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Strength and biocompatibility of polymethacrylate-silica composite dental implant materials.

A study was made of the strength properties of several composite dental implant materials composed of silica microspheres (6%, 24%, and 48% by weight) and PMMA. Prepared specimens of the materials were tested for compressive strength and tensile strength as a function of the curing methods. Compressive strength was reduced only slightly when the 6% mixture was used, as compared to 100% PMMA, but the compressive strengths of the 12% and 24% mixtures were reduced by approximately 30% when compared to 100% PMMA. The compressive strengths of these materials were reduced even further after curing in a microwave oven, and the tensile strengths decreased to a greater degree. The 6% mixture was reduced by 38% in the heat-cured specimens and was reduced by 27% in the microwave-cured specimens. Tooth replica implants were placed in baboons and the peri-implant tissues were studied histologically after 6 months. Inflammation was minimal. Peri-implant alveolar bone was viable and active, and both connective tissue and epithelial attachment to the implant surface was evident.

Alveolar Process↗

The interface between retained roots and dental implants: a histologic study in baboons.

BACKGROUND: This study is a derivative of another study evaluating implant efficacy in baboons. In the previous study it was noted that some implants were placed near or into retained root tips. The purpose of this study was to evaluate the effect of the inadvertent placement of root form implants into or near retained root fragments. METHODS: The baboon has severe dilacerations at the apices of the roots, making extraction very difficult; 120 teeth were extracted from 10 baboons. After the sites had healed, root form implants were placed in each of the sites. Sites were either loaded at various time intervals or left unloaded. Block sections were removed and processed for histologic examination. RESULTS: When the specimens were analyzed, it was noted that several implants were placed through retained root fragments, while others were placed through the periodontal ligament of other root fragments. In a few cases, implants were close to, but not in contact with, either the root or the periodontal ligament. These implants functioned as well as the others in the study. Histologically, there was no inflammation at any site. In some sections, the roots were in intimate contact with the implants, while in others, there was a gap between the two. Where the implant was in contact with the periodontal ligament, there was no apparent fibrous encapsulization of the implant. In some areas, it appeared that a calcified material was deposited on the implants. It was not possible to determine whether this material was bone or cementum. CONCLUSION: Unintentional placement of dental implants into retained root fragments did not result in any inflammation and may have produced cementum or cementum-like matrix on the titanium surface adjacent to the periodontal ligament of the retained root tip.

Animals↗

Persistent idiopathic facial pain following dental implant placement: a case report.

The present case report depicts the management of a patient with persistent idiopathic facial pain following the placement of 2 dental implants in the mandibular anterior alveolar ridge. After 15 months of unsuccessful diagnosis and management, the patient was seen at the Orofacial Pain Unit of the Oral Surgery and Implantology master's degree program of the University of Barcelona. Seven months after treatment onset, a combination of nortriptyline, clonazepam, and relaxation procedures has successfully controlled the patient's facial pain symptoms.

Analgesics↗

Enhanced wear resistance of ball-and-socket joints of dental implants by means of titanium gaseous nitriding.

The aim of this research is the surface hardening of the ball-and-socket joint of dental implants by means of heat treatments in order to obtain titanium nitrides. These nitrides minimize the wear of the titanium used in prosthesis. In this paper the optimum heat treatment, the hardness and the wear resistance are described in relation to the ball-and-socket joint without heat treatment.

Dental Implants↗

Transmission electron and high-voltage electron microscopy of osteocyte cellular processes extending to the dental implant surface.

Examination of the morphology of osteocytes within the bone supporting endosteal dental implants was performed using conventional transmission and high-voltage transmission electron microscopy (HVEM). The in vivo dog model used 72 implants inserted into the premolar region of 18 experimental animals. Forty-eight implants in 12 dogs were used as anterior abutments for fixed bridges for periods up to 12 months. The mineralized matrix of the supporting bone was either directly apposed to the implant surface or was separated from the implant by a narrow region of unmineralized matrix. Osteocytes were routinely observed to be closely associated with the bone-implant interface, as well as at a distance from the implant. Osteocytes were found to extend cellular processes directly to the implant surface through canaliculi. The osteocyte processes contained microfilaments. The three-dimensional capabilities of HVEM elucidated the nature of these cell processes at the point of exit from the osteocyte, as the processes extended through the mineralized matrix, and as the processes terminated at the implant interface. This report suggests that avenues of communication may exist between the implant and the osseous cells, providing intriguing hypotheses regarding biomechanical forces and osteogenesis at the implant interface. Furthermore, an electron-dense deposit was observed upon the inner confines of the canalicular wall, upon the outer aspects of the osteocyte lacuna, and upon the outer aspect of the bone interfacing the implant.

Animals↗

The effect of systemic flurbiprofen on bone supporting dental implants.

This article describes a study of the efficacy of the non-steroidal anti-inflammatory drug flurbiprofen in maintaining alveolar bone around mandibular root-form dental implants. The preliminary results indicate that, in appropriate doses, flurbiprofen may spare bone around such implants.

Adolescent↗

Dental implants in reconstructed jaws: patients' evaluation of functional and quality-of-life outcomes.

PURPOSE: To evaluate the quality-of-life aspect of treatment outcome following functional jaw reconstruction and dental implants in the maxilla or mandible. MATERIALS AND METHODS: This cross-sectional study used a questionnaire interview of 28 rehabilitated patients who received autogenous bone grafts from the ilium and endosseous implants (14 maxillary and 14 mandibular cases; 134 implants) for functional jaw reconstruction between 1988 and 1999. A questionnaire was developed to assess the quality-of-life outcome for those patients who had finished their rehabilitation at least 6 months prior to the interview. Responses to the questions were recorded by means of visual analog scales. RESULTS: In general, patients gave positive comments on the restoration of their orofacial appearance and function (mastication and speech). The majority (85.7%) found no problem in various daily social activities, including dining in public. DISCUSSION: The overall level of satisfaction with the treatment outcome and the degree of recommendation of the treatment to others were both favorable (mean scores 8.6 and 8.7 out of 10, respectively). CONCLUSION: Oral rehabilitation using functional jaw reconstruction can reach a satisfactory level of esthetics, function, and psychosocial well being of patients, thus improving their quality of life.

Activities of Daily Living↗

Biological fabrication of nacreous coating on titanium dental implant.

Titanium screws with 3.5mm diameter and 8mm length, as well as titanium flat sheets with size 4 mm x 8 mm x 0.3mm, were implanted into the epithelial mantle pearl sacs of a fresh water bivalve (Hyriopsis cumingii Lea) by replacing the pearls. After 45 days of cultivation, the implant surfaces were deposited with a nacre coating with iridescent luster. The coating could conform to some extent the thread topography of the screw implant and was about 200-600 microm in thickness. The coating was composed of a laminated nacreous layer and a transitional non-laminated layer that consisted mainly of vaterite and calcite polymorphs of calcium carbonate. The transitional layer was around 2-10 microm thick in the convex and flat region of the implant surface and could form close contact with titanium surface; while the transitional layer was much thicker in the steep concave regions and could not form close contact with the titanium surface. The reasons for inhomogeneity in thickness and the variation in interface character were discussed and the improvement to the design of the dental implant with respect to this coating method was suggested in the paper. The results suggest that it is possible to fabricate a biologically active and degradable, and mechanically tough and strong nacre coating on titanium dental implant by this novel coating technology.

Animals↗

Analysis of titanium dental implants after failure of osseointegration: combined histological, electron microscopy, and X-ray photoelectron spectroscopy approach.

A multitechnique approach has been used to characterize the surface of nonosseointegrated titanium implants and the surrounding biological tissues. Five pure titanium dental implants were used as reference, and 25 removed implants were studied. Surface and in-depth chemical compositions of the implants (from a total of 16 patients) were investigated by X-ray photoelectron spectroscopy (XPS). Histological slides of the surrounding tissues were examined by light microscopy, XPS, and electron microprobe analysis. None of the failed implants presented the regular surface composition and depth profile of the TiO2 overlayer; foreign elements (Ca, Na, P, Si, Cl, Zn, Pb, and Al) were observed on some implants. Fibrosis, lymphocytic and plasmocytic infiltrates, and granulomatous lesions were detected in the surrounding tissues. XPS and electron microprobe analysis indicated the presence of Zn, Fe, Sn, and Ti in the tissues. As a possible scenario for implant failure, we propose and discuss a oxidoreduction mechanism, leading to a partial dissolution or the complete dissociation of the protective titanium dioxide overlayer and to ion diffusion through the surrounding tissues.

Connective Tissue↗

Bone regeneration and tissue acceptance of human fascia lata grafts adjacent to dental implants: a preliminary case report.

The biologic principle of guided tissue regeneration (GTR) has been studied extensively in hopes of regenerating alveolar bone. Various materials have been utilized as regenerative membranes; however, all materials have disadvantages, and the ideal membrane material is yet to be identified. In this case report, human freeze-dried fascia lata strips were used as a regenerative barrier membrane in conjunction with the placement of endosseous root implants and demineralized, freeze-dried bone allograft. The major advantage in the use of human fascia lata for guided tissue regeneration is that a second procedure to remove the material is not necessary, and the fascia is accepted by the surrounding tissues without complication. There is acceptance of four endosseous root-form dental implants that were immediately placed into fresh extraction sockets and covered with demineralized freeze-dried bone allograft (DFDBA), with human freeze-dried fascia lata used to serve as a biocompatible, collagenous, regenerative augmentation membrane over the dental implants. The biologic concept of GTR is clinically applied to increase the dimensions of the edentulous, maxillary alveolar ridge with use of human freeze-dried fascia lata barrier membranes.

Adolescent↗

Application of the finite element method in dental implant research.

This article provides a review of the achievements and advancements in dental technology brought about by computer-aided design and the all powerful finite element method (FEM) of analysis. The scope of the review covers dental implants, jawbone surrounding the implant and the biomechanical implant and jawbone interaction. Prevailing assumptions made in the published finite element analysis (FEA) and their limitations are discussed in some detail which helps identify the gaps in research as well as future research direction.

Biocompatible Materials↗

Fatal sequel to dental implant surgery.

The rare complication of fatal venous air embolism arising as a direct result of dental implant surgery in the mandible is depicted. The deaths arose from the erroneous use of an air/water coolant mixture with internally irrigated implant drills. The pathogenesis and consequence of air embolism is discussed. Practitioners are warned about the dangers of using air-driven equipment during implant surgery.

Air Pressure↗

Light microscopic and scanning electron microscopic analyses of dental implants retrieved from humans.

This paper reports analyses obtained from 51 implant cases retrieved from humans and submitted to the AAIDRF-MCG Implant Retrieval Center. The undecalcified samples were embedded in PMMA and examined with scanning electron microscopy and with routine light or Nomarski microscopy. Cases included individual implants as well as 2 mandibles obtained at autopsy. Retrieved implants were sometimes shown to be encapsulated with connective tissue (CT), whereas other implants were apposed by bone, with only minimal CT association. In the latter cases, the implants were apposed by substantial amounts of viable bone. Nomarski microscopy disclosed the orientation and close apposition of the collagen bundles comprising the interfacial bone. In these cases where close bone apposition was observed to the implants, implant fracture was often the cause of failure. Periodontal lesions were reported around some implants showing a marked degree of inflammatory cell infiltrate (ICI). This study underscores the need for evaluation of failed human dental implants. Failure of implants placed longer than 10 years ago (perhaps loaded immediately) may be due to loss of bone support, CT encapsulation, and ICI (i.e., biological failure). Failure of more recently placed implants could also be due to this scenario, but failure was more often ascribed to biomaterial failure.

Alveolar Process↗

Fabrication and characterization of porous-rooted polymethylmethacrylate (PMMA) dental implants.

A comparative-agglomeration fabrication technique has been developed to produce polymethylmethacrylate dental implants having a porous coating on the root portion. This process allows control of pore structure enabling ingrowth of either bone or fibrous tissue. The relationships between mechanical properties and pore microstructure have been determined for materials produced by this process. The mechanical properties of the porous coating can be estimated from these relationships.

Dental Implantation↗

The surface analysis of implant materials. 1. The surface composition of a titanium dental implant material.

The surfaces of titanium (Ti) plates, as models for Ti implants, have been characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF SIMS). Plates were prepared with rough and smooth surface topographies--the rough being similar to that of an implant. The XPS data has been used to construct a model of the plates' surface chemical structure, from the gas-solid interface through to pure Ti metal. At the surface of as-received plates, which underwent the same preparative procedure as an implant, considerable surface contamination was detected. In particular, high levels of carbon (C) contaminants were detected; the nature of this C was elucidated by fitting the C 1s core line and from the secondary ion mass spectra. The oxygen (O) 1s core line could not be fitted using a minimum of 2 gaussian peaks, demonstrating the multiplicity of O environments. The detection of other elements in the XPS analysis further demonstrated that, in nominally pure Ti plates, the surface chemical composition deviates considerably from that of the bulk. The data obtained from the plates were confirmed by examination of a Ti abutment. The handling of Ti plates with stainless steel tweezers was investigated. No obvious change in surface chemistry was detected. All the above results bring into serious questions the validity of rigorous protocols demanded, in some techniques, in the handling and use of Ti implants.

Dental Implants↗