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Background: A new two-piece abutment design consisting of an upper prosthetic component and tissue-level base has been introduced; however, the biomechanical behavior of such a design has not been documented. This study aimed to investigate the effect of a two-piece abutment design on the stress in the implant components and surrounding bone, as well as its influence on microgap formation., Methods: To simulate the implant models in the mandibular left first molar area, we established nine experimental groups that included three bone qualities (type II, III, and IV) and three implant-abutment designs (internal bone level, tissue level, and a two-piece design). After the screw was preloaded, the maximum occlusal (600 N) and masticatory (225 N) forces were established. Finite element analysis was performed to analyze the maximum and minimum principal stresses on the peri-implant bone; the von Mises stresses in the implants, abutments, bases, and screws, and the microgaps at the implant-abutment, implant-base, and base-abutment interfaces., Results: For all three loading methods, the two-piece abutment design and bone-level connection exhibited similarities in the maximum and minimum principal stresses in the peri-implant bone. The von Mises stresses in both screws and bases were greater for the two-piece design than for the other connection types. The smallest microgap was detected in the tissue-level connection; the largest was observed at the implant-base interface in the two-piece design., Conclusions: The present study found no evidence that the abutment design exerts a significant effect on peri-implant bone stress. However, the mechanical effects associated with the base and screws should be noted when using a two-piece abutment design. The two-piece abutment design also had no advantage in eliminating the microgap., (© 2023. The Author(s).)

Objectives: Type 2 diabetes mellitus (T2DM) is a systemic disease that also compromises the bone healing capacity. In healthy individuals, surface modifications of dental implants are proven to increase bone response and implant success. The aim of this study was to clarify if the surface modifications also improve osseointegration in a setting with diabetes mellitus., Methods: T2DM was induced in 7 rats by a high-fat diet/low-dose streptozotocin injection. All animals received a hydroxyapatite (HA) implant, a sandblasted and acid-etched (SLA) implant, and a standard machined titanium implant for control in the tibia. After 4 weeks, thin-ground sections were produced, and the volume of new bone formation (nBV/TV) and bone-to-implant contact (nB.I/Im.I) were histomorphometrically analyzed., Results: Both surface modifications led to an increase of osseointegration compared with the machined surface implant in rats with T2DM. nBV/TV was highest in the SLA implants, whereas nB.I/Im.I was highest in the HA group. Regardless of the surface modification, a superordinate regional pattern of new bone formation over the length of the implant was observed., Conclusions: Implants with HA coating and SLA surface modifications seem to have the potential to increase osseointegration also in T2DM rats when compared with a conventional machined surface.

Purpose: To develop a TiOx film with high wettability using plasma oxidation methodology and to evaluate the effect of such surface modification on new bone formation and early osseointegration., Materials and Methods: Twenty sandblasted and acid-etched (SLA) titanium implants layered with a TiOx film layer were modified by plasma oxidation using a Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RFPECVD) system. Twenty SLA implants without any treatment were employed as the control group. Scanning electron microscopy was used to evaluate surface morphology of the coating. X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical composition of the implant surface, and the wettability was tested with the help of the contact angle calculation. All implants were randomly inserted into the proximal tibia of 20 rats with a split-plot design. Four weeks after implantation, early osseointegration of the two groups was analyzed by a removal torque test and histologic analysis., Results: The surface characteristics showed that both SLA and plasma oxidization-treated SLA (PO-SLA) surfaces displayed similar typical isotropic irregular indentations. As revealed by the XPS analyses, both TiO 2 and Ti 2 O 3 were coexistent in the PO-SLA surface. The contact angle measurement revealed that the super-hydrophilic surface was created out in the PO-SLA surface. Four weeks after implantation, a higher removal torque value was observed in the group of implants with the PO-SLA surface compared with the control group (12.68 ± 1.07 vs 9.95 ± 1.42 Ncm, P < .05), and a higher rate of bone-to-implant contact was also detected in the same group of implants with the PO-SLA surface (47.79% ± 9.59% vs 39.41% ± 9.00%, P < .05). The bone area ratio was also higher in the PO-SLA surface group than the control group (39.10% ± 10.01% vs 29.01% ± 7.24%, P < .05)., Conclusion: It was indicated that the PO-SLA surface has combined the effect of high wettability and micro/nano-structures to notably increase early bone apposition.

Objectives: To systematically review the current dental literature regarding clinical accuracy of guided implant surgery and to analyze the involved clinical factors., Material and Methods: PubMed and Cochrane Central Register of Controlled Trials were searched. Meta-analysis and meta-regression analysis were performed. Clinical studies with the following outcome measurements were included: (1) angle deviation, (2) deviation at the entry point, and (3) deviation at the apex. The involved clinical factors were further evaluated., Results: Fourteen clinical studies from 1951 articles initially identified met the inclusion criteria. Meta-regression analysis revealed a mean deviation at the entry point of 1.25 mm (95% confidence interval [CI]: 1.22-1.29), 1.57 mm (95% CI: 1.53-1.62) at the apex, and 4.1° in angle (95% CI: 3.97-4.23). A statistically significant difference (P < .001) was observed in angular deviations between the maxilla and mandible. Partially guided surgery showed a statistically significant greater deviation in angle (P < .001), at the entry point (P < .001), and at the apex (P < .001) compared with totally guided surgery. The outcome of guided surgery with flapless approach indicated significantly more accuracy in angle (P < .001), at the entry point (P < .001), and at apex (P < .001). Significant differences were observed in angular deviation based on the use of fixation screw (P < .001)., Conclusions: The position of guide, guide fixation, type of guide, and flap approach could influence the accuracy of computer-aided implant surgery. A totally guided system using fixation screws with a flapless protocol demonstrated the greatest accuracy. Future clinical research should use a standardized measurement technique for improved accuracy., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Our aim was to investigate the impact of diabetes mellitus and different durations of glycaemic control on early osseointegration of dental implants, and to explore possible mechanisms by measuring the expression of integrin α5β1 and fibronectin in bone around the implant. We divided 33 male Zucker diabetic fatty (ZDF) rats aged 3 months into 3 groups. The first group comprised diabetic rats with dental implants (controls); the second group was treated with insulin and implants were placed simultaneously (exenatide alone group); and the third group was treated with insulin until the serum glucose was at a constant concentration (< 16 mmol/L), and implants were then inserted (exenatide+normal glucose group). Rats were killed 7, 14, 30, and 60 days after implants had been inserted. The expression of integrin α5β1 and fibronectin in bone around the implants was detected by immunohistochemical analysis in each group. The expression in the exenatide+normal glucose group was stronger than in the other 2 groups. Fourteen days after implantation, expression of integrin α5β1 in the exenatide alone group was significantly stronger than that in the control group (p=0.027), and 60 days after implantation the expression of fibronectin in the exenatide alone group was also significantly stronger than that among the controls (p=0.001). Both fibronectin and integrin α5β1 participate in the adhesion of osteoblasts and act as signals at the bone/implant interface. Diabetes interferes with the osseointegration of implants by deferring expression of fibronectin and integrin α5β1., (Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of this project is to investigate the impact of diabetes mellitus and different glycemic control times on early osseointegration of dental implants by expression and significance of serum bone Gla protein (BGP) and alkaline phosphatase (ALP) levels in Zucker diabetic fatty (ZDF) rats after implantation., Materials and Methods: The animals were divided into three groups, each group with 11 rats and each rat with two dental implants (33 rats and 66 implants in total): group A, diabetic rats with dental implants (controls); group B, diabetic rats treated with insulin and implants placed simultaneously; and group C, diabetic rats treated with insulin until serum glucose at a constant level and then implants be placed. Levels of BGP and ALP in the serum were measured by enzyme-linked immunosorbent assay in each group. The software program SPSS (version 17.0 for Windows) was used to analyze all data; p < .05 was set as the level of statistical significance., Results: At the 7th day, serum levels of BGP in group B and C were lower than that in group A (p > 0.05). At the 14th day, serum levels of BGP in group C were significantly higher (p < 0.05). After 30 days, compared with group A, the serum levels of BGP in group B and C seems to be lower. Compared with group A, the serum levels of ALP in group B and C were significantly higher, whereas the serum levels of ALP in group C seems to be higher than B (p < 0.05)., Conclusions: The present results suggest that injection of delayed release microsphere of exenatide on ZDF rats can release exenatide at a steady rate and the blood glucose can be controlled at a constant level. Implant survival rates could be enhanced in DM subjects when blood plasma glucose level is under control; the serum levels of BGP in this study seems to have no relationship with local osseointegration, whereas the serum levels of ALP might offer insights into the activity of osseointegration around the implant surface., (© 2013 Wiley Periodicals, Inc.)

Objectives The aim of this study was to perform a histomorphometric evaluation of the healing characteristics and jawbone remodeling processes in the peri-implant bone tissue of three commonly used implant surfaces, during the early weeks of osseointegration. Material and methods Dental implants with three different surfaces (anodically modified, hydroxyapatite ( HA)-coated and machined) were inserted into the mandibular side-tooth region of twelve adult mini-pigs. Histomorphometric analyses were performed to evaluate remodeling processes 3, 6 and 12 weeks post-implantation. Results Only a few very early bone remodeling-resorption sites were found at 3 weeks. After 6 weeks, additional signs of remodeling-related reversal and bone formation were detectable in all three groups, which steadily increased until 12 weeks. At the latter time point, the amount of remodeled bone was significantly higher for the anodized and HA-coated surfaces than for the machined implants. Conclusion The results of this study demonstrate that peri-implant bone remodeling can start as early as 3 weeks after implantation and continues at a substantial level up to 12 weeks. The anodic modification or HA coating of implant surfaces appears to accelerate the conversion of primary regenerated bone into more mature secondary lamellar bone. If this observation is of clinical relevance, it has to be clarified in studies that include longer observational time periods. [ABSTRACT FROM AUTHOR]