Dental silicate ceramics surface modification by nonthermal plasma: A systematic review.

OBJECTIVES: Nonthermal atmospheric or low-pressure plasma (NTP) can improve the surface characteristics of dental materials without affecting their bulk properties. This study aimed to systematically review the available scientific evidence on the effectiveness of using NTP for the surface treatment of etchable, silica-based dental ceramics before cementation, and elucidate its potential to replace the hazardous and technically demanding protocol of hydrofluoric acid (HF) etching. METHODS: A valid search query was developed with the help of PubMed's Medical Subject Headings (MeSH) vocabulary thesaurus and translated to three electronic databases: PubMed, Web of Science, and Scopus. The methodological quality of the studies was assessed according to an adapted version of the Methodological Index for Non-Randomized Studies (MINORS). RESULTS: Thirteen in vitro study reports published between 2008 and 2023 were selected for the qualitative and quantitative data synthesis. The implemented methodologies were diverse, comprising 19 different plasma treatment protocols with various device settings. Argon, helium, oxygen, or atmospheric air plasma may significantly increase the wettability and roughness of silicate ceramics by plasma cleaning, etching, and activation, but the treatment generally results in inferior bond strength values after cementation compared to those achieved with HF etching. The technically demanding protocol of plasma-enhanced chemical vapor deposition was employed more commonly, in which the surface deposition of hexamethyl disiloxane with subsequent oxygen plasma activation proved the most promising, yielding bond strengths comparable to those of the positive control. Lack of power analysis, missing adequate control, absence of examiner blinding, and non-performance of specimen aging were common methodological frailties that contributed most to the increase in bias risk (mean MINORS score 15.3 ± 1.1). SIGNIFICANCE: NTP can potentially improve the adhesive surface characteristics of dental silicate ceramics in laboratory conditions, but the conventional protocol of HF etching still performs better in terms of the resin-ceramic bond strength and longevity. More preclinical research is needed to determine the optimal NTP treatment settings and assess the aging of plasma-treated ceramic surfaces in atmospheric conditions.

Laser-Doppler microvascular flow of dental pulp in relation to caries progression.

Pulpal blood supply can be measured noninvasively and objectively via laser-Doppler fluxmetry. The aim of the study was to measure and compare pulpal laser-Doppler (LD) flux values for permanent non-carious teeth and carious teeth with different degrees of caries progression. Conventional sensitivity tests were also conducted for a comparative analysis to clarify the difference between tooth sensitivity and vitality. Carious lesions were detected and assessed in 15 adult subjects using the International Caries Detection and Assessment System (ICDAS) criteria. Pulpal sensitivity of selected carious teeth (without previous prosthetic restoration or endodontic treatment) and suitable caries-free teeth were then tested with a cold stimulus and subsequently with a weak electric current, whereas their pulpal LD flux was recorded at a separate visit using individually designed silicone probe holders. The LD flux values for teeth with an ICDAS score 6 were significantly lower compared to the values for teeth with an ICDAS score 1 (p < 0.05). Pulpal LD flux values of teeth with active caries were significantly lower than those of teeth with solely inactive carious lesions (p < 0.05). The degree of agreement between sensitivity and vitality testing was fair within both of the pairs: cold test/LDF (κk = 0.232, p = 0.00) and electric test/LDF (κk = 0.354, p = 0.00). Pulpal LD flux measurement proved to be reliable in the pulp vitality assessment of carious and non-carious teeth and might improve the reliability of clinical decisions when used in addition to standard clinical diagnostic protocols.