Laser Spectroscopy Offers Prospect for Dental Surgery

Any kind of medical, surgical or dental intervention aims for a successful treatment with a little as possible stress for the patient including a low complication rate, good healing and preserving the anatomical structures as much as possible. Laser-based instruments appear to be the ideal tool, as they offer a number of advantages over the conventional approach. The coagulation of blood-vessels coming along with the ablation process allows for a dry and clear operating field. Several studies report of good postoperative soft tissue healing and only little swelling of laser wounds when compared to conventional surgery. One major drawback, however, is the lack of haptic feedback for the surgeon. As the actual penetration depth of the surgical laser is unknown, critical structures under or near the focus spot are prone to iatrogenic damage. Several structures in especially the oral cavity are already prone to damage in the conventional surgical procedures and it is important to notice that laser shots, even low energy ones, may just as well lead to irreparable alterations on the nerve tissue. An analytical method that determines what kind of tissue is being removed at the bottom of the cut may help prevent damaging important anatomical structures during a laser-surgery procedure.

Experimental LIBS measuring setup (Image: Wiley, Rohde)

One such analytical method is laser-induced breakdown spectroscopy, LIBS. In LIBS, a short laser pulse is used to generate plasma from a sample’s surface. The emissions from this plasma can then be analyzed with a spectrometer to determine the elemental composition of the targeted sample and in this way LIBS is able differentiate between several tissues when limiting the sample range to either the hard- or soft tissue class. In a new study a team of scientists from the Clinical Photonics Lab in Erlangen, Germany tested out the LIBS method on tissues that might be encountered in surgical or dental procedures in the oral cavity. Using LIBS, the classification of ex-vivo porcine oral soft and hard tissues was successfully demonstrated. Three soft tissues (oral mucosa, peripheral nerve, dental pulp) and four hard-tissues (cortical bone, cancellous bone, enamel, dentine), all related to the oral cavity, were examined for their elemental composition, and an emission-intensity-ratio based differentiation approach was attempted.

The results of this study suggest that, although the elemental composition of the samples is very similar within the respective soft- or hard tissue classes, the different quantitative distribution of their constituent elements can be used for a highly accurate tissue differentiation. The team paid special attention to the critical cortical-bone:cancellous-bone tissue pair and the differentiation between those tissues surrounding the mandibular and lingual nerve. “In addition, the differentiation between the dental tissues illustrates a prospect towards future tissue guided preparation of teeth” says team member Maximilian Rohde. The method used is reliable and reproducible and is meant to establish a baseline for later in-vivo experiments concerning a LIBS based feedback-control of surgical laser systems. (Source: CPL)

M. Rohde et al.: The differentiation of oral soft- and hard tissues using laser induced breakdown spectroscopy – a prospect for tissue specific laser surgery, J. Biophotonics 10 (10), 1258-1269 (2017); DOI_ 10.1002/jbio.201600153.

Link: Clinical Photonics Lab, Erlangen, Germany

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