Five-year evaluation of implants placed at extraction and with dehiscences and fenestration defects augmented with ePTFE membranes: results from a prospective multicenter study

Background: Barrier membranes have been used to promote bone ingrowth on implants with dehiscences and fenestrations. Membranes also have been used to protect defects adjacent to implants placed at the time of extraction. The concept of guided bone regeneration relates to preferentially allowing cells from bone to migrate into various defects while excluding fibrous tissue and epithelium. The purpose of these procedures is to enhance bone-to-implant contact at the treated sites and to prevent mucosal complications. Purpose: The purpose of this article is to report clinical outcomes for implants placed at the time of extraction and augmented with expanded polytetrafluoroethylene (ePTFE) and followed for 5 years. The outcomes for implants with dehiscences and fenestrations augmented with ePTFE barriers and followed up to 5 years also are reported. Methods and Materials: Four treatment centers participated in this study (Tucson, Gothenburg, Spokane, and Leuven). In the extraction group, teeth were removed for varying reasons, and Brånemark implants were placed and stabilized within the host bone. Defects present at the coronal implant aspect were covered with ePTFE barrier membranes. Flaps were rotated to cover the membrane-treated sites. If exposure of the material occurred prior to second-stage surgery, the membranes were removed. Barriers remaining unexposed were removed at second-stage surgery. The implants were followed up to 5 years. In the fenestration and dehiscence group, implants with exposed threads were augmented with ePTFE barrier membranes. The barriers were removed at appropriate intervals, and the patients were followed up to 5 years. Radiographic measurements were made from nonstandardized periapical radiographs at abutment connection and 1, 3, and 5-year follow-up visits. Results: Forty patients participated in the extraction group. They received a total of 49 implants. Three implants failed prior to loading. The 5-year cumulative survival rates for implants placed at the time of extraction were 93.9% and 93.8%, respectively, for maxillary and mandibular implants. The average maxillary mesial and distal marginal bone loss (1–5 yr) was 0.3 mm (standard deviation [SD] = 1.5) and 0.3 mm (SD = 1.0). In mandibles, the average mesial and distal bone loss (1–5 yr) was -0.2 mm (SD = 0.5) and -0.05 mm (SD = 0.6), respectively. The dehiscence and fenestration group included 44 patients. Twenty-six were followed for up to 5 years. Eight patients experienced total implant failure. For dehiscences and fenestrations, the cumulative survival rates were 76.8% and 83.8% for maxillary and mandibular implants, respectively. The average maxillary mesial and distal bone loss (1–5 yr) was 0.4 mm (SD = 0.8) and 0.2 mm (SD = 0.9), respectively. In mandibles, the average mesial and distal marginal bone loss was 0.3 mm (SD = 0.9) and 0.3 mm (SD = 0.8), respectively. Conclusions: Implants placed at the time of extraction and augmented with ePTFE barrier membranes have favorable long-term predictability. On the other hand, long-term evaluation of implant dehiscences and fenestrations augmented with barrier membranes indicates that they have less favorable 5-year survival rates. Membrane augmentation of these may be questioned.     

Interdisciplinary management of a common esthetic complaint

Esthetic restoration of the maxillary anterior dentition often requires an integrated perio-restorative team approach. Careful attention to treatment planning and treatment sequencing is essential in ensuring a desirable outcome and a satisfied patient. Detailed measurements, diagnostic wax-ups, surgical mock-ups, and stents all are effective communication tools which can be used to enhance interdisciplinary communication. These concepts and treatment modalities are illustrated in this case report.     

Adsorption of organic compounds and hydrophilicity of bismuth,cadmium and antimony electrodes

The adsorption behavior of various organic compounds at bismuth, antimony, cadmium, mercury and other “mercury-like” metals has been discussed. The systematic trends of the influence of the chemical nature of electrode metal and adsorbate to the molecular interaction parameter, a; limiting Gibbs adsorption, Γ_{A, max}; and Gibbs energy of adsorption, ΔG_A⁰, have been analyzed. The ingredients of the total Gibbs energy of organic compounds adsorption have been found. A new more general method for obtaining the metal-water; interaction Gibbs energy has been worked out and used. It was found that the dependence of Gibbs energy of metal-water interaction on the chemical nature of metal and aliphatic organic compound studied is weak. Only in the case of chemically very different metals, for example for Sb and Zn, the difference of Gibbs energy of metal-water interaction values is somewhat higher than the exactness of the determination of the experimental values of Gibbs energy of organic compound adsorption.     

The indications for the surgical treatment of chronic periodontitis of the permanent teeth in children and adolescents of different health groups]

Chronic granulating and granulomatous periodontitis of 250 permanent teeth was treated in children and adolescents aged 7 to 17, surgery had to be resorted to in 44 (18%) cases. Three groups of indications for radical treatment of chronic periodontitis in children were distinguished: difficulties in or impossibility of conservative treatment, inefficacy of conservative treatment, and somatic indications. The conservative and surgical methods together are most often indicated for patients in whom the adverse conditions of treatment (the first group of indications) are associated with an aggravated somatic status. Radical methods of treatment helped attain bone tissue recovery sooner (in 5-6 months) than after conservative therapy alone (in 8-9 months) and completely liquidate chronic foci of odontogenic infection.     

Microstructures of admixed amalgams produced from Pd-containing dispersants.

Blended Pd-containing dental amalgams were developed by substituting Pd for up to 20 w/o Ag or Cu in the Ag-Cu eutectic alloy. Melted ingots were lathe-comminuted to a particle size distribution of 1-45 microns. Alloy blends were created from two parts of a traditional amalgam and one part of experimental Ag-Cu-Pd particles. Amalgams with from 0.42 to 1.67 w/o Pd were fabricated by trituration of alloys and mercury at a Hg/alloy ratio of 1:1 with a mechanical triturator at 5000 rpm for 10 s and hand-condensed. XRD studies of these amalgams revealed the suppression of eta' (Cu6Sn5) phase with Pd addition and no gamma 2 (Sn8Hg) phase found. At 3.3 w/o Pd, the eta' (Cu6Sn5) concentration of the amalgam was below the detection limit of the instrumentation (1%). SEM micrographs revealed that reaction zones around eutectic particles decreased with increased Pd concentration.     

A caries preventive programme for Robertson school children--baseline data.

This study describes the baseline caries experience of a cohort school children in the Robertson area who were selected to take part in a longterm school-based preventive programme. On the whole baseline DMFT values for the various age groups did not differ significantly except for the 13-year-olds at Vergesig who had significantly higher values than those obtained at the other two schools. The D-component predominated with a moderate M-component and no filled teeth. The teeth at risk for the respective age groups did not differ significantly between the schools. The frequency of caries experience decreased from the molars to the central incisors except for the canines which were least vulnerable. The DMFT values were high and warrant the search for the most suitable preventive measures to facilitate reduction towards the WHO goal of 3 for 12-year-olds by the year 2000.     

Retrograde root filling with composite and a dentin-bonding agent. 2.

Abstract Investigations on retrograde root filling using a composite resin, Retroplast, bonded to the root surface with the dentin-bonding agent Gluma have been described. Here, detailed information is given about the surgical procedures. The aim was to obtain a thin retrograde composite filling on the root apex, made slightly concave, sealing the main root canal, accessory canals as well as dentinal tubules. Hemostasis was obtained primarily by applying 1% adrenaline and by using a needle suction tip, and care was taken not to damage the surrounding tissues by the various chemicals. The healing results, after up to 1 year, of 388 cases of various tooth types, treated with either retrograde composite or with amalgam were compared. The healing classification included four categories: 1) complete healing; 2) fibrous healing; 3) uncertain; and 4) failures. In the composite group, the healing rates were as follows: 74% showed completely healing, 4% fibrous healing, 15% uncertain and 7% were failures. In the amalgam group, 59% showed complete healing, 3% fibrous healing, 30% uncertain, and 8% were failures. Complete healing occurred significantly more often after filling with Retroplast than after filling with amalgam (p<0.00005). Significantly fewer proportion to other tooth types. The number of immediate postoperative complications did not differ significantly between the composite and the amalgam groups.     

The effects of resin-bonded and conventional fixed partial dentures on the periodontium: restoration type evaluated

The purpose of this study was to compare the long-term and short-term periodontal response to three different modalities of fixed prosthodontic tooth replacement. Posterior proximal sites adjacent to abutment teeth supporting etched metal and two designs of conventional fixed partial dentures (FPDs) were assessed 6 months to 5 years after insertion. For the long-term observation, the etched metal resin-bonded FPDs had significantly greater plaque scores than both of the conventional designs. The resin-bonded FPD group had statistically, but not clinically, significant increased probing depths than the supragingival FPD group. In spite of the increased levels of supragingival plaque associated with the etched metal FPD, this type of fixed prosthesis was no more injurious to the periodontium than the subgingival conventional FPD designs.     

Vertical root fracture and dentin deformation in curved roots: the influence of spreader design

The effect of lateral condensation using different tapered spreaders was evaluated. Curved mesiobuccal roots of maxillary molars were step-back prepared. Strain gauges applied to the root surfaces measured dentin deformation (distortion) during controlled lateral condensation with either fine finger or D11 spreaders. After obturation, roots were cross sectioned and analyzed under the stereomicroscope to detect the presence and pattern of fractures. The results showed no statistical difference between spreader designs as to mean distortion and the incidence of fractures; however several specimens in the D11 group showed high root distortion measurements. When fractures occurred, there were no consistent patterns of fracture in either spreader group. In conclusion, although there were no significant differences in mean deformation or fracture incidence in curved roots between the spreaders, the roots showing high deformation readings in the D11 group may be more susceptible to future vertical root fractures.