Periodontal Pathogen Adhesion, Cytotoxicity, and Surface Free Energy of Different Materials for an Implant Prosthesis Screw Access Hole.

Background and Objectives: Oral implant restorations are an excellent treatment option for edentulous patients; however, periodontopathogenic bacteria have been found in the microgaps between implant-abutment junctions. Implant designs to limit the microgaps have been extensively studied. However, studies have shown microgaps continue to exist, allowing for the leakage of bacteria into the implant system. Screw access hole materials are used to fill the access hole void. The use of materials with beneficial properties could provide bacterial leakage prevention. The aim of this study was to examine the surface free energy, cytotoxicity, and bacterial adhesion of selected screw access hole materials such as cotton, polytetrafluoroethylene (PTFE) tape, paraffin wax-polyolefin thermoplastic (PF), paraffin wax (Wax), gutta-percha (GP), and caviton EX (CE). Materials and Methods: A sessile drop test was performed to observe the contact angle and calculate the surface free energy of each material in order to determine the level of hydrophobicity. Cytotoxicity was examined in a mouse gingival epithelial cell line for day 1 and day 3. Bacterial adhesion was tested with Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans. Results: PTFE, PF, and wax presented low surface free energies of 19.34, 23.041, and 24.883 mN.m-1, respectively. No cytotoxicity was observed, except for GP and CE. Concurrently, the bacterial adhesion was also the lowest in PTFE and PF. Conclusions: Within the limits of this study, PTFE and PF showed an excellent biocompatibility with few bacterial adhesions. These materials could be potential screw access hole materials in clinical settings.

Patient-specific establishment of bacterial composition within the peri-implant microbiota during the earliest weeks after implant uncovering.

BACKGROUND AND OBJECTIVE: Dysbiosis, a loss of balance in the microbiota, is a potential factor of peri-implantitis. However, compositional change of the peri-implant microbiota soon after implant uncovering is still unknown. In this study, bacterial composition in the peri-implant sulcus was examined to understand the establishment of bacterial composition within the peri-implant microbiota during the earliest weeks after implant uncovering. METHODS: Microbiota samples were collected at weeks 1, 2, 4, and 6 after stage-two surgery. Bacterial DNA was isolated from the samples, and a 16S rRNA gene library was constructed. Sequence reads were obtained using a high-throughput sequencing platform and were taxonomically assigned at the phylum and genus levels. RESULTS: Alpha diversity indices, which did not include taxonomic information, were at similar levels throughout the four time points. At 1 and 2 weeks, the bacterial composition was similar among patients with the predominance of Firmicutes and Proteobacteria. However, the composition was diverse at 4 and 6 weeks and significantly dissimilar to the composition at 1 week. CONCLUSIONS: At 1 week, the peri-implant microbiota was already formed with alpha diversity as high as that at the later time points. However, the bacterial composition was not highly dissimilar among patients at 1 week. The composition changed over the passage of several weeks and was specific for each patient.

Combined in silico analysis identified a putative tooth root formation-related gene, Chd3, which regulates DNA synthesis in HERS01a cells.

There exists a close connection between changes occurring in the teeth and those occurring in the jaw during the evolutionary process. In mammals, the roots of teeth are supported, along with periodontal ligaments and alveolar bones by a unique structure termed the gomphosis. In the present study, we performed combined in silico analysis using the information obtained from various DNA microarrays and identified 19 putative tooth root formation-related genes. Furthermore, quantitative PCR was performed on the candidate genes, Chd3 was confirmed as having sufficient expression levels in the early stage of tooth root formation and increased gene expression toward the middle stage. A high degree of Chd3 gene expression was observed in secretory ameloblasts and Hertwig's epithelial root sheath (HERS), but low expression was observed in developing odontoblasts and stellate reticulum. The CHD3 foci were observed in the nucleus of the HERS01a cells. In addition, knockdown experiments using SiChd3 suggested the involvement of Chd3 in the suppression of DNA synthesis. These results suggested that Chd3 plays a role in DNA synthesis in HERS cells for promoting tooth root development.

Comparison of gingiva-derived and bone marrow mesenchymal stem cells for osteogenesis.

Presently, bone marrow is considered as a prime source of mesenchymal stem cells; however, there are some drawbacks and limitations. Compared with other mesenchymal stem cell (MSC) sources, gingiva-derived mesenchymal stem cells (GMSCs) are abundant and easy to obtain through minimally invasive cell isolation techniques. In this study, MSCs derived from gingiva and bone marrow were isolated and cultured from mice. GMSCs were characterized by osteogenic, adipogenic and chondrogenic differentiation, and flow cytometry. Compared with bone marrow MSCs (BMSCs), the proliferation capacity was judged by CCK-8 proliferation assay. Osteogenic differentiation was assessed by ALP staining, ALP assay and Alizarin red staining. RT-qPCR was performed for ALP, OCN, OSX and Runx2. The results indicated that GMSCs showed higher proliferative capacity than BMSCs. GMSCs turned more positive for ALP and formed a more number of mineralized nodules than BMSCs after osteogenic induction. RT-qPCR revealed that the expression of ALP, OCN, OSX and Runx2 was significantly increased in the GMSCs compared with that in BMSCs. Moreover, it was found that the number of CD90-positive cells in GMSCs elevated more than that of BMSCs during osteogenic induction. Taking these results together, it was indicated that GMSCs might be a promising source in the future bone tissue engineering.

Biomechanical Effect of an Exposed Dental Implant's First Thread: A Three-Dimensional Finite Element Analysis Study.

BACKGROUND The purpose of this study was to assess the effect of different exposure levels of a dental implant's first thread on adjacent bone stress and strain using the finite element analysis method. MATERIAL AND METHODS Three-dimensional models of 2 threaded implants and abutments with a mandibular bone segment were constructed to represent the covered (C) and exposed models. In the exposed models, the implant was first placed in the bone, and rotated around its axis a quarter-turn each time to simulate 4 different levels of first thread exposure at the mid-lingual side: Upper Flank (UF), Thread Crest (TC), Lower Flank (LF), and Thread Root (TR) models. Oblique forces were applied and analysis was performed. RESULTS Maximum compressive stress magnitude and distribution varied according to the exposed thread profile. In the exposed group, peak stress ranged from 136 MPa to 197 MPa in TC and LF models, respectively, compared to 141 MPa in C model. In LF, UF, and C models, peak stress was observed at the mid-lingual side of the crestal region, while in TC and TR models, peak stress shifted distally in accordance with thread profile. However, alveolar bone volumes which exhibited compressive microstrain levels within the physiological loading and maintenance windows were relatively close in all models. CONCLUSIONS Results suggest that the exposed thread profile influences stress and strain outcomes in the adjacent bone; however, this influence is only limited to a small region around the exposed thread.

Maxillary Sinus Floor Augmentation Using Low-Crystalline Carbonate Apatite Granules With Simultaneous Implant Installation: First-in-Human Clinical Trial.

PURPOSE: Carbonate apatite (CO3Ap), an inorganic component of human bone, can be fabricated in chemically pure form from calcium carbonate block via a dissolution-precipitation reaction. A first-in-human clinical trial was conducted in which low-crystalline CO3Ap granules were evaluated for safety and efficacy in sinus floor augmentation and simultaneous implant installation. MATERIALS AND METHODS: Procedures were performed in 8 patients (9 implants) with 2 granule sizes: small (300 to 600 µm) and medium (600 to 1,000 µm). Panoramic radiographic assessment was performed immediately after augmentation, 7 ± 2 months after augmentation, 6 ± 2 months after prosthetic loading, and 12 ± 2 months after prosthetic loading. RESULTS: Postoperative healing was uniformly uneventful, with no abnormal bleeding, pain, or swelling, and all implants achieved successful osseointegration. The mean residual maxillary molar bone height was 5.2 ± 0.8 mm preoperatively and increased to 14.0 ± 1.9 mm after augmentation. Implants 9.0 to 11.5 mm in length were placed. The post-augmentation height decreased to 12.4 ± 1.3 mm at 7 ± 2 months; after prosthetic loading, it decreased to 11.9 ± 0.8 mm at 6 ± 2 months and 11.7 ± 0.6 mm at 12 ± 2 months. No abnormal bone resorption of the augmented areas was observed, and bone height supporting the implants was maintained. The overall implant survival rate was 100%, with no implant failures or complications during the first year. CONCLUSIONS: Low-crystalline CO3Ap granules were useful and safe for sinus floor augmentation and simultaneous implant installation, providing a promising bone substitute for dental implant surgery.

Indirect osteoblast differentiation by liposomal clodronate.

Bisphosphonates impair function of osteoclasts and prevent bone resorption, the mechanism of which has been studied extensively. However, the possible effects of bisphosphonates on chondroblast differentiation and calcium deposition by osteoblasts have only been demonstrated recently. Moreover, cells from monocytic lineage are capable of stimulating osteoblast proliferation. Hence, susceptibility of osteoblasts to various factors requires further investigation. A primary culture of bone marrow-derived stromal cells was treated with liposomal clodronate (0.1, 0.5, or 1.0 mg/ml) or conditioned medium from liposomal clodronate. Liposomal clodronate (0.25 mg) was injected into mouse femur for in vivo experiments. The effects of liposomal clodronate were examined by alkaline phosphatase staining and/or activity assay, and real-time RT-PCR was used for studying the effect on osteogenic gene expression. Administration of liposomal clodronate to bone marrow-derived mesenchymal stromal cell culture enhanced alkaline phosphatase activity and mRNA levels of Runx2 and Dlx5. In addition, conditioned medium from liposomal clodronate also stimulated osteogenic characteristics similar to those of observed in vitro, and the number of exosomes in the conditioned medium was highest when pre-treated with liposomal clodronate. Western blot analysis revealed the presence of RANK proteins in exosomes collected from conditioned medium of liposomal clodronate. Identical observations were obtained in vivo, as liposomal clodronate-injected mouse femur showed increased alkaline phosphatase activity and Runx2 and Dlx5 mRNA expressions, even though the numbers of monocytes and macrophages were reduced. In conclusion, osteoblast differentiation was promoted via soluble RANK-containing exosomes in response to clodronates.

Injectable simvastatin gel for minimally invasive periosteal distraction: In vitro and in vivo studies in rat.

OBJECTIVES: To evaluate whether the subperiosteal injection of simvastatin (SIM) with a novel in situ gel-forming system, SrHA/Alg (strontium hydroxyapatite/alginate), can stimulate vertical bone augmentation in a rat calvarial model. MATERIAL AND METHODS: The SrHA/Alg solution was synthesized and combined with different doses of SIM (0.01, 0.02, 0.1, and 0.2 mg) to form the following groups: (1) SrHA/Alg only, (2) SrHA/Alg/0.01, (3) SrHA/Alg/0.02, (4) SrHA/Alg/0.1, and (5) SrHA/Alg/0.2. The SIM release pattern was analyzed, and rat primary periosteum-derived cell (PDC) responses were investigated. Twenty male Wistar rats were enrolled in the calvarial subperiosteal injection experiment with each animal receiving a 200-µl single subperiosteal injection of SrHA/Alg with different amounts of SIM (0, 0.01, 0.02, and 0.1 mg) incorporated (n = 5). The 0.2 mg dose group was not tested in vivo due to the severe toxicity found in vitro. The new bone formation was assessed histologically and radiologically at 8 weeks. RESULTS: The slow release of SIM was confirmed, and PDC viability decreased in the SrHA/Alg/0.2 group. Alkaline phosphatase positive areas and mineralization areas were significantly greater in the SrHA/Alg/0.01 and SrHA/Alg/0.02 groups (p < .05). The mRNA expression level of Runx2 significantly increased in the SrHA/Alg/SIM-0.02 group by day 7 (p < .05) and significantly higher levels of VEGF were found in the SrHA/Alg/0.01 and SrHA/Alg/0.02 groups at different time points (p < .05). In vivo, no prominent clinical sign of inflammation was observed, and the most significant bone gain was shown in the SrHA/Alg/0.02 group (p < .05). The osteoclast formation within the newly formed bone area was reduced in the SrHA/Alg/0.1 group (p < .05). CONCLUSIONS: When combined with SrHA/Alg system, the 0.02 mg SIM seemed to be the optimal dose to stimulate subperiosteal bone formation without inducing inflammation. This combination may hold potential therapeutic benefits for clinical bone augmentation in a minimally invasive manner.

Re-osseointegration of Dental Implants After Periimplantitis Treatments: A Systematic Review.

PURPOSE: This review considers possible surgical treatment modalities for induced periimplantitis to regain re-osseointegration as reported in the recent literature. MATERIALS AND METHODS: Electronic searches in MEDLINE/PubMed and Google Scholar databases were performed on experimental studies considering induced periimplantitis and attempts to achieve re-osseointegration from 2003 up to December 2016. Conflicts about articles were solved by authors' discussion. RESULTS: A total of 15 studies of 159 were finally included in the review. DISCUSSION: Various implant surface decontamination techniques chemical and/or mechanical have been used either alone or simultaneously with/without guided bone regeneration. Despite the access-flap surgery, it was observed that application of single decontamination measure either chemical or mechanical was not adequate to provide a better treatment outcome. Laser application such as CO2, diode, and Er: YAG has been a new treatment approach used for periimplantitis treatment. Er: YAG laser had showed no implant surface alteration and provided favorable environment for re-osseointegration. CONCLUSION: Promising results were observed in the studies that used combination of bone substitutes together with guided bone regeneration for the regenerative therapy. Regarding implant surfaces, better re-osseointegration was observed with rough implant surfaces rather than smooth ones.

Differences in knowledge related to dental implants between patients with and without a treatment history of dental implants.

OBJECTIVE: This aim of this study was to investigate the differences between patients with and without a treatment history of dental implants by use of a questionnaire survey in order to determine the information that is required for patients undergoing dental implants. MATERIALS AND METHODS: The questionnaires were given to 4512 patients who visited the Tokyo Medical and Dental University Hospital for oral implants between January 2012 and December 2014, and 2972 (66%) valid questionnaires were collected. RESULTS: There were 857 patients with a treatment history of dental implants and 2115 patients without. "Preservation of an adjacent tooth" was the reason that 32% of these patients chose implant therapy, and the patients without treatment history were significantly higher than the patients with one. Significantly, more patients without a treatment history of dental implants selected the after-effects of surgery and pain after surgery as their main concerns for implant therapy compared to those with a treatment history. In the question "Pain after surgery," the patients without treatment history did not know significantly lower than the patients with one. CONCLUSIONS: Patients without a treatment history of dental implants placed more importance on the preservation of healthy teeth. Because patients, in particular those without a treatment history of dental implants, are anxious about surgery, we should provide them with more information on treatment than we already do and explain the risks of treatment to them. To keep the credence between doctors and patients, informed consent and patient education on treatment are six important concerns.

A diversity of peri-implant mucosal thickness by site.

OBJECTIVES: The objective of this study was to examine peri-implant mucosal thickness at different sites of peri-implant crevice around 70 implants placed in 35 patients. MATERIAL AND METHODS: The peri-implant mucosal thickness was defined as distance of the peri-implant mucosal margin and the coronal edge of bone/implant contact and measured using the cast models and dental radiography. RESULTS: The overall mean peri-implant mucosal thickness was 3.6 ± 1.4 mm, wherein maxillary anterior implants, maxillary posterior implants and mandibular posterior implants had significantly different dimensions of median thickness of 4.25, 3.75 and 3.0 mm, respectively. Furthermore, the mesial and distal sites of those positioned implants measured unevenness in the thickness especially in the maxillary posterior region with statistical significance. CONCLUSION: The proposed methodology to evaluate peri-implant mucosal thickness measured with a big variation from overall 3.6 mm with a big variation from 1.6 to 7.0 mm in healthy volunteers. And significant difference was found in the depth among the three regions and, statistically, dispersion of individual peri-implant mucosal thickness resulted in lack of consistency. Although dental implants have been well developed, predictable and prevailing prosthetics, onset of peri-implantitis might be inevitable in some cases. Therefore, establishment of a standardized dimensional diagnosis of peri-implant tissues followed by pathologic ascertainment could be taken into account for the prevention or curing of peri-implantitis.

Ligature induced peri-implantitis: tissue destruction and inflammatory progression in a murine model.

OBJECTIVES: The aim of this study was to investigate tissue destruction and inflammatory progression of ligature-induced peri-implantitis in mice and to establish an alternative murine model of peri-implantitis. MATERIAL AND METHODS: Sixty male C57BL/6NCrSlc mice (4-week-old) were used and the maxillary right first molars were extracted. Eight weeks after extraction, custom-made pure titanium machined screw type implants (0.8 × 1.5 mm) were placed, one implant per animal. Four weeks later, 5-0 silk ligatures were applied around implant necks to induce peri-implantitis. Animals were sacrificed at 0 (before ligature), 7, 14, 21 and 28 days after ligature. Half of the samples were analyzed radiologically and histologically to measure bone level change, osteoclast number, density, and distribution. The rest of the samples was used to determine the relative mRNA expression levels of IL-1 and TNF-α with RT-PCR analysis. RESULTS: Bone levels at all sites (buccal, palatal, mesial, distal) decreased 40-50% significantly 28 days after ligature (P < 0.01). Osteoclast number at all post-ligature time points increased significantly (P < 0.05). However, their density at day 28 decreased significantly compared to that of day 21 (P < 0.05). Accordingly, IL-1 and TNF-α mRNA expression increased significantly at the early time points but decreased significantly at day 28 after ligature (P < 0.05). CONCLUSIONS: Inflammatory response followed by significant peri-implant bone resorption suggested 28 days ligation is sufficient to successfully induce peri-implantitis in the current mice model. This model might open a new avenue to study the pathogenesis and mechanism of peri-implantitis.

Histological and Histomorphometrical Determination of the Biogradation of ß-Tricalcium Phosphate Granules in Maxillary Sinus Floor Augmentation: A Prospective Observational Study.

INTRODUCTION: We have recently used highly pure ß-TCP (beta-tricalcium phosphate) as the bone grafting material to avoid highly invasive autogenous bone grafting. We evaluated the osseoconduction potential of highly pure ß-TCP in sinus augmentation surgery treatment. MATERIALS AND METHODS: The study group comprised 13 patients who underwent maxillary sinus floor augmentation with ß-TCP alone. Seven patients underwent sinus augmentation and implant placement simultaneously. Six patients were treated with a staged approach. Six months after surgery, specimens were obtained from 7 patients (for lateral biopsy) and 6 patients (for vertical biopsy). RESULTS: Histological and histomorphometrical analysis showed a mean bone proportion of 30.8% (vertical) and 12.0% (lateral) for new bone formation and good integration of the ß-TCP. New bone formation was lower in the lateral biopsy specimens than in the vertical. CONCLUSION: Highly pure ß-TCP is a safe bone-grafting material with superior osteoconductive properties. Histologic and radiographic examinations indicate that ß-TCP is slowly resorbed, which results in unresorbed graft material remaining even 6 months after the procedure, and that new bone replacement occurs slowly for approximately 1 year.

Regeneration of rabbit calvarial defects using biphasic calcium phosphate and a strontium hydroxyapatite-containing collagen membrane.

OBJECTIVES: Biphasic calcium phosphate (BCP) composed of 10% hydroxyapatite (HA) and 90% beta-tricalcium phosphate has been developed. Recently, a strontium hydroxyapatite-containing collagen membrane (Sr) was shown to stimulate early bone formation in rat calvarial defects at 4 weeks postoperatively, as compared with a cross-linked collagen membrane, for guided bone regeneration (GBR). The objective of this study was to evaluate these novel biomaterials for GBR in relation to a non-cross-linked collagen membrane (BG) and deproteinized bovine bone mineral (BO). MATERIALS AND METHODS: Twenty New Zealand rabbits were used in this study. Four defects of 7 mm in diameter were created in each rabbit, and three of the defects were treated with BG/BO, Sr/BO, and Sr/BCP. Ten rabbits were sacrificed at 12 and 24 weeks, respectively. Histological and histomorphometric analyses were conducted. Volumetric densities of mineralized new bone (MNB), bone marrow (BM), residual grafting material (RG), and non-mineralized connective tissue (NCT) were determined for each group. RESULTS: After 12 weeks, Sr/BCP yielded more MNB than BG/BO and Sr/BO with no significant difference among the three groups. After 24 weeks, however, Sr/BCP demonstrated significantly more MNB than BG/BO and Sr/BO. Both after 12 and 24 weeks, Sr/BCP showed significantly less RG than BG/BO and Sr/BO. There was a significant increase in MNB in Sr/BCP from 12 to 24 weeks. CONCLUSIONS: In defects grafted with BCP, more MNB was formed while less RG remained, than in defects grafted with BO. The Sr membrane was as effective as BG when comparing Sr/BO with BG/BO.

Effect of Induced Periimplantitis on Dental Implants With and Without Ultrathin Hydroxyapatite Coating.

PURPOSE: The aim of this study was to compare the effect of ligature-induced periimplantitis on dental implants with and without hydroxyapatite (HA) coat. METHODS: Thirty-two dental implants (3.3 mm wide, 13 mm long) with 4 surface treatments (8 implant/group) (M: machined, SA: sandblasted acid etched, S: sputter HA coat and P: plasma-sprayed HA coat) were inserted into canine mandibles. After 12 weeks, oral hygiene procedures were stopped and silk ligatures were placed around the implant abutments to allow plaque accumulation for the following 16 weeks. Implants with the surrounding tissues were retrieved and prepared for histological examination. Bone-to-implant contact (BIC) and implant surfaces were examined using scanning electron microscopy and energy dispersive x-ray spectroscopy. RESULTS: Histological observation revealed marginal bone loss and large inflammatory cell infiltrates in the periimplant soft tissue. Sputter HA implants showed the largest BIC (98.1%) and machined implant showed the smallest values (70.4%). After 28 weeks, thin sputter HA coat was almost completely dissolved, whereas plasma-sprayed HA coat showed complete thickness preservation. CONCLUSION: Thin sputter HA-coated implants showed more bone implant contact and less marginal bone loss than thick HA-coated implants under periimplantitis condition.

Rehabilitation of a Bilateral Maxillectomy Patient with a Free Fibula Osteocutaneous Flap and with an Implant-Retained Obturator: A Clinical Report.

A 47-year-old man underwent surgical resection and reconstruction with a fibula osteocutaneous flap. After the surgery, a surgical obturator was placed and adjusted. After flap healing, a conventional obturator was fabricated with polymethyl methacrylate resin and retained by the anatomical undercuts around the reconstructed fibula bone flap and the posterior part of the defect. As the defect shape changed with time, a second conventional obturator was fabricated and fitted. No further recurrence of myoepithelioma was observed for 2 years, and the patient was satisfied with the obturator during mastication and speech; however, despite having no major complaints, the patient found it difficult to chew on the right side, and the obturator was displaced slightly downward when the mouth was opened wide and shifted when chewing hard and sticky food. Thus, an implant-retained obturator was suggested to provide better retention and stability. Four dental implants were therefore placed into the fibula bone, although one did not osseointegrate because either primary stability was insufficient or overload was affected in the nonloaded implant environment and was replaced. After fitting custom abutments with a magnet, an implant-retained obturator was placed, and the patient was satisfied with the outcome. During 3 years of follow-up, no issues were noted with the implant bodies, abutments, obturator, or reconstructed site. The conventional obturator was displaced slightly downward when the patient opened his mouth wide, and it shifted when chewing hard and sticky food because there was limited fibula bone at the reconstruction site and more available posteriorly. For better retention and stability, the implant-retained obturator was fabricated with a custom abutment and magnetic retention. The patient was satisfied with the results, as improved implant retention increased the stability of the prosthesis. This clinical report describes the rehabilitation of a bilateral maxillectomy patient with a free fibula osteocutaneous flap and an implant-retained obturator. The patient's oral functions were improved when the prosthesis was stabilized by means of dental implants and custom abutments.

Effect of buccal gap distance on alveolar ridge alteration after immediate implant placement: a microcomputed tomographic and morphometric analysis in dogs.

INTRODUCTION: The buccal bone resorption and the deformation of soft tissue contour are major problems of immediate implant treatment. This study aims to examine the changes of alveolar bone and soft tissue after immediate implant placement in different buccal gap distances. MATERIALS AND METHODS: Eight implants were placed randomly in the mandibular premolar sockets of 6 hybrid dogs with 1, 2, and 3 mm buccal gap distances. The dogs were killed after 2 or 4 months for morphometric and microcomputed tomography analyses. DISCUSSION: After 2 months, the 3-mm group had the highest buccal bone volume (BV), buccal bone/soft tissue thickness, and the lowest bone resorption. The wider the buccal gap, the more buccal bone and soft tissue were formed in this experimental setting. After 4 months, the buccal BV had decreased significantly in the 1-mm and the 2-mm groups, whereas the 3-mm group resisted to buccal bone resorption. This difference was more pronounced at the crest. CONCLUSION: The 3 mm is the optimal gap distance among the groups examined, which drastically influences the healing of bone and soft tissue surrounding the implants.

Effects of Abutment Removal and Reconnection on Inflammatory Cytokine Production Around Dental Implants.

OBJECTIVES: The purpose of this study was to examine effects of abutment change on inflammatory cytokine production around implants. MATERIALS AND METHODS: Ten partially edentulous patients with a mean age of 60 years were recruited and divided into 2 groups. External Brånemark implants with anodic oxidized surface were installed and submerged in all patients. In the control group, the healing abutments were delivered at the second surgery, and they were removed more than 3 times till the final prosthesis delivery. In the test group, the final abutments were delivered at the second surgery. At different time points during the treatment, periimplant crevicular fluid was collected, and proinflammatory cytokines (interleukin-1ß [IL-1ß] and tumor necrosis factor [TNF]-α) were measured with enzyme-linked immunosorbent assay. The bone level was measured on the radiograms and clinical indices were also taken. RESULTS: All implants were osseointegrated. In the test group, IL-1ß level and probing depths were less in test group patients compared with the control group patients, whereas TNF-α level and bone level were not different between the groups. CONCLUSION: Although TNF-α and bone levels were not significantly different, delivering final abutment at the second surgery would induce less inflammation in the tissues around the implant.

Coated vs uncoated implants: bone defect configurations after progressive peri-implantitis in dogs.

In this study, hydroxyapatite coated vs uncoated implants were used to evaluate the type and dimensions of bone defects after progressive peri-implantitis in dogs. Thirty-two dental implants with 4 different surfaces-machined (M), sandblasted acid-etched (SA), 1-µm thin sputter hydroxyapatite (HA)-coated (S), and plasma-sprayed HA-coated (P)-were inserted into the mandibles of 4 beagle dogs after extracting all mandibular premolars. Experimental peri-implantitis was induced after 3 months using ligature to allow for plaque accumulation. After 4 months, ligatures were removed and plaque accumulation continued for 5 months (progression period). The open flap surgery demonstrated 3 patterns of peri-implantitis bone defect: (1) Class I defect: represented as circumferential intra-alveolar bone loss; (2) Class II defect: circumferential intra-alveolar defect with supra-alveolar bone loss exposing the implant surface; and (3) Class III defect: represented as circumferential intra-alveolar defect with supra-alveolar bone loss and buccal dehiscence. Class I was the most frequent (62.5%) defect pattern around implant types M, SA, and S; while implant type-P showed a recurring majority of Class II (62.5%). Comparison among the 4 implant groups revealed a significant defect width (DW) in implant type-P relative to other types (P < 0.01). However, no statistically significant differences were noted for defect depth (DD) (P > 0.05). We concluded that the shape and size of peri-implantitis bone defects were influenced by the type and thickness of the HA coat together with the quantity of the available peri-implant bone. Plasma-sprayed HA-coated implants showed larger peri-implant defects than did thin sputter HA-coated implants.

[A clinical investigation of new patients who had already received treatment with dental implants at other clinics in seventeen years].

The purpose of this study was to investigate new patients who had already received treatment with dental implants. The subjects were patients who visited the clinic for oral implants at Tokyo Medical and Dental University Hospital from April 1995 to March 2012. The results were as follows: 1) Of the total number of patients, there were 2,419 patients (14.0%) with dental implants. 2) Of the 2,419 patients, 252 patients (10.4%) had been referred from operating doctors or operating clinics. 3) There were 1,516 (62.7%) patients with complaints related to the implant therapy. 4) There were 1,367 (56.5%) patients who had ill feelings toward their attending doctors. 5) There were 1,112 (46.0%) patients with biological complications. 6) Regarding patients with or without a referral from the doctor who had performed their dental implant, those patients who had been referred showed significantly higher occurrence of loss of implants, neurological symptoms, doctor's recommendation, prosthetic problems, and surgical problems. Almost implant therapies were treated with other treatments for natural teeth, including surgical treatment, prosthetic treatment, periodontal treatment and maintenance. These were too complex to enable the results to be forecast before treatment, therefore unpredictable symptoms often occur in patients with implant therapy. Informed consent including patient education is important, but the results of this study suggest that it is insufficient at present.