Bone reactions around dental implants subjected to progressive static load: an experimental study in dogs.

OBJECTIVE: To evaluate histologically and histomorphometrically, the peri-implant bone reaction around implants subjected to controlled progressive orthodontic loading. MATERIALS AND METHODS: In three beagle dogs, bilateral edentulous flat alveolar ridges were created in the maxillary area posterior to the canines. After 8 weeks of healing, 24 implants (Biomet 3i) were inserted in the edentulous sites. Two experimental groups were created. Progressive loading group: Twelve implants were left to heal for 8 weeks uncovered, and abutments were adapted and connected by pairs with Ni-Ti orthodontic springs. A gradual static force of 100, 200 and 300 g was applied for a 3-week period each. Thus, a total progressive loading period of 9 weeks was exercised. Unloaded control group: Twelve implants were left to heal undisturbed. At the end of the experimental period, all implants of both groups were removed with the surrounding bone. Histologic and histomorphometric analyses were performed, and the following parameters were measured: bone-to-implant contact, bone density 1 and 2 mm distant to the implant threads and crestal bone resorption. Median regression models are used for statistical analysis. RESULTS: Implants of the progressive loading group exhibited significantly higher percentage of bone-to-implant contact compared to the unloaded control implants (P = 0.018). Bone density 1 and 2 mm distant to the threads was found to be the same between the two groups (P = 0.734 and P = 0.961, respectively). Crestal bone resorption did not differ between loaded and unloaded implants (P = 0.813). CONCLUSION: The application of progressive loading by controlled orthodontic force on osseointegrated implants provoked significant increase in the percentage of bone-to-implant contact of the low-density bone of the dog maxilla.

Novel mutations of the HRAS gene and absence of hotspot mutations of the BRAF genes in oral squamous cell carcinoma in a Greek population.

Oral squamous cell carcinoma (OSCC) is the sixth most common cancer in the world. The phosphatidylinositol 3 kinase (PI3K) signalling pathway has been reported to play an important role in OSCC. Since we have previously detected absence of hotspot PIK3CA gene mutations in the Greek population, we hypothesized that BRAF or HRAS may be activated as upstream effectors of the pathway. Furthermore, the status of the HRAS and BRAF mutations in OSCC has never been assessed before in the Greek population. Eighty-six primary paraffin-embedded tumors were screened for BRAF and HRAS hotspot mutations. In HRAS, two hotspot mutations in codon 12 (2.3%) and eight new genetic alterations were detected (8.6% overall). One new missense mutation, Alanine53Valine (Ala53Val), one silent mutation, two mutations in the 5'UTR region and four mutations in intron 1 were detected. No hotspot mutations in Braf were found. A new silent mutation/polymorphism T1803C was detected at a percentage of 30%. This study is the first to report HRAS mutations in the Greek population. The results suggest that RAS is an important member of the PI3K signalling pathway and may play a role in the tumorigenesis of OSCC.

Comparative biomechanical evaluation of mono-cortical osteosynthesis systems for condylar fractures using photoelastic stress analysis.

Fractures of the condyle account for 20-30% of all mandibular fractures, and are therefore one of the most common facial injuries. Precise evaluation of the mechanical stresses that develop in a fractured mandible is essential, particularly for the testing of systems currently used for stabilisation of the condylar fragment. Photoelastic stress analysis can be used to visualise alterations in the strain that is induced in the mandible by a fracture, and in the osteosynthesis materials used to stabilise it. This method, used on currently used osteosynthesis materials, showed that stabilisation of a subcondylar fracture with a single miniplate does not provide enough stability, whereas the use of two miniplates - properly positioned - offers sufficient stability in all loading conditions. A microplate may be used as a tension-resisting plate with equally good results.

Management of malignant parotid tumors.

INTRODUCTION: The aims of this study were to review our experience in the treatment of malignant parotid tumors in material from one center over a 12-year period and to assess treatment outcome and particularly survival. MATERIALS AND METHODS: Thirty-one patients treated primarily by surgery were included in the study. Complete data regarding the demographic details of the patients, tumor stage, presence of regional/distant metastases, treatment, tumor histology, grade, and follow up were compiled. With reference to the extent of tissue removed, partial superficial parotidectomy was performed in 11 patients, superficial parotidectomy, in 14 patients, and total radical parotidectomy, in six patients. RESULTS: The median time of follow-up was 64 months, ranging from 8 to 144 months. Eight patients developed recurrences. Six patients died within the follow-up time. The overall survival rates at 5 and 10 years were 82.2% and 76.7%, respectively. The 5- and 10-year disease-free survival rates were 74.8% and 69.8%, respectively. DISCUSSION: For patients with malignant parotid tumors, the treatment should be individualized according to the findings of each specific case, and regarding surgery, particular care and attention should be paid to maintaining all or part of the facial nerve whenever possible.

Intraosseous mandibular venous malformation.

Intraosseous venous malformations are rare benign lesions that account for approximately 0.5% to 1% of all osseous tumors. Involvement of the facial skeleton is rather uncommon, with the mandible and maxilla most frequently involved. In the current study, we report a case of an intraosseous venous malformation in a 52-year-old male patient with a history of mandibular keratocystic odontogenic tumor. The patient presented with an asymptomatic bony lesion in the mandible. Treatment involved surgical excision. Histopathologic examination of the excised specimen revealed an intraosseous venous malformation. Twelve months postoperatively, there was no evidence of recurrence.

Absence of hotspot mutations in exons 9 and 20 of the PIK3CA gene in human oral squamous cell carcinoma in the Greek population.

OBJECTIVE: Phosphatidylinositol-3 kinases (PI3K) are a group of heterodimeric lipid kinases that regulate many cellular processes. Recent studies have reported high frequencies of somatic hotspot mutations in the phosphatidylinositol-3 kinase catalytic alpha (PIK3CA) gene, which encodes for one of these kinases, in several human solid tumors, including oral squamous cell carcinoma (OSCC). The aim of this study was to determine the frequency of hotspot mutations in exons 9 and 20 of the PIK3CA gene in OSCC in the Greek population. STUDY DESIGN: Eighty-six formalin-fixed and paraffin-embedded primary tumor specimens were analyzed by direct genomic DNA sequencing. Chi-square was used for statistical analysis. RESULTS: No hotspot mutations were detected in any of the samples. Two intronic polymorphisms IVS8 and IVS9 were detected, mainly in patients with cancer of the buccal mucosa and lower gingival and alveolus respectively. CONCLUSIONS: PIK3CA hotspot mutations are unlikely to play a major role in the pathogenesis of OSCC in the Greek population.

Parathyroid hormone-related peptide (PTHrP), parathyroid hormone/parathyroid hormone-related peptide receptor 1 (PTHR1), and MSX1 protein are expressed in central and peripheral giant cell granulomas of the jaws.

OBJECTIVE: Parathyroid hormone-related peptide (PTHrP) binds to the parathyroid hormone receptor type 1 (PTHR1), which results in the activation of pathways in osteoblasts that promote osteoclastogenesis through the RANK/RANKL system. RANK/RANKL expression has been shown in central giant cell granuloma of the jaws but PTHrP/PTHR1 has not. MSX1 protein is a classical transcription regulator which promotes cell proliferation and inhibits cell differentiation by inhibiting master genes in tissues such as bone and muscle. It has been implicated in the pathogenesis of cherubism, and its expression has been reported in a single central giant cell granuloma (CGCG) case. We aimed, therefore, to study the expression of those proteins by the different cellular populations of central and peripheral giant cell granulomas (PGCGs) of the jaws. STUDY DESIGN: Twenty cases of CGCG and 20 cases of PGCG of the jaws were retrospectively examined by immunohistochemistry for the percentage of positively staining cells to antibodies for PTHrP, PTHR1, and MSX1, using a semiquantitative method. RESULTS: In both CGCG and PGCG of the jaws, PTHrP and PTHR1 were abundantly expressed by type I multinucleated giant cells (MGC) and mononucleated stromal cells (MSC) with vesicular nuclei, whereas type II MGC and MSC with pyknotic nuclei expressed those proteins to a lesser extent. In both CGCG and PGCG of the jaws, MSX1 was abundantly expressed by type I MGC and MSC but type II MGC did not express it. A statistically significant difference (P < .05) was observed between CGCG and PGCG in the expression of PTHrP in type II MGC and MSC with pyknotic nuclei and in the expression of PTHR1 in type II MGC. CONCLUSIONS: We suggest that in CGCG and PGCG of the jaws, PTHrP-positive immature osteoblasts activate PTHR1-positive mature osteoblasts to produce RANKL which interacts with RANK on the PTHrP/PTHR1-positive osteoclast-precursor cells found in abundance in the stroma of giant cell lesions and induces osteoclastogenesis through the classic pathway. Cells of the jawbones, the periodontal ligament, or the dental follicle, originating from the neural crest, may be involved in the pathogenesis of giant cell lesions of the jaws. Further study is required for these suggestions to be proved.

Surgical management of a large median dermoid cyst of the neck causing airway obstruction. A case report.

INTRODUCTION: Dermoid cysts of the floor of the mouth and submandibular space represent an unusual clinical entity. CASE REPORT: A case of an enlarged median dermoid cyst in a young female adult causing obstruction of the airway is reported. DISCUSSION: The need of an extraoral and intraoral incision for the removal of the cyst is discussed, along with a review of the literature.

Metastases to supramandibular facial lymph nodes in patients with squamous cell carcinoma of the oral cavity.

PURPOSE: This study evaluated the frequency of metastases to supramandibular facial lymph nodes (SFLNs) in patients with squamous cell carcinoma (SCC) of the oral cavity. PATIENTS AND METHODS: SFLNs were identified and removed during neck dissection from 43 patients with oral SCC. All of them were histopathologically and immunohistochemically examined, to detect possible metastases and micrometastases. RESULTS: Metastases to SFLNs were present in 6 patients (13.95%). Metastases were much more common among patients with palpable neck nodes, larger size of the primary site, advanced TNM stage, and greater age and those in whom the primary site was located in the mucosa of the alveolar ridge of the mandible. CONCLUSIONS: Surgical procedures in the region of the SFLNs must be performed very carefully, because of their close relation with the marginal mandibular nerve. In patients with oral SCC and palpable neck nodes, those with advanced disease, and those in whom the primary site is located in the mucosa of the alveolar ridge of the mandible, removal of SFLNs must be considered.

Large olfactory neuroblastoma (esthesioneuroblastoma) surgically treated with an Altemir technique modification: a case report.

INTRODUCTION: Olfactory neuroblastomas are rare malignant tumors that usually occur in the upper nasal cavity. The purpose of this paper is to present a case of a large olfactory neuroblastoma filling the entire nasal cavity, treated with an Altemir technique modification. METHODS: A 39-year-old woman presented with a large tumor of the nasal cavity. After the laboratory examinations, the tumor was classified as a Kadish stage A olfactory neuroblastoma. The selected treatment was the surgical excision after an Altemir technique modification combined with midfacial degloving and additional radiotherapy. RESULTS: Histopathology revealed a Hyams grade III olfactory neuroblastoma completely removed. Although the patient refused the additional radiotherapy, 18 months postoperatively, there were no signs of recurrence, and the patient shows big improvement on her sense of smell. CONCLUSIONS: Large olfactory neuroblastomas filling the entire nasal cavity extending back to the postnasal space can be completely removed using a transfacial approach as the Altemir technique modification is.

Bone regeneration using beta-tricalcium phosphate in a calcium sulfate matrix.

The aim of the study was the histomorphometric comparison of the osteogenic potential of beta-tricalcium phosphate (beta-TCP) alone or in a calcium sulfate matrix. Three round defects, 10 mm (diameter) x 5 mm (depth), were created on each iliac crest of 4 dogs. The defects were divided into 3 groups. Ten defects were filled with beta-TCP in a calcium sulfate (CS) matrix (Fortoss Vital; group A), 10 defects were filled with beta-TCP alone (Fortoss Resorb; group B), and 4 defects were left ungrafted to heal spontaneously (group C). All defects were left to heal for 4 months without the use of a barrier membrane. Histologic evaluation and morphometric analysis of undecalcified slides was performed using the areas of regenerated bone and graft remnants. All sites exhibited uneventful healing. In group A sites (beta-TCP/CS), complete bone formation was observed in all specimens, graft granules dominated the area, and a thin bridge of cortical bone was covering the defect. Group B (beta-TCP) defects were partially filled with new bone, the graft particles still dominated the area, while the outer cortex was not restored. In the ungrafted sites (group C), incomplete new bone formation was observed. The outer dense cortical layer was restored in a lower level, near the base of the defect. The statistical analysis revealed that the mean percentage of new bone regeneration in group A was higher than in group B (49.38% and 40.31%, respectively). A statistically significant difference existed between the 2 groups. The beta-TCP/CS group exhibited significantly higher new bone regeneration according to a marginal probability value (P = .004 < .05). The use of beta-TCP in a CS matrix produced significantly more vital new bone fill and preserved bone dimensions compared with the use of beta-TCP alone.

Branchial cleft cysts in adults. Diagnostic procedures and treatment in a series of 18 cases.

PURPOSE: Branchial cleft anomalies may be presented as branchial cysts, fistulas, or sinuses. Purpose of this paper is to present the diagnostic procedures and the treatment in a series of branchial cleft cysts. METHODS: Eighteen patients with branchial cleft cysts were surgically treated. All of them were subjected in laboratory examinations with ultrasonography, CT or/and MRI, and fine needle aspiration cytology (FNAC). Complete excision was the treatment in all cases. RESULTS: Eight patients had Type I, seven Type II, two Type III, and one a Type IV cyst. In all cases the surgical removal was successful and after 1 to 7 years post-surgical follow-up, no recurrences have been developed. CONCLUSIONS: Branchial cleft cyst diagnostic procedure must be the same as for other neck swellings. FNAC is very useful for the diagnosis and the surgical approach must ensure safe and complete cyst removal in order to avoid intraoperative complications and recurrences.

Use of a porcine dermal collagen graft (Permacol) in parotid surgery.

Our aim was to present the results of the use of porcine dermal collagen graft (Permacol) in the prevention of Frey's syndrome and face-contouring aesthetic deformities after operations on the parotid. We treated 19 patients with parotid tumours. After resection, a Permacol sheet was applied to the perimeter of the tissue deficit so that it was fully covered, and was sutured firmly. This technique produced satisfactory aesthetic results with good facial contouring in all patients. It also protected the exposed parotid nerve plexus, and none of the patients developed Frey's syndrome. Permacol produced good results in both postoperative facial contouring and prevention of Frey's syndrome.

Intramuscular myxoma of the masseter muscle. A case report.

PURPOSE: Myxomas are benign, locally infiltrative, connective tissue tumors that rarely occur in the head and neck region. The purpose of this paper is to describe a very rare case of an intramuscular myxoma of the masseter muscle. METHODS: A 74-year-old man presented with a 2-year history of a painless swelling over his left preauricular region. Computed tomography scan showed an intramasseter well-defined soft tissue mass. After a preauricular approach, a circumscribed solid gelatinous tumor was excised with thin margins including adjacent muscle tissue. RESULTS: Histopathology revealed an intramuscular myxoma, completely resected. The patient made an uneventful recovery, and there were no signs of recurrence 26 months after surgery. CONCLUSIONS: Intramuscular myxoma of the masseter is an extremely rare entity, but it must be considered in the differential diagnosis of the swellings of the preauricular region.

Vascular fractal dimension and total vascular area in the study of oral cancer.

BACKGROUND: Microvessel quantification has been studied extensively as a factor reflecting angiogenesis in various malignant tumors. The aim of our study was to evaluate the vascular fractal dimension and the immunohistochemically positive total vascular area in oral cavity carcinomas in order to assess their potential value as factors reflecting angiogenesis. METHODS: Histologic sections from 48 carcinomas and 17 nonmalignant mucosa specimens were evaluated by image analysis using fractal analysis software. Total vascular area was also quantified. RESULTS: Carcinomas presented higher mean values of vascular fractal dimension and total vascular area compared to normal mucosa. The difference for the vascular fractal dimension was statistically significant. CONCLUSIONS: This study provides evidence that vascular fractal dimension could be used as a reliable factor reflecting angiogenesis in oral squamous cell carcinoma and that there are several statistically significant correlations among total vascular area, vascular fractal dimension, nuclear size, and clinicopathologic factors.

Hypoglossal nerve palsy caused by a large vagal paraganglioma: case report.

We present a vagal paraganglioma in a 74-year-old woman, who presented with dysphagia, dysarthria and hoarseness.

Blow-out fractures in children: six years' experience.

OBJECTIVES: To present and analyze our experience in treating blow-out fractures in children, over a 6-year period. STUDY DESIGN: The study was retrospective with 16 consecutive cases of blow-out fractures in children aged 5 to 15 years. All patients presented with impairment of eye motility and diplopia together with radiological findings. Treatment included fracture reduction, release of entrapped periorbital soft tissues, and placement of an alloplastic membrane on the orbital floor. Fractures were linear in 11 cases (trapdoor) and severe or comminuted in 5 cases. RESULTS: Clinical symptoms subsided in all cases. Complete recovery of eye motility was achieved after surgical procedure in 13 cases; 2 patients presented late but had full recovery, and 1 patient, 4 years postoperatively, still had slight motility impairment. CONCLUSIONS: Surgical treatment of blow-out fractures, including periorbital tissue release and placement of a membrane lining on the orbital floor, presented satisfactory results in our cases.