Diagnosing cavitated proximal lesions is important for therapeutic decisions. This clinical study aimed to determine the validity of laser fluorescence (LF) and near-infrared reflection (NIRR) techniques for detecting early proximal cavities.The study included 43 proximal surfaces in 15 females who had limited radiolucent lesions in their bitewing radiographs. The approximal areas of interest were assessed by DIAGNOdent Pen (LF) and the Proxi interchangeable head of VistaCam iX intraoral camera (NIRR). Finally, orthodontic separators were placed in the contact points to provide enough space between the teeth. The sensitivity, specificity, and accuracy of diagnosing cavitated proximal surfaces were calculated for LF and NIRR against direct visual and tactile examination as the reference standard.On the basis of the reference standard, 34 surfaces (79.1%) were not cavitated, whereas 9 surfaces (20.9%) were cavitated and in need of restoration. The sensitivity, specificity, and accuracy of LF were 44.4%, 61.8%, and 58%, and those of NIRR were 88.9%, 14.7%, and 30%, respectively.The VistaCam iX Proxi was more sensitive and DIAGNOdent Pen was more specific in detection of proximal cavities. However, none of the techniques was accurate enough to be recommended as a sole approach for proximal caries detection.LF showed an overall superior diagnostic performance to NIRR for diagnosing proximal cavitation in permanent posterior teeth. Within the limitations of this study, neither VistaCam iX Proxi nor DIAGNOdent Pen could be considered a suitable device for diagnosing proximal cavities.