Aim: The aim of this study was to evaluate effectiveness of various polishing agents over surface roughness and topography of monolithic zirconia.
Materials and methods: Total 300 high-translucency LAVA PLUS Zirconia specimens (8 mm × 6 mm × 3 mm thickness) were prepared by sectioning blocks in the green stage. Sectioned blocks were sintered at 1450°C. Baseline surface roughness values of unpolished, ground blocks were measured using a profilometer. Samples were categorized into five groups, with each group having 60 samples—group I: White stone at 200,000 rpm with 40 strokes for 60 seconds and water coolant followed by polishing with diamond-impregnated silicone kit at 10,000 rpm with 40 strokes for 60 seconds (two steps); group II: Polishing done using diamond-impregnated silicone (two steps) at 10,000 rpm at 60 strokes for 90 seconds; group III: Polishing done using silicone paper containing silica carbide at 10,000 rpm at 40 strokes for 1 minute; group IV: Polishing done using silicone paper containing diamond at 10,000 rpm using 60 strokes in 90 seconds (two steps); group V: Polishing performed with silicone paper with diamond (two steps) at 8,000 rpm at 60 strokes for 90 seconds. Mean surface roughness (Ra) values were calculated. Collected data were analyzed using the one-way ANOVA and post hoc test using the SPSS software. One specimen per group was subjected to scanning electron microscopic analysis.
Results: Mean surface roughness values for all groups were found as 0.8, 0.7, 0.054, 0.002, and 0.01, respectively. No statistically significant difference was observed in polishing agents containing diamond (p = 0.7). Significant difference (p = 0.0) was observed between control groups compared to other groups. On SEM examination, surfaces polished with kits manufactured for Zirconia demonstrated greater smoothness compared to other porcelain polishers.
Conclusion: Polishing systems containing diamond particles were found to enhance the surface smoothness and reduce roughness of monolithic zirconia as compared to silica carbide. Polishing systems should be adhered to as per manufacturer due to abrasive particle size appropriateness.
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Sharma D, Jhingta P, Bathla SC. Challenges in Dental Implant Identification and Need of Universal Dental Implant Identification, Numbering, and Nomenclature System. Int J Prosthodont Restor Dent 2020; 10 (4):146-150.
Aim: As the number of dental implant patients and implant practitioners is increasing worldwide, implant(s) identification poses a daunting task in absence of detailed records. The purpose of this cross-sectional study was to survey the dental implant practitioners for methods used by them for record-keeping of dental implants and means of implant identification in cases where treatment records are inadequate. A unique Sharma Jhingta Implant identification, numbering, and nomenclature system is proposed to address the need for a universal implant documentation system.
Materials and methods: A cross-sectional study was planned. An electronic Google survey form was sent to 150 dentists with questions pertaining to study objectives. The questionnaire had two sections: the first section captured the demographic details of the respondents and the second section had questions on implant systems. It consisted of both open-ended and close-ended questions. Descriptive analysis was done and percentages were calculated for the responses.
Results: Responses of 104 implantologists were analyzed. Adin, Nobel Biocare, and Osstem were commonly used implant systems and the majority of clinicians were still using conventional methods of record-keeping namely patient treatment card and clinic record register (77.3% and 86.7%, respectively). Implantologists were facing difficulties in implant identification in previously treated patients and were either using their clinical judgment (72%) or professional colleagues’ opinion to identify implants. Implant identification software and apps were not used commonly by respondents.
Conclusion: There is a need for a universally accepted standardized method of implant identification numbering and nomenclature. Sharma Jhingta IINN system is an effective and easy to learn method for implant documentation.
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Sumanth K, Poovani S, Sonnahalli N. Evaluation of Effect of Fabrication Steps on Marginal Adaptation of CAD/CAM Zirconia-based Crowns in Comparison to Sintered PFM Crowns: An In Vitro Study. Int J Prosthodont Restor Dent 2020; 10 (4):151-157.
Aims: This study aimed to compare and evaluate the effect of fabrication steps on marginal adaptation of CAD/CAM zirconia-based crowns in comparison to sintered PFM crowns.
Materials and methods: Forty typhodont mandibular molar teeth were collected, a standardized protocol was followed for tooth preparation, after the tooth preparation 40 typhodont mandibular molar teeth were divided into two groups. Group I—20 CAD/CAM zirconia crowns and group II—20 sintered PFM restorations. Both the groups of crowns were analyzed for marginal fit during each step of fabrication, i.e., coping, after veneering, after cementation, and after thermomechanical loading. Each specimen was photographed using a stereomicroscope at 40× magnification to measure and evaluate the marginal discrepancy (MD). The results of a vertical MD of all tested fabrication stages were statistically analyzed using one-way analysis of variance (ANOVA), independent sample T-test.
Results: In this study, the marginal gap was increased after every tested stage for both the groups. The mean marginal adaptation values were least in each stage of fabrication for CAD/CAM zirconia-based crowns (coping—104.98 μm, veneering—108.46 μm, after cementation—110.11 μm, thermomechanical loading—116.41 μm) compared to sintered PFM crowns (coping—128.87 μm, veneering—132.41 μm, after cementation—135.51 μm, thermomechanical loading—136.9 μm).
Conclusion: The mean marginal adaptation values observed were all within the clinically acceptable range for both groups. Marginal adaptation of CAD/CAM zirconia-based crowns was better than sintered PFM crowns within each stage of fabrication.
Gopala Krishna Keerthi,
Srinivas R Pottem,
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Keerthi GK, Mahesh P, Pottem SR, Divya G. An In Vivo Study to Determine a Mathematical Formula to Relate Horizontal Condylar Guidance Angle Derived Clinically and Radiographically. Int J Prosthodont Restor Dent 2020; 10 (4):158-162.
Aim: Present study aims to derive the condylar guidance angle both clinically and radiographically and relate them by a mathematical formula.
Materials and methods: The study was conducted on 22 patients and both the clinically and radiographically derived condylar guidance values are used to derive a mathematical formula. Students t test and Pearson correlation test was done to find the difference between sagittal condylar guidance angle between protrusive interocclusal records and panoramic radiographs.
Results: The model of regression for right side was hypothesized and equation obtained was y = −0.080x + 23.49, while the model of regression for left side was hypothesized and equation obtained was y = −0.101x + 25.12, where y = dependent variable (condylar guidance value obtained by panoramic radiographs) and x = constant variable (condylar guidance value obtained by protrusive interocclusal records). The present study found that on the right side, there was a statistically significant (p = 0.019) difference in the mean protrusive interocclusal records (17.04 ± 6.61) and the panoramic radiographs (22.12 ± 7.2) whereas it was not significant (p = 0.101) on the left side.
Conclusion: From the observations, it can be concluded that the radiographically obtained condylar guidance angles were higher than the clinically derived angles.
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Bhattacharjee B, Bera RN, Bhatnagar A, Nagarajan N. Effect of Selective Serotonin Reuptake Inhibitors on Dental Implant Survival Rate in Patients with Neurological Disorders: A Systematic Review and Meta-analysis. Int J Prosthodont Restor Dent 2020; 10 (4):163-169.
Aim and objective: The aim and objective of the review was to evaluate how implant survival rate changes with the intake of selective serotonin reuptake inhibitors (SSRIs) in patients with neurological disorders.
Materials and methods: A systematic literature search was done in an electronic database (PubMed). In addition to this manual search of the references and gray literature was also done. Case reports, animal studies, literature reviews, and articles in non-English languages were not included. The Newcastle–Ottawa Scale was followed to assess the quality of the included studies. The meta-analysis was performed using statistical software Review Manager 5.03 and the outcome mean was measured by bivariate differential mean statistic with an intergroup estimate with a 95% confidence interval.
Results: A total of 344 articles were found in the PubMed database (n = 344) during the literature search. Five studies were included in the qualitative and quantitative analysis after removing duplicates and screening of titles and abstracts. Two studies were excluded by using eligibility criteria for the review. A total of 988 implants survived in the test group and 4,585 implants survived in the control group among all the studies (odds ratio: 0.41, 95% CI: 0.30–0.55). p < 0.00001 value from the analysis indicated a significant implant success rate in patients who were not taking any SSRI group of medications.
Conclusion: After evaluating the data from included studies, it can be concluded that patients taking the SSRI group of drugs for any neurological disorders had a higher chance of implant failures compared to the control group of patients.
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Sivaramakrishnan G, Alsobaiei M, Sridharan K, AlSulaiti F. Detection of Caries under Fixed Prosthodontic Restorations Using Cone-beam CT: A Meta-analysis. Int J Prosthodont Restor Dent 2020; 10 (4):170-175.
Aim: Secondary caries is the most common cause of failure of fixed prosthodontic restorations and radiography is often depended upon for the detection of caries under these restorations. Current radiographic techniques are specific, but they lack sensitivity. The inherent limitations in two-dimensional radiography led to the development of computed tomographic imaging techniques. Hence, this review aims to compile the available evidence on the utility of cone-beam computed tomography (CBCT) for detecting caries under fixed restorations.
Materials and methods: Electronic databases were screened for eligible studies using an appropriate search strategy. Full-texts were obtained and necessary data were extracted. The risk of bias of included studies was assessed using New Castle Ottawa scale. The mean gray values obtained on CBCT were recorded on a Forest Plot using RevMan 5 in Non-Cochrane mode. Mean difference with 95% confidence interval was used as the effect estimate of the mean gray values. Heterogeneity was assessed using Chi-square and I2 tests
Results: Three studies were included. Although there was significant heterogeneity between the studies as observed using the I2 values, a statistically significant difference in mean gray values between caries and dentin was observed when CBCT was used under lithium disilicate, zirconia, and metal-ceramic restorations. This indicates that caries can be diagnosed with accuracy under these restorations without the need for removing the restoration. The problem of metal artifacts in CBCT can be reduced if the field of view is small.
Conclusion: The results seem to indicate considering CBCT as a possible option if secondary caries is suspected, and in patients with high caries risk. If appropriately used with clinical judgment in high caries risk patients, a possible tooth loss could be prevented.
Aim: This technique aim to present a calculation-free method using Adobe Photoshop to apply the principles of facially driven smiles and to generate a wax-up based on measurements obtained from the final smile design.
Background: The lack of quantifiable measurements and the subsequent unrealistic expectations that develop can limit the use of virtual smile design or augmented reality applications. Developing a standardized measurement method that guides the laboratory wax-up after virtual smile design may solve this problem and allow many clinicians to utilize it in their day-to-day practice.
Technique: This technique article presents an efficient method of utilizing Adobe Photoshop software to create a facially driven smile design, to gather quantifiable measurements, and to fabricate a wax-up based on the digital design.
Conclusion: This technique allows the restorative dentist to achieve more predictable esthetic results and provides the laboratory technician with quantifiable measurements that they can use to bring the vision of the dentist to life.
Aim and objective: The purpose of this prototype model was to provide a novel and accessible facebow transfer.
Background: The practical application of this technique helps overcome the drawbacks of conventional facebow in providing accurate parallelism and precise midline orientation.
Technique: A MEMS-based three-axis gyroscope sensor is used for three axis rotational measurement. The electrical output of the gyroscope is via microcontroller that is driven to the OLED screen through I2C serial communication. A precise facial midline was obtained by using adjustable laser module of 650 nm in the current developed system. This detachable assembly was mounted on the Hanau spring bow and was evaluated on two patients.
Conclusion: Incorporation of the Gyro sensor with the adjustable laser light indicator in Hanau spring bow achieved accurate orientation of the occlusal plane and also helps in precise midline positioning, thereby decreasing occlusal errors and increasing the precision of the facebow.
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Mendiratta T, Atwal H, Viswambaran M, Kumar D, Gopi A. Rapid Prototyping: A Key Tool for Digital Craniofacial Reconstruction. Int J Prosthodont Restor Dent 2020; 10 (4):184-188.
Cranioplasty is performed following a traumatic injury, infection, tumor, or after a previous brain surgery for surgical repair of a defect or deformity. Reconstruction of such large cranial defects with complex geometric shapes (frontal or involving supraorbital ridges) along with soft tissue loss is challenging to reconstruct. Fabrication of polymethylmethacrylate (PMMA) cranial implants by conventional methods of moulage and mold formation may be difficult when the patient has neuromuscular incoordination and when margins of the defect cannot be accurately detected. Three-dimensional anatomic models built by rapid prototyping (RP) can serve as templates for the fabrication of customized cranial prostheses for such cranial defects with high accuracy and precision. This paper aims to present and compare two different techniques of craniofacial reconstruction to restore form and function for large complex cranial defects. In the first case, the cranial implant was fabricated using the conventional method whereas in the second case RP was used to fabricate the prosthesis, which proved to be an accurate, time-efficient, convenient, and easy-to-use alternative with great adaptability to cranial vault defects. The RP technology nowadays plays a pivotal role in digital rehabilitation of large complex craniomaxillofacial defects especially when the patients have compromised neuromuscular coordination, which impedes the clinical step of impression making as the patient cannot maintain an upright posture of the head.