[Effect of boron and fluoride on the expression of enamelin in rat incisor]

OBJECTIVE

To investigate the effects of overdose fluoride, boron and two factors on the expression of enamelin in rat incisor.

METHODS

32 Wistar rats were randomly divided into 4 groups. Group I: The distilled water was given. Group II: 220 mg/L NaF were given. Group III: 382 mg/L Na2B4O2.10H2O were given. Group IV: 220 mg/L NaF and 382 mg/L Na2B4O2.10H2O were given. The rats were sacrificed in the eighth week. HE staining was used to observe the morphology of ameloblasts. Immunohistochemical staining was used for study the expression of enamelin in rat incisors.

RESULTS

The results showed that the expression of enamelin was reduced in the group II (P<0.01). Compared with group I, the expression of enamelin in group IV had no significant difference. The expression of enamelin in group IV and group II had significant difference (P<0.01).

CONCLUSION

The overdose fluoride can inhibit the expression of enamelin. The effection was weaken when boron added. Boron reduced the toxicity of fluoride on teeth.

Root coverage with Emdogain/AlloDerm: a new way to treat gingival recessions

The recession of the gingival margin is becoming a more prominent condition in the oral situation of many patients and should be treated at its earliest detection. The multifactorial etiology, decision modality, and current trends in the treatment of gingival recession are discussed in this article. The surgical technique of choice depends on several factors, but among the different surgical protocols available, the clinician should select one that will minimize surgical trauma and achieve predictable esthetic results. All of the approaches described in this article can effectively treat deep and shallow Class I or II buccal recessions. Recently, as an alternative to autogenous gingival grafts in root coverage procedures, enamel matrix derivative (Emdogain) and acellular dermal matrix allograft (AlloDerm) were utilized to correct these gingival defects, negating the morbidity and the requirement for a second palatal surgical procedure. Emdogain or AlloDerm materials used alone or in combination are a predictable treatment for root coverage, are relatively easy to perform (although they are technique sensitive), present low patient morbidity, offer a significant increase in the percentage of root coverage and amount of keratinized tissue, and should be part of the periodontal plastic surgery armamentarium.

[Exclusion of candidate genes in a family with amelogenesis imperfecta]

OBJECTIVE

To localize the gene (s) responsible for autosomal dominant hypocalcified amelogenesis imperfecta in a Chinese family.

METHODS

A Chinese family which was diagnosed as autosomal dominant hypocalcified amelogenesis imperfecta (AD) was studied. Venous blood from nineteen family members was collected and genomic DNA was extracted from the blood. Eight short tandem repeats (STRs) spanning five hereditary AI candidate genes were selected and linkage analysis between the genetic markers and the disease loci was performed.

RESULTS

Genotype of the eight STRs were acquired, the linkage analysis result can not support that the gene for AI pedigrees was linked to ENAM, AMBN, TUF1, KLK4 or MMP-20.

CONCLUSION

The results can not support all proposed candidate gene regions as causal for autosomal dominant hypocalcified AI in this family. These linkage findings provide further evidence for genetic heterogeneity among families with autosomal dominant AI and indicate that, at least, some forms of autosomal dominant AI are not caused by a gene in the five most commonly reported AI candidate genes.

[Effects of EMPs on growth and attachment of human BMSCs]

PURPOSE

The present study is to evaluate the effects of enamel matrix proteins(EMPs) on the attachment, spreading and proliferation of human bone marrow stromal cells(hBMSCs) in vitro.

METHODS

Human BMSCs were obtained from human bone marrow aspiration and cultured in DMEM medium with 10% fetal bovine serum (FBS). EMPs was added into medium in several concentrations (50,100, 200, 300 microg/ml) as experimental groups. BMSCs were cultured without EMPs as control group. Attachment ability of hBMSCs was detected by counting cell number. Cell spreading rates were performed at various culture times by analysis of micrographs taken at predetermined sites of each wells. Cell proliferation rates were assessed by MTT assay. Data was statistically analyzed with SAS6.12 software for one-way ANOVA.

RESULTS

It was shown that BMSCs were cultured successfully in vitro. There was no significant change between the control group and experimental groups in cell attachment and cell spreading rate. However, the proliferation of BMSCs was significantly stimulated by EMPs in a dose- and time-dependent manner. EMPs at a concentration of 200 microg/ml significantly enhanced BMSCs proliferation (P < 0.05).

CONCLUSION

EMPs could promote the proliferating ability of human BMSCs, but have no effects on its attachment and spreading.Supported by National "863" Project (Grant No. 2002AA205013), Shanghai Municipal Education Development Fund(Grant No.2002-02) and Research Fund of Science and Technology Committee of Shanghai Municipality (Grant No.04dz05601).

[Effect of overdose fluoride on the expression of enamelin in rat mandibular incisor]

OBJECTIVE

To observe the effect of overdose fluoride on the expression of enamelin in rat mandibular incisor.

METHODS

Twenty Wistar rats were divided randomly into two groups. Animals were maintained in standard environment with free access to food and distilled water (control group) or water added with 100 mg/L F-(experimental group). The rats were killed in the eighth week. HE staining was used to observe the morphology of ameloblasts. Immunohistochemical staining was adopted to study the expressions of enamelin in rat incisor.

RESULTS

The ameloblasts of the treated rat were arranged in multi-layer. The ameloblasts in group II were thinner than those in group I. The structure of enamel matrix was in disorder. The expressions of enamelin in ameloblasts and odontoblasts were obviously inhibited in group II (P < 0.01).

CONCLUSION

The overdose fluoride inhibits the secretion of enamelin and leads to the abnormal development of enamel matrix.

[Preparation of enamel matrix proteins controlled release microspheres and their biological effects on the proliferation and differentiation of human periodontal ligament cells in vitro]

OBJECTIVE

To prepare enamel matrix proteins (EMPs) loaded dextran-based hydrogel microspheres (EMPs-dex-MPs), and to evaluate their EMPs controlled release property and their biological effects on the proliferation and differentiation of human periodontal ligament cells (PDLCs) in vitro.

METHODS

Using dimethylbenzene as the oil phase, EMPs-dex-MPs were achieved by emulsion-chemical crosslinking technique. The process of the recombination preparation was optimized by orthogonal factorization method. The configuration and size of EMPs-dex-MPs were determined by scanning electron microscope. The EMPs loading content and encapsulation rate of EMPs-dex-MPs, and their biodegradation characteristic were studied by routine analysis methods. Dynamic dialysis method was used to determine the release characteristic of EMPs-dex-MPs in vitro and its influencing factors. The proliferation of cultured PDLCs was measured by MTF method and the differentiation of PDLCs was measured by their alkaline phosphatase (ALP) activities.

RESULTS

The results showed that EMPs-dex-MPs were homogenous and stable with the average diameter 25 microm, and the EMPs loading content was (32.8 +/- 1.2)%, the encapsulation rate was (78.9 +/- 1.0)%. Under 9% physiological saline solution contained a very thimbleful quantity of dextranase EMPs-dex-MPs could be biodegraded completely during about 40 days. The in vitro experiments showed that about 80% of EMPs could be released out in 20 days. Using EMPs-dex-MPs could enhance the proliferation responses and ALP activities of PDLCs more than 12 days.

CONCLUSION

As a new sustained release system of growth factors, the dex-MPs is stable, workable and biodegradable. EMPs-dex-MPs, whose drug release can be controlled by preparation technique, may be more effective in promoting periodontal tissue regeneration.

Effect of GBR in combination with deproteinized bovine bone mineral and/or enamel matrix proteins on the healing of critical-size defects

OBJECTIVES

To evaluate the effect of guided bone regeneration (GBR) in combination with or without deproteinized bovine bone mineral (DBBM) and/or an enamel matrix derivative (EMD) on the healing of critical-size calvarial defects.

MATERIAL AND METHODS

Forty rats were used. In all animals, a standardized critical-size calvarial defect was created surgically. The animals were randomly allocated into 4 groups of 10 animals each. Group A: One calvarial defect was left untreated, while the galeal and the cerebral aspect of the contralateral defect were covered with a bioresorbable membrane (GBR). Group B: One calvarial defect was filled with EMD, while the contralateral defect was treated with GBR and EMD. Group C: One defect was filled with DBBM, while the contralateral defect was treated with combination of GBR and DBBM. Group D: One defect was filled with DBBM combined with EMD, while the contralateral defect was treated with combination of GBR, DBBM and EMD. The healing period was 4 months. Five specimens from each group were macerated and the length, the width and the vertical dimension (thickness) of the remaining defect were evaluated by a stereomicroscope. The remaining specimens in each group were analyzed histologically.

RESULTS

The defects of the macerated specimens that were left untreated or were treated only by EMD, DBBM and combination of EMD and DBBM did not present predictably complete healing of the defects. All the defects where GBR was applied alone or combined with DBBM and/or EMD presented always complete healing (P<0.05). The combined use of GBR with EMD and/or DBBM did not offer any significant advantage above GBR alone in terms of healing of the length and the width of the defect. However, the vertical dimension of the defect was significantly higher (P<0.05) in the GBR-treated specimens of Groups C and D. The histological analysis supported these findings.

CONCLUSION

The predictability of bone formation in critical-size defects depends mainly on the presence or absence of barrier membranes (GBR). The combined use with deproteinized bovine bone mineral and/or enamel matrix proteins did not significantly enhance the potential for complete healing provided by the GBR procedure.

[Clinical comparison between guided tissue regeneration and induced tissue regeneration]

AIM

The aim of the present study was to evaluate, over a period of 1 y, 3 different surgical methods for the treatment of periodontal bone defects.

METHODS

Thirty-six infrabone defects, at least 4 mm in depth, in non-smokers were enrolled in the study. Of these, 12 were treated with guided tissue regeneration (GTR) using a resorbable membrane with collagen, 12 with enamel matrix derivative (EMD) gel and 12 with a modified Widman flap (MWF). The pocket depth, attachment loss and gingival recession both before commencement of therapy and after an interval of 1 y are reported.

RESULTS

The reduction in pocket depth was 4 mm, 4.4 mm, and 4.5 mm, respectively, for the control group, GTR group and EMD group. The attachment gain for the respective treatments was: MWF, 2 mm; GTR, 2.8 mm; EMD, 2.9 mm. Gingival recession was: MWF, 1.8 mm; GTR, 1.5 mm; EMD, 1.1 mm.

CONCLUSION

These findings show the efficacy of the 3 methods in the treatment of bone defects, but none of the 3 emerges as being statistically superior to the others 2.

Porcine enamel matrix derivative enhances the formation of reparative dentine and dentine bridges during wound healing of amputated rat molars

We examined the biological effects of porcine enamel matrix derivative (EMD; Emdogain) on the formation of reparative dentine and dentine bridges in rat molars after pulp amputation. The pulp chambers of upper molars of Wistar rats were perforated and the amputated pulp surfaces were directly capped with either EMD or its carrier propylene glycol alginate (PGA) as control. The cavities were then restored with glass-ionomer cement. On post-amputation days 4-30, the dissected maxillae were examined by light and electron microscopy. In PGA-capped pulp, reparative dentine had been formed over the dentine walls under the prepared cavity on day 7 post-amputation and its thickness extended until day 30. On day 30, as well as reparative dentine formation, diffuse calcification had occurred beneath the amputated wound surfaces. Dentine bridge formation under the amputated coronal pulp surface was observed in 18.2% of amputated pulp on day 30. In EMD-capped pulp, reparative dentine had already been formed by odontoblast-like cells over the dentine walls, already on day 4 post-amputation, and its thickness extended until day 30. The Ca and P weight % and Ca/P ratio of reparative dentine matrix were similar to those of pre-existing dentine matrix, and these values were not different between PGA and EMD-capped pulp. Dentine bridge formation was observed in 27.3% of EMD-capped pulp on day 30. Our results suggest that EMD enhances the formation of both reparative dentine and dentine bridges during wound healing of amputated rat molar pulp.

Evaluation of PCR-based beef sexing methods

Analysis of the sex of beef meat by fast and reliable molecular methods is an important measure to ensure correct allocation of export refunds, which are considerably higher for male beef meat. Two PCR-based beef sexing methods have been optimized and evaluated. The amelogenin-type method revealed excellent accuracy and robustness, whereas the bovine satellite/Y-chromosome duplex PCR procedure showed more ambiguous results. In addition, an interlaboratory comparison was organized to evaluate currently applied PCR-based sexing methods in European customs laboratories. From a total of 375 samples sent out, only 1 false result was reported (female identified as male). However, differences in the performances of the applied methods became apparent. The collected data contribute to specify technical requirements for a common European beef sexing methodology based on PCR.

Clinical evaluation of an enamel matrix protein derivative (Emdogain) combined with a bovine-derived xenograft (Bio-Oss) for the treatment of intrabony periodontal defects in humans

The purpose of the present study was to compare the treatment of deep intrabony defects with a combination of an enamel matrix protein derivative (EMD; Emdogain) and a bovine-derived xenograft (BDX; Bio-Oss) to BDX alone. Twenty-four healthy patients, each of whom displayed one intrabony defect, were randomly treated with a combination of EMD + BDX (test) or with BDX alone (control). Soft tissue measurements were made at baseline and 1 year following the therapy No differences in any of the investigated parameters were observed at baseline between the two groups. No adverse healing response was observed in any of the patients. At 1 year after therapy, the sites treated with EMD + BDX showed a reduction in probing pocket depth (PPD) from 10.0 +/- 1.5 mm to 4.3 +/- 1.4 mm and a change in clinical attachment level (CAL) from 10.9 +/- 2.0 mm to 6.2 +/- 1.9 mm (P <.0001). In the group treated with BDX, the PPD was reduced from 9.7 +/- 2.4 mm to 3.2 +/- 0.7 mm and the CAL changed from 10.1 +/- 2.3 mm to 5.2 +/- 1.2 mm (P <.0001). Hard tissue fill was observed radiographically in all defects. Both treatments resulted in significant improvements of PPD and CAL. However, no statistically significant differences in any of the investigated parameters were observed between the test and control groups. Both therapies led to significant improvements of the investigated clinical parameters.

Y-STR DNA amplification as biological evidence in sexually assaulted female victims with no cytological detection of spermatozoa

Identification of spermatozoa is the biological evidence most often sought in specimens from rape victims. Absence of spermatozoa usually terminates biological investigations, and the victim's testimony can be contested. We assessed the utility and reliability of PCR amplification using Y-chromosomal STR polymorphisms in specimens from female victims of sexual assault with negative cytology. One hundred and four swabs without spermatozoa detected by cytology were collected from 79 alleged sexually assaulted female victims and amplification of Y-STR and of amelogenin was performed.Overall, Y-chromosome was detected and evidenced sexual penetration in 28.8% of swabs. In the population of victims examined more than 48 h after the sexual assault, Y-STR were still evidenced in 30% of the cases. These results show that swabs should be taken from victims for Y-chromosome DNA typing even after long delays between sexual assault and medical examination.

Identifying sex chromosome abnormalities in forensic DNA testing using amelogenin and sex chromosome short tandem repeats

Forensic DNA laboratories worldwide have begun using multiplexed STR systems to decrease analysis time and increase sample throughput. The loci used in these systems are basically "nonsense" regions of human DNA. However, due to the chromosome on which some of these loci are located, various genetic abnormalities can sometimes be detected. This paper will show one such abnormality--Klinefelter's Syndrome--and the process used to show the possibility of this defect in two undiagnosed males using peak height ratios at the Amelogenin locus, and X-Y STRs.

Surgical technique for treatment of infrabony defects with enamel matrix derivative (Emdogain): 3 case reports

A surgical protocol is described for the placement of Emdogain enamel matrix derivative during new attachment procedures. Three cases with infrabony defects were treated and a significant probing attachment level (PAL) gain, probing depth reduction, and bone fill were evident on clinical probing and during reentry procedures. The first patient presented a combined one-walled and circumferential defect at a maxillary central incisor. After 1 year the PAL gain was 7 mm. The second case showed a 3-walled defect distal to a maxillary canine. After 1 year the PAL gain was 8 mm, and a reentry procedure showed an almost total fill of the defect. The third patient presented a combined one- and 3-walled defect in the most apical part of the mesial aspect of a maxillary central incisor. One year after the surgical procedure, an orthodontic treatment was performed in this patient. After 6 more months the soft tissue showed a very good esthetic appearance, the papilla height was fully maintained, and there was a PAL gain of 5 mm; 18 months after surgery, reentry showed a significant regeneration of hard tissue that was impossible to probe. Because of these encouraging clinical results, further studies should be initiated to investigate the efficacy of the enamel matrix derivative in new attachment procedures.

Treatment of intrabony periodontal defects with an enamel matrix protein derivative (Emdogain): a report of 32 cases

Enamel matrix proteins, including Emdogain, have been proposed as a new modality for regenerative periodontal treatment. However, limited information is available concerning the clinical applicability and therapeutic results with Emdogain. The aim of the present study was therefore to evaluate the clinical outcome following the application of Emdogain in the treatment of intrabony periodontal defects. Twenty-eight patients with marginal periodontitis (thirty-two 2- and 3-walled intrabony defects) were included in this study. The following parameters were evaluated prior to treatment and 8 months after treatment: probing pocket depth, recession of the gingival margin, and clinical attachment level. The postoperative healing phase was uneventful in all cases. There were no complications such as allergic reactions, abscess formation, or infections throughout the entire study period. The mean probing pocket depth was reduced from 8.7 +/- 1.5 mm at baseline to 4.3 +/- 1.6 mm after 8 months (P < 0.001), the mean gingival recession increased from 1.8 +/- 1.2 mm to 3.3 +/- 0.9 mm, and the mean clinical attachment level changed from 10.6 +/- 1.9 mm to 7.6 +/- 1.8 mm (P < 0.001). New hard tissue formation was radiographically observed in 26 of the 32 defects. The present results suggest that the treatment of intrabony periodontal defects with Emdogain may lead to significant improvements of all of the investigated clinical parameters. However, controlled histologic and clinical trials are needed to compare this treatment modality with other conventional and regenerative periodontal surgical methods.

Enamel matrix derivative for periodontal reconstructive surgery: technique and clinical and histologic case report

This paper describes a step-by-step technique for the application of Emdogain, a new enamel matrix derivative (EMD) graft material, for periodontal reconstructive surgery. A case report is presented with a 1-year follow-up. The rationale for use and advantages and disadvantages of EMD are discussed. An additional human histologic case report demonstrates that the formation of new bone, cementum, and periodontal ligament is possible following the use of EMD.

DYS19 and amelogenin in artificial blood stains with defined amounts of male and female cells

The sensitivity of the DYS19 and the amelogenin STR systems for amplifying Y-specific fragments was assayed using artificial bloodstains with varying amounts of male and female (non-template) DNA in different ratios. The study confirmed the high sensitivity of both systems in detecting male-specific PCR fragments in stains containing 10-25 template molecules even in the presence of large amounts of female DNA in the mixture by silver-stain detection. However, blood mixtures which contain less than 10% male cells could be reliably typed only when at least 100 template molecules were present in the artificial bloodstain, due to increasing amounts of hemoglobin from the female blood which is a PCR inhibitor.

Ancient DNA in human bone remains from Pompeii archaeological site

aDNA extraction and amplification procedures have been optimized for Pompeian human bone remains whose diagenesis has been determined by histological analysis. Single copy genes amplification (X and Y amelogenin loci and Y specific alphoid repeat sequences) have been performed and compared with anthropometric data on sexing.

Studies on the changes in developing enamel caused by ingestion of high levels of fluoride in the rat

Exposure to chronic high levels of fluoride results in the formation of fluorosed enamel. Although enamel may be more susceptible to fluorotic effects at certain stages of development, fluoride at sufficiently high levels may affect enamel at all stages of formation. Careful study of the changes in enamel caused by chronic fluoride ingestion is needed to understand more fully the mechanisms involved in the formation of fluorotic enamel. This paper discusses the various studies we have completed to define the changes, in developing enamel of the rat incisor, caused by long-term ingestion of fluoride in drinking water. Fluoride has been found to inhibit secretion of enamel proteins. Changes in the maturation stage of enamel formation include the retention of amelogenin proteins during early maturation. The various mechanisms which have been investigated in the formation of fluorosed enamel include a direct effect of fluoride on the enamel organ, and specific interactions of fluoride with the extracellular enamel matrix. Although the same amount of protease appears to be secreted in fluorosed and control enamel, a delay in the digestion of amelogenin protein occurs. This suggests that fluoride may directly or indirectly inhibit the protease present in fluorosed enamel to slow the proteolysis of amelogenins.

Selective adsorption of porcine-amelogenins onto hydroxyapatite and their inhibitory activity on hydroxyapatite growth in supersaturated solutions

The selective adsorption of amelogenins onto synthetic hydroxyapatite (HA) and their inhibitory activity on the seeded HA crystal growth were investigated using enamel proteins obtained from the outer layer of immature porcine-enamel (soft, cheeselike in consistency) of developing permanent incisors. Special interests were paid to the effect of a postsecretory degradation of the original amelogenin(s) on their adsorption and inhibitory activity. In the adsorption studies, it was apparent that the originally secreted amelogenin (25 K), proline, and histidine-rich protein (2a), as well as the higher molecular weight components (60-90 K), showed a strong adsorption affinity onto the HA. This adsorption of protein 2a was related to its inhibition of the crystal growth of seeded HA in a dilute supersaturated solution. On the other hand, the partially degraded product (20 K) of amelogenins, protein 2b, lost the high adsorption affinity onto the HA, and consequently showed no significant inhibitory activity. The observed selective adsorption of protein 2a onto HA was apparent at pH 6.0 and pH 7.4 even in the presence of dissociative solvents, such as 3 M urea or 2 and 4 M guanidine-HCl; however, this selective behavior was sensitive to changes in pH, and was not displayed at pH values of 7.8 or 10.8. The results suggest that the originally secreted amelogenin 2a may play an active role in amelogenesis, and that enamel mineralization could be regulated by the secretion of amelogenins and their inactivation through partial enzymic degradation, prior to their complete removal.

Studies of the secondary structures of amelogenin from bovine tooth enamel

Circular dichroism and Fourier transform infrared spectroscopic studies of the major amelogenin protein of developing bovine tooth enamel in solution and in the solid state suggest a unique secondary structure containing beta-sheet and repetitive beta-turn structures. The repetitive beta-turn structure at the C-terminal end results from the unique primary structure of amelogenin.

Protein conformation in rat tooth enamel

Orientated 0.47 nm reflections in X-ray diffraction patterns of developing rat tooth enamel were confirmed using a wide range of specimen preparations and experimental conditions. This indicates that some of the organic matrix proteins adopt a beta-sheet conformation.