Effect of post etching cleansing on surface microstructure, surface topography, and microshear bond strength of lithium disilicate.

AIM: This study assessed the effect of postetch cleansing on the surface microstructure, surface topography, and microshear bond strength (µSBS) of lithium disilicate and the resin cement. SETTING AND DESIGN: In Vitro analytical study. MATERIALS AND METHODS: Fifteen discs (10 mm diameter and 2 mm thickness) were fabricated from highly translucent lithium disilicate IPS Emax 2 ceramic (Ivoclar Vivadent, Schaan, Liechtenstein). Four resin cement (RelyX Ultimate, 3M ESPE) cylinders (0.9 mm diameter and 4 mm high) were placed on each ceramic disc (total n = 60). The samples were divided into three groups based on the surface treatment of the ceramic discs (20 resin cement cylinders on 5 discs in each group). Group I (HF) (control) etched with 9.6% HF with no postetch cleansing, Group II (HFP) etched with 9.6% HF for 20 s followed by rinsing with water and postetching cleansing with 37% phosphoric acid, and Group III (HFPU) etched with 9.6% HF followed by active application of 37% phosphoric acid followed by postetch cleansing in ultrasonic bath for 5 min. µSBS of resin cement to ceramic surfaces was tested following a standard protocol. Surface roughness was evaluated using an atomic force microscope. Surface topography and elemental analysis were analyzed using SEM/EDX. Mode of failure was also assessed. STATISTICAL ANALYSIS USED: The data were analysed using one way analysis of variance and post hoc tukeys test. RESULTS: The µSBS were found to be highest for Group III (HFPU), followed by Group II (HFP) followed by Group I (HF) and were statistically significant. There was a difference in the surface topography and surface microstructure between the three groups. Mode of failure was predominantly adhesive. CONCLUSION: The µSBS, surface topography, and surface microstructure were found to be superior in the groups, in which postetch cleansing was done as compared to the control in which no postetch cleansing was done.

A Comparative Evaluation of Stress Distribution with Two Attachment Systems of Varying Heights in a Mandibular Implant-Supported Overdenture: A Three-Dimensional Finite Element Analysis.

PURPOSE: To analyze and compare the stress distribution in an implant-retained overdenture complex using ball and Locator attachments of three heights by means of a 3D finite element analysis (FEA). MATERIALS AND METHODS: Six finite element models comprising an edentulous mandible with two interforaminal bone-level implants and ball attachments of heights 1 mm (A1), 3 mm (A3), and 5 mm (A5), and Locator attachments of heights 1 mm (B1), 3 mm (B3), and 5 mm (B5), were designed using ANSYS Workbench Software. Unilateral vertical (100 N) and oblique loads (100 N at 30° to the longitudinal axis of the implant in buccolingual direction) were applied. Average von Mises stress values were evaluated quantitatively and qualitatively. RESULTS: Locator attachments showed lower stress values as compared to the ball attachments in all examined areas. The increase in the height of both resulted in increased stress values. Higher values were observed at the implant neck in all models, as compared to the body and the apex. The recorded stress was higher in the cortical bone as compared to the cancellous bone. CONCLUSIONS: Within the limitations of the study, Locator attachments demonstrated lesser and more homogenous stress distribution in the implant-overdenture complex in comparison to ball attachments. The stresses generated within the tissues increase with an increase in collar height of the attachment system and therefore, attachments should be as short as possible for more favorable stress transmission.

Osseodensification - A novel approach in implant dentistry.

Primary stability in dental implants is an essential factor for achieving successful osseointegration. Surgical procedure and bone quality are among the most common factors that affect primary stability. It is also crucial to achieve high-insertion torque which is important for obtaining primary stability. Maintaining sufficient bone bulk and density is essential to achieve necessary bone-to-implant contact for obtaining a biomechanically stable implant. A new concept for osteotomy called osseodensification (OD) has been at the forefront of changes in surgical site preparation in implantology. This relatively new concept with universally compatible drills has been proposed to help in better osteotomy preparation, bone densification, and indirect sinus lift and also achieve bone expansion at different sites of varying bone densities. This procedure has also shown improvement in achieving better implant primary stability and better osteotomy than conventional implant drills. A systematic review was undertaken to analyze if OD procedure had any advantages over conventional osteotomy on bone density and primary stability. An electronic database search was conducted in PubMed using keywords such as "OD," "implant primary stability," "implant bone density," and "implant osteotomy." A total of 195 articles were collected and subjected to screening using inclusion and exclusion criteria. A literature review was done, following which it was seen that the use of versah drills for bone OD resulted in undersized osteotomy compared to conventional drills. It also resulted in improved bone density and increase in percentage bone volume and bone-to-implant contact, thereby improving implant stability.

A clinical assessment of the volume of interproximal papilla after definitive prosthesis around immediate and delayed loading implants placed in the maxillary esthetic zone: An in vivo study.

BACKGROUND: The presence of the dental papilla is critical to achieve esthetics in a single tooth implant restoration. AIM: The purpose of this study was to determine if there were differences in the papilla fill between implant and teeth comparing immediate implant placement and provisionalised single tooth implant restorations with delayed implant placement and provisionalised single tooth implant restorations. The papilla fill in these two groups was evaluated using the Jemt papilla index. RESULTS: It was seen that there was no statistically significant difference seen in the volume of the papilla between both the groups. There was a statistically significant difference seen in both the groups on the distal and mesial side from the initial stage go the follow up period of 10 days, 3 months and 6 months. CONCLUSION: The interpretation of clinical papilla is a difficult task since many different clinical situations can be encountered while studying single tooth implant restorations. The single tooth implant restoration is a specific entity; the distance between the mesial and the distal side of one implant is never the same. Therefore the present study analysed the papilla as a unit and focused on the vertical fill related to the implant and adjacent teeth.

Impact of occlusal support and perceived chewing ability on oral health-related quality of life among patients attending a private dental institution in India.

PURPOSE: Presence of functional tooth units is essential for preserving masticatory function among individuals. Representing the essence of health promotion practice, demand to measure varied evaluation outcomes is highlighted. AIM AND OBJECTIVES: (1) To assess the influence of occlusal support and perceived chewing ability on oral health-related quality of life (OHRQoL) among adults attending a private dental institution in Mangalore. (2) To evaluate occlusal support using Eichner index (EI), perceived chewing ability using a self-administered questionnaire and OHRQoL using Oral Health Impact Profile-14 (OHIP-14). MATERIALS AND METHODS: Overall, 300 adults attending a private dental institution in Mangalore were included. EI was used to group participants into three groups. The chewing ability was assessed using a questionnaire on perceived difficulty while chewing eight common foods. OHRQoL was measured employing OHIP-14. Perceived general and oral health status and demographic information were collected. RESULTS: The mean perceived chewing ability score was 12.98 ± 6.2 and the mean total OHIP score was 9.23 ± 8.9. EI showed a significant relation with perceived chewing ability, OHIP, and perceived general health status (P < 0.05). Perceived chewing ability and OHIP demonstrated a significant correlation (r = 0.31, P < 0.001). Age, gender, education, occupation, monthly income, family income, and number of family members demonstrated a significant association with EI (P < 0.05). Binary logistic regression analysis revealed that EI, perceived chewing ability, and perceived oral health emerged as significant predictors of OHRQoL (P < 0.05). CONCLUSIONS: Occlusal support was significantly associated with perceived chewing ability, OHRQoL, and perceived general health status.

Comparative evaluation of antifungal action of tea tree oil, chlorhexidine gluconate and fluconazole on heat polymerized acrylic denture base resin - an in vitro study.

OBJECTIVE: Candida albicans-associated denture stomatitis is the most common type of denture stomatitis seen in denture wearers. This study evaluates and compares the antifungal action of fluconazole, chlorhexidine gluconate and tea tree oil on heat-polymerised denture base resin, which has been previously contaminated with C. albicans grown in BHI broth. MATERIAL AND METHODS: Seventy-five specimens were immersed in BHI broth previously inoculated with C. albicans and stored for 3 h at 37°C. They were divided into five groups (n = 15): G1: 2% chlorhexidine solution; G2: 100% pure pharmaceutical grade tea tree oil; G3: 65 µg/ml fluconazole solution; C1: specimens not disinfected; C2: specimens not contaminated with Candida. Each specimen was then transferred to individual tubes containing BHI broth and incubated for 24 h. Culture media turbidity was evaluated for absorbance over a period of 14 days using a microplate reader. It was observed that the lower the absorbance, the stronger the antimicrobial action. Statistical analysis was performed (two-way anova and Bonferroni test, p < 0.001). RESULTS: Chlorhexidine and tea tree oil inhibited Candida up to the 14th day, whereas antifungal effect of fluconazole was not significant after the 7th day. CONCLUSION: Tea tree oil and chlorhexidine gluconate are more effective than fluconazole in inhibiting C. albicans growth on heat-polymerised acrylic resin.

Best practices for the development, scale-up, and post-approval change control of IR and MR dosage forms in the current quality-by-design paradigm.

In this whitepaper, the Manufacturing Technical Committee of the Product Quality Research Institute provides information on the common, best practices in use today in the development of high-quality chemistry, manufacturing and controls documentation. Important topics reviewed include International Conference on Harmonization, in vitro-in vivo correlation considerations, quality-by-design approaches, process analytical technologies and current scale-up, and process control and validation practices. It is the hope and intent that this whitepaper will engender expanded dialog on this important subject by the pharmaceutical industry and its regulatory bodies.

Effect of addition of titanium dioxide nanoparticles on the antimicrobial properties, surface roughness and surface hardness of polymethyl methacrylate: A Systematic Review.

Background: Polymethyl Methacrylate (PMMA) denture-base resins have poor surface properties that facilitates microbial adhesion causing denture stomatitis. This systematic review aims to evaluate the effect of different sizes and percentages of titanium dioxide nanoparticles (TiO2NP) on the antimicrobial property, surface roughness and surface hardness of PMMA denture base resin.  Methods: A systematic search of English peer-reviewed articles, clinical trial registries, grey literature databases and other online sources was performed using the PRISMA-S Guidelines for In-Vivo and In-Vitro studies. Qualitative data synthesis was performed to analyse sample dimensions, acrylic used, treatments of nanoparticles, methods used for testing and effect of size and percentage of nanoparticle. Risk of bias assessment was done using modified Cochrane risk of bias tool. Results: Out of 1376 articles, 15 were included. TiO 2NP of size less than 30 nm was most frequently used. Both antimicrobial property and surface hardness improved irrespective of the size of the added TiO 2NP. Three studies reported increase in the surface roughness with less than 50 nm TiO 2NP.  3% TiO 2NP was most frequently used. On increasing the percentage, three studies reported an increase in antimicrobial property, while two studies found no change. With TiO 2NP greater than or equal to 3%, six studies reported an increase in surface hardness, while two reported increase in surface roughness. Large methodological variations were observed across studies. All studies except one were of moderate quality. Conclusions:   On addition of TiO 2NP to heat polymerized PMMA, the antimicrobial property and surface hardness improved irrespective of the size of the TiO 2NP, however, addition of nanoparticles less than 50 nm increased the surface roughness. Increasing the percentage of TiO 2NP increased the surface hardness but did not always increase the antimicrobial property. Addition of 3% TiO 2NP provided optimum results with regards to antimicrobial effect and surface hardness, but increase in the surface roughness.

Translucency characteristics of permanent maxillary central incisor in Indian population: An analytical cross-sectional study.

Background: Understanding the optical characteristics, especially the translucency patterns (TPs) in teeth can assist clinicians in creating biomimetic restorations. Aim: This study assessed the differences in enamel TPs and the area of translucency (AOT) in the most dominant teeth of an individual's smile according to their age and gender. Materials and Methods: This cross-sectional study was conducted on 140 consented individuals. Based on the age, there were four groups with 35 subjects in each. The digital imaging method is used to classify and differentiate different TPs. The AOT was measured with the assistance of ImageJ 1.51j8 software. Statistical Analysis Used: One-way ANOVA with a post hoc test was used to test the statistical significance difference among the various age groups, and an independent t-test was used to test the variations between genders. Results: The outcome of this study showed that the AOT was the highest for the 50 and above age group as compared to other age groups (P = 0.003). Although there were variations in the TPs between the two genders, the AOT showed no significant difference. Conclusion: The area of incisal third translucency in the upper central incisors varied between different age groups. However, gender had no influence in the area of incisal translucency. Wide variations in the TPs were seen based on age and gender.

Prevalence of metabolic syndrome and its association with atrial arrhythmias in patients with implanted permanent pacemaker for cardiac conduction abnormality.

The objective of the study was to find the prevalence of metabolic syndrome along with identifying the atrial arrhythmias, QTC interval, and coronary artery disease among these patients during follow-ups. Among 171 subjects who were implanted with permanent pacemakers, metabolic syndrome was present in 90 (52.6 %). Prevalence of Arrhythmias was 49 (28.7 %), atrial tachycardia (AT)/atrial fibrillation (AF) was seen in 29 (17 %) patients. Our study showed that there is a strong association between metabolic syndrome and atrial arrhythmias. Metabolic syndrome, age, coronary artery disease and Systolic blood pressure were good independent predictors of atrial arrhythmias among patients with pacemaker implantation.

A Nonlinear Three-Dimensional Finite Element Analysis of Stress Distribution and Microstrain Evaluation in Short Dental Implants with Three Different Implant-Abutment Connections in Single and Splinted Conditions in the Posterior Mandible.

Background: Stress distribution plays a vital role in the longevity and success of implant-supported prosthesis. This study evaluated the von Mises stress and microstrain in the peri-implant bone and the implant-abutment junction of short dental implants with three different implant-abutment connections in splinted and unsplinted conditions using finite element analysis (FEA). Materials and Methods: In this experimental study, nine transversely isotropic finite element models were developed, and randomly divided into three equal groups (n = 3): control, (Group AC) single-standard 4.3 × 10 mm bone level implant-supported restorations with external hexagonal (EH) connection, internal conical (IC) and internal trichannel (ITC) connection, single short implant-supported restorations (Group AT), and splinted short implant-supported restorations (Group B) for each of the three implant-abutment connections, respectively. A 200 N load was applied along the long axis of the implants and a 100 N (45°) oblique load was applied and von Mises stress and microstrain values were evaluated. Results: Single standard implants demonstrated the highest von Mises stress and microstrain values followed by single short implants and splinted short implants, respectively. Among the implant-abutment connections, the IC connection showed the highest values and the ITC connection showed the least values. Conclusion: Within the limitations of this study, it was concluded that splinting of short dental implants demonstrated lesser and more homogeneous stress and microstrain, especially on oblique loading. The microstrain values for all connections evaluated were within the physiological loading limit (200-2,500 N) and were hence considered safe for clinical use.

Cytotoxicity of dental cement on soft tissue associated with dental implants at different time intervals.

Background: To investigate and compare the effect of four commercially used dental cement at 24 hours, 48 hours,72 hours (h) and 6 days on the cellular response of human gingival fibroblast (HGF). Methods: 3 cement pellet samples were made for each 4-test cement (n=12). The cement used for this study were zinc phosphate (ZP), zinc oxide non-eugenol (ZOE), RelyX U200 (RU200), and glass ionomer cement (GIC). The cytotoxicity of peri-implant tissues was investigated using one commercial cell line. All processing was done following International Organization for Standardization (ISO) methods 10993-5 and 10993-12 (MTT assay Test). Cell cultures without dental cement were considered as control. Standard laboratory procedures were followed to permit cell growth and confluence over 48 hrs after sub-cultivation. Before being subjected to analysis, the cells were kept in direct contact with the cement samples for the suggested time period. To validate the results the specimens were tested three times each. Cell death and inhibition of cell growth were measured quantitatively. Results were analyzed using 1-way ANOVA (a=0.05) followed by Tukey B post hoc test. Results: The study showed the dental cement test material was cytotoxic. ZOE, ZP, GIC, and RU200 were cytotoxic in decreasing order, respectively, significantly reducing cell viability after exposure to HGF (p <0.001). Conclusions: Within the limitations of this in-vitro cellular study, results indicated that HGF were vulnerable to the test the dental cement. The highest cytotoxicity was observed in ZOE, followed by ZP, GIC, and RU200.

Two-step impression for atrophic mandibular ridge.

BACKGROUND: The clinical difficulties encountered while treating edentulous patients with atrophic mandibular ridges are legion. Capturing tissue details while making an impression of a resorbed mandibular ridge poses a great clinical challenge. Extending the denture bases adequately to cover all of the available supporting tissues is one of the prime requisite. Surgical approach is necessary only when the patient is incapable of wearing a conventional denture. This article describes a technique of making an impression of an atrophic mandibular ridge by the use of monophase and light-bodied impression material where surgical options such as implants, vestibuloplasty or ridge augmentation may not be feasible. This procedure results in improved stability and retention of the denture base.

Biomechanical Stress Analysis of Platform Switch Implants of Varying Diameters on Different Densities of Bone.

PURPOSE: The purpose of this study was to evaluate and compare the strain developed in D2 and D3 types of bones on vertical loading by platform switch implants of different diameters. MATERIALS AND METHODS: Implants of diameters 3.25 mm, 4.2 mm, and 5.0 mm and of length 11.5 mm were taken and placed each on D2 and D3 bone models. Strain gauges were attached on the buccal and the lingual sides on each of these samples, and a vertical load of 190N was placed on the samples. The strain was recorded using a data logger. The data obtained was analysed using one-way ANOVA and post hoc Tukey test. RESULTS: In D2 and D3 bone models, 3.25 mm significantly showed greater bone strain values. The buccal side strain was higher irrespective of the implant diameter and density of bone. CONCLUSION: Within the limitations of the study, it may be concluded that the narrow diameter implant produces greater strain than 4.2 and 5.0 mm diameter implants, respectively. The buccal side consistently produced higher bone strain values.

Effect of Different Surface Treatments on the Micro-Shear Bond Strength and Surface Characteristics of Zirconia: An In Vitro Study.

Purpose: To study the effect of different surface treatments on the micro-shear bond strength and surface characteristics of zirconia. Methods: Two types of zirconia ceramics were tested: opaque (O) and translucent (T). Each type of zirconia was further allotted into four groups based on the type of surface treatment method. The four groups were: control (C), air abrasion with 110 µm Al2O3 particles (A), etching with Zircos-E Etching solution for 2 hours (E), and a combination of air abrasion and etching (AE). After the surface treatment, all specimens were ultrasonically cleaned and 10 resin cement cylinders were attached to the zirconia discs in each group. A micro-shear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture surfaces were assessed under a compound microscope. SEM, EDAX, and AFM analyses were done for the zirconia specimens after being subjected to surface treatment. Statistical analysis for the bond strength test was done using the Shapiro-Wilk test, one-way analysis of variance (ANOVA), and Post hoc Tukey test. Results: The micro-shear bond strength values for the groups were as follows in megapascals (MPa): OC 18.96 (5.54), OA 22.66 (2.51), OE 28.48 (4.50), OAE 28.63 (4.53), TC 22.82 (5.46), TA 25.36 (5.17), TE 28.12 (4.76), and TAE 32.00 (3.47). The one-way analysis of variance (ANOVA) and post hoc Tukey HSD tests were done which showed significant results in the groups. In opaque zirconia, significant differences were seen in the etching and air abrasion with etching groups when compared with the control and air abrasion groups. There was no difference between the etching and air abrasion with etching groups. For translucent zirconia, the only significant difference was seen in the air abrasion with etching group in comparison with the control and air abrasion groups. The mode of failure was majorly adhesive. The surface topography and surface roughness showed significant differences between the groups. The EDAX results showed material loss that occurred due to sandblasting in the air abrasion groups. Conclusions: Etching with Zircos-E Etching solution significantly increased the bond strength of zirconia to resin cement when compared with other surface treatment methods. In translucent zirconia, the best results can be achieved by combining etching with air abrasion.

An In Vitro Study on the Shear Bond Strength of Feldspathic Porcelain to Nickel Chromium Alloy and Cobalt Chromium Alloy after Various Surface Treatments.

Background: To evaluate and compare the shear bond strength of feldspathic porcelain to four distinctively surface-treated Ni-Cr and Co-Cr alloys and to assess the impact of oxidation-heat treatment on porcelain to base metal alloy bond strength. Methods: 40 specimens each of nickel-chromium alloy and cobalt-chromium alloy were cast. A total of four groups of specimens were created. Group I was surface-treated by sandblasting with 50 µm alumina particles, Group II was surface-treated by sandblasting with 110 µm alumina particles, Group III and Group IV were surface-treated with 250 µm alumina particles. In Group IV, after sandblasting initially with 250 µm alumina particles, the alloys were subjected to oxidation and resandblasting with 250 µm alumina particles. Each of the specimen was coated with opaque and body porcelain and fired to a total thickness of 2 mm porcelain. A universal measuring machine was used to assess shear bond strength at a crosshead speed of 0.5 mm/min. Results: Two-way ANOVA followed by Tukey's post hoc test was used to assess the significant difference within the groups. Unpaired t-test was used for the intergroup comparison of the obtained data. The study showed that the size of the air abrasion particles used for sandblasting significantly influenced the porcelain to metal surface bond strength, with p value <0.001. The bond strength values of the two alloys tested showed no major variations. Result also showed that oxidation influences the metal-ceramic bond strength. Conclusions: The bond strength of the metal-ceramic interface is influenced by the alloy's surface treatment. The oxidation process impacts the bond strength of the metal-ceramic system.

Cytotoxicity of Dental Cements on Soft Tissue Associated with Dental Implants.

PURPOSE: To investigate and compare the cellular host response of human gingival fibroblasts (HGF) on four currently used cements. Methods and Material. 5 cement pellet samples were made for each of the 4 test cements (n = 20). The cements used for this study were zinc phosphate, zinc oxide noneugenol (ZOE), RelyX U200, and glass ionomer cement (GIC). One commercially available cell line was used to investigate the cytotoxicity of peri-implant tissues. Direct contact cell culture testing was conducted following International Organization for Standardization (ISO) methods 10993-5 and 10993-12 (MTT assay test). Cell cultures without dental cement were considered as control. Cells were allowed to grow and confluence over 48 hours after subcultivation according to standard laboratory procedures. The cells were kept in direct contact with the cement samples for 24 hours before being subjected to analysis. All specimens were tested in triplicate to validate the results. Quantitative evaluation of cytotoxicity was done to measure cell death and inhibition of cell growth. Results were analyzed using 1-way ANOVA (a = 0.05) followed by Tukey B post hoc test. RESULTS: The results of the study showed that HGF was vulnerable to the dental cement test material. GIC, zinc phosphate, ZOE, and resin cement were cytotoxic in decreasing order, respectively, and significantly reduced the cell viability after exposure to HGF (p < 0.001). CONCLUSIONS: Within the limitations of this in vitro cellular study, results indicated that the test dental cements were cytotoxic to HGF. The highest cytotoxicity was observed in GIC followed by zinc phosphate, ZOE, and resin cement.

A technique to achieve predictable iris positioning and symmetry in ocular and orbital prostheses.

An alternative technique for achieving predictable iris positioning and symmetry for ocular and orbital prostheses using a mounted graph grid is proposed.

Evaluation of Stress Generated with Different Abutment Materials and Angulations under Axial and Oblique Loading in the Anterior Maxilla: Three-Dimensional Finite Element Analysis.

PURPOSE: The aim of this study was to assess and correlate the stress distribution in an anterior maxillary implant-supported prosthesis with 0°(degree), 15°, and 25° angulated titanium and zirconia abutments using a three-dimensional (3D) finite element analysis (FEA). MATERIALS AND METHODS: Six FEA models consisting of a dentate anterior maxilla with a single bone-level implant of dimension 4.2 × 10 mm placed in the region of left maxillary central incisor and abutments of dimension 4.2 mm made of titanium and zirconia each with angulation 0° (IA and IB), 15° (IIA and IIB), and 25° (IIIA and IIIB) and ANSYS Workbench software were utilized to design a layered zirconia crown. Unilateral axial and oblique loads of 178 N were applied on the palatal aspect of the crown of left maxillary central incisor. Average von Mises stress values were evaluated in the implant and the peri-implant bone quantitatively and qualitatively. RESULTS: Stress was shown to increase with an increase in angulation in all the areas that were examined. Zirconia abutments showed lesser stress in the implant and surrounding bone than titanium abutments. When compared with the body and apex of the implant, the implant neck values were higher in all models. In between cortical and cancellous bone, the stress recorded was higher in the cortical bone. CONCLUSION: Within the limitations of this study, straight abutments generated a more uniform and minimal stress in implant and peri-implant bone than angulated abutments. Titanium abutments generated higher stress levels than zirconia abutments. The stresses generated are directly proportional to an increase in abutment angulation, and therefore, straight abutments are most suitable for favourable stress transmission.