Influence of denture-bearing conditions on masticatory function and patient-reported outcomes measures.

PURPOSE: To investigate the influence of different denture-bearing conditions on the masticatory function and patient-reported outcome measures (PROMs) of complete denture wearers. METHODS: Sixty edentulous patients were selected and allocated into two groups according to the American College of Prosthodontics' (ACP) classification: non-atrophic (NAT) (Classes I and II) (n = 24) and atrophic (AT) (Classes III and IV) (n = 36). All patients received new complete dentures (CDs). The objective variables (masticatory performance and swallowing threshold) were assessed as well as the PROMs (oral health-related quality of life (OHIP-EDENT), patient satisfaction) and quality of the prosthesis, at baseline (using the old CD) and after 4 months new prostheses use. Data were analyzed by Mann-Whitney test followed by the Generalized Equations Estimation (GEE), linear regression and Chi-square test. RESULTS: Higher masticatory performance was observed in the NAT group (p < .05) for both time points, baseline and after 4 months. However, compared to baseline, both groups showed significant masticatory improvement after 4 months (p < .05). Satisfaction and overall quality of life improved after 4 months with no difference between groups (p > .05). Regarding the quality of the CD, baseline results were significantly (p < .05) lower in the AT group, but after 4 months, no significant differences were found between groups and in intragroup analysis (p > .05). CONCLUSIONS: The denture-bearing conditions seems to impact masticatory function, but the PROMs are barely affected.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

OBJECTIVE: Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. MATERIALS AND METHODS: Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50 N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. RESULTS: The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. CONCLUSION: Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. CLINICAL RELEVANCE: The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

Does Streptococcus oralis supernatant influence on the proliferation and virulence of Candida albicans?

OBJECTIVE: To evaluate the influence of Streptococcus oralis supernatant on the proliferation and virulence of Candida albicans. DESIGN: S. oralis supernatant was obtained by filtration of overnight cultures. Single or dual-species cultures of C. albicans and S. oralis were cultivated in both planktonic and biofilm-based models. Planktonic culture growth was measured, and mature biofilms formed on resin disks were collected to measure biofilm metabolic activity, total biomass, and cell counts. Hyphae formation (virulence factor) and biofilm thickness were analyzed by confocal laser scanning microscopy. Data were analyzed by a one-way ANOVA test followed by the Tukey posthoc test (α = 0.05). RESULTS: We found that S. oralis supernatant did not influence C. albicans proliferation in planktonic cultures. However, biofilms containing S. oralis supernatant showed higher cell metabolism than C. albicans monoculture biofilms and C. albicans-S. oralis dual-culture biofilms (p < 0.05). Though S. oralis supernatants did increase biofilm metabolic activity, they did not affect the total biomass and cell counts of C. albicans (p > 0.05). However, biofilm imaging revealed enhanced C. albicans hyphae formation in biofilms containing S. oralis supernatant compared to C. albicans monoculture biofilms. CONCLUSIONS: Secreted metabolites in S. oralis supernatant may contribute to C. albicans metabolism and virulence.

Candida albicans Adhesins Als1 and Hwp1 Modulate Interactions with Streptococcus mutans.

Candida albicans and Streptococcus mutans are known to synergistically interact with each other in the oral cavity. For example, glucosyltransferase B (GtfB), secreted by S. mutans, can bind to the C. albicans cell surface, promoting dual-species biofilm formation. However, the fungal factors mediating interactions with S. mutans are unknown. The C. albicans adhesins Als1, Als3, and Hwp1 are key players in C. albicans single-species biofilm formation, but their roles, if any, in interacting with S. mutans have not been assessed. Here, we investigated the roles of the C. albicans cell wall adhesins Als1, Als3, and Hwp1 on forming dual-species biofilms with S. mutans. We assessed the abilities of the C. albicans wild-type als1Δ/Δ, als3Δ/Δ, als1Δ/Δ/als3Δ/Δ, and hwp1Δ/Δ strains to form dual-species biofilms with S. mutans by measuring optical density, metabolic activity, cell enumeration, biomass, thickness, and architecture of the biofilms. We observed that the C. albicans wild-type strain formed enhanced dual-species biofilms in the presence of S. mutans in these different biofilm assays, confirming that C. albicans and S. mutans synergistically interact in the context of biofilms. Our results reveal that C. albicans Als1 and Hwp1 are major players in interacting with S. mutans, since dual-species biofilm formation was not enhanced when the als1Δ/Δ or hwp1Δ/Δ strains were cultured with S. mutans in dual-species biofilms. Als3, however, does not seem to play a clear role in interacting with S. mutans in dual-species biofilm formation. Overall, our data suggest that the C. albicans adhesins Als1 and Hwp1 function to modulate interactions with S. mutans and could be potential targets for future therapeutics.

Clinical performance of short and extrashort dental implants with wide diameter: A systematic review with meta-analysis.

STATEMENT OF PROBLEM: Rehabilitation with wide-diameter reduced-length implants has become popular for patients with minimal vertical bone. However, a consensus on the benefits of this approach is lacking. PURPOSE: The purpose of this systematic review with meta-analysis was to evaluate the influence of wide compared with regular diameter on the clinical performance of short (<10 mm) and extrashort (≤6 mm) dental implants used for rehabilitations with single crowns, fixed partial dentures, or both, in the posterior region. MATERIAL AND METHODS: A search in 6 databases was conducted to select randomized controlled trials (RCTs) and nonrandomized controlled trials (N-RCTs). Five meta-analyses were performed, where the risk ratio (RR) was evaluated. The certainty of evidence was evaluated, and the risk of bias was determined from the Joanna Briggs Institute checklist. RESULTS: Fourteen articles were included, 272 wide- and 478 regular-diameter implants. One study presented a low, 3 an unclear, and 11 a high risk of bias. Meta-analyses showed no statistical difference: implant survival, short dental implants in N-RCTs (up to 1 year - RR 1.01 [0.98; 1.03], 1 to 5 years - RR 1.01 [0.94; 1.08], more than 5 years - RR 1.01 [0.97; 1.06]), extrashort dental implants in N-RCTs (RR 1.04 [0.90; 1.20]), RCTs (RR 1.05 [0.88; 1.25]); implant success in N-RCTs (RR 1.01 [0.97; 1.05]); prosthesis success in N-RCTs (RR 1.01 [0.97; 1.05]). CONCLUSIONS: Short and extrashort dental implants with a wide and regular diameter appear to be clinically appropriate options for implant-supported posterior restorations, with high survival, success, and prosthesis success rates.

Performance of complete dentures fabricated with the simplified and the traditional technique: A randomized clinical trial.

STATEMENT OF PROBLEM: The simplified technique has been recommended for the fabrication of removable complete dentures. However, a consensus regarding the performance of the simplified and the traditional techniques is lacking. PURPOSE: The purpose of this randomized clinical trial was to compare the performance of prostheses fabricated with the simplified and the traditional techniques. MATERIAL AND METHODS: Sixty participants were recruited and randomized into 2 groups: traditional technique (control group) and simplified technique (experimental group). The assessments were performed before treatment (baseline) and 2 and 4 months after adaptation to the new complete dentures. The variables evaluated were satisfaction, oral health-related quality of life (OHRQoL) by using the Brazilian version of the OHIP-EDENT, the quality of the prostheses, and, for the functional assessment, the masticatory performance and swallowing threshold. The data were analyzed by the Fisher exact test, the Mann-Whitney test, and the generalized equations estimating (GEE) method. RESULTS: At baseline, the mean ±standard deviation quality of the prostheses was 5.3 ±2.3 for the traditional technique and 4.9 ±2.3 for the simplified technique, and at 4 months, it was 9.3 ±0.9 and 9.1 ±0.9, respectively. For masticatory performance, the mean ±standard deviation X50 at baseline was 5.7 ±1.4 for the traditional technique and 5.7 ±0.9 for the simplified technique, and at 4 months, it was 3.8 ±1.2 and 3.7 ±0.9, respectively. The mean ±standard deviation OHRQoL at baseline was 14.1 ±8.6 for the traditional technique and 12.5 ±9.4 for the simplified technique, and at 4 months, it was 3.2 ±4.3 and 2.6 ±5.1, respectively. The mean ±standard deviation satisfaction at baseline was 9.5 ±3.9 for the traditional technique and 9.3 ±4.2 for the simplified technique; after 4 months, it was 14.8 ±2.0 for both techniques. There was a significant improvement (P<.05) for all variables in the study when comparing them at the baseline to those at the evaluation after provision of new complete dentures. There was no significant difference in all analyzed variables (P>.05) between the 2 techniques for prosthesis fabrication. CONCLUSIONS: The simplified technique appears to be a suitable alternative to the traditional technique for the fabrication of complete dentures, with similar performance.

Influence of diameter in the stress distribution of extra-short dental implants under axial and oblique load: a finite element analysis

Aim: This study evaluated the influence of a wide diameter on extra-short dental implant stress distribution as a retainer for single implant-supported crowns in the atrophic mandible posterior region under axial and oblique load. Methods: Four 3D digital casts of an atrophic mandible, with a single implant-retained crown with a 3:1 crown-to-implant ratio, were created for finite element analysis. The implant diameter used was either 4 mm (regular) or 6 mm (wide), both with 5 mm length. A 200 N axial or 30º oblique load was applied to the mandibular right first molar occlusal surface. The equivalent von Mises stress was recorded for the abutment and implant, minimum principal stress, and maximum shear stress for cortical and cancellous bone. Results: Oblique load increased the stress in all components when compared to axial load. Wide diameter implants showed a decrease of von Mises stress around 40% in both load directions at the implant, and an increase of at least 3.6% at the abutment. Wide diameter implants exhibited better results for cancellous bone in both angulations. However, in the cortical bone, the minimum principal stress was at least 66% greater for wide than regular diameter implants, and the maximum shear stress was more than 100% greater. Conclusion: Extra-short dental implants with wide diameter result in better biomechanical behavior for the implant, but the implications of a potential risk of overloading the cortical bone and bone loss over time, mainly under oblique load, should be investigated

Prosthetic complications and quality of life among wearers of mandibular overdenture with the Facility-Equator system.

This longitudinal study aimed to assess the performance of the Facility-Equator system as mandibular overdenture (MO) retainers from a prosthetic perspective during 2 years of loading and to investigate the oral health-related quality of life (OHRQoL) and whether prosthetic events can affect the OHRQoL. Twenty-four patients (68.1 ± 7.51 years) reported their OHRQoL through the Geriatric Oral Health Assessment Index (GOHAI) and Oral Health Impact Profile (OHIP-EDENT) questionnaires before MO loading and after 1 and 2 years of usage. Prosthetic occurrences were recorded during this period. Data were analyzed using the Wilcoxon test, Mann-Whitney test, and Spearman correlation coefficients. Of the 127 prosthetic events that occurred in the first year, the most frequent events were prosthesis adjustments (16.5%), dislodgement of the Equator attachment (14.17%), and O-ring replacement (11.8%). Eighty-seven prosthetic events were recorded in the second year, the most frequent events being prosthesis adjustments (27.6%), O-ring replacement (20.7%), and recapturing the female matrix (11.5%). All domains of the GOHAI and OHIP-EDENT questionnaires exhibited a significant difference (p < 0.05) between the baseline and 1- and 2-year evaluations, except in the Social Disability and Psychological Discomfort domains (p > 0.05) of OHIP-EDENT after 1 year. Complications related to prosthetic maintenance, such as fracturing of the prosthesis, Equator dislodgement, prosthesis rebasing, and new overdenture confection, affect the OHRQoL (p < 0.05), primarily the Physical Pain and Discomfort domains, especially in the first year of MO loading.

Patient-reported outcome measures and clinical performance of implant-retained mandibular overdentures with stud and ball attachments: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Evidence regarding the retention system for a mandibular overdenture is important for treatment planning. However, the clinical performance of stud and ball attachments for mandibular overdenture retainers is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to compare the clinical performance and self-reported patient outcomes of ball and stud attachments as mandibular overdenture retainers. MATERIAL AND METHODS: Randomized (RCTs) and nonrandomized (N-RCTs) controlled clinical trials were selected based on the eligibility criteria. The risk of bias was assessed by using the Cochrane Collaboration Tools, and the certainty of the evidence (COE) by using the grades of recommendation, assessment, development, and evaluation (GRADE) workshop approach. Meta-analyses according to the follow-up period were performed for implant survival, prosthetic maintenance and complications, bleeding on probing (BoP), marginal bone loss (MBL), satisfaction, and oral health-related quality of life (OHRQoL). RESULTS: Thirteen RCTs and 4 N-RCTs were included. Twelve studies presented a high risk of bias. The stud demonstrated a lower risk ratio (RR) (P<.001) for maintenance and complications concerning the need for matrix activation (RR 7.12 [2.65, 19.15]) (very low COE) and new overdentures (RR 2.47 [1.02, 5.96]) (moderate COE), ranging from 1 to 5 years of follow-up. Mean difference (MD) for MBL after 1 (MD 0.40 [0.28, 0.52]; P<.001) and 5 years (MD 0.18 [0.16, 0.20]; P<.001) was higher for ball attachments than that for stud (very low COE) attachments. Stud attachments also improved satisfaction (P<.001) when compared with ball attachments (very low COE). Implant survival rate (high COE), BoP (very low COE), and OHRQoL (low COE) were similar for the attachments. CONCLUSIONS: Stud and ball attachments are clinically appropriate options as mandibular overdenture retainers and are capable of restoring OHRQoL. Nevertheless, the stud showed greater improvement in satisfaction and less prosthetic aftercare and MBL.

Implant-supported crowns with locking taper implant-abutment connection: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Implant-supported single crowns are more prone to screw loosening than splinted prostheses. Therefore, the locking taper system, which has a screwless abutment, may perform better when associated with this type of rehabilitation. However, systematic reviews on this system are lacking. PURPOSE: The purpose of this systematic review was to evaluate the clinical performance and complications of single crowns retained by the locking taper system. MATERIAL AND METHODS: This systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) under CRD42020189921. An electronic search was made in 5 databases and 3 other sources up to February 2021 to select prospective clinical studies evaluating the performance of single crowns retained by the locking taper system by using the outcomes implant survival, success rate, complications, marginal bone loss (MBL), and prosthesis success rate. Four meta-analyses grouped according to the follow-up intervals were performed. The risk of bias of the selected studies was evaluated by using the RoB 2 checklist for randomized controlled trials (RCTs) and Downs and Black for uncontrolled studies. RESULTS: Twelve studies were included: 9 prospective cohort studies and 3 RCTs. A survival rate of 99% (98% to 99%) and a success rate of 97% (92% to 99%) after 5 years were found. Of the total, 2.6% biological and 2.9% prosthetic complications were described. The prosthesis success rate was 97% (96% to 98%) after 5 years. An average of -0.73 mm (-0.93 to -0.52) was found for the MBL after 5 years. The risk-of-bias assessment showed 2 RCTs with high risk and 1 RCT with low risk of bias. Among uncontrolled studies, 2 were classified as poor and 7 as fair. CONCLUSIONS: Single crowns retained by locking taper implants can be safely indicated based on the high survival and success rates achieved in the long term, the maintenance of bone level stability over time, and the low incidence of complications.

Fatigue and failure analysis of restored endodontically treated maxillary incisors without a dowel or ferrule.

STATEMENT OF PROBLEM: Information on the survival and mode of failure of endodontically treated incisors without a ferrule and restored without dowels is lacking. PURPOSE: The purpose of this in vitro study was to compare the survival and failure mode of endodontically treated incisors without a ferrule and restored with bonded ceramic crowns and various composite resin foundation restorations without dowels with a control group with fiber dowels. MATERIAL AND METHODS: Forty-five decoronated endodontically treated bovine incisors without ferrule were divided into 3 experimental groups and restored with different adhesive foundation restorations without dowel: nanohybrid composite resin (Nd), bulk-fill composite resin foundation restoration (NdB), and fiber-reinforced bulk-fill composite resin (NdFR). A control group with conventional foundation restorations (glass-fiber dowel with nanohybrid composite resin foundation restoration without ferrule) (D) was included for comparison. All teeth were prepared to receive bonded lithium disilicate ceramic crowns luted with dual-polymerizing composite resin cement and were subjected to accelerated fatigue testing. Cyclic isometric loading was applied to the incisal edge at an angle of 30 degrees and a frequency of 5 Hz, beginning with a load of 100 N (5000 cycles). A 100-N load increase was applied each 15 000 cycles. Specimens were loaded until failure or to a maximum for cycles endured of 1000 N (140 000 cycles). Groups were compared by using the Kaplan-Meier survival analysis (log rank test at α=.05 and pairwise post hoc comparisons) and life table analysis for load-at-failure (followed by Wilcoxon pairwise comparison α=.05). RESULTS: All the specimens failed before 140 000 load cycles. Even though no statistically significant differences were found between the experimental groups without dowel (P>.127), the fiber-reinforced foundation restoration yielded the highest mean ±standard deviation cycles to failure (46 023 ±4326) compared with Nd (38 899 ±2975) and NdB (39 751 ±2998). NdFR, however, outperformed the foundation restoration with glass-fiber dowel (35 026 ±2687) (P<.05). Most failure in groups without dowel were restorable, while 100% of catastrophic failure (unrestorable) were found in the group with dowels. CONCLUSIONS: Based on the present in vitro study, dowels did not improve the performance of the adhesive restoration of endodontically treated incisors without a ferrule. The use of a short fiber-reinforced composite resin foundation restoration without a dowel was able to not only improve the resistance of the restorations compared with adhesive foundation restorations with dowels but also minimize catastrophic failures.

Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study.

Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study

Abstract Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

Prosthetic complications and quality of life among wearers of mandibular overdenture with the Facility-Equator system

Abstract This longitudinal study aimed to assess the performance of the Facility-Equator system as mandibular overdenture (MO) retainers from a prosthetic perspective during 2 years of loading and to investigate the oral health-related quality of life (OHRQoL) and whether prosthetic events can affect the OHRQoL. Twenty-four patients (68.1 ± 7.51 years) reported their OHRQoL through the Geriatric Oral Health Assessment Index (GOHAI) and Oral Health Impact Profile (OHIP-EDENT) questionnaires before MO loading and after 1 and 2 years of usage. Prosthetic occurrences were recorded during this period. Data were analyzed using the Wilcoxon test, Mann-Whitney test, and Spearman correlation coefficients. Of the 127 prosthetic events that occurred in the first year, the most frequent events were prosthesis adjustments (16.5%), dislodgement of the Equator attachment (14.17%), and O-ring replacement (11.8%). Eighty-seven prosthetic events were recorded in the second year, the most frequent events being prosthesis adjustments (27.6%), O-ring replacement (20.7%), and recapturing the female matrix (11.5%). All domains of the GOHAI and OHIP-EDENT questionnaires exhibited a significant difference (p < 0.05) between the baseline and 1- and 2-year evaluations, except in the Social Disability and Psychological Discomfort domains (p > 0.05) of OHIP-EDENT after 1 year. Complications related to prosthetic maintenance, such as fracturing of the prosthesis, Equator dislodgement, prosthesis rebasing, and new overdenture confection, affect the OHRQoL (p < 0.05), primarily the Physical Pain and Discomfort domains, especially in the first year of MO loading.

Silane-Coating Strategy for Titanium Functionalization Does Not Impair Osteogenesis In Vivo.

Silane-coating strategy has been used to bind biological compounds to the titanium surface, thereby making implant devices biologically active. However, it has not been determined if the presence of the silane coating itself is biocompatible to osseointegration. The aim of the present study was to evaluate if silane-coating affects bone formation on titanium using a rabbit model. For this, titanium screw implants (3.75 by 6 mm) were hydroxylated in a solution of H2SO4/30% H2O2 for 4 h before silane-coating with 3-aminopropyltriethoxysilane (APTES). A parallel set of titanium screws underwent only the hydroxylation process to present similar acid-etched topography as a control. The presence of the silane on the surface was checked by x-ray photoelectron spectroscopy (XPS), with scanning electron microscopy (SEM) and atomic force microscopy (AFM). A total of 40 titanium screws were implanted in the tibia of ten New Zealand rabbits in order to evaluate bone-to-implant contact (BIC) after 3 weeks and 6 weeks of healing. Silane-coated surface presented higher nitrogen content in the XPS analysis, while micro- and nano-topography of the surface remained unaffected. No difference between the groups was observed after 3 and 6 weeks of healing (p > 0.05, independent t-test), although an increase in BIC occurred over time. These results indicate that silanization of a titanium surface with APTES did not impair the bone formation, indicating that this can be a reliable tool to anchor osteogenic molecules on the surface of implant devices.

Influence of Facial Morphology on Masticatory Function and Quality of Life in Elders Using Mandibular Overdentures: 3-Year Results.

Background: Facial types may interfere in the oral health-related quality of life (OHRQoL) and masticatory performance of implant-retained mandibular overdenture (IMO) wearers. Purpose: Investigate the medium-term changes in the masticatory function (MF) and OHRQoL parameters of IMO users, as a function of facial pattern, anteroposterior skeletal discrepancy, and sex. Methods: Forty IMO users, most of them Caucasian (90%) with average age of 69.17 years were classified according to their facial pattern and antero-posterior discrepancy prior to rehabilitation. MF was evaluated by the multiple sieves method to determine the average particle size (X50), heterogeneity (B) and masticatory efficiency (ME, calculated as the percentage of material retained in the 5.6 and 2.8 mm sieves), using Masticatory performance (MP) and swallowing threshold (ST) tests. OHRQoL was measured by applying the dental impact on daily life (DIDL) questionnaire. The data were analyzed by Wilcoxon-paired tests to analyze changes in MF parameters over time, and mixed-effect multilevel regression models were employed to verify differences between groups. Results: Significant changes were still observed in the 3rd year for the ST test with improvements in B for Mesofacial and in time for Dolichofacial individuals, while ME_2.8 deteriorated for Brachyfacial participants. B values of Class I and male individuals improved and brachyfacial individuals still presented worse homogenization (B) than Mesofacial participants in both masticatory tests. Class II and III participants still showed improvements in ME_5.6 and time compared to Class I despite increases in X50. Class II individuals needed less cycles than Class I in the 3rd year. Brachyfacial participants scored lower in the Appearance domain than Mesofacial ones in the 3rd year. Dolichofacial participants and Class III patients scored lower in the Oral Comfort domain than Mesofacial and Class I, respectively. In addition, age influenced the Pain, Oral Comfort and General Performance domains in the 3rd year. Conclusions: Differences in facial morphology continue to influence the MF and OHRQoL outcomes in the 3rd year, and age influenced some OHRQoL domains. Brachyfacial individuals continue to benefit least from rehabilitation with IMO according to masticatory parameters.

Influence of luting space of zirconia abutment on marginal discrepancy and tensile strength after dynamic loading.

STATEMENT OF PROBLEM: Although luting space is related to the marginal fit of indirect restorations, information on its influence on the marginal fit and tensile strength of zirconia abutments bonded to titanium bases is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the influence of luting space on the marginal discrepancy and tensile strength of zirconia abutments bonded to a titanium base after dynamic loading. MATERIAL AND METHODS: Ninety implant replicas were embedded in resin blocks to attach 4-mm-high titanium luting bases. Zirconia abutments (Ceramill Zolid FX) were fabricated with different internal luting spaces: 25 µm (G25), 50 µm (G50), or 75 µm (G75). The zirconia abutments were cemented on the titanium bases by using a resin cement (Panavia F 2.0) under a constant load of 20 N. The marginal discrepancy and internal fit of 10 random specimens from each group were evaluated with a stereoscopic microscope at ×50 magnification. The remaining specimens were submitted to the tensile strength test in which half were evaluated after dynamic loading (1.2 million cycles of 200 N at 3.8 Hz) in a mechanical fatigue machine. The tensile strength test was performed using a pullout apparatus coupled to a universal testing machine at a crosshead speed of 0.5 mm/min. The mode of failure was determined by observation at ×50 magnification under a stereomicroscope and classified into adhesive or mixed. The groups were compared by using 2-way ANOVA and the Tukey HSD test (α=.05). RESULTS: Increase in the luting space did not influence the marginal discrepancy (P>.05). All zirconia abutments exhibited lower pullout strength after fatigue simulation (P<.05). G75 demonstrated lower tensile strength than G25 and G50 before and after loading (P<.05). Most failures were adhesive at the zirconia-cement interface. CONCLUSIONS: The increase of the luting space to 75 µm did not influence marginal discrepancy; however, it reduced the tensile strength of a zirconia abutment bonded to a titanium base.

Resin-matrix ceramics for occlusal veneers: Effect of thickness on reliability and stress distribution.

OBJECTIVE: To evaluate the influence of resin-matrix ceramic material and thickness on reliability and stress distribution of occlusal veneers (OV). METHODS: One hundred and twenty-six OV of a mandibular first molar were milled using a CAD/CAM system and allocated according to materials (resin nanoceramic (RNC) or polymer-infiltrated ceramic network (PICN)) and thicknesses (0.5, 1.0 and 1.5 mm), totaling six groups (RNC0.5, RNC1, RNC1.5, PICN0.5, PICN1, and PICN1.5). Step-stress accelerated-life testing was performed (n = 21/group) with the load applied at the distobuccal cusp tip of the occlusal veneer until failure or suspension. The use level probability Weibull curves and reliability were calculated and plotted (90% CI). Finite element analysis evaluated the stress distribution according to maximum principal stress (σmax) on the restoration and maximum shear stress (τmax) on the cement layer. RESULTS: There was no difference in the probability of survival for the estimated missions among the groups, except at 600 N in which the results were significantly lower to PICN1.5 (6%) compared to RNC1 (55%) and RNC1.5 (60%). The σmax values were higher for PICN (31.85-48.63 MPa) than RNC (30.78-33.09 MPa) in the same thicknesses. In addition, 0.5 mm groups concentrated more stress in the restoration (33.09-48.63 MPa) than 1.0 mm (31.11-35.36 MPa) and 1.5 mm (30.78-31.85 MPa) groups in the same material. SIGNIFICANCE: Both resin-matrix ceramic materials seem up-and-coming restorative systems for occlusal veneers irrespective of the thicknesses as a consequence of the high reliability.

Effect of Silicon dioxide coating of acrylic resin surfaces on Candida albicans adhesion.

Acrylic resin has been used in the manufacture of prostheses, however, in the oral cavity, this material starts to retain microorganisms capable of causing gingival inflammation due its porosities. The aim of this study was to evaluate the influence of the use of silicon dioxide as a coating layer applied onto acrylic resin, on the adhesion of Candida albicans (Ca). After the incubation period in Sabouraud Dextrose Broth, a total of 1 ml of the Ca suspension was added to plate wells, each well containing a specimen of acrylic resin. The adhesion ability of Ca on acrylic resin was determined by counting colonies. Three groups (n = 6) of acrylic resin were assessed: with polishing (RP); without polishing (RW); with polishing and coating layer of silicon dioxide (RPC). Ca deposited on the surface of the acrylic resin was also observed using Scanning Electron Microscopy (SEM). Statistical assessment by Kruskal-Wallis and Student-Newman-Keuls Method were done (α = 2%). There was significant difference among the groups. The RPC group showed the lowest growth, with an average of 5.59 Log CFU/cm 2 ; there was a statistically significant difference in relation to group RW, which presented a growth of 6.07 Log CFU/cm 2 and to group RP with 5.91 Log CFU/cm 2 (p < 000.1). SEM images demonstrated that in the RP and RPC group, the surface of the resin had greater regularity, and smaller number of microorganisms. The application of silicon dioxide coating on acrylic resin appears to be a promising alternative, and its use can help in reducing the adhesion of Ca in prostheses.