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PubMed2005

Remineralization of carious dentin. II: In vivo microradiographic and chemical studies in human permanent teeth capped with calcium hydroxide.

The main aim of this in vivo study was to evaluate a possible remineralization of human carious dentin by means of chemical and microradiographic studies. Eighty-six samples of carious dentin were removed from 36 permanent teeth of 24 patients. These were divided into untreated (control) and chemically pure calcium hydroxide-capped (experimental) samples and analyzed at intervals varying from 10 to 120 days. They were classified according to depth of caries and degree of dentin softening and evaluated in relation to weight, phosphorus concentration, qualitative and quantitative microradiography and absolute values of total mineral content. One of two halves of each sample was selected for chemical studies and the other for total content of mineral salts. Experimental samples were examined with a light microscope and the results obtained showed a qualitative increase in radiopacity. Quantitatively, it was observed that, in the case of samples analyzed for phosphorus concentration, the average mean of differences in percentage increase after treatment was 9.6%, while for the samples evaluated microradiographically for total mineral content, it was 22.29%. In both cases, the differences were statistically significant.

Adolescent↗
PubMed1980

Ultrastructural and cytochemical observations on the alternating morphologic changes of the ameloblasts at the stage of enamel maturation.

The functional role of the alternating morphologic changes of the rat and hamster incisor ameloblasts at the stage of enamel maturation was investigated. Special attention was paid to the distribution of the intravenously injected horseradish peroxidase (HRP) throughout the ameloblastic layer. The ameloblasts at the stage of enamel maturation were divided into two groups with respect to their distal cell borders: ruffle-ended (RA) and smooth-ended ameloblasts (SA). In the ameloblastic layer, SA were distributed as several band-like structures (SA-bands) which ran transversely or obliquely along the distal surface of the ameloblastic layer. Intravenously injected HRP permeated the intercellular spaces of SA and reached the surface of the enamel, however it did not penetrate the distal junctions of RA. Five min after the injection, HRP was incorporated into the cytoplasmic vesicles of RA, while no incorporation was shown in SA. After 1 hr, however, HRP was incorporated into the incisal one-third of the ameloblasts in each SA-band. Acid phosphatase activity (p-nitrophenylphosphatase) was shown in the cytoplasmic vesicles, both in RA and SA. The most intense alkaline phosphatase activity was located on the ruffled border of RA, while no activity was detected on the unmodified apices of SA. Contact microradiography revealed a gradual increase of the radio opacity of enamel towards the incisal direction independent of the alternating changes of overlaying RA and SA. However, the fluorescence of injected tetracycline showed intense labelling at the portions of enamel which corresponded to RA. The portions of enamel being overlayed by SA were located in between such labelled areas and showed only faint fluorescence of tetracycline. These results suggest that, RA actively degrade, resorb and then digest the organic matrices of the enamel and also transport minerals into the enamel. It is also suggested that SA are formed from the RA which have become inactive metabolically and here the exhausted cytoplasmic organelles seem to be renewed and reactivated.

Acid Phosphatase↗
PubMed1991

Longitudinal observation of cementum regeneration through multiple fluorescent labeling.

The assessment of new attachment after periodontal treatment has been the focus of continuous research. An approach to longitudinally examine the deposition of cementum was devised by using fluorescence microscopy (FL), contact microradiography (CMR), and toluidine blue staining (TBS) after the injection of three labeling agents known to be incorporated within newly mineralized tissues with different tones: tetracycline, calcein, and alizarin complexion. Three adult Japanese monkeys (male, 6.0 to 8.3 Kg weight) were used for this experiment. Bone defects were surgically created in 24 mandibular sites and a copper plate was inserted for a period of 4 weeks to promote microbial colonization to form periodontal pockets. Scaling and root planing (baseline) were then performed, and the fluorescent agents were administered twice weekly leaving a 1 week interval between the different agents. The mandibular specimens were fixed in neutralized formalin and embedded in polyester resin. Undecalcified sections were prepared 3, 6, and 9 weeks after baseline. Cementum regeneration was confirmed in 18 out of 24 sites; in 6 samples only epithelial proliferation was observed. Regeneration could be seen as early as 2 weeks after debridement. Cementum was identified by observation under FL of a labeled structure, discrimination in the degree of mineralization of dentin by CMR, and by the presence of functional collagen fibers and location of the epithelial border by TBS. In this study the use of three different labeling agents using the three observation techniques was shown to be effective for the longitudinal assessment of cementum regeneration.

Alveolar Bone Loss↗
PubMed1991

Videodensitometrical study of the alveolar bone crest in periodontal disease.

The relative mineral content per unit volume of bone in the alveolar bone crest was determined in 81 bone crests from 25 human autopsy cases by means of contact microradiography and videodensitometry of 100 microns thick sections. Each bone crest was divided in 4 areas: crestal, mesial, distal, and trabecular; and the relative mineral content was determined for each area. The data were analyzed statistically and it was found that the crestal area had a significantly lower mineral content than the other 3 areas. Histologically, the crestal area had a reduced number of Sharpey's fibers and it was speculated that these features lower the probability of restoring the natural crestal shape and the fiber reattachment, increasing the risk of bone loss. No correlation was found between relative mineral content and age or extent of inflammatory infiltration of the periodontal tissues.

Absorptiometry, Photon↗
PubMed1994

Regional accelerated phenomenon in the mandible following mucoperiosteal flap surgery.

Striking remodeling activity occurs adjacent to the site of injury in orthopedic surgery. This reaction has been described as regional accelerated phenomenon (RAP), as it speeds up the healing stage. The phenomenon is a transient burst of localized remodeling process following surgical wounding of cortical bone. We explored whether RAP occurs following mucoperiosteal flap surgery in the jaw bone. Mucoperiosteal flaps were performed on 60 Wistar rats, either only on the buccal aspect or both on buccal and lingual aspects of the mandible. The surgical procedure lasted an average of 30 seconds and the flap was readapted without sutures. The rats were sacrificed at 3, 7, 10, 14, 21, and 120 days. High resolution x-ray microradiography of 1 to 1.5 mm thick ground sections between premolar and molar regions of the mandible were analyzed and revealed large areas of radiolucency which correlated to massive resorption of the alveolar bone, as well as areas in the bone proper. The RAP was observed as early as 10 days in the treated side group. Striking resorption of the cortical bone, both on the surface and the bone proper, occurred on the periodontal aspect of the crestal bone leading to widening of the periodontal ligament space, where a mucoperiosteal flap was performed on the buccal aspect. The resorption was more prominent when a mucoperiosteal flap was performed both on the lingual and buccal aspect. The alveolar bone recovered almost to control levels 120 days after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1996

Healing response to anorganic bone implantation in periodontal intrabony defects in dogs. Part I. Bone regeneration. A microradiographic study.

The purpose of the present study was to explore the regenerative potential of anorganic bone plus collagen (AB-C) in experimental intrabony defects. Eight healthy female beagle dogs, 3 to 4 years old and weighing 15 to 16 kilos, were used. After extraction of the mandibular third premolars (P3), surgical defects were created and inflammation induced by placement of cotton and steel braids. Eight weeks later, the braids were removed. The experimental lesions thus obtained were either treated by plain flap curettage (group 1: control) or were, in addition, implanted with AB-C (group 2: experimental). Blocks of AB-C alone were observed by scanning electron microscopy (SEM). The results show that the surface of the particles have the characteristics of a bone tissue. These particles are gathered together with a fibrillar network. Six, 18, and 36 weeks postoperative (PO), non-decalcified specimens from both groups were examined histologically by contact microradiography. In group 1, no significant bone regeneration was observed at 6, 18, or 36 weeks PO. In group 2, trabeculae undergoing mineralization and circumscribing dense particles above the reference notch were seen at 6 weeks PO; 18 and 36 week specimens showed significant bone regeneration with more or less dense remaining particles. The periodontal ligament space was always clear and the only signs of ankylosis noticed were deep in the notch on one 18 week group 2 specimen and on one 36 week group 1 specimen.

Alveolar Bone Loss↗
PubMed2000

The effect of topical delivery of novel bisacylphosphonates in reducing alveolar bone loss in the rat model.

BACKGROUND: Periodontal surgery stimulates osteoclast activity, leading to varying amounts of alveolar crest loss. We have established that topical application of 20 mg/ml of alendronate placed at the surgical mucoperiosteal site produced a striking reduction of alveolar bone loss in the rat model. The aim of this investigation was to examine the antiresorptive efficacy of 3 novel bisacylphosphonates topically delivered at the surgical site, in comparison to alendronate and etidronate which are in clinical use. METHODS: Mucoperiosteal flap (MF) surgery was performed on the buccal and lingual aspects next to molars on both sides of the rat mandible. A gelatin sponge soaked in the bisphosphonate solution prepared by dissolving 20 mg of the bisphosphonate (alendronate, etidronate, VS-5, VS-6, ISA-13, SuBP) in 1 ml of saline was applied to exposed bone on the right side of the mandible (experimental, MF + BPs ) and the left side was treated with saline only (control, MF + S). Sections were evaluated for bone loss using microradiography pattern and amount. RESULTS: The 3 novel bisacylphosphonates, VS-5 VS-6, and ISA-13 were more effective than etidronate, and less effective than alendronate. The most effective among this group was ISA-13 followed by VS-5 and VS-6. CONCLUSION: We conclude that ISA-13-like alendronate is effective in reducing alveolar bone loss when delivered at surgical sites. Since ISA-13 is well absorbed through mucose tissues, we suggest that ISA-13 efficacy on reducing bone loss should be tested by its application on the mucosal tissue.

Administration, Topical↗
PubMed2003

The influence of alendronate on bone formation and resorption in a rat ectopic bone development model.

BACKGROUND: Most bone grafting techniques that include bone marrow, alloplastic materials, and extracellular bone matrix produce new bone mass, filling bone defects unpredictably. In most cases, the new bone undergoes resorption due to low local strains, resulting in significant bone loss. Recently, it was shown that alendronate and other bisphosphonates reduce bone loss when administered systemically or locally. The aim of this study was to investigate whether alendronate is effective on bone formation or bone resorption. METHODS: A total of 64 rats were divided into 2 main groups. In all the rats, fresh bone marrow removed from DA young rats was placed into demineralized rat femur cylinders (DBMC) and implanted into subcutaneous sites of host DA rats, to form new bone. Group A served as an alendronate treatment group, and group B served as a non-treated control. Group A received 100 microl of 1.5 mg/ml alendronate solution at 1, 2, and 3 weeks (group A1) and at 3, 4, and 5 weeks (group A2). At designated times, the rats were sacrificed, and the implanted DBMC was dissected out of the thorax and processed for histological and microradiography image analysis. RESULTS: Alendronate given at 1, 2, and 3 weeks (during the bone formation phase) did not increase the amount of bone or the visual bone density in comparison to the time-matched control, after 4 and 8 weeks. When alendronate was injected at 3, 4, and 5 weeks, the bone mass increased by 70% and by 166% after 6 and 10 weeks, respectively, in comparison to the untreated control. The visual bone density in group A2 was maintained at the level of 140 +/- 15 at 6 weeks and 152 +/- 15 at 10 weeks. The matched, non-treated control group B2 was significantly lower, 106 +/- 20 and 108 +/- 15, respectively. The histological sections showed that alendronate treatment at 3, 4, and 5 weeks maintained the normal appearance of the ossicle at 6 and 10 weeks in comparison to the osteopenic bone appearance in the matched controls. CONCLUSIONS: This study suggests that alendronate is effective in inhibiting bone loss, but ineffective during the bone formation phase. We suggest, therefore, that alendronate should be administered in procedures where bone resorption is expected.

Alendronate↗
PubMed2003

Combined local application of tetracycline and bisphosphonate reduces alveolar bone resorption in rats.

BACKGROUND: Recent animal studies have shown that a combination of chemically-modified tetracyclines together with bisphosphonates, when delivered systemically, are synergistically effective in suppressing periodontal bone loss. In the present study, we explored the combined efficacy of local delivery of alendronate and tetracyclines in reducing alveolar bone loss. METHODS: Eighty-six (86) male Wistar rats were used in these experiments. The flap was elevated using a special periosteal elevator, on both sides of the mandible, as described previously. A gelfoam pellet containing the drugs was applied between the alveolar bone and the mucoperiosteal flap, according to the experimental protocol. The rats were divided into 5 treatment groups: 1) alendronate; 2) doxycycline hyclate 10% (DOXY); 3) tetracycline hydrochloride 1% (TET); 4) alendronate + DOXY; and 5) alendronate + TET. In the operated control sites (C), saline was applied. The rats were sacrificed 21 days following the flap procedure. Sections of the mandibles (1.5 mm), in a buccal-lingual direction, underwent microradiography and were analyzed for bone loss. RESULTS: DOXY alone was most effective in reducing bone loss. Alendronate was also effective in reducing bone loss as shown in previous reports. TET did not reduce bone loss significantly when used alone. In combination with alendronate TET was synergistically effective. The combined local treatment of alendronate + DOXY showed no additive effect. CONCLUSIONS: In the present study, we found that tetracyclines can be most effective in reducing alveolar bone loss when applied locally. The combined local treatment of alendronate and tetracycline may have a synergistic effect.

Administration, Topical↗
PubMed1997

Postmortem analysis of bone growth into porous-coated acetabular components.

Microradiography, backscattered electron microscopy, and histological analysis were used to conduct a quantitative postmortem study of seven consecutively retrieved anatomical porous replacement acetabular components that had been inserted during total hip arthroplasties. Screws had been used for the initial fixation of six components. The microradiographic analysis of all seven components showed that an average (and standard deviation) of 84 +/- 9 per cent (range, 72 to 93 per cent) of the porous coating was in direct apposition to the periprosthetic bone. The backscattered electron images demonstrated that an average of 12 +/- 6 per cent (range, 4 to 21 per cent) of the space available in the porous coating was occupied by ingrown bone. The amount of bone ingrowth was not significantly different among the three zones delineated by DeLee and Charnley. Uniformity of bone growth into the porous coating suggests that the preferential loading that occurs in the superior region did not differentially affect the bone ingrowth. The present study showed that consistent bone growth into anatomical porous replacement acetabular components can be achieved.

Acetabulum↗
PubMed1978

Microradiographic demonstration of pyelolymphatic backflow in the porcine kidney.

Pyelolymphatic backflow occurs when intrapelvic pressure rises acutely. Although peripelvic and hilar lymphatics have occasionally been demonstrated during intravenous urography and retrograde pyelography, the patterns of intrarenal microlymphatic filling have not previously been studied radiographically in multipapillary kidneys. Microradiography was performed after retrograde ureteral injections of barium sulfate suspension in recently excised pig kidneys. Contrast filled the ducts of Bellini and extended in a retrograde fashion as far as the distal convoluted tubules. Intrarenal cortical and corticomedullary microlymphatics, as well as veins, filled following forniceal rupture and interstitial extravasation. These anatomic studies suggest that the renal lymphatics may function as an alternate pathway of drainage of an acutely obstructed kidney.

Animals↗
PubMedDate not supplied

Demineralization effects of 2 bleaching procedures on enamel surfaces with and without post-treatment fluoride application.

In this in vitro study, the demineralization effect of 2 different bleaching procedures on enamel surfaces with and without the post-treatment application of fluoride was determined. Bovine enamel specimens (n= 180) were ground flat, polished and divided into 6 groups. Group A (n=30) specimens were bleached with Opalescence, 10% carbamide peroxide (Ultradent Products, Inc) for 8 hours daily for 2 weeks; Group B (n=30) specimens were treated with Whitestrips, 5.3% hydrogen peroxide (Procter & Gamble) for 1 hour daily for 2 weeks; Group C (n=30): the same as Group A, but after bleaching, a fluoride varnish was applied on the specimens and left for 1 hour (Duraphat, 2.26% F-); Group D (n=30): the same as Group B, followed by the same fluoride application as Group C; Group E (n=30): the specimens were covered with a glycerin gel as a control group; Group F (n=30): specimens were kept in Coca Cola 1 hour daily for 2 weeks. The mineral loss (vol% microm) and lesion depth (microm) were measured by microradiography. Data analysis was accomplished using the Kolmogorov-Smirnov, Kruskal-Wallis and Mann-Whitney U tests (p<0.05) (SPSS 11.0). The median mineral loss was statistically significantly higher in the non-fluoride groups (A: 271.20 vs C: 128.00 and B: 364.90 vs D: 151.10). The highest mineral loss was found in Group F (581.85 vol% microm) and was lowest in Group E (32.80 vol% microm). No statistically significant difference between groups was found for lesion depth.

Animals↗
PubMed1976

The effect of calcium hydroxide and fluorides on human dentine.

With the aid of scanning electron microscopy and microradiography, 45 teeth including 20 contralateral tooth pairs were studied to assess the effect on human dentine of (1) a 1 minute treatment with 3% NaF, (2) a dressing of Ca(OH)2 and (3) a dressing of Ca(OH)2 and CaPO3F after follow-up periods of 2-8 weeks. After NaF treatment the SEM revealed no sign of obliteration of the dentinal tubules, and on microradiograms no indication of increased density could be registered compared to an untreated control area. Under the calcium dressing the SEM revealed in 13 cases out of 20 (5 cases of 11 intrapair comparisons) a varying degree of constriction of the dentinal tubules. Constrictions varied from one tubule to another and ceased approximately 0.1 mm in the dentine. On the microradiograms no significant difference could be registered between untreated dentine and dentine treated with the calcium dressings. Dressings of Ca(OH)2 a combination of Ca(OH)2 and CaPO3F for 2 months, or a 1 minute treatment with a cavity cleaner containing 3% NaF can thus not be considered to result in a reliable obliteration of the dentinal tubules.

Calcium Hydroxide↗
PubMed1979

Radiopaque zones in the dentin beneath silicate fillings analyzed by electron microprobe.

Seven teeth which showed radiopaque zones beneath silicate fillings were sectioned and studied by microradiography and electron microprobe analysis in order to elucidate which elements were responsible for the increased absorption of X-rays and whether the presence of carious lesions could be masked by foreign elements in the tissue. The Ca concentration was frequently found to be either slightly increased or reduced compared with radiographically unaltered dentin. Increased concentrations of F and Zn occurred in the radiopaque zones. The highest F concentrations (0.4--1%) were recorded in zones with an increased Ca content. The highest Zn concentrations (5--8%) were found in the three specimens having a reduced Ca content. The possible conditions responsible for the increased Ca, F and Zn concentrations are discussed. The results indicate that both Ca and Zn may contribute to the increased absorption of X-rays. The hypothesis that carious dentin may be obscured in intraoral radiographs by the presence of foreign elements in the tissue, was not substantiated.

Calcium↗
PubMed1980

Inhibitory effect of a fluoride-containing amalgam on development of cavity wall lesions in vitro.

This study aimed to compare caries-like lesions produced aroung fluoride-containing amalgam and conventional amalgam fillings in vitro. Class V cavities were prepared in 90 extracted premolars, a fluoride-containing amalgam was inserted in 45 cavities (experimental group) and a conventional amalgam in 45 cavities (control group). After three months in an acidified gelatin solution, a longitudinal ground section passing through the cavity was prepared from each tooth. The sections were imbibed in water, quinoline and some in air before examination by polarized light microscopy. When imbibed in Canada balsam the sections were photographed and areas of demineralization in the enamel measured morphometrically. Some sections were studied by microradiography and electron microprobe analysis. Numerical scoring of the histological observations revealed significantly lower values for enamel and dentin cavity wall lesions in the experimental group, while the scores for the outer lesions were not statistically different between the two groups. The mean extension of enamel wall lesions was significantly lower in the experimental group, while no difference was observed in the outer lesions. A zone of increased mineralization in the enamel cavity walls was a frequent finding in the experimental group. This study has shown that fluoride-containing amalgam has an inhibitory effect on the development of experimental cavity wall lesions in vitro.

Dental Amalgam↗
PubMed1982

Antibiotic compounds and enamel demineralization. An in vitro study.

Discoloration, pigmentation and even caries-like lesions have been reported in teeth subsequent to per oral administration of antibiotics. The present in vitro study examines the possible medicament/tooth reaction by exposing plane, polished enamel surfaces to aqueous solutions or oily suspensions of various commonly used penicillin compounds, or to solutions of tetracycline sodium. The teeth were examined by visual inspection, microhardness tests, scanning electron microscopy and microradiography. pH and [Ca2+] of the test solutions were analyzed by potentiometry. Surface or subsurface lesions and a decline in microhardness were found in (most) enamel specimens exposed to aqueous solutions of the medicaments. Similar changes were found in test specimens immersed in deionized water, while saliva, oily suspensions of the medicaments and aqueous solutions made from ordinary Ca-penicillin had no adverse affect on the enamel. The most serious destruction was seen in enamel specimens submerged in watery solutions made from effervescent (citrate-containing) Ca-penicillin, or from tetracycline. A slight decline in pH was observed in the aqueous solutions during the experiment. The calcium ion concentration did not increase parallel to enamel destruction.

Dental Enamel↗
PubMed1983

Enamel structure in deciduous teeth from low-birth-weight infants.

Ground sections of deciduous teeth from 64 infants with birth weights below 2000 g and from 43 healthy full-term infants were examined in polarized light and by microradiography. The deciduous enamel displayed various changes, which were more frequent and pronounced in the low-birth-weight group. The main findings were diffuse areas of increased porosity and distinct subsurface lesions in the postnatal enamel. Five teeth with enamel hypoplasia from the low-birth-weight group were also examined. The hypoplasias were all located along the neonatal line. The postnatal enamel seemed to be more susceptible to disturbances in the mineralization than the prenatal enamel. The subsurface lesions showed an arrest in the very late stages of enamel maturation, which frequently occurred in the cervical deciduous enamel. Enamel hypoplasia is considered to be a result of severe neonatal hypocalcemia.

Dental Enamel↗
PubMed1984

Microscopic study of enamel defects in deciduous teeth of infants of diabetic mothers.

Ground sections of deciduous teeth from infants of diabetic mothers were examined in polarized light and by microradiography. Widened neonatal lines and subsurface lesions were the main findings in the enamel. Three teeth showed enamel hypoplasia in connection with the neonatal line. The widening of the neonatal line and the hypoplasias are related to the more frequent and more pronounced neonatal hypocalcemia occurring among infants of diabetic mothers.

Dental Enamel↗