A histological comparison in the dog of porous-coated vs. threaded dental implants

The histological findings of an 18-month trial, in the dog of a partially porous-coated endosseous dental implant made of Ti-6Al-4V, with a truncated conical shape, are described and compared with those for a cylindrical, threaded, endosseous implant made of commercially pure Ti. Six beagle dogs each received two porous-coated implants on one side of the mandible and two threaded implants on the contralateral side. Each set of two implants supported a two-unit fixed bridge for an 18-month functional period. Methylmethacrylate sections of both the buccolingual and mesiodistal aspects of each implant were examined qualitatively and by computer-assisted morphometry. The morphometric measurements were used for determination of the length of implant surface in direct contact with bone on each aspect of each implant. The data were expressed both as an absolute length and as a fraction of the maximum length available for contact (contact length fraction or CLF). On the buccal and lingual aspects of the implants, both the absolute lengths and CLF were significantly smaller for the porous-coated design. For the mesial and distal aspects, the absolute lengths and CLF were less for the porous-coated design, but the differences were not significant. However, when the absolute contact length was related to the corresponding vertical bone height, significant differences were observed, the absolute contact length being greater for any given bone height for the porous-coated design. Taken together, the data suggest that shorter implants may be used with the porous-coated design.     

Immune components in human dental periapical lesions.

Immunofluorescence techniques were used to investigate periapical lesions for the presence of components indicative of hypersensitivity reactions mediated by humoral factors. In periapical granulomas, IgG, IgA, IgM and IgE cells represented 70, 14, 4 and 10 per cent, respectively, of the immunoglobulin-containing cells (ICC) observed. Intact and apparently degranulating mast cells were seen in the vicinity of the IgE ICC. Thus, components required for anaphylactic-type hypersensitivity were present in these lesions. The connective tissue of unwashed periapical granulomas stained intensely for IgG but less so for IgA and complement (C₃). Prewashing failed to eliminate this staining which suggested that a portion of these components were bound to tissue. Quick-frozen sections showed enhanced C₃ fluorescence both of connective tissue and of structures resembling small blood vessels. The potential therefore also exists for antigen-antibody complex-type hypersensitivity in this type of lesion. Radicular cysts showed a different pattern of fluorescence in that both IgG and IgA represented 45 per cent of the ICC, whereas IgM and IgE ICC each represented 5 per cent of the ICC. Only anti-IgG tissue fluorescence was noteworthy in cystic tissue. The one periapical scar examined revealed no cellular or connective tissue staining. Thus, periapical tissues can contain the components necessary for host immunopathologic responses. These responses may participate in the development of periapical pathosis.     

Immune components in normal and inflamed human dental pulp.

Normal and inflamed human pulpal tissues were examined for the presence of humoral immune components. The results indicate that normal pulpal tissue is essentially devoid of components necessary for localized immunoglobulin synthesis as shown by the absence of any immunoglobulin-containing cells (ICC). Tissue fluorescence was observed only in the unwashed samples and mainly with the fluoresceinated IgG reagent. This fluorescence was essentially eliminated by prewashing prior to the application of the fluoresceinated antiserums. On the other hand, inflamed pulpal tissues showed the presence of various ICC. IgG ICC were preponderant, constituting more than 60 per cent of ICC observed. Significant numbers of IgA and IgE ICC were also observed in each sample examined; whereas IgM ICC were present in only 3 of 12 specimens. At the tissue level, fluorescence was observed both in unwashed and prewashed tissues, predominantly with the labelled IgG antiserum. The presence of ICC, as well as extracellular immunoglobulin in inflamed pulpal tissue suggests that the potential exists for immune mechanisms to contribute to the pathological periapical changes seen as sequelae to pulpal inflammation.     

The relation of lipids to the mineral components in salivary calculi.

Using lipid histochemical and microradiographic methods, the distribution of lipids and the inorganic component in different areas of salivary calculi was investigated. Two main groups of lipids were found, i.e. hydrophilic phospholipids and hydrophobic lipids. The hydrophilic phospholipids were shown to be composed mainly of phosphosphingosides and of the hydrophobic lipids cholesterol was demonstrated. Phosphosphingosides were localized in more or less lamellar zones as also in large homogeneous areas. In some cases the calculi were surrounded by a structureless non-mineralized zone exhibiting a strongly positive reaction for phosphosphingosides. Cholesterol was found in isolated band-formed areas. Phosphosphingosides and cholesterol were especially prevalent in areas showing a low or slight degree of mineralization. In areas showing a high degree of mineralization the corresponding lipids gave a weak or absent histochemical reaction. After EDTA-decalcification, however, an increase in the concentration of lipid was noticed in high mineralized areas, indicating a masking process. The influence of various factors on the presence and distribution of different lipids was discussed.     

Cost-effectiveness modeling of dental implant vs. bridge

Aims: We assess the cost-effectiveness of dental implant first-line strategy vs. fixed partial denture strategy in patients suffering from one single missing tooth.
Materials and methods: The model used a simulation decision framework over a 20-year period. Potential treatment switches can occur every 5 years. Transition probabilities come from literature, epidemiological reports or expert opinions. They have been programmed using specific distribution ranges to simulate the patients' and practice variability, and to take into account parameter uncertainty. Direct medical costs have been assessed according to a cost survey. Probabilistic sensitivity analyses were conducted using 5000 Monte-Carlo simulations, generating confidence intervals of model outcomes.
Results: We found that mean cost-effectiveness of the bridge strategy is higher than the implant strategy.
Conclusion: Implant as the first-line strategy appears to be the 'dominant' strategy, considering the lower overall costs and the higher success rate.     

Pain management in dental practice: tramadol vs. codeine combinations.

BACKGROUND: Tramadol hydrochloride is a novel, centrally acting analgesic with two complementary mechanisms of action: opioid and aminergic. First marketed in 1994, tramadol is frequently prescribed by physicians for the management of moderate-to-moderately severe chronic pain. The author evaluates its unique analgesic pharmacology and limited clinical utility for managing acute pain in dentistry. TYPES OF STUDIES REVIEWED: Clinical drug trials in medicine and dentistry were reviewed to assess analgesic efficacy. Postmarketing surveillance studies and reports of adverse drug events were evaluated to determine short- and long-term safety. RESULTS: Tramadol's maximum analgesic efficacy for relieving acute pain after oral surgery appears to be similar to that of 60 milligrams of codeine alone but less than that of a full therapeutic dose of a nonsteroidal anti-inflammatory drug or a codeine combination, such as aspirin/codeine or acetaminophen/codeine. Adverse events reported by patients receiving tramadol therapy since it was approved by the Food and Drug Administration suggest a risk of seizures, drug abuse and anaphylactoid reactions. CLINICAL IMPLICATIONS: Tramadol has limited indication for management of acute pain in dentistry, possibly as an alternative analgesic when gastrointestinal side effects contraindicate the use of nonsteroidal anti-inflammatory drugs and when codeine/acetaminophen combination analgesics are not well-tolerated or are contraindicated.     

Immuno-electron microscopic study of antigenic surface components of Actinomyces naeslundii in human dental plaque.

Rabbit antiserum to formalin-killed Actinomyces naeslundii I was used to investigate the ultrastructural location and distribution of the antigenic sites of A. naeslundii. Antigenic sites were identified by an indirect technique using goat anti-rabbit IgG coupled to horseradish peroxidase, also used to identify individual cells of A. naeslundii in a mixed bacterial population and in freshly isolated dental plaque. The bound antibody and associated reaction product were visible in ultrathin sections as an electron-dense amorphous material (100–150 nm thick) in juxtaposition to the bacterial cell wall. The location of the immuno-reactants suggested that the antigens are distributed superficially and evenly over the entire bacterial cell surface. Bridge-like extensions of the immuno-reactants connected adjacent cells, suggesting that a limited amount of antigenic material might extend out from the cell wall to provide structural continuity with similar material on adjacent cells.     

The relation of lipids to the mineral components in salivary calculi

Using lipid histochemical and microradiographic methods, the distribution of lipids and the inorganic component in different areas of salivary calculi was investigated. Two main groups of lipids were found, i.e. hydrophilic phospholipids and hydrophobic lipids. The hydrophilic phospholipids were shown to be composed mainly of phosphosphingosides and of the hydrophobic lipids cholesterol was demonstrated. Phosphosphingosides were localized in more or less lamellar zones as also in large homogeneous areas. In some cases the calculi were surrounded by a structureless non-mineralized zone exhibiting a strongly positive reaction for phosphosphingosides. Cholesterol was found in isolated band-formed areas. Phosphosphingosides and cholesterol were especially prevalent in areas showing a low or slight degree of mineralization. In areas showing a high degree of mineralization the corresponding lipids gave a weak or absent histochemical reaction. After EDTA-decalcification, however, an increase in the concentration of lipid was noticed in high mineralized areas, indicating a masking process. The influence of various factors on the presence and distribution of different lipids was discussed.