Evaluation of colour stability of provisional restorative materials exposed to different mouth rinses at varying time intervals: an in vitro study.

The most important factor affecting esthetics is colour. Whether a definitive prosthesis or a provisional restoration, maintenance of esthetics is of prime concern along with restoration of function. Colour stability of provisional prosthesis is affected by various factors and various studies are documented in the literature on this. The purpose of this study was to evaluate the colour stability of provisional restorative materials exposed to different mouth rinses at varying time intervals. 120 discs, each of self cure tooth moulding material, Protemp 4 and Revotek LC were prepared and immersed in two mouth rinses, hexidine and periogard and evaluated for their colour stability after 1 week, 1 and 3 months. The data obtained was statistically analysed using ANOVA and Tukey's post hoc analysis. The results indicate that there is a significant difference in the colour variation of various materials in two different mouth rinses at different time intervals. Revotek LC was found to be the most colour stable material and periogard had the least staining potential at varying time intervals.

Prosthetic Rehabilitation of a Patient with Congenitally Deformed Ears.

Treacher Collins syndrome is a rare autosomal dominant congenital disorder characterized by craniofacial deformities and is found in about 1 in 50,000 births. This is a bilaterally symmetrical abnormalities derived from the first and second brachial arches and the nasal placode. Unfortunately, many of the new surgical techniques are extensive and compromise the patient's quality of life, not only function and esthetics but also the psychological status of the patient. These problems require prompt rehabilitation with surgery or prosthetic rehabilitation. This article presents a procedure in the basic fabrication of a prosthetic ear by a three-piece die technique.

Assessment of occlusion changes during laboratory phase of relining: An in vitro study.

AIM: Assessment of occlusion changes during laboratory phase of relining is essential to evaluate the occlusal discrepancies that could get incorporated in the denture with the use of different relining materials. Since the long term stability and functional success of the denture is heavily influenced by occlusion, an In-vitro study to assess these changes after relining is warranted. The aim of the study is to evaluate the changes in occlusion during laboratory phase of relining procedure. SETTINGS AND DESIGN: This is an in vitro study with a total of 30 specimen. MATERIALS AND METHODOLOGY: A total of 30 maxillary standardized dentures were fabricated after mounting on a semi adjustable articulator. These samples will be divided into three groups based on the relining material used (Autopolymerizing resin, Heat-cure resin, Tissue conditioner). The vertical dimension, Centric contact points and eccentric contact points were measured before and after relining. STATISTICAL ANALYSIS USED: The variables were tested to see if they had a normal distribution using the Shapiro-Wilk test. Parametric distribution was seen for ECP leading to further comparison using one way analysis of variance (ANOVA). Non-parametric distribution was found while testing the VD, CCP leading to adoption of Kruskal-wallis test for comparison of groups. Dunn Bonferroni test was done for VD since results were significant. RESULTS: The results of this in-vitro study showed statistically significant difference with respect to change in vertical dimension in all groups pre and post relining (P = 0.005). The centric contact points showed lesser variation in position when comparing the pre to the post relining phase with the use of autopolymerising resins, whereas heat cure resins and tissue conditioners showed statistically significant difference in the centric point contacts post relining. No statistically significant changes were seen in eccentric occlusion post relining in all groups. Tissue conditioners showed minimum mean changes in eccentric contacts. CONCLUSION: Within the limitations of this study, the use of autopolymerising resins depicted the most stable results with respect to occlusion, for relining of dentures.

A comparative evaluation of application techniques of a paint-on die spacer in grooves: an in vitro study.

The use of paint-on die spacer to improve the seating of casting has become quite popular in the recent years. The generally accepted range of paint-on die spacer is approximately 20-40 µm, which suggests a range of tolerance. The painting of the retentive grooves with die spacer has always been a subject of debate. The primary purpose of this study was to determine if there was a tendency for the paint-on die spacer to accumulate in grooves of tooth preparation in sufficient thickness to exceed this accepted range of tolerance when applied using two different techniques. Eight die stone blocks with three grooves each were prepared. Half the samples were painted in unidirectional method and the other halves were painted using the haphazard method of application. The thickness of the die spacer was measured at different positions using 200× magnification and the mean and standard deviations were calculated. On analysis it was seen that the thickness of the paint-on die spacer in grooves was in the range of 20-40 µm for unidirectional method of application, whereas in haphazard method of application the thickness of the paint-on die spacer was in the range of 28-132 µm. From the above study it was concluded that the method of application influenced the thickness of the paint-on die spacer. The recommended thickness of the die spacer was achieved on unidirectional method of application.

Comparative Evaluation of Dimensional Accuracy and Tensile Strength of a Type IV Gypsum Using Microwave and Air Drying Methods.

To evaluate dimensional accuracy and tensile strength of a type IV gypsum product, at different time intervals, dried in air or a microwave oven. Eighty specimens prepared from a cylindrical mould were used for measuring tensile strength (group A). Twenty specimens from a master die mould were used for determining dimensional accuracy (group B). In group A, 40 specimens were dried in open air at room temperature (A1). The other 40 were removed after 30 min and air dried for 20 min. These were subjected to microwave oven drying for 5 min (A2). Ten specimens each were tested under diametral compression at each of the following time periods: 1, 2, 4 and 24 h after drying. In group B, ten specimens were dried in open air at room temperature (B1). Ten specimens were removed from the mould after 30 min and air dried for 20 min. These were then dried in a microwave oven for 5 min (B2). The data was statistically analyzed using students unpaired "t" test. At all time intervals, diametral tensile strength (DTS) values for specimens dried in microwave oven were significantly higher than for those dried in open air. There were no significant differences between the dimensional accuracy of the two groups. In this study, microwave oven drying had a positive effect on the DTS of a type IV gypsum and the microwave oven dried specimens were as accurate as the air dried specimens over the same time period.

A Comparison of Occlusal Schemes with Condylar Inclination and Anterior Guidance in Dentate Individuals.

PURPOSE: A Comparison of Occlusal Schemes with Condylar Inclination and Anterior Guidance in Dentate Individuals Methods. Twenty-six dentate patients between the ages of 18 to 30 of Indian Origin with canine-guided occlusion and 26 patients with group function occlusion were included in the study. The School of Articulator Munich (SAM) Axioquick system was used to assess the condylar guidance and eccentric tracings of the patients. For analyses, Student's t-test was used. For quantitative data, the mean and standard deviation were calculated. For all the statistical analysis the probability of type-I error of 0.05 was considered statistically significant. RESULTS: The mean condylar guidance for canine guided and group function occlusion on the right side was 38.4 ±12.7 and 30.5 ±12.5 and on the left side was 36.5 ±13.0 and 27.5±12.0 degrees with statistically significant difference [P value: 0.01]. The condylar guidance, incisal guidance, Bennett angle, protrusion, left lateral, right lateral, and left and right lateral angles were analyzed statistically between the two types of occlusions. The results showed a statistically significant difference between the two groups for all parameters except right condylar guidance. Furthermore, all the parameters were higher in canine guided occlusion group over group function occlusion. CONCLUSIONS: Within the study limitations, it was concluded that the condylar guidance was steeper in canine guided occlusion than in group function occlusion. The eccentric parameters were steeper in canine guided occlusion than in group function occlusion. CLINICAL SIGNIFICANCE: This study showcases that the condylar guidance might not play a major role in determining the occlusal scheme but, the incisal guidance determines the occlusal scheme predominantly in class 1 occlusion patients.

Complete rehabilitation of a patient with occlusal wear: a case report.

Prosthodontic management of occlusal wear problems is a demanding task on the part of the prosthodontist. Various factors such as vertical dimension of occlusion, centric relation, occlusal contact pattern, esthetics and phonetics need to be considered simultaneously for both anterior and posterior teeth during occlusal rehabilitation. This may be further complicated by existing restorations, pulpal exposure, missing teeth and tooth sensitivity. Different philosophies have been documented for rehabilitation of such cases and the choice of the treatment plan depends on the skill and experience of the clinician. This case report gives an overview of the different philosophies used for rehabilitation of such cases and a report which utilises Hobo's twin stage technique for the same.

A comparison between visual, digital photography and polarizing filter photography for shade selection.

AIM: There is an increased awareness for aesthetically pleasing restorations among patients in current practice. Due to variability in the natural tooth colour, shade selection becomes an intricate procedure. The aim of this study is to determine which of the three named methods is more accurate for shade selection in aesthetic dentistry. MATERIALS AND METHODS: Two VITAPAN classical shade guides were used for this study. Nine shades were selected from the first shade guide (A1, A2, A3.5, B1, B2, B3, C1, C2, C3) and the number was concealed. Ten selected participants were asked to identify each concealed shade with the second shade guide. Canon 5D camera with ISO 200, shutter speed 1/100 sec, F22 was used for capturing images of the second shade guide. Photoshop CS3 Software was used for developing the digital shade guide. The participants were asked to match the shades from the first shade guide with the prepared digital shade guide. The third photographic shade guide was prepared using a polarised filter on the Canon 5D camera with the same settings. The participants were asked to match shades with the prepared photographic shade guide. RESULTS: Total observations made during the study were 270. Cross table statistical analysis (Chi-square test) done using SPSS 20.0 showed statistically significant difference between conventional and digital photography (P = 0.049). Analysis between digital photography and polarizing filter photography did not reveal a significant association (P = 0.181). CONCLUSION: Digital photographic method was most accurate among the three shade selection methods. It can be used to obtain aesthetic results.

Prevalence of low back pain and carpal tunnel syndrome among dental practitioners in Dakshina Kannada and Coorg District.

CONTEXT: Dental practitioners who usually have to work for long durations in a particular fixed posture are more prone to musculoskeletal disorders (MSDs), particularly those involving the hand and wrist and also of the lower back. AIMS: To study the prevalence of carpal tunnel syndrome (CTS) and low back pain (LBP) among dental practitioners and to correlate the symptoms with the duration of practice. SUBJECTS AND METHODS: A closed-end questionnaire was distributed to 100 dental practitioners from Dakshina Kannada and Coorg districts of Karnataka, India. STATISTICAL ANALYSIS USED: Analyses were carried out using Chi-square test and Fisher's exact test. RESULTS: The study found that 86% of the total population of dentists practicing for more than 5 years showed symptoms of CTS and 54.0% experienced LBP. CONCLUSION: Symptoms of MSDs related to hands, wrists, and low back is widely prevalent among the dentists, which severely impact their work efficiency. Precautionary measures early in the clinical practice such as proper ergonomics in the operating field and few strengthening exercises as described in this study can reduce the onset and progression of the symptoms.

The Release of Elements from the Base Metal Alloys in a Protein Containing Biologic Environments and Artificial Saliva - An Invitro Study.

INTRODUCTION: It has been reported that protein containing solutions can accelerate the release of elements from the base metal alloys. AIM: This study aims to determine whether the solution in which an alloy is submerged and the exposure time have any effect on the amount of release of elements from the Ni-Cr and Co-Cr alloys. MATERIAL AND METHODS: A total of 126 specimens were made from the Ni-Cr alloy and 42 specimens were made from Co-Cr alloy in the form of 5mm diameter discs, 2mm in thickness. Dissolution experiments were carried out in Bovine Serum Albumin (BSA) and artificial saliva for a period of seven weeks and atomic absorption spectrophotometer was used for elemental analysis. STATISTICAL ANALYSIS: T-test was done to correlate the difference of elemental release from both BSA and artificial saliva. ANOVA test was done to compare the release at different time intervals and to compare the release of elements at different time intervals within a particular solution. TUKEY HSD test was done for comparison between the elements in a particular solution. RESULTS: The results showed that the elemental release was seen in both the solutions with a significant increase of release in BSA. The release of elements from the Ni-Cr alloy showed the predominant release of Cr. CONCLUSION: The protein containing solution showed maximum release of elements from Ni-Cr and Co-Cr alloys. The elements that released from the alloys never reached their threshold for toxic effects. Hence these alloys can be safely used in fabrication of metal restorations without any ill effects.

To Evaluate & Compare Retention of Complete Cast Crown in Natural Teeth Using Different Auxiliary Retentive Features with Two Different Crown Heights - An In Vitro Study.

BACKGROUND & OBJECTIVES: To evaluate the retention of complete cast crowns in teeth with adequate and inadequate crown height and to evaluate the effects of auxiliary retentive features on retention form complete cast crowns. MATERIALS AND METHODS: Sixty freshly extracted human premolars. They were divided into 2 major groups depending upon the height of the teeth after the preparation. Group1 (H1): prepared teeth with constant height of 3.5 mm and Group 2 (H2): prepared teeth with constant height of 2.5 mm. Each group is further subdivided into 3 subgroups, depending upon the retentive features incorporated. First sub group were prepared conventionally, second sub group with proximal grooves and third subgroups with proximal boxes preparation. Castings produced in Nickel chromium alloy were cemented with glass ionomer cement and the cemented castings were subjected to tensional forces required to dislodge each cemented casting from its preparation and used for comparison of retentive quality. The data obtained were statistically analyzed using Oneway ANOVA test. RESULTS: The results showed there was statistically significant difference between adequate (H1) and inadequate (H2) group and increase in retention when there was incorporation of retentive features compared to conventional preparations. Incorporation of retentive grooves was statistically significant compared to retention obtained by boxes. Results also showed there was no statistically significant difference between long conventional and short groove. CONCLUSION: Complete cast crowns on teeth with adequate crown height exhibited greater retention than with inadequate crown height. Proximal grooves provided greater amount of retention when compared with proximal boxes.

Evaluation and comparison of high-level microwave oven disinfection with chemical disinfection of dental gypsum casts.

BACKGROUND: The aim of this study was to evaluate and compare microwave disinfection with chemical disinfection of dental gypsum casts. MATERIALS AND METHODS: A total of 120 casts were prepared from a silicone mold using Type III dental stone. Of the 120 casts, 60 casts were contaminated with 1 ml suspension of Staphylococcus aureus and 60 casts were contaminated with 1 ml suspension of Pseudomonas aeruginosa. Then, the casts were disinfected with microwave irradiation and chemical disinfection using the microwave oven and 0.5% sodium hypochlorite. Bacteriologic procedures were performed; the cfu/ml for each cast was calculated as a weighted mean. The results were analyzed using Kruskal-Wallis test and Mann-Whitney test. RESULTS: The untreated casts showed Brain heart infusion broth counts of 106 log cfu/ml compared to irradiated and chemically disinfected casts, in which 105 log reduction of cfu/ml was seen. These results satisfied the requirements of current infection control guidelines for the dental laboratory. The results obtained for chemical disinfection were in equivalence with microwave disinfection. CONCLUSIONS: Within the limitation of this in vitro study, it was found that microwave disinfection of casts for 5 min at 900 W gives high-level disinfection that complies with the current infection control guidelines for the dental laboratory and microwave disinfection method is an effective and validated method as chemical disinfection. How to cite the article: Meghashri K, Kumar P, Prasad DK, Hegde R. Evaluation and comparison of high-level microwave oven disinfection with chemical disinfection of dental gypsum casts. J Int Oral Health 2014;6(3):56-60 .

Crestal bone preservation: a review of different approaches for successful implant therapy.

The level of bone crest surrounding the implant is of utmost significance to determine osseointegrated implant success, as preservation of marginal bone height is highly important for long-term dental implant survival. Various approaches have been described in the literature to prevent the crestal bone loss, including platform switching, non-submerged approach, scalloped implants, implant design modifications, progressive loading, immediate implant placement, etc. The purpose of this paper is to review all the possible methods to preserve the crestal bone, when each method should be used and their success rates in an attempt to address this complex problem of crestal bone resorption. "PubMed" and "Google Scholar" were used to find out any studies involving platform switching concept from 1990 up to 2009. Twenty-four studies involving methods for preservation of crestal bone were evaluated, which included 26% studies on platform switching, 22% on non-submerged approach, 17% on scalloped implants, 13% on progressive loading and 22% on immediate implant placement. Crestal bone preservation should be thought of starting from the design of the implant to be placed. The technique to be followed in a given case will depend upon the density of bone, force factors by the patient, bone volume and amount of soft tissues, etc. The best possible method or the combination of the methods should be used to preserve the crestal bone for the long-term success of the implants.

Role of colors in prosthodontics: application of color science in restorative dentistry.

Shade selection procedure depends on various factors including translucency, contour and surface texture. Tooth shade selection using a conventional means involves a high degree of subjectivity. Traditional shade guides are available that use several methods for quantifying shade. Technology-based systems provide with an advantage of natural looking restorations. They include RGB devices, colorimeters, spectrophotometers. The impact of the color science can be seen on various restorative materials ranging from ceramics to maxillofacial prosthetic materials.

Relation between oral stereognosis and masticatory efficiency in complete denture wearers: an in vivo study

Aim: The purpose of the present study was to evaluate the possible association between the oral stereognostic ability and masticatory efficiency at the time of denture insertion and after 6 months in complete denture wearers. Methods: Sixty edentulous patients were selected. The study was conducted in two parts. First, on the day of denture fit-in oral stereognostic ability test was conducted,followed by masticatory efficiency was carried out. The patients were recalled for check up after 6months and the same test was performed again. Data were tabulated and analyzed statistically by paired t-test and Pearson’s correlation coefficient. Results: There was weak correlation between oral stereognosis and masticatory efficiency. Many opinions have been presented in the literature in the past regarding oral stereognosis. The issue whether oral stereognosis also helps inpatients’ adaptation towards complete denture prosthesis is still ambiguous. No consensus has been reached. This study is further an attempt to understand the basic physiology of oral stereognosis and whether there is any possible relation between oral stereognosis and masticatory efficiency.Conclusions: Within the limitation of this study, it can be concluded that oral stereognostic ability improves with time, which might be due to adaptation to the denture. As adaptation towardsdenture improves masticatory efficiency improves as well. This study showed that there might bea weak association between oral stereognosis and masticatory efficiency.