Biomedical subjects

Emeka Nkenke

Publications and source records attributed to Emeka Nkenke.

33 records · Page 2Linked to original sources

PubMed2003

Relative en- and exophthalmometry in zygomatic fractures comparing optical non-contact, non-ionizing 3D imaging to the Hertel instrument and computed tomography.

AIM: It is the aim of the present study to introduce non-contact, non-invasive optical 3D imaging to relative exophthalmometry and to compare the resulting data to exophthalmometry values assessed by the Hertel instrument and computed tomography. PATIENTS AND METHODS: 20 patients (3 female, 17 male, 44.4+/-16.6 years) without orbital pathology, who were examined by computed tomography of head and neck for the exclusion of different diseases, and seven patients (1 female, 6 male, 40.1+/-14.4 years), who received routine orbital computed tomography because of zygomatic fractures, were included in the study. Optical 3D images of the facial surface were assessed and Hertel exophthalmometry was carried out to determine the relative globe position. In patients with zygomatic fractures the assessment of optical 3D images and Hertel values was repeated 5 days after surgery. RESULTS: For patients without orbital pathology relative exophthalmometry data were 1.4+/-1.1 mm for the Hertel instrument, 0.9+/-1.0 mm for computed tomography and 0.5+/-0.5 mm for optical 3D imaging. The values for Hertel exophthalmometry and computed tomography did not differ statistically significantly (p(Herteldifferencepreop/CTdifferencepreop)=0.284), while there was a significant difference between Hertel exophthalmometry and optical 3D imaging (p(Herteldifferencepreop/opticaldifferencepreop)=0.008). In the cases of zygomatic fractures, Hertel exophthalmometry revealed less pronounced relative differences in globe position than CT and optical 3D imaging data (Hertel 0.7+/-1.1 mm, CT 1.9+/-1.0 mm, optical 3D imaging 1.9+/-1.0 mm). Postoperatively, relative Hertel exophthalmometry showed an increased value revealing a more pronounced enophthalmos (1.7+/-1.0 mm), while the corresponding value of the optical 3D images decreased as a sign for normalization of the globe position (1.1+/-0.7 mm). CONCLUSION: Because of its reliance on the lateral orbital rims Hertel exophthalmometry can lead to an under- or overestimation of enophthalmos, when soft tissue oedema or a dislocation of the orbital rim are present. The combination of computed tomography as baseline measurement and optical 3D imaging for the follow-up examinations reveal more realistic data in cases of zygomatic fractures. Therefore, they should be preferred to the determination of Hertel values especially in more complex cases.

Adult↗

PubMed2003

Analysis of bone resorption after secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or prosthodontic treatment.

PURPOSE: We sought to analyze the success rate of secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or gap opening. PATIENTS AND METHODS: Sixty-eight secondary alveolar cleft bone grafts with iliac crest spongiosa were carried out in 57 patients (mean age, 9 years; age range, 8 to 11 years) with 11 bilateral and 46 unilateral clefts of the lip, alveolus, or palate. Gap closures were carried out after 53 bone grafts (78%), and gap openings with subsequent dental implants were carried out with 15 bone grafts (22%). The parameters acquired radiologically (orthopantomograms) at the time of the surgery and the follow-up examination (mean age, 3 years; age range, 7 months to 9 years) were 1) bone resorption in relation to the interdental height of the alveolar process in the vicinity of the cleft and 2) root growth of the teeth in the vicinity of the cleft. The statistically significant differences (P <.05) were monitored with a software program. Resorption grades I and II (>50% of the interalveolar bone height) were considered to be a success. RESULTS: Resorption was grade I in 69%, grade II in 19%, grade III in 10%, and grade IV in 1% of cases. Thus, the overall success rate was 88%. At the time of the osteoplasty, the root growth of the tooth in the immediate vicinity of the cleft was fully completed in 27 teeth (39%), three-quarters completed in 23 teeth (26.5%), and semicompleted in 18 teeth (33.8%). Twelve teeth (18%) in the vicinity of the cleft (lateral incisors/canine) remained unerupted and displaced after the surgery. It was necessary to expose unerupted teeth surgically to reposition them orthodontically. The resorption losses were significantly lower with gap closures than with gap openings (P <.001). However, bone grafts performed before canine eruption were largely carried out with the objective of orthodontic gap closure, in contrast to the bone grafts that were carried out after canine eruption (P <.02). CONCLUSION: Gap closures provide more favorable results than do gap openings in regard to resorption. Controlled dental eruptions or orthodontic gap closures reduce the graft resorption. The exact timing of surgery proved to be only a secondary consideration.

Alveolar Process↗

PubMed2003

Implant stability and histomorphometry: a correlation study in human cadavers using stepped cylinder implants.

The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.

Aged↗

PubMed2003

Bone contact, growth, and density around immediately loaded implants in the mandible of mini pigs.

The aim of the study was to compare the bone mineral apposition rate (BMAR) of immediately loaded implants with an unloaded control during the early healing phase in the partially edentulous mandible. In seven mini pigs, three premolars and the first molar were removed in the left mandible. Three months later, five implants were installed. Four implants received a fixed provisional restoration and were loaded immediately. The most anterior implant was used as unloaded control. Polychromatic fluorescence labelling was performed to assess the BMAR. After 4 months, the implants were retrieved together with the adjacent bone. Histological specimens were prepared and subjected to a fluorescence microscopic and histomorphometric analysis. Two provisional restorations were found partially lost at the end of the observation period. One implant that had lost the splinting fixation showed soft connective tissue healing. The BMAR did not differ statistically significantly between loaded and unloaded implants and within the single groups during the observation period (BMARloaded days 14-42=1.8+/-0.2 microm/d, BMARloaded days 42-70=1.8+/-0.1 microm/d, BMARloaded days 70-98=1.6+/-0.1 microm/d, pBMARloaded days 14-42/42-70/70-98 =0.156, BMARunloaded days 14-42=1.7+/-0.1 microm/d, BMARunloaded days 42-70=1.8+/-0.2 microm/d, BMARunloaded days 70-98=1.6+/-0.4 microm/d, pBMARunloaded days 14-42/42-70/70-98=0.368, pBMARloaded/unloaded days 14-42=0.073, pBMARloaded/unloaded days 42-70=0.098, pBMARloaded/unloaded days 70-98=0.262). Four months after implant placement, the bone-to-implant contact was 77.8+/-17.3% for the loaded and 78.0+/-5.8% for the unloaded implants (P=0.753). Immediate loading does not affect the bone mineral apposition rate when compared with unloaded implants. Rigid splinting seems to be the crucial factor for implant success. Uncontrolled masticatory forces can cause failure after partial loss of the provisional restoration.

Animals↗

PubMed2003

Anatomic site evaluation of the zygomatic bone for dental implant placement.

Thirty human zygomatic bone specimens (15 females mean age 81.60 +/- 11.38 years, 15 males, mean age 78.47 +/- 6.58 years) were examined by quantitative computed tomography and histomorphometry. The aim of the study was to assess the bone mineral density, the trabecular bone volume and the trabecular bone pattern factor. Moreover, the anterior-posterior and the medio-lateral dimensions and the estimated implant length within the zygomatic bone were determined. For quantitative computed tomography the specimens were scanned together with a bone mimicking anthropomorphic reference phantom. The bone mineral density was calculated for the specimens in the plane of the intended direction of the implant placement. Subsequently, with the sawing and grinding technique, the specimens were prepared in the same plane for histomorphometry. The trabecular bone mineral density was 369.95 +/- 188.80 mg/cm3 for the female and 398.94 +/- 99.11 mg/cm3 for the male specimens (P = 0.23). The male trabecular bone volume showed a value of 27.32 +/- 9.49%, while the female group reached a value of 19.99 +/- 7.60% (P = 0.23). The trabecular bone pattern factor was 1.2 x 10-2 +/- 1.28 mm-1 for the male and 1.02 +/- 0.96 mm-1 for the female specimens (P = 0.045). The study reveals that the zygomatic bone consists of trabecular bone with parameters that are unfavourable for implant placement. However, the success of implants placed in the zygomatic bone is secured by the employment of at least four cortical portions.

Aged↗

PubMed2003

Sinus floor augmentation with beta-tricalciumphosphate (beta-TCP): does platelet-rich plasma promote its osseous integration and degradation?

When dental implants are to be inserted, sinus floor augmentation is an effective treatment procedure to improve bone height in the posterior maxilla. In addition to autogenous bone material, allogenic materials, e.g. beta-tricalciumphosphate (beta-TCP), have been used successfully. The purpose of this study was to investigate whether the combination of beta-TCP with platelet-rich plasma (PRP) enhances bony regeneration and resorption of the tricalciumphosphate material. In a randomized prospective trial, 45 sinus floor elevations were performed in 39 patients. In 22 sites, PRP was added to the beta-TCP granules, while in 23 sites beta-TCP without PRP was used. Six months later, bone specimens were harvested from the augmented region during the implant insertion procedure. The formation of new bone was about 8-10% higher when PRP was applied. A faster degradation of the ceramic bone substitute was not observed. In conclusion, when PRP was added to beta-TCP, bone regeneration was supported to a small extent. However, the resorption of beta-TCP was not accelerated and foreign-body giant cells and soft tissue surrounding the beta-TCP granules were present.

Absorbable Implants↗

PubMed2003

Validation of in vivo assessment of facial soft-tissue volume changes and clinical application in midfacial distraction: a technical report.

The purpose of this study was to validate the assessment of visible volume changes of the facial soft tissue with an optical three-dimensional sensor and to introduce new parameters for the evaluation of the soft-tissue shape achieved from three-dimensional data of selected cases of midfacial distraction. Images of a truncated cone of known volume were assessed repeatedly with an optical three-dimensional sensor based on phase-measuring triangulation to calculate the volume. Two cubic centimeters of anesthetic solution was injected into the right malar region of 10 volunteers who gave their informed consent. Three-dimensional images were assessed before and immediately after the injections for the assessment of the visible volume change. In five patients who underwent midfacial distraction after a high quadrangular Le Fort I osteotomy, three-dimensional scans were acquired before and 6 and 24 months after the operation. The visible soft-tissue volume change in the malar-midfacial area and the mean distance of the accommodation vector that transformed the preoperative into the postoperative surface were calculated. The volume of the truncated cone was 235.26 +/- 1.01 cc, revealing a measurement uncertainty of 0.4 percent. The injections of anesthetic solution into the malar area resulted in an average visible volume change of 2.06 +/- 0.06 cc. The measurement uncertainty was 3 percent. In the five patients, the average distance of maxillary advancement was 6.7 +/- 2.3 mm after 6 months and 5.4 +/- 3.0 mm after 2 years. It was accompanied by a mean visible volume increase of 8.92 +/- 5.95 cc on the right side and 9.54 +/- 4.39 cc on the left side after 6 months and 3.54 +/- 3.70 cc and 4.80 +/- 3.47 cc, respectively, after 2 years. The mean distance of the accommodation vector was 4.41 +/- 1.94 mm on the right side and 4.74 +/- 1.32 mm on the left side after 6 months and 1.62 +/- 1.96 mm and 2.16 +/- 1.52 mm, respectively, after 2 years. The assessment of visible volume changes by optical three-dimensional images can be carried out with considerable accuracy. The determination of volume changes and accompanying accommodation vectors completes the cephalometric analysis during the follow-up of patients undergoing midfacial distraction. The new parameters will help to assess normative soft-tissue data on the basis of three-dimensional imaging with a view to an improved three-dimensional prediction of the operative outcome of orthognathic surgery.

Adolescent↗

PubMed2002

Morbidity of harvesting of retromolar bone grafts: a prospective study.

20 retromolar bone grafts were harvested in outpatients for augmentation of the implant site from January to June 2000 (10 female, 10 male, 40.9 +/- 12.8 years, minimum 17 years, maximum 66 years). The aim of the study was to assess typical complications of this procedure in a prospective manner. For the determination of the superficial sensory function of the inferior alveolar and the lingual nerve, an objective method was used. The bone grafts were harvested for single tooth reconstruction. In 14 cases a ridge augmentation and in 6 cases an endoscopically controlled crestal sinus floor elevation was performed. Preoperatively, the height of bone above the cranial aspect of the inferior alveolar nerve in the retromolar region was assessed radiologically with known markers. The maximum mouth opening was determined. The superficial sensory function of the inferior alveolar and the lingual nerve was assessed with the Pointed-Blunt Test, the Two-Point-Discrimination Test and the objective method of the 'Pain and Thermal Sensitivity' Test (PATH Test). Moreover, the pulp sensitivity of the teeth of the donor site was determined by cold vitality testing. All tests were repeated 1 week postoperatively. Intraoperatively, the width of the retromolar region was measured with a caliper. The patients rated the operative strain on a visual analogue scale. The height of bone above the inferior alveolar nerve in the retromolar region was 11.0 +/- 2.2 mm. The width of the retromolar area was 14.2 +/- 1.9 mm. Postoperatively, the maximal mouth opening changed significantly (40.8 +/- 3.5 mm preoperatively, 38.9 +/- 3.7 mm postoperatively, P = 0.006). However, the reduction was not relevant clinically. A direct injury of the inferior alveolar or lingual nerve did not occur. A sensitivity impairment could not be detected for either of the nerves by the different test methods 1 week postoperatively. The operative strain related to the donor site was significantly less than the strain generated by the implant placement (rating on a visual analogue scale 2.8 +/- 1.0 and 4.1 +/- 2.0, respectively, P = 0.027). Retromolar bone grafts are a viable method for augmentation of the implant site in conjunction with single tooth reconstruction with low strain on the patient and minimal risk of complications.

Adolescent↗

PubMed2002

Histomorphometric and fluorescence microscopic analysis of bone remodelling after installation of implants using an osteotome technique.

The influence of the osteotome technique on the osseointegration of rough-surfaced stepped cylinder implants (Frialit)-2) was compared to conventional preparation of the implant site in an animal model. A total of 104 implants were placed into the distal femoral condyle of 52 New Zealand white rabbits. This region contains sufficient trabecular bone for implant placement. The implant site was prepared either by the osteotome technique or by conventional technique with drills as a control group. During the healing period polychromatic fluorescence labelling was performed with four different fluorescent dyes. After 2, 4 and 8 weeks, the implants were removed with the surrounding bone. The sample preparation was done using the 'sawing and grinding' technique. Ground sections 100 microm thick were used for fluorescence microscopic analysis; 30- microm-thick ground sections were examined histomorphometrically. After 2 weeks the bone-to-implant contact ratio was 55.0 +/- 7.1% for the osteotome technique and 29.2 +/- 4.8% for the control group (P < 0.0005). After 4 weeks, the bone-to-implant contact ratio was still significantly better for the osteotome technique (bone-to-implant contact ratio osteotome technique 71.1 +/- 7.2%, bone-to-implant contact ratio control 59.0 +/- 6.3%, P = 0.003). Eight weeks after implant placement the bone-to-implant contact ratio was still better for the osteotome technique compared to the conventional implant placement. However it was no longer statistically significant. The qualitative fluorescence microscopic examination showed an earlier and stronger signal for the osteotome technique than the control group. With the latter, the zone of mineralization moved slowly towards the implant surface. Implant sites prepared by the osteotome technique showed a pronounced signal in the whole compressed area already by the second day. In conclusion, the osteotome technique increases new bone formation and leads to an enhanced osseointegration of dental implants in trabecular bone. However, more experimental trials have to be carried out on higher mammals that show a metabolic rate of bone that is more comparable to humans.

Analysis of Variance↗

PubMedDate not supplied

The endoscopically controlled osteotome sinus floor elevation: a preliminary prospective study.

PURPOSE: It was the aim of the present prospective study to quantify the gain in height of implant sites by endoscopically controlled osteotome sinus floor elevations (ECOSFE) with simultaneous implant placement and to report the number of sinus membrane perforations. MATERIALS AND METHODS: From October 1999 to December 2000, of 92 sinus floor elevations, 18 were carried out endoscopically controlled with an osteotome technique. As augmentation material, beta-tricalcium phosphate (beta-TCP) or autogenous bone was used; 22 implants were placed. RESULTS: The residual height of the alveolar crest in the posterior maxilla was 6.8 +/- 1.6 mm on average. The implant lengths ranged from 10 to 16 mm (mean implant length 12.2 +/- 1.4 mm). They were significantly larger than the residual height of the alveolar crests (P < .0005). Elevation of the sinus floor with an osteotome had to be supported by conventional sinus floor elevation instruments after a mean elevation of 3.0 +/- 0.8 mm to prevent perforation of the sinus membrane. However, 1 perforation occurred, which was repaired with a periosteal patch. At stage 2 surgery, 2 implants were removed because of mobility. Endoscopic control revealed one case in which beta-TCP could be found within the sinus; another case showed areas of polypoid mucosa on the sinus floor. DISCUSSION: With the ECOSFE, perforations of the sinus membrane can be visualized; however, they cannot be avoided. Although this technique is less invasive than the lateral window technique, it cannot be recommended as a standard procedure in the posterior maxilla because of the large amount of additional equipment needed and the technically demanding procedure. CONCLUSION: The use of the ECOSFE should be confined to scientific trials.

Adult↗

PubMedDate not supplied

Bone conditioning to enhance implant osseointegration: an experimental study in pigs.

PURPOSE: Osseointegration of implants depends on time and the local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm and Zarb. The aim of the present study was to enhance osseointegration of implants through conditioning of the bone bed and to compare in this context the efficacy of bone condensation, an osteoinductive collagen (Colloss), and platelet-rich plasma (PRP). MATERIALS AND METHODS: Porcine frontal skull bone was used for the preparation of Identical-size implant beds. Before placement of the implants (Ankylos, 3.5 x 4 mm), the implant beds were untreated (control) or conditioned with condensation, Colloss, or PRP. The animals were sacrificed after 2, 4, and 8 weeks. The specimens were then compared and analyzed by microradiography, and statistical analysis was performed using the Wilcoxon signed rank test. RESULTS: At the early observation times, significant effects on the sites of topical bone conditioning in comparison to the control group could be seen regarding the implant-bone interface (2 weeks: control 31%, Colloss 60%, condensation 73%, PRP 47%; 4 weeks: control 39%, Colloss 51%, condensation 40%, PRP 42%) and peri-implant bone density (2 weeks: control 31%, Colloss 48%, condensation 59%, PRP 39%; 4 weeks: control 47%, Colloss 53%, condensation 41%, PRP 50%). A leveling of the results between groups was found at 8 weeks (implant-bone interface: control 51%, Colloss 58%, condensation 55%, PRP 62%; peri-implant bone density: control 50%, Colloss 55%, condensation 51%, PRP 51%). DISCUSSION: Overall, bone condensation and Colloss apparently influenced bone formation process from the onset, but over the entire 8-week healing period, differences in bone formation were not significant CONCLUSION: It can be stated that, in the initial healing phase, an effect of topical bone conditioning may be achieved by the different described methods.

Animals↗

PubMedDate not supplied

Immediate versus delayed loading of dental implants in the maxillae of minipigs: follow-up of implant stability and implant failures.

PURPOSE: To assess the course of the stability and the failure rate of dental implants placed in the partially edentulous maxillae of minipigs. MATERIALS AND METHODS: Three months after tooth removal, implants were placed in 9 minipigs. Six implants (XiVE; Friadent, Mannheim, Germany) were placed on each side of the posterior maxilla after preparation of the implant sites either by an osteotome technique or with spiral drills. Implant stability was assessed by resonance frequency analysis (RFA) at the time of placement, at second-stage surgery (which took place after a healing periods of 1, 2, 3, 4, or 5 months), and after a loading period of 6 months. RESULTS: Implant stability was significantly influenced by the healing period (P = .007). Implant stability decreased after 1 to 3 months of healing for both of the placement techniques and increased after a healing period of 4 months. After implant site preparation by an osteotome technique, 6 of 12 immediately loaded implants, 18 of 24 implants loaded after healing periods of 1 to 3 months, and 1 of 18 implants loaded after a healing period of 4 or 5 months were lost. After implant site preparation using spiral drills, 7 of 12 immediately loaded implants, 12 of 24 implants loaded after healing periods of 1 to 3 months, and 2 of 18 implants loaded after healing periods of 4 or 5 months were lost. Broad overlapping of confidence intervals for the number of implant failures revealed that there was no relevant difference between immediate and early functional loading for either of the 2 techniques. DISCUSSION AND CONCLUSION: Implant loading after healing periods of 1 to 3 months did not improve implant survival compared to immediate loading in the posterior maxillae of minipigs. Not until a healing period of 4 months was reached did implant stability begin to increase. Only when functional loading was started at this point in time was maximal implant survival achieved.

Analysis of Variance↗

PubMedDate not supplied

Immediate versus delayed loading of dental implants in the maxillae of minipigs. Part II: histomorphometric analysis.

PURPOSE: To assess histomorphometric parameters of dental implants placed in partially edentulous maxillae of minipigs. MATERIALS AND METHODS: In 9 minipigs, 6 XiVE implants were placed on each side of the maxilla, either after implant site preparation by an osteotome technique or by spiral drills. The implants were restored with fixed provisional restorations and loaded either immediately or after healing periods of up to 5 months. After a loading period of 6 months, the animals were sacrificed and the implants were retrieved together with the adjacent bone. Histologic specimens were prepared and bone-to-implant contact (BIC) ratio, interthread bone area, and peri-implant bone area were determined. RESULTS: An analysis of variance revealed that the BIC ratio on the palatal side was significantly influenced by the preparation technique of the implant site (P = .001) and by the healing period (P = .02). After implant site preparation by an osteotome technique, higher BIC values were achieved for implants that were loaded either immediately or after healing periods of 1 to 3 months. After healing periods of 4 to 5 months, implant site preparation with spiral drills showed slightly better results in regard to BIC. Interthread bone area and peri-implant bone area did not differ significantly statistically for the 2 implant placement techniques and the 3 healing periods. DISCUSSION AND CONCLUSION: After 6 months of functional loading in the maxilla, successful immediately loaded implants performed the same as implants subjected to an unloaded healing period prior to loading as far as histomorphometric data were concerned. Prospective randomized clinical studies should be carried out in humans to compare immediate loading to loading after an unloaded healing phase.

Analysis of Variance↗

PubMedDate not supplied

The co-expression of c-myc and p53 increases and reaches a plateau early in oral oncogenesis.

BACKGROUND: The balance between cell proliferation and apoptosis plays a significant role in cancer development. The expressions of the p53 and c-myc genes, both strongly related to cell proliferation and apoptosis, were studied in sequential histological grades of oral carcinogenesis in an animal model. MATERIALS AND METHODS: Thirty-seven hamsters were divided into three groups (A,B,C), which were treated with 9,10-dimethyl-1,2-benzanthracene and sacrificed at 10,14 or 19 weeks, respectively, after treatment. The histological status of the oral lesions in the experimental groups corresponded well with tumour advancement (from dysplasia to moderately-differentiated carcinoma). Tumour sections were studied immunohistochemically. RESULTS: The expressions of both p53 and c-myc increased significantly in precancer stages and then reached a plateau. The same pattern was observed in the animal groups with the culmination of expression of both genes in group A. CONCLUSION: The coexpression of p53 and c-myc proteins in the earlier stages of oral oncogenesis may be used for the early detection of premalignant lesions.

Animals↗

PubMedDate not supplied

FGFR-2 and -3 play an important role in initial stages of oral oncogenesis.

BACKGROUND: FGFR-2 and FGFR-3 (fibroblast growth factor receptors) have been shown to play an important role in several processes including carcinogenesis. This study was designed to determine gradual FGFR-2 and FGFR-3 expression in sequential stages of oral carcinogenesis in an experimental animal system of Syrian golden hamsters. MATERIALS AND METHODS: Tissue sections ranging from normal mucosa to squamous cell carcinoma were studied using monoclonal antibodies against FGFR-2 and FGFR-3 proteins. RESULTS: A significant elevation was revealed in both FGFR-2 and FGFR-3 expression during the stages of dysplasia and early invasion, while in the later stages of oral carcinogenesis the expression of both FGFR-2 and FGFR-3 decreased although not significantly. CONCLUSION: Our findings indicate that FGFR-2 and FGFR-3 seem to play an important role in the initial stages of oral cancer progression.

Animals↗