Library

Notes: Abstract The aim of the present study was a microscopic analysis of dens invaginatus with a cutting grinding system that allowed to obtain thin ground sections of undemineralized material. Cavities of about 1 mm were present in the bulk of the inner enamel and these cavities were lined by aprismatic enamel, by a basophilic lamellar material and by cuboidal cells of probable epithelial origin. Enamel in a more external location had an amorphous aprismatic appearance with the presence of basophilic rounded or lamellar calcifications with the appearance of Liesegang's rings. In one case the interradicular space was occupied by a large amount of a highly calcified bone tissue.

Notes: Background: Leiomyosarcoma is a relatively uncommon mesenchymal tumor that exhibits smooth-muscle differentiation. Only 3 to 10% of leiomyosarcomas arise in the head and neck, the nose and paranasal sinuses, skin and subcutaneous tissue and cervical esophagus being the most common localizations. Most leiomyosarcomas involving the oral tissues primarily affect the maxillary sinus, the maxillary or mandibular bone. A review of the English-language literature since 1908 revealed 30 reported cases of primary leiomyosarcoma of the oral mucosa and soft tissues.Material and Methods: We report on a case of gingival leiomyosarcoma, arising in a 31-year-old female and involving the upper alveolar mucosa. Following the diagnosis of malignant neoplasm on frozen sections and an en-block resection, the tumour was formalin-fixed and paraffin embedded for histological and immunohistochemical examination.Results: Microscopically, the tumor was composed of interlacing fascicles of spindle-shaped cells with elongated, blunt-ended nuclei and eosinophilic cytoplasm, containing PAS-positive granules. Mitoses, both typical and atypical, and scattered necrotic foci were present. Consistent desmin, muscle specific and α-smooth muscle-specific, and vimentin immunoreactivity was demonstrated in the tumor cells. The patient is alive and free of disease at a 7-year follow-up.Conclusions: Intra-oral leiomyosarcomas are exceptionally rare. Accurate diagnosis and treatment is largely based on the careful search of clinical signs indicative of malignancy (e.g., neoplastic bone destruction, wide invasion of adjacent tissues) and intra-operative (frozen sections) examination of the lesion. Though the case reported herein showed an attenuated clinical behavior, prolonged follow-up is mandatory in view of possible tumor relapse.

Notes: Background: Calcifying odontogenic cyst (COC) is a rare lesion representing about 1% of jaw cysts. It may occur in a central (intraosseous) or peripheral (extraosseous) location.Method: A case of peripheral COC located on the gingiva, appearing as a painless, circumscribed, pink nodule has been reported.Results: Peripheral, in contrast to central, COC tends to affect older patients. Peripheral COC is a less aggressive lesion than the central counterpart, and a simple excision biopsy is curative.Conclusion: The histological finding of a keratinized epithelium rich in ghost cells has helped in making the diagnosis.

Notes: Background, aims: Liposarcoma is the 2nd most frequent soft tissue sarcoma in adults, but it is extremely rare in the head and neck and, particularly, in the oral cavity. We report on a 25-year-old female who presented with a periodontal mass, extended from the right upper 3rd molar to the right upper 2nd premolar, covered by intact oral mucosa. The clinical differential diagnosis included peripheral giant cell granuloma, salivary gland neoplasms, squamous cell carcinoma of the gingiva, sarcoma and malignant lymphoma.Methods: To accurately plan subsequent treatment, an excisional biopsy was performed and a myxoid liposarcoma was diagnosed. Consequently, the patient underwent wide excision of the neoplasm with maxillary en-block resection.Results: The post-operative course was uneventful and the patient is alive and well 8 years after the original diagnosis. The authors stress the importance of considering soft tissue sarcomas in the diagnostic approach to patients with unusual periodontal neoplasms and to plan adequate surgical sampling of the lesion (i.e. excisional biospy).Conclusions: This appears of pivotal importance as more limited specimens may result in inaccurate pre-operative diagnosis.

Notes: Abstract: Background: The placement of different graft materials and/or the use of occlusive membranes to cover the extraction socket entrance are techniques aimed at preserving/reducing alveolar ridge resorption. The use of grafting materials in fresh extraction sockets has, however, been questioned because particles of the grafted material have been found in alveolar sockets 6–9 months following their insertion.Aim: The aims of the study were to (i) evaluate whether alveolar ridge resorption following tooth extraction could be prevented or reduced by the application of a bioabsorbable polylactide–polyglycolide sponge used as a space filler, compared to natural healing by clot formation, and (ii) evaluate histologically the amount and quality of bone tissue formed in the sockets, 6 months after the use of the bioabsorbable material.Material and methods: Thirty-six patients, undergoing periodontal therapy, participated in this study. All patients were scheduled for extraction of one or more compromised teeth. Following elevation of full-thickness flaps and extraction of teeth, measurements were taken to evaluate the distance between three landmarks (mesio-buccal, mid-buccal, disto-buccal) on individually prefabricated stents, and the alveolar crest. Twenty-six alveolar sockets (test) were filled with a bioabsorbable polylactide–polyglycolide acid sponge (Fisiograft®), while 13 sockets (controls) were allowed to heal without any filling material. The flaps were sutured with no attempt to achieve primary closure of the surgical wound. Re-entry for implant surgery was performed 6 months following the extractions. Thirteen biopsies (10 test and three control sites) were harvested from the sites scheduled for implant placement.Results: The clinical measurements at 6 months revealed, in the mesial-buccal site, a loss of bone height of 0.2 mm (1.4 SD) in the test and 0.6 mm (1.1 SD) in the controls; in the mid-buccal portion a gain of 1.3 mm (1.9 SD) in the test and a loss of 0.8 mm (1.6 SD) in the controls; and in the distal portion a loss of 0.1 mm (1.1 SD) in the test and of 0.8 (1.5 SD) mm in the controls. The biopsies harvested from the test sites revealed that the new bone formed at 6 months was mineralized, mature and well structured. Particles of the grafted material could not be identified in any of the 10 test biopsies. The bone formed in the control sites was also mature and well structured.Conclusion: The results of this study indicate that alveolar bone resorption following tooth extraction may be prevented or reduced by the use of a bioabsorbable synthetic sponge of polylactide–polyglycolide acid. The quality of bone formed seemed to be optimal for dental implant insertion.

Notes: Aim: Haemangiopericytoma (HPC) represents approximately 3% of all tumours in the head and neck. This tumour is a soft tissue tumour derived from mesenchymal cells with pericytic differentiation. We present the clinicopathological findings of a case.Materials and Methods: A 69-year-old man was referred to our Department for a mass located on the right pre-molar maxillary gingiva; this mass caused problems during chewing, but was otherwise asymptomatic.Results: Clinical examination revealed a nodular, pink lesion, 3.5 cm in diameter, which was lined with normal mucosa. The lesion was mobile in relation to the deep and superficial tissues. Microscopic analysis of the neoplasm showed a vascular rich pattern, constituted by vessels covered with flat endothelium and surrounded by abundant spindly cells. On the basis of these histological and immunohistochemical findings, the final diagnosis was HPC.Conclusions: HPC is an uncommon vascular tumour for which the biological behaviour is difficult to predict. In our patient, no recurrences or distant metastases were present at a 4 years follow-up.

Notes: Bone neogenesis was studied in membrane-protected defects in a rabbit calvaria defect model using neutral, negatively, and positively charged titanium-reinforced GTAM membranes. Two standardized circular 8 mm wide and 1 mm deep defects were created in the calvaria of 36 rabbits leaving the inner cortex intact. The defects were subsequently covered with dome-shaped Ti-reinforced GTAM membranes stabilized with a titanium screw allowing the edges of the membranes to be closely approximated to the bone surface. The animals were divided into 6 groups of 6 rabbits each and were sacrificed at 5 days (Group l), 10 days (Group 2), 3 weeks (Group 3), 5 weeks (Group 4), 10 weeks (Group 5), and 20 weeks (Group 6). The distribution of the 72 membranes according to charge yielded 4 positively charged, 4 negatively charged and 4 neutral domes in each group. Histomorphometric analysis showed a more rapid and increased bone neogenesis with the negatively charged domes. A mean total area of 27.95% of newly-formed bone was observed in the negatively charged membrane sites at 10 days while negligible bone formation occurred with the neutral and positively charged domes at the same evaluation interval. Over time, negatively charged membranes supported more new-bone formation than neutral membranes while positively charged membranes showed the least new bone. This work demonstrates that negative electrical stimulation accelerates and maintains bone neogenesis. These results also suggest the potential applications of negatively charged GTAM membranes in clinical settings.

Notes: This study was designed to compare the regenerative potential at dehisced implant sites of the resorbable demineralized laminar bone sheets and non resorbable GTAM membranes. Twenty-six standard screw-type fixtures showing buccal dehiscences in 7 patients were treated using the GBR principles and received either laminar bone sheets (experimental) or GTAM (control) membranes. Twelve experimental and 10 control sites were available for evaluation at second stage surgery carried out 8 months following implant placement. Height and maximum width of the dchiscence defects were measured at the time of implant insertion and at second-stage procedure. Mean percentage of defect fill was 75.11% in the experimental dehiscences vwsus 86.70% in the control defects. A statistically significant difference in the percentage of defect fill could not be evidenced between the two treatment modalities. Complete till was observed in 25% of the experimental versus 70% of the control sites. A significant difference was found in the median Density Index with the GTAM group showing a consistency similar lo bone in a larger number of sites. Histologically, material with the same staining features of bone was evidenced inside the GTAM membranes in 3 cases while newly-formed bone was present in all instances under the control GTAM barriers. In ihe laminar bone-treated sites, the membrane maintained its integrity in almost all cases. Newly formed bone was found underlying the membrane in cases with a Density index of 5 with no evidence of bony tissue adhering to the laminar sheets.

Notes: Abstract: Surface implant modifications have been shown to have a relevant importance in modifying cell response. Expression profiling by DNA microarray is a new molecular technology that allows the analysis of gene expression in a cell system. By using DNA microarrays containing 19,200 genes, we identified in osteoblast-like cells line (MG-63) on new implant surface (nanoPORE, Out-Link, Sweden and Martina, Due Carrare, Padova, Italy), several genes whose expressions were significantly down-regulated. The differentially expressed genes cover a broad range of functional activities: (a) immunity, (b) vesicular transport (c) apoptosis and cell cycle regulation. It was also possible to detect some genes whose function is unknown. The data reported are, to our knowledge, the first genetic portrait of an implant surface. They can be relevant to better understand the molecular mechanism of implant osseointegration and as a model for comparing other materials.

Notes: In oral implantology, a 3–6 month stress-free healing period is presently accepted as a prerequisite to achieve bone apposition without interposition of a fibrous scar tissue. This protocol was introduced by Brånemark and co-workers in 1977. The aim of the present paper is to review the reasons that led Brånemark and collaborators to require long delayed loading periods. It is shown that the requirement for long delayed loading periods was drawn from the initiation and development periods of their original clinical trial. Demanding conditions were met involving simultaneously: 1) patients with poor bone quality and quantity, 2) non-optimized implant design, 3) short implants, 4) non-optimized surgical placement, 5) non-optimized surgical protocol and 6) biomechanically non-optimized prosthesis. Extrapolation of the requirement for long healing periods from these particular conditions to more standard situations involving refined surgical protocols and careful patient selection might be questioned. Albeit premature loading has been interpreted as inducing fibrous tissue interposition, immediate loading per se is not responsible for fibrous encapsulation. It is the excess of micromotion during the healing phase that interferes with bone repair. A threshold of tolerated micromotion exists, that is somewhere between 50 μm and 150 μm. It is suggested that loading protocols might be shortened through 2 different approaches. The first way would be to decrease stepwise the delayed loading period for free-standing implants below the presently accepted 3–6 months of healing. The second way would be to identify immediate loading protocols that are capable of keeping the amount of micromotion beneath the threshold of deleterious micromotion. Immediate loading protocols for implants-retained overdentures and fixed bridges are reviewed. It is shown that successful premature loading protocols require a careful and strict patient selection aimed to achieve the best primary stability. These various protocols need to be further documented in order to assess their predictability.