Histochemical and laser scanning microscopy characterization of the hydroxyapatite-bone interface: an experimental study in rabbits.

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.

Cystic compound odontoma in an unusual pericoronal posterior location.

The authors present a case of a compound odontoma located in a pericoronal location in the third molar region. The odontoma was in a radiolucent area enclosing the crown of the unerupted third molar.

Light and laser scanning microscopy analysis of hydroxyapatite used in periodontal osseous defects in man: evidence of a different resorption pattern in bone and soft tissues.

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.

Histologic analysis of a screw implant retrieved from man: influence of early loading and primary stability.

This paper presents a histologic analysis of a one-piece screw implant put into immediate function and retrieved from man after 7 years of clinical function. Compact lamellar bone with many Haversian canals and osteons was found very near the metal surface, and the morphometric analysis of the perimeter of the implant showed a percentage of bone contact of 86.69% (SD = 5.43). The compact bone was particularly thickened around the top of the spires. At high-power magnification, it was possible to observe optically a small empty gap between bone and titanium, and the use of a histochemical stain (von Kossa) showed that mineralized bone was separated from the metal surface by a very thin layer of unmineralized red-stained material; this layer had the same staining features as the osteoid and the osteocyte lamina limitans.

An histologic and histomorphometric study of bone reactions to unloaded and loaded non-submerged single implants in monkeys: a pilot study.

The authors present an histologic study of bone peri-implant tissue responses to non-submerged unloaded and early-loaded titanium screw implants in monkeys. Titanium screws were placed in the maxillae of 3 Macacus rhesus monkeys. One crown for each of three implants was placed after 30 days under occlusal contact, while the other three implants were left unloaded (one pair per animal). Fifteen months later, the animals were killed, and block sections were obtained to be processed for histology. Thin ground sections were excised so that histomorphometric analyses could be performed. In all samples examined, a tight contact of new bone to the implant surfaces was observed. Moreover, around the implant necks of the early-loaded screws was observed an histologic pattern of lamellar, cortical bone, thicker than in unloaded implants. Comparison with peri-implant bone of adjacent teeth showed a similarity to the surfaces of loaded peri-implant bone.

[The influence of the "age factor" on periodontal conditions in the diabetic patient]. / L'influenza del "fattore età" sulle condizioni parodontali del paziente diabetico.

Conflicting reports exist in dental literature on the relationship of diabetes mellitus to periodontal disease. Among the controversies about this relation, the role played by the age of patient has been widely investigated. Some authors, in fact, reported an increased prevalence and severity of gingivitis and periodontitis in children and young individuals with insulin dependent diabetes mellitus (IDDM) in comparison to healthy subjects, while other researchers were not able to confirm this finding. In particular some authors postulated the hypothesis that the diabetic state could influence periodontal conditions just after the age of 30-35. The aim of the present study has been to verify this hypothesis. One hundred thirty-two subjects participated in this study; among them 66 were IDDM patients and 66 were healthy controls comparable to the diabetics for the main epidemiological features. In particular, control subjects were similar to the diabetics for oral hygiene level in order not to attribute eventually occurring differences by mistake to the diabetic state instead of to a not comparable amount of bacterial plaque present on the teeth. Among 66 IDDM patients 33 were younger than 30 (medium age = 14; extremes: 6-22) and were indicated as DG (young diabetics) group; others 33 were older than 30 (medium age = 45.1; extremes: 31-66) and were indicated as DA (adult diabetics) group. A similar differentiation was made in the control group obtaining, in this way, two subgroups (CG = young controls and CA = adult controls). In the diabetic groups males were 53% while among controls they represented 58%.(ABSTRACT TRUNCATED AT 250 WORDS)

[The periodontal condition of patients with insulin- and non-insulin-dependent diabetes]. / Condizioni parodontali in pazienti affetti da diabete insulino- e non insulino-dipendente.

The authors compared through the most common clinical indexes the periodontal conditions of a group of type I and type II diabetic patients with those of a group of healthy control subjects. Results showed the existence of statistically significant differences for each parameter considered (plaque index, gingival index, bleeding index, attachment loss). Also with comparable oral hygiene diabetics showed a worse periodontal condition in comparison with controls. In absolute terms type II diabetics presented worse clinical index scores compared to type I diabetics even if not at a statistically significant level.

[A histological study of hard dental tissues in nondecalcified sections using the cutting-grinding technic]. / Studio istologico dei tessuri duri dentali su sezioni non decalcificate con la tecnica cutting-grinding.

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.