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Guided bone regeneration at zirconia and titanium dental implants: A pilot histological investigation
Abstract
Aim:
To test whether guided bone regeneration (GBR) of peri-implant defects at zirconia (ZrO2 ) implants differs from GBR at titanium (Ti) implants regarding the bone integration of the implant and of the grafting material.
Materials and methods:
Maxillary premolars and molars were extracted in seven dogs. After 5 months, four semi-saddle bone defects were created in each maxilla. Implant placement and simultaneous GBR were performed using the following randomly assigned modalities: (1) ZrO2 implant + deproteinized bovine bone mineral (DBBM) granules + a collagen membrane (CM), (2) ZrO2 implant + DBBM with 10% collagen matrix + CM, (3) ZrO2 implant + DBBM block + CM, and (4) Ti implant + DBBM granules + CM. After 3 months, one central histological section of each site was prepared. Histomorphometrical assessments were performed evaluating the augmented area (AA) within the former bone defect (primary outcome), the area of new bone (NB), bone substitute (BS), and non-mineralized tissue (NMT) within AA in mm(2) . In addition, the distance between the most coronal bone-to-implant contact and the margin of the former bone defect (fBIC-DEF), and the bone-to-implant contact fraction (BIC) were measured in mm.
Results:
AA measured 8.6 ± 4.0 mm(2) for ZrO2 implant + DBBM granules, 4.7 ± 1.6 mm(2) for ZrO2 implant + DBBM-collagen, 5.1 ± 1.9 mm(2) for ZrO2 implant + DBBM block, and 7.6 ± 2.8 mm(2) for Ti implant + DBBM granules. There were no statistically significant differences between the treatment modalities (P > 0.05). NB reached 2.0 ± 1.7 mm(2) for ZrO2 implant + DBBM granules, 0.9 ± 0.9 mm(2) for ZrO2 implant + DBBM-collagen, 2.1 ± 0.9 mm(2) for ZrO2 implant + DBBM block, and 0.8 ± 0.6 mm(2) for Ti implant + DBBM granules. fBIC-DEF amounted to 2.1 ± 1.7 mm(2) for ZrO2 implant + DBBM granules, to 2.7 ± 1.1 mm(2) for ZrO2 implant + DBBM-collagen, to 2.9 ± 1.2 mm(2) for ZrO2 implant + DBBM block, and to 3.4 ± 0.4 mm(2) for Ti implant + DBBM granules. BIC measured 70 ± 19% for ZrO2 implant + DBBM granules, 69 ± 22% for ZrO2 implant + DBBM-collagen, 77 ± 30% for ZrO2 implant + DBBM block, and 66 ± 27% for Ti implant + DBBM granules.
Conclusions:
The findings of the present pilot study suggest that zirconia and titanium implants grafted with DBBM granules and covered with a collagen membrane do not perform differently regarding the augmented ridge contour, the NB formation, and the implant osseointegration.
... Although proved effective as a space-making osteoconductive scaffold in obtaining a complete coverage of peri-implant bone dehiscences, particulate DBBM might be associated with a limited increase in thickness of the buccal bone plate. [6][7][8] Preclinical 6,7 and clinical 8 studies seem to suggest that guided bone regeneration (GBR) may result in an improvement of the peri-implant bone dehiscence as well as a relevant lateral bone augmentation when used with a DBBM block (bDBBM). The present study consists a proof-of-principle case report aimed at investigating if SPAL may be successfully used to obtain bone augmentation at peri-implant dehiscence sites when used with bDBBM. ...
... This consideration is well substantiated in the literature for the association of particulate DBBM and GBR. [6][7][8]10,11 In contrast, bDBBM may act as an efficacious osteoconductive scaffold while its mechanical properties would ensure a better dimensional stability at flap manipulation. Previous preclinical 6,7,11 and clinical 8 seems to corroborate our findings. ...
Background:
When used with deproteinized bovine bone mineral (DBBM) delivered as a particulate, the sub-periosteal peri-implant augmented layer (SPAL) technique was effective in completely correcting up to 92% of peri-implant buccal bone dehiscences. The use of a DBBM block (bDBBM), however, may result in an improvement of the peri-implant bone dehiscence as well as a relevant lateral bone augmentation since its mechanical properties may ensure a better dimensional stability at flap manipulation than particulate DBBM. The aim of the present a proof-of-principle case report is to investigate if SPAL may be successfully used to obtain bone augmentation at peri-implant dehiscence sites when used with bDBBM.
Case presentation:
Lateral bone augmentation was performed using the SPAL technique at two implants showing a buccal peri-implant bone dehiscence immediately after their placement. A partial-thickness flap was elevated, leaving the periosteal layer on the buccal cortical bone plate. The periosteal layer was, in turn, elevated to create a pouch, which was used to stabilize a bDBBM graft at the peri-implant buccal bone dehiscences. At re-entry, exposed implant surfaces were completely covered by new thick hard tissue up to their most coronal portion. A free epithelial-connective tissue graft was used to augment the peri-implant soft tissue phenotype.
Conclusion:
When used to accommodate bDBBM over the most coronal portion of an exposed implant, SPAL may successfully lead to an increase in peri-implant buccal tissue thickness.
... 3 However, ceramic materials have been proposed as an alternative option to meet the esthetic requirements of some patients and the needs of those with allergies to titanium, among others. 4,5 In particular, zirconia materials have been found to exert more positive effects on peri-implant tissue health [6][7][8] through their low affinity to bacterial colonization. Zirconia also offer favorable esthetic characteristics, 9,10 and ceramic implants of yttria-stabilized zirconia (Y-TZP) have been developed as an alternative to conventional titanium implants. ...
Objective: The objective of this study was to investigate the survival and biological and mechanical complications of one-piece and two-piece zirconia implants at five years of loading
Materials and Methods: Consecutive patients receiving zirconia implants were studied, collecting data at five years of loading on their clinical history, peri-implant health status, mechanical complications, esthetic results, and patient related outcomes.
Results: The study included 18 patients with 29 implants. The survival rate was 86% in implant-based analysis and 78% in patient-based analysis. There were no cases of peri-implantitis, but mucositis was present in 53% of implants. A mean of 4.1±0.81 mm was obtained for probing depth and 1.6±0.9 mm for crestal bone loss (radiographic assessment). There were no implant fractures. Major (10%) and minor (10%) prosthesis complications were observed. The esthetic outcome was moderate to almost perfect, with a high level of patient satisfaction. No significant association was found between survival rate and the presence of mucositis around one- or two-piece implants or any other study variable.
Conclusions: The survival rate is low for one- and two-piece zirconia implants. Both types of implants demonstrated a low mechanical complication rate. The incidence of periimplantitis is low but mucositis is present in 50%. Patient satisfaction related to esthetics and function is moderate to high. They represent a good option for patients requiring an alternative to titanium implants.
Clinical Relevance: Zirconia implants appear to be an alternative to the titanium option and may be indicated for patients requiring “metal-free” restorations.
... Zirconia is a standout amongst the most encouraging bio-ceramic that utilized as a dental implant owing its high mechanical properties 5) , different colors for different applied areas 6) , ability to keep the healthy gingiva color 7) , less inflammation around the implant 8) and comparable osseointegration 9) , translucency 10) , radiopacity 11) bacterial colonization 12) and biocompatibility 13,14) with titanium. However, zirconia has been known as a bioinert ceramic like Ti and numerous analysts detailed that the in vivo results for implantation indicate comparable outcome to the Ti 15,16) . ...
Yttria doped ZrO2 was deposited using an acidic zinc phosphatizing solution and the hydrothermal treatment. The coating was analyzed using a field emission-scanning electron microscope (FE-SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). A piston on three balls (ISO 6872) was used for the measurement of biaxial flexural strength. MC3T3-E1 cells attachment was evaluated by SEM, and cell proliferation were assessed using MTS assay™. SEM images confirmed that the zinc phosphate coating layer was successfully prepared and fully covered the surface. The measured adhesive strength of the coating was 79.11 MPa. In vitro cell study indicated that the coated sample had better cell morphology and proliferation. XRD and EDS analysis revealed that the crystalline coating structure indexed as zinc phosphate (hopeite) and the substrate was assigned as zirconia. The flexural strength test showed that the strength of zirconia before and after hydrothermal treatment was not affected.
... Aluminium oxide (Al 2 O 3 , alumina), a ceramic material for dental implants introduced at a similar time as titanium implants (Sandhaus, 1968;Sandhaus, 1971;Schulte & Heimke, 1976), was eventually withdrawn from the market due to an increased risk of implant fractures (Ananth et al., 2015;Andreiotelli et al., 2009;Hobkirk & Wiskott, 2009;Kohal et al., 2004). Zirconium dioxide (ZrO 2 , zirconia), however, shows favourable physicochemical properties (high bending strength and fracture toughness) depending upon its composition and processing (Piconi & Maccauro, 1999;Sivaraman et al., 2018) as well as high biocompatibility similar to titanium (Benic et al., 2017b;Bormann et al., 2012;Janner et al., 2018;Roehling et al., 2019). Although long-term results for zirconia implants are still missing and elevated heat generation was reported in vitro during implant insertion with zirconia implants when compared to titanium implants (Zipprich et al., 2019), promising clinical data investigating the outcome of one-piece zirconia implants after an observation period of 5 years have been recently obtained (Balmer et al., 2020). ...
Objectives
The aim of this study was to evaluate thermal effects of ceramic and metal implant drills during implant site preparation using a standardised bovine model.
Material and Methods
A total of 320 automated intermittent osteotomies of 10‐ and 16‐mm drilling depths were performed using zirconium‐dioxide‐based and stainless steel drills. Various drill diameters (2.0 / 2.2, 2.8, 3.5, 4.2 mm ∅) and different cooling methods (without / with external saline irrigation) were investigated at room temperature (21 ± 1°C). Temperature changes were recorded in real‐time using 2 custom‐built multichannel thermoprobes in 1‐ and 2‐mm distance to the osteotomy site. For comparisons a linear mixed model was estimated.
Results
Comparing thermal effects, significantly lower temperatures could be detected with steel‐based drills in various drill diameters, regardless of drilling depth or irrigation method. Recorded temperatures for metal drills of all diameters and drilling depths using external irrigation were below the defined critical temperature threshold of 47°C, whereas ceramic drills of smaller diameters reached or exceeded the harmful temperature threshold at 16‐mm drilling depths, regardless of whether irrigation was applied or not. The results of this study suggest that the highest temperature changes were not found at the deepest point of the osteotomy site but were observed at subcortical and deeper layers of bone, depending on drill material, drill diameter, drilling depth and irrigation method.
Conclusions
This standardised investigation revealed drill material and geometry to have a substantial impact on heat generation, as well as external irrigation, drilling depth and drill diameter.
... Neste artigo apresentamos implantes de zircônia de corpo único e de duas partes reabilitando espaços de região anterior e posterior, com rebordos cicatrizados, com alvéolos frescos, associado à regeneração óssea ou ainda com instalação guiada. Benic et al. 9 , em um estudo em animais, já observaram que os resultados da regeneração óssea guiada ao redor de implantes de titânio e de zircônia são muito semelhantes no que diz respeito à osseointegração, formação de novo osso e aumento de osso. Todos os casos apresentados neste artigo obtiveram 100% de sucesso clínico dos implantes e das próteses. ...
RESUMO Os implantes de zircônia são parafusos livres de metal que teoricamente podem substi-tuir os implantes de titânio. O objetivo deste artigo foi discutir as indicações para instalação dos implantes de zircônia e sua versatilidade nas reabilitações, ilustrando com casos clínicos. Esses casos mostram os implantes metal free aplicados em área anterior ou posterior, asso-ciado à regeneração óssea guiada, cirurgia guiada, em alvéolo fresco ou rebordo cicatrizado, com utilização de implantes de corpo único ou duas partes. Ao final de um ano de carrega-mento dos implantes, foi observado 100% de sucesso dos implantes e próteses instalados. Apesar de estudos de curto período de acompanhamento apresentarem resultados otimis-tas, são necessários mais estudos comparativos e de longo prazo. Descritores: Implantes dentários, cerâmica, ligas metalocerâmicas. ABSTRACT Zirconia implants are metal-free screws that can theoretically replace titanium implants. The aim of this paper was to discuss the indications for installation of zirconia implants and their versatility in rehabilitation, illustrating with cases report. These clinical cases show the metal free implants applied in the anterior or posterior area, associated with guided bone regeneration, guided surgery, fresh socket or completely healed ridge, using monotype or two-pieces implants. At one-year follow-up of implant loading, 100% success of the implants and prostheses was observed. Although short-term follow-up studies show optimistic results, further comparative and long-term studies are needed. Descriptors: Dental implants, zirconium, metal ceramic alloys. Versatilidade de aplicações para os implantes de zircônia-relato de casos
... after 16 weeks 22 . Benic et al. reported a BIC of 66% at 3 months after GBR was performed using deproteinized bovine bone mineral in the mandible of dogs 23 . A further study demonstrated that when mandibular bone defects were filled with either xenogeneic or synthetic bone substitutes, a two-stage implant placement protocol resulted in higher BIC than an immediate implant placement protocol (40.8% and 36.1% compared to 19.6% and 23.9%) after 8 weeks 24 . ...
The in vivo regeneration of bone flaps might be an alternative to autogenous bone grafting. The first human case of mandibular reconstruction using the greater omentum as a bioreactor was reported in 2016. However, whether engineered bone will support the osseointegration of dental implants has not yet been investigated. In this study, bone tissue engineering was performed in the greater omentum of nine miniature pigs using bone morphogenetic protein 2, bone marrow aspirate, and three different scaffolds: hydroxyapatite, biphasic calcium phosphate (BCP), and titanium. After 8 weeks, two implants were placed in each scaffold; after another 8 weeks, the bone blocks were harvested for radiographic, histological, and histomorphometric analysis. All implants exhibited sufficient primary stability, and the success rate was 100%. The bone-to-implant contact ratios (BICs) were 38.2%, 68.5%, and 42.9%; the inter-thread bone densities were 29.4%, 64.9%, and 33.5%; and the peri-implant bone-scaffold densities were 56.4%, 87.6%, and 68.6% in the hydroxyapatite, BCP, and titanium groups, respectively. The BIC showed a strong correlation (r = 0.76) with the peri-implant bone-scaffold density. This study shows that de novo engineered bone leads to successful osseointegration and therefore may allow implant-based prosthodontic rehabilitation. © 2019 International Association of Oral and Maxillofacial Surgeons
Purpose: To assess the literature comparing histologic levels of osseointegration for titanium vs zirconia dental implants. Materials and Methods: This systematic review was conducted following the PRISMA guidelines and was registered in PROSPERO (CRD42021236781). Electronic and manual searches were carried out through the PubMed/MEDLINE, PubMed Central, and Embase databases with a platform-specific search strategy combining controlled terms (MeSH and Emtree) and text words. The articles were selected by two independent investigators who evaluated the articles based on the criteria for eligibility. Results: A total of 17 articles were included. All were preclinical studies. The populations included dogs (27.55%), minipigs (14.28%), rats (14.28%), and rabbits (43.89%); and the implantation site varied among the mandible (36.82%), maxilla (9.04%), tibia (17.64%), skull (10.70%), and femur (25.80%). A total of 370 titanium (Ti) implants and 537 zirconia (Zr) implants were evaluated. The average osseointegration (% bone-to-implant contact) for Zr was 55.51% (17.6% to 89.09%), and for Ti was 58.50% (23.2% to 87.85%). There was no statistical difference between studies at the 2-month follow-up (P = .672), but this difference was significant at 1 and 3 months (P < .001). Conclusions: Within the limitations of this review, Zr implants had a similar level of osseointegration compared to Ti implants. Nonetheless, because these findings are based on preclinical research, all data must be carefully examined.
Objective:
To histologically evaluate soft tissue healing following immediately placed one-piece zirconia implant and grafting a xenograft into the buccal gap.
Material and methods:
The third and fourth premolars (PM3 and PM4) in both quadrants of the mandible of nine dogs were used for this experiment. Those teeth were removed flapless and implants were placed into the distal sockets in a lingual position. In one side of the jaw, the gap between the implant and the socket walls was grafted (test) while no grafting was performed in the contralateral side (control), randomly selected. After 6 months of healing, biopsies were obtained and prepared for histological analysis. Soft tissue measures like supracrestal soft tissue height (STH), length of barrier epithelium (BE) and connective tissue (CTC) were measured at buccal and lingual surfaces.
Results:
The marginal mucosa was in a coronal position on the test side compared with the control side. At the buccal surface, the BE was longer in the test side than in the control side, while the CTC was longer in the control side than in the test side. For the STH (BE + CTC) the difference between the groups was not statistically significant.
Conclusion:
The placement of a xenograft into the gap between 1-piece zirconia implant and the buccal wall in dogs modified the process of soft tissue healing, providing less soft tissue recession. The gap size seems to have a modifying effect on the application of this protocol.
Tissue engineering is an interdisciplinary field. Despite the name, most tissue engineering does not involve traditional engineering. Tissue engineering is about restoring tissue damaged by trauma or disease to its original condition. That in turn requires knowledge of the cellular structure of tissue and, in the case of musculoskeletal tissues like cartilage and bone, the extracellular matrix. Nanotechnology can be used in various ways for biomedical applications. The use of nanoparticles for site-specific, targeted drug delivery is widely reported by researchers. The major advantage is that you can target the drug to a specific site. Furthermore, you can control the release with the help of internal or external stimuli. The other highly explored area is to develop scaffolds for tissue engineering. Bio ceramics are basically inorganic materials with a mix of ionic and covalent bonding. These materials are an important source of biomaterial in biomedical engineering applications. The materials present the ideal properties for bone replacement and tissue engineering and are leading to a new era of regeneration materials. In this review, we discuss the various nanoparticles and bio ceramics that have been employed to upbring the field of hard tissue engineering to this current level.
Aim:
To test whether soft-type block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to different dimension of the augmented hard tissue than particulate bone substitute.
Material & methods:
In 40 patients, 40 two-piece dental implants were placed >2 months after tooth extraction. Following random allocation, 20 peri-implant bone dehiscences were grafted with a soft-type block made of synthetic biphasic calcium phosphate (BCP) + collagen and 20 bone dehiscences with particulate BCP. All the sites were covered with a collagen membrane stabilized with titanium pins. Immediately after wound closure and after 6 months, the horizontal dimension (HD) of the augmented hard tissue was measured at the level of implant shoulder using cone beam computed tomography. During re-entry at 6-months, the defect fill was clinically assessed.
Results:
At 6 months, the median HD measured 1.15 mm (mean: 1.31) in the soft-block group and 0.93 mm (mean: 1.05 mm) in the particulate group (p = 0.6). At 6 months, 7.1% of contained defects and 61.9% of non-contained defects showed an incomplete vertical defect fill.
Conclusions:
Soft-type block of BCP + collagen used for GBR of peri-implant defects did not differ from particulate BCP regarding the dimension of the augmented hard tissue after 6 months of healing. This article is protected by copyright. All rights reserved.
Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.
This article gives an overview of ceramics-based biomaterials with particular emphasis on their various properties and health care applications. Furthermore, bio ceramics are grouped as oxide and nitride-based bioinert ceramics, bioresorbable calcium phosphate-based materials and bioactive glasses/glass ceramics. Ceramics and bioglasses are good biomaterials, here mainly focused on bone replacement applications. Mesoporous glasses, nanocrystalline ceramics and composites, having a high surface area, corrosion resistive and better mechanical properties, could be future biomaterials. Controlled porosity with uniform pores distributed biomaterials could be achieved using fine synthesis routes like sol-gel and additive manufacturing. Bioceramics and bioglasses could also be synthesized by agro-food wastes and optimize their properties according to need and applications easily. Moreover, these sustainable resources exhibit inherent porosity due to presence of organic substance attached with inorganic materials. As crystallinity increased, the bioactivity decreases of ceramics. Both properties can be optimised using nano-crystalline and composite biomaterials.
Objective:
To evaluate the effect of two barrier membranes [multilaminated small intestinal submucosa (mSIS) and bioresorable collagen membrane (Bio-Gide)] combined with deproteinized bovine bone mineral Bio-Oss on guided bone regeneration through a canine extraction sockets model.
Methods:
The distal roots of 18 premolars of the Beagle' s bilateral maxillary and mandibular were removed, and 18 extraction sockets were obtained. They were randomly divided into 3 groups, and the following procedures were performed on the sockets: (1) filled with Bio-Oss and covered by mSIS (mSIS group), (2) filled with Bio-Oss and covered by Bio-Gide (BG group), (3) natural healing (blank control group). Micro-computed tomograph (Micro-CT) was performed 4 and 12 weeks after surgery to eva-luate the new bone regeneration in the sockets of each group.
Results:
The postoperative healing was uneventful in all the animals, and no complications were observed through the whole study period. Micro-CT analysis showed that the new bone fraction in the mSIS group and the BG group was significantly higher than that in the blank control group at the end of 4 weeks and 12 weeks (P < 0.05), and more new bone fraction was observed in the mSIS group than in the BG group, but the difference was not statistically significant (P>0.05). The new bone fraction of coronal third part of the socket in the mSIS group and BG group at the end of 4 weeks were significantly higher than that of the middle and apical third part of each group (P < 0.05). The values of bone mineral density were similar at 4 weeks in all the groups (P>0.05), but were significantly higher than that in the control group at the end of 12 weeks (P < 0.05). The bone morphometric analysis showed that the trabecular number and trabecular spacing were significantly better in the mSIS group and the BG group than in the control group at the end of 4 weeks and 12 weeks (P < 0.05), while the value in the mSIS group was slightly higher than in the BG group, but the difference was not statistically significant (P>0.05). The difference in trabecular thickness between all the groups was not statistically significant (P>0.05).
Conclusion:
mSIS membrane as a barrier membrane combined with deproteinized bovine bone mineral can enhance new bone formation in canine extraction sockets, similar to Bio-Gide collagen membrane.
Background. Currently, using of osteointegrated titanium implants has become a key component for restoring lost function in various areas of clinical medicine. The actual issue remains preservation or reconstruction of bone tissue for optimal use of titanium implants in traumatology and orthopedics, as well as in maxillofacial surgery. One of the most common grafts are hydroxyapatite-based material with various inclusions, for example, an antibiotic.
The aim of the study is to characterize the regeneration of bone tissue of the jaws alveolar ridge using the hydroxyapatite-based material “Collapan-L” in clinical practice.
Material and Methods. The study of the material “Collapan-L” (Intermedapatit, Russia) using involved 30 patients with a diagnosis “chronic periodontitis of the tooth”. Patients underwent complex surgical and orthopedic treatment to restore masticatory function. At the first stage, teeth were removed with the “Collapan-L” material used to preserve the alveolus. 4 months after extraction, dental implantation was performed with simultaneous trephine biopsy from the augmentation zone for histomorphometric analysis. At the stage of implant placement and before prosthetics the stability dynamics was measured.
Results. The study involved 42 tissue samples obtained at periods from 9 to 32 weeks after removal. The morphological assessment of bone tissue from the implantation zone determined that after 4 months trabeculae from the newly formed bone, including small fragments of biomaterial, were revealed; at the same time, there were signs of biodegradation of the implanted material fragments, there was no inflammatory infiltrate. After 6 months in a significant part of cases the granules of bone material were not found, which indicates a pronounced osseointegration of the material. In its structure, the formed bone tissue differences barely noticeable from the native one, which allows us to conclude that by the time of 24 weeks, the processes of reparative osteogenesis in the alveolus are completed.
Conclusion. Histological examination and assessment of changes in the stability showed that using of bone replacement material after tooth extraction can increase the regenerative potential of bone tissue, avoid additional surgical interventions to increase the volume of bone tissue in the area of future implantation, and the formed bone tissue is close in its structure to the native one.
Objective
To histologically evaluate healing following grafting a xenogenous bone substitute in the buccal gap around the immediately placed one‐piece zirconia implant.
Material and methods
The third and fourth premolars (PM3, PM4) in both quadrants of the mandible of nine Mongrel Hound dogs were used for this experiment. They have been removed and the recipient sites were prepared. The implants were placed in a lingual position in the socket. In one side of the jaw, the gap between the implant and the socket walls was grafted (test) while no grafting was performed in the contralateral side (control), randomly selected. After 6 months of healing, biopsies were obtained and prepared for histological analysis. Vertical and horizontal measures were recorded in buccal and lingual surface.
Results
The hard tissue was in a coronal position on the test side compared to the control side. The bone thickness around ZLA (zirconia large‐grit sandblasted and acid‐etched surface) level was larger on the test side. On the test side, the first bone‐implant contact and bone crest, at the buccal aspect, were more coronal to ZLA in PM4 while in PM3 the same happened with the bone crest. The width of the buccal bone wall was larger in PM4 than in PM3 at the ZLA level and 1mm apical to ZLA.
Conclusion
The placement of a xenograft in the gap between 1‐piece zirconia implant and the buccal wall in dogs modified the process of hard tissue healing, providing additional amount of hard tissue.
In this study, crystalline ZrO2 nanoparticles were synthesized in one pot at room temperature using an extremophilic Acinetobacter sp. KCSI1 and characterized using various techniques to study its structural, optical and crystalline properties. The average size of the ZrO2 nanoparticles was found to be 44 ± 7 nm. The XRD and Raman spectra showed the crystalline structure of ZrO2. HRTEM and SAED images showed well aligned ordered crystal lattice nanoparticles. The zeta potential of Bio-NP of ZrO2 has been found to be 36.5 ± 5.46 mV. The mechanical behaviour such as hardness and Young's modulus of Bio-ZrO2 NPs were determined using atomic force microscopy (AFM) and found to be 9.206 ± 2.22 and 0.285 ± 0.13 GPa, respectively. No significant cytotoxicity for ZrO2 nanoparticles was observed when tested with mouse fibroblast cells (L929), suggesting that the synthesized ZrO2 nanoparticle is biocompatible and safe for environmental applications.
Objective
To histologically and radiographically evaluate soft (primary outcome) and hard tissue integration of two‐piece titanium and zirconia dental implants with/without buccal dehiscence defects.
Materials & Methods
In 6 dogs, five implants were randomly placed on both sides of the mandible: i) Z1: a zirconia implant (modified surface) within the bony housing, ii) Z2: a zirconia implant (standard surface) within the bony housing, iii) T: a titanium implant within the bony housing, iv) Z1_D: a Z1 implant placed with a buccal bone dehiscence (3mm in height, identical width to implant body), and v) T_D: a titanium implant placed with a buccal bone dehiscence. Two weeks of healing and 6 months of loading were applied on each hemi‐mandible, respectively.
Results
The median level of the margo mucosae shifted more apically over time in all groups (borderline statistical significance in groups Z1_D: ‐0.52 mm and T_D: ‐1.26 mm). The median height of the peri‐implant mucosa in groups Z1_D and T_D was greatest at 2 weeks and 6 months, but the linear change in the peri‐implant mucosa was significant only for group T_D over time (‐1.45 mm). Z1 demonstrated a higher bone‐to‐implant contact compared to Z2 and T. Minimal change of radiographic marginal bone levels in all groups were observed (less than 1 mm).
Conclusion
When buccal dehiscence was presented, titanium implants presented significant loss of peri‐implant mucosal height compared to zirconia implants with a modified surface, due to greater apical shift of the margo mucosae. A modified zirconia surface enhanced osseointegration.
This article is protected by copyright. All rights reserved.
Titanium dioxide nanotubes (TNTs) have drawn wide attention and been extensively applied in the field of biomedicine, due to their large specific surface area, good corrosion resistance, excellent biocompatibility and enhanced bioactivity. This review describes the preparation of TNTs and the surface modification which entrust the nanotubes with better antibacterial property and enhanced osteoblast adhesion, proliferation and differentiation. Considering the contact between TNTs surface and surrounding tissues after implantation, the interactions between TNTs (with properties including diameter, length, wettability and crystalline phase) and proteins, platelets, bacteria and cells are illustrated. The state of the art in the applications of TNTs in dentistry, orthopedic implants and cardiovascular stents have been introduced. In particular, the application of TNTs in biosensing has attracted much attention due to its ability of rapid diagnosis of diseases. Finally, the difficulties and challenges for practical application of TNTs are also discussed.
Objectives:
The aims of this randomized clinical trial were to compare the dimensional changes and the histological composition after using deproteinized bovine bone mineral (DBBM) or deproteinized bovine bone mineral with 10% collagen (DBBM-C) and a collagen membrane in ridge preservation procedures.
Material and methods:
Patients who required an extraction and a subsequent implant-supported rehabilitation at a non-molar site were recruited. After extraction, a cone beam computed tomography (CBCT) was performed and sites were randomly treated either with DBBM or DBBM-C plus a collagen membrane. At 5 months, before implant placement, a second CBCT was performed and a biopsy of the area was obtained. A blinded investigator superimposed the CBCTs and performed measurements to determine bone volume changes between the two time points. Additionally, a histomorphometric analysis of the biopsies was performed in a blinded manner.
Results:
Eleven sites belonged to the DBBM group and eleven to the DBBM-C group. All together, a significant reduction in height and width was observed at 5 months of healing, but no statistically significant differences were observed between the DBBM and the DBBM-C group. The histomorphometric analysis revealed a similar composition in terms of newly formed bone, connective tissue and residual graft particles in both groups.
Conclusions:
Deproteinized bovine bone mineral with 10% collagen showed a similar behaviour as DBBM not only in its capacity to minimize ridge contraction but also from a histological point of view. Thus, both graft materials seem to be suitable for ridge preservation procedures.
Aim of this controlled prospective randomized study was to evaluate the outcome of two-piece zirconia implants compared to titanium implants over a period of up to 24 months.
A total of 31 implants (16 zirconia/Ziterion vario Z(®) + 15 titanium/Ziterion vario T(®) ) were inserted primary stable (>30 Ncm) in the maxilla (7) and mandible (24) of 22 patients (13 male, nine female) requiring neither bone nor soft tissue augmentation. After a healing period of 6 months in the maxilla and 4 months in the mandible, ceramic abutments were luted adhesively to the zirconia implants and definitive all-ceramic restoration was performed with high-density ceramics. Radiographic bone levels, condition of the peri-implant mucosa, aesthetic outcome, implant survival and success were recorded for up to 24 months.
Measurements of mean marginal bone levels 24 months after surgery showed a significant bone loss (P < 0.001) in both groups (Ti: 1.43 (SD ± 0.67) vs. Zir 1.48 (SD ± 1.05). One zirconia implant was lost 8 months after restoration. No further complications were recorded, giving an overall survival and success rate of 93.3% for zirconia and 100% for titanium implants after a period of up to 24 months.
After 24 months, success rates of the two-piece ceramic implants showed no significant difference compared to control two-piece titanium implants. The bonded zirconia implant abutment connection appears to be capable with clinical application over the observed period. However, further control measurements need to confirm the presented data.
Background:
Early implant placement with simultaneous contour augmentation is documented with short- and medium-term studies. The long-term stability of contour augmentation is uncertain.
Methods:
In this prospective, cross-sectional study, 41 patients with an implant-borne single crown were examined twice, in 2006 and 2010. Clinical, radiologic, and esthetic parameters were assessed at both examinations. In addition, a cone beam computed tomographic (CBCT) image was obtained during the second examination to assess the dimensions of the facial bone wall.
Results:
All 41 implants demonstrated ankylotic stability without signs of peri-implant infection at both examinations. The clinical parameters remained stable over time. Satisfactory esthetic outcomes were noted, as assessed by the pink and white esthetic score (PES/WES) indices. Overall, the PES scores were slightly higher than the WES scores. None of the implants developed mucosal recession over time, as confirmed by values of the distance between implant shoulder and mucosal margin and cast measurements. The periapical radiographs yielded stable peri-implant bone levels, with a mean distance between implant shoulder and first visible bone-implant contact value of 2.18 mm. The CBCT analysis demonstrated a mean thickness of the facial bone wall ≈2.2 mm. In two implants (4.9%) no facial bone wall was detectable radiographically.
Conclusions:
This prospective cross-sectional study demonstrates stable peri-implant hard and soft tissues for all 41 implants examined and satisfactory esthetic outcomes overall. The follow-up of 5 to 9 years confirmed again that the risk for mucosal recession is low with early implant placement. In addition, contour augmentation with guided bone regeneration was able to establish and maintain a facial bone wall in 95% of patients.
Aim:
The aim of the present prospective study was to evaluate the long-term outcome of implants placed simultaneously with guided bone regeneration (GBR) using resorbable and non-resorbable membranes.
Materials and methods:
The original study population consisted of 72 patients receiving a total of 265 implants. In all GBR-treated sites, demineralized bovine bone mineral (DBBM) was used in combination either with a collagen (CM) or an Expanded polytetrafluoroethylene (e-PTFE) membrane. A total of 112 implants was treated with CM, 41 implants were treated with e-PTFE membranes, and 112 served as a control group because implants were entirely surrounded by bone and did not need any GBR procedures. Clinical and radiographic analyses were performed after a period of 12-14 years.
Results:
The median follow-up time was 12.5 years (range 12-14 years). A total of 58 patients participated in the present investigation, corresponding to 80.5% of the original study population. The cumulative implant survival rate at the follow-up examination was 93.2%. For the control group the cumulative survival rate was 94.6%, for the CM 91.9%, and for the e-PTFE 92.6%. Differences among the groups were not statistically significant. The radiographically determined marginal bone level (MBL) amounted to: control 2.36 mm (SD), CM 2.4 mm (SD), e-PTFE 2.53 mm (SD). There is no evidence (P < 0.2) that the slope of bone level over time is different for the three treatment groups.
Conclusion:
It is concluded that implants placed simultaneously with GBR procedures using resorbable or non-resorbable membranes reveal a high survival rate ranging from 91.9% to 92.6%, therefore it is considered to be a safe and predictable therapy. [Correction added after online publication 30 November 2012: the marginal bone level of CM, e-PTFE, and control was corrected to 'control 2.36 mm (SD), CM 2.4 mm (SD), e-PTFE 2.53 mm (SD)' in the Results section].
The objective of this review was to evaluate the efficacy of different grafting protocols for the augmentation of localized alveolar ridge defects.
A MEDLINE search and an additional hand search of selected journals were performed to identify all levels of clinical evidence except expert opinions. Any publication written in English and including 10 or more patients with at least 12 months of follow-up after loading of the implants was eligible for this review. The results were categorized according to the presenting defect type: (1) dehiscence and fenestration-type defects, (2) horizontal ridge augmentations, (3) vertical ridge augmentations, and (4) maxillary sinus floor elevations using the lateral window technique or transalveolar approach. The review focused on: (1) the outcome of the individual grafting protocols and (2) survival rates of implants placed in the augmented bone.
Based on 2,006 abstracts, 424 full-text articles were evaluated, of which 108 were included. Eleven studies were randomized controlled clinical trials. The majority were prospective or retrospective studies including a limited number of patients and short observation periods. The heterogeneity of the available data did not allow identifying one superior grafting protocol for any of the osseous defect types under investigation. However, a series of grafting materials can be considered well-documented for different indications based on this review. There is a high level of evidence (level A to B) to support that survival rates of implants placed in augmented bone are comparable to rates of implants placed in pristine bone.
In the last decade the number of bioscience journals has increased enormously, with many filling specialised niches reflecting new disciplines and technologies. The emergence of open-access journals has revolutionised the publication process, maximising the availability of research data. Nevertheless, a wealth of evidence shows that across many areas, the reporting of biomedical research is often inadequate, leading to the view that even if the science is sound, in many cases the publications themselves are not “fit for purpose”, meaning that incomplete reporting of relevant information effectively renders many publications of limited value as instruments to inform policy or clinical and scientific practice [1–21]. A recent review of clinical research showed that there is considerable cumulative waste of financial resources at all stages of the research process, including as a result of publications that are unusable due to poor reporting [22]. It is unlikely that this issue is confined to clinical research [2–14,16–20].
To evaluate whether immediate non-occlusal loading of single zirconia implants could reduce early failures when compared to immediate occlusal loading.
Forty partially edentulous patients who received one single zirconia implant (Z-Systems) at least 10 mm long and 3.25 mm wide inserted with a torque of at least 35 Ncm were randomised to immediate occlusal or non-occlusal loading groups. All patients received provisional acrylic crowns the same day of implant placement. Provisional crowns were replaced after 4 to 5 months by definitive full ceramic crowns. Outcome measures were implant success, any complications and peri-implant marginal bone levels.
One year after loading, no patients had dropped out. Five implants (12.5%) failed early: three occlusally loaded and two non-occlusally loaded. Three complications occurred, all after delivery of the definitive crowns: one crown fractured (occlusal loading), one had to be remade after debridement because of hyperplastic tissues (occlusal loading), and one crown decemented (nonocclusal loading). These differences were not statistically significant. Both groups gradually lost periimplant bone in a highly statistically significant way. One year after loading, patients subjected to non-occlusal loading lost an average of 0.7 mm of peri-implant bone versus 0.9 mm in the occlusal group. This difference in bone loss between groups was not statistically significant. There was an association between immediate post-extractive implants and implant failures (P=0.01). Four of the 10 immediate post-extractive implants (40%) failed versus one out of 30 delayed implants (3%).
The results of this study do not provide a conclusive answer to whether immediate non-occlusal loading may decrease implant failures. Immediately loaded zirconia implants placed in post-extractive sites had high failure rates.
to compare the amount of new bone produced by Bio-Oss((R)) Collagen to that produced by collagen matrix in vivo.
eighteen bone defects, 5mm by 10mm were created in the parietal bone of 9 New Zealand White rabbits. 6 defects were grafted with Bio-Oss((R)) Collagen. 6 defects were grafted with collagen matrix alone (positive control) and 6 were left empty (negative control). Animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Quantitative analysis of new bone formation was made on 100 sections (50 sections for each group) using image analysis.
A total of 339% more new bone was present in defects grafted with Bio-Oss((R)) Collagen than those grafted with collagen matrix (positive control). No bone was formed in the negative control group.
Bio-Oss((R)) Collagen has the effect of stimulating new bone formation locally compared with collagen matrix in vivo. Bio-Oss((R) )Collagen may be utilized as a bone graft material.
Objectives:
To test whether GBR with an L-shaped soft-block bone substitute and particulate bone substitute differs from GBR with particulate bone substitute as regards the volume stability of the augmented region during flap closure.
Materials and methods:
Twenty peri-implant box-shaped bone defects were created in 10 pig mandibles. Every bone defect was augmented with each of the following two GBR procedures in turn: control group - particulate xenograft applied buccally + collagen membrane + pins; test group - particulate xenograft applied buccally + L-shaped soft-block xenograft applied buccally and occlusally + collagen membrane + pins. Cone-beam computed tomography scans were obtained before and after wound closure. The horizontal thickness (HT) of the augmented region (bone substitute + membrane) was assessed at the implant shoulder (HT0 mm ) and at 1 mm to 5 mm apical to the implant shoulder (HT1 mm -HT5 mm ). In the test group, the vertical thickness (VT) and 45° thickness (45-T) of the augmented region were measured from the implant shoulder. The changes in HT during flap suturing were calculated as absolute (mm) and relative values (%). Repeated-measures ANOVAs were used for statistical analysis.
Results:
The reduction in HT0 mm was 20.5 ± 23.3% (SD) in the control group and 2.4 ± 9.2% (SD) in the test group (P = 0.014). There were no statistically significant differences in changes in HT1-5 mm between the groups (P > 0.05). In the test group, the reduction in VT amounted to 28.0 ± 11.9% (SD) and the reduction in 45-T amounted to 24.8 ± 10.2% (SD) (P < 0.001).
Conclusion:
The addition of an L-shaped soft-block bone substitute to a particulate xenograft, covered by a collagen membrane and fixed with pins, significantly improved the horizontal volume stability of the augmented region during wound closure.
Objective:
To assess whether or not peri-implant soft tissue dimensions and hard tissue integration of loaded zirconia implants are similar to those of a titanium implant.
Materials and methods:
In 6 dogs, two one-piece zirconia implants (VC, ZD), a two-piece zirconia implant (BPI) and a control one-piece titanium implant (STM) were randomly placed. CAD/CAM crowns were cemented at 6 months. Six months later, animals were sacrificed and histomorphometric analyses performed, including: the level of the mucosal margin, the extent of the peri-implant mucosa, the marginal bone loss and the bone-to-implant contact (BIC). Means of outcomes variables were calculated together with their corresponding 95% confidence intervals.
Results:
In general, the mucosal margin was located coronally to the implant shoulder. The buccal peri-implant mucosa ranged between 2.64mm±0.70mm (VC) and 3.03mm±1.71mm (ZD) (for all median comparisons p>0.05). The relative marginal bone loss ranged between 0.65mm±0.61mm (BPI) and 1.73mm±1.68mm (ZD) (buccal side) and between 0.55mm±0.37mm (VC) and 1.69mm±1.56mm (ZD) (lingual side) (p>0.05). The mean BIC ranged between 78.6%±17.3% (ZD) and 87.9%±13.6% (STM) without statistically significant differences between the groups (p>0.05).
Conclusions:
One- and two-piece zirconia rendered similar peri-implant soft tissue dimensions and osseointegration compared to titanium implants 6 months of loading. Zirconia implants, however, exhibited a relatively high fracture rate. This article is protected by copyright. All rights reserved.
The aim of this clinical trial was to evaluate the safety and efficiency of a one-piece zirconia oral implant after 1 year of function.
Two centers included 60 subjects in need of implant-supported single-tooth restorations or three-unit bridges. A total of 71 zirconia one-piece implants were placed and immediately restored with a temporary reconstruction for at least 2 months. The final veneered zirconia restorations were then cemented and followed for 6 months and 1 year after insertion of the restorations. At each visit, a clinical evaluation was performed to analyze biological parameters of the implants and the neighboring teeth. A standardized periapical radiograph was taken at implant insertion, at the placement of the restorations and at the 1-year follow-up.
Sixty patients with 71 implants (48 in the mandible, 23 in the maxilla) were included in this study and provided with 11 bridges and 49 crowns. Two patients with three implants (one bridge and one single crown) could not be evaluated. One patient lost his implant 5 weeks after implant insertion. Based on 58 patients, the mean survival rate was 98.3% after one year when the implants of the two patients that did not show up were not counted as lost. The mean marginal bone loss from implant insertion to the 1-year follow-up after the final prosthetic restoration was 0.78 mm with a standard deviation of 0.79 mm. The probing depth around the implants increased from 2.7 mm at insertion of the prosthetic reconstruction to 3.5 mm one year after insertion. The probing depth around the adjacent teeth remained stable at 2.5 mm. At the 1-year recall, the difference was significant. The clinical attachment levels at implants and teeth were not different at the 1-year follow-up with 3.1 mm at tooth and implant sites.
The presently tested one-piece ceramic implant was successful in replacing single tooth and three-unit gaps after one year of function. Further long-term data are necessary to verify these initial findings.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
To test whether an equine bone substitute block used for guided bone regeneration (GBR) of peri-implant defects renders different results from bovine block or particulated bone substitutes regarding the dimensions of the augmented ridge and the amount of new bone.
Mandibular premolars and molars were extracted in eight dogs. After 4 months, four semi-saddle bone defects were created in each mandible and one titanium implant was inserted into every site. Bone augmentation by GBR was attempted using the following randomly assigned modalities: (i) particulated deproteinized bovine bone mineral (DBBM) + a collagen membrane (CM), (ii) block DBBM + CM, (iii) equine bone substitute block + CM, and (iv) empty controls. After 4 months, one central and two lateral sections of each site were prepared. Descriptive histological and histomorphometrical assessments were performed evaluating the augmented area (AA) within the former bone defect, the area of mineralized tissue (MT), non-mineralized tissue (NMT), and residual bone substitute (BS) within AA, the horizontal thicknesses of the augmented region (HTaugm ) and of the mucosa (HTmucosa ).
At the central sections, AA measured 11.2 ± 3.3 mm(2) for the equine block, 9.5 ± 2.6 mm(2) for DBBM block, 7.9 ± 4.8 mm(2) for particulated DBBM, and 2.4 ± 2.1 mm(2) for the empty control. All GBR groups rendered significantly higher values of AA in comparison with control (P ≤ 0.05). The differences in AA between GBR groups did not reach statistical significance (P > 0.05). The equine block rendered the highest values in HTaugm , although only the differences between equine block and control as well as equine block and DBBM block were statistically significant (P ≤ 0.05). With respect to HTmucosa , all GBR groups reached significantly higher values compared to control (P ≤ 0.05). The equine block revealed the most pronounced signs of graft degradation.
Guided bone regeneration lead to higher ridge dimensions and thicker covering mucosa than empty controls. The equine block with CM resulted in the most favorable outcomes regarding the maintenance of ridge contour. There were no significant differences regarding amount of new bone between GBR treatments.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
To test whether the use of (i) particulated bone substitute + collagen membrane used for guided bone regeneration (GBR) of peri-implant bone defects renders different results from (ii) particulated bone substitute + collagen membrane + fixation pins and from (iii) block bone substitute + collagen membrane with respect to the volume stability of the augmented region during suturing of mucosal flaps.
Twenty peri-implant box-shaped bone defects were created in 10 pig mandibles. Every bone defect was augmented once with each of the following GBR procedures: Granulate (particulated xenograft + collagen membrane), Granulate + Pins (particulated xenograft + collagen membrane + fixation pins), and Block (block xenograft + collagen membrane). Cone-beam computed tomography scans were obtained prior and after blinded wound closure. The horizontal thickness (HT) of the augmented region (bone substitute + membrane) was assessed at the implant shoulder (HT0 mm ) and at 1-5 mm apical to the implant shoulder (HT1 mm -HT5 mm ). The changes of HT during flap suturing were calculated as absolute (mm) and relative values (%). Repeated-measures ANOVA was used for statistical analysis.
Wound closure induced a statistically significant change of HT0 mm and of HT1 mm in all the treatment groups (P ≤ 0.05). The change in HT0 mm measured -42.8 ± 17.9% (SD) for Granulate, -22.9 ± 21.2% (SD) for Granulate + Pins, and -20.2 ± 18.9% (SD) for Block. The reduction in HT0 mm , HT1 mm , HT2 mm , and HT3 mm for the Granulate procedure was significantly higher as compared to the Granulate + Pins and the Block procedures (P ≤ 0.05). There were no statistically significant differences in the change of HT between the Granulate + Pins and the Block procedures (P > 0.05).
Wound closure induced displacement of the bone substitute resulting in a partial collapse of the collagen membrane in the coronal portion of the augmented site. The stability of the bone substitute and collagen membrane was enhanced by the application of fixation pins and by the use of block bone substitute instead of particulated bone substitute.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Objective
Sandblasting with subsequent acid etching is a potential procedure to generate microstructured surfaces on zirconia implants. The aim of the study was to systematically analyze the effect of these process steps on surface morphology and mechanical strength of the implants.Materials and methodsZirconia implant blanks (ceramic.implant, VITA) were sandblasted (105-μm alumina, 6 bar), subsequently HF-etched, and finally heat-treated at 1250°C. Surface topographies were documented by SEM. Surface roughness Ra (n = 4), monoclinic volume fraction in the surface layer (n = 1), and static fracture load (n = 4) were measured.ResultsSurface roughness Ra reached a maximum of 1.2 μm after 4× sandblasting. Scratches and sharp edges dominated the surface aspect. Fracture load increased with the number of sandblasting cycles with a gain of 30% after 20 cycles. HF etching did not change the Ra values, but sharp edges were rounded and small pits created. A minor decrease in fracture load with increasing etching time was observed. Heat treatment of 1 h reduced the fracture load by 1/3. Longer heat treatment had no further effect. The roughness Ra was not modified by heat treatment. Fracture load was strongly correlated with the monoclinic fraction except for the results obtained directly after acid etching, where a constant monoclinic fraction was observed.Conclusions
Sandblasting with 105-μm alumina followed by 1 h HF etching at room temperature and 1 h heat treatment at 1250°C is a reliable and tolerant process to create a surface roughness of about Ra = 1.2 μm on zirconia implants.
The development of bone augmentation procedures has allowed placement of dental implants into jaw bone areas lacking an amount of bone sufficient for standard implant placement. Thus, the indications for implants have broadened to include jaw regions with bone defects and those with a bone anatomy that is unfavorable for implant anchorage. Of the different techniques, the best documented and the most widely used method to augment bone in localized alveolar defects is guided bone regeneration. A large body of evidence has demonstrated the successful use of guided bone regeneration to regenerate missing bone at implant sites with insufficient bone volume and the long-term success of implants placed simultaneously with, or after, guided bone regeneration. However, the influence of guided bone regeneration on implant survival and success rates, and the long-term stability of the augmented bone, remain unknown. Many of the materials and techniques currently available for bone regeneration of alveolar ridge defects were developed many years ago. Recently, various new materials and techniques have been introduced. Many of them have, however, not been sufficiently documented in clinical studies. The aim of this review was to present the scientific basis of guided bone regeneration and the accepted clinical procedures. A classification of bone defects has been presented, aiming at simplifying the decision-making process regarding the choice of strategy for bone augmentation. Finally, an outlook into actual research and the possible future options related to bone augmentation has been provided.
Purpose:
This study aimed to compare the values of removal torque (RT) and bone-implant contact (BIC) reported in different animal studies for zirconia and titanium implants.
Materials and methods:
A systematic review of the literature was performed to analyze BIC and RT of animal studies in which both zirconia and titanium dental implants were used. To identify the studies to include in this systematic review, an exhaustive search of PubMed was performed of animal studies published in English with reports on the quantification of the osseointegration of both titanium and zirconia implants by means of BIC and/or RT. The results were aggregated and analyzed within each of the animal models (pig, rabbit, rat, monkey, dog, and sheep).
Results:
The selection process resulted in a final sample of 16 studies. In general, no significant differences were found between titanium and zirconia. The significant differences in terms of BIC and RT reported by the authors were attributable to the different surface treatments and microporosities of the implant surfaces studied, not to the materials themselves. Only two articles reported significantly lower BIC for modified zirconia implants as compared to modified titanium implants. Four authors described statistically significant differences in terms of RT between zirconia and titanium implants in the different animal models, regardless of the surface treatment received by the implants.
Conclusions:
Within the limitations of this study, the values for the BIC and RT of zirconia implants in most of the studies analyzed did not show statistical differences compared with titanium implants. Modified-surface zirconia may have potential as a candidate for a successful implant material, although further clinical studies are necessary.
The aim of this controlled clinical study was to compare a polyethylene glycol membrane (PEG) used for bone regeneration of peri-implant defects to a collagen membrane with respect to implant survival rate, dimensions of buccal peri-implant bone and mucosa.
Thirty-seven patients who received single tooth implants with simultaneous guided bone regeneration (GBR) in the posterior maxilla or mandible were enrolled in the study. Intra-operative heights of bone defects were assessed prior to bone augmentation. The defects were augmented with xenogenic bone mineral and randomly covered either with a porcine collagen membrane (control) or with a PEG membrane (test). Five years after implant placement, clinical evaluation and cone beam computed tomography (CBCT) scans were performed. Remaining height of bone defect, horizontal bone thickness, level of mucosal margin, and mucosal thickness were assessed in CBCT images. The difference of height of bone defect at implant placement and at 5-year follow-up was calculated. The differences between the two groups were analyzed using two-sided t-test and Mann-Whitney U-test.
After 5 years, 32 patients could be included and exhibited an implant survival rate of 100% for both groups. The buccal vertical bone gain between implant placement and 5-year follow-up amounted at 4.3 ± 1.5 (SD) mm and 4.8 ± 2.6 (SD) mm for the control and the test group, respectively (P = 0.493). Neither the bone height nor the thickness reached statistical significant differences between the two groups. The distance between mucosal margin and implant shoulder resulted in 0.8 ± 0.7 (SD) mm in the control and 0.5 ± 0.8 (SD) mm in the test group (P = 0.198). The mucosal thickness reached 1.4 ± 0.5 (SD) mm in the control and 1.3 ± 0.3 (SD) mm in the test group (P = 0.715). There were no significant correlations between height of bone defect at baseline and at follow-up examination and between different 5-year parameters.
A polyethylene glycol membrane used for bone regeneration of peri-implant defects performed as successfully as a collagen membrane with respect to implant survival rate and dimensions of the buccal peri-implant bone and mucosa after 5 years.
Aim:
To evaluate the clinical and radiological outcome of one-piece zirconia oral implants for three-unit fixed dental prosthesis (FDP) replacement after 1 year.
Materials:
Twenty eight patients were recruited for the investigation and signed an informed consent. All patients were treated with a one-stage implant surgery and a three-unit immediate temporary restoration on two one-piece zirconia implants. The implants were fabricated of yttria-stabilized tetragonal zirconia (y-TZP). The endosseous part of the implants was tapered with a porous surface. A total of 56 implants were inserted in the 28 patients. A total of 12 implants were placed in the upper jaws (six in the anterior area and six in the posterior area) and 44 in mandibles (all in the posterior area). At implant insertion and after 1 year, standardized radiographs were taken to evaluate the peri-implant bone loss. To evaluate any influences from different baseline parameters on the marginal bone loss a univariate analysis was performed. Clinical soft tissue parameters probing depth (PD), clinical attachment level (CAL), modified bleeding index (mBI) and modified plaque index (mPI) were recorded. Implant cumulative survival rates were calculated using actuarial life table analysis. Changes in the clinical variables were assessed using the Wilcoxon Signed Ranks test (PD, CAL) and the Sign test (mBl, mPl). All significance tests were conducted at a 5% level of significance.
Results:
After 1 year, one implant was lost resulting in a survival rate of 98.2%. The patient was excluded from further analysis. The marginal bone loss after 1 year amounted to 1.95 mm. In 40% of the patients a bone loss of at least 2 mm and in 28% of the patients a loss of more than 3 mm were observed. The PD decreased for implant and tooth sites over time, the values being significantly higher for implants than for teeth. Over 1 year, the CAL increased slightly around the implants and decreased around the teeth. At the 1-year follow-up, the CAL at the implant sites was statistically significantly higher than at the reference teeth. The mBI was significantly lower at implants than at teeth. The same result was found for the plaque index.
Conclusions:
A high frequency of increased radiographic bone loss (>2 mm) after 1 year around the presented one-piece zirconia implant system was found. The bone loss seems to be higher compared to the very limited availability of zirconia implant data. Therefore, within the limits of the present investigation, it may be concluded that the presented zirconia implant system possibly performs inferior to conventional titanium implants and to other zirconia implants regarding peri-implant bone loss.
Background: New dental implant systems are continuously introduced to the market. It is important that clinicians report their experiences with these implants when used in different situations.
Aim: The study aims to report the outcomes from a retrospective study on Neoss implants when used with or without guided bone regeneration (GBR) procedures.
Materials and Methods: The study group comprised of 50 consecutive patients previously treated with 183 Neoss implants (Neoss Ltd., Harrogate, UK) in 53 sites because of single, partial, or total tooth loss. Implants were placed in healed bone in 23 sites, while a GBR procedure was used in 30 sites in conjunction with implant placement. A healing period of 3 to 6 months was utilized in 45 sites and in 8 sites a crown/bridge was fitted within a few days for immediate/early function. The number of failures, withdrawn and dropout implants was analyzed in a life-table. All available intraoral radiographs from baseline and annual check-ups were analyzed with regard to marginal bone level and bone loss.
Results: A cumulative survival rate (CSR) of 98.2% was found for the non-GBR group and 93.5% for the GBR group with an overall CSR of 95.0% after up to 5 years of loading. In spite of the failures, all patients received and maintained their prostheses. Based on all available radiographs, the bone level was situated 1.3 ± 0.8 mm (n = 159) below the top of the collar at baseline and 1.7 ± 0.8 mm (n = 60) after 5 years of follow-up. Based on paired baseline and 1-year (n = 70) and 5-year radiographs (n = 59), the bone loss was found to be 0.4 ± 0.9 and 0.4 ± 0.9 mm, respectively. There were no statistically significant differences between GBR and non-GBR sites with regard to implant survival or bone loss.
Conclusions: The Neoss implant system showed good clinical and radiographic results after up to 5 years in function.
To investigate the clinical and radiographic outcome of a one-piece zirconia oral implant for single tooth replacement after 1 year.
A total of 65 patients received a one-stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion and after 1 year to monitor peri-implant bone loss. A univariate analysis of the influence of different baseline parameters on marginal bone loss from implant insertion to 12 months was performed. Soft tissue parameters were evaluated at prosthesis insertion and at the 1-year follow-up.
After 1 year, three implants were lost, giving a cumulative survival rate of 95.4%. The marginal bone loss after 1 year was 1.31 mm. Thirty-four per cent of the implants lost at least 2 mm bone, and 14% more than 3 mm. The univariate analysis could not depict any parameter influencing marginal bone loss. Probing depth, Clinical Attachment Level, Bleeding and Plaque Index decreased over 1 year.
The cumulative survival rate of the presented ceramic implant was comparable to the reported survival rate of titanium implants when immediately restored. However, the frequency of increased radiographic bone loss (>2 mm) after 1 year was considerably higher as compared to conventional two-piece titanium implants. The presented zirconia implant can therefore not be recommended for clinical usage.
Aim of this prospective case series was to evaluate the outcome of immediately provisionalized single-piece zirconia implants.
A total of 20 zirconia implants were inserted in single-tooth gaps in the maxilla (11) and mandible (9) of 20 patients. Implants were restored with all-ceramic CAD/CAM provisionals without occlusal contacts immediately after placement. Permanent all-ceramic restoration was performed 4 months after surgery. Plaque index (PI), bleeding on probing (BOP), Periotest® (PV), pink aesthetic score (PES), mean radiographic marginal bone levels (MBL), implant survival and success were evaluated up to 24 months.
Assessment of PI at baseline and follow-ups after 6, 12, 18 and 24 months revealed 27% (±5.3), 24% (±6), 23% (±6.1), 23% (±5.3) and 22% (±6.4), respectively. Evaluation of BOP revealed 25% (±5.6), 21% (±6), 21% (±7.2), 18% (±5.9) and 15% (±5.5), respectively. Implants presented stable at follow-ups (PV). PES improved, but not statistically significant from 8.13 (±1.5) at baseline to 10 (±2) 24 months after implantation. Measurements of MBL showed a significant bone loss of 1.01 mm within the first year after placement (P < 0.001) and 1.29 mm 24 months post-implant insertion, not reaching further statistically significant levels (P > 0.05). One implant was lost 4 months after placement, resulting in a survival and success rate of 95%.
Clinical and radiographic parameters demonstrated a 95% integration of immediately loaded zirconia single-piece implants. A long-term randomized-controlled clinical trial was initiated to confirm evidence of this protocol.
In the last decade the number of bioscience journals has increased enormously, with many filling specialised niches reflecting new disciplines and technologies. The emergence of open-access journals has revolutionised the publication process, maximising the availability of research data. Nevertheless, a wealth of evidence shows that across many areas, the reporting of biomedical research is often inadequate, leading to the view that even if the science is sound, in many cases the publications themselves are not "fit for purpose", meaning that incomplete reporting of relevant information effectively renders many publications of limited value as instruments to inform policy or clinical and scientific practice [1-21]. A recent review of clinical research showed that there is considerable cumulative waste of financial resources at all stages of the research process, including as a result of publications that are unusable due to poor reporting [22]. It is unlikely that this issue is confined to clinical research [2-14,16-20].
To compare the bone tissue response to surface-modified zirconia (ZrO2 ) and titanium implants.
Cylindrical low-pressure injection moulded zirconia (ZrO2 ) implants were produced with an acid-etched surface. Titanium implants with identical shape, sandblasted and acid-etched surface (SLA) served as controls. Eighteen adult miniature pigs received both implant types in the maxilla 6 months after extraction of the canines and incisors. The animals were euthanized after 4, 8 and 12 weeks and 16 zirconia and 18 titanium implants with the surrounding tissue were retrieved, embedded in methylmethacrylate and stained with Giemsa-Eosin. The stained sections were digitized and histomorphometrically analysed with regard to peri-implant bone density (bone volume/total volume) and bone-implant contact (BIC) ratio. Statistical analysis was performed using Mann-Whitney' U-test.
Histomorphometrical analysis showed direct osseous integration for both materials. ZrO2 implants revealed mean peri-implant bone density values of 60.4% (SD ± 9.9) at 4 weeks, 65.4% (SD ± 13.8) at 8 weeks, and 63.3% (SD ± 21.5) at 12 weeks after implantation, whereas Ti-SLA implants demonstrated mean values of 61.1% (SD ± 6.2), 63.6% (SD ± 6.8) and 68.2% (SD ± 5.8) at corresponding time intervals. Concerning the BIC ratio, the mean values for ZrO(2) ranged between 67.1% (SD ± 21.1) and 70% (SD ± 14.5) and for Ti-SLA between 64.7% (SD ± 9.4) and 83.7% (SD ± 10.3). For the two parameters investigated, no significant differences between both types of implants could be detected at any time point.
The results indicate that there was no difference in osseointegration between ZrO2 implants and Ti-SLA controls regarding peri-implant bone density and BIC ratio.
To test the hypothesis that peri-implant bone formation and mechanical stability of surface-modified zirconia and titanium implants are equivalent.
Twelve minipigs received three types of implants on either side of the mandible 8 weeks after removal of all pre-molar teeth: (i) a zirconia implant with a sandblasted surface; (ii) a zirconia implants with a sandblasted and etched surface; and (iii) a titanium implant with a sandblasted and acid-etched surface that served as a control. Removal torque and peri-implant bone regeneration were evaluated in six animals each after 4 and 13 weeks.
The titanium surface was significantly rougher than both tested zirconia surfaces. Mean bone to implant contact (BIC) did not differ significantly between the three implant types after 4 weeks but was significantly higher for titanium compared with both zirconia implants after 13 weeks (p<0.05). Bone volume density (BVD) did not differ significantly at any interval. Removal torque was significantly higher for titanium compared with both zirconia surfaces after 4 and 13 weeks (p<0.001). The sandblasted and etched zirconia surface showed a significantly higher removal torque after 4 weeks compared with sandblasted zirconia (p<0.05); this difference levelled out after 13 weeks.
It is concluded that all implants achieved osseointegration with similar degrees of BIC and BVD; however, titanium implants showed a higher resistance to removal torque, probably due to higher surface roughness.
The aim of this study was to evaluate the 5-year success rate of zirconia (ZrO2) implants with three different kinds of surfaces.
One-piece zirconia dental implants (CeraRoot) with three different roughened surfaces were designed and manufactured for this study: coated, uncoated, and acid-etched. Five different implant designs were manufactured. Standard or flapless surgical procedures were used for implant placement. Simultaneous bone augmentation or sinus elevation was performed when bone height or width was insufficient. Definitive all-ceramic restorations were placed 4 months after implant placement (8 months or more for implants when bone augmentation or sinus elevation was performed). The implants were followed up to 5 years (mean, 3.40 +/- 0.21).
In all, 831 implants were placed in 378 patients with a mean age of 48 years. The overall implant success rate after 5 years of follow-up was 95% (92.77% for uncoated implants, 93.57% for coated implants, and 97.60% for acid-etched implants). The success rate of the acid-etched surface group was significantly better than that of the other two.
From this midterm investigation, it can be concluded that zirconia dental implants with roughened surfaces might be a viable alternative for tooth replacement. Further follow-up is needed to evaluate the long-term success rates of the implant surfaces studied.
The aim of this animal study was to investigate and compare the osseointegration of zirconia and titanium dental implants. 14 one-piece zirconia implants and 7 titanium implants were inserted into the mandibles of 7 minipigs. The zirconia implants were alternately placed submerged and non-submerged. To enable submerged healing, the supraosseous part was removed, using a diamond saw. The titanium implants were all placed submerged. After a healing period of 4 weeks, a histological analysis of the soft and hard tissue and a histomorphometric analysis of the bone-implant contact (BIC) and relative peri-implant bone-volume density (rBVD; relation to bone-volume density of the host bone) was performed. Two zirconia implants were found to be loose. All other implants were available for evaluation. For submerged zirconia and titanium implants, the implant surface showed an intimate connection to the neighbouring bone, with both types achieving a BIC of 53%. For the non-submerged zirconia implants, some crestal epithelial downgrowth could be detected, with a resultant BIC of 48%. Highest rBVD values were found for submerged zirconia (80%), followed by titanium (74%) and non-submerged zirconia (63%). The results suggest that unloaded zirconia and titanium implants osseointegrate comparably, within the healing period studied.
Objective: The aim of this study was to evaluate osseointegration of one-piece zirconia vs. titanium implants depending on their insertion depth by histomorphometry.
Material and methods: Four one-piece implants of identical geometry were inserted on each side of six mongrel dogs: (1) an uncoated zirconia implant, (2) a zirconia implant coated with a calcium-liberating titanium oxide coating, (3) a titanium implant and (4) an experimental implant made of a synthetic material (polyetheretherketone). In a split-mouth manner they were inserted in submerged and non-submerged gingival healing modes. After 4 months, dissected blocks were stained with toluidine blue in order to histologically assess the bone-to-implant contact (BIC) rates and the bone levels (BL) of the implants.
Results: All 48 implants were osseointegrated clinically and histologically. Histomorphometrically, BL in the crestal implant part did not differ significantly with regard to material type or healing modality. The submerged coated zirconia implants tended to offer the most stable crestal BL. The histometric results reflected the different healing modes by establishing different BL. The median BIC of the apical implant part of the zirconia and titanium group amounted to 59.2% for uncoated zirconia, 58.3% for coated zirconia, 26.8% for the synthetic material and 41.2% for titanium implants.
Conclusions: Within the limits of this animal study, it is concluded that zirconia implants are capable of establishing close BIC rates similar to what is known from the osseointegration behaviour of titanium implants with the same surface modification and roughness.
Alumina toughening enhances the mechanical properties of zirconia ceramics but the biocompatibility of this material has rarely been addressed. In this study, we examined the osteoblast response to alumina-toughened zirconia (ATZ) with different surface topographies.
Human osteoblasts isolated from maxillary biopsies of four patients were cultured and seeded onto disks of the following substrates: ATZ with a machined surface, airborne-particle abraded ATZ, airborne-particle abraded and acid etched ATZ. Airborne-particle abraded and acid etched titanium (SLA) and polystyrene disks served as a reference control. The surface topography of the various substrates was characterized by profilometry (R(a), R(p-v)) and scanning electron microscopy (SEM). Cell proliferation, cell-covered surface area, alkaline phophatase (ALP) and osteocalcin production were determined. The cell morphology was analyzed on SEM images.
The surface roughness of ATZ was increased by airborne-particle abrasion, but with the R(a) and R(p-v) values showing significantly lower values compared with SLA titanium (Mann-Whitney U-test P<0.05). The proliferation assay revealed no statistically significant differences between the ATZ substrates, SLA titanium and polystyrene (Kruskal-Wallis test, P>0.05). All substrates were densely covered by osteoblasts. ALP and osteocalcin production was similar on the examined surfaces. Cell morphology analysis revealed flat-spread osteoblasts with cellular extensions on all substrates.
These results indicate that ATZ may be a viable substrate for the growth and differentiation of human osteoblasts. Surface modification of ATZ by airborne-particle abrasion alone or in combination with acid etching seems not to interfere with the growth and differentiation of the osteoblasts.
To analyze the clinical outcomes of endosseous implants following guided bone regeneration (GBR) procedures to correct dehiscence/fenestration defects associated with implant placement. METHODS/SEARCH STRATEGY: A Medline search was performed for human studies published in English focusing on GBR procedures for the correction of dehiscence/fenestration defects associated with the placement of screw-shaped titanium implants. The selected studies had to include at least 10 consecutively treated patients with a minimum follow-up of 12 months after the start of prosthetic loading. The clinical outcomes in terms of the complication rate of the GBR procedure, implant survival, and stability of marginal soft tissues around implants were evaluated.
Seven publications were included in this review. A total of 238 patients received 374 implants. Defects were treated with resorbable or non-resorbable membranes, in association with or without graft materials. Patients were followed for 1-10 years after the start of prosthetic loading. In the postoperative period, 20% of the non-resorbable membranes and 5% of the resorbable ones underwent exposure/infection. However, in the majority of cases, a complete or an almost complete coverage of the initial defect was obtained. The overall survival rate of implants, irrespective of the type of membrane and grafting materials, was 95.7% (range: 84.7-100%). No significant modifications of probing depth and/or variation of clinical attachment level around implants were observed during the follow-up period.
Despite the favorable results obtained, it was difficult to draw a significant conclusion as far as the more reliable grafting material and membrane barrier for the correction of dehiscence/fenestration defects are concerned, due to the limited sample of patients and the wide variety of grafting materials and membranes, used alone or in combination. Moreover, due to the lack of randomized clinical trials, it was impossible to demonstrate that such augmentation procedures are actually needed to allow the long-term survival of implants.
The purpose of the present study was to histologically compare the bone tissue responses to surface-modified zirconia and titanium implants.
Threaded zirconia implants were produced using a new low-pressure injection moulding technique and thereafter surface treated by acid etching. Titanium implants with the exact shape and surface treated by sandblasting and acid etching (SLA) served as controls. Fifteen adult pigs received both implant types in the maxilla 6 months after extraction of the second and third incisors. The animals were sacrificed after 4, 8 and 12 weeks and 30 implants with surrounding bone were retrieved.
Histological evaluation showed osseous integration for both materials. Zirconia implants revealed mean peri-implant bone density values of 42.3% (SD +/- 14.5) at 4 weeks, 52.6% (SD +/- 5.7) at 8 weeks and 54.6% (SD +/- 11.5) at 12 weeks after implantation, whereas Ti-SLA implants demonstrated mean values of 29% (SD +/- 10), 44.1% (SD +/- 18) and 51.6% (SD +/- 8.6) at corresponding time intervals. With respect to the bone-implant contact ratio, the mean values for zirconia ranged between 27.1% (SD +/- 3.5) and 51.1% (SD +/- 12.4) and for Ti-SLA, it ranged between 23.5% (SD +/- 7.5) and 58.5% (SD +/- 11.4). For the parameters investigated, no statistically significant differences between both types of implants could be detected at any time point.
No statistical difference between implants could be demonstrated with any of the methods used. The limited number of animals per group, however, does not allow to conclude that there is no difference in osseointegration between the two types of implants, although the data tend to suggest such a trend.
The aim of this study was to test whether or not implants associated with bone regeneration show the same survival and success rates as implants placed in native bone in patients requiring both forms of therapy.
Thirty-four patients (median age of 60.3 years, range 18-77.7 years) had been treated 5 years before the follow-up examination. Machined screw-type implants were inserted following one of two surgical procedures: (1) simultaneously with a guided bone regeneration (GBR) procedure, which involved grafting with xenogenic bone substitute material, autogenous bone or a mixture of the two and defect covering with a bio-absorbable collagen membrane (test) and (2) standard implantation procedure without bone regeneration (control). For data recording, one test and one control implant from each patient were assessed. Examination included measurements of plaque control record (PCR), probing pocket depth (PPD), bleeding on probing (BOP), width of keratinized mucosa (KM), frequency of situations with supra-mucosal location of the crown margin, implant survival assessment and radiographic examination. Radiographs were digitized to assess the marginal bone level (MBL). Differences between groups were tested using the one-sample t-test. The estimation of survival rate was based on Kaplan-Meier analysis.
The follow-up period of the 34 GBR and 34 control implants ranged from 49 to 70 months (median time 57 months). Cumulative survival rates reached 100% for the GBR group and 94.1% for the control group without statistical significance. No statistically significant differences for clinical and radiographic parameters were found between the two groups regarding PCR, BOP, PPD, KM and MBL.
The present study showed that, clinically, implants placed with concomitant bone regeneration did not performed differently from implants placed into native bone with respect to implant survival, marginal bone height and peri-implant soft tissue parameters.
Tissue reaction and stability of partially stabilized zirconia ceramic in vivo was evaluated with the use of the subcutaneous implantation test. During the experimental period, zirconia ceramic was completely encapsulated by a thin fibrous connective tissue with less than 80 μm thickness. No changes of weight and 3-point bending strength were detected after 12 months of implantation. The result suggests that zirconia ceramic is biocompatible and no degradation of zirconia ceramic occurred. © 1992 The Editorial Council of The Journal of Prosthetic Dentistry.
A new sawing-grinding method is described for the histological evaluation of jaw bones with teeth or bones containing implants (ceramic or metallic). The undecalcified bone is embedded in acrylic resin and sawed at 100 to 150 micrometers. The slices are ground automatically by a special machine to a thickness of 5-10 micrometers. The usually employed staining procedures for hard plastic embedded-tissues may be used. Plaque, fillings, crowns, bridges, implants and soft tissues are preserved in situ. Macroscopic and microscopic detail of good quality is preserved for histological and morphometrical evaluation.
Membranes, clinically used to improve bone regeneration according to the osteopromotion principle, have primarily been made of expanded polytetrafluoroethylene (Gore-Tex Membrane). Recently, different types of biodegradable membranes have become available. This investigation explored the osteopromotive potential of 10 different biodegradable and non-biodegradable membrane materials. Scanning electron microscopy revealed quite different surface configurations of these membranes, even though some of them were chemically closely related. Standardized, transosseous, critical size mandibular defects were made bilaterally in adult rats and were randomly covered with the different types of membrane. After 6 wk of healing, evaluation was performed by light microscopy according to a histological scoring system. Varying degrees of bone healing were seen beneath the different membranes. Some of the membranes (such as Gore-Tex Augmentation Material, Millipore and Resolut 'long term') revealed a good osteopromotive effect, whereas others had little or no beneficial effects on bone healing. Certain membrane materials caused a pronounced inflammatory response in the surrounding soft tissue, while others displayed a low inflammatory reaction. The study shows that different membranes differ strongly in osteopromotive efficacy, even if seemingly chemically closely related. Furthermore, the study demonstrates that membranes developed primarily for periodontal regeneration purposes may not be adequate to promote bone healing.
Due to their excellent mechanical properties, Yttria-stabilized Tetragonal Zirconia Polycrystal ceramics (Y-TZP) are used in ball heads for Total Hip Replacements. It is known that Y-TZP materials may show strength degradation due to ageing or to hydrothermal treatment. Also high wear of UHMWPE sockets coupled to steam sterilized Y-TZP ball heads after a short implantation period was recently reported. This effect may be related to ball head surface phase transformation, due to corrosive attack. The aim of this study is the evaluation of Y-TZP ceramics stability. Y-TZP made out of Yttria coated powders were aged at 140 degrees C under 0.2 MPa water pressure, in Ringer's solution at 37 degrees C, in NZW rabbits. Samples made out Yttria coated powders show lower strength degradation than samples made out coprecipitated powders, and UHMWPE discs coupled to Y-TZP rings made out coated powders do not show increase in wear after repeated sterilization cycles of the ceramic rings.
The aim of this prospective 5-year longitudinal study was to follow endosteal implants in which guided bone regeneration (GBR) was applied during implant placement. In 75 patients, defects around implants (Branemark System) were treated with Bio-Oss and Bio-Gide (112 implants). In split-mouth patients in this group, Bio-Oss and Gore-Tex were used in the second defect site (41 implants). All 75 patients had at least 1 implant that was entirely surrounded by bone and served as the control (112 implants). After placement of the definitive prostheses (single-tooth, fixed, or removable implant prostheses), patients were recalled after 6 months and then every 12 months during a 5-year observation period. The following variables were investigated: implant survival, marginal bone level (MBL), presence of plaque, peri-implant mucosal conditions, height of keratinized mucosa (KM), and marginal soft tissue level (MSTL). The cumulative implant survival rate after 5 years varied between 93% and 97% for implants treated with or without GBR. The mean MBL after 60 months was 1.83 mm for sites treated with Bio-Oss and Bio-Gide, 2.21 mm for sites treated with Bio-Oss and Gore-Tex, and 1.73 mm for the control sites. The MBL values were found to increase significantly with time and differed significantly among the treatment groups. During the observation period, KM varied between 3.16 and 3.02 mm. A slight recession of 0.1 mm was observed, and plaque was found in 15% of all sites and was associated with inflammatory symptoms of the peri-implant mucosa. It was observed that such symptoms and recession correlated more strongly with the type of restoration than with the type of treatment. This study demonstrated that implants placed with or without GBR techniques had similar survival rates after 5 years, but that bone resorption was more pronounced in sites with GBR treatment. It was assumed that the use of GBR is indeed indicated when the initial defect size is larger than 2 mm in the vertical dimension.
Background: Zirconia might be an alternative material to titanium for dental implant fabrication. The aim of the present study was to investigate the histological behavior (osseointegration) of loaded zirconia implants in an animal model and to compare it with the behavior of titanium implants.
Methods: Five months after extraction of the upper anterior teeth, 12 custom-made titanium implants (control group) and 12 custom-made zirconia implants (test group) were inserted in the extraction sites in six monkeys. Before insertion, the titanium implant surfaces were sandblasted with Al2O3 and subsequently acid-etched. The zirconia implants were only sandblasted. Six months following implant insertion, impressions were taken for the fabrication of single crowns. A further 3 months later, nonprecious metal crowns were inserted. Five months after insertion of the crowns, the implants with the surrounding hard and soft tissues were harvested, histologically prepared, and evaluated under the light microscope regarding the peri-implant soft tissue dimensions and mineralized bone-to-implant contact.
Results: No implant was lost during the investigational period. The mean height of the soft peri-implant tissue cuff was 5 mm around the titanium implants and 4.5 mm around the zirconia implants. No statistically significant differences were found in the extent of the different soft tissue compartments. The mean mineralized bone-to-implant contact after 9 months of healing and 5 months of loading amounted to 72.9% (SD: 14%) for the titanium implants and to 67.4% (SD: 17%) for the zirconia implants. There was no statistically significant difference between the different implant materials.
Conclusion: Within the limits of this animal experiment, it can be concluded that the custom-made zirconia implants osseointegrated to the same extent as custom-made titanium control implants and show the same peri-implant soft tissue dimensions.
Few investigations on guided bone regeneration (GBR) focus on the behaviour of tissues adjacent to barrier membranes. This study was conducted to (1) evaluate the barrier function potential of different resorbable and nonresorbable membranes for GBR, (2) investigate their structural changes after different intervals, and (3) characterize tissue composition and reaction adjacent to the barrier by qualitative histologic evaluation. Seven barriers for GBR were used per animal (made of dense or expanded polytetrafluoroethylene (d/ePTFE), titanium, polyetherurethane, collagen and two polylactide-polyglycolide-/-trimethylenecarbonate-co-polymers (PLPG, LPGTC) in standardized defects not exceeding the critical size) without using bone substitution material or autogenous bone at the right inferior margin of the mandibles of six domestic pigs. Samples of the defect areas with membranes were harvested after 2 days (one animal), 4 and 8 (two animals, each) and 12 weeks (one animal), respectively. The healing of bone defects was completed in all animals after 12 weeks. Nonresorbable barriers prevented the soft tissue in-growth into standardized defects. Thinner layers of fibrous tissue were seen underneath the dense and rigid barriers (dPTFE, titanium) when compared with collagen and PLPG/LPGTC, in which soft-tissue plugs occupied the crestal defect portion. PLPG-/LPGTC-barriers underwent structural changes after 4 weeks and revealed blistered central layers, whereas structural changes were not evident in nonresorbable barriers. The degradation of PLPG-/LPGTC-membranes was present with in-growth of fibres, vessels, and cells. Using collagen or synthetic polymer barriers for GBR, the application of bone or bone substitutes to prevent membrane prolapse into the defect is suggested.
The aim of the present study was to immunohistochemically evaluate lateral ridge augmentation using a particulated (BOG) or block (BOB) natural bone mineral biocoated with rhGDF-5 and rhBMP-2 in dogs.
Three standardized box-shaped defects were surgically created at the buccal aspect of the alveolar ridge in each quadrant of eight beagle dogs. After 2 months of healing, the chronic-type defects were randomly allocated in a split-mouth design to either (i) BOG or (ii) BOB biocoated with (a) rhGDF-5 or (b) rhBMP-2, respectively. Uncoated grafts served as controls. After 3 and 8 weeks, dissected blocks were prepared for immunohistochemical [osteocalcin (OC)] and histomorphometrical analysis [e.g. area (mm(2)) of new bone fill (BF), newly formed mineralized (MT) and non-mineralized tissue (NMT)].
rhBMP-2 biocoated BOG revealed significantly highest BF and MT values at 3 (upper and lower jaws - UJ/LJ - compared with BOG) and 8 weeks (UJ - compared with rhGDF-5). Biocoating of BOB using both rhGDF-5 and rhBMP-2 resulted in significantly increased MT values at 8 weeks (UJ/LJ - compared with BOB). In all groups, NMT adjacent to BOG and BOB scaffolds revealed pronounced signs of an OC antigen reactivity.
Within the limits of the present study, it was concluded that both rhGDF-5 and rhBMP-2 have shown efficacy; however, their bone regenerative effect was markedly influenced by the carrier.
Currently, zirconia is widely used in biomedical area as a material for prosthetic devices because of its good mechanical and chemical properties. Largely employed in clinical area for total hip replacement, zirconia ceramics (ZrO(2)) are becoming a prevalent biomaterial in dentistry and dental implantology. Although titanium is used in dental implantology currently, there is a trend to develop new ceramic-based implants as an alternative to monolithic titanium. This article reviews the evolution and development of zirconia through data published between 1963 and January 2008 in English language. Articles were identified via a MEDLINE search using the following keywords: zirconia, zirconia/biocompatibility, zirconia/osseointegration, zirconia/periointegration, zirconia/review, and zirconia/bacterial adhesion or colonization. This review of the literature aims at highlighting and discussing zirconia properties in biological systems for their future use in dental implantology. In conclusion, zirconia with its interesting microstructural properties has been confirmed to be a material of choice for the "new generation" of implants, thanks to its biocompatibility, osseoconductivity, tendency to reduce plaque accumulation, and interaction with soft tissues, which leads to periointegration. However, scientific studies are promptly needed to fulfill gaps like long-term clinical evaluations of "all zirconia implants," currently leading to propose an alternative use of "hybrid systems" (i.e., titanium screw with zirconia collar) and also bacterial colonization of zirconia. Moreover, there is a permanent need for consistent information about topography and chemistry of zirconia allowing easier cross-product comparisons of clinical devices.
Proceedings of the 1st European Workshop on Periodontology
- T. Albrektsson
- F Isidor
Tissue compatibility and stability of a new zirconia ceramic in vivo
- Y. Ichikawa
- Y. Akagawa
- H. Nikai
- H. Tsuru
Consensus report of session iv
- T Albrektsson
- F Isidor
Albrektsson, T. & Isidor, F. (1993) Consensus report
of session iv. Lang, N.P., & Karring, T., eds. Proceedings of the 1st European Workshop on Periodontology, London: Quintessence. 365-369.