This is an in vitro study for comparative evaluation of transverse bond strength, peel bond strength and water sorption properties between heat polymerized and auto-polymerized resins.

Two denture soft liners (Molloplast-B, Coe-Soft) were investigated. A total number of 60 specimens were used. Twenty specimens were used for evaluation of each physical property of soft liner. For transverse bond strength, ten specimens (64 ⨯ 2.5 ⨯ 10 mm) of each liner were made by processing the denture liners with heat cure polymethyl methacrylate (Meliodent). All specimens for transverse bond strength were conducted on samples immersed in distilled water at 37°C for 50 hours by using three-point transverse flexural tests in a Lloyd's Universal Testing Machine and transverse bond strength was calculated based on the maximum load, span length, breadth and thickness. Another set of ten specimens of (75 ⨯ 25 ⨯ 3 mm) of each denture liner were bonded over 25 mm of heat cure PMMA and separated over the remaining 50 mm of acrylic plate to estimate the peel bond strength. The peel bond strength were conducted on specimens which were dried at room temperature for 48 hours and tested at 21 1 ± C in a Lloyd's testing machine that was linked to an IBM Compatible Computer. The specimens were deformed with a cross head speed of 5 mm/minute according to ASTMD-903 and peel bond strength was calculated when peel angle was 180°. For water sorption tests, ten disc shaped samples of each liner of 50 mm in diameter and 0.5 mm in thickness were fabricated. After polymerization of the liners, the samples were then stored in distilled water at 37°C for 7 days. After one week, excess moisture was removed and each sample was weighed using electronic weighing machine.

The transverse bond strength of Molloplast-B and Coe-Soft were almost similar and did not show any significant difference in their values. But, there is a significant decrease in the peel bond strength and water sorption property of Molloplast-B and Coe-Soft.

The reason for transverse bond strength results being similar for both the liners is because they were polymerized chemically with the denture base resins and this chemical affinity could have made its bond strength almost equal. Since, there is a decrease in the peel bond strength of Molloplast-B, the chances of stripping of the liner at the flanges of the denture is minimal. The decrease in water sorption of Molloplast-B can be expected to retain the bond with the denture and sustain the resilience property of the material for a longer time.

Krishnappan PL, Jaiesh R, Swa- minathan TN. Comparative Evaluation of Heat-Polymerized and Auto-Polymerized Soft Liners with Regard to Transverse Bond Strength, Peel Bond Strength and Water Sorption: An in vitro Study. Int J Prosthodont Restor Dent 2014;4(3):61-67.

To determine the variations in average distances between various facial landmarks used to determine the vertical dimension of rest and occlusion among dentulous and edentulous subjects. Besides determining the reliability of these facial measurements against commonly used Chin-Nose distance, this study would also compare the difference between cephalometric landmarks (anterior nasal Spine-Menton) with the Chin-Nose distance (Niswonger's method).

To standardize the measurement and minimize errors associated with observer and subject movement, a novel instrument was designed in the form of an apparatus and was named as subject and device stabilizing apparatus (SDSA). One hundred and twenty subjects, in the age group of 30 to 60 years, were selected and divided into two equal groups which were further subdivided into subgroups. Measurements were recorded with the help of a digital vernier that was attached to the apparatus. The various facial measure- ments studied were Pupil-Stomion, Glabella-Subnasion, Pupil-Pupil and Angle-Angle both at rest and in occlusion. These measurements were then compared with Chin-Nose and anterior nasal Spine-Menton distance. Differences between the dentulous and edentulous subjects at rest and at occlusion were noted and statistically analyzed using unpaired ‘t’ test and Karl Pearson correlation coefficient.

Among the six measurements Chin-Nose, Glabella- Subnasion, Pupil-Stomion and anterior nasal Spine-Menton were closely associated between dentulous and edentulous subjects both at rest and at occlusion. Among all facial and cephalometric measurement the facial parameter of Pupil- Stomion illustrates the least deviation in edentulous (1.318) and dentulous (1.381) subjects at rest, whereas anterior nasal Spine-Menton displays least deviation in edentulous (2.751) and dentulous (1.224) subjects at occlusion.

The average facial measurements in dentulous subjects were more than measurements in edentulous subjects and among various facial measurements, Pupil-Stomion and anterior nasal Spine-Menton distance can be used clinically as a guide to verify vertical dimension of occlusion.

Brar A, Mattoo KA, Singh Y, Singh M, Khurana PRS, Singh M. Clinical Reliability of Different Facial Measurements in Determining Vertical Dimension of Occlusion in Dentulous and Edentulous Subjects. Int J Prosthodont Restor Dent 2014;4(3):68-77.

The abutment teeth of removable partial dentures are susceptible to root surface caries and secondary caries, and such caries sometimes result in crown destruction. In particular, in aged patients, this risk increases due to age-associated gingival recession, periodontal disease, decreased amount of saliva, and inadequate brushing caused by decreased finger motor function. Fluoride-releasing materials may prevent such caries. In this study, we evaluated the amounts of fluoride release from various fluoride-releasing cements based on the amount of fluoride release into artificial saliva.

In this study, the following three types of cement were used: Vitremer 2 Paste (3M Health Care: V2 hereafter) and Fuji Luting EX (GC: EX hereafter) as resin-modified glass-ionomer cements, and Clearfil SA Luting (Kuraray Medical: SA hereafter) as a fluoride-containing adhesive resin cement. Using the method indicated by the manufactures, 5 samples (diameter, 8 mm; thickness, 2 mm) for each type of cement were prepared. The samples were immersed in artificial saliva (5 ml) and left at room temperature. The artificial saliva used for immersion was replaced every 24 hours until 14 days after the initiation of immersion and every 48 hours thereafter until after 30 days. Fluoride release was measured in the immersion solution using a combination fluoride ion-selective electrode connected to an ion analyzer. For statistical analysis, one-way analysis of variance and the Bonferroni test were performed to compare the amount of fluoride ion release among the groups (? = 0.05).

The cumulative amount of fluoride ion release 30 days after the initiation of immersion was the highest for V2 (363.6 ± 87.1 μg/mm²), followed in order by EX (115.6 ± 7.9 μg/mm²) and SA (57.4 ± 23.9 μg/mm²). Significant differences were observed even from 1 day after the initiation of immersion between V2 and EX as well as SA. Concerning daily changes, the amount of fluoride ion release after 1 day was the highest for each type of cement; it was the highest for V2 (89.8 ± 13.5 μg/mm²), followed by SA (35.9 ± 8.3 μg/mm²) and EX (34.3 ± 3.2 μg/mm²). The amount of release gradually decreased after 2 days or more. Significant differences were observed from 1 day after the initiation of immersion between V2 and EX as well as SA. A significant difference between EX and SA was present from 2 until 4 days after the initiation of immersion.

V2 as a resin-modified glass-ionomer cement showed the highest amount of fluoride release, indicating continuous sustained fluoride release.

Ogami K, Yokomoto M, Koike T, Ueda T, Tomura K, Sakurai K. Differences in the Amount of Fluoride Release among Fluoride-Releasing Cements. Int J Prosthodont Restor Dent 2014;4(3):78-81.

The accuracy of an impression remains critical factor in achieving passive fit of an implant framework. The accuracy of the master cast would depend on the type of impression material, the implant impression technique and accuracy of die material. The different impression techniques advocated in the literature for implant impressions include direct (open tray) and indirect (closed tray) techniques. Direct technique use square impression copings that are picked up in the impressions which were used in this study.

To evaluate the accuracy of direct impression made with resin splinted and bis-GMA splinted open-tray impression coping. Thus to compare the accuracy of impressions obtained using different splinting materials.

A wax mandibular reference model was fabricated and four implants were placed in the mandibular anterior region using surveyor and acrylized with clear heat cure acrylic resin using injection molding technique. Spaced primary cast was fabricated with a uniform thickness of space about 2 mm. Ten custom trays were fabricated using the light curable resin sheets. Medium body polyether impression material was used. Pentamix was used to get a uniform mix. These trays were randomly divided among the two groups, with five trays in each group. Impression techniques were divided into two groups namely:

  Group A - direct impression technique with open tray impression copings splinted with autopolymerizing acrylic resin (GC pattern resin), group B - direct impression technique with open tray impression copings splinted with Protemp TM4 (bis- GMA) syringable temporisation material. Thus, final impressions were made. Total of 10 master casts were fabricated. Evaluation of casts using Dynascope-Vision engineering, Tesa Microhite 2D and coordinate measuring machine were used.

Statistical comparisons were made using ANOVA test and post-hoc test. Same amount of deviation values obtained with resin splinted and bis-GMA splinted impression copings. The difference in the values might be because of the variation in the rigidity of the materials used.

Both the splinting material exhibit similar accuracy in impression, so bis-GMA can be used, which is easy to handle, less time consuming, less technique sensitive, rigid and readily available material in clinics, instead of resin splinted material which is technique sensitive, more time consuming and cumbersome.

Selvaraj S, Mohan J, Simon P, Dorairaj J. Comparison of Accuracy of Direct Implant Impression Technique using Different Splinting Materials. Int J Prosthodont Restor Dent 2014;4(3):82-89.

Shambharkar VI. Technique to fabricate a Hollow facial Prosthesis for Lateral Midfacial Defect. Int J Prosthodont Restor Dent 2014;4(3):90-95.

This article presents a novel case report about the use of PRF as an autogenous, cost-effective and resorbable internal matrix prior to placement of MTA as an apical barrier.

Bansode PV, Pathak S, Wavdhane M, Khedgikar S. Apexification of Immature Necrotic Tooth with MTA using Platelet Rich Fibrin as an Internal Matrix. Int J Prosthodont Restor Dent 2014;4(3):96-99.