Biomedical subjects
Publications and source records attributed to P Trisi.
The Authors have studied the efficacy of the sealing effect of thermomechanical compaction of guttapercha according to McSpadden with an in vitro analysis on undecalcified tooth sections and with a clinical evaluation of ten patients with periapical lesions. The analysis of the results has shown a good sealing capacity of the McSpadden technique.
The effects of several metabolites deriving from the arachidonic acid cascade on oral tissues are reviewed. These include the effects on the pulp, tissues and gingiva, and on the development of radicular cysts and epithelial tumours of the oral cavity.
Tumor necrosis factor (TNF) and interleukin-1 (IL-1) are soluble factors that play a pivotal role in acute and chronic inflammation. TNF is a 17 Kda protein mainly released by monocytes and macrophages and is a common mediator of toxic shock, cachexia and tumor necrosis. IL-1 was first described as a lymphocyte activating factor and it was then discovered that IL-1 has a number of other biological activities and that there are at least two major types of IL-1 (alpha and beta) which bind to the same receptor. Recently it has been shown that TNF and IL-1 beta have an important role in bone resorption.
The authors present the results of a epidemiological transversal study concerning 26 type I diabetic patients: as a control have been observed 24 healthy subjects, similar for age and sex to the diabetic patients. The results show a higher incidence of caries in diabetic patients than in the healthy subjects; this is probably due to the high carbohydrates diet of the young patients.
Odontoma in most cases presents in the mixed dentition period and can remain for long unrecognised. Asymptomatic during its long latency period, odontoma gives signs of life only in an aspecific way: the absence in the arch of one or more teeth should direct the clinician towards investigations which make it possible to identify the cause, as this may be due to odontomas. Radiography may clearly point to the presence of this lesion and may direct the operator towards surgical/orthodontic treatment so as to restore to the dental arch a tooth that would otherwise have remained included. It is, furthermore, important to remove the lesion, even though it is quite benign, because it is easily subject to septic complications. It should be recalled that it is always necessary to back up clinical with histological diagnosis so as to differentiate the odontoma from other lesions with different prognosis and therapy.
Artificial cross-shaped intrabony defects were created in the mandibles of 12 rabbits and the cavities covered with Type I highly cross-linked resorbable collagen membranes for 30 days. Similar cavities were prepared in three control animals and left uncovered for the same time period. Morphological and analytical data were obtained by means of light microscopy, scanning electron microscopy, and x-ray energy-dispersive spectrometry. After the experimental period, the membrane covered cavities were completely filled with regenerated bone. In the control specimens, the artificial cavities were occupied by fibrous connective tissue.
The aim of this investigation was to conduct a comparative histometric analysis of bone-implant interface between a rough titanium surface and smooth implants in low-density human jawbone after 3, 6, and 12 months of submerged, undisturbed healing. Six adult volunteer patients undergoing standard implant placement were enrolled in this project. Each patient received 1 smooth and 1 rough implant. After 3, 6, and 12 months, the implants were harvested for histometric analysis. The values of bone-implant contact were the following: 3 months smooth 6.2%, 3 months rough 58.9%, 6 months smooth 3.55%, 6 months rough 72.9%, 12 months smooth 6.7%, and 12 months rough 76.75%. The results showed that in low-density bone the rough surface dramatically enhanced the amount of bone-to-implant contact. Because of the small number of implants examined, definite conclusions cannot be drawn, even though the statistical analysis showed significant differences between the smooth and rough groups (P = .0129; F = 76.065). Nevertheless, a trend was evident in these observations: while a rough implant surface may enhance the rate of osseointegration, it is not able to significantly change the bone density, and an implant placed low-density bone is at a higher risk of failure when occlusal loading begins.
The aim of this study was to compare the characteristics of the bone-to-implant interface of hydroxyapatite-coated and non-coated commercially pure titanium threaded implants after different periods of healing in humans. To eliminate possible variations of the results from differences in bone quality and in surgical techniques used in the different test and control sites, only one half of each implant was coated with hydroxyapatite. The coated portions of the implants showed a tendency toward a higher percentage of direct bone-to-implant contact at each period of healing that was observed, although the small number of specimens does not allow definitive conclusions to be made.
With the cutting-grinding technique (Exakt System) it is possible to obtain sections with a width of less than 10 microns of specimens such as teeth, crowns, bridges, implants, mineralized structures, which cannot be cut with routine histological techniques. In the present paper the authors study the efficacy of this technique in hard dental tissues.
An experimental study was done in rabbits to characterize the bone-hydroxyapatite (HA) interface by the use of histochemical staining for mineralized tissue and laser scanning microscopy (LSM) on undemineralized sections. Twenty HA-coated Sustain implants were placed in rabbit femurs and retrieved after 6 months. The specimens were then processed to obtain thin ground sections. In all specimens, there was intimate contact between bone and HA. In some portions, mineralized bone was in tight, direct contact with the HA, while in other portions, a basophilic unmineralized material was present between bone and HA. This material was thicker in areas with active bone formation upon the HA surface and had staining characteristics similar to the material present around the osteocyte lacunae. LSM showed a fluorescence present in many areas of the interface, in osteocyte lacunae, and inside the coating. An organic bonding between bone and HA can probably be hypothesized.
Hydroxyapatite (HA) is a highly biocompatible material that recently has been shown to undergo biodegradation. The mechanisms of this phenomenon are unclear, and humoral and cellular events have been thought to be implicated. In the present study HA particles were put into infraosseous defects on teeth that were to be extracted for prosthetic reasons and then retrieved after a 1-year period. The specimens were processed with the cutting grinding system. Results show a very sharp difference of the biodegradation processes, related to the tissues that surround the HA particles. HA in tight contact with mineralized bone showed no evidence of degradation or resorption, while on the contrary, in the areas where bone loose connective tissue was present, it was possible to observe HA crystals detached and scattered in cells cytoplasm or extracellular fluids. This dissolution and resorption phenomenon were observed also by Laser Scanning Microscope (LSM) in fluorescent mode. These differences in degrees of degradation between bone and loose connective tissue could be due to the small amount of interstitial fluid present in mineralized bone and the greater flow of fluid through connective tissue.