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PubMedDate not supplied

Enhancing osseointegration by capacitively coupled electric field: a pilot study on early occlusal loading in the dog mandible.

Expeditious postoperative appositional growth of bone to dental implants is desired for clinically successful fixation of oral implants. The present study was performed to evaluate the effect of applying a capacitively coupled electric field (CCEF) followed by functional loading on peri-implant osteogenesis in the dog mandible. Nine adult beagles were used in this study. All premolars on both sides of the mandible were removed from each dog. A physio-odontlam implant (POI, Ti-6AI-4v) with 2 stages (3.7 mm in diameter and 8.0 mm in length), whose surface had been treated with anodic oxidation and sandblasted, was placed into each test site by self-tapping. Daily application of CCEF (8 hours per day) was initiated on the day following surgery and continued for 14 days or 21 days. After CCEF treatment was finished for each period, a prosthetic abutment and a straight post were placed on each implant. Four days after placement of the post, implants were placed under functional loading for 30 days. The dogs were then sacrificed, and histologic and radiographic studies of the mandible were performed. Relatively well calcified, mature bone with a lamellar-like structure was observed by contact microradiography and histologic study (double staining with basic fuchsin-methylene blue) of the peri-implant region on the CCEF-treated samples. In contrast, poorly calcified, immature bone without a lamellar structure was observed in control sites not treated with CCEF. The bone area ratios of the CCEF-treated sides were larger than those of control sides. These results suggest that the application of CCEF after implant placement may enhance peri-implant osteogenesis, even with functional loading.

Animals↗

PubMed2001

[The remineralization of enamel lesions by casein phosphopeptide-amorphous calcium fluoride phosphate in vitro].

OBJECTIVE: To evaluate the remineralizing effect on artificial enamel subsurface lesions in vitro by 2% casein phosphopeptide-amorphous calcium fluoride phosphate complexes (CPP-ACFP) solution. METHODS: Twenty-eight enamel blocks were cut from human third molars, in which 2 lesions were prepared from each block. The 28 samples were randomly assigned to the four study groups, in which each group was incubated in remineralization solution for 1, 3, 5, 10 days respectively. After remineralization the samples were sectioned, microradiographied and the mineral content were determined by microdensitometry. RESULTS: The remineralizing solution replaced 9.19%, 14.27%, 29.07%, 38.45% of mineral lost after 1, 3, 5, 10 days respectively (y = 8.9316 x0.6347, R2 = 0.9322; y: remineralizing rate, x: time). Significant differences were found in remineralizing rate between any two groups using One-way Scheffe multiple comparison. CONCLUSIONS: The 2% CPP-ACFP solution could significantly remineralize the artificial enamel subsurface lesion in vitro. The remineralizing rates were increased with the experiment time (within 10 days).

Caseins↗

PubMed2002

[Effect of sodium chloride treatment on remineralization of human root dentine caries in vitro].

OBJECTIVE: To investigate the influence of soluble phosphoprotein removal from artificial dentin caries lesions by pretreatment of NaCl on subsequent remineralization. METHODS: Human root dentin samples were demineralized in an acidic gel (pH = 4.4) at 37 degrees C for 48 hours. Samples were pretreated with 0.5 mol/L NaCl solution and 0.5 mol/L disodium EDTA solution respectively. The histomorphologic changes of root caries surface were examined by scannings electronic microscope. Mineral profiles were assessed by means of microradiography. RESULTS: No histomorphologic changes were present on root caries surface after treated with 0.5 mol/L NaCl solution, while many opened dentin tubules were seen after treated with 0.5 mol/L disodium EDTA solution. The remineralization results showed that pretreatment with 0.5 mol/L NaCl solution increased more remineralization than pretreated with 0.5 mol/L disodium EDTA solution. CONCLUSION: 0.5 mol/L NaCl solution has no damage on the root caries surface. The in vitro results suggested that removal of soluble phosphoprotein from dentin lesions is an interesting approach to enhance remineralization.

Dental Caries↗

PubMedDate not supplied

The effect of a doxorubicin, cisplatin and ifosfamide combination chemotherapy on bone turnover.

BACKGROUND: Use of combination adjuvant chemotherapies have improved the disease-free survival rate of tumor patients significantly. Previous experimental studies have shown that chemotherapeutic agents have negative effects on fixation of porous coated prosthesis, but the effects on normal bone turnover rate and mechanicalproperties have been reported to be minimal. MATERIALS AND METHODS: Fourteen dogs were used to study the effect of a doxorubicin, cisplatin and ifosfamide combination in normal bone turnover. We developed a safe and clinically-relevant canine model for multidrug perioperative chemotherapy that simulates current cancer treatment. The bone specimens were analyzed using microradiography, bone histomorphometry and torsional testing. The results were compared with canines that underwent a similar surgical protocol without chemotherapy. RESULTS: The results showed no differences in mechanical properties after 22 weeks of chemotherapy. The porosity, osteonal activity and mineral apposition rate of the cortical bone were unaffected. The results also showed no difference in porosity of perimeter in cancellous bone, but the mineral apposition rate was significantly reduced. CONCLUSION: The difference in mineral appostion rate of cancellous bone shows that, although the effect of temporary chemotherapy on bone may have minor effects on normal turnover and that the effect may be reversible, it causes disturbance in bone mass accumulation. This may later raise the risk for fragility fractures and osteoporosis.

Animals↗

PubMed2003

[Patellar reconstruction during total knee arthroplasty after previous patellectomy].

PURPOSE OF THE STUDY: In order to limit the consequences of prior total patellectomy on knee function after total knee arthroplasty, we propose an original technique using an en bloc patellar graft to reconstruct the quadriceps lever arm. The purpose of this work was to describe the technique and present preliminary results obtained in seven patients. PATIENTS AND METHODS: Seven en bloc patellar grafts were performed in seven patients (6 women and 1 man) during total knee arthroplasty procedures for femorotibial degenerative joint disease after prior patellectectomy (mean 13 years before arthroplasty, range 5-20 years). We implanted three posterior stabilized prostheses, one ultracongruent prosthesis, two prostheses preserving the posterior cruciate ligament, and one bi-cruciate prosthesis. The patella was reconstructed with an autologous bone graft fashioned from the tibial plateau in six cases, and with a homologous graft fashioned from a bone-bank femoral head in one. Transosseous sutures were used to fix the graft to the extensor system. A polyethylene button was cemented on five of the grafts. RESULTS: Active extension was defective in five knees prior to the patellar graft and in only one knee after patellar reconstruction. The IKS knee score improved from 41 points (range 35-45) before surgery to 78 points (range 55-95) after grafting and the IKS function score from 35 (range 5-50) to 72 (range 40-100). Four of the seven grafts were removed (eight weeks to five years after implantation, mean two years) mainly due to failure of fixation leading to progressive migration. Follow-up varied from eight weeks to six years. Mean follow-up for the three grafts still in place was 4.6 years (4-6 years). After removing the patellar graft (4 knees) the IKS knee score decreased to 68 points (20-95) and the IKS function score to 62 points (30-100). Lack of active extension reappeared in three of the knees after removing the patellar graft but was not observed in the three knees with the patellar graft in place (and flexion was at least 110 degrees ). Microradiography of the patellar graft explanted after two years revealed peripheral corticalization with areas of living bone tissue seen on the pathology specimens. Inversely, the autografts explanted at eight weeks and at five years exhibited bone necrosis. CONCLUSION: This preliminary study shows that patellar autograft can improve the performance of total knee arthroplasty on patellectomized knees. The fixation technique must be improved using transosseous transverse sutures in addition to peripheral sutures in order to limit secondary migration of the graft. A patellar autograft fixed into the extensor system can remain viable two years after implantation. This technique can be proposed when total knee arthroplasty is indicated for a patellectomized knee, particularly in patients with lack of active extension.

Adult↗

PubMed2003

Acceleration of callus maturation using rhOP-1 in mandibular distraction osteogenesis in a rat model.

The aim of this study was to assess if the application of rhOP-1 induces accelerated consolidation of the callus in mandibular distraction osteogenesis. In seven adult Wistar rats a bilateral osteotomy of the horizontal ramus of the mandible was performed in the molar region and a custom designed distractor was mounted to the mandible. With a rate of 0.7 mm per day the device was activated bilaterally after the seventh postoperative day. After seven days of distraction two times 50 microg rhOP-1 were injected on two subsequent days directly into the callus. The contralateral side received an injection of placebo solution. The animals were killed four weeks after the end of distraction. A three-point bending test revealed a significantly higher strength of the distracted mandible in the rhOP-1 side (66.3 N vs. 30.4 N, P=0.034, paired t-test). Undecalcified histological sections were examined using microradiography and fluorescence microscopy after sequential intravital polychromic labelling. A continuous bony bridging was seen in all rhOP-1 sites and in none of the control sites. The data indicate that rhOP-1 may be an option to accelerate callus maturation in mandibular distraction osteogenesis.

Animals↗

PubMed1993

[The characters on histopathological changes in dental fluorosis]

The microradiography SEM and TEM were used ton observe histopathological changes in dental fluorasis with various degrees in this study.The characters of histopathological changes of dental fluorasis are:(1) the lesios appear in exterior layer of enamel,not excess one third enamel.(2)the future of the lesion is enamel-hypoplasia,enamel rods were hypomineralized.the space among enamel rods widen and form some cavities.There are a lot of spaces in intercrystlines.Many micropores and injures exhibit on enamel surface.(3)the clinic severe degree of lesion is similar to the histopathological changes.It could be indicated using the Dean's and the TF index.

Journal Article↗

PubMed1992

The effect of an experimental mouthrinse on enamel lesion remineralization in vitro.

This paper describes the effect of a 2 ppm fluoride containing, slightly acidic mouthrinse (pH = 6) on the remineralization of enamel lesions in vitro. The rinse was applied twice daily for 2 min, on about 85 microns in depth artificial lesions. Artificial enamel lesions were formed at pH = 5 in a 6% CMC gel. The lesions were subsequently remineralized in vitro in a neutral remineralizing solution (1.5 mM Ca and 0.9 mM phosphate) with or without the application of the rinse. After 3 weeks the samples were evaluated by means of quantitative microradiography. The results showed that a statistically significant reduction in lesion depth occurred of 48 and 29% with or without rinse application, with respect to the original lesion depth. The effect of the rinse compared with no rinse decreased the lesion depth by 40%. The data indicate that application of a slightly acidic rinse with 2 ppm fluoride applied twice a day, stimulates the remineralization at the lesion front and does not lead to blocking of enamel pores observed after acidic, high level F applications (APF).

Animals↗

PubMedDate not supplied

Osteorticular amyloidosis in a patient under dialysis treated by total hip arthroplasty: case report and review of the literature.

The authors present the case of a patient affected by kidney failure, who had been undergoing dialysis for several years when areas of osteolysis and bone resorption in the proximal femur and pathologic fracture appeared. She was treated surgically by hybrid total hip arthroplasty. The patient also complained of pains in other joints. The bone tissue taken from the osteolytic area was examined histologically. The test showed the presence of an amyloid substance. Microradiography and X-ray diffractometry carried out on the same samples confirmed the lack of mineralisation due to the presence of aluminum ions, presumably derived from dialysis. The high concentration of this element was confirmed by resum assay with spectrophometry in atomic absorption. Considering the results of the aforementioned tests, the patient was put on dialysis using a polymethylmethacrylate filter.

Amyloidosis↗

PubMed1992

Enhancement of bone bonding to bioactive ceramics by demineralized bone powder.

In an attempt to enhance the bonding of bone to bioactive ceramics, allogeneic demineralized bone powder (DBP) was used in combination with bioactive ceramic implants in rabbit tibiae. Rectangular plates (10 x 15 x 2 mm) made of apatite-wollastonite-containing glass ceramics were implanted in the proximal metaphyses of the bilateral tibiae of 20 rabbits, with DBP packed into the medullary cavity. In the control group, only the plates of A-W GC were implanted in the bilateral tibiae of 20 rabbits. Four rabbits from each group were killed at two, four, eight, 12, and 25 weeks after implantation for the tensile test. Results of the tensile test and histologic examination of the undecalcified specimens by Giemsa surface stain and contact microradiography confirmed that DBP significantly accelerated the process of bone bonding to the implant and increased the strength of bone-implant bonding.

Animals↗

PubMed2005

[Can bone quality be assessed non-invasively?--Imaging--].

Properties of "bone quality" contain "structural property" and "material property" . Most components of "material properties" cannot be visualized by current technology. Mineralization, one of material properties, can be evaluated using synchrotron radiation CT or contact microradiography with high spatial and density resolution, but they are invasive examinations. On the other hand, "structural property" can be radiographically delineated, even though only a few methods are available non-invasively. Assessments of macrostructure of bone by radiograms or CT, and trabecular microstructure by high resolution CT or MR can be done non-invasively, and provide valuable results in clinical studies. Bone scintigram provides limited but useful information of bone turnover.

Bone and Bones↗

PubMed1992

New aspects of the degeneration of bioprosthetic heart valves after long-term implantation.

Bioprosthetic heart valves removed 76 to 150 months after implantation were morphologically investigated to correlate structural alterations with clinical failure modes. Traditional morphologic methods of evaluating valvular heterografts, such as microradiography and electron microscopy, were complemented by undecalcified ground sections, a new technique for analyzing the distribution of mineral deposits. Apart from well-investigated mechanisms that accelerate tissue degeneration, our observations point to additional facts: (1) phagocytosis of collagen fibrils and elastic material by macrophages and foreign body giant cells in areas near tears and perforations and (2) initial calcification indicated by delicate crystals in the intercellular space arranged in close relation to the periodicity of the cross-striation pattern of collagen fibrils. The present report not only calls attention to degenerative changes that are enhanced by mechanical stress but also underlines phagocytosis as an important mechanism in the destruction of bioprosthetic heart valves.

Bioprosthesis↗

PubMed2005

In vitro model for evaluating the effect of child formula toothpastes on artificial caries in primary dentition enamel.

PURPOSE: To determine if the in vitro 10-day pH-cycling model used for permanent teeth could be utilized to evaluate de/remineralization effects, on the enamel of primary teeth, of child formula toothpastes. METHODS: Sound extracted primary anterior teeth were coated with nail varnish, leaving a 1 mm-wide window prior to being placed in a demineralizing solution to produce artificial carious lesions in enamel. The teeth were subsequently cut longitudinally into 100 microm thick sections. The 72 specimens were randomly assigned to six groups. In Set 1 contained the specimens in Group a, which were treated with a pea-sized (0.32 g) quantity of non-fluoride toothpaste (First Teeth), and Groups b and c which were treated with half and pea-sized (0.16 g) quantities of fluoridated toothpaste (Colgate), and cycled for 10 days. The specimens in Set 2 (Groups A, B and C) were similarly treated but subjected to 7-day pH-cycling. RESULTS: After Day 8 the lesions in Set 1 extended into dentin and so could not be evaluated. Polarized light microscopy and microradiography were used to evaluate the lesions subjected to 7-day pH-cycling. Lesions in Groups A and B increased in depth and area by approximately 50%, while those in Group C increased in depth and area by 20%; however, no statistically significant differences occurred between the groups. If this model pH cycling is to be used for primary teeth, a reduction from 10 to 7 days in length should be considered.

Cariostatic Agents↗

PubMed2006

[Dentin demineralization in situ during frequent exposures to bananas or sucrose].

The aim of the study was to compare sucrose solution and bananas on demineralizing potential in situ, and to address the question if fluoride toothpaste is equally effective in preventing dentin demineralization at open, smooth surfaces and at plaque stagnation sites (grooves). Four volunteers wore an appliance containing bovine dentin specimens with narrow grooves and a smooth surface for two 1-week in situ periods, with 8 1-minute exposures daily: either by a rinse with 10% sucrose, or by consumption of a piece of banana. Twice daily, the appliance was dipped in toothpaste slurry of a fluoride-free toothpaste at one side and a fluoride toothpaste at the contralateral side. Demineralization was assessed by tranversal microradiography. No difference in dentin demineralization was found after frequent exposure to either sucrose solution or bananas. Fluoride toothpaste effectively protected dentin only at the smooth surfaces. In the grooves, fluoride affected the demineralization pattern; it drove lesions towards the bottom of the groove.

Cariogenic Agents↗

PubMed1991

[Sandblaster or alumina-coated 316 L stainless steel for implantable material in orthopedic surgery. Study on metacarpal bone of sheep].

We have carried out a study in sheep of the behavior of bone in the presence of two materials, 316 L stainless steel with a surface roughened by sandblasting, and the same type of steel, plasma-coated with alumina. Twelve nails of each type were implanted into the medullary cavities of previously fractured metacarpal bones. The samples were removed after 90 days for six animals and after 180 days for six others. The functional study and the radiographic analysis, as well as the growth of bone around the implants as assessed with a light microscope and with microradiography, did not show any significant difference between both types of temporary implants.

Aluminum Oxide↗

PubMed1991

Physico-chemical and morphological studies of horse dentin.

The well-developed thick peritubular matrix (PM) in the middle layer of horse dentin was physico-chemically and also morphologically compared with the intertubular matrix (IM) and the enamel using several microscopes. In scanning laser microscopy, the PM showed a higher laser-beam reflection than the IM, and the contrast image was similar to that of the backscattered electrons by SEM, but to be lower than that of X-ray opacity in microradiography. By SEM-EDX, Ca, P, and Mg were detected from the PM and IM. The mineral content of the PM composed of 15-20 nm sandygrain-shaped crystallites under SEM was significantly higher than that of the IM, but lower than the enamel. The PM/IM in each Ca and P content by weight showed a low average of 1.11, which corresponded to that of their specific gravities previously reported. In Vickers hardness tests, the PM was significantly harder than the IM but softer than the enamel. The PM/IM in the microhardness number showed a high average of 1.85.

Animals↗

PubMed1991

Microscopic and chemical examinations for estimating the time since death of skeletal remains--its application to forensic cases.

Postmortem changes in human compact bones were examined by microradiography and electron microscopy, simultaneously with an examination of UV-fluorescence in the cross-section of bones by microscopic spectrophotometry. Total protein content in bones were also examined. No significant morphological changes were found in compact bones exposed to the open air for less than 10 years since death. In bones buried in the soil, vacuolation of bone tissues generally began around 5 years since death. This histological changes extended into the mid zone of the substantia compacta in bones of 6 years or more. In bones left in the sea for 4 or 5 years, vacuoles with 5-10 microns in diameter were observed in the outer peripheral zone of the substantia compacta. The relative intensity of UV-fluorescence in the peripheral zone of the substantia compacta dwindled with time since death and their correlation coefficient was considerably high. Although the correlation coefficient of protein content with time since death of bones was significant, it was too low for forensic science application. These microscopic methods were applied to the estimation of bone date in 5 actual criminal cases and the reliability of the determination of time since death based on the present data were evaluated. The results obtained provided good estimations of the bone date.

Bone and Bones↗

PubMed1991

The effect of an antimicrobial releasing varnish on root demineralisation in situ. The influence of the demineralisation period.

Caries in exposed root surfaces is becoming a significant problem in dentistry. Varnish applications have interesting preventive possibilities against root caries. The effect of such a varnish, containing two antimicrobials, was studied on the demineralisation of roots with a twofold aim. Firstly, the efficacy of the varnish was investigated in situ as a function of the demineralisation period. Ten participants wore sound intact roots treated with the varnish in an intra oral appliance for 2, 4 and 6 weeks. Secondly, the effect of the varnish on root demineralisation after removal of the varnish was measured. The results showed that the reduction, in demineralization of about 80% after 2 weeks, decreased in magnitude with the length of the in situ demineralisation period. After 4 weeks there was no longer statistically significant difference compared with untreated roots. The acid attack by plaque was, however, substantial in this model; after 6 weeks in situ untreated roots were so strongly demineralised that microradiography was no longer possible anymore. In the second experiment in which the varnish was removed 2 days after application there was a trend toward a reduction of about 30% in root demineralisation after 2 weeks. This was not statistically significant when compared with no application.

Adult↗