Prosthodontics and Crown and Bridge

Purpose: To study the perception of online classes among the students of Government Dental College, Alappuzha, a rural tertiary care center and dental education institute in the state of Kerala, India, during COVID-19 pandemic. Materials and Methods: Questionnaire comprised of four domains: the first domain included socio-demographic details, the second domain was used to explore the details of online classes that happened during the pandemic, third domain was on the students’ perception of online classes and the fourth domain was on students’ likes and dislikes, suggestions and practices. Results: Media quality in various platforms and interaction potential with teachers were assessed. Even though understanding of the academic content was found good, perception of clinical/ pre-clinical learning was poor. Preferred duration of each session was 45 min to 1 h. Majority of students preferred regular classes and few suggested a blended mode beyond the COVID-19 pandemic. Sharing of reading materials in the form of multimedia slides or any other detailed reading format or recordings and a provision to store them for further reference too was preferred. Conclusions: Acceptable levels of e-learning experience were revealed by the study participants. In the Indian context, as a developing country, good network and internet coverage has to be ensured for students for the successful implementation of online education. E-learning can be adopted as an adjunct to traditional classroom learning after the prevailing pandemic.
Keywords: Blended learning, COVID-19, cross-sectional study, dental education, online class

Introduction: Flexural strength is one of the most important properties which determine the clinical success of dentures. Even though titanium oxide nanoparticles (nano-TiO 2) and zirconium oxide nanoparticles (nano-ZrO 2) are extensively used to modify the properties of polymethyl methacrylate (PMMA) resin, there is negligible documentation in the literature comparing these two. Aim: The aim of the study is to find out and compare the effect of incorporation of 1 weight % nano-TiO 2 and nano-ZrO 2 on the flexural strength of heat-activated PMMA resin. Materials and Methods: 1 weight % of TiO 2 and ZrO 2 nanoparticles were weighed using a digital weighing balance and mixed with PMMA resin powder using the geometric dilution method. Sixty "35 mm × 10 mm × 3 mm" rectangular-shaped specimens fabricated were divided into three different groups, each containing twenty samples each. The specimens were loaded to failure at a crosshead speed of 1 mm/min and with 500 N load cell in a Universal Instron Testing Machine, Model 3345. Flexural strength was registered by the machine with 0.001 MPa precision. Results: PMMA with nano-TiO 2 group had the maximum flexural strength, load at maximum flexure, and load at break followed by unreinforced PMMA and PMMA with nano-ZrO 2. Statistically significant difference was noted between the three groups (P < 0.001). Post hoc analysis using Tukey's post hoc test showed a statistically significant difference for all three pair-wise comparison. Conclusions: Within the limitations of this study, it can be concluded that nano-TiO2 greatly enhanced the flexural strength, load at maximum flexure load, and load at break of PMMA resin, whereas nano-ZrO2 significantly reduced these properties of PMMA.

Introduction: Awareness, attitude, and practice play a major role in containing any infectious disease. Coronavirus disease 2019 (COVID-19) has no definitive treatment or vaccines; hence, it is momentous to spread awareness regarding the prevention strategies. It is crucial for the government and concerned authorities to understand the students' perception and attitude in the time of the current pandemic. Aim: The aim of this study is to assess the level of awareness among the students of Government Dental College Alappuzha, a rural tertiary care center and Dental College in Kerala, India, regarding COVID-19 and their attitude toward the pandemic. Methodology: Questionnaire which included 21 items was used for the research. Observed data were coded, tabulated, and analyzed using IBM SPSS Statistics for Windows (Version 20.0. Armonk, NY, USA: IBM Corp.). The total awareness score calculated was 20. Comparison between gender (males/females) and study groups (preclinical students/clinical students) was made using the Chi-square test. Comparison of total awareness scores between study groups was made using independent t-test. Results: Most of the study participants across study groups regularly kept track of the latest news on COVID-19 and perceived it to be of moderate or very dangerous risk though they were quite optimistic of its control. About 96% of males and 82% of females felt it is necessary to get mental health help if one panics in lieu of the pandemic situation. The mean total awareness score (out of 20) was 15.16 ± 1.81. There was no significant difference in total awareness score based on gender (15.23 ± 2.24 for males and 15.15 ± 1.71 for females) and also among the category of students (14.88 ± 1.94 for preclinical students and 15.35 ± 1.69 among clinical students). Conclusions: Attempts should be made for increasing the awareness regarding the preferred method of hand hygiene, protocol for performing aerosol-generating procedures, and airborne infection isolation room.

Rehabilitation of completely edentulous state is achieved successfully by the fabrication of complete denture. When compared to
any other artificial organs used in human body, complete dentures
have received a high degree of success .But maxillary complete
dentures always have problems such as excessive tissue coverage,
altered taste and temperature sensations and reduction in oral
volume. These can be minimized to a certain extent by reducing
the coverage of the palate. Very often this is not attempted for
fear of loss of retention. Palate less complete denture is an alternative denture for upper edentulous patients in case of gagging,
large palatal torus and restoring the lost taste perception. Palate
less complete denture will restore the lost good tastes, comfort
and normal physiology of tissue to edentulous mouth and a good
alternative to full palatal coverage dentures [1]. The anatomy and
neuromuscular control of the tissues in and around the denture
bearing area helps in the retention of the complete maxillary denture even if the palatal coverage is reduced. Reduction of palatal
coverage reduced gagging tendency [2]. Palate less dentures in U
shape was more comfortable and effective like conventional dentures with complete palatal coverage [3]. The aims of the study
were to evaluate the effect of reduction of palatal coverage to
twenty percent of total area over denture retention and to compare and evaluate the subjective response of denture wearers to
dentures with conventional palatal coverage and reduced palatal coverage.

Background: Different pattern materials do not produce copings with satisfactory, marginal accuracy when used on stone dies at varying time intervals. Purpose: The purpose of this study was to evaluate and compare the vertical marginal accuracy of patterns formed from three materials, namely, thermoplastic resin, light cured wax and inlay casting wax at three-time intervals of 1, 12, and 24 h. Methodology: A master die (zirconia abutment mimicking a prepared permanent maxillary central incisor) and metal sleeve (direct metal laser sintering crown #11) were fabricated. A total of 30 stone dies were obtained from the master die. Ten patterns were made each from the three materials and stored off the die at room temperature. The vertical marginal gaps were measured using digital microscope at 1, 12, and 24 h after reseating with gentle finger pressure. Results: The results revealed a significant statistical difference in the marginal adaptation of three materials at all the three-time intervals. Light cured wax was found to be most accurate at all time intervals, followed by thermoplastic resin and inlay casting wax. Furthermore, there was a significant difference between all pairs of materials. The change in vertical marginal gap from 1 to 24 h between thermoplastic resin and light cured wax was not statistically significant. Conclusion: The marginal adaptation of all the three materials used, was well within the acceptable range of 25-70 µm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

Purpose
The study investigated the efficacy of three different laboratory techniques viz,
a. Posterior palatal strap
b. Polyaramid ber reinforcement, and
c. Glass ber reinforcement, in decreasing the posterior palatal shrinkage of denture bases that occur during processing.
Materials and methods
Forty identical maxillary edentulous casts were made from high strength dental stone using a standard exible rubber mold. An undersized
wax occlusal rim was made which was duplicated in heat cure acrylic resin to be used as a standard jig throughout the study to regulate the
volume of resin. Forty casts were divided into 4 groups; Group I – Control, Group II- posterior palatal strap , Group III- Kevlar 49 ber
reinforcement, and Group IV- Glass ber reinforcement. The casts for posterior palatal strap were altered by addition of box at the base of
the cast which served as a mechanical lock. In case of Kevlar ber and Glass ber reinforcement, pre-pregs were incorporated in the base
during the packing stage. Twenty-four hours after polymerization the bases on their casts were sectioned at the posterior border at predesignated points and evaluated for degree of adaptation using a high resolution microscope.
Results and Conclusion
Statistical analysis was performed using analysis of variance followed by 95% condence interval test. The maximum gap was noted in mid
palatine region (0.132mm) followed by maxillary tuberosity region (0.005mm) in control group. There was no measurable gap between the
cast and denture base in any of the three different laboratory techniques compared. The study concluded that the ber reinforcement
technique was simply the best and most efficient when compared with the other techniques.

Background: Prosthesis misfit plays an important role in complications such as occlusal and abutment screw loosening and fracture in implant restorations. Reproducing the intraoral relationship of implants through impression procedures is the first step in achieving an accurate, passively fitting prosthesis to ensure maximum accuracy. Hence, splinting of multiple implants with most accurate material may be a valid option. Context: The results of splinting multiple implants are always inconsistent, and there is limited literature available to compare the accuracy of impression techniques as well as materials. In such situation, more and more studies have to be done to prove the efficacy and accuracy of each splinting materials. Aim: The aim of the study was to evaluate the positional accuracy in multiple implants using acrylic resin, pattern resin, flowable composite, and bite registration paste. Subjects and Methods: An acrylic resin model was fabricated into which four implant analogs placed. The copings attached were splinted with dental floss onto which acrylic resin was added, which was sectioned and rewelded (Group A). Similarly, pattern resin, flowable composite, and bite registration material were added which were considered as Group B, C, and D, respectively. Impressions were made in vinyl polysiloxane and analogs were attached. The casts retrieved from each group were analysed for the positional accuracy of implants. Statistical Analysis: One-way ANOVA was done to analyze the significant difference between the four implant analogs of each group with the master model. The confidence interval was also calculated to assess the accuracy. Results: It was observed that all materials are equally effective for the accurate reproduction of implant positions. There was no significant difference between the centroids of implant analogues of master model and the mean of interimplant distance 1 and 2, 1 and 4, 3 and 4 and 2 and 4 in each group. The P-values were >0.05. The accuracy of splinting materials were analysed and it showed that splinting with flowable composite (Group C) as well as bite registration paste were in par with the conventionally used materials like pattern resin and acrylic resin. Conclusions: Results showed that flowable composite as well as bite registration material can be recommended as splinting material of choice for multiple implant cases, as these exhibited similar results like other groups (pattern resin and acrylic resin) which are conventionally used.

Background and aim: Denture adhesives augment the retention and stability of the complete denture. The included studies have not directly compared tensile bond strength between zinc and zinc-free denture adhesives. This study compared the tensile bond strength of zinc-containing and zinc-free denture adhesives on different denture base resin materials at various intervals. Material and methods: Four groups of denture base resin materials (Acralyn H, Lucitone199-DB1, SR Ivocap-DB2, Polytray-DB3) were fabricated using different polymerization techniques. Each group had ten specimens. The control group consisted of resin cylinders coated with artificial saliva, while the test groups had denture adhesive applied between the test and control cylinders. Tensile bond strength was measured using a universal testing machine. Results:  The tensile bond strength values of Fixodent with DBI &DB3 and DB2 &DB3 at 5 min (P < 0.01), 3 hours
(P < 0.01), and 6 hours (P < 0.061 and P < 0.020) alongside with DB1 & DB2, DBI & DB3, and DB2 & DB3 at 12
hours (P < 0.01) were found to be statistically significant. The tensile bond strengths variations of Fittydent with
DB1 & DB3 and DB2 & DB3 at 3 hours (P =0.013, P =0.012) and 6 hours (P < 0.01), and DB2 & DB3 at 12 hours
(P=0.015), was statistically significant at 0.05 level.

The marginal integrity of a restoration depends on the ability of impression material to accurately record the finish lines, which in turn will assure marginal adaptation and restoration aesthetics. To reveal the subgingival finish lines of preparation and to create enough room for the impression material, the gingiva must retracted vertically and horizontally be laterally. The most common and widely used method of gingival retraction uses a cord system for gingival displacement. Due to the technique dependence of gingival displacement with cord, products like expasyl paste and magic foam gel were developed. Thus the primary objective of this study was to determine the amount of gingival retraction achieved in width and depth using impregnated stayput retraction cord compared to magic foam gel and expasyl paste measured in micrometers using stereomicroscope under 10X resolution of the cast obtained before and after retraction which was sliced buccolingually to obtain a three millimetre specimen. Secondary objective was to assess presence or absence of gingival bleeding in the sulcus after retracting all three agents and to determine time taken for placement. Null hypothesis was there is no significant difference in the width and depth of gingival sulcus retracted in fixed prosthodontic treatment using impregnated stay put cord compared to magic foam gel and expasyl paste gingival displacement systems. Results
revealed that the null hypothesis was ruled out. Expasyl paste caused the greatest horizontal retraction.The largest vertical retraction was obtained by the impregnated stayput cord. The best hemostatic effect was shown by the magic foam gel retraction system. Applying Expasyl paste to the sulcus required less time.

BACKGROUND AND OBJECTIVES: The comparison of crestal bone loss in relation to implants placed using conventional drilling osteotomy method and using bone expansion screws in maxillary region. METHODS: The crestal bone loss was measured after implant placement and after a period of six months, and the results analyzed. Equal number of male and female patients of comparable age group who opted implant treatment were selected. RESULTS AND DISCUSSION: After a period of six months of implant placement, a mean value of 1.37 mm of crestal bone loss was noticed for implants placed using conventional osteotomy method while a mean of 0.73 was noticed in relation to implants placed using expansion screws. CONCLUSION: The implants placed using bone expansion screws show less crestal bone loss compared to implants placed using conventional osteotomy method in maxillary edentulous ridge having less than ideal bone width. It infers that the bone expansion method using expansion screws is more reliable and relatively noninvasive way of
implant bed preparation.

Treatment options for insufficient ridge morphology includes the use of short implants, vertical ridge augmentation procedures, or cantilever prostheses in completely edentulous patients. Due to the less predictable long-term prognosis associated with the above-mentioned procedures, the "All on 4" technique was proposed for the rehabilitation in edentulous jaws. The All on 4 treatment concept meets the patient requirements with an immediately loaded fixed prosthesis supported by four implants. This article depicts a clinical report in which an "All on 4" implant treatment is done with delayed loading protocol due to inadequate primary stability obtained.

Introduction: Awareness, attitude, and practice play a major role in containing any infectious disease. Coronavirus disease 2019 (COVID-19) has no definitive treatment or vaccines; hence, it is momentous to spread awareness regarding the prevention strategies. It is crucial for the government and concerned authorities to understand the students&#39; perception and attitude in the time of the current pandemic. Aim: The aim of this study is to assess the level of awareness among the students of Government Dental College Alappuzha, a rural tertiary care center and Dental College in Kerala, India, regarding COVID-19 and their attitude toward the pandemic. Methodology: Questionnaire which included 21 items was used for the research. Observed data were coded, tabulated, and analyzed using IBM SPSS Statistics for Windows (Version 20.0. Armonk, NY, USA: IBM Corp.). The total awareness score calculated was 20. Comparison between gender (males/females) and study groups (preclinical students/clinical students) was made using the Chi-square test. Comparison of total awareness scores between study groups was made using independent t-test. Results: Most of the study participants across study groups regularly kept track of the latest news on COVID-19 and perceived it to be of moderate or very dangerous risk though they were quite optimistic of its control. About 96% of males and 82% of females felt it is necessary to get mental health help if one panics in lieu of the pandemic situation. The mean total awareness score (out of 20) was 15.16 ± 1.81. There was no significant difference in total awareness score based on gender (15.23 ± 2.24 for males and 15.15 ± 1.71 for females) and also among the category of students (14.88 ± 1.94 for preclinical students and 15.35 ± 1.69 among clinical students). Conclusions: Attempts should be made for increasing the awareness regarding the preferred method of hand hygiene, protocol for performing aerosol-generating procedures, and airborne infection isolation room.

Purpose: To study the perception of online classes among the students of Government Dental College, Alappuzha, a rural tertiary care center and dental education institute in the state of Kerala, India, during COVID-19 pandemic. Materials and Methods: Questionnaire comprised of four domains: the first domain included socio-demographic details, the second domain was used to explore the details of online classes that happened during the pandemic, third domain was on the students’ perception of online classes and the fourth domain was on students’ likes and dislikes, suggestions and practices. Results: Media quality in various platforms and interaction potential with teachers were assessed. Even though understanding of the academic content was found good, perception of clinical/pre-clinical learning was poor. Preferred duration of each session was 45 min to 1 h. Majority of students preferred regular classes and few suggested a blended mode beyond the COVID-19 pandemic. Sharing of reading materials in the form of multimedia slides or any other detailed reading format or recordings and a provision to store them for further reference too was preferred. Conclusions: Acceptable levels of e-learning experience were revealed by the study participants. In the Indian context, as a developing country, good network and internet coverage has to be ensured for students for the successful implementation of online education. E-learning can be adopted as an adjunct to traditional classroom learning after the prevailing pandemic.

BACKGROUND AND OBJECTIVES: The comparison of crestal bone loss in relation to implants placed using conventional drilling osteotomy method and using bone expansion screws in maxillary region. METHODS: The crestal bone loss was measured after implant placement and after a period of six months, and the results analyzed. Equal number of male and female patients of comparable age group who opted implant treatment were selected.RESULTS AND DISCUSSION: After a period of six months of implant placement, a mean value of 1.37 mm of crestal bone loss was noticed for implants placed using conventional osteotomy method while a mean of 0.73 was noticed in relation to implants placed using expansion screws.CONCLUSION: The implants placed using bone expansion screws show less crestal bone loss compared to implants placed using conventional osteotomy method in maxillary edentulous ridge having less than ideal bone width. It infers that the bone expansion method using expansion screws is more reliab...

BACKGROUND AND OBJECTIVES: The comparison of crestal bone loss in relation to implants placed using conventional drilling osteotomy method and using bone expansion screws in maxillary region. METHODS: The crestal bone loss was measured after implant placement and after a period of six months, and the results analyzed. Equal number of male and female patients of comparable age group who opted implant treatment were selected. RESULTS AND DISCUSSION: After a period of six months of implant placement, a mean value of 1.37 mm of crestal bone loss was noticed for implants placed using conventional osteotomy method while a mean of 0.73 was noticed in relation to implants placed using expansion screws. CONCLUSION: The implants placed using bone expansion screws show less crestal bone loss compared to implants placed using conventional osteotomy method in maxillary edentulous ridge having less than ideal bone width. It infers that the bone expansion method using expansion screws is more reliable and relatively noninvasive way of implant bed preparation.