The color-matching ability of single-shade universal composites in extracted human teeth.

OBJECTIVES: To evaluate the color-match with extracted natural teeth of three single-shade universal composites, a group-shade universal composite, and a highly translucent-shade conventional composite. METHODS: Twenty extracted human teeth were divided into light- and dark-shade groups (n = 10, LSG and DSG). A preparation was restored with the 3 single-shade universal composites, OMNICHROMA (OMC), Admira Fusion x-tra U (AFU), and Essentia U (ESU); a highly translucent-shade conventional composite, Tetric EvoCeram T (TEC-T); and two shades of a group-shade universal composite-Filtek Universal Restorative (FUR A1 and A4). Composites were photopolymerized, polished, and stored in water for 24 h. The ΔE00 value between the unprepared and restored surfaces was obtained using a spectrophotometer. Composite placement and measurements were repeated three times per tooth. Color differences were statistically analyzed with the within-between-subjects t-test and repeated-measures analysis of variance (ANOVA), followed by post hoc pairwise comparisons with a Bonferroni adjustment (α = 0.05). RESULTS: There were no statistically significant differences between OMC and FUR (A1 and A4). AFU and ESU showed significantly higher ΔE00 values than OMC and TEC-T (p < 0.05). Single-shade composites exhibited significantly higher ΔE00 values in the DSG than in the LSG except ESU (p < 0.05). None of the composites satisfied the criteria for an acceptable match (ΔE00 >1.8). CONCLUSION: OMC showed the same color matching ability as a group-shade universal composite. A highly translucent-shade conventional composite and OMC exhibited better color matching ability than other single-shade composites. Overall, single-shade universal composites performed better in lighter-shaded teeth. CLINICAL SIGNIFICANCE: Single-shade universal composites have the potential to reduce chair time by eliminating shade selection in cavities with lighter-shade teeth. Highly translucent incisal conventional composites also may be used if the appropriate shade of composite is not available.

Isolated effect of filler particle size on surface properties of experimental resin composites before and after toothbrush abrasion.

OBJECTIVE: This study aimed to isolate the relationship between filler size and the surface properties of roughness and gloss before and after toothbrush abrasion for experimental resin-based composites (RBCs) containing uniform spherical fillers. MATERIALS AND METHODS: Five experimental light-cured RBCs with different spherical filler sizes and three commercial RBCs were studied. Forty specimens were polished using silicon carbide papers. Gloss was measured after 0, 90, 180, and 360 min of simulated toothbrushing, and surface roughness was measured before and after 360 min of toothbrushing. Two-way ANOVA/Tukey's multiple comparison tests were used to compare the RBCs, and the correlation between particle size and surface roughness or gloss was also determined. RESULTS: After polishing and toothbrushing, RBCs with smaller fillers exhibited significantly higher gloss and lower surface roughness, and RBCs with larger fillers exhibited lower gloss and higher surface roughness. A significant correlation was found between filler particle size and gloss and surface roughness both before and after toothbrush abrasion. CONCLUSIONS: Gloss of RBCs containing fillers with larger particle sizes was significantly reduced. After toothbrushing abrasion, the surface roughness increased for all RBCs, except those containing the finest-sized fillers. The particle size of the filler is a critical determinant of the surface roughness and gloss of RBCs, after polishing and after toothbrushing. CLINICAL SIGNIFICANCE: Increased surface roughness caused by toothbrush abrasion reduces the gloss of resin-based composites. Resin-based composites containing finer fillers best maintain glossiness after routine tooth brushing.

Bond Strength of Two Resin Cements with Leucite-reinforced Ceramic Using Different Bonding Agents.

AIM: To compare the bond strength of two resin cements to leucite-reinforced ceramics using three different boding agents and evaluate the compatibility of bonding agents. MATERIALS AND METHODS: Twenty extracted sound human molars were sectioned horizontally 2-3 mm above the cementoenamel junction (CEJ). CAD/CAM ceramic blocks for inLab were also sectioned to create 4 mm thick and bonded to the dentin. The adhesive groups assigned were divided into four adhesive groups: Group I: Variolink II dual-cure resin cement and Scotchbond Multi-Purpose Plus adhesive, group II: Multilink Automix dual-cure resin cement and Multilink primers, group III: Multilink Automix and Clearfil SE bond 2 (CSE2) adhesive, group IV: Multilink Automix and CSE2 with light curing after adhesive application. Five specimens of each group were sectioned perpendicular to obtain six microsticks of 1 × 1 mm width from each sample. Microtensile bond strength data were expressed in MPa. Fracture modes (FrMs) analyzed for the surfaces were divided into six patterns. Microtensile bond strength data were statistically analyzed with one-way ANOVA and Tukey post hoc tests (α = 0.05). T-test was performed at the 5% significance level to analyze groups III and IV with and without light curing. RESULTS: Group I showed the highest µTBS average of 13.67 MPa, group IV showed 12.26 MPa, group III showed 12.15 MPa, and group II showed the lowest average of 10.84 MPa. No significant differences were found between the bonding agents. However, the six types of failure modes, although all observed, were characterized by the adhesive system: Type I: adhesive failure of laminated dentin and ceramic; type II: adhesive failure of laminated ceramic; type III: adhesive failure of laminated dentin; type IV: cohesive failure of luting agent; type V: cohesive failure of dentin, and type VI: mixed failure of adhesion and cohesion. As a result, the FrM most commonly observed was the adhesive failure at the luting cement-ceramic block interface. CONCLUSION: The combination of resin cements and bonding agents did not significantly affect the bond strength of CAD/CAM ceramic restorations and dentin. CLINICAL SIGNIFICANCE: Several universal bonding agents are currently available for direct and indirect bonding, and using the same bonding agent for direct and indirect restorations could simplify inventory and benefit routine clinical practice. How to cite this article: Aida N, Koi K, Amaya-Pajares SP, et al. Bond Strength of Two Resin Cements with Leucite-reinforced Ceramic Using Different Bonding Agents. J Contemp Dent Pract 2023;24(11):859-863.

Development and maintenance of surface gloss of dental composites after polishing and brushing: Review of the literature.

OBJECTIVE: To describe the effect of the composites' composition to produce high surface smoothness/gloss using finishers/polishers, and to assess maintained smoothness/gloss under toothbrush abrasion. MATERIALS AND METHODS: PubMed papers published from January 01, 2000 to September 01, 2021 were included, and keywords used were: filler particle size, shape, amount of dental composites; finishing/polishing, gloss/roughness, and toothbrush abrasion of composites. Seventy-five in-vitro studies were included in this literature review. Forty-six articles assessed filler particle size/composition/shape and distribution to obtain high gloss/smoothness on different formulations; and the finishers/polishers effect on these materials. Twenty-nine papers assessed toothbrush abrasion of composites. RESULTS: Suprananofill/nanofill/microfills typically showed the smoothest and glossiest surfaces compared to nanohybrid, microhybrid and hybrid composites. Microfill (0.04-0.07 µm, 71-88 GU); suprananofill (0.001-0.8 µm, 52-92 GU), microhybrids (0.05-0.35 µm, 35-95 GU) and nanohybrids (0.05-0.21 µm, 66-97 GU). Composites with small, spherical particles tend to show smoother, glossier surfaces and more wear resistant compared to resin composites with larger or irregular particles. Several studies showed higher roughness and reduced gloss after toothbrush abrasion. CONCLUSIONS: Within the limitations of this study, suprananofill/nanofill/microfill composites tended to show the smoothest/glossiest surfaces due to smaller particle size. Composites with small, spherical particles tended to show smoother/glossier surfaces. Overall, toothbrush abrasion showed higher surface roughness and reduced gloss. CLINICAL SIGNIFICANCE: Suprananofills/nanofills/microfills had good polishability and polish retention due to their smaller particle size. The effectiveness of a polishing system is material-dependent. In general, Enhance-PoGo, Sof-Lex discs, and Sof-Lex Spiral wheels showed similar level of smoothness.

Intramedullary injury combined with osteoporosis therapeutics regulates targeted local osteogenesis.

Bone marrow ablation prompts transient bone formation in nearly the entire medullary cavity before marrow regeneration occurs. Here, we establish a procedure to direct bone formation in a desired particular site within the medullary cavity for support of biomedical devices. Local intramedullary injury was performed in the tibiae of rats and parathyroid hormone (PTH), alendronate, or saline was administered. Newly generated bone in the medulla was assessed by micro-CT and histology. To evaluate the function of newly generated bone, animals received intramedullary injury in tibiae followed by daily PTH. At day-14, implants were placed in the endocortical bone and the bone response to the implants was assessed. The fate of newly generated bone was compared with and without implants. We found that neither intramedullary injury nor medication alone resulted in bone formation. However, when combined, substantial bone was generated locally inside the diaphyseal medulla. Newly formed bone disappeared without implant placement but was retained with implants. Bone was especially retained around and between the implants. This study found that local bone marrow disruption followed by PTH or alendronate generated substantial cancellous bone locally in the diaphyseal medulla. This approach offers promise as a tissue engineering tool in medicine and dentistry.

Distinctive tooth-extraction socket healing: bisphosphonate versus parathyroid hormone therapy.

BACKGROUND: Patients with osteoporosis who receive tooth extractions are typically on either oral bisphosphonate or parathyroid hormone (PTH) therapy. Currently, the consequence of these therapies on hard- and soft-tissue healing in the oral cavity is not clearly defined. The aim of this study is to determine the differences in the therapeutic effect on tooth-extraction wound healing between bisphosphonate and PTH therapies. METHODS: Maxillary second molars were extracted in Sprague Dawley rats (n = 30), and either bisphosphonate (zoledronate [Zol]), PTH, or saline (vehicle control [VC]) was administered for 10 days (n = 10 per group). Hard-tissue healing was evaluated by microcomputed tomography and histomorphometric analyses. Collagen, blood vessels, inflammatory cell infiltration, and cathepsin K expression were assessed in soft tissue using immunohistochemistry, quantitative polymerase chain reaction, and immunoblotting. RESULTS: Both therapies significantly increased bone fill and suppressed vertical bone loss. However, considerably more devital bone was observed in the sockets of rats on Zol versus VC. Although Zol increased the numbers of blood vessels, the total blood vessel area in soft tissue was significantly smaller than in VC. PTH therapy increased osteoblastic bone formation and suppressed osteoclasts. PTH therapy promoted soft-tissue maturation by suppressing inflammation and stimulating collagen deposition. CONCLUSION: Zoledronate therapy deters whereas PTH therapy promotes hard- and soft-tissue healing in the oral cavity, and both therapies prevent vertical bone loss.

Effect of zoledronate on oral wound healing in rats.

PURPOSE: Osteonecrosis of the jaw (ONJ) is a growing concern in patients who receive bisphosphonates that target osteoclasts. As osteoclasts play multifunctional roles in the bone marrow, their suppression likely affects bone homeostasis and alters wound healing of the jaw. The objective was to delineate the impact of osteoclast suppression in the bone marrow and wound healing of the jaw. EXPERIMENTAL DESIGN: Zoledronate was administered to senile rats for 14 weeks. A portion of the gingiva was removed to denude the palatal bone. Gene expression in the bone marrow was assessed and histologic sections were analyzed to determine the wound healing status. RESULTS: Angiogenesis-related genes, CD31 and VEGF-A, were not altered by zoledronate. VEGF-C, which plays a role in lymphangiogenesis, was suppressed. There was a decrease in gene expression of Tcirg1 and MMP-13. Bone denudation caused extensive osteocyte death indicative of bone necrosis. In zoledronate-treated rats, the necrotic bone was retained in the wound while, in controls, osteoclastic resorption of the necrotic bone was prominent. Even though large necrotic bone areas existed in zoledronate-treated rats, overlaying soft tissue healed clinically. Immunohistochemical staining showed rich vascularity in the overlaying soft tissue. CONCLUSIONS: Zoledronate therapy impacts bone marrow by suppressing genes associated with lymphangiogenesis and tissue remodeling, such as VEGF-C and MMP-13. Zoledronate was associated with impaired osseous wound healing but had no effect on angiogenic markers in the bone marrow or soft tissue wound healing. Zoledronate selectively blunts healing in bone but does not affect soft tissue healing in the oral cavity.