Comparative evaluation of the effect of surface treatment of fiber-reinforced posts and prefabricated metal posts on adhesion of a resin-based luting cement: An in vitro study.

BACKGROUND: The purpose of this study was to evaluate the effect of surface treatment of fiber-reinforce post and metal post of adhesion of a resin luting cement. MATERIALS AND METHODS: Sixty methyl methacrylate specimens were fabricated with a customized metal rod. The samples were segregated into six groups (F1, F2, F3, M1, M2, and M3) of 10 specimens (n = 10) each. The first three groups (F1, F2, and F3) were for fiber posts and (M1, M2, and M3) were for metal posts. The postspace preparation was done with dedicated drills supplied by the postmanufacturers to a length of 14 mm. F1 and M1 were the control groups. The posts in F2 and M2 groups were treated with airborne-particle abrasion with 70 µm Al2O3 particles for 5 s at a constant distance of 20 mm, cleaned with alcohol and cemented in the postspace. The posts in the F3 and M3 groups were treated with airborne-particle abrasion followed by primer application. After cementing the posts into the postspace, the acrylic blocks were sectioned with a motor-driven jigsaw to obtain four specimens each of 3-mm thickness. These sections were then subjected to push-out tests on a universal testing machine. RESULTS: There was a statistically significant increase in the bond strength of both fiber and metal posts to resin cement after airborne-particle abrasion with Al2O3 particles and airborne abrasion followed by primer application. CONCLUSION: There is an increase in the bond strength of the resin cement with the prefabricated posts after the various surface treatments.

Effect of Melaleuca alternifolia Mixed with Tissue Conditioners in Varying Doses on Colonization and Inhibition of Candida albicans: An In Vitro Study.

AIMS AND OBJECTIVES: The study was conducted to evaluate the Colonization & Inhibition of Candida albicans in selected commercially available denture lining materials material by mixing them with varying concentrations and doses of tea tree oil. MATERIALS AND METHODS: Five test discs of 10mm diameter and 1.5mm thickness were prepared using commercially available soft denture lining materials (Viscogel and GC-soft). Tea tree oil of varying concentrations (10%, 20%, 30%, and 40%) and doses (0.5 ml, 1.0 ml, 1.5 ml, 2.0 ml) were added during manipulation. Test discs kept in sterile artificial saliva were inoculated with Candida albicans (ATCC-2091 strain) and incubated for 6 weeks. These discs were fixed, dehydrated air dried and stained using 0.03% acridine orange stain and observed under Fluorescent microscope to count the colonies on the surface of each disc to evaluate the colonization. To evaluate inhibition, test discs were placed on the top of Sabouraud's dextrose agar inoculated with Candida albicans (ATCC-2091 strain). After incubation at 370C for 48 hours, the zone of Inhibition formed around the samples was measured. RESULTS: The GC soft liner had higher mean colonization and lesser zone of inhibition of C.albicans when compared to Visco-gel soft liner (P < 0.001) and highest zone of inhibition observed with 2 ml volume and 40% vol/vol concentration of melaleuca alternifolia (P < 0.05). INTERPRETATION AND CONCLUSION: By the addition of Tea Tree oil, Viscogel had good acquired good antifungal properties than GC-soft lining materials.

Stress Distribution in Bone and Implants in Mandibular 6-Implant-Supported Cantilevered Fixed Prosthesis: A 3D Finite Element Study.

PURPOSE: The purpose of the study was to evaluate by a 3-dimensional finite element analysis the load transmission to periimplant bone by a framework supported by 6 implants placed in an edentulous mandible and to compare the stress distribution for varying cantilever lengths. METHODOLOGY: A computerized model of the anterior segment of a mandible with a 6-implant-supported bridge was created in software. The length of the cantilever segment was considered as 10, 15, and 20 mm. A 150 N load was applied to the terminal point of the cantilever segment, and Von Mises stresses were analyzed along implants, framework, and bone. RESULTS: When the cantilever length was increased from 10 to 20 mm, the stress increased 79.66% in the framework, 68.16% in implants, and 59.96% and 52.81% in cortical and cancellous bones, respectively. CONCLUSION: The greatest amount of stress was seen around the distal-most region of the distal-most implant. The framework absorbed the maximum amount of stresses followed by the implants, cortical bone, and cancellous bone. Extension of the cantilever beyond 15 mm could lead to greater stress in the lingual cortical plate, which could compromise the integrity of the implants.

A Clinical Study Evaluating Changes in the Microbial Flora Around Dental Implants During Various Stages of Implant Restoration.

PURPOSE: This study evaluated the microbial colonization of dental implants in healthy patients before placing the implants and during the various stages of implant treatment. MATERIALS AND METHODS: Saliva (in completely edentulous patients) and gingival crevicular fluid samples (in partially edentulous patients) were collected from patients and analyzed to estimate the growth of microorganisms after culture. Samples were collected during 10 phases of implant placement and prosthesis insertion. Sixty dental implants, 18 of NobelReplace Select (Nobel Biocare) and 42 of GSIII/TSIII (Osstem), were evaluated. The microbial titer was estimated in colony-forming units (CFU) per milliliter. The percentage distribution of the organisms during the various phases was noted and the average was compared. RESULTS: Most prevalent microorganism found was gram-positive Streptococci (3.59 × 10 CFU/mL). The titer of Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Pseudomonas being 0.42 × 10 CFU/ml, 0.15 × 10 CFU/mL, 0.09 × 10 CFU/mL, and 0.03 × 10 CFU/mL, respectively. The titer of these organisms noted during the experimental phase was low. A similarity was observed in the maximum colony-forming unit per milliliter between baseline and completion of implant therapy indicating establishment of equilibrium. CONCLUSION: Regular microbial evaluation along with clinical and radiographic monitoring could help in recognizing the potential for periimplantitis and in prevention of the same.

The influence of thread geometry on biomechanical load transfer to bone: A finite element analysis comparing two implant thread designs.

BACKGROUND: The success of dental implants depends on the manner in which stresses are transferred to the surrounding bone. An important consideration is to design an implant with a geometry that will minimize the peak bone stresses caused by standard loading. The aim of this study was to assess the influence of implant thread geometry on biomechanical load transfer and to compare the difference between two different thread designs. MATERIALS AND METHODS: A three-dimensional finite element model of D2 bone representing mandibular premolar region was constructed. Two implants of differing thread geometries, 13-mm length, and 4-mm diameter along with superstructures were simulated. One design featured fourfold microthread of 0.4-mm pitch, 0.25-mm depth in the crestal one-third; 0.8-mm pitch, 0.5-mm depth in the apical two-third. The other design had a single-pitch microthread of 0.8-mm pitch, 0.25-mm depth in the crestal one-third; 0.8-mm pitch, 0.5-mm depth in the apical two-third. A static axial load of 100-N was applied to the occlusal surface of the prosthesis. ANSYS CLASSIC 9.0 (PA,USA)software was used for stress analysis as von Mises stresses. RESULTS: A comparison of von Mises stresses between two thread designs revealed that fourfold microthread allows better stress distribution within the implant body by 43.85%, abutment by 15.68%, its superstructure by 39.70% and 36.30% within cancellous bone as compared to single-pitch microthread. The effective stress transfer to the cortical bone is lowered by 60.47% with single-pitch microthread. CONCLUSION: Single-pitch microthread dissipates lesser stresses to cortical bone while the implant body, abutment, and superstructure absorb more stress. This will have a positive influence on the bone-implant contact and contribute to preservation of crestal bone. Implant with single pitch microthread will thus be preferable to be used in areas where the amount of cortical bone available is less.

A correlation between bone (B), insertion torque (IT), and implant stability (S): BITS score.

STATEMENT OF PROBLEM: Although criteria for assessing bone quality have been reported, an overall score that correlates bone quality with the primary stability and secondary stability of implants is not yet available. PURPOSE: The purpose of this article was to propose a scoring index that will establish a correlation among the bone density values from computed tomography, maximum insertion torque values, and resonance frequency analysis in different phases of implant treatment. MATERIAL AND METHODS: In this study, 60 implant sites were evaluated to assess bone density (Hounsfield units), insertion torque values (Ncm), and primary stability and secondary stability (implant stability quotient values obtained by using resonance frequency analysis). On the basis of computed tomography data, the bone was classified as D1 to D4. The insertion torque was noted and classified into 2 groups, A and B. The implant stability quotient values obtained from resonance frequency analysis depicting primary stability and secondary stability were classified into 5 groups. The primary score noted was a result of the values obtained for the 3 parameters at the time of implant placement. The secondary score was obtained by considering the values of the bone density and resonance frequency analysis recorded at different time intervals. RESULTS: Bone densities of D2, D3, and D4 were noted, dividing the bone type into 3 groups. The maximum torque noted in the study was 40 Ncm. The difference between various insertion torque values and bone types was found to be statistically nonsignificant. Higher mean implant stability quotient values were obtained for primary and secondary stability for the D2 bone than for D3 and D4 bone. When analyzed according to the time of insertion, the mean values increased at second stage surgery in all bone types. The difference in mean values among all bone types was found to be statistically significant (P<.001). A comparison of primary and secondary implant stability quotient values in all bone types did not find any statistical significance (P=.780). A score was recorded at the time of implant placement and at the time of second stage surgery, and the prosthetic treatment was planned accordingly. CONCLUSIONS: The score highlights the importance of considering the association of bone quality, insertion torque values, and stability as denoted by implant stability quotient throughout treatment. Based on the variation in the score noted at recall visits, alterations in the treatment plan can be made with respect to the healing period and prosthetic design.

Facile preparation of tetrahydro-5H-pyrido[1,2,3-de]-1,4-benzoxazines via reductive cyclization of 2-(8-quinolinyloxy)ethanones and their antioxidant activity.

Pd/C-catalyzed reductive cyclization of 1-aryl-2-(8-quinolinyloxy)ethanones opens a facile access to the title compounds in good yields. The scope of this reductive cyclization is explored and the antioxidant activities of the products are studied.

Maxillary and mandibular first premolars showing three-cusp pattern: an unusual presentation.

Dental anatomy is the study of morphology of various teeth in human dentitions. The application of dental anatomy in clinical practice is important, and dentist should have a thorough knowledge regarding the morphology of the teeth. At times as a result of genetic variation, environmental factors, diet of an individual and race, variations in the morphology of the teeth can be observed. These variations have been extensively studied by the researcher in the field of anthropology to define a particular race. The most commonly observed changes include peg-shaped laterals, shovel-shaped incisors, and extra cusp on molar. Common variations documented with regard to maxillary and mandibular first premolars are the variation in the number of roots. But the variations with respect to crown morphology are few. We report a first documented unusual presentation of maxillary and mandibular first premolars with three-cusps pattern in a female patient.