A novel blue light laser system for surgical applications in dentistry: evaluation of specific laser-tissue interactions in monolayer cultures.

OBJECTIVES: The objective of this study was to examine a new blue light diode laser system (445 nm) for dental soft tissue surgery on cellular level. MATERIALS AND METHODS: An in vitro cell culture model was established to evaluate the effects of the 445-nm diode laser in comparison to an established infrared diode laser (IR). Monolayer cell cultures were irradiated and wound healing was morphometrically measured. Fluorescence staining was used for proof of potential DNA double-strand breaks as well as cytoskeleton alterations. Cellular live/dead discrimination was performed and temperature development during laser irradiation was measured with a thermographic infrared camera. RESULTS: A characteristic zone formation was detected after irradiation with both wavelengths. Despite a larger wound area after irradiation with 445 nm, due to its higher temperature development, this laser system showed a faster wound healing in comparison to the IR laser. No increase of devitalized cells was documented with higher distances between laser tip and cell layer and thus without thermal interaction. Neither cytoskeleton alteration nor DNA double-strand breaks could be recorded after irradiation in non-contact mode. CONCLUSIONS: The blue diode laser system demonstrated an excellent direct thermal coupling to cells and tissues without side effects even by reduced power settings. CLINICAL RELEVANCE: The blue diode laser seems to be a promising technology for clinical application due to high absorption of blue light without major side effects in adjacent tissues even by reduced power settings.

In vitro biocompatibility of ICON(®) and TEGDMA on human dental pulp stem cells.

OBJECTIVES: Resin infiltrants have been successfully used in dental medicine preventing the progression of tooth decay in an early phase of caries development. ICON(®) is an infiltrant of low-viscosity which penetrates via dentinal tubules into the lesion in dependence of the demineralization depth. Hence, we performed an in vitro study to determine the effect of ICON(®) on human dental pulp stem cells (hDPSCs). METHODS: Using explant technique, primary hDPSCs were collected from extracted teeth. Characterization and isolation were performed with typical mesenchymal stem cell markers (Stro-1, CD73, CD90, CD105) and hDPSCs differentiation was validated by immunofluorescence and flow cytometry. HDPSCs were stimulated with light-cured ICON(®) (lc) and non-light-cured ICON(®) (nc) conditioned media as well as different TEGDMA concentrations followed by the analysis of cytotoxicity, pro- and anti-inflammatory responses and differentiation using XTT assay, RT-PCR and ELISAs, respectively. RESULTS: Initial analysis demonstrated that hDPSCs express characteristic mesenchymal stem cell markers and differentiate into adipocytes, chondrocytes and osteoblasts. Notably, ICON(®) nc dramatically reduced cell viability (up to 98.9% after 48h), whereas ICON(®) lc showed only a modest cytotoxicity (10%). Data were in line with cytokine expression demonstrating increased levels of IL-6 and IL-8 as well as decreased IL-10 after ICON(®) nc exposure compared to ICON(®) lc. ICON(®) lc caused almost no alterations of DSPP, whereas ICON(®) nc markedly elevated DSPP mRNA levels (130.3-times). A concentration-dependent effect was observed in TEGDMA challenged hDPSCs. SIGNIFICANCE: ICON(®) is a successful minimal invasive technique. However, clinicians should strictly follow manufacturer's instructions to prevent adverse effects.

[Not Available]. / Nouvelle procédure pour la réalisation de prothèses totales intégrée au flux de travail numérique

Compte tenu du développement démographique, il faut s'attendre à une augmentation du nombre de patients dépendants, à mobilité restreinte et présentant une perte de dents totale, de sorte qu'à l'avenir, les possibilités de réhabilitation dentaire efficientes et économiques présentent un grand intérêt. Dans ce contexte, les technologies CFAO (CAO/FAO) pourraient constituer des alternatives intéressantes au processus de fabrication conventionnel. Dans ce contexte, le Baltic Denture Sys-tem de Merz Dental a été testé dans le cadre d'une présentation de cas: une patiente a reçu successivement deux nouvelles prothèses complètes, la première conçue et réalisée dans le flux de travail conventionnel, et la deuxième en flux de travail numérique. Après la prise d'empreinte fonction­nelle et l'enregistrement de la relation intermaxillaire avec des dispositifs d'enregistrement prédéterminés ­ dans le sens de corps de prothèse simplifiés ­, les données ainsi obtenues ont été numérisées au laboratoire dentaire et transposées pour la réalisation des prothèses par un processus de fraisage à partir d'ébauches préfabriquées dans lesquelles les rangées de dents prothétiques sont déjà intégrées dans les corps de prothèse. Malgré certaines difficultés lors de la combinaison de la prise d'empreinte et de l'enregistrement occlusal, il a été possible de réaliser pour notre patiente de nouvelles «prothèses dentaires numériques¼ très satisfaisantes.