Evaluation of the DIAGNOdent method for detection and quantification of carious lesions : in vitro and in vivo studies

The sites most susceptible to dental caries are the occlusal surfaces and the margins of existing restorations. These are also the sites at which lesion detection by conventional methods is most unsatisfactory. There is a need in general dental practice for simple efficient methods of detecting and recording quantitative data about the presence and severity of caries at the most susceptible sites and monitoring lesion response to intervention.

Aim: The aim of the present thesis was to evaluate a new laser fluorescence-based device, DIAGNOdent, for detection and quantification of carious lesions on occlusal surfaces and around the margins of restorations under both in vitro and in vivo conditions.

Methods: Part I. DIAGNOdent and occlusal caries (papers I and IV) The performance of the DIAGNOdent instrument was compared with the Electronic Caries Monitor (ECM), a method based on electrical conductance measurement, for in vitro detection and quantification of occlusal caries. In paper IV, DIAGNOdent readings on teeth scheduled for extraction were recorded before and after extraction, and during storage of the extracted teeth for three months. Lesion depth was determined by histopathological analysis in both papers.

Part II. DIAGNOdent and secondary caries (papers II and III) Restored teeth were measured with DIAGNOdent along the margin of the restoration, under laboratory and clinical conditions. The restorations were then removed and visual-tactile examination was conducted by two observers. For the in vitro study, the teeth were hemisectioned and examined under a microscope.

Results: In vitro evaluation of DIAGNOdent for occlusal caries detection showed that DIAGNOdent had high reproducibility (ICC=0.97) and higher correlation with histopathological examination (r=0.93) than the ECM. For the clinical study on occlusal caries, t-test for dependent samples did not indicate any statistically significant differences between DIAGNOdent readings obtained intraorally, and after extraction, and from extracted teeth stored in thymol saline up to 3 months. The correlation coefficient ranged from 0.59 to 0.73.

For secondary caries detection, the clinical performance of DIAGNOdent in terms of sensitivity/specificity was lower than that in the in vitro study, (0.60/0.81 versus 0.77/0.81). Regarding ROC analyses, the Az values were 0.89 and 0.78, for DIAGNOdent under in vitro and in vivo conditions, respectively.

Conclusions: The results suggest that DIAGNOdent may be a valuable adjunct to conventional methods for detection of occlusal and secondary carious lesions. If properly applied and correctly interpreted, this technique would facilitate the detection of carious lesions on occlusal surfaces and around the margins of restorations, and allow the clinician to make more well-informed treatment decisions.

List of scientific papers

I. Bamzahim M, Shi XQ, Angmar-Mansson B (2002). Occlusal caries detection and quantification by DIAGNOdent and Electronic Caries Monitor: in vitro comparison. Acta Odontol Scand. 60(6): 360-4.
https://doi.org/10.1080/000163502762667397

II. Bamzahim M, Shi XQ, Angmar-Mansson B (2004). Secondary caries detection by DIAGNOdent and radiography: a comparative in vitro study. Acta Odontol Scand. 62(1): 61-4.
https://doi.org/10.1080/00016350310008526

III. Bamzhim M, Aljehani A, Shi XQ (2005). Clinical performance of DIAGNOdent in detection of secondary carious lesions. Acta Odontol Scand. [Accepted]
https://doi.org/10.1080/00016350510019621

IV. Zhang DQ, Bamzahim M, Yuan Y, Shi XQ (2005). In vivo and in vitro validation of DIAGNOdent for detection and quantification of occlusal caries. [Submitted]