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J L Saffar

Publications and source records attributed to J L Saffar.

At least 19 recordsLinked to original sources
PubMed1992

Effects of prostaglandin inhibition on the bone activities associated with the spontaneous drift of molar teeth in the rat.

Little is known about local bone regulation that enables spontaneous molar tooth drift. In this study the role of prostaglandins (PGs) were investigated in the rat by inhibiting PG-synthesis with indomethacin (7 mg/kg/d). Untreated animals were killed at the start of the experiment, while treated ones were killed after 3, 7, or 14 days of treatment. Mandibles were processed for histomorphometry without demineralization. Changes in osteoclasts and extent of the different steps of the bone remodeling sequence (resorption, reversal, and formation) were assessed along the remodeling side of the socket of the buccal root of the first molar. The total number of osteoclasts decreased after 7 days of PG inhibition (P < 0.01 vs controls) and then partially recovered. This change was due to a sharp decrease in active cells on day 7 (P < 0.01), while inactive cells remained unchanged throughout the experimental period. The extent of resorption fell on day 7 (P < 0.01) and then recovered almost to the control level on day 14. Reversal at first increased insignificantly and thereafter decreased (P < 0.02) for the remaining 7 days. Formation was modified only on day 14; at that time it had doubled compared with controls. These results show that PGs are involved in the local regulation of bone remodeling accompanying tooth drift. Resorption inhibition was partial, indicating that other factors participate with PGs in this regulation; in addition, the trend to recovery observed at the end of the experimental period suggests that these factors can take over from PGs to achieve the necessary remodeling of the socket.

Alveolar Process↗
PubMed1992

Spontaneous recovery from growth disturbances and osteopenia induced by a high carbohydrate diet in hamsters.

Femoral osteopenic changes characterized by a fall in metaphyseal trabecular bone volume (TBV) have been previously reported in hamsters fed a high carbohydrate diet for 45 days. In the present study the effects of the diet were assessed after 90 days. Serum P was significantly reduced (p less than 0.05) in experimental animals; serum Ca was unaltered. Disturbances in body growth had occurred as shown by a reduction in body weight gain (p less than 0.05) in the first 45 days of the experiment and by a decrease in femoral size (p less than 0.02). Osteopenia had also developed: the epiphyseal TBV decreased (p less than 0.05) as well as the thickness of both epiphyseal and metaphyseal trabeculae (p less than 0.001). However signs of partial recovery from this condition were observed as shown by an increased body weight gain in the last 45 days of the experiment (p less than 0.02) and lack of difference in metaphyseal TBV, assumed to be the more labile, between the 2 groups. Moreover bone formation significantly increased along metaphyseal trabeculae and the endosteal aspect of the cortices.

Animals↗
PubMed1991

Partial inhibition of bone resorption by disodium cromoglycate in a synchronized model of bone remodeling.

In a previous study we observed that mast cell degranulation might be associated to bone resorption. To verify this assumption, the efficiency of cromoglycate was assessed on a synchronized sequence of bone remodeling induced in male Wistar rats along the mandibular cortex. After 4 days (time of osteoclastic peak in this model), cromoglycate (15/mg/kg and 30 mg/kg/d per os) decreased the number of degranulating mast cells, especially in the population adjacent to the bone surface. Concomitantly the extent of resorption surface was decreased vs untreated animals. Active osteoclasts were lower whereas the total number of osteoclasts (both active and inactive) was not statistically modified. The mean osteoclast-bone interface was not modified. No dose effect was found. These data indicate that mast cell degranulation is involved in the events leading to osteoclast resorption, presumably in the mechanisms providing osteoclast access to bone surface.

Animals↗
PubMed1991

Identification of osteoclasts and their mononuclear precursors. A comparative histological and histochemical study in hamster periodontitis.

Quantification of osteoclast resorption, a good index of periodontitis destruction, is primarily based on osteoclast identification. As their identification is sometimes dubious, we compared osteoclastic counts in hamster specimens processed for either routine histology or tartrate-resistant acid phosphatase (TRAP) staining. No difference was found between the two approaches concerning the number of osteoclasts. However the mean bone-osteoclast interface was higher in the TRAP-stained specimens (+30%, p less than 0.02). As osteoclast precursors are also TRAP+ cells, they were quantified too. Compared with controls, there was a dramatic increase (p less than 0.0001) in periodontitis-affected animals. Precursors were strongly correlated to active osteoclasts (r = 0.97). Our data suggest that precursors are recruited only when the disease is active in a given site.

Acid Phosphatase↗
PubMed1990

Changes in mast cell number during the activation phase of an induced synchronized remodeling sequence in the rat.

Increase in mast cell (MC) number has been reported in some pathological conditions with increased remodeling. However, it is not known whether MCs are involved in the physiological remodeling of bone. In the present study the possible variations in MCs were investigated during the activation phase in a rat model of synchronized remodeling. Seven groups of 10 rats were used. As early as the first day of induction, MCs increased by 50% and then decreased on day 2. The same pattern of changes recurred on days 3 and 4. Intact non-degranulating MCs increased mainly at some distance from the bone surface. Degranulating MCs conversely decreased near the cambium layer of the periosteum. Prostaglandins were not involved in these changes. These results suggest an association between the events leading to the onset of bone resorption and MCs. Degranulation might induce the release of agents active on these events.

Animals↗
PubMed1990

Bone reactions around transplanted roots. A 5-month quantitative study in dogs.

The aim of this experiment was to study endosteal bone reactions around roots transplanted into an edentulous crest, and the role, if any, of periodontal ligament (PDL) remnants preservation. After extraction of premolars and healing of the crests, 20 roots in 5 dogs were transplanted into bone cavities prepared in the edentulous areas. Roots implanted in the lower and upper right cavities had their PDL remnants preserved while those grafted in the left cavities had their surface planed and dried. After 5 months, the roots with surrounding bone were removed. 2 bone areas were delineated at the mesial aspect of each root, one immediately adjacent to the alveolar wall and the other distal to it. Results demonstrated that bone volume was higher in the proximal versus distal area in the maxilla and mandible preserved groups. The adipocyte content of the marrow spaces, an index of bone maturation, was less pronounced in the proximal versus distal areas in the preserved groups. The number of osteoclasts was higher in the proximal zone in the preserved groups as were the extents of the different bone remodeling activities. The results indicate that the organization of PDL around transplanted roots is associated with rearrangement of the bone tissue surrounding the grafts. This process of long duration might be an adaptation to the likely low mechanical strains applied on bone through the root. Transplantation of PDL-damaged roots did not induce such events in the surrounding bone which had acquired the structure of an edentulous crest.

Adipose Tissue↗
PubMed1990

Bone formation in tricalcium phosphate-filled periodontal intrabony lesions. Histological observations in humans.

The capacity of a tricalcium phosphate (TCP) ceramic to promote bone formation after grafting in intrabony defects was studied in humans. Five biopsies were collected from 4 patients during reentry surgery 16 to 40 months after implantation. They were processed without demineralization for histological examination. In the less mature samples, the grafted material was surrounded by a highly fibrous, highly cellular, and poorly vascularized connective tissue. Howship's lacuna-like cavities were clearly visible at the surface of the material. They contained resorbing mononuclear phagocytes. At a more mature stage, TCP granules were embedded in an acellular fibrous material which underwent mineralization from the medullary spaces towards the granules. The bone formed was subsequently remodeled. The implanted material itself was progressively modified. It first acquired the staining appearance of bone. After its structure became loose and vacuolated, it was invaded by cells and vessels. The present data indicate that TCP has osteogenic potential and is subject to degradation. Unlike in experimental wounds, these processes are of long duration in human defects.

Adult↗
PubMed1990

[Arachidonic acid derivatives in periodontitis].

A myriad of mediators of inflammation are involved in the onset and progress of periodontal disease. The exact roles of some of them are understood nowadays. In this paper, the current knowledge on the products of the arachidonic acid cascade (i.e. prostaglandins and leukotrienes) is reviewed. The main interests of these mediators are in their potential in diagnosing the phases of activity of periodontitis and the therapeutic prospects that their inhibition open up.

Arachidonic Acids↗
PubMed1989

Periodontal and femoral bone status in periodontitis-affected hamsters receiving a high dose indomethacin treatment.

The aim of this study was to test the effect of a high dose (6 mg/kg/d) of indomethacin, a PG-synthesis inhibitor, on hamster periodontitis and to verify a possible systemic skeletal action. Thirty animals were separated into three groups: control, untreated periodontitis-affected, and indomethacin treated groups. Compared to affected untreated animals, indomethacin reduced the number of osteoclasts (p less than 0.001) to the control level, and accordingly the extent of resorption (p less than 0.01). A partial decrease in reversal (p less than 0.05) was also obtained; the persistence of aborted reversal lacunae was the scar of the pretreatment period. The extent of formation was markedly increased by indomethacin (p less than 0.01). Bacterial plaque accumulation was not modified but PMNLs investing plaque were dramatically decreased (p less than 0.02). Indomethacin had no influence on the femoral periosteal remodeling, nor on metaphyseal and epiphyseal trabecular density, nor on growth plate thickness. These results confirm the positive effect of indomethacin on hamster periodontitis and emphasize the role of PGs on periodontitic bone disturbances, particularly on the uncoupling of the remodeling sequence. The reduction in PMNL migration is an important feature, which possibly participates in the improvement of the bone status. The lack of femoral changes indicates that a mid-term treatment with indomethacin has no detrimental action on ordered skeletal growth and bone mass.

Alveolar Process↗
PubMed1988

Role of prostaglandins in bone resorption in a synchronized remodeling sequence in the rat.

The role of prostaglandins (PGs) in physiological remodeling has not yet been defined. The present study was undertaken to determine whether they intervene during the activation phase in a highly reproducible and synchronized model of bone remodeling. Indomethacin was employed to inhibit PG synthesis. This treatment throughout the entire activation period (4 days in this model) inhibited osteoclastic resorption completely. By modifying the treatment procedure, it appeared that PGs were operative mainly between the second and third day of activation. PGs did not seem to act on precursor recruitment, since off-bone osteoclasts (putatively inactive cells) were numerous in the treated groups. PGs might also be involved in osteoclast activity as the mean interface between osteoclasts and bone surface was reduced in the treated groups. However, indomethacin was unable to inhibit the remodeling sequence durably since a 6-day treatment resulted in a high profile of resorption. This suggests that factors other than PGs were responsible for activating resorption.

Animals↗
PubMed1988

[Root reactions during treatment with indomethacin in the rat].

During the course of a study on the effect of indomethacin, an inhibitor of PG-synthesis, on the alveolar bone remodeling associated with the drift of the rat molar, the root profile appeared altered. The perimeter of the buccal root of the lower first molar had increased during the 7-day experimental period (+9%; p less than 0.02) in the treated group. This was due to an increase in the extent of root resorption lacunae (+99%; p less than 0.05). They were located in the disto-buccal aspect of the root, i.e., facing the alveolar wall remodeling area. The periodontal ligament width was also increased (p less than 0.001). This might be an adaptative process to maintain the periodontal ligament width as the drift of the teeth had not ceased while the remodeling had markedly slowed down. These results show that the osteoclastic population responsible for root resorption was not PG-dependent, unlike that active on alveolar wall. In addition, dentin deposition was accelerated in the pulp area underlying the resorption lacunae in the treated group as shown by measuring the distance between two fluorescent labels incorporated in a 6-day interval (p less than 0.05).

Alveolar Process↗
PubMed1987

[The respective roles of occlusal abrasion and bacterial plaque in the etiology of alveolar lysis in periodontitis in hamsters].

This study was designed to determine the respective roles of occlusal attrition and subsequent tooth egression, and bacterial plaque accumulation on bone loss (or radicular denudation) during hamster periodontitis. Seventy young male animals were separated into 7 groups. Occlusal attrition was compared on 3 different diets (standard in pellet form, standard in powder form, and Keyes 2000 in powder form), thought to have different abrasiveness. The role of bacterial plaque wad evidenced by inhibiting it with Penicillin V in animals fed the same 3 diets. Compared to animals killed at the beginning of the experimental period (absolute controls), 3 months later bacterial plaque was slightly increased in hamsters fed the standard diet, very markedly increased in 2000 diet-fed animals and, decreased in the 3 antibiotic treated groups. Occlusal attrition was increased in the 2 groups fed the standard diets but not in the 2000 diet-fed animals. Radicular denudation was slightly increased in the standard diet groups, very markedly increased in the 2000 diet group, and unchanged in the antibiotic treated animals. Thus, the less abrasive diet was associated with the greatest plaque accumulation and bone loss; conversely, with the most abrasive diets, radicular denudation had slightly progressed with only small amounts of plaque. This suggests that in hamster periodontitis, bone loss is not influenced by occlusal attrition but is completely dependent on the direct action of bacterial plaque.

Alveolar Process↗