The dark side of dioxygen biochemistry

The aim of this study was to evaluate the clinical function and long-term prognosis of overdentures retained by a small number of implants in the maxilla and mandible using one of two different attachment systems. Included in the study were all patients referred to specialty clinics in J?nk?ping and Link?ping, Sweden, during the treatment period who needed an overdenture and could be provided with a minimum number of two bilaterally-placed implants. Excluded were patients with bone-grafted jaws, irradiated cancer patients, heavy bruxers, and patients who had lost a fixed prosthesis because of implant losses. The patients were randomly assigned to receive one retentive system, either a round 2-mm-diameter bar with clips or ball attachments (Nobel Biocare). Eighteen overdentures were placed in maxillae and 32 in mandibles, supported by a total of 115 Br?nemark implants. Of the implants placed, 86.1% were continuously osseointegrated. The cumulative implant survival rates after 7 years of loading were 75.4% in the maxillae and 100% in the mandibles. There was no difference in implant survival rate between the attachment systems. Patients with implant losses were characterized by severely resorbed maxillary ridges and inferior bone quality, together with unfavorable loading circumstances such as short implants combined with long leverages. Complications and prosthetic adjustments were mostly resolved early and easily.     

An update on the clinical documentation on currently used bone anchored endosseous oral implants

In order to achieve safe and predictable results with oral implant therapy, the clinician has to rely on the scientific documentation when choosing a particular implant system. This review condenses the relevant clinical documentation on currently used endosseous oral implant systems and may help in the process of choosing an implant system.     

In vitro attachment of human gingival fibroblasts to endosseous implant materials

In recent years, the focus of dental implant research has been the nature of the bone-implant interface associated with osseointegration, yet the transgingival portion of endosseous dental implants has received little attention. The purpose of this study was to determine the attachment of human gingival fibroblasts to three different implant materials: commercially pure titanium, non-porous hydroxyapatite, and porous hydroxyapatite. Cell attachment was quantified by radiolabeling gingival fibroblasts with tritiated thymidine and counting attached cells by liquid scintillation following incubation for periods of 20, 40, and 60 minutes. Additional studies coating implant surfaces with fibronectin were also performed. The nature of the implant material itself appeared to affect the number of attached cells. Determined on a surface area basis, fibroblast attachment was greatest to titanium followed by non-porous hydroxyapatite. Porous hydroxyapatite demonstrated the least amount of fibroblast attachment. When incubated with fibronectin at a concentration of 50 micrograms/ml, no increase in the number of cells attached to the various implant materials was observed. A small but statistically significant increase in the number of fibroblasts attached to porous hydroxyapatite at 40 minutes was observed when implant materials were pre-treated with fibronectin.     

The use of transitional implants for immediate fixed temporary prostheses in cases of implant restorations

While the original Br?nemark implant protocol has continued to evolve, the avoidance of implant loading during osseointegration remains a prerequisite with all implant systems. Immediately loaded transitional implants have recently been developed to support the fabrication of a fixed provisional prosthesis that provides implant patients with improved aesthetics and function during the osseointegration period. In this manner, osseointegration can occur free from prosthetic and transmucosal loads. This article describes the use of transitional implants and presents a classification of three different case types.     

Wortmannin sensitizes mammalian cells to radiation by inhibiting the DNA-dependent protein kinase-mediated rejoining of double-strand breaks

STATEMENT OF PROBLEM: The cone-screw abutment has been shown to diminish micromovement by reducing the burden of component loosening and fracture. However, anecdotal concern for cold welding of cone-screw joints in implant design has been identified as a potential source for lack of retrievability. PURPOSE: This comparative study evaluated the loosening torque, as a percentage of tightening torque, for the ITI Straumann and Astra Tech (3.5 and 4.0 mm diameters) implant systems, which use an 8-degree and 11-degree internal cone, respectively. MATERIAL AND METHODS: Implants and abutments from each system were mounted in a torque device, and a range of tightening torques was applied. Loosening torques were then measured, and the influence of conus angle, interfacial surface area, saliva contamination, and time delay to loosening were all assessed. RESULTS: The loosening torque only exceeded tightening torque at the highest levels, just before component failure, when plastic deformation was expected. For all clinically relevant levels of torque, both in a dry environment and with components bathed in artificial saliva at 37 degrees C, loosening torque was always seen to be 80% to 90% of tightening torque, demonstrating that cold welding does not occur. There was a high correlation between loosening and tightening torque for all systems tested, but no statistical difference when comparing wet versus dry or comparing individual data for each system. CONCLUSIONS: It can be concluded that for clinically relevant levels of tightening torque, no problems are anticipated with respect to retrievability.     

Presence of a fatty acid-binding protein in the armadillo Harderian gland

Clinical measurements on gingival indices and morphologic observations were performed in this study to verify the defending mechanism of gingival soft tissue against foreign invasions from the perspective of epithelial adhesion/attachment to implant surfaces in the monkey mandible. The following zones were observed using scanning electron microscopy: (1) plaque zone, suggesting susceptibility of the gingival tissue to bacterial invasion; (2) nude zone, demonstrating indirect adhesion of epithelial cells to the implant surface through the mucous layer and preventing bacterial invasion; and (3) epithelial cell attached zone, having greater bond strength of epithelial cells at the cell-implant interface as compared to cell-cell bonding within the epithelial cell layer. This study suggested that epithelial cell attachment/adhesion may play a dominant role in retaining the successful condition of a dental implant.     

Review of Zest for work.

Reviews the book "Zest for work" by Hersey Rexford (see record 1955-06370-000). The present book includes information about workers in railroad shops. According to the reviewer, the work in this book does not turn up any dramatic discoveries, but the case studies should interest some readers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mucosal attachment at different abutments. An experimental study in dogs

The present experiment was performed to examine if the material used in the abutment part of an implant system influenced the quality of the mucosal barrier that formed following implant installation. 5 beagle dogs were included in the study. The mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. Three fixtures of the Br?nemark System were installed in each mandibular quadrant (a total of 6 fixtures per animal). Abutment connection was performed after 3 months of healing. In each dog the following types of abutments were used: 2 "control abutments" (c.p. titanium), 2 "ceramic abutments" (highly sintered Al2O3), 1 "gold abutment", and 1 "short titanium abutment". This "short titanium abutment" was provided with an outer structure made of dental porcelain fused to gold. Following abutment connection a plaque control program was initiated and maintained for 6 months. The animals were sacrificed and perfused with a fixative. The mandibles were removed and each implant region was dissected, demineralized in EDTA and embedded in EPON. Semithin sections representing the mesial, distal, buccal and lingual aspects of the peri-implant tissues were produced and subjected to histological examination. The findings from the analysis demonstrated that the material used in the abutment portion of the implant influenced the location and the quality of the attachment that occurred between the periimplant mucosa and the implant. Abutments made of c.p. titanium or ceramic allowed the formation of a mucosal attachment which included one epithelial and one connective tissue portion that were about 2 mm and 1-1.5 mm high, respectively. At sites where abutments made of gold alloy or dental porcelain were used, no proper attachment formed at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutment fixture junction was hereby occasionally exposed and the mucosal barrier became established to the fixture portion of the implant. It was suggested that the observed differences were the result of varying adhesive properties of the materials studied or by variations in their resistance to corrosion.     

Comparison of strength and failure mode of seven implant systems: an in vitro test

STATEMENT OF PROBLEM: The mechanical weakness of implant systems is a problem in the clinical situation. PURPOSE: This study experimentally evaluated how joint design influences the strength and failure mode of dental implant systems. MATERIAL AND METHODS: The strength tests focused on the systems as a whole. Seven implant systems with different joint design were evaluated. RESULTS: Strength and failure mode varied significantly between the implant systems and deep joints, in contrast to shallow joints, favored resistance to bending moments. The mean failure force ranged between 138 to 693 Newtons for the various implant systems. CONCLUSION: In construction of implant systems, joint depth should be taken into consideration.     

Single-stage surgery for implant placement: a retrospective study

Single-stage implant placement surgery offers patients a number of advantages. These include reduced cost and time commitments and greater comfort, function, and convenience. This article reports on the results of using a single-stage technique with 58 patients fitted with 240 implants. No implant failures were detected in any patients prior to the final attachment of a Dolder bar. Among the 27 patients and the 125 implants followed for a longer period of time, 99.2% exhibited no signs of implant mobility or pain. Indicators of gingival health and oral hygiene ranged in quality from acceptable to ideal.     

Biomechanical considerations when combining tooth-supported and implant-supported prostheses

The force distribution of multiple tooth-supported and implant-supported prostheses is completely different. A direct correlation exists between the degree of flexion at the site of loading and the amount of force distribution to other members of the prosthesis. Micromovement produced by the periodontal fibers facilitates force distribution to all the root surfaces of the natural tooth abutments. The rigidity of the implant/abutment/prosthesis configuration concentrates the force at the crestal bone at the site of loading with limited distribution to the remaining implants. Differential mobility concentrates the force distribution to the bone support of the most rigid members of splinted natural teeth or to the implants when they are united with natural teeth in a combined prosthesis. Implants always support the natural teeth and never the other way around. Therefore a nonrigid attachment is recommended between a tooth-supported prosthesis and an implant-supported prosthesis when they are combined. However, when implants are interspersed with natural teeth in the same prosthesis, the restoration will be implant borne. This requires special force distribution analysis to prevent implant overload.     

Generation, Microwave Spectrum, and Ab Initio MO Calculation of trans-1-Nitrosopropene, CH3CH&dbond;CH-NO (syn form)

With the increasing worldwide spread of the Isshiki technique for external vocal fold medialization, some disadvantages and limitations have also emerged. and an increasing demand for a ready-made and standardized implant system can be observed. For this reason. I started experimental and clinical investigations with the goal of replacing the silicone with a safer material, and also simplifying and standardizing the surgical procedure. In particular, the danger of implant dislocation should be excluded with greater certainty. As a result, I have developed an implant made of medical-grade titanium. My surgical experiences in 20 patients with this newly developed titanium vocal fold medializing implant revealed that vocal fold medialization could be performed easily and that no perioperative complications occurred in any case. The major advantage was a significant reduction of operative time due to the preformed implant. This is not only more convenient for both the surgeon and the patient, but is also critical for obtaining optimal results due to the reduced intralaryngeal swelling and hematoma. The reduction of the glottic gap by the operation was statistically significant. Significant improvement of all voice parameters was achieved and demonstrated by a statistically significant reduction of the voice dysfunction index. Compared to the current techniques and implant systems, I see the following additional advantages: 1) titanium is a relatively safe implant material with excellent biocompatibility: 2) the design of the implant ensures optimal fixation and stabilization: 3) the implantation technique and handling is simple and time-saving; 4) the titanium sheet is easy to shape and adapt to the individual situation: and 5) only 2 sizes of implants, and no expensive instruments, are required.     

Characterization of two avian reoviruses that exhibit strain-specific quantitative differences in their syncytium-inducing and pathogenic capabilities

This report outlines the experimental, surgical, and prosthodontic protocols for a prospective clinical trial using the Endopore dental implant to replace single maxillary teeth. Twenty patients (10 male, 10 female) ranging in age from 30 to 60 years each received one implant (mean length 10.1 mm), which, after an initial healing period of 4 months, was restored with a single crown. Records collected included radiographs, Periotest mobility measurements, supragingival Plaque Index, and an assessment of peri-implant soft tissue health using pocket probing depths, sulcular bleeding following probing, and probing attachment levels. Radiographs were exposed at predetermined intervals following crown placement (1 and 6 months, and then yearly) in a standardized procedure using a specialized filmholder that attaches to each implant after removal of the crown. At the time of this preliminary report, all of the 20 implants placed had been uncovered and were in function; 16 of the implants had been in function for 6 months or more, 14 had passed 1 year of function, and 3 had passed the 2-year function point. There have been no failures to date.     

Toward a neurobiology of attachment.

Although much has been written about the psychological aspects of attachment, still relatively little is known about how the brain organizes this complex behavior or how attachment alters brain organization. Recent research has suggested that neuropeptides may be important as neural modulators for several complex behaviors. This review examines the research on one specific neuropeptide, oxytocin, to describe approaches to the neurobiology of attachment at several levels, including molecular, cellular, and whole animal studies. A key to understanding oxytocin's role in behavior is a careful analysis of the pattern of oxytocin receptors in the brain. The available data support the hypothesis that oxytocin is critical for maternal behavior and pair-bond formation in select nonhuman animals. Humans have oxytocin and brain oxytocin receptors, but the role of this neuropeptide system in human attachment remains highly speculative. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implant retained overdentures in mandibular reconstruction: a case report

This case report describes the clinical and laboratory procedures used in the rehabilitation of a patient treated for oral cancer with surgery and radiation therapy. During surgery, a large portion of the mandible was removed and reconstructed with a bone graft. Following therapy, the patient was left with poor esthetics and difficulties with mastication and speech. The goal of prosthodontic treatment was to improve esthetics and restore function. This was successfully achieved through the placement of dental implants and the construction of an implant retained overdenture. A bar was employed to split the implants together and an O-ring system was chosen for retention. The decision to use this type of prosthesis and attachment selection was based on the patient's dental history, esthetic demands, and the need for stress distribution.     

Cochlear implants in children: an analysis of use over a three-year period

OBJECTIVE: This study aimed to determine whether children continue to wear their cochlear implant systems 1 and 3 years after implantation. STUDY DESIGN: The design was a prospective study based on the analysis of forced-choice questionnaires on implant use completed independently by parents and teachers. SETTING: The study was performed at a dedicated pediatric cochlear implant program in a tertiary referral center in the United Kingdom. PATIENTS: All 85 consecutively implanted children who had reached the 1-year interval after implantation and 37 children who had reached the 3-year assessment interval after implantation participated. The patients represented all socioeconomic status groups, the entire range of educational settings, and often lived at a considerable distance from the implant center. MAIN OUTCOME MEASURES: Parents and local teachers were asked to describe implant use in the following categories: 1) all of the time; 2) most of the time; 3) some of the time; and 4) none of the time. RESULTS: One year after implantation, parents and teachers, respectively, rated 79 (93%) and 82 (96%) children as full-time users (category 1). Parents rated six children (7%) as users most of the time (category 2), and teachers rated three children (4%) as users most of the time. No child was rated as an occasional or nonuser (category 3 or 4). At 3 years after implantation, 33 (89%) and 34 (95%) children were rated as full-time users (category 1) by parents and teachers, respectively. Parents judged four children (11%) and teachers rated two children (5%) to be users most of the time (category 2). Again, no child was rated in category 3 or 4 as an occasional or nonuser. CONCLUSIONS: The majority of implanted children use their implant systems all of the time over a 3-year period after implantation when selected appropriately and given appropriate follow-up.     

Fixed temporization and bone-augmented ridge stabilization with transitional implants

Utilization of dental implants in full-mouth restorations is now a well-accepted treatment modality, with numerous modifications and implant systems documented in the literature. The efficacy of the treatment procedure generally requires an extended postplacement healing period prior to loading the implant fixture with the stress of mastication. Until recently, clinicians have not been able to address patient comfort requirements during the healing period. The teaching objective of this article is to present and evaluate a transitional implant system used to provide function during the healing phase. The system consists of thin titanium transitional implants and a three-component overdenture that is intended to absorb the pressure during function and protect the augmented implant site and the definitive implant fixtures from the stress of immediate loading. Treatment objectives for the transitional and definitive implants are made during the initial treatment planning. Three cases are presented to document and illustrate the clinical procedure.     

Attending to the exploration side of infant attachment: Contributions from self-determination theory.

Understanding the intergenerational transmission of attachment patterns has been a main focus of attachment research for many years. Most of the empirical work conducted on this question has addressed maternal sensitivity to infants’ attachment needs. Given that security of attachment is defined as an attachment/exploration balance, some researchers have stressed the need to explore maternal behaviours in the context of infant exploration. The authors propose that self-determination theory (SDT) could contribute to attachment work in this respect given that it has clearly operationalized parental exploration-related behaviours and has related them to numerous child outcomes. This article highlights conceptual, empirical, and methodological parallels that can be drawn between SDT and attachment theory, thus suggesting that they could be complementary on many levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Continuity and change in the measurement of infant attachment: Comment on Fraley and Spieker (2003).

R.C. Fraley and S.J. Spieker (2003) refocused attention on the important question of continuous versus categorical measurement of infant attachment. This commentary begins with a brief response to Fraley and Spieker's position. Next, it highlights the usefulness of the categorical approach by reviewing some of the major advances in the field that have been fostered by a categorical approach. These include the identification of the disorganized attachment group, the development of the concept of conditional behavioral strategies, the creation of systems for coding attachment beyond infancy, and a greater understanding of cross-generational associations. The author then makes several propositions for future research that are necessary for clarifying how best to measure infant attachment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nuclear magnetic resonance and cochlear implant

Chou underlined that ive potential effects may be anticipated if MRI is realized on implantees: 1) force on the implant by strong magnetic field, 2) current induced by the implant in the radiofrequency (RF) field, 3) damage of implant by RF exposure, 4) MRI image distortion caused by the implant, 5) implant and adjacent tissue heating due to the absorption of RF energy. We studied the reality of the four first of these risks on the Digisonic cochlear implant from MXM using the Siemens Magneton 42 SP, which supplied the implants during 10 minutes with 1 Tesla magnetic field, RF 42 MHz, maximum intensity 10 kV. During T1 and T2 sequences we could notice that: 1) Provided the receiver is strongly attached in its skull niche as requested by normal surgical procedure, no deplacement may be observed: 2) No adverse current may been observed as well on the implanted electrodes as in the internal circuitry; 3) No damage or adverse magnetisation have been detected in the 3 studied receivers; 4) Cerebral imaging of the animal is moderately darkened by the implant. The volume of the shadow involved by the implant is approximately three times the volume of the implant. As Chou demonstrated that no observable heating could be detected after a long MRI sequence, and as Portnoy using Nucleus device observed also that neither adverse current nor implant damage could be detected, we estimate that there are no real contraindication to perform MRI on implantees, provided the surgical attachment has been correctly realised. Practical attitudes will be evoked and discussed.