High-viscosity glass-ionomer cement or composite resin for restorations in posterior permanent teeth? A systematic review and meta-analyses.

OBJECTIVES: Answer the PICO question: Do class I and II posterior restorations in permanent teeth placed with high-viscosity glass-ionomer cement (HV-GIC) fail more than composite resin (CR) restorations? DATA: The study was registered in the PROSPERO database (CRD42020138290). Randomized and controlled clinical trials, comparing the performance of HV-GIC and CR in load bearing cavities of posterior permanent teeth were included. Cochrane risk of bias tool and GRADE were used to assess the quality and certainty of the evidence. Meta-analyses were performed for clinical outcomes on USPHS and FDI criteria for 12-, 24- and 36-months follow-ups. SOURCES: PubMed, Scopus and Web of Science were last searched on April 2, 2022, without language or date restrictions. Reference lists of primary studies and their related article link in PubMed were manually searched. STUDY SELECTION: Ten studies were included, while data from 8 were used for the meta-analyses. A total of 849 HV-GIC and 800 CR restorations were followed. The primary outcome was the fracture/retention of the restoration, with a comparable performance for both materials on all follow-ups. The 36 months follow-up for class I restorations (longest) showed risk difference of -0,00 (95%CI -0,03 to 0,03; p = 0,98) and no heterogeneity (p = 0,98, I2=0%). The certainty of the evidence is moderate, as all included studies were at an uncertain risk of bias. CONCLUSIONS: HV-GIC and CR presented comparable clinical performance in posterior permanent teeth up to 36 months. HV-GIV wear in class I restorations followed by 24 months was the only poorer result compared to CR. CLINICAL SIGNIFICANCE: Conservative load bearing cavities in permanent posterior teeth can be restored with HV-GIC with comparable clinical performance to CR expected at least up to 3 years. HV-GIC is a valuable direct restorative option for posterior teeth in high caries risk patients, in which CR is frequently associated with failure.

Effect of surface treatment and cement type on dentin bonding of processed resin composite.

PURPOSE: To examine the effect of surface treatment and cement type on dentin bonding of processed resin composite restorations. METHODS: Bovine incisors were sectioned to expose mid-dentin, and randomly assigned to four different groups: Group ULT, Lava Ultimate composite blocks were bonded to dentin with RelyX Ultimate; Group ULT-CJ was treated as in Group ULT but CoJet was used to treat the intaglio surface prior to bonding; Group UNC was bonded with RelyX Unicem 2; and Group UNC-CJ was treated as in Group UNC but CoJet was used to treat the intaglio surface. RelyX Unicem 2 was used as a self-adhesive resin cement, while RelyX Ultimate was used as an adhesive resin cement with Scotchbond Universal. All adhesives and resin composites were polymerized with a high-irradiance LED polymerizing light (Elipar DeepCure-S). After bonding, all specimens were kept in 100% humidity and 37°C for 7 days and then processed for microtensile bond strength (µTBS) testing (n=15). The failure mode was analyzed under SEM as cohesive, adhesive, or mixed. Data were analyzed for statistical significance using two-way ANOVA and Tukey's HSD post-hoc test (α=0.05). RESULTS: Mean µTBS values ranged from 8.83 MPa (±3.13 MPa) for UNC to 25.63 MPa (±5.94 MPa) for ULT-CJ. Means were statistically significantly higher for the adhesive cement when compared with the self-adhesive cement (P< 0.05), and, for the adhesive cement, CoJet resulted in statistically significantly higher means (P< 0.05). The number of pre-test failures was uniform across groups (n=2-4). Failures were predominantly adhesive and mixed. The adhesive resin cement RelyX Ultimate performed significantly better than the self-adhesive resin cement RelyX Unicem 2, and surface treatment with CoJet improved bond strengths of Lava Ultimate to dentin. CLINICAL SIGNIFICANCE: CoJet treatment and adhesive resin cements should be used when bonding laboratory/CAD-CAM processed resin composite restorations to dentin.

Prosthetic rehabilitation and management of an MTA-treated maxillary central incisor with root perforation and severe internal resorption.

Root canal perforation and root resorption are challenging clinical conditions to correctly diagnose and treat, especially when they occur in anterior teeth. This clinical report describes the computed tomography findings, endodontic treatment, prosthetic rehabilitation, and clinical outcome of an iatrogenic root perforation and internal resorption in a maxillary central incisor. The case management consisted of endodontic retreatment, periodontal surgery, and prosthetic rehabilitation. Gray mineral trioxide aggregate (MTA) was used to fill the resorption space and seal the perforation. The prosthetic treatment was performed with glass fiber-reinforced dowels and all-ceramic crowns. No signs or symptoms, including discomfort, pain, or esthetic defects were observed in 30 months of follow-up.

Unusual anatomy of a maxillary first molar with two palatal roots: a case report.

The success of endodontic therapy is based on good endodontic access, correct cleaning and shaping, and adequate root canal obturation. However, endodontic treatment is also dependent on a sound knowledge of the internal anatomy of human teeth, especially when anatomical variations are present. Certain anatomical changes may be present to varying degrees, and it is important to report these to improve the understanding and expertise of endodontic specialists. With this aim in mind, this study reports an example of a maxillary first molar showing unusual anatomy (four roots and six root canals) and describes the endodontic treatment that was employed.

Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics.

OBJECTIVE: To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). METHODS: Disks (Ø12 mm x 1.1mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(Ic)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. RESULTS: The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. SIGNIFICANCE: The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values.

Influence of leucite content on slow crack growth of dental porcelains.

OBJECTIVES: To determine the stress corrosion susceptibility coefficient, n, of seven dental porcelains (A: Ceramco I; B: Ceramco-II; C: Ceramco-III; D: d.Sign; E: Cerabien; F: Vitadur-Alpha; and G: Ultropaline) after aging in air or artificial saliva, and correlate results with leucite content (LC). METHODS: Bars were fired according to manufacturers' instructions and polished before induction of cracks by a Vickers indenter (19.6N, 20s). Four specimens were stored in air/room temperature, and three in saliva/37 degrees C. Five indentations were made per specimen and crack lengths measured at the following times: approximately 0; 1; 3; 10; 30; 100; 300; 1000 and 3000 h. The stress corrosion coefficient n was calculated by linear regression analysis after plotting crack length as a function of time, considering that the slope of the curve was [2/(3n+2)]. Microstructural analysis was performed to determine LC. RESULTS: LC of the porcelains were 22% (A and B); 6% (C); 15% (D); 0% (E and F); and 13% (G). Except for porcelains A and D, all materials showed a decrease in their n values when stored in artificial saliva. However, the decrease was more pronounced for porcelains B, F, and G. Ranking of materials varied according to storage media (in air, porcelain G showed higher n compared to A, while in saliva both showed similar coefficients). No correlation was found between n values and LC in air or saliva. SIGNIFICANCE: Storage media influenced the n value obtained for most of the materials. LC did not affect resistance to slow crack growth regardless of the test environment.