Different finish-line designs have been advocated for tooth preparations of ceramic crowns. However, scientific evidence is lacking to help clinicians make a proper selection.
The purpose of this ...systematic review and meta-analysis was to evaluate the effects of finish-line designs on the marginal and internal adaptations of ceramic crowns.
This report follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The literature search was conducted in MEDLINE via the PubMed, Embase, and Web of Science databases with no publication year or language limits. In vitro studies comparing the marginal and internal adaptations of ceramic crowns with rounded shoulder and chamfer finish lines were included in the meta-analysis.
Sixteen studies were included in the qualitative synthesis and meta-analyses. Statistical analyses were conducted using the Review Manager Software. Meta-analyses were performed with random-effects models (α=.05). Ceramic crowns with rounded shoulders exhibited significantly better marginal adaptation than those with chamfers (P<.001; mean difference=−7.8; 95% confidence interval=−11.6 to −4.1). Moreover, ceramic crowns with chamfers exhibited significantly better internal adaptation than those with rounded shoulders (P=.020; mean difference=35.0; 95% confidence interval=6.5 to 63.5).
The difference in marginal adaptation of ceramic crowns using 2 finish-line designs was small, and the clinical significance was low, whereas the results of internal adaptation favored the chamfer finish line.
Abstract This study aims to evaluate the effects of etching with sulfuric acid (SA) and vinyl sulfonic acid (VSA) on the bond strength between a light-curing indirect resin composite and ...polyetherketoneketones (PEKK). PEKK specimens were ground with 600 silicon carbide papers, etched with 90% SA for 5 s (90-5 SA) or 95% VSA for 30 s (95-30 VSA), and then modified with a phosphate primer ; afterward, a light-curing resin composite was veneered on the specimens. Two control groups were also prepared without etching (unetched/unprimed and unetched/primed). After 20,000 thermocycles in water at 4 and 60℃, the shear bond strengths of the specimens were determined and subjected to a nonparametric (Steel-Dwass) test (α=0.05, n=8). The etched surfaces were observed by scanning electron microscopy (SEM) at 2000x magnification. Higher bond strengths were obtained when the PEKK surface was etched with 90-5 SA or 95-30 VSA (90-5 SA/unprimed 24.3 +- 4.3 MPa, 90-5 SA/primed 26.2 +- 3.2 MPa, 95-30 VSA/unprimed 23.7 +- 2.5 MPa, 95-30 VSA/primed 24.3 +- 4.1 MPa), and these values were not statistically different, whereas the two control groups exhibited significantly lower bond strengths (unetched/unprimed 12.2 +- 1.7 MPa, unetched/primed 9.5 +- 2.7 MPa). SEM observations revealed that 95-30 VSA led to a microporous (felt-like) surface, which was different from the surface structure etched with 90-5 SA. Etching the PEKK surface with SA or VSA significantly improved the bond strength between resin composite and PEKK in contrast with the application of the phosphate primer. Appropriate chemical etching could be a useful option when fabricating prostheses using PEKK-based materials and indirect resin composites.
There is limited information about denosumab-related osteonecrosis of the jaw (DRONJ), unlike bisphosphonate-related ONJ (BRONJ). The mode of action is clearly different between denosumab and ...bisphosphonates. DRONJ occurs mainly following tooth extraction in cancer patients treated with the combination of denosumab and other drugs including chemotherapy. However, DRONJ animal models similar to these clinical situations have not been developed. The aims of this study were to 1) create a new model of high-prevalence chemotherapy/anti-RANKL antibody-related ONJ-like lesions to mimic patients receiving a denosumab/chemotherapy combination; and 2) compare the histopathological and immunopathological findings in the early stages of BRONJ-like and anti-RANKL antibody-related ONJ-like lesions. Cyclophosphamide (CY) and anti-mouse RANKL monoclonal antibody (mAb) or zoledronate combination therapy (CY/mAb and CY/ZA, respectively) was performed to create ONJ-like lesions in female C57BL/6J mice. Both maxillary first molars were extracted at 3 weeks after drug administration. The animals were euthanized at either 2 or 4 weeks after tooth extraction. Increased necrotic bone and empty lacunae with decreased living bone and osteocyte numbers were common histopathological findings in CY/mAb- and CY/ZA-induced impaired wound healing at 4 weeks after tooth extraction, and they were diagnosed as ONJ-like lesions based on validation of BRONJ and DRONJ in humans. In areas of impaired healing at 2 weeks post-extraction, decreases in angiogenesis and F4/80+LYVE-1− macrophages were noted as common immunopathological findings, although anti-angiogenesis was worse with CY/mAb than with CY/ZA. Interestingly, CY/mAb did not reduce F4/80+LYVE-1+ cells and normal lymphangiogenesis remained, whereas CY/ZA profoundly suppressed the larger size of F4/80+LYVE-1+ cells, similar to vessels with a concomitant decrease in lymphangiogenesis. Therefore, the distribution of the larger size of F4/80+LYVE-1+ cells differed in the early stages between different antiresorptive-induced ONJ-like lesions in conjunction with lymphangiogenesis, although the histopathological findings were similar. These findings suggest that the pathogenesis of BRONJ and DRONJ may differ due to the distributions of F4/80+LYVE-1+ tube-like-structured cells.
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•Cyclophosphamide (CY)/anti-RANKL antibody (mAb)-related osteonecrosis of the jaw (mAb-ONJ) model mice were created.•mA monotherapy profoundly inhibited angiogenesis in the tooth extraction sockets.•Histopathology was similar in mAb-ONJ-like and bisphosphonate-related ONJ (BRONJ)-like lesions.•Immunopathology was clearly different in the early stages between mAb-ONJ-like and BRONJ-like lesions.
This study was conducted to evaluate the effects of ceramic microbeads on the bond strength between resin and zirconia. Microbeads made of zirconia (TZ) and zircon (ZS) were treated with and without ...hydrofluoric acid (HF). The microbeads were sintered to zirconia disks using intermediate feldspathic porcelains. Two control groups, NB (without microbeads) and AS (without porcelain and microbeads), were also prepared. All specimens were treated with a phosphate primer and veneered with a light-curing resin composite. The 24-h shear bond strengths were determined and analyzed by the Tukey-Kramer test (α=0.05, n=10). The TZ-HF specimen exhibited the highest bond strength, followed by TZ, ZS-HF, ZS, AS, and NB. Scanning electron microscopy observations revealed that the TZ-HF specimen had a complicated debonded surface, and it included microconcavities where the microbeads were detached. Sintering etched zirconia beads onto a zirconia framework with feldspathic porcelains is useful for bonding layered resin composite materials.
Denosumab-related osteonecrosis of the jaw (DRONJ), which mainly occurs in cancer patients receiving anti-receptor activator NF-kappaB ligand (RANKL) antibody, reduces oral health-related quality of ...life. However, the exact mechanisms of and definitive treatment strategies for DRONJ remain unknown. We hypothesized that cessation of denosumab heals and/or ameliorates DRONJ, since it is a protein-based antibody agent, although stopping denosumab should be avoided in clinical situations. Therefore, the aims of this study were: 1) to create a healing and/or amelioration murine model of DRONJ-like lesions induced by chemotherapy/anti-RANKL antibody (mAb) combination therapy and tooth extraction; and 2) to investigate histopathology and immunopathology in the extraction sockets by comparing the murine model of DRONJ-like lesions with the amelioration/healing model of DRONJ-like lesions. Eight-week-old, female C57B/6J mice received chemotherapeutic drug (cyclophosphamide: CY) and mAb combination therapy (CY/mAb) with tooth extraction. Open wounds were sustained in CY/mAb-treated mice at 2 and 4 weeks post-extraction. Impaired socket healing was diagnosed as CY/mAb-related ONJ-like lesions at 3 weeks post-extraction in this study. Next, mAb was discontinued for 2 and 4 weeks after diagnosis of CY/mAb-related ONJ-like lesions. mAb cessation for 2 weeks induced partial osseous wound healing and significantly improved soft tissue wound healing of the extraction sockets. Anti-angiogenesis and normal lymphangiogenesis with CY/mAb combination therapy was not changed by mAb discontinuation. However, mAb cessation for 2 weeks significantly increased the number of CD38+F4/80+ M1 and CD163+F4/80+ M2 macrophages, which significantly increased the M2/M1 ratio in the connective tissue of extraction sockets. No direct effects of mAb on macrophages were noted both in vivo and in vitro. Therefore, the developed healing and/or amelioration murine model of CY/mAb-related ONJ-like lesions is a useful tool to investigate the histopathology and immunopathology of DRONJ in humans. Dynamic polarization shifting from M1 to M2 macrophages induced by mAb cessation may play an important role in wound healing, rather than angiogenesis and lymphangiogenesis, in DRONJ.
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•Anti-RANKL antibody (mAb) cessation reduced cyclophosphamide (CY)/mAb-related osteonecrosis of the jaw-like lesions in mice.•mAb cessation did not affect anti-angiogenesis or lymphangiogenesis in the extraction sockets.•Dynamic polarization shifting from CD38+F4/80+ M1 to CD163+F4/80+ M2 macrophages was induced by mAb cessation.•mAb monotherapy did not directly affect macrophage polarization.
Objective
The aim of this comprehensive systematic review and meta‐analysis was to investigate the pathology and pathogenesis of medication‐related osteonecrosis of the jaw (MRONJ) in rodents.
...Background
Medication‐related osteonecrosis of the jaw occurs in patients taking antiresorptive drugs, such as bisphosphonates and denosumab, and anti‐angiogenesis agents. However, there is limited information about the pathology of MRONJ at the clinical level. Moreover, no information about the exact mechanisms of MRONJ is clinically available.
Materials and methods
The PubMed, SCOPUS and Medline databases were used to search for relevant articles up to April 2018 by two independent reviewers. A systematic review and meta‐analysis were performed.
Results
Of the 1841 studies, 10 articles met the eligibility criteria. The most commonly observed pathology of MRONJ‐like lesions was exposed bone without epithelial coverage, decreases in the number of osteocytes and increases in necrotic bone with more empty lacunae. No definitive pathogenesis of MRONJ‐like lesions was found. Both zoledronic acid (ZA) monotherapy and ZA/chemotherapeutic and/or dexamethasone combination therapy were significant high‐risk factors for developing MRONJ‐like lesions (P < 0.00001 and P < 0.0001, respectively).
Conclusion
Based on rodent studies, common pathological findings were extracted in bisphosphonate‐related ONJ (BRONJ)‐like lesions, whereas no definitive pathogenesis was identified. There is no information about the pathology and pathogenesis of denosumab‐related ONJ. These findings clearly suggest that accumulation of scientific evidence based on animal studies is absolutely necessary to explore the pathology and pathogenesis of MRONJ in humans. ZA administration would be a significant risk factor for developing BRONJ‐like lesions.
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The aim was to investigate the effect of groove designs on bone quality under controlled-repetitive load conditions for optimizing dental implant design. Anodized Ti-6Al-4V alloy ...implants with −60° and +60° grooves around the neck were placed in the proximal tibial metaphysis of rabbits. The application of a repetitive mechanical load was initiated via the implants (50N, 3Hz, 1800 cycles, 2days/week) at 12weeks after surgery for 8weeks. Bone quality, defined as osteocyte density and degree of biological apatite (BAp) c-axis/collagen fibers, was then evaluated. Groove designs did not affect bone quality without mechanical loading; however, repetitive mechanical loading significantly increased bone-to-implant contact, bone mass, and bone mineral density (BMD). In +60° grooves, the BAp c-axis/collagen fibers preferentially aligned along the groove direction with mechanical loading. Moreover, osteocyte density was significantly higher both inside and in the adjacent region of the +60° grooves, but not −60° grooves. These results suggest that the +60° grooves successfully transmitted the load to the bone tissues surrounding implants through the grooves. An optimally oriented groove structure on the implant surface was shown to be a promising way for achieving bone tissue with appropriate bone quality. This is the first report to propose the optimal design of grooves on the necks of dental implants for improving bone quality parameters as well as BMD. The findings suggest that not only BMD, but also bone quality, could be a useful clinical parameter in implant dentistry.
Although the paradigm of bone quality has shifted from density-based assessments to structural evaluations of bone, clarifying bone quality based on structural bone evaluations remains challenging in implant dentistry. In this study, we firstly demonstrated that the optimal design of dental implant necks improved bone quality defined as osteocytes and the preferential alignment degree of biological apatite c-axis/collagen fibers using light microscopy, polarized light microscopy, and a microbeam X-ray diffractometer system, after application of controlled mechanical load. Our new findings suggest that bone quality around dental implants could become a new clinical parameter as well as bone mineral density in order to completely account for bone strength in implant dentistry.
Background and objective
There are a few experimental models that clearly describe the pathological differences in tissue destruction between periodontitis and peri‐implantitis. We recently reported ...that the formation of immune complexes accelerates site‐specific loss of attachment and alveolar bone resorption when an antigen is topically applied in the gingival sulcus of an immunized rat. We applied this model to the peri‐implant tissues and compared peri‐implant destruction to periodontitis without using a ligature.
Material and methods
Twenty‐five rats were used in this study and were divided into five groups. Implantation was performed immediately after extraction of right first molars in rats. The left first molars were left untreated to be examined as natural teeth. The immunized group consisted of rats that had received intraperitoneal lipopolysaccharide (LPS), whereas the nonimmunized group received only phosphate‐buffered saline (PBS). The untreated baseline group received only implantation. After intraperitoneal booster injection, half of each group received topical application of LPS in the palatal gingival sulcus daily for 3 days. The other half of the groups received PBS. Histopathological and histometrical findings were observed with hematoxylin and eosin staining, collagen fibers were observed with Azan staining, and formation of immune complexes was immunohistologically evaluated by C1qB expression.
Result
Peri‐implant tissue destruction was greater in the immunized and LPS‐applied groups than in the other groups. No periodontal destruction was observed. Formation of immune complexes was observed in the junctional epithelium and adjacent connective tissue in the immunized groups.
Conclusion
Antigen‐induced peri‐implant tissue destruction occurs faster than periodontal tissue destruction.
Osteonecrosis of the jaw (ONJ), which is a rare but severe adverse effect, mainly occurs in oncology patients receiving chemotherapeutic agents and bisphosphonates. However, the combined impact of ...chemotherapy and bisphosphonates on wound healing after tooth extraction remains unknown. The aim of this study was to determine the precise etiology of ONJ induced by chemotherapy and bisphosphonate combination therapy. Mice received zoledronate (ZA) monotherapy, cyclophosphamide (CY) monotherapy or CY/ZA combination therapy. The maxillary first molars were extracted 3 weeks after the initiation of drug treatment. Moreover, antivascular endothelial growth factor A (VEGFA) monoclonal antibody (mAb) was administered once every 2 days just after tooth extraction for 2 weeks. Soft and hard tissue wound healing was evaluated 2 and 4 weeks post-extraction using histomorphometry, microcomputed tomography and immunohistochemistry. ZA monotherapy did not induce impaired oral wound healing and ONJ-like lesions 2 and 4 weeks post-extraction, respectively. Tooth extraction socket healing worsened with severe anti-angiogenesis by CY monotherapy and CY/ZA combination therapy 2 weeks post-extraction. However, CY monotherapy rarely induced ONJ-like lesions with severe angiogenesis suppression, whereas CY/ZA combination therapy frequently induced ONJ-like lesions with severe angiogenesis inhibition 4 weeks post-extraction. Interestingly, anti-VEGFA mAb therapy delayed osseous wound healing with normal soft tissue wound healing of tooth extraction sockets, although this therapy significantly suppressed blood vessel formation. Our findings suggest that anti-angiogenesis alone is not the main cause of ONJ-like lesions induced by CY/ZA combination therapy. The combination of suppressed osteoclasts and anti-angiogenesis, in addition to other risk factors such as chemotherapy, may contribute to the development of ONJ.
Summary
Since the initial description of medication‐related osteonecrosis of the jaw (MRONJ) almost two decades ago, the potential pathophysiology and risk factors have been elaborated on in many ...investigations and guidelines. However, the definitive pathophysiology based on scientific evidence remains lacking. Consequently, the optimal clinical treatment and prevention strategies for MRONJ have not been established. Despite their different mechanisms of action, many drugs, including bisphosphonates, denosumab, angiogenesis inhibitors, and other medications, have been reported to be associated with MRONJ lesions in cancer and osteoporosis patients. Importantly, MRONJ occurs predominantly in the jawbones and other craniofacial regions, but not in the appendicular skeleton. In this up‐to‐date review, the currently available information and theories regarding MRONJ are presented from both clinical and basic science perspectives. The definition and epidemiology of MRONJ, triggering medication, and histopathology are comprehensively summarized. The immunopathology and the potential pathophysiology based on immune cells such as neutrophils, T and B cells, macrophages, dendritic cells, and natural killer cells are also discussed. In addition, antiangiogenesis, soft tissue toxicity, necrotic bone, osteocyte death, and single‐nucleotide polymorphisms are examined. Moreover, other possible mechanisms of MRONJ development are considered based on the unique embryological characteristics, different cell behaviors between jawbones and appendicular skeleton, unique anatomical structures, and sustained bacterial exposure in the oral cavity as a basis for MRONJ site specificity. Based on the literature review, it was concluded that multiple factors may contribute to the development of MRONJ, although which one is the key player triggering MRONJ in the craniofacial region remains unknown.
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