The influence of three different Erbium:YAG pulse energies on the microleakage of Class V compomer restorations

Summary. Objectives. To investigate the influence of three Erbium:YAG pulse energies (200 mJ, 240 mJ, and 300 mJ with a 100 mJ dentine finish) on the microleakage of Class V compomer restorations (Compoglass). Design. In vitro study Sample and methods. Sixty-one extracted human premolar teeth were randomly allocated to three groups (according to pulse energy). Each tooth hosted one test cavity prepared with one of the three Er:YAG pulse energies using a pulse repetition rate of 5 Hz and a pulse duration of 250 s, and one control cavity prepared with a conventional diamond bur in a high-speed hand piece. Both cavities were placed at the cervical margin of the tooth and were restored and finished according to the manufacturer’s instructions. Each tooth was then stored in 0·12% thymol solution at 37 °C for three months, before being thermocycled through water baths between 5 °C and 55 °C for 240 cycles. Microleakage was assessed using a methylene blue dye penetration technique and was quantified using a score 0 (none) to 4 (to and into the axial wall). The data was analysed using the Kruskal–Wallis and Mann–Whitney U-tests. Results. Leakage was seen in all groups at both the dentine and enamel margins. There were no statistically significant differences in leakage (P < 0·05) at either the enamel or dentine margins, except for the 240 mJ lased enamel margins. This group performed significantly better than the enamel margins prepared with 200 mJ (P = 0·03) and the 300/100 mJ (P = 0·01) laser energies as well as the conventionally prepared enamel margins (P < 0·001). Conclusion. Cavity preparation with this Erbium:YAG laser did not influence the microleakage of Compoglass restorations adversely. Different pulse energies were required for optimum cavity sealing at the enamel and dentine margins and for different materials

Removal of partially erupted third molars using an erbium (Er): YAG laser: a randomised controlled clinical trial

We compared Erbium (Er):YAG laser with a surgical bur for removal of partially erupted lower third molars. Patients were randomised to be treated by either laser or bur. A total of 42 patients (laser=22; bur=20) were treated. A greater reduction in the range of mouth opening was found after laser than after bur treatment. Postoperative pain was more common after bur treatment. The duration of operation was considerably longer with laser than with bur. No persistent complications were encountered

Development of fibre-optic confocal microscopy for detection and diagnosis of dental caries”

We report on the development of a fibre-optics-based confocal imaging system for the detection and potential diagnosis of early dental caries. A novel optical instrument, capable of recording axial profiles through caries lesions using single-mode optical fibres, has been developed. The practical study illustrates that miniature confocal devices based around single-mode optical fibres may provide additional diagnostic information for the general dental practitioner

Fibre-optic confocal microscopy of early caries lesions

No abstract available

Automated laser registration and quantitative assessment of articular cartilage for computer assisted orthopaedic surgery

Over the last decade Computer Assisted Orthopaedic Surgery (CAOS) has emerged particularly in the area of minimally invasive Uni-compartmental Knee Replacement (UKR) surgery. Image registration is an important aspect in all computer assisted surgery including Neurosurgery, Cranio-maxillofacial surgery and Orthopaedics. It is possible for example to visualise the patient's medial or lateral condyle on the tibia in the pre-operated CT scan as well as to locate the same points on the actual patient during surgery using intra-operative sensors or probes. However their spatial correspondence remains unknown until image registration is achieved. Image registration process generates this relationship and allows the surgeon to visualise the 3D pre-operative scan data in-relation to the patient's anatomy in the operating theatre. Current image registration for most CAOS applications is achieved through probing along the articulating surface of the femur and tibial plateau and using these digitised points to form a rigid body which is then fitted to the pre-operative scan data using a best fit type minimisation. However, the probe approach is time consuming which often takes 10–15 minutes to complete and therefore costly. Thus the rationale for this study was to develop a new, cost effective, contactless, automated registration method which would entail much lesser time to produce the rigid body model in theatre from the ends of the exposed bones. This can be achieved by taking 3D scans intra-operatively using a Laser Displacement Sensor. A number of techniques using hand held and automated 3D Laser scanners for acquiring geometry of non-reflective objects have been developed and used to scan the surface geometry of a porcine femur with four holes drilled in it. The distances between the holes and the geometry of the bone were measured using digital vernier callipers as well as measurements acquired from the 3D scans. These distances were measured in an open source package MESHLAB version 1.3.2 used for the interpretation, post-processing and analysis of the 3D meshes. Absolute errors ranging from of 0.1 mm to 0.4 mm and the absolute percentage errors ranging from 0.48% to 0.75% were found. Additionally, a pre-calibrated dental model was scanned using a 650 nm FARO™ Laser arm using the global surface registration approach in Geomagic Qualify package and our 3D Laser scanner. Results indicate an average measurement error of 0.16 mm, with deviations ranging from 0.12mm to −0.13 mm and a standard deviation of 0.2 mm. We demonstrated that by acquiring multiple scans of the targets, complete 3D models along with their surface texture can be developed. The overall scanning process, including time required for the post-processing of the data requires less than 20 minutes and is a cost-efficient approach. Moreover, the majority of that time was used in post processing the acquired data which could be potentially reduced through the use of bespoke application software. This project has provided proof of concept for a new automated, non-invasive and cost efficient registration technique with the potential of providing a quantitative assessment of the articular cartilage integrity during lower limb arthroplasty

Fibre optic confocal microscopy of early caries lesions

Examines instances of fibre optic confocal microscopy of early caries lesions

Application of a novel confocal imaging technique for the early detection of dental decay

In order to stop or prevent the progression of dental disease, early detection and quantification of decay are crucially important. Dental decay (caries) detection methods have traditionally involved clinical examination by eye, using probes and dental radiography, but up to 60% of lesions are missed. What the dentist requires is a cheap, reliable method of detection of early disease, ideally with information on the depth and rate of growth or healing. Conventional commercial scanning confocal microscopes are unsuitable for use on dental patients. We report on a fibre optic based confocal microscope designed for in vivo examination of caries lesions. The system utilizes a common fibre both as the source and to detect the reflected confocal signal. The initial system has been optimized using dielectric mirrors and the thickness of the stack has been measured with high precision. Dental samples have been examined and the system has been demonstrated to provide information on the depth and mineral loss of a lesion. Fibre optic microscopy (FOCM) demonstrates a practical route to developing an in vivo caries profiler. In this paper, the FOCM and its applications in caries detection are described and the potential of this scheme as a practical dental probe is discussed

Blue laser diode excited fluroescence spectroscopy of natural caries lesions

We report on the use of a blue laser diode to excite natural fluorescence from a range of dentalsamples. Sixty teeth with naturally occurring lesions were examined. The lesions were classified onvisual inspection as falling into three classes as shiny lesions, dull lesions and brown lesions. Theresulting fluorescence was then examined using a fibre optically coupled spectrometer in a series ofwavelength bands. By examining the intensity ratios in the two wavelength bands 480-500nm and620 to 640nm we were able to classify the lesion types and thus provide a quantifiable measurementof lesion types. This method has application for detection of dental caries as well as demonstratingpotential application to evaluate lesions which may represent different degrees of caries activity

Fluorescence spectroscopy of natural carious lesions

We report on the use of a blue laser diode to excite natural fluorescence from a range of dental samples. Sixty teeth with naturally occurring lesions were examined. The lesions were classified onvisual inspection as falling into three classes as shiny lesions, dull lesions and brown lesions. The resulting fluorescence was then examined using a fibre optically coupled spectrometer in a series ofwavelength bands. By examining the intensity ratios in the two wavelength bands 480-500nm and620 to 640nm we were able to classify the lesion types and thus provide a quantifiable measurementof lesion types. This method has application for detection of dental caries as well as demonstrating potential application to evaluate lesions which may represent different degrees of caries activity

Fluorescence spectroscopy of natural carious lesions

No abstract available