various crosslinking methods have been introduced to increase the longevity of collagen membranes. The aim of this study was to compare and evaluate the degradation and bone regeneration patterns of 3 collagen membranes.

Methods: Four 8-mm-diameter circular bone defects were created in the calvaria of 10 rabbits. In each rabbit, each defect was randomly allocated to 1) the sham control group, 2) the non-crosslinked collagen sponge (NS) group, 3) the chemically crosslinked collagen membrane (CCM) group, or 4) the biphasic calcium phosphate (BCP)-supplemented ultraviolet (UV)-crosslinked collagen membrane (UVM) group. Each defect was covered with the allocated membrane without any graft material. Rabbits were sacrificed at either 2 or 8 weeks post-surgery, and radiographic and histologic analyses were done.

Results: New bone formed underneath the membrane in defects in the CCM and UVM groups, with a distinctive new bone formation pattern, while new bone formed from the base of the defect in the NS and control groups. The CCM maintained its shape until 8 weeks, while the UVM and NS were fully degraded at 8 weeks; simultaneously, sustained inflammatory infiltration was found in the margin of the CCM, while it was absent in the UVM. In conclusion, the CCM showed longer longevity than the UVM, but was accompanied by higher levels of inflammation.

Conclusions: Both the CCM and UVM showed distinctive patterns of enhancement in new bone formation in the early phase. UV crosslinking can be a biocompatible alternative to chemical crosslinking.
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http://dx.doi.org/10.5051/jpis.2004180209DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920838PMC
February 2021

Efficacy of Local Minocycline Agents in Treating Peri-Implantitis: An Experimental In Vivo Study in Beagle Dogs.

Pharmaceutics 2020 Oct 23;12(11). Epub 2020 Oct 23.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul 03772, Korea.

Background: Local delivery agents (LDA) have the advantage of delivering the antibiotics at high concentrations to the targeted sites. However, the constant flow of gingival crevicular fluids and saliva may restrict their efficacy. Therefore, the drug sustainability and pharmacodynamic properties of any proposed LDA should be evaluated.

Methods: Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Peri-implantitis were experimentally induced using silk-ligatures. Each implant was randomly allocated to receive one of the following four treatments: (i) MC (Chitosan-alginate (CA) minocycline), (ii) MP (CA-without minocycline), (iii) PG (Polyacrylate-glycerin minocycline), and (iv) Control (mechanical debridement only). Mechanical therapies and LDAs were administered into the gingival sulcus two times at a 4-week interval. Drug sustainability as well as clinical, radiographical, and immunohistochemical (IHC) analyses were conducted to evaluate the efficacies of treatments.

Results: Reduced mean probing depth was observed in all of the test groups after the second delivery. A minimal marginal bone level change was observed during the treatment period (MP (-0.06 ± 0.53 mm) to PG (-0.25 ± 0.42 mm)). The distribution of IHC cell marker analysis of all targeted antibodies ranged from 6.34% to 11.33%. All treatment outcomes between the test groups were comparable. A prolonged retention of LDA was observed from CA microspheres (MC and MP) at both administrations ( < 0.017) and prolonged sustainability of bacteriostatic effect was observed from MC compared to PG after the second administration ( < 0.05).

Conclusions: Prolonged retention of CA microspheres was observed and the longer bacteriostatic effect was observed from the MC group. Mechanical debridement with adjunct LDA therapy may impede peri-implantitis progression, however, prolonged drug action did not lead to improved treatment outcome.
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http://dx.doi.org/10.3390/pharmaceutics12111016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7690844PMC
October 2020

Core Ossification of Bone Morphogenetic Protein-2-Loaded Collagenated Bone Mineral in the Sinus.

Tissue Eng Part A 2020 Oct 19. Epub 2020 Oct 19.

Clinic of Reconstructive Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.

The objective of this study was to investigate release kinetics and ossification patterns of bone morphogenetic protein-2-soaked collagenated porcine bone mineral (BMP-2/CPBM) in rabbit sinuses. Release kinetics of BMP-2/CPBM was determined up to 56 days. In 16 rabbits, BMP-2/CPBM (BMP group) and CPBM alone (control group) were bilaterally grafted in both sinuses. After 4 ( = 8) and 12 ( = 8) weeks, radiographic and histologic analyses were performed. Approximately 40% of BMP-2 was released from CPBM during 3 days ; release maintained at a reduced level until day 56. , new bone formation in BMP group was dominant at the center and decreased toward the borders of the sinus, while it mainly possessed close to the sinus membrane and basal bone in control group. At the center, significantly more new bone was found in BMP group compared to control group at 4 weeks (29.14% vs. 16.50%;  < 0.05). The total augmented volume of BMP group was significantly greater than control group at 4 (370.13 mm vs. 299.32 mm) and 12 (400.40 mm vs. 290.10 mm) weeks ( < 0.05). In conclusion, BMP-2/CPBM demonstrated a core ossification with a greater augmented volume and new bone formation in the center of the sinus compared to CPBM alone. Impact statement The center of the augmented maxillary sinus tends to show a slower and inferior new bone formation compared to the sites near the sinus membrane and basal bone. In this study, bone morphogenetic protein-2 (BMP-2) loaded onto collagenated porcine bone mineral (CPBM) resulted in a greater augmented volume and new bone formation at the center of the grafted sinus compared to CPBM alone. Therefore, BMP-2-added CPBM in maxillary sinus augmentation may potentially be beneficial to the clinicians, in terms of accelerating the new bone formation at the center area where the apical half of the implant fixture usually places.
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http://dx.doi.org/10.1089/ten.TEA.2020.0151DOI Listing
October 2020

Clinical factors influencing implant positioning by guided surgery using a nonmetal sleeve template in the partially edentulous ridge: Multiple regression analysis of a prospective cohort.

Clin Oral Implants Res 2020 Dec 22;31(12):1187-1198. Epub 2020 Sep 22.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Korea.

Objective: To determine the positional accuracy of implants placed with a three-dimensionally printed template having nonmetal sleeves and to determine the contributing factors to observed deviations.

Materials And Methods: One hundred and eighty-seven implants placed in 72 patients were analyzed. Presurgical intraoral scans and cone-beam computed tomography images obtained before and after surgery were superimposed, and vertical, angular, platform, and apex deviations were measured between the virtually planned and actually placed positions. A multiple linear regression model was designed for identifying the contributing factors. Statistical significance was set at p < .05, with Bonferroni correction if necessary (p < .0167).

Results: A total of 187 implants demonstrated deviations of 0.65 [0.56, 0.75] mm (mean [95% confidence interval]) vertically, 3.59° [3.30°, 3.89°] angularly, 1.16 [1.04, 1.28] mm at platform, and 1.50 [1.36, 1.65] mm at apex. Implants placed in the mandible showed larger angular, platform, and apex deviations compared with those in the maxilla (p = .049, p = .014 and p = .003, respectively). Implants placed at the third or fourth nearest sites from the most-distal tooth had larger deviations than those placed at the first or second nearest sites, in vertical, platform, and apical aspects (p = .015, p = .011 andp = .018, respectively). This was only applicable to free-ending-supported templates (p < .0167), and anchor pin-supported free-ending templates (p < .0167).

Conclusion: Using a three-dimensionally printed surgical template with a nonmetal sleeve in the partial edentulous ridge resulted in larger deviations in implants placed in the mandible or distal free-end third or fourth nearest site.
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http://dx.doi.org/10.1111/clr.13664DOI Listing
December 2020

Dimensional changes of the maxillary sinus augmented with a collagenated synthetic bone block or synthetic bone particulates: A pre-clinical study in rabbits.

J Clin Periodontol 2020 11 21;47(11):1416-1426. Epub 2020 Sep 21.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, South Korea.

Objective: To compare the efficacy of a collagenated synthetic bone substitute (C-SBS) to a particulated synthetic bone substitute (P-SBS) in volume maintenance and new bone formations in a rabbit sinus model.

Materials And Methods: Either C-SBS or P-SBS was grafted in both sinuses of 16 rabbits. Four (N = 8) or 12 (N = 8) weeks after the surgery, total augmented volume (TAV) and area (TAA), as well as new bone volume (NBV) and area (NBA), were statistically compared by radiographic and histomorphometric analyses (p < .05).

Results: The differences in TAV, NBV, TAA and NBA between C-SBS and P-SBS groups at 4 weeks were not statistically significant. The TAV (267.13 ± 62.08 vs. 200.18 ± 40.32 mm ) and NBV (103.26 ± 10.50 vs. 71.10 ± 7.58 mm ) in group C-SBS were significantly higher than in group P-SBS at 12 weeks (p < .05). The TAA (19.36 ± 2.88 vs. 14.48 ± 2.08 mm ) and NBA (5.43 ± 1.20 vs. 3.76 ± 0.78 mm ) in group C-SBS were significantly higher than in group P-SBS at 12 weeks (p < .05).

Conclusions: Collagenated synthetic bone substitute grafted in rabbit sinuses demonstrated more favourable outcomes across all outcome measures compared to P-SBS at 12 weeks.
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http://dx.doi.org/10.1111/jcpe.13363DOI Listing
November 2020

Soft Tissue Dimensions Following Tooth Extraction in the Posterior Maxilla: A Randomized Clinical Trial Comparing Alveolar Ridge Preservation to Spontaneous Healing.

J Clin Med 2020 Aug 10;9(8). Epub 2020 Aug 10.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul 03722, Korea.

Background: To assess the soft tissue dimension following tooth extraction and alveolar ridge preservation in the posterior maxilla compared to spontaneous healing.

Methods: Thirty-five patients randomly assigned to alveolar ridge preservation (ARP) and spontaneous healing (SH) after maxillary molar extraction. The crestal, buccal, and palatal gingival thickness at 6 months was measured around virtually placed implant fixtures using superimposed cone-beam computed tomography and intraoral scan taken at 6 months. Buccal mucogingival junction (MGJ) level change over 6 months was estimated using intraoral scans obtained at suture-removal and 6 months.

Results: The crestal gingiva was significantly thinner in group ARP (-1.16 mm) compared to group SH ( < 0.05). The buccal and palatal gingiva was significantly thinner at the implant shoulder (IS) level in group ARP (buccal: -0.75 mm; palatal: -0.85 mm) compared to group SH ( < 0.05). The thickness at 2 mm below the IS of both sides and the buccal MGJ level change were similar in both groups ( > 0.05).

Conclusions: ARP in the posterior maxilla resulted in a thinner soft tissue on top of and at the prospective level of the implant shoulder at 6 months. The buccal MGJ level changed minimal for 6 months in both groups.
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http://dx.doi.org/10.3390/jcm9082583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464084PMC
August 2020

Locally Applied Slow-Release of Minocycline Microspheres in the Treatment of Peri-Implant Mucositis: An Experimental In Vivo Study.

Pharmaceutics 2020 Jul 16;12(7). Epub 2020 Jul 16.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul 03772, Korea.

Background: The objective of this is preclinical investigation was to evaluate the differential drug sustainability and pharmacodynamic properties of two local minocycline microsphere carriers: chitosan-coated alginate (CA) and poly(meth)acrylate-glycerin (PG).

Methods: Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Each implant was randomly assigned to receive one of the following four treatments: (i) CA (CA-based minocycline), (ii) placebo (CA substrate without minocycline), (iii) PG (PG-based minocycline) and (iv) control (mechanical debridement only). After inducing peri-implant mucositis, the randomly assigned treatments were administered into the gingival sulcus twice at a 4-week interval using a plastic-tipped syringe. Drug sustainability and pharmacodynamic (clinical, radiographical and cell marker intensity) evaluations were performed after each administration.

Results: The CA microspheres remained longer around the healing abutment compared to the PG microspheres at both administrations and a longer bacteriostatic effect was observed from CA (7.0 ± 5.7 days) compared to PG (1.2 ± 2.6 days). The efficacy of the applied therapies based on clinical, radiographical and histological analyses were comparable across all treatment groups.

Conclusions: CA microspheres showed longer carrier and bacteriostatic effect sustainability when compared to PG microspheres, however, longer drug sustainability did not lead to improved treatment outcomes.
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http://dx.doi.org/10.3390/pharmaceutics12070668DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407908PMC
July 2020

Effects of soft tissue grafting prior to orthodontic treatment on preventing gingival recession in dogs.

J Periodontal Implant Sci 2020 Aug 12;50(4):226-237. Epub 2020 May 12.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Korea.

Purpose: This study was conducted to assess the efficacy of prophylactic gingival grafting in the mandibular anterior labial area for preventing orthodontically induced gingival recession.

Methods: Eight mongrel dogs received gingival graft surgery at the first (I1) and third (I3) mandibular incisors on both sides based on the following group allocation: AT group (autogenous connective tissue graft on I1), AT-control group (contralateral side in the AT group), CM group (xenogeneic cross-linked collagen matrix graft on I3) and CM-control group (contralateral side in the CM group). At 4 weeks after surgery, 6 incisors were splinted and proclined for 4 weeks, followed by 16 weeks of retention. At 24 weeks after surgery, casts were made and compared with those made before surgery, and radiographic and histomorphometric analyses were performed.

Results: Despite the proclination of the incisal tip (by approximately 3 mm), labial gingival recession did not occur. The labial gingiva was thicker in the AT group (1.85±0.50 mm vs. 1.76±0.45 mm, >0.05) and CM group (1.90±0.33 mm vs. 1.79±0.20 mm, >0.05) than in their respective control groups.

Conclusions: The level of the labial gingival margin did not change following labial proclination of incisors in dogs. Both the AT and CM groups showed enhanced gingival thickness.
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http://dx.doi.org/10.5051/jpis.2000420021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443382PMC
August 2020

Oral Fluid Biomarkers for Diagnosing Gingivitis in Human: A Cross-Sectional Study.

J Clin Med 2020 Jun 3;9(6). Epub 2020 Jun 3.

Department of Periodontology, Research Institute of Periodontal Regeneration, Yonsei University College of Dentistry, Seoul 120-749, Korea.

Diagnoses based on oral fluid biomarkers have been introduced to overcome limitations of periodontal probe-based diagnoses. Diagnostic ability of certain biomarkers for periodontitis have been identified and widely studied, however, such studies targeting gingivitis is scarce. The aims of this study were to determine and compare the efficacies and accuracies of eight biomarkers in diagnosing gingivitis with the aid of receiver operating characteristic (ROC) curves. The probing depth (PD), clinical attachment loss (CAL), bleeding on probing (BOP), gingival index (GI), and plaque index (PI) were examined in 100 participants. Gingival crevicular fluid was collected using paper points, and whole-saliva samples were collected using cotton roll. Samples were analyzed using enzyme-linked immunosorbent assay kits for the different biomarkers. The levels of matrix metalloproteinase (MMP)-8, MMP-9, lactoferrin, cystatin C, myeloperoxidase (MPO), platelet-activating factor, cathepsin B, and pyridinoline cross-linked carboxyterminal telopeptide of type I collagen were analyzed. MPO and MMP-8 levels in saliva were strongly correlated with gingivitis, with Pearson's correlation coefficients of 0.399 and 0.217, respectively. The area under the curve (AUC) was largest for MMP-8, at 0.814, followed by values of 0.793 and 0.777 for MPO and MMP-9, respectively. The clinical parameters of GI and PI showed strong correlations and large AUC values, whereas PD and CAL did not. MMP-8 and MPO were found to be effective for diagnosing gingivitis. Further investigations based on the results of this study may identify clinically useful biomarkers for the accurate and early detection of gingivitis.
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http://dx.doi.org/10.3390/jcm9061720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356847PMC
June 2020

Immediate versus delayed application of bone morphogenetic protein-2 solution in damaged extraction sockets: a preclinical in vivo investigation.

Clin Oral Investig 2021 Jan 26;25(1):275-282. Epub 2020 May 26.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, 50-1, Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.

Objective: To compare the clinical, radiographic, and histological healing patterns between the immediate and delayed applications of bone morphogenetic protein-2 (BMP-2) in damaged extraction sockets in dogs.

Materials And Methods: The distal roots of the fourth premolars of the mandible were extracted bilaterally in five beagle dogs, and buccal bone defects (4 mm wide and 9 mm high) were surgically created. Collagenated biphasic calcium phosphate (CBCP) soaked for 10 min in 100 μL of BMP-2 solution was applied immediately to the defect site in the control group. In the test group, the BMP-2 solution of same dose was injected into the grafted site 2 weeks after grafting with a saline-soaked CBCP. The dogs were sacrificed 2 weeks later. Clinical, histological, and radiographic analyses were followed.

Results: Swelling and inflammatory reactions were predominantly observed in the control group at 2 weeks. The area of new bone formation was significantly larger in the control group compared with the test group (10.8 ± 7.0 mm [mean ± SD] and 6.3 ± 3.1 mm, respectively; p = 0.043). No significant difference was found in ridge width at 2 mm, 4 mm and 6 mm below the lingual bone crest between the control (2.6 ± 1.0 mm, 3.2 ± 0.9 mm and 4.5 ± 0.5 mm, respectively) and test group (3.3 ± 1.0 mm, 3.7 ± 1.3 mm and 4.2 ± 1.0 mm; all p > 0.05).

Conclusions: Delayed application of BMP-2 2 weeks after surgery did not show any advantage over immediate application of BMP-2 in terms of new bone formation.

Clinical Relevance: This study suggests that it might be better to apply BMP-2 immediately in alveolar ridge preservation, instead of delayed application, in order to enhance new bone formation.
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http://dx.doi.org/10.1007/s00784-020-03362-wDOI Listing
January 2021

Bioactive characteristics of an implant surface coated with a pH buffering agent: an study.

J Periodontal Implant Sci 2019 Dec 4;49(6):366-381. Epub 2019 Nov 4.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Korea.

Purpose: The purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation.

Methods: Titanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted.

Results: In both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (=0.000 and =0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (=0.040, =0.000, and =0.000, respectively).

Conclusions: SOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.
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http://dx.doi.org/10.5051/jpis.2019.49.6.366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920039PMC
December 2019

Clinical benefits of ridge preservation for implant placement compared to natural healing in maxillary teeth: A retrospective study.

J Clin Periodontol 2020 03 7;47(3):382-391. Epub 2020 Jan 7.

Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, South Korea.

Aim: The purpose of this retrospective study was to determine clinical benefits of ridge preservation in terms of surgical invasiveness of implant placement compared to natural healing in the maxilla.

Materials & Methods: This study included 178 patients with 206 implants placed at ridge-preserved sites and 493 patients with 656 implants placed at naturally healed sites in maxillary anterior and posterior regions. Patient- and implant-related data were collected from electronic dental records including additional augmentation procedures performed before or during implant placement and surgical complications. Cumulative survival rate was assessed using Kaplan-Meier method. The annual peri-implant marginal bone loss between the two groups was compared using the Mann-Whitney U test.

Results: The follow-up period was 24.4 ± 18.1 months (mean ± standard deviation) for ridge-preserved sites and 45.7 ± 29.6 months for naturally healed sites. Sinus augmentation was performed at similar frequencies in the two groups, but lateral approach was applied significantly more at naturally healed sites (37.2%) than ridge-preserved sites (8.3%, p ≤ .001). There was no intergroup difference in the cumulative survival rate or annual peri-implant marginal bone loss.

Conclusion: Ridge preservation can be clinically beneficial for minimizing the invasiveness of implant surgery by simplifying the procedure when sinus augmentation is expected in the maxilla.
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http://dx.doi.org/10.1111/jcpe.13231DOI Listing
March 2020

Histologic analysis following grafting of damaged extraction sockets using deproteinized bovine or porcine bone mineral: A randomized clinical trial.

Clin Oral Implants Res 2020 Jan 27;31(1):93-102. Epub 2019 Nov 27.

Department of Periodontology, Research Institute for Periodontal regeneration, Yonsei University College of Dentistry, Seoul, Korea.

Objectives: This study histologically analyzed biopsy samples obtained from sites of damaged extraction socket grafting using deproteinized bovine bone mineral (DBBM) or deproteinized porcine bone mineral (DPBM) with coverage by a collagen membrane.

Material And Methods: One hundred patients participated in this randomized controlled clinical trial of extraction socket grafts performed in cases of periodontally compromised teeth. All participants were blinded to their group allocations, and each material was grafted with coverage by collagen membranes after extraction of the tooth and removal of granulation tissue. At implant placement at 4 months, a biopsy was harvested at the implant site using a trephine was analyzed histologically.

Results: Eighty-five biopsy samples were acquired, of which 81 were finally included in the histologic analysis (42 in DBBM and 39 in DPBM group). Both DBBM and DPBM groups showed comparable proportions of residual biomaterial (12.37 ± 5.67% and 12.21 ± 5.75%, respectively), newly formed bone (15.07 ± 10.52% and 18.47 ± 11.47%, respectively), and nonmineralized tissue (72.56 ± 10.07% and 71.55 ± 15.47%, respectively). There were no significant differences in these histologic parameters between the two groups with different biomaterials.

Conclusion: Comparable histologic bone formation was found in both socket grafted groups with DBBM or DPBM covered by collagen membranes in periodontally damaged extraction sockets. However, a wide variation in new bone formation was found after 4 months of postsurgical healing and a tendency of higher new bone formation was shown at damaged sockets that had an intact unilateral residual wall regardless of buccal or lingual side.
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http://dx.doi.org/10.1111/clr.13557DOI Listing
January 2020

Alveolar ridge preservation in the posterior maxilla reduces vertical dimensional change: A randomized controlled clinical trial.

Clin Oral Implants Res 2019 Jun 13;30(6):515-523. Epub 2019 May 13.

Department of Fixed and Removable Prosthodontics and Dental Material Science, Dental School, University of Zurich, Zurich, Switzerland.

Objectives: To test whether or not alveolar ridge preservation reduces vertical changes in the posterior maxilla compared to spontaneous healing following tooth extraction.

Materials And Methods: Forty subjects requiring extraction of maxillary posterior teeth with root apices protruding into the maxillary sinus floor were consecutively enrolled. Patients were randomly assigned to either one of two surgical interventions: an alveolar ridge preservation procedure using collagenated bovine bone mineral and a resorbable collagen membrane (test) or no grafting (control). Cone-beam computed tomographies were taken immediately and at 6 months after surgery, prior to dental implant placement.

Results: Based on radiographic data, the level of the sinus floor remained stable over time (baseline to 6 months) in the test group (-0.14 mm [-0.31, -0.02]). In the control group, the sinus floor level shifted more coronally (-1.16 mm [-1.73, -0.61]) than the test group (p < 0.05). The test group demonstrated a significantly larger residual bone height than the control group at 6 months (7.30 mm [6.36, 8.20] vs. 4.83 mm [3.94, 5.76], respectively, p < 0.05). Implant placement without any additional sinus augmentation procedure was performed in 42.9% of test group cases, whereas in all of the subjects in the control group an additional augmentation procedure was needed (100% of the cases).

Conclusion: Alveolar ridge preservation in the posterior maxilla maintained the vertical bone height more efficiently and resulted in less need for sinus augmentation procedures at 6 months compared to spontaneous healing.
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http://dx.doi.org/10.1111/clr.13436DOI Listing
June 2019

Soft tissue substitutes to increase gingival thickness: Histologic and volumetric analyses in dogs.

J Clin Periodontol 2019 01 29;46(1):96-104. Epub 2018 Nov 29.

Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.

Objectives: To evaluate the histologic and volumetric changes of gingival tissues following grafting with collagen-based matrices at labial aspect of teeth in canines.

Materials And Methods: Gingival augmentation was performed in the mandibular incisor area using two types of xenogeneic cross-linked collagen matrices (CCMs), bovine CCM for BCCM group and porcine CCM for PCCM group, whereas the contralateral sides remained untreated (B-control group and P-control group). Descriptive histology, histometric and volumetric analyses were performed after 12 weeks. For statistical comparison between each test group and respective control group, paired t test was used for histometric analysis, and repeated-measured analysis of variance was used for volumetric analysis (p < 0.05).

Results: An increased number of rete pegs and an enhanced formation of new blood vessels were observed at both grafted sites compared to the corresponding control sites. There was statistically significant gain of horizontal thickness only in BCCM group (1.36 ± 0.27 mm vs. 1.26 ± 0.34 mm; p < 0.05) compared to the B-control groups.

Conclusion: BCCM was effective for gingival augmentation in terms of horizontal thickness at the labial aspect of teeth at 12 weeks post-surgery.
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http://dx.doi.org/10.1111/jcpe.13034DOI Listing
January 2019

Optically bifacial thin-film wire-grid polarizers with nano-patterns of a graded metal-dielectric composite layer.

Opt Express 2008 Oct;16(21):16867-76

Materials Lab, Corporate R&D Center, Samsung SDI Co Ltd, Yongin, Gyeonggi 446-577, South Korea.

We report on the concept of a thin film wire-grid polarizer (WGP) with optically dual characteristics by introducing a nano-patterned graded metal-dielectric composite-material layer. The Ti-SiO(2) composite layer with a depth profile of a gradually-varied composition ratio shows an absorptive feature due to the elimination of an optical interface between a metal and a glass substrate, while the metal side of the WGP gives a reflective character. The unprecedented optically-bifacial thin-film WGP with the 144 nm-period straight-line patterns of a 100 nm-thick Ti-SiO(2) composite layer and a 185 nm-thick Al layer shows the exceptionally low reflectance below 15 % from the absorptive side and the high polarization extinction ratio (PER) of over 500 at 550 nm, which is acceptable for use as various display applications such as AMOLEDs and LCDs.
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October 2008

Weak-microcavity organic light-emitting diodes with improved light out-coupling.

Opt Express 2008 Aug;16(17):12632-9

Department of Physics, KAIST, Daejeon 305-701, Korea.

We propose and demonstrate weak-microcavity organic light-emitting diode (OLED) displays with improved light-extraction and viewing-angle characteristics. A single pair of low- and high-index layers is inserted between indium tin oxide (ITO) and a glass substrate. The electroluminescent (EL) efficiencies of discrete red, green, and blue weak-microcavity OLEDs are enhanced by 56%, 107%, and 26%, respectively, with improved color purity. Moreover, full-color passive-matrix bottom-emitting OLED displays are fabricated by employing low-index layers of two thicknesses. As a display, the EL efficiency of white color was 27% higher than that of a conventional OLED display.
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http://dx.doi.org/10.1364/oe.16.012632DOI Listing
August 2008

Far-field radiation of photonic crystal organic light-emitting diode.

Opt Express 2005 Jul;13(15):5864-70

Utilizing the near- to far-field transformation based on the 3-D finite difference time domain (FDTD) method and Fourier transformation, the far-field profile of a photonic crystal organic light emitting diode is studied to understand the viewing angle dependence. The measured far-field profiles agree well with those of the simulation. The enhancement of the extraction efficiency in excess of 60% is observed for the optimized photonic crystal pattern.
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http://dx.doi.org/10.1364/opex.13.005864DOI Listing
July 2005