Nikolaos Donos

Early osseointegration to hydrophilic and hydrophobic implant surfaces in humans

OBJECTIVE To evaluate the rate and degree of osseointegration at chemically modified moderately rough, hydrophilic (SLActive) and moderately rough, hydrophobic (SLA) implant surfaces during early phases of healing in a human model. MATERIAL AND METHODS The devices used for this study of early healing were 4 mm long and 2.8 mm in diameter and had either an SLActive chemically modified or a moderately rough SLA surface configuration. These devices were surgically installed into the retro-molar area of 49 human volunteers and retrieved after 7, 14, 28 and 42 days of submerged healing. A 5.2-mm-long specially designed trephine with a 4.9 mm inside diameter, allowing the circumferential sampling of 1 mm tissue together with the device was applied. Histologic ground sections were prepared and histometric analyses of the tissue components (i.e. old bone, new bone, bone debris and soft tissue) in contact with the device surfaces were performed. RESULTS All device sites healed uneventfully. All device surfaces were partially coated with bone debris. A significant fraction of this bone matrix coating became increasingly covered with newly formed bone. The process of new bone formation started already during the first week in the trabecular regions and increased gradually up to 42 days. The percentage of direct contact between newly formed bone and the device (bone-to-implant contact) after 2 and 4 weeks was more pronounced adjacent to the SLActive than to the SLA surface (14.8% vs. 12.2% and 48.3% vs. 32.4%, respectively), but after 42 days, these differences were no longer evident (61.6% vs. 61.5%). CONCLUSION While healing showed similar characteristics with bone resorptive and appositional events for both SLActive and SLA surfaces between 7 and 42 days, the degree of osseointegration after 2 and 4 weeks was superior for the SLActive compared with the SLA surface.

Oxidative Stress, Systemic Inflammation, and Severe Periodontitis

Periodontal infections have been associated with a state of chronic inflammation. To ascertain whether severe periodontitis and its treatment are associated with oxidative stress, we recruited 145 cases (periodontitis) and 56 controls in a case-control study. A further pilot intervention study of 14 cases (periodontal therapy) was performed. Blood samples were taken at baseline (case-control) and 1, 3, 5, 7, and 30 days after treatment (intervention). Diacron-reactive oxygen metabolites (D-ROM), anti-oxidant potential, C-reactive protein (CRP), interleukin-6, and lipid profiles were determined with high-sensitivity assays in serum. Patients with severe periodontitis exhibited higher D-ROM levels (P < 0.001) and lower total anti-oxidant capacity (P < 0.001) compared with healthy control individuals. These findings were independent of age, gender, smoking habits, ethnicity, and standard lipids differences. D-ROM levels were positively correlated with CRP (R = 0.4, P < 0.001) and clinical periodontal parameters (R = 0.20, P < 0.05). Acute increases of D-ROM (P < 0.01) were observed following periodontal therapy. Analysis of these data suggests a positive association between severe periodontitis and oxidative stress.

Clinical outcomes of implants following lateral bone augmentation: systematic assessment of available options (barrier membranes, bone grafts, split osteotomy)

OBJECTIVE To compare the clinical outcomes related to implants following lateral augmentation procedures (GBR, bone grafts, split osteotomy) with implants placed in pristine sites. MATERIAL AND METHODS A systematic review of all prospective studies of implants placed simultaneously or as a second surgery following lateral augmentation compared with implants placed in pristine bone with 6 months of loading was performed. RESULTS From 435 potentially relevant publications, 125 full-text publications were screened and four were identified as fulfilling the inclusion criteria. Three studies compared implants placed with simultaneous GBR or with a bone substitute and one with autogenous bone graft as a staged procedure. The implant survival at the augmented sites irrespective of the procedure used varied from 91.7% to 100% and from 93.2% to 100% at the control sites for a period between 12 and 59.1 months. CONCLUSIONS Within the limits of the systematic review there was evidence that the evaluated augmentation techniques result in similar implant survival between augmented and pristine sites. The small number of retrieved studies fulfilling the inclusion criteria limited the conclusions regarding the success of the augmentation and its effect on the survival of the implants. Properly designed randomized controlled clinical trials on this topic are needed.

Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine-derived xenograft: a randomized, controlled clinical trial

OBJECTIVES The aim of this randomized, controlled clinical trial was to compare the potential of a synthetic bone substitute or a bovine-derived xenograft combined with a collagen membrane to preserve the alveolar ridge dimensions following tooth extraction. METHODS Twenty-seven patients were randomized into two treatment groups following single tooth extraction in the incisor, canine and premolar area. In the test group, the alveolar socket was grafted with Straumann Bone Ceramic (SBC), while in the control group, Bio-Oss deproteinized bovine bone mineral (DBBM) was applied. In both groups, a collagen barrier was used to cover the grafting material. Complete soft tissue coverage of the barriers was not achieved. After 8 months, during re-entry procedures and before implant placement, the horizontal and vertical dimensions of the residual ridge were re-evaluated and trephine biopsies were performed for histological analysis in all patients. RESULTS Twenty-six patients completed the study. The bucco-lingual dimension of the alveolar ridge decreased by 1.1+/-1 mm in the SBC group and by 2.1+/-1 in the DBBM group (P<0.05). Both materials preserved the mesio-distal bone height of the ridge. No differences in the width of buccal and palatal bone plate were observed between the two groups. The histological analysis showed new bone formation in the apical part of the biopsies, which, in some instances, was in direct contact with both SBC and DBBM particles. The coronal part of the biopsies was occupied by a dense fibrous connective tissue surrounding the SBC and DBBM particles. CONCLUSION Both biomaterials partially preserved the width and the interproximal bone height of the alveolar ridge.

Systematic review of implant outcomes in treated periodontitis subjects

OBJECTIVES To determine implant outcomes in partially dentate patients who have been treated for periodontitis compared with periodontally healthy patients. MATERIAL AND METHODS All longitudinal studies (until March 2006) of endosseous dental implants of at least 6 months of loading were searched. Studies presented with one or more of the outcome measures (implant survival, success, bone-level change, peri-implantitis) were included. Screening, data abstraction and quality assessment were conducted independently and in duplicate. RESULTS From 4448 citations, 546 full-text papers were screened and nine studies were included. Overall, the non-periodontitis patients demonstrated better outcomes than treated periodontitis patients. However, the strength of evidence showed that the studies included were at a medium to high risk of bias, with lack of appropriate reporting and analysis of outcomes plus lack of accounting for confounders, especially smoking. Furthermore, the studies showed variability in the definitions of treated and non-periodontitis, outcome criteria and quality of supportive periodontal therapy. Meta-analysis could not be performed due to heterogeneity of the chief study characteristics. CONCLUSIONS There is some evidence that patients treated for periodontitis may experience more implant loss and complications around implants than non-periodontitis patients. Evidence is stronger for implant survival than implant success; methodological issues limit the potential to draw robust conclusions.

The effect of diabetes mellitus on osseous healing

Diabetes mellitus and, in particular, type 1 diabetes has been associated with impaired osseous wound healing properties. The scope of the present review is to discuss the clinical evidence supporting a higher rate of complications during fracture healing in diabetic patients and the histological evidence indicating impaired potential for intramembranous and endochondral ossification in the presence of uncontrolled experimental diabetes. The article further provides a synthesis of our current understanding of the plausible molecular mechanisms underlying the diabetic bone healing pathophysiology and of the role of insulin treatment in promoting osseous healing in the diabetic status.

Periodontal health status and bacteraemia from daily oral activities: systematic review/meta‐analysis

AIM The aim of this study was to investigate the robustness of the observations on the influence of oral hygiene, gingival and periodontal status on the development of bacteraemia from everyday oral activities (B-EOA), analysing its prevalence, duration, magnitude and bacterial diversity. MATERIAL AND METHODS This systematic review/meta-analysis complies with PRISMA reporting guidelines. MEDLINE-PubMed, the Cochrane Library and Embase were explored for detecting studies on B-EOA. RESULTS There were 290 potentially eligible articles, of which 12 article on B-EOA fulfilled the inclusion criteria and were processed for data extraction (seven on toothbrushing, one on dental flossing and four on chewing). Evaluating the influence of plaque and gingival indices on the prevalence of bacteraemia following toothbrushing, the pooled odds ratios were 2.61 [95% confidence interval (CI) = 1.45-4.69] and 2.77 (95% CI = 1.50-5.11), respectively. None of five studies on bacteraemia following dental flossing and chewing revealed a statistically significant association between oral hygiene, gingival or periodontal status and the development of bacteraemia. CONCLUSIONS Meta-analysis showed that plaque accumulation and gingival inflammation scores significantly increased the prevalence of bacteraemia following toothbrushing. However, systematic review showed no relationship between oral hygiene, gingival and periodontal status and the development of B-chewing, and there is no evidence that gingival and periodontal health status affects B-flossing.

Gene expression profile of osseointegration of a hydrophilic compared with a hydrophobic microrough implant surface

OBJECTIVES To compare the gene expression profile of osseointegration associated with a moderately rough and a chemically modified hydrophilic moderately rough surface in a human model. MATERIAL AND METHODS Eighteen solid screw-type cylindrical titanium implants, 4 mm long and 2.8 mm wide, with either a moderately rough (SLA) or a chemically modified moderately rough (SLActive) surface were surgically inserted in the retromolar area of nine human volunteers. The devices were removed using a trephine following 4, 7 and 14 days of healing. The tissue surrounding the implant was harvested, total RNA was extracted and microarray analysis was carried out to identify the differences in the transcriptome between the SLA and SLActive surfaces at days 4, 7 and 14. RESULTS There were no functionally relevant gene ontology categories that were over-represented in the list of genes that were differentially expressed at day 4. However, by day 7, osteogenesis- and angiogenesis-associated gene expression were up-regulated on the SLActive surface. Osteogenesis and angiogenesis appeared to be regulated by BMP and VEGF signalling, respectively. By day 14, VEGF signalling remains up-regulated on the SLActive surface, while BMP signalling was up-regulated on the SLA surface in what appeared to be a delayed compensatory response. Furthermore, neurogenesis was a prominent biological process within the list of differentially expressed genes, and it was influenced by both surfaces. CONCLUSIONS Compared with SLA, SLActive exerts a pro-osteogenic and pro-angiogenic influence on gene expression at day 7 following implant insertion, which may be responsible for the superior osseointegrative properties of this surface.

The role of bone debris in early healing adjacent to hydrophilic and hydrophobic implant surfaces in man

OBJECTIVE To evaluate morphologically and morphometrically the sequential healing and osseointegration events at moderately rough implant surfaces with and without chemical modification. Particularly the role of bone debris in initiating bone formation was emphasized. MATERIAL AND METHODS Solid, screw-type cylindrical titanium implants (SSI) (n=49), 4 mm long and 2.8 mm wide, with either chemically modified (SLActive(®)) or sandblasted and acid-etched (SLA(®)) surface configurations were surgically installed in the retromolar region of 28 human volunteers. After 7, 14, 28 and 42 days of submerged healing, the devices were retrieved with a trephine. Histologic ground sections were prepared and histomorphometrically analyzed. Linear measurements determined fractions of old bone (OBIC), new bone (NBIC), soft tissue (ST) and bone debris (BD) in contact with the SSI surfaces. RESULTS Healing was uneventful at all installation sites. Sixty-one percent of all devices were suitable for morphometric analyses. All implant surfaces were partially coated with bone debris and new bone formation was observed as early as 7 days after installation. There was a gradual increase in NBIC, whereas OBIC, ST and BD progressively decreased over time. NBIC after 2 and 4 weeks was higher on SLActive(®) than on SLA(®) surfaces, albeit statistically not significant. The BD : ST ratio changed significantly from 7 to 42 days (from 50 : 50 to 10 : 90 for SLActive(®); from 38: 62 to 10 : 90 for SLA(®)) (Fishers exact test, P<0.01). CONCLUSION Both SLActive(®) and SLA(®) devices became progressively osseointegrated, while old bone on the device surface was gradually resorbed. The decrease in BD : ST ratio suggests that bone debris, created during implant installation and adhering to moderately rough surfaces, significantly contributed to the initiation of bone deposition and mediated the connection between the old bone and the new bone on the implant surface.

Interleukin‐6 in oral diseases: a review

Interleukin-6 (IL-6) is a pleomorphic cytokine involved in a number of physiologic and pathologic processes including response to trauma and infection and development and progression of inflammation and malignancy. IL-6 is emerging as an important mediator and novel therapeutic target for chronic inflammatory diseases and cancer. The present study reviews the available evidence regarding the association between IL-6 and a range of oral diseases including infections (periodontal disease and endodontic infections), immunologically mediated disorders (oral lichen planus and Sjögrens syndrome) and malignancy (oral cancer and precancer). The role of common genetic variants of IL-6 in determining individual susceptibility to certain oral diseases, as well as novel therapeutic strategies based on IL-6 inhibition are also discussed.