Marc Bolla

Scanning Electron Microscopy Analysis of Experimental Bone Hacking Trauma

The authors report on their macro- and microscopy study of bone lesions made by a sharp force instrument (a single blade knife), and a sharp-blunt instrument classified as a chopping weapon (a hatchet). The aim of this work was to attempt to identify the instrument by analyzing the general class characteristics of the cuts. Each weapon was used on human bones. The results indicate that macroscopic analysis is more problematic. The microscopic analysis assessed that characteristics examined were effective in distinguishing sharp from sharp-blunt injury to the bone. The microscope facilitates analysis unachievable with macroscopic methods, some three-dimensional characteristics not visible to the naked eye being clearly defined with its use. Emphasis has been placed on the value of SEM as an anthropologists tool in bone lesion injuries.

In vitro action of Bordeaux red wine on the microhardness of human dental enamel

Several studies have demonstrated that the regular and large consumption of wine is associated with increased risk of tooth erosion. Here, the effect of Bordeaux red wine on enamel was estimated by measuring changes in its Vickers microhardness. Thirty premolars were used; microhardness tests were performed on buccal areas before and after 10, 30, 90 and 120 s immersion in the wine (pH=3.9). Enamel surfaces were also observed by scanning electron microscopy. No statistically significant difference was found between the mean Vickers microhardness obtained at t=0 and 90 s, but slight signs of enamel demineralisation were observed with the scanning electron microscope. It appears that wine has no disastrous effect on the microhardness of dental enamel when the two are in contact for less than 90 s. When the exposure is for at least 120 s, it may become harmful, as the decrease in the microhardness of enamel was then significant (P<0.05).

Experimental Single Controlled Study of Burned Bones: Contribution of Scanning Electron Microscopy

Burned bones were studied using Scanning Electron Microscopy. The samples were cut from a maxillary-mandibular block taken during an autopsy. These fragments were heated in a furnace under controlled temperature conditions for 60 minutes. The temperatures ranged from 150 to 1150 degrees Celsius. The results are as following: (i) there are significant alterations of the bone, more and more obvious as the temperature increases, (ii) it appears to be difficult to establish a precise correlation between the temperature and the scanning electron microscopy patterns.

Removal of Thermafil root canal filling material.

The aim of this study was to evaluate if removal of Thermafil plastic carriers and reestablishment of working length were possible in single rooted teeth filled with the Thermafil system. Twenty freshly extracted maxillary central incisors were prepared and filled with #30 Thermafil plastic obturators according to manufacturers recommendations. Teeth were divided in two groups: Group I: 10 teeth were retreated using dimethylformamide as a solvent. Group II: 10 teeth were retreated using chloroform as a solvent. Removal of filling material was performed manually using K files and H files alternately between carrier and dentinal walls. The average time needed to remove the plastic carrier was 7 min for group I and approximately 6 1/2 min for group II. No deformation of the plastic carrier was observed after removal from the canal. Removal of plastic carriers and measurement of the proper working length were easily performed using manual endodontic instruments. Chloroform greatly enhanced this procedure.

Scanning electron microscopy analysis of experimental bone hacking trauma of the mandible.

The authors report on a macroscopic and microscopic study of human mandible bone lesions achieved by a single-blade knife and a hatchet. The aim of this work was to complete the previous data (scanning electron microscopy analysis of bone lesions made by a single-blade knife and a hatchet, on human femurs) and to compare the lesions of the femur with those of the mandible. The results indicate that the mandible is a more fragile bone, but the features observed on the mandible are quite similar to those previously observed on the femur. This work spells out the main scanning electron microscopy characteristics of sharp (bone cutting) and blunt (exerting a pressure on the bone) mechanisms on human bone. Weapon characteristics serve to explain all of these features.

Dental Materials and Implants

Understanding the mechanisms of everyday processes, such as eating and cleaning, can help dentists and oral surgeons fi nd the optimal methods for maintaining healthy teeth. In recent times, the use of dental implants has become an everyday occurrence and the complex loading of these needs to be established within the laboratory environment. Dental adhesives, amalgams, porcelains, polymers and ceramics undergo testing in vitro to determine their performance and suitability in a clinical situation. Dental implants are fatigue tested to determine their long term performance and ensure they will provide years of pain-free, useful service. Here are a small sample of our solutions for testing of dental materials and implants. Repeatability Reliability Ease of Use Reduced Maintenance

Physicochemical and mechanical approaches to dentine/resin adhesive interface

Abstract The aim of this study is to determine the influence of different characteristic parameters of the human dentine surface on the interaction between dentine and adhesive resin. The dentine surface of 21 freshly extracted teeth (from patients between the ages of 13 and 77 years old) was treated with Total Etch (Vivadent etching gel) and characterised by three methods: Vickers microhardness (for mechanical characterisation); wettability (in order to characterise the dentine and adhesive interactions using the drop angle); optical and electron microscopy with image analysis (for microstructural characterisation). The average number and diameter of the tubules on the surfaces were calculated. Then 21 stubs of Z100 restorative (3M dental products) were bonded on the dentine substrate of these teeth using Syntac Sprint (Vivadent). The shear bond strength (Instron universal testing machine) at a crosshead speed of 0·5 mm s-1 was determined. Shear bond strength and microhardness increases with the age of the tooth. The shear bond strength decreases with the per cent surface area, and average number of tubules. The wettability angle increases with the number of tubules and the per cent surface area of tubules. The results were analysed with the use of Spearman Rank. The explanation of the wettability behaviour is very complicated and it is necessary to take into account the evolution of the resin adhesive viscosity over time. The originality in this work is that the physicochemical characterisation and mechanical study were carried out on the same tooth. The fact that no significant statistical correlation is found between dentine, its specific parameters, and the shear bond strength can be explained by the observation of fracture surfaces using SEM in combination with EDX analysis. This shows some very heterogeneous fractures, from adhesive resin interfacial fracture to cohesive fractures in the adhesive resin or restorative composite resin. This work demonstrates that the dentine resin adhesive interface is highly complex. It depends not only on the superficial parameters of the dentine but also on the physicochemistry of the resin and the adherence test parameters.