Is there any biomaterial substitute for peri-implant soft tissue phenotype modification? A network meta-analysis of the appraisal literature.

Evidence shows that an increased width and thickness of the keratinized mucosa favours peri-implant health. The aim of this network meta-analysis was to compare the clinical effects of alternative biomaterials for peri-implant soft tissue phenotype modification (PSPM) in patients with dental implants when compared to autologous tissue grafts. An electronic search without language or date limitations was performed in four databases and the grey literature for articles published until November 2020. The eligibility criteria included randomized clinical trials (RCTs) evaluating the clinical outcomes of biomaterials for PSPM. A pairwise and network meta-analysis was conducted for each parameter to assess and compare the outcomes between the different treatment arms for the primary and secondary outcomes. A total of 11 RCTs were included in this review. The free gingival graft (FGG) showed the best clinical effect for increasing keratinized mucosa width (KMW). When compared in a network, the FGG demonstrated the best treatment ranking of probability results, followed by connective tissue graft (CTG), acellular dermal matrix (ADM), and xenogeneic collagen matrix (XCM). For the parameters 'mucosa thickness' and 'participant satisfaction with aesthetics', the results were CTG > ADM > XCM and XCM > ADM > CTG, respectively. Autogenous tissue grafts (FGG/CTG) demonstrate the best results in increasing KMW and mucosa thickness when compared to the other biomaterials.

The impact of a modified cutting flute implant design on osseointegration.

Information concerning the effects of the implant cutting flute design on initial stability and its influence on osseointegration in vivo is limited. This study evaluated the early effects of implants with a specific cutting flute design placed in the sheep mandible. Forty-eight dental implants with two different macro-geometries (24 with a specific cutting flute design - Blossom group; 24 with a self-tapping design - DT group) were inserted into the mandibular bodies of six sheep; the maximum insertion torque was recorded. Samples were retrieved and processed for histomorphometric analysis after 3 and 6 weeks. The mean insertion torque was lower for Blossom implants (P<0.001). No differences in histomorphometric results were observed between the groups. At 3 weeks, P=0.58 for bone-to-implant contact (BIC) and P=0.52 for bone area fraction occupied (BAFO); at 6 weeks, P=0.55 for BIC and P=0.45 for BAFO. While no histomorphometric differences were observed, ground sections showed different healing patterns between the implants, with better peri-implant bone organization around those with the specific cutting flute design (Blossom group). Implants with the modified cutting flute design had a significantly reduced insertion torque compared to the DT implants with a traditional cutting thread, and resulted in a different healing pattern.

Immunoexpression of angiogenesis and proliferation markers in patients treated with cyclosporin A.

AIM: In the present immunohistochemical study, the expression of vascular endothelial growth factor, nitric oxide synthase 1 and 3, and Ki-67 in the gingival tissues of renal transplant patients treated with cyclosporin A was assessed. Gingival overgrowth (GO) frequently occurs in transplant patients receiving immunosuppressive drugs such as cyclosporine and this gingival inflammation might play an important role in the pathogenesis of drug-induced GO. METHODS: Twenty-eight human gingival biopsies were taken from healthy patients with chronic periodontitis (N.=14 control group), and from renal transplant recipients treated with cyclosporin A (N.=14 test group). The retrieved specimens were immunohistochemically processed and stained for vascular endothelial growth factor, nitric oxide synthase 1 and 3, and Ki-67. RESULTS: The levels of vascular endothelial growth factor, nitric oxide synthase 1 and 3, and Ki-67 were found to be significantly different among groups (P>0.001), with patients treated with cyclosporin A showing higher levels of all the analyzed markers compared to control group. CONCLUSION: In summary, the data from this pilot study suggests that the investigated factors have a role in the inflammation processes associated to immunosuppressive therapy. However, further studies with a larger sample population need to be conducted for an exhaustive knowledge of the mechanisms leading to GO.

Dental implants installed in irradiated jaws: a systematic review.

The aim of this study was to assess the survival rate of titanium implants placed in irradiated jaws. MEDLINE, EMBASE, and CENTRAL were searched for studies assessing implants that had been placed in nongrafted sites of irradiated patients. Random effects meta-analyses assessed implant loss in irradiated versus nonirradiated patients and in irradiated patients treated with hyperbaric oxygen (HBO) therapy. Of 1,051 potentially eligible publications, 15 were included. A total of 10,150 implants were assessed in the included studies, and of these, 1,689 (14.3%) had been placed in irradiated jaws. The mean survival rate in the studies ranged from 46.3% to 98.0%. The pooled estimates indicated a significant increase in the risk of implant failure in irradiated patients (risk ratio: 2.74; 95% confidence interval: 1.86, 4.05; p < .00001) and in maxillary sites (risk ratio: 5.96; 95% confidence interval: 2.71, 13.12; p < .00001). Conversely, HBO therapy did not reduce the risk of implant failure (risk ratio: 1.28; 95% confidence interval: 0.19, 8.82; p = .80). Radiotherapy was linked to higher implant failure in the maxilla, and HBO therapy did not improve implant survival. Most included publications reported data on machined implants, and only 3 studies on HBO therapy were included. Overall, implant therapy appears to be a viable treatment option for reestablishing adequate occlusion and masticatory conditions in irradiated patients.

Halogen lamp and LED activation of resin-modified glass ionomer restorative material. In vitro microhardness after long-term storage.

AIM: The purpose of this study was to evaluate the activation of resin-modified glass ionomer restorative material (RMGI, Vitremer-3M-ESPE, A3) by halogen lamp (QTH) or light-emitting diode (LED) by Knoop microhardness (KHN) in two storage conditions: 24 hrs and 6 months and in two depths (0 and 2 mm). MATERIALS AND METHODS: The specimens were randomly divided into 3 experimental groups (n = 10) according to activation form and evaluated in depth after 24 h and after 6 months of storage. Activation was performed with QTH for 40s (700 mW/cm) and for 40 or 20 s with LED (1,200 mW/cm2). After 24 hrs and 6 months of storage at 37 degrees C in relative humidity in light-proof container, the Knoop microhardness test was performed. Statistics Data were analysed by three-way ANOVA and Tukey post-tests (p < 0.05). RESULTS: All evaluated factors showed significant differences (p < 0.05). After 24 hrs there were no differences within the experimental groups. KHN at 0 mm was significantly higher than 2 mm. After 6 months, there was an increase of microhardness values for all groups, being the ones activated by LED higher than the ones activated by QTH. CONCLUSION: Light-activation with LED positively influenced the KHN for RMGI evaluated after 6 months.

On site noninvasive assessment of peri-implant inflammation by optical spectroscopy.

BACKGROUND AND OBJECTIVE: Optical spectroscopy has been proposed to measure regional tissue hemodynamics in periodontal tissue. The objective of this study was to further evaluate the diagnostic potential of optical spectroscopy in peri-implant inflammation in vivo by assessing multiple inflammatory parameters (tissue oxygenation, total tissue hemoglobin, deoxyhemoglobin, oxygenated hemoglobin and tissue edema) simultaneously. MATERIAL AND METHODS: A cross-sectional study was performed in a total of 64 individuals who presented with dental implants in different stages of inflammation. In brief, visible-near-infrared spectra were obtained, processed and evaluated from healthy (n = 151), mucositis (n = 70) and peri-implantitis sites (n = 75) using a portable spectrometer. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was employed to determine the relative contribution of each inflammatory component to the overall spectrum. RESULTS: Tissue oxygenation at peri-implantitis sites was significantly decreased (p < 0.05) when compared with that at healthy sites, which was largely due to an increase in deoxyhemoglobin and a decrease in oxyhemoglobin at the peri-implantitis sites compared with the mucositis and healthy sites. In addition, the tissue hydration index derived from the optical spectra in mucositis was significantly higher than that in other groups (p < 0.05). CONCLUSION: In summary, the results of this study revealed that hemodynamic alterations can be detected around diseased peri-implant sites by optical spectroscopy, and this method may be considered an alternative and feasible approach for the monitoring and diagnosis of peri-implant diseases.

Prevalence and microbiological diversity of Archaea in peri-implantitis subjects by 16S ribosomal RNA clonal analysis.

BACKGROUND AND OBJECTIVE: This study evaluated the prevalence and the molecular diversity of Archaea in the subgingival biofilm samples of subjects with peri-implantitis. MATERIAL AND METHODS: Fifty subjects were assigned into two groups: Control (n = 25), consisting of subjects with healthy implants; and Test (n = 25), consisting of subjects with peri-implantitis sites, as well as a healthy implant. In the Test group, subgingival biofilm samples were taken from the deepest sites of the diseased implant. In both groups, subgingival biofilm was collected from one site with a healthy implant and from one site with a periodontally healthy tooth. DNA was extracted and the 16S ribosomal RNA gene was amplified with universal primer pairs for Archaea. Amplified genes were cloned and sequenced, and the phylotypes were identified by comparison with known 16S ribosomal RNA sequences. RESULTS: In the Control group, Archaea were detected in two and three sites of the implant and the tooth, respectively. In the Test group, Archaea were detected in 12, 4 and 2 sites of diseased implants, healthy implants and teeth, respectively. Diseased implants presented a significantly higher prevalence of Archaea in comparison with healthy implants and natural teeth, irrespective of group. Over 90% of the clone libraries were formed by Methanobrevibacter oralis, which was detected in both groups. Methanobacterium congelense/curvum was detected in four subjects from the Test group and in two subjects from the Control group. CONCLUSION: Although M. oralis was the main species of Archaea associated with both healthy and diseased implant sites, the data indicated an increased prevalence of Archaea in peri-implantitis sites, and their role in pathogenesis should be further investigated.

VEGF and MVD expression in sinus augmentation with autologous bone and several graft materials.

OBJECTIVE: The aim of this study was to assess vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) in maxillary sinus augmentation with autogenous bone and different graft materials for evaluating their angiogenic potential. METHODS: Biopsies were harvested 10 months after sinus augmentation with a combination of autogenous bone and different graft materials: hydroxyapatite (HA, n = 6 patients), demineralized freeze-dried bone allograft (DFDBA, n = 5 patients), calcium phosphate (CP, n = 5 patients), Ricinus communis polymer (n = 5 patients) and control group--autogenous bone only (n = 13 patients). RESULTS: In all the samples, higher intensities of VEGF expression were prevalent in the newly formed bone, while lower intensities of VEGF expression were predominant in the areas of mature bone. The highest intensity of VEGF expression in the newly formed bone was expressed by HA (P < 0.001) and CP in relation to control (P < 0.01) groups. The lowest intensities of VEGF expression in newly formed bone were shown by DFDBA and polymer groups (P < 0.05). When comparing the different grafting materials, higher MVD were found in the newly formed bone around control, HA and CP (P < 0.001). CONCLUSION: Various graft materials could be successfully used for sinus floor augmentation; however, the interactions between bone formation and angiogenesis remain to be fully characterized.

Histological comparison between implants retrieved from patients with and without osteoporosis.

The aim of this restrospective histologic study was to evaluate the bone-to-implant contact of loaded implants retrieved from patients with and without osteoporosis. The evaluated material consisted of 22 threaded, cylindrical, loaded dental implants retrieved from 21 patients: 7 from 7 women with postmenopausal osteoporosis (osteoporosis group) and the remaining 15 from 14 patients without history of osteoporosis or other metabolic diseases (control group). Histologic analysis revealed bone tissue in the threads of the retrieved implants, with variations in the percentage of bone-to-implant contact for the implants retrieved from both groups. The pristine bone was mostly mature bone and/or lamellar and compact, and numerous osteocytes were observed in the lacunae, although areas of woven bone could be distinguished. In some specimens, there were areas of newly formed bone exhibiting different degrees of maturation and remodeling. The mean bone-to-implant contact was 46.00+/-11.46% and 47.84+/-14.03% for the osteoporosis group and control group, respectively. The results of this histomorphometric study suggest that osteoporosis may not be a contra-indication for implant placement, at least after osseointegration has been established.