The application of microscopic surgery in dentistry

The use of the microscope as a tool for practising Medicine, especially in surgical specialisations, has been established for decades. The microscope was first used in OdontologyDentistry back to the 1970s and 1980s, and was introduced more widely (although it was still far from being in general use) during 1990s. The purpose of this article is to describe the main applications of the microscope in OdontologyDentistry today, as well as providing odontologists and stomatologists, whether specialists or in general practice, with information about microscopic OdontologyDentistry for better patient care. This work also gives particular importance to matters needed to achieve the necessary manual dexterity to work in a magnified operating field using a surgical microscope (SM).     

Gingival neurofibroma in a neurofibromatosis type 1 patient

Neurofibroma is a benign peripheral nerve sheath tumour. It is one of the most frequent tumours of neural origin and its presence is one of the clinical criteria for the diagnosis of type 1 neurofibromatosis (NF-I). Neurofibromatosis type 1 is an autosomal dominantly inherited disease due to an alteration in the long arm of chromosome 17. About 50% of NF-I patients have no family history of the disease. NF-I patients have skin lesions (cafe au lait spots and neurofibromas) as well as bone malformations and central nervous system tumours. Diagnosis is based on a series of clinical criteria. Gingival neurofibroma in NF-I is uncommon. Treatment of neurofibromas is surgical resection. The aim of this paper is to report a case of NF-I with gingival involvement and to review the literature.     

How is the biocompatibilty of dental biomaterials evaluated?

All biomaterials used in dentistry must be evaluated for biocompatibility using screening assays to protect patient health and safety. The purpose of this review is to explain the international biocompatibility guidelines, and to explain the structure of a test program. The test program requires the structured assessment of materials into four phases; general toxicity, local tissue irritation, pre-clinical, and clinical evaluation. Different types of screening assays are available, and it is important to understand the advantages and limitations of the various types of assays that are available, so that they can be selected for appropriateness and interpreted accurately. New scientific advances in terms of the chemical properties of dental materials, tissue engineering, stem cell, genetic transfer, biomaterial, and growth factor therapies are under development. These new therapies create improved opportunities to restore and regenerate oral tissues, but they can also present new hazards to patients. Prior to their clinical use, these new technologies must be proven to be safe, and not hazardous to human health. A structured biocompatibility assessment and advice on the selection of assays are outlined to evaluate these new therapies.     

Bone defect formation during implant placement following alveolar distraction

PURPOSE: This retrospective study was designed to evaluate the volume of hard tissue generated at the time of implant placement in distracted alveolar bone. MATERIALS AND METHODS: All patients who underwent distraction osteogenesis between 2000 and 2003 were included. The preoperative bone height, amount of distraction performed, and presence or absence of complications affecting implant placement were recorded. The augmentation achieved was correlated with insufficient bone formation using the Spearman correlation and the Fisher exact test. RESULTS: The study included 43 implants placed in 17 cases of alveolar distraction. Of the 34 implants placed in bone augmented by 4.5 to 6.5 mm, bone defects were observed with 12. All 9 implants placed in ridges augmented by 7 to 10.5 mm demonstrated a bone defect. The "defect" and "no-defect" implant groups differed significantly with respect to preoperative bone height and amount of distraction performed (P < .001 for both). Significantly more defects were formed in bone augmented by > 25% compared to bone augmented by < 25% (P < .001). CONCLUSIONS: When considering distraction osteogenesis, augmentation of up to 25% of the initial bone height seems more predictable and less likely to be associated with complications at the time of implant placement. In distractions greater than 25% of the original height, additional treatment should be considered.     

Hydrolytic stability of composite repair bond

The hydrolytic stability of composite repairs is a desirable property. In the present study, the composite repair microtensile bond strength, failure mode distribution, and nanoleakage occurrence before and after thermocycling were evaluated. Standardized, 1-month-old composite substrates were roughened, cleaned, and randomly assigned to seven groups according to the intermediate agent applied. Resin-based, silane-based, and combined silane/adhesive coupling agents were investigated. The same resin composite as the substrate was used for repair. For each group, repaired samples were wet stored for 24 h (37 degrees C) or thermocycled (5,000 cycles, 5-55 degrees C). Failure mode and silver nitrate penetration were examined by stereomicroscopy. Intermediate agent, experimental condition, and their interaction were significant factors. Hydrophobic flowable composites resulted in statistically higher repair strengths, lower occurrence of adhesive failures, and good quality interfacial coupling without any silver uptake in both conditions. Light-curing, hydrophilic resin monomer-based intermediate agents, although not affected by thermocycling, showed a more pronounced silver penetration. The composite repair strength of a self-curing silane/adhesive agent was significantly affected by thermal stresses, despite the absence of silver uptake. A prehydrolized silane agent recorded the lowest repair strength, with minimal or no evidence of interfacial silver impregnation after thermocycling. In conclusion, flowability and hydrophobic nature can be considered important properties when selecting intermediate agents for composite repair.     

Periodontal and oral microbiological status of an adult population undergoing haemodialysis: a cross-sectional study

OBJECTIVES: The aim of this cross-sectional study was to evaluate the periodontal status and oral microbiological patterns of a population with end-stage renal disease (ESRD), undergoing haemodialysis (HD). DESIGN: This was a cross-sectional study, involving 52 patients from the Nephrology Department and 52 matched control subjects. MATERIALS AND METHODS: The subjects had a periodontal clinical examination; subgingival plaque samples were taken and analysed using a semiquantitative polymerase chain reaction (PCR) test to detect Porphyromas gingivalis, Tannerella forsythia, Prevotella intermedia, Prevotella nigrescens and Actinobacillus actinomycetemcomitans. Subgingival plaque and saliva samples were studied for Candida and Enterobacteriaceae. MAIN OUTCOME MEASURES: Most of the 104 subjects had some degree of loss of periodontal attachment (LPA) > or =3 mm [11 (10.5%) had severe LPA; 16 (15.4%) moderate LPA; and 64 (61.5%) mild LPA]. Only 13 subjects (12.5%) presented good periodontal health. Results: No statistically significant differences were found between the HD patients and the control group regarding bleeding index, number of teeth, or percentage of LPA > or =3 mm. However, a statistically significant difference was seen in the degree of oral hygiene. CONCLUSIONS: On the basis of the findings presented here, we cannot associate ESRD with more severe periodontal destruction. Although HD patients presented a higher number of periodontopathic microorganisms than the matched controls, a prolonged duration of HD did not bear a statistically significant relationship with the percentage of sites with LPA > or =3 mm, specific microbiota or composition of biofilm.