New approach in paediatric dentistry: ultrasonic nondestructive evaluation of restorative dental materials. Experimental study.

AIM: The ultrasonic inspection is a non invasive method which is very developed in the industrial field, for the non-destructive evaluation of materials, and in the medical field, for the ultrasound diagnostic analysis. In paediatric dentistry the most widely used non- destructive evaluation is the X-ray technique. Radiographs are valuable aids in the oral health care of infants, children, adolescents, allowing dentists to diagnose and treat oral diseases that cannot be detected during a visual clinical examination. The aim of this in vitro study was to analyse the ultrasonic non-destructive evaluation (UT-NDE) technique to inspect both dental materials internal structure and the form and position of internal defects in order to obtain a diagnostic method, free of ionising radiations, in paediatric dentistry. Moreover the ultrasonic inspection (UT) could be a rapid method of diagnosis in uncooperative paediatric patients. MATERIALS AND METHODS: Study Design: Experimental samples were manufactured with the characteristics of a large composite or glass ionomer cement paediatric dental restoration, in terms of either size or operative technique used. Characteristics of the common restorations were analysed and reproduced in vitro, using the same operative conditions, also adding operative defects into some samples. All the samples were subjected to an innovative UT test using the pulse echo immersion scanning technique. Both C-scans and full volume scans were carried out during the experimental programme. To enhance the data obtained from the UT scan, a digital system (Ecus Inspection software) for signal detection, archiving, processing and displaying was used. RESULTS: UT images showed the presence of internal defects in the dental materials. It was also possible to inspect very thin discontinuity such as the one represented by the fluid resin. STATISTICS: In order to execute the statistical analysis, the values of electric voltage measured in five higher white points and in five higher grey points of the pictures pixels, were measured for each sample. Then, the average values and the standardised data were calculated. CONCLUSION: n In conclusion, the ultrasonic test could be a diagnostic non-invasive method in paediatric patients, capable to evaluate the quality of the restorative teeth filling, showing internal little defects. In vivo application of this diagnostic method should be developed.