Peri-implant Bone Tissue Research Articles

Weighted Gene Coexpression Network Analysis Identified IL2/STAT5 Signaling Pathway as an Important Determinant of Peri-Implantitis.

Objective Peri-implantitis (PI) is one of the main reasons for dental implant failure. Until now, the etiology and pathogenesis of PI remain unclear. Methods In this study, we used differentially expressed genes (DEGs) analysis and gene function enrichment analysis to assess the expression profile of peri-implant bone tissue and gingiva in PI public data from the Gene Expression Omnibus (GEO) database. Then, we used gingival tissues from patients with PI and healthy individual to construct gene coexpression networks to reveal the biological functions of the genes in PI using RNA sequencing data. Afterward, key gene modules were selected to reveal the critical biological process or signaling pathway using Hallmark's gene enrichment and expression analysis of the related pathway members in PI. Results DEGs were enriched in the formation of cellular responses to external stimuli in bone tissue. Cytokine production, lymphocyte activation, immune response-regulating signaling pathway, and blood vessel development were the top GO biology process or pathways of the DEGs in gingival tissue. Weighted gene coexpression network analysis (WGCNA) of RNA-seq data was used to assess the results of correlation analysis between modules and traits and correlation analysis between modules and functions. kMEpurple, kMEgreen, and kMEred modules were selected as the key gene modules. Signaling pathways and gene expression analysis were performed on selected modules, such as IL2/STAT5 signaling pathway, TNFα signaling pathway via NFκB, and angiogenesis were enriched in kMEpurple module. Hedgehog signaling pathway, Wnt β-catenin signaling pathway, and IL2/STAT5 signaling pathway were enriched in kMEgreen module. Peroxisome, IL2/STAT5 signaling pathway, and epithelial-mesenchymal transformation process were enriched in kMEred module. All the enrichment results of key modules contained IL2/STAT5 signaling pathway. Conclusion. Differential gene and enrichment analysis based on public data showed differences in gene expression patterns and biological process between bone and gingival tissues in PI. This spatial-temporal heterogeneity is reflected in the formation of cellular responses to external stimuli, which was enriched in bone tissue, but cytokine production, lymphocyte activation, immune response regulating signaling pathway, and blood vessel development were enriched in gingival tissue. WGCNA and Hallmark gene sets enrichment analysis of the gingival tissue expression profile and showed that IL2-mediated activation of immune cells could be a critical mechanism in PI. As a new clinical treatment alternative, we suggest that IL2/STAT5 pathway blockers could be helpful in the treatment of PI.

Titanium nanotopography induces osteocyte lacunar-canalicular networks to strengthen osseointegration

Osteocyte network architecture is closely associated with bone turnover. The cellular mechanosensing system regulates osteocyte dendrite formation by enhancing focal adhesion. Therefore, titanium surface nanotopography might affect osteocyte network architecture and improve the peri-implant bone tissue quality, leading to strengthened osseointegration of bone-anchored implants. We aimed to investigate the effects of titanium nanosurfaces on the development of osteocyte lacunar-canalicular networks and osseointegration of dental implants. Alkaline etching created titanium nanosurfaces with anisotropically patterned dense nanospikes, superhydrophilicity, and hydroxyl groups. MLO-Y4 mouse osteocyte-like cells cultured on titanium nanosurfaces developed neuron-like dendrites with increased focal adhesion assembly and gap junctions. Maturation was promoted in osteocytes cultured on titanium nanosurfaces compared to cells cultured on machined or acid-etched micro-roughened titanium surfaces. Osteocytes cultured in type I three-dimensional collagen gels for seven days on nano-roughened titanium surfaces displayed well-developed interconnectivity with highly developed dendrites and gap junctions compared to the poor interconnectivity observed on the other titanium surfaces. Even if superhydrophilicity and hydroxyl groups were maintained, the loss of anisotropy-patterned nanospikes reduced expression of gap junction in osteocytes cultured on alkaline-etched titanium nanosurfaces. Four weeks after placing the titanium nanosurface implants in the upper jawbone of wild-type rats, osteocytes with numerous dendrites were found directly attached to the implant surface, forming well-developed lacunar-canalicular networks around the nano-roughened titanium implants. The osseointegration strength of the nano-roughened titanium implants was significantly higher than that of the micro-roughened titanium implants. These data indicate that titanium nanosurfaces promote osteocyte lacunar-canalicular network development via nanotopographical cues and strengthen osseointegration. Statement of significanceThe clinical stability of bone-anchoring implant devices is influenced by the bone quality. The osteocyte network potentially affects bone quality and is established by the three-dimensional (3D) connection of neuron-like dendrites of well-matured osteocytes within the bone matrix. No biomaterials are known to regulate formation of the osteocyte network. The present study provides the first demonstration that titanium nanosurfaces with nanospikes created by alkali-etching treatment enhance the 3D formation of osteocyte networks by promoting osteocyte dendrite formation and maturation by nanotopographic cues, leading to strengthened osseointegration of titanium implants. Osteocytes attached to the titanium nanosurfaces via numerous cellular projections. The success of osteocyte regulation by nanotechnology paves the way for development of epoch-making technologies to control bone quality.

Analysis of the Chemical Composition and Morphological Characterization of Tissue Osseointegrated to a Dental Implant after 5 Years of Function

Osseointegration implies the coexistence of a biocompatible implant subjected to masticatory loads and living bone tissue adhered to its surface; this interaction is a critical process for the success of implants. The objective of this work is to analyze the osseoformation and osseointegration of a dental implant in operation for 5 years microscopically through morphological analysis of the surface and chemical composition through a variable pressure scanning electron microscope (VP-SEM) and energy dispersive X-ray spectrometry (EDX). The chemical composition and general characteristics of the structural morphology of random areas of the surfaces of an osseointegrated dental implant from an ex vivo sample were analyzed. On the surface of the implant free of bone tissue, titanium (TI) was mainly identified in the area of the implant threads and carbon (C) in the depth of the implant threads. Phosphorus (P), calcium (Ca), oxygen (O), carbon (C), with dense and homogeneous distribution, and, to a lesser extent, sodium (Na) were detected on the bone surface around the contour of the implant. Regarding the morphological characteristics of the implant surface, a rough structure with some irregularities and detachments of the implant lodged in the bone tissue was observed. Microscopic analysis showed calcified bone tissue distributed in an orderly manner on the coronal and medial surface and sinuous and irregular in the apical area, with the presence of red blood cells. The composition of the implant allows a dynamic process of bone remodeling and regeneration subject to the biological and mechanical needs of the operation. Dental implants are shown to have exceptional and long-lasting biocompatibility that enables the formation of mature peri-implant bone tissue.

Biomechanical comparison of four treatment models for the totally edentulous maxilla: a finite element analysis

The aim of this study is to evaluate by finite element analysis different techniques of totally edentulous maxilla rehabilitation, considering implants, bone tissue, metallic infra-structure, and prosthetic abutments characteristics, by means of a three-dimensional model. Stress distribution on bone tissue, implants, and abutments was analyzed with four configurations (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants). Greater tension on bone tissue were found around distal implants, in all treatment groups, but not exceeding resistance limits of cortical bone. Von Mises stress was higher on the distal region of distal implants of all-on-four and M-4 techniques. Higher stress concentration was seen on angled abutments of zygomatic implants. The highest values of minimal compression stresses were concentrated on peri implant-bone tissue, especially in the model of All-on-4. Therefore, the present finite element analysis revealed that the four configurations of treatment (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants) for the totally edentulous maxilla are feasible and safe, from a biomechanical point of view.

Histological and Immunohistochemical Analysis of Peri-Implant Soft and Hard Tissues in Patients with Peri-Implantitis.

Currently, researchers are focused on the study of cytokines as predictive biomarkers of peri-implantitis (PI) in order to obtain an early diagnosis and prognosis, and for treatment of the disease. The aim of the study was to characterize the peri-implant soft and hard tissues in patients with a peri-implantitis diagnosis. A descriptive observational study was conducted. Fifteen soft tissue (ST) samples and six peri-implant bone tissue (BT) samples were obtained from 13 patients who were diagnosed with peri-implantitis. All the samples were processed and embedded in paraffin for histological and immunohistochemical analyses. A descriptive and quantitative analysis of mast cells and osteocytes, A proliferation-inducing ligand (APRIL), B-cell activating factor (BAFF), osteonectin (ON), and ∝-smooth muscle actin (∝-SMA) was performed. We observed the presence of mast cells in peri-implant soft tissue in all samples (mean 9.21 number of mast cells) and osteocytes in peri-implant hard tissue in all samples (mean 37.17 number of osteocytes). The expression of APRIL-ST was 32.17% ± 6.39%, and that of APRIL-BT was 7.09% ± 5.94%. The BAFF-ST expression was 17.26 ± 12.90%, and the BAFF-BT was 12.16% ± 6.30%. The mean percentage of ON was 7.93% ± 3.79%, and ∝-SMA was 1.78% ± 3.79%. It was concluded that the expression of APRIL and BAFF suggests their involvement in the bone resorption observed in peri-implantitis. The lower expression of osteonectin in the peri-implant bone tissue can also be associated with a deficiency in the regulation of bone remodeling and the consequent peri-implant bone loss.

Influence of morphofunctional properties of platelets on the mechanical characteristics of the «bone tissue-implant» system in the experiment

The use of platelet-based biological materials attracts special attention in regenerative medicine. The aim of the work was to study the peculiarities of mechanical properties of the system «peri-implant bone tissue-implant» depending on the morphofunctional properties of platelets under conditions of titanium rod implantation into the femur bone of rabbits. The number of platelets, mean volume (MPV), thrombocrit, ratio of large platelets to their total number, and ADP-induced aggregation were determined. During mechanical testing, we determined the maximum load on the «peri-implant bone-implant» system and its elastic properties. According to the result of preoperative determination of the morphofunctional characteristics of the platelets, the rabbits were divided into 2 groups: low platelet potential (LTP) and high platelet potential (HPP). Determination of the mechanical parameters of the «peri-implant bone tissue-implant» system showed that the maximum load in the NTP group was lower than in the VTP group, at the same time, no significant differences were found in the parameter characterizing elasticity (Elastic). The number as well as the morphofunctional characteristics of the circulating platelets in the blood have a significant impact on the strength characteristics of the newly formed peri-implant bone tissue.

Peri-Implant Repair Using a Modified Implant Macrogeometry in Diabetic Rats: Biomechanical and Molecular Analyses of Bone-Related Markers.

DM has a high prevalence worldwide and exerts a negative influence on bone repair around dental implants. Modifications of the microgeometry of implants have been related to positive results in bone repair. This study assessed, for the first time, the influence of an implant with modified macrodesign based on the presence of a healing chamber in the pattern of peri-implant repair under diabetic conditions. Thirty Wistar rats were assigned to receive one titanium implant in each tibia (Control Implant (conventional macrogeometry) or Test Implant (modified macrogeometry)) according to the following groups: Non-DM + Control Implant; Non-DM + Test Implant; DM + Control Implant; DM + Test Implant. One month from the surgeries, the implants were removed for counter-torque, and the bone tissue surrounding the implants was stored for the mRNA quantification of bone-related markers. Implants located on DM animals presented lower counter-torque values in comparison with Non-DM ones, independently of macrodesign (p < 0.05). Besides, higher biomechanical retention levels were observed in implants with modified macrogeometry than in the controls in both Non-DM and DM groups (p < 0.05). Moreover, the modified macrogeometry upregulated OPN mRNA in comparison with the control group in Non-DM and DM rats (p < 0.05). Peri-implant bone repair may profit from the use of implants with modified macrogeometry in the presence of diabetes mellitus, as they offer higher biomechanical retention and positive modulation of important bone markers in peri-implant bone tissue.

Analysis of Peri-Implant Bone Loss with a Convergent Transmucosal Morphology: Retrospective Clinical Study

Objective: The aim of this study was to analyze the peri-implant bone loss of infracrestal, supracrestal, and crestal implants from the day of placement and up to 1 year of prosthetic loading. Material and methods: A retrospective clinical study was carried out. The sample consisted of 30 implants placed on 30 patients. It was divided into three groups: infracrestal (n = 10), crestal (n = 10), and supracrestal (n = 10) implants. Results: Following the statistical analysis, it was observed that, 4 months after implant placement, the mean values of total peri-implant bone loss were 0.04 mm in infracrestal implants, 0.26 mm in crestal implants, and 0.19 mm in supracrestal implants. At the end of one year of prosthetic loading, the peri-implant bone loss was 0.12 mm in infracrestal implants, 1.04 mm in crestal implants, and 0.27 mm in supracrestal implants. It was determined that peri-implant bone loss in crestal implants was significantly higher than in supracrestal implants, and these in turn were significantly higher than in infracrestal implants. Conclusions: The implants that obtained a better biological behavior on peri-implant bone tissue were the infracrestal implants with a converging transmucosal abutment.

Use of 6-mm Short Implants in Japanese Patients: Clinical, Radiologic, and Patient Satisfaction Results in a Retrospective Study with a 2-Year Follow-up.

Implant therapy for tooth loss in the molar area is challenging due to the anatomical limitations, requiring bone augmentation procedures that are associated with high surgical complexity and long postsurgical recovery. Recently, many studies have demonstrated the usefulness of short implants. However, few studies have been performed in Japanese patients to evaluate peri-implant bone changes, changes in peri-implant epithelial tissue, and patient satisfaction. The present study included 16 patients (5 men, 11 women; mean age: 60 years) who received 26 short (6-mm) implants. Changes in peri-implant bone and epithelial tissue were measured radiographically at superstructure loading and after 2 years. Peri-implant pocket probing depth was measured at the epithelial tissue and compared at both time points. Patient satisfaction was graded using the Oral Health Impact Profile (OHIP-14) before treatment and at follow-up. The mean mesial and distal bone levels were -0.05 mm and 0.37 mm at loading, respectively, and were 0.33 mm and 0.53 mm after 2 years, respectively. Significant peri-implant bone formation for mesial and distal bone levels at both time points were determined by Wilcoxon signed-rank test. Mean probing depth increased slightly, from 3.03 mm at loading to 3.33 mm after 2 years, but no significant difference was found. The OHIP-14 found that patient satisfaction levels increased after 2 years. Using 6-mm short implants in sites with insufficient bone levels can be a highly beneficial treatment option for patients, as it avoids the need for bone augmentation. However, more long-term and detailed studies on the clinical outcomes for these implants are required.

Biomimetic hierarchical implant surfaces promote early osseointegration in osteoporotic rats by suppressing macrophage activation and osteoclastogenesis.

Successful implant-bone integration remains a formidable challenge in osteoporotic patients, because of excessive inflammatory reactions and osteoclastogenesis around the peri-implant bone tissue. This study designed biomimetic micro/sub-micro hierarchical surfaces on titanium implants based on natural bone hierarchical structures to mitigate macrophage-mediated inflammatory reactions, osteoclastogenesis, and osteogenesis in vitro, as well as promote early osseointegration in vivo. It was found that the biomimetic hierarchical surfaces inhibited M1 macrophage-mediated inflammatory reactions via suppression of the TLR2/NF-κB signaling pathway in vitro. Subsequently, osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was observed to be significantly enhanced on hierarchical surfaces in the presence of macrophage conditional media. Furthermore, osteoclast formation was also decreased by inhibiting the osteoclastogenesis regulatory factor NFATc-1 expression on hierarchical surfaces. In vivo, the implant with a micro/sub-micro hierarchical surface underwent rapid and early osseointegration, with the newly formed bone being tightly integrated with the implants. Hence, the hierarchical surface mitigated the inflammatory microenvironment around the implant, thereby inhibiting osteoclastogenesis. This study thus offers a novel biomimetic strategy for designing surface hierarchical topography to facilitate implant-bone osseointegration in osteoporotic patients.

125. Dynamic PET facilitated Pharmacokinetic Modeling and High-dose Rifampin Regimens for Staphylococcus aureus Orthopedic Implant Associated Infections: Bench to Bedside

125. Dynamic PET facilitated Pharmacokinetic Modeling and High-dose Rifampin Regimens for <i>Staphylococcus aureus</i> Orthopedic Implant Associated Infections: Bench to Bedside

Titanium surface with nanospikes tunes macrophage polarization to produce inhibitory factors for osteoclastogenesis through nanotopographic cues

Definitive prevention of inflammatory osteolysis around peri-implant bone tissue remains unestablished. M1 macrophages play a key role in the host defense against inflammatory osteolysis, and their polarization depends on cell shape. Macrophage polarization is controlled by environmental stimuli, particularly physicochemical cues and hence titanium nanosurface might tune macrophage polarization and function. This study determined whether titanium nanosurfaces with anisotropically patterned nanospikes regulates macrophage polarization for inhibiting osteoclast differentiation of osteoclast precursors. Alkaline-etching treatment with different protocols created two types of titanium nanosurfaces that had anisotropically patterned nanospikes with high or low distribution density, together with superhydrophilicity and the presence of hydroxyl groups. J774A.1 cells (mouse macrophage-like cell line), cultured on both titanium nanosurfaces, exhibited truly circulated shapes and highly expressed M1, but less M2, markers, without loss of viability. M1-like polarization of macrophages on both titanium nanosurfaces was independent of protein-mediated ligand stimulation or titanium surface hydrophilic or chemical status. In contrast, other smooth or micro-roughened titanium surfaces with little or no nanospikes did not activate macrophages under any culture conditions. Macrophage culture supernatants on both titanium nanosurfaces inhibited osteoclast differentiation of RAW264.7 cells (mouse osteoclast precursor cell line), even when co-incubated with osteoclast differentiation factors. The inhibitory effects on osteoclast differentiation tended to be higher in macrophages cultured on titanium nanosurfaces with denser nanospikes. These results showed that titanium nanosurfaces with anisotropically patterned nanospikes tune macrophage polarization for inhibiting osteoclast differentiation of osteoclast precursors, with nanotopographic cues rather than other physicochemical properties. Statement of significancePeri-implant inflammatory osteolysis is one of the serious issues for dental and orthopedic implants. Macrophage polarization and function are key for prevention of peri-implant inflammatory osteolysis. Macrophage polarization can be regulated by the biomaterial's surface physicochemical properties such as hydrophilicity or topography. However, there was no titanium surface modification to prevent inflammatory osteolysis through immunomodulation. The present study showed for the first time that the titanium nanosurfaces with anisotropically patterned nanospikes, created by the simple alkali-etching treatment polarized macrophages into M1-like type producing the inhibitory factor on osteoclast differentiation. This phenomenon attributed to nanotopographic cues, but not hydrophilicity on the titanium nanosurfaces. This nanotechnology might pave the way to develop the smart implant surface preventing peri-implant inflammatory osteolysis through immunomodulation.

Strontium-incorporated titanium implant surfaces treated by hydrothermal treatment enhance rapid osseointegration in diabetes: A preclinical vivo experimental study.

The aim of the current study was to explore effects of strontium-incorporated titanium implant surfaces by hydrothermal treatment on osseointegration in diabetic rats. The surface characteristics of SLA and SLA-Sr surfaces were detected by related instruments. Thirty-six male Sprague-Dawley rats were induced into diabetes, and thirty-six rats were normal. SLA and SLA-Sr implants were, respectively, inserted into bilateral tibial metaphysis of each rat. Percentage of bone-to-implant contact (BIC%) and percentage of bone area (BA%) were analyzed at 4 and 8weeks after implantation. Immunohistochemistry of osteoprotegerin (OPG) and Wnt5a were conducted at 1 and 4weeks. Gene expression levels of inflammatory cytokines and related signaling molecules in peri-implant bone tissue were detected at 3 and 7days. Strontium was uniformly distributed on SLA-Sr surfaces, and it was released in an effective concentration range. SLA-Sr surfaces showed significantly higher BIC% in diabetic rats at 4 (p<.05) and 8weeks (p<.05). Besides, it displayed higher BIC% at 4weeks (p<.05) in normal rats. Also, SLA-Sr surfaces upregulated expression of OPG at 4weeks (p<.05) in diabetic rats. What's more, SLA-Sr surfaces downregulated inflammation (TNF-α, IL-1β, and IL-6; p<.01) in diabetic rats at 3days. In addition, expression of Wnt5a and ROR2 was upregulated (p<.05) at 7days after implantation under diabetes. It is suggested that strontium-incorporated titanium implant surfaces by hydrothermal treatment could enhance implant osseointegration as compared with SLA implant surfaces in diabetic rats.

Comparing the Clinical Outcome of Peri-implant Hard and Soft Tissue Treated with Immediate Individualized CAD/CAM Healing Abutments and Conventional Healing Abutments for Single-Tooth Implants in Esthetic Areas Over 12 Months: A Randomized Clinical Trial.

The purpose of this study was to compare the clinical influence of immediate individualized CAD/CAM healing abutments and conventional healing abutments on peri-implant soft and hard tissue in shaping the emergence profile. Patients with a single maxillary incisor missing who accepted dental implantation were registered in this study. After implantation, individualized CAD/CAM healing abutments and regular prefabricated abutments were randomly inserted to shape the emergence profile. A radiograph was taken, and the pink esthetic score, papilla height, papilla proportion, and probing depth were recorded at 6 months after implant placement (T1), loading (T2, definitive restoration), and 1 year after loading (T3). Patient self-assessment scores were also evaluated through the visual analog scale. The data were analyzed statistically using the t test or repeated-measurements analysis of variance (ANOVA). Twenty patients were enrolled in this study, including 9 patients using individualized abutments and 11 patients using conventional abutments. The mean total marginal bone level in the individualized abutment group was 1.53 ± 0.65 mm at implant placement, 1.10 ± 0.47 mm at loading, and 0.76 ± 0.47 mm at 1 year after loading. In contrast, the mean total marginal bone level in the conventional abutment group was 0.62 ± 0.39 mm at implant placement, 0.14 ± 0.55 mm at loading, and -0.04 ± 0.53 mm at 1 year after loading. The differences between the individualized abutment group and conventional abutment group were statistically significant for the mesial and distal marginal bone level at three time points, respectively (P ≤ .05). Similarly, there were significant differences in probing depth, papilla height, and pink esthetic score between the two groups. This immediately individualized healing abutment protocol may significantly preserve the peri-implant marginal bone and soft tissue. The use of individualized CAD/CAM healing abutments for shaping the emergence profile shows better esthetic outcomes than conventional healing abutments.

Nerve growth factor combined with dental pulp stem cells promotes peri-implant osseointegration in rats

To observe the effect of nerve growth factor (NGF) combined with dental pulp stem cells (DPSCs) on periimplant osseointegration in rats and explore the underlying mechanism. Cultured DPSCs were treated with NFG or with NFG plus the TrkA antagonist K252a, and after osteogenic induction, the formation of calcium nodules was observed and the expressions of RUNX2 and osteocalcin (OCN) were detected with Western blotting. SD rat models with femoral implantation of dental implants were established and divided into control, DPSCs, DPSCs+NGF, DPSCs+K252a, and DPSCs+ NGF+K252a groups, and in all but the control group, DPSCs were injected locally before placement of the implants (n=8); NGF, K252a and their combination were injected intraperitoneally on a daily basis for 4 weeks. All the rats underwent micro-CT, and the peri-implant bone tissues were collected for HE staining and detection of RUNX2 and OCN expressions using Western blotting. In cultured DPSCs, the number of calcium nodules and the expression levels of RUNX2 and OCN were significantly higher in NGF group than in the control group (P < 0.05), and were significantly lower in NGF+K252a group than in NGF group (P < 0.05). In the rat models, the BMD, TB. Th, TB. N and expressions of RUNX2 and OCN in the peri-implant bone tissues were significantly higher in DPSCs group and DPSCs+NGF group than in the control group (P < 0.05), significantly higher in DPSCs+NGF group than in DPSCs group (P < 0.05), comparable between DPSCs+K252a group and DPSCs group (P> 0.05), and significantly lower in DPSCs+NGF+K252a group than in DPSCs+NGF group (P < 0.05). NGF combined with DPSCs can promote osseointegration in the peri-implant tissues in rats possibly due to a TrkA-mediated effect of NGF for promoting osteogenic differentiation of the DPSCs.

CBCT analysis of the tissue thickness at immediate implant placement with contour augmentation in the maxillary anterior zone: a 1-year prospective clinical study

BackgroundImmediate implant placement with simultaneous contour augmentation such as guided bone regeneration (GBR) or connective tissue grafting (CTG) has been widely performed. However, few prospective studies have evaluated both peri-implant bone and soft tissue changes between the preoperative and postoperative periods. The purpose of this study is to quantify the horizontal dimensional changes of the facial bone and soft tissue following immediate implant placement with contour augmentation.Material and methodsTwenty patients who underwent immediate implant placement in the anterior maxilla received GBR and CTG (test group) or GBR only (control group). Cone-beam computed tomography (CBCT) scans were taken preoperatively and 1 year after the definitive prosthesis connection, and then, they were superimposed. On the CBCT images of the two stages, the horizontal distance from the implant platform to the facial bone surface (BW) and the horizontal soft tissue width (GW) were measured at the implant platform level and 2 mm apical to the implant platform level. The sum of BW and GW (=TW) was used to assess the facial mucosal contour.ResultsBW decreased significantly from preoperative to 1 year after prosthesis connection with a mean decrease of 0.47 mm (P =0.021) in the control group and a mean decrease of 0.50 mm (P = 0.019) in the test group at the implant platform level. GW increased significantly with a mean increase of 1.37 mm (P =0.005) in the test group at the implant platform level. TW decreased significantly with a mean decrease of 0.46 mm in the control group (P =0.049) but increased significantly with a mean increase of 0.87 mm in the test group (P =0.005) at the implant platform level.ConclusionsImmediate implant placement with CTG showed a soft tissue gain of 1.37 mm compensated for bone resorption, thus still preserving the preoperative mucosal contour. CTG should be performed with immediate implant placement in cases where preoperative mucosal contours need to be maintained.

A novel surgical model for the preclinical assessment of the osseointegration of dental implants: a surgical protocol and pilot study results

BackgroundDental implants are considered the gold standard replacement for missing natural teeth. The successful clinical performance of dental implants is due to their ability to osseointegrate with the surrounding bone. Most dental implants are manufactured from Titanium and it alloys. Titanium does however have some shortcomings so alternative materials are frequently being investigated. Effective preclinical studies are essential to transfer the innovations from the benchtop to the patients. Many preclinical studies are carried out in the extra-oral bones of small animal models to assess the osseointegration of the newly developed materials. This does not simulate the oral environment where the dental implants are subjected to several factors that influence osseointegration; therefore, they can have limited clinical value.AimThis study aimed to develop an appropriate in-vivo model for dental implant research that mimic the clinical setting. The study evaluated the applicability of the new model and investigated the impact of the surgical procedure on animal welfare.Materials and methodsThe model was developed in male New Zealand white rabbits. The implants were inserted in the extraction sockets of the secondary incisors in the maxilla. The model allows a split-mouth comparative analysis. The implants’ osseointegration was assessed clinically, radiographically using micro-computed tomography (µ-CT), and histologically. A randomised, controlled split-mouth design was conducted in 6 rabbits. A total of twelve implants were inserted. In each rabbit, two implants; one experimental implant on one side, and one control implant on the other side were applied. Screw-shaped implants were used with a length of 8 mm and a diameter of 2 mm.ResultsAll the rabbits tolerated the surgical procedure well. The osseointegration was confirmed clinically, histologically and radiographically. Quantitative assessment of bone volume and mineral density was measured in the peri-implant bone tissues. The findings suggest that the new preclinical model is excellent, facilitating a comprehensive evaluation of osseointegration of dental implants in translational research pertaining to the human application.ConclusionThe presented model proved to be safe, reproducible and required basic surgical skills to perform.

Biomechanical evaluation of 3-unit fixed partial dentures on monotype and two-piece zirconia dental implants

This study aimed to evaluate the biomechanical behavior, stress distributions and bone microstrain of fixed partial dentures (FPD) with ceramic abutments supported on monotype zirconia implants, titanium implants and two-piece zirconia implants, using finite element analysis. A three-dimensional model of the jaw was simulated containing 1.0 mm thick cortical bone and cancellous bone tissue. A FPD and implant models (4.1 x 10 mm) were modeled containing a cement-retained implant abutment. These models were replicated in three groups with similar geometries: Titanium Implant and Zirconia Abutment (Ti-Zr); Zirconia Implant and Zirconia Abutment (Zr-Zr) and Monotype Zirconia Implant (Zr-S). An axial load of 300 N was applied to the center of the first premolar. The microstrain (με) and the Von-Mises stress (MPa) were assumed as failures criteria. For the three groups, a higher stress concentration was observed in the region of FPD connectors. The Ti-Zr group showed a higher stress concentration in the prosthesis and implant when compared to the other groups. However, the smaller elastic modulus of the titanium implant, in relation to the zirconia, provided a lower stress in the abutment and in the prosthetic screw. The monotype implant system allowed a more homogeneous stress distribution and its strain were predominantly located in the cervical region of the peri-implant bone tissue. Monotype or two-piece zirconia implants can be used for rehabilitation with FPD. However, the absence of separation between implant and abutment in the monotype system avoids the stress concentration in the prosthetic screw and reduced the peri-implant bone strain.

Implant-associated osteomyelitis: Development, characterisation, and application of a porcine model.

Implant-associated osteomyelitis: Development, characterisation, and application of a porcine model.

Design of metal-polymer structure for dental implants with stiffness adaptable to alveolar bone

Mechanical adaptability of implants to the surrounding alveolar bone is one of the critical factors that influences its long-term service. Experimental study shows that widely adopted titanium implants are prone to induce stress shielding due to the considerable mismatch of moduli between stiff implant and alveolar bone, which is considered to induce resorption of peri-implant bone tissues and impair the retention of implants. Moreover, current commercial dental implants with fixed stiffness are unable to meet various alveolar bone conditions of the patients of different ages and physical situations. To solve the two problems, a novel design of metal-polymer structure is proposed for dental implants, which combines two kinds of biocompatible materials, i.e., titanium and polyether-ether-ketone (PEEK). The proposed composite structure allows patient-specific adjustment of equivalent modulus for dental implant in a cost-effective way. In this paper, three designs are given and compared to show how an optimized biomechanical health degree of peri-implant bone can be achieved to fit the alveolar bone condition of patients.