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.

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.

Comparison of Sagittal Condylar Guidance Angle Obtained by Radiographic Methods and Manual Programming of Articulators in Dentate Patients - A Clinico-radiographic Study.

Background: The ultimate goal of advanced procedures in prosthetic dentistry is to construct a prosthesis based on the accurate reproduction of condylar guidance. Aim: To compare the sagittal condylar inclination obtained using the cone-beam computed tomography (CBCT), panoramic image, and two articulator systems. Settings and Design: A cross-sectional study was carried out in 20 dentate patients in the age group of 20-40 years. Materials and Methods: Sagittal condylar guidance angles (SCGAs) were measured on two semi-adjustable articulators (Hanau Wide Vue and Denar Mark 320) using protrusive interocclusal record. SCGAs were also measured on the CBCT scans (CBCT reconstructed panoramic image and CBCT sagittal cross section) and the panoramic images obtained from the patients. The angles were determined on the radiographs by joining two lines: Frankfort's horizontal plane and the other plane were drawn by connecting the superior-most point on the glenoid fossa and the inferior-most point on the articular eminence. All the measurements were done twice by two operators independently. Statistical Analysis Used: The data were analyzed using the paired t-test and Pearson's correlation coefficient with a P ≤ 0.05. Results: There was no significant difference between the right and the left side in any of the groups (P ≥ 0.05). In addition, there was no significant difference between the clinical methods (P ≥ 0.05). However, there was a significant difference between the clinical and the radiographic methods (P ≤ 0.05). Furthermore, there was a strong correlation between the clinical and radiographic methods with Pearson's Correlation coefficient above 0.67. Conclusion: There is a strong correlation between the clinical and radiographic methods. Thus, CBCT and OPG can be used an adjunct to clinical methods to record sagittal condylar guidance.

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.

Dental implications of bisphophonate-related osteonecrosis.

OBJECTIVES: The aim is to explore the current theories about clinical , pathological and dental management of bisphosphonate related osteonecrosis of the jaws. Also discussed are the actions of bisphosphonates, pathogenesis related to the susceptibility of jaws, the predisposing risk factors for the development of bisphosphonate-related osteonecrosis of the jaws (BRONJ) and diagnostic criteria based on the literature review. DISCUSSION: Osteoporosis is a disease that generally affects the mineral status of both cortical and trabecular bone in post menopausal women. Bisphosphonates are a group of drugs that preserve and increase bone mass. Bisphosphonate drugs are classified according to use and method of delivery. The bisphosphonates used for the treatment of osteoporosis are taken orally. Little is known about the side effects and dangers of the long-term use of therapeutic doses of Bisphosphonates. A recent complication reported is osteonecrosis of jaws. The use of IV bisphosphonates for multiple myeloma and metastatic bone diseases suggests that dosage, length of treatment, and route of administration, as well as cofactors such as use of glucocorticoids and immunosuppressive agents, and dental surgery, could all be related to the incidence of BRONJ. This review provides an update on current knowledge about clinical, pathological and management aspects of BRONJ. CONCLUSIONS: Little evidence exists to direct the prosthodontic management of patients with a history of bisphosphonate use. Patients with active osteonecrosis related to bisphosphonate use have reduced tissue tolerance to function with removable prostheses and decreased potential for osseointegration of dental implants. Decisions should be based on clinical judgment tempered by the presenting conditions, medical profile, and patient needs. A better understanding would help in a dental setting to prevent any complication and help to improve the prognosis for those being treated for osteoradionecrosis.Until further evidence emerges regarding management of patients with active bisphosphonate- related osteonecrosis, conservative prosthodontic treatment is reasonable and prudent.

Evaluation of satisfaction with masticatory efficiency of new conventional complete dentures in edentulous patients--a survey.

BACKGROUND: Knowing how patients really feel after treatment is, very often, as relevant as the success rate of the conventional dentures and it can even be the measurement of masticatory function. AIM AND OBJECTIVES: This questionnaire survey aimed to analyse the satisfaction level and masticatory efficiency of patients treated with conventional complete dentures. DESIGN AND SETTING: Thirty edentulous patients were considered in the study. Satisfaction level and masticatory efficiency were analysed based on specific questionnaires for edentulous patients and by a likert rating scale from 0 to 5, at three moments: Prior to treatment (edentulous period), after the insertion of the new dentures and at 30-45 days follow-up. MATERIALS AND METHODS: Thirty patients including 12 male and 18 female patients (mean age 65 years), who voluntarily came for the services. T-test was applied at three different levels. RESULTS: The rehabilitation with conventional complete dentures produced an improvement (p < 0.05) in satisfaction level and masticatory efficiency. CONCLUSION: Thus, those patients who were edentulous previously and dissatisfied with their masticatory ability showed improvement after receiving a new set of conventional complete dentures.

Evaluation of Risk Factors of Peri-Implant Disease Using a New Manual Risk Assessment Model: A Clinical study.

Background: Implants are being widely used as a treatment option and are considered the best line of treatment owing to their high level of predictability. However, over 5 years, 0-14.4% of dental implants have demonstrated peri-inflammatory reactions associated with loss of crestal bone and ultimately loss of the implant. Peri-implant diseases are categorized into peri-implant mucositis and peri-implantitis. There are a number of risk factors associated with these conditions, and the early detection of these possible risk factors, change in the treatment protocol whenever required along with a regular follow-up, can ensure a better survival rate of dental implants. In the present study, an attempt has been made to evaluate the risk factors associated with peri-implant diseases and also to correlate these risk factors to the prevalence of peri-implant diseases using the formulated risk assessment model. Methodology. The risk assessment model was prepared based on existing literature explaining the risk factors for peri-implant diseases. This study was conducted as a pilot study, and the method of complete sampling was used wherein all subjects in whom implants have been placed at the Department of Periodontology and Department of Prosthodontics were recalled and assessed. The model was then evaluated on patients in whom dental implants were placed and the implants were loaded for a year. A total of 13 subjects with 21 implants were assessed for the presence or absence of risk factors, and a score was given. Test of proportion and chi-square test was done. Results and Discussion. Of the 21 implants assessed, 15 implants were found to be at low risk and 6 implants with moderate risk of peri-implant disease. The number of implants with low risk was higher in implants with peri-implant mucositis (25%) whereas the implants with moderate risk was higher in implants with peri-implantitis (75%). This comparison was statistically significant with a p value of 0.022. Conclusion: This risk assessment tool can be used in the early detection of peri-implant disease, and identifying the risk factor may help in the success rate of the implant survival.

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.

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.

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.

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.

Critical Assessment on Unmet Oral Health Needs and Oral Health-related Quality of Life Among Old Age Home Inhabitants in Karnataka, India.

PURPOSE: To critically assess the unmet oral health needs and oral health-related quality of life among old age home inhabitants in Karnataka, India. METHODS: A total of 96 older adults (males=32, 33.33%, females=64, 66.67%) aged 60 years and above, residing in old age homes were included in this cross-sectional study. The mean age of the participants included in the study was 69.25±7.99 years. Oral health status and dental needs were assessed using the Oral Hygiene Index Simplified (OHIS) and the WHO Oral Health Assessment forms. Oral health-related quality of life was evaluated by administrating the Geriatric Oral Health Assessment Index (GOHAI) questionnaire through an interview format. STATISTICAL ANALYSIS: The Statistical Package for Social Sciences (SPSS) version 17 was used. Descriptive statistics was tabulated for oral health status and GOHAI scores. Student's t-test and ANOVA were applied to check the association of the GOHAI responses with the number of years of residence in old age homes, age groups, gender, and dentition status. RESULTS: The mean age of the participants included in the study was 69.25±7.99 years. Twenty-six (27.1%) participants reported diabetes mellitus and hypertension. Most of the participants 89 (91.7%) visited the dentist when they had dental complaints. Among the dentulous study population, the majority of the participants had untreated dental caries indicated for dental extraction and needed periodontal therapy. Amongst the participants, 68 (70.82%) required prosthetic rehabilitation. More than 10 years of residence in old aged homes, over 80 years of age, being female, and completely edentulous groups showed lower total GOHAI scores compared to their counterparts. CONCLUSION: The majority of the participants showed unmet oral health needs and lower GOHAI scores indicating poor oral health-related quality of life.

Evaluation of chemical disinfection and microwave irradiation on denture base materials: An in vitro study.

OBJECTIVE: This study evaluated the effect of chemical disinfection and microwave irradiation on the surface hardness and roughness of two commercially available hard relining materials (Ufi Gel hard, GC Kooliner) and one denture base resin (Trevalon). MATERIALS AND METHODS: A total of 72 specimens (n = 24) were divided into four groups. C: Not disinfected, Cl: disinfected with 4% chlorhexidine solution, Gl: disinfected with 2% glutaraldehyde solution, Mw: disinfected with microwave irradiation (650 W; 6 min). Hardness and roughness measurements were made after polymerisation, 1st day, 14th day and 28th day. RESULTS: Ufi Gel hard showed an increased roughness after 1st day (P = 0.021) following chemical disinfection and GC Kooliner showed similar results after 14th day (P < 0.05). Microwave irradiation showed a significant increase in surface roughness value after 1st day (P < 0.05) for both Ufi Gel hard and GC Kooliner. Hardness of both Ufi Gel (12.131 to 7.333 VHN) and Kooliner (9.133 to 5.276 VHN) was significantly reduced by chemical disinfection, while microwave irradiation resulted in an increased surface hardness of Kooliner (from 9.126 to 12.713 VHN) and Ufi Gel hard (from 11.698 to 14.940VHN). Results for Trevalon were not significant for both the disinfection methods. CONCLUSIONS: Microwave irradiation increased the surface roughness and hardness of Ufi Gel hard and Kooliner, while chemical disinfection resulted in a decreased hardness and increased roughness of both hard relining materials. There was no effect of either of the disinfection methods on Trevalon.

Microbial assessment of dental unit waterlines in an institutional setup in Karnataka, South India.

BACKGROUND AND AIM: Biofilms in dental unit waterlines (DUWLs), suction hoses, and fittings are a potentially significant source of cross-contamination posing significant health risk as these may come into contact with patients during treatment. The purpose of this in vitro study was to identify the spectrum of bacterial flora colonizing the DUWLs and to detect pathogenic microorganisms present in such an environmental niche. MATERIALS AND METHODS: Thirty DUWL samples were collected from in use dental units selected randomly from various clinical departments. Samples were collected from the following devices; 3-in-1 syringe waterline, section of waterline tubing supplying the 3-in-1 syringe, and the air rotor water. The samples were subjected to bacteriological analysis, and all bacterial isolates were tested for their ability to form biofilms. RESULTS: A descriptive analysis of the results obtained was carried out, and it was observed that 7 out of 30 (23.3%) samples collected from DUWL were supplying water of unsatisfactory quality with species of low-pathogenicity bacteria isolated present in significant numbers; four of ten (40%) water supply lines contained bacterial biofilms; and the species with greatest capability to form biofilms were Enterobacter species (spp.). In addition, the results were also subjected to Chi-square test which revealed no statistical difference between the species and the location of collection of samples. CONCLUSION: Within the limitations of this study, it is concluded that DUWLs are not totally free of contamination. Microbial biofilms are a significant source of cross-contamination and cross-infection in the dental clinic environment.

Evaluation of effect of recasting of nickel-chromium alloy on its castability using different investment materials: An in vitro study.

CONTEXT: Castability has been found to be affected by many aspects of the entire casting system. Very few references in dental literature are available regarding recasting of the base metal alloys. AIMS: To evaluate and compare the castability of fresh and reused nickel-chromium alloy and to evaluate the effect of two brands of investment materials on castability of nickel-chromium alloy. SUBJECTS AND METHODS: For the experimental purpose of evaluation of the effect of recasting of nickel-chromium alloy on its castability, different percentages of new and casted alloy (Nickel-chromium alloy-(Wirolloy NB, Type 4 (Ni-67%; Cr-25%; Mo-5%; Si-1.5%; Mn, Nb, B, C each <1%) and two commercial brands of investment materials namely, Deguvest Impact (Degudent; Dentsply Germany) and Bellavest SH (Degudent; Dentsply Germany) was used to obtain 30 samples. Castability value was obtained using Whitlock's formula. Student t-test and one way ANOVA using SPSS 20.0 software was done. RESULTS: The results of this study confirm earlier works that demonstrate that there is no significant difference in castability values of new and recast alloys. In addition, it also demonstrated, there was no difference in castability using Deguvest Impact and Bellavest SH investment materials. CONCLUSIONS: Within the limitations of the study, it was concluded that there was no significant difference found in castability of different percentage combinations of new and once casted alloy using two investment materials. The addition of new alloy during recasting to maintain the castability of nickel-chromium alloy may therefore not be required.

Prosthetic rehabilitation of a patient after partial maxillectomy: A clinical report.

Malignant melanoma of the oral cavity is very rare. This clinical report describes a method for prosthetic rehabilitation of a patient with malignant melanoma of the palate following partial maxillectomy with a closed hollow interim obturator.