The effect of acid etching on remineralization of incipient caries lesions : a micro-ct study

Indiana University-Purdue University Indianapolis (IUPUI)Etching of enamel caries lesions has been demonstrated to enhance remineralization. However, this effect reaches a plateau after a period of time. This study aimed at investigating the effectiveness of additional acid etching on remineralization. Forty 1 mm × 2 mm human enamel blocks with chemically induced artificial incipient lesions were used. Ten specimens were randomly selected at the end of demineralization for transverse microradiography (TMR) analysis. The remaining specimens were then divided into three groups (n = 10). Group A was remineralized by a pH cycling system with 1100 ppm sodium fluoride for 20 days. In group B, the specimens were etched with 35-percent phosphoric acid for 30 s and then remineralized. Group C was remineralized by same procedure as group B plus and given an additional acid etch after 10 days of remineralization. Mineral density was measured by x-ray microtomography (µ-CT). The volumetric mineral content [VM (µm3×105)] was determined between 91 and 0-wt%. The µ-CT % mineral recovery (%) was calculated using the formula 100×(remineralize VM - demineralization VM) / (sound VM - demineralization VM). One-hundred-μm sections of demineralized and remineralized specimens were used to assess the mineral loss (IML: vol%×µm) and lesion depth (µm) using TMR. The three groups showed no significant difference in mineral change or mineral content for µ-CT or TMR lesion depth. The TMR IML showed a significant difference between the demineralized specimens and the three remineralized groups. The correlation between TMR IML and TMR lesion depth was 0.66 (p < 0.0001). The µ-CT percent mineral recovery from demineralization was correlated with neither TMR IML nor TMR lesion depth. When evaluated with µ-CT, the twice-acid-etched group presented lower mineral gain values than the group etched only once with acid. Also, the twice-etched group presented lower mineral gain and greater TMR IML compared with the non-acid etch group. TMR images revealed reduction of surface layer in the acid-etched groups, especially in the twice-etched group, in which significant reduction or loss of surface layer occurred. Based on these results, we conclude that additional acid etching with 35-percent phosphoric acid does not enhance remineralization compared with a single application of acid etching. We believe that the viable existence of the surface layer is essential for remineralization of the lesion. Further investigations into the accuracy of µ-CT to detect minute mineral changes in incipient caries lesions are probably needed

Current Novel Caries Diagnostic Technologies: Restorative Dentists’ Attitude and Use Preferences

Early detection of caries lesions is key to a successful restorative dental treatment plan. The aim of this study was to investigate the preferences and attitude of graduate restorative dentistry residents (RDRs) regarding novel caries diagnostic technologies (NCDT) and to provide a brief overview of available technologies for both specialized and general dental practice. This cross-sectional study used an online questionnaire (17 questions) concerning RDRs’ attitude, preferences, and insights regarding five available NCDTs. It was distributed among twenty RDRs at a local government dental school following a review session about NCDTs. Collected responses were analyzed statistically using one-way analysis of variance (ANOVA), chi-squared with Bonferroni correction, and Kruskal-Wallis tests at a 0.05 significance level. Sixty-five percent of RDRs reported an interest in NCDTs as a discussion topic and almost half of them were positive towards their use, however, sixty percent of respondents were hesitant to diagnose caries solely using NCDTs. Fiber-optic-transillumination (FOTI) systems were ranked the best overall and with regard to all the investigated criteria (p &lt; 0.05). Chosen reasons for FOTI included price followed by ease of use. In general, high price rated as the most perceived reason for not choosing a given NCDT followed by low practical applicability. Meanwhile, ease of use followed by relevant application ranked as the main reported reasons to choose an NCDTs

The effect of thermal aging on flexural strength of CAD/CAM hybrid and polymeric materials

The field of dentistry is consistently innovating with the introduction of novel hybrid and polymer materials for computer-aided design and manufacturing (CAD/CAM). It is noteworthy that the temperature within the oral cavity has a significant impact on the strength of new biomaterials utilized for CAD/CAM fabrication of fixed partial dentures (FPDs). Studies have demonstrated that alterations in intraoral temperature may significantly affect the longevity and durability of dental restorative materials. This study aimed to evaluate the flexural strength, flexural modulus, and effect of thermal aging on CAD/CAM restorative materials. Five CAD/CAM materials were investigated: nano-ceramic-hybrid (GR), polymer-infiltrated-ceramic-network (VE), polyether-ether-ketone (PK), fiberglass-reinforced epoxy-resin (CT), and Feldspar Ceramic (VB). A total of 100 bar-shaped specimens were prepared (N = 20). Each group was subdivided into thermocycling (TC) and no-thermocycling (NTC) subgroups (n = 10). All the specimens underwent a 3-point bending test. The mean flexural strengths and moduli were statistically analyzed using paired t-test, analysis of variance (ANOVA), and Bonferroni pair-wise comparison (p < 0.05). Significant differences were observed in the flexural strength (FS) and modulus (E) between the materials (p < 0.001). GR had the highest FS among tested hybrid materials. NTC CT had the highest FS (924.88 ± 120.1 MPa), followed by GR (385.13 ± 90.73 MPa), then PK (309.56 ± 46.84 MPa). The FS of brittle ceramic VB was the lowest (p < 0.001), but similar to that of PICN VE. Only resin-containing VE and CT significantly decreased in E after thermocycling (p < 0.01, p = 0.013), showing the softening effect of thermocycling on their resin matrix. It can be concluded that new hybrid materials (GR) had higher flexural strength than feldspar ceramic and other resin/polymeric CAD/CAM materials. Polymeric PEEK and GR hybrid materials were resistant to significant deleterious effects of TC. Therefore, they would be appropriate for situations with a higher stress load

Mechanical Properties of Three-Dimensional Printed Provisional Resin Materials for Crown and Fixed Dental Prosthesis : A Systematic Review

The emergence of digital dentistry has led to the introduction of various three-dimensional (3D) printing materials in the market, specifically for provisional fixed restoration. This study aimed to undertake a systematic review of the published literature on the Mechanical Properties of 3D- Printed Provisional Resin Materials for crown and fixed dental prosthesis (FDP). The electronic database on PubMed/Medline was searched for relevant studies. The search retrieved articles that were published from January 2011 to March 2023. The established focus question was: “Do provisional 3D-printed materials have better mechanical properties than conventional or milled provisional materials?”. The systematically extracted data included the researcher’s name(s), publication year, evaluation method, number of samples, types of materials, and study outcome. A total of 19 studies were included in this systematic review. These studies examined different aspects of the mechanical properties of 3D-printed provisional materials. Flexural Strength and Microhardness were the frequently used mechanical testing. Furthermore, 3D-printed provisional restorations showed higher hardness, smoother surfaces, less wear volume loss, and higher wear resistance compared to either milled or conventional, or both. 3D-printed provisional resin materials appear to be a promising option for fabricating provisional crowns and FDPs.Dentistry, Faculty ofNon UBCOral Biological and Medical Sciences (OBMS), Department ofReviewedFacult