Surface roughness and optical characteristics evaluations after chairside adjustment of different zirconia types.

STATEMENT OF PROBLEM: Limited evidence is available for the effect of chairside adjustment using rotary cutting instruments on the surface roughness and optical properties of different zirconia types. PURPOSE: To evaluate the effect of simulated adjustments on surface roughness and optical properties of different zirconia types. MATERIALS AND METHODS: Three Partially Stabilized Zirconia (PSZ) types based on mole percent yttria (Y) concentration from the same manufacturer (Katana; Kuraray) were used: 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ. Thirty disk-shaped specimens (Ø14 × 1.2 mm) from different zirconia types (N = 90) were prepared. Specimens were either left without adjustment (NA), adjusted with Dialite ZR finishing and polishing system (Brasseler) (APol), or adjusted with course diamond instruments only (ADia). The specimens were distributed into 9 groups (n = 10): Group 3Y-PSZ/NA, Group 3Y-PSZ/APol, Group 3Y-PSZ/ADia, Group 4Y-PSZ/NA, Group 4Y-PSZ/APol, Group 4Y-PSZ/ADia, Group 5Y-PSZ/NA, Group 5Y-PSZ/APol, and Group 5Y-PSZ/ADia. The surface roughness of specimen was analyzed using an Atomic Force Microscope (AFM) (Bruker's Dimension Icon, Bruker) and Root Means Square (RMS) were recorded (nm). Surface Gloss (SG), Translucency Parameter (TP), and Contrast Ratio (CR) values of all groups were recorded using an integrating sphere spectrophotometer. Statistical analysis was performed using analysis of variance (ANOVA) and Tukey's multiple comparison tests for pairwise comparisons at p < 0.05 and 95% confidence interval. RESULTS: APol had no effect on the surface roughness (p = 0.88) while ADia had a significant negative effect (p < 0.05) despite the type of zirconia. Out of the three testes optical properties, only SG was negatively affected by ADia for all types of zirconia (p < 0.05). The two adjustment types did not affect the TP of all the tested zirconia (p = 0.91). The CR was not affected by the tested adjustments for all zirconia types (p = 0.726). CONCLUSION: Proper zirconia adjustment following a sequence of burs and polishers can maintain acceptable roughness and optical properties. Adjustment of zirconia with rough diamond can lead to deleterious effects and should be avoided. CLINICAL SIGNIFICANCE: Chairside adjustment of zirconia could lead to rougher surface and unpredictable changes of surface gloss. Therefore, zirconia adjustment should be minimized to the greatest extent possible and a proper protocol should be followed if had to be done.

Saliva exposure reduces gingival keratinocyte growth on TiO2-coated titanium.

Bioactive, nanoporous TiO2-coating has been shown to enhance cell attachment on titanium implant surface. The aim of this study was to evaluate, whether the saliva proteins affect the epithelial cell adhesion on TiO2-coated and non-coated titanium. Grade V titanium discs were polished. Half of the discs were provided with TiO2-coating produced in sol with polycondensation method. Half of the TiO2-coated and non-coated discs were treated with pasteurized saliva for 30 min. After saliva treatment, the total protein amounts on surfaces were measured. Next, the hydrophilicity of discs were measured with water contact angle measurements. Further, the gingival keratinocyte adhesion strength was measured after 2 and 6 h of cultivation using serial trypsinization. In addition, cell growth and proliferation were measured after 1, 3, and 7 days of cell culture. Finally, cell morphology, spreading and adhesion protein signals were detected with high resolution confocal microscopy. As a result, in sol coated TiO2-surface had significantly higher hydrophilicity when compared to non-coated titanium, meanwhile both non-coated and TiO2-coated surfaces with saliva treatment had a significant increase in hydrophilicity. Importantly, the amounts of adhered saliva proteins were equal between TiO2-coated and non-coated surfaces. Adhesion strength against enzymatic detachment was weakest on non-coated titanium after saliva exposure. Cell proliferation and cell spreading were highest on TiO2-coated titanium, but saliva exposure significantly decreased cell proliferation and spreading on TiO2-coated surface. To conclude, even though saliva exposure makes titanium surfaces more hydrophilic, it seems to neutralize the bioactive TiO2-coating and decrease cell attachment to TiO2-coated surface.

Occlusal veneers and load-bearing capacity of a restored tooth.

PURPOSE: The aim of this study was to evaluate the influence of restoration bonding and type of preparation on load bearing capacity of a tooth restored with indirect glass ceramic or hybrid ceramic occlusal veneer restoration. MATERIALS AND METHODS: Occlusal surfaces of extracted human molar teeth were prepared for indirect occlusal veneers with or without circumferential chamfer. The occlusal veneers were milled either from CAD/CAM hybrid ceramic (HC) Cerasmart (GC), or lithium-disilicate glass ceramic (LDGC) IPS e.max CAD (Ivoclar Vivadent) blocks. Finalized veneers were bonded to teeth following manufacturers' instructions or according to the technique for the intended deteriorated bonding using n-hexane wax solution preconditioning on restorations (n=8/group). The ultimate fracture load was recorded, and fracture types were analyzed and classified visually. Statistical analysis was performed using one-way ANOVA. RESULTS: The highest fracture load was recorded in teeth with bonded LDGC veneer (p≤0.0007). The bonded HC veneers had only marginally higher fracture load compared to non-bonded veneers. In all groups with deteriorated bonding, veneers loosened without tooth fracture whereas in the bonded veneer groups tooth fractures were observed, especially in teeth restored with LDGC material. CONCLUSIONS: Bonded LDGC occlusal veneers have high load bearing capacity which exceeds the fracture resistance of tooth structure. Circumferential chamfer preparation for an occlusal veneer has no influence on fracture load of a restored tooth.

Effect of TiO2 Abutment Coatings on Peri-Implant Soft Tissue Behavior: A Systematic Review of In Vivo Studies.

Establishing a proper soft tissue adhesion around the implant abutment is essential to prevent microbial invasion, inhibit epithelial downgrowth, and obtain an optimal healing process. This systematic review aims to evaluate the real potential of TiO2 coating on the behavior of peri-implant soft tissue health and maintenance. A specific aim was to evaluate clinically and histologically the effect of TiO2 abutment coating on epithelial and connective tissue attachment. Electronic database searches were conducted from 1990 to 2023 in MEDLINE/PubMed and the Web of Science databases. In total, 15 out of 485 publications were included. Eight studies involved humans, and seven were animal studies. Exposure time ranges from 2 days to 5 years. The peri-implant soft tissue evaluations included clinical assessment (plaque index (PI), peri-implant probing pocket depth (PPD), and bleeding on probing (BoP)), histological as well as histomorphometric analysis. The Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies was used to evaluate the overall quality of the studies included in the review. The results showed some variation but remained within acceptable limits. Within the limitations of this systematic review, the present findings suggest that TiO2 coatings seem to influence soft tissue healing. TiO2-coated abutments with a roughness value between 0.2 and 0.5 µm enhance soft tissue health. Sol-gel-derived TiO2 coatings induced better soft tissue attachment than noncoated machined abutment surfaces. The anodized titanium abutments demonstrate comparable clinical and histological outcomes to conventional machined abutments. However, there was variation among the included studies concerning TiO2 coating characteristics and the measured outcomes used to evaluate the soft tissue response, and therefore, quantitative analysis was not feasible. Long-term in vivo studies with standardized soft tissue analysis and coating surface parameters are necessary before a definitive conclusion can be drawn. OSF Registration No.: 10.17605/OSF.IO/E5RQV.

Osteoblast Attachment on Bioactive Glass Air Particle Abrasion-Induced Calcium Phosphate Coating.

Air particle abrasion (APA) using bioactive glass (BG) effectively decontaminates titanium (Ti) surface biofilms and the retained glass particles on the abraded surfaces impart potent antibacterial properties against various clinically significant pathogens. The objective of this study was to investigate the effect of BG APA and simulated body fluid (SBF) immersion of sandblasted and acid-etched (SA) Ti surfaces on osteoblast cell viability. Another goal was to study the antibacterial effect against Streptococcus mutans. Square-shaped 10 mm diameter Ti substrates (n = 136) were SA by grit blasting with aluminum oxide particles, then acid-etching in an HCl-H2SO4 mixture. The SA substrates (n = 68) were used as non-coated controls (NC-SA). The test group (n = 68) was further subjected to APA using experimental zinc-containing BG (Zn4) and then mineralized in SBF for 14 d (Zn4-CaP). Surface roughness, contact angle, and surface free energy (SFE) were calculated on test and control surfaces. In addition, the topography and chemistry of substrate surfaces were also characterized. Osteoblastic cell viability and focal adhesion were also evaluated and compared to glass slides as an additional control. The antibacterial effect of Zn4-CaP was also assessed against S. mutans. After immersion in SBF, a mineralized zinc-containing Ca-P coating was formed on the SA substrates. The Zn4-CaP coating resulted in a significantly lower Ra surface roughness value (2.565 µm; p < 0.001), higher wettability (13.35°; p < 0.001), and higher total SFE (71.13; p < 0.001) compared to 3.695 µm, 77.19° and 40.43 for the NC-SA, respectively. APA using Zn4 can produce a zinc-containing calcium phosphate coating that demonstrates osteoblast cell viability and focal adhesion comparable to that on NC-SA or glass slides. Nevertheless, the coating had no antibacterial effect against S. mutans.

Er:YAG laser debonding of zirconia and lithium disilicate restorations.

STATEMENT OF PROBLEM: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations of different formulations are being used increasingly in monolithic form for a range of clinical applications. Using rotary instruments to remove such restorations for any purpose is challenging, but they can be removed conservatively with erbium lasers. However, studies on how a laser penetrates different zirconias to break the cement bond between the tooth surface and the zirconia are lacking. PURPOSE: The purpose of this in vitro study was to evaluate and compare the time required for an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser to remove different types of zirconia and lithium disilicate crowns. MATERIAL AND METHODS: Forty extracted premolar teeth were prepared, scanned, designed, and milled to fabricate 40 computer-aided design and computer-aided manufacturing (CAD-CAM) crowns, which were assigned to 4 groups (n=10): 3 mol% Y-TZP, 4 mol% Y-TZP, 5 mol% Y-TZP, and lithium disilicate as a control. All crowns were bonded to the teeth with a self-adhesive resin cement (Panavia SA Cement Universal). Each specimen was irradiated with an Er:YAG laser with the following parameters: 300 mJ, 15 Hz, 5.0 W, and a 50-microsecond pulse duration (supershort pulse mode). The irradiation time required for crowns to be retrieved successfully was recorded for each specimen. Data were statistically analyzed using analysis of variance and the Tukey honestly significant difference post hoc test (α=.05). The intaglio surfaces of the restorations were analyzed using scanning electron microscopy (SEM). RESULTS: The mean ±standard deviation times in minutes needed for crown debonding were 12.46 ±4.17 for the 3 mol% Y-TZP group, 10.30 ±3.33 for the 4 mol% Y-TZP group, 4.03 ±1.62 for the 5 mol% Y-TZP group, and 2.08 ±0.92 for the lithium disilicate group. A statistically significant difference (P<.05) in the debonding time was found for all investigated groups, expect between the 3 mol% and 4 mol% Y-TZP groups and between the 5 mol% Y-TZP and lithium disilicate groups. SEM analysis of the ceramic surfaces showed no visual damage associated with Er:YAG laser irradiation. CONCLUSIONS: Zirconia crown retrieval time with the Er:YAG laser was influenced by the yttria content of the zirconia, with decreasing retrieval time with increasing yttria content. Er:YAG laser debonding of zirconia crowns is a noninvasive, efficient, and rapid approach to the removal of crowns and could be applied in clinical practice.

Gastric acid challenge of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after polishing and glazing-impact on surface properties.

OBJECTIVES: To investigate the impact of simulated gastric acid on the surface properties of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after certain polishing and glazing procedures. MATERIALS AND METHODS: Four different types of square-shaped specimens (10 × 10 × 2 mm3, n = 13) were manufactured: lithium disilicate-reinforced glass-ceramic milled and polished (LDS-P); milled, polished, and glazed (LDS-PG); milled, glazed, and no polishing (LDS-G); and milled and polished zirconia-reinforced lithium silicate glass-ceramic (ZR-LS). Specimens were immersed in hydrochloride acid (HCl 0.06 M, pH 1.2) to simulate gastric acid irritation and stored in the acid for 96 h in 37 °C. Specimen weight, surface gloss, Vickers surface microhardness and surface roughness (Ra, Rq, with optical profilometer), and surface roughness on nanometer level (Sq, Sal, Sq/Sal, Sdr, Sds with atomic force microscope) were measured before and after the acid immersion. RESULTS: ZR-LS specimens lost significantly more weight after acid immersion (p = 0.001), also surface microhardness of ZR-LS was significantly reduced (p = 0.001). LDS-G and LDS-PG showed significantly lower surface roughness (Sa, Sq) values compared to LDS-P before (p ≤ 0.99) and after (p ≤ 0.99) acid immersion and ZR-LS after acid immersion (p ≤ 0.99). CONCLUSIONS: Gastric acid challenge affects the surface properties of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic. Glazing layer provides lower surface roughness, and the glazed surface tends to smoothen after the gastric acid challenge. CLINICAL RELEVANCE: Surface finish of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic has a clear impact on material's surface properties. Gastric acidic challenge changes surface properties but glazing seems to function as a protective barrier. Nevertheless, also glazing tends to smoothen after heavy gastric acid challenge. Glazing can be highly recommended to all glass-ceramic restorations but especially in patients with gastroesophageal reflux disease (GERD) and eating disorders like bulimia nervosa.

Zirconia implants interfere with the evaluation of peri-implant bone defects in cone beam computed tomography (CBCT) images even with artifact reduction, a pilot study.

OBJECTIVES: Three-dimensional cone beam computed tomography (CBCT) imaging can be considered, especially in patients with complicated peri-implantitis (PI). Artifacts induced by dense materials are the drawback of CBCT imaging and the peri-implant bone condition may not be assessed reliably because the artifacts are present in the same area. This pilot study investigates the performance of the artifact reduction algorithm (ARA) of the Planmeca Viso G7 CBCT device (Planmeca, Helsinki, Finland) with three different implant materials and imaging parameters. METHODS: Three pairs of dental implants consisting of titanium, zirconia, and fiber reinforced composite (FRC) were set into a pig mandible. A vertical defect simulating peri-implantitis bone loss was made on the buccal side of one of each implant. The defect was identified and measured by two observers and compared to the actual dimensions. In addition, the bone structure and the marginal cortex visibility between the implants were estimated visually. RESULTS: The bone defect and its dimensions with the zirconia implant could not be identified in any image with or without the metal artifact reduction algorithm. The bone defect of titanium and FRC implants were identified with all three imaging parameters or even without ARA. The interobserver agreement between the two observers was almost perfect for all categories analyzed. CONCLUSION: Peri-implantitis defect of the zirconia implant and the peri-implant bone structure of the zirconia implants cannot be recognized reliably with any ARA levels, or any imaging parameters used with the Planmeca Viso G7. The need for ARA when imaging the peri-implant bone condition of the titanium and FRC implants may be unnecessary.

Bioactive Glasses in Periodontal Regeneration: A Systematic Review.

Bioactive glasses (BAGs) are surface-active ceramic materials that can be used in bone regeneration due to their known osteoconductive and osteoinductive properties. This systematic review aimed to study the clinical and radiographic outcomes of using BAGs in periodontal regeneration. The selected studies were collected from PubMed and Web of Science databases, and included clinical studies investigating the use of BAGs on periodontal bone defect augmentation between January 2000 and February 2022. The identified studies were screened using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A total of 115 full-length peer-reviewed articles were identified. After excluding duplicate articles between the databases and applying the inclusion and exclusion criteria, 14 studies were selected. The Cochrane risk of bias tool for randomized trials was used to assess the selected studies. Five studies compared using BAGs with open flap debridement (OFD) without grafting materials. Two of the selected studies were performed to compare the use of BAGs with protein-rich fibrin, one of which also included an additional OFD group. Also, one study evaluated BAG with biphasic calcium phosphate and used a third OFD group. The remaining six studies compared BAG filler with hydroxyapatite, demineralized freeze-dried bone allograft, autogenous cortical bone graft, calcium sulfate ß-hemihydrate, enamel matrix derivatives, and guided tissue regeneration. This systematic review showed that using BAG to treat periodontal bone defects has beneficial effects on periodontal tissue regeneration. OSF Registration No.: 10.17605/OSF.IO/Y8UCR.

Influence of Surface Characteristics of TiO2 Coatings on the Response of Gingival Cells: A Systematic Review of In Vitro Studies.

The soft tissue-implant interface requires the formation of epithelium and connective tissue seal to hinder microbial infiltration and prevent epithelial down growth. Nanoporous titanium dioxide (TiO2) surface coatings have shown good potential for promoting soft tissue attachment to implant surfaces. However, the impact of their surface properties on the biological response of gingival cells needs further investigation. This systematic review aimed to investigate the cellular behavior of gingival cells on TiO2-implant abutment coatings based on in vitro studies. The review was performed to answer the question: "How does the surface characteristic of TiO2 coatings influence the gingival cell response in in vitro studies?". A search in MEDLINE/PubMed and the web of science databases from 1990 to 2022 was performed using keywords. A quality assessment of the studies selected was performed using the SciRAP method. A total of 11 publications were selected from the 289 studies that fulfilled the inclusion criteria. The mean reporting and methodologic quality SciRAP scores were 82.7 ± 6.4/100 and 87 ± 4.2/100, respectively. Within the limitations of this in vitro systematic review, it can be concluded that the TiO2 coatings with smooth nano-structured surface topography and good wettability improve gingival cell response compared to non-coated surfaces.

Focal adhesion formation of primary human gingival fibroblast on hydrothermally and in-sol-made TiO2 -coated titanium.

Optimal cell adhesion of the gingival fibroblasts to dental implants is important for maintaining good implant integration. The aim of this study was to discover, if the nanoporous TiO2 -coating on titanium alloy substrates is able to increase the cell adhesion of the human gingival fibroblasts (HGF). The study consisted of three differently produced titanium groups: hydrothermally produced TiO2 -coating (HT), novel TiO2 -coating made in sol (SOL), and noncoated control group. Primary HGF cells were initiated from gingival biopsies from patients having a third molar extraction. HGF were cultivated on titanium discs for 2 and 24 h to determine the initial attachment with confocal microscope. The cell spreading and adhesion protein signals were measured. In addition, expression of adhesion proteins vinculin, paxillin, and focal adhesion kinase (FAK) were measured after 3 days of cultivation by using Western Blotting. Higher protein levels of paxillin, vinculin, and FAK were induced on both coated discs compared to noncoated discs. The difference was statistically significant (p < 0.05) concerning expression of paxillin. The cell spreading was significantly larger on SOL discs after 2 and 24 h when comparing to noncoated controls. The confocal microscope analyses revealed significantly higher adhesion protein signals on both HT- and SOL-coated titanium compared to control group. This study showed, that both methods to produce TiO2 -coatings are able to increase HGF adhesion protein expression and cell spreading on titanium surface. Accordingly, the coatings can potentially improve the gingival attachment to titanium implant surfaces.

Bioactive glass air-abrasion promotes healing around contaminated implant surfaces surrounded by circumferential bone defects: An experimental study in the rat.

OBJECTIVES: The present study aimed to evaluate the healing of experimentally induced bone defects around contaminated dental implants after air-abrasion using 45S5 or zinc oxide (ZnO)-containing bioactive glasses (BAGs). MATERIALS AND METHODS: One maxillary first molar was extracted from each Sprague-Dawley rat (n = 30). After 4-week healing, a titanium implant was placed in the extraction site with a circumferential bone defect. The rats were randomized into five different groups: (1) implants with Fusobacterium nucleatum and Porphyromonas gingivalis dual-species biofilm (IB); (2) implants with biofilm subjected to inert glass air-abrasion (inert); (3) sterile implants (S); (4) implants with biofilm subjected to 45S5 BAG air-abrasion (45S5); and (5) implants with biofilm subjected to ZnO-containing BAG air-abrasion (Zn4). After 8-week healing, maxillae were dissected, and histomorphometric analyses were performed. RESULTS: The first bone-to-implant contact was significantly shorter for the inert (1.58 ± 1.16 mm; p = 0.016), S (0.28 ± 0.13 mm; p < 0.001), 45S5 (0.41 ± 0.28 mm; p < 0.001), and Zn4 (0.26 ± 0.16 mm; p < 0.001) groups compared to IB group. Also, significantly more bone-to-implant contact was seen for S (72.35% ± 8.32%; p < 0.001), 45S5 (57.91% ± 24.10%; p = 0.002), and Zn4 (70.49% ± 12.74%; p < 0.001) groups than the IB group. The bone volume with the threads demonstrated significantly higher value for S (69.32% ± 9.15%; p < 0.001), 45S5 (58.93% ± 23.53%; p = 0.001), and Zn4 (68.65% ± 12.41%; p < 0.001) groups compared to the IB group. The bone volume within the defects was significantly higher for S (68.79% ± 11.77%; p < 0.001), 45S5 (62.51% ± 20.51%; p = 0.002), and Zn4 (73.81% ± 15.07%; p < 0.001) groups compared to the IB group. CONCLUSIONS: This study suggests that air-abrasion of contaminated moderately rough implant surfaces with either 45S5 or ZnO-containing BAGs enhances osseointegration and bone defect regeneration.

Oral health-related quality of life among home-dwelling older people with and without domiciliary care.

OBJECTIVES: The aim was to compare oral health-related quality of life (OHRQoL) between home-dwelling older people with and without domiciliary care when adjusted for gender, education, use of dental services and removable dental prostheses. BACKGROUND: OHRQoL of home-dwelling older people with and without domiciliary care is a neglected area of research, with few studies having been conducted. MATERIALS AND METHODS: A secondary analysis was conducted on the Finnish Health 2011 interview data. Home-dwelling participants (age ≥ 70) with or without domiciliary care were included (n = 758). OHRQoL was measured with the Oral Health Impact Profile questionnaire (OHIP-14) calculating three outcomes: prevalence of at least one impact reported: "occasionally," "fairly often" or "very often" (OFoVo), severity as mean sum score and mean of the seven OHIP-14 dimensions. These were evaluated by use of domiciliary care using logistic and negative binomial regression analyses. RESULTS: Domiciliary care clients tended to have poorer OHRQoL than non-clients (severity mean 4.33 vs 4.11, P = .057), especially men (6.71 vs 4.15, P = .027), and reported more psychological discomfort than non-clients (mean 1.10 vs 0.82, P = .039). The use of removable dental prostheses was the strongest predictor (OR 2.84, P < .001) of poor OHRQoL. CONCLUSION: Domiciliary care clients tended to report poorer OHRQoL, especially with regard to psychological discomfort dimension than non-clients. Thus, support of oral hygiene and regular utilisation of oral health services should be part of domiciliary care among older people to enhance OHRQoL.

Strength and phase transformation of different zirconia types after chairside adjustment.

STATEMENT OF PROBLEM: Limited evidence is available for the effect of chairside adjustment using diamond instruments on different types of zirconia. PURPOSE: The purpose of this in vitro study was to evaluate the effect of simulated adjustments on the biaxial flexural strength and phase transformation of 3 different zirconia types. MATERIAL AND METHODS: Three zirconia types from the same manufacturer (Katana; Kuraray) were used: High Translucency (3Y-PSZ), Super Translucent Multi Layered (4Y-PSZ), and Ultra Translucent Multi Layered (5Y-PSZ). Thirty disk-shaped specimens (Ø14×1.2 mm) were fabricated according to the International Organization for Standardization (ISO) Standard 6872 from different zirconia types (N=90). Specimens were either left without adjustment (NA), adjusted with Dialite ZR finishing and polishing system (Brasseler) (APol), or adjusted with course diamond instruments only (ADia). The specimens were distributed into 9 groups (n=10): group 3Y-PSZ/NA, group 3Y-PSZ/APol, group 3Y-PSZ/ADia, group 4Y-PSZ/NA, group 4Y-PSZ/APol, group 4Y-PSZ/ADia, group 5Y-PSZ/NA, group 5Y-PSZ/APol, and group 5Y-PSZ/ADia. The biaxial flexural strength of each specimen was measured by using a universal testing machine (Model 4411; Instron) and according to ISO 6872. X-ray diffraction analysis was conducted to quantify the monoclinic phase transformation. Scanning electron microscopy images were obtained to evaluate the fracture pattern. Statistical analysis was performed by using analysis of variance (ANOVA) and Tukey multiple comparison tests for pairwise comparisons (α=.05). RESULTS: The mean biaxial flexural strengths ranked from the highest to the lowest were for 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ under any test condition (P=.007). Chairside adjustment with a diamond instrument significantly decreased the flexural strength of all zirconia types (P<.05). No statistically significant difference was found between the effect of APol and ADia on the strength of zirconia 3Y-PSZ (P=.603), 4Y-PSZ (P=.993), and 5Y-PSZ (P=.660). Phase transformation did not occur in the 5Y-PSZ groups. ADia groups had significantly higher phase transformation values regardless of zirconia type (P<.05). CONCLUSIONS: The biaxial flexural strength of zirconia decreased significantly after chairside adjustment with diamond instruments regardless of the yttria percentage. Adjustment with the Dialite ZR finishing and polishing system caused less tetragonal to monoclinic phase transformation than adjustment with a course-grit diamond instrument.

Epithelial cell attachment and adhesion protein expression on novel in sol TiO2 coated zirconia and titanium alloy surfaces.

An adequate mucosal attachment is important when it comes to preventing peri-implant inflammation. The aim of this study was to compare epithelial cell adhesion and adhesion protein expression on in sol TiO2 -coated and non-coated zirconia and titanium alloy surfaces. Fifty-six zirconia and titanium discs were cut, and half of them were coated with bioactive TiO2 -coating. To study the epithelial cell attachment, human gingival keratinocytes were cultivated on discs for 1, 3, 6, and 24 h. The cell proliferation was detected by cultivating cells for 1, 3, and 7 days. In addition, the levels of adhesion proteins laminin y2, integrin α6, ß4, vinculin, and paxillin were detected with Western Blot method. Furthermore, high-resolution imaging of the actin cytoskeleton and focal adhesion proteins was established. Longer-term cell culture (1-7 days) revealed higher cell numbers on the coated zirconia and titanium discs compared to non-coated discs. The difference was statistically significant (p < .05) after 24 h on coated zirconia and after 3 and 7 days on coated titanium discs compared to non-coated discs. Clear induction in the protein levels of laminin y2 and integrin α6 were detected on both coated samples, meanwhile integrin ß4 were clearly induced on coated titanium alloy. The microscope evaluation showed significantly increased cell spreading on the coated discs. According to this study, the in sol induced TiO2 -coating increases keratinocyte attachment and the expression of adhesion proteins on coated zirconia and titanium in vitro. Consequently, the coating has potential to enhance the mucosal attachment on implant surfaces.

Push-Out Force and Microleakage of Screw Access Hole Filling Materials in Monolithic Zirconia Implant Crowns.

PURPOSE: To test the push-out force and marginal leakage of different screw hole-sealing methods in monolithic zirconia implant crowns. MATERIALS AND METHODS: Ninety monolithic zirconia (Prettau, Zirkonzahn) specimens were milled with two different screw access hole designs: conventional smooth hole or threaded screw hole (for group PMMA-SC), and divided into five groups (n = 18) according to filling method: unbonded composite (UBC); bonded composite (BC); airborne-particle abrasion of screw hole and unbonded composite (ABR-UBC); airborne-particle abrasion of screw hole and bonded composite (ABR-BC); and PMMA screw plugs (PMMA-SC). Twelve specimens per group were subjected to static push-out force with a universal testing machine. Before testing, 6 specimens per group were stored in dry conditions, and 6 were kept in water storage (+37°C) for 7 days. For the remaining specimens (n = 6), cotton pellets were placed under the screw access hole fillings, and the specimens were immersed in 0.5% basic fuchsin solution for 2 weeks. Dye in cotton pellets was dissolved in 2 mL of water, and absorbances of the solutions were measured with a spectrophotometer at 465 nm. Data are reported as mean and SD. Statistical analysis was made using a generalized linear model with logarithmic transformation. RESULTS: PMMA-SC specimens showed the highest push-out forces (P < .0001) and lowest fuchsin penetration (P = .009). Airborne-particle abrasion increased the push-out force and decreased the microleakage in composite groups. The storage conditions affected the results of both unbonded groups. CONCLUSION: The design and sealing method of the screw access hole affect push-out force and microleakage.

Perceived oral health and oral health behaviours among home-dwelling older people with and without domiciliary care.

OBJECTIVES: The aim was to compare the perceived oral health and oral health behaviours of home-dwelling older people with and without domiciliary care. BACKGROUND: Oral health is poor in long-term care, but less is known about perceived oral health of home-dwelling older people receiving domiciliary care. MATERIALS AND METHODS: Data from the Health 2000 and Health 2011 surveys (BRIF8901) were used. Interview participants were at least 70 years old and living at home with or without domiciliary care (n = 1298 in 2000 and n = 1027 in 2011). Differences in perceived oral health (subjective oral health, pain, eating difficulties) and oral health behaviours (hygiene, use of services) were compared based on the use of domiciliary care and stratified by gender. Differences between groups were compared with the chi-square test. RESULTS: In 2011, compared to non-clients, domiciliary care clients more often had poor subjective oral health (40.3% vs. 28.9%, P = .045). In both surveys, they also used oral health services less recently (2000, 76.4% vs. 60.9%; and 2011, 61.1% vs. 46.6%) and more often had difficulties chewing hard food (2000, 50.6% vs. 34%, P < .001; and 2011, 38.4% vs. 20.7%, P < .001) than non-clients. In 2000, clients had more difficulty eating dry food without drinking (39.5% vs. 21.6%, P < .001) and cleaning their teeth and mouth (14.3% vs. 1.1%, P < .001) than non-clients. Women clients in 2011 brushed their teeth less often than non-clients (43.5% vs. 23.7%, respectively, P = .001). CONCLUSION: Domiciliary care clients have poorer perceived oral health, and greater difficulties with eating and oral hygiene maintenance than non-clients.

Organotypic in vitro block culture model to investigate tissue-implant interface. An experimental study on pig mandible.

In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture models, which fail to replicate the three-dimensional native human oral mucosal tissue completely. Thus, the present study aimed to describe a novel tissue culture model using pig mandibular block including alveolar bone and gingival soft tissues to evaluate the tissue attachment to titanium implant provided with hydrothermally induced TiO2 coating. Tissue attachment on TiO2 coated and non-coated implants were compared. Ti-6Al-4V alloy posts were used to function as implants that were inserted in five pig mandibles. Implants were delivered with two different surface treatments, non-coated (NC) titanium and hydrothermal induced TiO2 coated surfaces (HT). The tissue-implant specimens were cultured at an air/liquid interface for 7 and 14 days. The tissue-implant interface was analyzed by histological and immunohistochemical stainings. The microscopic evaluation suggests that pig tissue explants established soft and hard tissue attachment to both implant surfaces. The epithelial cells appeared to attach to the coated implant. The epithelium adjacent to the implant abutment starts to change its phenotype during the early days of the healing process. New bone formation was seen within small pieces of bone in close contact with the coated implant. In conclusion, this in vitro model maintains the viability of pig tissue and allows histologically and immunohistochemically evaluate the tissue-implant interface. HT-induced TiO2 coating seems to have a favorable tissue response. Moreover, this organotypic tissue culture model is applicable for further studies with quantitative parameters to evaluate adhesion molecules present at the implant-tissue interface.

Effect of specific retention biomaterials for ball attachment on the biomechanical response of single implant-supported overdenture: A finite element analysis.

PURPOSE: The purpose of this finite element analysis (FEA) was to evaluate the effect of specific retention biomaterials with different elastic modulus on the biomechanical response to the axial and off-axial biting loads of a mandibular midline single implant-supported overdenture (SIO) model. METHODS: Five 3-dimensional (3D) finite element models of an edentulous mandible with SIO were designed as follows: model M with a titanium retentive element for ball attachment, model P with a PEEK retentive element, model S with a silicone resilient liner retentive element, model T with a thermoplastic acrylic resin retentive element made from a CAD-CAM material, and model A with a polyacetal resin retentive element. Posterior bilateral vertical load (PV) at the 1st molar areas and anterior oblique load (AO) at the incisal edge of the mandibular central incisors at a 30-degree angle of 100 N were applied. Stress values were recorded. RESULTS: Stress values were higher for all models under (AO) loading than under (PV) loading. Model M recorded the highest stress values on the implant, its components, cortical, and cancellous bone under both loading conditions. Under (AO) loading condition, the ball abutment von Mises stress value in model S was almost 7 times lower than that of model M (19 and 130 MPa respectively) and the other 3 models (P, T, and A) (119, 121, and 120 MPa respectively). However, model S recorded the highest value of denture base stress at the attachment area. CONCLUSIONS: The elastic modulus of retention materials can affect stresses generated on the implant overdenture components and supporting structures.

Effect of bioactive glass air-abrasion on Fusobacterium nucleatum and Porphyromonas gingivalis biofilm formed on moderately rough titanium surface.

This aim of this study was to investigate the effects of three types of air-abrasion particles on dual-species biofilms of Fusobacterium nucleatum and Porphyromonas gingivalis, both of which were cultured on sandblasted and acid-etched (SA) titanium discs. Out of 24 SA discs with biofilm, 18 were exposed to either air-abrasion using Bioglass 45S5 (45S5 BG; n = 6), novel zinc (Zn)-containing bioactive glass (Zn4 BG; n = 6), or inert glass (n = 6). The efficiency of biofilm removal was evaluated using scanning electron microscopy (SEM) imaging and culturing techniques. Air-abrasion using 45S5 BG or Zn4 BG demonstrated a significant decrease in the total number of viable bacteria compared to discs air-abraded with inert glass or intact biofilm without abrasion. Moreover, P. gingivalis could not be detected from SEM images nor culture plates after air-abrasion with 45S5 BG or Zn4 BG. The present study showed that air-abrasion with 45S5 or Zn4 bioactive glasses can successfully eradicate dual-biofilm of F. nucleatum and P. gingivalis from sandblasted and acid-etched titanium discs.