The local anaesthetic effect of a dental laser prior to cavity preparation: a pilot volunteer study.

OBJECTIVES: It has been suggested that laser preconditioning can produce dental anaesthesia. This study aimed to assess the response of the dental pulp to laser preconditioning. METHODS: The effects of laser preconditioning, sham laser (negative control), and composite curing light (positive control) on the response of the dental pulp to electric pulp testing was investigated in this double-blind crossover trial with six volunteers. The Er,Cr:YSGG laser or curing light was shone on a premolar tooth in a sweeping motion for 30 seconds (in the sham treatment, the laser was not activated) in blindfolded volunteers subjected to a consistent aural stimulus. Treatment method at each visit was randomized and performed by a researcher not involved in pulp testing. Teeth were pulp tested twice initially by another member of the research team to get baseline readings, immediately following the treatment, and thereafter every two minutes for 10 minutes. Results were analyzed using analysis of variance and an independent-sample t-test. RESULTS: There were no significant differences in pulpal response between treatments (p>0.05). CONCLUSION: Laser preconditioning did not affect pulpal response as measured by an electronic pulp tester. Laser preconditioning did not result in any pain or noticeable symptoms for both teeth and soft tissues.

Smart materials in dentistry.

Most dental materials are designed to have a relatively 'neutral' existence in the mouth. It is considered that if they are 'passive' and do not react with the oral environment they will be more stable and have a greater durability. At the same time, it is hoped that our materials will be well accepted and will cause neither harm nor injury. This is an entirely negative approach to material tolerance and biocompatibility and hides the possibility that some positive gains can be achieved by using materials which behave in a more dynamic fashion in the environment in which they are placed. An example of materials which have potential for 'dynamic' behaviour exists with structures which are partly water-based or have phases or zones with significant water content and for which the water within the material can react to changes in the ambient conditions. Such materials may even be said to have the potential for 'smart' behaviour, i.e. they can react to changes in the environment to bring about advantageous changes in properties, either within the material itself or in the material-tooth complex. The controlled movement of water or aqueous media through the material may cause changes in dimensions, may be the carrier for various dissolved species, and may influence the potential for the formation of biofilms at the surface. Some of these issues may be closely interrelated. Clearly, materials which do not have the capacity for water transport or storage do not have the potential for this sort of behaviour. Some materials which are normally resistant to the healthy oral environment can undergo controlled degradation at low pH in order to release ions which may prove beneficial or protective. It is doubtful whether such behaviour should be classified as 'smart' because the material cannot readily return to its original condition when the stimulus is removed. Other materials, such as certain alloys, having no means of transporting water through their structure, can display smart behaviour by undergoing predictable changes in structure in response to applied mechanical or thermal stimuli. It has been difficult to harness such behaviour to the benefit of patients but progress in this area is slowly being made.