Influence of Simulated Oral Conditions on Different Pretreatment Methods for the Repair of Glass-Ceramic Restorations

Optical properties of repaired additively manufactured resin composites and zirconia and subtractively manufactured ceramics: a comparative study of composite resins

OBJECTIVE

This study aims to examine color properties of repairs made with various composites on restorations produced through additive-manufactured resin composites (AM-RC) and zirconia (AM-Z) or subtractive manufacturing (SM) after coffee thermocycling (CTC).

MATERIALS AND METHODS

Disk-shaped specimens (Ø10 × 2 mm; N = 120) were fabricated using six different material groups: additively manufactured resin composite (AM-RC) materials (Crowntec [C], NextDent [ND]), additively manufactured zirconia (AM-Z) materials (Lithoz [LI], INNI-Cera [IN]), and subtractively manufactured (SM) materials (CEREC Tessera [ALD], Vita Enamic [EN]). Subsequently, each group was further subdivided into two subgroups (n = 10) based on the type of repair using two different composites resins: Clearfil Majesty Posterior (CL) (n = 60) and Filtek Z350 (FZ) (n = 60). Specimens underwent thermal cycling (CTC), consisting of 10,000 cycles between 5 °C and 55 °C. Color measurements were performed both before and after thermal cycling for all materials. Color discrepancies (ΔE00) and relative translucency parameters (RTPs) were calculated. Statistical analyses were conducted at a significance level of α = 0.05.

RESULTS

A one-way ANOVA of ΔE00 values between CL and FZ revealed a significant difference (P = 0.007), with FZ exhibiting higher ΔE00 values. Significant differences in ΔE00 values were also observed among IN, C, and ND after CTC (P < 0.05). ALD demonstrated the lowest amount color change (P < 0.05). LI and EN colors showed no significant difference (P = 0.75). Following CTC, C, ND, and IN colors matched CL. In contrast, ALD, EN, and L colors exhibited significant differences (P ≤ 0.050). FZ showed a poor color match with all AM and SM materials. Furthermore, significant differences in RTP values were identified for all specimens (P < 0.001), with LI having the highest RTP and IN the lowest (P < 0.001).

CONCLUSION

The optical properties of composite and ceramic materials, as well as their stability over time, are crucial for their durability. ALD demonstrated the most consistent color stability. While the CL repair composites experienced some color changes, these changes remained within acceptable limits. Additionally, the LI (AM-Z) material exhibited the highest level of translucency.

Repair protocols for indirect monolithic restorations: a literature review

Despite the advancements in indirect monolithic restorations, technical complications may occur during function. To overcome this issues, intraoral repair using resin composite is a practical and low-cost procedure, being able to increase the restoration's longevity. This review aimed to evaluate the need for repair and suggest a standardized repair protocol to the main indirect restorative materials. For this, studies were surveyed from PubMed with no language or date restriction, to investigate the scientific evidence of indirect monolithic restoration repair with direct resin composite. A classification to guide clinical decisions was made based on the FDI World Dental Federation criteria about defective indirect restorations considering esthetic and functional standards, along with the patient's view, to decide when polishing, repairing or replacing a defective restoration. Based on 38 surveyed studies, different resin composite intraoral repair protocols, that included mechanical and chemical aspects, were defined depending on the substrate considering resin-based, glass-ceramic or zirconia restorations. The presented criteria and protocols were developed to guide the clinician's decision-making process regarding defective indirect monolithic restorations, prolonging longevity and increasing clinical success.

Assessment of Sodium Diamine Fluoride (SDF) with Light Curing Technique: A Pilot Study of Antimicrobial Effects

Silver diamine fluoride (SDF) has been useful in clinical dentistry for the purpose of caries arrest and prevention. Although methods for the application of SDF are well-known among dental professionals, such as microbrush applications, few studies have explored the effect of light curing, which accelerates precipitation onto dentin, and whether this has any effect on the antimicrobial properties of SDF. To assess this technique, single (Streptococcus gordonii) and polymicrobial (mixed salivary) colonies were grown and plated using SDF applied to hydroxyapatite discs with and without treatment with curing light. Kirby-Bauer Zone of Inhibition assay results revealed no significant differences in the areas between the two treatment groups (SDF: 1.27 mm, SDF plus curing light: 1.25 mm), p = 0.887 in the single culture (S. gordonii) experiments. In addition, no significant differences were found between the two treatment groups (SDF: 1.26 mm, SDF plus curing light: 1.24 mm), p = 0.771 in the polymicrobial culture experiments. Although there may be specific properties associated with SDF induced following light curing, these differences do not appear to be associated with the antimicrobial properties affecting gram-positive or polymicrobial films.