Laser-induced autofluorescence of caries

Abstract

The laser induced autofluorescence from carious regions of human teeth was studied using a krypton ion laser at 407 flirt as excitation source, a fiberoptical detection system combined with a polychromator and an optical muLtichannel analyzer. In addition, time.resolved and time-gated fluorescence measurements in the nanosecond range were carried out. It was found that carious regions contain different fluorophores which emit in the red spectral range. The emission spectra with maxima around 590 nm, 625 nm and 635 nm are typical for metalloporphyrins, copro-and protoporphyrin. During excitation the fluorescence was bleached. Non-carious regions showed a broad fluorescence band with a maximum in the short-wavelength spectral region with shorter fluorescence decay times than the carious regions. Therefore, caries can be detected by spectral analysis of the autofluorescence as well as by determination of the fluorescence decay times or by time-gated imaging.

Micro-computerized tomography assessment of fluorescence aided caries excavation (FACE) technology: comparison with three other caries removal techniques

“…13 In another study, Lennon et al compared FACE with CME and found that FACE left less bacterially infected dentine after excavation than CME. 35 They concluded that FACE is more effective at removing infected dentine without significantly increasing cavity size when compared to CE. The relative cavity volume (MIP) of FACE in their study was 3, which is similar to our result of 3.19.…”

“…Various researchers have used histology to characterize the bacteria left after caries excavation using the FACE technology. 18 After application of the FACE method to excavate caries, teeth sections were evaluated for the presence of bacteria in the dentin tubules using light microscopy 19,35 or laser-scanning confocal microscopy. 18,20 Those studies confirmed that the FACE method removes more caries-affected tissue than CE or caries dye.…”

“…22,23 This red autofluorescence of caries and dental plaque is believed to be caused by porphyrins and metalloporphyrins synthesized by oral microorganisms. 35 Porphyrins and metalloporphyrins typically have absorption maxima between 398 and 421 nm and emission maxima between 530 and 633 nm. 24 Because porphyrins are produced by bacterial metabolic activity, the red fluorescence intensity reflects the intensity and extent of the caries-affected tissues.…”

Optical clearing of biological tissues: prospects of application in medical diagnostics and phototherapy

“…The porphyrin molecules are also endogenic phosphors, the content of which in cells considerably increases under some pathologic conditions. Besides, some bacteria, causing, e.g., the inflammation diseases of skin [239] and gums [240], inhabiting the caries tooth lesions [241], can accumulate considerable amounts of porphyrins. Combining the measured autofluorescence spectra with those of reflection and absorption, OCT and other optical methods allows the diagnostics of caries and tooth tissue demineralisation [241][242][243][244][245], skin cancer [246,247], and pre-cancer changes of cervical tissue [248], mammary gland [249], and other diseases.…”

Diagnóstico Fotodinâmico: Princípios E Aplicações

“…O tecido dentário saudável não apresenta bandas de emissão no vermelho, assim, somente o tecido cariado irá fluorescer. Os espectros de excitação e emissão das lesões de cárie são típicos de porfirinas, principalmente da protoporfirina IX, a possível fonte de porfirina no tecido cariado é a biossíntese bacteriana que ocorre no local (KONIG et al, 1998). HAMISHAKI et al (2014) realizaram um estudo comparativo entre a inspeção visual realizada por dentistas com experiência clínica e um aparelho de fluorescência a laser (DIAGNOdent®) para diagnosticar a cárie dentária secundária.…”